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This is a continuation of application Ser. No. 08/512,857, filed Aug. 9, 1995 now abandoned. BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to an apparatus for recording and reproducing video signals and audio signals on and from a magnetic tape in adjacent tracks which are inclined relative to the longitudinal direction of the tape, the apparatus comprising a drum-shaped scanning device around which the magnetic tape is wrapped along a helical path during recording and reproduction and which comprises a rotationally drivable head support for carrying a plurality of magnetic heads, the head support carrying one head pair for the transmission of analog video signals at at least one given tape speed, this one head pair comprising two diagonally arranged magnetic heads having head gaps with oppositely oriented azimuth angles for scanning the magnetic tape along adjacent inclined tracks, and at least one further head pair for the transmission of analog audio signals at at least one given tape speed, this further head pair comprising two diagonally arranged magnetic heads having head gaps with oppositely oriented further azimuth angles for scanning the magnetic tape along further adjacent inclined tracks, the azimuth angles of the two magnetic heads of the one head pair being smaller than the further azimuth angles of the two magnetic heads of the further head pair, the apparatus further comprising a signal processing device for processing analog video signals and analog audio signals, this signal processing device being connected to the respective magnetic heads during the transmission of analog video signals and analog audio signals. The invention also relates to an apparatus for recording and/or reproducing video signals and audio signals on/from a magnetic tape in adjacent tracks which are inclined relative to the longitudinal direction of the tape, the apparatus comprising a drum-shaped scanning device around which the magnetic tape is wrapped along a helical path during the recording and reproduction of signals and which comprises a rotationally drivable head support for carrying a plurality of magnetic heads, the head support carrying one head pair for the transmission of information signals at at least one given tape speed, this one head pair comprising two diagonally arranged magnetic heads having head gaps with oppositely oriented azimuth angles for scanning the magnetic tape along adjacent inclined tracks, and at least one further head pair for the transmission of further information signals at at least one given tape speed, this further head pair comprising two diagonally arranged magnetic heads having head gaps with oppositely oriented further azimuth angles for scanning the magnetic tape along further adjacent inclined tracks, the azimuth angles of the two magnetic heads of the one head pair being smaller than the further azimuth angles of the two magnetic heads of the further head pair, the apparatus further comprising a signal processing device for processing the information signals and the further information signals, this signal processing device being connected to the respective magnetic heads during the transmission of information signals and further information signals. The invention further relates to a magnetic tape for cooperation with an apparatus of the type defined in the first paragraph, and with an apparatus of the type defined in the second paragraph, this tape having been provided with adjacent tracks which are inclined relative to the longitudinal direction of the tape. 2. Description of the Related Art An apparatus of the type defined in the first and second paragraphs has been marketed by, for example, Philips Electronics under the type designation VR 632, and is known therefrom. This known apparatus is a video recorder in accordance with the VHS standard for analog video signals in accordance with a PAL television standard. In this video recorder, the head support of the drum-shaped scanning device carries a first head pair comprising two diagonally disposed magnetic heads having head gaps with comparatively small oppositely oriented first azimuth angles of approximately +6° an -6°, a second head pair comprising two diagonally disposed magnetic heads having head gaps also with comparatively small oppositely oriented second azimuth angles of approximately +6° an -6°, and a further head pair comprising two diagonally disposed magnetic heads having head gaps with comparatively large oppositely oriented further azimuth angles of approximately +30° an -30°. With the known video recorder, it is possible to record and reproduce analog PAL video signals by means of the magnetic heads of the first head pair in comparatively wide first inclined tracks having a track width of approximately 48 μm while the magnetic tape is driven at a normal tape speed in a so-called Short-Play mode, to record and reproduce analog PAL video signals by means of the magnetic heads of the second head pair in comparatively narrow second inclined tracks having a track width of approximately 24 μm while the magnetic tape is driven at a reduced tape speed in a so-called Long-Play mode, and to record and reproduce analog frequency-modulated audio signals both in the Short-Play mode and in the Long-Play mode by means of the magnetic heads of the further head pair in comparatively narrow further inclined tracks having a track width of approximately 32 μm in the Short-Play mode and of approximately 24 μm in the Long-Play mode. During recording both in the Short-Play mode and in the Long-Play mode, the analog frequency-modulated audio signals are first recorded in the comparatively narrow further inclined tracks, recording being effected down to deeper lying areas of the magnetic tape, and after this, the analog PAL video signals are recorded on the magnetic tape in the comparatively wide first inclined tracks and in the comparatively narrow second inclined tracks, which is effected in less deep areas of the magnetic tape. As a result of the arrangement of the magnetic heads on the head support of the drum-shaped scanning device, the recording of analog video signals and analog frequency-modulated audio signals in the known apparatus is effected in such a manner that the comparatively narrow further inclined tracks, which are scanned by the magnetic heads of the further head pair in the Short-Play mode and in which the analog audio signals are recorded, are wholly overlapped by the comparatively wide first inclined tracks, which are scanned by the magnetic heads of the first head pair in the Short-Play mode and in which the analog video signals are recorded, and that the comparatively narrow further inclined tracks, which are scanned by the magnetic heads of the further head pair in the Long-Play mode and in which the analog frequency-modulated audio signals are recorded, are, in essence, also overlapped by the comparatively narrow second inclined tracks, which are scanned by the magnetic heads of the second head pair in the Long-Play mode and in which the analog video signals are recorded. Expressed in other words, this means that in the known apparatus, not only the magnetic heads of the further head pair and the magnetic heads of the first head pair scan mutually overlapping inclined tracks in the Short-Play mode but also the magnetic heads of the further head pair and the magnetic heads of the second head pair scan mutually overlapping inclined tracks in the Long-Play mode. This imposes the restriction that the known apparatus is only capable of recording and reproducing analog video signals and analog audio signals as explained above. As already stated, an apparatus of the type defined in the first and second paragraphs has been marketed by Philips Electronics under the type designation VR 632, and is known therefrom. The construction of this known apparatus has already been explained above. It is to be noted merely that this known apparatus is only capable of recording, and hence, storing and reproducing information signals in the form of analog PAL video signals and further information signals in the form of analog frequency-modulated audio signals on/from a magnetic tape. A magnetic tape of the type defined in the third paragraph is also generally known, for example, from the magnetic-tape-cassettes in accordance with the VHS standard which are currently marketed worldwide. SUMMARY OF THE INVENTION It is an object of the invention to remove the above-mentioned restriction of an apparatus of the type defined in the first paragraph and to improve such an apparatus of the type defined in the first paragraph in such a manner that, in addition to the transmission of analog video signals and analog audio signals, such an apparatus is also capable of recording and reproducing digital video signals and the associated digital audio signals using the same number of magnetic heads. According to the invention, this object is achieved in that the magnetic heads of the one head pair and the magnetic heads of the further head pair are arranged on the head support in such a relationship to one another that the magnetic heads of the one head pair and the magnetic heads of the further head pair scan adjacent interleaved inclined tracks at a given tape speed, in such a manner that, each time, an inclined track scanned by a magnetic head of one of these two head pairs is situated between two of the inclined tracks scanned by the magnetic heads of the other one of these two head pairs, and in that the gap lengths of the head gaps of the magnetic heads of the one head pair and of the further head pair are, at most, 0.40 μm, and in that the apparatus comprises a signal processing device for processing digital video signals and digital audio signals, this signal processing device being connected to the magnetic heads of the one head pair and of the further head pair during the recording and reproduction of such digital video signals and digital audio signals. In this way it is achieved that in an apparatus in accordance with the invention, while the magnetic tape is being driven with the given tape speed, the magnetic heads of the one head pair and the magnetic heads of the further head pair now scan four adjacent non-overlapping inclined tracks during each revolution of the head support. These four inclined tracks scanned by the four magnetic heads of both head pairs during each revolution provide an adequate storage capacity to allow a digital video signal and an associated digital audio signal to be stored with satisfactory quality. Since the gap lengths of the head gaps of the four magnetic heads of the two head pairs do not exceed 0.40 μm, this advantageously guarantees a faultless and good-quality recording and reproduction of digital video signals and digital audio signals. An apparatus in accordance with the invention has the advantage that it invariably enables analog video signals to be recorded in and reproduced from inclined tracks while the magnetic tape is driven at the given tape speed. Only the possibility of recording analog audio signals in inclined tracks is no longer available due to the small gap lengths of the magnetic heads of the further head pair, but this is not a meaningful restriction because, at any rate, a high-quality audio signal recording is guaranteed by the recording of digital audio signals in inclined tracks and, moreover, such apparatuses always also have provisions for the recording and reproduction of analog audio signals in/from a longitudinal audio track by means of a stationary magnetic audio head. In spite of the small gap lengths of the magnetic heads of the further head pair, an apparatus in accordance with the invention invariably enables analog audio signals to be reproduced from inclined tracks. Thus, an apparatus in accordance with the invention enables analog video signals to be recorded in and reproduced from inclined tracks and analog audio signals to be reproduced from inclined tracks and, in addition, enables digital video signals and digital audio signals to be recorded in and reproduced from inclined tracks without the number of magnetic heads being increased in comparison with a known apparatus which is only capable of recording analog video signals and analog audio signals in and reproducing them from inclined tracks. It is to be noted that the German Patent Specification DE 35 10 766 C2 discloses a video recorder which is suitable for recording and reproducing analog video signals and digital video signals in adjacent inclined tracks, but this known video recorder is not suited for reproducing audio signals from such inclined tracks because the rotationally drivable head support of this known video recorder does not carry any magnetic heads for the transmission of audio signals, whereas an apparatus in accordance with the invention is definitely suitable for this, in that the magnetic heads provided on the rotationally drivable head support for the reproduction of analog audio signals are also utilized for recording and reproducing digital video signals and digital audio signals, which are transmitted in mutually interleaved form. Furthermore, in the video recorder known from the German Patent Specification DE 35 10 766 C2, the analog video signals are recorded and reproduced in/from each inclined track by means of a head pair which scans each time one inclined track and whose magnetic heads scan one track half each. However, the head gaps of the two magnetic heads should then be aligned very exactly because, otherwise, excessive signal attenuations and even signal dropouts may occur during reproduction of the analog video signals. Such an exact alignment of the head gaps, however, is very difficulty and is therefore intricate and expensive. An apparatus in accordance with the invention does not have these problems. It is to be noted also that a digital video recorder system for recording and reproducing digital video signals and digital audio signals has been proposed, in which two pairs of magnetic heads arranged on a rotationally drivable head support scan four adjacent inclined tracks during one revolution of the head support. Each pair of magnetic heads then comprises one magnetic head having a head gap with a comparatively large azimuth angle of +20° and one magnetic head having a head gap with a comparatively large azimuth angle of -20°, the four magnetic heads of the two pairs of magnetic heads being arranged on the head support in such a relationship relative to one another that these four magnetic heads scan a track pattern of mutually interleaved inclined tracks, in which an inclined track to be scanned with a magnetic head having a head gap with an azimuth angle of -20° (or +20°) is situated between two inclined tracks to be scanned with a magnetic head having a head gap with an azimuth angle of +20° (and -20°, respectively). However, this known video recorder system enables exclusively digital video signals and digital audio signals to be recorded in inclined tracks and to be reproduced from these inclined tracks, whereas an additional transmission of analog video signals and analog audio signals from only two inclined track during each revolution of the magnetic heads by means of the same magnetic heads with which the digital video signals and digital audio signals are recorded and reproduced is not possible with the proposed known video recorder system, without at least losing one of the well-known advantages of analog video signal recording systems, such as the VHS system, i.e., the advantages of the so-called azimuth damping and of the continuous signal flow without the use of signal buffers. Thus, the special advantages of an apparatus in accordance with the invention are not obtained or attainable with the known video recorder system. The apparatus described in U.S. Pat. No. 5,412,515, corresponding to European Patent Specification EP-0,346,973 B1, also relates to the same field as the known video recorder system. Moreover, it is to be noted that European Patent Application EP-0,601,963 A2 discloses a system for recording and reproducing analog video and audio signals as well as digital video and audio signals. However, in this known system, recording and reproduction of the digital signals, i.e., the digital video and audio signals in interleaved form, is effected only with the magnetic heads provided for the recording and reproduction of these digital signals, for which reason it is necessary, in order to obtain a satisfactory transmission bandwidth, that during the recording and reproduction of digital signals, the magnetic heads are operated with a speed of rotation which is twice as high as that during the recording and reproduction of analog signals. Conversely, in an apparatus in accordance with the invention, apart from the magnetic heads provided for the recording and reproduction of analog video signals, the magnetic heads provided for the transmission of analog audio signals are additionally used for the recording and reproduction of digital video and audio signals, as a result of which the number tracks scanned per revolution of the magnetic heads is doubled and, consequently, the advantage is obtained that the speed of rotation of the magnetic heads during the recording and reproduction of digital video and audio signals need not be doubled in comparison with the speed of rotation of the magnetic heads during the recording and reproduction of analog video and audio signals. Moreover, European Patent Application EP-0,601,963 A2 does not give any details about the positioning of the rotationally drivable magnetic heads on a head support and the values of the gap lengths of the rotationally drivable magnetic heads. In an apparatus in accordance with the invention, it has proven to be advantageous if the magnetic heads of the one head pair and the magnetic heads of the further head pair are arranged on the head support in such a relationship to one another that, at the given tape speed, a magnetic head with a positive azimuth angle of the one head pair scans a track which, viewed in the tape transport direction, follows a track scanned by a magnetic head with a positive azimuth angle of the further head pair. Thus, it is achieved that there is only a slight difference between the relative position of the magnetic heads of the one head pair and the magnetic heads of the further head pair with respect to one another in an apparatus in accordance with the invention, and the relative position of the magnetic heads of the one head pair and the magnetic heads of the further head pair with respect to one another in a known apparatus in accordance with the VHS standard, so that a drum-shaped scanning device for an apparatus in accordance with the invention can be manufactured in the same way as the drum-shaped scanning device of a known apparatus in accordance with the VHS standard and, consequently, the same production technology can be used. In an apparatus in accordance with the invention, it has proven to be advantageous if the gap lengths of the head gaps of the magnetic heads of the one head pair and of the further head pair are 0.30 μm, at most. This is advantageous in view of a maximal bandwidth for the transmission of digital signals by means of these magnetic heads. In an apparatus in accordance with the invention, in which the head support carries a first head pair for the transmission of analog video signals at a normal tape speed, this first head pair comprising two diagonally arranged magnetic heads having head gaps with oppositely oriented first azimuth angles for scanning the magnetic tape along first adjacent inclined tracks, and a second head pair for the transmission of analog video signals at a reduced tape speed, this second head pair comprising two diagonally arranged magnetic heads having head gaps with oppositely oriented second azimuth angles for scanning the magnetic tape along second adjacent inclined tracks, and which carries a further head pair for the transmission of analog audio signals at at least one of the tape speeds, this further head pair comprising two diagonally arranged magnetic heads having head gaps with oppositely oriented further azimuth angles for scanning the magnetic tape along further adjacent inclined tracks, the first azimuth angles of the two magnetic heads of the first head pair and the second azimuth angles of the two magnetic heads of the second head pair being smaller than the further azimuth angles of the two magnetic heads of the further head pair, as is known from the afore-mentioned apparatus bearing the type designation VR 632, it has also proven to be advantageous if the magnetic heads of the second head pair and the magnetic heads of the further head pair are arranged on the head support in such a relationship to one another that the magnetic heads of the second head pair and the magnetic heads of the further head pair scan adjacent interleaved inclined tracks at a given tape speed, such that, each time, an inclined track scanned by a magnetic head of one of these two head pairs is situated between two of the inclined tracks scanned by the magnetic heads of the other one of these two head pairs, and the gap lengths of the head gaps of the magnetic heads of the second head pair and of the further head pair are, at most, 0.40 μm, and the apparatus comprises a signal processing device for processing digital video signals and digital audio signals, this signal processing device being connected to the magnetic heads of the second head pair and of the further head pair during the recording and reproduction of such digital video signals and digital audio signals. This is advantageous, in particular, because in such an apparatus, several recording and reproducing possibilities for analog video signals are available, recording and reproduction of analog video signals also being possible in special-feature modes in which a magnetic tape is driven with a tape speed which differs from the normal tape speed. In an apparatus in accordance with the invention, as defined in the preceding paragraph, it has also proven to be advantageous if the magnetic heads of the second head pair and the magnetic heads of the further head pair are arranged on the head support in such a relationship to one another that, at the given tape speed, a magnetic head with a positive azimuth angle of the second head pair scans a track which, viewed in the tape transport direction, follows a track scanned by a magnetic head with a positive azimuth angle of the further head pair. With such an apparatus in accordance with the invention, it is thus achieved that there is only a slight difference between the relative position of the magnetic heads of the second head pair and the magnetic heads of the further head pair with respect to one another in such an apparatus in accordance with the invention, and the relative position of the magnetic heads of the second head pair and the magnetic heads of the further head pair with respect to one another in a known apparatus in accordance with the VHS standard. It has then also proven to be advantageous if the gap lengths of the head gaps of the magnetic heads of the second head pair and of the further head pair are 0.30 μm, at most. This is advantageous in view of a maximal bandwidth for the transmission of digital signals by means of these magnetic heads. It is another object of the invention to construct an apparatus of the type defined in the second paragraph, such that digital video signals and digital audio signals can be recorded and digital video signals and digital audio signals can be reproduced in a simple manner by means which are known per se. To this end, an apparatus of the type defined in the second paragraph is characterized in that the magnetic heads of the one head pair and the magnetic heads of the further head pair are arranged on the head support in such a relationship to one another that the magnetic heads of the one head pair and the magnetic heads of the further head pair scan adjacent interleaved inclined tracks at a given tape speed, such that, each time, an inclined track scanned by a magnetic head of one of these two head pairs is situated between two of the inclined tracks scanned by the magnetic heads of the other one of these two head pairs, and in that the gap lengths of the head gaps of the magnetic heads of the one head pair and of the further head pair are, at most, 0.40 μm, and in that the apparatus comprises a signal processing device for processing digital video signals and digital audio signals, this signal processing device being connected to the magnetic heads of the one head pair and of the further head pair during the recording and reproduction of such digital video signals and digital audio signals. This is a simple way of realizing an apparatus by means of which digital video signals and digital audio signals can be recorded in inclined tracks. Moreover, this yields an apparatus which enables digital video signals and digital audio signals to be reproduced from the inclined tracks. A magnetic tape provided with a recording of digital video signals and digital audio signals in inclined tracks by means of such an apparatus in accordance with the invention can be used, for example, in an apparatus in accordance with the invention which is adapted to record and reproduce digital video signals and digital audio signals as well as to record and reproduce analog video signals and analog audio signals in inclined tracks, in order to reproduce the recorded digital video signals and digital audio signals from the inclined tracks by means of this apparatus. In such an apparatus in accordance with the invention, it has also proven to be advantageous if the magnetic heads of the one head pair and the magnetic heads of the further head pair are arranged on the head support in such a relationship to one another that at the at least one given tape speed a magnetic head with a positive azimuth angle of the one head pair scans a track which, viewed in the tape transport direction, follows a track scanned by a magnetic head with a positive azimuth angle of the further head pair. This has the afore-mentioned advantage that also with such an apparatus in accordance with the invention, a slight difference is obtained between the relative positions of the magnetic heads in an apparatus in accordance with the invention and a known apparatus in accordance with the VHS standard. In such an apparatus in accordance with the invention, it has also proven to be advantageous if the gap lengths of the head gaps of the magnetic heads of the one head pair and of the further head pair are 0.30 μm, at most. This has the afore-mentioned advantage that also with such an apparatus in accordance with the invention, a maximal bandwidth is obtained for the transmission of digital signals by means of these magnetic heads. A very important variant of such an apparatus in accordance with the invention, is that this apparatus is configured as an arrangement for manufacturing magnetic tapes with pre-recorded digital video signals and digital audio signals. Such an apparatus in accordance with the invention is configured only to record digital video signals and digital audio signals in inclined tracks in order to enable pre-recorded magnetic tapes to be manufactured with a high recording quality. According to the invention, a magnetic tape of the type defined in the third paragraph is characterized in that tracks groups which adjoin one another successively in the longitudinal direction of the tape, which are each of similar configuration, and which each comprise four successively adjacent tracks, have been provided on the magnetic tape, and of the four successively adjacent tracks of each track group, the first track contains a recording made with a magnetic head having a first azimuth angle and the second track contains a recording made with a magnetic head having a second azimuth angle, and the third track contains a recording made with a magnetic head having an azimuth angle opposite to the first azimuth angle, and the fourth track contains a recording made with a magnetic head having an azimuth angle opposite to the second azimuth angle. An advantageous variant of a magnetic tape in accordance with the invention is characterized in that the first track contains a recording made with a magnetic head having a positive first azimuth angle and the second track contains a recording made with a magnetic head having a positive second azimuth angle, and in that the first azimuth angle is larger than the second azimuth angle. Another advantageous variant of a magnetic tape in accordance with the invention is characterized in that the recordings contained in the four tracks of each track group have been made with magnetic heads whose azimuth angles correspond to the azimuth angles known from the VHS system. A further advantageous variant of a magnetic tape in accordance with the invention is characterised in that the first azimuth angle has a nominal value of 30° and the second azimuth angle has a nominal value of 6°. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described with reference to four exemplary embodiments of the invention which are shown in the drawings but to which the invention is not limited, in which: FIG. 1 shows, diagrammatically, a relevant part of a prior-art video recorder in accordance with the VHS standard, by means of which analog video signals in accordance with a PAL television standard and analog audio signals can be recorded and reproduced; FIG. 2 is a diagrammatically developed view showing the positions of the head gaps of magnetic heads on a rotationally drivable head support of a drum-shaped scanning device of the prior-art video recorder shown in FIG. 1; FIG. 3 shows a part of a first track pattern already recorded on a magnetic tape having tracks capable of being scanned by two head pairs of the prior-art video recorder in FIG. 1 in a so-called Short-Play mode in order to reproduce analog PAL video signals and analog audio signals, and a part of a second track pattern already recorded on a magnetic tape, whose tracks can be scanned by means of two head pairs of the prior-art video recorder in FIG. 1 in a so-called Long-Play mode in order to reproduce analog PAL video signals and analog audio signals; FIG. 4, in a way similar to FIG. 1, shows, diagrammatically, a part of a video recorder in accordance with a first embodiment of the invention, which is adapted to record and reproduce analog video signals in accordance with a PAL standard and analog audio signals, and to record and reproduce digital video signals and digital audio signals; FIG. 5 is a diagrammatically developed view showing the positions of the head gaps of magnetic heads on a rotationally drivable head support of a drum-shaped scanning device of the video recorder shown in FIG. 4; FIG. 6 shows a part of a track pattern already recorded on a magnetic tape, for example, by means of a video recorder as shown in FIG. 1, whose tracks can be scanned by means of one head pair of the video recorder in FIG. 4 in a so-called Short-Play mode in order to reproduce analog PAL video signals; FIG. 7 shows a part of a track pattern already recorded on a magnetic tape, for example, by means of a video recorder as shown in FIG. 1, having tracks capable of being scanned by two head pairs of the video recorder in FIG. 4 in a Short-Play mode in order to reproduce analog PAL video signals and analog audio signals; FIG. 8 shows a part of a track pattern already recorded on a magnetic tape, for example, by means of a video recorder as shown in FIG. 1, having tracks capable of being scanned by two head pairs of the video recorder in FIG. 4 in a Long-Play mode in order to reproduce analog PAL video signals; FIG. 9 shows a part of a track pattern on a magnetic tape having tracks capable of being scanned at a given tape speed by two head pairs of the video recorder in FIG. 4 in order to record and reproduce digital video signals and digital audio signals in a Short-Play mode; FIG. 10, similarly to FIGS. 2 and 5, is a diagrammatically developed view showing the positions of the head gaps of magnetic heads on a head support of a drum-shaped scanning device of a video recorder in accordance with a second embodiment of the invention, which is adapted to record and reproduce analog video signals in accordance with the NTSC standard and analog audio signals and to record and reproduce digital video signals and digital audio signals; FIG. 11 shows a part of a track pattern already recorded on a magnetic tape in a Short-Play mode, for example, by means of a prior-art video recorder, having tracks containing analog NTSC video signals and analog audio signals, these tracks capable of being scanned by two head pairs having head gaps as shown in FIG. 10, in order to reproduce analog NTSC video signals and analog audio signals in a Short-Play mode; FIG. 12 shows a part of a track pattern recorded on a magnetic tape, for example, by means of a prior-art video recorder, having tracks containing analog NTSC video signals and analog audio signals, these tracks capable of being scanned by two head pairs having head gaps as shown in FIG. 10, in order to reproduce analog NTSC video signals and analog audio signals in a Long-Play mode; FIG. 13 shows a part of a track pattern recorded on a magnetic tape in an extended-Long-Play mode, for example, by means of a prior-art video recorder, having tracks containing analog NTSC video signals and analog audio signals, these tracks capable of being scanned by two head pairs having head gaps as shown in FIG. 10, in order to reproduce analog NTSC video signals and analog audio signals in an extended-Long-Play mode; FIG. 14 shows a part of a track pattern on a magnetic tape having tracks capable of being scanned at a given tape speed by two head pairs having head gaps as shown in FIG. 10, in order to record and reproduce digital video signals and digital audio signals in a Short-Play mode; FIG. 15, in way similar to FIGS. 1 and 4, shows, diagrammatically, a part of a video recorder in accordance with a third embodiment of the invention, which is adapted to record and reproduce analog video signals in accordance with a PAL standard and analog audio signals, and to record and reproduce digital video signals and digital audio signals; FIG. 16, in a way similar to FIGS. 2, 5 and 10, is a diagrammatically developed view showing the positions of the head gaps of magnetic heads on a head support of a drum-shaped scanning device of the video recorder shown in FIG. 15; FIG. 17 shows, in broken lines, a part of a track pattern already recorded on a magnetic tape in a Short-Play mode, for example, by means of a video recorder as shown in FIG. 1, having tracks containing analog PAL video signals, these tracks capable of being scanned by one head pair of the video recorder shown in FIG. 15 in a Short-Play mode in order to reproduce analog PAL video signals, and, in solid lines, a part of a track pattern having tracks capable of being scanned at a given tape speed by two head pairs of the video recorder shown in FIG. 15, in order to record and reproduce digital video signals and digital audio signals in a Short-Play mode; FIG. 18, in a way similar to FIGS. 1, 4 and 15, shows, diagrammatically, a part of a video recorder in accordance with a fourth embodiment of the invention, which is adapted to record and reproduce digital video signals and digital audio signals in inclined tracks; FIG. 19, in a way similar to FIGS. 2, 5, 10 and 16, is a diagrammatically developed view showing the positions of the head gaps of magnetic heads on a head support of a drum-shaped scanning device of the video recorder shown in FIG. 18; and FIG. 20 shows a part of a track pattern on a magnetic tape having tracks capable of being scanned, at a given tape speed in order to record and reproduce digital video signals and digital audio signals in a Short-Play mode, by two head pairs of the video recorder shown in FIG. 18. DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows, diagrammatically, a part of a known prior-art video recorder 1. The video recorder 1 is constructed to record and reproduce analog video signals and analog audio signals on a magnetic tape 2 in adjacent tracks which are inclined relative to the longitudinal or forward direction of the tape indicated by an arrow 3, i.e., in inclined tracks. For this purpose, the video recorder 1 comprises a drum-shaped scanning device 4 around which the magnetic tape 2 is wrapped along a helical path during the recording and reproduction of signals, which is not shown in FIG. 1 but which is generally known to those skilled in the art. Four movable tape guides 5, 6, 7 and 8 serve to wrap the magnetic tape 2 and to keep it wrapped around the drum-shaped scanning device 4. The magnetic tape 2 is further in scanning contact with a stationary magnetic head 9, by means of which analog signals can be recorded on and reproduced from the magnetic tape 2 in a track which extends in the longitudinal direction 3 of the tape, i.e., in a longitudinal track. The magnetic tape 2 is further wrapped around a capstan 10. A movable pressure roller 11 presses the magnetic tape 2 against the capstan 10 during recording and reproduction of signals. The capstan 10 can be driven by a motor 13 via a drive transmission 12, which is shown, diagrammatically, as a dash-dot line. The motor 13 is powered by a power supply 14. The power supply 14 includes a speed control device for driving the motor 13, and hence the capstan 10, at the given constant speeds desired in each case. In the video recorder 1 shown in FIG. 1, the magnetic tape 2 can be driven to record and reproduce analog PAL video signals and analog audio signals with a tape speed v(P)=2.34 m/s in a so-called Short-Play mode, and with a tape speed v(P/2)=v(P)/2=1.17 m/s in a Long-Play mode. The drum-shaped scanning device 4 comprises a rotationally drivable head support 15 carrying a plurality of magnetic heads. The rotationally drivable head support 15 can be driven by a motor 17 in a direction indicated by an arrow 18 via a drive transmission 16, which is also shown, diagrammatically, as a dash-dot line. A power supply 19 serves to power the motor 17. The power supply 19 includes a speed control device for driving the motor 17, and hence the head support 15, at at least one desired given constant speed. In the video recorder 1 shown in FIG. 1, the rotationally drivable head support 15 is driven with a speed n(P)=1500 r.p.m. in all the modes of operation. For the transmission of analog PAL video signals while the magnetic tape 2 is driven with the normal tape speed v(P), the head support 15 carries a first head pair 20 of two diagonally mounted magnetic heads SP1 and SP2, having head gaps with oppositely oriented comparatively small first azimuth angles, by means of which the magnetic tape 2 can be scanned along first adjacent inclined tracks 21 and 22, as is illustrated by the part of a track pattern shown in the upper part of FIG. 3. FIG. 2 shows, diagrammatically, a development of the head support 15 in a plane 24 represented, diagrammatically, as a dash-dot line in FIG. 1, FIG. 2 showing this development viewed in the direction indicated by the arrow 25 in FIG. 1. As is apparent from FIGS. 1 and 2, the head gap of the magnetic head SP2 occupies an angular position referred to as 0° and the magnetic head SP1 occupies the diagonally opposed angular position of 180° in the situation shown. FIG. 2 also illustrates the height positions of the head gaps of the magnetic heads SP2 and SP1 relative to the head support 15, i.e., relative to a reference surface having a height H=0 on the head support 15. The two magnetic heads SP1 and SP2 each have a head gap with a gap width of approximately 48 μm. Consistent with accepted terminology in the field, the direction of the gap width of a magnetic head corresponds to the direction of the track width of the track scanned by the magnetic head, and the gap length of a magnetic head corresponds to the length direction, predominantly along the direction of tape travel, of the track scanned by the magnetic head. The gap length of the head gap of each of the two magnetic heads SP1 and SP2 has a value of approximately 0.45 μm. The magnetic head SP1 has an azimuth angle of approximately +6°, and the magnetic head SP2 has an azimuth angle of approximately -6°. These azimuth angles cannot be shown properly in FIG. 2 as this would require an extremely large scale in the direction of the gap width, i.e., in the height direction of the drawing, for which reason the azimuth angles of the head gaps have not been shown in FIG. 2. The azimuth angles of the two magnetic heads SP1 and SP2 are represented in FIG. 3 by the tracks 21 and 22 which are scanned by these magnetic heads. The representation of the azimuth angles applies also for the azimuth angles of all the others of magnetic heads mentioned hereinafter. For the transmission of analog video signals while the magnetic tape 2 is driven with the reduced tape speed v(P/2), the head support 15 further carries a second head pair 26 of two diagonally mounted magnetic heads LP1 and LP2, having head gaps with oppositely oriented comparatively small second azimuth angles, by means of which the magnetic tape 2 can be scanned along second adjacent inclined tracks 27 and 28, as is illustrated by the part of a track pattern in the lower part of FIG. 3. The head gaps of the magnetic heads LP1 and LP2 occupy angular positions close beside and before the head gaps of the magnetic heads SP2 and SP1 in a direction identical to that indicated by the arrow 18. The angular distance between the head gaps of the magnetic heads LP1 and SP2 or LP2 and SP1, respectively, essentially corresponds to twice the distance by which two successive line synchronization pulses of an analog video signal will be or have been recorded in an oblique track, which is of known dimension. FIG. 2 also shows the height positions of the head gaps of the magnetic heads LP1 and LP2 relative to the head support, i.e., relative to its reference surface having the height H=0. The two magnetic heads LP1 and LP2 each have a head gap with a gap width of approximately 35 μm. The gap length of the head gap of each of the two magnetic heads LP1 and LP2 is approximately 0.45 μm. The magnetic head LP1 has a head gap with an azimuth angle of approximately +6°, and the magnetic head LP2 has a head gap with an azimuth angle of approximately -6°, as is illustrated in the track pattern 29 shown in FIG. 3 by the solid-line hatching. As is apparent from FIG. 3, the head gaps of the magnetic heads LP1 and LP2 have an excess width in relation to the tracks 27 and 28, as a result of which during the recording of video signals by means of the two magnetic heads LP1 and LP2, a part of the wider track recorded previously by a magnetic head LP1 or LP2 is partly overwritten by the respective magnetic head LP2 or LP1 which subsequently scans the magnetic tape 2. This is a step long known to those skilled in the art. For the transmission of analog audio signals at the tape speeds v(P) and v(P/2), the head support 15 further carries a further head pair 30 of two diagonally arranged magnetic heads A1 and A2 having head gaps with oppositely oriented comparatively large further azimuth angles, by means of which the magnetic tape 2 can be scanned along further adjacent inclined tracks 31, 32 and 33, 34 respectively, as is illustrated by the track patterns 23 and 29 in FIG. 3. The head gaps of the magnetic heads A1 and A2 are situated at angular positions which are 40° spaced from and situated behind the head gaps of the magnetic heads SP1 and SP2 in a direction opposite to that indicated by the arrow 18. FIG. 2 also shows the height positions of the head gaps of the magnetic heads A1 and A2 relative to the head support 15, i.e., relative to its reference surface having the height H=0. The magnetic heads A1 and A2 each have a head gap with a gap width of approximately 32 μm. The gap length of the head gap of each of the two magnetic heads A1 and A2 is approximately 1.2 μm. The magnetic head A1 has a head gap with an azimuth angle of approximately +30°0 and the magnetic head A2 has a head gap with an azimuth angle of approximately -30°, as is illustrated in the track patterns 23 and 29 by the broken-line hatchings in the tracks 31, 32 and 33, 34 respectively. It is to be noted that during the recording of analog video signals and analog audio signals, depending on the mode of operation, the magnetic heads A2 and A1 first write an analog audio signal in the respective tracks 31, 32 and 33, 34 scanned by these heads, the analog audio signal being recorded in deeper situated tape layers of the magnetic tape 2, after which, depending on the mode of operation, the magnetic heads SP1 and SP2 or LP1 and LP2 record the analog video signals into the respective tracks 21, 22 and 27, 28 scanned by them, this recording being effected in higher situated tape layers, overwriting the audio signal component stored in the deeper situated tape layers. This is a step long known to those skilled in the art. It is to be noted that the head support 15 of the drum-shaped scanning device 4 may also carry further magnetic heads. These heads may be, for example, magnetic erase heads for the track-by-track erasure of signals stored in inclined tracks. The video recorder 1 has a signal processing device 35 for processing analog PAL video signals and analog audio signals. This signal processing device 35 inter alia includes a modulator device and a demodulator device for modulating and demodulating the luminance signal components of the analog PAL video signals, and frequency conversion devices for the frequency conversion of the chrominance signal components of the analog PAL video signals, as well as frequency-response-modifying circuit elements, amplifiers and an audio signal processing device for processing the analog audio signals which can be recorded and reproduced by means of the stationary magnetic head 9 but also for the frequency-modulation and frequency-demodulation of analog audio signals to enable frequency-modulated analog audio signals to be recorded by means of the rotationally drivable magnetic heads A1 and A2, and to enable frequency-modulated analog audio signals reproduced by means of the magnetic heads A1 and A2 to be frequency-demodulated, respectively. Such a device for processing analog video signals and analog audio signals is known, for example, from video recorder which is commercially available from Philips Electronics under the type designation VR 632. The signal processing device 35 has a first input 36 for receiving an analog PAL video signal. The signal processing device 35 further has a second input 37 for receiving an analog audio signal. The signal processing device 35 further has a first terminal 38. Analog audio signals processed by the signal processing device 35 can be applied to the stationary magnetic head 9 in order to be recorded in a longitudinal track on the magnetic tape 2 and analog audio signals reproduced by means of the stationary magnetic head 9 can be applied to the signal processing device 35 in order to be processed via the first terminal 38. The signal processing device 35 further has a second terminal 39. Analog PAL video signals processed by the signal processing device 35 can be applied to the two magnetic heads SP1 and SP2 in the Short-Play mode in order to be recorded, and analog PAL video signals reproduced by the two magnetic heads SP1 and SP2 in the Short-Play mode can be applied to the signal processing device 35 in order to be processed, via the second terminal 39. The signal processing device 35 further has a third terminal 40. Analog PAL video signals processed by the signal processing device 35 in the Long-Play mode can be applied to the magnetic heads LP1 and LP2 in order to be recorded on the magnetic tape 2, and analog PAL video signals reproduced by the two magnetic heads LP1 and LP2 in the Long-Play mode can be applied to the signal processing device 35 in order to be processed, via the third terminal 40. The signal processing device 35 further has a fourth terminal 41. Frequency-modulated analog audio signals processed by the signal processing device 35 can be applied to the two magnetic heads A1 and A2 in order to be recorded on the magnetic tape 2 in inclined tracks, and frequency-modulated analog audio signals reproduced by the two magnetic heads A1 and A2 can be applied to the signal processing device 35 in order to be frequency-demodulated and further processed, via the fourth terminal 41. It is to be noted that a rotary transformer is arranged between the terminals 39, 40, 41 and the magnetic heads SP1, SP2 and LP1, LP2, and A1, A2, but this is not shown in FIG. 1. The signal processing device 35 further has a first output 42 at which the reproduced analog PAL video signals processed by the signal processing device 35 are available. The signal processing device 35 further has a second output 43 at which the reproduced analog audio signals processed by the signal processing device 35 are available. In a Short-Play mode, in which the magnetic tape 2 is driven in the forward direction 3 with the normal tape speed v(P) and the rotationally drivable head support 15 is driven with a speed n(P)=1500 r.p.m., the video recorder 1, shown in FIG. 1, enables analog PAL video signals and analog audio signals to be recorded in and reproduced from the tracks 21, 22, 31 and 32 in accordance with the track pattern 23, recording and reproduction being effected with the magnetic heads A1, A2 and SP1, SP2. In a Long-Play mode, in which the magnetic tape 2 is driven in the forward direction 3 with half the tape speed v(P/2) and the head support 15 is driven with a speed n(P)=1500 r.p.m., the video recorder 1 further enables analog PAL video signals and analog audio signals to be recorded in and reproduced from the tracks 27, 28, 33 and 34 in accordance with the track pattern 29, recording and reproduction being effected with the magnetic heads A1, A2 and LP1, LP2. FIG. 4, in a similar way to FIG. 1, shows, diagrammatically, a part of a video recorder in accordance with a first embodiment of the invention. The video recorder 1 also comprises a drum-shaped scanning device 4 with a rotationally drivable head support 15. The head support 15 also carries three pairs 20, 26, 30 of magnetic heads SP1, SP2, and LP1, LP2, and A1, A2. However, in comparison with the video recorder 1 shown in FIG. 1, the magnetic heads LP1 and LP2 of the second head pair 26 in the video recorder 1 shown in FIG. 4 have different relative positions with respect to the magnetic heads SP1 and SP2 of the first head pair 20 and the magnetic heads A1 and A2 of the second head pair 30 as well as the head support 15. As will appear from a comparison of FIGS. 2 and 5, the magnetic heads LP1 and LP2 of the second head pair 26 in the video recorder 1 shown in FIG. 4, occupy higher height positions relative to the head support 15 than in the video recorder 1 in FIG. 1. In the video recorder 1 shown in FIG. 4 the magnetic heads LP1 and LP2 of the second head pair 26 and the magnetic heads A1 and A2 of the further head pair 30 are arranged on the head support 30 in such a relationship to one another that the magnetic heads LP1 and LP2 of the second head pair 26 and the magnetic heads A1 and A2 of the further head pair 30 scan interleaved inclined tracks 44, 45, 46, 47, 48 when the magnetic tape 2 is driven with a given tape speed v(D) in the forward direction 3 and the head support is driven with a given speed n(D) in the direction indicated by the arrow 18. In so doing, one of the inclined tracks 44, 46 and 48 scanned by a magnetic head LP1 or LP2 of the second head pair 26 is situated between two of the inclined tracks 45 and 47 scanned by the magnetic heads A2 and A1 of the further head pair 30, as can be seen in the track pattern 49 shown in FIG. 9. In the video recorder 1 shown in FIG. 4, the given tape speed v(D) has a value v(D)=v(N)=3.33 m/s. This speed v(N) corresponds to the normal tape speed in a Short-Play mode of a video recorder in accordance with the VHS standard for recording and reproducing video signals in conformity with the NTSC television standard. However, said given tape speed v(D) in the video recorder 1 as shown in FIG. 4 may also have a value which differs from v(N). In the video recorder 1 shown in FIG. 4, the given speed of rotation n(D) has a value n(D)=n(N)=1800 r.p.m. This speed n(N) corresponds to the normal head speed of a video recorder in accordance with the VHS standard for recording and reproducing video signals in conformity with the NTSC standard. However, this speed n(D) may also have a value which differs from n(N). In the video recorder 1 shown in FIG. 4, a magnetic tape 2 can be driven not only with said given tape speed v(D)=v(N), but also with the normal tape speed v(P) already mentioned with reference to the video recorder 1 of FIG. 1, this normal tape speed having a value of 2.34 m/s and corresponding to the normal tape speed in a Short-Play mode of a video recorder in accordance with the VHS standard for recording and reproducing video signals in conformity with a PAL standard. In the video recorder 1 shown in FIG. 4, the rotationally drivable head support 15 with the magnetic heads it carries can be driven not only with the speed n(D)=n(N)=1800 r.p.m., but also with the speed n(P)=1500 r.p.m. In the video recorder 1 shown in FIG. 4, the magnetic heads SP1 and SP2 of the first head pair 20 have the same values for their azimuth angles, their gap widths and their gap lengths as in the video recorder 1 shown in FIG. 1. The magnetic head SP1 has a head gap with an azimuth angle of approximately +6°, a gap width of approximately 48 μm, and a gap length of approximately 0.45 μm. The magnetic head SP2 has a head gap with an azimuth angle of approximately -6°, a gap width of approximately 48 μm, and a gap length of approximately 0.45 μm. However, alternatively, the head gaps of the magnetic heads SP1 and SP2 may each have a gap length of approximately 0.33 μm. The magnetic heads A1 and A2 of the further head pair 30 of the video recorder 1 shown in FIG. 4 have the same values for their azimuth angles and their gap widths as in the video recorder 1 shown in FIG. 1. The magnetic head A1 has a head gap with an azimuth angle of approximately +30° and a gap width of approximately 32 μm. The magnetic head A2 has a head gap with an azimuth angle of approximately -30° and a gap width of approximately 32 μm. However, in comparison with the magnetic heads A1 and A2 of the video recorder 1 shown in FIG. 1, the magnetic heads A1 and A2 of the video recorder 1 shown in FIG. 4 have differently dimensioned gap lengths. The magnetic heads A1 and A2 of the video recorder 1 in FIG. 4 each have a head gap with a gap length of approximately 0.30 μm. The magnetic heads LP1 and LP2 of the second head pair 26 of the video recorder 1 shown in FIG. 4 have azimuth angles of the same values as the corresponding magnetic heads LP1 and LP2 of the video recorder 1 shown in FIG. 1. The magnetic head LP1 has a head gap with an azimuth angle of approximately +6° and the magnetic head LP2 has a head gap with an azimuth angle of approximately -6°. The gap length of the head gap of each of the two magnetic heads LP1 and LP2 of the video recorder 1 in FIG. 4, however, is approximately 0.30 μm, whereas the gap length of the head gap of each of the two magnetic heads LP1 and LP2 of the video recorder 1 in FIG. 1 has a value of approximately -0.45 μm. The gap width of the head gap of each of the two magnetic heads LP1 and LP2 of the video recorder 1 in FIG. 4 is approximately 32 μm, whereas the gap width of the head gaps of the magnetic heads LP1 and LP2 of the video recorder in FIG. 1 has a value of approximately 35 μm. The video recorder 1 in FIG. 4 further comprises a signal processing device 50 for processing digital video signals and digital audio signals. The signal processing device 50 has a first input 51 for receiving analog video signals. The analog video signals at the first input 51 are applied to the signal processing device 50. In the signal processing device 50, these analog video signals are digitized and processed in order to be recorded in digital form. After this, the video signals, which have been processed in the signal processing device 50 in order to be recorded in digital form, are applied to a first terminal 52 and to a second terminal 53. In a modified embodiment, it is alternatively possible to apply digital video signals directly to the first input 51 of a signal processing device 50. Moreover, a signal processing device 50 may have two separate first inputs, one input being arranged to receive analog video signals and the other input being arranged to receive digital video signals. The first terminal 52 is connected to a first terminal 54 of a first switching device 55. The first switching device 55 has a second terminal 56 connected to the third terminal 40 of the signal processing device 35. A change-over terminal 57 of the first switching device 55 is connected to the magnetic heads LP1 and LP2 of the second head pair 26 via a rotary transformer, not shown. The second terminal 53 of the signal processing device 50 is connected to a first terminal 58 of a second switching device 59. The second switching device 59 has a second terminal 60 connected to the fourth terminal 41 of the signal processing device 35. A change-over terminal 61 of the second switching device is connected to the magnetic heads A1 and A2 of the second head pair 30 via a rotary transformer, not shown. The digital video signals to be recorded can be applied from the two terminals 52 and 53 to the magnetic heads LP1, A2, LP2, A1 via the two switching devices 55 and 59, these four magnetic heads LP1, A2, LP2, A1 recording the digital video signals applied to them in the adjacent tracks 44, 45, 46, 47 and 48 on a magnetic tape 2, the magnetic tape 2 being driven in the forward direction 3 with the tape speed v(D)=v(N). Digital video signals reproduced from the tracks 44, 45, 46, 47 and 48 by the magnetic heads LP1, A2, LP2, A1 can be applied to the two terminals 52 and 53 of the signal processing device 50 via the two switching devices 55 and 59. In the signal processing device 50, the reproduced digital video signals applied to it are processed and subsequently converted into analog video signals. The converted analog video signals are applied to a first output 62 of the signal processing device 50, where they are available for further processing. In a modified embodiment, conversion of the processed digital via into analog video signals may be omitted, in which case a signal processing device 50 supplies digital video signals at its first output 62; these signals may still be combined with digital audio signals. However, a signal processing device 50 may alternatively have two separate first outputs, in which case digital video signals are available at one output and analog video signals are available at the other output. The signal processing device 50 further has a second input 63, to which analog audio signals can be applied. Applied analog audio signals are applied from the second input 63 to the signal processing device 50 and, in the signal processing device 50, they are converted into digital audio signals and processed for recording on the magnetic tape 2. The digital audio signals processed for recording on the magnetic tape 2 are also supplied to the two terminals 52 and 53 of the signal processing device 50 similarly to the processed digital video signals to be recorded, the processed digital audio signals to be recorded and the processed digital video signals to be recorded being interleaved with one another. The processed digital audio signals are recorded on the magnetic tape 2 in the same way as the digital video signals in the tracks 44, 45, 46, 47 and 48 by means of the magnetic heads LP1, A2, LP2 and A1. In a modified embodiment, digital audio signals may also be applied directly to the second input 63 of a signal processing device 50 if such digital audio signals have not yet been applied to the first input 51 of this signal processing device 50 in interleaved form with digital video signals. Moreover, a signal processing device 50 may have two separate inputs, in which case analog audio signals can be applied to the one input and digital audio signals can be applied to the other input. Digital audio signals reproduced from the magnetic tape 2 together with the digital video signals with which they are interleaved are applied to the terminals 52 and 53 of the signal processing device 50 via the switching devices 55 and 59. In the signal processing device 50, the digital audio signals are separated from the digital video signals and are subsequently converted into analog audio signals. The analog audio signals are applied to a second output 64 of the signal processing device 50, at which they are available for further processing. In a modified embodiment, the conversion of the processed digital video signals into analog video signals may be omitted, in which case a signal processing device 50 supplies digital audio signals at its second output, which signals may still be interleaved with digital video signals. A signal processing device 50, however, may also have two separate second outputs, in which case digital audio signals are available at the one output and analog audio signals are available at the other output. The video recorder 1 shown in FIG. 4 is suitable for recording and reproducing analog PAL video signals and associated audio signals and for recording and reproducing digital video signals and associated digital audio signals FIG. 6 shows a part of a track pattern 65 comprising two tracks 66 and 67 and recorded by a video recorder for recording PAL video signals in a Short-Play mode. The track pattern 65 may have been recorded, for example, by means of a known video recorder 1 as shown in FIG. 1. The analog PAL video signals stored in the tracks 66 and 67 of the track pattern 65 can be read and reproduced by the magnetic heads SP1 and SP2 of the first head pair 20 of the video recorder 1 shown in FIG. 1 in a Short-Play mode when the magnetic tape 2 is driven in the forward tape transport direction 3 with the tape speed v(P)=2.34 m/s, and the magnetic heads SP1 and SP2 are driven with the speed n(P)=1500 r.p.m., as is indicated in FIG. 6. The reproduced analog video signals are applied to the second terminal 39 of the signal processing device 35 and are subsequently processed in the signal processing device 35. Likewise, it is possible to record analog PAL video signals on a magnetic tape 2 by the magnetic heads SP1 and SP2 of the video recorder 1 of FIG. 1 in a Short-Play mode, in which case, the magnetic tape 2 is also driven with the tape speed v(P)=2.34 m/s, and the magnetic heads SP1 and SP2 are driven with the speed n(P)=1500 r.p.m., and the magnetic heads SP1 and SP2 record the analog PAL video signals applied to them in tracks 66 and 67 in accordance with the track pattern 65, which is shown partly in FIG. 6. The recorded analog PAL video signals are applied to the magnetic heads SP1 and SP2 from the signal processing device 35 via the second terminal 39 of this device. FIG. 7 shows a further part of a track pattern 68 comprising tracks 69 and 70 as well as 71 and 72. The tracks 69 and 70 contain analog PAL video signals. The tracks 71 and 72 contain associated analog audio signals in frequency-modulated form. The signals have been recorded by means of a known video recorder for recording and reproducing analog PAL video signals and associated analog frequency-modulated audio signals in a Short-Play mode. Recording may have been effected by means of, for example, a video recorder 1 as shown in FIG. 1. The recorded analog PAL video signals can be scanned and reproduced by means of the magnetic heads SP1 and SP2 and the associated analog audio signals can be scanned and reproduced by means of the magnetic heads A1 and A2, despite their small gap lengths of only 0.30 μm, in a Short-Play mode of the video recorder 1 shown in FIG. 4 when the magnetic tape 2 is driven in the forward tape-transport direction 3 with the tape speed v(P)=2.34 m/s, and the magnetic heads are driven in the direction indicated by the arrow 18 with a speed of rotation of n(P)=1500 r.p.m., as is indicated in FIG. 7. The reproduced analog video signals are applied to the second terminal 39 of the signal processing device 35 and are subsequently processed in the signal processing device 35. The reproduced analog audio signals are applied to the fourth terminal 41 of the signal processing device 35 via the second switching device 35 and are subsequently processed in the signal processing device 35. As already stated, it is possible to record analog PAL video signals by the magnetic heads SP1 and SP2 of the video recorder 1 of FIG. 4 in a Short-Play mode. Recording of analog audio signals by the magnetic heads A1 and A2 is not possible because the gap length of 0.30 μm of the head gaps of these two magnetic heads A1 and A2 is too small for the recording of analog audio signals. However, recording of analog audio signals is possible by the stationary magnetic head 9, to which analog audio signals can be applied from the first terminal 38 of the signal processing device 35. Analog audio signals reproduced by the stationary magnetic head are applied to the first terminal 38 of the signal processing device 35 for processing these signals. FIG. 8 shows a part of a further track pattern 73 comprising tracks 74 and 75, which have been recorded on the magnetic tape 2 in a Long-Play mode by a known video recorder for recording and reproducing analog PAL video signals and associated analog audio signals, for which the magnetic tape 2 was driven in the forward tape transport direction 3 with half the tape speed v(P/2)=V(P)/2=1.17 m/s, and the magnetic heads were driven in the direction indicated by the arrow 18 with a speed of rotation n(P)=1500 r.p.m. Of the signals stored in accordance with the track pattern 73 in the tracks 74 and 75, the analog PAL video signals stored in the tracks 74 and 75 can be reproduced in a Long-Play mode by the magnetic heads LP1 and LP2. Likewise, the recording of analog PAL video signals is possible in a Long-Play mode by the magnetic heads LP1 and LP2. Both during reproduction and during recording of analog PAL video signals in the Long-Play mode, the magnetic heads LP1 and LP2 are connected to the third terminal 40 of the signal processing device 35 via the first switching device 55. In the Long-Play mode, the magnetic tape is driven with the tape speed v(P/2)=V(P)/2=1.17 m/s, and the magnetic heads are driven with a speed of rotation n(P)=1500 r.p.m. During the recording of analog PAL video signals, the magnetic heads LP1 and LP2 of the video recorder shown in FIG. 4 writes the same tracks 74 and 75 in accordance with the track pattern 73 as with a known video recorder for recording and reproducing analog PAL video signals and analog audio signals. It is to be noted that the magnetic heads LP1 and LP2 have an excess width in relation to the tracks 74 and 75. By means of the magnetic heads A2 and A1 of the video recorder 1 shown in FIG. 4, it is not possible to reproduce the analog audio signals stored in the tracks 74 and 75 in the relative positions, shown in FIG. 8, of the head gaps of the magnetic heads LP1, A2, LP2, A1 with respect to the tracks 74 and 75 to be scanned, because the magnetic head A2, having a head gap with an azimuth angle of approximately -30°, always scans a track, for example the track 75, in which the analog audio signals have been recorded with a magnetic head having a head gap with an azimuth angle of +30°. Likewise, the magnetic head A1, having a head gap with an azimuth angle of approximately +30°, always scans a track, for example the track 74, recorded by means of a magnetic head having a head gap with an azimuth angle of -30°. However, by means of a tracking servo device provided in the video recorder 1 shown in FIG. 4, the head gaps of the magnetic heads LP1, A2, LP2, A1 can be brought into such relative positions with respect to the tracks to be scanned that a satisfactory tracking is obtained for all the four magnetic heads, thereby guaranteeing a correct scanning of the tracks and a correct reproduction of the analog video signals and analog audio signals recorded in these tracks. FIG. 9 shows the afore-mentioned track pattern 49 comprising the tracks 44, 45, 46, 47 and 48. The tracks 44, 45, 46 and 47 are successively scanned by the magnetic heads LP1, A2, LP2, A1 in one complete revolution of the head support 15 when the magnetic tape 2 is driven in the forward tape transport direction 3 with the tape speed v(D)=v(N)=3.33 m/s, and the magnetic heads are driven in the direction indicated by the arrow 18 with said speed of rotation n(D)=n(N)=1800 r.p.m. in a Short-Play mode for the recording and reproduction of digital video signals and digital audio signals. The four tracks 44, 45, 46 and 47 scanned by the magnetic heads LP1, A2, LP2 and A1 in one revolution of the head support 15 provide enough storage capacity to record the digital video signals and digital audio signals, which are interleaved with one another, on the magnetic tape 2. During the recording and reproduction of digital video signals and digital audio signals, the magnetic heads LP1, LP2 and A1, A2 are connected to the terminals 52 and 53 of the signal processing device 50 via the switching devices 55 and 59. It is to be noted that the head gaps of the magnetic heads LP1, A2, LP2 and A1 have a slight excess width in relation to the tracks 44, 45, 47 and 48. Thus, the video recorder 1 shown in FIG. 4 constitutes an apparatus by means of which it is possible to record and reproduce analog PAL video signals, to reproduce analog audio signals, and to record and reproduce digital video signals and digital audio signals in/from inclined tracks, the transmission of analog video signals and analog audio signals and for the recording and reproduction of digital video signals and digital audio signals being effected with the same number of magnetic heads. The transmission of analog video signals and analog audio signals with a video recorder in accordance with the invention is possible because the magnetic heads required for this purpose have head gaps whose azimuth angles have values as used in known video recorders in accordance with the VHS standard. Recording and reproduction of digital video signals and digital audio signals by means of a video recorder in accordance with the invention by magnetic heads suitable for the transmission of analog PAL video signals and analog audio signals is achieved very simply in that these magnetic heads are arranged in a new relationship to one another, which differs from the relationship as used in the known VHS video recorders, and in that the head gaps of these magnetic heads have a gap length suitable for the recording and reproduction of digital signals. A video recorder 1 in accordance with a second exemplary embodiment of the invention will now be described with reference to FIGS. 10 to 14, this video recorder being constructed and suited to record and reproduce analog video signals in accordance with the NTSC standard, and the associated analog audio signals, and to record and reproduce digital video signals and associated digital audio signals. The construction of this video recorder 1 in accordance with the invention basically corresponds to the construction of the video recorder 1 shown in FIG. 4, and FIG. 10 only shows the head gaps of the magnetic heads SP1, SP2, LP1, LP2, A1 and A2 of the video recorder 1 in accordance with the second embodiment of the invention. The video recorder 1 in accordance with the invention as shown in FIG. 10 has another arrangement of the magnetic heads SP1, SP2, LP1, LP2, A1 and A2 in comparison with the rotationally drivable head support 15 as used in the video recorder 1 shown in FIGS. 4 and 5. The angular positions and the height positions of the individual magnetic heads SP1, SP2, LP1, LP2, A1 and A2, as well as the values of the azimuth angles and the gap widths of the head gaps of the magnetic heads SP1, SP2, LP1, LP2, A1 and A2, appear in FIG. 10. With respect to the gap lengths of the head gaps, it is to be noted that the magnetic heads SP1 and SP2 each have a gap length of approximately 0.54 μm, the magnetic heads LP1 and LP2 each have a gap length of approximately 0.20 μm, and the magnetic heads A1 and A2 each have a gap length of approximately 0.20 μm. In the video recorder 1 as shown in FIG. 10 a magnetic tape 2 is driven in the forward tape transport direction 3 with a tape speed v(N)=3.33 m/s in a Short-Play mode. In a Long-Play mode, which is not, or hardly, customary in practice, a magnetic tape 2 is driven in the forward tape transport direction 3 with half the tape speed v(N/2)=v(N)/2=1.66 m/s. In an extended Long-Play mode, a magnetic tape 2 is driven in the forward tape transport direction 3 with one-third of the tape speed v(N), i.e., v(N/3)=v(N)/3=1.11 m/s. These tape speeds are indicated in each of the FIGS. 11, 12 and 13. FIG. 11 shows a part of a track pattern 76 comprising tracks 77, 78 and 79, 80. The tracks 77, 78, 79 and 80 of the track pattern 76 were recorded on the magnetic tape 2 in a Short-Play mode by a known video recorder in accordance with the VHS system for the recording and reproduction of analog NTSC video signals and associated audio signals, the magnetic tape having been driven with the tape speed v(N)=3.33 m/s, and the magnetic heads having been driven in the direction indicated by the arrow 18 with the speed of rotation n(N)=1800 r.p.m. The tracks 77, 78, 79 and 80 of the track pattern 76 recorded on a magnetic tape 2 can be scanned by a video recorder 1 in accordance with the invention as shown in FIG. 10 in order to reproduce the NTSC video signals and analog audio signals recorded in these tracks when the magnetic tape 2 is driven with the tape speed v(N)=3.33 m/s, and the magnetic heads are driven in the direction indicated by the arrow 18 with the speed of rotation n(N)=1800 r.p.m., the tracks 77 and 78 then being scanned by the magnetic heads SP1 and SP2 of the video recorder 1 of FIG. 10, and the tracks 79 and 80 of the track pattern 76 being scanned by the magnetic heads A2 and A1 to reproduce the analog NTSC video signals and the frequency-modulated analog audio signals recorded in these tracks. By means of the magnetic heads SP1 and SP2 of a video recorder 1 as shown in FIG. 10, it is also possible to record analog NTSC video signals on a magnetic tape 2 in tracks 77 and 78 in accordance with the track pattern 76. It is not possible to record analog audio signals by means of the magnetic heads A1 and A2 because the gap length of these two magnetic heads A1 and A2 has a value which is too small for the recording of analog audio signals. However, recording of analog audio signals is possible by means of the stationary magnetic head 9. FIG. 12 shows a part of a track pattern 81 comprising tracks 82 and 83. A track pattern 81, comprising tracks 82 and 83, can be recorded in a Long-Play mode by means of a known video recorder for recording and reproducing analog NTSC video signals and analog audio signals, the analog NTSC video signals being recorded in the tracks 82 and 83 as indicated by the solid-line hatching and, in addition, analog audio signals being recorded in the tracks 82 and 83 as indicated by the dash-dot hatching. Such a recording of analog audio signals in the Long-Play mode is not specified in the standard for VHS video recorders for NTSC signals and is not current practice. The analog NTSC video signals recorded in the tracks 82 and 83 can be scanned and reproduced by means of the magnetic heads LP1 and LP2 of the video recorder 1 shown in FIG. 10. Likewise, it is possible to record analog NTSC video signals on a magnetic tape 2 in a Long-Play mode in accordance with the track pattern 81 by means of the magnetic heads LP1 and LP2 of the video recorder 1 shown in FIG. 10. The analog audio signals stored in the tracks 82 and 83 can be reproduced by the magnetic heads A1 and A2 because the magnetic heads A1 and A2 almost completely cover the tracks 82 and 83 to be 83 to be scanned by them. FIG. 13 shows a part of a track pattern 84 comprising tracks 85 and 86. The tracks 85 and 86 store analog NTSC video signals and analog audio signals recorded in an extended Long-Play mode by a known video recorder for the recording and reproduction of analog NTSC video signals and frequency-modulated analog audio signals. FIG. 13 diagrammatically shows the stored analog NTSC video signals as dash-dot hatchings. When the head gaps of the magnetic heads LP1 and LP2 as well as A1 and A2 occupy the relative positions shown in FIG. 13 with respect to the tracks 85 and 86, it is possible to read and reproduce the analog NTSC video signals in the tracks 85 and 86 by the magnetic heads LP1 and LP2, and the analog audio signals in the tracks 85 and 86 by the magnetic heads A1 and A2, because both the magnetic heads LP1 and LP2 and the magnetic heads A1 and A2 provide an adequate coverage of the tracks to be scanned by them in order to obtain a satisfactory reproduction quality. By means of the magnetic heads LP1 and LP2 of the video recorder 1 in accordance with the invention shown in FIG. 10, it is possible to record analog NTSC video signals in accordance with the track pattern 84 in an extended Long-Play mode. As already stated, it is not possible to record frequency-modulated analog audio signals by the magnetic heads A1 and A2 due to the small gap length of the head gaps of these magnetic heads. It is to be noted also that the head gaps of the magnetic heads LP1 and LP2 as well as A1 and A2 have an excess width in relation to the tracks 85 and 86. FIG. 14 shows a part of a track pattern 87 comprising tracks 88, 89, 90 and 91. In the video recorder 1 in FIG. 10, in the same way as in the video recorder 1 in FIG. 4, the tracks 88, 89, 90 and 91 are also scanned by the magnetic heads LP1, A2, LP2 and A1 in one revolution of the rotationally drivable head support 15 when a magnetic tape 2 is driven in the forward tape transport direction with the tape speed v(D)=v(N)=3.33 m/s, and when the magnetic heads are driven in the direction indicated by the arrow 18 with the speed of rotation v(D)=n(N)=1800 r.p.m. During scanning of the tracks 88, 89, 90 and 91 by the magnetic heads LP1, A2, LP2 and A1, it is possible either to record or to reproduce digital video signals and digital audio signals. The video recorder 1 shown in FIG. 10 also has the advantage that by means of the same magnetic heads, it is possible to transmit analog video signals and associated analog audio signals, and to record and reproduce digital video signals and associated digital audio signals. FIG. 15 shows a part of a video recorder 1 in accordance with a third exemplary embodiment of the invention. This video recorder 1 is constructed and is suited to record and reproduce analog PAL video signals and associated analog audio signals, and to record and reproduce digital video signals and associated digital audio signals. In a modification, such a video recorder can also be constructed so as to be suited to record and reproduce analog NTSC video signals and associated analog audio signals, and to record and reproduce digital video signals and associated digital audio signals. In the video recorder 1 shown in FIG. 15, the rotationally drivable head support 15 carries only two pairs 20 and 30 of magnetic heads SP1 and SP2 as well as A1 and A2. The angular positions and the height positions of the of the head gaps of the magnetic heads SP1, SP2 and A1, A2 appear in FIG. 16. FIG. 16 also gives the values of the azimuth angles and the gap widths of the head gaps of the magnetic heads SP1, SP2 and A1, A2. With respect to the gap lengths of the head gaps of the magnetic heads SP1, SP2 and A1, A2, it is to be noted that the magnetic heads SP1 and SP2 each have a gap length of approximately 0.30 μm, and the magnetic heads A1 and A2 each have a gap length of approximately 0.30 μm. However, the gap lengths of the head gaps of the magnetic heads SP1, SP2, A1 and A2 may alternatively be approximately 0.25 μm, or approximately 0.20 μm. In the video recorder 1 shown in FIG. 15, the magnetic heads SP1 and SP2 of the one head pair 20 and the magnetic heads A1 and A2 of the further head pair 30 are arranged on the head support 15 in such a relationship to one another that the magnetic heads SP1 and SP2 of the one head pair 20 and the magnetic heads A1 and A2 of the further head pair 30 scan adjacent interleaved inclined tracks 92, 93, 94, 95, 96 and 97, as shown by the solid-line track pattern 98 in FIG. 17, when the magnetic tape 2 is driven with a given tape speed v(D)=v(N)=3.33 m/s, and the magnetic heads are driven with the speed of rotation n(D)=n(N)=1800 r.p.m. The tracks 92, 93, 94 and 95 can be scanned by the magnetic heads SP1, A2, SP2 and A1 during one full revolution of the rotationally drivable head support 15. During scanning of the track pattern 98, the magnetic heads SP1, A2, SP2 and A1 can record digital video signals and digital audio signals, or can reproduce digital video signals and digital audio signals, said magnetic heads SP1, A2, SP2 and A1 being connected to the two terminals 52 and 53 of the signal processing device 50 via the two switching devices 55 and 59. It is to be noted that in the video recorder 1 shown in FIG. 15, the change-over terminal 57 of the first switching device 55 is connected to the magnetic heads SP1 and SP2 via a rotary transformer, and not to the magnetic heads LP1 and LP2, as in the video recorder 1 shown in FIGS. 4 and 10. Moreover, it is to be noted that the head gaps of the magnetic heads SP1 and SP2 have an excess width in relation to the tracks 92, 94 and 96. In the video recorder 1 shown in FIG. 15, a magnetic tape 2 can be driven in the forward tape transport direction 3 not only with the afore-mentioned tape speed v(D)=v(N)=3.33 m/s, but also with the tape speed v(P)=2.34 m/s. When a magnetic tape 2 is driven in the forward tape transport direction 3 with the tape speed v(P)=2.34 m/s, the magnetic heads SP2 and SP1 of the one head pair 20 can scan tracks 99 and 100 of a track pattern 101, which is shown in broken lines in FIG. 17. During scanning of the tracks 99 and 100, it is possible to record or to reproduce analog PAL video signals in a Short-Play mode. When a magnetic tape 2, on which both analog PAL video signals and analog frequency-modulated audio signals have been stored by a known video recorder in accordance with the VHS standard for the recording and reproduction of analog video signals and analog audio signals in/from inclined tracks, is wrapped around the drum-shaped scanning device 4 of the video recorder 1 shown in FIG. 15, both the recorded analog PAL video signals and the recorded analog audio signals can be scanned and reproduced with the magnetic heads SP1, A2, SP2, A1 in a suitable relative position of the head gaps of the magnetic heads SP1, A2, SP2 and A1 with respect to the tracks, which relative position can be obtained by means of a tracking control device of the video recorder 1 in FIG. 15. The video recorder 1 in FIG. 15 also has the advantage that by magnetic heads provided for the transmission of analog video signals and analog audio signals, it is also possible to record and reproduce digital video signals and digital audio signals, namely, in a particularly simple manner, in that the magnetic heads required for this purpose are arranged on a rotationally drivable head support in a given new relationship to one another and the head gaps of these magnetic heads have a suitable gap length for this. FIG. 18 shows a part of a video recorder 1 in accordance with a fourth exemplary embodiment of the invention. This video recorder 1 is constructed and suitable for the recording and reproduction of digital video signals and associated digital audio signals in inclined tracks. In the video recorder 1 shown in FIG. 18, the rotationally drivable head support 15 also carries only two pairs 20 and 30 of magnetic heads D1, D2 and D3, D4. The angular positions and the height positions of the head gaps of the magnetic heads D1, D2 and D3, D4 are shown in FIG. 19. FIG. 19 also gives the values of the azimuth angles and the gap widths of the head gaps of the magnetic heads D1, D2 and D1, D2. With respect to the gap widths of the head gaps of the magnetic heads D1 and D2, it is to be noted that these gap width need not necessarily have a value of 48 μm, but may also have smaller values of approximately 40 μm, 35 μm or even 30 μm. With respect to the gap lengths of the head gaps of the magnetic heads D1 and D2 as well as D3 and D4, it is to be noted that the magnetic heads D1 and D2 may each have a gap length of approximately 0.30 μm, and likewise, the magnetic heads D3 and D4 may each have a gap length of approximately 30 μm. The gap lengths of the head gaps of the magnetic heads D1, D2, D3 and D4, however, may alternatively be approximately 0.25 μm, or approximately 0.20 μm. In the video recorder 1 shown in FIG. 18, the magnetic heads D1 and D2 of the one head pair 20 and the magnetic heads D3 and D4 of the further head pair 30 are arranged on the head support 15 in such a relationship to one another that the magnetic heads D1 and D2 of the one head pair 20 and the magnetic heads D3 and D4 of the further head pair 30 scan adjacent interleaved inclined tracks 102, 103, 104, 105, 106 and 107, as shown by the track pattern 108 in FIG. 17, when the magnetic tape 2 is driven with a given tape speed, i.e., the tape speed v(D)=v(N)=3.33 m/s, and the magnetic heads are driven with the speed of rotation n(D)=n(N)=1800 r.p.m. The tracks 102, 103, 104 and 105 can be scanned by the magnetic heads D1, D2, D3 and D4 during one full revolution of the rotationally drivable head support 15. During scanning of the track pattern 108, the magnetic heads D1, D2, D3 and D4 can record digital video signals and digital audio signals, or can reproduce digital video signals and digital audio signals, said magnetic heads D1, D2, D3 and D4 in the present case not being connected to the two terminals 52 and 53 of the signal processing device 50 via the switching devices. It is to be noted that the head gaps of the magnetic heads D1 and D2 have an excess width in relation to the tracks 102, 104 and 106. In the video recorder 1 shown in FIG. 18, the second input 63 of the signal processing device 50, to which input 63 analog audio signals can be applied, is connected to an input 109 of an audio signal processing device 110 for processing analog audio signals. At a terminal 111, the audio signal processing device 110 supplies analog audio signals, which are applied to the stationary magnetic head 9. The stationary magnetic head 9 records these analog audio signals in a longitudinal track 112 which extends in the longitudinal direction 3 of the tape, as is shown, diagrammatically, in FIG. 20. Analog audio signals reproduced by the stationary magnetic head 9 are applied to the terminal 111 of the audio signal processing device 110, after which the audio signal processing device 110 supplies the reproduced analog audio signals processed by this device to an output 113. The output 113 may be connected to the second output 64 of the signal processing device 50. The recording and reproduction of analog audio signals by the stationary magnetic head 9 may not be desirable for sound-dubbing purposes. Moreover, the video recorder 1 shown in FIG. 18 has the first input 51 of the signal processing device 50, this input 51 being arranged to receive analog video signals, connected to an input 114 of a CTL signal processing device 115. The CTL signal processing device 115 comprises, as is known per se from existing video recorders, a sync separator stage, a microprocessor and an input/output stage. The sync separator stage extracts the synchronization signals, particularly, the vertical synchronization signals, from the video signal applied to the CTL signal processing device 115 and, by means of the extracted vertical synchronization signals, the microprocessor generates a CTL signal, which, in known manner, for example, in accordance with the VHS standard, may be formed by a squarewave signal and which is applied to a terminal 116 of the CTL signal processing device 115 via the input/output stage. The CTL signal is applied from the terminal 116 to a further stationary magnetic head 117, having a head gap arranged, in known manner, in line with the head gap of the stationary magnetic head 9, perpendicularly to the longitudinal direction 3 of the tape in the video recorder 1. For the sake of clarity of the drawing, this mutually aligned position of the head gaps of the two magnetic heads 9 and 117 is not shown in FIG. 18. By means of the stationary magnetic head 117, the CTL signal is recorded on a magnetic tape 2 in a further track 118 which extends in the longitudinal direction 3 of the tape, as is shown in FIG. 20. It is to be noted with respect to the CTL signal, that this signal is formed by a squarewave signal having one rising edge 121 and one falling edge 122 per revolution of the rotationally drivable head support 15 for the magnetic heads D1, D2, D3 and D4. A rising edge 121 may be recorded in the track 118, for example, so as to correspond to the beginning of an inclined track, for example, to the inclined track 102, and the subsequent falling edge 122 may be recorded in the track 118 so as to correspond to the next track plus one, i.e., the track 104. The next rising edge 121 is then recorded in the track 118 so as to correspond to the next inclined track plus two, i.e., the track 106. A CTL signal reproduced by the stationary magnetic head 117 is applied to the terminal 116 of the CTL signal processing device 115 and, in the CTL signal processing device 115, it is first applied to the output/input stage and is subsequently processed further. After this, the processed CTL signal is available at an output 119 of the CTL signal processing device 115. From the output 119, a reproduced CTL signal is applied to an input 120 of the power supply 14, which, as already stated, includes a speed control device in which the CTL signal is used as phase information for the speed control of the motor 13 for driving the capstan 10. The video recorder 1 shown in FIG. 18 also has the advantage that, by means which are known per se, digital video signals and digital audio signals can be recorded in and reproduced from inclined tracks in a particularly simple manner in that the magnetic heads required for this are arranged on a rotationally drivable head support in a given new relationship to one another, and the head gaps of these magnetic heads each have a gap length suitable for this purpose. A part of the video recorder 1 shown in FIG. 18 may be a part of an arrangement for manufacturing pre-recorded magnetic tapes, i.e., an arrangement for recording video signals and audio signals in digital form on a magnetic tape in inclined tracks with a high recording quality. The invention is not limited to the exemplary embodiments described above. There are a multitude of further possibilities for the mutual positions of the magnetic heads provided on a rotationally drivable head support of a drum-shaped scanning device of a video recorder for transmitting analog video signals and analog audio signals and for recording and reproducing digital video signals and digital audio signals. There are also further possibilities as regards the choice of the gap lengths of the head gaps of the magnetic heads provided for transmitting analog video signals and analog audio signals and for recording and reproducing digital video signals and digital audio signals; for example, alternatively the gap length may be only approximately 0.15 μm, but conversely it may also have a value of approximately 0.35 μm. Furthermore, in the exemplary embodiment shown in FIG. 20, the sequence of the tracks is such that recurrently groups of tracks having azimuth angles of each time +30°, +6°, -30°, -6° are recorded. It is obvious that another sequence of the azimuth angles in the groups of tracks is possible, for example +30°, -6°, -30°, +6° or +6°, +30°, -6°, -30°. It is to be noted also that in a variant of the invention, the recording apparatus in accordance with the invention may be configured to record information with a half bit rate. The speed of the record carrier is halved and two heads are used for recording the information with the halved bit rate. The two heads may be the two heads having the same absolute azimuth angle, i.e., either the heads with azimuth angles of +30° and -30°, or the heads with azimuth angles of +6° and -6°. The last-mentioned possibility is less interesting because the difference between the azimuth angles of this head pair is comparatively small (12°). It is also possible to use the two heads with azimuth angles of +30° and +6° or the two heads with azimuth angles of -30° and -6° for recording the information with the halved bit rate. The recording apparatus is then operated in an interval mode. The information is now recorded during half the time because the head pair with which the information is recorded is only in contact with the record carrier for half the time. In addition, it is to be noted that the recording apparatus may be adapted to record information with a bit rate which is halved once more, i.e., with a quarter of the original bit rate, with a record carrier speed which is also halved once more. In the above embodiment using two heads with the same absolute azimuth angle for recording the information with the halved bit rate, this can be achieved in that only one head is used for recording the information. This head then writes the information in tracks on the record carrier during half the time. This would also mean that tracks with the same azimuth angle would be recorded adjacent one another. This is undesirable. Therefore, a second head with another azimuth angle is arranged adjacent this head. These two heads are then used alternately to record the information. In the above embodiment in which the recording apparatus is operated in an interval mode to record the information with the halved bit rate, this can be achieved in that the information is only recorded by means of the head pair during a quarter of the time, i.e., one time for every two revolutions of the head drum. It will be evident that a reproducing apparatus identical to the described recording apparatus can be used to reproduce the information with the halved bit rate or with the bit rate halved once more.

An apparatus for recording and reproducing video and audio signals in either analog or digital form. The heads are arranged to conform with existing analog standards, such as VHS, and yet are also able to record in digital form in adjacent non-overlapping tracks. In a preferred embodiment, one pair of heads is arranged with a small azimuth angle (±6 degrees), and another pair is arranged with a larger second azimuth angle (±30 degrees), conforming to the VHS standard, but the head width and location are modified compared to the standard such as to allow recording and reproducing both VHS as well as digital tapes.

FIELD OF THE INVENTION The present invention relates to a disazo compound as a reactive dye and a method of dyeing cellulosic fibers using this compound. Further, the present invention relates to a reactive dye composition and a dyeing method for dyeing cellulose or cellulose-containing fibers using a reactive dye. BACKGROUND OF THE INVENTION Various reactive dyes have been known. They have been widely used for dyeing cellulosic fibers. The reactive dyes have reactive groups such as monochloro-triazinyl, monofluoro-triazinyl, fluoro-chloro-pyrimidinyl, dichloro-quinoxazinyl, vinylsulfonyl, sulfato-ethylsulfonyl and the like. For dyeing, the reactive dye is used in the presence of an acid binder such as sodium carbonate, sodium hydroxide, sodium metasilicate and the like in a dyeing bath having a pH of 10 or higher and a temperature of 100° C. or less. The acid binder is often added stepwise during a dyeing step in order to avoid problems such as unlevel dyeing, lowering in color yield due to hydrolysis and the like. On the other hand, cellulose-containing blended fibers, especially blended cotton/polyester fibers are commercially employed in large quantities since they give comfortable clothes. A disperse dye used for dyeing polyester fibers is generally used in a dye bath having an acid to neutral pH and a temperature of about 100 to 140° C. in order to avoid its decomposition and alteration. These dyeing conditions of a disperse dye do not agree with those of a reactive dye. Therefore, when blended fibers are dyed, a two bath method wherein respective fibers are independently treated in respective dye bath and an one bath/two step method wherein both fibers are successively treated in one dye bath while sliding dying conditions for each fibers. For purposes of reducing a dyeing time, saving energy, simplifying dyeing operations and the like, a reasonable dyeing method wherein there is no need for controlling a delicate and complicated addition of an agent during a dyeing step has been desired. And, in the dyeing of blended polyester/cotton fibers, an efficient one bath/one step dyeing method wherein both fibers are dyed simultaneously in one dye bath is desired. This one bath/one step dyeing method is sometime referred to as “one bath dyeing method”. A reactive dye used in this method should have a stability without causing a decomposition and a high dyeing property under conditions of dyeing polyester fibers with a disperse dye, that is, in a dye bath having an acidic to neutral pH and a temperature of 100 to 140° C. Some reactive dyes having the above properties have been proposed. Yellow reactive dyes relating to the present invention can be exemplified in, for example, JP-A-60-086168 (1985), JP-A-01-308460 (1989) and the like. However, the dyes described in these patents have not always satisfactory properties. For example, the dyes do not show sufficient dyeing property over a relatively low temperature range around 100° C. and therefore a high color yield is not attained. Problems such as color breakup and unlevel dyeing upon dyeing using a mixed dye comprising a reactive dye and other dye are observed so that a formulation compatibility, a reproducibility and the like are not still satisfactory. Thus, the development of a yellow reactive dye which always shows a high dyeing property, has a good reproducibility and excellent fastnesses in various aspects such as a fastness to light, a fastness to chlorinated water, a fastness to washing and the like, and does not invite problems such as thermal discoloration, phototropy and the like is strongly desired. In addition, in a mixed dye comprising a yellow reactive dye together with a red reactive dye and/or a blue reactive dye, reactive dyes having a reactive groups such as carboxypyridinio-triazinyl group, for example C.I. Reactive Yellow 162, 163, 178; C.I. Reactive Red 221; C.I. Reactive Blue 216, 217; and the like have been used. When a mixed dye comprising the above known reactive dye is used for dyeing, however, many problems such as a poor dyeing reproducibility and an unlevel dyeing property caused by the difference in dyeing property of dyes to be mixed, a color transfer (migration) during a drying step caused by a poor washing of a non-fixed dye, and the like are found. Thus, in a mixed dye comprising a yellow reactive dye together with a red reactive dye and/or a blue reactive dye, the development of a reactive dye composition which shows negligible change in hue with the change of dyeing conditions including an inorganic salt concentration, a bath ratio, a pH of a dye bath, a dyeing temperature, a dyeing period and the like over a wide temperature range from 90 to 140° C., excellent dyeing reproducibility and excellent washing property of a non-fixed dye and without causing problems such as a color transfer of a non-fixed dye during a drying step and the like is desired. Further, the development of a reactive dye composition having excellent formulation compatibility brought about by harmonizing a dyeing property of each dye component and the development of a method of dyeing cellulose fibers or cellulose-containing fibers are strongly desired. SUMMARY OF THE INVENTION Under the above circumstances, the present inventors zealously researched in order to develop a yellow reactive dye having high dyeing property and excellent dyeing reproducibility in a dye bath having an acidic to neutral pH and a wide temperature range. As a result, they found a disazo compound having desired properties. Further, they found a reasonable dyeing technique by which cellulose or cellulose-containing fibers can be dyed with good reproducibility and without inviting a trouble caused by a insufficient washing of a non-fixed dye and the like, by using the above disazo compound together with a specific red reactive dye and/or a specific blue reactive dye so that a dyeing property of each dye component can be harmonized. Accordingly, the present invention relates to: (1) a disazo compound which in a free acid form is represented by the following general formula (1): wherein R 1 is hydrogen atom or methoxy group; R 2 is hydrogen atom, methyl group, methoxy group, acetylamino group or ureido group; R 3 is hydrogen atom or methoxy group; R 4 is hydrogen atom, methyl group, acetylamino group or ureido group; and m is 2 or 3; (2) a method of dyeing cellulosic fibers comprising using the disazo compound as described in the above (1); (3) a reactive dye composition comprising (A) a yellow reactive dye which comprises at least one compound selected from the group consisting of compounds which in free acid forms are represented by the general formula (1) as described in the above (1), together with (B) a red reactive dye which comprises at least one compound selected from the group consisting of azo compounds which in free acid forms are represented by the following general formula (2):  wherein R 5 is CH 3 or C 2 H 5 ; R 6 and R 7 are independently H, Cl or CH 3 ; and X is  and azo compounds which in free acid forms are represented by the following general formula (3):  wherein A is a benzene nucleus having 1 to 2 sulfonic acid group or carboxyl group and optionally methyl group, methoxy group or chlorine atom, or a naphthalene nucleus having 1 to 3 sulfonic acid groups; R 8 , R 9 and R 10 are independently hydrogen atom or methyl group; n is 1 or 2; Y is  or chlorine atom; and B is —(CH 2 ) p — in which p is 2 or 3, —C 2 H 4 OC 2 H 4 —, —CH 2 CH(OH)CH 2 —,  in which R 11 , R 12 and R 13 are independently hydrogen atom, methyl group, sulfonic acid group or carboxyl group, provided that this formula does not represent  in which Q is O, SO 2 , NHCO or NH,  and/or (C) a blue reactive dye which comprises at least one compound selected from the group consisting of formazane compounds which in free acid forms are represented by the following general formula (4):  wherein D is a group of a formazane compound represented by the following general formula (5):  in which the benzene nucleus c may have sulfonic acid group or chlorine atom; t is 0 or 1; when t is 0, R 16 is hydrogen atom, E is the above-defined D or phenyl group substituted with methyl, methoxy, sulfonic acid group or chlorine and when t is 1, R 14 and R 15 each is hydrogen atom or methyl group; G is —C 2 H 4 —, —C 2 H 4 OC 2 H 4 —, phenylene group optionally substituted with methyl, sulfonic acid group, carboxyl or chlorine,  in which J is O, SO 2 , NH and NHCO,  Z is chlorine atom or  in which carboxyl group is bonded to 3 or 4 position; E is the above-defined D; C 1-2 alkyl group; or phenyl group optionally substituted with methoxy, sulfonic acid group or carboxyl, R 16 is hydrogen atom and alternatively R 16 together with E form  provided that when E is D, R 16 is hydrogen atom and when G is  E is not D,  and disazo compounds which in free acid forms are represented by the following general formula (6):  wherein M is phenyl group optionally substituted with sulfonic acid group, carboxyl, methyl, methoxy or chlorine, naphthyl group substituted with 1 to 3 sulfonic acid group, C 1-3 alkyl group optionally substituted with carboxyl or sulfonic acid group or hydrogen atom; R 17 is hydrogen atom or methyl group; W 1 and W 2 are independently chlorine atom or  in which carboxyl group is bonded to 3 or 4 position, provided that at least one of W 1 and W 2 is  in which carboxyl group is bonded to 3 or 4 position; (4) a reactive dye composition as described in the above (3) which contains the red reactive dye (B) comprising a compound represented by the following formulae (7) and/or (8): and a mixture of the blue reactive dye (C) comprising compounds represented by the following formulae (9) and (10): (5) a reactive dye composition as described in the above (4) wherein the yellow reactive dye (A) comprises a compound represented by the formula (11): and the mixing ratio of the compounds represented by the above formulae (9) and (10) in the blue reactive dye (C) is 50 to 70:50 to 30; (6) a method of dyeing cellulose or cellulose-containing fibers comprising using the reactive dye composition described in the above (3), (4) or (5); (7) a method of dyeing cellulose or cellulose-containing fibers comprising using the yellow reactive dye (A) together with the red reactive dye (B) and/or the blue reactive dye (C) as described in the above (3), (4) or (5); (8) a method of dyeing cellulose or cellulose-containing fibers as described in the above (6) or (7) wherein a pH of a dye bath is 5 to 9 and a dyeing temperature is 90 to 140° C.; and (9) a method of dyeing cellulose or cellulose-containing fibers as described in the above claim (8) wherein the dyeing temperature is 95 to 110° C. DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in more detail. The disazo compound of the present invention is represented by the above formula (1) in a free acid form. For example, this compound is synthesized by the following method. A compound which in a free acid form is represented by the general formula (12): wherein m is as defined above, is diazotized. The thus-diazotized compound is coupled with a compound represented by the general formula (13): wherein R 1 and R 2 are as defined above, to obtain a compound which in a free acid form is represented by the general formula (14): wherein R 1 , R 2 and m are as defined above. The diazotization is conducted according to a conventional method using hydrochloric acid and sodium nitrite at a temperature of 0 to 20° C. The coupling is conducted at a temperature of 0 to 30° C. and a pH of 3 to 8. After the reaction, the reaction product is generally salted out with sodium chloride or the like, filtered and isolated. On the other hand, a compound which in a free acid form is represented by the general formula (15): is diazotized. The thus-diazotized compound is coupled with a compound represented by the general formula (16): wherein R 3 and R 4 are as defined above, to obtain a compound which in a free acid form is represented by the general formula (17): wherein R 3 and R 4 are as defined above. The diazotization is conducted according to a conventional method using hydrochloric acid and sodium nitrite at a temperature of 0 to 20° C. The coupling is conducted at a temperature of 0 to 30° C. and a pH of 3 to 8. Then, the compound of the formula (14) or (17) and cyanuric chloride are condensed in any order to obtain a compound which in a free acid form is represented by the general formula (18): wherein R 1 , R 2 , R 3 , R 4 and m are as defined above. The first condensation in the above reaction is conducted in water at a temperature of 0 to 30° C. and a pH of 2 to 8 and the second condensation is conducted at a temperature of 30 to 70° C. and a pH of 3 to 8. Then, the resultant compound of the above formula (18) is reacted with nicotinic acid to obtain a disazo compound represented by the above formula (1). This reaction is conducted in water at a temperature of 80 to 100° C. and a pH of 4 to 7. The form of the disazo compound of the above formula (1) of the present invention may be either its free acid or its salt, or a mixture thereof. Preferably, the disazo compound of the above formula (1) is in the form of its alkali metal salt or its alkaline earth metal salt, especially in the form of Na, K and Li salts thereof. The disazo compound is generally isolated in the form of the above salt by subjecting it to a treatment such as salting out or the like, if necessary. Example of the compound which in a free acid form is represented by the above formula (12) and which is used in the preparation of the disazo compound of the above formula (1) includes 2-amino-3,6-naphthalene-disulfonic acid, 2-amino-4,9-naphthalene-disulfonic acid, 2-amino-5,7-naphthalene-disulfonic acid, 2-amino-6,8-naphthalene-disulfonic acid and the like (wherein m is 2), and 2-amino-3,6,8-naphthalene-trisulfonic acid, 2-amino-4,6,8-naphthalene-trisulfonic acid and the like (wherein m is 3). Example of the compound of the above formula (13) includes aniline, 2-methoxyaniline, 3-methylaniline, 3-methoxyaniline, 3-acetylaminoaniline, 3-ureidoaniline, 2,5-dimethoxyaniline, 2-methoxy-5-methylaniline, 2-methoxy-5-acetylaminoaniline and the like. On the other hand, example of the compound which in a free acid form is represented by the above formula (15) includes 2-aminobenzenesulfonic acid, 3-aminobenzenesulfonic acid, 4-aminobenzenesulfonic acid and the like. Example of the compound of the formula (16) includes aniline, 2-methoxyaniline, 3-methylaniline, 3-acetylaminoaniline, 3-ureidoaniline, 2-methoxy-5-methylaniline, 2-methoxy-5-acetylaminoaniline and the like. Next, the reactive dye composition of the present invention will be described below. The reactive dye composition of the present invention can be obtained by formulating (A) a yellow reactive dye with (B) a red reactive dye and/or (C) a blue reactive dye. The reactive dye composition of the present invention comprises as a yellow reactive dye at least one compound selected from the group consisting of compounds represented by the above general formula (1). Example of the compound represented by the above general formula (1) is shown in Table 1. TABLE 1 positions of SO 3 H position of group on SO 3 H group naphthalene on benzene ring R 1 R 2 ring R 3 R 4 4, 8 H NHCOCH 3 3 OCH 3 H 4, 8 H NHCONH 2 4 H H 6, 8 H NHCOCH 3 4 H H 3, 6, 8 H OCH 3 3 OCH 3 H 3, 6, 8 H NHCONH 2 4 H H 4, 6, 8 H NHCOCH 3 4 H H 4, 6, 8 H CH 3 3 H CH 3 Among the disazo compounds represented by the general formula (1) contained as a yellow reactive dye in the reactive dye composition of the present invention, a compound represented by the formula (11) is preferable. Any other yellow reactive dye having similar reactive groups such as C.I. Reactive Yellow 162, 163, 178 and the like may be used as a yellow reactive dye, in addition to the disazo compound represented by the above formula (1). The form of the disazo compound of the above formula (1) may be either its free acid or its salt, or a mixture thereof. Preferably, the disazo compound of the formula (1) is in the form of its alkali metal salt or its alkaline earth metal salt, especially in the form of Na, K and Li salts thereof. The disazo compound is generally isolated in the form of the above salt by subjecting it to a treatment such as salting out or the like, if necessary. A red reactive dye capable of being contained in the reactive dye composition of the present invention comprises at least one compound selected from the group consisting of compounds represented by the general formula (2) and compounds represented by the general formula (3). Compounds represented by the general formulae (7) and/or (8) are preferable. Further, a red reactive dye may comprise a mixture of a compound represented by the general formula (2) and a compound represented by the general formula (3). Among the compounds represented by the general formula (2), a compound which in a free acid form is represented by the following formula (19) is preferable. A mixing ratio of a compound represented by the general formula (3) and a compound represented by the formula (19) is generally 50 to 100:50 to 0, preferably 70 to 100:30 to 0. Similar to the case of yellow reactive dye, any other red reactive dye having similar reactive groups may be used as a red reactive dye, in addition to the compounds represented by the general formulae (2) and (3). A blue reactive dye capable of being contained in the reactive dye composition of the present invention comprises at least one compound selected from the group consisting of compounds represented by the general formula (4) and compounds represented by the general formula (6). A mixture of a compound represented by the above formula (9) and a compound represented by the above formula (10) is preferable. The mixture comprising a compound represented by the formula (9) and a compound represented by the formula (10) in a mixing ratio of 50 to 70:50 to 30 is more preferable. Similar to the cases of yellow reactive dye and red reactive dye, any other blue reactive dye having similar reactive groups may be used as a blue reactive dye, in addition to the compounds represented by the general formulae (4) and (6). The above compounds of the above formulae (2), (3), (4) and (6) can be synthesized by known methods, for example the methods described in JP-A-60-086169(1985), JP-A-60-090264 (1985), JP-A-60-090265 (1985) and the like. The form of each of these compounds may be either its free acid or its salt, or a mixture thereof. Preferably, the above compounds are in the form of their alkali metal salts or their alkaline earth metal salts, especially in the form of Na, K and Li salts thereof. These compounds are generally isolated in the form of their salts by subjecting them to a treatment such as salting out or the like, if necessary. In the reactive dye composition of the present invention, dyes may be formulated by any method of formulation. For example, a method comprising independently preparing respective dye and then blending the dyes; a method comprising blending dyes in the form of reaction liquids immediately after their preparation and drying to make a composition; a method comprising dissolving respective dye upon dyeing to make a composition under solution; a method comprising dissolving respective dye in a dye bath to make a composition in the dye bath can be employed. A mixing ratio of a yellow reactive dye (A) with a red reactive dye (B) and/or a blue reactive dye (C) is not particularly limited. Generally it is selected depending on desired color tone. For example, a mixing ratio of a yellow reactive dye (A), a red reactive dye (B) and a blue reactive dye (C) to obtain a brown color tone, a gray color tone and a dark green color tone easily giving rise to problems as to a dyeing reproducibility and the like is preferably selected as follows: (brown color tone) (A):(B):(C)=40 to 80:10 to 40:5 to 40 (gray color tone) (A):(B):(C)=10 to 40:10 to 20:50 to 80 (dark green color tone) (A):(B):(C)=30 to 60:0 to 10:40 to 70 If necessary, the reactive dye composition of the present invention contains known additives such as a concentration controlling agent (anhydrous sodium sulfate and the like), a dispersing agent (Demol N, trade name of Kao Corporation, a Tamol-type dispersing agent; Vanilex RN, trade name of Kao Corporation, a lignin-type dispersing agent, and the like), an anti-reducing agent (Polymin L New, trade name of Nippon Kayaku Co., Ltd., an anti-reduction agent; MS powder, trade name of Meisei Chemical Works, Ltd., an anti-reduction agent, and the like). The disazo compound of the above formula (1) and the reactive dye composition according to the present invention can be applied for dyeing cellulosic fibers by a method such as a dip dyeing method, a continuous dyeing method by padding according to the conventional method and a printing method. If the dying method of the present invention is a dip dyeing method, a bath ratio is generally 1:5 to 1:50. In the dyeing method of the present invention, the dyeing method per se can be conducted according to a known method. A fiber material capable of being dyed by the dyeing method of the present invention includes cotton, hemp, rayon, polynosic, cupra, lyocell fibers and the like, their mutual mixtures, their blended fibers with other fibers such as polyester fibers, acetate fibers, polyacrylonitrile fibers, wool, silk, polyamide fibers such as nylon and the like, and cowoven fabrics thereof. The disazo compound and the reactive dye composition according to the present invention are very useful since they have always high dyeing property under the condition of a bath pH of 5 to 9 and a temperature of generally 90 to 140° C., more preferably 95 to 135° C. and therefore they can dye blended fibers containing cellulosic fibers, especially blended polyester/cotton fibers in the co-existence of a disperse dye by a reasonable one bath/one step dyeing method. For example, the dyeing of blended polyester/cotton fibers in a one bath/one step dyeing method is conducted as follows: The disazo compound or the reactive dye composition of the present invention and a disperse dye(s) are formulated depending on desired hue and concentration. Additionally, a pH controlling agent for keeping a dye bath at a pH of 5 to 9, preferably 6 to 8 [for example, 0.1 to 5 g/L of Kayaku Buffer P-7 (trade name of Nippon Kayaku Co., Ltd.)], an inorganic salt [for example, 5 to 80 g/L of anhydrous sodium sulfate] and if necessary, a dispersing and leveling agent [for example, 0.1 to 5 g/L of KP leveller RP (trade name of Nippon Kayaku Co., Ltd.)] are added to prepare a dye bath with a bath ratio of 1:5 to 1:50. After a fabric to be dyed is introduced in the dye bath, for example, the temperature of the dye bath is increased to 120 to 140° C. over 20 to 40 minutes and the dyeing is conducted at the same temperature for 20 to 60 minutes. After the dyeing step is finished, the resultant dyed fabric is washed with water and/or hot water and then soaped in a soaping bath containing 0.1 to 5 g/L of a commercially available soaping agent to complete the dyeing. Further, the disazo compound and the reactive dye composition according to the present invention have excellent property that they show high dyeing property at a relatively low temperature around 100° C. Therefore, the disazo compound and the reactive dye composition of the present invention can dye polyacrylonitrile fibers which are generally dyed with a basic dye at about 100° C. in a dye bath having an acidic to neutral pH, or wool, silk and blended fabrics comprising cellulose fibers and polyamide fibers (for example, nylon and the like) which are dyed with an acid dye. The blended fibers can be dyed in one bath dyeing method using the above compound or composition. For example, the one bath dyeing of blended nylon/cotton fibers is conducted as follows: The disazo compound or the reactive dye composition of the present invention and an acid dye(s) are formulated depending on desired hue and concentration. Additionally, a pH controlling agent for keeping a dye bath at a pH of 5 to 9, preferably 6 to 8 [for example, 0.1 to 5 g/L of Kayaku Buffer P-7 (trade name of Nippon Kayaku Co., Ltd.)], an inorganic salt [for example, 5 to 40 g/L of anhydrous sodium sulfate] and if necessary, an anti-contamination agent for nylon [for example, 0.1 to 5 g/L of Sunresist NR-100L (trade name of Nikka Chemical Co., Ltd.)] are added to prepare a dye bath with a bath ratio of 1:5 to 1:50. After a fabric to be dyed is introduced in the dye bath, for example, a temperature of the dye bath is increased to 90 to 110° C., preferably 95 to 110° C. over 20 to 60 minutes and the dyeing is conducted at the same temperature for 20 to 60 minutes. If necessary, 0 to 40 g/L of anhydrous sodium sulfate is further added during a dyeing step. After the dyeing step is finished, the resultant dyed fabric is washed with water and/or hot water and then soaped in a soaping bath containing 0.1 to 5 g/L of a commercially available soaping agent to complete the dyeing. A fiber material capable of being dyed with the disazo compound or the reactive dye composition of the present invention is not limited to the materials mentioned above. A fiber material essentially consisting of cellulosic fibers can be dyed in the same way as that described above. Upon dyeing, the conventional method comprising treating a fiber material in a dye bath at a temperature of generally 40 to 100° C., adding an acid binder in the dye bath and then dyeing can be employed. Alternatively, the so-called all-in-one dyeing method comprising previously adding to a dye bath an acid binder or a buffer in an amount for keeping the dye bath at a pH of 5 to 9 and then dyeing can be employed. For example, when cellulosic fibers such as cotton and the like are dyed, a dye bath is first prepared by mixing the disazo compound or the reactive dye composition of the present invention in an amount which is varied depending on desired hue and concentration, a pH controlling agent for keeping the dye bath at a pH of 5 to 9, preferably 6 to 8 [for example, 0.1 to 5 g/l of Kayaku Buffer P-7 (trade name of Nippon Kayaku Co., Ltd., a pH controlling agent)] and an inorganic acid, [for example, 5 to 100 g/L of anhydrous sodium sulfate] in a bath ratio of 1:5 to 1:50. After a material to be dyed is introduced in the dye bath, for example a temperature of the dye bath is increased to generally 90 to 120° C., suitably 95 to 110° C. over 20 to 40 minutes and the dyeing is conducted at the same temperature for 20 to 60 minutes. As the pH controlling agent used in the dyeing of cellulosic fibers, a pH sliding agent by which a pH is varied with time due to the change in temperature and the like during a dyeing step, for example 0.1 to 5 g/L of Kayaslide PH-509 or Kayaslide PH-608 (Kayaslide is a trade name of Nippon Kayaku Co., Ltd., a pH controlling or sliding agent), can be used. After the dyeing step is finished, the resultant dyed material is washed with water and/or hot water and then soaped in a soaping bath containing 0.1 to 5 g/L of a commercially available soaping agent to complete the dyeing. The disazo compound and the reactive dye composition of the present invention has high dyeing property even at a low temperature range around 100° C., shows a small change in hue even if dyeing conditions are varied, dyes with excellent dyeing reproducibility and washes off a non-fixed dye satisfactorily. Accordingly, they can dye a fiber material without inviting the problem of a color transfer of a non-fixed dye to the fabric material during a drying step. Further, the disazo compound and the reactive dye composition of the present invention are very excellent in solid dyeing of blended fibers comprising a mutual mixture of cellulosic fibers, for example blended cotton/rayon fibers. By using the disazo compound and the reactive dye composition of the present invention, problems caused by a delicate and complicated addition of an acid binder during a dyeing step such as a lowering in color yield due to hydrolysis, an unlevel dyeing, a color breakup upon dyeing using a mixed dye and the like can be resolved. Simultaneously, the dyeing can be conducted with improved efficiency and high reproducibility. Upon dyeing, the disazo compound of the present invention can be used singly or in mixture. If desired, the disazo compound of the present invention can be used in combination with a reactive dye other than the disazo compound of the present invention, a disperse dye and/or an acid dye. An acid binder and a pH controlling agent (sometimes referred to as “a buffer”) usable in the dyeing method of the present invention are not especially limited. Example of an acid binder includes sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, sodium metasilicate, trisodium phosphate, tripotassium phosphate, sodium pyrophosphate, potassium pyrophosphate, sodium trichloroacetate and the like. Example of a pH controlling agent includes commercially available pH controlling agents, acetic acid+sodium acetate, monosodium phosphate+disodium phosphate, monopotassium phosphate+disodium phosphate, maleicacid+borax, boric acid+borax, and the like. They can be used singly or in a suitable mixture, if necessary. If necessary during a dyeing step, known dyeing auxiliaries such as a dispersing agent (Demol N, Vanilex RN and KP Leveller RP, trade names of Nippon Kayaku Co., Ltd., a dispersing and leveling agent for disperse dyes), a leveling agent (Newbon TS, trade name of Nikka Chemical Co., Ltd., a leveling agent for specific anionic nylon; Miguregal AM, trade name of Nikka Chemical Co., Ltd., a leveling agent for disperse dyes), a carrier agent (Carrier 430, trade name of Nikka Chemical Co., Ltd., a carrier agent, and the like), a metal sequestrant (Kayachelator N-1, trade name of Nippon Kayaku Co., Ltd., a neutral metal sequestrant, and the like), an anti-reduction agent (Polymin L-New, Miss. powder and the like) and the like can be used. The disazo compound represented by the above formula (1) and the reactive dye composition of the present invention have always high dyeing property as a reactive dye over a wide temperature range in the presence of a buffering agent capable of keeping a dye bath at a pH of 5 to 9. Therefore, they can dye cellulosic fibers with high color yield and excellent properties including build-up property, levelness and reproducibility. Owing to these properties, the disazo compound and the reactive dye composition of the present invention are very effective for dyeing blended fibers containing cellulosic fibers, especially blended polyester/cotton fibers in the co-existence of a disperse dye by a reasonable one bath/one step dyeing method. Of course, a material to be dyed is not limited to the above-mentioned materials. The disazo compound and the reactive dye composition of the present invention can also dye cellulosic fibers such as cotton, hemp, rayon, polynosic, cupra, lyocell fibers or the like and their mixture with excellent fastnesses in various aspects such as a fastness to light, a fastness to chlorinated water, a fastness to washing and the like and without inviting any problem such as thermal discoloration, phototrophy and the like. EXAMPLES The present invention will be described in further detail by referring to the following examples. All parts and percentages referred to herein are by weight unless otherwise indicated. Example 1 2-Amino-4,8-naphthalene-disulfonic acid was diazotized and coupled with 3-acetylaminoaniline. Then, the thus-coupled product was salted out with sodium chloride and filtered to separate 23.2 parts of 2-(4-amino-2-acetylaminophenylazo)-4,8-naphthalene disulfonic acid. Sodium hydroxide was added thereto and dissolved in 300 parts of water. After 9.3 parts of cyanuric chloride was added, a first condensation was conducted at a temperature of 0 to 5° C. and a pH of 5 to 7. Sodium carbonate was added during the reaction to complete the reaction. Then, a solution of 13.8 parts of 4-(4-aminophenylazo) benzenesulfonic acid in 200 parts of water was added and a second condensation was conducted at a temperature of 50° C. and a pH of 6 to 7. Next, a suspension of 12 parts of nicotinic acid in 100 parts of water was added and then the reaction was continued at a temperature of 95° C. and a pH of 6 to 7 until completion. Thereafter, the reaction was salted out, thereby 41 parts of the disazo compound which in a free acid form is represented by the formula (20) is obtained. This compound was dissolved in water very well. The resultant solution had a maximum absorption wavelength of 365 nm. The compound 4-(4-aminophenylazo)benzenesulfonic acid used in this example was obtained by coupling aniline previously sulfomethylated with formalin and sodium hydrogensulfite with diazotized 4-aminobenezenesulfonic acid, hydrolyzing the sulfomethyl group under an alkaline condition, salting out and separating. Example 2 2-Amino-3,6,8-naphthalene-trisulfonic acid was diazotized and coupled with 3-acetylaminoaniline. Then, the thus-coupled product was salted out with sodium chloride and filtered to separate 27.2 parts of 2-(4-amino-2-acetylaminophenylazo)-3,6,8-naphthalene trisulfonic acid. Sodium hydroxide was added thereto and dissolved in 300 parts of water. After 9.3 parts of cyanuric chloride was added, a first condensation was conducted at a temperature of 0 to 5° C. and a pH of 5 to 7. Sodium carbonate was added during the reaction to complete the reaction. Then, a solution of 13.8 parts of 4-(4-aminophenylazo)-benzenesulfonic acid in 200 parts of water was added and a second condensation was conducted at a temperature of 50° C. and a pH of 6 to 7. Next, a suspension of 12 parts of nicotinic acid in 100 parts of water was added and then there action was continued at a temperature of 95° C. and a pH of 6 to 7 until completion. Thereafter, the reaction was salted out, thereby 44 parts of the disazo compound which in a free acid form is represented by the formula (21) is obtained. This compound was dissolved in water very well. The resultant solution had a maximum absorption wavelength of 377 nm. Examples 3 to 18 Disazo compounds which in free acid forms are represented by the following general formula (22) and having substituents as shown in Table 2 were synthesized in the same way as described in Example 1. Table 2 also shows a maximum absorption wavelength (nm) of a solution of each of the resultant compounds. TABLE 2 maximum positions position absorp- of SO 3 H of SO 3 H tion group on group on wave- naphtha- benzene length Ex. lene ring R 1 R 2 ring R 3 R 4 (nm) 3 4, 8 H H 4 H H 355 4 4, 8 H NHCOCH 3 3 OCH 3 H 366 5 4, 8 H OCH 3 3 OCH 3 H 368 6 4, 8 H NHCONH 2 4 H H 373 7 4, 8 H NHCONH 2 4 H NHCONH 2 375 8 4, 8 OCH 3 CH 3 4 H NHCOCH 3 378 9 6, 8 H NHCOCH 3 4 H H 369 10 6, 8 H NHCOCH 3 3 H CH 3 370 11 6, 8 H NHCONH 2 4 H NHCONH 2 376 12 6, 8 OCH 3 H 3 OCH 3 H 366 13 6, 8 H CH 3 3 H CH 3 368 14 3, 6 H NHCOCH 3 4 H H 367 15 3, 6 H NHCONH 2 3 H CH 3 374 16 3, 6 H CH 3 4 H CH 3 366 17 5, 7 H NHCOCH 3 4 H H 362 18 5, 7 H NHCONH 2 4 H NHCOCH 3 370 Examples 19 to 29 Disazo compounds which in free acid forms are represented by the following general formula (23) and having substituents as shown in Table 3 were synthesized in the same way as described in Example 2. Table 3 also shows a maximum absorption wavelength (nm) of a solution of each of the resultant compounds. TABLE 3 maximum positions position absorp- of SO 3 H of SO 3 H tion group on group on wave- naphtha- benzene length Ex. lene ring R 1 R 2 ring R 3 R 4 (nm) 19 3, 6, 8 H H 4 H H 371 20 3, 6, 8 H NHCOCH 3 3 OCH 3 H 379 21 3, 6, 8 H OCH 3 3 OCH 3 H 381 22 3, 6, 8 H NHCONH 2 4 H H 384 23 3, 6, 8 H NHCONH 2 4 H NHCONH 2 385 24 3, 6, 8 OCH 3 CH 3 4 H NHCOCH 3 390 25 4, 6, 8 H NHCOCH 3 4 H H 371 26 4, 6, 8 H NHCOCH 3 3 H CH 3 372 27 4, 6, 8 H NHCONH 2 4 H NHCONH 2 379 28 4, 6, 8 H CH 3 3 H CH 3 369 29 4, 6, 8 OCH 3 H 4 H NHCOCH 3 368 Example 30 A dye bath was prepared by adding water to 0.5 part of the disazo compound obtained in Example 2, 60 parts of mirabilite, 2 parts of disodium phosphate, 0.5 part of monopotassium phosphate and 1 part of sodium m-nitrobenzene sulfonic acid group such that the total volume was 1000 parts. The pH value of this dye bath was 7. 50 Parts of a knitted cotton fabric was introduced in the dye bath. After the temperature of the dye bath was increased to 130° C. over 30 minutes, the dyeing was conducted at this temperature for 40 minutes. The pH value of the dye bath after dyeing was 7, the same as that before dyeing. Then, the fabric was washed with water, soaped in an aqueous solution containing an anionic surfactant at a temperature of 100° C., washed with water and dried, there by a yellow-dyed fabric was obtained. The thus-dyed fabric was levelly dyed at a high color yield. It did show neither thermal discoloration nor phototropy. Its fastnesses to light, chlorinated water and washing were good. Example 31 A dye bath was prepared by adding water to 0.3 part of the disazo compound obtained in Example 1, 0.15 part of Kayacelon Yellow E-3GL (a disperse dye of Nippon Kayaku Co., Ltd.), 0.05 part of Kayacelon Yellow E-BRL conc (a disperse dye of Nippon Kayaku Co., Ltd.), 60 parts of mirabilite, 1 part of sodium m-nitrobenzenesulfonate, 2 parts of a condensate of naphthalenesulfonic acid with formalin (a dispersing agent), 2 parts of disodium phosphate and 0.5 part of monopotassium phosphate such that the total volume was 1000 parts. The pH value of this dye bath was 7. 50 Parts of a fabric comprising blended polyester/cotton (50/50) fibers was introduced in the dye bath. After the temperature of the dye bath was increased to 130° C. over 30 minutes, the dyeing was conducted at this temperature for 60 minutes. Then, the fabric was washed with water, soaped in an aqueous solution containing an anionic surfactant at a temperature of 100° C., washed with water and dried, thereby a yellow-dyed fabric was obtained. The thus-dyed fabric was levelly dyed irrespective of the nature of the fibers at a high color yield. Its fastnesses to light, chlorinated water and washing were good. Example 32 A dye bath was prepared by adding water to 0.3 part of the disazo compound obtained in Example 1, 0.15 part of Kayacelon Yellow E-3GL, 0.05 part of Kayacelon Yellow E-BRL conc, 60 parts of mirabilite, 2 parts of a condensate of naphthalenesulfonic acid with formalin (a dispersing agent), 3 parts of Mignol RP100 (a special emulsifying agent of Ipposha Oil Industries Co., Ltd.), 2 parts of disodium phosphate and 0.5 part of monopotassium phosphate such that the total volume was 1000 parts. The pH value of this dye bath was 7. 50 Parts of a fabric comprising blended polyester/cotton (50/50) fibers was introduced in the dye bath. After the temperature of the dye bath was increased to 130° C. over 30 minutes, the dyeing was conducted at this temperature for 60 minutes. Then, the fabric was washed with water, soaped in an aqueous solution containing an anionic surfactant at a temperature of 100° C., washed with water and dried, thereby a yellow-dyed fabric was obtained. The thus-dyed fabric was levelly dyed irrespective of the nature of the fabrics at a high color yield similar to the dyed fabric of Example 31. Its various fastnesses were good. Example 33 A dye bath was prepared by adding water to 0.5 part of the disazo compound obtained in Example 2, 60 parts of mirabilite, 2 parts of disodium phosphate and 0.5 part of monopotassium phosphate such that the total volume was 1000 parts. The pH value of this dye bath was 7. 50 Parts of a knitted cotton fabric was introduced in the dye bath. After the temperature of the dye bath was increased to 95° C. over 30 minutes, the dyeing was conducted at this temperature for 60 minutes. The pH value of the dye bath after dyeing was 7, the same as that before dyeing. Then, the fabric was washed with water, soaped in an aqueous solution containing an anionic surfactant at a temperature of 100° C., washed with water and dried, thereby a yellow-dyed fabric was obtained. The thus-dyed fabric was levelly dyed at a high color yield similar to the dyed fabric of Example 30. Its various fastnesses were good. Example 34 A dye bath was prepared by adding water to 0.5 part of the disazo compound obtained in Example 2, 0.5 part of Kayacelon React Blue CN-MG (reactive dye of Nippon Kayaku Co., Ltd.), 60 parts of mirabilite, 2 parts of disodium phosphate and 0.5 part of monopotassium phosphate such that the total volume was 1000 parts. The pH value of this dye bath was 7. 50 Parts of a knitted cotton fabric was introduced in the dye bath. After the temperature of the dye bath was increased to 95° C. over 30 minutes, the dyeing was conducted at this temperature for 60 minutes. The pH value of the dye bath after dyeing was 7, the same as that before dyeing. Then, the fabric was washed with water, soaped in an aqueous solution containing an anionic surfactant at a temperature of 100° C., washed with water and dried, thereby a green-dyed fabric was obtained. During the dyeing step, the dyes mixed were compatible each other. A hue of the fabric to be dyed remained similarly and the resultant dyed fabric was levelly dyed without inviting any problem such as color breakup and unlevel dyeing. Dyeing reproducibility was excellent. Example 35 A dye bath was prepared by adding water to 0.3 part of the disazo compound obtained in Example 1, 0.2 part of Kayanol Milling Yellow 5GW (an acid dye of Nippon Kayaku Co., Ltd.), 0.04 part of Kayanol Milling Yellow RW new (an acid dye of Nippon Kayaku Co., Ltd.), 30 parts of mirabilite, 2 parts of disodium phosphate and 0.5 part of monopotassium phosphate such that the total volume was 1000 parts. The pH value of this dye bath was 7. 50 Parts of a cowoven fabric comprising blended nylon/cotton (50/50) fibers was introduced in the dye bath. After the temperature of the dye bath was increased to 100° C. over 30 minutes, the dyeing was conducted at this temperature for 60 minutes. Then, the fabric was washed with water, soaped in an aqueous solution containing an anionic surfactant at a temperature of 100° C., washed with water and dried, thereby a yellow-dyed fabric was obtained. The thus-dyed fabric was levelly dyed irrespective of the nature of the fibers at a high color yield. Example 36 A dye bath was prepared by adding water to the combination and amounts of dyes (compounds) shown in Table 4 (Combination and amounts (in parts) of compounds), 50 parts of anhydrous sodium sulfate and 1 part of Kayaku Buffer P-7 (a pH controlling agent) such that the total volume was 1000 parts. The pH value of this dye bath was 7.2. 50 Parts of a knitted cotton fabric was introduced in the dye bath. After the temperature of the dye bath was increased to 100° C. over 40 minutes, the dyeing was conducted at this temperature for 30 minutes. The pH value of the dye bath remaining after dyeing was 7.0. Then, the fabric was washed with water and hot water successively, soaped in 1000 parts of an aqueous solution containing 1 part of a commercially available soaping agent at a temperature of 100° C. for 10 minutes, washed with water and dried, thereby a brown-dyed fabric was obtained. In each of Comparative Examples 1 to 3, the dyeing was conducted in the same way as that described in Example 36, provided that the combination and amounts of dyes (compounds) shown in Table 4, was used, thereby a brown-dyed fabric was obtained. TABLE 4 reactive dyes yellow red blue formula amount formula amount formula amount Ex. 36 (11) 0.20 (7) 0.10  (9) 0.12 (10) 0.08 Comparative (24) 0.20 (7) 0.10  (9) 0.12 Ex. 1 (10) 0.08 Comparative (25) 0.05 (7) 0.10  (9) 0.12 Ex. 2 (26) 0.15 (10) 0.08 Comparative (26) 0.15 (7) 0.10  (9) 0.12 Ex. 3 (24) 0.05 (10) 0.08 The compounds which in free acid forms are represented by the formulae (24), (25) and (26), respectively used in Comparative Examples 1 to 3 are shown below. Next, methods for testing and judging dependency on dyeing conditions, fixing efficiency and washing property will be described below. Dependency on Dyeing Conditions [Salt Concentration] The dyeing was conducted in the same way as that described in Example 36 except that 25 parts of anhydrous sodium sulfate was used instead of 50 parts of anhydrous sodium sulfate. Method of judgment: The difference in hue between the fabric dyed with 50 parts of anhydrous sodium sulfate and the fabric dyed with 25 parts of anhydrous sodium sulfate was judged by the naked eye. ◯ small hue difference Δ medium hue difference × significant hue difference [pH] The dyeing was conducted in the same way as that described in Example 36 except that 1 part of a mixture of boric acid and borax (7:3) was used instead of 1 part of Kayaku Buffer P-7 (a pH controlling agent). The pH value of the dye bath was 8.3. The pH value of the dye bath remaining after dyeing was 8.0. Method of judgment: The difference in hue between the fabric dyed in a dye bath of pH 7 and the fabric dyed in a dye bath of pH 8 was judged by the naked eye. ◯ small hue difference Δ medium hue difference × significant hue difference [Temperature] The dyeing was conducted in the same way as that described in Example 36 except that the dyeing temperature of 95° C. was used instead of the dyeing temperature of 100° C. Method of judgment: The difference in hue between the fabric dyed at the temperature of 100° C. and the fabric dyed at the temperature of 95° C. was judged by the naked eye. ◯ small hue difference Δ medium hue difference × significant hue difference Fixing Efficiency The dyeing was started in the same way as that described in Example 36. After the dyeing was conducted at a temperature of 100° C. for 30 minutes, the thus-dyed fabric was taken out, immediately dehydrated and dried, thereby a non-washed fabric was obtained. Method of judgment: The difference in hue between the above non-washed fabric and the dyed fabric after washing obtained in Example 36 was judged by the naked eye. The fixing efficiency means a ratio of (a fixed dye)/the total of (a fixed dye and a non-fixed dye) on a dyed fabric. ◯ hue difference is small and lowering in concentration is minor; It indicates that fixing efficiency of each of yellow, red and blue reactive dyes is high. × blue hue is strong and lowering in concentration is significant; It indicates that fixing efficiency of a yellow reactive dye is low. When a fixing efficiency of certain hue component is lower in a mixed dyeing, a reproducibility upon dyeing becomes poor. Washing Property The dyeing was started in the same way as that described in Example 36. After the dyeing was conducted at a temperature of 100° C. for 30 minutes, the thus-dyed fabric was taken out, washed with water, soaped in 1000 parts of an aqueous solution containing 1 part of a commercially available soaping agent at 95° C. for 10 minutes and then washed with water, thereby a dyed fabric was obtained. Immediately the dyed fabric under a wet condition was folded in four. A cotton broadcloth (white cloth) was put on an uppermost of the folded fabric and ironed at 130° C. for three minutes so that the fabric and the cloth were subjected to heat treatment under pressure. Method of judgment: The degree of color transfer of a non-fixed dye to a cotton broadcloth (white cloth) by this heat treatment was judged by the naked eye. ◯ Color transfer of an on-fixed dye to a white cloth is minor. The color similar to that of the dyed fabric is transferred. × Color transfer of a non-fixed dye, especially a yellow dye is significant. When a washing property is poor and a color transfer of a non-fixed dye during a drying step of a dyed fabric is significant, levelness or fastnesses become worse. Dependency on dyeing conditions, fixing efficiency and washing property of Example 36 and Comparative Examples 1 to 3 were compared. Results are shown in Table 5. TABLE 5 dependency on dyeing condition salt fixing washing concentration pH temperature efficiency property Ex. 36 ◯ ◯ ◯ ◯ ◯ Comparative Δ X Δ X X Ex. 1 Comparative ◯ X X X X Ex. 2 Comparative ◯ X Δ X X Ex. 3 Only in the case of using the combination of compounds for dyeing as shown in Example 36, each dye component of yellow, red and blue reactive dyes showed the same dyeing property. Even if the dyeing conditions such as salt concentration, pH of a dye bath, dyeing temperature and the like were varied, a change in hue was minor, a fixing efficiency was high and a dyeing reproducibility was also excellent. Further, a color transfer of a non-fixed dye was not observed and a washing property was excellent. In addition, the dyeing rates of dye components agreed well with each other and therefore a very level dyeing was attained. Examples 37 to 46 The dyeing was conducted in the same way as that described in Example 36 except that the combination and amounts of compounds as shown in Table 6 was used. TABLE 6 reactive dyes yellow red blue formula amount formula amount formula amount Ex. 37 (27) 0.20  (7) 0.10  (9) 0.12 (10) 0.08 Ex. 38 (11) 0.16  (7) 0.10  (9) 0.12 (25) 0.04 (10) 0.08 Ex. 39 (11) 0.16  (7) 0.10  (9) 0.12 (26) 0.04 (10) 0.08 Ex. 40 (11) 0.20  (8) 0.10  (9) 0.12 (10) 0.08 Ex. 41 (11) 0.20  (7) 0.05  (9) 0.12 (8) 0.05 (10) 0.08 Ex. 42 (11) 0.20  (7) 0.07  (9) 0.12 (19) 0.03 (10) 0.08 Ex. 43 (11) 0.20  (7) 0.10  (9) 0.02 Ex. 44 (11) 0.02  (7) 0.02 (10) 2.00 Ex. 45 (11) 1.00  (7) 1.00 — — Ex. 46 (11) 0.50 — —  (9) 0.30 (10) 0.20 The compound which in a free acid form is represented by the formula (27) used in Example 37 is shown below. The hue of the resultant dyed fabric in Examples 37 to 46 was a dark pink color (Example 43), a navy blue color (Example 44), a scarlet red color (Example 45), a green color (Example 46) or a brown color (other examples). In either of the combinations of Examples 37 to 46, the dyeing rates of dye components during a dyeing step agreed well with each other, a fixing efficiency was high and a washing property was excellent. Further, each of the resultant dyed fabrics was excellent in levelness and various fastnesses such as a fastness to light, a fastness to light with perspiration, a fastness to chlorinated water and the like. Examples 47 to 50 A dye bath was prepared by adding water to the combination and amounts of dyes (compounds) shown in Table 7, 50 parts of anhydrous sodium sulfate and 1 part of Kayaslide PH-509 (a pH sliding agent of Nippon Kayaku Co., Ltd.) such that the total volume was 1000 parts. The pH value of this dye bath was 5.2. 50 Parts of a knitted cotton fabric was introduced in the dye bath. After the temperature of the dye bath was increased to 95° C. over 40 minutes, the dyeing was conducted at this temperature for 30 minutes. The pH value of the dye bath remaining after dyeing was 8.7. Then, the fabric was washed with water and hot water successively, soaped in 1000 parts of an aqueous solution containing 1 part of a commercially available soaping agent at a temperature of 100° C. for 10 minutes, washed with water and dried, thereby a dyed fabric was obtained. Examples 51 to 54 A dye bath was prepared by adding water to the combination and amounts of dyes (compounds) shown in Table 7, 50 parts of anhydrous sodium sulfate and 1 part of Kayaku Buffer P-7 (a pH controlling agent of Nippon Kayaku Co., Ltd.) such that the total volume was 1000 parts. The pH value of this dye bath was 7.2. 50 Parts of a knitted cotton fabric was introduced in the dye bath. After the temperature of the dye bath was increased to 120° C. over 40 minutes, the dyeing was conducted at this temperature for 30 minutes. The pH value of the dye bath remaining after dyeing was 6.9. Then, the fabric was washed with water and hot water successively, soaped in 1000 parts of an aqueous solution containing 1 part of a commercially available soaping agent at a temperature of 100° C. for 10 minutes, washed with water and dried, thereby a dyed fabric was obtained. TABLE 7 reactive dyes yellow red blue formula amount formula amount formula amount Ex. 47 (11) 0.18 (7) 0.12  (9) 0.11 (10) 0.08 Ex. 48 (11) 0.20 (8) 0.12  (9) 0.11 (10) 0.08 Ex. 49 (11) 1.10 (7) 0.90 — — Ex. 50 (11) 0.55 — —  (9) 0.30 (10) 0.20 Ex. 51 (11) 0.18 (7) 0.12  (9) 0.11 (10) 0.08 Ex. 52 (11) 0.20 (8) 0.12  (9) 0.11 (10) 0.08 Ex. 53 (11) 1.10 (7) 0.90 — — Ex. 54 (11) 0.55 — —  (9) 0.30 (10) 0.20 The hue of the resultant dyed fabric in Examples 47 to 50 was a brown color (Examples 47 and 48), a scarlet red color (Example 49) and a green color (Example 50). In either of the combinations of Examples 47 to 50, the dyeing rates of dye components during a dyeing step agreed well with each other, a fixing efficiency was high and a washing property was also excellent. Further, each of the resultant dyed fabrics was excellent in levelness and various fastnesses such as a fastness to light, a fastness to light with perspiration, a fastness to chlorinated water and the like. The hue of the resultant dyed fabric in Examples 51 to 54 was a brown color (Examples 51 and 52), a scarlet red color (Example 53) and a green color (Example 54). In either of the combinations of Examples 51 to 54, the dyeing rates of dye components during a dyeing step agreed well with each other, a fixing efficiency was high and a washing property was also excellent. And, each of the resultant dyed fabrics was excellent in levelness and various fastnesses such as a fastness to light, a fastness to light with perspiration, a fastness to chlorinated water and the like. Example 55 A dye bath was prepared by adding water to the combination and amounts of dyes (compounds) shown in Table 8, 50 parts of anhydrous sodium sulfate and 1 part of Kayaku Buffer P-7 (a pH controlling agent of Nippon Kayaku Co., Ltd.) such that the total volume was 1000 parts. The pH value of this dye bath was 7.2. 50 Parts of a cowoven fabric comprising blended cotton/rayon (50%/50%) fibers was introduced in the dye bath. After the temperature of the dye bath was increased to 100° C. over 40 minutes, the dyeing was conducted at this temperature for 30 minutes. The pH value of the dye bath remaining after dyeing was 7.0. Then, the fabric was washed with water and hot water successively, soaped in 1000 parts of an aqueous solution containing 1 part of a commercially available soaping agent at a temperature of 100° C. for 10 minutes, washed with water and dried, thereby a dyed fabric was obtained. In Comparative Examples 4 and 5, the dyeing was conducted in the same way as that described in Example 55 except that the combination and amounts of dyes (compounds) shown in Table 8, was used, thereby a dyed fabric was obtained. TABLE 8 reactive dyes yellow red blue formula amount formula amount formula amount Ex. 55 (11) 0.20 (7) 0.15  (9) 0.12 (10) 0.08 Comparative (25) 0.05 (7) 0.15  (9) 0.12 Ex. 4 (26) 0.15 (10) 0.08 Comparative (26) 0.15 (7) 0.15  (9) 0.12 Ex. 5 (24) 0.05 (10) 0.08 Solid Dyeing Property of Cotton/Rayon Fibers Method of judgment: A solid dyeing of cotton/rayon fibers dyed in one bath dyeing method was judged by the naked eye. ◯ excellent solid dyeing × inferior solid dyeing Hues of cotton and rayon fibers in the resultant dyed fabric and a solid dyeing property of Example 55 and Comparative Examples 4 and 5 are shown in Table 9. TABLE 9 hue solid dyeing cotton fibers rayon fibers property Ex. 55 brown brown ◯ Comparative brown purple - violet X Ex. 4 Comparative brown purple - violet X Ex. 5 Only in the case of using the combination of compounds for dyeing as shown in Example 55, each dye component of yellow, red and blue reactive dyes showed the same dyeing property on rayon fibers. In this case, a solid dyeing property of cotton and rayon fibers dyed in one bath dying method was very excellent. Thus, the reactive dye composition of the present invention is very effective in solid dyeing of blended cotton/rayon fibers and a cowoven fabric thereof. Example 56 A dye bath was prepared by adding water to 0.4 part of the compound of the formula (11), 0.1 part of the compound of the formula (7), 0.07 part of the compound of the formula (9), 0.05 part of the compound of the formula (10), 0.22 part of Kayalon Microester Yellow AQ-LE (trade name of Nippon Kayaku Co., Ltd., a disperse dye for polyester fibers), 0.15 part of Kayalon Microester Red AQ-Le (trade name of Nippon Kayaku Co., Ltd., a disperse dye for polyester fibers), 0.05 part of Kayalon Microester Blue AQ-LE (trade name of Nippon Kayaku Co., Ltd., a disperse dye for polyester fibers), 60 parts of anhydrous sodium sulfate and 1 part of Kayaku Buffer P-7 (a pH controlling agent of Nippon Kayaku Co., Ltd.) such that the total volume was 1000 parts. The pH value of this dye bath was 7.2. 50 Parts of a fabric comprising blended cotton/polyester fibers were introduced in the dye bath. After the temperature of the dye bath was increased to 130° C. over 40 minutes, the dyeing was conducted at this temperature for 40 minutes. The pH value of the dye bath remaining after dyeing was 6.9. Then, the fabric was washed with water and hot water successively, soaped in 1000 parts of an aqueous solution containing 1 part of a commercially available soaping agent at a temperature of 100° C. for 10 minutes, washed with water and dried, thereby a yellowish brown-dyed fabric was obtained. When the dye composition of Example 56 was used, a washing property during a washing step was excellent. The resultant dyed fabric was levelly dyed irrespective of the nature of fibers. Various fastnesses such as a fastness to light, a fastness to light with perspiration, a fastness to washing and the like were also excellent. Example 57 A dye bath was prepared by adding water to 1 part of the compound of the formula (11), 0.35 part of the compound of the formula (7), 0.16 part of the compound of the formula (9), 0.11 part of the compound of the formula (10), 0.3 part of Kayanol Yellow NFG (trade name of Nippon Kayaku Co., Ltd., an acid dye for nylon fibers), 0.16 part of Kayanol Floxine NK (trade name of Nippon Kayaku Co., Ltd., an acid dye for nylon fibers), 0.09 part of Kayanol Blue N2G (trade name of Nippon Kayaku Co., Ltd., an acid dye for nylon fibers), 60 parts of anhydrous sodium sulfate and 1 part of Kayaku Buffer P-7 (a pH controlling agent of Nippon Kayaku Co., Ltd.) such that the total volume was 1000 parts. The pH value of this dye bath was 7.3. 50 Parts of a fabric comprising blended cotton/nylon fibers was introduced in the dye bath. After the temperature of the dye bath was increased to 100° C. over 40 minutes, the dyeing was conducted at this temperature for 40 minutes. The pH value of the dye bath remaining after dyeing was 7.1. Then, the fabric was washed with water and hot water successively, soaped in 1000 parts of an aqueous solution containing part of a commercially available soaping agent at a temperature of 80° C. for 10 minutes, washed with water and dried, thereby a brown-dyed fabric was obtained. When the dye composition of Example 57 was used, a washing property during a washing step was excellent. The resultant dyed fabric was levelly dyed irrespective of the nature of fibers. A fastness to light and a fastness to light with perspiration were excellent. Example 58 The compound of the formula (11) as a yellow reactive dye, the compound of the formula (7) as a red reactive dye and the compounds of formulae (9) and (10) as blue reactive dyes were mixed in a ratio of 50%: 25%: 15%: 10% to obtain a reactive dye composition of the present invention. The dyeing was conducted in the same way as that described in Example 36 using 0.5 part of this reactive dye composition, thereby a brown-dyed fabric was obtained. When the reactive dye composition of Example 58 was used, the dyeing rates of dye components during a dyeing step agreed well with each other. A fixing efficiency was high and a washing property was also excellent. The resultant dyed fabric was levelly dyed and excellent in fastnesses such as a fastness to light, a fastness to light with perspiration, a fastness to chlorinated water and the like. EFFECT OF THE INVENTION When cellulosic fibers are dyed with the disazo compound of the present invention, the dyeing with a high color yield, excellent fastnesses in various aspects, good thermal discoloring and good phototropy can be conducted with good levelness and reproducibility. Further, cellulosic fibers can be dyed with excellent reproducibility by an efficient all-in-one method. A fabric comprising blended polyester/cotton fibers can be dyed in the co-existence of a disperse dye by a reasonable one bath/one step method. In addition, cellulose or cellulose-containing fibers can be efficiently dyed with excellent washing property, excellent reproducibility, good levelness and high fastnesses, by using the reactive dye composition of the present invention.

The present invention provides a disazo compound which in a free acid form is represented by the formula (1) and which has high ability to dye cellulosic fibers and attains efficient dyeing with satisfactory reproducibility; and a method of dyeing cellulosic fibers with the compound. Also provided are: a reactive dye composition comprising a compound represented by the formula (1) and a specific red reactive dye and/or a specific blue reactive dye; and a method of dyeing cellulosic fibers with the composition. In the formula, R 1 and R 3 each represents hydrogen atom or methoxy group; R 2 and R 4 each represents hydrogen atom, methyl group, acetylamino group, ureido group, etc.; and m is 2 or 3.

FIELD OF THE INVENTION This invention relates generally to abrasive articles and more particularly to abrasive wheels having a mounting hub permanently affixed thereto with the combination adapted for quick attachment and release to an appropriate portable power tool. The abrasive wheel may be disposed of when spent. BACKGROUND OF THE INVENTION The use of rotatably driven abrasive articles is widespread and familiar in our industrial society. One of the more serious problems encountered in the use of such devices resides in the provision of effective means for preventing undesired or accidental disassociation of the article from the shaft, spindle or other rotatable drive means on which it is mounted. This problem is particularly acute when the connection between the article and its driving shaft or spindle is intentionally detachable to facilitate quick removal and replacement of the article. Into this category fall a host of devices, for example, portable powered grinders wherein the grinding wheels employed are intentionally detachable from the power driven shaft so that they may be readily replaced. To properly mount the grinding wheel upon the shaft, provision must be made to provide sufficient clamping force and also to secure the wheel rotationally. One means of securing the grinding wheel to the drive shaft has been to provide an appropriate backing member with a central opening which is aligned with an opening provided in the depressed center abrasive grinding wheel. A bolt or nut member (depending upon the configuration of the drive shaft; that is, whether it is externally or internally threaded) is inserted from the face side of the grinding wheel and is then tightened in place. In this manner a plurality of loose parts are configured in a completed assembly ready for use. As the grinding wheel is utilized the appropriate clamping force is provided to securely affix the grinding wheel to the drive shaft. Such an assembly, however, typically requires appropriate tools such as wrenches or the like to attach and remove the grinding wheel from the drive shaft. Such a device is shown in U.S. Pat. Nos. 489,149; 3,596,415; 1,998,919; 566,883; 507,223; 1,162,970; 791,159; 489,149 and 3,210,892. Subsequently it became desirable to affix the mounting hub permanently to the grinding wheel so that the entire unit may be attached and detached from the drive shaft and discarded when the grinding wheel has been worn down. In these types of devices it is customary to utilize an adhesive such as an epoxy resin or the like between the backing member and the back surface of the grinding wheel to retain integrity between the mounting hub and the grinding wheel to secure the wheel rotationally. Even though the adhesive tended to work quite well in most applications, it was discovered that in some instances the adhesive would break loose and the grinding wheel would rotate relative to the mounting hub. Such was particularly the case since the hub was a one-piece member which was internally threaded and held in place upon the grinding wheel by swaging an extension thereof into place, thus providing a fixed clamping force holding the grinding wheel. No additional clamping force was exerted during further rotation of the wheel during use as was the case with the traditional nut which was secured from the face as above described. As a result various keyways and corresponding key structures were developed between the wheel and the mounting hub and used in conjunction with the adhesive to preclude rotational movement between the mounting hub and the grinding wheel. Examples of such devices are shown in U.S. Pat. Nos. 3,136,100; 4,015,371; 2,278,301; 3,081,584; 3,500,592; 3,800,483; 4,240,230 and 4,541,205. Additional prior art patents known to applicant are U.S. Pat. Nos. 3,041,797; 3,879,178; 1,724,742; 3,912,411; 3,879,178; 3,960,516; 4,026,074; 4,054,425; 4,088,729; 4,322,920; 4,439,953; 4,449,329; 4,601,661; 791,791; 872,932; 2,567,782; 3,136,100; 3,210,892 and 3,621,621. The devices utilized in the prior art for providing the disposable finishing article assembly including the permanent affixed mounting hub generally provide the service intended. There are, however, certain inherent disadvantages found with regard to the various devices. Such disadvantages are that in manufacturing, the utilization of an adhesive adds additional labor to the cost of manufacturing. In certain of the devices, parts must be keyed together and properly aligned in order to function appropriately. In addition thereto, through the utilization of die-cast mounting hubs which are included as an integral unitary part of the backing member there is no additional clamping force exerted upon the finishing article as it is being rotated by the power tool. Furthermore, such mounting hubs are relatively bulky, take up space and add substantial weight and additional cost to the completed product. To solve the problems of the prior art as briefly summarized above, applicant has developed an abrasive article having a drive member non-removably affixed thereto for mounting on a rotatable spindle of a power tool. The drive member includes a backing member and a retaining nut positioned on opposite sides of the abrasive article with the retaining nut upset or swaged to hold the retaining nut and the backing member together on opposite sides of the abrasive article. A pressure cap is provided and may take various forms and may be constructed of different materials. For example, the pressure cap may be metal or plastic and may be secured to the backing member through a rotational mechanism or through upsetting or clamping the backing member. The pressure cap engages a shoulder on the spindle of the power tool and through engagement between the treads and the retaining nut and the threaded spindle as well as the forces applied by the pressure cap. The abrasive article is placed in compression between the backing member and a flange on the retaining nut during use of the abrasive article when such is operatively secured upon the spindle of the power tool. Such devices are illustrated and described in applicant's issued patents; namely 4,694,615; 4,754,577; 4,760,670; 4,924,634; 4,979,336 and 5,031,361. These patents of applicant constitute the best prior art known to applicant. The disclosure of applicant's U.S. Pat. No. 4,694,615 is incorporated herein by reference. SUMMARY OF THE INVENTION An abrasive wheel having a drive member non-removably affixed thereto for mounting on a rotatable spindle of a power tool. The drive member includes a backing member having a central opening therethrough secured by a retaining nut positioned on the opposite side from the backing member. The retaining nut extends through an opening in the abrasive wheel from the face toward the back of the finishing article and has a radial flange at one end thereof seated against the abrasive wheel face. A pressure cap defining a central opening extends outwardly from the backing member. The pressure cap includes an inner surface defining a plurality of spaced apart grooves. Means extending upwardly from the end of said retaining nut opposite said flange is disposed within said grooves to secure the retaining nut, backing member and pressure cap on said wheel without the use of adhesives while permitting limited longitudinal movement therebetween. The pressure cap extends longitudinally away from the backing member for the top of the pressure cap to engage the power tool spindle for placing the abrasive wheel in compression between said backing member and radial flange during use thereof when the finishing article is operatively secured upon the spindle of the power tool. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross sectional view of a preferred embodiment of a finishing article assembly constructed in accordance with the principles of the present invention and mounted in operable position on the spindle of a power tool; FIG. 2 is an exploded view of the structure as illustrated in FIG. 1; FIG. 3 is a cross sectional view taken about the lines 3--3 in FIG. 2 of a backing member constructed in accordance with the present invention and having a pressure cap affixed thereto; FIG. 4 is a cross sectional view of a retaining nut constructed in accordance with the principles of the present invention; FIG. 5 is a bottom plan view of a pressure cap constructed in accordance with the principles of the present invention; FIG. 6 is an enlarged cross sectional view of the pressure cap taken about the lines 6--6 of FIG. 5; FIG. 7 is an enlarged fragmentary cross sectional view illustrating a preferred embodiment for securing the pressure cap, the backing member and the retaining nut to the abrasive wheel; and FIG. 8 illustrates the manner in which the securing operation may be performed. DETAILED DESCRIPTION By reference now to FIGS. 1 through 7, there is illustrated a preferred embodiment of a disposable abrasive wheel drive member assembly constructed in accordance with the principles of the present invention. The term abrasive wheel is intended herein to be a generic term for abrasive devices constructed in accordance with the present invention which may take many forms, such, for example, as grinding wheels of all types including depressed center wheels, flat disks, cut off wheels, diamond blades, or the like. For purposes of ease of illustration and clarity of description only a seven (or nine) inch diameter depressed center grinding wheel will be shown and described. It will, however, be understood by those skilled in the art that other disposable abrasive articles which may be placed in compression during use thereof may be substituted for the grinding wheel shown. As is shown in FIGS. 1 through 7, a depressed center grinding wheel 10 has a disposable drive member or hub assembly 12 permanently affixed thereto without the use of adhesives so that the grinding wheel may be attached to the threaded spindle 14 of an appropriate power tool 16. According to the principles of the present invention, a disposable mounting hub or drive member is constructed in such a manner that when the grinding wheel is placed in operation upon the spindle 14 the grinding wheel 10 is placed in compression and the more force that is applied to the grinding wheel during utilization thereof, the greater the operational compression becomes. As a result of placing the grinding wheel in such compression the grinding wheel is maintained upon the spindle and at the same time, through the compression or clamping force, the grinding wheel 10 cannot rotate relative to the drive member or hub assembly 12. However, as a result of the construction of the drive member, the spent grinding wheel may be easily removed from the spindle for disposal usually without the utilization of hand tools or the like. As is clearly shown, the grinding wheel 10 includes a back surface 18 and a front surface 20. The central portion of the grinding wheel is depressed as viewed from the front thereof and as is shown at 22, with a corresponding central raised portion 24 on the back thereof. A centrally located aperture 26 is provided in the depressed center portion of the grinding wheel 10. The purpose of the depressed center of the grinding wheel 10 is to insure that the driving member or spindle does not protrude beyond the face portion 20 of the wheel 10 and thus interfere with a workpiece during the time the grinding wheel 10 is being utilized. However, when certain types of abrasive articles are utilized such that the outer circumference is used instead of the face, then a depressed center may not be necessary or included in the article. A backing member 28 is provided and is adapted to be received on the back surface 18 of the grinding wheel 10 about the raised portion 24. The backing member 28 has a diameter which is less than the diameter of the wheel 10. The backing member 28 defines a second central aperture 30 therethrough which is aligned with the aperture 26 in the grinding wheel 10. The backing member 28 is preferably stamped from sheet metal. As is shown more specifically in FIG. 3, the backing member 28 includes an inner surface 36 and an outer surface 38. The inner surface 36 is disposed opposed the back surface 18 of the abrasive finishing wheel 10. The inner surface 36 includes a land 40. The land 40 is formed about the outer peripheral portion of the backing member 28. On seven and nine inch wheels with depressed centers the land 40 always engages the back surface 18 of the abrasive finishing wheel away from the depressed center. On smaller depressed center grinding wheels, diamond wheels, flat surface or cut off wheels and the like, the backing member may take the form of a flat washer like member. As shown in FIG. 4, a retainer nut 44 includes a body portion 46 which is hollow and has a radially outwardly extending flange 48 at a first end 50 thereof. The internal surface of the body 46 has threads 56 formed therealong for attachment to the threaded spindle 14 of the power tool. A continuous wall 52 extends upwardly from the body 46 and terminates in a rim 53. The wall 52 is relatively thin and as will be described more in detail below may be upset or swaged. The nut 44 is inserted through the aperture 26 in the grinding wheel and the aperture 30 in the backing member 28 from the front surface 20 toward the rear surface 18 of the grinding wheel 10. The wall 52 of the nut 44 extends through the opening 30 in the backing member 28. The nut 44 is preferably constructed from a metal die casting but may be formed from an aluminum extrusion which is then machined to provide the flange 48 and the threads 46. Alternatively the nut may be formed from steel bar stock, molded plastic, composite materials, or formed by cold heading. To provide proper operational compressive forces on the disposable grinding wheel as above described, a pressure cap 60 forms a part of the hub assembly 12. The metal pressure cap 60 is formed as a hexagonal nut shaped member having a hollow body 72, and an inner surface 73. Preferably the metal pressure cap 60 is formed by metal die casting, however, it will be recognized that it may be formed from molded plastic or composite material. The metal pressure cap 60 includes a first or rear surface 62 for engaging a surface 64 on the power tool spindle when the grinding wheel is in an operable position on the power tool 16. A second or front surface 66 on the metal pressure cap 60 rests upon the outer surface 38 of the backing member 28. The inner surface 73 of the pressure cap 60 defines a plurality of grooves 80, 82, 84, 86, 88 and 90. The grooves 80-90 terminate at the upper surface 62 in a plurality of apertures 92-102. Also extending inwardly radially from the surface 73 is a plurality of ribs 104, 106, 108, 110, 112 and 114. The ribs 104-114 are disposed between adjacent grooves 80-90 respectively. The ribs 104-114 provide strength to the flat surfaces 116-126 forming the hexagonal nut form of the pressure cap 60. The pressure cap 60 at the end 128 thereof includes in the embodiment as illustrated an extension 130. The extension 130 extends through the opening 30 in the backing member 28 and is turned as shown at 132 in FIG. 3 to retain the pressure cap on the backing member 28 so that it protrudes outwardly therefrom. It will be appreciated by those skilled in the art that a relatively minor amount of material is required to secure the pressure cap 60 to the backing member 28 because there is no tension force being applied which would tend to separate the pressure cap from the backing member. Those skilled in the art will also recognize that the pressure cap and the backing member may be constructed of a unitary die cast structure if such is desired or, alternatively, from a unitary molded plastic or composite member depending upon the particular application. The combination of the metal pressure cap 60 and the backing member 28 is retained in position on the abrasive wheel 10 by upsetting the continuous wall 52 so that portions thereof extend into the grooves 80-90. Once installed, the retaining nut 44, the backing member 28 and the metal pressure cap 60 remain permanently on the grinding wheel 10 and are disposed of along with the spent wheel 10. The hollow body 72 of the metal pressure cap 60 defines an aperture 61 for receiving the spindle 14 of the power tool. When assembled, the apertures 26, 30 and 61 are aligned axially. As is illustrated more particularly in FIG. 8 along with FIGS. 1, 6 and 7, the hub assembly is affixed to the wheel 10 by upsetting sections of the wall 52 extending upwardly from the nut 44 so that these sections of the wall 52 are disposed within and extend into the grooves 80-90 formed in the inner surface 73 of the pressure cap 60. During assembly the retainer nut 44 is inserted through the opening 26 in the wheel 10 with the wall 52 extending upwardly from the rear surface 18 thereof. The combination of the backing member 28 with the pressure cap 60 affixed thereto is then disposed such that the wall 52 is received within the hollow body 72 of the pressure cap 60. An appropriate tool such as is illustrated at 132 in FIG. 8 is inserted into the apertures 92-102 of the body 72 of the pressure cap 60. An appropriate force F is applied downwardly thereto as shown by the arrow 134. The end 136 of the tool is appropriately shaped to engage the rim 53 of the wall 52 and upset the wall 52 thereof driving sections of the wall 52 into the grooves 80-90. When such is done the retaining nut and the combination of the metal pressure cap and the backing member are held in place on the wheel 10. By causing the sections of the wall 52 to engage the grooves 80-90 of the pressure cap 60 it will be recognized by those skilled in the art that the pressure cap and the nut are rotationally locked together. Also by extending the sections of the wall into the grooves there is an axial securing together of these elements on the wheel 10. The assembly is also accomplished such that there is permitted limited axial movement so that when the wheel is operably affixed to the spindle 14 the wheel is placed in compression through forces applied by the pressure cap downwardly and by the flange 50 on the nut 44 upwardly through the forces generated by the cooperative threads between the spindle and the retaining nut 44. Although a groove has been provided at the point where the flat surfaces of the outer surface of the pressure cap 60 come together so that in the hexagonal form there are six such grooves it should be understood by those skilled in the art that a smaller number of grooves may be utilized, for example, such as two disposed opposed each other. However, by providing the additional two opposed sets of such grooves additional strength for the rotational locking is provided. It will be understood by those skilled in the art that by providing the hexagonal form with the rotational locking as above described one may, if desired, utilize a wrench to remove the spent abrasive wheel from the power tool 16 when it is required to replace it with a fresh wheel. Experience, has however, taught that because of the particular way in which the present invention is constructed it may be easily removed from the power tool by hand. The force necessary to cause the grinding wheel 10 to be placed in compression is generated upon attachment of the spindle 14 to the threads 56 in the nut 44. By reference to FIG. 1 it will be noted that when the grinding wheel is threaded upon the spindle 14 the surface 62 engages the spindle 64. The interengagement between the threads 14 and 56 of the spindle and nut, respectively, urge the nut upward toward the backing member 28 as the wheel is seated upon the spindle. At the same time, the spindle seat 64 applies a downward force to surface 62 of the pressure cap 60 which in turn, through the surface 66 applies a downward force to the backing member 28. Therefore, this mutual clamping force causes the grinding wheel to be placed in compression. Those skilled in the art will recognize that as the grinding wheel 10 is used by being placed against a workpiece, additional torque is applied causing the grinding wheel to be further tightened onto the spindle 14. That is, if the grinding wheel moves, even incrementally, during contact with a workpiece, the friction between the nut and the grinding wheel center causes the nut to rotate in a further tightening direction. Such rotation of the nut further urges the nut toward the flange which in turn applies a further force to the flange. The more the grinding wheel is tightened the greater the operational compression force becomes and the more securely the grinding wheel 10 is clamped between the backing member 28 and the flange 48 on the nut 44. As a result of this strong clamping or compression the grinding wheel 10 is precluded from movement relative to the hub or driving member 12 and at the same time is precluded from disengaging from the spindle 14. It will be recognized by those skilled in the art that the grinding wheel assemblies as illustrated in FIGS. 1 through 7 and as above described require no adhesive for construction and may be simply and easily assembled, are relatively light in weight as compared to the prior art devices utilizing the solid cast hubs and provides a secure attachment of the abrasive article to the power tool and through the utilization of the increased compression precludes relative rotation of the grinding wheel with respect to the driving member. It has also been discovered that the utilization of the device as above described and as constructed in the preferred embodiment is extremely smooth in operation with no vibration. The reason for such extremely smooth operation is that all of the parts are perfectly aligned one with the other with the abutting surfaces parallel when in compression and only the wheel 10 can cause any vibration and then only if it is not properly balanced during the construction thereof. Through the structures as illustrated and described, all currently known sizes of depressed center grinding wheels may be accommodated. In addition thereto flat grinding wheels and diamond wheels may also be accommodated. There has thus been disclosed a disposable abrasive article driving member assembly which securely holds the article during operation, which is light in weight, vibration-free, and less expensive than prior art throw-away articles while meeting all safety standards currently known and in existence.

A disposable abrasive wheel for mounting on a rotatable threaded spindle of a power tool. The abrasive wheel contains a retaining nut on one side and a backing member on the other side non-removably secured together on the abrasive wheel without the aid of adhesives in such a manner that the abrasive wheel is placed in compression when it is operably secured upon the spindle of the power tool under operative loads. A metal pressure cap extends outwardly from the backing member and has an upper flat surface for engaging a should formed on the spindle of the power tool during operation of the finishing article. The metal pressure cap includes an inner surface defining a plurality of grooves. A peripheral wall extends upwardly from the retaining nut into the pressure cap and includes portions thereof disposed within said grooves.

RELATED APPLICATIONS [0001] The present application is a Continuation Application of U.S. patent application Ser. No. 12/320,052 filed on Jan. 15, 2009, which was a Divisional Application of U.S. patent Ser. No. 11/980,630, (now U.S. Pat. No. 7,499,123) filed on Oct. 31, 2007, which was a Divisional Application of U.S. patent application Ser. No. 11/134,299 (now U.S. Pat. No. 7,349,043 B2) which was filed on May 23, 2005. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention Technical Field [0003] The present invention relates to a planar light source, a display device, a portable terminal device, and a ray direction switching element, and in particular, to a planar light source that can change an irradiation angle of illumination light, a display device that can change an angle of field using the planar light source, a portable terminal device that uses the display device, and a ray direction switching element that is incorporated in the planar light source. [0004] 2. Description of the Related Art Background Art [0005] In accordance with the development of technologies in recent years, a liquid crystal display device (LCD), which is wide in an angle of field, that is, visually recognizable in a wide angle range, has been put to practical use. In addition, a portable information terminal mounted with the LCD is also widely used. In such a portable information terminal, it is desirable that the angle of field of the LCD is wide when a user looks at information displayed on the LCD with other people. On the other hand, in the portable information terminal, the user often does not want other people to peep at displayed information. In such a case, it is desirable that the angle of field of the LCD is narrow. In this way, the angle of field is required to be wide and narrow depending on a state of use of the LCD. Conventionally, LCDs meeting such a demand have been proposed. [0006] FIGS. 24( a ) and 24 ( b ) schematically show a first conventional liquid crystal display device that is described in Japanese Patent Laid-Open No. 6-59287. FIG. 24( a ) shows the liquid crystal display device at the time when a voltage is not applied thereto. FIG. 24( b ) shows the liquid crystal display device at the time when a voltage is applied thereto. As shown in FIGS. 24( a ) and 24 ( b ), the first conventional liquid crystal display device includes a liquid crystal panel in which a liquid crystal material (not shown) is sealed by transparent substrates 102 and 108 . A polarizing plate 101 is provided on one surface of this liquid crystal panel. On the other surface, a guest host liquid crystal cell 131 , in which a liquid crystal material consisting of liquid crystal molecules 131 a and elongate pigment molecules 131 b are sealed by two transparent substrates 114 provided with transparent electrodes 110 on surfaces thereof, is provided. The pigment molecules 131 b have a larger amount of absorption of light in a minor axis direction of the molecules than in a major axis direction thereof. When a voltage is not applied to the guest host liquid crystal cell 131 , the liquid crystal molecules 131 a and the elongate pigment molecules 131 b are arranged to be parallel to the surfaces of the transparent substrates 114 in a longitudinal direction. When a voltage is applied to the guest host liquid crystal cell 131 , the liquid crystal molecules 131 a and the elongate pigment molecules 131 b are arranged to be perpendicular to the surfaces of the transparent substrates 114 in the longitudinal direction. The polarizing plate 101 is provided on a surface on the opposite side of a surface opposed to the liquid crystal panel of the guest host liquid crystal cell 131 . [0007] In the first conventional liquid crystal display device constituted in this way, which is described in Japanese Patent Laid-Open No. 6-59287, light in a wide angle range passes through the liquid crystal panel to be made incident on the guest host liquid crystal cell 131 . When an image is displayed at a wide angle of field, a voltage is not applied to the guest host liquid crystal cell 131 to make a light absorbing direction of the guest host liquid crystal cell 131 coincident with an absorbing direction of the polarizing plate 101 , whereby the light passes through the guest host liquid crystal cell 131 directly. Consequently, it is possible to visually recognize a display screen in a wide angle range. [0008] When an image is displayed at a narrow angle of field, when a voltage is applied to the guest host liquid crystal cell 131 , the pigment molecules 131 b are arranged to be perpendicular to the surfaces of the transparent substrates 114 in the longitudinal direction, and an angle of incidence of light deviates largely from a direction perpendicular to the surfaces of the transparent substrates 114 . This light is absorbed by the pigment molecules 131 b and does not pass through the guest host liquid crystal cell 131 . Therefore, even if an angle distribution of light made incident on the display device is wide, an angle distribution of emitted light is narrowed by absorption of the guest host liquid crystal. Consequently, it is possible to reduce a size of a visually recognizable display screen. [0009] FIG. 25 is a diagram schematically showing a second conventional liquid crystal display device that is described in Japanese Patent Laid-Open No. 10-197844. The second conventional liquid crystal display device includes a backlight 113 , as shown in FIG. 25 . A PDLC cell 136 , in which a Polymer Dispersed Liquid Crystal (PDLC) layer 111 is sandwiched by two transparent substrates 109 , is provided on the backlight 113 . A polarizing plate 101 is provided on the PDLC cell 136 , and a Twisted Nematic-Liquid Crystal Display (TN-LCD) is provided on the polarizing plate 101 . A guest host liquid crystal cell is provided on the TN-LCD, and the polarizing plate 101 is provided on the guest host liquid crystal cell. This guest host liquid crystal cell has the same structure as the guest host liquid crystal cell that is used in the first conventional liquid crystal display device described in Japanese Patent Laid-Open No. 6-59287. [0010] In the second conventional liquid crystal display device constituted in this way, which is described in Japanese Patent Laid-Open No. 10-197844, wide field of view display and narrow field of view display are switched by switching ON and OFF of a voltage applied to the guest host liquid crystal cell. In addition, transmission and reflection of light is switched by switching ON and OFF of a voltage applied to the PDLC cell to adjust brightness of a display screen. [0011] Japanese Patent Laid-Open No. 11-142819 discloses a liquid crystal display device in which a condensing element consisting of a prism sheet and a light scattering element consisting of a PDLC cell are provided between a light source and a liquid crystal panel. Japanese Patent Laid-Open No. 11-142819 mentions that it is possible to switch a narrow angle of field and a wide angle of field by increasing directivity of light with the prism sheet and, then, transmitting or scattering light from the prism sheet with the PDLC cell. In addition, Japanese Patent Laid-Open No. 9-105907 discloses a similar liquid crystal display device in which an optical element consisting of a PDLC cell is provided between a light source and a liquid crystal panel. [0012] On the other hand, conventionally, a high directivity backlight, in which an irradiation range of illumination light is fixed but directivity in a specific direction such as the front direction is improved, has been developed (see, for example, monthly magazine “Display” May 2004, pages 14 to 17). FIG. 26 is a perspective view showing a conventional high directivity backlight 213 described in the monthly magazine “Display” May 2004, pages 14 to 17. As shown in FIG. 26 , in this conventional high directivity backlight 213 , an LED 201 is arranged in one location where a light guide plate 202 is provided, and a linear micro-prism is arranged concentrically around the LED 201 in the light guide plate 202 . A prism sheet 203 , in which a prism structure is also arranged concentrically around the LED 201 , is arranged on a light emission surface of the light guide plate 202 . In addition, a reflection sheet 204 is arranged on a surface on the opposite side of the surface of the light guide plate 202 on which the prism sheet 203 is provided. [0013] Exit light from the LED 201 is made incident on the light guide plate 202 and emitted radially along the surface of the light guide plate 202 by the linear micro-prism formed in the light guide plate 202 . At this point, the LED 201 is arranged in one location of the light guide plate 202 , and a longitudinal direction of the linear micro-prism formed in the light guide plate 202 is arranged to be substantially perpendicular to the LED 201 . Thus, even if light guided through the light guide plate 202 hits the linear micro-prism, the light is not deflected in the longitudinal direction of the linear micro-prism but travels linearly and radially around the LED 201 . The light emitted from the light guide plate 202 is refracted by the prism sheet 203 and deflected in a vertical direction with respect to the light emission surface of the light guide plate 202 . Consequently, a high directivity backlight, in which directivity is improved two-dimensionally in a front direction, is realized. DISCLOSURE OF THE INVENTION Problems to Solved by the Invention [0014] However, the conventional techniques described above has problems described below. In the liquid crystal display device described in Japanese Patent Laid-Open No. 6-59287, a difference of an amount of absorption of light is small in the minor axis direction and the major axis direction of the pigment molecules in the guest host liquid crystal cell. In other words, a pigment dichroic ratio is low. In addition, liquid crystal molecules near the transparent substrates do not stand at the time of voltage application, and the pigment molecules arranged in parallel to the transparent substrates remains. Consequently, in the guest host liquid crystal cell at the time of voltage application, efficiency of absorbing light, an incident angle of which deviates largely from the direction perpendicular to the surfaces of the transparent substrates, falls, and an angle of field at the time of the narrow field of view display increases. [0015] In addition, in the liquid crystal display device described in Japanese Patent Laid-Open No. 10-197844, the wide field of view display and the narrow field of view display are also switched by switching ON and OFF of a voltage applied to the guest host liquid crystal. Consequently, the same problems as the liquid crystal display device described in Japanese Patent Laid-Open No. 6-59287 occur. [0016] Moreover, in the liquid crystal display device described in Japanese Patent Laid-Open No. 11-142819, light from a light source is condensed by the prism sheet, that is, directivity of light is improved. The light with high directivity passes through the PDLC cell directly, whereby a size of a visually recognizable display screen is reduced. However, since the prism sheet does not have a sufficient effect for improving directivity of light, an angle of field at the time of the narrow field of view display increases. In other words, other people peep at displayed information. SUMMARY OF THE INVENTION [0017] The invention has been devised in view of such problems, and it is an object of the invention to provide a planar light source having a large variable width of an irradiation angle of illumination light, a display device having a large variable width of an angle of field that uses the planar light source, a portable terminal device that uses the display device, and a ray direction switching element that is incorporated in the planar light source. Means for Solving the Problems [0018] A planar light source in accordance with the invention includes: a backlight that emits light in a planar shape; a ray direction regulating element that regulates a direction of light made incident from the backlight and emits the light and in which a transparent area for transmitting light and an absorption area for absorbing light are formed alternately in a direction perpendicular to a light regulating direction thereof; and a transparent and scattering switching element that is capable of switching a state in which light made incident from the ray direction regulating element is transmitted and a state in which the light is scattered. [0019] In the invention, the beam direction regulating element, which controls a direction of light, and the transparent and scattering switching element, which can switch the transparent and the scattering state according to ON and OFF of an applied voltage, are provided between the backlight and a liquid crystal panel, whereby it is possible to increase a variable width of an irradiation angle of light in the planar light source. [0020] It is preferable that an emitting direction of light emitted by the backlight spreads radially in an elliptical shape with respect to a direction perpendicular to an emission surface, and the transparent area and the absorption area of the ray direction regulating element are formed alternately in a direction parallel to a long diameter direction of the ellipse. [0021] It is preferable that an emitting direction of light emitted from the back light spreads radially in an elliptical shape with respect to a direction perpendicular to an emission surface and, in the ray direction regulating element, the transparent area and the absorption area are formed alternately in a direction parallel to a short diameter direction of the ellipse. Consequently, since an amount of light of the backlight passing through the ray direction regulating element increases, it is possible to realize a bright planar light source. [0022] An emitting direction of light emitted by the backlight may be condensed radially in a circular shape with respect to a direction perpendicular to an emission surface. Consequently, since a loss of absorption of light by the ray direction regulating element can be reduced, it is possible to realize bright display. In addition, since directivity of the backlight is two-dimensional, it is also possible to switch the narrow field of view display and the wide field of view display concerning a direction orthogonal to the direction in which the transparent area and the absorption area of the ray direction regulating element are arranged alternately. [0023] It is preferable that, in the transparent and scattering switching element, a polymer dispersed liquid crystal layer, in which liquid crystal molecules are dispersed in a polymer film, is sandwiched between a pair of flat electrodes, and the polymer dispersed liquid crystal layer is in a state in which the polymer dispersed liquid crystal layer transmits incident light when a voltage is applied between the flat electrodes and in a state in which the polymer dispersed liquid crystal layer scatters incident light when a voltage is not applied between the flat electrodes. Consequently, since the transparent and scattering switching element does not consume electric power in the state in which the transparent and scattering switching element scatters incident light, the electric power is allocated to a backlight light source. Thus, it is possible to improve brightness of the planar light source at the time of the scattering state. [0024] An orientation state of the liquid crystal molecules at the time when a voltage is applied thereto may be held after the application of the voltage is stopped. [0025] The transparent and scattering switching element and the ray direction regulating element may be formed integrally. Consequently, since the ray direction regulating element can be supported by the transparent and scattering switching element, it is possible to realize a highly stable and thin planar light source. [0026] The transparent and scattering switching element and the ray direction regulating element may have a common substrate. [0027] A substrate of the ray direction regulating element may be only a substrate common to the ray direction regulating element and the transparent and scattering switching element. Consequently, it is possible to further reduce thickness of the planar light source. In addition, it is preferable that an amount of light of the backlight and the transparent and scattering states of the transparent and scattering switching element can be set independently. Consequently, it is possible to set intensity and directivity of light emitted from the planar light source in various ways. [0028] It is also possible that the transparent and scattering switching element is in the state in which the transparent and scattering switching element scatters incident light when a voltage is not applied between the flat electrodes, and in which a voltage is applied to the transparent and scattering switching element when the transparent and scattering switching element is used in the scattering state. Consequently, it is possible to increase a front luminance without significantly decreasing a luminance in an oblique direction at the time when the transparent and scattering switching element is used in the scattering state. [0029] A display device in accordance with the invention includes: a backlight that emits light in a planar shape; a ray direction regulating element that regulates a direction of light made incident from the backlight and emits the light and in which a transparent area for transmitting light and an absorption area for absorbing light are formed alternately in a direction perpendicular to a light regulating direction thereof; a transparent and scattering switching element that is capable of switching a state in which light made incident from the ray direction regulating element is transmitted and a state in which the light is scattered; and a liquid crystal panel that displays an image using light made incident from the transparent and scattering switching element. [0030] In the invention, the beam direction regulating element, which controls a direction of light, and the transparent and scattering switching element, which can switch the transparent and the scattering state according to ON and OFF of an applied voltage, are provided between the backlight and a liquid crystal panel, whereby it is possible to increase a variable width of an angle of field of the display device. [0031] It is preferable that an emitting direction of light emitted by the backlight spreads radially in an elliptical shape with respect to a direction perpendicular to an emission surface and, in the ray direction regulating element, the transparent area and the absorption area are formed alternately in a direction parallel to a long diameter direction of the ellipse. [0032] The white light source may be constituted by a blue LED and a yellow phosphor to adjust an amount of light with pulse modulation. Consequently, it is possible to control chromaticity change of the display device when an amount of light of the white light source is adjusted simultaneously with switching of transparent and scattering. [0033] A direction in which the transparent area and the absorption area of the ray direction regulating element are formed alternately and a pixel arrangement direction of the display panel do not have to be parallel to each other. Consequently, it is possible to reduce moiré due to the ray direction regulating element and the display panel. [0034] The display panel may be a liquid crystal panel, and the liquid crystal display panel may be a panel of a lateral electric field mode, a multi-domain vertical orientation mode, or a film compensation TN mode. Consequently, it is possible to control tone reversal and improve visibility at the time when the transparent and scattering switching element is in the scattering state. [0035] The portable terminal device may have adjusting means that can change an amount of the backlight and the transparent and scattering states of the transparent and scattering switching element independently from each other. Consequently, a user can set an optimum state according to an environment of use of the portable terminal device. [0036] The portable terminal device may have electric power accumulating means, residual amount detecting means for electric power accumulated in the electric power accumulating means, and control means that automatically changes an amount of the backlight and the transparent and scattering states of the transparent and scattering switching element on the basis of detected residual amount information. When the transparent and scattering element is brought into the transparent state, since an amount of light of the backlight can be reduced, it is possible to reduce power consumption when residual battery power is low and extend an operating time of the portable terminal device. [0037] The transparent area and the absorption area of the ray direction regulating element may be formed alternately in a lateral direction of the portable terminal device. Consequently, it is possible to increase a variable width of an angle of field in the lateral direction of the portable terminal device. [0038] A ray direction switching element in accordance with the invention is characterized in that a ray direction regulating element, which regulates a direction of incident light and emits light, and a transparent and scattering switching element, which is capable of switching a state in which light made incident from the ray direction regulating element is transmitted and a state in which the light is scattered, are integrally formed. Consequently, since the ray direction regulating element can be supported by the transparent and scattering switching element, it is possible to realize a highly stable and thin ray direction switching element. [0039] In the ray direction switching element, the transparent and scattering switching element and the ray direction regulating element may be formed on a common substrate. A substrate of the ray direction regulating element may be only a substrate common to the ray direction regulating element and the transparent and scattering switching element. ADVANTAGE OF THE INVENTION [0040] According to the invention, the ray direction regulating element, that controls a direction of light, and the transparent and scattering switching element, which can switch the transparent and scattering states by turning ON and OFF an applied voltage, are provided between the backlight and the liquid crystal panel, whereby it is possible to increase a variable width of an irradiation angle of light in the planar light source and increase a variable width of an angle of field of the liquid crystal display device that uses the planar light source. BRIEF DESCRIPTION OF THE DRAWINGS [0041] FIG. 1 is a sectional view showing a liquid crystal display device in accordance with a first embodiment of the invention; [0042] FIG. 2 is a perspective view showing an example of a backlight that is used in the liquid crystal display device in accordance with the first embodiment of the invention; [0043] FIG. 3 is a diagram showing a direction of light emitted from the backlight; [0044] FIG. 4 is a plan view showing an example of a louver that is used in the liquid crystal display device in accordance with the first embodiment of the invention; [0045] FIG. 5 is a diagram showing a light distribution characteristic at the time of a wide angle of field of the liquid crystal display device in accordance with the first embodiment of the invention; [0046] FIG. 6 is a diagram showing a light distribution characteristic at the time of a narrow angle of field of the liquid crystal display device in accordance with the first embodiment; [0047] FIG. 7 is a plan view showing an example of a louver that is used in a liquid crystal display device in accordance with a first modification of the first embodiment of the invention; [0048] FIG. 8 is a plan view showing an example of a louver that is used in a liquid crystal display device in accordance with a second modification of the first embodiment of the invention; [0049] FIG. 9 is a diagram showing a light distribution characteristic at the time of a wide angle of field of a liquid crystal display device in accordance with a third modification of the first embodiment of the invention; [0050] FIG. 10 is a diagram showing a light distribution characteristic at the time of a narrow angle of field of the liquid crystal display device in accordance with the third modification of the first embodiment of the invention; [0051] FIG. 11 is a sectional view showing a liquid crystal display device in accordance with a second embodiment of the invention; [0052] FIG. 12 is a sectional view showing a liquid crystal display device in accordance with a third embodiment of the invention; [0053] FIG. 13 is a sectional view showing a liquid crystal display device in accordance with a fourth embodiment of the invention; [0054] FIG. 14 is a sectional view showing a liquid crystal display device in accordance with a fifth embodiment of the invention; [0055] FIG. 15 is a sectional view showing a liquid crystal display device in accordance with a sixth embodiment of the invention; [0056] FIG. 16 is a sectional view showing a liquid crystal display device in accordance with a seventh embodiment of the invention; [0057] FIG. 17 is a sectional view showing a liquid crystal display device in accordance with an eighth embodiment of the invention; [0058] FIG. 18 is a sectional view showing a liquid crystal display device in accordance with a ninth embodiment of the invention; [0059] FIG. 19 is a sectional view showing a liquid crystal display device in accordance with a tenth embodiment of the invention; [0060] FIG. 20 is a graph showing a result of an experiment in which a slight voltage is applied to a transparent and scattering switching element in a scattering state to adjust a scattering property; [0061] FIG. 21 is a perspective view showing a portable terminal device mounted with a liquid crystal display device of the invention; [0062] FIG. 22 is a plan view showing a transparent and scattering switching element of a liquid crystal display device in accordance with a twelfth embodiment of the invention; [0063] FIG. 23 is a plan view showing a liquid crystal display device in which a direction in which a transparent area and an absorption area of a ray direction regulating element are formed alternately and a pixel arrangement direction of a liquid crystal display panel are not parallel to each other; [0064] FIG. 24( a ) is a diagram schematically showing a first conventional liquid crystal display device at the time when a voltage is not applied thereto; [0065] FIG. 24( b ) is a diagram schematically showing a first conventional liquid crystal display device at the time when a voltage is applied thereto; [0066] FIG. 25 is a diagram schematically showing a second conventional liquid crystal display device; and [0067] FIG. 26 is a perspective view showing a conventional high directivity backlight. DETAILED DESCRIPTION OF THE EMBODIMENTS Best Mode for Carrying Out the Invention [0068] Embodiments of the invention will be hereinafter explained specifically with reference to the accompanying drawings. First, a first embodiment of the invention will be explained. FIG. 1 is a sectional view showing a liquid crystal display device in accordance with the first embodiment. FIG. 2 is a perspective view showing an example of a backlight that is used in the liquid crystal display device in accordance with the first embodiment. FIG. 3 is a diagram showing a direction of light emitted from the backlight. FIG. 4 is a plan view showing an example of a louver that is used as a ray direction regulating element in the liquid crystal display device in accordance with the first embodiment. FIG. 5 is a diagram showing a light distribution characteristic at the time of a wide angle of field of the liquid crystal display device in accordance with the first embodiment. FIG. 6 is a diagram showing a light distribution characteristic at the time of a narrow angle of field of the liquid crystal display device. [0069] As shown in FIG. 1 , in the liquid crystal display device in accordance with the first embodiment, a backlight 13 is provided, and a louver 12 (a ray direction regulating element) is provided above the backlight 13 . A transparent and scattering switching element 22 is provided above the louver 12 , and a liquid crystal panel 21 is provided above the transparent and scattering switching element 22 . [0070] As shown in FIG. 2 , a linear light source 36 of a prism shape is provided along one end face of the backlight 13 , and white LEDs 25 are provided to be opposed to both ends thereof, respectively. The linear light source 36 includes plural prisms (not shown), which are arranged cyclically, to refract light, which is made incident on the linear light source 36 from the white LEDs 25 , substantially orthogonally in a direction of the backlight 13 with the plural prisms. In this way, the linear light source 36 emits linear light in the direction of the backlight 13 from a side of the backlight 13 . In addition, the backlight 13 includes plural prisms (not shown) that are arranged cyclically in a direction orthogonal to a surface extending in parallel to the linear light source 36 and opposed to the linear light source 36 . These prisms refract linear light made incident from the linear light source 36 in a direction orthogonal to one surface 37 of the backlight 13 and emit planar light from the entire surface 37 . Such a backlight 13 emits light, of which light in a direction parallel to the linear light source 36 has a wider angle than light in a direction orthogonal to the linear light source 36 . [0071] As shown in FIG. 3 , a direction 35 of light emitted from the backlight 13 is defined by a polar angle θ and an azimuth φ. The polar angle θ is an angle formed by the direction 35 and a direction 34 perpendicular to a surface of the backlight 13 . On a projection surface 13 parallel to the backlight 13 , when an X-Y rectangular coordinate with a point, where the direction 34 and the projection surface 33 cross each other, as an origin O is assumed, the azimuth φ is an angle formed by a line, which connects an intersection where the direction 35 and the projection surface 33 cross each other and the origin O, and the X axis. In this way, light emitted from the backlight 13 is diffused light, and θ and φ have wide distributions. [0072] As shown in FIG. 1 , the louver 12 is a ray direction regulating element that improves directivity of light emitted from the backlight 13 . The louver 12 regulates a ray direction of broadening light made incident from the backlight 13 in one direction and emits the light. This light regulating direction is, for example, a direction perpendicular to a surface of the louver 12 . Of the light emitted from the louver 12 , directivity of light in a direction perpendicular to the surface of the louver 12 (light regulating direction) is improved. In this case, the light emitted with the direction thereof regulated by the louver 12 broadens a little, although a polar angle θ is smaller than that of the light emitted from the backlight 13 shown in FIG. 3 . [0073] In the louver 12 , for example, a transparent area 12 a , which transmits light, and an absorption area 12 b , which absorbs light, are formed to be arranged alternately in a direction parallel to the surface of the louver 12 . The direction in which the transparent area 12 a and the absorption area 12 b are arranged alternately is identical with, for example, a direction in which the backlight 13 emits wide angle light, that is, a direction parallel to the linear light source 36 . As shown in FIG. 4 , viewed from a direction perpendicular to the surface of the louver 12 , the transparent area 12 a and the absorption area 12 b of a stripe shape are arranged alternately. The louver 12 can adjust, for example, thickness and an arrangement pitch of the transparent area 12 a and the absorption area 12 b and an absorption amount of light in the absorption area 12 b to adjust an emission angle at the time when incident light is emitted. [0074] As shown in FIG. 1 , in the transparent and scattering switching element 22 , a PDLC layer 11 formed by scattering liquid crystal molecules 11 b in a polymer matrix 11 a is put in electrodes 10 , and a transparent substrate 9 is provided on the each electrode 10 . A voltage is applied to the PDLC layer 11 , which is sandwiched between the electrodes 10 , by the electrodes 10 , whereby an orientation state of liquid crystal molecules in the PDLC layer 11 changes. The PDLC layer 11 is formed by, for example, exposing a mixture of a photo-curing resin and a liquid crystal material to light and hardening the mixture. The transparent and scattering switching element 22 scatters or transmits light made incident from the louver 12 and emits the light to the liquid crystal panel 21 . [0075] In the liquid crystal panel 21 , a polarizing panel 1 , which polarizes light made incident from the transparent and scattering switching element 22 , is provided, and a transparent substrate 8 is provided on the polarizing plate 1 . A pixel electrode 7 defining a pixel area is provided on the transparent substrate 8 in a matrix shape. A liquid crystal layer 6 is provided to cover surfaces of the pixel electrode 7 and the transparent substrate 8 . A common electrode 5 for applying a voltage to the liquid crystal layer 6 is provided on the liquid crystal layer 6 , and the transparent dielectric layer 4 is provided on the common electrode 5 . In the transparent dielectric layer 4 , a groove is formed in a position corresponding to an area of the surface of the transparent substrate 8 , which is not covered by the pixel electrode 7 , and a black matrix 3 , which prevents external light from being projected on the liquid crystal panel, is provided in the groove. A transparent substrate 2 is provided to cover the transparent dielectric layer 4 and the black matrix 3 , and a polarizing plate 1 , which polarizes emitted light from the liquid crystal panel, is provided on the transparent substrate 2 . [0076] As shown in FIG. 5 , light emitted from the backlight 13 has an elliptical distribution 38 spreading widely in an X direction compared with a Y direction. This emitted light distribution indicates that light spreads largely as an area of a distribution area is larger. When light of this distribution 38 is made incident on the louver 12 , light spreading in the X direction is absorbed by the louver 12 to change to light of a distribution 39 with high directivity that is distributed substantially in a round shape. In the case of the wide field of view display, when the light of this distribution 39 is made incident on the transparent and scattering switching element 22 in the scattering state, light of a circular distribution is uniformly scattered to change to light of a circular distribution 40 that spreads more largely. The light of this distribution 40 is transmitted through the liquid crystal panel 21 and emitted to realize the wide field of view display. [0077] As shown in FIG. 6 , when light of the distribution 38 emitted from the backlight 13 is made incident on the louver 12 , light spreading in the X direction is absorbed by the louver 12 to change to light of the distribution 39 with high directivity that is distributed in substantially in a round shape. In the case of the narrow field of view display, when the light of this distribution 39 is made incident on the transparent and scattering switching element 22 in the transparent state, light of a circular distribution is transmitted through the transparent and scattering switching element 22 directly and light of the distribution 39 is emitted. The light of this distribution 39 is transmitted through the liquid crystal panel 21 and emitted to realize the narrow field of view display. [0078] Next, an operation of the liquid crystal display device in accordance with the first embodiment formed as described above will be explained. First, a case of the wide field of view display will be explained. As shown in FIG. 1 , light emitted from the backlight 13 is made incident on the louver 12 . As shown in FIG. 3 , light emitted from the backlight 13 is diffused light, and θ and φ have wide distributions. In the backlight 13 shown in FIG. 2 , as shown in FIG. 5 , light emitted from the backlight 13 has a larger value of θ in the case in which φ is close to 0 degree or 180 degrees than in the case in which φ is close to 90 degrees or 270 degrees. In other words, the light has the elliptical distribution 38 spreading widely in the X direction compared with the Y direction. When the light of this distribution 38 is made incident on the louver 12 , light with large θ is absorbed by the absorption area 12 b of the louver 12 . Light with small θ is transmitted through the transparent area 11 a . Therefore, in light emitted from the louver 12 , the light with large θ is removed and light of the distribution 39 with a small distribution area and high directivity is emitted. [0079] As shown in FIG. 1 , the light of the distribution 39 with high directivity emitted from the louver 12 is made incident on the transparent and scattering switching element 22 . In the case of the wide field of view display, a voltage is not applied to the PDLC layer 11 . Consequently, the PDLC layer 11 is in a state in which the liquid crystal molecules 11 b are scattered at random in the polymer matrix 11 a , and the incident light is scattered. Therefore, as shown in FIG. 5 , light of the circular distribution 39 is uniformly scattered by the PDLC layer 11 to change to light of the circular distribution 40 spreading more largely. In other words, the light, directivity of which is improved by the louver 12 , is scattered by the transparent and scattering switching element 22 to have lower directivity and change to light with a wide angle. As shown in FIG. 1 , the light of the distribution 40 spreading in a wide range is made incident on the liquid crystal panel 21 and emitted while keeping the distribution 40 . In this way, an image is displayed in a wide angle of field. [0080] Next, a case of the narrow field of view display will be explained. As shown in FIG. 6 , as in the case of the wide field of view display, light having the elliptical distribution 38 emitted from the backlight 13 is changed to light of the distribution 39 with a small distribution area and high directivity by the louver 12 . [0081] As shown in FIG. 1 , the light of the distribution 39 is made incident on the transparent and scattering switching element 22 . In the case of the narrow field of view display, a predetermined voltage is applied to the PDLC layer 11 . Consequently, the PDLC layer 11 comes into the transparent state in which the liquid crystal molecules 11 b scattered in the polymer matrix 11 a are oriented. In other words, the PDLC layer 11 transmits incident light directly. Therefore, as shown in FIG. 6 , the light of the circular distribution 39 is transmitted through the PDLC layer 11 directly. In other words, the light, directivity of which is improved by the louver 12 , is emitted from the transparent and scattering switching element 22 in a state of the distribution 39 keeping high directivity. As shown in FIG. 1 , the light of the distribution 39 with high directivity is made incident on the liquid crystal panel 21 and emitted while keeping the distribution 39 . In this way, an image is displayed at a narrow angle of field. [0082] In this way, light with low directivity emitted from the backlight 13 is converted into light with high directivity by the louver 12 , and the light with high directivity is transmitted or scattered by the transparent and scattering switching element, which uses the PDLC layer, to switch the narrow field of view display and the wide field of view display. Consequently, it is possible to increase a variable width of an irradiation angle of light in the planar light source and increase a variable width of an angle of field of the liquid crystal display device that uses the planar light source. [0083] Here, the same liquid crystal display device as the first embodiment is constituted using the conventional prism sheet instead of the louver 12 to measure a relation between an angle of field and a luminance in the case of the narrow field of view display. A range of an angle of field of 0 degree, that is, an angle of field, at which a luminance of a value equal to or larger than half a luminance at the time when the liquid crystal display device is viewed from the front is obtained, is 30 degrees to the left and the right. On the other hand, in the first embodiment, a range of an angle of field, at which a luminance of a value equal to or larger than half a luminance at the angle of field 0 degree is obtained, is 20 degrees to the left and the right. In this way, in the first embodiment, it is possible to realize the narrow field of view display effectively compared with the conventional technique. [0084] Next, a first modification of the first embodiment of the invention will be explained. FIG. 7 is a plan view showing an example of a louver that is used in a liquid crystal, display device in accordance with the first modification of the first embodiment. In the first embodiment described above, as shown in FIG. 4 , the transparent area 12 a and the absorption area 12 b of a stripe shape are arranged alternately on the surface of the louver 12 when the louver 12 is viewed from a direction perpendicular to the surface. Thus, directivity of light made incident on the louver 12 can be improved only in one direction. On the other hand, in the first modification of the first embodiment, as shown in FIG. 7 , a circular transparent area 12 a is arranged in the absorption area 12 b in a matrix shape when the louver 12 is viewed from a direction perpendicular to the surface of the louver 12 . Consequently, it is possible to improve directivity of light made incident on the louver 12 in various directions. Components, operations, and effects in the first modification of the first embodiment other than those described above are the same as those in the first embodiment. [0085] Next, a second modification of the first embodiment will be explained. FIG. 8 is a plan view showing an example of a louver that is used in a liquid crystal display device in accordance with the second modification of the first embodiment. In the first modification of the first embodiment, as shown in FIG. 7 , the circular transparent area 12 a is arranged in the absorption area 12 b in a matrix shape. On the other hand, in the second modification of the first embodiment, as shown in FIG. 8 , a quadrangle transparent area 12 a is arranged in the absorption area 12 b in a matrix shape when the louver 12 is viewed from a direction perpendicular to the surface of the louver 12 . The transparent area 12 a is, for example, a square or a rectangle. Components, operations, and effects in the second modification of the first embodiment other than those described above are the same as those in the first modification of the first embodiment. [0086] Next, a third modification of the first embodiment of the invention will be explained. FIG. 9 is a diagram showing a light distribution characteristic at the time of a wide angle of field of a liquid crystal display device in accordance with a third modification of the first embodiment. FIG. 10 is a diagram showing a light distribution characteristic at the time of a narrow angle of field. [0087] In the first embodiment, as shown in FIG. 5 , light emitted from the backlight 13 has the elliptical distribution 38 spreading in the X direction widely compared with the Y direction. When the light of this distribution 38 is made incident on the louver 12 , the light spreading in the X direction is absorbed by the louver 12 to change to light of the distribution 39 with high directivity that is distributed substantially in a round shape. In the case of the wide field of view display, when the light of this distribution 39 is made incident on the transparent and scattering switching element 22 in the scattering state, light of a circular distribution is uniformly scattered to change to light of the circular distribution 40 spreading more largely. The light of this distribution 40 is transmitted through the liquid crystal panel 21 and emitted to realize the wide field of view display. In addition, as shown in FIG. 6 , when light of the distribution 38 emitted from the backlight 13 is made incident on the louver 12 , light spreading in the X direction is absorbed by the louver 12 to change to light of the distribution 39 with high directivity that is distributed substantially in a round shape. In the case of the narrow field of view display, when the light of this distribution 39 is made incident on the transparent and scattering switching element 22 in the transparent state, light of a circular distribution is transmitted through the transparent and scattering switching element 22 directly and light of the distribution 39 is emitted. The light of this distribution 39 is transmitted through the liquid crystal panel 21 and emitted to realize the narrow field of view display. [0088] On the other hand, in the third modification of the first embodiment, as shown in FIG. 9 , light emitted from the backlight 13 has an elliptical distribution 41 spreading widely in the Y direction compared with the X direction. When the light of this distribution 41 is made incident on the louver 12 , directivity of light spreading in the X direction is further improved by the louver 12 and, in particular, light distributed in the X direction changes to light of a distribution 42 having high directivity. In the case of the wide field of view display, when the light of this distribution 42 is made incident on the transparent and scattering switching element 22 in the scattering state, the light scatters to spread in the X direction to change to light of a distribution 43 . The light of this distribution 43 is transmitted through the liquid crystal panel 21 and emitted to realize the wide field of view display. In addition, as shown in FIG. 10 , when the light of the distribution 41 emitted from the backlight 13 is made incident on the louver 12 , directivity of light spreading in the X direction is further improved by the louver 12 and, in particular, light distributed in the X direction changes to light of the distribution 42 having high directivity. In the case of the narrow field of view display, when the light of this distribution 42 is made incident on the transparent and scattering element 22 in the transparent state, in particular, light of a distribution having high directivity of light distributed in the X direction is transmitted through the transparent and scattering switching element 22 directly and light of the distribution 42 is emitted. The light of this distribution 42 is transmitted through the liquid crystal panel 21 and emitted to realize the narrow field of view display with respect to the X direction. [0089] In the third modification of the first embodiment, compared with the first embodiment, since an amount of light, which is emitted from the backlight 13 and absorbed by the louver 12 , can be reduced, it is possible to realize bright wide field of view display. In particular, since an amount of light of the backlight 13 is limited, the third modification is effective in the case in which switching of an angle of field only in the X direction has to be realized. Components, operations, and effects in the third modification of the first embodiment other than those described above are the same as those in the first embodiment. [0090] Next, a second embodiment of the invention will be explained. FIG. 11 is a sectional view showing a liquid crystal display device in accordance with the second embodiment. In the first embodiment described above, as shown in FIG. 1 , the one louver 12 , in which the transparent area 12 a and the absorption area 12 b of a stripe shape are arranged alternately, is provided between the backlight 13 and the transparent and scattering switching element 22 . On the other hand, in the second embodiment, as shown in FIG. 11 , a louver 15 , in which a transparent area 15 a and an absorption area 15 b of a stripe shape are arranged alternately in one direction, and a louver 14 , in which a transparent area 14 a and an absorption area (not shown) of a stripe shape are arranged alternately in a direction orthogonal to an arrangement direction in the louver 15 , are stacked to be provided between the backlight 13 and the transparent and scattering switching element 22 . Consequently, in the second embodiment, it is possible to improve directivity of light made incident on the louver 12 not only in one direction but also in a direction orthogonal to the direction. Therefore, for example, it is possible to realize the narrow field of view display effectively not only in the horizontal direction but also in the vertical direction. Components, operations, and effects in the second embodiment other than those described above are the same as those in the first embodiment. [0091] Next, a third embodiment of the invention will be explained. FIG. 12 is a sectional view showing a liquid crystal display device in accordance with the third embodiment. In the first embodiment described above, as shown in FIG. 1 , the conventional PDLC layer 11 , in which the liquid crystal molecules 11 b are scattered uniformly in the polymer matrix 11 a , is used as the planar transparent and scattering switching element 22 . On the other hand, in the third embodiment, as shown in FIG. 12 , a PDLC layer 16 , which is modulated such that distribution of liquid crystal molecules 16 b scattered in a polymer matrix 16 a has unevenness cyclically, is used. In the modulated PDLC layer 16 , for example, a portion where the liquid crystal molecules 11 b are dense and a portion where the liquid crystal molecules 11 b are sparse are repeated cyclically in one direction. The modulated PDLC layer 16 scatters incident light intensely in the direction in which the portion where the liquid crystal molecules 11 b are dense and the portion where the liquid crystal molecules 11 b are sparse are repeated cyclically. Consequently, it is possible to increase an angle of field in this direction. [0092] That is, in the transparent and scattering switching element, the polymer dispersed liquid crystal layer 16 may include a high density portion where a density of the liquid crystal molecules is high and a low density portion where a density of the liquid crystal molecules is low, and the high density portion and the low density portion may be formed alternately in a direction perpendicular to the light regulating direction. [0093] It is possible to manufacture such a modulated PDLC layer 16 by using the same material as the conventional PDLC layer for a PDLC layer and subjecting the PDLC layer to exposure and photo-curing via a photo-mask. Light is irradiated on the PDLC layer before curing via a photo-mask on which a linear pattern is formed cyclically. A part irradiated by the light starts to harden. At this point, a concentration gradient of the liquid crystal molecules 16 b occurs between a hardening area and a not-hardening area. After the PDLC layer is subjected to the exposure for a predetermined time via the photo-mask, the entire surface of the PDLC layer is exposed to light, whereby the modulated PDLC layer 16 is obtained. In this modulated PDLC layer 16 , a mixture of two or more kinds of liquid crystal molecules with different sizes may be used as the liquid crystal molecules 16 b . Components, operations, and effects in the third embodiment other than those described above are the same as those in the first embodiment. [0094] Next, a fourth embodiment of the invention will be explained. FIG. 13 is a sectional view showing a liquid crystal display device in accordance with the fourth embodiment. In the fourth embodiment, as shown in FIG. 13 , in addition to the structure of the liquid crystal display device in accordance with the first embodiment, the liquid crystal display device further includes a light source light intensity control unit 26 that controls an amount of an electric current to be supplied to a white LED 25 and adjusts an amount of light, that is, a luminance of the white LED 25 and a transparent and scattering switching element control unit 27 that switches ON and OFF of a voltage of the transparent and scattering switching element 22 . The light source light intensity control unit 26 and the transparent and scattering switching element control unit 27 are constituted to be associated with each other. Components in the fourth embodiment other than those described above are the same as those in the first embodiment. [0095] Next, operations of the liquid crystal display device in accordance with the fourth embodiment constituted as described above will be explained. As shown in FIG. 13 , in the case of the wide field of view display, the transparent and scattering switching element control unit 27 does not apply a voltage to the transparent and scattering switching element 22 . Consequently, light made incident on the transparent and scattering switching element 22 from the louver 12 is scattered. At this point, the light source light intensity control unit 26 supplies an electric current to the white LED 25 such that a front luminance, that is, a luminance at an angle of field of 0 degree of the liquid crystal panel 21 takes a predetermined value. In the case of the narrow field of view display, the transparent and scattering switching element control unit 27 applies a voltage to the transparent and scattering switching element 22 . Consequently, light made incident on the transparent and scattering switching element 22 from the louver 12 is transmitted through the transparent and scattering switching element 22 directly. Therefore, when an amount of an electric current supplied to the white LED 25 is the same, that is, an amount of light emitted from the backlight 13 is the same, a front luminance of the liquid crystal panel 21 is excessively large. Thus, the amount of electric current supplied to the white LED 25 is adjusted such that the front luminance of the liquid crystal panel 21 in the case of the narrow field of view display takes as same value as that in the case of the wide field of view display. Consequently, in the fourth embodiment, the front luminance of the liquid crystal panel 21 is kept constant. Note that, in the case in which the white LED 25 is constituted by a blue LED and a yellow phosphor, an amount of light of the white LED 25 may be adjusted by pulse width modulation of an electric current. In the white LED 25 constituted by the blue LED and the yellow phosphor, the yellow phosphor is excited by a part of blue light emitted by the blue LED to emit yellow light, and the blue light and the yellow light are mixed to generate white light. When an amount of an electric current is adjusted such that the front luminance of the liquid crystal panel 21 in the case of the narrow field of view display takes a value equivalent to that in the case of the wide field of view display, since an emission ratio of the blue light and the yellow light fluctuates, chromaticity change of the liquid crystal panel 21 occurs. On the other hand, when an amount of light is adjusted by the pulse modulation, the adjustment of an amount of light is realized by adjusting a ratio of light emitting time, it is possible to control chromaticity change of the liquid crystal panel 21 . Operations and effects in the fourth embodiment other than those described above are the same as those in the first embodiment. [0096] Next, a fifth embodiment of the invention will be explained. FIG. 14 is a sectional view showing a liquid crystal display device in accordance with the fifth embodiment. In the fourth embodiment described above, as shown in FIG. 13 , the white LED 25 and the linear light source 36 are used. On the other hand, in the fifth embodiment, as shown in FIG. 14 , a light source, in which a red LED 28 , a green LED 29 , and a blue LED 30 are arranged linearly and cyclically, is used instead of the linear light source 36 . The liquid crystal display device includes the light source light control unit 26 that controls amounts of electric currents to be supplied to the red LED 28 , the green LED 29 , and the blue LED 30 and adjusts amounts of lights, that is, luminances of the LEDs. Components in the fifth embodiment other than those described above are the same as those in the fourth embodiment. [0097] Next, operations of the liquid crystal display device in accordance with the fifth embodiment constituted as described above will be explained. As shown in FIG. 14 , lights emitted from the red LED 28 , the green LED 29 , and the blue LED 30 are made incident on the backlight 13 . Red, green, and blue are three primary colors of light, and lights of these colors are superimposed to form white light. The backlight 13 converts incident light into planar light. In the case of the wide field of view display, this light is made incident on the transparent and scattering switching element 22 and scattered. At this point, since a degree of scattering of light depends on a wavelength of the light, light with a shorter wavelength is scattered more intensely and light with a longer wavelength is less likely to be scattered. In other words, blue light is likely to be scattered and red light is less likely to be scattered. Therefore, a display image at the time when the liquid crystal panel is viewed from the front is reddish. [0098] Thus, when light is scattered by the transparent and scattering switching element 22 , for example, an amount of an electric current supplied to the blue LED 30 is increased to intensify blue light that is likely to be scattered, and an amount of an electric current supplied to the red LED 28 is reduced to weaken red light that is less likely to be scattered. In this way, in the wide field of view display and the narrow field of view display, intensity of lights emitted by the red LED 28 , the green LED 29 , and the blue LED 30 are adjusted in association with presence or absence of application of a voltage to the transparent and scattering switching element 22 , whereby a tint of a display image at the time when the liquid crystal panel is viewed from the front can be kept constant. Operations and effects in the fifth embodiment other than those described above are the same as those in the fourth embodiment. [0099] Next, a sixth embodiment of the invention will be explained. FIG. 15 is a sectional view showing a liquid crystal display device in accordance with the sixth embodiment. In the sixth embodiment, in addition to the structure of the liquid crystal display device in accordance with the first embodiment, transparent substrates 121 are provided on both sides of the louver 12 . In an example, a material of the transparent substrates 121 is polyethylene terephthalate. Components in the sixth embodiment other than those described above are the same as those in the first embodiment. [0100] In the liquid crystal display device in accordance with the sixth embodiment constituted as described above, since the transparent substrates 121 are provided on both the sides of the louver 12 , there is an effect that it is possible to improve resistance of the louver 12 against changes in temperature and humidity, and reliability of the liquid crystal display device is improved. Operations and effects in the sixth embodiment other than those described above are the same as those in the first embodiment. In addition, the sixth embodiment can also be applied to the second to the fifth embodiments. [0101] Next, a seventh embodiment of the invention will be explained. FIG. 16 is a sectional view showing a liquid crystal display device in accordance with the seventh embodiment. Whereas the louver and the transparent and scattering switching element are fixed by a couple-face tape in the sixth embodiment, in the seventh embodiment, the louver 12 having the transparent substrates 121 on both the sides thereof and the transparent and scattering switching element 22 are bonded and, as a result, formed integrally. Components in the seventh embodiment other than those described above are the same as those in the sixth embodiment. [0102] In the liquid crystal display device in accordance with the seventh embodiment constituted as described above, the transparent substrates 121 are provided on both the sides of the louver 12 and, in addition, the louver 12 and the transparent and scattering switching element 22 are formed integrally. Thus, it is possible to improve resistance of the louver 12 against changes in temperature and humidity and improve reliability of the liquid crystal display device. It is also possible to reduce thickness of the liquid crystal display device. Operations and effects in the seventh embodiment other than those described above are the same as those in the sixth embodiment. [0103] Next, an eighth embodiment of the invention will be explained. FIG. 17 is a sectional view showing a liquid crystal display device in accordance with the eighth embodiment. Compared with the structure of the liquid crystal display device in accordance with the seventh embodiment, the eighth embodiment is characterized in that the louver 12 and the transparent and scattering switching element 22 are integrally formed and have a common substrate. In this example, the louver 12 has the transparent substrates 121 on both the sides thereof, and the substrate 121 of the louver 12 is also used as a transparent substrate on the transparent and scattering switching element 22 side. Thus, the transparent and scattering switching element 22 does not have the transparent substrate 9 on the louver 12 side. Components in the eighth embodiment other than those described above are the same as those in the seventh embodiment. [0104] As described above, in the liquid crystal display device in accordance with the eighth embodiment, it is possible not only to improve reliability as in the liquid crystal display device in accordance with the seventh embodiment but also to reduce thickness of the liquid crystal display device. In addition, since the number of substrates constituting the liquid crystal display device can be reduced, it is also possible to reduce weight of the liquid crystal display device. Operations and effects in the eighth embodiment other than those described above are the same as those in the seventh embodiment. [0105] Next, a ninth embodiment of the invention will be explained. FIG. 18 is a sectional view showing a liquid crystal display device in accordance with the ninth embodiment. Compared with the structure of the liquid crystal display device in accordance with the eighth embodiment, in the ninth embodiment, the louver 12 has only the transparent substrate 121 common to the louver 12 and the transparent and scattering switching element 22 and does not have a transparent substrate on the backlight 13 side. Components in the ninth embodiment other than those described above are the same as those in the eighth embodiment. [0106] In the liquid crystal display device in accordance with the ninth embodiment constituted as described above, since the transparent substrate on the backlight 13 side of the louver 12 is not provided, reliability is lower than the reliability of the liquid crystal display device in accordance with the eighth embodiment. However, since the transparent substrate 121 is set on the transparent and scattering switching element 22 side, it is possible to improve reliability compared with the first embodiment. In addition, compared with the liquid crystal display device in accordance with the eighth embodiment, in the ninth embodiment, since the transparent substrate of the louver 12 can be removed, it is possible to further reduce thickness and weight of the liquid crystal display device. Operations and effects in the ninth embodiment other than those described above are the same as those in the eighth embodiment. [0107] Next, a tenth embodiment of the invention will be explained. FIG. 19 is a sectional view showing a liquid crystal display device in accordance with the tenth embodiment. Compared with the structure of the liquid crystal display device in accordance with the first embodiment, the liquid crystal display device in accordance with the tenth embodiment is different in that the high directivity backlight 213 described in the monthly magazine “Display” May 2004, pages 14 to 17 is used. Components in the tenth embodiment other than those described above are the same as those in the first embodiment. [0108] In the liquid crystal display device according to the tenth embodiment constituted as described above, since the high directivity backlight 213 with directivity improved two-dimensionally on a light emitting surface thereof is used, it is possible to reduce a loss in absorption of light by the louver 12 and realize bright display. In addition, since the directivity of the backlight is two-dimensional, it is also possible to show an effect of switching of an angle of field concerning a direction orthogonal to the direction in which the transparent area and the absorption area of the louver 12 are arranged alternately. Note that the high directivity backlight suitably used in the embodiment is not limited to the high directivity backlight described in the monthly magazine “Display” May 2004, pages 14 to 17, and it is possible to apply any backlight to the liquid crystal display device as long as directivity thereof is improved two-dimensionally. [0109] FIG. 20 is a graph showing a result of an experiment in which a slight voltage is applied to the transparent and scattering switching element 22 in the scattering state to adjust a scattering property in the liquid crystal display device in accordance with the tenth embodiment. In the graph, a horizontal axis indicates an angle of field and a vertical axis indicates a luminance. A result indicated by a broken line is a luminance distribution in the case in which a voltage is not applied to a PDLC layer constituting a transparent and scattering switching element, and a result indicated by a solid line is a luminance distribution in the case in which a slight voltage (in an example, 1 volt) is applied to the PDLC layer. Note that the slight voltage in this context means a small voltage compared with a voltage for bringing the transparent and scattering switching element into a transparent state. Whereas a front luminance (a luminance in a 0° direction) in the case in which a voltage is not applied to the PDLC layer is 75 cd/m 2 , a front luminance in the case in which a slight voltage is applied is improved to 120 cd/m 2 . On the other hand, in an oblique direction, more specifically, in a range from +25° to +80° or a range from −25° to −80°, although a luminance in the case in which a voltage is applied slightly falls, a degree of the fall in the voltage is extremely small, and a luminance of substantially the same degree as that in the case in which a voltage is not applied is secured. This indicates that it is possible to improve a luminance in a front direction significantly without decreasing the luminance in the oblique direction significantly by applying a slight voltage at the time of scattering of the transparent and scattering switching element to slightly decrease the scattering property. This result is effective in the case in which a front luminance falls in the wide field of view display, due to limited amount of light of the back light. Although the tenth embodiment is explained, the explanation is not limited to the tenth embodiment but is applicable to the other embodiments as well. Operations and effects in the tenth embodiment other than those described above are the same as those in the first embodiment. [0110] Next, an eleventh embodiment of the invention will be explained. FIG. 21 is a perspective view showing a portable terminal device mounted with the liquid crystal display device of the invention. As shown in FIG. 21 , a liquid crystal display device 100 of the invention is mounted on, for example, a cellular phone 90 . [0111] The liquid crystal display device of the invention can be applied to a portable device such as a cellular phone and makes it possible to perform display for switching an angle of field. In particular, in the case in which the liquid crystal display device of the invention is mounted on a cellular phone, a transparent area and an absorption area of a louver serving as a ray direction regulating element are arranged alternately at least in a lateral direction of the cellular phone, whereby it is possible to switch the wide field of view display and the narrow field of view display with respect to the lateral direction of the cellular phone. This makes it possible to prevent a peep by other people from the lateral direction in public transportation facilities and the like. Note that the portable device is not limited to the cellular phone, and it is possible to apply the liquid crystal display device to various portable terminal devices such as a Personal Digital Assistant (PDA), a game machine, a digital camera, and a digital video camera. Moreover, the portable device mounted with the liquid crystal display device of the invention may have a setting for changing amounts of a light source at the time of the wide field of view display and the narrow field of view display independently from each other and may be capable of setting light emitting ratios of the light source in both the cases. Consequently, a user can set an optimum angle of field according to an environment of use. Furthermore, the portable device may have means for detecting residual battery power and have control means that can automatically change an angle of field according to the detected residual battery power. As described above, in the liquid crystal display device of the invention, since an electric power can be reduced more at the time of narrow field of view display than at the time of the wide field of view display, it is possible to reduce power consumption by automatically changing the wide field of view display to the narrow field of view display when residual battery power is low and extend an operating time of the portable device. [0112] Next, a twelfth embodiment of the invention will be explained. FIG. 22 is a plan view showing the transparent and scattering switching element 22 of a liquid crystal display device in accordance with the twelfth embodiment. Compared with the structure of the first embodiment, the twelfth embodiment is different in that at least one side of the electrodes 10 of the transparent and scattering switching element 22 is machined in a line shape. Components in the twelfth embodiment other than those described above are the same as those in the first embodiment. [0113] In the liquid crystal display device in accordance with the twelfth embodiment constituted as described above, it is possible to perform switching of transparent and scattering partially in plane by applying different voltages to the electrodes 10 machined in a line shape of the transparent and scattering switching element 22 . Consequently, for example, it is possible to change the transparent and scattering switching element 22 to transparent only for a portion where confidential information is displayed on the basis of image information displayed on the liquid crystal display device to perform the narrow field of view display. Note that a shape of the electrodes 10 of the transparent and scattering switching element 22 is not limited to the line shape but may be a block shape. [0114] Consequently, it is possible to switch the narrow field of view display and the wide field of view display in a block shape. In addition, in the two transparent substrate arranged above and below the PDLC layer, the electrodes may be machined in a line shape, respectively, and arranged such that longitudinal directions thereof are orthogonal to each other. This makes it possible to perform passive matrix drive for the transparent and scattering switching element 22 and switch an angle of field of an arbitrary portion on a screen. Operations and effects in the twelfth embodiment other than those described above are the same as those in the first embodiment. [0115] Note that, as the PDLC layer that is used in the respective embodiments and the respective modifications, a PDLC layer, which is in the scattering state when a voltage is not applied thereto and is in the transparent state at the time of voltage application. Consequently, the transparent and scattering switching element does not consume electric power when the transparent and scattering switching element is in a state in which the transparent and scattering switching element scatters incident light. Thus, since the electric power is allocated to the backlight power supply, it is possible to improve brightness of the planar light source at the time of the scattering state. However, a form of the PDLC layer is not limited to the above, and a PDLC layer, which is in the transparent state when a voltage is not applied thereto and in the scattering state at the time of voltage application, may be used. Such a PDLC layer is obtained by exposing a material to light to harden the material while applying a voltage thereto. Consequently, in the portable information terminal, it is unnecessary to apply a voltage to the PDLC layer and it is possible to control power consumption in the narrow field of view display that is used frequently. [0116] In addition, cholesteric liquid crystal, ferroelectric liquid crystal, or the like may be used as the liquid crystal molecules used in the PDLC layer. The liquid crystal keeps an orientation state at the time when a voltage is applied thereto even if an applied voltage is turned OFF and has a memory property. It is possible to reduce power consumption by using such a PDLC layer. [0117] As shown in FIG. 23 , a direction in which the transparent area and the absorption area of the ray direction regulating element and a pixel arrangement direction of the liquid crystal display panel may be not parallel to each other. Consequently, it is possible to reduce moiré due to the ray direction regulating element and the display panel and improve an image quality of the liquid crystal display device. [0118] The display panel, which is used in combination with the planar light source of the invention, is not limited to the transparent liquid crystal panel. Any display panel may be used as long as the display panel uses a backlight. In particular, it is possible to use a liquid crystal panel with less dependency on an angle of field suitably. As an example of a mode of such a liquid crystal panel, in a lateral electric field mode, there are an IPS (In-Plane Switching) system, an FFS (Fringe Field Switching) system, an AFFS (Advanced Fringe Field Switching) system, and the like. In addition, in a vertical orientation mode, there are an MVA (Multi-domain Vertical Alignment) system, a PVA (Patterned Vertical Alignment) system, an ASV (Advanced Super V) system, and the like in which a liquid crystal panel is multi-domained to reduce dependency on an angle of field. It is also possible to use the invention in a liquid crystal display panel of a film compensation TN mode suitably. By using these liquid crystal panels with less dependency on an angle of field, it is possible to control tone reversal of display when the transparent and scattering switching element is in the scattering state and improve visibility. In addition, the liquid crystal panel is not limited to the transmission liquid crystal panel, and any panel may be used as long as the panel has a transmission area in each pixel. It is also possible to use a semi-transmission liquid crystal panel, a micro-transmission liquid crystal panel, and a micro-reflection liquid crystal panel that have a reflection area in a part of each pixel. Note that the reflection area does not always need to have reduced dependency on an angle of field, and only the transmission area may have reduced dependency on an angle of field.

A planar light source includes a backlight that emits light in a planar shape, a ray direction regulating element that regulates a direction of light made incident from the backlight and emits the light, whereby a directivity of the light is improved, and in which a transparent area for transmitting light and an absorption area for absorbing light are formed, and a transparent and scattering switching element that is switchable between a state in which light which is transmitted by the ray direction regulating element and made incident on the switching element is transmitted and a state in which the light is scattered. The transparent areas are formed in a shape of a matrix including a plurality of rows and a plurality of columns, the transparent and absorption areas are formed alternately, and the absorption area is formed so that the transparent areas are separated.

FIELD OF THE INVENTION [0001] The present invention relates to a glitter combining antibacterial property and aesthetic appreciation property, and to a cloth with the glitter concerned adhered therein. BACKGROUND ART [0002] In recent years, as consumer's clean inclination increases and process of production and freshness management of meat and agricultural products, marine products, flowering plant and the like are needed, a nonwoven fabric equipped with antibacterial property is used in the field of packaging materials. And as such antibacterial nonwoven fabrics, conventionally nonwoven fabrics in which organic antibacterial agents, animal protein derived antibacterial agents, such as chitosan, vegetable antibacterial agents, such as hinokitiol, and mineral antibacterial agents, such as silver zeolite are impregnated or adhered may be mentioned. [0003] Moreover, packaging materials made of nonwoven fabric in which ornament of metal color is given are used based on consumer's taste. And as nonwoven fabrics with ornament given that are used for such a usage, there are nonwoven fabrics adhered by a glitter equipped with aesthetic appreciation property of metallic luster, such as a glitter in which metal, such as aluminium, is vapor-deposited on a synthetic resin film, and a resultant laminated film is finely cut; a glitter in which a protective layer that protects the above-described metal vapor deposition side is prepared on a laminated film; or a glitter in which metal vapor deposition side of a laminated film and a synthetic resin film are dyed. [0004] Furthermore, in order to improve air conditioning efficiency, heat insulation film is adhered on windshields of cars and on windowpanes of buildings and the like, and many of such heat insulation films are constituted by laminated films in which metals are vapor-deposited onto one side of a synthetic resin film and adhesive layer is prepared on the vapor-deposited metal layer. [0005] However, in addition to a problem that although a certain conventional antibacterial nonwoven fabric has antibacterial property, antibacterial agent easily separates and falls by washing, and it had a problem that it was not provided with aesthetic appreciation property. Moreover, such an antibacterial nonwoven fabrics had a problem that they could not block or scatter harmful electric wave and electromagnetic wave. [0006] Moreover, although conventional nonwoven fabric with ornament given therein is equipped with aesthetic appreciation property in metal color, it had problems that it did not have antibacterial property, or that handling was difficult for being easy to adhere to an undesirable place by static electricity charging because of aluminium and the like used therein. [0007] Furthermore, although conventional heat insulation films were equipped with outstanding insulation property of heat, it had problems that they could not be used for textiles, such as garments, by reasons of shapes, stiffness, weight and the like. [0008] Then, the present invention aims at providing a glitter that provides antibacterial property, insulation of electromagnetic wave, aesthetic appreciation property in metal color, antistatic property, and insulation of heat to the textiles concerned by being used to the textiles, and a cloth with the glitter concerned adhered therein. DESCRIPTION OF THE INVENTION [0009] Namely, a glitter according to the present invention is characterized in that antibacterial metal is vapor-deposited on a first synthetic resin film to form a vapor deposition membrane, a synthetic resin is coated on a surface of antibacterial metal of the above-described vapor deposition membrane, or a second synthetic resin film is adhered to a surface of the antibacterial metal of the above-described vapor deposition membrane to form a laminated film, and the above-described laminated film is finely cut. In addition, antibacterial metal is a metal having antibacterial properties in which ion exchange is enabled, such as silver, steel, and zinc. [0010] Moreover, a cloth according to the present invention is characterized in that the above-described glitter is adhered to raw yarns. [0011] Thus, a glitter according to the present invention is equipped with antibacterial property by antibacterial metal, insulation of electromagnetic wave, an antistatic property, and aesthetic appreciation property by metallic luster of an antibacterial metal. In addition, since a glitter according to the present invention is a laminated film finely cut that includes vapor deposition membrane made of antibacterial metal, it may easily be adhered to textiles, such as garments, and thereby an insulation property of heat may be easily given to the textiles. BRIEF DESCRIPTION OF THE DRAWINGS [0012] [0012]FIG. 1 is an appearance view showing an appearance of cloth (nonwoven fabric) according to the present invention; [0013] [0013]FIG. 2 is a partial enlargement view of the nonwoven fabric; [0014] [0014]FIG. 3 is a view showing a constitution of a glitter according to the present invention; [0015] [0015]FIG. 4 is a view illustrating a manufacture of a glitter; and [0016] [0016]FIG. 5 is a view illustrating a manufacture of a nonwoven fabric. BEST MODE FOR CARRYING OUT THE INVENTION [0017] Hereinafter, embodiments of a glitter and cloth (nonwoven fabric) according to the present invention will be described based on drawings. [0018] [0018]FIG. 1 is a view showing an appearance of a nonwoven fabric 1 according to the present invention, and as is shown in the view, nonwoven fabric 1 constitutes a base fabric 2 and the like made of a nonwoven fabric, and adhesion part 1 a to which a glitter 4 mentioned later is adhered is prepared. [0019] [0019]FIG. 2 is a partial enlargement of the adhesion part 1 a , and as is shown in the view, the glitter 4 is adhered to a raw yarn 2 a constituting the base fabric 2 with an adhesive 3 . [0020] The raw yarn 2 a may be either of chemical and synthetic fibers, such as acrylic fiber, nylon fiber, polypropylene fiber, rayon, acetate, cupra, and cellulose fiber (not specified), or natural fiber, such as cotton, hemp, silk, and wool yarn, and two or more of them may be used in combination. [0021] Moreover, the adhesive 3 has starch, povals, or transparent thermoplastic resins as main components, and as such thermoplastic resins, resins currently generally used, such as polyester, polyurethane, acrylic may just be used. [0022] Furthermore, the glitter 4 includes a first synthetic resin film 41 , a vapor deposition membrane 42 , and a second synthetic resin film 43 , as shown in FIG. 3, and is a laminated film with a form of approximately square having a length that the one side of it is about 0.1 mm to about 3 mm. As shown in the view, the four edges are exposed outside and a thickness of a vapor deposition membrane 42 is 25 nm to about 300 nm, and in view of guarantee of function and of cost it is preferable about 50 nm. Here, an antibacterial metal is a metal having antibacterial property in which ion exchange is enabled, such as silver, copper, and zinc, and especially, if a balance of antibacterial property and an aesthetic appreciation property are taken into consideration, use of silver is optimal. Moreover, synthetic resin films 41 and 42 are transparent films with a thickness of about 5 to 100 microns currently made of polyester, nylon and the like. [0023] Now, such a nonwoven fabric 1 is manufactured in following steps shown below. (1) Manufacture of a glitter 4 , and (2) adhesion of the glitter 4 . In addition, a method of manufacture is described based on FIGS. 4 and 5. [0024] (1) Manufacture of a Glitter 4 [0025] First, antibacterial metal is vapor-deposited on one side of the first synthetic resin film 41 to form a vapor deposition membrane 42 (refer to FIG. 4( a )), the second synthetic resin film 43 is adhered to a metal side of the vapor deposition membrane 42 with adhesive and the like (refer to FIG. 4( b )) to form a laminated film 4 a . Next, the laminated film 4 a is cut out by shredder and the like in a shape of fine particles (refer to FIG. 4( c )) to manufacture the glitter 4 . When cutting, in order to set exposure of the vapor deposition membrane 42 greater, it is preferable to be cut in zigzag shape. [0026] (2) Adhesion of the Glitter 4 [0027] First, by intaglio printing method, adhesive 3 is applied on a base fabric 2 , and a layer of adhesive 3 is formed on the base fabric 2 (refer to FIG. 5( a )). In addition, a thickness of the adhesive 3 is preferable to be thinner than the first and second synthetic resin films 41 and 43 so that exposure of the four edges of the vapor deposition membrane 42 may not be prevented. Next, the glitter 4 is sprinkled on a base fabric 2 , thereby whole surface is covered (refer to FIG. 5( b )), and the glitter 4 is heated and pressure-fitted by pressure from above. Finally, the glitter 4 which was not adhered is aspirated (refer to FIG. 5( c )), then the nonwoven fabric 1 is completed. [0028] Thus, since the glitter 4 is adhered to the raw yarns 2 a , the nonwoven fabric 1 is equipped with antibacterial property, insulation of electromagnetic wave, antistatic property, and insulation of heat by vapor deposition membrane 42 included in glitter 4 , and also with aesthetic appreciation property by metallic luster of antibacterial metal. [0029] In addition, the present invention is not limited to the above-described embodiments and Examples, and various modification is possible within a range of technical matter indicated in claims. [0030] For example, in the above-described Example, the second synthetic resin film 43 was adhered with adhesives on the vapor deposition membrane 42 formed on the first synthetic resin film 41 to constitute the laminated film 4 a , and in addition, the synthetic resin may be coated on the vapor deposition membrane 42 to constitute the laminated film. [0031] Moreover, in the above-described Example, although the glitter 4 is adhered to a surface of the base fabric 2 , it may be adhered to an inside thereof depending on a thickness of the base fabric 2 and the like. [0032] Furthermore, in the above-described Example, although nonwoven fabric was used as a base fabric, various cloth, such as woven fabric and knit fabric, may be used. In addition, these cloths are used for garments and also for outer material or lining cloth of a chair, an interior design article, futon, a cushion, a pillow, a bed, rag dolls, and dolls or the like. A cloth with the glitter adhered therein may be adhered on concrete walls, ceilings, floors and the like, and may be built in for usage as electromagnetic wave removal material. [0033] In addition, although the glitter 4 obtained by finely cutting the laminated film 4 a was adhered on the base fabric 2 in the above-described Example, the glitter 4 may be put in a cloth bag and the like to be used as purification material for bathtubs and flower vases or the like, and moreover may be directly applied to wall materials and the like. And it may be equally mixed or adhered with cottons or the like that synthetic resins, such as polyester, are the principal components which are well used as bulking materials and cushioning materials for a chair, an interior design article, futon, a cushion, a pillow, a bed, rag dolls, and dolls or the like. INDUSTRIAL APPLICABILITY [0034] Since a glitter according to the present invention constitutes a laminated film including antibacterial metal, it is equipped with antibacterial property by antibacterial metal, insulation of electromagnetic wave, antistatic property, and aesthetic appreciation property by metallic luster of antibacterial metal. Moreover, the glitter may be easily adhered to textiles, such as garments, and may give insulation of heat easily to the textiles. Furthermore, since such glitter is adhered to raw yarn, a cloth according to the present invention is also equipped with characteristics, such as antibacterial property.

Glitters which are provided with aesthetic, antistatic and heat insulating features due to antibacterial and electromagnetic-wave shielding features and metal colors, and which can be imparted to textile products; and cloth provided with these features. An antibacterial metal is vapor-deposited on a first synthetic resin film to form a deposited film, synthetic resin is spread on the antibacterial metal surface of the deposited film or a second synthetic resin film is bonded to the antibacterial metal surface to form a laminate, and the laminate is shredded into glitters ( 4 ), the glitters then being bonded by an adhesive ( 3 ) to raw yarns ( 2 a ) constituting a base cloth.

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority from Japanese Patent Application Reference No. 2000-070994, filed Mar. 9, 2000, and No. 2000-210690, filed Jul. 6, 2000, the entire contents of which are hereby incorporated by reference. [0002] This application is related to U.S. Ser. No. 09/572,790, filed May 17, 2000 entitled “CRYPTOGRAPHIC APPARATUS AND METHOD”, having Soichi Furuya and Michael Roe listed as inventors, the entire contents of which are hereby incorporated by reference. BACKGROUND OF THE INVENTION [0003] The present invention relates to a technique for ensuring security of confidential information. [0004] Cryptographic processing apparatuses proposed so far employ a block cipher or a stream cipher for concealing data. Various types of block ciphers have been proposed including DES and IDEA. DES and IDEA are described in the following reference. [0005] Reference 1: Menezes, van Oorschot, Vanstone, Handbook of Applied Cryptography, CRC Press, 1996, pp. 250-259, pp. 263-266. [0006] The security of the total cryptographic process of each block cipher and its characteristics are discussed based on a block-cipher operation mode employed, such as ECB, CBC, CFB, OFB, or the counter mode. However, only the iaPCBC mode is known to be capable of performing both cryptographic processing and detection of an alteration at the same time, and other modes cannot detect alterations by themselves. Block-cipher operation modes are described in the following reference. [0007] Reference 2: Schneider, Applied Cryptography, Second Edition, John Wiley & Sons, Inc., 1996, pp. 189-209. [0008] The iaPCBC mode is described in the following reference. [0009] Reference 3: Gligor, Donescu, “Integrity-Aware PCBC Encryption Schemes,” Preproceedings in Secure Protocol Workshop, Cambridge, 1999, to appear in Lecture Notes in Computer Science series, Springer-Verlag. [0010] The iaPCBC mode is an operation mode which uses a block cipher. Regarding encryption, the iaPCBC mode can perform neither parallel processing nor preprocessing, which makes it very difficult to implement the iaPCBC mode in the environment in which processing at extremely high speed is required. [0011] On the other hand, there is a system which generates a cryptographic checksum called a “message authentication code” (hereinafter referred to as “MAC”) in order to detect alterations. By implementing a MAC generation process as an independent mechanism, and executing the process during cryptographic processing in one of the above block-cipher operation modes, it is possible to perform both cryptographic processing and detection of an alteration at the same time. In this case, however, it is necessary to share two completely independent cryptographic keys, one for encryption and the other for alteration detection, and, furthermore, data to be encrypted must be processed twice, that is, for encryption and for MAC generation. As a result, a realized cryptographic system may be complicated or may not be suitable for processing data having an extended length. In addition, the processing speed of the block cipher is slower than the current communication speed, which means that it is difficult to apply any technique using a combination of the block cipher and MAC to processing of the order of gigabit-per-second or terabit-per-second. MAC is described in the following reference. [0012] Reference 4: Menezes, van Oorschot, Vanstone, Handbook of Applied Cryptography, CRC Press, 1996, pp. 352-368. [0013] In contrast with the block cipher, a stream cipher is an encryption mechanism which uses one of various proposed cryptographic pseudorandom number generators. The stream cipher was not able to detect alerations by itself regardless of security or characteristics of each implementation. Well-known stream ciphers, or pseudorandom number generators used for stream ciphers include SEAL, a linear feedback shift register using a nonlinear combination generator, a linear feedback shift register using a nonlinear filter, and a clock-controlled linear feedback shift register. SEAL is described in the following reference. [0014] Reference 5: Schneider, Applied Cryptography, Second Edition, John Wiley & Sons, Inc., 1996, pp. 398-400. [0015] On the other hand, systems based on the above feedback shift registers are described in the following reference. [0016] Reference 6: Menezes, van Oorschot, Vanstone, Handbook of Applied Cryptography, CRC Press, 1996, pp. 203-212. [0017] A technique using a combination of a stream cipher and a MAC can also perform both cryptographic processing and detection of an alteration at the same time, and, furthermore, processing of a stream cipher is 2 to 20 times faster than that of a block cipher. However, as is the case with the combination of a block cipher and MAC, every MAC generation system (meaning every combination of a stream cipher and MAC) requires sharing of two different keys, and processing of a message twice. When considered in detail, the MAC generation system requires a particular mechanism in addition to that necessary for the stream cipher itself, and considerable computational complexity. For example, MAC generation systems such as HMAC and UMAC require a safe hash function having guaranteed cryptographically-collision-free one-way characteristics. This means that it is necessary to implement the above safe function in addition to a stream cipher. HMAC is described in the above Reference 4 (pp. 355, Example 9.67) while UMAC is described in the following reference. [0018] Reference 7: Black, Halevi, Krawczyk, Krovetz, Rogaway, “UMAC: Fast and Secure Message Authentication,” Advances in Cryptology,—CRYPTO '99 Lecture Notes in Computer Science, Vol. 1666, Springer-Verlag, 1999. [0019] Generally, however, hash functions such as SHA-1 and MD5 are very complicated, and are not easy to implement. These hash functions are described in the following reference. [0020] Reference 8: Menezes, van Oorschot, Vanstone, Handbook of Applied Cryptography, CRC Press, 1996, pp. 347-349. [0021] The security of hash functions has not yet been studied adequately in contrast with study of the security of block ciphers. Therefore, a user may not be able to incorporate a hash function because the user cannot rely on the hash function. Of MAC generation systems, MMH uses only a pseudorandom number generator, and requires a very small amount of additional resources such as circuits and programs to add an alteration detection function to the cryptographic process. However, MMH requires a pseudorandom number sequence whose length is as long as that of the message, taking long time to generate necessary random numbers. MMH is described in the following reference. [0022] Reference 9: Halevi, Krawczyk, “MMH: Software Message Authentication in the Gbit/Second Rates,” Fast Software Encryption, 4 th International Workshop, FSE '97, Lecture Notes in Computer Science, Vol. 1267, Springer-Verlag, 1997. [0023] As described above, the prior art techniques are unsatisfactory in terms of ensuring of security and high-speed processing, and therefore it is required to develop a safer and faster cryptographic processing technique. SUMMARY OF THE INVENTION [0024] The present invention provides a safer and faster symmetric-key cryptographic processing technique. [0025] The present invention provides a symmetric-key cryptographic method which is capable of performing alteration detection and decryption at the same time, and whose safety for data confidentiality and data alteration protection is provable. [0026] The present invention provides a symmetric-key cryptographic method which advantageously has preprocessing and parallel processing functions, and which is capable of processing at high speed, capitalizing on the high-speed processing characteristics of the pseudorandom number generator. [0027] The present invention provides a symmetric-key cryptographic method whose processing speed is not only faster than that of the conventional block cipher, but can be made still faster as the amount of resources employed is increased, and which can attain a high level of parallel operation for high-speed processing. [0028] The present invention provides a symmetric-key cryptographic method whose processing speed does not drop even when a very short message is processed. [0029] The present invention provides a symmetric-key cryptographic method which can be implemented by adding a very small circuit or program to stream cipher equipment. [0030] The present invention provides a symmetric-key cryptographic method capable of processing each block using a pseudorandom number sequence as a key stream, and detecting an alteration at the same time. [0031] A symmetric-key cryptographic method according to a first aspect of the present invention generates ciphertext C, using plaintext P, a key stream S, redundancy data (hereinafter simply referred to as a redundancy) R, and an initial value V, where the length of the key stream S is longer than that of the ciphertext C. [0032] Specifically, when the length of the redundancy R is b bits and the length of the plaintext P is L=n*b+t bits (t is an integer equal to or larger than 0 and smaller than b, and n is an integer equal to or larger than 0), this method adds ((b−t) mod b) number of “0” bits and then the redundancy R to the end of the plaintext P to produce a character string having a length of L+((b−t) mod b)+b bits. This length is a multiple of the length b. [0033] This character string is divided into blocks P i (1≦i≦m) each having b bits. The expression “Xi (1≦i≦n)” denotes a string of variables Xi having n elements from 1 to n. In the above case, the key stream must have a length of 2*m*b bits. [0034] This key stream is either shared secretly between the encryption side apparatus and the decryption side apparatus beforehand, or generated from a secret key shared beforehand (this secret key corresponds to an input to a pseudorandom number generator, for example). [0035] The key stream of the above length is divided into two block series, A i and B i (1≦i≦m, each block has b bits). [0036] Letting the feedback initial value F 0 =V, ciphertext blocks C i are calculated by the following formula. (This initial value V is also shared but it is not necessary to keep it secret). F i =P i ^ A i , C i =( F i *B i )^ F i−1 (1≦i≦m). [0037] The obtained cipher blocks C i are concatenated to produce a character string, which is output as ciphertext C. Here, the operators “*” and “^ ” denote multiplication and addition, respectively, in the finite field F2 b . [0038] The corresponding decryption is performed as follows. [0039] If the length of ciphertext C′ is not a multiple of b bits, a rejection indication is output. If it is a multiple of b bits, on the other hand, the ciphertext C′ is divided into blocks C′ i (1≦i≦m′) each having b bits. [0040] By setting key stream blocks A i and B i (1≦i≦m′), and letting the feedback value F′ 0 =V, the following processing is performed. F′ i =( C′ i ^ F′ i−1 )/ B i , P′ i =A i ^ F′ i (1≦i≦m′). [0041] The obtained results P′ i are concatenated to produce a character string, which is stored as decryption results P′. The operator “/” denotes division in the finite field F2 b . [0042] The redundancy R must be restored as the b-bit character string P′ m if no alteration has been made. It is guaranteed that the probability that an attacker who does not know the keys might successfully make an alteration to the ciphertext without changing the redundancy R, which is restored as the character string P′ m , is at most ½ b . Based on the above fact, it is possible to detect alterations by checking whether the character string P′ m is identical to the redundancy R when b is sufficiently large (32 or more). [0043] The symmetric-key cryptographic method of the first aspect is characterized in that influence of an alteration made to a cipher block is propagated to the last block when the ciphertext has been decrypted, whichever cipher block has been altered. Accordingly, even if an attacker makes an alteration without directly changing the redundancy R, it is possible to detect the alteration. [0044] More specifically, after a feedback value for the next block is generated and stored, encryption operation on the current block is performed using a feedback value generated as a result of encryption operation on the previous block. That is, when generated intermediate values are denoted by X t (t=1 . . . n), that is, X 1 , X 2 , . . . X n , in the order of generation, and the feedback value F i for the next block is indicated by the intermediate value X i , and furthermore, the intermediate value to which the feedback value F i−1 generated as a result of operation on the previous block is applied is indicated by X j , the arguments i and j have the relationship i≦j (a necessary condition). [0045] According to the first aspect of the present invention, the probability that an alteration made to ciphertext might pass the alteration detection check is ½ b . However, the method requires division operation in a finite field in decryption, and uses random-number data whose size is twice the size of the plaintext. [0046] Description will be made of a symmetric-key cryptographic method according to a second aspect of the present invention, which does not ensure cryptographic security as high as that provided by the symmetric-key cryptographic method of the first aspect, but can provide more efficient processing, instead. [0047] The symmetric-key cryptographic method of the second aspect processes a message and a redundancy in the same way as they are processed in the symmetric-key cryptographic method of the first aspect. When plaintext with a redundancy has m blocks, a key stream having a length of b*(m+1) bits is required. This key stream is divided into blocks A i (1≦i≦m) and B (B≠0). [0048] Letting the feedback initial value F 0 =V, cipher blocks C i are obtained by the following formula. F i =P i ^ A i , C i =( F i *B )^ F i−1 (1≦i≦m). [0049] The obtained cipher blocks C i are concatenated to produce a character string, which is output as ciphertext C. [0050] The corresponding decryption is performed as follows. [0051] If the length of ciphertext C′ is not a multiple of b bits, a rejection indication is output. If it is a multiple of b bits, on the other hand, the ciphertext C′ is divided into blocks C′ i (1≦i≦m′) each having b bits. [0052] As in the encryption, by setting key stream blocks A i (1≦i≦m′) and B, and letting the feedback value F′ 0 =V, the following processing is performed. F′ i =( C′ i ^ F′ i−1 )/ B, P′ i =A i ^ F′ i (1≦i≦m′). [0053] The redundancy portion is extracted from the obtained series of blocks P′ i , and checked whether it is identical to the predetermined redundancy (the encrypted redundancy R). If the redundancy portion is identical to the predetermined redundancy, the remaining blocks of the series of blocks P′ i are output as a message; otherwise a rejection indication is output. [0054] The redundancy (the encrypted redundancy R) must be restored as the b-bit character string P′ m if no alteration has been made. [0055] The symmetric-key cryptographic method of the second aspect uses a plurality of key streams (each obtained from a different pseudorandom number sequence) during encryption/decryption of blocks (plaintext or ciphertext blocks) Of the plurality of key streams, one is changed for each iteration of the processing while the others are left unchanged, that is, the same key streams are used for all the iterations. More specifically, when two pseudorandom number sequences (key streams) supplied for encryption/decryption of the i-th block are denoted as A i and B i , the key stream A i is changed each time a block is processed, whereas B i is not changed during processing of all the blocks. [0056] According to the second aspect of the present invention, the probability that an alteration made to ciphertext by an attacker who does not know the keys might not be detected in the subsequent alteration detection process is (m−1)/2 b . Generally, the alteration success rate is preferably ½ 32 or less. Since the data length m is set to about 232 at maximum for actual implementation, b is preferably equal to 64 or more. In such a case, multiplication operation in the finite field F2 64 is performed for both encryption and decryption. This operation is implemented by means of hardware at very high speed and low cost. In the case of software implementation, however, high-speed operation may be provided using a symmetric-key cryptographic method according to a third aspect of the present invention as described below. [0057] The symmetric-key cryptographic method according to the third aspect of the present invention uses a longer redundancy. To begin with, the redundancy is set to have b*d bits, assuming that the subsequent processing is carried out in units of b bits. The message and the redundancy are processed in the same way as they are processed in the symmetric-key cryptographic methods of the first and second aspects to produce a series of blocks P i (1≦i≦m,m≦d) composed of the message and the redundancy, each block having b bits. The key stream is set to have a length of b*(m+d) bits, and is divided into two block series A i (1≦i≦m) and B i (≠0,1≦i≦d). [0058] Letting the feedback initial value F (i) 0 =V i (1≦i≦d), cipher blocks C i are calculated by the following formula. F (1) i =P i ^ A i , F (j+1) i =( F (j) i *B j )^ F (j) i−1 (1≦j≦d), C i =F (d+1) i (1≦i≦m). [0059] The obtained cipher blocks C i are concatenated to produce a character string, which is output as ciphertext C. [0060] The corresponding decryption is performed as follows. [0061] If the length of ciphertext C′ is not a multiple of b bits, a rejection indication is output. If it is a multiple of b bits, on the other hand, the ciphertext C′ is divided into blocks C′ i (1≦i≦m′) each having b bits. [0062] As in the encryption, by setting key stream blocks A i (1≦i≦m′) and B i (≈0,1≦i≦d), and letting the feedback initial value F (i) 0 =V i (1≦i≦d), the following processing is performed. F′ (d+1) i =C′ i , F′ (j) i =( F′ (j+1) i ^ F′ (j) i−1 )/ B j (1≦j≦d), P′ i =A i ^ F′ (1) i (1≦i≦m). [0063] The redundancy portion is extracted from the obtained blocks P′ i , and checked whether it is identical to the predetermined redundancy (the encrypted redundancy). If the extracted redundancy is identical to the predetermined redundancy, the remaining blocks of the blocks P′ i are output as a message; otherwise a rejection indication is output. [0064] In the symmetric-key cryptographic method of the third aspect, although a redundancy having a length of b*d bits is used, operations necessary for encryption and decryption are carried out in the finite field F2 b . Multiplication in the finite field F2 b requires a computational amount (computational complexity) only 1/d 2 of that required by multiplication in the finite field F2 b*d However, since the number of required multiplication operations increases by a factor of d, this high-speed processing method possibly takes time about 1/d of the time taken by the conventional method to complete the multiplication operations using a redundancy of the same length. [0065] A symmetric-key cryptographic method according to a fourth aspect of the present invention incorporates the multiplication in the finite field F2 b employed by the symmetric-key cryptographic methods of the first through third aspects into the 3-round Feistel structure. Specifically, the operation A*B is replaced by a function which calculates M 1 =A L ^ ( A R *B L ), M 2 =A R ^ ( M 1 *B R ), M 3 =M 1 ^ ( M 2 *B L ), [0066] and outputs M 3 ∥M 2 (B L and B R can be switched around, as A L and A R , or M 2 and M 3 ). These operations are self-invertible, and therefore the same operations can be used for the corresponding decryption. [0067] A fifth aspect of the present invention relates to a method of dividing a message for processing. Specifically, plaintext P is divided into a predetermined number t of character strings P i (1≦i≦t). The predetermined number t is decided according to a rule on which both the transmitter and the receiver have agreed. Each character string is combined with a different redundancy R i (1≦i≦t) and then encrypted to produce ciphertext C i using a symmetric-key cryptographic method according to one of the above aspects of the present invention. Separately from the above process, all redundancies R i are concatenated to produce plaintext (R 1 ∥R 2 ∥R 3 ∥ . . . ∥R t ), which is then encrypted using a redundancy R shared between the transmitter and the receiver to obtain ciphertext C t+1 . The above pieces of ciphertext (a series of ciphertext blocks) are concatenated (that is, C 1 ∥C 2 ∥C 3 ∥ . . . ∥C t+1 ) to produce the final ciphertext C. [0068] In the corresponding decryption, the ciphertext is divided into t number of character strings according to a predetermined rule, and the character strings are each decrypted separately. If each decryption result is not a reject, and all the redundancies R i are included in the redundancy plaintext (encrypted using the redundancy R in the encryption process, and now obtained as a result of decryption), the decryption results are accepted, and each piece of plaintext obtained as a result of decryption is concatenated in the order of the corresponding redundancy. If any one of the decryption results is a reject, the entire decryption results are rejected. [0069] According to a sixth aspect of the present invention, multiplication in the finite field F2 b in the above five aspects of the present invention is replaced with multiplication in the finite field Fp, where p is a prime number which can be expressed as “2 k +1” using an integer k. [0070] Specifically, the operation a*(b+1)+1 in the finite field Fp is performed instead of the multiplication a*b in the finite field F2 b . This operation can be accomplished by a combination of one multiplication operation, two addition operations, and one shift operation of a 2 b -bit shift register, making it possible to perform multiplication operations in the finite field F2 b using a general-purpose processor at high speed. [0071] The above operation a*(b+1)+1 in the finite field Fp can provide high-speed processing, compared with multiplication in F2 b , which requires b number of exclusive OR operations and b number of shift operations, and compared with multiplication in Fp using a general prime number p, which requires one multiplication operation and one division operation (a division operation requires time a few tens of times longer than that required by an addition operation or a shift operation). [0072] Since the present invention uses pseudorandom numbers, a user can employ a cryptographic primitive which the user believes is most reliable by selecting one from among block ciphers, hash functions, and stream ciphers as the pseudorandom number generator, which means that the security of the system can be easily attributed to the cryptographic primitive which the user has selected. Furthermore, the pseudorandom number generation can be carried out separately from the plaintext and the ciphertext processing, making it possible to employ parallel processing and preprocessing, resulting in processing at high speed. [0073] As for implementation cost, the present invention can avoid additional implementation which is difficult to make, such as the additional implementation of a hash function. [0074] These and other benefits are described throughout the present specification. A further understanding of the nature and advantages of the invention may be realized by reference to the remaining portions of the specification and the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0075] [0075]FIG. 1 is a system configuration employed in embodiments of the present invention; [0076] [0076]FIG. 2 is a flowchart of a plaintext preparation subroutine; [0077] [0077]FIG. 3 is a flowchart of a random number generation subroutine; [0078] [0078]FIG. 4 is a flowchart of an encryption subroutine; [0079] [0079]FIG. 5 is a flowchart of the decryption program shown in FIG. 1. [0080] [0080]FIG. 6 is a flowchart of the ciphertext preparation subroutine shown in FIG. 5; [0081] [0081]FIG. 7 is a flowchart of the decryption subroutine shown in FIG. 5; [0082] [0082]FIG. 8 is a flowchart of the plaintext extraction subroutine shown in FIG. 5; [0083] [0083]FIG. 9 is a flowchart of the redundancy extraction subroutine shown in FIG. 5; [0084] [0084]FIG. 10 is a diagram showing data blocks in encryption; [0085] [0085]FIG. 11 is a diagram showing data blocks in the decryption shown in FIG. 7; [0086] [0086]FIG. 12 is a flowchart of the random number generation 2 subroutine according to a second embodiment of the present invention; [0087] [0087]FIG. 13 is a flowchart of the encryption 2 subroutine of the second embodiment; [0088] [0088]FIG. 14 is a flowchart of the decryption program of the second embodiment; [0089] [0089]FIG. 15 is a flowchart of the decryption 2 subroutine of the second embodiment; [0090] [0090]FIG. 16 is a diagram showing data blocks in the encryption according to the second embodiment; [0091] [0091]FIG. 17 is a diagram showing data blocks in the decryption according to the second embodiment; [0092] [0092]FIG. 18 is a flowchart of the encryption program according to a third embodiment of the present invention; [0093] [0093]FIG. 19 is a flowchart of the random number generation 3 subroutine of the third embodiment; [0094] [0094]FIG. 20 is a flowchart of the encryption 3 subroutine of the third embodiment; [0095] [0095]FIG. 21 is a flowchart of the decryption program of the third embodiment; [0096] [0096]FIG. 22 is a flowchart of the decryption 3 subroutine of the third embodiment; [0097] [0097]FIG. 23 is a diagram showing data blocks in the encryption according to the third embodiment; [0098] [0098]FIG. 24 is a diagram showing data blocks in the decryption according to the third embodiment; [0099] [0099]FIG. 25 is a flowchart of the parallel encryption program according to a fifth embodiment of the present invention; [0100] [0100]FIG. 26 is a flowchart of the parallel decryption program of the fifth embodiment; [0101] [0101]FIG. 27 is a diagram showing data blocks in the encryption according to the fifth embodiment; [0102] [0102]FIG. 28 is a diagram showing data blocks in the decryption according to the fifth embodiment; [0103] [0103]FIG. 29 is a flowchart of the random number generation 4 subroutine according to a fourth embodiment of the present invention; [0104] [0104]FIG. 30 is a flowchart of the plaintext preparation 2 subroutine of the fourth embodiment; [0105] [0105]FIG. 31 is an explanatory diagram showing a padding operation on a message according to the fourth embodiment; [0106] [0106]FIG. 32 is a flowchart of the decryption program of the fourth embodiment; [0107] [0107]FIG. 33 is a flowchart of the plaintext extraction 2 subroutine shown in FIG. 32; [0108] [0108]FIG. 34 is an explanatory diagram showing an extraction operation on decrypted text according to the fourth embodiment; [0109] [0109]FIG. 35 is a diagram showing the configuration of a system for cryptocommunications according to a sixth embodiment of the present invention; [0110] [0110]FIG. 36 is a diagram showing the configuration of an encryption apparatus employed in a cryptocommunication system according to a seventh embodiment of the present invention; [0111] [0111]FIG. 37 is a diagram showing the configuration of a contents delivery system according to an eighth embodiment of the present invention; [0112] [0112]FIG. 38 is a diagram showing the configuration of a system according to a ninth embodiment of the present invention; and [0113] [0113]FIG. 39 is a diagram showing the configuration of an encryption/decryption router according to a tenth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0114] (First Embodiment) [0115] [0115]FIG. 1 shows the configuration of a computer system including a computer A 10002 and a computer B 10003 connected to each other through a network 10001 for cryptocommunications from the computer A 10002 to the computer 10003 . The computer A 10002 has an operation unit (hereinafter referred to as “CPU”) 10004 , a memory unit (volatile or nonvolatile, hereinafter referred to as “RAM”) 10005 , and a network interface 10006 therein, and a display 10007 and a keyboard 10008 externally connected thereto for the user to operate the computer A 10002 . The RAM 10005 stores an encryption program PROG 1 _ 10009 , a random number generation program PROG 2 _ 10010 , a secret key K 10011 , which is secret information shared only between the computers A 10002 and B 10003 , a redundancy R 10012 and an initial value V 10013 , which both are data shared between the computers A 10002 and B 10003 , and encryption-target data 10014 to be transmitted to the computer B 1003 . The computer B 10003 has a CPU 10015 , a RAM 10016 , and a network interface 10017 therein, and a display 10018 and a keyboard 10019 externally connected thereto for the user to operate the computer B 10003 . The RAM 10016 stores a decryption program PROG 3 _ 10020 , a random number generation program PROG 2 _ 10021 , the secret key K 10011 , the redundancy R 10012 , and the initial value V 10013 . [0116] The computer A 10002 executes the encryption program PROG 1 _ 10009 to generate ciphertext C 10022 from a message M 10014 , and transmits the generated ciphertext C 10022 to the network 10001 through the network interface 10006 . Receiving the ciphertext C 10022 through the network interface 10017 , the computer B 10003 executes the decryption program PROG 3 _ 10020 , and if no alteration is detected, the computer B 10003 stores the decryption results in the RAM 10016 . [0117] Each program employed can be introduced into each RAM by receiving the program from another computer in the form of a transmission signal, which is a transmission medium on the network 10001 , or by using a portable medium such as a CD or an FD. Each program can be configured so that it runs under control of the operating system (not shown) of each computer. [0118] The encryption program PROG 1 _ 10009 is read out from the RAM 10005 , and executed by the CPU 10004 in the computer A 10002 . The encryption program PROG 1 _ 10009 internally calls a random number generation program PROG 2 _ 10010 as a subroutine to process the input secret key K 10011 , the redundancy R 10012 , the initial value V 10013 , and the message M 10014 so as to output ciphertext C 10022 . [0119] The decryption program PROG 3 _ 10020 is read out from the RAM 10016 , and executed by the CPU 10015 in the computer B 10003 . The decryption program PROG 3 _ 10020 internally calls a random number generation program PROG 2 _ 10021 as a subroutine to process the input key 10011 , the redundancy R 10012 , the initial value V 10013 , and the ciphertext C 10022 so as to output a message or an alteration detection alarm. [0120] Description will be made of the process flow of the encryption program PROG 1 _ 10009 . [0121] Step 20002 (a data setting subroutine): waits for input of an initial value V, a redundancy R, and a secret key K. [0122] Step 20003 (a plaintext preparation subroutine): waits for input of plaintext, adds predetermined padding and a redundancy to the given plaintext, and divides the padded plaintext into a series of plaintext blocks P i (1≦i≦n) each having 64 bits and outputs them. [0123] Step 20004 (a random number generation subroutine): outputs pseudorandom number sequences A i and B i (1≦i≦n) based on the secret key K. [0124] Step 20005 (an encryption subroutine): uses the pseudorandom number sequences A i and B i , the series of plaintext blocks P i (1≦i≦n), and the initial value V to output a series of ciphertext blocks C i (1≦i≦n). [0125] Step 20006 : concatenates the series of ciphertext blocks C i (1≦i≦n) obtained at step 20005 one after another sequentially to output ciphertext C. [0126] In this specification, the term “padding” used above refers to addition of additional data to main data. In the case of padding of digital data, the additional data is often concatenated to the main data, simply bits to bits. [0127] Description will be made of the process flow of the plaintext preparation subroutine with reference to FIG. 2. [0128] Step 20202 : waits for input of an encryption-target message M. The message M is either input from the keyboard 10008 or read out from a RAM, or introduced from another medium. [0129] Step 20203 : adds padding indicating the length of the message. Specifically, this step adds 64-bit binary data indicating the length of the message M to the head of the message M. [0130] Step 20204 : adds padding to the message so that the length of the message is a multiple of a predetermined number. Specifically, the padded data is set to have an integer multiple of 64 bits for subsequent processing. When the length of the message M to which the data indicating the length is added at step 20203 is L bits, this step adds (64−L(mod 64)) number of Os to the end of the message M. [0131] Step 20205 (addition of redundancy data): further adds a redundancy R of 64 bits to the end of the message. [0132] Step 20206 (division of message data into plaintext blocks): divides the data obtained at step 20205 into blocks P 1 , P 2 , . . . P n , each having 64 bits. [0133] Description will be made of the process flow of the random number generation subroutine with reference to FIG. 3. [0134] Step 20302 (input of necessary parameters): obtains the number n of blocks making up the padded message, and the secret key K. [0135] Step 20303 (generation of a pseudorandom number sequence A): calls the random number generation program PROG 2 to generate a pseudorandom number sequence having 64*n bits and output it as a pseudorandom number sequence A. [0136] Step 20304 (division of random number sequence A into blocks): divides the pseudorandom number sequence A into blocks A 1 , A 2 , . . . , A n , each having 64 bits. [0137] Step 20305 (initialization of a counter i): initializes a counter so that i=1. [0138] Step 20306 (generation of a random number B i ): executes PROG 2 using the secret key K to generate a random number B i having 64 bits. [0139] Step 20307 : if the random number B i generated at step 20306 is 0, returns to step 20306 . [0140] Step 20308 : if i=n, performs step 20310 . [0141] Step 20309 : increments the counter i and returns to step 20306 . [0142] Description will be made of the process flow of the encryption subroutine with reference to FIG. 4. [0143] Step 20402 : sets an initial value F 0 so that F 0 =V. [0144] Step 20403 : sets a counter so that i=1. [0145] Step 20404 : calculates a feedback value F i by the formula F i =P i ^ A i . [0146] Step 20405 : calculates a ciphertext block C i by the formula C i =(F i *B i )^ F i−1 . [0147] Step 20406 : if i=n, performs step 20408 . [0148] Step 20407 : increments the counter i and returns to step 20404 . [0149] Description will be made of the process flow of the decryption program PROG 3 _ 10020 with reference to FIG. 5. [0150] Step 20502 (a data setting subroutine): waits for input of the initial value V, the redundancy R, and the secret key K. [0151] Step 20503 (a ciphertext preparation subroutine): waits for input of ciphertext C′, and divides the given ciphertext C′ into a series of ciphertext blocks C′ i (1≦i≦n) each having 64 bits and outputs them. [0152] Step 20504 (a random number generation subroutine): outputs pseudorandom number sequences A i and B i (1≦i≦n) based on the secret key K. [0153] Step 20505 (a decryption subroutine): uses the pseudorandom number sequences A i and B i , the series of ciphertext blocks C′ i (1≦i≦n), and the initial value V to output a series of plaintext blocks P′ i (1≦i≦n). [0154] Step 20506 (a plaintext extraction subroutine): combines the series of plaintext blocks P′ i into three data strings L′, M′, and Z′. [0155] Step 20507 (a redundancy extraction subroutine): divides Z′ into R′ and T′. [0156] Step 20508 : if T=0 and R′=R, proceeds to step 20510 . [0157] Step 20509 : outputs a rejection indication and proceeds to step 25011 . [0158] Step 20510 : stores M′ into a RAM. [0159] At step 20509 or 20510 , the decryption program outputs a result (acceptance/rejection or the encryption result) to the display 10018 as a notification to the user. [0160] Description will be made of the process flow of the ciphertext preparation subroutine with reference to FIG. 6. [0161] Step 20602 : waits for input of ciphertext C′. [0162] Step 20603 : divides the ciphertext C′ into blocks C′ 1 , C′ 2 , . . . C′ n , each having 64 bits. [0163] Description will be made of the process flow of the decryption subroutine with reference to FIG. 7. [0164] Step 20702 : sets an initial value F′ 0 so that F′ 0 =V. [0165] Step 20703 : initializes a counter so that i=1. [0166] Step 20704 : calculates a feedback value F′ i by the formula F′ i =(C′ i ^ F′ i−1 )/B i . [0167] Step 20705 : calculates a plaintext block P′ i by the formula P′ i =F′ i ^ A i . [0168] Step 20706 : if i=n, performs step 20708 . [0169] Step 20707 : increments the counter i and returns to step 20704 . [0170] Description will be made of the process flow of the plaintext extraction subroutine with reference to FIG. 8. [0171] Step 20802 : sets L′ to the first 64-bit plaintext block. [0172] Step 20803 : sets M′ to the L′ number of bits starting from the most significant bit of P′ 2 included in the series of decrypted plaintext blocks. [0173] Step 20804 : after L′ and M′ are removed from the series of decrypted plaintext blocks, sets Z′ to the remaining decrypted plaintext blocks (data). [0174] Description will be made of the process flow of the redundancy extraction subroutine with reference to FIG. 9. [0175] Step 20902 : sets R′ to the lower 64 bits of Z′. [0176] Step 20903 : after R′ is removed from Z′, sets T′ to the remaining data. [0177] [0177]FIG. 10 is an explanatory diagram showing the encryption process. The encircled plus “(+)” denotes an exclusive OR logic operation between two pieces of data each having a width of 64 bits, while the encircled X mark “(×)” denotes a multiplication operation between two pieces of data each having a width of 64 bits in the finite field F2 64 . [0178] The message M 20931 is added with data 20930 indicating the length, appropriate padding 20932 , and a redundancy R 20933 to produce plaintext P 20934 . [0179] The produced plaintext P 20934 is divided into blocks P 1 — 20935 , P 2 — 20936 , P 3 — 20937 , . . . P n — 20938 , each having 64 bits. [0180] P 1 — 20935 and A 1 — 20940 are exclusive-ORed to produce a feedback value F 1 — 20941 which is then multiplied by B 1 — 20942 in a finite field. The result is exclusive-ORed with an initial value F 0 — 20939 to obtain a ciphertext block C 1 — 20943 . [0181] Similarly, P 2 — 20936 and A 2 — 20946 are exclusive-ORed to produce a feedback value F 2 — 20945 which is then multiplied by B 2 — 20946 in a finite field. The result is exclusive-ORed with the feedback value F 1 — 20941 to obtain a ciphertext block C 2 — 20947 . [0182] The above procedure is repeated up to P n — 20938 , obtaining ciphertext blocks C 1 — 20943 , C 2 — 20947 , C 3 — 20951 , . . . , C n — 20955 . The ciphertext blocks are concatenated one after another in that order to obtain ciphertext C_ 20956 . [0183] [0183]FIG. 11 is an explanatory diagram showing the decryption process. The encircled slash “(/)” denotes a division operation between two pieces of data each having a width of 64 bits in the finite field F2 64 . In the figure, data introduced to the encircled slash symbol from top is the dividend, while data introduced from left is the divisor. [0184] Ciphertext C′_ 20960 is divided into blocks C′ 1 — 20962 , C′ 2 — 20963 , C′ 3 — 20964 , . . . , C′ n — 20965 , each having 64 bits. [0185] C′ 1 and an initial value F′ 0 — 20961 are exclusive-ORed, and the result is divided by B 1 — 20966 . The division result is set as a feedback value F′ 1 — 20967 . The feedback value F′ 1 — 20967 and A 1 — 20968 are exclusive-ORed to obtain a plaintext block P′ 1 — 20969 . [0186] The other blocks C′ 2 — 20963 , C′ 3 — 20964 , . . . , C′ n — 20965 are also processed in the same way as C′ 1 — 20962 to obtain plaintext blocks P′ 1 — 20969 , P′ 2 — 20972 , P′ 3 — 20977 , . . . , P′ n — 20981 , which are then concatenated one after another to produce plaintext P′_ 20982 . The plaintext P′_ 20982 is divided into L′_ 20983 , M′_ 20984 , and Z′_ 20985 . Furthermore, Z∝_ 20985 is divided into T′_ 20988 and R′_ 20989 so as to check the redundancy R′_ 20989 . [0187] The first embodiment uses a pseudorandom number sequence whose length is about twice as long as that of the message for cryptographic processes. Even though pseudorandom-number processing is faster than block-cipher processing, it is highest in computational complexity in these cryptographic processes. Therefore, it is desirable to reduce the number of random numbers to use. [0188] (Second Embodiment) [0189] As describe below, a second embodiment of the present invention employs a function different from that used by the first embodiment. By employing this function, the second embodiment can reduce the number of random numbers necessary to use, and use the same divisor for each iteration in its decryption process, which makes it possible to perform the division operation at substantially the same speed as that of a multiplication operation if the reciprocal is calculated beforehand, resulting in very efficient processing. [0190] The second embodiment employs an encryption program PROG 1 A and a decryption program PROG 3 A instead of the encryption program PROG 1 and the decryption PROG 3 , respectively. [0191] The encryption program PROG 1 A replaces the random number generation subroutine 20004 and the encryption subroutine 20005 employed in the encryption program PROG 1 _ 10009 in FIG. 1 by a random number generation 2 subroutine 21004 and an encryption 2 subroutine 21005 , respectively. [0192] Description will be made of the process flow of the random number generation 2 subroutine 21004 with reference to FIG. 12. [0193] Step 21102 (input of necessary parameters): obtains the number n of message blocks making up a padded message, and a secret key K. [0194] Step 21103 (generation of pseudorandom number sequence A): calls the random number generation program PROG 2 to generate a pseudorandom number sequence having 64*n bits and output it as a pseudorandom number sequence A. [0195] Step 21104 (division of pseudorandom number sequence A into blocks): divides the pseudorandom number sequence A into blocks A 1 , A 2 , . . . , A n , each having 64 bits. [0196] Step 21105 (generation of random number B): executes PROG 2 using the secret key K to generate a random number B having 64 bits. [0197] Step 21106 : if the value of B generated at step 21105 is 0, returns to step 21105 . [0198] Description will be made of the process flow of the encryption 2 subroutine 21005 with reference to FIG. 13. [0199] Step 21202 : sets an initial value F 0 so that F0=V. [0200] Step 21203 : sets a counter so that i=1. [0201] Step 21204 : calculates a feedback value F i by the formula F i =P i ^ A i . [0202] Step 21205 : calculates a ciphertext block C i by the formula C i =(F i *B)^ F i−1 . [0203] Step 21206 : if i=n, performs step 21208 . [0204] Step 21207 : increments the counter i and returns to step 21204 . [0205] Description will be made of the process flow of the decryption program PROG 3 A corresponding to PROG 1 A with reference to FIG. 14. [0206] The decryption program PROG 3 A replaces the random number generation subroutine 20504 and the decryption subroutine 20505 employed in the decryption program PROG 3 _ 10020 by a random number generation 2 subroutine 21304 and a decryption 2 subroutine 21305 , respectively. [0207] Step 21302 (a data setting subroutine): waits for input of the initial value V, the redundancy R, and the secret key K. [0208] Step 21303 (a ciphertext preparation subroutine): waits for input of ciphertext C′, and divides the given ciphertext C′ into a series of ciphertext blocks C′ i (1≦i≦n) each having 64 bits and outputs them. [0209] Step 21304 (a random number generation subroutine): outputs pseudorandom number sequences A i (1≦i≦n) and B in response to the secret key K. [0210] Step 21305 (a decryption subroutine): uses the pseudorandom number sequences A i and B, the series of ciphertext blocks C′ i (1≦i≦n), and the initial value V to output a series of plaintext blocks P′i (1≦i≦n). [0211] Step 21306 (a plaintext extraction subroutine): combines the series of plaintext blocks P′ i into three data strings L′, M′, and Z′. [0212] Step 21307 (a redundancy extraction subroutine): divides Z′ into R′ and T′. [0213] Step 21308 : if T=0 and R′=R, proceeds to step 21310 . [0214] Step 21309 : outputs a rejection indication and proceeds to step 21311 . [0215] Step 21310 : stores M′ into a RAM. [0216] Description will be made of the process flow of the decryption 2 subroutine 21305 in FIG. 14 with reference to FIG. 15. [0217] Step 21402 : sets an initial value F′ 0 so that F′ 0 =V. [0218] Step 21403 : calculates 1/B beforehand. [0219] Step 21404 : initializes a counter so that i=1. [0220] Step 21405 : calculates a feedback value F′ i by the formula F′ 1 =(C′ i ^ F′ i−1 )*(1/B). [0221] Step 21406 : calculates a plaintext block P′ i by the formula P′ i =F′ i ^ A i . [0222] Step 21407 : if i=n, performs step 21409 . [0223] Step 21408 : increments the counter i and returns to step 21405 . [0224] [0224]FIG. 16 is an explanatory diagram showing the encryption process employed by the above method of increasing the processing speed. [0225] The message M 21421 is added with data 21420 indicating the length, appropriate padding 21422 , and a redundancy R 21423 to produce plaintext P 21424 . [0226] The produced plaintext is divided into blocks P 1 — 21425 , P 2 — 21426 , P 3 — 21427 , . . . , P n — 21428 , each having 64 bits. [0227] P — 21425 and A 1 — 21431 are exclusive-ORed to produce a feedback value F 1 — 21432 which is then multiplied by B_ 21429 in a finite field. The result is exclusive-ORed with an initial value F 0 — 21430 to obtain a ciphertext block C 1 — 21433 . [0228] Similarly, P 2 — 21426 and A 2 — 21434 are exclusive-ORed to produce a feedback value F 2 — 21435 which is then multiplied by B_ 21429 in a finite field. The result is exclusive-ORed with the feedback value F 1 — 21432 to obtain a ciphertext block C 2 — 21436 . [0229] The above procedure is repeated up to P n — 21428 , obtaining ciphertext blocks C 1 — 21433 , C 2 — 21436 , C 3 — 21439 , . . . , C n — 21442 . The ciphertext blocks are concatenated one after another in that order to obtain ciphertext C_ 21443 . [0230] [0230]FIG. 17 is an explanatory diagram showing the corresponding decryption process. [0231] Ciphertext C′_ 21450 is divided into blocks C′ 1 — 21453 , C′ 2 — 21454 , C′ 3 — 21455 , . . . , C′ n — 21456 , each having 64 bits. [0232] C′ 1 and an initial value F′ 0 — 21451 are exclusive-ORed, and the result is multiplied by 1/B_ 21452 . The multiplication result is set as a feedback value F′ 1 — 21457 . The feedback value F′ 1 — 21457 and A 1 — 21458 are exclusive-ORed to obtain a plaintext block P′ 1 — 21459 . [0233] The other blocks C′ 2 — 21454 , C′ 3 — 21455 , . . . , C′ n — 21456 are also processed in the same way as C′ 1 — 21453 to obtain plaintext blocks P′ 1 — 21459 , P′ 2 — 21462 , P′ 3 — 21465 , . . . P′ n — 21468 , which are then concatenated one after another to produce plaintext P′_ 21476 . The plaintext P′_ 21476 is divided into L′_ 21469 , M′_ 21470 , and Z′_ 21471 . Furthermore, Z′_ 21471 is divided into T′_ 21474 and R′_ 21475 so as to check the redundancy R′_ 21475 . [0234] The second embodiment uses a 64-bit redundancy, and therefore employs addition and multiplication in the finite field F2 64 . [0235] With enhanced efficiency provided by this embodiment, it is possible to realize high-speed cryptographic processing. An implementation example written in the C programming language achieved a processing speed of 202 Mbit/sec in encryption processing using a 64-bit processor with a clock frequency of 600 MHz. On the other hand, a processing speed of 207 Mbit/sec was observed in decryption processing. [0236] The above implementation uses such operations as pseudorandom number generation, exclusive OR, and multiplication in the finite field F2 64 which are efficiently implemented especially by hardware. For example, it is estimated that with a gate array fabricated in a 0.35-μm process, the above operations can be implemented by adding an additional circuit having 3 k gates for the pseudorandom number generator. Furthermore, the pseudorandom number generator can be implemented using parallel processing, making it easy to realize a parallel processing device (including the pseudorandom number generator) having a processing speed as high as required. Thus, it is possible to realize a processing speed of 9.6 Gbit/sec at maximum by adding a circuit having about 36 k gates to a parallel pseudorandom number generator. [0237] (Third Embodiment) [0238] As described below, a third embodiment of the present invention uses another high-speed processing function to provide processing at higher speed with the same security level as those of the first and the second embodiments. In another aspect, the third embodiment can provide higher security equivalent to F2 128 if operations in the finite field F2 64 employed in the first and second embodiments are also used. [0239] In the aspect of providing processing at higher speed described above, the third embodiment uses an operation in the finite field F2 32 twice. Since multiplication in the field F2 64 generally requires a computational amount (computational complexity) four times as much as that for the finite field F2 32 , the third embodiment requires only half ((¼)*2) of the computational amount (computational complexity) required by an operation in the finite field F2 64 , actually doubling the processing speed. [0240] In the aspect of enhancing security, the third embodiment can use both an operation in the finite field F2 64 and a 64-bit feedback value twice to reduce the alteration success rate from 2 −64 of the above method to 2 −128 . [0241] The third embodiment employs an encryption program PROG 1 B and a decryption program PROG 3 B instead of the encryption program PROG 1 and the decryption program PROG 3 . [0242] The encryption program PROG 1 B replaces the random number generation subroutine (step 20004 ) and the encryption subroutine (step 20005 ) employed in the encryption program PROG 1 _ 10009 in FIG. 1 by a random number generation 3 subroutine 21504 and an encryption 3 subroutine 21505 . Description will be made of the process flow of the encryption program PROG 1 B with reference to FIG. 18. [0243] Step 21502 (a data setting subroutine): waits for input of an initial value V, a redundancy R, and a secret key K. [0244] Step 21503 (a plaintext preparation subroutine): waits for input of plaintext, adds predetermined padding and a redundancy to the given plaintext, and divides the padded plaintext into a series of plaintext blocks P i (1≦i≦n) each having 32 bits and outputs them. [0245] Step 21504 (random number generation 3 subroutine): outputs pseudorandom number sequences A i (1≦i≦n), Ba, and Bb based on the secret key K. [0246] Step 21505 (encryption 3 subroutine): uses the pseudorandom number sequences A i , Ba, and Bb, the series of plaintext blocks P i (1≦i≦n), and the initial value V to output a series of ciphertext blocks C i (1≦i≦n). [0247] Step 21506 : concatenates the series of ciphertext blocks C i (1≦i≦n) obtained at step 21505 one after another sequentially to output ciphertext C. [0248] Description will be made of the process flow of the random number generation 3 subroutine 21504 with reference to FIG. 19. [0249] Step 21602 (input of necessary parameters): obtains the number n of message blocks making up the padded message and the secret key K. [0250] Step 21603 (generation of pseudorandom number sequence A): calls the random number generation program PROG 2 to generate a pseudorandom number sequence having 32*n bits and output it as a pseudorandom number sequence A. [0251] Step 21604 (division of random number sequence A into blocks): divides the pseudorandom number sequence A into blocks A 1 , A 2 , . . . , A n , each having 32 bits. [0252] Step 21605 (generation of random number Ba): executes PROG 2 using the secret key K to generate a random number Ba having 32 bits. [0253] Step 21606 : if the value of the random number Ba generated at step 21605 is 0, returns to step 21605 . [0254] Step 21607 (generation of random number Bb): executes PROG 2 using the secret key K to generate a random number Bb having 32 bits. [0255] Step 21608 : if the value of the random number Bb generated at step 21607 is 0, returns to step 21607 . [0256] Description will be made of the process flow of the encryption 3 subroutine 21505 with reference to FIG. 20. The symbols “*” and “^ ” denote multiplication and addition, respectively, in the finite field F2 32 . [0257] Step 21702 : sets initial values FA 0 and FB 0 so that FA 0 =FB 0 =V. [0258] Step 21703 : initializes a counter so that i=1. [0259] Step 21704 : calculates a feedback value FA i by the formula FA i =P i ^ A i . [0260] Step 21705 : calculates a feedback value FB i by the formula FB i =(FA i *Ba)^ FA i−1 . [0261] Step 21706 : calculates a ciphertext block C i by the formula C i =(FB i *Bb)^ FB i−1 . [0262] Step 21707 : if i=n, performs step 21709 . [0263] Step 21708 : increments the counter i and returns to step 21704 . [0264] Description will be made of the process flow of the decryption program PROG 3 B with reference to FIG. 21. The decryption program PROG 3 B replaces the random number generation subroutine 20504 and the decryption subroutine 20505 employed in the decryption program PROG 3 _ 10020 by a random number generation 3 subroutine 21804 and a decryption 3 subroutine 21805 , respectively. [0265] Step 21802 (a data setting subroutine): waits for input of the initial value V, the redundancy R, and the secret key K. [0266] Step 21803 (a ciphertext preparation subroutine): waits for input of ciphertext C′, and divides the given ciphertext C′ into a series of ciphertext blocks C′ i (1≦i≦n) each having 32 bits and outputs them. [0267] Step 21804 (a random number generation subroutine): outputs pseudorandom number sequences A i (1≦i≦n), Ba, and Bb based on the secret key K. [0268] Step 21805 (a decryption subroutine): uses the pseudorandom number sequences A i , Ba, Bb, the series of ciphertext blocks C′ i (1≦i≦n), and the initial value V to output a series of plaintext blocks P′ i (1≦i≦n). [0269] Step 21806 (a plaintext extraction subroutine): combines the series of plaintext blocks P′ i into three data strings L′, M′, Z′. [0270] Step 21807 (a redundancy extraction subroutine): divides Z′ into R′ and T′. [0271] Step 21808 : if T=0 and R=R′, proceeds to step 21810 . [0272] Step 21809 : outputs a rejection indication and proceeds to step 21811 . [0273] Step 21810 : stores M′ into a RAM. [0274] Description will be made of the process flow of the decryption 3 subroutine 21805 in FIG. 21 with reference to FIG. 22. The symbol “/” denotes division in the finite field F2 32 . [0275] Step 21902 : sets initial values FA′ 0 and FB′ 0 so that FA′ 0 =FB′ 0 =V. [0276] Step 21903 : calculates 1/Ba and 1/Bb beforehand. [0277] Step 21904 : initializes a counter so that i=1. [0278] Step 21905 : calculates a feedback value FB′ i by the formula FB′ i =(C′ i ^ FB i−1 )*(1/Bb). [0279] Step 21906 : calculates a feedback value FA′ i by the formula FA′ i =(FB′ i ^ FA′ i−1 )*(1/Ba). [0280] Step 21907 : calculates a plaintext block P′ i by the formula P′ i =FA′ i ^ A i . [0281] Step 21908 : if i=n, performs step 21910 . [0282] Step 21909 : increments the counter i and returns to step 21905 . [0283] [0283]FIG. 23 is an explanatory diagram showing the encryption process employed by the above method of increasing the processing speed. [0284] The message M 21921 is added with data L 21920 indicating the length, appropriate padding 21922 , and a redundancy R 21923 to produce plaintext P 21924 . [0285] The produced plaintext P 21924 is divided into blocks P 1 — 21925 , P 2 — 21926 , P 3 — 21927 , . . . , P n_21928, each having 32 bits. [0286] P 1 — 21925 and A 1 — 21933 are exclusive-ORed to produce a feedback value FA 1 — 21934 which is then multiplied by Ba_ 21929 in a finite field. The result is exclusive-ORed with an initial value FA 0 — 21930 to obtain a feedback value FB 1 — 21935 . The obtained feedback value FB 1 — 21935 is multiplied by Bb_ 21931 in a finite field, and the multiplication result is exclusive-ORed with an initial value FB 0 — 21932 to obtain a ciphertext block C 1 — 21936 . [0287] Similarly, P 2 — 21926 and A 2 — 21937 are exclusive-ORed to produce a feedback value FA 2 — 21938 which is then multiplied by Ba_ 21929 in a finite field. The result is exclusive-ORed with the feedback value FA 1 — 21934 to obtain an feedback value FB 2 — 21939 . The obtained FB 2 — 21939 is multiplied by Bb_ 21931 in a finite field, and the multiplication result is exclusive-ORed with the feedback value FB 1 — 21935 to obtain a ciphertext block C 2 — 21940 . [0288] The above procedure is repeated up to P n — 21928 , obtaining ciphertext blocks C 1 — 21936 , C 2 — 21940 , C 3 — 21944 , . . . , C n_21950. The ciphertext blocks are concatenated one after another in that order to obtain ciphertext C_21951. [0289] [0289]FIG. 24 is an explanatory diagram showing the corresponding decryption process. [0290] Ciphertext C′_ 21960 is divided into blocks C′ 1 — 21961 , C′ 2 — 21962 , C′ 3 — 21963 , . . . , C′ n_21964, each having 32 bits. [0291] C′ 1 and an initial value FB′ — 21965 are exclusive-ORed, and the result is multiplied by 1/Bb_ 21966 . The multiplication result is set as a feedback value FB′ 1 — 21969 . The feedback value FB′ 1 — 21969 is exclusive-ORed with an initial value FA′ 0 — 21967 , and the result is multiplied by 1/Ba_ 21968 to generate a feedback value FA′ 1 — 21970 . The feedback value FA′ 1 — 21970 is exclusive-ORed with A 1 — 21971 to obtain a plaintext block P′ 1 — 21972 . [0292] The other blocks C′ 2 — 21962 , C′ 3 — 21963 , . . . , C′ n — 21964 are also processed in the same way as C′ 1 — 21961 to obtain plaintext blocks P′ 1 — 21972 , P′ 2 — 21976 , P′ 3 — 21980 , P n_21985, which are then concatenated one after another to produce plaintext P′_21986. The plaintext P′_21986 is divided into L′_21897, M′_21988, and Z∝_21989. Furthermore, Z′_21989 is divided into T′_21992 and P′_21993 so as to check the redundancy R′_21993. [0293] (Fourth Embodiment) [0294] As described below, a fourth embodiment of the present invention provides a cryptographic method capable of properly starting encryption/decryption processing without using information on the length of a message to be processed. Accordingly, the fourth embodiment makes it possible to perform cryptographic processing of data (message) of a stream type, whose entire length is not known beforehand. [0295] The fourth embodiment replaces the random number generation 2 subroutine and the plaintext preparation subroutine in the encryption program PROG 1 A, and the decryption program PROG 3 A employed in the second embodiment by a random number generation 4 subroutine, a plaintext preparation 2 subroutine, and a decryption program PROG 6 , respectively. [0296] Description will be made of the process flow of the random number generation 4 subroutine with reference to FIG. 29. [0297] Step 40212 (input of necessary parameters): obtains the number n of message blocks making up a padded message, and a secret key K. [0298] Step 40213 (generation of pseudorandom number sequence A): calls the random number generation program PROG 2 to generate a pseudorandom number sequence having 64*n bits and output it as a pseudorandom number sequence A. [0299] Step 40214 (division of pseudorandom number sequence A into blocks): divides the pseudorandom number sequence A into blocks A 1 , A 2 , . . . A n , each having 64 bits. [0300] Step 40215 (generation of random number B): executes PROG 2 using the secret key K to generate a random number B having 64 bits. [0301] Step 40216 : if the value of B generated at step 40215 is 0, returns to step 40215 . [0302] Step 40217 (generation of random number Q): executes PROG 2 using the secret key K to generate a random number Q having 64 bits. [0303] Next, description will be made of the process flow of the plaintext preparation 2 subroutine with reference to FIGS. 30 and 31. [0304] Step 40202 : waits for input of an encryption-target message M 40300 . The message is either input from the keyboard 10008 or read out from a RAM, or introduced from another medium. [0305] Step 40203 : adds padding to the message so that the length of the message is a multiple of a predetermined number. Specifically, the padded data (message) is set to have an integer multiple of 64 bits for subsequent processing. When the length of the message M 40300 is L bits, this step adds (64−L(mod 64)) number of Os to the end of the message M 40300 . [0306] Step 40204 (addition of secret data): further adds 64-bit secret data Q 40302 to the end of the message M 40300 . The secret data Q 40302 can be known by only a person who holds or has obtained its key (or the key data). The secret data may be a random number generated from the secret key K. The above step 40217 performs this process of generating secret data. [0307] Step 40205 (addition of redundancy data): still further adds a redundancy R 40303 of 64 bits to the end of the message M 40300 . [0308] Step 40206 (division of message data into plaintext blocks): divides the data P 40304 (the padded message) obtained at step 40205 into blocks P 1 , P 2 , . . . , P n , each having 64 bits. [0309] Description will be made of the process flow of the decryption program PROG 6 with reference to FIGS. 32 and 34. [0310] Step 40402 (a data setting subroutine): waits for input of the initial value V, the redundancy R, and the secret key K. [0311] Step 40403 (a ciphertext preparation subroutine): waits for input of ciphertext C′, and divides the given ciphertext C′ into a series of ciphertext blocks C′ i (1≦i≦n) each having 32 bits and output them. [0312] Step 40404 (random number generation 4 subroutine): outputs pseudorandom number sequences A i (1≦i≦n) and B based on the secret key K. [0313] Step 40405 (decryption 3 subroutine): uses the pseudorandom number sequences A i , B, and Q, the series of the ciphertext blocks C′ i (1≦i≦n), and the initial value V to output a series of plaintext blocks P′ i (1≦i≦n). [0314] Step 40406 (plaintext extraction 2 subroutine): combines the series of plaintext blocks P′ i 40601 into three data strings M′ 40602 , Q′ 40603 , and R′ 40604 . [0315] Step 40407 : if Q′ 40603 =Q 40302 and R′ 40604 =R 40303 , proceeds to step 40409 . [0316] Step 40408 : outputs a rejection indication and proceeds to step 40410 . [0317] Step 40409 : stores M′ into a RAM. [0318] Step 40410 : ends the process. [0319] Next, description will be made of the process flow of the plaintext extraction 2 subroutine with reference to FIG. 33. [0320] Step 40502 : removes the last 128 bits of the decrypted plaintext, and sets a plaintext block M′ to the remaining decrypted text. [0321] Step 40503 : sets Q′ to the upper 64 bits of the removed last 128 bits obtained at step 40502 . [0322] Step 40504 : sets R′ to the lower 64 bits of the removed last 128 bits. [0323] (Fifth Embodiment) [0324] The above first through fourth embodiments of the present invention have a single-processor configuration, that is, they do not employ parallel processing. A fifth embodiment of the present invention, however, shows that the present invention can be easily applied to parallel processing. [0325] The system configuration (not shown) of the fifth embodiment is different from that shown in FIG. 1 in that the computer A 10002 employs both a CPU 1 _ 30004 and a CPU 2 _ 30005 instead of the CPU 10004 , and the RAM 10005 stores a parallel encryption program PROG 4 _ 30016 in addition to the components shown in FIG. 1. Furthermore, the computer B 10003 employs both a CPU 1 _ 30017 and a CPU 2 _ 30018 instead of the CPU 10015 , and the RAM 10016 stores a parallel decryption program PROG 5 _ 30025 in addition to the components shown in FIG. 1. [0326] The computer A 10002 executes the parallel encryption program PROG 4 _ 30016 to generate ciphertext C 10022 from a message M 10014 and transmit the generated ciphertext C 10022 . Receiving the ciphertext C 10022 , the computer B 10003 executes the parallel decryption program PROG 5 _ 30025 , and if no alteration is detected, the computer B 10003 stores the decryption results into the RAM 10016 . [0327] The CPUs 1 _ 30004 and 2 _ 30005 implement the parallel encryption program PROG 4 _ 30016 by executing the program read out from the RAM 10005 in the computer A 10002 . The parallel encryption program PROG 4 _ 30016 internally calls and executes the encryption program PROG 1 _ 10009 and the random number generation program PROG 2 _ 10010 as its subroutines. [0328] The CPUs 1 _ 30017 and 2 _ 30018 executes the parallel decryption program PROG 5 _ 30025 read out from the RAM 10016 in the computer B 10003 . The parallel decryption program PROG 5 _ 30025 calls and executes the decryption program PROG 3 _ 10020 and the random number generation program PROG 2 _ 10021 as its subroutines. [0329] The other configurations and operations of the system are the same as those shown in FIG. 1. [0330] Description will be made of the process flow of the parallel encryption program PROG 4 _ 30016 with reference to FIG. 25. The expression “A∥B” denotes concatenation of two bit-strings A and B. [0331] Step 40002 : divides a message M into two parts, M 1 and M 2 , in message processing performed by the CPU 1 . [0332] Step 40003 : uses an initial value V+1, a redundancy R+1, a secret key K, and the plaintext M 1 to output ciphertext C 1 in encryption processing by the encryption program PROG 1 _ 10009 executed by CPU 1 . [0333] Step 40004 : uses an initial value V+2, a redundancy R+2, the secret key K, and the plaintext M 2 to output ciphertext C 2 in encryption processing by the encryption program PROG 1 _ 10009 executed by CPU 2 . [0334] Step 40005 : uses an initial value V, a redundancy R, the secret key K, and plaintext (R 1 ∥R 2 ) to output ciphertext C 3 in encryption processing by the encryption program PROG 1 _ 10009 executed by CPU 1 . [0335] Step 40006 : generates ciphertext C (C=C 1 ∥C 2 ∥C 3 ). [0336] Step 40007 : stores the ciphertext C into a memory. [0337] Description will be made of the process flow of the parallel decryption program PROG 5 _ 30025 with reference to FIG. 26. [0338] Step 40102 : divides ciphertext C′ into three parts, C′ 1 , C′ 2 , and C′ 3 . C′ 3 has 192 bits, and C′ 1 and C′ 2 has the same length, where C′=C′ 1 ∥C′ 2 ∥C′ 3 . [0339] Step 40103 : uses the initial value V+1 and the secret key K to decrypt the ciphertext block C′ 1 into a message block M′ 1 and the redundancy R+1 in decryption processing by the decryption program PROG 3 _ 10020 executed by the CPU 1 , and stores the message block M′ 1 and the redundancy R+1. [0340] Step 40104 : uses the initial value V+2 and the secret key K to decrypt the ciphertext block C′ 2 into a message block M′ 2 and the redundancy R+2 in decryption processing by the decryption program PROG 3 _ 10020 executed by CPU 2 , and stores the message block M′ 2 and the redundancy R+2. [0341] Step 40105 : if at least one of the decryption results obtained at steps 40103 and 40104 is a reject, performs step 40111 . [0342] Step 40106 : uses the initial value V and the secret key K to decrypt the ciphertext block C′ 3 into a block and the redundancy R in decryption processing by the decryption program PROG 3 _ 10020 executed by the CPU 1 , and stores the decryption result (the decrypted block) and the redundancy R. [0343] Step 40107 : if the decryption results obtained at step 40106 is a reject, performs step 40111 . [0344] Step 40108 : if the decrypted block obtained at step 40106 is not equal to (R+1)∥(R+2), performs step 40111 . [0345] Step 40109 : lets M′=M′ 1 ∥M′ 2 (M′: decryption result). [0346] Step 40110 : stores M′ into a memory and performs step 40112 . [0347] Step 40111 : outputs a rejection indication. [0348] As described above, the fifth embodiment can provide parallel cryptographic processing using two separate processors. [0349] [0349]FIG. 27 is an explanatory diagram showing the encryption process employed by the above parallel cryptographic processing method. [0350] M 1 — 40141 and M 2 — 40142 obtained as a result of dividing a message M 40140 are added with redundancies R+1 and R+2, respectively, and denoted as blocks 40143 and 40144 . The blocks 40143 and 40144 are encrypted by use of encryption processes 40146 and 40147 to obtain ciphertext blocks C 1 — 40149 and C 2 — 40150 , respectively. Further, a combination of the redundancies R+1 and R+2, which is set as a message, and another redundancy R are encrypted to obtain a ciphertext block C 3 — 40151 . [0351] The ciphertext blocks C 1 — 40149 , C 2 — 40150 , and C 3 — 40151 are concatenated one after another to output ciphertext C 40152 . [0352] [0352]FIG. 28 is an explanatory diagram showing the corresponding parallel decryption process. [0353] Ciphertext C′ 40160 is divided into three blocks, C′ 1 — 40161 , C′ 2 — 40162 , and C′ 3 — 40163 . [0354] The obtained blocks C′ 1 — 40161 , C′ 2 — 40162 , and C′ 3 — 40163 are decrypted by decryption processes 40164 , 40165 , and 40166 to obtain plaintext blocks 40167 , 40168 , and 40169 , respectively. [0355] If the obtained plaintext blocks are accepted, and the redundancies included in the plaintext blocks 40167 and 40168 are identical to the message portions of the plaintext block 40169 , and furthermore the redundancy included in the plaintext block 40169 is equal to the one shared beforehand, the message portions M′ 1 — 40170 and M′ 2 — 40171 are extracted from the plaintext blocks 40167 and 40168 , respectively, and concatenated to obtain a message M′ 40172 . [0356] Any CPU capable of executing a program can be used for the above embodiments whether it is a general-purpose CPU or a dedicated one. Even though the above embodiments are each implemented by execution of programs by a CPU (or CPUs), dedicated hardware can be used for each process employed, providing high speed and low cost. [0357] Any of known pseudorandom number generators can be applied to the above embodiments. The known pseudorandom number generators include a pseudorandom generator using a linear feedback shift register (LFSR) with a nonlinear filter, a nonlinear feedback shift register, a combining generator, a shrinking generator, a clock-controlled pseudorandom number generator, a Geffe generator, an alternating step generator, RC4, SEAL, PANAMA, the OFB mode of the block cipher, the counter mode of the block cipher, and other pseudorandom number generators using hash functions. [0358] (Sixth Embodiment) [0359] The above first through fifth embodiments each provides a cryptographic processing method. A sixth embodiment of the present invention, on the other hand, shows that the present invention can be applied to various information systems. [0360] [0360]FIG. 35 is a diagram showing the configuration of a system in which computers A 50016 and B 50017 are connected through a network 50009 for cryptocommunications from the computer A 50016 to the computer B 50017 . The computer A 50016 has a CPU 50007 , a RAM 50001 , and a network interface device 50008 therein. The RAM 50001 stores key-exchange protocol software 50002 for executing a key-exchange protocol, a public key 50004 of the authentication center, a secret-key generation program 50003 , an encryption program 50006 , and communication data 50005 (corresponding to the message M in each embodiment described above) to be transmitted using cryptocommunications. The computer B 50017 has a CPU 50014 , a RAM 50010 , and a network interface device 50015 therein. The RAM 50010 stores key-exchange protocol software 50011 and a decryption program 50013 . [0361] The computer A executes the secret-key generation program 50003 to generate a secret key used for cryptocommunications with the computer B 50017 . The computers A 50016 and B 50017 executes the key-exchange protocol software 50002 and 50011 , respectively, to share the secret key generated by the computer A. [0362] After sharing the secret key, the computer A 50016 executes the encryption program 50006 of the present invention to encrypt the communication data 50005 at high speed. The computer A 50016 then transmits the encryption results to the computer B 50017 through the network 50009 using the network interface device 50008 . [0363] The computer B 50017 executes the decryption program 50013 of the present invention to decrypt received ciphertext at high speed to restore the communication data. [0364] This embodiment shows that the present invention can provide high-speed and safe cryptocommunications even when available hardware resources are limited. That is, the present invention is capable of realizing a highly safe cryptocommunication system which is faster than the conventional cryptographic method, and provides confidentiality as well as a mathematically proven alteration detection function. [0365] (Seventh Embodiment) [0366] The above sixth embodiment performs cryptographic processing by use of software. A seventh embodiment of the present invention, on the other hand, shows that the present invention can be realized by hardware implementation. [0367] [0367]FIG. 36 is a diagram showing the configuration of an encryption apparatus employed in a crytocommunication system using a network. The computer 50110 has a RAM 50101 , a CPU 50104 , and a network interface device 50105 therein, and is connected to a network 50106 . The RAM 50101 stores communication data 50103 (corresponding to the message M in each embodiment described above) to be encrypted and a communication program 50102 , and the CPU 50104 executes the communication program 50102 to output the communication data 50103 to the network interface device 50105 . The network interface device 50105 includes a secret-key generation circuit 50107 , an encryption circuit 50109 , and a key-exchange protocol circuit 50108 , and has a public key 50110 of the authentication center stored in its memory area. According to the execution of the communication program 50102 , the network interface device 50105 generates a secret key by use of the secret-key generation circuit 50107 , and exchanges the generated secret key with another device on the network using the key-exchange protocol circuit 50108 so as to share the generated secret key with the communication destination device. The encryption circuit 50109 in the network interface device 50105 encrypts the input communication data 50103 at high speed using the generated and then shared secret key to generate ciphertext, which is then output to the network 50106 . [0368] This embodiment shows that the present invention can provide safe and fast cryptocommunications using limited hardware resources. Particularly, if this embodiment is combined with the cryptographic processing method of the second embodiment, more efficient and safe cryptocommunications can be realized. This is because addition and multiplication in the finite field F2 64 employed in the second embodiment are suitable for hardware implementation. The decryption process can also be implemented by hardware in the same way. [0369] As shown by this embodiment, the present invention can provide a cryptographic method whose hardware implementation requires a small number of gates or performs very high-speed processing. [0370] (Eighth Embodiment) [0371] By using a computer capable of performing cryptographic processing employed in the sixth or seventh embodiment, it is possible to easily realize a contents delivery protected by encryption. An eighth embodiment of the present invention shows an example of a contents delivery. [0372] As shown in FIG. 37, a storage device (whose medium is not limited to a specific type, that is, it is possible to use a semiconductor storage device, a hard disk, a magnetic storage device such as one using tape, or an optical storage device such as a DVD or an MO) storing contents 50201 as digital information is connected to a computer 50202 capable of performing encryption processing according to the present invention. An information reproduction device 50205 (an MPEG reproduction device, a digital TV, a personal computer, etc.) which is to reproduce contents and may be located in a physically remote place is connected to an external coding device 50204 capable of performing decryption processing according to the present invention. The computer 50202 and the external coding device are connected to each other through a network 50203 . [0373] The contents 50201 is encrypted by the computer 50202 capable of encryption, and then transmitted to the network 50203 . The external coding device 50204 capable of decryption decrypts the encrypted contents, and outputs the decryption results to the information reproduction device 50205 . The information reproduction device 50205 stores and reproduces input information. [0374] The contents 50201 handled by the information reproduction device 50205 include not only electronic files but also multimedia data such as computer software, sound, and image. Contents which require real-time processing, such as sound and movie, can be encrypted or decrypted at high speed by applying the present invention, making it possible to secure smooth real-time transmission. Furthermore, the receiving device can detect data corruption due to alteration or noise during the transmission, ensuring communications free of transmission errors. [0375] (Ninth Embodiment) [0376] The eighth embodiment delivers contents by transmission through a network. When it is necessary to deliver a very large amount of information, however, it is more efficient to deliver ciphertext on a DVD, etc. beforehand, and then transmit the decryption key at the time of permitting the decryption of the ciphertext. Such a system is provided by a ninth embodiment. [0377] As shown in FIG. 38, contents are distributed to the consumer as ciphertext, using a medium such as a DVD-ROM 50307 , beforehand. The consumer enters information 50306 (money transfer information) on payment for contents using a contents-key exchange program 50305 running on the consumer's personal computer 50304 . The contents-key exchange program 50305 then obtains a key from a contents-key table in a key server 50302 through a network 50303 . A decryption program 50308 decrypts the ciphertext contents recorded on the DVD-ROM 50307 using the obtained key. The decryption results are output to the information reproduction device 50309 which then reproduces the contents. [0378] This embodiment may be configured such that the contents are not output to the information reproduction device 50309 , and the personal computer 50304 itself reproduces them. In a typical example, the contents is a program to be executed on a personal computer. The above reproduction method of using a personal computer is efficient in such a case. When ciphertext contents recorded on a DVD-ROM can be divided into several parts, and each part is encrypted using a different key, it is possible to control keys transmitted to the contents-key acquisition program 50305 so as to limit contents which can be decrypted by the consumer. [0379] The ninth embodiment was described assuming that data recorded on the DVD-ROM 50307 is to be read out. Generally, a very large amount (a few tens of megabytes to a few hundreds of megabytes) of data is stored on the DVD-ROM 50307 , and therefore a fast cryptographic processing method is required for processing such data. Since the present invention can provide high-speed decryption, the present invention is suitably applied to distribution of charged contents using a DVD medium. [0380] (Tenth Embodiment) [0381] In a tenth embodiment of the present invention, the present invention is applied to a router which controls packet transfer on a network. This router encrypts packets differently depending on the destination router of each packet at the time of their transmission to the network. [0382] [0382]FIG. 39 is a diagram showing the configuration of a cryptographic router. The network router 50401 has a routing table 50402 , a packet exchanger 50403 , network interfaces A 50404 , B 50405 , and C 50406 , and an internal parallel encryption/decryption device 50410 therein. The network interfaces A 50404 , B 50405 , and C 50406 are connected to external networks A 50407 , B 50408 , and C 50409 , respectively. [0383] The internal parallel encryption/decryption device 50410 has a secret-key table 50411 , a router-key storage area 50412 , and a parallel encryption/decryption circuit 50413 therein. [0384] A packet sent from the network A 50407 is transmitted to the internal parallel encryption/decryption device 50410 through the network interface A 50404 . After recognizing that the received packet is originated from the network A 50407 , the internal parallel encryption/decryption device 50410 refers to the secret-key table 50411 to obtain the secret key corresponding to the network A 50407 , stores the obtained secret key in the router-key storage area 50412 , and decrypts the packet using the parallel encryption/decryption circuit 50413 . The internal parallel encryption/decryption device 50410 then transmits the s decryption results to the packet exchanger 50403 . [0385] The following description assumes that this decrypted packet should be transmitted to the network B. The packet exchanger 50403 transfers the packet to the internal parallel encryption/decryption device 50410 . The internal parallel encryption/decryption device 50410 refers to the secret-key table 50411 to obtain the secret key corresponding to the network B 50408 , stores the obtained secret key in the router-key storage area 50412 , and encrypts the packet using the parallel encryption/decryption circuit 50413 . The internal parallel encryption/decryption device 50410 then transmits the encryption results to the network interface B 50405 which, in turn, transmits the received encrypted packet to the network B 50408 . [0386] This embodiment is applied to an application used in an environment in which a large quantity of hardware resources are available and which requires cryptocommunications at very high speed. In the CBC mode of the block cipher in which parallel processing is difficult to employ, it is difficult to enhance its processing speed even when a large quantity of hardware resources are available. In contrast, parallel processing is very easy to employ in the present invention (providing a high level of parallel operation) since the pseudorandom number generation process is independent from the plaintext and ciphertext processing. That is, the present invention can attain a higher communication speed in the environment in which a large quantity of hardware resources suitable for parallel processing are available.

The present invention provides a symmetric-key cryptographic technique capable of realizing both high-speed cryptographic processing having a high degree of parallelism, and alteration detection. The present invention performs the steps of: dividing plaintext composed of redundancy data and a message to generate a plurality of plaintext blocks each having a predetermined length; generating a random number sequence based on a secret key; generating a random number block corresponding to one of said plurality of plaintext blocks from said random number sequence; outputting a feedback value obtained as a result of operation on said one of the plurality of plaintext blocks and said random number block, said feedback value being fed back to another one of the plurality of plaintext blocks; and performing an encryption operation using said one of the plurality of plaintext blocks, said random number block, and a feedback value obtained as a result of operation on still another one of the plurality of plaintext blocks to produce a ciphertext block.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a door closer including apparatus for indicating the position of the door. The invention is especially suitable for installation in connection with a penitentiary cell door or door to any other room where security is important. More specifically, the invention relates to a door closer in which the pinion shaft is formed with a cam surface and a lever is mounted thereadjacent and works against the cam surface, the lever actuating an indicator switch to indicate remotely whether the door is open or closed as reflected from the position of the cam on the pinion shaft. Still more specifically, the invention includes eccentric means for adjusting the position of the fulcrum of the lever so that the indicator gives the truest possible reading of the door position. 2. Description of the Related Art Including Information Disclosed Under §§1.97-1.99 In the prior art there are showings of door position indicators especially suitable for doors in penal institutions. An interesting example is shown in the U.S. Pat. No. 4,721,946, which issued Jan. 26, 1988 to Richard L. Zunkel. In this patent the pinion shaft of a door closer is provided with a rotary cam surface which directly actuates the lever arm of a micro-switch to indicate that the door is either closed, open or that the operator arm has been removed. Another example of such a device is shown in the U.S. Pat. No. 4,334,388, which issued June 15, 1982 to Raymond V. Kambic. In this patent a control arm is pivoted in the door frame and moves with the door. The arm is mounted on a shaft which carries, in a friction drive mounting, a lever arm which actuates a microswitch to indicate electrically to a remote panel the condition of the door. Other art of interest includes two U.S. Catlett patents U.S. Pat. Nos. 4,220,051 and 4,333,270, as well as the U.S. Pat. No. 4,124,847 to Cashman. SUMMARY OF THE INVENTION The present invention provides a door closer having a position indicator. The closer has a pinion shaft provided with a cam surface. A lever is mounted adjacent the shaft to work against the cam surface. Movements of the lever caused by the turning of the cam surface as the pinion shaft rotates are reflected in the actuation of a micro-switch, adjacent the lever. In a preferred embodiment the lever is provided with an eccentrically mounted fulcrum by which the lever may be adjusted to accurately indicate the position of the door. BRIEF DESCRIPTION OF THE DRAWINGS Further features and objects of the invention will be apparent from the following specification and the drawings, all of which disclose nonlimiting embodiments of the invention. In the drawings: FIG. 1 is a front elevational view of a door closer having an indicator switch arrangement mounted thereadjacent, the operator arm is broken off to save drawing space; FIG. 2 is a sectional view taken on the line 2--2 of FIG. 1; FIG. 3 is similar to FIG. 2 but shows an arrangement for operation with the opposite hand of the door mounting; FIG. 4 is an enlarged top view of the eccentric mounting of the fulcrum pivot for the actuating lever with the operating arm removed; FIG. 5 is a partly sectional fragmentary view showing in detail the side elevation of the pivot mounting; and FIG. 6 is an enlarged fragmentary sectional view taken on the line 6--6 of FIG. 4. DESCRIPTION OF THE PREFERRED EMBODIMENT An apparatus embodying the invention is shown in FIG. 1 and generally designated 10. It comprises a door closer 12 and a housing 14 including a spring-containing tube or cup 16. The tube has at its rightward end the usual adjustment gear 18 for the spring. The gear 18 may be rotated by rotation of the meshing gear 20 mounted for rotation in boss 22 and having a shaft operable through a conventional opening in the top of the door frame. As shown, the closer is mounted on a base plate 24 which is secured by means (not shown) to the door frame 26 (FIG. 6). The underside of the base plate 24 is covered by a dress plate 28. Extending downward centrally of the housing 14 is the pinion shaft 30 of the closer. A hub 32 is mounted on the lower end of the closer and fixedly mounts an operating arm 34 shown partly in section. As shown in FIGS. 1 and 6, the rightward end of the operating arm 34 has a downward shaft 36 terminating downward in a roller 38, which moves inside a formed track 50. The track is supported on the top element 46 of the door 48. As is conventional, when the door opens, the roller moves in the track in one direction "cocking" the arm 34 of the closer. When the door is released, the arm drives the door closed as the roller 38 moves in the opposite direction in the formed track. Thus the shaft 36 is coordinated with the movement of the door. The structure so far described is a conventional door closer arrangement whereby a piston (not shown) inside the housing 12 carries a rack (not shown) which is engaged by a pinion (not shown) on the upper end of the shaft 30. The piston is urged leftward by the spring in cup or tube 16 causing the operator arm 34 to draw the door closed. The piston compresses the spring in cup 16 when the door is opening. As is conventional, hydraulic fluid in the housing 14 is worked on by the piston, and the closing speed and latching speed of the door are damped by controls which meter the flow of the oil on the return stroke of the piston. Attention is now directed to the portion of the disclosed structure comprising the invention. Above the hub 32 the pinion shaft 30 is formed with a flat 60 (FIGS. 1, 2, and 3). As best shown in FIG. 2, a lever 62 is mounted on the base plate 24 and comprises a section 64 which works against the shaft 30. The mounting of the lever 62 is preferably by means of a fulcrum pin 66 at one end of the lever. As shown (FIGS. 4, 5), the pin 66 is eccentrically formed on a rotatable circular mount 68. The mount is formed with a central peripheral groove 70 receiving an O-ring 72. The lower end of the mount has an outward flange 74. In assembly the mount is rotatably held in a circular opening 76 in the base plate which is recessed at 77 in the area of the opening 76. On its underside the opening 76 has an outward annular recess 78 which forms a stop shoulder for the flange 74, limiting the upward movement of the mount. An Allen wrench socket 80 is formed centrally in the lower face of the mount 68. The O-ring 72 provides heavy friction in the rotation of the mount so that once the radial position of the mount is set, it remains in that position until moved by wrench as described. As shown (FIG. 2), the leftward end of the lever 62 is enlarged and has a central opening 82 which receives the pin 66. A C-ring 84 snaps into a groove at the upper end of the pin 66 to hold the assembly together. The opening 82 is sufficiently large to permit free pivoting of the lever 62 on the pin 66. Preferably, on the opposite side of the lever 62 from the pivot 66 the lever 62, which is crooked, as shown in FIG. 2, is apertured at 86 and receives one end of a spring 88. The other end of the spring is mounted by a fastener 90 to the base plate 24, biasing the lever 62 toward the pinion shaft 30. A microswitch 92 having a button actuator 94 is mounted also on the base plate 24 and is arranged so that the distal end of the lever 62 engages the button 94 to actuate the switch when the flat 60 is presented to the section 64 of the lever. Wires from the switch as shown lead to a junction box 96 as shown in FIG. 1 and from there to an indicator or signal means. Actuation of the switch 92 in this manner puts the switch 92 in a first condition, which is indicated on a remote indicator by means of obvious electrical circuitry, as disclosed in more detail in the aforementioned patent to Kambic. When the door is opened in the arrangement shown, the shaft 30 will turn clockwise and the flat 60 will progressively face toward the left. The "corner" formed at the intersection of the shaft circle and the flat 60 causes the lever 62 to move, disengaging the button 94 and putting the switch 92 in a second condition indicating on the remote indicator that the door is opening or opened. If the door is of opposite hand (i.e., with hinges on the right of the door instead of on the left), a rearrangement of the parts, as shown in FIG. 3, may be desired. In the FIG. 3 arrangement, a lever 62' is relatively straight and is pivoted on pin 66', fashioned identically to that as shown in FIGS. 4 and 5. The switch 92' and its button 94' are activated by the distal end of the lever 62, which is biased toward the shaft 30' by spring 88'. Because the door associated with the setup of FIG. 3 will open in a reverse direction from the door 48, shaft 30' will move counterclockwise so that the flat 60' will move toward the left and raise the distal end of the lever 62' away from the button 94', indicating on the remote indicator that the door is opening or opened. An important aspect of the invention is the provision of the mount 68 which moves the pin 66 or 66' in an arc as a wrench is inserted by a serviceman or installer in the socket 80 of the mount and turned. The mount can be adjusted so that an indication of the door as closed can be read at the indicator only when the door is precisely closed and the flat 60 or 60' rests evenly against the section 64 or 64' of the lever 62 or 62'. Alternatively, the fulcrum of the lever can be set so that the switch 92 does not change condition until the door is opened an inch or so. As should be understood by now, the indicator does not signal the open condition of the door until the flat 60 has turned by a preset amount depending on adjustment past the flat contact condition with the lever as shown in FIG. 2. At any rate, because of the structure disclosed, the door position indicator of the invention provides an extremely accurate reading of the door position. In addition, it should be noted that the operation of apparatus embodying the invention is directly tied to the position of the pinion shaft 30, and does not rely on variables such as friction discs or special auxilliary cams, as with the prior art. At the same time, it should be noted that the present apparatus involves only a minor change to a conventional door closer, namely, the cutting of the flat 60 or 60' on the pinion shaft to a degree farther along the shaft than is normally done to key the hub 30 to the arm. It is thus clear that the invention provides a door monitoring apparatus of extreme sensitivity and which is direct and reliable in operation. It is understood that variations of the invention are possible and thus the invention is not limited to the embodiments disclosed but is of a scope as defined by the following claim language or reasonable equivalents thereof.

A door closer has a cam surface on its pinion shaft. A lever mounted thereadjacent works against the shaft, and when the door is closed, engages a switch to indicate remotely the condition of the door. The lever fulcrum is mounted on an eccentric arrangement so that the change from "door closed" to "door opened" position can be set at a precise point.

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit under 35 U.S.C. §119(e) to U.S. Provisional Patent Application No. 61/449,598, filed Mar. 4, 2011 and titled “Linear Vibrator Providing Localized Haptic Feedback,” this disclosure of which is hereby incorporated herein in its entirety. TECHNICAL FIELD [0002] Embodiments described herein generally relate to vibration-producing devices, and more particularly to vibration-producing devices providing localized haptic feedback. BACKGROUND [0003] Many electronic devices use linear vibrators to provide generalized haptic feedback by shaking or vibrating the device enclosure. For example, many mobile telephones may be set to a vibrate mode, so that the phone body (e.g., enclosure) vibrates when a call is received in lieu of emitting an audible ring tone. However, linear vibrators typically vibrate the entire device and/or enclosure and thus provide generalized haptic feedback. [0004] In certain embodiments, it may be useful or desirable to localize haptic feedback. For example, certain electronic devices may use virtual or touch-based keyboards, buttons, and other input mechanisms. Without some form of localized feedback, it may be difficult for a user to detect if the input mechanism was properly or adequately touched. A generalized haptic feedback, such as vibrating the entire electronic device, may be insufficiently precise. SUMMARY [0005] One embodiment described herein may take the form of an apparatus for providing haptic feedback, including: a shell defining an aperture; a driver disposed within the shell; a mass disposed within the coil; and a projection connected to the mass and extending through the aperture. [0006] Another embodiment described herein may take the form of a method for providing generalized and localized haptic feedback, including the operations of: receiving an input signal; determining if the input signal corresponds to a generalized haptic feedback; if so, providing a first input to a linear vibrator; otherwise, providing a second input to a linear vibrator; wherein the linear vibrator outputs a generalized haptic feedback in response to the first input; and the linear vibrator outputs a localized haptic feedback in response to the second input. BRIEF DESCRIPTION OF THE FIGURES [0007] FIG. 1 is a cut-away perspective view of a simplified linear vibrator capable of providing haptic feedback. [0008] FIG. 2 is a cut-away view perspective of the linear vibrator of FIG. 1 in a sample electronic device enclosure. [0009] FIG. 3A is a cross-sectional view of the linear vibrator of FIG. 1 in a first operational position within the enclosure of FIG. 2 . [0010] FIG. 3B is a cross-sectional view of the linear vibrator of FIG. 1 in a second operational position within the enclosure of FIG. 2 . [0011] FIG. 4 is a cross-sectional view of the linear vibrator of FIG. 1 in a third operational position within the enclosure of FIG. 2 , providing localized haptic feedback. [0012] FIG. 5 is a flowchart depicting operational modes of the linear vibrator of FIG. 1 . DETAILED DESCRIPTION [0013] One embodiment described herein may take the form of a linear vibrator capable of providing localized haptic feedback. The vibrator may include a mass and a driver operable to oscillate or otherwise move the mass. The driver and mass may be contained within a shell. A projection may extend from one end of the mass through the shell. [0014] During normal operation, the driver may oscillate the mass rapidly along an axis of motion. The kinetic energy created by this oscillation may be transferred to the shell by a leaf spring or other coupling element coupling the mass and the shell. For example, any elastic element may couple the mass and shell. The shell, in turn, may be connected or affixed to a housing of an electronic device. In this manner, the housing may vibrate as the kinetic energy of the mass oscillation is transferred through the shell and to the housing, thereby providing generalized haptic feedback. [0015] Further, the vibrator may be operated in a boosted mode to provide localized haptic feedback. In the boosted mode, the driver moves the mass reciprocally further along its axis of motion. The range of motion of the mass in the boosted mode is sufficient to cause the projection to impact a portion of the electronic device housing. The projection may transfer kinetic energy directly to the impacted portion of the housing. Since the projection is relatively small in relation to the size of the housing, this impact may create a vibration in a relatively small area of the housing. In certain embodiments, the vibration may be felt only in the impacted portion of the housing. In other embodiments, the vibration may be felt in some area around the impacted portion but generally not across the entirety of the housing. Thus, the embodiment may provide generalized haptic feedback when operating in a standard mode and localized haptic feedback when operating in a boosted mode. [0016] FIG. 1 is a cut-away view of one sample embodiment of a linear vibrator 100 , taken approximately through the center of the embodiment. It should be appreciated that the linear vibrator 100 shown in FIG. 1 is simplified for purposes of clarity. For example, an elastic member (such as a leaf spring) generally rests between the magnet 105 and shell 110 ; the elastic member is not shown in FIG. 1 . Likewise, one or more pads may be placed between the inner surface of the top wall 115 and the top of the magnet to mute or muffle sounds created by the magnet impacting the shell. These pads are likewise not shown. Other elements on the linear vibrator 100 may also be omitted from FIG. 1 for purposes of clarity, although one of skill in the art will appreciate that such elements may be present in operation or construction. [0017] Generally, the linear vibrator 100 includes a shell 110 , a coil 120 disposed within the shell and adjacent the interior of the shell's sidewall(s), a mass (e.g., magnet) 105 within the coil and a tap rod 125 projecting upwardly from the magnet. “Up,” “down,” “top,” “bottom” and other such directions and/or references are used for purposes of convenience and with respect to the orientation shown in the figures, although it should be appreciated that certain embodiments may vary such directions, references and relationships described by directions and/or references, as necessary. For example, in some embodiments the tap rod 125 may project downwardly from the magnet 105 when the linear vibrator 100 is in the orientation shown in FIG. 1 . [0018] It should also be appreciated that the mass 105 need not be magnetic in and of itself. Instead, the mass 105 may be made of steel, iron or another material that reacts to magnetic fields, such that the mass may move when the coil 120 is energized. Similarly, it should be appreciated that the single coil 120 shown in the figures may be replaced with multiple coils in order to create a multi-phase actuator. [0019] The tap rod 125 extends through an opening 130 in the top of the shell and is affixed to the magnet 105 . The tap rod may be made from any suitable material, including metal, ceramic, a magnetic material, composites, plastics and the like. As the magnet 105 moves, the tap rod 125 moves. [0020] FIG. 2 is a cut-away view showing the linear vibrator 100 affixed to a wall 200 of the electronic device enclosure 205 . The enclosure 205 may be the body of a mobile phone, for example, or the body of a tablet computing device, personal digital assistant, laptop computer, computing peripheral or other suitable device. Typically, although not necessarily, the linear vibrator's shell is affixed to a rear wall 200 of the enclosure. In the present embodiment, neither the shell 110 nor the tap rod 125 of the vibrator abuts the enclosure 205 when the vibrator is inactive. An air gap 210 exists between the top of the tap rod and the inner surface of the upper wall 215 of the device enclosure. [0021] It should be appreciated that the size, configuration and/or positioning of the shell 110 and/or tap rod 125 may vary from embodiment to embodiment. Accordingly, the setup shown in FIG. 2 is meant merely to be illustrative of one sample embodiment. [0022] FIGS. 3A and 3B depict the linear vibrator 100 during normal operation (e.g., when generalized haptic feedback is required or requested). During normal operation, current is provided to the coil 120 . When the coil is energized, it generates a magnetic field that displaces or deflects the magnet 105 . Generally, the magnet 105 is deflected upward. When the coil 120 is de-energized, the magnet may return to its initial position. Thus, if the current is a direct current, the coil may be sequentially energized and de-energized to rapidly oscillate the magnet between the positions shown in FIGS. 3A and 3B . It should be appreciated that the deflection shown in FIG. 3B results from energizing the coil 120 . When the coil is energized, the size of the air gap 210 between the tap rod and top surface of the enclosure shrinks, but typically the air gap is still present. The motion of the magnet 105 or mass may create a vibration or motion in the enclosure or associated electronic device, thereby generating a haptic feedback for a user. [0023] Other embodiments may provide an alternating current to energize the coil 120 . In these embodiments, the magnet 105 may be forced upward during one phase of the alternating current and downward during the other. Accordingly, it may not be necessary to sequentially energize and de-energize the coil as with a direct current. [0024] FIG. 4 depicts the linear vibrator 100 during a boosted operation, at maximum deflection. When enhanced localized haptic feedback is desired, the current provided to the linear vibrator 100 may be increased, thereby increasing the maximum deflection of the magnet 105 within the coil 120 . This, in turn, increases deflection of the tap rod 125 . In the present embodiment, the tap rod 125 is deflected sufficiently to impact the electronic device housing, thereby creating a localized feedback that may be physically perceived (for example, by a user's finger or hand). The aforementioned oscillation of the magnet 105 draws the tap rod 125 down, away from the enclosure, and then pushes the rod into the enclosure. The frequency of oscillation may be varied to create different haptic responses. [0025] Certain embodiments may actuate the linear vibrator 100 in response to different input signals. Further, the vibrator 100 may be actuated in normal or boosted mode in response to different input signals. As one non-limiting example, the vibrator may be incorporated into a mobile telephone having a touch-sensitive input. When a telephone call is received and the phone is set to a silent or vibrate mode, the linear vibrator 100 may operate in the normal mode. Thus, the received call functions as an input signal to activate the vibrator. The normal mode may not only provide haptic feedback, but an audible feedback such a s a “buzz” or vibrating noise, as well. [0026] Further, the vibrator 100 may be configured to be activated when a user touches a particular portion of a touch-sensitive screen of the mobile phone. When the user's touch or near-touch is sensed in the appropriate area of the screen, the vibrator may be activated in a boosted mode, thereby providing localized haptic feedback directly under the area in which the touch was sensed. In this manner, the localized haptic feedback may serve to confirm the touch to the user, for example by emulating the feeling of pressing a button. In this embodiment, the linear vibrator 100 is located under the particular portion of the touch screen in which localized haptic feedback is desired. The touch screen may be capacitive sensing, resistive sensing, or the like. In some embodiments, the button may not be depressed by a user input. Instead, the localized haptic feedback may vibrate or move the button (or button area) in such a manner that it emulates the feeling of pressing a button, for example through vibration or motion of the button area. [0027] This may be useful, for example, in a touch-sensitive mobile phone having a button or other input that is not physically depressed but instead operates when a touch is sensed. That is, instead of mechanical actuation, the button may initiate an input command when the phone senses a user is touching the button. (“Button,” in this case, refers to a particular portion of the touch screen as opposed to a separate, mechanically actuated input) By providing localized haptic feedback at the physical location of the button when it is touched, a user may know his touch was sensed and the input initiated/accepted. Thus, the linear vibrator 100 may be located beneath the button. In another embodiment, touching the button may toggle the vibrator between the boosted and normal modes. In such an embodiment, the haptic feedback may occur after the user input as toggled the operational mode and after the user input has ceased. Accordingly, the user input need not be present in order for a particular operational mode to be active; rather, the user input can impact the mode of haptic feedback even after the input has ceased. [0028] FIG. 5 is a general flowchart showing one sample method for operating the linear vibrator described herein. The method begins in operation 500 , in which an actuation signal is received by the embodiment. In operation 505 , it is determined whether the vibrator 100 is to be driven in normal or boosted mode. [0029] If normal mode is desired, operation 515 is executed and normal current is delivered to the linear vibrator 100 . This provides a generalized haptic output; the linear vibrator is driven so that the tap rod 125 does not impact the enclosure. Generally, the range of motion of the magnet 105 and tap rod 125 may be similar to that shown in FIGS. 3A and 3B . Following operation 515 , operation 520 is executed. [0030] By contrast, if a boosted mode is desired then operation 510 is executed. In operation 510 , sufficient current is provided to the linear actuator that it operates in the boosted mode described with respect to FIG. 4 . That is, a higher level of current is supplied to the coil than in the normal mode of operation, and the magnet 105 is deflected sufficiently that the tap rod impacts the enclosure. As the magnet oscillates, the tap rod 125 repeatedly strikes the enclosure to provide localized haptic feedback. Following operation 510 , operation 520 is accessed. [0031] In operation 520 , the embodiment determines if a termination condition is reached. The termination condition may vary and may depend on the mode in which the linear vibrator 100 is operating. For example, answering an incoming call may serve as a termination condition for the linear vibrator being driven in its normal mode. Similarly, the cessation of a capacitive input on a particular portion of a touch screen may serve as a termination condition when the linear vibrator is being driven in a boosted mode. [0032] If no termination condition is reached, then the embodiment continues providing current to operate the linear vibrator in operation 525 . Periodically, the embodiment returns to operation 520 to again check for a termination condition. [0033] If a termination condition is detected, then current to the vibrator is stopped and end state 530 is entered. [0034] It should be appreciated that either current or voltage may drive the linear vibrator. Accordingly, references to current herein should be understood to encompass voltage, as necessary or appropriate. [0035] Although embodiments have been described with respect to particular physical configurations and methods of operation, one of ordinary skill in the art will appreciate that alternatives exist. Such alternatives are contemplated and considered to be within the scope of protection.

An apparatus for providing haptic feedback, including: a shell defining an aperture; a driver disposed within the shell; a mass disposed within the coil; and a projection connected to the mass and extending through the aperture. Also described herein is a method for providing generalized and localized haptic feedback, including the operations of: receiving an input signal; determining if the input signal corresponds to a generalized haptic feedback; if so, providing a first input to a linear vibrator; otherwise, providing a second input to a linear vibrator; wherein the linear vibrator outputs a generalized haptic feedback in response to the first input; and the linear vibrator outputs a localized haptic feedback in response to the second input.

FIELD OF THE INVENTION This invention, as described in Disclosure Document No. 260928, filed Aug. 22, 1990, relates to power trains or drive trains. More particularly, this invention relates to a fluid mechanical device. Even more particularly, this invention relates to a continuously variable drive train for use in power equipment drive trains, etc. BACKGROUND OF THE INVENTION The use of various types of transmissions for transferring energy from a power source, such as an engine, to an output shaft is well known. Some transmissions utilize a plurality of differently sized gears and require manual shifting in order to employ the differently sized gears in a specific sequence as the speed of vehicle is increased. Some other common transmissions are automatic and do not require a clutch in order to shift from one speed to another. There has not heretofore been provided a continuously variable drive train having the advantages provided by the system of this invention. SUMMARY OF THE PRESENT INVENTION In accordance with the present invention there is provided a unique continuously variable drive train system which is very smooth and efficient. It provides for infinite variation in output speed. The drive train system of the invention is self-contained, self-controlled, and self-regulated. In a preferred embodiment the drive train system comprises: (a) a first rotatable bell housing which is adapted to be connected to and rotatably driven by said power source; (b) a second rotatable bell housing within said first housing; (c) a first fluid coupler disposed between said first and second housings, (d) a rotatable output shaft; (e) a first planetary gear assembly comprising a first sun gear, a first ring gear (which is a double ring gear having first and second integral sections), and a first planet carrier having at least one planet gear operatively connecting said first sun gear and the first section of the first ring gear, wherein said first planet carrier is connected to said output shaft in driving engagement therewith; (f) a second planetary gear assembly comprising a second sun gear, a second planet carrier, and at least one planet gear and one planet reversing gear operatively connecting said second sun gear and the second section of the first ring gear; (g) a third planetary gear assembly comprising a third sun gear which is operatively connected to the second section of the first ring gear by means of at least one planet gear; (h) a fourth planetary gear assembly comprising a fourth sun gear, a second ring gear, and a third planet carrier having at least one planet gear operatively connecting said fourth sun gear and said second ring gear; wherein said third planet carrier is connected to said second bell housing: (i) first one-way clutch means adapted to prevent said second planet carrier from rotating in a direction opposite to the direction of rotation of said output shaft; (j) second one-way clutch means disposed between said first bell housing and said fourth sun gear; wherein said second clutch means prevents said fourth sun gear from rotating at a speed greater than that of said first bell housing; (k) third one-way clutch means disposed between said second bell housing and said third sun gear; wherein said third clutch means prevents said third sun gear from rotating at a speed greater than that of said second bell housing; and (1) a second fluid coupler disposed between said second bell housing and said third sun gear. The first sun gear has a larger diameter than the third sun gear. Rotation of the first bell housing transmits energy through the planetary gear assemblies to the output shaft. The apparatus of this invention does not require use of electronic computers. The apparatus operates as a continuously variable unit which is mounted between the power source and the transfer case of trucks, tractors, etc. The apparatus is smoother than use of conventional equipment. It provides for a gradual transition from one range of operation to the next range. There is no need for any shifting mechanism. The apparatus utilizes two simple fluid couplers. There is no need for use of a torque converter. Also, there is no need for disc clutches or clutch bands. Other advantages of the apparatus of this invention will be apparent from the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS The invention is described in more detail hereinafter with reference to the accompanying drawing, wherein like reference characters refer to the same parts and in which: FIG. 1 is a side elevational, partially sectioned view of a preferred embodiment of the drive train system of the invention. DETAILED DESCRIPTION OF THE INVENTION In FIG. 1 there is shown a preferred embodiment of continuously variable drive train system 10 for connection to a power source such as an internal combustion engine or electric motor having an output shaft 12 which serves as the power input to the drive train system. For example, the drive train system of this invention may be located rearwardly of the power source and may be connected to the output shaft 12 by means of bolts 13. The drive train system 10 comprises a first rotatable bell housing 14 which is connected directly to the output shaft of the power source so that it rotates at the same speed and in the same direction as the shaft 12. The output shaft 20 extends through the drive train system at its central axis, as shown. The output shaft 20 can be operatively connected to any desired apparatus for utilization of the rotational energy of the shaft. A splined mounting sleeve 15 surrounds tubular shaft 46 which in turn surrounds output shaft 20. A sprague (oneway) clutch surrounds shaft 46. Sleeve 15 is secured to a stationary frame 11 (e.g., a vehicle frame). A dust cover 18 is connected to the rear end of the bell housing 14 and surrounds sleeve 15. O-rings 17A and 17B are sealing between the adjacent surfaces. Within bell housing 14 there is a second rotatable bell housing 22 which is connected to first pump 24A through housing section 22A and first turbine 24B. Bell housing 14 and bell housing 22 are both filled with a suitable hydraulic fluid. As bell housing 14 rotates, the pump 24A tends to cause the turbine 24B and bell housing 22 to rotate in the same direction. The front portion 22A of housing 22 includes a central hub which is splined or otherwise securely connected to the hub portion of sun gear 26. A planet carrier 28 is keyed to the output shaft 20 by means of key 21. A planet gear shaft 30 supports planet gear 32 between sun gear 26 and ring gear 34 as shown. As illustrated in the drawing, ring gear 34 is a double ring gear. It includes a first section which meshes with planet gear 32 and a second adjacent section which meshes with planet gear 50B. The first and second sections of ring gear 34 are integral with each other. They may be case as one piece, for example, or they may be individual gears which are bolted or riveted together. Bell housing 22 also includes two fluid coupler sections, i.e., second turbine 36A and second pump 36B. Primary sun gear 26, through planet gear 32, initially exerts negative torque and rotation on ring gear 34. It is ring gear 34 which, during starting range, initially transmits negative torque and rotation through planet gears 50A and 50B (which are integrally connected to each other) to drive sun gear 52 in positive direction at a higher rate of velocity than that of second turbine 36A, but sprague clutch 57 locks up to prevent the velocity of sun gear 52 and second pump 36B from exceeding that of turbine 36A. The negative rotation exerted on ring gear 34 occurs only initially. Eventually ring gear 34 will rotate in positive direction. Consequently, turbine 36A and pump 36B rotate positively at equal velocities. Thus, no driving torque will be generated between turbine 36A and pump 36B during the starting range. At the rear of housing 22 there is a planetary carrier housing 23 which serves to support planet gear shaft 40 on which there is carried a planet gear 42 between sun gear 45 and ring gear 44A. Sun gear 44B is connected to ring gear 44A by means of sleeve portion 44C. Member 37 is connected at its upper end to pump 36B and at its lower end it is splined to tubular shaft 52A via spline 52B. The opposite end of sleeve 52A comprises sun gear 52. A reversing planet gear 48 is carried on planet shaft 47 between sun gear 44B and planet gear 50. As shown, the planet gear 50 includes two gear sections (50A and 50B), one of which is larger than the other, as illustrated. One portion (50B) resides between planet gear 48 and ring gear 34. The other portion (50A) is in operable connection with sun gear 52. One way (sprague) clutch 55 is located between mounting sleeve 15 and tubular shaft 46. Sleeve 15 is splined to block 16 which is rigidly attached to the frame 11. When the sprague clutch becomes locked, tubular shaft 46, planet carrier 46A, planet shaft 47, and planet shaft 49 all remain stationary. Planet shafts 47 and 49 are carried on planet carrier 46A. One-way (sprague) clutch 56 is located between the hub of sun gear 45 and bell housing 14 to prevent the sun gear 45 from rotating faster than housing 14. One way (sprague) clutch 57 is located between member 37 and housing 22 to prevent member 37, sun gear 52 and coupler section 36B from rotating faster than housing 22. The drive train system 10 provides three ranges of operation with a gradual transition from one range to the next without any external controlling device. All of the gears of the drive train system are permanently and rotatably interconnected and remain so throughout all three ranges of operation. Because the drive train system provides for forward driving of the output shaft, a conventional gear box may be connected to the output shaft to provide for neutral, forward drive, and reverse drive operation. The operation of the drive train system will now be explained. In the first range of operation, the first pump and first turbine, in conjunction with the first sun gear, third sun gear and double ring gear, exert torque and rotation on the output shaft. Also, the second pump is caused to rotate at a rate of velocity equal to that of the second turbine. Specifically in the first range of operation, first pump 24A and housings 14 and 18 begin to spin. Then first turbine 24B and sun gear 26 rotate in a positive direction (i.e., in the same direction as shaft 12 from the power plant). As turbine 24B begins to rotate, then one-way clutch 55 locks up immediately to prevent negative rotation of planet carrier 46A, shaft 47 and shaft 49. Planet gear 32 will rotate negatively on planet shaft 30 to drive double ring gear 34 in negative direction. Ring gear 34 will rotate planet gear 50 negatively on planet shaft 49 to drive sun gear 52 in positive direction. However, the velocity of the sun gear 52 is restrained to rotate only to the extent of the positive velocity of turbine 24B. This is due to the locked up one-way clutch 57. Turbine 36A and pump 36B rotate at equal velocities during the starting or first range of operation. Accordingly, elements 52, 37, 24B, 22A, 36A, 36B and sun gear 26 will all rotate as one unit. Sun gear 26 is larger than sun gear 52 and has more teeth (e.g., 78 teeth versus 54 teeth). Both gears are indirectly in mesh with double ring gear 34. Consequently, there exists a ratio differential between the ratio of the first gear set and the ratio of the third gear set. This ratio differential is such that double ring gear 34 is allowed to rotate in negative direction, but it is also simultaneously restrained to a limited degree. Since sun gear 52 becomes locked to turbine 24B and also becomes locked indirectly to sungear 26, this sun gear 52 serves as a rotating reaction member. This reaction is transmitted through planet gears 50A and 50B (which are integral portions of the same gear) to restrain the negative velocity of double ring gear 34. This conversely exerts a positive torque and rotation on planet carrier 28 and output shaft 20, merely at a velocity equal to the extent of the restraint. If sun gear 26 has 78 teeth and sun gear 52 has 54 teeth, for example, then there is a 24 tooth differential which provides a certain degree of restraint on double ring gear 34. If sun gear 26 has 78 teeth and sun gear 52 has 68 teeth, then there is only a 10 tooth differential between the two gears which provides less restraint on the ring gear 34. If sun gear 26 and sun gear 52 have an equal number of teeth, then there is no differential. As a result, there would be no restraint on ring gear 34. Consequently, ring gear 34 would be allowed to rotate negatively without exerting any torque or rotation on output shaft 20. Assuming that sun gear 26 has 78 teeth and sun gear 52 has 54 teeth, then one complete revolution of these sun gears is equal to 24.9366 of the 114 teeth of ring gear 34. This indicates that ring gear 34 has been restrained in the amount covering 24.9366 teeth of the ring gear's 114 teeth. This results in a ratio of 4.5716:1 (turbine to output ratio). Consequently, the positive rotation of sungear 26 will now rotate planet gear 32 negatively on planet shaft 30 and cause planet gear 32 to be rolled positively around the inner circumference of ring-gear 34, the distance of the restrained 24.9366 teeth which will result in a 4.5716:1 turbine-to-output shaft speed ratio. This sequence will continue tooth by tooth throughout the first range of operation, at a turbine to output speed ratio of 4.5716:1. During the second part of the first range of operation, the negative rotation of ring gear 34 is utilized in that it rotates planet gear 50 negatively while gear portion 50A rotates sun gear 52 positively and gear portion 50B rotates reversing planet gear 48 on shaft 47 to rotate sun gear 44B and ring gear 44A of the fourth gear set in negative direction. Ring gear 44A and gear 34 always rotate in the same direction. The orbit of planet shaft 40 and planet gear 42, plus the negative rotation of ring gear 44A, causes sun gear 45 to rotate. Ring gear 44A, through planet gear 42, accelerates sun gear 45 at the rate of velocity five times that of coupler section 24A and of the main drive shaft 12. Eventually, sun gear 45 will reach the velocity of shaft 12 and housing 14. At that point, one-way clutch 56 will lock up to prevent the velocity of sun gear 45 from exceeding that of the shaft 12 and coupler pump 24A. This then initiates the intermediate range of operation. When the velocity of turbine 24B, housings 22 and 23, and the orbit of planet shaft 40 and planet gear 42 exceeds the lock-up point of one-way clutch 56, then planet gear 42 will employ sun gear 45 as a rotating reaction member to exert positive torque (restraint) on the negative rotating ring gear 44A. During the starting range, the power flow originated from the negative rotation of ring gear 34 and flowed through gears 50B, 48, and 44B to ring gear 44A of the fourth gear set. However, during the intermediate range, the power flow reverses and originates from the orbiting planet shaft 40 and flows through gears 42, 44A, 44B, 48 and 50A to restrain ring gear 34. When the negative rotation of ring gear 34 is restrained, that allows sun gear 26, through planet gear 32, to exert additional torque and acceleration to planet carrier 28 and therefore output shaft 20. Eventually, ring gear 34 will reach the point of zero velocity and then begin to rotate and accelerate in the positive direction. Although the factor of "restraint" does not cease, the power flow originating through planet shaft 40 and transmitted through 44A, 44B and 50A will assist in accelerating ring gear 34, planet carrier 28 and output shaft 20. From the beginning of the intermediate range, the torque generated through shafts 40, 42, 44A, 44B, 48, 50A and 50B to sun gear 52 has forced gear 52 and pump 36B to decelerate back towards zero velocity. With turbine 36A accelerating in the positive direction and pump 36B decelerating, there occurs a "kinetic" energy buildup within the fluid coupler 36A/36B. When this "kinetic" energy builds up to a point where it overpowers the negative torque transmitted through sun gear 44B, then pump 36B and sun gear 52 (through gears 50A and 50B and reversing planet gear 48) will employ the greatly accelerated sun gear 44B as a rotating reaction member to assist ring gear 34 in accelerating planet carrier 28 and output shaft 20. At this point, the final range of operation is initiated. The "kinetic" energy generated in fluid coupler 36A/36B and exerted on pump 36B and sun gear 52 is great enough to assist in accelerating ring gear 34, planet carrier 28 and output shaft 20. In other words, sun gear 52 drives gears 50A and 50B. Then gear 50B, through gear 48, uses gear 44B as a rotating reaction member to cause ring gear 34 to accelerate. This results in acceleration of output shaft 20. The apparatus shown and described herein operates through a triple path drive. Sun gear 26, sun gear 44B, and sun gear 52 all drive simultaneously. As previously described, sun gear 52 (through gears 50A, 50B and reversing planet gear 48) uses the greatly accelerated sun gear 44B as a rotating reaction member to assist gear 34 in accelerating planet carrier 28 and output shaft 20. Finally, all elements will rotate, each at its ultimate rate of velocity, driven through the triple path drive. During the final range of operation, any slippage occurring in either fluid coupler tends to cause deceleration of ring gear 34, and increased load on output shaft 20 will decelerate ring gear 34. This allows turbine 24B and sun gear 26 to advance. An increase in torque input will also decelerate ring gear 34 and allow pump 24A and turbine 24B and sun gear 26 to advance without affecting the velocity of the output shaft 20. Thus, with load on the output or increasing torque input, or both, will enhance the turbine to output speed ratio. In reviewing the operation of the apparatus of this invention it will be seen that some sun gears serve as driving elements and in other instances these same sun gears will serve as rotating reaction members. This multiple feature has not heretofore been utilized in drive trains and is very unique. During the starting range, sun gear 26 serves as a driving element, planet carrier 46A serves as a stationary reaction member, and sun gear 52 serves as a rotating reaction member. Sun gear 45 idles freely in the positive direction. During the intermediate range, sun gear 26 and sun gear 44B serve as driving elements. Planet carrier 46A serves as a stationary reaction member, and sun gear 45 serves as a rotating reaction member. During the final range, sun gear 26 still serves as a driving element, and sun gear 52 now also serves as a driving element. Sun gear 44B serves as a fast rotating reaction member. Planet carrier 46A rotates in a positive direction. One-way clutch 55 over-runs. During the intermediate range and the final range of operation, when the accelerator pedal is depressed to speed up the motor, the following is what happens at the site of ring gear 34: pump 24A and bell housing 14 will surge ahead, while turbine 24B and output shaft 20 will momentarily (a fraction of a second) remain at a constant velocity. When housing 22 accelerates, clutch 56 unlocks and permits sun gear 45 to accelerate and permits ring gear 44A, sun gear 44B, and gears 48 and 50 to decelerate double ring gear 34. As outer housing 14 surges ahead, then pump 36B and sun gear 52 will be caused to surge ahead and, through gear 50, will permit double ring gear 34 to decelerate. As turbine 24B and sun gear 26 surge ahead (before sun gear 45 velocity reaches that of housing 22 to again lock-up clutch 56), then sun gear 26 (through planet gear 32) will decelerate double ring gear 34. In the first phase of the starting range, the ratio differential between the first gear set and the third gear set is such that sun gear 52 permits negative rotation of ring gear 34, but simultaneously restrains the velocity of gear 34 to a certain degree, which results in a 4.5716:1 turbine to output speed ratio. In the second phase of the starting range the negative rotation of ring gear 34, through gears 50B, 48, 44B, 44A and 42 drives sun gear 45 in positive direction at a rate of velocity five times that of housing 14 and pump 24A. Eventually sprague clutch 56 locks sun gear 45 to housing 14 to initiate the intermediate range. In the first phase of the intermediate range (when sprague clutch 56 locks up) then the path of power flow reverses--it flows from the orbiting planet shaft 40 where gear 42 employs sun gear 45 as a rotating reaction member to drive gears 44A, 44B, 48 and 50B to restrain ring gear 34. In the second phase of the intermediate range, the drive through gears 42, 44A, 44B, 48 and 50B continues and then switches to gear 50A to decelerate sun gear 52 and pump 36B. Ring gear 34 at this time is rotating in positive direction. In the final range there is a triple path drive. Ring gear 44A and sun gear 44B are accelerating in positive direction, and through gears 48 and 50B, assist in accelerating ring gear 34. Pump 36B and sun gear 52 accelerate, and sun gear 52 (through gears 50A, 50B and 48) employs fast rotating sun gear 44B as a rotating reaction member to accelerate planet gear 50B and ring gear 34--all this to assist sun gear 26 in accelerating planet carrier 28 and output shaft 20. The basic concept of the apparatus of this invention involves planetary gearsets where (a) the sungear of the gearset is permitted to rotate freely in a positive direction, and (b) the ring gear of the same gearset rotates freely in a negative direction without exerting rotation on the output shaft, and (c) means are provided to gradually restrain the negative velocity of the ring gear to thereby exert torque and rotation on the output shaft. The largest sungear serves as the primary input. The factor of restraint does not cease; it is present through operation of the apparatus regardless of the range of operation. As previously described herein, the entire continuously variable drive train system spins or rotates during operation when it is connected to a power source. All of the elements of the system are permanently and rotatably interconnected. No shifting is required. A gradual transition is obtained from one range of operation to the next range of operation. Other innovations of the system of this invention are apparent from the foregoing description and the accompanying drawings. Other variants are possible without departing from the scope of this invention. The absolute size of the various gears present in the system, and the number of teeth on each gear, may vary. These are matters which are considered design parameters which can be varied by engineers or designers when designing the system for a particular application.

A continuously variable drive train or power train which is a fluid mechanical drive system which is self-contained and self-controlled. It is useful as in power equipment drive train between a power source and a transfer case, for example, etc. It includes first and second rotatable bell housings, two fluid couplers, and a plurality of inter-connected planetary gear assemblies for transmitting rotational energy from a power source (e.g., an engine) to an output shaft.

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a divisional of U.S. patent application Ser. No. 12/196,405 filed on Aug. 22, 2008 , now U.S. Pat. No. 8,128,658 issued Mar. 6, 2012, which is a continuation-in- part application of: (1.) U.S. patent application Ser. No. 11/541,506 filed on Sep. 29, 2006, now U.S. Pat. No. 7,601,165 issued Oct. 13, 2009; (2.) U.S. patent application Ser. No. 12/014,399 filed on Jan. 15, 2008, now U.S. Pat. No. 7,909,851 issued Mar. 22, 2011; (3.) U.S. patent application Ser. No. 12/014,340 filed on Jan. 15, 2008. now U.S. Pat. No. 7,905,904 issued Mar. 15, 2011; (4.) U. S. patent application Ser. No. 11/935,681 filed on Nov. 6, 2007, now U.S. Pat. No. 7,905,903 issued Mar. 15, 2011; (5.) U.S. patent application Ser. No. 11/869,440 filed on Oct. 9, 2007, now U.S. Pat. No. 7,857,830 issued Dec. 28, 2010; (6.) U.S. patent application Ser. No. 11/784,821 filed on Apr. 10, 2007; (7.) U.S. patent application Ser. No. 11/347,661 filed on Feb. 3, 2006, now U.S. Pat. No. 7,749,250 issued Jul. 6, 2010; and (8.) U.S. patent application Ser. No. 11/347,662 filed on Feb. 3, 2006, now abandoned. The disclosures of the above applications are incorporated herein by reference. FIELD The present disclosure relates to method of coupling soft tissue to bone and, more particularly, to a method and apparatus using a plurality of fasteners and suture cinch loop construction to couple soft tissue to a bone. BACKGROUND The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. It is commonplace in arthroscopic procedures to employ sutures and anchors to secure soft tissues to bone. Despite their widespread use, several improvements in the use of sutures and suture anchors may be made. For example, the procedure of tying knots may be very time consuming, thereby increasing the cost of the procedure and limiting the capacity of the surgeon. Furthermore, the strength of the repair may be limited by the strength of the knot. This latter drawback may be of particular significance if the knot is tied improperly as the strength of the knot in such situations may be significantly lower than the tensile strength of the suture material. To improve on these uses, sutures having a single preformed loop have been provided. FIG. 1 represents a prior art suture construction. As shown, one end of the suture is passed through a passage defined in the suture itself. The application of tension to the ends of the suture pulls a portion of the suture through the passage, causing a loop formed in the suture to close. Relaxation of the system, however may allow a portion of the suture to translate back through the passage, thus relieving the desired tension. It is an object of the present teachings to provide an alternative device for anchoring sutures to bone and soft tissue. The device, which is relatively simple in design and structure, is highly effective for its intended purpose. The present teachings provide for a method for coupling soft tissue to bone. The method includes the following: implanting in bone a first anchor including a first suture construct connected to the first anchor; passing a first adjustable loop of the first suture construct at least one of over or through the soft tissue; coupling the first adjustable loop to one of a first locking feature of the first anchor or a second locking feature of a second anchor; adjusting the first adjustable loop by pulling a first end of the first suture construct; and securing the soft tissue against bone by pulling the first end of the first suture construct. The present teachings provide for another method for coupling soft tissue to bone. The method includes: implanting in bone a first anchor including a first suture construct connected to the first anchor, the first suture construct including a first end and a second end; passing a first adjustable loop of the first suture construct at least one of over or through the soft tissue; coupling the first adjustable loop to a first locking feature of a second anchor having a second suture construct with a second adjustable loop; adjusting the first adjustable loop by pulling the first end of the first suture construct, the first end passed through a first passage portion defined by the first suture construct; securing the soft tissue against the bone with the first adjustable loop by pulling the first end; implanting the second anchor in bone; passing the second adjustable loop at least one of over or through the soft tissue; coupling the second adjustable loop to a second locking feature of a third anchor; implanting the third anchor in bone; adjusting the second adjustable loop by pulling a third end of the second suture construct; and securing the soft tissue against the bone with the second adjustable loop by pulling the third end of the second suture construct. The present teachings also provide for a bone anchor for coupling soft tissue to bone. The bone anchor includes a bone coupling portion, a tissue coupling portion, and a suture construct. The bone coupling portion includes a plurality of bone locking features. The tissue coupling portion is adjacent to the bone coupling portion. The tissue coupling portion defines an aperture and a suture coupling feature. The suture construct is seated within the aperture. The suture construct includes a first adjustable loop. A first end of the suture construct is passed through the first passage portion defined by the suture construct. The suture construct defines a first aperture and a second aperture at opposite ends of the first passage portion. Pulling the first end of the suture construct decreases a length of the first adjustable loop. SUMMARY To overcome the aforementioned deficiencies, a method for configuring a braided tubular suture and a suture configuration are disclosed. The method includes passing a first end of the suture through a first aperture into a passage defined by the suture and out a second aperture defined by the suture so as to place the first end outside of the passage. A second end of the suture is passed through the second aperture into the passage and out the first aperture so as to place the second end outside of the passage. A method of surgically implanting a suture construction in a bone is disclosed. A suture construction is formed by passing the suture through a bore defined by a locking member. A first end of the suture is passed through a first aperture within the suture into a passage defined by the suture and out a second aperture defined by the suture so as to place the first end outside of the passage and define a first loop. A second end of the suture is then passed through the second aperture into the passage and out the first aperture so as to place the second end outside of the passage, and define a second loop. A fastener is coupled to bone. Soft tissue is then passed through the first and second loops. The locking member is coupled to the fastener. Tension is applied onto the first and second ends to constrict the first and second loops about the soft tissue. In another embodiment, a method of surgically implanting a suture is disclosed. The suture is passed through a bore defined by a first fastener. A suture construction is formed by passing the suture through a bore defined by a locking member. A first end of the suture is passed through a first aperture within the suture into a passage defined by the suture and out a second aperture defined by the suture so as to place the first end outside of the passage and define a first loop. A second end of the suture is then passed through the second aperture into the passage and out the first aperture so as to place the second end outside of the passage, and define a second loop. A second fastener is coupled between the first and second loops. After the fastener is coupled to the patient, tension is applied onto the first and second ends to constrict at least one of the first and second loops about the soft tissue. Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. DRAWINGS The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. FIG. 1 represents a prior art suture configuration; FIGS. 2A and 2B represent suture constructions according to the teachings; FIG. 3 represents the formation of the suture configuration shown in FIG. 4A ; FIGS. 4A and 4B represent alternate suture configurations; FIGS. 5-7 represent further alternate suture configurations; FIG. 8 represents the suture construction according to FIG. 5 coupled to a bone engaging fastener; FIGS. 9-11B represent the coupling of the suture construction according to FIG. 5 to a bone screw; FIGS. 12A-12E represent the coupling of a soft tissue to an ACL replacement in a femoral/tibial reconstruction; FIGS. 13A-13D represent a close-up view of the suture shown in FIGS. 1-11C ; FIGS. 14A and 14B represent side and top views of a suture construction used to couple soft tissue to bone; FIGS. 15A-15D represent an alternate method of coupling soft tissue to bone; FIGS. 16A-16D represent yet another method for coupling soft tissue to bone; FIG. 17 is an alternate method of coupling soft tissue to bone; FIGS. 18A-18B represent an alternate mechanism for coupling soft tissue to bone; and FIGS. 19A-19C represent another method of coupling soft tissue to bone. DETAILED DESCRIPTION The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. FIG. 2A represents a suture construction 20 according to the present teachings. Shown is a suture 22 having a first end 24 and a second end 26 . The suture 22 is formed of a braided body 28 that defines a longitudinally formed hollow passage 30 therein. First and second apertures 32 and 34 are defined in the braided body 28 at first and second locations of the longitudinally formed passage 30 . Briefly referring to FIG. 3 , a first end 24 of the suture 22 is passed through the first aperture 32 and through longitudinal passage 30 formed by a passage portion and out the second aperture 34 . The second end 26 is passed through the second aperture 34 , through the passage 30 and out the first aperture 32 . This forms two structures or loops 46 and 46 ′. Structures defined herein can be loops, knots or tangles, each having unique properties. As seen in FIG. 2B , the relationship of the first and second apertures 32 and 34 with respect to the first and second ends 24 and 26 can be modified so as to allow a bow-tie suture construction 36 . As described below, the longitudinal and parallel placement of first and second suture portions 38 and 40 of the suture 22 within the longitudinal passage 30 resists the reverse relative movement of the first and second portions 38 and 40 of the suture once it is tightened. The first and second apertures are formed during the braiding process as loose portions between pairs of fibers defining the suture. As further described below, the first and second ends 24 and 26 can be passed through the longitudinal passage 30 multiple times. It is envisioned that either a single or multiple apertures can be formed at the ends of the longitudinally formed passage. As best seen in FIGS. 4A and 4B , a portion of the braided body 28 of the suture defining the longitudinal passage 30 can be braided so as to have a diameter larger than the diameter of the first and second ends 24 and 26 . Additionally shown are first through fourth apertures 32 , 34 , 42 , and 44 . These apertures can be formed in the braiding process or can be formed during the construction process. In this regard, the apertures 32 , 34 , 42 , and 44 are defined between adjacent fibers in the braided body 28 . As shown in FIG. 4B , and described below, it is envisioned the sutures can be passed through other biomedically compatible structures. FIGS. 5-7 represent alternate constructions wherein a plurality of loops 46 a - d are formed by passing the first and second ends 24 and 26 through the longitudinal passage 30 multiple times. The first and second ends 24 and 26 can be passed through multiple or single apertures defined at the ends of the longitudinal passage 30 . The tensioning of the ends 24 and 26 cause relative translation of the sides of the suture with respect to each other. Upon applying tension to the first and second ends 24 and 26 of the suture 22 , the size of the loops 46 a - d is reduced to a desired size or load. At this point, additional tension causes the body of the suture defining the longitudinal passage 30 to constrict about the parallel portions of the suture within the longitudinal passage 30 . This constriction reduces the diameter of the longitudinal passage 30 , thus forming a mechanical interface between the exterior surfaces of the first and second parallel portions as well as the interior surface of the longitudinal passage 30 . As seen in FIGS. 8-11B , the suture construction can be coupled to various biocompatible hardware. In this regard, the suture construction 20 can be coupled to an aperture 52 of the bone engaging fastener 54 . Additionally, it is envisioned that soft tissue or bone engaging members 56 can be fastened to one or two loops 46 . After fixing the bone engaging fastener 54 , the members 56 can be used to repair, for instance, a meniscal tear. The first and second ends 24 , 26 are then pulled, setting the tension on the loops 46 , thus pulling the meniscus into place. Additionally, upon application of tension, the longitudinal passage 30 is constricted, thus preventing the relaxation of the tension caused by relative movement of the first and second parallel portions 38 , 40 , within the longitudinal passage 30 . As seen in FIGS. 9-11B , the loops 46 can be used to fasten the suture construction 20 to multiple types of prosthetic devices. As described further below, the suture 22 can further be used to repair and couple soft tissues in an anatomically desired position. Further, retraction of the first and second ends allows a physician to adjust the tension on the loops between the prosthetic devices. FIG. 11 b represents the coupling of the suture construction according to FIG. 2B with a bone fastening member. Coupled to a pair of loops 46 and 46 ′ are tissue fastening members 56 . The application of tension to either the first or second end 24 or 26 will tighten the loops 46 or 46 ′ separately. FIGS. 12A-12E represent potential uses of the suture constructions 20 in FIGS. 2A-7 in an ACL repair. As can be seen in FIG. 12A , the longitudinal passage portion 30 of suture construction 20 can be first coupled to a fixation member 60 . The member 60 can have a first profile which allows insertion of the member 60 through the tunnel and a second profile which allows engagement with a positive locking surface upon rotation. The longitudinal passage portion 30 of the suture construction 20 , member 60 , loops 46 and ends 24 , 26 can then be passed through a femoral and tibial tunnel 62 . The fixation member 60 is positioned or coupled to the femur. At this point, a natural or artificial ACL 64 can be passed through a loop or loops 46 formed in the suture construction 20 . Tensioning of the first and second ends 24 and 26 applies tension to the loops 46 , thus pulling the ACL 64 into the tunnel. In this regard, the first and second ends are pulled through the femoral and tibial tunnel, thus constricting the loops 46 about the ACL 64 (see FIG. 12B ). As shown, the suture construction 20 allows for the application of force along an axis 61 defining the femoral tunnel. Specifically, the orientation of the suture construction 20 and, more specifically, the orientation of the longitudinal passage portion 30 , the loops 46 , and ends 24 , 26 allow for tension to be applied to the construction 20 without applying non-seating forces to the fixation member 60 . As an example, should the loops 24 , 26 be positioned at the member 60 , application of forces to the ends 24 , 26 may reduce the seating force applied by the member 60 onto the bone. As best seen in FIG. 12C , the body portion 28 and parallel portions 38 , 40 of the suture construction 20 remain disposed within to the fixation member 60 . Further tension of the first ends draws the ACL 64 up through the tibial component into the femoral component. In this way, suture ends can be used to apply appropriate tension onto the ACL 64 component. The ACL 64 would be fixed to the tibial component using a plug or screw as is known. After feeding the ACL 64 through the loops 46 , tensioning of the ends allows engagement of the ACL with bearing surfaces defined on the loops. The tensioning pulls the ACL 64 through a femoral and tibial tunnel. The ACL 64 could be further coupled to the femur using a transverse pin or plug. As shown in FIG. 12E , once the ACL is fastened to the tibia, further tensioning can be applied to the first and second ends 24 , 26 placing a desired predetermined load on the ACL. This tension can be measured using a force gauge. This load is maintained by the suture configuration. It is equally envisioned that the fixation member 60 can be placed on the tibial component 66 and the ACL pulled into the tunnel through the femur. Further, it is envisioned that bone cement or biological materials may be inserted into the tunnel 62 . FIGS. 13A-13D represent a close-up of a portion of the suture 20 . As can be seen, the portion of the suture defining the longitudinal passage 30 has a diameter d 1 which is larger than the diameter d 2 of the ends 24 and 26 . The first aperture 32 is formed between a pair of fiber members. As can be seen, the apertures 32 , 34 can be formed between two adjacent fiber pairs 68 , 70 . Further, various shapes can be braided onto a surface of the longitudinal passage 30 . The sutures are typically braided of from 8 to 16 fibers. These fibers are made of nylon or other biocompatible material. It is envisioned that the suture 22 can be formed of multiple type of biocompatible fibers having multiple coefficients of friction or size. Further, the braiding can be accomplished so that different portions of the exterior surface of the suture can have different coefficients of friction or mechanical properties. The placement of a carrier fiber having a particular surface property can be modified along the length of the suture so as to place it at varying locations within the braided constructions. FIGS. 14A and 14B represent the coupling of soft tissue to a bone. Shown is a plurality of bone engaging fasteners 60 coupled to suture constructions 22 shown in FIG. 2A or FIG. 4 . Each fastener 60 is coupled to a bone by being pressed into or threaded into an aperture formed within the bone. Adjoining fasteners are coupled together using loops 46 from an adjacent suture construction 22 . The fasteners 60 define a locking feature 92 which is used to couple the fastener 60 to the bone. Disposed on a first end of the fastener 60 is an aperture 94 configured to hold the suture construction 22 . Additionally, in the fastener 60 is a locking feature 100 configured to engage with one of the first or second loops 46 or 47 of an adjacent suture construction 22 . Returning briefly to FIG. 14A , a suture end 26 and first loop 46 can be passed around or through an aperture 84 in soft tissue. The first loop 46 is then fed around or through a second aperture 84 ′ formed in the soft tissue 80 . After passing through the aperture 84 ′, the first loop 46 is coupled to the coupling feature 100 in an adjacent bone coupling fastener 60 . At this point, the first and second ends 24 , 26 of the suture 22 are pulled tight, tightening the suture loop 46 about the soft tissue 80 . This pulls the soft tissue 80 against a surface of the bone. This can be used to couple soft tissue in an anatomy such in the repair of a rotator cuff. It is envisioned that a plurality of fasteners 60 can have associated suture constructions 22 which can similarly be coupled to adjacent fasteners 60 . Alternatively, the loops 46 , 47 can looped around or passed through the soft tissue 80 and then can be coupled to the coupling feature 100 of its fastener 60 . FIGS. 15A-15D represent an alternate method of coupling soft tissue 80 to a bone. As shown in FIG. 15A , a first bone coupling fastener 60 is coupled to an aperture 63 formed in the bone. The bone coupling fastener 60 defines a fastener accepting bore 96 . The bore 96 may be a through bore or may terminate within the fastener 96 . The fastener accepting bore 96 is configured to accept a suture bearing fastener 98 . The first loop 46 can be coupled to the second loop 47 to fix the soft tissue 80 . The suture bearing fastener 98 defines an aperture 104 configured to accept the suture construction 22 according to any of the present teachings. As described below, the fastener 98 can also have a concave suture locking feature 100 . Disposed at a proximal end 102 of the fastener 96 can be soft tissue piercing feature 105 which can be an acute angle. Additionally, the suture bearing fastener 98 can have locking features to facilitate the coupling to the bore 96 of the bone coupling fastener 60 . As seen in FIG. 15B , the suture construction of FIGS. 1-7 can be coupled to the suture bearing fastener 98 through the suture bearing aperture 104 using a knot. After the suture bearing fastener 98 is pressed through or adjacent to the soft tissue 80 , the suture construction 22 can be looped over the soft tissue 80 and engaged with the concave locking feature 100 . The suture bearing fastener 98 can be pressed into the fastener 60 to lock the suture 22 into place. Tension can then be applied to the suture 22 construction to constrict the loop 46 or loops 46 and 47 about the soft tissue 80 . As seen in FIGS. 15C and 15D , the soft tissue 80 can be threaded through the loops 46 and 47 prior to or after the coupling of the suture bearing fastener 98 to the bone engaging fastener 60 . A guide wire 99 can be coupled to the bone through the fastener bore 96 . The guide wire 99 is then used to align the suture bearing fastener 98 through the soft tissue 80 and into the bore 96 of fastener 60 . As shown in FIG. 16A-16C , one loop 46 of the suture construction 22 can have a fastening element 112 coupled thereto. This fastener element 112 can take the form of a hook having an aperture which accepts the suture from a loop 47 . The loop 46 of the suture construction can be passed through the aperture 84 formed in the soft tissue 80 . FIG. 16D shows the fastener element 112 can be coupled to the first loop 46 . After the first and second loops 46 and 47 are coupled together about the soft tissue 80 , tension can be applied to the ends of the construction to pull the soft tissue to the bone. As shown in FIG. 17 , bone engaging fastener 60 can have a bore 96 defined therein. The bore 96 can have a defined fastening loop 114 which is used to couple a suture construction 22 to the fastener 60 . In this regard, it is envisioned the passage portion 30 of the suture construction can be fixed within the fastening loop. One or both loops 46 and 47 can then be passed through an aperture 84 defined in the soft tissue 80 . These loops of material can be hooked to a hook 116 defined within the bore 96 . The application of tension to the ends pulls the soft tissue to the bone without the use of knots or additional fasteners. FIGS. 18A and 18B represent an alternate method of coupling soft tissue 80 to bone. Shown is a bone engaging fastener 60 defining an internal bore 96 . The internal bore 96 defines a locking mechanism such a through pin 120 . Disposed about the locking mechanism is a suture construction 22 having a single loop 46 . Disposed on the loop 46 is a locking hook 122 . As shown in FIG. 18B , the locking hook 122 can be used to couple the fastener 60 to a suture loop 124 passed through an aperture 84 formed in soft tissue 80 . The application of tension to the ends 22 and 26 of the suture construction 22 pulls the locking hook 122 and suture 124 into the bore 96 , thus locking the soft tissue 80 to the bone. As seen in FIGS. 19A-19C , the fastener 60 can have a pair of suture constructions 22 and 22 ′. The first suture 22 can have a coupling member 122 , while the second suture 22 ′ can have a loop 46 threaded through the soft tissue 80 . After the loop 46 is threaded through or around the soft tissue, the locking member 122 is coupled to the loop 46 . The application of tension to the ends 26 of the suture constructions 22 and 22 ′ pull the locking member 122 into a bore 96 formed by the fastener 60 . This locks the loop 46 into position. Tension on the end 26 of suture 22 then pulls the soft tissue to the bone. It should be noted that while the interior bore of the fasteners 60 is shown as being smooth, it is envisioned that the interior surface can have features such as barbs or locking tabs to facilitate the coupling of the suture engaging fastener 98 with the bone engaging fastener 60 . Additionally, the interior bores can define driving surfaces or features such as a hex head. The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. For example, any of the above mentioned surgical procedures is applicable to repair of other body portions. For example, the procedures can be equally applied to the repair of wrists, elbows, ankles, and meniscal repair. The suture loops can be passed through bores formed in soft or hard tissue. It is equally envisioned that the loops can be passed through or formed around an aperture or apertures formed in prosthetic devices, e.g. humeral, femoral or tibial stems. Such variations are not to be regarded as a departure from the spirit and scope of the invention.

A method and apparatus for coupling a soft tissue implant into a locking cavity formed within a bone. The method includes the following: implanting in bone a first anchor including a first suture construct connected to the first anchor; passing a first adjustable loop of the first suture construct at least one of over or through the soft tissue; coupling the first adjustable loop to one of a first locking feature of the first anchor or a second locking feature of a second anchor; adjusting the first adjustable loop by pulling a first end of the first suture construct; and securing the soft tissue against bone by pulling the first end of the first suture construct.

BACKGROUND OF THE INVENTION Cable operators sell advertising at a substantial discount compared to the broadcast networks because of the fragmented nature of the cable viewing situation. Cable viewers can "channel surf" and avoid commercials. While the total number of advertising spots in a cable system is very large, the number of viewers per channel is relatively small. This makes for inefficient advertising and results in a substantial lost opportunity for the cable industry. The sale of commercials is done on the basis of a "cost per thousand" viewers (CPM) parameter. The CPM for broadcast networks is typically more than double--in some cases triple--that of cable programmers. Advertisers pay on a sliding scale per reached viewer. A program or network which reaches larger numbers of viewers not only gets more revenue because the number of viewers is larger but also gets more revenue per viewer because of the efficiency of reaching a larger audience at one time. A series of steps are proposed in this invention to increase the effectiveness of the advertising on cable and similar multichannel media and raise the revenue potential of the advertising spots for the programmer and cable operator. SUMMARY OF THE INVENTION Accordingly, it is an object of this invention to provide a system and process which will solve the problems described above and overcome the disadvantages associated with the prior art systems described above. It is another object of the present invention to provide a process by which many, most, or all of the cable programmers synchronize their programming and insert the same commercial simultaneously. With this invention, the number of viewers reached is approximately the same as the number reached by the major over-the-air broadcast networks. The trend in viewing is away from the networks and to the cable programmers. In the near future, the sum of cable programming viewers will exceed the number of viewers watching any of the networks. Using this invention, the cable industry will be able to increase its CPM to a value equal to or exceeding that of the networks. This will substantially increase the profitability of advertising on cable. A full "road block" would be a situation in which all channels had the same commercial at the same time. No matter what channel the viewer tuned to, he would see the same commercial. This was occasionally done with approximate timing when there were just three networks. With the addition of more channels, particularly on cable, the "road block" approach has become nearly impossible to accomplish. There are technical reasons why this will become even more difficult in the future. It is a further object of the invention to provide a system and process which will overcome these problems and make a partial road block feasible. Since the same commercial will appear on a large number of cable programmer channels, a partial "road block" will be established. That is, a viewer switching between participating cable programmer channels will see the same commercial no matter which channel he chooses. The only way to escape the commercial is to go to a non-participating broadcast or cable channel or a channel which has no commercials. In principle, the broadcast networks can participate creating an even more comprehensive "road block". It is important to realize that "cable programming" forms the backbone of the telcos, DBS, and other media entry into the video business. The 1992 Cable Act required the cable industry to surrender its programming to its competitors. Thus this method also applies to the delivery of programming over these other media. It will be understood by those skilled in the art that this invention can be applied to any broadband media; i.e. any media which simultaneously delivers multiple channels. It will also be understood that this invention can be applied across several media so that the "road block" applies not only to attempts to switch channels within one media but also to attempts to switch to other media. In this case, a viewer switching from one broadband media, such as cable, to another broadband media, such as DBS, Video Dialtone, etc. etc. would see the same commercial. The fundamental principles involved in this invention are the synchronization of the time slots into which the commercials are inserted, the synchronization of the commercials, and the distribution of common timing information. Two fundamental ways of synchronizing commercials are to either make them simultaneously available to all channels or to download them and start them simultaneously. Downloading can be accomplished via a satellite signal, land lines of fiber, coax, twisted pairs, or other media, radio waves, or even physical movement of media which stores the commercial. Simultaneously starting the commercials can be accomplished in two ways. Either the information concerning the start time is downloaded and stored so that the equipment knows when to initiate the commercial or a commercial initiation command can be simultaneously delivered to all locations. In principal, these functions can be accomplished at either the display site or home, the cable headend, the satellite uplink facility, or the production facility. Clearly, the cost of equipment required is minimized if these functions are located in places where signals are concentrated. In general, multiple Programming Facilities feed each Production Facility. Multiple Production Facilities feed each Satellite Up Link Facility. Large numbers of cable headends are fed from each satellite. Large numbers of receive sites are fed from each headend. While any of these facilities can be used to implement the invention, the most economies are enjoyed if the invention is implemented at the Satellite Uplink Facilities or the Production Facilities. The National Synchronization Center provides signals appropriate to the implementation chosen. The National Synchronization Center may provide the timing information. The National Synchronization Center may be the source of simultaneously delivered commercials. The National Synchronization Center may be the source of the command which initiates commercials. Further improvements include the monitoring and logging of compliance and participation, the compensation for compliance, and an optional receive-site channel access control means to avoid interruptions in commercials appearing on multiple channels during channel changing. If the timing of the commercials is approximate, there may be some overlap or some gaps in the presentation of the commercial as the viewer switches from channel to channel. If the timing is precise, the overlap or gap is minimized. In order to increase the precision of the timing of the commercials and the programming which precedes and the programming which follows the commercials, it will be necessary for all of the participating programmers to utilize a common time base. The National Institute of Standards and Technology, NIST, (formerly the National Bureau of Standards, NBS) provides timing information of sufficient accuracy for this purpose. Other sources of timing information are available. It will be appreciated that the absolute correctness of time is not important. It is only important that participating networks are synchronized. The pre-recorded commercials are delivered in advance and contained in appropriate storage means such as magnetic or optical tape or disc or semiconductor or other memory. The pre-recorded commercials are simultaneously started with sufficient precision to appear simultaneous to viewers changing channels. Simultaneous delivery (via satellite or land link) of the commercials to all participating networks is a way of ensuring that the timing is precise as long as the same number of satellite links is used by all of the networks. Multiple satellite links or several links in cascade should be avoided. In addition, commercially available time compressor/expanders are available which stretch or squeeze the programming and/or commercial length to fit precisely in the time available. These technologies can be employed to ensure precise slots for the commercials. These technologies are included in commercially available professional video tape machines. They are adaptable to other media as well. All of these techniques are intended to permit the implementation of the "Cable Network". Most of the techniques do not require the modification of set top boxes. This will allow a rapid deployment. Only the last technique, an optional receive-site channel access control means to avoid interruptions in commercials appearing on multiple channels during channel changing, requires modification of set top box designs. This modification, however, is relatively inexpensive. A "road block" can be established without this improvement, but it will be less effective since the display of the commercial will be interrupted during channel changes. A Further Improvement In some circumstances, the nature of the programming will not allow precise timing. In other cases, the nature of the programming cannot be controlled and may at some times be amenable to precise timing and at other times not. A further improvement accommodates this situation. In the further improvement, programmers are provided with a financial incentive to synchronize the commercials and are measured and rewarded according to their willingness and ability to comply. The incentive is based on a formula which is determined by business conditions. An example is provided. In this example, all participating networks are supplied with precise time signals as above. The networks will precisely synchronize their commercials if this does not disrupt their programming. If a disruption is caused, the precision of the synchronization may be reduced. An important part of this further process is the measurement and logging of the timing of the commercial insertions. This data is relayed to a central point. Statistical data on network viewership is also accumulated. The total number of viewers covered by properly synchronized commercials is tallied and compared with the viewership rates for the broadcast networks. If the total number of viewers of a synchronized commercial is equivalent to that of the top rated broadcast network, the CPM rate used for that broadcast network applies to each complying cable network. The complying network is rewarded with that higher CPM applied to its viewership numbers. Any network which fails to synchronize gets the normal cable CPM for a stand-alone commercial. If the total number of viewers of a synchronized commercial is equivalent to that of the second rated broadcast network, the CPM rate used for that broadcast network applies and each complying cable network is rewarded with that CPM applied to its viewership numbers. Any network which fails to synchronize gets the normal cable CPM for a stand-alone commercial. If the total number of viewers of a synchronized commercial is equivalent to that of the third rated broadcast network, the CPM rate used for that broadcast network applies and each complying cable network is rewarded with that CPM applied to its viewership numbers. Any network which fails to synchronize gets the normal cable CPM for a stand-alone commercial. If the total number of viewers of a synchronized commercial fails to meet some minimum number, the normal cable CPM rates apply to all participants. This is just one example of how the compensation and incentive plan can be structured from a business perspective. Another Improvement Depending on the tuner used in the TV, VCR, or set top box, there may be some acquisition time required as the tuner goes from channel to channel. This can result in a noticeable glitch during channel change which interferes with the presentation of the commercial. This problem is aggravated if the channels are scrambled because the descrambler takes additional time to acquire the signal and properly descramble it. In some cases, the total time could be a significant fraction of a second and result in a very noticeable interruption. The situation becomes even worse if the programming is digitally compressed. This is because the digital decompression circuitry requires time to acquire and process the signal from the new channel. A possible approach for avoiding this problem is to employ two tuners, one for the current channel and one for the next channel. This adds significant expense. If the two channels are scrambled, two descramblers are necessary in addition to the tuners to make a "seamless transition". This is very expensive. If the two channels are digitally compressed, two decompression circuits will also be necessary to make a "seamless transition". This is extremely expensive. An approach proposed in this invention is to download instructions to the receiver to indicate the channels which are carrying the same commercial. If the viewer intends to switch from one channel to another, both of which have the same commercial, the channel indicator changes, but the tuner, and/or descrambler, and/or Decompression circuits remain on the current channel until the commercial is completed. Then, the tuner, and/or descrambler, and/or Decompression circuits go to the new channel. In this way an interruption in the display is avoided during the commercial. This process continues as the viewer goes from channel to channel unless one of the channels selected does not have the "road block" commercial. This part of the invention is inexpensively implemented in the microcomputer which controls the tuner and adds very little cost to the set top box or TV or VCR. In the case where channels are being scanned and one of the channels does not have the "road blocked" commercial, the microprocessor can determine if a scanning operation is underway and the channel without the "road blocked" commercial will be spanned before its signal can be acquired. In that case, the scanning process continues without changing the channel and the commercial continues without interruption. The Addressable Advertising invention for delivering targeted advertisements to consumers may be combined with the Road Block to increase advertising effectiveness even further. Addressable Advertising has been disclosed in patent application SN 08/354,620 filed Dec. 13, 1994 entitled Apparatus and Method for Targeting Advertisements to Consumers. Addressable Advertising can be implemented in three ways. One way is by switching between simultaneously delivered channels to deliver advertising appropriately targeted to the viewer. Another implementation downloads and stores advertisements in advance and selects the appropriate advertisement from those stored locally. Yet another implementation causes the appropriate advertisement to be selected from a server at a central site and switched onto the line connecting the subscriber. When the Road Block is also implemented, the same advertisement appears independent of which participating channel is watched. In summary, with the present invention, advertising can be presented in a "partial road block" or even a full "road block" fashion increasing the value of advertising to the advertiser, the programmer, the broadband signal delivery system, and reducing the annoyance to viewers of commercials flashing by. Methods of accomplishing this without the need for changes in set top boxes is presented. A more effective and pleasing technique is described for those situations where scrambling and/or digital compression are employed. These methods also apply to the artifacts which maybe present when a tuner takes a visible amount of time to acquire a new channel. BRIEF DESCRIPTION OF THE DRAWINGS The attainment of the foregoing and related objects, advantages and features of the invention should be more readily apparent to those skilled in the art, after review of the following more detailed descriptions of the invention, taken together the drawings, in which: FIG. 1: A satellite uplink/Production Facility prior to the invention; FIG. 2: A satellite uplink/Production Facility with precise commercial timing and optional signal time compression/expansion; FIG. 2a: Multiple locations are synchronized; FIG. 2b: Multiple facilities, sources, and receive systems and sites; FIG. 3: A satellite uplink/Production Facility with single-hop satellite delivered commercials for precise timing; FIG. 4: A satellite uplink/Production Facility with precise commercial timing and optional signal time compression/expansion and compliance monitoring and data collection; FIG. 5: A set top box with interruption suppression technology. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning now to the drawings, more particularly to FIG. 1, there is shown a block diagram of a satellite uplink/Production Facility prior to the invention comprising three major elements. The first element is a satellite 100 fed from a Satellite Uplink 102 which is in turn fed from a Production Facility 104. The Production Facility 104 and the Satellite Uplink 102 may be co-located or separated by an arbitrary distance. The satellite 100 is fed with signals from a satellite antenna 106 or dish, fed with connection 108 from the High Power Transmitter 110. The satellite antenna 106 and the High Power Transmitter 110 are fed via connection 112 from the exciter 114 which has the correct signal level and impedance levels to properly operate the High Power Transmitter 110. The exciter 114 is fed via connection 116 from the modulator 118. All of these components are commonly available and used in satellite practice. They are familiar to those skilled in the satellite transmission arts. The Production Facility 104 comprises a switcher 122 connected to the satellite uplink via a connection 120. This connection may be just a short connection from one part of the facility to another or it may consist of a transmission path spanning an arbitrary distance. In some cases it may be a satellite or microwave link as well. If the distances are substantial, fiber optic links may be used. The switcher 122 combines various video and audio signals from a variety of sources under the influence of the control console 136. The control console 136 may be automatic, computer controlled, or manually operated, or operated under a combination of modes depending on the program material or the time of day. The switcher 122 selects between such signal sources as one or more line feeds 124 connecting to one or more external signal sources 126, one or more program playback devices 128 coupled to the switcher 122 by connection 130, one or more commercial playback devices 132 coupled to the switcher 122 by connection 134. The control console 136 influences the program playback device 128 via connection 142. The control console 136 influences the commercial playback device 132 via connection 138. The external signal sources 126 could be other Production Facilities, other satellite links, other remote locations where events such as sporting games, news stories, etc, are covered. The program playback device 128 and the commercial playback device 132 can consist of tape machines, optical or magnetic disk machines, semiconductor or other storage media depending on the technology currently available and practical at the time the invention is practiced. FIG. 2 shows a block diagram of the satellite uplink/Production Facility system of FIG. 1 augmented with precise commercial timing and optional signal time compression/expansion. In FIG. 2a, the facility of FIG. 2, 240, is replicated in multiple locations 242 and 244, to demonstrate the process of synchronization. A common timing source 200 is located in the National Synchronization Center 246 and is distributed by connection 202 to multiple satellite uplink/Production Facility sites. The connection 202 could be a satellite link, wire line links, or a radio transmission. The common timing source 200 could be derived from the National Institute of Standards and Technology, NIST, (formerly the National Bureau of Standards, NBS) or any other source. If a common source 200 is used, the absolute precision of that source is unimportant. The important factor is that all systems are synchronized by the same source. The connection 202 must have insignificant differences in transmission times to the various satellite uplink/Production Facility systems to avoid the introduction of different delays. For example, if connection 202 involved satellite distribution and some satellite uplink/Production Facility system sites received the signal via one satellite link while others required two or more links, the transmission delays to the various sites would be sufficiently different to upset the synchronization and viewers would be disturbed by the differences from channel to channel. At each satellite uplink/Production Facility system site, a Timing Signal Receiver 206 receives the common timing source signal 200 via connection 202 and processes it for further use at the site. In most cases the control console 136 will receive the timing signal via connection 208 from the Timing Signal Receiver 206. The control console 136 then operates as before, but with greater timing precision. An optional Time Compressor/Expander 212 can be used to process the signals from the Program Playback Device 128 by coupling it to the Program Playback Device 128 with connection 210 and coupling it to the Switcher 122 with connection 214. The optional Time Compressor/Expander 212 is coupled to the Control Console 136 by connection 222. An optional Time Compressor/Expander 218 can be used to process the signals from the Commercial Playback Device 132 by coupling it to the Commercial Playback Device 132 with connection 216 and coupling it to the Switcher 122 with connection 220. The optional Time Compressor/Expander 218 is coupled to the Control Console 136 by connection 224. The optional Time Compressor/Expanders 212 and 218 take signals previously loaded into them and play them back at appropriate speeds to precisely fit a time constraint. If the original signal did not fully fit the time allotted, the Time Compressor/Expanders 212 and 218 would play back more slowly to expand the time of playback. Conversely, if the original signal was too long to fit the time allotted, the Time Compressor/Expanders 212 and 218 would play back more quickly to shorten the time of playback. These optional Time Compressor/Expanders 212 and 218 would not be necessary if Program Playback Device 128 and Commercial Playback Device 132 had sufficient variable playback speed features. FIG. 2b shows multiple facilities sources, and receive systems and sites. In an actual application, multiple satellites 100, 180, and 182 may be employed. Many more satellites may be involved. Signals for those satellites may come from multiple facilities similar to the facilities of FIG. 2 and FIG. 2a all under the control of a National Synchronization Center 246. In the figure, multiple Programmers 184, 186,188 convey their signals to a Production Facility 104 which processes the signals according to the methods of this invention under the influence of signals conveyed via connection 202 from the National Synchronization Center 246. The processed signals are conveyed via connection 120 to Satellite Up Link 102 which then uses antenna 106 to send the signals to one or more of the satellites. In this portion of the Figure, the Programmers 184, 186, and 188, the Production Facility 104 and the Satellite Up Link 102 and even the antenna 106 may be located at arbitrary distances from each other and connected by appropriate means. Multiple such facilities are used in the cable industry. Some such as facility 250 are all located in one place. Others such as Facility 252 have the Production Facility and the Satellite Up Link and antenna located in one place and the Programmer 256 at some distance. In some cases, a Programmer 188 may feed more than one Production Facility 104 and 252. In other situations, the Programmer and Production Facility 258 may be combined and the Satellite Up Link 260 located elsewhere. These various components, Programmer, Production Facility, and Satellite Up Link may also have different ownership or may be owned by the same entity. The signals from the multiple satellites 100, 180, and 182 are received by multiple Head End Facilities 262, and 296 for processing and distribution to end users in homes 294. Some homes 298 may receive signals directly from the satellites 100, 180, and 182 in a Direct Broadcast Service. When the Head End 262 receives the signals, multiple antennas 264 are used to feed Satellite Receivers 268 via connections 266. The Satellite Receivers 268 select the appropriate frequency, demodulate the signals and bring them down to a common frequency and then convey them via connection 270 to a collection of Modulators and a combiner 272 where they are put on appropriate television channels and combined into a broadband signal which is conveyed by fiber cable or coaxial cable or twisted pair cable or radio frequency transmission or other means 268 to neighborhoods where subscribers reside. In the neighborhood, the signals are put on distribution lines 290 which bring the signals outside residences 294. A "drop line" 292 conveys the signal to the residence 294. At the Head End, some signals from the Satellite Receivers 268 are conveyed by connections 286 to a Switcher 276 which conveys the signals at appropriate times via connections 274 to the Modulators and Combiner 272. The Switcher may also convey the signals by connection 278 to a Program Playback device 280 for recording and later playback through the Switcher 276 or via connection 282 to a Commercial Playback device 284 for recording and later playback through the Switcher 276. FIG. 3 shows the satellite uplink/Production Facility of FIG. 2 with the addition of an optional single-hop satellite link for delivery of commercials with precise timing. Precise timing of the commercials can also be achieved if they are distributed from a common source via satellite 100 (or another satellite) to satellite receive antennae 300. The satellite receive antenna 300 is coupled to the satellite commercial receiver 304 via connection 302. The received commercial is coupled to the Switcher 122 via connection 306. Alternatively, the commercial could be distributed via land connection 308 consisting of wire, fiber, or radio links. The common distribution of commercials to participating sites ensures their precise timing and avoids the need for other hardware to adjust the timing of the commercials. The timing of the programming may still have to be adjusted. FIG. 4 shows a satellite uplink/Production Facility with precise commercial timing and optional signal time compression/expansion and compliance monitoring and data collection. The Compliance Monitor and Log 400 monitors and logs the timing information coupled via connection 402 from the Timing Signal Receiver 206 and the timing and status of the control console 136 via connection 404 and the timing and status of the switcher 122 via connection 406. These data are then conveyed via connection 408 to a central administrative facility for record keeping and management of the business. An optional monitoring facility 410 can be employed to further ensure compliance with the timing requirements. The optional monitoring facility 410 consist of a satellite receive antenna 412 coupled to one or more satellite receivers 416 via connections 414. A monitoring computer 420 is coupled via connection 418 to the receiver 416 and via connection 424 to the Timing Signal Receiver 422 which is also coupled to the common timing source 200 via connection 202. The monitoring computer 420 accumulates information about the timing of the commercials so that the business can be accurately managed. It will be appreciated that the signals to be monitored can be conveyed by other means such as cable, fiber, or of-air-antenna. Also, multiple Monitoring Facilities may be employed. Furthermore, the Monitoring Facility 410 may be part of the National Synchronization Center 246 of FIG. 2a. FIG. 5 shows a simplified block diagram of a set top box 500 as might be used in the cable industry or any other video or audio provider. Only the elements needed to describe the set top box 500 operation for the purposes of this invention are included. It will be appreciated that there are a variety of ways of implement set top boxes and that the alternate approaches in no way preclude the implementation of the present invention. The description of FIG. 5 is for illustrative purposes only and is not the only method of implementing the invention. The set top box 500 includes an analog descrambler 516 and a digital decompressor 580 and with interruption suppression technology implemented in a Channel Processor 578. The set top box 500 is divided into three major sections. The top section processes analog video and is representative of advanced analog set top boxes currently in use in the cable industry. Similar designs are used by other video signal providers. The center section is representative of the new compressed digital video set top boxes being introduced into cable practice and for Direct Broadcasting Satellite. The bottom section contains the circuitry of this invention. That circuitry plus supporting software in the Microcontroller 550, implement the invention. The Analog Video part of the set top box functions in the usual manner and is well understood by those skilled in the cable arts. Bi-directional cable 502 connects to the input of the set top box and conveys its broadband spectrum to a node 504. The broadband spectrum consists of multiple video, audio, and data signals modulated on carrier frequencies so that they may all be simultaneously conveyed to multiple receive sites. Node 504 allows upstream return signals to be conveyed to the cable 502 and also splits the input downstream signal so that it feeds both the Tuner 506 and the Out of Band Data Extractor 542. The Tuner 508 receives the broadband spectrum from the input cable 502 through the node 504 via connection 506. The Tuner 508 selects a single channel out of the multiple channels presented to it. In the United States, that channel consists of 6 MHz of continuous spectrum. The channel is conveyed by connection 510 to Detector 512 which converts it from a modulated signal on a carrier frequency to a signal ranging from zero Hz to 4.2 MHz. These are frequencies suitable for creating pictures on television display devices and for reproducing audio. That demodulated signal is then conveyed to a Descrambler 516 via connection 514. The Descrambler 516 reconfigures the signals under the influence of control signals conveyed to it by connection 592 from the Microcontroller 550. The video and audio signals are converted into a normal television signal if the subscriber is authorized to receive the programming. If the subscriber is not authorized to receive the signal it remains scrambled and is basically unwatchable. If the signal is from an unscrambled channel, it passes through the Descrambler 516 without change. The descrambled or unscrambled signals are conveyed to a Node 568 which allows these signals to continue on for further processing or accepts signals via connection 586 from the Video & Audio Decompressor 580 in the digital portion of the system. The digital portion is further described below. The audio portion of the signal is conveyed by connection 518 to an external terminal 530 for optional direct connection to the viewers "audio system". The audio signal also conveyed via connection 518 to Remodulator 524 which places the signal on a conventional television channel which is unoccupied in the local environment. Typically, this is channel 2 or 3. The video portion of the output signal from Descrambler 516 is conveyed via connection 536 to a summing Node 532. Node 532 passes the analog signal to the On Screen Display unit 520. If the program was digital rather than analog, the signal would come from Video & Audio Decompressor 580 via connection 534 instead. In either case, it would pass through the On Screen Display unit 520. The On Screen Display unit 520 introduces additional graphics to the video under the influence of signals conveyed via connection 552 from the Microcontroller 550. The additional graphics include text and drawing intended to make use of the services easier and to provide supplementary information. The channel number being watched is inserted into the video image by the On Screen Display unit 520. Most modern TVs and VCRs use On Screen Displays for their channel indication rather than a separate display. This not only saves money but is considered more convenient by many consumers. The video from the On Screen Display unit 520 is conveyed to a baseband video output 528 for those subscribers who have TV receivers or monitors with baseband inputs. The signal is also conveyed by connection 522 to the Remodulator 524 so that it may be impressed upon channel 2 or 3 (or some other locally unoccupied channel) and conveyed to connector 526 for connection to and display by an ordinary TV receiver. The input broadband spectrum frequently contains data on a different frequency from that used to carry the programming. The data may be necessary for the control of authorization of the subscribers programming. It may also contain ancillary data for the subscriber. Electronic program guide information as well as other services are carried in this manner. The other services include messaging services and supplementary information for programming. Signals for educational programs are often conveyed in this manner. This data is conveyed from the input cable 502, thru Node 504 via connection 566 to the Out of Band Data Extractor 542. The Out of Band Data Extractor 542 finds and removes the data from the input spectrum and presents it to the Microcontroller 550 for further process ing via connection 546. Data may also be carried in this manner for the purposes of this invention. If the data used for this invention is included in a out of Band signal, then the Out of Band Data Extractor 542 will convey it to the Data Decoder 57 4 via connection 560. In a similar manner, data may be included in the program signal. This is termed In-Band Data. As one example, this data may be digital data in the Vertical Banking Interval (VBI) of the television picture. The VBI is that period of time during which the picture tube retraces back to the top of the screen. In order to prevent unpleasant diagonal white lines on the screen, the electron beam in the picture tube is turned off (blanked). This "free time" can be used to carry data. There are other portions of the video and audio signal that can be used to carry In-Band Data. The In-Band Data is available in the demodulated signal after Detector 512. It is conveyed by connection 514 to the In-Band Data Extractor 538 which processes the signal and makes available in a suitable form for Microcontroller 550 via connection 540. If the data used for this invention is also included in an In-Band Data signal, then the In-Band Data Extractor 538 will convey it to the Data Decoder 574 via connection 598. If the set top box is used in a two way cable system, the Microcontroller 550 conveys appropriate signals via connection 548 to the Optional Upstream Transmitter 562 which prepares it for transmission up the cable to the head end. The modulated upstream signal is conveyed via connection 564 to Node 504 where it is directed up the cable connection 502. The optional upstream signals can be used to monitor the usage or the operation of the set top box. These signals can also be used for ordering programming or merchandise or responding to questions and requests from the point of program origination. A Remote Controller 584 emits appropriate signals to a Remote Control Receiver 590 for subscriber control of the system. These signals are conveyed by connection 582 to the Microcontroller 550 where they are interpreted and appropriate action initiated. Usually, the remote control signals are infra-red. However, occasionally, radio frequency signals are used. In the distant past, acoustic signals were employed. Future systems may use voice commands. Microcontroller 550 issues control signals via connection 544 to Tuner 508 determining the frequency to be selected. When the viewer issues requests with the Remote Controller 584, they are interpreted by the Remote Control Receiver 590 and conveyed by connection 582 to the Microcontroller 550. If the subscriber requested a channel change, that request is converted into suitable commands for the Tuner 508 and conveyed to it. If the channel is scrambled and the viewer is authorized, the Microcontroller 550 also provides information via connection 592 to the Descrambler 516 which allows it to descramble the signal. Under some circumstances, the Microcontroller 550 takes a different course of action. For example, if the viewer requests a channel which is not authorized, the Microcontroller 550 will not issue instructions to the Descrambler 592 to descramble the signal. It may instead convey signals via connection 552 to the On-Screen Display device 520 instructing it to put an appropriate on-screen message on display instead. That message may instruct the viewer on ways of subscribing to the unauthorized service. The viewer may enter further data via the remote controller 584 which is interpreted by the Remote Control Receiver 590 and conveyed via connection 582 to the Microcontroller 550. The Microcontroller then further processes the information and sends it via connection 548 to the Optional Upstream Transmitter 562 which conveys it in modulated form via connection 564 to Node 504 where it is sent upstream to the program origination site. At the program origination site, the information is processed and if the subscriber can now be authorized, a suitable In Band or Out of Band signal is returned to the set top box 500 with an address code which causes on the appropriate set top box to respond and all others to not respond. If the control is an Out of Band signal, it passes thru cable 502, Node 504, connection 566 to the Out of Band Data Extractor where it is demodulated and presented to the Microcontroller via connection 546. The Microcontroller, now suitably authorized, removes the On Screen message from the On Screen Display unit 520 by sending an appropriate signal via connection 552 and sends a suitable signal to Descrambler 516 via connection 592 instructing it to descramble the signal. If the data was sent via and In-Band Data signal, it would pass thru cable 502, Node 504, connection 506, Tuner 508, connection 510, Detector 512, and connection 514 to the In-Band Data Extractor 538 where it would be demodulated and passed to the Microcontroller 550 via connection 540. Then as in the Out of Band signal case, the Microcontroller 550 would initiate descrambling. Another example involves parental control. If the program is of a nature that parents may not wish children to view it, it may be protected by a parental control code. When the viewer uses Remote Controller 584 to request a parentally controlled channel, the Remote Control Receiver 590 interprets the signal and conveys it via connection 582 to the Microcontroller 550 which has stored a list of the channels and/or programs which are to be parentally controlled. Rather than instructing the Tuner 508 to tune to the parentally controlled channel, the Microcontroller 550 conveys a signal via connection 552 to the On Screen Display unit 520 putting up a message informing the viewer that this is a parentally controlled channel and requesting a code. If the viewer knows the code, it is entered via the remote control 584 thru the Remote Control Receiver, thru connection 582, to the Microcontroller 550. If the code is correct, the Microcontroller 550 will remove the On Screen message by issuing a command via connection 552 to the On Screen Display unit 520 and then issue a channel change instruction via connection 544 to the Tuner 508. If the code is incorrect, either no further action is taken or the on screen message is appropriately modified. Of course, a Power Supply 570 is included to provide operating voltages and currents for the other components of the system. If the signals are compressed digital signals, they are further processed in the Digital Video circuits section of the set top box 500. As before, the Tuner 508 selects a channel of frequencies and conveys it via connection 510 to the Detector 512 which processes the signal and conveys it via connection 514 to the Digital Demultiplexer 558 which is controlled by signals from the Microcontroller 550 via connection 556. Digital Video compression squeezes multiple programs in the same spectrum that was previously used for just one analog channel. A method of choosing just one of those programs is required. The digital bits associated with the desired program are selected by the Demultiplexer 558 and the other bits are discarded. The selected bit stream is then conveyed via connection 594 to the Video & Audio Decompressor 580 where the signals are converted into ordinary analog video and audio signals if the subscriber is authorized to receive them. The audio signals are conveyed via connection 586 to the Node 568 where they then pass to either the output connector 530 or the Remodulator 524. The video signals are conveyed via connection 534 to the Node 532 where they then pass to the On Screen Display unit 520 for further enhancement and then on to the external video connection 528 or the Remodulator 524 for insertion into channel 2 or 3 (or some other suitable channel) and to connection 526. If the program is not authorized, Microcontroller 550 conveys instructions via connection 552 to the On Screen Display unit 520 to put up an appropriate message as described above. The nature of the present invention is such that it can be easily and economically introduced into present set top box practice either thru the addition of a modest amount of additional circuitry and software or thru the modification of already existing circuitry and software. This will now be described. The operation of the set top box 500 is normal except that information pertaining to the channel number displayed by the On Screen Display Generator 520 is governed by the interaction of the channel Processor 578 and the Microcontroller 550 in a manner that implements an improvement of the invention. The Channel Processor 578 stores information about which channels have the same commercial. That information is downloaded into the Channel Processor 578 from the Data Decoder 574 via connection 576. The Data Decoder 574 receives that information either from Out-of-Band Data Extractor 542 via connection 560 or from In-Band Data Extractor 538 via connection 598. The Out-of-Band Data Extractor 542 is coupled via connection 566 to a Node 504 which takes the broadband spectrum on the bi-directional input cable 502 and conveys it to the Out-of-Band Data Extractor 542. This is a commonly used approach in the cable industry for the carriage of data in available portions of the spectrum. Its principle advantage is that the data is continuously available and can have a large capacity. Alternatively and sometimes in addition, an In-Band Data Extractor 538 is used to detect auxiliary data carried in unused portions of the video signal. A common example of this is data carried in the Vertical Blanking Interval (VBI). The VBI is used to carry data such as Teletext or Captioning for the Hearing Impaired. Either method can be used to convey data to the Channel Processor 578 regarding the list of channels which are participating and carrying the same commercial. This list can be downloaded at any time prior to the display of the commercial. When the viewer uses his Remote control 584 to request a channel change, a signal is transmitted to the Remote Control Receiver 590. The signal is conveyed via connection 582 to the Microcontroller 550 and then via bi-directional connection 588 to the Channel Processor. If the newly requested channel is on the previously downloaded list and therefore has the same commercial as the currently displayed channel, the Channel Processor 578 temporarily stores the new channel number and also causes the On Screen Display Generator 520 to display the new number. However, the tuner 508 continues to tune the current channel containing the commercial. This avoids any disruption in the display of the commercial. When the commercial is over, the Channel Processor conveys a signal to the microcontroller 550 via bi-directional connection 588 instructing it to send a signal via connection 544 to the Tuner 508 causing it to go to the new channel. If the channel is digitally compressed, the Channel Processor 578 instructs the Digital Demultiplexer 558 via connection 596 to continue selecting the same commercial while it instructs the Microcontroller 550 via bi-directional connection 588 to send the new channel indication to the On Screen Display 520. This continues until the commercial is completed. Then, the Channel Processor 578 instructs the Microcontroller 550 via bi-directional connection 588 to send signals to the Tuner 508 via connection 544 to go to a new frequency if necessary and the Channel Processor 578 conveys instructions via connection 596 to the Digital Demultiplexer 558 to select the new bit stream for the new program. Alternatively, the instructions conveyed by the Channel Processor 578 via connection 596 to the Digital Demultiplexer 558 could have been conveyed by a different route. The Channel Processor 578 could send instructions via bi-directional connection 588 to Microcontroller 550 which then relays them to the Digital Demultiplexer 558 via connection 556. Either process is acceptable. In the event the subscriber is doing a channel scan and channels which do not include the commercial are scanned, the system can be instructed to retain the selected commercial and not attempt to make a split second presentation from the scanned channel. If the scanning enters a range where multiple channels are not participating, then it may be necessary to display the video on the non-participating channels. Data pertaining to the commercials watched (and other data) can be accumulated in the Channel Processor and then conveyed at appropriate times via connection 572 to the Optional Upstream Transmitter 562 where it is modulated onto a suitable carrier, conveyed via connection 564 to Node 504 and upstream on the cable 502. An alternate embodiment of the invention avoids the storage of lists in the Channel Processor. When the viewer issues a channel change request from the Remote Controller 584, it is conveyed from the Remote Control Receiver 590 via connection 582 to the Microcontroller 550. The Microcontroller 550 may either directly convey the signal to the Optional Upstream Transmitter 562 or convey it via bi-directional connection 588 to the Channel Processor 578 which then conveys it via connection 572 to the Optional Upstream Transmitter 562. The Optional Upstream Transmitter 562 modulates the signal on an appropriate carrier and conveys it via connection 564 to Node 504 which sends it upstream on cable 502. The programming site then determines if the same commercial is present on the current channel and on the newly requested channel. If the same commercial exists on both channels, either an addressed In-Band or an addressed Out of Band signal is sent to the viewers "set top box" 500 where it is appropriately processed and conveyed to the Microcontroller 550 which takes appropriate action. If the same commercial is on both channels, only the channel display is changed. If different commercials are on the two channels, both the display and the Tuner 508 and if digital, the Demultiplexer 558 are changed as well. The Data Decoder 574 consists of logical circuits which determine if In-Band Data or Out-of-Band Data are intended for the Channel Processor 578. If the data is intended for the Channel Processor 578, it is stored in the Data Decoder 574 and at an appropriate time conveyed to the Channel Processor 578 via connection 576. The Channel Processor 578 can be implemented with either specially designed logic or as software in a microcontroller or microprocessor. The economics in effect at the time of implementation will dictate which is the more appropriate approach. Other factors determining the approach taken include whether the Channel Processor 578 is to be added to an existing design which may be at capacity and not be able to absorb these functions or whether the Channel Processor 578 is part of a new design which will allow it to be fully integrated with other functions and more economically accommodated. The Channel Processor 578 consists of Random Access Memory, RAM, Read Only Memory, ROM, and logic and/or computing circuits all commonly available and well understood in the digital circuit design arts. The interconnection of these circuits in forms such as used in this invention are also very well understood. Software to implement these functions is also a commonly understood art. It will be appreciated that the Data Decoder 574 is similar in function and implementation to portions of the Out of Band Data Extractor 542 and the In Band Data Extractor 538. It will also be appreciated that the Channel Processor 578 is similar in function and implementation to portions of the Microcontroller 550. As a consequence, the functions of the Data Decoder 574 can be combined with those of the Out of Band Data Extractor 542 and the In Band Data Extractor 538. Similarly, the functions of the Channel Processor 578 can be combined with the Microcontroller 550.

A satellite uplink/studio system has timing means coupled therewith for precise commercial timing such that prerecorded commercials are simultaneously started with sufficient precision to appear simultaneously to viewers changing channels.

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. patent application Ser. No. 12/361,091 filed Jan. 28, 2009 which claims priority to Japanese Patent Application No. 2008-025237 filed Feb. 5, 2008 each of which is hereby incorporated by reference herein in its entirety. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video playback apparatus and a video display apparatus which reproduce and display an original video in a trick playback mode, such as a fast forward playback mode and a slow playback mode, and also relates to a method for controlling these apparatuses. 2. Description of the Related Art A television (TV) set which can display video at a high frame rate has recently been commercialized for improving a response of moving images. The TV set converts video signals of 60 frames per second (fps) input from a playback device such as a digital versatile disc (DVD) player into video signals of 120 fps by a built-in frame interpolator and displays the video signals on a screen. When the video signals recorded in a DVD is reproduced in a trick playback mode, the DVD player adjusts the frame rate by decimating frames in a fast forward playback mode and by doubling the frames in a slow playback mode. The video signals thus, can be output in a fixed frame rate, regardless of a normal playback mode or the trick playback mode, and it enables any type of display device to reproduce and display the video signals. Japanese Patent Application Laid-Open No. 2001-054066 discusses a video display system which changes decoding processing speed in the fast forward playback mode and the slow playback mode, and rewrites a video random access memory (VRAM) at a different frame rate. Japanese Patent Application Publication No. 2007-528012 discusses a display method which switches a display scan mode in response to the trick playback mode. According to a conventional trick playback method, however, the display image reproduced in the trick playback mode does not always have a high image quality in a case where the video from a playback device that can perform a high frame rate playback is displayed by a display device that can display the video at the high frame rate. FIG. 11 illustrates device setting and a transition of the frame rate in a conventional 2× speed fast forward playback mode. A DVD playback unit 3 reproduces an original video data of 60 fps which is recorded in a DVD by 2× speed fast forward playback, and the original data is converted to playback video data of 120 fps. Since an output video frame rate from a transmission unit 6 is normally fixed at 60 fps, the output video frame rate is decimated and output by a frame doubling/decimating units. Input video data of 60 fps received by a receiving unit 32 in a TV set 31 is converted to the video data with the frame rate of 120 fps by a frame interpolator 34 , and displayed. FIG. 12 schematically illustrates frame images to be displayed. Since the frame images are interpolated after odd-numbered frames of the original video data are decimated, reproducibility of the displayed video is poor. FIG. 13 illustrates the device setting and a transition of the frame rate at a conventional ¼× speed slow playback mode. A DVD playback unit 3 reproduces the original video data of 60 fps which is recorded in a DVD by ¼× speed slow playback, and the original data is converted to the playback video data of 15 fps. Since the video frame rate from a transmission unit 6 is normally fixed at 60 fps, a frame interpolator 4 and a frame doubling/decimating unit 5 are turned on and the interpolated and doubled video data is output. The video data of 60 fps received by a receiving unit 32 of a TV set 31 is converted to the video data with the frame rate of 120 fps by a frame interpolator 34 and displayed. FIG. 14 schematically illustrates the frame images to be displayed. An interpolated frame image processed by the frame interpolator 4 , a doubled frame image processed by the frame doubling/decimating unit 5 , and an interpolated frame image processed by the frame interpolator 34 are inserted between frame images of the original video data. As a result, smoothness of the video to be displayed is lost because three similar frame images continue. SUMMARY OF THE INVENTION The present invention is directed to displaying a high-quality trick playback video by exchanging device information of a playback device and a display device and controlling and associating operations of their respective frame rate conversion units in response to a request for a trick playback. According to an aspect of the present invention, a video display apparatus adapted to be connected to a video playback apparatus having a first frame rate conversion unit configured to convert a frame rate of video data, includes a second frame rate conversion unit configured to convert a frame rate of the video data which is input from the video playback apparatus, and a control unit configured to control and associate operations in the first frame rate conversion unit and the second frame rate conversion unit in response to a request for performing a trick playback of the video data. According to another aspect of the present invention, a video playback apparatus adapted to be connected to a video display apparatus having a second frame rate conversion unit configured to convert a frame rate of input video data, includes a playback unit configured to reproduce video data recorded in a recording media and output playback video data, the first frame rate conversion unit configured to convert a frame rate of the playback video data, and a control unit configured to control and associate operations in the first frame rate conversion unit and the second frame rate conversion unit in response to a request for performing a trick playback of the video data. According to an exemplary embodiment of the present invention, video is displayed with a smooth motion when a recorded video is reproduced in a trick playback. Further features and aspects of the present invention will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments, features, and aspects of the invention and, together with the description, serve to explain the principles of the invention. FIG. 1 is a block diagram illustrating a video playback apparatus and a video display apparatus according to an exemplary embodiment of the present invention. FIG. 2 is a flow chart illustrating processing procedures of the video playback apparatus and the video display apparatus according to the exemplary embodiment of the present invention. FIG. 3 is a table illustrating device information of a DVD player. FIG. 4 is a table illustrating device information of a TV set. FIG. 5 is a flow chart illustrating procedures for generating a device setting table. FIG. 6 is an example of a device setting table. FIG. 7 is a diagram illustrating transition processes of a frame rate in a 2× speed fast forward playback mode according to the exemplary embodiment of the present invention. FIG. 8 is a diagram illustrating transition processes of a frame rate in a ¼× speed slow playback mode according to the exemplary embodiment of the present invention. FIG. 9 is a diagram illustrating a display frame structure in the ¼× speed slow playback mode according to the exemplary embodiment of the present invention. FIG. 10 is a diagram illustrating transition processes of a frame structure in the ¼× speed slow playback mode according to the exemplary embodiment of the present invention. FIG. 11 is a diagram illustrating transition processes of a frame rate in a conventional 2× speed fast forward playback mode. FIG. 12 is a diagram illustrating a display frame structure in the conventional 2× speed fast forward playback mode. FIG. 13 is a diagram illustrating transition processes of a frame structure in a conventional ¼× speed slow playback mode. FIG. 14 is a diagram illustrating a display frame structure in the conventional ¼× speed slow playback mode. DETAILED DESCRIPTION OF THE EMBODIMENTS Various exemplary embodiments, features, and aspects of the invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram of a video playback apparatus and a video display apparatus which can be connected to each other according to an exemplary embodiment of the present invention. A DVD player 1 as a video playback apparatus and a TV set 31 as a video display apparatus are connected to each other via an interface. However, the TV set 31 and the DVD player 1 are not necessarily separate bodies. That is, the DVD player 1 can be mounted in the TV set 31 . A DVD as a recording media recording original video data is inserted into a DVD reading unit 2 , and then a DVD playback unit 3 outputs the original video data recorded in the DVD as playback video data. A user selects a playback operation system using a remote controller, either in a normal playback operation or a trick playback operation (fast forward playback, or slow playback). A remote control signal receiving unit 7 receives remote control signals. A playback control unit 8 performs setting of playback speed of the DVD playback unit 3 , a frame interpolator 4 , a frame doubling/decimating unit 5 , and a transmission unit 6 according to a user operation of the remote controller. Alternatively, a display control unit 38 can perform settings of the playback speed of the DVD playback unit 3 , the frame interpolators 4 and 34 , the frame doubling/decimating unit 5 , and the transmission unit 6 according to the user operation using a remote controller of the TV set 31 . As a communication interface between the transmission unit 6 and a receiving unit 32 , a high-definition multimedia interface (HDMI) can be used. Video data and control commands are communicated between the DVD player 1 and the TV set 31 via the HDMI. The display control unit 38 of the TV set 31 controls the receiving unit 32 , the frame interpolator 34 , and a display unit 35 . A communication unit 9 of the DVD player 1 and a communication unit 37 of the TV set 31 communicate device information and setting details of each unit to each other using a consumer electronics control (CEC) line of the HDMI. The display unit 35 is a display apparatus which is structured with a display panel such as a crystal panel, a plasma display panel, an electroluminescence panel, and can display video at a plurality of display frame rates. FIG. 2 is a flow chart illustrating processing procedures in the DVD player 1 and the TV set 31 . When the DVD player 1 and the TV set 31 are powered on, in step S 51 , the playback control unit 8 of the DVD player 1 communicates with the display control unit 38 of the TV set 31 via the communication unit 9 , and acquires the device information of the TV set 31 . The display control unit 8 of the TV set 31 can communicate with the playback control unit 8 of the DVD player 1 via the communication unit 37 , and acquires the device information of the DVD player 1 . As illustrated in FIG. 4 , the device information of the TV set 31 includes a frame rate that can be received by the receiving unit 32 , a setting of the frame rate which can be changed by the frame interpolator 34 , and a display frame rate at the display unit 35 . Next, in step S 52 , the playback control unit 8 generates a device setting table which describes a device setting that can reproduce the video with the highest quality image at the time of performing the trick playback based on the acquired device information of the TV set 1 and the acquired device information of the DVD player 1 . As illustrated in FIG. 3 , the device information of the DVD player 1 includes a setting of the frame rate which can be changed by the frame interpolator 4 , a setting for frame doubling/decimating which can be executed by the frame doubling/decimating unit 5 , and an output frame rate which can be output by the transmission unit 6 . The device setting table associates operations among the frame interpolator 4 , the frame doubling/decimating unit 5 , and the frame interpolator 34 with each other according to a playback mode of the trick playback. FIG. 6 is a device setting table which describes operations of each block for obtaining a high-quality display image at the time of performing trick playback. The device setting table is stored in a memory unit in the playback control unit 8 or the display control unit 38 . In the device setting table, the operations of each block corresponding to each playback mode such as a normal playback, a fast forward playback (×2, ×4, or more), and a slow playback (×½, ¼, or more) are described. Each block includes a frame rate conversion block (the frame interpolators 4 and 34 , and the frame doubling/decimating unit 5 ), the transmission unit 6 and the receiving unit 32 of HDMI, and the display unit 35 . FIG. 5 illustrates a determination flow in generating the device setting table based on the device information of the TV set 31 and the DVD player 1 . When it is determined in step S 201 that the fast forward playback mode is set, then in step S 202 , the playback control unit 8 turns off the frame interpolator 4 of the DVD player 1 . This is because the playback control unit 8 can increase the frame rate without performing interpolation during fast forward playback. Next, in step S 203 , when it is determined that an upper limit of a frame rate available for transmission is equal to or greater than the output frame rate (60 fps×fast forward playback speed) of the DVD playback unit 3 (YES in step S 203 ), the process proceeds to step S 205 . In step S 205 , the playback control unit 8 turns off the frame doubling/decimating unit 5 and outputs the video data as it is. When the upper limit of the frame rate available for transmission is less than the output frame rate of the DVD playback unit 3 (NO in step S 203 ), the process proceeds to step S 204 . In step S 204 , the playback control unit 8 performs decimating of the video data to obtain the frame rate available for transmission by the frame doubling/decimating unit 5 . The upper limit of the frame rate available for transmission is determined based on a transmission speed of HDMI. In step S 207 , the display control unit 38 of the TV set 31 determines whether to turn on or off the frame interpolator 34 based on the information about frame interpolation which can be executed by the frame interpolator 34 and the display frame rate in the display unit 35 . This operation relates to, for example, the operation of the TV set 31 in a case where the TV set 31 receives the video data of 120 fps at the fast forward playback speed of 2× from the DVD player 1 . When the TV set 31 further executes the frame interpolation to the input video data to convert the frame rate to 240 fps and the display unit 35 can display the video at the converted frame rate, the video can be displayed at higher quality. It is not necessary to further perform the frame interpolation to 240 fps in a case where the TV set 31 receives the video data of 120 fps in the normal speed viewing. The display frame rate at the display unit 35 is determined as described above. Returning to step S 201 , when it is determined that the slow playback mode is set, then in step S 209 , the playback control unit 8 turns on the frame interpolator 4 of the DVD player 1 . It is because the DVD player 1 can improve the frame rate without damaging the image quality during the slow playback by executing the frame interpolation. Next, in step S 210 , when it is determined that a lower limit of a frame rate available for transmission is equal to or less than the output frame rate (60 fps×slow playback speed) of the DVD playback unit 3 (YES in step S 210 ), the process proceeds to step S 211 . In step S 211 , the playback control unit 8 turns off the frame doubling/decimating unit 5 . When the lower limit of the frame rate available for transmission is greater than the output frame rate of the DVD playback unit 3 (NO in step S 210 ), the process proceeds step S 212 . In step S 211 , the playback control unit 8 turns on the frame doubling/decimating unit 5 and sets the frame doubling so that the frame rate available for transmission is obtained. In a case where the playback control unit 8 turns off the frame doubling/decimating units (in step S 211 ), the display control unit 38 of the TV set 31 turns on the frame interpolator 34 in step S 213 . In a case where the playback control unit 8 turns on the frame doubling/decimating unit 5 (in step S 212 ), the display control unit 38 of the TV set 31 turns off the frame interpolator 34 in step S 214 . According to the above described procedures, the device setting table is generated. Returning to FIG. 2 , when the user inputs a request for the trick playback using the remote controller, the play control unit 8 controls and associates the frame interpolator 4 , the frame doubling/decimating unit 5 , and the frame interpolator 34 based on the device setting table. In step S 53 , the playback control unit 8 sets the frame interpolator 4 of the DVD player 1 . The playback control unit 8 turns off the frame interpolator 4 at the time of performing the fast forward playback, while the playback control unit 8 turns on the frame interpolator 4 at the time of performing the slow playback. Next, in step S 54 , the playback control 8 performs the device setting of the frame doubling/decimating units. The playback control unit 8 adjusts the device setting by frame doubling/decimating so as to provide the frame rates that can be transmitted and received by the output unit 6 and the receiving unit 32 . However, this operation lowers the image quality, so that the frame doubling/decimating unit 5 is adjusted to be turned off to the utmost extent. Next, in step S 55 , the playback control unit 8 sets a transmission frame rate for the transmission unit 6 and the receiving unit 32 . In step S 56 , the playback control 8 sets the frame interpolator 34 of the TV set 31 . The playback control unit 8 turns off the frame interpolator 34 at the fast forward playback, while the playback control unit 8 turns on the frame interpolator 34 at the time of performing the slow playback. According to the above settings, the DVD playback unit 3 performs the trick playback based on the request, and the video based on the playback video data is displayed on the screen of the display unit 35 . A specific operation to be performed when the 2× speed fast forward playback is selected is described. FIG. 7 illustrates on-off operations and the transition of the frame rate of each block. The DVD playback unit 3 reproduces the original video data of 60 fps recorded in the DVD at the 2× speed fast forward playback, and the original video data is converted to the playback video data of 120 fps. The frame interpolator 4 and the frame doubling/decimating unit 5 are turned off, and the transmission unit 6 outputs the playback video data of 120 fps. The frame interpolator 34 of the TV set 31 is turned off, and the playback video data is finally displayed as the video at the display frame rate of 120 fps. Since the playback video data of 120 fps is displayed in the display frame of 120 fps without executing the frame interpolation, the playback video data is displayed at the highest quality. A specific operation to be performed when the ¼× speed slow playback is selected is described. FIG. 8 illustrates on-off operations and the transition of the frame rate of each block. The DVD playback unit 3 reproduces the original video data of 60 fps recorded in the DVD at the ¼× speed slow playback, and the original video data is converted to the playback video data of 15 fps. The frame interpolator 4 is turned on while the frame doubling/decimating unit 5 is turned off, and the transmission unit 6 outputs the playback video data of 30 fps. The frame interpolator 34 of the TV set 31 is turned on, and the playback video data is finally displayed as the video at the display frame rate of 60 fps. FIG. 9 schematically illustrates the frame image to be displayed. FIG. 10 illustrates transition processes until the frame image becomes a display frame image. Original video 101 of the DVD is output at slow ¼× speed as a DVD playback unit output 107 , and converted to a frame interpolator output 108 . More specifically, a frame A-B which is generated from frames A and B is interpolated to the DVD playback unit output 107 . Next, the frame image is output as a frame doubling/decimating unit output 109 without changes. Then, the frame image is output as a frame interpolator output 110 . More specifically, a frame A-[A-B] which is generated from the frames A and A-B, and a frame [A-B]-B which is generated from the frames A-B and B, are interpolated to the frame doubling/decimating unit output 109 . In other words, the video is displayed with a smooth motion since the display frame images are structured with the interpolated frames which are not doubling frames. While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all modifications, equivalent structures, and functions.

A video display apparatus adapted to be connected to a video playback apparatus having a first frame rate conversion unit configured to convert a frame rate of video data, includes a second frame rate conversion unit configured to convert a frame rate of the video data which is input from the video playback apparatus, and a control unit configured to control and associate operations in the first frame rate conversion unit and the second frame rate conversion unit in response to a request for performing a trick playback of the video data.

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims domestic priority to commonly owned copending U.S. Provisional Application Ser. No. 62/254,338, filed Nov. 12, 2015, the disclosure of which is hereby incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] The hydrofluoro-olefin 2,3,3,3-tetrafluoropropene (HFO-1234yf, CF 3 CF═CH 2 ) is a low global warming compound with zero ozone depletion potential which finds use as a refrigerant, a foam blowing agent, a monomer for polymers, and many other applications. A number of methods are known in the art for making HFO-1234yf. See, for example U.S. Pat. Nos. 8,975,454, 8,618,340, 8,058,486, and 9,061,957. See also, U.S. Patent Pub. Nos. 2009-0099396 and 2008-0058562. [0003] Another route to HFO-1234yf is the hydrofluorination of 1,1,2,3-tetrachloro-propene (TCP), as disclosed in U.S. Pat. Nos. 8,084,653 and 8,324,436. PCT Publication No. WO 2009/003085 Al describes the preparation of HFO-1234yf via the metathesis of hexafluoropropene (HFP) and ethylene. This process requires the use of an expensive metathesis catalyst in an organic solvent and thus not cost effective for commercial production. [0004] These methods for making HFO-1234yf generally involve multiple steps, by-product formation, and have a low atom efficiency percentage. Atom efficiency percentage is calculated as follows: [0000] (the molecular weight of the desired product) divided by (the molecular weight of the substances formed)×100. [0005] The thermal dimerization of fluoro-olefins has been described in the literature. See, for example, U.S. Pat. Nos. 2,427,116; 2,441,128; 2,462,345; 2,848,504; 2,982,786; and 3,996,301. See also, J. Fluorine. Chem., 2004, 125, 1519; J. Chem. Soc., Perkin I, 1973, 1773; J. Chem. Soc., Perkin I, 1983, 1064. [0006] U.S. Pat. No. 3,996,299 describes a process for the formation of the copolymer produced from vinylidine fluoride and 2,3,3,3-tetrafluoro-propylene. This process involves the cyclodimerization of a perfluoroolefin, such as perfluoropropylene, with a terminal monoolefin, such as ethylene, to produce the cyclic compound1,1,2-trifluoro-2-trifluoromethyl-cyclobutane (TFMCB). The cyclic compound such as TFMCB is then subjected to a thermal cracking operation to produce a mixture of acyclic fluorine-containing olefins, such as vinylidine fluoride and 2,3,3,3-tetrafluoro-propylene, which can be used as monomers and/or comonomers in polymerization reactions. [0007] The '299 patent discloses the cyclodimerization reaction can occur over a very wide range of reaction conditions. For example, the patent indicates that the reaction temperature can be in the range of 200°-600° C., preferably 300°-400° C., and that the reaction time in the range of about 4 to about 1000 hours, preferably 10 to 100 hours. The '299 patent also indicates that the ratio of the monoolefin to the perfluoroolefin usually is in the range of 0.1:1 to about 100:1 preferably 1:1 to about 10:1. [0008] The '299 patent discloses that the thermal cracking of the cyclic compound at temperatures in the range of 500° to 1000° C. and preferably in the range of 600° to 700° C. It is stated that the cracking reaction can be carried out continuously by passage through a heated reactor tube maintaining a contact time in the range of 0.01-10 seconds. [0009] Applicants have come to recognize several problems and disadvantages associated with the formation of HFO-1234yf according to a process as described in the '299 patent. One such problem is that the '299 patent fails to recognize the potential problem in the cracking reaction associated with olefin oligomerization at high temperatures. Other problems are the presence of HFP and ethylene (the starting material) in the cracking products along with other side products, which are not mentioned in the '299 patent. Applicants have come to appreciate that these problems would be exacerbated under many of the dimerization reaction conditions specified in the '299 patent. The final reaction product is thus a complex mixture under the specified reaction conditions, especially with large excess of ethylene to HFP ratios. Another problem is that many of the permitted ratios of perfluorolefin, such as HFP, to the monolefin, such as ethylene, can produce undesirable reaction product results, including unwanted or detrimental by-products and/or poor conversions and/or selectivities. Similar disadvantages associated with unwanted or detrimental by-products and/or poor conversions and/or selectivities are possible within the range of reaction conditions for the cracking reaction. [0010] At least in part as a result of the recognition of these problems with the prior art, applicants have developed new and greatly improved processes that provide significant and unexpected advantages in the production of HFO-1234yf and mixtures of HFO-1234yf and vinylidine fluoride (VDF). SUMMARY OF THE INVENTION [0011] One aspect of the present invention is directed to a process for making HFO-1234yf and/or vinylidine fluoride (VDF) comprising: (a) reacting ethylene with hexafluoropropylene (HFP) in an ethylene:HFP mole ratio of greater than about 1:6 to less than about 1:1.2 for a contact time of not less than about 1 hour and not greater than about 100 hours and at an average reaction temperature of greater than about 250° C. and less than about 400° C. to produce 1,1,2-trifluoro-2-trifluoromethyl-cyclobutane (TFMCB) in a yield of at least about 40% and a selectivity of at least about 75%; and (b) converting said 1,1,2-trifluoro-2-trifluoromethyl-cyclobutane (TFMCB) to (VDF) and/or HFO-1234yf, preferably by cracking, and more preferably in some embodiments by thermal cracking (hereinafter referred to as “pyrolysis”), said TFMCB in a reaction zone for a contact time of less than about 10 seconds and at an average temperature of less than about 850° C. to produce (VDF) and/or HFO-1234yf, preferably both VDF and HF-1234yf and even more preferably in a VDF:HFO-1234yf mole ratio of less than about 1.5:1 and not less than about 0.8:1. [0014] Another aspect of the invention provides a process for forming (VDF) and/or HFO-1234yf comprising: (a) providing a stream comprising 1,1,2-trifluoro-2-trifluoromethyl-cyclobutane (TFMCB); and (b) cracking, and preferably pyrolyzing said 1,1,2-trifluoro-2-trifluoromethyl-cyclobutane (TFMCB) for a contact time of less than about 10 seconds and at an average temperature of less than about 850° C. to produce (VDF) and/or HFO-1234yf, preferably both VDF and HF-1234yf and even more preferably in a VDF:HFO-1234yf mole ratio of less than about 1.5:1 and not less than about 0.8:1. [0017] One preferred embodiment of the pyrolysis reaction according to this aspect of the invention is depicted in Reaction Scheme I below: [0000] [0018] As described herein, one embodiment of this reaction is conducted by introducing into a reaction vessel, preferably into a heated tubular reaction vessel, a stream comprising, and preferably comprising in major proportion by weight, and even more preferably consisting essentially of, TFMCB. According to preferred embodiments the tubular reactor comprises a stainless steel tube placed in a furnace maintained at elevated temperature and passing the TFMCB through the reactor, preferably in a continuous operation, at a contact time of less than about 10 seconds, more preferably less than about 5 seconds, to produce a reaction product stream comprising 1234yf and/or VDF, preferably both. Preferably, the embodiments include a quenching operation to quickly reduce the temperature of the reaction product to halt the pyrolysis reaction, such as for example, introducing the reaction product stream into a cylinder maintained at temperature much lower than the temperature of the heated reaction vessel. In some embodiments no carrier gas (e.g., helium) is present in the reaction stream. The reaction temperatures preferably range from 500° C. to 1000° C., preferably from 750° C. to 850° C. [0019] Although applicants do not intend to be bound by or to any particular theory of operation, it is believed that conducting the pyrolysis reaction in accordance with prior practice, as exemplified for example in the '299 patent, can result poor product yield and/or conversions as a result of, for example, over-cracking of the reactants, which in turn also has the potential disadvantage of resulting in low run times and/or high reactor fouling rates, potentially making such operations not commercially viable. Applicants have unexpectedly found that these and other disadvantages associated with prior operation can be avoided, and substantial and important improvements can be achieved, by operating the pyrolysis reaction within the process ranges described herein. [0020] In certain embodiments, the pyrolysis provides a yield in the range of about 80% to about 90%, based on the amount of VDF and HFO-1234yf together, and preferably in a VDF:HFO-1234yf molar ratio of from about 1.5:1 to about 0.8:1. In certain embodiments, the pyrolysis provides a conversion rate of about 70%, based on the conversion of the starting materials. [0021] In certain embodiments, the pyrolysis is conducted in a batch mode. In certain embodiments the pyrolysis is conducted in a continuous mode. [0022] In certain embodiments the process further comprises a step of separating the mixture of the compounds HFO-1234yf and vinylidine fluoride, using conventional techniques. [0023] The compound 1,1,2-trifluoro-2-trifluoromethylcyclobutane (TFMCB) is a known compound. TFMCB has a boiling point of 68° C. and was used as a component of a cleaning solvent composition in U.S. Pat. Nos. 5,026,499 and 5,035,830, which is incorporated herein by reference. [0024] Methods for the synthesis of this compound are known. See for example, PCT Publication No. 2000/75092, which is incorporated herein by reference and which describes the codimerization of TFE and ethylene to give tetrafluorocyclobutane, and subsequent electrochemical fluorination give perfluorocyclobutanes. The compound 1,1,2-trifluoro-2-trifluoromethyl-cyclobutane (TFMCB) was also synthesized and fluorinated in this publication. [0025] Another aspect of the invention provides improved methods for the preparation of TFMCB comprising: reacting ethylene with hexafluoropropylene (HFP) in an ethylene:HFP mole ratio of greater than about 1:6 to less than about 1:1.2 for a contact time of not less than about 1 hour and not greater than about 100 hours and at an average reaction temperature of greater than about 250° C. and less than about 400° C. to produce 1,1,2-trifluoro-2-trifluoromethyl-cyclobutane (TFMCB) in a yield of at least about 40% and a selectivity of at least about 75%. According to preferred embodiments of this aspect of the invention, the reaction comprises Reaction Scheme II as shown below: [0000] [0026] According to the preferred Reaction Scheme II, the synthesis of TFMCB, comprises the thermal dimerization of hexafluoropropene (HFP) and ethylene in the presence of a polymerization or oligomerization inhibitor. These starting materials are commercially available, and the resulting product is produced with high purity. [0027] In certain embodiments, the reaction is conducted at a temperature in the range of from about 290° C. to 450° C., preferably from about 300° C. to 350° C. [0028] In certain embodiments, the HFP and ethylene are present in the reactor at a molar ratio of from 1:2 to 1:10. [0029] In certain embodiments, the HFP and ethylene are present in the reactor at a molar ratio of from 1:2 to 1:6. [0030] As described above, the reaction mixture preferably includes one or more polymerization or oligomerization inhibitors. Suitable inhibitors include t-butyl catechol and similar compounds. Other well-known inhibitors include terpenes, such as limonene pinene and the like, and the quinone compounds, 1,4-naphtho-quinone, 2,5-di-tert-butyl-hydroquinone, hydroquinone, hydroquinone monomethyl ether, mono-tert-butyl hydroquinone, para-benzoquinone, toluhydroquinone, and trimethyl-hydroquinone; and the like. [0031] In certain embodiments, the oligomerization inhibitor is present at from about 200 ppm to about 3% by weight. In certain embodiments, the oligomerization inhibitor is present at from about 500 ppm to 3000 ppm. [0032] In certain embodiments, the thermal dimerization is conducted for a reaction time in the range of from about one to five hours. [0033] In certain embodiments, at least a portion of unreacted starting materials contained in the reaction product are separated from the reaction product and recycled to the reactor and/or otherwise processed. [0034] In certain embodiments, the reaction product stream contains at least about 92% on a molar basis of TFMCB. In certain embodiments, the product TFMCB is further purified by distillation to greater than about 99.8% purity. [0035] Although applicants do not wish to be bound by or to any particular theory of operation, it is believed that operation of the dimerization reaction according to the preferred operating ranges disclosed herein avoid significant disadvantages that can be associated with conducting such operations according to the prior art, including for example the '299 patent. For example, applicants have unexpectedly found that product yield and/or product selectivity can be dramatically improved by operating the dimerization reaction within the operating parameters disclosed herein, and that operating outside certain of these parameters can cause a dramatic drop-off in conversion and/or yield, or can cause the production of detrimental byproducts. By way of further example, the present inventors have come to appreciate that the conditions which are needed to obtain the improved yield and selectivity of the present invention can result in unwanted and detrimental oligomerization of the reactants ethylene and/HFP. See, J. Polymer Sci., 1981, 19, 741 and J. Am. Chem. Soc., 1958, 842. This problem was not recognized by the prior art, but applicants have found that serious disadvantages can be avoided by taking steps, as disclosed herein, to ensure that substantial oligomerization does not occur in the dimerization reaction. [0036] For example, the present inventors have found that in certain embodiments severe oligomerization of ethylene and/or other unwanted side reactions can occur if polymerization inhibitor is not included in effective amounts, which in certain embodiments is at least about 200 ppm. In addition, the present inventors have discovered that conducting the reaction with the HFP:ethylene ratios described herein can produce the unexpected advantage of substantially eliminating or at least substantially reducing the formation of HFP or ethylene dimers or oligomers and/or accelerating the reaction of HFP-ethylene codimerization. The present inventors have also found that in certain embodiments and ethylene:HFP ratio greater than the preferred amounts disclosed herein can result in a surprising acceleration of the unwanted dimerization/oligomerization reaction(s). [0037] It should be appreciated by those persons having ordinary skill in the art(s) to which the present invention relates that any of the features described herein in respect of any particular aspect and/or embodiment of the present invention can be combined with one or more of any of the other features of any other aspects and/or embodiments of the present invention described herein, with modifications as appropriate to ensure compatibility of the combinations. Such combinations are considered to be part of the present invention contemplated by this disclosure. [0038] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. DETAILED DESCRIPTION OF THE INVENTION [0039] One aspect of the present invention is directed to a process for the formation of a mixture of the compounds HFO-1234yf (CF 3 CF═CH 2 ) and vinylidine fluoride (F 2 C═CH 2 ) by the pyrolysis of a cyclobutane derivative made from ethylene and hexafluoropropene, namely, 1,1,2-trifluoro-2-tri-fluoromethyl-cyclobutane. [0040] Unlike the process taught in U.S. Pat. Nos. 3,996,299 and 4,086,407, in a preferred embodiment no helium carrier gas is used, which reduces the cost and simplifies the purification of the reaction products. [0041] The pyrolysis or cracking of 1,1,2-trifluoro-2-trifluormethyl-cyclobutane (TFMCB) is preferably conducted, preferably continuously, at an average temperature of from about 750° C. to about 800° C. in a suitable reactor (e.g., stainless steel or the like) to afford a mixture of both HFO-1234yf and VDF. [0042] Typically, the thermal cracking of the neat cyclobutane compound in a hot tube reactor gave a mixture of 1234yf and VDF in excellent yield (atom efficiency percentage of about 80% to 90%) with a conversion of rate of about 70%. Approximately 3% to 5% of unreacted HFP and ethylene were observed in the product mixture. If desired, this mixture of compounds may be separated using conventional methods. [0043] Since TFMCB is a liquid (bp 67° C.), it is conveniently added to the reactor via a heated mixer operated at about 100° C., which vaporizes the TFMCB. The tube reactor is first flushed with nitrogen and thereafter, neat liquid TFMCB is introduced to the heated zone at a predetermined flow rate, e.g., via a syringe pump or the like. [0044] For the preparation of TFMCB in the examples, the compounds HFP and ethylene were mixed in a stainless cylinder reactor with a molar ratio of 1:2 to 1:10, preferably, 1:2 to 1:6, along with from 200 ppm to 3% of one or more oligomerization inhibitors, preferably 500 ppm to 3000 ppm, and heated to 250° to 550° C., preferably 290° to 400° C. for designated times (e.g., one to five hours). [0045] Unreacted starting materials (HFP and/or ethylene) were recycled into a separate container and recycled. The final TFMCB product was decanted from the reactor with greater than 92% purity. Distillation through a column gives greater than 99.8% pure TFMCB. [0046] The process can be carried out either continuously in a hot tube flow system or batch wise in a pressure vessel and the separation of products can be simultaneously or in separate steps. In general, the reaction can be performed sub-atmospherically, atmospherically, or super-atmospherically, e.g., within a pressure range of from 0.1 atm to 1000 atm. [0047] It should be noted that during the pyrolysis of TFMCB in the examples, both HFP and ethylene were formed, each generated at about 3% to about 5%, between temperatures ranging from 500° C. to 900° C. This ratio did not change, even when changes were made to the pyrolysis conditions, including: temperature, contact time, and the presence or absence of carrying gases. This discovery was surprising in view of the teachings of the '299 and '407 patents discussed above, which disclosed no HFP and/or ethylene formation in the pyrolysis process. EXAMPLES [0048] The invention is further described by the following illustrative examples, which are not to be construed as limiting the scope of the invention. Example 1 Pyrolysis of TFMCB [0049] Pyrolysis of distilled TFMCB (495 g, 99.6%) was carried out in a heated stainless pipe reactor in a furnace (see Table II). The reactor was heated to and maintained at 800° C. for 30 minutes to equilibrate and was flushed with nitrogen. Liquid 1,1,2-trifluoro-2-(trifluoromethyl)-cyclobutane was introduced to the heated zone (100° C.) with a programmed syringe pump. [0050] Once the flow of cyclobutane was started, the nitrogen flow was switched off and the pyrolysis was conducted in a continuous mode. The resulting pyrolysis products were collected in a cooled 1 gallon stainless steel cylinder. GC monitoring of products were done at the beginning and end of the reaction. Details are summarized in Table I below: [0000] TABLE I Scale Up Summary Item Description Reactor Stainless steel (0.375″ × 12″); Volume of heated zone = 10.85 cm 3 Amount of 495.5 g (99.6% GC) cyclobutane used Temperature 800° C. Duration of 7.83 h pyrolysis Flow rate 0.74 mL/min (liquid), 130 mL/min (vapor) (or 1.03 g/min) Total products 485.5 g collected Mass balance Mass loss = 495.5 − 485.5 = 10 g (2%) (Recovery = 98%) Collection 1 gal SS cyl (~200-300 psi at RT); cooled by Liq N 2 vessel/pressure while collecting. Contact time 5 sec [CT = Volume of heated zone cm 3 /vapor (CT) flow rate in sccm] Conversion 70% Yields 1234yf (157.2 g, 81%); VDF (105.9 g, 97%) Conditions: temperature range ~700°-850° C.; Contact time ~1 to 60 sec range. [0051] As shown in Table I, the laboratory scale reactor was made from stainless steel and had dimensions of 0.375 inches in diameter and a length of 12 inches, providing a heating zone of 10.85 cm 3 . As indicated, the flow rate of the TFMCB provided a contact time of 5 seconds for the pyrolysis reaction. The collection vessel was also made from stainless steel and was cooled with liquid nitrogen during the collection of the reaction product mixture. [0052] For production purposes, the reactor will be much larger, using suitable constructions materials for conducting the pyrolysis reaction on much greater amounts of TFMCB. Reaction temperatures may vary from those employed in the laboratory scale reactor. It is anticipated that the product composition of 1234yf/VDF to HFP/ethylene will not change, but the TFMCB conversion will be affected by changes in the operational temperatures. No carrier gas is expected to be used in a production plant. Finally, in production processing, the collection vessel will be much larger, and cooling will be provided by alternate means, such as cold water. In a production plant, it is anticipated that the product gas out of the reactor would be compressed into a pressurized storage vessel before distillation or further processing. Comparative Examples 1A & 1B [0053] 1A. The purified TFMCB (3.0 g) from Example 3 was passed through a heated stainless tube reactor at 800° C. at 0.5 ml/min. The reaction tube had a diameter of 1.5 cm with a reaction zone length of 13.0 cm, which was filled with 6.8 g Inconel 625 mesh. The contact time with helium carrier gas of 66.7 ml/min was 14.1 sec, and 3.0 g of product gas was collected. GC analysis showed 3.8% ethylene, 48.7% VDF, 3.3% HFP, and 44.2% 1234yf. [0054] 1B. The reaction temperature was lowered to 750° C., 3.79 g of TFMCB was passed through the tube at 32.4 sec contact time. 3.78 g of product was recovered. GC analysis showed 3.8% ethylene, 48.9% VDF, 3.2% HFP, and 44.1% 1234yf. Example 2 [0055] A number of reactions were carried out at various temperatures and contact times. Typically, the reactions were carried out by passing neat vaporized 1,1,2-trifluoro-2-(trifluoromethyl)-cyclobutane through a stainless tube/pipe reactor placed in a heated furnace as shown in FIG. 1. These results are shown below in Table II. [0000] TABLE II Pyrolysis of neat 1,1,2-trifluoro-2-(trifluoromethyl)cyclobutanes cyclobut. Flow rate Products -mixture Feed Liq. Flow Vap Flow Vol %* by GC Run # 41923- T (° C.) Used (g) (mL/min) (mL/min) CT (sec) Ethylene VDF HFP 1234yf Feed Others 11** 32-4 700 31.80 0.20 35.41 18.4 5.01 60.17 2.29 30.18 0.05 2.3 12 33-1 750 4.78 0.76 133.67 4.9 3.72 48.74 3.23 42.12 1.68 0.51 13 33-2 800 5.23 1.25 219.38 3.0 3.69 46.48 3.09 40.54 5.76 0.44 14 33-3 750 3.93 0.94 164.85 3.9 3.63 47.27 3.18 41.52 3.83 0.57 15 33-4 750 5.45 1.20 211.03 3.1 3.68 45.93 3.15 40.88 5.9 0.46 16 33-5 750 4.32 0.78 135.91 4.8 3.69 47.58 3.29 43.02 0.02 2.4 17 33-6 800 3.97 0.67 117.55 5.5 3.8 48.64 3.29 43 0.68 0.59 18 33-7 800 2.98 0.53 93.75 6.9 3.68 48.23 3.31 43.78 0.21 0.79 *volume % based on cailbration by analytical dept. Tube Reactor: SS tube; ⅜″ diameter, volume of heated zone 10.85 cm 3. **Done at 31.8 g scale and products collected 32 g in a cylinder. [0056] As shown in Table II, the ratio of VDF to HFP was relatively constant and there remained about 2-5% of unreacted HFP and ethylene. Example 3 Production of TFMCB [0057] In a 1000-mL stainless steel cylinder was charged with 0.6 g t-butyl catechol, the cylinder is evacuated with nitrogen three times. Next, 52.0 g of HFP and 11.6 g of ethylene (mole ratio 1/1.19) were condensed into the cylinder. The cylinder was heated to 242° C. to 250° C. for 72 hours, and the inside pressure dropped from 600 psi to 500 psi at the end of reaction. Unreacted HFP and ethylene were recovered in a separate cylinder (39.6 g), and the product of 19.6 g was withdrawn from the reactor by vacuum. GC analysis showed 96.58% pure TFMCB. Example 4 Production of TFMCB [0058] A 2-L stainless cylinder was charged with 1.01 g of t-butyl catechol, and the cylinder is evacuated with nitrogen three times. Next, 50.0 g of HFP and 56.5 g of ethylene were condensed into the cylinder. The cylinder was heated to 320° C. to 329° C. for one hour, and the inside pressure dropped from 700 psi to 500 psi at the end of reaction. Unreacted HFP and ethylene were recovered in a separate cylinder (75.8 g), and the TFMCB product (29.4 g) was decanted from the reactor. [0059] GC analysis showed 94.34% purity (46.2% yield based on HFP). Further distillation through a column gave 99.8% pure 1,1,2-trifluoro-2-trifluoromethyl-cyclobutane (TFMCB), 1 H-NMR (CDCl 3 ) 2.62 ppm (m, 1H), 2.45 ppm (m, 2H), 2.24 ppm (m, 1H); 19 F-NMR (CDCl 3 ) −80.70 ppm (dt, J=9.3, 2.5Hz, CF 3 ), −101.0 ppm (dm, J=212.9Hz, 1F), −114.73 ppm (dtm, J=211.9, 16.2Hz, 1F), −176.37 ppm (m, 1F). Example 5 TFMCB Production [0060] A 2-L stainless cylinder was charged with 1.10 g of t-butyl catechol, and the cylinder is evacuated with nitrogen three times. Next, a calculated amount of HFP and ethylene were condensed into the cylinder. The cylinder was heated to designated temperature for various time periods. The results were listed in Reaction Table III below. [0000] Reaction Table III HFP/ Ethylene Temperature/° C. TFMCB Yield % Product Entry ratio (time/h) (based on HFP) selectivity % 1 1.05/1.0   250 (72 h) 15.4 96.6 2  1/1.19 242 (72 h) 26.8 96.6 3  1/1.48 238 (120 h) 30.5 95.0 4  1/1.97 256 (72 h) 39.6 97.6 5 1/3.0 350 (19 h) 89.6 77.4 6  1/3.35 375 (4 h) 77 74.8 7 1/3.0 400 (1.2 h) 110% yield (some 58.4 oligomer of ethylene) 8 1/0.9 400 (1 h) 69 56.9 9 1/3.0 365 (3 h) 90.8 84.8 10 1/3.0 370 (1.5 h) 92.9 78.0 11 1/3.0 320-330 (5 h) 97.9 91.4 12  1/6.17 320-331 (1 h) 66.8 94.1 Example 6 TFMCB Production [0061] A one gallon stainless cylinder was charged with 60 mg of t-butyl catechol (200 ppm), and the cylinder is evacuated with nitrogen three times. Next, 140.7 g of HFP and 159.0 g of ethylene (mole ratio 1/6.05) were condensed into the cylinder. The cylinder was heated to 320° C. to 329° C. for one hour, and the inside pressure dropped from 800 psi to 600 psi at the end of reaction. Unreacted HFP and ethylene were recovered in a separate cylinder (174.5 g), and the product of 121.7 g was decanted from the reactor. GC analysis showed 78.10% of TFMCB, and 21.40% of side products from ethylene oligomers by GC and GCMS analysis. [0062] As used herein, the singular forms “a”, “an” and “the” include plural unless the context clearly dictates otherwise. Moreover, when an amount, concentration, or other value or parameter is given as either a range, preferred range, or a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions within the range. It is not intended that the scope of the invention be limited to the specific values recited when defining a range. [0063] From the foregoing, it will be appreciated that although specific examples have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit or scope of this disclosure. It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting, and that it be understood that it is the following claims, including all equivalents, that are intended to particularly point out and distinctly claim the claimed subject matter.

Disclosed is a process for the formation of a mixture of the compounds 2,3,3,3-tetrafluoropropene (1234yf) and vinylidine fluoride, comprising pyrolyzing 1,1,2-trifluoro-2-trifluoro-methyl-cyclobutane under conditions effective to produce a reaction product comprising 1234yf and vinylidine fluoride in a 1234yf:vinylidine fluoride molar ratio of from about 0.5 to about 1.2.

This application claims the benefit of U.S. Provisional Application No. 60/134,871, entitled “Private Dialing Plan for Voice on a Packet-Based Network,” filed on May 19, 1999, and of U.S. Provisional Application No. 60/152,045, entitled “Private Dialing Plan for Voice on a Packet-Based Network,” filed on Sep. 2, 1999, the subject matter of which is incorporated herein by reference. BACKGROUND OF THE INVENTION 1) Technical Field This invention relates generally to Internet Telephony, and more specifically to telephone dialing protocols. 2) Discussion of Prior Art In conventional telephone systems, telephone numbers are a series of signaling or identifying digits that are used for a variety of purposes. A common use is dialing a telephone number corresponding to a telephone that a caller wishes to reach. Other uses include various telephone identification roles (such as caller ID or call-returning services) or for billing a call to a particular telephone account. A standard plan for assigning telephone numbers, such as the North American telephone numbering plan, is generally used as the basis for assigning telephone numbers for the Public Switched Telephone Network (PSTN). In conventional telephone service, a dialing plan refers to the calling methods, shortcuts and services which a caller selects based on the presence or absence of special digits or symbols (#,*) which are appended to the assigned telephone number or used in place of the telephone number. For example, with conventional telephone service, calls outside the local area code are dialed starting with a “1,” international calls are dialed starting with “011,” and custom calling services such as call return, call forwarding or speed dialing of stored telephone numbers are often selected by dialing shortcuts consisting of one or two digits and a symbol. Internet Telephony bypasses portions of the PSTN and instead routes telephone calls over the Internet, typically avoiding long distance telephone charges. Previously, Internet Telephony required users to master a complex set of information and have a certain familiarity with Internet Protocol (IP) addresses, nickname servers, and URL terminology. This unfamiliar and sometimes arcane set of access methodologies impeded the growth of Internet Telephony because everyday consumers found it excessively complicated compared with traditional telephony. The most commonly-used technology for Internet Telephony is NetMeeting, developed by Microsoft. NetMeeting requires two access methodologies for users to find and connect to each other. The first is for a user to log onto a series of servers called ILS servers and wait for the correct server to be explicitly identified by the e-mail address of the other party. Once the e-mail address is displayed, the user can click on the address link that will send the other party a message requesting that they accept the telephone connection. On the surface this seems uncomplicated, but increasing numbers of NetMeeting users keep the ILS servers too busy for new connections. Hence, there is no way for an entering user to connect with another user until someone leaves the ILS server, thus allowing access and subsequently a connection. NetMeeting's second access methodology for using Internet Telephony further confounds users. A connection must be established by entering the other party's IP address in order to notify them that the caller would like to make a telephonic connection. The major impediment to making a successful connection using this method is that some dial-up users have a different IP address each time they log in. Casual Internet users must master of a complex set of utilities beyond their typical competency just to look up their own current IP address. Even if a calling user can determine his correct IP address, it must be relayed to the called user. This requires making a telephone call or sending an electronic mail message, which tends to defeat the utility of Internet Telephony. There is, therefore, a need to overcome the above-cited shortcomings of today's Internet Telephony. SUMMARY OF THE INVENTION The present invention makes Internet Telephony as simple to use as a conventional telephone. The invention permits simple, telephone-like numbers to be used for Internet Telephony. The invention helps make Internet Telephony more universal, and provides users a robust system that is both readily available and easily understandable. With the dialing plan of the invention, the telephone number plans and dialing plans of conventional telephone systems are expanded and modified to be well-suited to an Internet-based system. The dialing plan of the present invention uses a signaling protocol such as Q.931 to establish, maintain and release switched connections over a packet-based network. The dialing plan uses conventional telephone numbers as a basis for identifying both the calling party and the called party. Database search keys based on conventional telephone numbers of dialing plan members are used to access various plan database information, such as the user's IP address and any optional services or features available for that member. The invention herein will be called the ZeroPlus dialing plan. After users have registered their conventional telephone numbers in the ZeroPlus system, users may make telephone calls on-net to on-net, off-net to on-net, on-net to off-net, and off-net to off-net. The ZeroPlus number is user-specific, and, once assigned through the ZeroPlus system, becomes the user's permanent Internet telephone number for ZeroPlus calls. Registered users may use a conventional telephone to call a ZeroPlus Internet Telephony gateway. Once connected to that number, members are prompted for a Personal Identification Number (PIN) code, enabling the off-net call. Registered users who are away from a computer can simply dial either a local direct-dial telephone access number for ZeroPlus, if available, or, for a nominal additional charge, dial a 1-800 number. This private dialing plan is called “ZeroPlus,” referring to the fact that on-net calls are placed by dialing “0” plus a conventional telephone number. Adding to this simplicity is that user's Internet Telephone numbers are based on one of the user's normal telephone numbers. Not only is the number easy to use and remember, it is assigned to a respective user permanently for his or her exclusive use on the ZeroPlus system. Consequently, users can contact each other without having to remember a new number, nickname, IP address, or e-mail address as in other Internet Telephony methods. The primary difference between using a traditional telephone number and an Internet telephone number according to the invention is that when an on-net member who is logged onto the ZeroPlus gateway dials an on-net counterpart, “0” plus the number are dialed as opposed to the traditional “1” plus the number dialed for traditional long distance telephone calls. Placing and receiving a ZeroPlus call either on or off the Internet is simple and transparent for the user, requiring no special training or technical competency. In so far as possible, the ZeroPlus invention has a user interface that closely resembles a conventional telephone system. When a ZeroPlus call is placed to the IP address of an on-line destination computer which has the ZeroPlus client installed and running, the destination computer will generate an audible ring. The call originator will hear a “ringback” sound analogous to that heard on a traditional telephone network. The ID of the current calling party will be passed to the computer of the called party. The called party can choose to answer the call by “picking up” the incoming call much like a normal telephone call, if the current status of the data network permits. If the called party is not on-line or does not have the ZeroPlus client launched, then the calling party will hear a “fast busy” sound, indicating that the party is not currently on-line, again emulating the traditional telephone network. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an end-to-end diagram of the private dialing plan network; FIG. 2 shows several of the dialing sequences used in the plan; FIG. 3 is a diagram of activities associated with a simple PC-to-PC call; FIG. 4 shows the Gatekeeper Message format; FIG. 5 shows the Gatekeeper Request Message Information Elements format; FIG. 6 a shows the Gatekeeper Confirmation Message Information Elements (Section 1) format; FIG. 6 b shows the Gatekeeper Confirmation Message Information Elements (Section 2) format; FIG. 7 shows the Gatekeeper Rejection Message Information Elements format; FIG. 8 shows the Admission Request Message Information Elements format; FIG. 9 a shows the Admission Confirmation Message Information Elements (Section 1) format; FIG. 9 b shows the Admission Confirmation Message Information Elements (Section 2) format; FIG. 10 shows the Admission Reject Message Information Elements format; FIG. 10 shows the Authorizing Request Message Information Elements format; FIG. 12 shows the Authorizing Confirmation Message Information Elements format; FIG. 13 shows the Authorizing Rejection Message Information Elements format; FIG. 14 a shows the End of Call Message Information Elements (Section 1) format; FIG. 14 b shows the End of Call Message Information Elements (Section 2) format; FIG. 15 shows the End of Call Ack Message Information Elements format; FIG. 16 shows the Bandwidth Request Message Information Elements format; FIG. 17 shows the Bandwidth Confirmation Message Information Elements format; FIG. 18 shows the Bandwidth Reject Message Information Elements format; FIG. 19 shows the FaxCall Message Information Elements format; FIG. 20 shows the GK Trunks Busy Message 0x4E Information Elements format; FIG. 21 shows the GK Trunks Busy ACK Message 0x4F Information Elements format; FIG. 22 shows the GK Trunks Busy ACK Message 0x4E Information Elements format; FIG. 23 shows the GK Trunks Unbusy Message 0x4C Information Elements format; FIG. 24 shows the GK Trunks Unbusy ACK Message 0x4D Information Elements format; FIG. 25 shows the Heartbeat Message Information Elements format; FIG. 26 illustrates PC-to-PC Forward Unconditional. FIG. 27 is a diagram of activities associated with a forward on busy PC-to-PC call; FIGS. 28 a and 28 b are a diagram of activities associated with a forward on no-answer PC-to-PC call; FIG. 29 is a diagram of activities associated with a forward on no-response PC-to-PC call; FIGS. 30 a and 30 b are a diagram of activities associated with call waiting during a PC-to-PC call; FIGS. 31 a , 31 b and 31 c are a diagram of activities associated with a blind transfer during a PC-to-PC call; FIGS. 32 a , 32 b and 32 c are a diagram of activities associated with a consultative transfer during a PC-to-PC call; and FIG. 33 is a diagram of activities associated with a telephone-to-telephone call. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS As shown in FIG. 1 , ZeroPlus has a unique multi-access architecture. Calls are managed by Internet “gatekeepers.” Users can make telephone connections to or from Internet-based computers 103 , 157 and 159 , and also make connections to or from conventional analog telephones 101 and 155 . For illustrative purposes it is assumed that user computer A 103 initiates the call, and user computer B 157 or user computer C 159 receives the call. The roles of caller and receiver can be interchanged among these user computers. A ZeroPlus gatekeeper 115 A receives ZeroPlus on-net calls over the Internet or another network from an initiating user computer A 103 , or over a telephone line through the PSTN from an initiating conventional telephone 101 . The gateway converts the analog telephone signals into data packets for transmission on the network. Gatekeeper 115 determines exactly how to route the call through either Internet 129 , or some combination of conventional telephone networks. A call directed to an on-net computer IP address is routed through Internet 129 to the destination user computers B 157 or C 159 . A call directed to an off-net conventional telephone is routed from the Internet through a regional gateway 131 to one of several regional or local telephone carrier destination “hubs” 143 , and then to the receiving conventional telephone 155 . Traditional telephone networks require large, complex business and technical departments whose job it is to add and connect new users and to bill existing users. The ZeroPlus system allows new users to be rapidly connected to the system by logging onto the Internet and completing an on-line form. This information is then stored in the ZeroPlus database where it can be retrieved to verify assigned user telephone numbers, define a user profile and generate on-line billing by matching usage with user data stored in the database. This eliminates much of the workforce typically required in traditional telephony, significantly reducing the cost of user acquisition and maintenance. On a traditional telephone network, users are not connected until a technician receives the customer information on a work order and determines and implements the required connections to the telephone network. This often involves a delay of days or weeks. ZeroPlus users are given immediate access to the ZeroPlus system by virtue of its ability to store registration data, to interact in real time with the system database and to immediately assign and validate a telephone number. Upon completion of the new user processing, users are immediately e-mailed a personal PIN code so they can begin using the service. Provided they have ZeroPlus software loaded and launched on their systems, have entered their user access number, and are allowed to make the call by the gate keeper, ZeroPlus users have immediate access to any on-net ZeroPlus user computer or off-net PSTN telephone number. Conventional telephones usually connect to the PSTN through a physical connection made between a set of copper wires and a Class 5 switch at the PSTN central office. On the ZeroPlus network, users are connected via an analog modem, cable modem, Digital Subscriber Line (DSL) modem, Integrated Services Digital Network (ISDN) modem, 802.11 wireless modem, or any other digital network access that is now, or in the future will become, available. An important benefit of the ZeroPlus telephone numbering scheme is that, through the use of a Primary Rate Interface (PRI) digital gateway and the ZeroPlus numbering scheme, every digital call center switch and Integrated Voice Response (IVR) system in existence can route ZeroPlus calls. This means that call centers can benefit from their existing investment in call center technology to route calls from the PSTN. Unlike competing systems that use nicknames and e-mail addresses, when ZeroPlus calls are received, existing switches, PBX, or IVR systems can be configured to route ZeroPlus calls to call center agents just like calls that have originated from the PSTN. Signing up for ZeroPlus service is simple and user friendly. New ZeroPlus users visit the ZeroPlus website to sign up and initiate service. A Registration page collects information about customers to create a database of user and routing information. During the sign-up process, a sequence of messages is displayed to the user. The various messages and user interfaces described herein are illustrative examples of how the sign-up process is conducted. After potential users request an Internet Phone number, a legal contract appears which the registrant is asked to carefully consider and either accept or decline. At the end of the contract, two buttons appear, inviting the registrant the option of indicating “I accept” or “I decline.” After accepting, the first field entered will be the user's e-mail address. After inputting the e-mail address, a search is done to ensure that the entered e-mail address does not already have an assigned a phone number. If it does, the user will be notified of the ineligibility for a new ZeroPlus telephone number for that entered e-mail address. Otherwise, the process will continue. Fields are provided so that the customer can input: First Name Last Name Address 1 Address 2 City State (pull down selection menu) Zip Code Home Phone Number Password (at least eight characters) Entry for two friends or business acquaintances who should be contacted regarding the service. An e-mail will automatically be generated to those e-mail addresses, such as, “first name, last name has asked us to inform you that he/she has just received his/her Internet Phone Number from www.ZeroPlus.com. If you wish to talk to first name for free, whenever online, please visit us and get your own ZeroPlus Number!” After inputting the information, two buttons appear at the end of the fields, one for “Give Me My Internet Phone Number” and the other for “Clear Fields.” After the user has submitted the customer information, the service searches the database to verify that the requested number has not been previously registered. If it has not, the service responds by offering the customer the desired telephone number, which displays a screen, for example, which says, Your new Internet phone number is “0+home phone.” Do you want to keep this number or would you like us to offer another one? If you wish to select another number, it must start with 0+XXX as the first four numbers. A “Keep this number” or “Propose another number” button appears at the bottom of the page. If a user wants to propose a special telephone number, the user is limited to telephone numbers within their current area code. If the person wants to select another number, a screen appears that says, “I wish to have the following Internet phone number:” The screen should show 0+XXX-___ ____, where the last seven digits can be selected by the user, and the XXX is their current area code. After the information has been entered, two buttons appear at the end of the fields, one for “Submit my Internet telephone number” and the other for “Clear fields.” The service searches for the number, and if it's available, tells the user: Congratulations! Your new Internet telephone number is O+XXX-___ ____. Please write it down. If the requested number is not available, the program scrolls through the number database until it finds the next available sequential number, and offers that number to the user: The number you requested is not available. The next closest number is 0+XXX-___ ____. Would you like to keep this number? “Keep this number” and “Propose another number” buttons appear at the bottom of the page. This process continues until the user has chosen a permanent Internet telephone number. Some numbers will be blocked by this system. If a customer requests an 800, 888, 100, 200, 300, 400, 500, 600, 700, 877, or 900 number, a screen appears indicating: The 0+___ ____number you requested has been reserved for the holder of the existing telephone number. If you or your company own this existing number and wish to use it as your Internet phone number, please call us at 1-800-___ ___ — Two buttons should appear, saying “Propose another number” or “Back to home page” sending the person back to the original link. The final screen for completion asks whether the user wants his or her number listed in the 0+directory (“White Pages”). The user selects one of three choices: “I wish to have my Internet telephone number listed in the 0+directory, along with my name, city, state, and country.” “I wish to have my Internet telephone number listed in the 0+directory, along with my name only.” I do not wish to have my Internet telephone number listed in the 0+directory The final screen also provides users with the option be notified of additional features that are available from the ZeroPlus service. The customer selects one of two choices: “Please notify me by e-mail when new ZeroPlus services are available” “Do not notify me when new services are available.” In addition to a discrete telephone number, each user will be required to have a unique nickname, which is equivalent to an e-mail address. The user should be able to propose a nickname, find out if it has been taken, and if it has, have the opportunity to propose another nickname. The screens are developed similarly to those listed under “ZeroPlus Number Proposal.” After the user has selected their Internet telephone number, he/she will automatically be able to download the client GUI. Any system requirements will be listed, and a button will be clicked to “Downloàd 0+Software.” As this information is collected and logged into the database, a directory system enables users to look up a person's Internet telephone number on ZeroPlus' “White Pages” by inputting names, addresses, city, state, etc. When for example, user computer A 103 logs in, it notifies the gatekeeper of its IP address. Each gateway accepts calls that are routed to it based on the routing tables that are set up on the gatekeeper. Every time an administrator adds a new gateway, the routing tables must be updated to ensure that the gateway will handle all PSTN-bound calls in a particular set of area codes. The gateway will only handle calls that the administrator has routed to it. If a ZeroPlus user dials a local PSTN to place a call at least partially routed over the Internet, he or she will be greeted by a voice asking for the ZeroPlus number followed by the PIN Code. Once the caller enters that information and press the pound (#) key, the caller will be asked for the number that they wish to call. At this point they are given the option of dialing either zero (0) plus the number (e.g. “0 301 601 0000”), or one (1) plus the number (e.g. “1 301 601 0000”) followed by the pound (#) key. If the user dials a ZeroPlus number the gatekeeper will be contacted and provide the IP address of the ZeroPlus member's personal computer (PC). If the leading number dialed is “1,” the gatekeeper provides the IP address of the gateway responsible for terminating calls to that area and city code. One plus numbers' routes are determined by the administrator's entry into the routing tables. ZeroPlus numbers are routed according to the IP address assigned by the ISP when the user logged into the ISP's service. A dialed number is converted into an IP address by a simple process. The caller enters zero (“0”) plus a ten digit telephone number into a client ZeroPlus application by either of two methods. One is by clicking the number buttons on the application GUI which simulates the touch-tone pad on a standard telephone. The other method is to use the numbers on the computer keyboard to dial the desired telephone number. Either method assumes that the user has established a network connection and launched the ZeroPlus client application. Once the telephone number of the called party is entered into the application by either of the two methods above, the user can either press the <enter> key on the keyboard or click the “Talk” button on the ZeroPlus GUI. This action initiates a message, with the called party's telephone number and the requested current IP address, to the gatekeeper 115 . The gatekeeper will look up the called party's telephone number on the database server and, using data therein, determine the current or last known IP address for the called party's telephone number. The gatekeeper sends a message with the called party IP address back to the calling party's client. At this juncture, the calling party's client launches the standard call setup messages directly to the called party's IP address. If the called party is online, the client will respond in kind with the standard setup message responses and, once negotiated, the voice session will be opened in both directions. If the called party is not online and has call forwarding engaged, the calling party's client will attempt to forward the call based on forwarding information sent when it first requested the number translation. Accordingly, FIG. 2 shows an access dialing sequence 201 dialed by a user to connect to the plan Internet gateway, and sequences 211 and 221 , used to connect with the call recipient. An on-line computer accesses the gateway by dialing sequence 201 beginning with element 203 , which is a leading “0” digit, followed by the caller's registered ZeroPlus Internet telephone number 205 and a corresponding user PIN code 206 . After sequence 201 gains access to the gateway 115 , the caller can place calls using sequence 211 to obtain an on-net computer-to-computer call. To complete a desired connection, the gatekeeper 115 accesses a database (not shown) which tracks the IP addresses corresponding with the destination number. The destination number selected by the calling user is then associated with the IP address of the destination computer 157 . Alternately, an on-net caller can use sequence 221 to place a call to an off-net conventional telephone 155 . The only difference between sequence 211 and sequence 221 is that on-network calls in sequence 211 are proceeded with a “0” while off-network calls to conventional telephones in sequence 221 are proceeded with a “ 1 .” Thus, to dial an off-net telephone number, a ZeroPlus user simply dials sequence 221 (“1” plus the destination telephone number) from the ZeroPlus Graphical User Interface (GUI) client software, thus sending the information to the Internet Telephony gateway best situated to deliver the call cost effectively, which is usually the gateway closest to the destination. In this way, the simplified dialing plan has originated a call from a data network such as the Internet 129 to the PSTN. Thus, the access code for gateway calling consists of a combination of both the registered ZeroPlus telephone number and a member PIN. Number portability is made available by the ZeroPlus system by deriving both ZeroPlus access numbers and desired destination numbers from the users' conventional telephone numbers. Upon entering their gateway access code, users will be prompted for the telephone number they wish to reach. Again, this can be any on-net “0” plus telephone number or an off-net “1” plus telephone number. Zeroplus Operating Modes Calls can be placed in various modes, including PC-to-PC, PC-to-Phone, Phone-to-PC, and Phone-to-Phone. Further, PC-to-PC calls can feature call waiting, call forwarding, call transfer, three-way calling, and voice mail. User computer A 103 , user computer B 157 and user computer C 159 are referred to as Stations A, B, and C in this section. This description assumes that all parties/stations (A, B, C, and D) have data connectivity and have already logged into ZeroPlus, and that an IP Address is already associated with each these stations. Note that station D does not explicitly appear on the diagrams. As shown in FIG. 3 , in PC-to-PC calls, Station A 103 dials Station B's 157 or 159 ZeroPlus number. The ZeroPlus application sends an Admission Request message which contains the calling number (Station A) and the called number (Station B) to the Gatekeeper 115 . The Gatekeeper responds with an Admission Confirm containing IP Addresses which route to Station B. When Station B receives a Setup message, it sends an Authorization Request to the Gatekeeper. The Gatekeeper responds to Station B with an Authorization Confirm. Since it is available to accept the call, Station B then responds to Station A's Setup message with an Alerting message, and begins to ring. Station A begins to ring when it receives the Alerting message from Station B. When Station B answers the call, a Connect message is sent to Station A and a voice channel is opened from Station B to Station A. When Station A receives the Connect message from Station B, it responds to the Connect message with a Connect Acknowledgement and opens a voice channel from Station A to Station B. Signaling Messages Interacting with the Gatekeeper Various signaling message formats are used between end-point stations, gateways and the gatekeeper. All these message formats are specially defined for this inventions. Gatekeeper Logging-In Messages Gatekeeper Request— FIG. 5 shows the Gatekeeper Request Message Information Elements format. When the user logs in, a Gatekeeper Request Message is sent from the station to the gatekeeper to request user validation. Gatekeeper Confirm— FIG. 6 a shows the Gatekeeper Confirmation Message Information Elements (Section 1) format. FIG. 6 b shows the Gatekeeper Confirmation Message Information Elements (Section 2) format. The gatekeeper sends a Gatekeeper Confirm back to the end station in response to a Gatekeeper Request if the user information is valid. Gatekeeper Reject— FIG. 7 shows the Gatekeeper Rejection Message Information Elements format. The gatekeeper sends a Gatekeeper Reject back to the end station in response to a Gatekeeper Request if the user information is invalid. Call Setup Messages Admission Request— FIG. 8 shows the Admission Request Message Information Elements format. When a calling station initiates a call, it collects a farend number. This number along with the calling number is passed to the gatekeeper in the Admission request Message. Admission Confirm— FIG. 9 a shows the Admission Confirmation Message Information Elements (Section 1) format. FIG. 9 b shows the Admission Confirmation Message Information Elements (Section 2) format. The gatekeeper sends an Admission Confirmation Message back to the calling station in response to an Admission Request Message if the gatekeeper successfully translates the called number. Admission Reject— FIG. 10 shows the Admission Reject Message Information Elements format. The gatekeeper sends an admission Reject Message back to the calling station in response to an Admission Request Message if the gatekeeper is unsuccessfully in translating the called number. Bandwidth Management Messages Bandwidth Request— FIG. 16 shows the Bandwidth Request Message Information Elements format. A gateway sends a gatekeeper a Bandwidth Request Message to request a bandwidth change to the Class of Service. Bandwidth Confirm— FIG. 17 shows the Bandwidth Confirmation Message Information Elements format. The gatekeeper sends a gateway a Bandwidth Confirm Message in response to a Bandwidth Request Message if the gatekeeper can allocate bandwidth of the Class of Service for this call. Bandwidth Reject— FIG. 18 shows the Bandwidth Reject Message Information Elements format. The Gatekeeper sends the Gateway a Bandwidth Reject Message in response to a Bandwidth Request Message if the gatekeeper cannot allocate bandwidth of the Class of Service for this call. Faxcall— FIG. 19 shows the FaxCall Message Information Elements format. The gateway (that detected the fax call) sends a FaxCall Message to the Farend Gateway to inform the Farend Gateway to change its class of service (or compression). Trunks Busy— FIG. 20 shows the GK Trunks Busy Message 0x4E Information Elements format. This message is sent from a gatekeeper to a gateway to request “busying out” or disabling the remaining available channels because bandwidth constrains the network. Trunks Busy ACK— FIG. 21 shows the GK Trunks Busy ACK Message 0x4F Information Elements format. FIG. 22 shows the GK Trunks Busy ACK Message 0x4E Information Elements format. These messages are sent from a gateway to a gatekeeper to acknowledge the busy trunks request message. Trunks Unbusy— FIG. 23 shows the GK Trunks Unbusy Message 0x4C Information Elements format. This message is sent from a gatekeeper to a gateway to request “unbusying out” or enabling all “busied out” channels because of bandwidth availability. FIG. 24 shows the GK Trunks Unbusy ACK Message 0x4D Information Elements format. These messages are sent from a gateway to a gatekeeper to acknowledge the unbusy trunks request message. Other Messages Heartbeat— FIG. 25 shows the Heartbeat Message Information Elements format. A station sends a Heartbeat message to the gatekeeper regularly after it receives a Gatekeeper Confirm message after the station logs in. The message tells the gatekeeper that the station is currently up and running and also tells the gatekeeper the station is currently on call. To further illustrate the invention, various calling features are described in terms of Zeroplus messages. PC to PC—Forward Unconditional FIG. 26 illustrates the case in which Station B unconditionally forwards received calls to Station C. Station A dials Station B's ZeroPlus number. The ZeroPlus application sends an Admission Request containing the calling number (Station A) and the called number (Station B) to the Gatekeeper. The Gatekeeper responds with an Admission Confirm message containing IP Addresses which route to Station B. Since Station B is in forward mode, the Admission Confirm message also contains forwarding information (unconditionally forwarded to Station C). Since Station B is unconditionally forwarded, Station A's ZeroPlus application sends a Setup message to Station C. When Station C receives the Setup message, it sends an Authorization Request to the Gatekeeper, which responds to Station C with an Authorization Confirm. Since Station C is available to accept the call, it then responds to Station A's Setup message with an Alerting message and begins to ring. Station A produces a ringback sound when it receives the Alerting message from Station C. When Station C answers the call, a Connect message is sent to Station A and a voice channel is opened from Station C to Station A. When Station A receives the Connect message from Station C, it responds with a Connect Acknowledgement and opens a voice channel from Station A to Station C. PC to PC—Forward on Busy FIG. 27 illustrates the case in which Station B forwards incoming calls when busy to Station C. Station A dials Station B's ZeroPlus number. The ZeroPlus application sends an Admission Request containing the calling number (Station A) and the called number (Station B) to the Gatekeeper. The Gatekeeper responds with an Admission Confirm message containing IP Addresses which route to Station B. Since Station B is in forward mode, the Admission Confirm message also contains forwarding information (forwarded on busy to Station C). Station A's ZeroPlus application sends a Setup message to Station B. Station B is already on a call with Station D (not shown) when it receives Station A's Setup message. Therefore, Station B responds to Station A's Setup message with a Release Complete and continues on the call with Station D. Upon receiving the Release Complete message, Station A determines that Station B is currently busy and uses the forwarding information received in the initial Admission Confirm message from the Gatekeeper to send another Admission Request to the Gatekeeper. The Gatekeeper responds with an Admission Confirm message. When Station A receives the Admission Confirm message from the Gatekeeper, it sends a Setup message to Station C. When Station C receives the Setup message, it sends an Authorization Request to the Gatekeeper, which responds to Station C with an Authorization Confirm. Since it is available to accept the call, Station C then responds to Station A's Setup message with an Alerting message and begins to ring. When Station A receives the Alerting message from Station C, a ringback sound is heard. When Station C answers the call, it sends a Connect message to Station A and opens a voice channel from Station C to Station A. When Station A receives the Connect message from Station C, it responds with a Connect Acknowledgement and opens a voice channel from Station A to Station C. PC to PC—Forward on No Answer FIGS. 28 a and 28 b illustrate the case in which Station B does not answer, and forwards calls to Station C. Station A dials Station B's ZeroPlus number. The ZeroPlus application sends an Admission Request containing the calling number (Station A) and the called number (Station B) to the Gatekeeper. The Gatekeeper responds with an Admission Confirm containing IP Addresses which route to Station B. Since Station B is in forward mode, the Admission Confirm message also contains forwarding information (forwarded on no answer to Station C). Station A's ZeroPlus application sends a Setup message to Station B. Station B is currently not on a call. Upon receiving Station A's Setup message, Station B sends an Authorization Request to the Gatekeeper, which responds with an Authorization Confirm to Station B. Since Station B is available to accept this call, it sends Station A an Alerting message and begins to ring. Upon receiving the Alerting message from Station B, Station A emits a ringback sound. After five rings, since Station A has received information to forward calls on no answer, to Station C. Therefore, Station A stops ringing and sends a Disconnect message to Station B to begin disconnecting the call. Station A also sends an End-of-Call and an Admission Request message to the Gatekeeper. To complete disconnecting the call between stations A and B, in response to Station A's Disconnect message, Station B sends a Release message and also stops ringing. When Station A receives Station B's Release message, it responds by sending a Release Complete message to Station B, which completes disconnecting the call from Station A's perspective. Receiving Station A's Release Complete message completes disconnecting the call from Station B's perspective. The Gatekeeper responds with an Admission Confirm message to Station A. When Station A receives the Admission Confirm message from the Gatekeeper, it sends a Setup message to Station C. When Station C receives the Setup message, it sends an Authorization Request to the Gatekeeper, which responds with an Authorization Confirm to Station C. Since Station C is available to accept the call, it then responds to Station A's Setup message with an Alerting message and begins to ring. When it receives the Alerting message from Station C, Station A commences ring back. When Station C answers the call, it sends a Connect message to Station A and opens a voice channel from Station C to Station A. When Station A receives the Connect message from Station C, it responds with a Connect Acknowledgement and opens a voice channel from Station A to Station C. PC to PC—Forward on No Response FIG. 29 illustrates the case in which on no response, Station B forwards calls to its station to Station C. Station A dials Station B's ZeroPlus number. The ZeroPlus application sends an Admission Request containing the calling number (Station A) and the called number (Station B) to the Gatekeeper. The Gatekeeper responds with an Admission Confirm containing IP Addresses which route to Station B. Since Station B is forwarded, the Admission Confirm message also contains forwarding information (forwarded on no response to Station C). Station A's ZeroPlus application sends a Setup message to Station B. Station B is currently not logged into ZeroPlus. After three seconds, Station A resends the Setup message to Station B. After another three seconds, Station A's ZeroPlus application determines that there is no response from Station B. Since Station A has forwarding on no response information for Station B, it sends another Admission Request to the Gatekeeper. The Gatekeeper responds with an Admission Confirm message to Station A. When Station A receives the Admission Confirm message, it sends a Setup message to Station C. When Station C receives the Setup message, it sends an Authorization Request to the Gatekeeper, which responds with an Authorization Confirm to Station C. Since it is available to accept the call, Station C then responds to Station A's Setup message with an Alerting message and begins to ring. When it receives the Alerting message from Station C, Station A commences ringback. When Station C answers the call, it sends a Connect message to Station A and opens a voice channel from Station C to Station A. When Station A receives the Connect message from Station C, it responds with a Connect Acknowledgement and opens a voice channel from Station A to Station C. PC to PC—Call-Waiting FIGS. 30 a and 30 b illustrate the case in which Station B has the call-waiting feature enabled, is talking to Station A, and receives an incoming call from Station C. Station A dials Station B's ZeroPlus number. The ZeroPlus application sends an Admission Request containing the calling number (Station A) and the called number (Station B) to the Gatekeeper. The Gatekeeper responds to Station A with an Admission Confirm message containing IP Addresses which route to Station B. When Station A receives the Admission Confirm message, it sends a Setup message to Station B. Since Station B is currently not on a call, when it receives the Setup message from Station A it sends an Authorization Request to the Gatekeeper, which responds with an Authorization Confirm to Station B. Since it is available to accept the call, Station B then responds to Station A's Setup message with an Alerting message and begins to ring. When it receives the Alerting message from Station B, Station A commences ringback. When Station B answers the call, it sends a Connect message to Station A and opens a voice channel from Station B to Station A. When Station A receives the Connect message from Station B, it responds with a Connect Acknowledgement and opens a voice channel from Station A to Station B. While Station A and Station B are conducting their call, Station C dials Station B's ZeroPlus number. The Station C ZeroPlus application sends an Admission Request containing the calling number (Station C) and the called number (Station B) to the Gatekeeper. The Gatekeeper responds to Station C with an Admission Confirm message containing IP Addresses which route to Station B. When Station C receives the Admission Confirm message, it sends a Setup message to Station B. Station B is currently on a call with Station A. Since Station B has the call-waiting feature enabled, when it receives the Setup message from Station C, Station B sends an Authorization Request to the Gatekeeper. The Gatekeeper responds with an Authorization Confirm to Station B. Since it is available to accept the call, Station B then responds to Station C's Setup message with an Alerting message. At this time, Station B hears the call-waiting tone. When it receives the Alerting message from Station B, Station C begins ringback. Station B clicks on the GUI Flash button to answer the call from Station C. Upon receiving the Suspend message from Station B, Station A closes the voice channel from itself to Station B and responds with a Suspend Acknowledgement message. Upon receiving the Connect message from Station B, Station C opens a voice channel from itself to Station B and responds with a Connect Acknowledgement message to Station B, thus answering the new call. PC to PC—Blind Transfer FIGS. 31 a , 31 b and 31 c illustrate the case in which Station B has the transfer feature enabled. Station A dials Station B's ZeroPlus number. The Station A ZeroPlus application sends an Admission Request containing the calling number (Station A) and the called number (Station B) to the Gatekeeper. The Gatekeeper responds to Station A with an Admission Confirm message containing IP Addresses which route the call to Station B. When Station A receives the Admission Confirm message from the Gatekeeper, it sends a Setup message to Station B. Since Station B is currently not on a call, when it receives the Setup message from Station A it sends an Authorization Request to the Gatekeeper. The Gatekeeper responds to Station B with an Authorization Confirm. Since it is available to accept the call, Station B then responds to Station A's Setup message with an Alerting message and begins to ring. When it receives the Alerting message from Station B, Station A begins to ringback. When Station B answers the call, it sends a Connect message to Station A and opens a voice channel from Station B to Station A. When Station A receives the Connect message from Station B, it responds with a Connect Acknowledgement and opens a voice channel from Station A to Station B. Next, the Station A user verbally requests to be transferred to Station C. The Station B user clicks on the Transfer button. This event sends a Suspend message to Station A and closes the voice channel from Station B to Station A. Upon receiving the Suspend message from Station B, Station A closes the voice channel from itself to Station B and responds with a Suspend Acknowledgement. Station B acknowledges receipt of the Suspend Acknowledgement message from Station A. Clicking the GUI Transfer button at Station B also initiates dialing the second leg of the transfer. The GUI prompts the Station B user to enter a number to dial. Station B then enters Station C's ZeroPlus number and clicks on the Dial button, which initiates Station B transferring to Station C. Station B's ZeroPlus application sends an Admission Request containing the calling number (Station B) and the called number (Station C) to the Gatekeeper. The Gatekeeper responds to Station B with an Admission Confirm message containing IP Addresses which route to Station C. When Station B receives the Admission Confirm message, it sends a Setup message to Station C. Since Station C is currently not on a call when it receives the Setup message, it sends an Authorization Request to the Gatekeeper, which responds with an Authorization Confirm to Station C. Since it is available to accept the call, Station C then responds to Station B's Setup message with an Alerting message and begins to ring. When it receives the Alerting message from Station C, Station B begins ringback. Station B completes the blind transfer by clicking the Transfer button before Station C has answered. Station B sends a Transfer message containing Station C's number to Station A. Upon receiving the Transfer message from Station B, Station A does the following: responds to Station B with a Transfer Acknowledgement message, and sends the Gatekeeper an End of Call and an Admission Request message. When Station B receives the Transfer Acknowledgement message, it sends an End Of Call message to the Gatekeeper for each of the transfer legs. Station B has completed its part of the transfer. The Gatekeeper sends to Station A an Admission Confirm message containing IP Addresses which route to Station C. When Station A receives the Admission Confirm message, it sends a Setup message to Station C. When it receives the Setup message from Station A, Station C sends an Authorization Request to the Gatekeeper. The Gatekeeper responds to Station C with an Authorization Confirm. Station C determines that the Setup message from Station A is due to a transfer, then, since it is available to accept the call, responds to Station A's Setup message with an Alerting message and continues to ring. When it receives the Alerting message from Station C, Station B begins to ring. When Station C answers the call, a Connect message is sent to Station A and a voice channel is opened from Station B to Station A. When Station A receives the Connect message from Station B, it responds to the Connect message with a Connect Acknowledgement and opens a voice channel from Station A to Station B. PC to PC—Consultative Transfer FIGS. 32 a , 32 b and 32 c illustrate the case in which Station B has the transfer feature enabled. Station A dials Station B's ZeroPlus number. The Station A ZeroPlus application sends an Admission Request containing the calling number (Station A) and the called number (Station B) to the Gatekeeper. The Gatekeeper responds to Station A with an Admission Confirm message containing IP Addresses which route to Station B. When Station A receives the Admission Confirm message, it sends a Setup message to Station B. Since Station B is currently not on a call, when it receives the Setup message from Station A it sends an Authorization Request to the Gatekeeper. The Gatekeeper responds with an Authorization Confirm to Station B. Since it is available to accept the call, Station B then responds to Station A's Setup message with an Alerting message and begins to ring. When it receives the Alerting message from Station B, Station A begins ringback. When Station B answers the call, it sends a Connect message to Station A and opens a voice channel from Station B to Station A. When Station A receives the Connect message from Station B, it responds to the Connect message with a Connect Acknowledgement and opens a voice channel from Station A to Station B. Next, Station A verbally requests to be transferred to Station C. Station B clicks on the Transfer button, which sends a Suspend message to Station A and closes the voice channel from Station B to Station A. Upon receiving the Suspend message from Station B, Station A closes the voice channel from itself to Station B and responds with a Suspend Acknowledgement. Station B acknowledges the receipt of the Suspend Acknowledgement message from Station A. Clicking the Station B's Transfer button also initiates dialing the second leg of the transfer. The GUI prompts the Station B user to enter a number to dial. The Station B user then enters Station C's ZeroPlus number and clicks on the Dial button, which initiates Station B dialing Station C. Station B's ZeroPlus application sends an Admission Request containing the calling number (Station B) and the called number (Station C) to the Gatekeeper. The Gatekeeper responds to Station B with an Admission Confirm message containing IP Addresses which routes to Station C. When Station B receives the Admission Confirm message from the Gatekeeper, it sends a Setup message to Station C. Since Station C is currently not on a call when it receives the Setup message from Station B, it sends an Authorization Request to the Gatekeeper. The Gatekeeper responds with an Authorization Confirm to Station C. Since it is available to accept the call, Station C then responds to Station B's Setup message with an Alerting message and begins to ring. When it receives the Alerting message from Station C, Station B begins ringback. When Station C answers the call, it sends a Connect message to Station B and opens a voice channel from Station B to Station C. When Station B receives the Connect message from Station C, it responds with a Connect Acknowledgement and opens a voice channel from Station C to Station A. After Station C has answered, the Station B user completes the consultative transfer by clicking the Transfer button. Station B sends a Transfer message containing Station C's number to Station A. Upon receiving the Transfer message, Station A does the following: responds with a Transfer Acknowledgement message to Station B, and sends the Gatekeeper an End of Call and an Admission Request message. When Station B receives the Transfer Acknowledgement message, it sends an End Of Call message to the Gatekeeper for each of the transfer legs. Station B has completed its part of the transfer. Next, the Gatekeeper sends to Station A an Admission Confirm message containing IP Addresses which route to Station C. When Station A receives the Admission Confirm message, it sends a Setup message to Station C. When it receives the Setup message Station C sends an Authorization Request to the Gatekeeper, which responds with an Authorization Confirm to Station C. Station C determines that the Setup message from Station A is due to a transfer and then, since it is available to accept the call, responds to Station A's Setup message with a Connect message. Station C closes the voice channel from itself to Station B and reopens a voice channel from itself to Station A. When Station A receives the Connect message from Station C, it sends a Connect Acknowledgement to Station C and opens a voice channel from itself to Station C. Calls Via Internet Involving Conventional Telephones The system also manages calls to or from conventional telephones. The gateway gatekeeper and gateway seamlessly bridge calls from the Internet destined to the PSTN and calls from the PSTN to the Internet, or PSTN to PSTN via Internet. When a call goes from PSTN to PSTN, the gateway responsible for the specific area and city code at the point of origin handles that portion of the call, and a gateway responsible for the destination area and city code handles the termination side of the call. Each side of the call is treated as a separate call which is bridged together over Internet or other data network that both gateways have in common. Note that a gatekeeper also includes a gateway, in addition to its call management functions. The gateway also is used for the PSTN side of a PC-to-telephone and a telephone-to-PC call. Whenever the PSTN or another switch, PBX, IVR or other call center device is utilized in the origination and/or the termination of a call, a gateway must also be used at any point where traditional telecommunication technology is involved. For phone-to-phone calls, neither party uses a PC. Both sides are handled by gateways as previously explained. For PC-to-phone or phone-to-PC calls, ZeroPlus software is required only on the PC side of the call, and a gateway will handle the other side of the call. PC-to-PC calls require that both parties have ZeroPlus software. The gatekeeper determines which is the “best way” to route calls. The gatekeeper has routing tables much like those in traditional telecommunications switches. These routing tables are addressed any time a calling party addresses a call request to the gatekeeper. There are two completely different routing methodologies. One is for on-net calls (i.e. calls originating from and terminating at ZeroPlus clients on the Internet). The second is a more sophisticated routing methodology for calls originating on the Internet and terminating off-net, i.e. calls where the calling party is connected via the Internet and the called party is reached via a one (“1”) plus termination through a gateway to the PSTN. In this situation the gatekeeper routing tables determine the least cost route to terminate the call. The “best way” is a combination of the least cost route and available resources. In the event that all resources are available (i.e. all gateways for termination of off-net traffic in all cities still have ports available to handle the call), the default route will be the least cost one. For example, if a call is destined for area code 512 (Austin, Tex.) and there is a gateway on the network that provides local service in Austin, the least cost route would terminate the call in Austin without applying any long distance leg. But, if the Austin gateway were to have all ports busy at the time of the call attempt, it would be necessary to terminate the call through another gateway on the network. In this case a routing table would route the call anywhere except Texas due to the large premium on calls that originate and terminate in Texas. It actually costs less to terminate a call in Oklahoma and pay a discount long distance rate to back haul the call to Texas. The programming of the routing tables emulates that which is standard and ordinary in the telecommunications industry today. Programming the routing tables does not require a programmer, only an administrator who minimizes costs associated with calls destined for different areas of the country. The gatekeeper database has routing information and tables of data related to the IP addresses. The gatekeeper determines the IP addresses of any device addressed by the service. In the case of the end-user, once data connectivity has been established, it allows the computer to be assigned an IP address by the Internet Service Provider (ISP), and the user launches the ZeroPlus Application. When the application starts up it opens a dialog box and requires the user to input his or her ten digit ZeroPlus number and the associated four digit PIN. After the user enters the appropriate information into the dialog box and clicks the OK button, the application sends to the gatekeeper a validation request containing the ZeroPlus number, PIN, and current IP address of the station. The gatekeeper looks up the ZeroPlus number in the database and verifies that both the PIN and the ZeroPlus number are correct, sends a validation accepted message to the ZeroPlus application and updates the user's account with the current IP address. The gatekeeper also sends back information associated with the current features (i.e. call forwarding, call waiting, three way calling, call transfer, voice mail) to which the member has access. For example, if the member has “call forward set on no answer” assigned to his/her office ZeroPlus telephone number, the ZeroPlus telephone number of that ZeroPlus station will be passed back to the application. If the user has call transfer, three-way calling, and call waiting capability, the gatekeeper will include information in the message to the application notifying it to accept requests for these features. If the member has subscribed to voice mail, the IP address of the voice mail server or its “phone number” will be passed to the application. Upon receipt of a confirmation, the end station will commence sending “heartbeat” messages to the gatekeeper so that the gatekeeper will know that the station is still “logged on.” Traditional telephone network users are restricted to telephone devices which are physically connected to a set of wires within a fixed structure, such as a home. With portable telephones such as cellular phones, the equipment is mobile but the telephone number is not. Mobile cellular telephone numbers are device-specific to a particular cell telephone. Cell telephone users lose number portability because they have to use a specific cell telephone registered for that telephone number. The ZeroPlus architecture provides a device-independent telephone number access strategy. This enables mobile users to use their portable telephone number during travel without necessarily taking their physical portable telephone with them. ZeroPlus users with at least 28.8 Kbps access to a digital data network and a computer with the ZeroPlus GUI have access to all incoming calls and are able to make outgoing calls on their current ZeroPlus account. Members may use ZeroPlus with telephones when they do not have access to their computer. Inbound calls placed to the user computer are not forwarded to conventional telephones unless they subscribe to and use the call forward-feature of the service to forward their ZeroPlus calls to an off-net telephone number. To originate ZeroPlus calls without access to their computers, members dial a PSTN access number and follow the instructions to connect either on-net or off-net calls. Billable calls are posted to their ZeroPlus accounts. Traditional telephone network users have grown accustomed to a variety of add-on features and up-grades available on the PSTN. The ZeroPlus system, through its robust combination of technology, hardware, software and connectivity to the PSTN, also makes a large suite of features available to users. Upgrades (for an added fee) include call forwarding, call waiting, call transfer, caller ID, “follow me” service, voice mail and conference calls, as described previously. The ZeroPlus plan also provides connection shortcuts to frequently called numbers. The list is called the “ZP Pals” list. Once the gatekeeper has sent the validation acceptance message, it can access what ZeroPlus users this member has in his/her ZP Pals list and what ZP Pals have this member in their list. It sends a message to the “logging in” station containing the ZP Pals list, what the IP address is for each of the “pals” that are online, and what members are interested in the online status of this station. An exception to this is that the Gatekeeper will not return IP addresses for members if “Call Blocking” applies. This feature prevents other users from determining online status or placing calls to the blocked ZeroPlus number. The end station will then display the ZP Pals who have gatekeeper-supplied current IP addresses with the “online indicator” and send each of them, along with the members having this user in their ZP Pals list, a message telling them the member is online. ZP Pals on the list without an IP address will be displayed with the “offline indicator.” The end station will notify all “interested parties” when it is shutting down so that the other stations will know to update the status for the user on this station to “offline.” In the event that the gatekeeper fails to receive a “heartbeat” from a station it believes to be online, it will send all interested parties notification that the station is “offline,” update the status it has on that station to reflect the fact that it is offline, and close out any calls that might be active for that station. This is to address the problem that computers do “crash” occasionally or lose Internet connectivity. It is not sufficient to rely on a “clean” shutdown for the end stations. ZeroPlus provides phone number location independence. The ZeroPlus number and PIN code as well as the ZP-Pals list, feature set, and possible affiliate partner logos are all location independent. For example, if a member signs in through an affiliate partner such as Talk City and has a home telephone number which is “1 301 555 1212,” the corresponding ZeroPlus number “0 301 555 1212” will be assigned to their home computer. Upon logging onto ZeroPlus, the gatekeeper checks and validates the account and then notifies the ZeroPlus application of all of the services that the user has available. The application would also be provided with the user's ZP-Pals list, and the current status (i.e. on-line or off-line) of each of those individuals. If a ZeroPlus member is visiting a family which has a multimedia computer but is not a ZeroPlus member and does not have the application resident on their hard drive, then the only thing that the member would have to do would be to download the application and log in using his/her ZeroPlus number and PIN. Once the user logs into that computer, all normal ZeroPlus capabilities would be available at that computer. The ZeroPlus number and all associated account features are completely portable and hardware independent. While traditional home telephone numbers require a fixed port on a switch, or the number has to be forwarded to another fixed port on a switch. ZeroPlus numbers are completely hardware and port independent. The numbers are routed, not switched. What has been described is a private dialing plan wherein conventional telephone numbers are used as the basis for creating caller access numbers and the number dialed to reach the recipient. Although described with respect to a particular exemplary embodiment, principles of the invention may be exploited in other dialing systems and telephonic communication methods. Accordingly, the embodiments described herein should be regarded as merely illustrative of the invention and should not be construed as limiting the scope of the invention.

A private dialing plan for the communication of packetized voice on a packet-based network using a signaling protocol such as Q.931 to establish, maintain and release switched connections over the network. The dialing plan uses a “telephone number” based on a conventional 10-digit telephone number, such as the user's regular telephone number. A leading single digit consisting of a “0” or a “1” is added in front of the conventional telephone number. A leading “0” indicates that the desired call is to be directed to the called party's on-network computer by means of the Internet, while a leading “1” indicates the call is directed through a special gateway to the called party's conventional telephone.

CROSS REFERENCES TO RELATED APPLICATIONS This application is a division of Ser. No. 80,760, filed Oct. 1, 1979, now U.S. Pat. No. 4,339,031, issued July 13, 1982. 1. "Conveyor belt" by Merle L. Hoover, U.S. Ser. No. 69,664 filed Aug. 24, 1979, now abandoned in favor of continuation U.S. Ser. No. 224,419, filed Jan. 12, 1982. 2. "Conveyor Belt Chain and Method for Its Use" by Harry R. Becker, U.S. Pat. No. 4,282,971, issued Aug. 11, 1981. 3. "Conveyor System Having An Inby Terminal Connected to a Bridge Conveyor for Unitary Movement Therewith", by Neal W. Densmore and Donald E. McDaniel, U.S. Ser. No. 80,851, filed Oct. 1, 1979. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to conveyor systems, and, more particularly, is directed to an articulated conveyor adapted to be suspended from an overhead monorail and capable of traversing a curvilinear path. 2. Description of the Prior Art In mining operations, especially underground mining operations, such as, coal mining or the like, conveyors or series of conveyors are used to transport the mined ore from the mine. Normally, there is a main conveyor that moves the mined material along a fixed path. The main conveyor has a terminal end at a fixed location for receiving the material being mined. In the past, shuttle cars or other short distance haulage vehicles have been used to transport the mined material from the mining machine to the fixed terminal end of the main conveyor. The use of shuttle cars and other such haulage vehicles is intermittent, time consuming, and inefficient in not providing for the continuous transport of the mined materials from the mining machine to the fixed conveyor. Thus, in more recent years there have been several developments directed toward a mobile articulated conveyor that provides for continuous transport of the discharge of a continuous miner to the main conveyor as the miner advances into the mine face and changes the direction of its forward movement. Such mobile articulated conveyors are particularly adaptable to "room and pillar" type coal mining operations wherein the mobile conveyor follows the continuous miner and changes in direction as the machine penetrates into the mine face in one room and then is backed out and set to work in the mine face of another room while roof bolts are installed in the recently mined room. The mining machine is then backed out of this second room and set to work in either the recently roofbolted room or it may go on to still another room. One of these more recently developed mobile articulated conveyors is shown in the Payne et al. patent, U.S. Pat. No. 3,707,218, and sold under the trade designation "Serpentix". The Serpentix conveyor has an endless trough shaped, accordion-pleated belt supported on a vertebrae-like member which, in turn, is supported on the mine floor by stanchions. The stanchion supported conveyor was cumbersome and did not lend itself to frequent shifting of the conveyor path from room to room. Thus, Craggs, as shown in U.S. Pat. No. 3,920,115, suspended the Serpentix conveyor from an overhead monorail and thereby provided a flexible frame conveyor which could be attached to the surge car behind a mining machine. The conveyor could now follow the mining machine as it moved from one room to another in performing its mining operation. Another development is such mobile articulated conveyors is disclosed in McGinnis U.S. Pat. No. 3,701,411 which shows a conveyor comprised of an endless belt supported on a train of pivotally interconnected portable cars or carriages. Each of the carriages are supported on ground engaging wheels thereby providing mobility to the conveyor. A self propelled tractor is connected to the conveyor train to move it from one location to another. Another development along the same lines can be found in U.S. Pat. No. 3,863,752. A later McGinnis patent, U.S. Pat. No. 4,061,223, discloses a mobile articulated conveyor suspended from an overhead monorail. Shown is a U-shaped conveyor belt carried by a plurality of individual carriage units suspended from the overhead monorail. The carriage units are fastened to one another by a resilient, flexible spline member which provides for positioning of the carriage units around vertical and horizontal curves. The conveyor belt is driven by a separate power belt and guided by guide rollers. Although, the above-referenced developments have made an advancement in the art of mobile articulated conveyors, each has encountered specific problems and does not perform as satisfactorily as desired. Along with suffering from the shortcomings of being expensive, cumbersome, bulky, complex structures, with some having a high silhoutte, these referenced developments have experienced problems in maintaining the upper conveying run portion of the belt in a suitable load conveying mode as the conveyor moves around horizontal and vertical curves. Further, these prior conveyors do not provide a smooth path for the belt to follow around curves, thus pinching the belt and causing excessive wear thereto. SUMMARY OF THE INVENTION The preferred embodiment of the conveyor system, as disclosed herein, includes various unique features for facilitating the transport of materials from a first location, such as an area where a continuous miner is working, to a second location, such as where the receiving end of a second conveyor is positioned, wherein the travel path defined between the first and second locations includes horizontal and/or vertical curves. While these unique features are particularly adapted for conveying materials along a curvilinear path such as experienced in underground mining operations, it will be readily apparent that some of such features may be incorporated, either singly or together, into above ground conveying systems for conveying materials along either linear or curvilinear paths, as well as, for conventional above and below ground flexible conveyors and thereby improve the same. Also, some of these features comprise inventions in other copending applications, cross referenced above; however all are illustrated and described herein for facilitating a complete and thorough understanding of those of the features comprising the present invention. It is, accordingly, the principal object of the present invention to provide a conveyor system with an articulated conveyor in which the aforementioned problems of the prior art have been overcome and which is simple and inexpensive in structure, reliable in operation, and is so constructed to present a low profile enabling the same to maneuver around pillars and through low clearance passageways. More particularly, an object of the present invention is to provide an improved articulated conveyor which is adapted to be suspended from an overhead rail and which is capable of traversing a curvilinear path while maintaining the conveying run portion of an orbital conveying belt in a predetermined operative mode. More specifically, an object of the present invention is to provide an articulated conveyor which includes a train of carriages suspended from an overhead monorail with each carriage cooperating with an adjacent carriage so as to selectively limit the lateral swing of one carriage relative to an adjacent carriage in thereby maintaining the carriage train in a predetermined disposition relative to the monorail as the same moves along the monorail. Yet another object of the present invention is to suspend the carriages a relatively short distance below the monorail so as to decrease the tendency of the carriages to swing in a transverse direction as the carriage moves longitudinally along the monorail. Still another object of the present invention is to provide a conveyor with an improved traction drive means for moving a mobile articulated conveyor along an overhead rail while substantially eliminating any binding and other deleterious forces normally associated with, or resulting from, moving a rigid member through horizontal and/or vertical curved paths. Still further, an object of the present invention is to provide a conveyor with a traction drive means wherein the configuration is such that a conveyor can be driven from either one of its ends or from an intermediate section thereof while maintaining a low profile of the conveyor. Another object of the present invention is to provide a conveyor with an improved sprocket for driving a chain which is attached to a prestretched orbital conveying belt so as to relieve any increase in tension in the belt due to the belt traveling around the drive sprocket, and thus, decrease wear to the belt and prolong its life. In pursuance of these and other objects, the present invention sets forth a conveying system comprised of a plurality of tandemly disposed carriages that are connected to one another by an articulated joint so as to permit each carriage to move universally relative to an adjacent carriage and to permit the train of carriages to be moved in unison along a curvilinear path. Each of the carriages includes a framework defining an open extent extending longitudinally therethrough and constructed of an upper elongated link member disposed adjacent the overhead rail and a pair of traversely spaced apart, longitudinally extending side members disposed on opposite sides of the open extent and interconnected to the elongated link member, preferably, by a pair of longitudinal spaced downwardly projecting U-shaped frame members. The carriages further carry means for supporting an orbital belt which extends longitudinally within the open extent and preferably located between the upper elongated link member and the lower side members. Mounted on the respective ends of adjacent link members are portions that form the articulated joint which thereby connect adjacent carriages and permit universal movement of one carriage relative to its tandemly disposed adjacent carriage. In the preferred embodiment, the carriage train is suspended from and below the overhead rail by suspension means cooperable with the rail and connected to the carriages via selected ones of the articulated joints. Mounted on the ends of adjacent side members are structures that cooperate with one another so as to selectively limit the lateral movement of adjacent carriages relative to one another during the longitudinal movement thereof. More particularly, one of the side member end structures partially surrounds the side member end structures of an adjacent carriage with the cooperating ends structures being so positioned relative to one another such that one side member is permitted to move a given amount with respect to the other side member, and thereafter, the side member end structures engage one another so as to cause common movement thereof and thus preventing further swing of the carriages. The articulated conveyor is moved along the monorail by drive traction means that includes at least a pair of transversely spaced apart rotatable traction drive wheels being disposed on the opposite sides of the rail. Driveably coupled to respective ones of the wheels is a pair of transversely spaced apart power units being disposed on opposite sides of the rail and pivotally connected to one another below the drive wheels. To maintain the drive wheels in drive traction relationship with the rail, pivot means, preferably in the form of an actuator transversely disposed and interconnected between respective lower portions of the power units, are provided and operable to pivot the power units toward and away from one another and thus move the drive wheels toward and away from one another so as to maintain the drive wheels in drive traction relationship with the overhead rail. Additionally, the drive traction means includes an elongated framework suspended from the rail and disposed within the vicinity of the power units. The framework is connected to at least one of the carriages and includes end portions spaced longitudinally outwardly from the opposite longitudinal ends of the power units with a rigid frame member interconnecting the opposite end portions. The respective ends of the power units are connected to respective end portions of the framework by link means, preferably in the form of a flexible chain. Upon movement of the power units in one direction, one of the chains is put in tension in providing a force transmitting path through the rigid frame member to an adjacent carriage. Upon movement of the drive unit in the opposite direction, the other one of the chains is put in tension so as to provide a force transmitting path through the rigid frame member. The chain not in tension is relaxed and incapable of transmitting a force through the rigid frame member. The present invention further includes an improved sprocket for driving the conveyor belt. The drive sprocket comprises a plurality of teeth arranged in sets of three around the periphery of the sprocket with the first two teeth of each set being spaced a given distance from each other on a circumferential pitch circle on the sprocket. The third tooth of each set being spaced a distance less than the given distance from the trailing one of the first two teeth of each set. The third tooth also constitutes the first tooth of the succeeding set. The present invention also includes the method of relieving the tension in the belt as it travels around the drive sprocket by moving the links of the chain toward one another into a closer longitudinal spacing between each other during portions of their path of travel about the sprocket than the longitudinal spacing between the links as they enter and exit from the sprocket. Other advantages and attainments of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings in which there is shown and described an illustrative embodiment of the invention. BRIEF DESCRIPTION OF THE DRAWINGS In the course of the following detailed description reference will be frequently made to the attached drawings in which: FIG. 1 is a diagrammatic plan view of the conveyor system embodying the principles of the present invention. FIG. 2 is a fragmentary side elevational view of the conveyor system. FIG. 3 is an enlarged sectional view of a carriage as taken along line 3--3 of FIG. 2. FIG. 4 is a side elevation view of the carriage shown in FIGS. 2 and 3. FIG. 5 is a top plan view showing the arrangement of the carriages as they pass around a horizontal curve. FIG. 6 and 7 show an end view and a side elevational view respectively of one end structure of one of the side members which form a portion of the limiting means. FIG. 8, 9 and 10 respectively show the top plan, side elevational and end view of the other one of the end structures that form the other portion of the limiting means. FIG. 11 shows, on a somewhat enlarged scale, one of the articulated joints used for suspending the carriages from the monorail. FIG. 12 is an end view of the articulated joint as seen along line 12--12 in FIG. 11. FIG. 13 is an enlarged side elevational view of the drive traction means seen in FIG. 2. FIG. 14 is a top plan view of the drive traction means shown in FIG. 13. FIG. 15 is a sectional view of the drive traction means as taken along line 15--15 on FIG. 13. FIG. 16 is an enlarged side elevational view of the take-up carriage shown in FIG. 2. FIG. 17 is a top plan view of the take-up carriage of FIG. 16 showing the hydraulic cylinders. FIG. 18 is a sectional view of the take-up carriage as taken along line 18--18 of FIG. 16. FIG. 19 is an end view showing the outby terminal positioned above the panel belt conveyor as seen from line 19--19 in FIG. 2. FIG. 20 is a side view of the drive sprocket in engagement with the belt drive chain. FIG. 21 is an enlarged side elevational view of the inby terminal as seen in FIG. 2 showing in dotted lines the pivoted movement thereof and with the load discharge end of the bridge conveyor being shown in its elevated overlyng position above the inby terminal. FIG. 22 is a top plan view of the inby terminal with the hopper removed. FIG. 23 is a sectional view of the inby terminal as taken along line 23--23 in FIG. 22. FIG. 24 is a top plan view of the bridge conveyor as shown in FIG. 2 showing the steerable wheels in two different positions. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In the following description, it is to be understood that such terms as "forward", "rearward", "left", "right", "upward", "downward", etc., are words of convenience and are not to be construed as limiting terms. In General Referring now to the drawings, and particularly to FIGS. 1 and 2, there is shown a conveyor system having a mobile articulated conveyor which is adapted to be suspended from overhead rail means, such as a monorail, and which is capable of traversing a curvilinear path. The conveyor system is indicated generally by the numeral 10 and comprises the preferred embodiment of the present invention. As shown in FIGS. 1 and 2, the conveyor system 10 generally includes an articulated conveyor having an orbital conveying belt 12 carried by a train of tandemly disposed, carriages 14 with an outby terminal 16 located at one end of the train and an inby terminal 18 located at the opposite end of the train; means 20 cooperable with each of the carriages 14 and the overhead supported rail means, such as monorail 22, for pivotally interconnecting the carriages 14 and suspending the carriages from the monorail 22; traction drive means 24 cooperable with the overhead monorail 22 and being connected to at least one of the carriages 14 for moving the train of carriages along the path defined by the monorail. An extendable/retractable unit, referred to herein as a take-up carriage 26, is interposed between a pair of adjacent carriages 14 or between the outby unit 16 and the traction drive unit 24 (as shown in FIG. 2) to increase or decrease the length of the carriage train to thereby provide proper tensioning of the orbital belt 12. Further, a bridge conveyor, generally indicated by the numeral 28, is connected to the inby terminal end of the carriage train for unitary movement therewith. The bridge conveyor 28 has one end, the discharge end 30, suspended from the monorail 22 and positioned above the inby terminal 18, whereas the other end, the material loading end 32, is supported on a pair of steerable wheels 33, 34 (only the right wheel being shown in FIG. 2). The various controls for controlling the operation of the conveyor system 10 are housed within a control box 36 which is also suspended from the monorail 22 and is connected to the outby terminal 16 end of the carriage train. The control box 36 forms no part of the present invention and its specific structure will not be discussed in detail. Suffice it to say that it is a box or housing of conventional nature that houses the various control components for regulating the operation of the conveyor system. Also seen in FIG. 2, is a stationary panel belt conveyor, being generally indicated by the numeral 38, of conventional construction and forming no part of this invention. The panel belt conveyor 38 is supported on the mine floor and positioned below the outby terminal 16 for receiving mined material discharged therefrom. As will be readily understood by those skilled in the art, the outby discharge terminal of the carriage train may reciprocate along the monorail 22, back and forth, over the panel conveyor 38 as the other end of the conveyor system, the bridge conveyor 28 follows a continuous miner (not shown) as it proceeds around horizontal and vertical curves from room to room, between pillars P, in extracting the mineral from the mine face, as seen in FIG. 1. For illustration purposes, in the preferred embodiment, the orbital conveying belt 12 is of the type disclosed and claimed in the U.S. patent of Harry R. Becker, entitled "C0NVEY0R BELT CHAIN AND METHOD FOR ITS USE" having U.S. Pat. No. 4,282,971 and issued on Aug. 11, 1981. The Becker belt is a precontrolled stretchable belt formed of a stretchable elastic material having a chain attached to the longitudinal centerline thereof for controlling the amount of prestretch of the belt as well as for driving the conveyor belt. However, it should be noted here that the conveyor system of the present invention is not limited to the incorporation of such a controlled prestretch belt, nor an elastic material belt per se, but includes a wide variety of types of conveying orbital belts. The various above-mentioned components of the conveyor system 10 will now be described in further detail hereinafter. Carriages As discussed above, a plurality of carriages 14 are disposed below the monorail 22 and arranged in single file fashion to form a carriage train. Each of the carriages 14 is constructed so as to define an open extent extending generally longitudinally through the train thereof with each carriage 14 mounting means for supportinq an orbital belt within the open extent of the carriage train. Since, in the preferred embodiment, all of the carriages 14 are identical, only one will be discussed in detail. As seen in FIGS. 3 and 4, each carriage 14 includes a framework having an upper elongated tubular link member 40 and a pair of downwardly projecting, generally inverted U-shaped members depending from and spaced apart along the tubular link member 40. Each of the U-shaped members have left and right leg portions 42, 44 (only the right leg portion 44 of each U-shaped frame member being seen in FIG. 4) respectfully defining the outer lateral sides of the open extent and being interconnected by an upper bight portion 46 defining the upper boundary of the open extent. The U-shaped frame members are constructed from a flat metal bar and are longitudinally spaced along and inwardly from the respective ends of the elongated tubular link member 40. More specifically, the elongated tubular link member 40 is secured to the undersurface of the bight portion 46 of the respective frame members by welding or the like, and preferably, the tubular link member 40 is positioned centrally of each bight portion. For increased strength, webs 48 are welded between the tubular link member 40 and the respective bight portions. When each carriage 14 is suspended from the monorail 22 in a manner to be described below, its elongated tubular link member 40 is disposed a relatively short distance below and generally parallel to the monorail 22. As also seen in FIGS. 3 and 4, the framework of each carriage 14 includes left and right longitudinally the opposite sides of the open extent and positioned generally at a lower level than the elongated tubular link member 40. The left side member 50 extends, generally horizontally, across the lower edge of the left leg portions 42 of the pair of frame members associated with a respective carriage whereas the right side member 52 extends, generally horizontally, across the lower ends of the right leg portions 44 of the pair of frame members associated with the same carriage. Preferably, the left and right side members 50, 52 are oriented generally parallel to one another and generally parallel to the elongated tubular link member 40. In the preferred embodiment, the longitudinal axis of the side members 50, 52 and the longitudinal axis of the elongated tubular link member 40 associated with each carriage 14 form the apices of an isosceles triangle. A plurality of rollers comprise the means mounted on each carriage 14 for moveably supporting the orbital conveying belt within the open extent of the carriage train. An upper series of rollers are provided for supporting the upper conveying run portion 12a of the belt 12 and a lower series of rollers are provided for supporting the lower return run portion 12b of the belt 12. The rollers are supported on left and right brackets 54, 56 respectively (as seen in FIG. 3) which project inwardly into the open extent from the respective leg portions 42, 44 of each frame member. Each of the brackets 54, 56 is formed by a pair of spaced apart plates suitably fastened to the outer edges of the respective leg portion. The plates are identical and irregular in shape forming cantilever arms that project into the open extent. In the preferred embodiment, the upper conveying run portion 12a of the belt 12 is supported by respective left and right troughing idlers 58, 60 and a centrally disposed dumbell idler 62 so as to maintain the belt 12 in a cross-sectional trough-shaped configuration, as shown in FIG. 3. The left troughing idler 58 is rotatably mounted on the cantilever arm portion of the left bracket 54 by a pair of spaced plates 64, 65 transversely disposed between the bracket side plates. The upper end of each mounting plate 64, 65 is notched to receive the respective shaft ends of the idler 58. The right troughing idler 60 is similarly rotatably mounted between the bracket side plates which form the cantilever arm portion of the right wing bracket 56 by a pair of similar notched mounting plates 66, 67. For the sake of clarity, the left and right troughing idlers 58, 60 along with their respective mounting plates 64-67 have not been shown in FIG. 4. The dumbell idler 62 is transversely disposed between the respective cantilever arm portions of the left and right brackets 54, 56 and rotatably supported on notched plates 68, 69 secured between the side plates that form the respective arm portions. Idler 62 takes on the dumbell shape so as to accomodate space for the chain that is attached to the belt 12 which will be discussed later in more detail. As can be easily understood, such mounting of the troughing idlers 58, 60 and dumbell idler 62 permits easy removal of same and ready access to belt 12. For maintaining the upper conveying run portion 12a of the orbital belt 12 in an operative position on the troughing idlers 58, 60 and the dumbell idler 62, each carriage 14 is provided with respective left and right upper edge idlers 70, 72 which, in the preferred embodiment, are of capstan shape. The left edge idler 70 is rotatably supported between the upper portion of the side plates that form the left bracket 54 whereas the right edge idler 72 is rotatably supported between the side plates that form the right bracket 56. As best seen in FIG. 3, the left and right edge idlers 70, 72 project into the open extent, toward one another, and are generally horizontally disposed having their tapered flange portions being disposed adjacent the respective outer edges of the orbital belt 12. The return run portion 12b of the orbital belt 12 is supported on a transversely disposed return idler 74 rotatably mounted on respective left and right mounting plates 76, 78 which are also notched to receive the respective left and right ends of idler shaft 80. The mounting plates 76, 78 are suitably secured between the flange of a channel member 82 that interconnects the lower ends of the respective left and right leg portions 42, 44 of each U-shaped frame member. The respective ends of the channel member 82 are attached to the respective leg portions by pins 84, 85 that pass through aligned apertures provided in the flange of the channel member and through the side plates that form the left and right brackets 54, 56. The belt return run portion 12b is maintained on the return idler 74 by left and right edge idlers 86, 88 rotatably supported on a lower portion of respective left and right brackets 54, 56. As seen in FIG. 3, the lower edge idlers 86, 88 are disposed below the cantilever arm portions of the respective brackets and are so positioned as to engage the outer edges of the return run portion 12b of the belt 12. It should be appreciated another feature of the invention is that the mounting of the return idler 74 provides easy access to the belt 12 as well as easy access to the upper conveying run idlers 58, 60 and 62. The return idler 74 can be easily removed by removing the channel member attaching pins 84, 85, whereas, the upper conveying run idlers 58, 60 and 62 can be removed by lifting them out of their respective notched mounting plates. Preferably, as seen in FIG. 4, the upper conveying run idlers 58, 60, 62 and the return run idler 74 are so positioned that the respective axes thereof lie in a generally vertical plane. Each carriage 14 is further provided with means for limiting the lateral movement of one carriage relative to the aligned position of an adjacent carriage to thereby maintain the conveying run portion 12a of the orbital belt 12 in a predetermined operative mode as the train of carriages are moved along the overhead monorail 22. In the preferred embodiment, the limiting means are provided on the respective ends of each side member 50, 52 of each carriage. The limiting means of one side member end of a respective carriage, cooperates with the adjacent end of the side member carried by the adjacent carriage such that each carriage can only move laterally a limited amount independently of the lateral movement of the adjacent carriage and thereafter the carriages move together in common movement. As seen in FIG. 4, on the left end of the right side member 52 the limiting means takes the form of a generally upright plate 90 (see FIGS. 6 and 7) secured to the terminal end of the side member. Mounted on the right end of the right side member 52 the limiting means takes the form of an L-shaped configuration, being generally indicated by the numeral 92, formed from an upper plate 92a that slants upwardly and outwardly from the terminal end and a side plate 92b that slants away and outwardly from the terminal end (see FIGS. 8, 9, 10). On a straight-run section of the monorail 22, wherein the carriages 14 are generally aligned with the longitudinal centerline of the respective side members of adjacent carriages being in alignment, the respective limiting means cooperate such that the L-shaped plate structure 92 of one side member end partially surrounds the upright plate structure 90 of the adjacent side member end. In such straight line positions the respective cooperating plate structures are in a non-contacting relationship; however, in a curve section of the monorail 22, such as seen in FIG. 5, wherein one carriage is angularly disposed relative to an adjacent carriage, the respective cooperating plate structures of adjacent right side members 52 are in engagement thereby transferring the load of one carriage onto another which tends to retard the swinging movement of one carriage relative to its adjacent carriage. Furthermore, the abutting relationship of the plate structures 90 and 92 also assists in retarding the lateral swing of adjacent carriages. As will be noted, the cooperating plate structures at the adjacent ends of adjacent left side members 50 are spaced farther apart than their relative position in a straight run section. The cooperation of the plate structures at the ends of the side members 50, 52 of adjacent carriages 14 as described above limits the lateral swinging movement of the carriages as they move along the overhead rail, thus providing a smooth path for the conveying run portion 12a of the belt 12. Means for Suspending and Connecting Carriages As described above, the carriages 14 are tandemly disposed, being connected to one another, and are suspended from the overhead monorail 22 as shown in FIG. 2. With specific reference to FIGS. 11 and 12, there is illustrated in greater detail the means for connecting the carriages and for suspending the carriages from the monorail. Secured to each end of each elongated tubular link member 40 of a carriage framework is a yoke member 94 that projects outwardly therefrom having an end portion which defines a concave ball receiving socket adapted to partially receive a ball, such as ball 96. As best seen in FIG. 11, the yoke members 94 associated with the adjacent ends of adjacent link members 40 are positioned around the ball 96 with an annular gap existing therebetween for retaining a lubricant therewithin. The respective yoke members 94 are clamped about the ball 96 by left and right blocks 98, 100 (see FIG. 12) each having a cavity therewithin such that when the blocks are clamped together they form a cavity which takes the shape of the outer periphery of the respective yoke members 94, and further define conical or tapered slot sections on opposite sides of the cavity which allow the link members 40 to move up and down in the vertical direction and from side to side in the horizontal direction whereby adjacent link members are permitted to move relative to one another. Fastening bolts 102 are used to hold the blocks 98, 100 together (see FIG. 12). As described, the above components form an articulated joint. Each of the blocks 98, 100 have integral trolley support members extending upwardly therefrom for rotatably supporting therebetween respective left and right pairs of trolleys or wheels 104, 106 which are cooperable with the monorail 22 for movement therealong. For centering the trolley wheels 104, 106 on respective sides of the I-shape monorail 22, left and right guide rollers 108, 110 respectively are provided for rolling contact with the respective sides of the web portion of the I-beam. The guide rollers 108, 110 are rotatably supported on pins 112, 114 that extend between upper and lower inwardly extending projections of the upright integral trolley support members. As will be easily understood by those skilled in the art, suspending of the carriages 14 from the articulated joints that connect the carriages permits the use of smaller joints in that the stress forces that are transmitted to the joints are transferred to the more rigid I-beam, thereby reducing wear and damage to the joints. Traction Drive Means Relocation of the conveyor system 10 along the overhead monorail 22 is achieved by actuation of the traction drive means 24 seen in FIGS. 13, 14 and 15. While in the preferred embodiment there is shown only one traction drive unit being interposed between two carriages; however, depending on the length of the conveyor and the elevated grade which it traverses, there may be several traction drive units associated with a conveyor. Furthermore, the traction drive unit may be located at either end of the conveyor, or, as shown in the preferred embodiment, the traction drive unit may be located between adjacent carriages. As best seen in FIG. 15, the traction drive means 24 basically includes a pair of transversely spaced apart left and right power units 114, 116 respectively disposed on opposite sides of the open extent of the carriage train, each unit having driveably coupled thereto a pair of traction drive wheels with the wheels being associated with the left power unit 114 being referred to by numeral 118, 119 while the drive wheels associated with the right power unit 116 being referred to by the numeral 120, 121. The respective drive wheels 118, 119 of the left power unit 114 are rotatable in opposite directions and cooperable With the opposite sides of the monorail 22 from that of the respective drive wheels 120, 121 of the right power unit 116. Since the specific components of the power units 114, 116 may be conventional, it should suffice to say that each drive unit has a housing which supports a motor and a drive train, such as a gear train or chain and sprocket drive, that transmit power from the motor to the drive shafts which support the respective drive wheels for rotation of same. Such driven rotation of the drive wheels 118, 119, 120 and 121 results in movement of the traction drive means 24 along the monorail 22. As shown in the preferred embodiment, the left and right power units 114, 116 are identical in construction but are reversely orientated on opposite sides of the monorail 22. As stated above and as best seen in FIG. 15, the left and right power units 114, 116 are respectively disposed on opposite sides of the open extent of the carriage train having their respective housings projecting generally vertically and outwardly from the opposite sides of the open extent and with their respective drive components extending generally horizontally, and slightly above the upper boundary of the open extent, from the housing inwardly to the respective drive shafts for rotating the drive wheels 118, 119, 120 and 121. As seen in FIG. 14, stub arms 122, 124 are attached to one side of the left power unit housing 114 and projects inwardly therefrom and stub arm 126 is attached to the opposite side of the left power unit housing 114 projecting inwardly therefrom, whereas, corresponding stub arms 128, 130 and 132 are attached respectively to the opposite side of the housing of the other or right power unit 116 and project inwardly therefrom. The left and right units 114, 116 are pivotally coupled to one another by two pivot pins, one pin 134 passing through aligned aperatures provided in stub arms 122, 124 and 132 and the other pivot pin 136 passing through aligned apertures provided in stub arms 126, 128 and 130. As best seen in FIG. 15, the above described pivot connection of the left and right power units 114, 116 is disposed a relatively short distance below the monorail 22 with the axis of the pivot pins 134, 136 lying generally within a vertical plane that passes through the longitudinally centerline of the I-beam web section. As best seen in FIG. 15, means in the form of an actuator assembly, generally indicated by the numeral 138, have been provided to pivot the left and right power units 114, 116 and therewith the left and right pairs of drive wheels 118, 119, 120 and 121 toward and away from one another and about the pivot pins 134, 136 so as to maintain the drive wheels 118, 120 in drive traction relationship with the overhead monorail 22. The actuator assembly 138 is pivotally interconnected between the lower ends of left and right leaf springs 140, 142 respectively, the left leaf spring 140 is attached at one end to the bottom of left power unit housing 114 and projects downwardly therefrom, while the right leaf spring 142 is attached to the bottom of the right power unit housing 116 and projects downwardly therefrom. The actuator assembly 138 extends transversely between the lower ends of the springs 140, 142 and includes a transversely disposed cylinder 144, preferably hydraulic, having its cylinder end pivotably connected to the right leaf spring 142 by right pin 146. The piston rod end is threadably connected to one end of a threaded extension rod 148 that has its other end pivotally connected to the left leaf spring 140 by left pin 150. Fastening nuts 152 are threaded on the extension rod and piston rod and operable so as to lock the actuator assembly 138 in selected ones of the expanded and retracted positions of the hydraulic cylinder 144, thus retaining the power units 114, 116 in their relative pivoted positions in cases where a hydraulic leak occurs and the cylinder 144 looses pressure. The operation of the actuator assembly 138 is such that upon extension of the cylinder 144, the power units 114, 116 pivot about the pivot pins 134, 136, with the lower ends of the power units being forced away from one another and with the upper ends moving closer to one another thereby causing the left and right pairs of drive wheels 118, 119, 120 and 121 to move toward one another, squeezing and pinching the monorail 22 therebetween and thus, resulting in drive traction relationship. Retraction of the cylinder 144 causes reverse pivot rotation of the power units, thereby resulting in less pressure being applied by the drive wheels 118-121 against the monorail 22. The primary purpose of the leaf springs 140, 142 are to alleviate shock loading to the drive components associated with the drive wheels 118-121 as may be experienced in such circumstances wherein the sections of monorail 22 are not in perfect alignment which would tend to create an excessive force on the various connections and components when the drive wheels pass over such a disjointed rail juncture. The traction drive means 24 further includes a framework, generally indicated by the numeral 154, having an open extent extending longitudinally therethrough and in general alignment with that of the carriage train for accommodating the orbital belt 12 in a manner similar to that of the above described carriages 14. The framework 154 is similar in structure to the carriages 14 but is modified to some extent for space allowance for the power units 114, 116. Furthermore, it will be seen from the following description that the framework 154 is connected to the carriages 14 and interconnected to the power units 114, 116 so as to transmit the movement force from the power units 114, 116 to the carriages 14 free from binding and other deleterious forces which normally would be associated with, or result from, moving a rigid member through a horizontal curve. For clarity and to facilitate the understanding of the description, the end of the framework as seen in FIG. 13 toward the right side of the drawing will be referred to as the front end of the framework whereas the end of the framework on the left side will be referred to as the rear of the framework. Now, with particular reference to FIGS. 13 and 14, the framework 154 is comprised of respective upper and lower longitudinally extending box shaped tubular side frame members 155, 156 and 157, 158 disposed on opposite sides of the open extent and interconnecting front and rear longitudinally spaced apart upright members 160, 162 respectively, disposed adjacent the opposite sides of the open extent (only the upright members on the right side are shown in FIG. 13). Mounted to and extending upwardly and rearwardly from the rear end of each of the upper side frame members 155, 156 is a diagonal plate 164 while another diagonal plate 166 extends upwardly and forwardly from the front end of each of the upper side frame members 155, 156. Spanning between the front and rear diagonal plates 164, 166 are front and rear transverse frame members 168, 170 respectively, the front frame member 168 being positioned a short distance forward of the front portion of the power units 114, 116 and the rear frame member 170 being positioned a short distance rearwardly of the rear portion of the power units 114, 116. Mounted on the forward face of the front frame member 168 and on the rearward face of the rear frame member 170, and downwardly a short distance from the vertex of each member, are outward projecting yokes which may be identical to those previously described yoke members 94 carried by the carriages 14 that form the above described articulated joint 20 for suspending the carriages 14 from the monorail 22. Still referring to FIG. 13, secured to the front end of each of the lower side frame members 157, 158 and projecting generally downwardly and forwardly therefrom are lower front diagonal plates 172 that support front side member extensions 174, 175 which are vertically offset to the respective lower frame members 157, 158. Mounted on the outward end of the forward extensions 174, 175 are L-shaped plate structures identical to those plate structures 92 carried by the carriages 14 that form a portion of the cooperating limit means. Similar diagonal plates 176 are secured to the rear end of the lower side frame members 157, 158 for supporting vertical offset rearward extensions 178, 179 which have supported thereon the upright plate structure 90 as described above that forms the other cooperating portion of the limiting means. As seen in FIGS. 13 and 14, the power units 114, 116 are connected to the framework 154 by front and rear flexible members illustrated as chains 180, 182 respectively. The front chain 180 is connected to a eyelet 184 mounted on the rear face of the front frame member 170 while the other end of the chain is connected to eyelet 186 mounted on the right pivot pin 136. The rear chain 182 is similarly connected to a eyelet 188 mounted on the front face of the rear frame member 168 and eyelet 190 mounted on pivot pin 134. The traction drive unit as shown in FIG. 13 is depicted in an operative mode wherein the carriages 14 are moved or driven in the forward direction, further into the mine, which would be toward the right as seen in FIG. 2, and thus, the rear chain 182 is under tension whereas the front chain 180 is relaxed. In such forward movement, the carriages 14 to the left of the power units 114, 116 are pulled along the monorail 22 whereas the carriages 14 to the right of the power units 114, 116 are pushed along the monorail 22 by the forces transmitted from the carriage on the left and thru the framework 154 of the traction drive means. In other words, as the power units 114, 116 move forwardly, the line of force, of the carriages to the left, is through the rear chain 182 and through the successive elongated tubular link members 40 associated with each of said carriages. The line of force for the carriages on the right (those being pushed) is through the rear chain 182, down through the rear diagonal side plates 164, across the upper side frame members 155, 156, up through the front diagonal plates 166 and to the elongated tubular link member associated with the carriage on the right of the power units. In the reverse direction wherein the power units 114, 116 are reversely operated to drive the carriages out of the mine (to the left), the rear chain 182 is now in a relaxed condition whereas the front chain 180 will now be in tension and the force lines are opposite to those described in the forward direction. It will be appreciated by those skilled in the art, that the above described drive coupling relationship of the power units 114, 116 and carriages is such that any deterious forces which may result from the power units moving along the monorail 22 such as the reaction forces of the power units per se produced when the power units move over a disjoined rail section are not transmitted to the framework 154 or the carriages 14. Such mounting arrangement permits the power units 114, 116 freedom of movement relative to the framework 154 in that there are no rigid connections between the two, but only the connection of the chains 180, 182. Furthermore, such chain connections between the power units and the carriages allow the power units to move more freely around a curved section of the monorail rather than would be the case were the power units rigidly connected to the framework. The framework 154 of the traction drive means 24 also includes parts that support the orbital belt 12 in a manner similar to that of the carriages 14. For example, left and right brackets (not shown) which may be identical in construction to those described in the above described carriage section, are carried respectively by the front and rear upright frame members 160, 162. For the sake of brevity, it should suffice to say that the brackets, as described above, rotatably support the idlers (not shown in FIGS. 14 and 15) associated with the upper conveying run portion 12a of the belt 12 as well as the reverse run portion 12b of the belt. It will be appreciated by those skilled in the art, that the specific configuration of the traction drive means 24 just described allows for a low profile unit having a height which is approximately equal to that of the carriages, thus permitting operation thereof in confined areas wherein the vein of coal is of low height. Take-up Carriage As briefly mentioned hereinabove, the conveyor system 10 is provided with a take-up carriage, being generally indicated by the numeral 26, that is similar in construction to the standard carriage 14 described above but which is adapted to expand and retract in the longitudinally direction so as to increase or decrease the overall longitudinal length of the carriage train. Such expandable/retractable take-up carriage, when associated with a conveyor system of the type shown in the preferred embodiment having a controlled prestretched conveying belt, serves as a means for maintaining the controlled prestretch of the belt under such conditions where the belt chain becomes worn. In addition, when it is desired to decrease the amount of tension in the belt for making repairs, the take-up carriage 26 can be retracted to shorten the length of the carriage train and thereby reducing the tension in the belt 12. Although, in the preferred embodiment as shown in FIG. 2, the take-up carriage 26 is interposed between the outby terminal 16 and traction drive means 24, the take-up carriage 26 may be interposed between adjacent carriages 14 or it may be interposed between the inby terminal 18 and an adjacent carriage. Furthermore, even though only one take-up carriage 26 is shown, there may be more than one in a given carriage train. As seen in FIGS. 16, 17, and 18, the take-up carriage 26 includes a framework similar to that of a standard carriage but which has been divided into two substantially identical portions (FIG. 16), the portion on the right being referred to as the front portion and generally indicated by the numeral 192, and the portion to the left being referred to as the rear portion and generally indicated by the numeral 194. The right or front portion 192 is a mirror image of the left or rear portion 194 (with the exception of the limiting plate structures 90, 92), that is, it is reversely oriented relative to the left or rear portion such that the portions are symmetrical about a transversely extending vertical plane that passes through the longitudinal midsection of the take-up carriage 26. The overall configuration of the take-up carriage 26, when the front and rear portions 192, 194 are coupled together, is similar to the configuration of a standard carriage 14. The front and rear portions 192, 194 of the take-up carriage 26 each include a downwardly projecting U-shaped frame member 196 respectively having their respective leg portions disposed adjacent the opposite sides of the open extent of the carriage and with its respective bight section disposed adjacent the upper boundary of the open extent. An elongated tubular link member 198 having a yoke 200 on one end is secured to the undersurface of the bight section of each of the respective U-shaped members 196. The yoke ends of the link members 198 extend in a direction away from the opposite longitudinal ends of the take-up carriage 26 and are identical to the yoke members 94 of the standard carriage 14. As in the case of the standard carriage 14, the yoke 200 forms a component of each of the above described articulated joints 20 which suspends the take-up carriage 26 from the monorail 22. As best seen in FIGS. 16 and a short distance past or beyond the respective U-shaped members. The link member 198 of the front and rear portions 192, 194 telescope over an elongated insert tube 202 which is provided with apertures spaced along its longitudinal extent and with a central collar 204 formed about the periphery thereof and located generally at the midsection of the insert tube 202 for centering the insert tube 202 between the ends of the link members 198. For connecting the link members 198 on the centrally positioned insert tube 202 so as to retain the front and rear frame portions 192, 194 in desired spaced apart location, pins (not shown) are passed through apertures provided in the link members 198 and through corresponding apertures of the insert tube 202. Supported on the lower leg portion of each of the frame members 196 of the front and rear portions 192, 194 of the take-up carriage 26 is an elongated side frame member 206, one being disposed on each opposite side of the open extent. The side members 206 are substantially identical to the side members 50, 52 of the standard carriage 14 and support on the respective ends thereof cooperating upright and L-shaped plate structures 90 and 92 that form the limiting means previously discussed. For telescopic connection of each of the respective front and rear side members 206, an elongated insert bar 208 is provided which is adapted to be inserted into the ends of the respective side members. The insert bar 208 is provided with spaced apertures therealong whereas each of the inner ends of the side members 206 are provided with an aperture. Connecting pins (not shown) are inserted through the apertures in the ends of the side members 206 and selected apertures in the insert bar 208 so as to retain the side members 206 in selected longitudinally spaced apart positions. As best seen in FIGS. 16 and 17, means, preferably, in the form of a pair of hydraulic cylinders 210, 212 are provided to couple the front and rear frame portions 192, 194 and are operational for moving the portions toward and away from one another. The left cylinder 210 (as seen in FIG. 18) is disposed adjacent the left side of the link members 198 and has its cylinder end pivotally connected to the rear portion link member by a pin 214 that passes through a pair of vertical spaced apart ear members 216 (see FIG. 18) that are secured to the side of the rear link member and adjacent the yoke end thereof while its piston rod end is pivotally connected to the front portion link member by a pin 218 that passes through vertically spaced ear members 220 (only the upper one being shown in FIG. 17) that are secured to the side of the front link member. The right cylinder 212 extends along the right side of the link members and is pivotally connected in a similar manner by pins 222, 224 passing through respective ear members 226, 228 provided on the right side of each of the front and rear link members. As can be readily understood, expansion of the cylinders 210, 212 causes the front and rear portions 192, 194 of the take-up carriage framework 26 to move away from one another, thus increasing the total length of the carriage train, resulting in an increase in the tension of the orbital belt 12 and tightening of the chain associated with the belt which has been elongated due to wear. Once the cylinders 210, 212 have extended to a preselected length, the front and rear framework portions 192, 194 are locked in their desired location by passing the connecting pins (not shown) through the side members 206 and associate insert member 208 as well as the connecting pins (not shown) through the link members 198 and the associated insert tube 202. The locking of the front and rear framework portions 192, 194 in their positions insures that they remain in their relative position should a hydraulic failure occur and the cylinders 210, 212 loose pressure. In situations where repairs are being made to the conveyor, the cylinders 210, 212 are retracted, thus decreasing the tension on the belt to thereby facilitate access to and handling of the belt. For moveably supporting the orbital belt 12 within the open extent, the take-up carriage 26 is provided with belt support means identical to the means associated with a standard carriage 14. Thus, for the sake of brevity, and to eliminate repetition in description, it should suffice to say that the belt support means associated with the take-up carriage 26 generally includes respective left and right brackets 230, 232 (see FIG. 18) mounted on the respective leg portions of each U-shaped frame members 196 that rotatably support an upper series of idlers for supporting the upper conveying run portion 12a of the belt and a lower series of rollers for supporting the low return run portion 12b of the belt. Outby Terminal As seen in FIGS. 2 and 19, with particular reference to FIG. 2, connected to the terminal carriage on the extreme left or outward end of the carriage train is a portion of the conveyor commonly known in the conveyor art as an outby terminal, being generally indicated by the numeral 16. This terminal is also suspended, in a like manner to the carriages 14, from the monorail 22 in an elevated position above the panel belt conveyor 38 for discharging of materials on same. The outby terminal 16 houses means for driving and reversing the direction of the orbital belt 12 and is basically conventional in structure having a framework composed of transversely spaced apart, longitudinally extending frame members 233, 234 (see FIG. 19) disposed on opposite sides of the open extent. The outward ends of the frame members 233, 234 are interconnected by a transversely extending hanger 236 while the opposite ends, or the inward ends of frame members 233, 234 are interconnected by a transversely extending, downwardly projecting, U-shaped frame member 238 as shown in FIG. 2 which similar to U-shaped frame member 196. Mounted to the outward face of hanger 236 and U-shaped member 238 is a short tubular link member 240 having a yoke end portion which forms a portion of the articulated suspension joint 20 associated with the adjacent carriage 14 on one end and a portion of the articulated joint 20 associated with the control box 36 on the other end. Mounted on each of the frame members 233, 234 and projecting forwardly therefrom toward the take-up carriage 26 is a short side member 242 (only the one on the right side being shown in FIG. 2) having mounted to its outward end an L-shaped plate structure, identical to those plate structures 92 associated with the carriages, for cooperating with the adjacent upright plate structure 90 on each end of the side members 206 associated with the take-up carriage 26. For funneling the mined material onto the panel conveyor 38, a pair of sheet metal skirts 243, 244 are provided on the outward end of the outby terminal 16, one skirt 243 being attached to the outward end of the side frame member 233 and shaped so as to divert the material inwardly toward the longitudinally centerline of the panel belt, whereas the other skirt 244 is attached to the opposite side frame member 234 and so shaped to direct the material in a similar fashion. Transversely extending between the side frame members 234 is an upper series and a lower series of longitudinally spaced rotatably mounted idlers 245 (only one of which is shown in FIG. 2) for respectively supporting the upper conveying and lower return run portions of the belt 12. It will be noted here that the upper conveying run portion 12a of the belt is normally trough shaped as it passes through the carriages 14, however, the conveying run portion flattens out as it passes around the outby terminal 16. Before discussing the means for driving the orbital belt 12, it should be pointed out again that the belt shown in the preferred embodiment is of the type shown and described in the aforesaid copending application of Harry R. Becker. Briefly, the belt 12 is comprised of an elongated web of resilient material having a chain 246 attached thereto and extending along the longitudinal length of the web. The chain 246 includes alternating C-shaped links which are attached to the belt and H-shaped links that connect the adjacent C-shaped links and which are adapted to be engaged by a twin-drive sprocket 248 which will be described in further detail hereinafter. Furthermore, the belt is classified as having a controlled prestretch, that is, the belt is in tension in its assembled position on the conveyor. The primary purpose of using a prestretched belt is to maintain the edges of the belt in tension when the belt passes around horizontal curves thereby maintaining the trough shape of the belt. Prestretching of the belt is accomplished by fastening the C-shaped links to the belt in its relaxed position whereby the H-shaped links are in loose connection. Then when the belt is installed on a conveyor, the chain links will be pulled apart by the maximum amount permitted by the loose link connection, to thereby stretch the belt to a predetermined elongation over its relaxed length. Details of the prestretched belt can be found in the above-reference application. Now, with reference to FIGS. 2 and 19, it will be seen that the belt drive means basically includes electric motors 249, 250 and associated conventional drive components being supported on and extending longitudinally along each of the side frame members 233, 234 of the outby terminal framework (only the motor and associated drive components on the right side are shown in FIG. 2). As best seen in FIG. 19, the respective motors 249, 250 and associated drives are driveably connected to respective left and right gear boxes 252, 254 located on the outward ends of the respective side frame members 233, 234 for transmitting rotary motion to a transversely extending drive shaft 256 that extends between the opposite side frame members. The gear boxes 252, 254 are driveably coupled to the respective ends of the shaft 256 with the drives being such that the shaft is driven in a counterclockwise direction as viewed in FIG. 2. Mounted on the drive shaft 256, midway betwcen the side frame members 234, are a pair of transversely spaced drive sprockets 248 adapted to engage the H-shaped connecting links of the chain 246 for thereby driving the chain and the belt therewith. The configuration of the drive sprockets 248 is unique and will be described in detail hereinafter. Supported on the shaft 256, adjacent each side of the pair of drive sprockets 248, are respective left and right self cleaning frusto-conical shaped drums 258, 260 which are so mounted as to freely rotate about the shaft 256. The frusto-conical shaped drums 258, 260 are so arranged and oriented on the shaft 256 such that the drums 258, 260 in combination with the drive sprockets 248, forces the belt 12 to take on a crown-shaped configuration. Crown shaped belt drives are well known in the art and are primarily used for centering of the belt on the idlers. Since the belt is prestretched, i.e. in tension, and passes over a crown shaped drive, the center of the belt (that portion of the belt disposed about the drive sprockets) travels at a faster speed than the marginal edge portions. However, the freely rotating side drums 258, 260 will allow the speed of the marginal edge portions to catch up with the center portions thereby substantially eliminating scrubbing of the edges of the belt as would normally occur with those drives wherein the side drums are fixed to the shaft for rotation therewith along with the rotation of the drive sprockets. Drive Sprockets As previously discussed, the chain 246 is attached loosely to the belt 12 in a relaxed mode, and then, when it is assembled into the train, the belt is stretched until the chain links are tight. When the chain 246 is in such taut condition, the belt is elongated approximately ten percent (10%). As the chain 246 passes over the drive sprockets 248, the belt travels on a greater radius than the chain and thus, an additional stretch load, in the range of approximately 36%, is imposed on the belt. The free rotating idler drums 258, 260 on each side of the sprockets 248 are tapered outward and are slightly smaller than the sprockets thereby giving a crowning effect to the assembly and functioning to relieve the stretch on the edges of the belt. The greatest concentration of tension in the belt 12 is in the area immediately over the chain 246 and between the chain and belt fasteners (not shown). The tension in this area has been relieved by approximately ten percent (10%) by the unique configuration of the drive sprockets 248 and their operative relationship with the chain 246 which will now be discussed in further detail. In discussing the drive, reference will be made to FIGS. 19 and 20 and particularly FIG. 20 wherein there is shown, for the sake of clarity, a portion of the chain 246 in drive engagement with a portion of one of the drive sprockets 248 (left sprocket), it being understood that the other one of the drive sprockets engages the opposite side of the chain in a like manner. As discussed above, the chain 246 consists of alternating H-shaped drive links and alternating C-shaped connecting links interposed between adjacent H-links. As seen in FIG. 20 and for simplicity in explanation, reference numerals 262, 264, and 266 have been assigned to three of the H-shaped links and reference numerals 268 and 270 have been assigned to the connecting links. Additionally, the letters "a" and "b" have been assigned respectively to the outwardly projecting cylindrical front and rear portions of each of the H-shaped links 262, 264, and 266. The chain per se is not a part of this invention and is described and claimed in the above referred to patent application. Furthermore, it should be said that this particular chain is shown for illustrational purposes only and is one type chain which cooperates with the drive sprockets 248, there being other such chains of different designs which will also cooperate with the drive sprockets so as to relieve the additional tension inparted to the prestretched belt 12 as it passes over the drive sprockets 248. Still referring to FIG. 20, the drive sprocket 248 is driven in a clockwise direction (as indicated by the direction arrow) and its unique configuration includes a plurality of alternating pitch drive teeth, being represented by numerals 272 through 282, formed about its periphery with the circular pitch between teeth 272-274, 276-278 and 280-282 being represented by "p"; and with the circular pitch between teeth 274-276 and 276-278 being represented by "p 1 "; "p" being greater than "p 1 ". It will also be noted that "p" represents the pitch of each of the H-shaped drive links 264, 266 and 268. As the chain passes over and partially around the sprocket 248, drive tooth 272 initially engages drive portion 262a of link 262. When the chain is taut and in its linear position, the distance between adjacent drive links is also "p" i.e. the distance between 262a of link 262 and 264b of link 264, and thus the pitch of the connecting links is "p". However, in the meantime, tooth 274 has engaged drive portion 264b of link 264. Then upon further rotation of the sprocket, tooth 274 forces the link 264 forward thereby causing a gap (non-contacting relationship) portion of the connecting link 270 thereby resulting in relaxation of link 270 toward link 268. Such relaxation of the chain beginning at tooth 276 allows contraction of the belt, thereby relieving the tension in the portion of the belt between the fastner elements (not shown) that attach the connecting links 268, 270 of the chain to the belt. A similar sequence of events occur with tooth 278 and link 264 as well as with the other preceding teeth and links. As a result, the total relaxation of all of the links of that portion of the chain passing over the sprocket teeth at any given point of time relieves the increased tension in the belt due to its passing over the drive sprockets 248. Inby Terminal Again referring to FIG. 2, connected to the terminal carriage on the extreme right or inward end of the carriage train is a portion of the conveyor system commonly known in the conveyor art as an inby terminal, being generally indicated by the numeral 18. The inby terminal 18 is similar in structure to the previously described outby terminal 16. In the preferred embodiment, the inby terminal 18 houses means for driving the orbital belt 12 from its opposite end which is substantially identical to the belt drive means associated with the outby terminal 16. Due to the length of the conveyor system, and thus the length of thc orbital belt 12, it has been found to be advantageous to drive the orbital belt 12 from each of its ends. Primarily, the belt drive means associated with the inby terminal 18 pulls the return run portion 12b of the belt and keeps this portion taut, whereas, the belt drive means associated with the outby terminal 16 pulls the upper conveying run portion 12a of the belt to keep it taut. As seen in FIGS. 21, 22 and 23 with particular reference to FIG. 22, the inby terminal 18 includes a support framework composed of a pair of transversely spaced elongated side plates disposed adjacent the opposite lateral sides of the open extent, the left side plate being referred to by the numeral 284 while the right side plate being referred to by the numeral 286. The inward ends (to the right as seen in FIG. 22) of the side plates 284, 286 are interconnected by upper and lower transversely extending vertically spaced cross bars 288, 289, with only the upper bar 288 being shown in FIG. 22. The outward ends (to the left) of the side plates 284, 286 are interconnected by a similar cross bar 290. Transversely extending between the side plates 284, 286 are an upper series of longitudinal spaced, conventional, impact idlers 292, for supporting the upper conveying run portion of the belt 12 and a lower series of longitudinal spaced, conventional idlers 294 for supporting the return run portion of the belt. Mounted on the lower portion of the outward (left) cnd of the side plates 284, 286 are short stub side members 295, 296 that project outwardly therefrom toward the adjacent carriage 14 for cooperation with the L-shaped plate structure 92 carried by the side members 52 of the adjacent carriage for purposes of limiting lateral movement of the carriage as previously described. The inby terminal 18 is also provided with a hopper 298 (not shown in FIG. 22) for directing the material discharge from the bridge conveyor 28 onto the conveying run portion of the orbital belt 12. The hopper 298 is supported on the top edge of the side plates 284, 286 and extends upwardly and outwardly therefrom with continuous transition portions extending above and between the side plates. Referring still to FIGS. 21, 22 and 23, as stated above, the belt drive means may be identical to the one associated with the outby terminal 16 and generally includes left and right electric motors 300, 302, respectively disposed adjacent the outer sides of the respective side plates 284, 286. The motors 300, 302 are driveably coupled, by conventional drive components, to respective left and right gear boxes or reducers 304, 306 attached to the other (inward) end of the side plates. The gear boxes 304, 306 are driveably coupled to the respective ends of a drive shaft 310 that transversely extends between the side plates 284, 286. The drive shaft 310 supports for rotary movement therewith a pair of drive sprockets (identical to previously described drive sprockets 248) for driveable engagement with the chain 246 which is attached to the longitudinal centerline of the belt. Additionally, the shaft 310 supports, on each side of the drive sprockets, a pair of self cleaning drums which are identical to drums 258, 260. As best seen in FIGS. 21 and 23, the inby terminal 18 is suspended from its end adjacent the carriage 14 by respective left and right brackets 312, 314 (only the right bracket 314 being seen in FIG. 21). The brackets 312, 314 are secured to the respective sides of an elongated tubular link member 316 which is disposed below the monorail 22 with the ends thereof forming portions of the articulated joints 20 which may be identical to those described previously. The brackets 312, 314 project downwardly and outwardly from the link member with their respective terminal portions being positioned adjacent the outer surface of the upper end portions of the side plates 284, 286. Each of the brackets 312, 314 is attached to a corresponding side plate by two pins, a forward attaching pin 318 and a rear pivot pin 320. As can be easily seen, the mounting of the inby terminal 18 is such that upon removal of the forward attaching pins 318, the inby terminal 18 can be pivoted about the pivot pins 320 upwardly from its operative mode position (as shown in full lines) to its inoperative transport mode position as shown in dotted lines in FIG. 21. Such pivoted mounting of the inby terminal 18 is necessary when it is desired to move the conveyor outwardly (to the left) of the mine, because the inward end of the inby terminal is positioned below the upper portion of the panel belt conveyor 38. It should also be easily recognized that before the inby terminal 18 is pivoted from its operative to inoperative mode, the bridge conveyor 28 must first be disconnected. Bridge Conveyor For dumping mined material on the orbital belt 12 at the inby terminal end of the carriage train, the conveyor system 10 also includes an elongated bridge conveyor 28 connected to the inward end of the carriage train, inwardly and adjacent to the inby terminal 18 (see FIG. 2). As seen in FIGS. 2 and 24, the bridge conveyor 28 is of conventional construction having a material receiving end 32 that follows a continuous miner (not shown) and a delivery end 30 positioned above and connected to the inby terminal 18 for delivering the materials from the mining machine to the orbital belt of the carriage train. The receiving end 32 of the bridge conveyor 28 is supported on a pair of remotely controlled steerable wheels 33, 34 whereas the delivery end 30 is connected in its elevated position to the inby terminal 18 with a swivel mechanism 330 thereby enabling the receiving end 32 to swing in a horizontal plane so as to follow the mining machine through its various maneuvers. Bridge conveyors are well known in the art and are of such common types as an endless belt, an apron conveyor, a flight conveyor, and the like. In the preferred embodiment of this invention, there is diagrammatically illustrated (FIGS. 2 and 24) an endless belt conveyor operably supported within an elongated framework having left and right sidewalls 332, 334. Rotatably supported between the sidewalls 332, 334 of the framework are several transversely extending belt support rollers 336 (only one of which being shown in FIGS. 2 and 24), drum rollers 338, 339 located at the terminal ends of the bridge conveyor, a belt drive drum 340 and a take-up drum or pulley 342 (see FIG. 2) which is operably associated with the drive drum 340. For simplicity, drive drum 340 and take-up pulley 342 have not been shown in Fig. 24. An endless belt 344 is entrained around these various drums and pulleys and is frictionally driven by the drive drum 340 which is rotated by conventional power units such as electric motors (not shown). For directing or funneling the mined material from the mining machine onto the bridge conveyor 18, a rectangular shaped hopper 346 is provided on the receiving end of the bridge conveyor. Additionally, supported on the receiving end 30 are the steerable wheels 33, 34 mounted on spindles that are attached to opposite sidewalls 332, 334 of the framework and which are inter-connected by a transverse tie rod 348. A hydraulic cylinder 350 having its piston rod connected to the tie rod 348 and its opposite end connected to a portion of the framework is provided for shifting the tie rod 348 and thus causing the wheels 33, 34 to turn in a conventional manner. The steering mechanism is only illustrative of any conventional well known mechanism and it should suffice to say that extension of the cylinder 350 causes the wheels 33, 34 to turn in one direction whereas retraction of the cylinder 350 causes the wheels 33, 34 to turn in the opposite direction. The hydraulic hose connection and controls have not been shown but it is understood that movement of the wheels 33, 34 can be controlled from a remote location such as by an operator positioned in a location adjacent the inby terminal 18. The other end of the bridge conveyor 28, the delivery end 30, is positioned above and connected to the inby terminal 18 and suspended from the monorail 22 by the swivel mechanism 330 that includes an arcuate shaped tongue or clevis having its respective ends attached to the end of the framework by attaching pins 351, 352 (see FIG. 24). A horizontal plate 354 is secured along the bight portion of the tongue and is provided with an aperture for receiving a vertical pivot pin 356 that extends upwardly therethrough and through an aperture in an elongated tubular link member 358 that is supported by longitudinally spaced articulated joints of the types previously described. As can be readily appreciated, the mounting of the bridge conveyor 28 is such that it moves in unison with the movement of the carriage train and inby terminal 18 and that the receiving end 32 thereof, due to the swivel coupling 330, can swing to side to side to thereby follow the mining machine. It is thought that the invention and many of its attendant advantages will be understood from the foregoing description and it will be apparent that various changes may be made in form, construction and arrangement of the conveyor system without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinabove described being merely a preferred or exemplary embodiment thereof.

An improved drive sprocket for driving a chain is set forth. The drive sprocket contains a plurality of peripheral drive teeth having a leading drive surface thereon. The sprocket has a first pair of teeth spaced a predetermined circumferential distance from each other on a pitch circle about the sprocket and a third tooth being spaced a distance less than the above mentioned predetermined distance from the trailing tooth of the first pair of teeth. The leading drive surface of each tooth engages and drives the chain around the sprocket.

CONTINUING DATA [0001] The present application is a continuation-in-part of U.S. patent application Ser. No. 13/231,077 filed Sep. 13, 2011 which is a continuation-in-part of U.S. patent application Ser. No. 12/924,628 filed Sep. 30, 2010 which claims priority to the following: [0000] (1) U.S. Provisional Patent Application No. 61/277,871 filed Sep. 30, 2009; (2) U.S. Provisional Patent Application No. 61/281,046 filed Nov. 12, 2009; (3) U.S. Provisional Patent Application No. 61/336,242 filed Jan. 19, 2010; (4) U.S. Provisional Patent Application No. 61/339,273 filed Mar. 2, 2010; which is further a continuation-in-part of U.S. patent application Ser. Nos. 12/806,114; 12/806,117; 12/806,121; 12/806,118; 12/806,126; 12/806,113, all filed Aug. 5, 2010, all of which claim priority to: (1) U.S. Provisional Patent Application No. 61/273,518 filed Aug. 5, 2009; (2) U.S. Provisional Patent Application No. 61/273,536 filed Aug. 5, 2009; (3) U.S. Provisional Patent Application No. 61/277,871 filed Sep. 30, 2009; (4) U.S. Provisional Patent Application No. 61/281,046 filed Nov. 12, 2009; (5) U.S. Provisional Patent Application No. 61/336,242 filed Jan. 19, 2010; (6) U.S. Provisional Patent Application No. 61/339,273 filed Mar. 2, 2010; all of which are further continuations-in-part of U.S. patent application Ser. No. 12/803,805 filed Jul. 7, 2010 which claims priority to: (1) U.S. Provisional Patent Application No. 61/224,904 filed Jul. 12, 2009; (2) U.S. Provisional Patent Application No. 61/273,518 filed Aug. 5, 2009; (3) U.S. Provisional Patent Application No. 61/273,536 filed Aug. 5, 2009; (4) U.S. Provisional Patent Application No. 61/277,871 filed Sep. 30, 2009; (5) U.S. Provisional Patent Application No. 61/281,046 filed Nov. 12, 2009; (6) U.S. Provisional Patent Application No. 61/336,242 filed Jan. 19, 2010; (7) U.S. Provisional Patent Application No. 61/339,273 filed Mar. 2, 2010; which further is a continuation-in-part of U.S. patent application Ser. No. 12/360,467 filed Jan. 27, 2009; and which further is a continuation-in-part of U.S. patent application Ser. No. 12/584,143 filed Sep. 1, 2009 which claims priority to U.S. Provisional Patent Application No. 61/094,595 filed Sep. 5, 2008. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] This invention relates to illumination devices and, more particularly, to controlling illumination devices. [0004] 2. Description of Related Art [0005] A wide variety of lighting control systems are currently commercially available for controlling a variety of lighting features from simple on/off switching to complex color adjustment and performance monitoring. Such systems also communicate according to a wide variety of protocols over various communication channels. As an example, a simple system could be just a triac dimmer and a single lamp. As another example, a complex system could be a hierarchical campus wide network. In such a complex system, up to 64 intelligent fluorescent lamp ballasts within a room or group of rooms could be wired together using the Digital Addressable Lighting Interface (DALI) standard, for instance, with an Ethernet enabled DALI controller, which then communicates with other DALI controllers and a computer server over Ethernet within each building. At the top layer of the hierarchy, the computer servers in different buildings within a campus could communicate over the Internet using Internet Protocol (IP). [0006] Some lighting control systems use protocols that are somewhat specific to lighting, such as 0-10V, DMX512, DALI, and Dynalite, while others use protocols that target building automation in general, such as X10, LonWorks, C-Bus, and ZigBee. Still other lighting control systems use industry standard networking protocols such as Ethernet, Wi-Fi, and HomePlug. At the campus wide level with communication over the Internet, such complex lighting control systems can also use telecom networking protocols such as SONET and ATM. All theses standards and protocols communicate at different rates, using different modulation and packetizing schemes, over various communication channels. Such channels include powerline for X10 and HomePlug, RF for ZigBee and Wi-Fi, optical fiber for SONET, and dedicated wires for most of the others including 2 wire DC for 0-10V, twisted pair for DALI and others, and CAT5 for Ethernet. [0007] The 0-10V standard was one of the earliest and simplest lighting control signaling system, which is still supported by many fluorescent ballasts produced by companies such as GE, Philips, and Sylvania. Such ballasts produce light from an attached fluorescent lamp that is proportional to the DC voltage input to the ballast through two wires. Although simple to understand and implement, each ballast must have a dedicated cable to the system controller, which can become very expensive and cumbersome in large installations. Additionally, such a lighting control system can only control light level and cannot extract information from the ballast, such as if a bulb has burned out. [0008] The DMX512 stands for “Digital Multiplex with 512 pieces of information” and is a standard for digital communication commonly used in theaters and production studios. DMX512 communicates over shielded twisted pair cable using EIA-485 standard voltages levels with node connected together in a daisy chain manner. Data is sent one byte per packet at 250 kbaud in a manner similar to RS232. The DMX512 protocol is popular for stage lighting due to the robustness of its cable and the relatively long communication distances. [0009] The DALI standard, which is becoming relatively popular for commercial lighting systems, is similar to DMX512 in that various lamps can be individually controlled using a relatively low data rate digital control bus, however, there are many differences ranging from the type of communication cable and interconnections to data format and messaging requirements. While DMX512 communicates uni-directionally over shielded twisted pair cable between two nodes, DALI communicates bi-directionally over un-shielded twisted pair that can be tapped by up to 64 devices. While all DMX512 data frame comprise one start bit, 8 data bits, and two stop bits, DALI has different sized frames for communication in the different directions with both acknowledge and data bytes in one direction and no acknowledge in the other direction. [0010] Unlike DALI, DMX512, 0-10v, and other protocols developed specifically for lighting, X10 was developed for general home automation of which lighting is an important subset. A further substantial difference is that X10 typically communicates data over the power lines that are already connected to most devices. X10 devices typically communicate one bit of information around each zero crossing of a 50 or 60 Hz AC mains cycle, by coupling bursts of a high frequency signal onto the powerline. As such, the data rate is very low. To compensate, the protocol is very simple in which all packets consist of an 8 bit address and a 4 bit command. Since only 16 commands are possible, functionality is limited. [0011] HomePlug is another protocol that uses the power line for communication, however, unlike X10, which was architected for home automation, HomePlug was designed to allow products communicate with each other and the Internet through existing home electrical wiring. A variety of versions of HomePlug have been released with data rates ranging from 10 to 200 Mbit/s. HomePlug achieves such data rates using adaptive modulation and complex error correction algorithms on over a thousand Orthogonal Frequency Division Multiplexed (OFDM) sub-carriers. [0012] Data in a HomePlug network is typically communicated in Ethernet compatible packets, which comprise of a header with about 22 bytes, the payload with up to 1500 bytes, and a CRC code with 4 bytes, however, HomePlug also provides a variety of higher level services that provide, among other things, guaranteed delivery, fixed latency, quasi-error free service, and jitter control. As such, a HomePlug interface is much more complicated than is needed for simply lighting control. [0013] Although communication over a power line is a good solution for some building networking applications, there are some drawbacks. For instance, there can be excessive attenuation between different phases of typically three phase systems, which can be overcome by active repeaters or sometimes with special capacitors. Additionally, signals can propagate through the power line between different buildings causing interference and security concerns. When appliances turn on and off significant noise is generated that can corrupt transmission. HomePlug physical layer interfaces have overcome some of such issues at the expense of complex analog and digital signal processing. [0014] LonWorks is a building automation protocol that typically uses either twisted pair cable at 78 kbit/sec or the power line at a few kilobits per second for the communication channel. For communication over the power line, LonWorks uses dual carrier frequency operation in which messages are sent using one carrier frequency and, if a response is not received, the message is sent a second time using a second carrier frequency. More recent releases of the protocol allow IP data frames to be communicated across a LonWorks network, and a library of commands for a wide variety of appliances and functions have been and continue to be developed for a range of residential and commercial applications. [0015] The C-Bus Protocol targets home automation systems as well as commercial lighting systems. Unlike the X10 protocol, C-Bus typically uses dedicated CAT5 cables and is considered by some to be more robust as a result. Ethernet also typically uses CAT5 cable for communicating between devices in a star topology with a router or switch at the center. Common data rates include 10, 100, and 1000 Mbit/sec, which are all deployed widely worldwide for computer networking. As mentioned previously, Ethernet data frames comprise a header of typically 22 bytes, a payload of up to 1500 bytes, and a CRC of four bytes. In many applications, the payload of an Ethernet frame is an Internet Protocol (IP) packet. Although overkill for simple lighting systems, Ethernet comprises the backbone of a variety of building lighting control networks, such as those from LumEnergi and others. [0016] ZigBee comprises a group of high level communication protocols that typically use the IEEE 802.15.4-2003 standard for Wireless Personal Area Networks (WPANs) as the physical layer. As such, ZigBee typically uses small low power radios to communicate between appliances, light switches, consumer electronic, and other devices in a residence for instance. IEEE 802.15.4 uses either the 868 MHz, 915 MHz, or 2.4 GHz radio frequency bands. Data is direct-sequence spread spectrum coded and then Binary Phase Shift Key (BPSK) or Orthogonal Quadrature Phase Shift Key (OQPSK) modulated prior to transmission. Data is communicated in one of four different types of frames with variable data payload. Such frames include beacon frames, which specify a super-frame structure similar to that of HomePlug, data frames used for transfers of data, acknowledge frames used for confirming reception, and MAC command frame used for controlling the network. The SuperFrame structure allows certain devices guaranteed bandwidth and provides shared bandwidth for other devices. Many aspects of the network enable very low power communication with battery powered devices. [0017] Wi-Fi or 802.11 is a very common wireless network for data communication between computers. A number of versions of the protocol including 802.11a, 802.11b, and 802.11g have been released over the years. The recent version, 802.11g, operates at the 2.4 GHz band and uses Orthogonal Frequency Division Multiplexing (OFDM) and typically achieves about 22 Mbit/sec average throughput. Similar to Ethernet, Wi-Fi frames comprise of a header, payload, and CRC. Similar to 802.15.4, Wi-Fi has a variety of different types of frames for communication management. In general, Internet Protocol (IP) and the associated Transport Control Protocol (TCP) run over Wi-Fi networks. [0018] Although wireless protocols such as ZigBee and Wi-Fi do not need dedicated wires to communicate between devices, nor do they have the limitation previously mentioned associated with power line communication, such wireless networks can be limited by congestion in the increasingly crowded RF spectrum. Additionally, different countries in the world allocate spectrum differently which forces devices to sometimes operate in different frequency bands. SUMMARY OF THE INVENTION [0019] An alternative physical layer communication channel and associated network protocol for lighting control among other applications have been introduced that use modulated visible light traveling through free space to communicate data. According to such visible light communication (VLC) protocol, all devices synchronize to a frequency or phase of the AC mains for instance and produce gaps during which messages can be sent. At other times, lamps using LEDs or any other type of light source, simply produce illumination. During the gap times some number of bytes of data can be sent from one lamp to one or more other lamps that can comprise a complete message in itself, or such data can accumulate over any number of gaps to produce much larger messages. [0020] Using visible light to communicate between lamps and other devices in a lighting system has many advantages over wired, wireless, and powerline communication networks such as those previously described. No dedicated wires are needed, which is important especially for installation in existing buildings. The visible light spectrum is unregulated globally and does not suffer from the congestion and interference common in RF wireless communication. Electrical noise on the powerline, from appliances turning on and off for instance, does not affect communication integrity as in powerline communication protocols. No expensive and complicated analog and digital signal processing is necessary to modulate and demodulate data as in many wireless and powerline protocols. The light source needed to transmit data is necessary anyway to provide illumination, and in the case that the light source is one or more LEDs, the LEDs can operate as the light detector as well. As such, the visible light communication protocol can be implemented in an LED lamp for virtually no additional cost. [0021] A limitation of such a visible light communication protocol is that data cannot be communicated through walls between various rooms in a building. Another limitation is that, other than the remote controller, it is difficult to cost effectively control such a visible light communication network. The invention described herein, in various embodiments, provides solutions to overcome these limitations. [0022] According to one embodiment, an electronic device is provided herein for controlling a lighting system. In certain exemplary embodiments, the electronic device is mounted to a wall in a room or held in a hand, for instance, and comprises a Human Machine Interface (HMI), such as a touch screen or a set of buttons (e.g., dedicated to specific lighting functions or programmable to perform a variety of functions) that are illuminated by a light source. In addition to illuminating the HMI, the light source also transmits messages through free space using visible light to one or more lamps in the room. For example, a HMI could comprise an LCD panel, which is illuminated by an LED backlight for displaying information about the controls or lighting system, and either an overlaid touch screen sensor or additional pushbuttons for entering information. Alternatively, the HMI could comprise just pushbuttons that are illuminated by some light source for use in the dark. [0023] For a handheld electronic device (otherwise referred to herein as a wireless communication device), such as a smart phone or tablet computer, the display backlight could be modulated in a variety of ways including playing a video with alternating light and dark frames to produce light modulated with data. The ambient light sensor available on many handheld electronic devices could be used to receive data transmitted through free space using visible light. An alternative light source in many handheld electronic devices such as smart phones is the camera flash, which typically comprises one or more LEDs that can be modulated through software to transmit data through free space using visible light. [0024] As another example, the light source in an electronic device that is mounted to a wall, for instance, can be synchronized to a frequency or phase of the AC mains, produce communication gaps that are synchronous to the communication gaps used by lamps in the room, and transmit data to the lamps in response to input from a user. Additionally, such an electronic device can have a light detector for receiving information from the lamps that is transmitted through free space using visible light. If the light source is one or more LEDs, then the LEDs can be both the light source and the light detector. In a further embodiment, the light produced by a light source in the electronic device is perceived as unchanging by a user independent of whether data is being transmitted or not. This is accomplished, for instance, by producing a small amount of light continuously when data is not being transmitted and by turning this small amount of light off before or after data is transmitted at high brightness for instance. In this exemplary embodiment, control circuitry within the electronic device is configured to produce commands in response to input directly from a user. [0025] In certain exemplary embodiments, an electronic device comprising an HMI with a light source and a light detector also comprises circuitry to interface to any type of data communication network typically used for lighting or building control information. Such data communication network could communicate over dedicated wires (e.g., Ethernet, DALI, DMX512, and others), the power line (e.g., X10, HomePlug, and others), RF wireless (e.g., ZigBee, Wi-Fi, and others), or any other communication channel including for instance fiber optic cable and wireless infra-red. Such data communication network could interface for instance to a central building controller over Ethernet or DALI, or could interface for instance to a wireless communication device (such as a smartphone) over Wi-Fi, Bluetooth, IRDA, or any other data communication protocol supported by such wireless communication device. In some instances, the electronic device could comprise interfaces to multiple data communication networks, such as Ethernet and Wi-Fi, to support lighting control systems with mixed environments. [0026] In an electronic device comprising an HMI that can communicate through free space using visible light, and interfaces to one or more data communication networks, control circuitry would receive input directly from the user through the HMI, data received from such data communication networks, or data received optically through free space. Such control circuitry in response to such input or data would produce commands encoded and transmitted according to a visible light communication protocol. [0027] In certain exemplary embodiments, a lamp comprises a light source for illuminating an area and transmitting data through free space using visible light, a light detector for receiving data transmitted through free space using visible light, and an interface to one or more other types of data communication networks that carry lighting control information. If one or more LEDs can operate as the light source, then such LEDs could also be operable as both the light source and the light detector. The data communication network could communicate with the lamp over any type of communication channel and communication protocol. The lamp could be a lamp in a ceiling, for instance. In such a lamp, control circuitry receives input from one or more such data communication network or networks and produces commands encoded and transmitted according to a visible light communication protocol such as that described in the one or more priority applications listed herein. DESCRIPTION OF THE DRAWINGS [0028] The present invention may be better understood, and its numerous objects, features, and advantages made apparent to those skilled in the art by referencing the accompanying drawings. [0029] FIG. 1 is an exemplary block diagram of a lighting control system comprising a plurality of lamps, an electronic device and optional wireless communication device. [0030] FIG. 2 is an exemplary block diagram of a lamp that communicates with an electronic device and/or other lamps through free space using visible light. [0031] FIG. 3 is an exemplary block diagram of a lamp that communicates with other lamps through free space using visible light and with a network and other controlling devices through a Wi-Fi interface. [0032] FIG. 4 is an exemplary diagram for the structure of a Wi-Fi data communication packet. [0033] FIG. 5 is an exemplary diagram for a packet communicated through free space using visible light. [0034] FIG. 6 is an exemplary drawing of an electronic device with an HMI, wherein the electronic device controls a lighting system by communicating with lamps through free space with visible light and communicating with a network and other controlling devices through Wi-Fi and Ethernet interfaces. [0035] FIG. 7 is an exemplary block diagram of an electronic device with an HMI, wherein the electronic device controls a lighting system by communicating with lamps through free space with visible light and communicating with a network and other controlling devices through Wi-Fi and Ethernet interfaces. [0036] FIG. 8 is an exemplary timing diagram for communicating between an HMI and lamps through free space using visible light. [0037] The use of the same reference symbols in different drawings indicates similar or identical items. While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. DETAILED DESCRIPTION [0038] Turning now to the drawings, FIG. 1 is one example of a building lighting system 10 that comprises building controller 11 configured for controlling the lighting system and a network 12 that connects room1 13 , room2 14 , and roomN 15 to building controller 11 . The lighting system 10 shown in FIG. 1 further includes an electronic device 16 , or possibly a lamp 22 , which communicates with the network 12 . The designation room1 through roomN represents any number of rooms in a building or even multiple buildings to one of more central controllers represented by building controller 11 . Within any particular room, a plurality of lamps (e.g., lamps 17 , 18 , and 19 within room1, or lamps 22 , 23 and 24 within room2) may communicate with each other and with an electronic device 16 through modulated visible light shown in FIG. 1 with bi-directional arrows. [0039] In example room1 13 , electronic device 16 interfaces between network 12 , lamps 17 , 18 , and 19 , and optionally wireless communication device 20 . Wireless communication device 20 may or may not be part of building lighting system 10 , but if included, can be any type of mobile device including but not limited to mobile phones, smart phones, personal digital assistants (PDA), and mobile computers such as netbooks, notebooks, and laptops. Wireless communication device 20 could also be a stationary device, such as a desktop computer. In some embodiments, wireless communication device 20 may communicate with electronic device 16 using any radio or infra-red frequency wireless communication protocol including, but not limited to, Zigbee, Wi-Fi, and Bluetooth. In some embodiments, wireless communication device 20 may be configured for controlling the lighting system, similar to electronic device 16 , and may be considered to be a hand held electronic device. [0040] Network 12 typically might communicate according to the wired DALI or Ethernet standards, or the wireless ZigBee or Wi-Fi standards, but could communicate according to any data communication protocol using wired, wireless, powerline, fiber optic, or any other type of communication channels. Network 12 and optional wireless communication device 20 can communicate according to the same or different wireless protocols, or can communicate over different protocols using different wired or wireless communication channels. [0041] Electronic device 16 represents any electronic device that provides an interface between lamps 17 , 18 and 19 and network 12 , and that also provides a human machine interface (HMI) 21 . HMI 21 is configured to receive input from a user, which is typically used, but not limited to, local control of lamps 17 , 18 , and 19 in room1 13 , for instance. In one embodiment, electronic device 16 could be a device mounted on a wall within room1 13 that enables a user to control the lighting within room1 13 independent of and/or overriding commands from building controller 11 . Electronic device 16 could be a device about the size of a conventional light switch or a ganged light switch. In one example, electronic device 16 could be implemented with an HMI 21 , such as a display and touch screen that enables a user to select lighting functions from a menu or nested menus for instance. Electronic device 16 also, for instance, could be implemented with an HMI 21 , such as a set of buttons that are dedicated to particular functions, such as on/off, dimming, color, timing, and other functions such as those described in the one or more priority application listed herein. [0042] In the example lighting system of FIG. 1 , electronic device 16 communicates with lamps 17 , 18 , and 19 through modulated visible light. According to one embodiment, electronic device 16 could comprise a dedicated light source, which is configured to provide illumination and to transmit data optically through free space using visible light, and optionally an additional light detector, which is configured to receive data transmitted optically through free space using visible light. According to another embodiment, the dedicated light source may be used to both illuminate the HMI 21 and to communicate modulated visible light uni-directionally or bi-directionally with lamps 17 , 18 , and 19 in the example room1 13 of FIG. 1 . [0043] In order for the HMI 21 to be visible in the dark, for instance, the electronic device typically comprises a backlight (or a light source positioned behind the HMI) that illuminates the HMI (e.g., various push buttons or an LCD display with an overlaid touch screen sensor) from behind. Many possible HMIs are possible with the commonality that a light source is typically necessary for a user to see in at least a dark environment. Such a light source typically will be an LED or array of LEDs, but could comprise any type of light source including, for instance, Cold Cathode Fluorescent lamps (CCFL). If the light source is a CCFL or, for instance, a white LED with a phosphor coating, preferentially the electronic device also comprises an additional photo-detector. [0044] According to one embodiment of the invention, the light emitted from the backlight of the HMI is modulated in such a way that one or more of lamps 17 , 18 , and 19 can detect the data represented by such modulation. In some embodiments, electronic device 16 can also receive data sent by lamps 17 , 18 , or 19 , e.g., through the additional photo-detector, or through the backlight. For example, if the backlight comprises one or more LEDs for illumination and data transmission, and preferentially mono-chromatic LEDs such as red, green, and blue, the LEDs used for illumination and data transmission may also be used to receive data sent by lamps 17 , 18 , or 19 . [0045] According to another embodiment of the invention, wireless communication device 20 , which could be any type of computing device with a backlit display such as a smart phone, PDA, or a tablet, netbook, notebook, or desktop computer, may communicate directly with electronic device 16 or with lamps 17 , 18 , and 19 through free space using visible light. For example, wireless communication device 20 may produce commands in response to input received directly from a user, and may transmit such commands to the electronic device 16 or directly to the lamps 17 , 18 and 19 using visible light. As with electronic device 16 , the backlight for the display of the wireless communication device 20 can be modulated to transmit data or commands optically to the electronic device 16 or directly to lamps 17 , 18 , and 19 . This can be accomplished in various ways including, but not limited to, playing a video with alternating light and dark frames producing the transmitted data. The ambient light sensor available on many wireless communication devices can also be used as a light sensor to receive data. Alternatively, the camera flash, which typically comprises one or more LEDs on a smart phone, for instance, can also be modulated through software to transmit data to electronic device 16 or to lamps 17 , 18 , and 19 in the example of FIG. 1 . [0046] According to another embodiment, a lamp may be used to interface with the network 12 instead of an electronic device. As represented by room2 14 , for instance, lamp 22 provides an interface between the lamps 22 , 23 , and 24 within room2 14 and network 12 . As such, lamp 22 comprises a network interface, which is capable of communicating with network 12 according to any protocol using any communication channel including, but not limited to, RF wireless, wired, fiber optic, or power line. In this example room2 14 , lamp 22 further comprises a light source for illumination and data transmission, and a light detector for receiving data from lamps 23 and 24 . In one embodiment of the invention, if the light source is one or more LEDs, then such LEDs can also operate as the light detector depending on when data is to be sent or received. [0047] As in example room1 13 and wireless communication device 20 , wireless communication device 25 in room2 14 , for instance, can locally control lamps 22 , 23 , and 24 by overriding commands from building controller 11 or can implement any functionality supported by lighting system 10 . In this example room2 14 , wireless communication device 25 communicates with lamp 22 , which also provides the interface to network 12 . As such, according to one embodiment of the invention, lamp 22 further comprises a wireless interface compatible with wireless (RF, infra-red, etc) communication device 25 and an interface compatible with network 12 . [0048] Within the example room1 13 and room2 14 , lamps 17 , 18 , and 19 , and lamps 22 , 23 , and 24 respectively communicate between each other using modulated visible light. When observed by the human eye, although the light is visible, the modulation of the light is typically not discernable and is typically perceived as constant and unchanging light. The maximum distance between any two lamps, for instance lamps 17 and 18 , is determined by the brightness and directionality of the data transmitting lamp and the light detection sensitivity of the data receiving lamp. In the example room1 13 , lamps 17 and 18 are positioned within such maximum communication distance, and lamps 17 and 19 for instance are positioned beyond such maximum communication distance. According to another embodiment of the invention, lamp 18 in the example room1 13 relays messages sent through modulated visible light between lamps 17 and 19 to enable communication between large numbers of lamps that are large distances apart. [0049] According to the invention, lamps that relay commands first receive data on a light detector and forward such input to control circuitry that regenerates commands in response to such input. For instance, commands can be directed from lamp 17 to lamp 19 only, while lamp 18 simply receives and retransmits such commands along a dedicated path as in the Internet. Alternatively, messages from an example lamp 17 can be broadcast to all lamps in which lamp 18 for instance responds to such broadcast command and also retransmits such command to lamp 19 for instance. As such, commands can be sent through a network of lamps as broadcast messages or through dedicated or ad-hoc paths between particular lamps or groups of lamps. Ad-hoc paths are well known to those practicing in the field of mesh networking, which is commonly used in Zigbee wireless networks for instance. [0050] FIG. 1 is just one example of many possible lighting control systems 10 , which could comprise any number of buildings, rooms within each building, and lamps within each room, hallway, entryway, etc. Additionally, lighting control system 10 may comprise of any number of building controllers and any type or multi-types of networks between rooms. The networks 12 between rooms can communicate according to any type of protocol including standards such as Ethernet, DALI, Wi-Fi, and others that use wired, RF, power line, fiber optic, or any other type of data communication channel. [0051] The embodiments of the invention illustrated by this example FIG. 1 include, but are not limited to, the following devices: a. electronic device 16 that produces commands in response to input received directly from a user through an HMI 21 , from a lighting control network 12 , or from a wireless communication device 20 , and transmits such commands using the same light source that is used to illuminate the HMI 21 of the electronic device 16 ; b. wireless communication device 20 that produces commands in response to input directly from a user and transmits such commands to the electronic device 16 or directly to the lamps 17 , 18 or 19 using the backlight or the flash of the wireless communication device 20 ; c. lamp 22 that produces commands in response to input received from a lighting control network 12 or a wireless communication device 25 and transmits such commands to lamps 23 and 24 using the same light source that is used for illumination; d. lamp 17 that produces commands in response to input received from another lamp 18 or 19 or an electronic device 16 and detected by the light sensor, and transmits such commands using the same light source that is used for illumination. [0056] Preferentially, lamps 17 , 18 , 19 , 22 , 23 , and 24 and optionally electronic device 16 communicate between each other in synchronization with the AC mains 31 , as described in one or more priority applications listed herein; however, such devices could communicate according to any communication protocol that uses visible light traveling through free space. Such communication can be between devices that are in or out of synchronization and according to any modulation technique, data rate, or distance. Likewise, any routing or mesh networking protocol can be implemented using such devices that receive and retransmit commands optically through free space. As noted herein, the term “free space” refers to communication within space, but not confined to, for example, an optical fiber. Thus, transfer of commands occurs optically, but not constrained within an optical fiber or any other type of waveguide device, yet is free and able to travel optically in any non-obstructed direction. The example of a building lighting system 10 does not limit the embodiment to a single building, but can be among several buildings or within a portion of the building. Moreover, each room shown in the lighting system 10 is configured according to one example if, for example, there are several rooms controlled by a lighting system. If the system controls only a single room, then the example in FIG. 1 would apply to different sub-regions within that room, each having a different interface to a network. Likewise, each room or sub-regions of a room can be controlled according to that shown in room1 13 , room2 14 , or both. [0057] Thus, the lighting system can be controlled with an electronic device 16 that comprises a HMI 21 and provides an interface between lamps 17 , 18 , 19 and network 12 . Alternatively, the lighting system can be controlled with a wireless communication device, e.g., device 25 , and interface to the network 12 can be achieved solely with a light source (e.g., lamp 22 ), which can also function as a light detector. In this case, the HMI can be achieved by a wireless communication device (e.g., device 25 ) that need not be configured between the lamps 22 , 23 , and 24 and the network 12 . [0058] Accordingly, an electronic device is provided herein having both a light source and a light detector, as well as control circuitry, which is configured to produce commands for controlling the lighting system in response to received input and/or data. The electronic device can further comprise an HMI configured to receive input from a user, and/or a network interface configured to receive data from a network, depending on the configuration shown in the examples of FIG. 1 . Various embodiments of lamps are also provided herein having a light source, a light detector and control circuitry that produces commands transmitted by the light source in response to commands received through the light detector. In some embodiments, a lamp may be configured to produce commands in response to input received from a network 12 or a wireless communication device 25 and to transmit such commands to other lamps using the same light source that is used for illumination. [0059] FIG. 2 is one example of a block diagram of a lamp 30 comprising a light source that is configured to provide illumination and transmit data optically through free space, a light detector that is configured to receive data transmitted optically through free space, and a control circuit that produces commands transmitted by the light source in response to commands received through the light detector. According to one embodiment, LEDs 36 may be configured at different times as both the light source and the light detector. Example lamps 17 , 18 , 19 , 23 or 24 could comprise the circuitry represented by this example FIG. 2 . As such, in addition to providing general illumination, a lamp comprising such control circuitry can receive messages sent via modulated visible light (e.g., from electronic device 16 , wireless communication device 20 or 25 , or another lamp) and can retransmit such information according to any pre-determined fixed routing or any ad-hoc mesh networking protocols for instance. [0060] As shown in FIG. 2 , lamp 30 connects to the AC mains 31 that provides power and synchronization in this example. Power supply 32 converts AC power to DC power that provides current to LEDs 36 and voltage to the remaining circuitry in lamp 30 . Timing 33 typically comprises a phase locked loop (PLL) that locks to the AC mains 31 frequency and/or phase, and provides timing information to visible light communication (VLC) network controller 34 and physical layer interface (PLI) 35 . Since the example electronic device 16 and lamps 17 , 18 , 19 , 22 , 23 , and 24 ( FIG. 1 ) are all coupled and thus synchronized to the same AC mains 31 , the timing of the VLC network controllers 34 and PLIs 35 in all such example devices is substantially the same, which simplifies data communication as described in one or more priority applications listed herein. [0061] PLI 35 typically comprises an LED driver circuit (not shown) that produces a substantially DC current to produce illumination from LEDs 36 and modulated current to transmit data from LEDs 36 . Such substantially AC and DC currents can be combined in many different ways to produce both illumination and transmit data using the same light source. Periodic time slots can be produced in synchronization with the AC mains 31 during which the example DC current is turned off and the example AC current is turned on during gaps in which data is transmitted. [0062] PLI 35 also typically comprises a receiver circuit (not shown) that in this example FIG. 2 detects photo-current induced in LEDs 36 while receiving data transmitted using visible light through free space. Such receiver typically converts such photo-current to voltage, which is then compared to a reference voltage to determine a sequence of ones and zeros sent by the transmitting device. The details of one example PLI 35 are described in one or more priority applications listed herein. [0063] VLC network controller 34 interfaces with PLI 35 and memory 37 to receive commands transmitted using visible light through free space, to implement the necessary control circuit functionality of lamp 30 , and in some cases, re-transmit commands using LEDs 36 that were previously received by LEDs 36 during gap times. Commands received by the light detector, in this case LEDs 36 , can be stored in memory 37 and further processed. Commands that target lamp 30 can be interpreted by VLC network controller 34 and processed locally. For instance, the brightness or color of LEDs 36 can be adjusted by adjusting the substantially DC current applied to LEDs 36 by the driver function within PLI 35 . Commands that target other or additional lamps can be stored in memory 37 and re-transmitted by PLI 35 and LEDs 36 during subsequent gap times for instance. Such commands can be routed through a pre-determined path, through an ad-hoc mesh network, or broadcast to all electronic devices for instance. VLC network controller 34 may be configured to communicate such commands according to a visible light communication protocol. [0064] In this example FIG. 2 , timing 33 can not only synchronize all electronic devices and lamps 30 in the network, but can also provide timing to power supply 32 to minimize noise coupling into PLI 35 . As such, FIG. 2 is just one example of many possible lamps 30 that receive commands communicated through free space using a light detector and re-transmit such commands to other electronic devices or lamps using visible light. The preferential visible light communication protocol is described in one or more priority applications listed herein, however, any visible light communication protocol and multiplexing scheme between illumination and data communication are possible. Additionally, lamp 30 could have a variety of block diagrams different from this example FIG. 2 . For instance, lamp 30 could be DC or solar powered for instance. Likewise, any type of light source is possible including, but not limited to, fluorescent tubes, compact fluorescent lights, incandescent light, etc. In particular, lamp 30 could comprise a light detector, such as a silicon photo-diode in addition to the light source, which in this example FIG. 2 is LEDs 36 . [0065] FIG. 3 is one example block diagram of a lamp 40 (e.g., lamp 22 in FIG. 1 ) that can transmit and receive data communicated using visible light through free space, and can also communicate according to the wireless 802.11 protocol with building controller 11 and wireless communication devices 20 and 25 . As in lamp 30 , lamp 40 comprises LEDs 36 , PLI 35 , VLC Network Controller 34 , memory 37 , and timing 33 . Power supply 41 may be slightly different from power supply 32 due to the additional load provided by the additional processor 42 and Wi-Fi interface 43 . [0066] In this example lamp 40 , LEDs 36 operate as both the light source and the light detector for transmitting and receiving data using visible light communicated through free space. LEDs 36 also provide illumination. Wireless 802.11 interface 43 can receive messages from wireless communication devices (e.g., a smart phone) 20 and 25 , or from building controller 11 , and can forward such messages to processor 42 , which can implement the control circuitry functionality necessary to interpret or translate such messages to commands that can be transmitted through free space using visible light (e.g., using LEDs 36 as the light source). Likewise, commands transmitted optically through free space can be received by LEDs 36 operating as light detectors, interpreted or translated by processor 42 , and transmitted by Wi-Fi interface 43 back to wireless communication devices 20 and 25 or building controller 11 . [0067] Whether or not a lamp includes a processor and separate Wi-Fi interface, as shown in FIG. 3 , it is appreciated that the lamp operates as a light source and a light detector via one or more LEDs to which it controls. When a separate processor and Wi-Fi interface are not included, as in the embodiment of FIG. 2 , the VLC network 34 of the lamp 30 provides the control circuitry through the PLI 35 to the light source and light detector dual purpose function of the LEDs 36 . The controllable LEDs can control other LEDs within optical range, both within a bank of LEDs 36 or external to the bank of LEDs as shown by the bi-directional arrows of FIGS. 2 and 3 . [0068] FIG. 4 illustrates the typical data frame format 50 for Wi-Fi, which comprises up to thirty bytes for header 60 , zero to two thousand three hundred twelve (2312) bytes for data 58 , and four bytes for frame check sequence (FCS) 59 . Header 60 typically comprises two bytes for frame control 51 , two bytes for the duration ID 52 , six bytes for source address 53 , six bytes for destination address 54 , six bytes for receiver address 55 , two bytes for sequence control 56 , and six bytes for transmitter address 57 . Typically in a Wi-Fi network, data 58 comprises packets that conform to the Internet Protocol (IP), which comprise up to an additional 20 bytes of header. [0069] FIG. 5 illustrates a possible data frame format, which is generally compatible with the ZigBee wireless RF protocol, for communicating with visible light. The data frame format shown in FIG. 5 comprises a Physical Protocol Data Unit (PPDU) 70 , which further comprises four bytes for preamble sequence 66 , one byte for start of frame delimiter 67 , one byte for frame length 68 , and up to 128 bytes for Mac Protocol Data Unit (MPDU) 69 . MPDU 69 comprises two bytes for frame control 61 , one byte for data sequence number 62 , four to twenty bytes for address information 63 , N bytes for data 64 , and four bytes for Frame Check Sequence (FCS) 65 . [0070] In the example lamp 40 illustrated in FIG. 3 , Wi-Fi interface 43 can forward received data frames conforming to the example Wi-Fi protocol illustrated in FIG. 4 to processor 42 . Processor 42 interprets such data frames and creates data frames conforming to the example visible light communication protocol illustrated in FIG. 5 . Processor 42 inputs such data frames to VLC network controller 34 for transmission through PLI 35 and LEDs 36 . Likewise, data frames input to VLC network controller 34 through LEDs 36 and PLI 35 can be processed and transmitted through PLI 35 and LEDs 36 or forwarded to processor 42 , which can interpret such data frames, create data frames conforming to the example Wi-Fi protocol and forward such data frames to Wi-Fi interface 43 for transmission over such Wi-Fi network. [0071] FIG. 3 is just one of many possible block diagrams for lamp 40 . For instance, instead of the LEDs 36 shown in FIG. 3 , the light source could be a fluorescent bulb or any other type of light source. Lamp 40 could also comprise a photo-detector, such as a silicon photodiode, instead of using LEDs 36 as both the light source and light detector. Lamp 40 does not need to be synchronized to the AC mains and comprise timing block 33 . Many other means of synchronization are possible and communication even without synchronization is possible. Lamp 40 could be battery or solar powered, for instance, and as such would have a different or no power supply 41 . VLC network controller 34 and PLI 35 in this example implement the data frame format illustrated in FIG. 5 , but could implement any type of communication protocol using visible light. For instance, the protocol described uses substantially the same frame format as ZigBee, however, any frame format including substantially simpler versions with smaller headers are possible. [0072] Wi-Fi interface 43 is just one example of many different network interfaces using many different types of communication channels that are possible. It is also possible to have multiple interfaces to different networks. Some other network examples include X10, DMX512, DALI, Ethernet, ZigBee, HomePlug, LonWorks, C-Bus, Dynalite, Bluetooth, and even SONET and ATM. A typical configuration for lamp 22 in FIG. 1 could include a Wi-Fi interface 43 for communicating with a smart phone for instance for local control, and an Ethernet interface (not shown) for communicating with a building controller 11 . [0073] FIG. 6 illustrates one embodiment of the electronic device 16 from FIG. 1 that interfaces to network 12 , wireless communication device 20 , and lamps 17 , 18 and 19 . In this example FIG. 6 , a user can also control lamps 17 , 18 , and 19 within room1 13 , and potentially the entire lighting system 10 , by pushing regions of touch screen 80 that overlay menu 84 that is an image produced by LCD 81 and illuminated by backlight 82 . The example menu 84 provides various buttons to turn lights on and off (ON/OFF), adjust brightness (DIM), change color (COLOR), set the timer (TIMER), adjust the ambient light sensor (AMB), and access advanced programming functions (PROG). In this example FIG. 6 , electronic device 16 is powered by the AC mains 31 and is contained within housing 83 . The HMI in FIG. 6 is provided by the touch screen 80 and LCD 81 . [0074] Electronic device 16 communicates with building controller 11 through network 12 according to any one of many different data communication protocols over any of a variety communication channels including but not limited to CAT5 or twisted pair cable, RF wireless, powerline or fiber optics. Although it need not communicate with device 20 , electronic device 16 can also optionally communicate with wireless communication device 20 (which could be a smart phone) using any one of many different RF, infrared, or other wireless communication protocols, including but not limited to Wi-Fi, ZigBee, Bluetooth, IRDA, or others. According to one embodiment of the invention, electronic device 16 communicates with lamps 17 , 18 , or 19 through free space using modulated visible light that also provides illumination for electronic device 16 . [0075] FIG. 7 is an example functional block diagram of the electronic device 16 that comprises a touch screen 80 , LCD 81 , backlight 82 , and housing 83 , as shown in FIG. 6 . Housing 83 can comprise the same timing 33 , memory 37 , VLC network controller 34 , PLI 35 and Wi-Fi interface 43 as illustrated in FIG. 3 , and can also comprise Ethernet interface 91 , touch screen controller 93 , graphic controller 94 , and processor 92 . LEDs 36 in the examples of FIG. 6 and FIG. 7 reside in backlight 82 and produce illumination for LCD 81 , and transmit data through free space using visible light. Additionally, LEDs 36 (which in the example of FIG. 7 could be red LEDs) can also operate as light detectors for receiving data transmitted through free space using visible light. [0076] In this example FIG. 7 , electronic device 16 interfaces with building controller 11 according to the Ethernet protocol, which typically uses CAT5 cable as the communication channel. Messages received by Ethernet interface 91 can be forwarded to processor 92 , which can implement the control circuitry necessary to interpret or translate such messages to commands that can be transmitted through free space using visible light with LEDs 36 as the light source. As in FIG. 3 , messages received through Wi-Fi interface 43 can also be forwarded to processor 92 for interpretation and translation to commands that can be transmitted through free space using visible light with LEDs 36 as the light source. [0077] In this example FIG. 7 , commands transmitted optically through free space can also be received by LEDs 36 operating as light detectors, interpreted or translated by processor 92 , and transmitted by Wi-Fi interface 43 back to wireless communication devices 20 or 25 , or transmitted by Ethernet interface 91 to building controller 11 . Likewise, processor 92 can route messages from any of Ethernet interface 91 , Wi-Fi interface 43 , and VLC network controller 34 to any other such network interface. [0078] The protocol for communicating through free space using visible light can be the same as, or different from, the protocol described in one or more priority applications listed herein. In this example FIG. 7 , LEDs 36 can be configured to continuously provide illumination and communicate for instance with lamps 17 , 18 , or 19 , building controller 11 , or wireless communication device 20 at any time. As another possibility, LEDs 36 could typically be turned off and electronic device 16 could be in a low power state until a user first touches touch screen 80 , after which electronic device 16 powers up, illuminates LEDs 36 , and enables communication. [0079] FIG. 6 and FIG. 7 are just examples of many possible diagrams for an electronic device 16 comprising an HMI 21 . Although FIGS. 6 and 7 illustrate the HMI 21 of the electronic device 16 as including a touch screen 80 and LCD 81 , the HMI could have any one of many other possible mechanical forms that do not necessarily include touch screen 80 or LCD 81 . For example, HMI 21 could comprise mechanical buttons that are illuminated from in front, behind, above, or below. As a further example, HMI 21 could comprise an Organic LED (OLED) display instead of an LCD. Backlight 82 can be any type of light source positioned in any manner to provide illumination for HMI 21 , which may have a dedicated light detector (such as a silicon photodiode) or use LEDs 36 for both emitting and detecting light. If HMI 21 comprises an OLED or any other type of active matrix display, such light source could be such active matrix display. Likewise, an OLED display could be the detector as well. [0080] Electronic device 16 could be battery or solar powered, or powered in any other way instead of being powered by AC mains 31 . Electronic device 16 could be synchronized to lamps 17 , 18 , and 19 through any one of a number means, or not at all. Electronic device 16 could be a mobile computing device such as a smart phone, PDA, or netbook, notebook, or laptop computer, or a stationary computing device such as a desktop computer or even a television. [0081] Menu 84 and the associated functionality described herein is just one possibility. Any number of different menus with totally different functionality is possible. If HMI 21 does not comprise some sort of display, then menu 84 may be replaced by pushbuttons for instance. [0082] The block diagram for the electronic device 16 illustrated in FIG. 7 is just one of many possible examples. For instance, the light source could be a CCFL or even a CFL instead of the LEDs 36 . The electronic device 16 could also comprise an additional photodetector. Memory 37 could be a part of processor 92 . Other than the Wi-Fi and Ethernet interfaces illustrated, any type of network interface is possible to communicate with building controller 11 , network 12 , or wireless communication device 20 . Any number of network interfaces is also possible, including none. For instance, a smart phone could communicate directly with lamps 17 , 18 , and 19 by modulating the backlight or the camera flash, and as such, would not need a Wi-Fi interface 43 or Ethernet interface 91 . Ambient light sensors could be used to receive data transmitted optically. [0083] FIG. 8 is an example timing diagram for transmitting data optically from electronic device 16 in a way that minimizes or eliminates flicker. The current through LEDs 36 is typically I1 103 , which should produce sufficient light to see menu 84 . As described in one or more priority applications listed herein, the current supplied to the LEDs 36 is periodically reduced from I1 103 to I0 102 to produce communication gaps 100 and 101 in synchronization preferentially with the AC mains 31 . As noted in the priority applications, the communication gaps are produced at regular, periodic intervals of each cycle of the AC mains, and the time duration of said communication gaps may be less than one quarter of each cycle of the AC mains. During gaps 100 when data is not being transmitted, the current through LEDs 36 is reduced to I0 102 , which could be a low level close to or equal to zero. During gaps 101 when data is being transmitted, the current through LEDs 36 is modulated between I0 102 and I2 104 , which is higher than I0 102 , so that the LEDs 36 emit light at two different output levels. I2 104 is preferentially, but not necessarily, the highest current LEDs 36 can tolerate in order to produce the most light to communicate the maximum distance. Any data modulation technique is possible including but not limited to Non-Return to Zero (NRZ) and Bi-phase. [0084] To minimize possible flicker produced by gaps 101 during which data is transmitted at high brightness, during time 105 preceding gap 101 , as shown in FIG. 8 , or after gap 101 (not shown), the current through LEDs 36 is reduced from I1 103 to I0 102 , such that the average brightness of light produced by LEDs 36 is the same whether or not data is transmitted during the gap times. [0085] FIG. 8 is just one of many possible examples of a timing diagram for transmitting data optically from electronic device 16 . For instance, communication gaps could occur at a faster or slower rate than the AC mains 31 , at rates totally unrelated to the AC mains 31 , or not at all. As an example, a video could be played on a smart phone that modulates the backlight or the light from an active display, such as an OLED, with light and dark frames in the video. The light from the electronic device could also be allowed to flicker for instance and as such could have a significantly different timing diagram from FIG. 8 . [0086] While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown and described by way of example. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed.

Intelligent illumination device are disclosed that use components in an LED light to perform one or more of a wide variety of desirable lighting functions for very low cost. The LEDs that produce light can be periodically turned off momentarily, for example, for a duration that the human eye cannot perceive, in order for the light to receive commands optically. The optically transmitted commands can be sent to the light, for example, using a remove control device. The illumination device can use the LEDs that are currently off to receive the data and then configure the light accordingly, or to measure light. Such light can be ambient light for a photosensor function, or light from other LEDs in the illumination device to adjust the color mix.

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation of application Ser. No. 11/929,267, filed on Oct. 30, 2007, which is a continuation of application Ser. No. 10/792,984, filed on Mar. 4, 2004, now U.S. Pat. No. 7,344,566, issued Mar. 18, 2008, which is a continuation-in-part of application Ser. No. 10/384,229, filed on Mar. 7, 2003, now U.S. Pat. No. 7,008,455, issued Mar. 7, 2006. BACKGROUND [0002] The present disclosure relates generally to a lip implant, and more particularly to a lip implant, which may be used for lip augmentation or enhancement. [0003] Within the field of Plastic Surgery, soft tissue augmentation has long been in popular demand by people wishing to enhance their physical appearance. More recently, lip augmentation, i.e. increasing the fullness of the lips, has become a viable entity. [0004] Currently, there are a variety of materials and methods used for lip augmentation. Some of the current techniques provide for temporary lip augmentation via injection of various materials into the lip such as fat, collagen, hyaluronic acid, and particulated dermis or fascia. One of the disadvantages of such temporary techniques is the need for the patient to periodically undergo additional procedures to maintain the lip fullness. [0005] Other techniques, such as liquid silicone injections, provide a more permanent lip augmentation. However, liquid silicone injections may be complicated by skin ulceration, long-term nodularity and granuloma formation, and chronic cellulitis. Furthermore, it is inherently difficult to remove liquid silicone from the lips should a problem arise or should the patient desire removal. That is, reversibility is difficult or impossible. [0006] Another permanent lip augmentation technique is the implantation of expanded polytetraflouroethylene (PTFE) such as Gore-Tex® strips or tubular forms of PTFE such as Softform® and Ultrasoft™. Expanded PTFE utilizes the concept of tissue ingrowth into the porous wall of the implant. While beneficial in some areas of the body, implantation of such material into the lips can be complicated by tissue adherence to the implant. Tissue ingrowth may result in restriction of lip excursion and result in an abnormal appearance during facial expression. Furthermore, fluid may accumulate inside the tubular forms of PTFE, thereby resulting in an unacceptable incidence of postoperative surgical infection and subsequent loss of implant. [0007] Therefore, what is needed is a lip implant that eliminates, or at least significantly reduces, the above-described complications. Moreover, instrumentation and a method for insertion of this new lip implant are needed. Finally, a method that is easily reversible is needed. BRIEF DESCRIPTION OF THE DRAWINGS [0008] FIG. 1 is a perspective view of a lip implant according to one embodiment of the present disclosure. [0009] FIG. 2 is a cross-sectional view of the lip implant of FIG. 1 taken along the line 2 - 2 . [0010] FIG. 3 is a perspective view of a lip implant instrument according to one embodiment of the present disclosure. [0011] FIG. 4 is a side view of the lip implant instrument of FIG. 3 . [0012] FIG. 5 is a cross-sectional view of the lip implant instrument of FIG. 4 taken along the line 5 - 5 . [0013] FIG. 6 is a schematic view of a lip for receiving the lip implant according to the present disclosure. [0014] FIG. 7 is a perspective view of a lip implant according to another embodiment of the present disclosure. [0015] FIG. 8 is a perspective view of a lip implant according to yet another embodiment of the present disclosure. [0016] FIG. 9 is a perspective view of a lip implant according to yet another embodiment of the present disclosure. [0017] FIG. 10 is a perspective view of a lip implant according to yet another embodiment of the present disclosure. [0018] FIG. 11 a is a sectional view of a lip implant according to yet another embodiment of the present disclosure. [0019] FIG. 11 b is a sectional view of a lip implant according to yet another embodiment of the present disclosure. [0020] FIG. 11 c is a sectional view of a lip implant according to yet another embodiment of the present disclosure. DESCRIPTION [0021] Referring to FIG. 1 , a lip implant for implantation into a lip of a patient (not shown) is generally referred to by reference numeral 10 . In one embodiment, the lip implant is integrally formed of medical grade silicone and is substantially solid as shown in the cross-section of FIG. 2 . The implant can be manufactured by a variety of methods including, but not limited to, injection molding, cast molding, extrusion, or cutting from a larger, solid block. [0022] The lip implant 10 is formed to have a substantially uniform level of hardness as can be measured by the durometer A-scale rating. Of course, hardness can be measured in manners other than via durometer A-scale ratings. In one embodiment, the lip implant 10 has a durometer rating of ten (10) or less resulting in a relatively soft lip implant. In such an embodiment, the lip implant 10 may include a skin 12 , also formed of silicone, having a higher durometer rating to provide the lip implant with structural integrity and manageability. Accordingly, the provision of the skin 12 may aid in handling or manageability of the lip implant 10 . However, the provision for a skin 12 is not always necessary, and the lip implant 10 with a durometer rating of ten (10) or less may be used without the need for an external skin. Of course, the particular durometer rating of the lip implant 10 may vary depending on the particular firmness desired. Also, the lip implant 10 may have a varying durometer rating of 0 to 50, resulting in a lip implant having a non-uniform hardness. [0023] The lip implant 10 is shaped to have a substantially circular cross-section ( FIG. 2 ). The diameter of the lip implant 10 is substantially uniform along the longitudinal axis of a middle portion 14 of the lip implant. The diameter of the middle portion 14 of the lip implant 10 can vary depending on the desired thickness of the lip implant. For instance, the diameter of the lip implant 10 may be between 2-10 millimeters. [0024] The middle portion 14 of the lip implant 10 defines a pair of end portions 16 . The end portions 16 are tapered in diameter such that the diameter of the lip implant 10 along the end portions decreases from the middle portion 14 to the ends of the lip implant. The middle portion 14 and the end portions 16 of the lip implant 10 cooperate to define the length of the lip implant, which can vary depending on the desired length of the lip implant. For instance, the length of the lip implant 10 may be between 5-8 centimeters. [0025] Referring to FIGS. 3-5 , a lip instrument for use in implanting the lip implant 10 is generally referred to by reference numeral 20 . The lip instrument 20 includes a pair of arms 22 a , 22 b coupled together at a pivot point 24 in any conventional manner to provide for relative pivotal movement of the arms about a pivotal axis P ( FIG. 4 ). Proximal to the pivotal axis P, the arms 22 a, 22 b include a pair of integrally formed ring-like members 26 a, 26 b, respectively, which define a pair of finger openings 28 a, 28 b. A pair of protrusions 30 a, 30 b extend towards one another from the ring-like members 26 a, 26 b, respectively, to prevent over-rotation of the arms 22 a, 22 b. [0026] Distal to the pivotal axis P, the arms 22 a, 22 b include a pair of integrally formed curved clamping members 32 a, 32 b, respectively, which cooperate to grasp the lip implant 10 ( FIG. 1 ) as will be further described with respect to the method of insertion. Referring to FIG. 5 , the clamping members 32 a, 32 b include an outer generally convex surface 34 a, 34 b, respectively, and a corresponding inner generally concave surface 36 a, 36 b. [0027] The inner surfaces 36 a, 36 b of the clamping members 32 a, 32 b face one another such that closing of the clamping members defines a generally circular area for grasping the lip implant 10 ( FIG. 1 ). The inner surfaces 36 a, 36 b are formed of a non-crushing surface in order to prevent damage to the lip implant 10 ( FIG. 1 ) when squeezed between the clamping members. In one embodiment, the inner surfaces 36 a, 36 b are formed of carbide. [0028] Referring to FIG. 6 , a lip region 40 of a patient (not shown) to receive the lip implant is depicted. The lip region 40 includes an upper lip 42 and a lower lip 44 , which meet at a pair of commissures 46 a, 46 b. The commissures 46 a, 46 b are substantially equidistant from a midline M of the lip region 40 . A tunnel 48 , as is generally illustrated in phantom in FIG. 6 , is formed through the lower lip 44 for reasons to be described with respect to the method for insertion. Method for Insertion [0029] In operation, referring to FIG. 6 , the lip region 40 is prepared for insertion of the implant by administering a local or regional anesthetic. Incisions are then made at each commissure 46 a, 46 b of the lip region 40 via a conventional scalpel or scissors. For sake of clarity, the method of insertion will be described with respect to insertion of the lip implant 10 into the lower lip 44 although it will be understood that the lip implant can be inserted into the upper lip 42 as well. [0030] Initial formation of the tunnel 48 is then performed with conventional curved iris scissors (not shown). The iris scissors are inserted into the lower lip 44 via the incision at commissure 46 a to dissect the tunnel 48 towards the midline M of the lip region 40 . In a like manner, the iris scissors are then inserted through the incision at commissure 46 b on the opposite side of the lip region 40 to dissect the tunnel 48 towards the midline M of the lip region. Such dissection culminates in the initial formation of the tunnel 48 through the lower lip 44 . The tunnel 48 is then widened via manipulation of the iris scissors or lip instrument 20 to complete the formation of the tunnel. [0031] After establishing the tunnel 48 , the lip instrument 20 is inserted into the lower lip 44 via the incision at commissure 46 a and the tunnel 48 such that the clamping members 32 a, 32 b extend through the tunnel enabling a portion of the clamping members to extend outside of the incision at commissure 46 b. The lip instrument 20 is then actuated to grasp the lip implant 10 between the clamping members 32 a, 32 b. The lip implant 10 is then drawn into the lower lip 44 via the lip instrument 20 until it is positioned appropriately within the tunnel 48 whereupon the lip implant is released from the lip instrument. [0032] A conventional suture, such as a chromic or nylon suture, is then used to close the incisions at commissures 46 a, 46 b. Antibiotic ointment may be applied to the incisions at commissures 46 a, 46 b as a prophylaxis against infection. Ice may be applied indirectly to the lip region 40 to reduce swelling. [0033] Thus, as described, insertion of the lip implant 10 is accomplished simply and quickly and in an uninterrupted manner. Thus, many of the problems associated with previous lip augmentation techniques can be eliminated with the use of the lip implant 10 . Furthermore, this process is completely reversible if desired. Alternates and Equivalents [0034] It is understood that a variety of alternative lip implants are contemplated by this disclosure. For example, and referring now to FIG. 7 , a lip implant 70 substantially similar in all respects to the lip implant 10 of FIGS. 1 and 2 , other than those features described below, has a middle portion 72 that includes a section 74 having a non-uniform diameter. [0035] In another alternative embodiment, and referring now to FIG. 8 , a lip implant 80 substantially similar in all respects to the lip implant 10 of FIGS. 1 and 2 , other than those features described below, includes a middle portion 82 having a non-uniform diameter along the entire length of the middle portion. [0036] In yet another alternative embodiment, and referring now to FIG. 9 , a lip implant 90 substantially similar in all respects to the lip implant 10 of FIGS. 1 and 2 , other than those features described below, is substantially non-uniform in diameter along the length of the implant. The lip implant 90 is reduced in diameter at a middle portion 92 thereof. [0037] In operation, the lip implants 70 , 80 and 90 of FIGS. 7 , 8 and 9 , respectively, are inserted into the lower lip 44 ( FIG. 6 ) of the patient in a substantially similar manner as described above. Thus, the embodiments of FIGS. 7 , 8 and 9 enjoy the advantages of that of FIG. 1 with respect to providing a structurally sound and safe lip implant for lip augmentation purposes. [0038] In yet another alternative embodiment, and referring now to FIG. 10 , an alternative lip implant 100 substantially similar in all respects to the lip implant 10 of FIGS. 1 and 2 , other than those features described below, is shaped to have a substantially elongated cross-section, which is substantially uniform in size along the length of the implant. In operation, the lip implant 100 is inserted into the lower lip 44 ( FIG. 6 ) of the patient in a substantially similar manner as described above. After insertion into the lower lip 44 , the lip implant 100 may be further sized to correspond to the shape of the lip. For example, the ends of the lip implant 100 may be cut in a tapered fashion such that the lip implant is customized to the particular shapes and contours of the lower lip 44 . [0039] As can be appreciated, the materials used in forming the lip implants of the present disclosure can be varied to include additional materials for use with silicone or alternative materials other than silicone. For example, the lip implants 10 , 70 , 80 , 90 , 100 and other embodiments of the lip implant of the present disclosure may alternatively be formed of urethane rather than silicone. [0040] Moreover, referring to FIG. 11 a , an alternative lip implant 110 a includes an inner core region 112 a formed of expanded polytetraflouroethylene (PTFE) such as Gore-Tex®, and an outer shell 114 a formed of silicone. The silicone used for the outer shell 114 a provides the lip implant 110 a with additional manageability. More importantly, the presence of the outer silicone shell 114 a aids in preventing tissue-adherence associated with the use of expanded PTFE. [0041] It is understood that other types of outer shells are contemplated for the lip implant 110 . For example, in some embodiments, the outer shell 114 a may be in the form of a polymer coating, such as Parylene™, which can be applied to the exterior of the inner core region 112 a to provide structural integrity and manageability. Accordingly, any number of materials including but not limited to silicone, urethane, expanded PTFE, and biocompatible polymers, and any combination of such materials may be used to form the lip implant 110 a. [0042] In another embodiment, and referring to FIG. 11 b , an alternative lip implant 110 b includes an inner core region 112 b formed of materials such as liquid silicone, silicone gel or beads, cohesive silicone gel or beads, biocompatible oil, saline or a biocompatible hydrogel material. The lip implant 110 b further includes an outer shell 114 b, which may be formed of a variety of materials including but not limited to silicone, urethane and biocompatible polymer (such as Parylene™). As can be appreciated, the outer shell 114 b encloses the inner core region 112 b and may be formed in an impermeable or semipermeable manner such that there is minimal or no leakage of the inner core region 112 b through the outer shell. [0043] In still other embodiments, and referring to FIG. 11 c , an alternative lip implant 110 c includes an inner core region 112 c, which may take the form of a hollow space defined by an outer shell 114 c. In such an embodiment, the inner core region 112 c can be filled with a gas such as air. Moreover, the outer shell 114 c may be formed of a variety of materials including but not limited to silicone, urethane and biocompatible polymers. As can be appreciated, the outer shell 104 c may be formed in an impermeable manner such that there is no leakage of gas from the inner core region 112 c through the outer shell. [0044] While the invention has been particularly shown and described with reference to embodiments thereof, it is understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention. For example, although a plurality of shapes of the lip implant 10 is described, these shapes are merely representative of the variety of shapes that the lip implant may take. Thus, the lip implant 10 is not limited to the longitudinal or cross-sectional shapes as described. [0045] Moreover, the tapered end portions 16 of the lip implant 10 may be removed resulting in a lip implant having a rod-like shape. Still further, the degree of taper and the length of the end portions 16 may be varied to accommodate the various desires or needs of implant patients. [0046] Still further, the clamping members 32 a, 32 b of the lip instrument 20 may be removable attached to the lip instrument such that various other clamping members may be used therewith. For instance, various degrees of curvature may be required of the clamping members resulting in the need to interchange the clamping members. [0047] Furthermore, the inner surfaces 36 a, 36 b of the clamping members 32 a, 32 b may be formed of a variety of materials other than carbide. [0048] Still further, during insertion of the lip implant 10 into the lower lip 44 , the incision may be made in the general commissure region on each side of the lip region 40 and such insertion is not limited to an exact commissure point. [0049] It is also understood that all spatial references, such as “diameter”, “longitudinal,” “increase,” and “decrease” are for illustrative purposes only and can be varied within the scope of the invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the following claims.

A lip implant having first and second regions is described. The lip implant includes a first region formed of a liquid, solid, or a gas and a second region formed of a solid material. Also described is a lip implant having an elongated cross-section. A method for insertion of the implant is also described along with the instrumentation facilitating its insertion.

CROSS REFERENCE TO RELATED PATENTS [0001] The present U.S. Utility patent application claims priority pursuant to 35 U.S.C. §119(e) to U.S. Provisional Application Ser. No. 61/256,226, entitled “DISTRIBUTED STORAGE NETWORK DATA REVISION CONTROL,” (Attorney Docket No. CS089), filed Oct. 29, 2009, pending, which is hereby incorporated herein by reference in its entirety and made part of the present U.S. Utility Patent Application for all purposes. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0002] NOT APPLICABLE INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC [0003] NOT APPLICABLE BACKGROUND OF THE INVENTION [0004] 1. Technical Field of the Invention [0005] This invention relates generally to computing systems and more particularly to data storage solutions within such computing systems. [0006] 2. Description of Related Art [0007] Computers are known to communicate, process, and store data. Such computers range from wireless smart phones to data centers that support millions of web searches, stock trades, or on-line purchases every day. In general, a computing system generates data and/or manipulates data from one form into another. For instance, an image sensor of the computing system generates raw picture data and, using an image compression program (e.g., JPEG, MPEG, etc.), the computing system manipulates the raw picture data into a standardized compressed image. [0008] With continued advances in processing speed and communication speed, computers are capable of processing real time multimedia data for applications ranging from simple voice communications to streaming high definition video. As such, general-purpose information appliances are replacing purpose-built communications devices (e.g., a telephone). For example, smart phones can support telephony communications but they are also capable of text messaging and accessing the internet to perform functions including email, web browsing, remote applications access, and media communications (e.g., telephony voice, image transfer, music files, video files, real time video streaming. etc.). [0009] Each type of computer is constructed and operates in accordance with one or more communication, processing, and storage standards. As a result of standardization and with advances in technology, more and more information content is being converted into digital formats. For example, more digital cameras are now being sold than film cameras, thus producing more digital pictures. As another example, web-based programming is becoming an alternative to over the air television broadcasts and/or cable broadcasts. As further examples, papers, books, video entertainment, home video, etc. are now being stored digitally, which increases the demand on the storage function of computers. [0010] A typical computer storage system includes one or more memory devices aligned with the needs of the various operational aspects of the computer's processing and communication functions. Generally, the immediacy of access dictates what type of memory device is used. For example, random access memory (RAM) memory can be accessed in any random order with a constant response time, thus it is typically used for cache memory and main memory. By contrast, memory device technologies that require physical movement such as magnetic disks, tapes, and optical discs, have a variable response time as the physical movement can take longer than the data transfer, thus they are typically used for secondary memory (e.g., hard drive, backup memory, etc.). [0011] A computer's storage system will be compliant with one or more computer storage standards that include, but are not limited to, network file system (NFS), flash file system (FFS), disk file system (DFS), small computer system interface (SCSI), internet small computer system interface (iSCSI), file transfer protocol (FTP), and web-based distributed authoring and versioning (WebDAV). These standards specify the data storage format (e.g., files, data objects, data blocks, directories, etc.) and interfacing between the computer's processing function and its storage system, which is a primary function of the computer's memory controller. [0012] Despite the standardization of the computer and its storage system, memory devices fail; especially commercial grade memory devices that utilize technologies incorporating physical movement (e.g., a disc drive). For example, it is fairly common for a disc drive to routinely suffer from bit level corruption and to completely fail after three years of use. One solution is to a higher-grade disc drive, which adds significant cost to a computer. [0013] Another solution is to utilize multiple levels of redundant disc drives to replicate the data into two or more copies. One such redundant drive approach is called redundant array of independent discs (RAID). In a RAID device, a RAID controller adds parity data to the original data before storing it across the array. The parity data is calculated from the original data such that the failure of a disc will not result in the loss of the original data. For example, RAID 5 uses three discs to protect data from the failure of a single disc. The parity data, and associated redundancy overhead data, reduces the storage capacity of three independent discs by one third (e.g., n−1=capacity). RAID 6 can recover from a loss of two discs and requires a minimum of four discs with a storage capacity of n−2. [0014] While RAID addresses the memory device failure issue, it is not without its own failures issues that affect its effectiveness, efficiency and security. For instance, as more discs are added to the array, the probability of a disc failure increases, which increases the demand for maintenance. For example, when a disc fails, it needs to be manually replaced before another disc fails and the data stored in the RAID device is lost. To reduce the risk of data loss, data on a RAID device is typically copied on to one or more other RAID devices. While this addresses the loss of data issue, it raises a security issue since multiple copies of data are available, which increases the chances of unauthorized access. Further, as the amount of data being stored grows, the overhead of RAID devices becomes a non-trivial efficiency issue. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS [0015] FIG. 1 is a schematic block diagram of an embodiment of a computing system in accordance with the invention; [0016] FIG. 2 is a schematic block diagram of an embodiment of a computing core in accordance with the invention; [0017] FIG. 3 is a schematic block diagram of an embodiment of a distributed storage processing unit in accordance with the invention; [0018] FIG. 4 is a schematic block diagram of an embodiment of a grid module in accordance with the invention; [0019] FIG. 5 is a diagram of an example embodiment of error coded data slice creation in accordance with the invention; [0020] FIG. 6 is a flowchart illustrating the determination of a data revision number; [0021] FIG. 7 is a flowchart illustrating the retrieving of like revision data; [0022] FIG. 8 is a flowchart illustrating the storing of data; [0023] FIG. 9 is another flowchart illustrating the storing of data; [0024] FIG. 10 is another flowchart illustrating the storing of data; [0025] FIG. 11 is a flowchart illustrating the deleting of data; and [0026] FIG. 12 is a flowchart illustrating the retrieving of data. DETAILED DESCRIPTION OF THE INVENTION [0027] FIG. 1 is a schematic block diagram of a computing system 10 that includes one or more of a first type of user devices 12 , one or more of a second type of user devices 14 , at least one distributed storage (DS) processing unit 16 , at least one DS managing unit 18 , at least one storage integrity processing unit 20 , and a distributed storage network (DSN) memory 22 coupled via a network 24 . The network 24 may include one or more wireless and/or wire lined communication systems; one or more private intranet systems and/or public internet systems; and/or one or more local area networks (LAN) and/or wide area networks (WAN). [0028] The DSN memory 22 includes a plurality of distributed storage (DS) units 36 for storing data of the system. Each of the DS units 36 includes a processing module and memory and may be located at a geographically different site than the other DS units (e.g., one in Chicago, one in Milwaukee, etc.). The processing module may be a single processing device or a plurality of processing devices. Such a processing device may be a microprocessor, micro-controller, digital signal processor, microcomputer, central processing unit, field programmable gate array, programmable logic device, state machine, logic circuitry, analog circuitry, digital circuitry, and/or any device that manipulates signals (analog and/or digital) based on hard coding of the circuitry and/or operational instructions. The processing module may have an associated memory and/or memory element, which may be a single memory device, a plurality of memory devices, and/or embedded circuitry of the processing module. Such a memory device may be a read-only memory, random access memory, volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, cache memory, and/or any device that stores digital information. Note that if the processing module includes more than one processing device, the processing devices may be centrally located (e.g., directly coupled together via a wired and/or wireless bus structure) or may be distributedly located (e.g., cloud computing via indirect coupling via a local area network and/or a wide area network). Further note that when the processing module implements one or more of its functions via a state machine, analog circuitry, digital circuitry, and/or logic circuitry, the memory and/or memory element storing the corresponding operational instructions may be embedded within, or external to, the circuitry comprising the state machine, analog circuitry, digital circuitry, and/or logic circuitry. Still further note that, the memory element stores, and the processing module executes, hard coded and/or operational instructions corresponding to at least some of the steps and/or functions illustrated in FIGS. 1-12 . [0029] Each of the user devices 12 - 14 , the DS processing unit 16 , the DS managing unit 18 , and the storage integrity processing unit 20 may be a portable computing device (e.g., a social networking device, a gaming device, a cell phone, a smart phone, a personal digital assistant, a digital music player, a digital video player, a laptop computer, a handheld computer, a video game controller, and/or any other portable device that includes a computing core) and/or a fixed computing device (e.g., a personal computer, a computer server, a cable set-top box, a satellite receiver, a television set, a printer, a fax machine, home entertainment equipment, a video game console, and/or any type of home or office computing equipment). Such a portable or fixed computing device includes a computing core 26 and one or more interfaces 30 , 32 , and/or 33 . An embodiment of the computing core 26 will be described with reference to FIG. 2 . [0030] With respect to the interfaces, each of the interfaces 30 , 32 , and 33 includes software and/or hardware to support one or more communication links via the network 24 and/or directly. For example, interfaces 30 support a communication link (wired, wireless, direct, via a LAN, via the network 24 , etc.) between the first type of user device 14 and the DS processing unit 16 . As another example, DSN interface 32 supports a plurality of communication links via the network 24 between the DSN memory 22 and the DS processing unit 16 , the first type of user device 12 , and/or the storage integrity processing unit 20 . As yet another example, interface 33 supports a communication link between the DS managing unit 18 and any one of the other devices and/or units 12 , 14 , 16 , 20 , and/or 22 via the network 24 . [0031] In general and with respect to data storage, the system 10 supports three primary functions: distributed network data storage management, distributed data storage and retrieval, and data storage integrity verification. In accordance with these three primary functions, data can be distributedly stored in a plurality of physically different locations and subsequently retrieved in a reliable and secure manner regardless of failures of individual storage devices, failures of network equipment, the duration of storage, the amount of data being stored, attempts at hacking the data, etc. [0032] The DS managing unit 18 performs distributed network data storage management functions, which include establishing distributed data storage parameters, performing network operations, performing network administration, and/or performing network maintenance. The DS managing unit 18 establishes the distributed data storage parameters (e.g., allocation of virtual DSN memory space, distributed storage parameters, security parameters, billing information, user profile information, etc.) for one or more of the user devices 12 - 14 (e.g., established for individual devices, established for a user group of devices, established for public access by the user devices, etc.). For example, the DS managing unit 18 coordinates the creation of a vault (e.g., a virtual memory block) within the DSN memory 22 for a user device (for a group of devices, or for public access). The DS managing unit 18 also determines the distributed data storage parameters for the vault. In particular, the DS managing unit 18 determines a number of slices (e.g., the number that a data segment of a data file and/or data block is partitioned into for distributed storage) and a read threshold value (e.g., the minimum number of slices required to reconstruct the data segment). [0033] As another example, the DS managing module 18 creates and stores, locally or within the DSN memory 22 , user profile information. The user profile information includes one or more of authentication information, permissions, and/or the security parameters. The security parameters may include one or more of encryption/decryption scheme, one or more encryption keys, key generation scheme, and data encoding/decoding scheme. [0034] As yet another example, the DS managing unit 18 creates billing information for a particular user, user group, vault access, public vault access, etc. For instance, the DS managing unit 18 tracks the number of times user accesses a private vault and/or public vaults, which can be used to generate a per-access bill. In another instance, the DS managing unit 18 tracks the amount of data stored and/or retrieved by a user device and/or a user group, which can be used to generate a per-data-amount bill. [0035] The DS managing unit 18 also performs network operations, network administration, and/or network maintenance. As at least part of performing the network operations and/or administration, the DS managing unit 18 monitors performance of the devices and/or units of the system 10 for potential failures, determines the devices and/or unit's activation status, determines the devices' and/or units' loading, and any other system level operation that affects the performance level of the system 10 . For example, the DS managing unit 18 receives and aggregates network management alarms, alerts, errors, status information, performance information, and messages from the devices 12 - 14 and/or the units 16 , 20 , 22 . For example, the DS managing unit 18 receives a simple network management protocol (SNMP) message regarding the status of the DS processing unit 16 . [0036] The DS managing unit 18 performs the network maintenance by identifying equipment within the system 10 that needs replacing, upgrading, repairing, and/or expanding. For example, the DS managing unit 18 determines that the DSN memory 22 needs more DS units 36 or that one or more of the DS units 36 needs updating. [0037] The second primary function (i.e., distributed data storage and retrieval) begins and ends with a user device 12 - 14 . For instance, if a second type of user device 14 has a data file 38 and/or data block 40 to store in the DSN memory 22 , it send the data file 38 and/or data block 40 to the DS processing unit 16 via its interface 30 . As will be described in greater detail with reference to FIG. 2 , the interface 30 functions to mimic a conventional operating system (OS) file system interface (e.g., network file system (NFS), flash file system (FFS), disk file system (DFS), file transfer protocol (FTP), web-based distributed authoring and versioning (WebDAV), etc.) and/or a block memory interface (e.g., small computer system interface (SCSI), internet small computer system interface (iSCSI), etc.). In addition, the interface 30 may attach a user identification code (ID) to the data file 38 and/or data block 40 . [0038] The DS processing unit 16 receives the data file 38 and/or data block 40 via its interface 30 and performs a distributed storage (DS) process 34 thereon (e.g., an error coding dispersal storage function). The DS processing 34 begins by partitioning the data file 38 and/or data block 40 into one or more data segments, which is represented as Y data segments. For example, the DS processing 34 may partition the data file 38 and/or data block 40 into a fixed byte size segment (e.g., 2 1 to 2 n bytes, where n=>2) or a variable byte size (e.g., change byte size from segment to segment, or from groups of segments to groups of segments, etc.). [0039] For each of the Y data segments, the DS processing 34 error encodes (e.g., forward error correction (FEC), information dispersal algorithm, or error correction coding) and slices (or slices then error encodes) the data segment into a plurality of error coded (EC) data slices 42 - 48 , which is represented as X slices per data segment. The number of slices (X) per segment, which corresponds to a number of pillars n, is set in accordance with the distributed data storage parameters and the error coding scheme. For example, if a Reed-Solomon (or other FEC scheme) is used in an n/k system, then a data segment is divided into n slices, where k number of slices is needed to reconstruct the original data (i.e., k is the threshold). As a few specific examples, the n/k factor may be 5/3; 6/4; 8/6; 8/5; 16/10. [0040] For each slice 42 - 48 , the DS processing unit 16 creates a unique slice name and appends it to the corresponding slice 42 - 48 . The slice name includes universal DSN memory addressing routing information (e.g., virtual memory addresses in the DSN memory 22 ) and user-specific information (e.g., user ID, file name, data block identifier, etc.). [0041] The DS processing unit 16 transmits the plurality of EC slices 42 - 48 to a plurality of DS units 36 of the DSN memory 22 via the DSN interface 32 and the network 24 . The DSN interface 32 formats each of the slices for transmission via the network 24 . For example, the DSN interface 32 may utilize an internet protocol (e.g., TCP/IP, etc.) to packetize the slices 42 - 48 for transmission via the network 24 . [0042] The number of DS units 36 receiving the slices 42 - 48 is dependent on the distributed data storage parameters established by the DS managing unit 18 . For example, the DS managing unit 18 may indicate that each slice is to be stored in a different DS unit 36 . As another example, the DS managing unit 18 may indicate that like slice numbers of different data segments are to be stored in the same DS unit 36 . For example, the first slice of each of the data segments is to be stored in a first DS unit 36 , the second slice of each of the data segments is to be stored in a second DS unit 36 , etc. In this manner, the data is encoded and distributedly stored at physically diverse locations to improved data storage integrity and security. Further examples of encoding the data segments will be provided with reference to one or more of FIGS. 2-12 . [0043] Each DS unit 36 that receives a slice 42 - 48 for storage translates the virtual DSN memory address of the slice into a local physical address for storage. Accordingly, each DS unit 36 maintains a virtual to physical memory mapping to assist in the storage and retrieval of data. [0044] The first type of user device 12 performs a similar function to store data in the DSN memory 22 with the exception that it includes the DS processing. As such, the device 12 encodes and slices the data file and/or data block it has to store. The device then transmits the slices 11 to the DSN memory via its DSN interface 32 and the network 24 . [0045] For a second type of user device 14 to retrieve a data file or data block from memory, it issues a read command via its interface 30 to the DS processing unit 16 . The DS processing unit 16 performs the DS processing 34 to identify the DS units 36 storing the slices of the data file and/or data block based on the read command. The DS processing unit 16 may also communicate with the DS managing unit 18 to verify that the user device 14 is authorized to access the requested data. [0046] Assuming that the user device is authorized to access the requested data, the DS processing unit 16 issues slice read commands to at least a threshold number of the DS units 36 storing the requested data (e.g., to at least 10 DS units for a 16/10 error coding scheme). Each of the DS units 36 receiving the slice read command, verifies the command, accesses its virtual to physical memory mapping, retrieves the requested slice, or slices, and transmits it to the DS processing unit 16 . [0047] Once the DS processing unit 16 has received a read threshold number of slices for a data segment, it performs an error decoding function and de-slicing to reconstruct the data segment. When Y number of data segments has been reconstructed, the DS processing unit 16 provides the data file 38 and/or data block 40 to the user device 14 . Note that the first type of user device 12 performs a similar process to retrieve a data file and/or data block. [0048] The storage integrity processing unit 20 performs the third primary function of data storage integrity verification. In general, the storage integrity processing unit 20 periodically retrieves slices 45 , and/or slice names, of a data file or data block of a user device to verify that one or more slices have not been corrupted or lost (e.g., the DS unit failed). The retrieval process mimics the read process previously described. [0049] If the storage integrity processing unit 20 determines that one or more slices is corrupted or lost, it rebuilds the corrupted or lost slice(s) in accordance with the error coding scheme. The storage integrity processing unit 20 stores the rebuild slice, or slices, in the appropriate DS unit(s) 36 in a manner that mimics the write process previously described. [0050] FIG. 2 is a schematic block diagram of an embodiment of a computing core 26 that includes a processing module 50 , a memory controller 52 , main memory 54 , a video graphics processing unit 55 , an input/output (IO) controller 56 , a peripheral component interconnect (PCI) interface 58 , at least one IO device interface module 62 , a read only memory (ROM) basic input output system (BIOS) 64 , and one or more memory interface modules. The memory interface module(s) includes one or more of a universal serial bus (USB) interface module 66 , a host bus adapter (HBA) interface module 68 , a network interface module 70 , a flash interface module 72 , a hard drive interface module 74 , and a DSN interface module 76 . Note the DSN interface module 76 and/or the network interface module 70 may function as the interface 30 of the user device 14 of FIG. 1 . Further note that the IO device interface module 62 and/or the memory interface modules may be collectively or individually referred to as IO ports. [0051] The processing module 50 may be a single processing device or a plurality of processing devices. Such a processing device may be a microprocessor, micro-controller, digital signal processor, microcomputer, central processing unit, field programmable gate array, programmable logic device, state machine, logic circuitry, analog circuitry, digital circuitry, and/or any device that manipulates signals (analog and/or digital) based on hard coding of the circuitry and/or operational instructions. The processing module 50 may have an associated memory and/or memory element, which may be a single memory device, a plurality of memory devices, and/or embedded circuitry of the processing module 50 . Such a memory device may be a read-only memory, random access memory, volatile memory, non-volatile memory, static memory, dynamic memory, flash memory, cache memory, and/or any device that stores digital information. Note that if the processing module 50 includes more than one processing device, the processing devices may be centrally located (e.g., directly coupled together via a wired and/or wireless bus structure) or may be distributedly located (e.g., cloud computing via indirect coupling via a local area network and/or a wide area network). Further note that when the processing module 50 implements one or more of its functions via a state machine, analog circuitry, digital circuitry, and/or logic circuitry, the memory and/or memory element storing the corresponding operational instructions may be embedded within, or external to, the circuitry comprising the state machine, analog circuitry, digital circuitry, and/or logic circuitry. Still further note that, the memory element stores, and the processing module 50 executes, hard coded and/or operational instructions corresponding to at least some of the steps and/or functions illustrated in FIGS. 1-12 . [0052] FIG. 3 is a schematic block diagram of an embodiment of a dispersed storage (DS) processing module 34 of user device 12 and/or of the DS processing unit 16 . The DS processing module 34 includes a gateway module 78 , an access module 80 , a grid module 82 , and a storage module 84 . The DS processing module 34 may also include an interface 30 and the DSnet interface 32 or the interfaces 68 and/or 70 may be part of user 12 or of the DS processing unit 14 . The DS processing module 34 may further include a bypass/feedback path between the storage module 84 to the gateway module 78 . Note that the modules 78 - 84 of the DS processing module 34 may be in a single unit or distributed across multiple units. [0053] In an example of storing data, the gateway module 78 receives an incoming data object that includes a user ID field 86 , an object name field 88 , and the data field 40 and may also receive corresponding information that includes a process identifier (e.g., an internal process/application ID), metadata, a file system directory, a block number, a transaction message, a user device identity (ID), a data object identifier, a source name, and/or user information. The gateway module 78 authenticates the user associated with the data object by verifying the user ID 86 with the managing unit 18 and/or another authenticating unit. [0054] When the user is authenticated, the gateway module 78 obtains user information from the management unit 18 , the user device, and/or the other authenticating unit. The user information includes a vault identifier, operational parameters, and user attributes (e.g., user data, billing information, etc.). A vault identifier identifies a vault, which is a virtual memory space that maps to a set of DS storage units 36 . For example, vault 1 (i.e., user 1 's DSN memory space) includes eight DS storage units (X=8 wide) and vault 2 (i.e., user 2 's DSN memory space) includes sixteen DS storage units (X=16 wide). The operational parameters may include an error coding algorithm, the width n (number of pillars X or slices per segment for this vault), a read threshold T, a write threshold, an encryption algorithm, a slicing parameter, a compression algorithm, an integrity check method, caching settings, parallelism settings, and/or other parameters that may be used to access the DSN memory layer. [0055] The gateway module 78 uses the user information to assign a source name 35 to the data. For instance, the gateway module 60 determines the source name 35 of the data object 40 based on the vault identifier and the data object. For example, the source name may contain a file identifier (ID), a vault generation number, a reserved field, and a vault identifier (ID). As another example, the gateway module 78 may generate the file ID based on a hash function of the data object 40 . Note that the gateway module 78 may also perform message conversion, protocol conversion, electrical conversion, optical conversion, access control, user identification, user information retrieval, traffic monitoring, statistics generation, configuration, management, and/or source name determination. [0056] The access module 80 receives the data object 40 and creates a series of data segments 1 through Y 90 - 92 in accordance with a data storage protocol (e.g., file storage system, a block storage system, and/or an aggregated block storage system). The number of segments Y may be chosen or randomly assigned based on a selected segment size and the size of the data object. For example, if the number of segments is chosen to be a fixed number, then the size of the segments varies as a function of the size of the data object. For instance, if the data object is an image file of 4,194,304 eight bit bytes (e.g., 33,554,432 bits) and the number of segments Y=131,072, then each segment is 256 bits or 32 bytes. As another example, if segment sized is fixed, then the number of segments Y varies based on the size of data object. For instance, if the data object is an image file of 4,194,304 bytes and the fixed size of each segment is 4,096 bytes, the then number of segments Y=1,024. Note that each segment is associated with the same source name. [0057] The grid module 82 receives the data segments and may manipulate (e.g., compression, encryption, cyclic redundancy check (CRC), etc.) each of the data segments before performing an error coding function of the error coding dispersal storage function to produce a pre-manipulated data segment. After manipulating a data segment, if applicable, the grid module 82 error encodes (e.g., Reed-Solomon, Convolution encoding, Trellis encoding, etc.) the data segment or manipulated data segment into X error coded data slices 42 - 44 . [0058] The value X, or the number of pillars (e.g., X=16), is chosen as a parameter of the error coding dispersal storage function. Other parameters of the error coding dispersal function include a read threshold T, a write threshold W, etc. The read threshold (e.g., T=10, when X=16) corresponds to the minimum number of error-free error coded data slices required to reconstruct the data segment. In other words, the DS processing module 34 can compensate for X-T (e.g., 16−10=6) missing error coded data slices per data segment. The write threshold W corresponds to a minimum number of DS storage units that acknowledge proper storage of their respective data slices before the DS processing module indicates proper storage of the encoded data segment. Note that the write threshold is greater than or equal to the read threshold for a given number of pillars (X). [0059] For each data slice of a data segment, the grid module 82 generates a unique slice name 37 and attaches it thereto. The slice name 37 includes a universal routing information field and a vault specific field and may be 48 bytes (e.g., 24 bytes for each of the universal routing information field and the vault specific field). As illustrated, the universal routing information field includes a slice index, a vault ID, a vault generation, and a reserved field. The slice index is based on the pillar number and the vault ID and, as such, is unique for each pillar (e.g., slices of the same pillar for the same vault for any segment will share the same slice index). The vault specific field includes a data name, which includes a file ID and a segment number (e.g., a sequential numbering of data segments 1 -Y of a simple data object or a data block number). [0060] Prior to outputting the error coded data slices of a data segment, the grid module may perform post-slice manipulation on the slices. If enabled, the manipulation includes slice level compression, encryption, CRC, addressing, tagging, and/or other manipulation to improve the effectiveness of the computing system. [0061] When the error coded data slices of a data segment are ready to be outputted, the grid module 82 determines which of the DS storage units 36 will store the EC data slices based on a dispersed storage memory mapping associated with the user's vault and/or DS storage unit 36 attributes. The DS storage unit attributes may include availability, self-selection, performance history, link speed, link latency, ownership, available DSN memory, domain, cost, a prioritization scheme, a centralized selection message from another source, a lookup table, data ownership, and/or any other factor to optimize the operation of the computing system. Note that the number of DS storage units 36 is equal to or greater than the number of pillars (e.g., X) so that no more than one error coded data slice of the same data segment is stored on the same DS storage unit 36 . Further note that EC data slices of the same pillar number but of different segments (e.g., EC data slice 1 of data segment 1 and EC data slice 1 of data segment 2 ) may be stored on the same or different DS storage units 36 . [0062] The storage module 84 performs an integrity check on the outbound encoded data slices and, when successful, identifies a plurality of DS storage units based on information provided by the grid module. The storage module then outputs the encoded data slices 1 through X of each segment 1 through Y to the DS storage units. Each of the DS storage units 36 stores its EC data slice(s) and maintains a local virtual DSN address to physical location table to convert the virtual DSN address of the EC data slice(s) into physical storage addresses. [0063] In an example of a read operation, the user device 12 and/or 14 sends a read request to the DS processing unit 14 , which authenticates the request. When the request is authentic, the DS processing unit 14 sends a read message to each of the DS storage units 36 storing slices of the data object being read. The slices are received via the DSnet interface 32 and processed by the storage module 84 , which performs a parity check and provides the slices to the grid module 82 when the parity check was successful. The grid module 82 decodes the slices in accordance with the error coding dispersal storage function to reconstruct the data segment. The access module 80 reconstructs the data object from the data segments and the gateway module 78 formats the data object for transmission to the user device. [0064] FIG. 4 is a schematic block diagram of an embodiment of a grid module 82 that includes a control unit 73 , a pre-slice manipulator 75 , an encoder 77 , a slicer 79 , a post-slice manipulator 81 , a pre-slice de-manipulator 83 , a decoder 85 , a de-slicer 87 , and/or a post-slice de-manipulator 89 . Note that the control unit 73 may be partially or completely external to the grid module 82 . For example, the control unit 73 may be part of the computing core at a remote location, part of a user device, part of the DS managing unit 18 , or distributed amongst one or more DS storage units. [0065] In an example of write operation, the pre-slice manipulator 75 receives a data segment 90 - 92 and a write instruction from an authorized user device. The pre-slice manipulator 75 determines if pre-manipulation of the data segment 90 - 92 is required and, if so, what type. The pre-slice manipulator 75 may make the determination independently or based on instructions from the control unit 73 , where the determination is based on a computing system-wide predetermination, a table lookup, vault parameters associated with the user identification, the type of data, security requirements, available DSN memory, performance requirements, and/or other metadata. [0066] Once a positive determination is made, the pre-slice manipulator 75 manipulates the data segment 90 - 92 in accordance with the type of manipulation. For example, the type of manipulation may be compression (e.g., Lempel-Ziv-Welch, Huffman, Golomb, fractal, wavelet, etc.), signatures (e.g., Digital Signature Algorithm (DSA), Elliptic Curve DSA, Secure Hash Algorithm, etc.), watermarking, tagging, encryption (e.g., Data Encryption Standard, Advanced Encryption Standard, etc.), adding metadata (e.g., time/date stamping, user information, file type, etc.), cyclic redundancy check (e.g., CRC32), and/or other data manipulations to produce the pre-manipulated data segment. [0067] The encoder 77 encodes the pre-manipulated data segment 92 using a forward error correction (FEC) encoder (and/or other type of erasure coding and/or error coding) to produce an encoded data segment 94 . The encoder 77 determines which forward error correction algorithm to use based on a predetermination associated with the user's vault, a time based algorithm, user direction, DS managing unit direction, control unit direction, as a function of the data type, as a function of the data segment 92 metadata, and/or any other factor to determine algorithm type. The forward error correction algorithm may be Golay, Multidimensional parity, Reed-Solomon, Hamming, Bose Ray Chauduri Hocquenghem (BCH), Cauchy-Reed-Solomon, or any other FEC encoder. Note that the encoder 77 may use a different encoding algorithm for each data segment 92 , the same encoding algorithm for the data segments 92 of a data object, or a combination thereof. [0068] The encoded data segment 94 is of greater size than the data segment 92 by the overhead rate of the encoding algorithm by a factor of X/T, where X is the width or number of slices, and T is the read threshold. In this regard, the corresponding decoding process can accommodate at most X−T missing EC data slices and still recreate the data segment 92 . For example, if X=16 and T=10, then the data segment 92 will be recoverable as long as 10 or more EC data slices per segment are not corrupted. [0069] The slicer 79 transforms the encoded data segment 94 into EC data slices in accordance with the slicing parameter from the vault for this user and/or data segment 92 . For example, if the slicing parameter is X=16, then the slicer slices each encoded data segment 94 into 16 encoded slices. [0070] The post-slice manipulator 81 performs, if enabled, post-manipulation on the encoded slices to produce the EC data slices. If enabled, the post-slice manipulator 81 determines the type of post-manipulation, which may be based on a computing system-wide predetermination, parameters in the vault for this user, a table lookup, the user identification, the type of data, security requirements, available DSN memory, performance requirements, control unit directed, and/or other metadata. Note that the type of post-slice manipulation may include slice level compression, signatures, encryption, CRC, addressing, watermarking, tagging, adding metadata, and/or other manipulation to improve the effectiveness of the computing system. [0071] In an example of a read operation, the post-slice de-manipulator 89 receives at least a read threshold number of EC data slices and performs the inverse function of the post-slice manipulator 81 to produce a plurality of encoded slices. The de-slicer 87 de-slices the encoded slices to produce an encoded data segment 94 . The decoder 85 performs the inverse function of the encoder 77 to recapture the data segment 90 - 92 . The pre-slice de-manipulator 83 performs the inverse function of the pre-slice manipulator 75 to recapture the data segment. [0072] FIG. 5 is a diagram of an example of slicing an encoded data segment 94 by the slicer 79 . In this example, the encoded data segment includes thirty-two bits, but may include more or less bits. The slicer 79 disperses the bits of the encoded data segment 94 across the EC data slices in a pattern as shown. As such, each EC data slice does not include consecutive bits of the data segment 94 reducing the impact of consecutive bit failures on data recovery. For example, if EC data slice 2 (which includes bits 1, 5, 9, 13, 17, 25, and 29) is unavailable (e.g., lost, inaccessible, or corrupted), the data segment can be reconstructed from the other EC data slices (e.g., 1, 3 and 4 for a read threshold of 3 and a width of 4). [0073] FIG. 6 is a flowchart illustrating the determination of a data revision number where the DS processing determines the revision number and appends it to, or associates it with EC data slices being distributedly stored. The DS processing subsequent retrieval of EC data slices verifies that the slices utilized to recreate the data segment have the same appended revision number to improve data consistency and system performance. The retrieval method will be discussed in greater detail with reference to FIG. 7 . [0074] The method 600 begins with the step 602 where the DS processing creates EC data slices for a data segment in accordance with the operational parameters as previously discussed. As illustrated by block 604 , the DS processing determines the revision number for the slices of the data segment based on one or more of a timestamp, a random number, the user vault ID, the user ID, the data object ID, a hash of the data object, and/or a hash of the data object ID. For example, the revision number may be eight bytes and comprise a UNIX time timestamp and a random number (e.g., to provide an improvement of a unique revision number when data is stored at the same time). [0075] As illustrated by block 606 , the DS processing appends the revision number to each pillar slice of the same data segment such that each pillar slice of the same data segment has the same revision number. In an embodiment, the DS processing appends the same revision number to all the slices of all the data segments of the data object. In another embodiment, the DS processing appends the same revision number to all the slices of each data segment but the revision numbers from data segment to data segment of the data object are different. [0076] As illustrated by block 608 , the DS processing determines the DS units to send the slices to in accordance with the virtual DSN address to physical location table for the user vault of the data object. [0077] As illustrated by block 610 , the DS processing sends a write command and slices with the appended revision number to the DS units such that the DS units will store the slices and send a write confirmation message to the DS processing in response. Note that the slices are substantially sent in parallel from the DS processing to the DS units via similar or different portions of the network. Networks are known to fail from time to time thus all of the DS units may not receive the slices. As a result of network failures and other potential issues, the DS units may contain slices with different revision numbers for the same data object and/or data segment. [0078] The DS processing receives the write confirmation message from the DS units. The DS processing determines a write threshold (e.g., from the user vault, a command, a predetermination) where the write threshold is the minimum number of pillars required to store the unique slices of the same data segment to meet the criteria of a favorable write sequence. The write threshold is less than the pillar width n and greater than the read threshold (discussed previously). [0079] As illustrated by blocks 612 and 616 , the DS processing determines if the number of received write confirmation messages is equal to or greater than the write threshold. The determination may be based on one or more of comparing the number of received write confirmations to the write threshold, a command, a predetermination, and/or a system performance indicator. The DS processing may continue to keep checking for new write confirmations when the DS processing determines that the number of received write confirmation messages is not equal to or greater than the write threshold. As further illustrated by block 616 , the DS processing may fail the write sequence if a predetermined period of time expires before the DS processing determines that the number of received write confirmation messages is equal to or greater than the write threshold. [0080] As illustrated by blocks 614 , the DS processing sends a write commit command to the DS units when the DS processing determines that the number of received write confirmation messages is equal to or greater than the write threshold. The DS unit makes the slice visible on subsequent retrievals when the DS unit receives the write commit command for slices the DS unit has write confirmed. [0081] The DS unit may request the slice be resent from the DS processing when the DS unit receives the write commit command for slices the DS unit has not write confirmed. The DS processing sends the write command and slices with the appended revision number to the DS units such that the DS units will store the slices and send a write confirmation message to the DS processing in response when the DS processing receives the slice request from the DS unit. [0082] FIG. 7 is a flowchart illustrating the retrieving of like revision data where the DS processing retrieves slices from the DS unit pillars and verifies that the slices have the same appended revision numbers to improve data consistency. [0083] According to method 700 , at block 702 the DS processing determines the DS units (the pillars) to retrieve slices from in accordance with the virtual DSN address to physical location table for the user vault of the data object. As further illustrated by block 702 , the DS processing sends a retrieve command message to the DS units where the message includes the slice name. The DS processing sends the retrieve command to at least a read threshold number of DS units. For example, the DS processing sends the retrieve command to ten DS units in a 16/10 DSN system. In another example, the DS processing sends the retrieve command to twelve DS units in a 16/10 DSN system to provide better performance. The DS processing may create and temporarily save a list of DS units that were sent the retrieve command such that the DS processing may choose different DS units in a subsequent retrieval attempt if the present retrieval attempt fails. DS units send the slice and appended revision number corresponding the slice name to the DS processing when the DS unit receives the retrieval command message. [0084] As illustrated by block 704 , the DS processing receives the slices and appended revision number from the DS units. The DS processing determines the number of received slices by counting them. The DS processing determines the read threshold number for this vault by retrieving the read threshold number form the vault. The DS processing proceeds to the next step when the DS processing determines that at least a read threshold number of slices have been received from the DS units. [0085] As illustrated by blocks 706 and 708 , the DS processing determines if the appended revision numbers for the slices from each of the DS units are the same by comparing the revision numbers. Note that it is possible for some of the revision numbers to be different (e.g., as a result of a failure of a previous write sequence or some other DS unit failure). [0086] As illustrated by block 710 , the DS processing determines different DS units to send retrieval commands and the DS processing sends the retrieve command to at least a read threshold number of DS units when the appended revision numbers for the slices from each of the current DS units are not the same. The determination may be based on which DS units were already tried (saved previously) and which of those were in a majority where the majority had the same revision number. In such a scenario, the DS processing need only send a retrieval command message to a smaller set of DS units that have not been tried yet. The method branches to the step of the DS processing receiving a read threshold number of slices with appended revision numbers from the DS units. [0087] As illustrated by block 712 , the DS processing de-slices and decodes the slices to produce the data segment when the appended revision numbers for the slices from each of the current DS units are the same. [0088] FIG. 8 is a flowchart illustrating the storing of data where the DS processing utilizes a transaction process to improve data consistency. [0089] The method 800 begins at block 802 , where the DS processing receives a data object to store (e.g., from the user device). As illustrated by block 804 , the DS processing creates the slices in accordance with the operational parameters and appends revision numbers created as previously discussed with reference to FIG. 6 . The DS processing determines the DS units and sends a write command and the slices with the appended revision numbers. The determination may be based on the virtual DSN address to physical location table. [0090] As further illustrated by block 804 , the DS unit sends a write command confirmation message to the DS processing in response to receiving the write command. The DS processing receives the write command confirmation messages, counts them, and determines if a write threshold number of confirmations has been received by comparing the count of received write command confirmation messages to the write threshold. The DS processing sends a write commit command to the DS units where the DS processing received a write command confirmation message. Note that now the newest revision is successfully stored in the DSN. [0091] In the next steps, the DS processing stores the directory in the DSN memory where the directory links the user root file to the data object to the slice name and revisions. In other words, the directory maps the data object to locations of encoded data slices generated from the data objects. These locations may be virtual DSN addresses, such as a source name or slice name that is further translated, e.g., via a lookup in a virtual DSN address to physical location table, to the DS unit locations, e.g., DS unit identifier. [0092] As illustrated by block 808 , the DS processing determines the current directory (e.g., reading it in the DS processing file system, receiving it from the user device, etc.) and caches it locally in the DS processing. As shown at block 810 , the DS processing creates slices for the current directory and sends the slices with the write command and a revision number (e.g., the directory is assigned a revision number) to the DS units associated with the user vault. After caching the current directory, and before sending the directory slices to be stored, a new entry can be added to represent the directory slices. The DS units receive the slices and write command and will process the write sequence as will be discussed in greater with reference to FIG. 9 . [0093] As illustrated by blocks 812 and 814 , the DS processing determines the response from the DS units where the response may be a write failure or a write success (e.g., a write command confirmation). The write failure may result from one or more of the slice names were already write locked (e.g., an active write transaction was already in process), the DS processing determines that the number of write confirmations is below the write threshold, and/or the number of write confirmations with the same revision numbers is below the write threshold. [0094] As illustrated by block 814 , the DS processing branches back to the step of determining the directory when the DS processing determines the response from the DS units is a write failure. [0095] As illustrated by block 816 , the DS processing sends a write commit command to the DS units where the DS processing received successful write confirmations when the DS processing determines the response from the DS units is a write success. Note that this step will activate the revision of the current directory. [0096] FIG. 9 is another flowchart illustrating the storing of data where the DS unit processes write transactions in accordance with a transaction process to improve the consistency of stored data. [0097] The method 900 begins at block 902 , where the DS unit receives a write command, slice name, revision number, and slice for storage. The DS unit may determine if this slice name is already in a write locked state (e.g., in an active write sequence) by a lookup. The DS unit may send a write lock failure message to the DS processing when the DS unit determines that this slice name is already in a write locked state. [0098] As illustrated by block 904 , the DS unit may invoke write lock (e.g., write in a local table for this slice name) for this slice name when the DS unit determines that this slice name is not already in a write locked state. [0099] As illustrated by block 906 , the DS unit stores the slice and revision and sends a write confirmation command message to the DS processing where the message includes the write confirmation, the slice name, and the revision. [0100] As illustrated by block 908 , the DS unit starts a rollback timer where the time value may be determined by the DS unit based on a predetermined value (e.g., a lookup) or a variable value based in part on a system performance indicator. For example, a longer rollback timer may be determined when the system performance indicator indicates that the system is busier than the average. [0101] As illustrated by block 910 , the DS unit determines if the write commit command has been received from the DS processing when the rollback timer is active. As illustrated by block 912 , the DS unit removes the write lock and makes the slice visible in subsequent retrievals when the DS unit determines that a receive commit was received while the rollback timer is active. [0102] As illustrated by block 914 , the DS unit determines if the rollback timer has expired when the DS unit determines that a receive commit has not been received while the rollback timer is active. The DS unit branches back to the step of determining if a write commit command has been received when the DS unit determines that the rollback timer has not expired. [0103] As illustrated by block 916 , the DS unit rolls back the version to the previous slice version (e.g., subsequent retrievals will provide the last version, not the current version), removes the write lock for this slice name, and may delete the current version when the DS unit determines that the rollback timer has expired. [0104] Generally, after a write the DS unit may either commit or rollback. A rollback may be implemented in response to a rollback request, or in response to a failure to receive a commit command. Both a commit and a rollback result in the write lock for the slice being removed. In other embodiments, the same behavior as receiving a rollback request, can be implemented using an inactivity timer. In various embodiments, rolling back a request does not necessarily restore a slice to its previous version, because in general the state of the latest slice is changed using a commit procedure. Instead any temporary memory used for holding an uncommitted slice is freed. Also, when a slice is committed, any previous revisions for that slice continue to exist. [0105] FIG. 10 is another flowchart illustrating the storing of data where the DS unit stores a revision. [0106] The method 1000 begins at block 1002 , with the DS unit receiving a write command, slice name, slice, and revision from the DS processing. As illustrated by block 1004 , the DS unit determines a local timestamp where in an embodiment the timestamp may be a UNIX time timestamp. [0107] As illustrated by block 1006 , the DS unit stores the slice, revision, and timestamp. Note that the DS unit may not delete previous revisions of slices of the same data object such that the data object may be subsequently retrieved from previous revisions based in part on the timestamp. [0108] FIG. 11 is a flowchart illustrating the deleting of data where the DS unit processes a delete sequence for a revision. [0109] The method 1100 begins at block 1102 with the DS unit receiving a delete command, slice name, and revision from the DS processing. In various embodiments, delete commands may not be used; instead a write command is used to cause the DS unit to “write” a delete marker. As illustrated at block 1104 , the DS unit determines a local timestamp where in an embodiment the timestamp may be a UNIX time timestamp. [0110] As illustrated as block 1106 , the DS unit appends the timestamp and a delete marker to the slice. Note that the DS unit may not delete the slice in favor of marking when the delete command was received. In another embodiment, the DS unit deletes selective slices to free up memory while preserving at least a read threshold number of slices per data such that the data object may be subsequently retrieved from previous revisions based in part on the timestamp. [0111] FIG. 12 is a flowchart illustrating the retrieving of data where the DS unit retrieves a particular revision of a data segment (e.g., of a data object) based in part on the timestamp. In other words, the DS unit will retrieve sluices of a snapshot of the data object. [0112] The method 1200 begins at block 1202 with the DS unit receiving a read command, slice name, and timeframe from a requester (e.g., the DS processing unit, the DS managing unit, the storage integrity processing unit, or the user device). Note that the timeframe may or may not be exactly aligned with timestamps associated with previous revisions. As illustrated by block 1204 , the DS unit determines which local timestamp is closest to the timeframe based on a comparison of timestamps to the timeframe. [0113] As illustrated by block 1206 , the DS unit determines the slice for the timestamp based on a lookup. Note that this slice revision represents the snapshot closest to the received timeframe. As illustrated at block 1208 , the DS unit retrieves the slice and revision and sends the slice and revision to the requester. [0114] In some embodiments, a read request returns all available revisions, rather than a specific version or versions associated with a specific time frame. When all revisions are returned in response to a read request, the DS processing unit can determine the best way to handle the various revisions received. [0115] As may be used herein, the terms “substantially” and “approximately” provides an industry-accepted tolerance for its corresponding term and/or relativity between items. Such an industry-accepted tolerance ranges from less than one percent to fifty percent and corresponds to, but is not limited to, component values, integrated circuit process variations, temperature variations, rise and fall times, and/or thermal noise. Such relativity between items ranges from a difference of a few percent to magnitude differences. As may also be used herein, the term(s) “coupled to” and/or “coupling” and/or includes direct coupling between items and/or indirect coupling between items via an intervening item (e.g., an item includes, but is not limited to, a component, an element, a circuit, and/or a module) where, for indirect coupling, the intervening item does not modify the information of a signal but may adjust its current level, voltage level, and/or power level. As may further be used herein, inferred coupling (i.e., where one element is coupled to another element by inference) includes direct and indirect coupling between two items in the same manner as “coupled to”. As may even further be used herein, the term “operable to” indicates that an item includes one or more of power connections, input(s), output(s), etc., to perform one or more its corresponding functions and may further include inferred coupling to one or more other items. As may still further be used herein, the term “associated with”, includes direct and/or indirect coupling of separate items and/or one item being embedded within another item. As may be used herein, the term “compares favorably”, indicates that a comparison between two or more items, signals, etc., provides a desired relationship. For example, when the desired relationship is that signal 1 has a greater magnitude than signal 2 , a favorable comparison may be achieved when the magnitude of signal 1 is greater than that of signal 2 or when the magnitude of signal 2 is less than that of signal 1 . [0116] The present invention has also been described above with the aid of method steps illustrating the performance of specified functions and relationships thereof. The boundaries and sequence of these functional building blocks and method steps have been arbitrarily defined herein for convenience of description. Alternate boundaries and sequences can be defined so long as the specified functions and relationships are appropriately performed. Any such alternate boundaries or sequences are thus within the scope and spirit of the claimed invention. [0117] The present invention has been described above with the aid of functional building blocks illustrating the performance of certain significant functions. The boundaries of these functional building blocks have been arbitrarily defined for convenience of description. Alternate boundaries could be defined as long as the certain significant functions are appropriately performed. Similarly, flow diagram blocks may also have been arbitrarily defined herein to illustrate certain significant functionality. To the extent used, the flow diagram block boundaries and sequence could have been defined otherwise and still perform the certain significant functionality. Such alternate definitions of both functional building blocks and flow diagram blocks and sequences are thus within the scope and spirit of the claimed invention. One of average skill in the art will also recognize that the functional building blocks, and other illustrative blocks, modules and components herein, can be implemented as illustrated or by discrete components, application specific integrated circuits, processors executing appropriate software and the like or any combination thereof.

Multiple revisions of an encoded data slice can be stored in a distributed storage unit. Before writing a new revision of an encoded data slice to storage, the distributed storage unit can invoke a write lock for all encoded data slices having the same slice name as the slice being currently written. The slice being currently written can be stored in temporary storage, and a rollback timer started. If a commit command is received before expiration of the rollback timer, the currently written slice can be permanently stored and made accessible for read requests. If the rollback timer expires prior to the storage unit receiving a commit command, however, a previously stored revision will be used.

This application claims priority to Provisional Application Ser. No. 61/480,424 filed Apr. 29, 2011, the content of which is incorporated by reference. BACKGROUND The present invention relates to resource allocation in multi-cellular networks. The exponentially increasing demand for data (particularly in the downlink) has ensured that future wireless cellular networks will be interference-limited. This necessitates a careful handling of inter-cell interference. Indeed substantial performance gains are possible if inter-cell interference is managed via coordinated resource allocation across multiple cells. Studies on coordinated processing assumed that both data and channel state information of all users are shared in real-time. However, in practice coordination is possible only on a per-cluster basis. Furthermore, the limited backhaul bandwidth essentially prevents real-time data sharing. Thus, it is reasonable to assume that each user can be served by only one base station. Nevertheless, downlink beam-vectors can still be optimized based on the inter-cell channel qualities and has been considered. The application of linear transmit precoding over interference limited networks has been bolstered by recent degree-of-freedom (DoF) optimality results for interference alignment schemes (that involve linear precoding) for time-varying or frequency-selective interference channels. More importantly, realizing its benefits, fourth generation cellular standards such as LTE-A—CoMP: Coordinated Multi-Point TX/RX and IEEE 802.16m—Multi-BS MIMO have enabled coordinated linear transmit precoding among multiple cells albeit based on limited exchange of channel state information (CSI). Unfortunately, the optimal multi-cell linear precoding design problems are known to be hard even when perfect and global CSI is available. In particular, the weighted sum rate optimization problem even in the SISO interference channel with perfect CSI was shown to be NP hard. Consequently distributed and iterative algorithms that seek sub-optimal solutions have been proposed under both perfect CSI and imperfect CSI. Practical resource allocation problems are inherently mixed optimization problems. This is because while the precoders can often be matrices with arbitrary complex-valued entries (subject to power constraints), most of the resources that have to be assigned to the users (such as frequency sub-carriers, modulations, among others) are discrete in nature. In order to handle the discrete aspect of our resource allocation problems we leverage sub-modular optimization techniques that can often provide a worst-case guarantee even when a low-complexity greedy algorithm is employed. We consider a cluster of cells communicating over multiple orthogonal slots in a coordinated fashion such that each user is associated with (and is served by) a particular cell and where intra-cell interference is avoided by ensuring users associated with the same cell are not simultaneously served on the same slot. In the following, we will use the terms user and mobile device interchangeably. Similarly the terms base station and source are also used interchangeably. Under this setup, we formulate and analyze three important versions of practical downlink multi-cell coordinated resource allocation under the following practical constraints that significantly reduce the signaling overhead and will be ubiquitous in the emerging 4G cellular networks. The first constraint is that in any scheduling interval each scheduled user can be served using only one or at-most two distinct modulations. In practical systems, each modulation must be one out of 4, 16 or 64 QAM. On other hand powerful Turbo codes of several distinct coding rates are available. Hence it is reasonable to assume that for each QAM alphabet, ideal outer codes of a continuum of coding rates in are available. In addition to the above constraint, each scheduled user can be served using only one rank, i.e., the ranks of all the precoding matrices used to serve a particular user in a scheduling interval must be identical. Thus, while a different precoding matrix can be used to serve a particular user on each of its assigned slots, all these matrices must have a common rank. In certain systems with more stringent signaling overhead constraints, in any scheduling interval each scheduled user can be served by only one distinct precoding matrix drawn from a pre-defined finite codebook, over all slots assigned to that user. SUMMARY In one aspect, a system is disclosed that performs coordinated resource allocation among multiple cells in a cellular downlink. Three predetermined coordinated resource allocation problems are formulated as optimization problems that comply with certain predetermined constraints. In another aspect, a method allocates resources in a wireless system to optimize communication between a set of sources and a plurality of mobile wireless devices over a plurality of orthogonal resource slots by: enforcing each source to transmit to at-most one device over each orthogonal slot; enforcing that the number of data streams transmitted by a source to a device is identical on all slots on which the said source transmits to the said device; and optimizing a metric responsive to the assignment of resource slots to mobile devices by each source in the set. Advantages of the preferred embodiments may include one or more of the following. The system uses low complexity approximation methods that yield performance guarantees. These processes exploit the fact that either the original problems or some of their sub-problems can be recast as the maximization of a monotonic sub-modular function under a matroid constraint. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an exemplary system for resource allocation in a multi-cellular downlink. FIGS. 2 , 4 and 6 show exemplary scenarios for coordinated resource allocation. FIG. 3 shows an exemplary process for allocating resources in the scenario of FIG. 2 . FIG. 5 shows an exemplary process that handles constrained resource allocation in multi-source networks with interference cancellation. FIG. 7 shows an exemplary process that handles constrained resource allocation in multi-source networks with interference avoidance. DESCRIPTION Various embodiments are now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments. It may be evident, however, that such embodiment(s) may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing one or more embodiments. In the following paragraphs, the present invention will be described in detail by way of example with reference to the attached drawings. Throughout this description, the preferred embodiment and examples shown should be considered as exemplars, rather than as limitations on the present invention. As used herein, the “present invention” refers to any one of the embodiments of the invention described herein, and any equivalents. Furthermore, reference to various feature(s) of the “present invention” throughout this document does not mean that all claimed embodiments or methods must include the referenced feature(s). The system may be implemented in hardware, firmware or software, or a combination of the three. Preferably the invention is implemented in a computer program executed on a programmable computer having a processor, a data storage system, volatile and non-volatile memory and/or storage elements, at least one input device and at least one output device. FIG. 1 shows an exemplary system for resource allocation in a multi-cellular downlink. In FIG. 1 , multiple sources TX 1 and TX 2 can communicate with multiple intended receivers RX 1 a , RX 1 b , RX 1 c , RX 2 a , RX 2 b simultaneously on the same channel. This can lead to significant inter-cell interference and degrade throughput. On the other hand, allowing only one or a few sources to communicate may also be quite sub-optimal. The system of FIG. 1 overcomes Interference and Limited Over-the-Air (OTA) Signaling before spectral efficiency gains can be realized. The OTA signaling problems include limited channel state information (CSI) feedback from users and constraints on scheduling flexibility. The system also handles complexity constraints on scheduling at the base stations. The system of FIG. 1 avoids intra-cell interference by enforcing per-cell orthogonality, i.e., each base-station (BS) only talks to at-most one user on each one of its multiple slots. Next, three relevant scenarios are shown in FIGS. 2 , 4 and 6 for coordinated resource allocation. The system handles these scenarios efficiently through processes shown in FIGS. 3 , 5 and 7 . Turning now to FIG. 2 , one exemplary interference suppression condition is shown. In this scenario, resource allocation (Scheduling) under Interference Suppression is handled. Here: 1) Each scheduled user suppresses interference from signals intended for co-slot other cell users via linear filtering 2) Interference covariance can be estimated by a scheduled user without explicit signaling about the interferers. 3) Full scheduling flexibility can be enjoyed since signaling overhead is not a bottleneck. This examplary arrangement includes a multi-cell downlink comprising of M cells and N orthogonal resource slots that are available in each scheduling interval. In this example for Interference Suppression, M=2 cells (sources), N=4 slots. FIG. 3 shows an exemplary process for allocating resources in the scenario of FIG. 2 . First, during initialization, a feasible assignment is done for each cell and a probability determin parameter is set for each cell ( 310 ). Next, at each base station, for each cell q=1 . . . M, the process fixes the current assignment of all other cells to determine a good feasible assignment for a cell q ( 312 ). The process then sets q=1 ( 314 ) and then iterates q=1 to q=M as follows. First, the process checks to see if q>M ( 314 ). If not, the process probabilistically updates base station q to its good feasible assignment determined in ( 312 ). If the good assignment is chosen, the process conveys the assignment to the other base stations ( 318 ). Then the process checks the next station ( 320 ). Once all base stations have been checked, each base station receives the updated assignments from the other base stations and determines the system rate using the updated assignments ( 322 ). The process then checks convergence criteria ( 324 ) and if convergence is not achieved, then the process loops back to ( 312 ) to continue processing. Otherwise, the process outputs the base station assignments and exits ( 326 ). Next, an exemplary constrained resource allocation in multi-source networks with interference cancellation is shown in FIG. 4 with M=2 sources, N=4 slots. In this example, scheduled users can now cancel interference from signals intended for co-slot other cell users. The interference cancellation involves decoding the codewords intended for other users. This can be realized with a reasonable signaling overhead if we impose scheduling restrictions. We now enforce that each scheduled user must see the same set of co-slot other cell users or any subset of those other cell users. FIG. 5 shows an exemplary process that handles constrained resource allocation in multi-source networks with interference cancellation. During initialization, the process sets G to be the set of all multi cell allocation elements and S to be an empty set ( 502 ). Next, the process iterates from 510 - 516 . In 510 , the process selects the best multi-cell allocation element from G that is feasible under constrained scheduling with respect to allocations in S. The process then checks if the system can be improved by adding the best allocation element to S ( 512 ). If so, the best allocation element is added to S and that element is removed from G ( 514 ). The process checks if G is empty and if not, loops back to 510 . If G is empty in 516 , or if adding the best allocation element does not improve the system rate in 512 , the process outputs S and exits ( 518 ). FIG. 6 shows an exemplary scenario for scheduling under Interference Avoidance. In this case, at-most one user across all M cells can be scheduled on each slot. In this examplary scheduling under Interference Avoidance, M=2 sources, N=4 slots. FIG. 7 shows an exemplary process that handles constrained resource allocation in multi-source networks with interference avoidance. During initialization, the process sets G to be the set of all single cell allocation elements and S to be an empty set ( 602 ). Next, the process iterates from 610 - 616 . In 610 , the process selects the best single-cell allocation element from G that is feasible under constrained scheduling with respect to allocations in S. The process then checks if the system can be improved by adding the best allocation element to S ( 612 ). If so, the best allocation element is added to S and that element is removed from G ( 614 ). The process checks if G is empty and if not, loops back to 610 . If G is empty in 616 , or if adding the best allocation element does not improve the system rate in 612 , the process outputs S and exits ( 618 ). We consider a downlink cellular network with universal frequency reuse where a cluster of M coordinated base stations simultaneously transmit on N orthogonal (in the time or frequency or code domain) resource slots during each scheduling interval. Each base station (BS) is equipped with P antennas and serves at-most one multi-antenna user (mobile) on each resource slot. Moreover, each user is served by only its anchor base station and the association of each user to an anchor BS is pre-determined. In addition the coordinated base stations only exchange channel quality related measurements. Let B q denote the set of users that can be served by the BS q, where q=1, . . . , M. Without loss of generality, we assume that each user is identified by a unique index so that B q 1 ∩B q 2 =Ø for q 1 ≠q 2 . Then, let B q (n) be the terminal scheduled by base station q on slot n, for q=1, . . . , M and n=1, . . . , N. An intra-cell orthogonality constraint is imposed, i.e., each BS can schedule at-most one user on each one of the N slots in a scheduling interval so that |B q (n)|≦1∀q,n. The signal transmitted by base station q on slot n can then be expressed as x q ( n )= W q,k ( n ) b q,k ( n )ε P , kε q ( n ),  (1) where b q,k (n) is the complex symbol vector transmitted by base station q on slot n to user kεB q (n) using the precoding matrix W q,k (n). We assume that E[b q,k (n)b q,k † (n)]=I, E[b q 1 k 1 (n 1 )b q 2 k 2 † (n 2 )]=0 for (n 1 ,q 1 ,k 1 )≠(n 2 ,q 2 ,k 2 ) and that tr ( W q,k ( n ) W q,k ( n ) † )≦ q ,max, where P q,max is the pre-determined maximum per-slot transmit power at base station q. Next, assuming that the maximum propagation delay within the cluster of coordinated base stations is small compared to the inverse of the signal bandwidth, the signal received by user kεB q (n) on slot n can be written as y k ⁡ ( n ) = ∑ j = 1 M ⁢ ⁢ H k , j ⁡ ( n ) ⁢ x j ⁡ ( n ) + z k ⁡ ( n ) , ( 2 ) where H k,j (n) models the MIMO channel between base station j and user k on slot n (which includes small-scale fading, large-scale fading and path attenuation), while z k (n) is the additive circularly-symmetric Gaussian noise vector. Next, for each user k we can define a finite set of formats k which can consist of (constellation(s), precoding rank) pairs or can consist of (constellation(s), precoding matrix) pairs. Thus the practical constraints mentioned before can be enforced by imposing that each scheduled user can be served using any one format drawn from its format set in a scheduling interval. Further, for some channel realizations it may be optimal (with respect to the system utility or system rate) to let only a subset of the M base-stations transmit on a slot. To allow for such a possibility, we insert a dummy user θ q in q, ∀q which can be only served using a dummy format ζ q . Thus, selecting (θ q , ζ q ) as the (user,format) pair for BS q on a slot means that BS q does not transmit on that slot. Next, scheduling under Inter-Cell Interference Suppression is discussed. We consider scheduling in the scenario where each scheduled user suppresses the inter-cell interference (caused by co-slot signals intended for users in other cells) via linear filtering. Consequently, a scheduled user does not need to know the constellations and coding rates assigned to the co-scheduled other-cell users and a user can be scheduled with any set of other-cell users on each of its assigned slots. These facts make this scenario one of dominant interest in practical systems. In order to formulate our optimization problem, we define a set Ω whose elements are M-tuples of (user, format) pairs, i.e., Ω={(ω (1) ,ω (2) , . . . ,ω (M) ):ω (q) =( u,ƒ ), uε q , ƒfε u , ∀1≦ q≦M} Let ={1, . . . , N} denote the set of orthogonal slots. We define a per-slot system utility or rate-function r:Ω× →IR+ such that r((ω (1) , ω (2) , . . . , ω (M) ), n) yields the system weighted sum-rate on slot n obtained upon assigning (ω (1) , ω (2) , . . . , ω (M) )εΩ to slot n. While our formulation allows for any general rate-function, the two cases of interest are the following: The first case is one where each format specifies constellation(s) and a rank. In this case, for any choice (ω (1) , ω (2) , . . . , ω (M) )εΩ the precoding matrices can be designed on a per-slot basis based on the (estimates of) the channel realizations on each slot. Note that for any given (ω (1) , ω (2) , . . . , ω (M) ) (which specifies a choice of users and their formats), we have an M user narrowband MIMO Gaussian interference channel (GIFC) wherein all transmission ranks along with the corresponding maximum transmit powers have been specified. Consequently, we can employ any one of several known algorithms for designing precoding matrices, such as the ones: based on interference alignment, maximizing the signal-to-leakage-noise ratio etc. The per-slot system rate can be computed once the precoding matrices have been designed. The second case is the one where each format specifies constellation(s) and a precoding matrix. In this case an interesting decoupling property holds. From the received signal model in (2) we can deduce that once the precoding matrices used by all BSs on a slot are specified, the rate obtained by scheduling a user in any cell on that slot is invariant to the choice of the other-cell co-slot users. Thus, given a choice of M formats (one for each cell) ƒ (1) , . . . , ƒ (M) and users u (1) , . . . , u (M) , the system rate on each slot is a sum of M per-cell rates, i.e., letting ω (q) =(u (q) , ƒ (q) ), we have that r ⁡ ( ( ω ( 1 ) , ω ( 2 ) , ⋯ , ω ( M ) ) , n ) = ∑ q = 1 M ⁢ ⁢ r ~ ⁡ ( u ( q ) , f ( 1 ) , ⋯ , f ( M ) , n ) ( 3 ) Let (ω (q) ,n) denote an indicator function which is equal to one when ω (q) is selected by BS q for slot n and zero otherwise. Define Ω (q) ={ω (q) :ω (q) =( u,ƒ ), uε q , ƒε u } so that Ω=Ω (1) ×Ω (2) . . . ×Ω (M) . Then, we can formulate our optimization problem as in (4). max { X ⁡ ( ω ( q ) , n ) ⁢ : ω ( q ) ∈ Ω ( q ) , 1 ≦ q ≦ M , n ∈ N } ⁢ ∑ ( ω ( 1 ) , ω ( 2 ) , ⋯ , ω ( M ) ) ∈ Ω ⁢ ⁢ ∑ n ∈ N ⁢ ⁢ r ⁡ ( ( ω ( 1 ) , ω ( 2 ) , ⋯ , ω ( M ) ) , n ) ⁢ ∏ q = 1 M ⁢ ⁢ X ⁡ ( ω ( q ) , n ) ⁢ ⁢ s . t . ⁢ ∑ ω ( q ) ∈ Ω ( q ) ⁢ ⁢ X ⁡ ( ω ( q ) , n ) = 1 , ∀ n , q ; X ⁡ ( ω ( q ) , n ) ∈ { 0 , 1 } , ∀ ω ( q ) ∈ Ω ( q ) , n , q ; ( ∑ n = 1 N ⁢ ⁢ X ⁡ ( ω 1 ( q ) , n ) ) ⁢ ( ∑ n = 1 N ⁢ ⁢ X ⁡ ( ω 2 ( q ) , n ) ) = 0 , ∀ ω 1 ( q ) , ω 2 ( q ) ∈ Ω ( q ) , ∀ q ⁢ : ⁢ ω 1 ( q ) = ( u , f 1 ) , ω 2 ( q ) = ( u , f 2 ) , f 1 ≠ f 2 ; ( 4 ) Note that in (4) the first constraint ensures that each BS selects one (user, format) pair for each slot, recall that a BS can remain silent on a slot by selecting the dummy-user and its format for that slot. The second constraint ensures that each scheduled user is assigned only one format. Our first result is that (4) is unlikely to be optimally solved by a low (polynomial) complexity algorithm. It follows upon reducing (4) to two special cases and exploiting their known hardness. The first case considered in is power control over a single slot system (N=1) with one user per-cell (K=1), which is shown to be strongly NP-hard. The other one shown to be NP-hard in is the single-cell (M=1) resource allocation problem in which each scheduled user can be assigned one of two formats across all its assigned slots. In order to obtain a good heuristic we now discuss Algorithm I which is a randomized algorithm. In each iteration of Algorithm I, each BS assumes that the per-slot (user, format) allocations made by all other BSs remain fixed at their respective values at the end of the previous iteration. The process then tries to optimize the system rate by selecting a (user, format) pair for each slot using a pre-determined sub-routine, under the constraint that each scheduled user is served using only one format. All BSs perform such optimization in parallel and depending on the outcome of its optimization each BS adopts a new allocation for itself with a probability. We offer the following result on the randomized algorithm. For any arbitrarily fixed choice p q ε(0,1), ∀q, the randomized algorithm converges with probability one. The solution obtained upon convergence is such that no base-station can improve the system utility by invoking its sub-routine after assuming the allocations of other base-stations to be fixed. A state denotes a particular feasible choice of (ω (1) , ω (2) , . . . ω (M) )εΩ for each slot, where feasibility is satisfied if each scheduled user is assigned only one of its formats on all its allocated slots. Clearly there are a finite number of such states and each state maps to one system rate. Also, given the per-slot (user, format) pair allocations made by all other BSs, each BS determines a preferred tentative state using a pre-defined sub-routine and updates its (user, format) pair allocations with a time-invariant probability, if the preferred tentative state yields a strictly higher system rate. Thus, the sequence of states across iterations of the randomized algorithm forms a time-homogenous Markov chain. Then, let a terminating state denote a state for which none of the M preferred tentative states (one determined by each BS) offers a higher system rate and note that such a state is absorbing (i.e., the probability of leaving this state is zero). The fact that the optimal system rate is bounded above together with the finite number of states is enough to conclude that such terminating states exist. Also, since all {p q } q=1 M lie in the open interval (0,1), there is a strictly positive probability of reaching a terminating state starting from any initial state. Almost sure convergence of the time-homogenous Markov chain to a terminating state follows from this fact. To obtain a practical randomized algorithm we must specify a low-complexity subroutine. Towards this end, for each BS q we define (q) to be a family of subsets of Ω (q) such that the null set and all singleton subsets (i.e., of cardinality one) of Ω (q) are elements of (q) . In addition, any subset (q) ⊂ Ω (q) is an element of (q) if and only if any two distinct elements ω 1 (q) ,ω 2 (q) ε (q) , where ω 1 (q) =(u 1 , ƒ 1 ),ω 2 (q) =(u 2 , ƒ 2 ), satisfy u 1 ≠u 2 . (q) is an independence family and (q) =(Ω (q) , (q) ) is a matroid. Next, given the allocations of made by all other BSs at the end of the previous iteration, {{tilde over (χ)}(ω (m) ,n):ω (m) εΩ (m) , m≠q, nε }, we define a set function ƒ q :Ω (q) →IR + as f q ⁡ ( A ( q ) ) = ∑ n ∈ N ⁢ ⁢ max ω ( q ) ∈ A ( q ) ⁢ { ∑ ω ( m ) ∈ Ω ( m ) , m ≠ q ⁢ ⁢ r ⁡ ( ( ω ( 1 ) , ω ( 2 ) , ⋯ , ω ( M ) ) , n ) ⁢ ( ∏ m = 1 , m ≠ q M ⁢ ⁢ X ~ ⁡ ( ω ( m ) , n ) ) } , ∀ A ( q ) ⊆ Ω ( q ) . ( 5 ) A simple greedy sub-routine (referred to as the single-cell greedy sub-routine) is proposed next in Algorithm II. We offer the following result on this choice of the sub-routine. For any fixed choice of {{tilde over (χ)}(ω (m) ,n):ω (m) εΩ (m) , m≠q, nε }, the optimization problem in (17) is NP hard. The single-cell greedy sub-routine yields a constant ½-approximation to (17). It can be shown that for any given {{tilde over (χ)}(ω (m) ,n):ω (m) εΩ (m) , m≠q, nε }, the optimization problem in (17) is equivalent to max A ( q ) ∈ I _ ( q ) ⁢ f q ⁡ ( A ( q ) ) . ( 6 ) In addition it can be shown that ƒ q (.) in (5) is a monotonic sub-modular set function. Invoking Lemma 1 we see that the problem in (6) is a monotonic submodular function maximization problem subject to a matroid constraint. Nemhauser et. al. have shown that a greedy algorithm yields a ½ approximation for any such problem. The proposed sub-routine is the greedy algorithm adapted to the problem at hand. Next, we consider scheduling in the scenario where all users can exploit inter-cell interference cancellation. In order to enable inter-cell interference cancellation in practical systems, the scheduler should satisfy the additional constraint that on all its assigned slots, each user is scheduled with the same set of other-cell users. This constraint allows each scheduled user to be informed about the modulations and coding rates assigned to its co-slot other cell users with a reasonable signaling overhead. Thus, while inter-cell interference cancellation can enable a higher system rate, the accompanying scheduling restriction can degrade these gains. We emphasize that any scheduling decision that satisfies the aforementioned constraint is also conducive to interference alignment. This is due to the fact that the scheduled users can now be divided into multiple groups, where each group represents a choice of users (one for each cell). Notice further that the set of slots can also be partitioned across these groups. Consequently, since each user in a group is also assigned one rank, we have a wideband GIFC model for each group, wherein the rank for each user is specified. Thus, we can design wideband precoders that can achieve much better alignment and higher degrees of freedom compared to per slot (constant channel) precoder designs. The optimization problem can now be formulated as in (7). max { X ⁡ ( ω ( q ) , n ) ω ( q ) ∈ Ω ( q ) , 1 ≦ q ≦ M , n ∈ N } ⁢ ∑ ( ω ( 1 ) , ω ( 2 ) , ⋯ , ω ( M ) ) ∈ Ω ⁢ ⁢ ∑ n ∈ N ⁢ ⁢ r ⁡ ( ( ω ( 1 ) , ω ( 2 ) , ⋯ , ω ( M ) ) , n ) ⁢ ∏ q = 1 M ⁢ ⁢ X ⁡ ( ω ( q ) , n ) s . t . ⁢ ∑ ω ( q ) ∈ Ω ( q ) ⁢ ⁢ X ⁡ ( ω ( q ) , n ) = 1 , ∀ n , q ; X ⁡ ( ω ( q ) , n ) ∈ { 0 , 1 } , ∀ ω ( q ) ∈ Ω ( q ) , n , q ; ( ∑ n = 1 N ⁢ ⁢ ∏ q = 1 M ⁢ ⁢ X ⁡ ( ω 1 ( q ) , n ) ) ⁢ ( ∑ n = 1 N ⁢ ⁢ ∏ q = 1 M ⁢ ⁢ X ⁡ ( ω 2 ( q ) , n ) ) = 0 , ∀ ( ω 1 ( 1 ) , ω 1 ( 2 ) , ⋯ , ω 1 ( M ) ) ≠ ( ω 2 ( 1 ) , ω 2 ( 2 ) , ⋯ , ω 2 ( M ) ) ∈ Ω ⁢ ⁢ if ⁢ ⁢ ∃ ⁢ q ⁢ ⁢ s . t . ⁢ ω 1 ( q ) = ( u , f 1 ) , ω 2 ( q ) = ( u , f 2 ) & ⁢ ⁢ u ≠ v q ; Note that the rate function r((ω (1) , ω (2) , . . . , ω (M) ), n) now yields the per-slot system rate under interference cancellation. We now proceed to re-formulate (7). To do so, we define a set ε(u) for each user u in the system. Recall that each user index is unique. In particular, for each user uε q , we define a set ε(u) ⊂ Ω as ε( u )={(ω (1) ,ω (2) , . . . ,ω (M) )εΩ:ω (q) =( u,ƒ ), ƒε u } so that Ω=∪ uεB q ε(u), ∀q. Then, we define a family of sets (q) ε (q) ⊂ Ω: ∩ε( u )|≦1, ∀ uε , u≠θ q   (8) (q) is an independence family and (Ω, (q) ) is a partition matroid. The set ∩ q=1 M (q) is a p-system with p=M. Defining a set function ƒ:Ω→IR + such that for ∀ ⊂ Ω f ⁡ ( A ) = ∑ n ∈ N ⁢ ⁢ max ( ω ( 1 ) , ω ( 2 ) , ⋯ , ω ( M ) ) ∈ A ⁢ r ⁡ ( ( ω ( 1 ) , ω ( 2 ) , ⋯ , ω ( M ) ) , n ) , ( 9 ) we can re-formulate the optimization problem in (7) as max A ∈ ⋂ q = 1 M ⁢ P _ ( q ) ⁢ f ⁡ ( A ) . ( 10 ) With this re-formulation in hand, we propose the multi-cell greedy algorithm in Algorithm III to sub-optimally solve (10). This algorithm has the following property: For any fixed K≧1 and N≧1, the optimization problem in (7) is strongly NP hard. For any fixed M≧1, the optimization problem in (7) is NP hard. The multi-cell greedy algorithm yields a constant 1 M + 1 -approximation to (7). An additional scheduling flexibility can also be incorporated at the expense of more complexity, by modifying the rate-function and using it in the multi-cell greedy algorithm. In particular, we can consider a more relaxed scheduling restriction that on all its assigned slots, each user is scheduled with the same set of other-cell users or any subset of those other-cell users. To accommodate this relaxed constraint, for any choice of (ω (1) , . . . , ω (M) ) on a slot n, the rate function r((ω (1) , . . . , ω (M) ),n) can be computed as the maximum per-slot system rate that can be obtained by allowing any subset ⊂ {1, . . . , M} of the BSs to transmit to their respective chosen users using the selected formats while the remaining BSs are silent. Clearly, computing such a rate-function incurs more complexity. However, with such a rate function there is no need to include a dummy user θ q in q in any cell q. We next consider an important special case which arises when a scheduled user can only be served using a precoding matrix drawn from a finite set. We assume that the per-slot system rate satisfies (3). We will show that in this case the sub-problem in (20) permits another reformulation. Towards this end, we define a super-set of formats as =∪ q=1 M q u and note that if a user u (q) ε q cannot employ a particular format ƒ (q) ε , we can always set {tilde over (r)}(u (q) , ƒ (1) , . . . , ƒ (q) , . . . , ƒ (M) ,n) to be a large negative number for all n, so that the incompatible (user, format) pair will never be selected. Then, observe that (20) now simplifies to max ( ω ( 1 ) , ⋯ , ω ( M ) ) ∈ u ⁢ : ⁢ S ⋃ ( ω ( 1 ) , ⋯ , ω ( M ) ) ∈ ⋂ q = 1 M ⁢ P _ ( q ) ⁢ ∑ n ⁢ ⁢ max ⁢ { v n , ∑ q = 1 M ⁢ ⁢ r ~ ⁡ ( u ( q ) , f ( 1 ) , ⋯ , f ( M ) , n ) } , ( 11 ) where v n = max ( ω ( 1 ) , ω ( 2 ) , ⋯ , ω ( M ) ) ∈ S ⁢ r ⁡ ( ( ω ( 1 ) , ω ( 2 ) , ⋯ , ω ( M ) ) , n ) = max ( ω ( 1 ) , ω ( 2 ) , ⋯ , ω ( M ) ) ∈ S ⁢ ∑ q = 1 M ⁢ ⁢ r ~ ⁡ ( u ( q ) , f ( 1 ) , ⋯ , f ( M ) , n ) . Now suppose that we are given any set ε∩ q=1 M (q) that is not maximal, i.e., { ( ω ( 1 ) , ⋯ , ω ( M ) ) ∈ Ω ⁢ \ ⁢ S ⁢ : ⁢ S ⋃ ( ω ( 1 ) , ⋯ , ω ( M ) ) ∈ ⋂ q = 1 M ⁢ P _ ( q ) } ≠ ϕ , ong with corresponding coefficients {ν n } nε . We extract the sets (q) for q=1, . . . , M from such that (q) consists of the non-dummy users that have been selected in for cell q. Furthermore, we define a set function h : →IR + as h S ⁡ ( T ) = ∑ n ∈ T ⁢ ⁢ u n + max f ( 1 ) , ⋯ , f ( M ) ∈ F ⁢ ∑ q = 1 M ⁢ ⁢ max u ( q ) ∈ B q ⁢ \ ⁢ u ( q ) ⁢ ∑ n ∈ N ⁢ \ ⁢ T ⁢ ⁢ r ~ ⁡ ( u ( q ) , f ( 1 ) , ⋯ , f ( M ) , n ) , ∀ T ⊆ N . ( 12 ) For any given set ε∩ q=1 M (q) that is not maximal in (q) , the maximization problem in (20) can be re-formulated as the following un-constrained maximization problem: max T ⊆ N ⁢ h S ⁡ ( T ) . ( 13 ) The set function h (.) is not monotonic and unfortunately need not be submodular. In this context we note that an efficient local search method for un-constrained maximization of a non-monotonic albeit submodular function is available which offers a constant approximation. Thus, the step (20) in the multi-cell greedy algorithm can be solved using the lower complexity alternative from the two equivalent formulations in (11) and (13), which in turn depends on the system parameters such as K, M & N. Next, we consider an interference limited environment over which interference avoidance is a useful approach. In particular, on each slot only one BS is allowed to transmit. To formulate the resulting resource allocation problem, we define a superset of (user, format) pairs {tilde over (Ω)}=∪ q=1 M Ω (q) . Then let r su (ω (q) ,n) denote the rate obtained on slot n when only the (user, format) pair in ω (q) is scheduled and all BSs other than q remain silent. The corresponding optimization problem can now be formulated as max { X ⁡ ( ω ( q ) , n ) ⁢ X ⁡ ( ω ( q ) , n ) ∈ { 0 , 1 } ω ( q ) ∈ Ω ( q ) , 1 ≦ n ≦ M , n ∈ N } ⁢ ∑ n ∈ N ⁢ ⁢ max 1 ≦ q ≦ M ⁢ { ∑ ω ( q ) ∈ Ω ( q ) ⁢ ⁢ r su ⁡ ( ω ( q ) , n ) ⁢ X ⁡ ( ω ( q ) , n ) } ⁢ ⁢ s . t . ⁢ ∑ ω ( q ) ∈ Ω ( q ) ⁢ ⁢ X ⁡ ( ω ( q ) , n ) = 1 , ∀ n , q ; ⁢ ⁢ ( ∑ n = 1 N ⁢ ⁢ X ⁡ ( ω 1 ( q ) , n ) ) ⁢ ( ∑ n = 1 N ⁢ ⁢ X ⁡ ( ω 2 ( q ) , n ) ) = 0 , ∀ ω 1 ( q ) , ω 2 ( q ) ∈ Ω ( q ) ⁢ : ⁢ ω 1 ( q ) = ( u 1 , f 1 ) , ω 2 ( q ) = ( u 2 , f 2 ) & ⁢ ⁢ u 1 ≠ u 2 , ∀ q ; ( 14 ) We next define another family of subsets of {tilde over (Ω)} as ={∪ q=1 M q : q ε (q) , ∀q}. A key property is the fact that the union of matroids is also a matroid. Next, consider the set function {tilde over (ƒ)}:{tilde over (Ω)}→IR + defined as f ~ ⁡ ( A ) = ∑ n ∈ N ⁢ ⁢ max ω ( q ) ∈ A ⁢ { r su ⁡ ( ω ( q ) , n ) } , ∀ A ⊆ Ω ~ . ( 15 ) Then, the resource allocation problem in (14) can be equivalently formulated as max A ∈ I _ ~ ⁢ { f ~ ⁡ ( A ) } ( 16 ) In Algorithm IV, we propose a simple greedy method for scheduling under interference avoidance and offer the following result. The optimization problem in (16) is NP hard. Algorithm IV yields a constant ½-approximation to (16). In addition, it also yields a constant 1 2 ⁢ M -approximation to (4) as well as (7). The optimization problem in (16) is that of maximizing a monotonic sub-modular set function subject to a matroid constraint. Thus, a simple greedy algorithm (adapted as Algorithm IV) yields a ½ approximation. Also, since r((ω (1) , ω (2) , . . . , ω (M) ),n)≦M max q=1, . . . , M {r su (ω (q) ,n)}, we can show that the solution yielded by the greedy algorithm offers a system utility that is no less than 1 2 ⁢ M of the optimal value obtained by solving (4). Further, the remaining part is also true since the solution yielded by Algorithm IV is also feasible for (7). max { x ⁡ ( ω ( q ) , n ) ⁢ ω ( q ) ∈ Ω ( q ) , n ∈ N } ⁢ ∑ ( ω ( q ) , ω ( 1 ) , ⋯ , ω ( M ) ) ∈ Ω ⁢ ⁢ ∑ n ∈ N ⁢ ⁢ ⁢ r ⁡ ( ( ω ( 1 ) , ω ( 2 ) , ⋯ , ω ( M ) ) , n ) ⁢ ( ∏ m = 1 , m ≠ q M ⁢ ⁢ X ¨ ⁡ ( ω ( m ) , n ) ) ⁢ X ⁡ ( ω ( q ) , n ) ⁢ ⁢ s . t . ⁢ ( ∑ n = 1 N ⁢ ⁢ X ⁡ ( ω 1 ( q ) , n ) ) ⁢ ( ∑ n = 1 N ⁢ ⁢ X ⁡ ( ω 2 ( q ) , n ) ) = 0 , ∀ ω 1 ( q ) , ω 2 ( q ) ∈ Ω ( q ) ⁢ : ⁢ ω 1 ( q ) = ( u , f 1 ) , ω 2 ( q ) = ( u , f 2 ) , f 1 ≠ f 2 ; ∑ ω ( q ) ∈ Ω ( q ) ⁢ ⁢ X ⁡ ( ω ( q ) , n ) = 1 , ∀ n ; X ⁡ ( ω ( q ) , n ) ∈ { 0 , 1 } , ∀ ω ( q ) ∈ Ω ( q ) , n ; ( 17 ) [Algorithm I: Randomized Algorithm] 1. Initialize with any feasible assignment {(ω (q) ,n)}, ω (q) εΩ (q) , 1≦q≦M, mεN} and let {tilde over (R)} denote the corresponding system rate. 2. REPEAT 3. At each BS q, assuming {{tilde over (χ)}(ω (m) ,n):ω (m) εΩ (m) , m≠q, nε } to be fixed, (sub-optimally) solve the optimization problem in (17) using a pre-determined sub-routine and let {{tilde over (χ)}(ω (q) ,n)}, {circumflex over (R)} q denote the obtained solution and the corresponding objective function value. 4. If {circumflex over (R)} q >{tilde over (R)} then with probability p q update all {{tilde over (χ)}(ω (q) ,n)),ω (q) εΩ (q) , nε } to {{circumflex over (χ)}(ω (q) ,n)), ω (q) εΩ (q) , nεN} and inform other base stations m≠q about the update. 5. Collect updates from other base stations if any. 6. UNTIL {circumflex over (R)} q ={tilde over (R)}, ∀q 7. OUTPUT {(ω (q) ,n)},ω (q) εΩ (q) , 1≦q≦M, nεN}. [Algorithm II: Single-Cell Greedy Sub-Routine] 1. Initialize G (q) =Ω (q) ,S (q) =φ 2. REPEAT 3. Solve max ω ( q ) ∈ G ( q ) ⁢ : ⁢ S ( q ) ⋃ ω ( q ) ∈ T _ ( q ) ⁢ f q ⁡ ( S ( q ) ⋃ ω ( q ) ) ⁢ ( 18 ) and let {circumflex over (ω)} (q) ,{circumflex over (ν)} (q) denote the optimal solution and the optimal objective function value. 4. If {circumflex over (ν)} (q) >ƒ q ( (q) ) then update s (q) →s (q) ω (q) , g (q) →g (q) \ω (q)   (19) 5. UNTIL {ω (q) εg (q) : (q) ∪ω (q) ε (q) }=φ or δ (q) =ƒ q ( (q) ) 6. For each nεN determine {circumflex over (ω)} (q) as arg ⁢ ⁢ max ω ( q ) ∈ G ( q ) ⁢ ∑ ω ( q ) ∈ Ω ( q ) ω , n ⁢ ⁢ r ⁡ ( ( ω ( 1 ) , ω ( 2 ) , ⋯ , ω ( M ) ) , n ) ⁢ ( ∏ m = 1 , m ≠ q M ⁢ ⁢ X ^ ⁡ ( ω ( m ) , n ) ) and set χ({circumflex over (ω)} (q) ,n)=1 and χ(ω (q) ,n)=0, ∀ω (q) ≠{circumflex over (ω)} (q) . [Algorithm III: Multi-Cell Greedy Algorithm] 1. Initialize. g=Ω,δ=φ 2. REPEAT 3. Solve max ω ( 1 ) , ⋯ , ω ( M ) ⁢ n ∈ N x ⋃ ( ω ( 1 ) , ⋯ , ω ( M ) ) ⁢ n ∈ N q - 1 M ⁢ X _ ( q ) ⁢ f ⁡ ( S ⋃ ( ω ( 1 ) , ⋯ , ω ( M ) ) ) ( 20 ) and let ({circumflex over (ω)} (1) , . . . , {circumflex over (ω)} (M) ), {circumflex over (ν)} denote the optimal solution and the optimal objective function value. 4. If {circumflex over (ν)}>ƒ(S) then update S→S ∪({circumflex over (ω)} (1) , . . . ,{circumflex over (ω)} (M) ), g→g \({circumflex over (ω)} (1) , . . . ,{circumflex over (ω)} (M) ), 5. UNTIL {(ω (1) , . . . , ω (M) )εg:s∪(ω (1) , . . . , ω (M) )ε∩ q=1 M (q) }=φ or {circumflex over (ν)}=ƒ(S) 6. OUTPUT [Algorithm IV: Greedy Algorithm for Interference Avoidance] 1. Initialize g=Ω,s=φ 2. REPEAT 3. Solve max ω ( q ) ∈ G , S ⋃ ω ( q ) ∈ X _ ⁢ f ~ ⁡ ( S ⋃ ω ( q ) ) ( 21 ) and let {circumflex over (ω)} ({circumflex over (q)}) , {circumflex over (ν)} denote the optimal solution and the optimal objective function value. 4. If {circumflex over (ν)}>{tilde over (ƒ)}(S) then update s→s∪ω (q) , g→g\ω (q) ,  (22) 5. UNTIL (ω (q) εg:s∪ω (q) ε =φ or {circumflex over (ν)}=ƒ(S) 6. OUTPUT Various modifications and alterations of the invention will become apparent to those skilled in the art without departing from the spirit and scope of the invention, which is defined by the accompanying claims. It should be noted that steps recited in any method claims below do not necessarily need to be performed in the order that they are recited. Those of ordinary skill in the art will recognize variations in performing the steps from the order in which they are recited. In addition, the lack of mention or discussion of a feature, step, or component provides the basis for claims where the absent feature or component is excluded by way of a proviso or similar claim language. While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not of limitation. Likewise, the various diagrams may depict an example architectural or other configuration for the invention, which is done to aid in understanding the features and functionality that may be included in the invention. The invention is not restricted to the illustrated example architectures or configurations, but the desired features may be implemented using a variety of alternative architectures and configurations. Indeed, it will be apparent to one of skill in the art how alternative functional, logical or physical partitioning and configurations may be implemented to implement the desired features of the present invention. Also, a multitude of different constituent module names other than those depicted herein may be applied to the various partitions. Additionally, with regard to flow diagrams, operational descriptions and method claims, the order in which the steps are presented herein shall not mandate that various embodiments be implemented to perform the recited functionality in the same order unless the context dictates otherwise. Terms and phrases used in this document, and variations thereof, unless otherwise expressly stated, should be construed as open ended as opposed to limiting. As examples of the foregoing: the term “including” should be read as meaning “including, without limitation” or the like; the term “example” is used to provide exemplary instances of the item in discussion, not an exhaustive or limiting list thereof; the terms “a” or “an” should be read as meaning “at least one,” “one or more” or the like; and adjectives such as “conventional,” “traditional,” “normal,” “standard,” “known” and terms of similar meaning should not be construed as limiting the item described to a given time period or to an item available as of a given time, but instead should be read to encompass conventional, traditional, normal, or standard technologies that may be available or known now or at any time in the future. Likewise, where this document refers to technologies that would be apparent or known to one of ordinary skill in the art, such technologies encompass those apparent or known to the skilled artisan now or at any time in the future. A group of items linked with the conjunction “and” should not be read as requiring that each and every one of those items be present in the grouping, but rather should be read as “and/or” unless expressly stated otherwise. Similarly, a group of items linked with the conjunction “or” should not be read as requiring mutual exclusivity among that group, but rather should also be read as “and/or” unless expressly stated otherwise. Furthermore, although items, elements or components of the invention may be described or claimed in the singular, the plural is contemplated to be within the scope thereof unless limitation to the singular is explicitly stated. The presence of broadening words and phrases such as “one or more,” “at least,” “but not limited to” or other like phrases in some instances shall not be read to mean that the narrower case is intended or required in instances where such broadening phrases may be absent. The use of the term “module” does not imply that the components or functionality described or claimed as part of the module are all configured in a common package. Indeed, any or all of the various components of a module, whether control logic or other components, may be combined in a single package or separately maintained and may further be distributed across multiple locations. Additionally, the various embodiments set forth herein are described in terms of exemplary block diagrams, flow charts and other illustrations. As will become apparent to one of ordinary skill in the art after reading this document, the illustrated embodiments and their various alternatives may be implemented without confinement to the illustrated examples. For example, block diagrams and their accompanying description should not be construed as mandating a particular architecture or configuration. The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Although the invention is described above in terms of various exemplary embodiments and implementations, it should be understood that the various features, aspects and functionality described in one or more of the individual embodiments are not limited in their applicability to the particular embodiment with which they are described, but instead may be applied, alone or in various combinations, to one or more of the other embodiments of the invention, whether or not such embodiments are described and whether or not such features are presented as being a part of a described embodiment. Thus the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

A method to allocate resources in a wireless MIMO system, by enforcing per-cell orthogonality to avoid intra-cell interference; and allocating resources based on interference handling.

This is a continuation of application Ser. No. 08/385,197 filed Feb. 7, 1995, now abandoned, which is a continuation of application Ser. No. 07/809,957 filed Dec. 18, 1991, now abandoned. BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to the field of computer memories, and more particularly, to an improved method and apparatus for refreshing dynamic random access memories (DRAMs) utilized in a data processing system. 2. Art Background Data processing systems typically utilize dynamic memories to store and retrieve data. Dynamic memories advantageously provide substantial memory capacity and low power consumption. Dynamic memories, however, must be periodically refreshed in order to preserve the data stored in the memory cells of the dynamic memory. Periodic refreshment is required because a dynamic memory cell typically consists of a single transistor and a capacitor, and the state of the memory cell is determined by the state of the charge on the capacitor, a charge which eventually degrades or leaks off the capacitor. A dynamic random access memory ("DRAM") defines as part of its specification a refresh period indicating how frequently the DRAM must be refreshed. Such refresh periods typically range between 2 mS and 32 mS. This period of time corresponds, with some worst-case approximation, to the maximum amount of time allowed between refresh operations. A data processing system utilizing a DRAM typically employs circuitry and logic external to the DRAM to insure that these refresh operations are conducted in a timely fashion. One disadvantage of these mandatory refresh operations is that they consume valuable system time, as other operations with respect to the DRAM are necessarily stalled until the refresh operation is completed. For example, if the mandatory refresh operation takes eight clock cycles to complete, all other memory operations with respect to the DRAM are effectively stalled for these eight dock cycles. These eight clock cycles, which might potentially be used for other memory operations, are essentially lost to the mandatory refresh operation. As will be described, the present invention provides for a data processing system with an optional refresh capability in addition to a mandatory refresh capability. With both an optional refresh capability and a mandatory refresh capability, the present invention provides for the selective use of optional refreshes to minimize the system time lost to refresh operations. SUMMARY OF THE INVENTION The present invention operates within a data processing system which utilizes dynamic random access memories ("DRAMs") requiring periodic refreshment. The data processing system includes a processor coupled to a system bus. A memory controller for controlling memory operations is coupled to the system bus and to a memory bus in communication with the DRAMs. The memory controller includes a memory operation command queue for sequentially receiving memory operation commands placed on the system bus, and a refresh module for initiating refresh operations. The refresh module includes circuitry for initiating either a mandatory refresh operation or an optional refresh operation. This circuitry includes a mandatory refresh counter, a refresh flip-flop, a coupling to the memory operation command queue, and refresh logic. In the present invention, the mandatory refresh counter is initially loaded with a predetermined first value. This predetermined first value is chosen such that the period of time it takes to decrement the mandatory refresh counter down to zero corresponds to the refresh period for the DRAMs. Thus, as a general rule, the mandatory refresh counter counts down from an initial value to zero to determine when the next mandatory refresh operation should be be initiated. However, while this count is in progress, if the memory operation command queue is empty, an optional refresh operation is initiated to take advantage of this condition. The use of an optional refresh operation avoids the need to conduct the next mandatory refresh operation. Thus, when the mandatory refresh counter reaches zero, and an optional refresh operation has been conducted during the count from the predetermined first value to zero, the ordinarily conducted mandatory refresh operation is cancelled. Instead, the mandatory refresh counter is simply loaded again with the first predetermined value, and the process of decrementing the mandatory refresh counter is repeated. If, on the other hand, the mandatory refresh counter reaches zero, and an optional refresh operation has not been conducted during the count from the predetermined first value to zero, a mandatory refresh operation is initiated. Thereafter, the mandatory refresh counter is loaded again with the first predetermined value, and the process of decrementing the mandatory refresh counter is repeated. BRIEF DESCRIPTION OF THE DRAWINGS Further details are explained below with the help of the examples illustrated in the attached drawings in which: FIG. 1 is a functional block diagram of one possible data processing system employing the teachings of the present invention. FIG. 2 is a functional block diagram of the modules and queues in the memory controller relevant to the refresh capability of the present invention. FIG. 3 is a flow chart illustrating the method of the present invention. DETAILED DESCRIPTION OF THE INVENTION As will be described, the present invention finds application in data processing systems employing dynamic random access memory. In particular, the present invention is applicable to the data processing system described in the copending application Ser. No. 07/554,283, now U.S. Pat. No. 5,283,877 filed Jul. 17, 1990, incorporated fully herein, by reference. This application discloses an improved single in-line memory module (SIMM) employing dynamic random access memories (DRAMs) having particular application for use by a digital computer for storing and retrieving data and programs. While the present invention will be described at least partly within the context of this particular data processing system, it will be appreciated by one skilled in the art that the present invention may be used in any data processing system utilizing dynamic memory requiring refreshment. In the following description for purposes of explanation, numerous details are set forth such as specific memory sizes, bandwidths, data paths, etc. in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that these specific details are not required in order to practice the present invention. In other instances, well known electrical structures and circuits are shown in block diagram form in order not to obscure the present invention unnecessarily. FIG. 1 illustrates one possible data processing system in which the teachings of the present invention may be utilized. A processor 10 is coupled to a system bus 12 for communicating with various system components, including input/output devices 14, and a memory controller 16. The processor 10 stores and retrieves data, which may comprise programs and/or alphanumeric and other data, in single in-line memory modules (SIMMs) 20, 21, 22, and 23. Each of these SIMMs 20-23 includes sixteen dynamic random access memories (DRAMs). As illustrated, SIMMs 20 through 23 communicate with the memory controller 16 over a memory bus 24. In addition, a clock 26 provides timed, digital clock signals over memory bus 24 to the SIMMs 20-23. Although FIG. 1 illustrates four single in-line memory modules coupled to memory bus 24, it will be appreciated by one skilled in the art that the present invention may be used in a data processing system with any number of SIMMs. In operation, the processor 10 issues read and write commands over the system bus 12, which in turn, couples the commands to the memory controller 16. In a read operation, data is coupled from the SIMMs to the memory controller 16 over memory bus 24, and the memory controller 16 then couples the data to the system bus 12 to be read. In a write operation, data is coupled to the memory controller 16 over the system bus 12, and the memory controller 16 then couples the data to the SIMMs over the memory bus 24. Various control signals are provided by the memory controller 16 to accomplish storage of data, retrieval of data, and refreshment of the DRAMs within the SIMMs. In particular, the memory controller 16 provides row address strobes (RAS), column address strobes (CAS), and load pulses (LD -- L) for the DRAMs disposed in the SIMMs, as well as other timing signals associated with the storage and retrieval of data in the SIMMs. The memory refresh system of the present invention will now be described. FIG. 2 illustrates a functional block diagram of the modules and queues in the memory controller 16 relevant to this memory refresh system. In general, system bus 12 is coupled to memory controller 16 through system bus control logic 30. In particular, memory operation commands which have been coupled to the system bus 12 are coupled to the memory controller 16 through system bus control logic 30. System bus control logic 30 couples the memory operation commands to a memory operation command queue (CMDQUE) 32. Data which has been coupled to the system bus 12 is similarly coupled through system bus control logic 30 to a data-in queue (DIQUE) 50. This data-in queue 50 is in turn coupled to the memory bus 24. Continuing to refer to FIG. 2, a memory master module 34 embodies a state machine and is coupled to the memory operation command queue 32. The memory operation command queue 32 couples memory operation commands to the memory master module 34 which directs the memory operations corresponding to these commands. The memory master module 34 is also coupled to a memory control module 36 which provides, over memory bus 24, the timing signals, RAS, CAS, and LD -- L to the DRAMS in the SIMMs. (See FIG. 1.) As illustrated in FIG. 2, a memory refresh module 40 is coupled to both the memory master module 34 and the memory control module 36. The memory refresh module 40 determines when a refresh operation should take place, and further provides the control signals needed to initiate a refresh operation. In particular, as will be described, when the memory refresh module determines that a refresh operation should take place, the memory refresh module 40 provides two refresh control signals RFSET and REF. The memory refresh module 40 provides the RFSET signal to memory master module 34 to start a refresh cycle, and provides the REF signal to memory control module 36 to select the timing signals for the refresh operation. In the presently preferred embodiment, the memory refresh module 40 includes a mandatory refresh counter 42, a refresh flip-flop 44, a coupling to the memory operation command queue 32, and refresh logic 46. As illustrated, the mandatory refresh counter 42, the refresh flip flop 44, and the memory operation command queue are coupled to refresh logic 46. With reference to FIGS. 1 and 2, the functioning of the memory refresh module 40 will now be described. The mandatory refresh counter 42 is initially loaded with the refresh period for the DRAMs used within the memory module or modules. This is accomplished by loading the mandatory refresh counter 42 with a first predetermined value such that the period of time it takes to decrement the mandatory refresh counter 42 with each clock cycle from the first predetermined value to a second predetermined value, corresponds to the refresh period for the DRAMs. This first predetermined value can be hard-wired in the system, or in the alternative, loaded from the processor 10. The presently preferred embodiment sets this second predetermined value to zero. However, it will be appreciated that the present invention can utilize a mandatory refresh counter 42 which decrements to any second predetermined value, or alternatively, increments to any second predetermined value. Following the loading of the mandatory refresh counter 42, the refresh flip-flop 44 is set on. The mandatory refresh counter 42 is then decremented with each clock cycle. When the mandatory refresh counter 42 counts down to zero, an MRCZ control signal is issued and provided to the refresh logic 46. If at the time the MRCZ control signal is received by refresh logic 46, the refresh flip-flop 44 is on, the memory refresh logic 46 issues an RFSET control signal to the memory master module 34 to initiate a refresh operation, and an REF control signal to the memory control module 36 to select the timing signals for a refresh operation. The refresh operation is then conducted under the control of the memory master module 34 and the memory control module 36. Other memory operations are necessarily interrupted for the number of clock cycles it takes to complete this mandatory refresh operation. As described, whenever the mandatory refresh counter 42 reaches zero, a determination is made as to whether a mandatory refresh operation must be initiated. It will be appreciated that a mandatory refresh operation will always take place when the mandatory refresh counter 42 reaches zero, unless the refresh flip-flop 44 is off. As will be described, the refresh flip-flop 44 is placed in an off condition whenever an optional refresh operation is conducted. It should be noted, however, that regardless of whether a mandatory refresh operation is in fact initiated, following this determination, the present invention thereafter reloads the mandatory refresh counter 42 with the first predetermined value, which in turn, sets the refresh flip-flop 44 on. Referring again to FIG. 2, it can be seen that refresh logic 46 receives a third input in addition to the input from the mandatory refresh counter 42, and the refresh flip-flop 44. This third input arises from a coupling to the memory operation command queue 32, and indicates the status of the memory operation command queue 32. When the memory operation command queue 32 is empty, a no-operation signal (NO-OP) is coupled to refresh logic 46. When refresh logic 46 is provided with a NO-OP signal, and the refresh flip-flop 44 is in the on condition, the memory refresh logic 46 initiates what is termed an optional refresh operation. As with the mandatory refresh operation, refresh logic 46 issues an RFSET control signal to the memory master module 34 to start a refresh operation, and an REF control signal to the memory control module 36 to select the timing signals for a refresh operation. Following an optional refresh operation, the inhibit flip-flop 44 is reset off. It will be appreciated, therefore, that following an optional refresh operation, because the refresh flip-flop 44 is thereafter in the off condition, any further optional or mandatory refresh operations are inhibited until the refresh flip-flop 44 is set on again. As described earlier, this occurs when mandatory refresh counter 42 counts down to zero, a determination is made as to whether to conduct a mandatory refresh operation, and the mandatory refresh counter is reloaded, thereby causing the refresh flip-flop 44 to be set on again. As a general principle, the present invention utilizes optional refresh operations to effectively substitute for mandatory refresh operations whenever such substitutions result in a net savings of system time expended on refresh operations. It will be appreciated that the present invention takes advantage of what might be termed "idle time" in the data processing memory (GDC) system. The present invention uses this "idle time" to accomplish optional refresh operations. These optional refresh operations, when they occur, obviate the need to conduct the immediately succeeding mandatory refresh operation. As such, the immediately succeeding mandatory refresh operation is effectively cancelled. It will be additionally appreciated that the savings in system time provided by the present invention depends upon a number of factors, including the number of clock cycles generally needed to complete a refresh operation, as well as the sequence, timing, and duration of NO-OP conditions. For example, if it is assumed that a refresh operation consumes 8 clock cycles, a system utilizing only mandatory refresh operations can generally be assumed to regularly interrupt and stall eight clock cycles worth of memory operations while the mandatory refresh operation is taking place. These eight clock cycles are essentially lost to the refresh operation. In the present invention, if the NO-OP condition which triggers the optional refresh operation lasts for one clock cycle, the optional refresh operation interrupts and stalls only seven clock cycles worth of memory operations. Thus, at a minimum, every time an optional refresh operation is conducted, it can be assumed that at least one clock cycle worth of system time is being saved. On the other hand, if as is likely, the NO-OP condition which triggers the optional refresh operation lasts for a greater number of clock cycles, the system time saved is correspondingly higher. For example, if the triggering NO-OP condition lasts for eight clock cycles, the present invention conducts a refresh operation for these eight clock cycles and thereby saves eight clock cycles worth of system time. (A NO-OP condition lasting for more than eight clock cycles would still result in a savings of eight clock cycles, for the refresh operation is assumed, in this example, to last but eight clock cycles.) The method of the present invention is illustrated in further detail in the flow chart shown in FIG. 3. Referring to FIG. 3, the mandatory refresh counter (MRC) is initially loaded with the refresh count. This causes the refresh flip-flop (RFF) to be set on. The mandatory refresh counter is then decremented with each clock cycle. If the count in the mandatory refresh counter is zero, and the refresh flip flop is on, the system executes a refresh operation and returns anew to the first step wherein the mandatory refresh counter is loaded with the refresh count. This particular refresh operation corresponds to a mandatory refresh operation. If, on the other hand, the count in the mandatory refresh counter is zero, and the refresh flip-flop is off, the mandatory refresh operation is bypassed, and the system simply returns anew to the first step. This would correspond to the condition wherein an optional refresh operation had previously taken place. Assuming the count in the mandatory refresh counter is not zero, the system determines whether an optional refresh operation should take place. If the memory operation command queue provides a NO-OP signal and the refresh flip-flop is on, a refresh operation corresponding to an optional refresh is initiated. Following the optional refresh operation, the refresh flip-flop is reset off, and the system returns to the step of decrementing the mandatory refresh counter. If, instead, the memory operation command queue provides a NO-OP signal, and the refresh flip-flop is off the system bypasses the optional refresh operation, and simply returns to the step of decrementing the mandatory refresh counter. This situation would correspond to the condition wherein an optional refresh operation had previously taken place. If an optional refresh had occurred during the time when the mandatory refresh counter was counting down to zero, and if on the next counting down of the mandatory refresh counter to zero no other optional refresh occurs, the refresh flip-off would still be on, the system would execute a mandatory refresh upon the refresh counting down to zero on that next cycle. The time between refreshes might in this worst case exceed the refresh time required by the specifications set forth by the DRAM. However, the effect is only a minor one, since the DRAM specifications are highly conservative in their estimate of refresh time required. Thus the present invention uses this conservative refresh time to its advantage. Also, since the refreshes operate on only a group of DRAM cells during any one refresh operation, the effect on data is minimal. Thus, the advantage of reducing the total time for refreshes far outweighs any risk of data degradation. If the count in the mandatory refresh counter is not zero, and the memory operation command queue does not provide the refresh logic with a NO-OP signal, no refresh operation need take place. Instead, the memory operation command in the memory operation command queue is simply executed without interruption, and the refresh system returns to the step of decrementing the counter. While the present invention has been particularly described with reference to FIGS. 1 through 3 and with emphasis on certain memory system architectures, it should be understood that the figures are for illustration only and should not be taken as limitations upon the invention. In addition, it is clear that the methods and apparatus of the present invention have utility in any application wherein a data processing system utilizes dynamic memories requiring refreshment. It is contemplated that many changes and modifications may be made, by one of ordinary skill in the art, without departing from the spirit and scope of the invention as disclosed above.

A data processing system which utilizes dynamic memory that requires periodic refreshment includes a processor coupled to a memory controller which is in turn coupled to the dynamic memory. The memory controller includes a memory operation command queue for sequentially receiving memory operation commands from the processor and a refresh module for initiating refresh operations. The refresh module includes circuitry for initiating either a mandatory refresh operation or an optional refresh operation. Mandatory refresh operations are initiated at the conclusion of periodic intervals, unless an optional refresh operation has been initiated within the particular interval. An optional refresh operation is initiated within a particular interval if the memory operation command queue is empty. Optional refresh operations thereby serve to substitute for mandatory refresh operations, minimizing the system time lost to refresh operations.

This is a continuation of application Ser. No. 07/680,180 filed Apr. 3, 1991 now U.S. Pat. No. 5,248,924. BACKGROUND OF THE INVENTION The present invention relates generally to a numerically controlled machine tool and to an operator work management system. A numerical control unit is designed to perform numerical control processing in accordance with a cutting program provided by a paper tape, etc. Specifically, a machine tool is driven according to the results of the control processing in order to cut a workpiece. FIG. 10 is a block diagram of a prior art numerical control unit. A cutting program read from a tape reader 11 is stored into a memory 18. When this cutting program is to be executed, it is first read from the memory 18 block by block and then processed in a controller 12 containing a processor, a control program memory, etc. The controller 12 then performs numerical control processing in accordance with the cutting program, thereby driving a servo motor of a machine tool 14 so as to move a table or a tool rest in accordance with a move command, or for controlling the machine tool 14, via an electrical control box 13, to perform, for example, coolant on/off and spindle run/reverse/stop commands. The numeral 15 indicates an operation board including zeroing, Jogging and other command switches, buttons and indicators. The numeral 16 is a manual data input device (hereinafter referred to as the "MDI") for manually entering various types of data into the controller 12, and numeral 17 is a display unit ("DSP") for displaying the current position and other data of the machine. The components 11 to 17 (with the exception of the machine tool 14) constitute a computerized numerical control unit (hereinafter referred to as a "CNC"). The controller 12 in the CNC is a computer which performs predetermined numerical control processing on the basis of a control program and the cutting program to control the machine tool 14. The machine tool 14 controlled by the CNC is referred to as a numerically controlled machine tool (NC machine tool), and most of the present machine tools are NC machine tools. The operator controlling this NC machine tool is usually provided with work directives through cutting programs for cutting workpieces to be finished on that day, and work setup instructions as a preliminary to cutting. The operator carries out the setup work in accordance with the work instruction and causes the CNC to run the predetermined cutting programs to cut workpieces. The operator then writes the work done on that day in a work report or the like. The NC machine tool may generally be operated by any person including unauthorized personnel by simply powering up. To prevent this, some CNCs have a function of disabling NC data from being rewritten unless a key provided therefor is switched on. Further, recent CNCs holding a larger internal memory capacity have a function of allowing the keying history of the operator to be stored in an internal memory for a later check of the operation performed. Further, some CNCs allow CNC-generated error, alarm and other histories to be stored in an internal memory, so that errors and alarms occurring at various times can be checked later. Furthermore, there is a growing tendency for recent CNCs to display messages, etc. for the operator on a display device to allow the operator to "converse" with the CNC and be guided during operation, thereby improving the operability of the CNC. To allow kanji (Chinese characters), kana (Japanese phonetic characters) and other characters to be displayed for this purpose, in addition to the roman alphabet and numerals, the NC contains character fonts which are employed to display kanji, kana and other characters. FIG. 12 is a block diagram illustrating the major parts of a prior art CNC display control section, wherein the numeral 60 indicates a microcomputer; 61 a ROM for storing programs and other data required for the microcomputer 60 to perform predetermined operations, 59 a RAM used for pointers, operation, etc., 62 an address decoder for accessing memories, etc., and 63 a first-An first-out register (FIFO register) to which display data is written from a host microcomputer for NC control (not illustrated) and which is designed to issue an interrupt signal INT to the microcomputer 60 when, for example, data of 16 characters is entered. The numeral 64 indicates a CRT controller for generating horizontal and vertical synchronization signals and scanning addresses, 65 a pulse generator circuit, 66 an address switching circuit for switching between a CPU address and a scanning address, 67 an address decoder, 68 a character RAM (video RAM) for storing characters coded into addresses corresponding to the positions on a display screen, 69 a color RAM (video RAM) for storing colors for painting characters on the display screen, 70 a character ROM for converting character codes output by the character RAM 68 into corresponding display data (alphabetic characters, kanji, kana and symbols), 71 a display control circuit for outputting red, green and blue video signals in accordance with the output of the color RAM 69, 17 a display unit,. and 72 a screen thereof. A character string to be displayed on the screen 72 of the display unit 17 is entered sequentially from the NC controlling microcomputer (not illustrated) to the FIFO register 63. A character in this character string is coded, for example, in sixteen bits. When a character code of sixteen characters is entered into the FIFO register 63, the microcomputer 60 is interrupted to perform interrupt processing. In other words, the character code is read from the FIFO register 63 and written to the separately specified address of the character RAM 68. When color designating information is then entered into the FIFO register 63, that information is read and color information is written to the corresponding area of the color RAM 69. When the information is written to the RAMs 68 and 69, the address switching circuit 66 is switched to the scanning address position of the CRT controller 64 whereby the contents of the character RAM 68 and the color RAM 69 at the scanning addresses are read in synchronization with each other. The output of the character RAM 68 is provided in character code and converted into display character data in the character RAM 70. Namely, if that character code is a kanji code, multiple pieces of dot data matching the shape of that kanji character are outputted. According to that dot data and the color information of the color RAM 69, the display control circuit 71 creates red, green and blue video signals, which are then input to the display unit 17 and displayed as a character on the screen 72. Accordingly, the use of the kanji and kana characters to form a character string sent from the NC controlling host microcomputer allows comments and other guides to be displayed in kanji and other characters which can be most easily understood by the Japanese. Since not many terms are employed in the NC field, the number of kanji characters used is limited. Hence, the character ROM can be composed of a single LSI for characters including kana. Since the known display control device shown in FIG. 12 is configured as described above, the character ROM 70 must be replaced to display characters corresponding to the user's native language and the display language cannot be changed easily. To improve this disadvantage, a display control section wherein the character ROM 70 is replaced by a character RAM and the data of the character RAM is changed through the key switches of the operation panel for use with a numerical control unit is disclosed in Japanese Patent Disclosure Publication No. 189785 (1985). In the NC machine tool known in the art which has only the aforementioned functions, a work instruction containing all work directives for the operator and a cutting program must be passed to the operator in pairs and both must always be managed at the same time. In addition, before starting the cutting operation, the operator needs to check various pieces of data (parameters, tool information, etc.) in the CNC to see if they are appropriate. Since all setup prior to the cutting is left to the operator, defects may occur due to operator errors, e.g. workpieces may be machined with a different parameter value. In addition, because a work report is written by the operator, there may be incorrect or omitted entries, and further the operator may leave things out when inconvenient for himself or herself. Moreover, when it is desired to make the NC machine tool operable only for particular operators, the key of the CNC must be passed to each operator, and further, the absence of this key simply disallows the internal data of the CNC from being changed and the NC machine tool itself can be operated as desired. SUMMARY OF THE INVENTION A primary object of the present invention is to provide a CNC or other computer-controlled system which allows data such as work directives for the operator, cutting programs, parameters and tool information to be stored in a single portable storage medium, enabling the operator to display any necessary work directive on the CNC screen by simply inserting the storage medium into the CNC. All required data are read from the storage medium, set to the CNC, and printed on a printer as needed. Another object of the present invention is to provide a CNC or other computer-controlled system which allows the work report of the operator to be eliminated by storing the work results of the operator in the storage medium. A reliable work record is kept by automatically recording the actual work of the operator in the storage medium. A further object of the present invention is to provide a CNC or other computer-controlled system which provides a record of how long and in what way the NC machine tool has been operated by which operator to be kept in an operation recording memory in the CNC by placing operator identifying information in the storage medium. A further object of the present invention is to provide a CNC which disallows an operator who attempts to operate an NC machine tool from doing so unless the operator loads the storage medium into the CNC and enters a PIN (personal identification number) code which matches that in the storage medium, and which ensures management of the NC machine tool by disallowing the NC machine tool from being operated if conditions such as the code number, availability periods and available time windows stored in the storage medium are not satisfied. A further object of the present invention is to provide a display control section which allows data shown on a display device to be easily changed, including the language used in the display. The CNC according to the present invention includes a read/write device (R/W device) to allow data in the portable storage medium to be transferred, and contains identification codes denoting NC machine tools, and the storage medium includes identification codes designating operators, PIN codes known only to the operators, and further has data including identification codes of the NC machine tools allowed for operation if there are several NC machine tools. The CNC is designed to perform processing after determining whether or not the operator is permitted to operate the CNC. The CNC always checks to see if the storage medium has been inserted in the CNC. Further, the CNC has clock and calendar functions, and the storage medium includes check data including the operable periods and operable time windows in which the operator is permitted to operate. The display control section of the CNC comprises a font RAM for storing font data used for converting a predetermined character code into display data matching a display section and rewriting means for rewriting the font data placed in the font RAM. The rewriting means comprises an external storage medium for storing the font data and identification codes, and font data storing means for referencing the identification codes stored in the external storage medium for placing into the font RAM the font data stored in the external storage medium only when the external storage medium loaded stores the desired font data. The display control section concerned with the present invention comprises a message RAM for storing message data employed for displaying a predetermined message on a display section and rewriting means for rewriting the message data placed in said message RAM. The rewriting means comprises an external storage medium storing the message data and identification codes employed for identifying the types of message data, and message data storing means for referencing the identification codes stored in the external storage medium for placing into the message RAM the message data stored in the external storage medium only when the loaded external storage medium stores the desired message data. The CNC concerned with the present invention allows a dedicated language to be interpreted and batch-processed and work directive data to be described in the batch-processed dedicated language. The CNC allows screen display commands described in the work directive data to be displayed on the CNC screen. The CNC allows the operator to switch between an ordinary CNC display screen and a work directive screen as appropriate. The CNC allows the work directive displayed on the CNC screen to be printed on a printer. The CNC also allows batch processing currently being performed to be stopped and resumed by operator commands. The CNC allows data, such as parameters and tool data, to be named as appropriate. The CNC allows date and time of creation to be assigned to data such as parameters and tool data. The CNC allows a dedicated language for batch processing in a cutting program to be separated from the cutting program and processed in individual processing systems, and allows work records to be stored into the work record data area of the portable storage medium. The CNC also allows the record of operation performed to be stored in an operation recording memory provided in the CNC. When attempting to operate the NC machine tool, the operator first loads the portable storage medium into the R/W device of the CNC and switches on the CNC power supply. The CNC then directs the operator to enter the PIN code. In response to this directive, the operator enters the PIN code. The NC machine tool is enabled for operation only if the PIN code matches a code in the storage medium and other availability conditions are satisfied (whether or not the NC machine tool is available and is in an available period for this operator, for example. If the operator is not permitted to perform specific operation but nevertheless attempts to perform such an operation, the NC machine tool is disabled. Removal of the storage medium from the CNC disables the CNC. The CNC cannot be operated outside the authorized period and time block during when the operator is permitted to operate the CNC. The rewriting means rewrites the font data of the font RAM or the message data of the message RAM in blocks. The rewriting means references the identification codes stored in the external storage medium and rewrites the font data of the font RAM or the message data of the message RAM in blocks only when the external storage medium contains the desired character data or message data. The CNC performs batch processing according to the. work directive data stored in the storage medium, thereby displaying the work directives for the operator on the CNC screen, entering data such as the cutting programs, parameters and tool information, and making the settings for the cutting programs. The operator can work according to the work directives displayed on the CNC screen. The operator can switch between the ordinary CNC screen and the work directive screen as appropriate to view the necessary screen when required, and can output the work directly data displayed on the screen to the printer as required. In addition, the operator can stop and resume the batch processing as needed. The parameters, tool data, etc. can be managed under arbitrary names. The date of creation can be assigned to the parameters, tool data, etc. so that the data can be separated from the date and time of creation. The cutting program and the language dedicated to batch processing can be described on an identical program. Further, the work record of each operator and the operation record of the CNC can be easily kept. BRIEF DESCRIPTION OP THE DRAWINGS FIG. 1 is a block diagram illustrating major parts of an NC unit concerned with the present invention. FIG. 2 is a block diagram showing primary parts of a portable storage medium processing system. FIG. 3 illustrates the locations of data stored in a memory. FIG. 4 shows check data locations. FIG. 5 provides an example of an NC machine tool management form. FIG. 6 is an IC card formatting and creating flowchart. FIG. 7 is an NC processing flowchart. FIG. 8 is an IC card checking flowchart. FIG. 9 gives an example of operation record data. FIG. 10 is a block diagram illustrating main parts of an NC unit known in the art. FIG. 11 is a block diagram showing main parts of a display control section concerned with the present invention. FIG. 12 is a block diagram illustrating main parts of a display control section known in the art. FIG. 13 gives an example of a work directive screen display. FIG. 14 provides an example of a work directive screen display. FIG. 15 shows another example of a work directive screen display. FIG. 16 provides a further example of a work directive screen display. FIG. 17 shows another example of a work directive screen display. FIG. 18 provides an example of work record data. FIG. 19 shows the contents of a font RAM. FIG. 20 illustrates a data map in a font data section. FIG. 21 is a schematic flowchart for language input processing. FIG. 22 illustrates a parameter data section. FIG. 23 is a schematic flowchart for parameter input processing. FIG. 24 is a block diagram showing major data processing parts of the NC unit. FIG. 25 provides an example of the work directive data. FIG. 26 is a block diagram illustrating primary display data processing parts. FIG. 27 is a schematic flowchart for processing performed to disable part of the operation. DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing the CNC according to the present invention. As compared to the block diagram of the known CNC shown in FIG. 10, the major characteristics of the CNC according to the invention are the additions of a R/W section 20 for transferring data to and from the portable storage medium, an external storage medium processor 21 for controlling the data transfer to and from the storage medium and the main functions of the present invention, and a select switch 22 for switching the operation of the operation board 15 and the MDI 16 to be valid or invalid, and an operation recording memory 23. Further, as compared to the block diagram the display control section in the prior art CNC in FIG. 12, the CNC according to the present invention is characterized by the use of RAMs in the font and message sections allowing data to be changed as shown in FIG. 11. FIG. 2 is a block diagram of the portable storage medium processing system. This embodiment will be described employing an IC card as a portable storage medium. Referring now to FIG. 2, the numeral 1 indicates an IC card, and 40 a processor for performing processing such as data transfer to and from the IC card 1. The IC card 1 includes a storage 3 for storing various types of data (described later), an input/output section 4 forming a signal path to and from the processing system 40 or the CNC 10, and a control section 2 comprising, for example, a CPU for controlling the storage section 3 and I/O section 4. Particularly, as shown in FIG. 3, the storage section 3 includes a check data area 31 employed to determine whether the NC machine tool loaded with the IC card 1 is enabled for operation or not, a work directive data area 37 used to give a work directive to the operator, a cutting data area 38 for storing various types of data required for cutting, a work record data area 39 for recording the details of machining faults or errors as well as the details of the work done by the operator, a message data area 77 and a font data area 78 respectively storing messages and fonts in a language used by the operator. Further, as shown in FIG. 4, the check data area 31 includes an identification code area 32 for storing identification code(s) used to identify whether the IC card 1 is the appropriate one for the present system, an operator name area 33, a PIN code area 34, a machine identification code area 35 for storing the identification codes of machines to be authorized, and a time period and time block area 36 for storing the period and time block in which the operator is permitted to use the CNC. In FIG. 2, the processor 40 is employed by a system manager to set various types of data to the IC card 1 and fetch data from the IC card 1 for the management of the operator's work. The processor 40 may comprise dedicated hardware, a general-purpose computer, or a personal computer, etc. As shown in FIG. 2, the main hardware block configuration of the processor 40 is provided with a processor section 41 consisting of, for example, a CPU for controlling the whole operation, a storage 43 for storing various types of information, a display 45 for displaying various types of data for the system manager according to the results of the processing in the processor section 41, a printer 46 for printing various types of information, a reader/writer section (hereinafter referred to as the "R/W section") for forming a signal path to and from the loaded IC card 1 for transferring data, and a keyboard 44 employed by the manager to enter various types of data. The storage 43 contains data required for the IC card 1, e.g. various types of data needed for cutting. The operation of the present invention will now be summarized. FIG. 5 illustrates an example of a management form of an NC machine tool employing a management system of the present invention, wherein a manager 51 instructs an operator 52 and an operator 53 to perform work by operating an NC machine tool 54 and an NC machine tool 55, respectively. Various types of data required (such as cutting programs for machining and parameters and tool information set in the CNC) are assumed to have been created beforehand using a CAM system 50, and stored in the processor 40. It will be recognized that the CAM system 50 and the processor 40 may operate on the same hardware. The manager 51 devises a work schedule to determine the details of the work to be done by the operators 52, 53. The IC cards 1, 1 corresponding to the operators 52, 53 are created employing the processor 40 in accordance with the work details. The manager 51 gives the IC cards 1 to the operators 52, 53 and instructs them which NC machine tools to use. This instruction is extremely simple because detailed subsequent work directives are stored in the work directly data area 36 (FIG. 4) of the IC cards 1. The operators 52, 53 load the IC cards 1 into the corresponding NC machine tools 54, 55 and carry out the day's work in accordance with the work directives stored in the IC cards 1. When the day's work is finished, the operators 52, 53 remove the respective IC cards 1, from the NC machine tools 54, 55 and deliver them to the manager 51. The operators 52, 53 need not make a detailed report to the manager 51 since the records of their work are kept in the work record data area 34 of the IC cards 1. By loading the IC cards 1 presented by the operators 52, 53 into the processor 40 and reading the work record data 38, the manager 51 will be able to obtain detailed work records and devise the next work schedule according to the contents of the work records. Now that the operation example of the management system according to the invention has been summarized, the, operation of its necessary areas will now be described in more detail. The manager 51 stores various types of necessary data into the storage 43 of the processor 40 before initiating cutting. The manager 51 who has devised the work schedule creates the IC cards 1 to be given to the operators 52, 53 by means of the processor 40 in accordance with the work schedule. A processing flowchart for creating a new IC card is shown in FIG. 6. The contents of the IC card 1 are first loaded into the R/W section 42 of the processor 40 (step 101). The IC card 1 is then formatted (step 102). This process clears all areas of the IC card 1 and writes to the IC card 1 an identification code 32 indicating that the IC card 1 is exclusively used for this system. The name of the operator 33 who will receive the IC card 1 is entered (step 103). The PIN code 34 known only to the operator who will receive the IC card 1 is entered (step 104). The identification codes 35 of the NC machine tool(s) which the operator is permitted to use is entered. Respective identification codes 35 are entered when the operator is to use a plurality of NC machine tools (step 105). The period (duration) and time block (e.g., a work shift) when the operator may use the NC machine tool(s) are entered (step 106). Several periods and time blocks may be set and the day of week may also be changed. In the example in the area 36 shown in FIG. 4: 1990. 07. 01; 1990. 07. 31 indicates that the NC machine tool may be used from Jul. 1, 1990 to Jul. 31, 1990, and * 8:00 ; 17:00 indicates the NC machine tool may be used in a time block from 8 o'clock to 5 pm on weekdays. It is assumed that the NC machine tool is not allowed for use on Saturdays and Sundays unless otherwise specified as indicated below: ST 8:00; 12:00 indicates that the NC machine tool may be used from 8 o'clock to 12 o'clock on Saturdays. The other days of the week may be specified individually by Monday (MO), Tuesday (TU), Wednesday (WE), Thursday (TH), Friday (FR) and Sunday (SU). #END designates the end of data. Returning now to FIG. 6, the work directive data to be processed on that day is then entered (step 107). This data gives the operator specific directives on the work to be done on that day and the details thereof will be described later in the section wherein the operator loads the IC card 1 into the NC unit 10 and is given the work directives. All required cutting data is then entered (step 108). Data on the language used by the operator is entered (step 109). Among the steps for creating the new IC card 1 as described above, usually only the steps 107 and 108 need be executed if the operator name 33, the PIN code 34, the available NC machine tool 35, the available period and time 36, and the language used 77, 78 are not to be changed. An IC card 1 created as described above is given to each operator who will do the work. The NC unit 10 according to the present invention is provided with a select switch marked 22 in FIG. 1. This switch makes valid or invalid the instructions of the operator given to the NC unit 10 from the operation board 15 and the MDI 16. When the select switch 22 is OFF, all operator operation is made invalid and the NC unit 10 and the machine tool 14 are disabled. This select switch 22 is switched ON/OFF on a software basis and switched ON when it is Judged that predetermined conditions have been met. Further, the NC unit 10 according to the present invention includes a function of disabling part of the operator's instructions, e.g. a function to disable entered data. This prevents a cutting program or parameters, from being rewritten unless the machine is enabled to accept such instructions. As illustrated in the flowchart in FIG. 27, when an attempt is made to change a parameter, a check is made to see if parameter rewrite is permitted (step 161), and if it is permitted, rewrite processing is performed (step 162). If it is not permitted, error processing is performed (step 163). This processing notifies the operator that parameter rewrite is not permitted, by a screen display, etc. Similarly, when an attempt is made to rewrite a cutting program, a check is made to see if cutting program rewrite is permitted (step 164), and if it is permitted, rewrite processing is performed (step 165). If it is not permitted, error processing is performed (step 163). Whether the rewrite permission has been granted or not is Judged by the PIN code 34 (FIG. 4) known to the operator. "J" at the end of the PIN code indicates that rewrite permission has not been given and "S" indicates that rewrite permission has been granted. The operator must load the predetermined dedicated IC card 1 into the NC unit 10 before initiating operation. The NC unit 10 according to the present invention is not designed to provide for the removal of the IC card 1 by the operator partway through the operation. Namely, the NC unit 10 always checks if the IC card 1 is properly inserted in the NC unit 10, and if it detects the absence of the IC card 1, the NC unit 10 comes to an emergency stop, brings the machine tool 14 to a stop, and switches off the select switch 22, thereby disabling the NC unit 10 and the machine tool 14 from operation unless the IC card 1 is properly loaded into the NC unit 10 again. The procedure for starting machine operation will now be described. Each operator loads the IC card 1 into the R/W section 20 of the corresponding NC machine tool 14 and initiates work. An NC unit processing flowchart beginning with the start of the work by the operator is shown in FIG. 7. The CNC unit 10 and the machine tool 14 are powered up (step 111). The select switch 22 is set to OFF to disable the operation board 15 and the MDI 16 for operation (step 112). This completely disables the NC machine tool 14 for operation until the select switch 22 is set to ON. A check is made to see if the IC card 1 is coupled to or loaded in the R/W section 20 of the CNC 10 (step 113). If the IC card 1 is not loaded, the following message is displayed on the display unit 17 of the CNC: "LOAD THE IC CARD." in order to prompt the operator to insert the IC card 1 (step 114). If the IC card 1 is loaded, a check is made to see whether or not the IC card 1 inserted may be used (step 115). This check is performed as shown in FIG. 8. First a check is made on the identification code 32 among the data stored in the check data area 31 of the IC card 1 to see if the IC card 1 is for this system (step 130). If it is, the operator is prompted to enter the PIN code (step 131). The select switch 22 is set to ON in this case to enable the PIN code to be entered from the MDI 16. When the operator enters the PIN code, the select switch 22 is set to OFF again and a check is made to see if the PIN code entered matches the PIN code 34 in the IC card 1 (step 132). If the PIN codes match, a check is made to see if the machine identification code stored in the CNC exists in the machine identification code area 35 stored in the IC card 1 (step 133). If the IC card 1 is judged as valid, then the available period and time block 36 in the IC card 1 are checked to see if permission to use the NC machine tool 14 is granted at this point on the basis of the calendar and the clock in the CNC (step 135). If in the available time windows, permission is granted (step 136). Permission is not granted if any of the conditions at steps 130, 132, 133, 134 and 135 is not satisfied (step 137). Whether or not permission is granted to the operator is judged via the above procedure. Returning to FIG. 7, if the permission is not obtained, the following message or the like is displayed on the display unit 17 of the CNC (step 116): "UNAUTHORIZED" to disable any operation. If permission is provided, then the select switch 22 is set to ON to enable the operation board 15 and the MDI 16 for operation, thereby allowing the operator to operate the NC machine tool 14 (step 117). The CNC reads the operator name 33 recorded in the IC card 1 and records the operator name 33 and the work starting date and time of day into the operation recording memory of the NC unit 10 as shown in FIG. 28 on the basis of the calendar and clock data in the CNC (step 118). Processing on the language data is then performed (step 119). This process replaces the language data in the NC unit 10 with the language data stored in the IC card 1, thereby changing the language displayed by the NC unit 10 if appropriate. The display control section concerned with the present invention will now be described. FIG. 11 is a block diagram illustrating the display control section of the NC unit 10 concerned with the embodiment of the present invention, wherein the numeral 1 indicates an IC card which, as shown in FIG. 3, includes a storage section 3 for storing various types of data including message data corresponding to the specified language in the area 77 and font data corresponding to the same language in the area 78. The message and font data are language data, e.g. data for English, French, Korean and German. As shown in FIG. 11, a font RAM 73 is used as a memory for storing the font data to allow the font data in the NC 10 to be changed. As shown in FIG. 19, the font RAM 73 is divided into a common font section 75 (a font section used commonly for each language, and containing such common elements as numerals, symbols, etc.) and a language-basis font section 76. Since the common font section 75 need not be changed according to the language used, only the language-basis font section 76 is changed. This language-basis font section is also stored in the font data section 78 of the IC card 1. If desired, the IC card may be made to store the common section data as well, as a guard against memory loss due to battery failure or the like in the NC itself. Further, a RAM area 74 for storing message data on a language basis is provided as shown in FIG. 11 to display messages corresponding to the language used. Messages to be shown on the NC display are not described directly in the control program in the NC 10 but message numbers are described in the control program so that the required message is displayed by extracting the message data corresponding to the specified number from the message RAM 74. In language processing, a check is first made to see if the language data in the IC card 1, i.e. the message data 77 and the font data 78, exist as shown in the processing flowchart of FIG. 21 (step 141). If that data does not exist, language data processing is not performed. If the data exists, a check is made to see if the font data 78 in the IC card 1 differs from the font data 74 stored in the NC (step 142). If they are identical, font data processing is not performed. If they are different, font data 78 is entered from the IC card 1 to the font RAM 73 in the NC unit 10 (step 143)o A check is made to see if the message data 77 in the IC card 1 differs from the message data 74 stored in the NC 10 (step 144). If they are identical, message data processing is not performed. If they are different, the message data 77 is entered from the IC card 1 to the message RAM 74 in the NC unit 10 (step 145). To identify whether the font data 73 is different or not, a language identification code 84 in the font data section 78 as shown in FIG. 20 is compared with the language identification codes in the font data section of the CNC. The message data is also identified in an identical manner. As described above, the contents of the font RAM 73 can be changed as appropriate by storing the font data placed in the font data area 78 of the IC card 1 into the font RAM 73 of the NC unit 10. The contents of the message RAM 74 can be changed as appropriate by storing the message data placed in the message data area 77 of the IC card 1 into the message RAM 74 of the NC unit 10. Returning to FIG. 7 again, the process of giving work directives to the operator on the basis of the work directive data 37 in the IC card 1 will now be described. After reading the work directive data 37 in the IC card 1, the NC unit 10 proceeds with the work by displaying a work directive for the operator according to the data described in the work directive data area 37 (step 120), entering the cutting program, parameters, tool information, etc. as required (step 121), storing the work record into the work record data area 39 of the IC card 1 (step 122), and performing the batch processing for the next work directive. When all work is complete (step 123), the NC unit 10 records the work end time of day in the CNC (step 124) and terminates the work. At this time, the select switch 22 is set to OFF to disable the NC machine tool for further operations (step 125). The above work directive data is processed as batch data in a batch processor 8 as shown in FIG. 24. While the NC unit known in the art only analyzes and runs the cutting program in a cutting program processor 9, the NC unit 10 according to the present invention is provided with the batch processor 8 on a higher level than the cutting program processor 9 to allow the batch data such as the work directive data 32 to be processed, the NC unit 10 to transfer various types of data, such as the cutting program, parameter and tool data, and run the specified cutting program the specified number of times, and to allow the data to be displayed on the display unit 17 of the NC unit 10 to give the operator the work directives. It is also possible to switch from batch processing to ordinary processing to operate the NC unit 10 without performing batch processing, unlike in the ordinary NC unit. The operator's operations during batch processing will now be described. FIG. 14 gives an example of a display provided on the CRT screen 72 of the display unit 17 on the NC unit 10 while batch processing is performed. As shown on this screen, it is possible to display a work directive for the operator on the CRT screen 72 on the basis of the work directly data 37. Menu items "PRECEDING SCREEN" and "FOLLOWING SCREEN" are employed to view the preceding screen and the following screen, respectively, when a long work directive must be displayed over a plurality of screens. By pressing a menu key 25 corresponding to a menu item "WORK DIRECTIVE" among menu items 27, the most recent work directive data is displayed on the screen 72. This is because display data 26 to be shown on the CRT screen 72 of the display unit 17 on the NC unit 10 are created by synthesizing screen data 29 created by ordinary processing, i.e. screen data to be displayed when batch processing is not performed, and screen data 30 created by the batch processing as shown in FIG. 26. The data 29, 30 is stored until updated, and therefore, any area cleared by the data 30 displayed by batch processing can be restored any time, and conversely, the data 30 created by the batch processing can be displayed again. If the ordinary screen data 29 is overwritten by the data 30 created by the batch processing on the screen display, the menu item "WORK DIRECTIVE" is highlighted. If the data 30 created by the batch processing is erased, the "WORK DIRECTIVE" item is not highlighted. By selecting this "WORK DIRECTIVE" menu item, the work directive display can be erased or redisplayed. When the work directly extends over a plurality of screens, all data is created in the area 30 and part of that data is displayed on the screen. Therefore, the required area of the work directive can be displayed on the CRT screen 72 by pressing the menu item "PRECEDING SCREEN" or "FOLLOWING SCREEN". A menu item "PRINT" is employed to print the work directive, i.e., the data displayed by batch processing, on a printer. By pressing a menu key 25 corresponding to a menu item "FREE OPERATION", the batch processing is stopped and the ordinary NC unit operation is enabled. In this case, the "FREE OPERATION" menu item changes to "BATCH OPERATION" and the selection of "BATCH OPERATION" allows the batch operation to be resumed (i.e., the menu key acts as a toggle). However, since interruption occurs partway during the batch operation, it is necessary to resume the batch operation after returning to a state wherein the batch operation may be resumed (e.g. machine state). This allows the operator to interrupt the batch processing as appropriate and perform arbitrary processing. Since the NC unit 10 according to the present invention also allows the processing to be either performed via the batch processor 8 or in the same manner as in the ordinary NC unit without batch processing as shown in FIG. 24, the NC unit 10 can be used while switching between batch processing and ordinary processing as necessary. A menu item "CHECK" is used to notify the NC unit 10 that the operator has finished the required work in response to the work directive. The work directly data will now be described. FIG. 13 provides an example of the work directive data, which is stored in the work directly data area 37 of the IC card 1. The NC reads and executes this data sequentially. It should be noted that while the work directive data 37 is executed after it is read in the system of the present invention, it is possible to sequentially execute the work directive data 37 while simultaneously reading it from the IC card 1. In FIG. 13: *DISP ALL indicates that the entire area of the CRT screen 72 of the display unit 17 on the NC unit 10 is used. This causes the whole area of the CRT screen 72 to be employed for display. When it is desired to use only part of the CRT screen 72, e.g. it is desired to overwrite the ordinary NC unit display screen and use only part thereof, the operator can specify the area desired for use as indicated below: *DISP @16, 50-20, 80 which indicates that only the area from line 16, column 50 to line 20, column 80 on the screen is used for display and the previously displayed data remains in the other area. By specifying the employed area as indicated above, specified data is displayed only in the specified part of the screen marked 28 in FIG. 17 and the previous display remains in the other part. *CLEAR indicates that the specified screen area (the entire screen for *DISP ALL and only the specified portion for other display situations, i.e., *DISP @16, 50-20, 80) is cleared. *@6, 23 SAY "*** TOOL LAYOUT ***" indicates that the data enclosed in the quotation marks (" ") is displayed in the specified position, i.e.: *** TOOL LAYOUT *** is displayed, beginning in line 6, column 23, in the above example. *CHECK progresses the execution to the next step when the operator presses the menu key 25 corresponding to the "CHECK" menu item 27 displayed on the display unit 17 in FIG. 14. *LOAD W120 indicates that the cutting program for workpiece No. 120 in the IC card 1 is stored into the memory 18 of the NC unit 10. *LOAD P001, 90.08.03 indicates that parameters in the IC card 1 are stored into the memory 18 of the NC unit 10. "P001" shown above is a parameter name and "90.8.03" denotes the date of creation. The NC unit 10 according to the present invention manages all data, such as the parameters and tool data, under names 81 and dates 82 assigned thereto as indicated in FIG. 22; wherein the numeral 80 indicates a parameter data section contained in the memory 18 of the NC unit 10 and parameter names 81 and dates of creation 82 are stored therein together with parameter data 83. The date may include year, month, day and time of day. FIG. 23 illustrates a processing flowchart for storing the data of the IC card 1 into the memory 18 of the NC unit 10. First a check is made to see if a parameter specified in the work data 37 also exists in the cutting data area 38 of the IC card 1 (step 151). In this case, a check is made to determine whether both the parameter name and date are identical. If the specified parameter does not exist in the IC card 1, a check is made to see if the specified parameter is identical to a parameter stored in the NC (step 152). If it does and they are identical, the processing is terminated. If they are different, error processing is performed (step 153) and the processing is then terminated. In error processing, a message is displayed to notify the operator that the parameter does not exist and asks the operator what to do. If the specified parameter exists in the IC card 1 at step 151, a check is made to see if the specified parameter is identical to one stored in the NC (step 154). If they are different, the parameter stored in the cutting data area 38 of the IC card 1 is read to the memory 18 of the NC unit 10 (step 155). If they are identical, processing is terminated since the parameter need not be read. Whether they are identical or not is Judged by the parameter names 81 and parameter dates 82. When the corresponding data is rewritten by the operator, the dates 82 are also changed to the dates when the data has been rewritten. This allows any data, whether or not it has been changed by the operator, to be easily identified. Returning now to FIG. 13: *LOAD T001, 90.08.11 indicates that the tool data is stored into the memory 18 of the NC unit 10. As in the case of parameters, "T001" is a tool data name and "09.08.11" represents a date of creation. The procedure for storing the tool data into the NC unit 10 is also similar to that used in the case of parameters. *D0 W120, 1500 indicates a command which repeats the cutting of workpiece No. 120 1500 times. This causes the NC unit 10 to be started and the cutting program of the workpiece No. 120 to be consecutively run 1500 times. FIG. 14 illustrates a work directive displayed on the CRT screen 72 of the display unit 17 on the NC unit 10 at a time when the work data in FIG. 13 is executed. This directive instructs the operator to set the tool data as directed. When the operator presses the menu key 25 corresponding to the menu item "CHECK" 27 after setting and checking the tool data, the next work directive as shown in FIG. 15 is displayed. In this way, appropriate work directives can be given to the operator sequentially on the basis of the work directive data 37. As soon as the cutting of 1500 pieces of workpiece No. 120 is finished, the next directive as shown in FIG. 16 is displayed whereby the operator can progress the work according to the appropriate work directives from the NC unit 10. As the work directives are given only at the beginning and end of cutting in the above example, the creation of work directive data as shown in FIG. 25 allows the "NUMBER OF WORKPIECES CUT" incremented by 1 every time one workpiece is cut to be displayed on part of the screen marked 28 in FIG. 17. FIG. 25 illustrates a batch program showing how this would be done: *WC=0 indicates 0 is assigned to a variable named WC". *DOWHILE WC<1500 indicates the execution is repeated up to *ENDDO if the value of "WC" is less than 1500. *WC=WC+1 indicates that the value of "WC" is incremented by 1. @18, 66 DISPN(WC, 4, 0) indicates that the value of "WC" is displayed in four digits and zero decimal places, beginning in line 18, column 60. "WC" is a numerical value representing the number of workpieces cut. In the above example, the batch processing data is treated as the work directive data 37 separately from the cutting program and executed by the batch processor 8. However, since any batch data is headed by "*" or "@" which clearly differentiates batch data from ordinary NC cutting program commands, i.e. a cutting program conforming to the EIA programming standard, the batch data may be described within the ordinary cutting program and executed separately from the cutting program. This allows directives to be given and messages to be displayed for the operator more appropriately when they are required partway through the cutting. FIG. 18 shows an example of data recorded in the work record data area 39 of the IC card 1, wherein the work start time of day and the end time of day are recorded. In this example, the work was started at 8:11 in the morning on Aug. 7, 1990 and ended at 4:41 in the afternoon on the same day. During the work, the "time of day" when a "CODE" and its event occur and the "details" of the event are recorded. In this example, the following information is recorded: 1) The input of workpiece No. 120 data was started at 8:15: 2) The input of parameter "P001" was started at 8:17; 3) The input of tool data "T001" was started at 8:20; 4) The beginning of cutting of workpiece No. 120 500 times was started at 8:31; 5) The cutting of 500 copies of workpiece No. 120 ended at 11:54; 6) Work was halted at 12:03; 7) Work was restarted at 1:17; 8) The input of data on workpiece No. 700 was started at 1:26; 9) The cutting of the first of 200 copies of workpiece No. 700 was started at 1:47; 10) Tool No. 11 was broken at 2:13 (at this point, 47 copies of workpiece No. 700 were finished); 11) Tool data "T001" was changed at 2:34; 12) Cutting was resumed at 2:47; and 13) The cutting of 200 copies of workpiece No. 700 ended at 4:07. The manager 51 can display this data on the display 45 of the processor 40 or print it on the printer 46. FIG. 9 shows a work operation record stored in the operation recording memory 23 in the CNC. In this example, an operator named "MITSUBISHI MIKI" operated continuously from 8:11 to 4:41 on Aug. 7, 1990, and then an operator named "MITSUBISHI YOUKO" began work at 8:15 on Aug. 8, 1990. A detailed work record similar to the data recorded in the work record data area 39 of the IC card 1 is also recorded here at the same time. The present invention allows only authorized operators to operate the CNC, ensuring that the CNC cannot be employed without permission. In addition, closer management can be performed because operators may be authorized to use the CNC corresponding to only one or a plurality of machines. Unlike the data rewrite disable key employed with the prior art CNC, the present invention allows any operator use to be invalidated, thereby preventing illegal use. The present invention can selectively disable operation for items resulting in inconvenience if rewritten erroneously, e.g. parameters and cutting programs, eliminating the possibility of illegal data changes. Closer management can be conducted since permission is granted on an operator basis. Unless the portable storage medium is loaded, the present invention disables the operation of the CNC to prevent the CNC from being operated illegally. Further, if the operator removes storage medium on leaving the field site, it is possible to completely prevent the CNC from being operated by any unauthorized person. The present invention allows the CNC to be operated only during a period and time band permitted to the operator. The present invention allows the language shown on the display of the NC to be changed as desired according to the operator, whereby the NC can be operated by any operator independently of the language he or she speaks and utilized in any country, contributing to the achievement of effective utilization of the NC on an international basis. In addition, the present invention ensures ease of changing the language, producing an advantageous effect on the utilization environment of the NC wherein different languages are employed alternately. Further, data necessary for the change in language is placed in a single IC card which is freely portable and the operator can carry his or her own IC card and easily switch to a language he or she prefers at the start of work, leading to an improvement in working environment of the operator. Moreover, since the font in the NC can be changed, symbols and the like can be used as required to give a message to the operator. Further, the present invention prevents the contents of the font RAM or the message RAM from being rewritten accidentally; the external storage medium contains the desired font data or message data. The CNC describes all necessary instructions automatically in the work directive data and executes the data in batch processing. This ensures that data entry errors, misoperation, etc. can be prevented. In addition, when manual work by the operator is unnecessary, all work can be done by batch processing only, which eliminates the need of manpower other than an operator deployed in the case of an emergency, making a large contribution toward unattended operation of the CNC. The present invention can give appropriate work directives to the operator by sequentially displaying them on the CNC screen. The present invention allows switching between the work directive display and the ordinary CNC display so that the last work directive displayed may be checked. The operator can output the work directive displayed on the screen to the printer as required, which is useful when work must be done at a location where it is difficult for the operator to do the work and view the screen at the same time. When it is desired to stop the work, batch processing can be stopped and resumed at any time, which is useful when the operator wishes to stop a machine tool and take a rest or when it is desired to halt cutting for such purposes as chip removal. Data such as parameters and tool information need not be checked in detail and can be differentiated using assigned names so that whether or not the data is correct can be Judged by simply checking the names before cutting. As compared to a case where names cannot be assigned in the prior art, easier management is ensured by assigning names to the data corresponding to cutting. If data has been rewritten with the name remaining unchanged, the date of creation can be assigned for ease of checking if the data has been rewritten. Comparison of the names and dates of creation allows any data to be checked securely, increasing the reliability of the work. Data can be displayed on the CNC screen during the run of a cutting program and the control of the cutting program run itself can be described in a dedicated language, making the cutting program control considerably flexible. The work record of each operator can be kept exactly to ensure precise work management. The operation record of the CNC can be kept exactly to ensure proper CNC management. This allows any accident resulting from misoperation, etc. to be troubleshooted easily.

A numerical control system for controlling a machine tool including a control device for controlling the machine tool; external portable storage device for storing data; a disabling device for disabling the control device; a read/write device, operable when the external portable storage device is manually coupled thereto, for reading data from the external portable storage device and for writing data to the external portable storage device; and a determining device for determining whether the external portable storage device is coupled to the read/write device. The disabling device disables the control device when the determining device determines that the external portable storage devices not coupled to the read/write

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims benefit of U.S. Provisional Application No. 62/195,085, filed Jul. 21, 2015, which is hereby incorporated herein by reference in its entirety. BACKGROUND [0002] Mycobacterium avium subspecies paratuberculosis (MAP) is a bacteria implicated in the etiology of multiple diseases including Crohn's disease and diabetes mellitus in humans [Hermon-Taylor, J., et al. (2000). Can J Gastroenterol, 14(6):521-542; Sechi, L. A., et al. (2008). Clin Infect Dis, 46(1):148-149]. It is also known to be a causative agent of Johne's disease, a bovine disease similar to Crohn's disease [Naser, S. A., et al. (2004). The Lancet, 364(9439):1039-1044]. It is an obligate intracellular pathogen, living inside the macrophages of the infected host [Xu, S., et al. (1994). J Immunol, 153(6):2568-2578]. MAP increases the suitability of the macrophage as a host and prevents its own destruction by preventing the acidification of the phagosome and by preventing the fusion of the lysosome and the phagosome into the phagolysosomal complex [Crowle, A. J., et al. (1991). Infect Immun, 59(5):1823-1831; Frehel, C., et al. (1986). Infect Immun, 52(1):252-262]. They are also resistant to destruction even in an acidified, mature phagolysosome [Gomes, M. S., et al. (1999). Infect Immun, 67(7):3199-3206]. The primary mechanism for the destruction of M. avium resistant to phagolysosomal degradation is the induction of apoptosis of the infected macrophage through a tumor necrosis factor α (TNF-α) dependent mechanism [Fratazzi, C., et al. (1999). J Leukoc Biol, 66(5):763-764; Fratazzi, C., et al. (1997). J Immunol, 158(9):4320-4327]. There is evidence that Mycobacteria evade this host response by inhibiting apoptosis, and by stimulating necrosis, which allows the bacteria to disseminate [Kabara, E., et al. (2012). Front Microbiol, 3; Behar, S. M., et al. (2010). Nature Reviews Microbiology, 8(9):668-674]. Furthermore, in an active infection the body's ability to clear apoptotic cells may be outpaced. The delay in clearance results in the apoptotic cell bodies losing their membrane integrity and becoming secondary necrotic cells [Elliott, M. R., et al. (2010). J Cell Biol, 189(7):1059-1070]. In the case of the apoptosis of an active macrophage, this includes the leaking of lysosomal content, including reactive oxygen species (ROS), leading to inflammation and oxidative stress. [0003] Mycobacteria are slow growing microorganisms, which can require several months for visible colonies to be observed on sold agar media. Molecular techniques including Polymerase Chain reaction (PCR) techniques require extensive time, cost and labor. There is therefore a need for a predictive test of mycobacteria in samples to provide faster and cost-effective alternatives. SUMMARY [0004] Compositions and methods for predicting the presence of a mycobacterial infection in a sample, such as a sample from a subject, are provided. In some embodiments, the method further comprises assaying the sample to directly detect the presence of the mycobacterial infection if infection is predicted. However, as this is a time-consuming and expensive process, the disclosed methods can be used to predict the presence of the mycobacterium prior to confirmation by direct detection, thereby saving time and money. [0005] The disclosed method involves assaying a biological sample from the subject for detection of selenium, wherein the presence of selenium in the sample is an indication of mycobacterium in the sample. In some embodiments, the method involves directly detecting the presence of selenium using separation and elemental detection techniques, e.g., high performance liquid chromatography (HPLC) with inductively coupled plasma mass spectrometry (ICP-MS). [0006] In some embodiments, the method involves detecting the presence of a selenoprotein in the sample. For example, selenoproteins can be detected by immunoassay using antibodies or the like that selectively bind the selenoprotein. However, the selenoprotein can also be detected indirectly by assaying for its enzymatic activity. This generally involves the use of a colorimetric assay of the selenoprotein's enzymatic activity. [0007] The disclosed methods are disclosed for use with any mycobacterium . In some cases, the mycobacterium is a slow growing mycobacterium . In some embodiments, the mycobacterium is selected from the group consisting of a Mycobacterium tuberculosis complex, a Mycobacterium avium complex (MAC), a Mycobacterium gordonae clade, a Mycobacterium kansasii clade, a Mycobacterium nonchromogenicum/terrae clade, a Mycolactone-producing mycobacteria, and a Mycobacterium simiae clade. In some embodiments, the mycobacterium is selected from the group consisting of M. bohemicum, M. botniense, M. branderi, M. celatum, M. chimaera, M. conspicuum, M. cookii, M. doricum, M. farcinogenes, M. haemophilum, M. heckeshornense, M. intracellulare, M. lacus, M. leprae, M. lepraemurium, M. lepromatosis, M. malmoense, M marinum, M. monacense, M. montefiorense, M. murale, M. nebraskense, M. saskatchewanense, M. scrofulaceum, M. shimoidei, M. szulgai, M. tusciae, M. xenopi, and M. yongonense. [0008] In some embodiments, the mycobacterium is MAP, and the selenoprotein is a glutathione peroxidase. In these embodiments, MAP can be predicted based on the detection of an increase in glutathione peroxidase cellular activity in a sample from the subject. [0009] Mycobacterial infections are believed to be involved in the pathogenesis of many diseases, including inflammatory bowel disease (e.g., Crohn's disease and ulcerative colitis), tuberculosis, Type I Diabetes Mellitus, and Multiple Sclerosis. Therefore, in some embodiments, the subject of the disclosed method has or is suspected of having inflammatory bowel disease, tuberculosis, Type I Diabetes Mellitus, or Multiple Sclerosis. [0010] Once a mycobacterium is predicated, and optionally confirmed by direct detection, the method can further comprising treating the subject with a therapeutically effective amount of an antibiotic. In addition, the subject's infection can be monitored after treatment with the antibiotic using the disclosed methods to confirm that the treatment is effective. [0011] The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. DESCRIPTION OF DRAWINGS [0012] FIG. 1 depicts reduced and oxidized states of glutathione. [0013] FIG. 2 shows agarose gels illustrating the presence or absence of MAP-IS900 gene following nPCR. The PCR products following the second round of nPCR were analyzed on 2% agarose gel. M represents molecular weight marker in bp. = represents negative control from second round of amplification. − represents negative control from first round of amplification. TE represents TE buffer negative control. + represents positive control prepared from MAP DNA strain ATCC 43015. 1-100 represents patient samples. [0014] FIG. 3A is a Scatter plot of selenium-dependent GPx activity for MAP negative and MAP positive bovine samples. FIG. 3B is a scatter plot of selenium-dependent GPx activity for MAP negative and MAP positive samples among CD patients and healthy relatives. FIG. 3C is a scatter plot of selenium-dependent GPx activity for Healthy and CD individuals. FIG. 3D is a scatter plot of selenium-dependent GPx activity for MAP negative and MAP positive among CD patients. FIG. 3E is a scatter plot of selenium-dependent GPx activity for MAP negative and MAP positive in randomized field study. [0015] FIG. 4 is a bar graph showing average GPx activity levels in plasma samples from blood samples identified as MAP negative and positive individuals according to according to disease status. DETAILED DESCRIPTION [0016] Bacterial infections are a major global healthcare problem, and their detection has to be performed in diverse settings and samples preferably with single-instrument-based diagnostic modalities, using sensitive and robust probes. Mycobacterium avium spp. paratuberculosis (MAP) is found within the white blood cells of infected animals with Johne's disease, a form of animal paratuberculosis, which is associated with chronic enteritis, reminiscent of Crohn's disease in humans. In humans, Crohn's disease is a debilitating chronic inflammatory syndrome of the gastrointestinal track and adjacent lymph nodes. The detection of MAP in tissues from patients with Crohn's disease has been extensively reported, including in human peripheral blood. In those studies, MAP was identified by a culture method followed by PCR identification of a MAP genomic marker. The whole process took several months to complete, due to the slow growing nature of this pathogen. Such a slow detection method not only delays the diagnosis, but also slows any potential therapeutic intervention. Likewise, difficulties in detecting an intracellular pathogen, such as MAP, hamper studies aimed at the investigation of the potential role of MAP in Crohn's disease pathology, as well as the pathogen's impact on the dairy and beef industries. Compositions and methods are therefore disclosed for predicting the presence of a mycobacterial infection in a sample, such as a sample from a subject. [0017] As used herein, a “sample” or “test sample” can include, but is not limited to, biological material obtained from an organism or from components of an organism, food sample, or environmental sample (e.g. water sample or any other sample from an environmental source believed to contain a microorganism). The test sample may be of any biological tissue or fluid, for example. In some embodiments, the test sample can be a sample from a subject. Examples of sample from a subject include, but are not limited to sputum, cerebrospinal fluid, blood, blood fractions such as serum and plasma, blood cells, tissue, biopsy samples, urine, peritoneal fluid, pleural fluid, amniotic fluid, vaginal swab, skin, lymph fluid, synovial fluid, feces, tears, organs, or tumors. A test sample can also include recombinant cells, cell components, cells grown in vitro, and cell culture constituents including, for example, conditioned medium resulting from the growth of cells in cell culture medium. [0018] The term “subject” refers to any individual who is the target of administration or treatment. The subject can be a vertebrate, for example, a mammal. Thus, the subject can be a human or veterinary patient. The term “patient” refers to a subject under the treatment of a clinician, e.g., physician. [0019] The term “predict” does not refer to the ability to predict the presence of a mycobacterial infection with 100% accuracy. Instead, the skilled artisan will understand that the term “predict” refers to an increased probability that a sample has a mycobacterial infection. [0020] The term “infection” refers to a microbial invasion of living tissue that is deleterious to the organism. [0021] The term “therapeutically effective” refers to the amount of the composition used is of sufficient quantity to ameliorate one or more causes or symptoms of a disease or disorder. Such amelioration only requires a reduction or alteration, not necessarily elimination. [0022] The term “treatment” refers to the medical management of a patient with the intent to cure, ameliorate, stabilize, or prevent a disease, pathological condition, or disorder. This term includes active treatment, that is, treatment directed specifically toward the improvement of a disease, pathological condition, or disorder, and also includes causal treatment, that is, treatment directed toward removal of the cause of the associated disease, pathological condition, or disorder. In addition, this term includes palliative treatment, that is, treatment designed for the relief of symptoms rather than the curing of the disease, pathological condition, or disorder; preventative treatment, that is, treatment directed to minimizing or partially or completely inhibiting the development of the associated disease, pathological condition, or disorder; and supportive treatment, that is, treatment employed to supplement another specific therapy directed toward the improvement of the associated disease, pathological condition, or disorder. [0023] The term “antibody” refers to natural or synthetic antibodies that selectively bind a target antigen. The term includes polyclonal and monoclonal antibodies. In addition to intact immunoglobulin molecules, also included in the term “antibodies” are fragments or polymers of those immunoglobulin molecules, and human or humanized versions of immunoglobulin molecules that selectively bind the target antigen. [0024] The term “specifically binds”, as used herein, when referring to a polypeptide (including antibodies) or receptor, refers to a binding reaction which is determinative of the presence of the protein or polypeptide or receptor in a heterogeneous population of proteins and other biologics. Thus, under designated conditions (e.g. immunoassay conditions in the case of an antibody), a specified ligand or antibody “specifically binds” to its particular “target” (e.g. an antibody specifically binds to an endothelial antigen) when it does not bind in a significant amount to other proteins present in the sample or to other proteins to which the ligand or antibody may come in contact in an organism. Generally, a first molecule that “specifically binds” a second molecule has an affinity constant (Ka) greater than about 10 5 M −1 (e.g., 10 6 M −1 , 10 7 M −1 , 10 8 M −1 , 10 9 M −1 , 10 10 M −1 , 10 11 M −1 , and 10 12 M −1 or more) with that second molecule. [0025] Selenium Measurement [0026] The measurement of Selenium and/or Selenium-dependent glutathione peroxidase/molecules can be performed using standard methods available in the market. [0027] In some embodiments, the method involves directly detecting the presence of selenium using separation and elemental detection techniques. Suitable separation techniques include high performance liquid chromatography (HPLC), gas chromatography (GC), and capillary electrophoresis (CE). Suitable elemental detection techniques include any type of mass spectrometry, including but not limited to matrix assisted laser desorption time of flight (MALDI-TOF) mass spectrometry, electrospray mass spectrometry, inductively coupled plasma mass spectrometry (ICP/MS), ICP-atomic emission spectrometry (ICP/AES), atomic fluorescence spectrometry (AFS), and atomic absorption spectrometry (AAS). For example, HPLC-ICP/MS can be used for the detection and speciation of selenium in the sample. [0028] In some embodiments, the method involves detecting the presence of a selenoprotein in the sample. For example, selenoproteins can be detected by immunoassay using antibodies or the like that selectively bind the selenoprotein. [0029] The steps of various useful immunodetection methods have been described in the scientific literature, such as, e.g., Maggio et al., Enzyme-Immunoassay, (1987) and Nakamura, et al., Enzyme Immunoassays: Heterogeneous and Homogeneous Systems, Handbook of Experimental Immunology, Vol. 1: Immunochemistry, 27.1-27.20 (1986), each of which is incorporated herein by reference in its entirety and specifically for its teaching regarding immunodetection methods. Immunoassays, in their most simple and direct sense, are binding assays involving binding between antibodies and antigen. Many types and formats of immunoassays are known and all are suitable for detecting the disclosed biomarkers. Examples of immunoassays are enzyme linked immunosorbant assays (ELISAs), radioimmunoassays (MA), radioimmune precipitation assays (RIPA), immunobead capture assays, Western blotting, dot blotting, gel-shift assays, Flow cytometry, protein arrays, multiplexed bead arrays, magnetic capture, in vivo imaging, fluorescence resonance energy transfer (FRET), and fluorescence recovery/localization after photobleaching (FRAP/FLAP). [0030] In general, immunoassays involve contacting a sample suspected of containing a molecule of interest (such as the disclosed biomarkers) with an antibody to the molecule of interest or contacting an antibody to a molecule of interest (such as antibodies to the disclosed biomarkers) with a molecule that can be bound by the antibody, as the case may be, under conditions effective to allow the formation of immunocomplexes. Contacting a sample with the antibody to the molecule of interest or with the molecule that can be bound by an antibody to the molecule of interest under conditions effective and for a period of time sufficient to allow the formation of immune complexes (primary immune complexes) is generally a matter of simply bringing into contact the molecule or antibody and the sample and incubating the mixture for a period of time long enough for the antibodies to form immune complexes with, i.e., to bind to, any molecules (e.g., antigens) present to which the antibodies can bind. In many forms of immunoassay, the sample-antibody composition, such as a tissue section, ELISA plate, dot blot or Western blot, can then be washed to remove any non-specifically bound antibody species, allowing only those antibodies specifically bound within the primary immune complexes to be detected. [0031] Immunoassays can include methods for detecting or quantifying the amount of a molecule of interest (such as the disclosed biomarkers or their antibodies) in a sample, which methods generally involve the detection or quantitation of any immune complexes formed during the binding process. In general, the detection of immunocomplex formation is well known in the art and can be achieved through the application of numerous approaches. These methods are generally based upon the detection of a label or marker, such as any radioactive, fluorescent, biological or enzymatic tags or any other known label. See, for example, U.S. Pat. Nos. 3,817,837; 3,850,752; 3,939,350; 3,996,345; 4,277,437; 4,275,149 and 4,366,241, each of which is incorporated herein by reference in its entirety and specifically for teachings regarding immunodetection methods and labels. [0032] As used herein, a label can include a fluorescent dye, a member of a binding pair, such as biotin/streptavidin, a metal (e.g., gold), or an epitope tag that can specifically interact with a molecule that can be detected, such as by producing a colored substrate or fluorescence. Substances suitable for detectably labeling proteins include fluorescent dyes (also known herein as fluorochromes and fluorophores) and enzymes that react with colorometric substrates (e.g., horseradish peroxidase). The use of fluorescent dyes is generally preferred in the practice of the invention as they can be detected at very low amounts. Furthermore, in the case where multiple antigens are reacted with a single array, each antigen can be labeled with a distinct fluorescent compound for simultaneous detection. Labeled spots on the array are detected using a fluorimeter, the presence of a signal indicating an antigen bound to a specific antibody. [0033] Fluorophores are compounds or molecules that luminesce. Typically fluorophores absorb electromagnetic energy at one wavelength and emit electromagnetic energy at a second wavelength. Representative fluorophores include, but are not limited to, 1,5 IAEDANS; 1,8-ANS; 4-Methylumbelliferone; 5-carboxy-2,7-dichlorofluorescein; 5-Carboxyfluorescein (5-FAM); 5-Carboxynapthofluorescein; 5-Carboxytetramethylrhodamine (5-TAMRA); 5-Hydroxy Tryptamine (5-HAT); 5-ROX (carboxy-X-rhodamine); 6-Carboxyrhodamine 6G; 6-CR 6G; 6-JOE; 7-Amino-4-methylcoumarin; 7-Aminoactinomycin D (7-AAD); 7-Hydroxy-4-I methylcoumarin; 9-Amino-6-chloro-2-methoxyacridine (ACMA); ABQ; Acid Fuchsin; Acridine Orange; Acridine Red; Acridine Yellow; Acriflavin; Acriflavin Feulgen SITSA; Aequorin (Photoprotein); AFPs—AutoFluorescent Protein—(Quantum Biotechnologies) see sgGFP, sgBFP; Alexa Fluor 350™; Alexa Fluor 430™; Alexa Fluor 488™; Alexa Fluor 532™; Alexa Fluor 546™; Alexa Fluor 568™; Alexa Fluor 594™; Alexa Fluor 633™; Alexa Fluor 647™; Alexa Fluor 660™; Alexa Fluor 680™; Alizarin Complexon; Alizarin Red; Allophycocyanin (APC); AMC, AMCA-S; Aminomethylcoumarin (AMCA); AMCA-X; Aminoactinomycin D; Aminocoumarin; Anilin Blue; Anthrocyl stearate; APC-Cy7; APTRA-BTC; APTS; Astrazon Brilliant Red 4G; Astrazon Orange R; Astrazon Red 6B; Astrazon Yellow 7 GLL; Atabrine; ATTO-TAG™ CBQCA; ATTO-TAG™ FQ; Auramine; Aurophosphine G; Aurophosphine; BAO 9 (Bisaminophenyloxadiazole); BCECF (high pH); BCECF (low pH); Berberine Sulphate; Beta Lactamase; BFP blue shifted GFP (Y66H); Blue Fluorescent Protein; BFP/GFP FRET; Bimane; Bisbenzemide; Bisbenzimide (Hoechst); bis-BTC; Blancophor FFG; Blancophor SV; BOBO™-1; BOBO™-3; Bodipy492/515; Bodipy493/503; Bodipy500/510; Bodipy; 505/515; Bodipy 530/550; Bodipy 542/563; Bodipy 558/568; Bodipy 564/570; Bodipy 576/589; Bodipy 581/591; Bodipy 630/650-X; Bodipy 650/665-X; Bodipy 665/676; Bodipy Fl; Bodipy FL ATP; Bodipy Fl-Ceramide; Bodipy R6G SE; Bodipy TMR; Bodipy TMR-X conjugate; Bodipy TMR-X, SE; Bodipy TR; Bodipy TR ATP; Bodipy TR-X SE; BO-PRO™-1; BO-PRO™-3; Brilliant Sulphoflavin FF; BTC; BTC-5N; Calcein; Calcein Blue; Calcium Crimson -; Calcium Green; Calcium Green-1 Ca 2+ Dye; Calcium Green-2 Ca 2+ ; Calcium Green-5N Ca 2+ ; Calcium Green-C18 Ca 2+ ; Calcium Orange; Calcofluor White; Carboxy-X-rhodamine (5-ROX); Cascade Blue™; Cascade Yellow; Catecholamine; CCF2 (GeneBlazer); CFDA; CFP (Cyan Fluorescent Protein); CFP/YFP FRET; Chlorophyll; Chromomycin A; Chromomycin A; CL-NERF; CMFDA; Coelenterazine; Coelenterazine cp; Coelenterazine f; Coelenterazine fcp; Coelenterazine h; Coelenterazine hcp; Coelenterazine ip; Coelenterazine n; Coelenterazine O; Coumarin Phalloidin; C-phycocyanine; CPM I Methylcoumarin; CTC; CTC Formazan; Cy2™; Cy3.18; Cy3.5™; Cy3™; Cy5.18; Cy5.5™; Cy5™; Cy7™; Cyan GFP; cyclic AMP Fluorosensor (FiCRhR); Dabcyl; Dansyl; Dansyl Amine; Dansyl Cadaverine; Dansyl Chloride; Dansyl DHPE; Dansyl fluoride; DAPI; Dapoxyl; Dapoxyl 2; Dapoxyl 3′DCFDA; DCFH (Dichlorodihydrofluorescein Diacetate); DDAO; DHR (Dihydorhodamine 123); Di-4-ANEPPS; Di-8-ANEPPS (non-ratio); DiA (4-Di 16-ASP); Dichlorodihydrofluorescein Diacetate (DCFH); DiD-Lipophilic Tracer; DiD (DilC18(5)); DIDS; Dihydorhodamine 123 (DHR); Dil (DilC18(3)); I Dinitrophenol; DiO (DiOC18(3)); DiR; DiR (DilC18(7)); DM-NERF (high pH); DNP; Dopamine; DsRed; DTAF; DY-630-NHS; DY-635-NHS; EBFP; ECFP; EGFP; ELF 97; Eosin; Erythrosin; Erythrosin ITC; Ethidium Bromide; Ethidium homodimer-1 (EthD-1); Euchrysin; EukoLight; Europium (111) chloride; EYFP; Fast Blue; FDA; Feulgen (Pararosaniline); FIF (Formaldehyde Induced Fluorescence); FITC; Flazo Orange; Fluo-3; Fluo-4; Fluorescein (FITC); Fluorescein Diacetate; Fluoro-Emerald; Fluoro-Gold (Hydroxystilbamidine); Fluor-Ruby; FluorX; FM 1-43™; FM 4-46; Fura Red™ (high pH); Fura Red™/Fluo-3; Fura-2; Fura-2/BCECF; Genacryl Brilliant Red B; Genacryl Brilliant Yellow 10GF; Genacryl Pink 3G; Genacryl Yellow 5GF; GeneBlazer; (CCF2); GFP (S65T); GFP red shifted (rsGFP); GFP wild type′ non-UV excitation (wtGFP); GFP wild type, UV excitation (wtGFP); GFPuv; Gloxalic Acid; Granular blue; Haematoporphyrin; Hoechst 33258; Hoechst 33342; Hoechst 34580; HPTS; Hydroxycoumarin; Hydroxystilbamidine (FluoroGold); Hydroxytryptamine; Indo-1, high calcium; Indo-1 low calcium; Indodicarbocyanine (DiD); Indotricarbocyanine (DiR); Intrawhite Cf; JC-1; JO JO-1; JO-PRO-1; LaserPro; Laurodan; LDS 751 (DNA); LDS 751 (RNA); Leucophor PAF; Leucophor SF; Leucophor WS; Lissamine Rhodamine; Lissamine Rhodamine B; Calcein/Ethidium homodimer; LOLO-1; LO-PRO-1; Lucifer Yellow; Lyso Tracker Blue; Lyso Tracker Blue-White; Lyso Tracker Green; Lyso Tracker Red; Lyso Tracker Yellow; LysoSensor Blue; LysoSensor Green; LysoSensor Yellow/Blue; Mag Green; Magdala Red (Phloxin B); Mag-Fura Red; Mag-Fura-2; Mag-Fura-5; Mag-Indo-1; Magnesium Green; Magnesium Orange; Malachite Green; Marina Blue; I Maxilon Brilliant Flavin 10 GFF; Maxilon Brilliant Flavin 8 GFF; Merocyanin; Methoxycoumarin; Mitotracker Green FM; Mitotracker Orange; Mitotracker Red; Mitramycin; Monobromobimane; Monobromobimane (mBBr-GSH); Monochlorobimane; MPS (Methyl Green Pyronine Stilbene); NBD; NBD Amine; Nile Red; Nitrobenzoxedidole; Noradrenaline; Nuclear Fast Red; i Nuclear Yellow; Nylosan Brilliant lavin E8G; Oregon Green™; Oregon Green™ 488; Oregon Green™ 500; Oregon Green™ 514; Pacific Blue; Pararosaniline (Feulgen); PBFI; PE-Cy5; PE-Cy7; PerCP; PerCP-Cy5.5; PE-TexasRed (Red 613); Phloxin B (Magdala Red); Phorwite AR; Phorwite BKL; Phorwite Rev; Phorwite RPA; Phosphine 3R; PhotoResist; Phycoerythrin B [PE]; Phycoerythrin R [PE]; PKH26 (Sigma); PKH67; PMIA; Pontochrome Blue Black; POPO-1; POPO-3; PO-PRO-1; PO-I PRO-3; Primuline; Procion Yellow; Propidium lodid (P1); PyMPO; Pyrene; Pyronine; Pyronine B; Pyrozal Brilliant Flavin 7GF; QSY 7; Quinacrine Mustard; Resorufin; RH 414; Rhod-2; Rhodamine; Rhodamine 110; Rhodamine 123; Rhodamine 5 GLD; Rhodamine 6G; Rhodamine B; Rhodamine B 200; Rhodamine B extra; Rhodamine BB; Rhodamine BG; Rhodamine Green; Rhodamine Phallicidine; Rhodamine: Phalloidine; Rhodamine Red; Rhodamine WT; Rose Bengal; R-phycocyanine; R-phycoerythrin (PE); rsGFP; 565A; 565C; 565L; 565T; Sapphire GFP; SBFI; Serotonin; Sevron Brilliant Red 2B; Sevron Brilliant Red 4G; Sevron I Brilliant Red B; Sevron Orange; Sevron Yellow L; sgBFP™ (super glow BFP); sgGFP™ (super glow GFP); SITS (Primuline; Stilbene Isothiosulphonic Acid); SNAFL calcein; SNAFL-1; SNAFL-2; SNARF calcein; SNARF1; Sodium Green; SpectrumAqua; SpectrumGreen; SpectrumOrange; Spectrum Red; SPQ (6-methoxy-N-(3 sulfopropyl) quinolinium); Stilbene; Sulphorhodamine B and C; Sulphorhodamine Extra; SYTO 11; SYTO 12; SYTO 13; SYTO 14; SYTO 15; SYTO 16; SYTO 17; SYTO 18; SYTO 20; SYTO 21; SYTO 22; SYTO 23; SYTO 24; SYTO 25; SYTO 40; SYTO 41; SYTO 42; SYTO 43; SYTO 44; SYTO 45; SYTO 59; SYTO 60; SYTO 61; SYTO 62; SYTO 63; SYTO 64; SYTO 80; SYTO 81; SYTO 82; SYTO 83; SYTO 84; SYTO 85; SYTOX Blue; SYTOX Green; SYTOX Orange; Tetracycline; Tetramethylrhodamine (TRITC); Texas Red™; Texas Red-X™ conjugate; Thiadicarbocyanine (DiSC3); Thiazine Red R; Thiazole Orange; Thioflavin 5; Thioflavin S; Thioflavin TON; Thiolyte; Thiozole Orange; Tinopol CBS (Calcofluor White); TIER; TO-PRO-1; TO-PRO-3; TO-PRO-5; TOTO-1; TOTO-3; TriColor (PE-Cy5); TRITC TetramethylRodaminelsoThioCyanate; True Blue; True Red; Ultralite; Uranine B; Uvitex SFC; wt GFP; WW 781; X-Rhodamine; XRITC; Xylene Orange; Y66F; Y66H; Y66W; Yellow GFP; YFP; YO-PRO-1; YO-PRO 3; YOYO-1; YOYO-3; Sybr Green; Thiazole orange (interchelating dyes); semiconductor nanoparticles such as quantum dots; or caged fluorophore (which can be activated with light or other electromagnetic energy source), or a combination thereof. [0034] A modifier unit such as a radionuclide can be incorporated into or attached directly to any of the compounds described herein by halogenation. Examples of radionuclides useful in this embodiment include, but are not limited to, tritium, iodine-125, iodine-131, iodine-123, iodine-124, astatine-210, carbon-11, carbon-14, nitrogen-13, fluorine-18. In another aspect, the radionuclide can be attached to a linking group or bound by a chelating group, which is then attached to the compound directly or by means of a linker. Examples of radionuclides useful in the aspect include, but are not limited to, Tc-99m, Re-186, Ga-68, Re-188, Y-90, Sm-153, Bi-212, Cu-67, Cu-64, and Cu-62. Radiolabeling techniques such as these are routinely used in the radiopharmaceutical industry. [0035] The radiolabeled compounds are useful as imaging agents to diagnose neurological disease (e.g., a neurodegenerative disease) or a mental condition or to follow the progression or treatment of such a disease or condition in a mammal (e.g., a human). The radiolabeled compounds described herein can be conveniently used in conjunction with imaging techniques such as positron emission tomography (PET) or single photon emission computerized tomography (SPECT). [0036] Labeling can be either direct or indirect. In direct labeling, the detecting antibody (the antibody for the molecule of interest) or detecting molecule (the molecule that can be bound by an antibody to the molecule of interest) include a label. Detection of the label indicates the presence of the detecting antibody or detecting molecule, which in turn indicates the presence of the molecule of interest or of an antibody to the molecule of interest, respectively. In indirect labeling, an additional molecule or moiety is brought into contact with, or generated at the site of, the immunocomplex. For example, a signal-generating molecule or moiety such as an enzyme can be attached to or associated with the detecting antibody or detecting molecule. The signal-generating molecule can then generate a detectable signal at the site of the immunocomplex. For example, an enzyme, when supplied with suitable substrate, can produce a visible or detectable product at the site of the immunocomplex. ELISAs use this type of indirect labeling. [0037] As another example of indirect labeling, an additional molecule (which can be referred to as a binding agent) that can bind to either the molecule of interest or to the antibody (primary antibody) to the molecule of interest, such as a second antibody to the primary antibody, can be contacted with the immunocomplex. The additional molecule can have a label or signal-generating molecule or moiety. The additional molecule can be an antibody, which can thus be termed a secondary antibody. Binding of a secondary antibody to the primary antibody can form a so-called sandwich with the first (or primary) antibody and the molecule of interest. The immune complexes can be contacted with the labeled, secondary antibody under conditions effective and for a period of time sufficient to allow the formation of secondary immune complexes. The secondary immune complexes can then be generally washed to remove any non-specifically bound labeled secondary antibodies, and the remaining label in the secondary immune complexes can then be detected. The additional molecule can also be or include one of a pair of molecules or moieties that can bind to each other, such as the biotin/avadin pair. In this mode, the detecting antibody or detecting molecule should include the other member of the pair. [0038] Other modes of indirect labeling include the detection of primary immune complexes by a two-step approach. For example, a molecule (which can be referred to as a first binding agent), such as an antibody, that has binding affinity for the molecule of interest or corresponding antibody can be used to form secondary immune complexes, as described above. After washing, the secondary immune complexes can be contacted with another molecule (which can be referred to as a second binding agent) that has binding affinity for the first binding agent, again under conditions effective and for a period of time sufficient to allow the formation of immune complexes (thus forming tertiary immune complexes). The second binding agent can be linked to a detectable label or signal-generating molecule or moiety, allowing detection of the tertiary immune complexes thus formed. This system can provide for signal amplification. [0039] Immunoassays that involve the detection of as substance, such as a protein or an antibody to a specific protein, include label-free assays, protein separation methods (i.e., electrophoresis), solid support capture assays, or in vivo detection. Label-free assays are generally diagnostic means of determining the presence or absence of a specific protein, or an antibody to a specific protein, in a sample. Protein separation methods are additionally useful for evaluating physical properties of the protein, such as size or net charge. Capture assays are generally more useful for quantitatively evaluating the concentration of a specific protein, or antibody to a specific protein, in a sample. Finally, in vivo detection is useful for evaluating the spatial expression patterns of the substance, i.e., where the substance can be found in a subject, tissue or cell. [0040] Provided that the concentrations are sufficient, the molecular complexes ([Ab-Ag]n) generated by antibody-antigen interaction are visible to the naked eye, but smaller amounts may also be detected and measured due to their ability to scatter a beam of light. The formation of complexes indicates that both reactants are present, and in immunoprecipitation assays a constant concentration of a reagent antibody is used to measure specific antigen ([Ab-Ag]n), and reagent antigens are used to detect specific antibody ([Ab-Ag]n). If the reagent species is previously coated onto cells (as in hemagglutination assay) or very small particles (as in latex agglutination assay), “clumping” of the coated particles is visible at much lower concentrations. A variety of assays based on these elementary principles are in common use, including Ouchterlony immunodiffusion assay, rocket immunoelectrophoresis, and immunoturbidometric and nephelometric assays. The main limitations of such assays are restricted sensitivity (lower detection limits) in comparison to assays employing labels and, in some cases, the fact that very high concentrations of analyte can actually inhibit complex formation, necessitating safeguards that make the procedures more complex. Some of these Group 1 assays date right back to the discovery of antibodies and none of them have an actual “label” (e.g. Ag-enz). Other kinds of immunoassays that are label free depend on immunosensors, and a variety of instruments that can directly detect antibody-antigen interactions are now commercially available. Most depend on generating an evanescent wave on a sensor surface with immobilized ligand, which allows continuous monitoring of binding to the ligand. Immunosensors allow the easy investigation of kinetic interactions and, with the advent of lower-cost specialized instruments, may in the future find wide application in immunoanalysis. [0041] The use of immunoassays to detect a specific protein can involve the separation of the proteins by electophoresis. Electrophoresis is the migration of charged molecules in solution in response to an electric field. Their rate of migration depends on the strength of the field; on the net charge, size and shape of the molecules and also on the ionic strength, viscosity and temperature of the medium in which the molecules are moving. As an analytical tool, electrophoresis is simple, rapid and highly sensitive. It is used analytically to study the properties of a single charged species, and as a separation technique. [0042] Generally the sample is run in a support matrix such as paper, cellulose acetate, starch gel, agarose or polyacrylamide gel. The matrix inhibits convective mixing caused by heating and provides a record of the electrophoretic run: at the end of the run, the matrix can be stained and used for scanning, autoradiography or storage. In addition, the most commonly used support matrices—agarose and polyacrylamide—provide a means of separating molecules by size, in that they are porous gels. A porous gel may act as a sieve by retarding, or in some cases completely obstructing, the movement of large macromolecules while allowing smaller molecules to migrate freely. Because dilute agarose gels are generally more rigid and easy to handle than polyacrylamide of the same concentration, agarose is used to separate larger macromolecules such as nucleic acids, large proteins and protein complexes. Polyacrylamide, which is easy to handle and to make at higher concentrations, is used to separate most proteins and small oligonucleotides that require a small gel pore size for retardation. [0043] Proteins are amphoteric compounds; their net charge therefore is determined by the pH of the medium in which they are suspended. In a solution with a pH above its isoelectric point, a protein has a net negative charge and migrates towards the anode in an electrical field. Below its isoelectric point, the protein is positively charged and migrates towards the cathode. The net charge carried by a protein is in addition independent of its size—i.e., the charge carried per unit mass (or length, given proteins and nucleic acids are linear macromolecules) of molecule differs from protein to protein. At a given pH therefore, and under non-denaturing conditions, the electrophoretic separation of proteins is determined by both size and charge of the molecules. [0044] Sodium dodecyl sulphate (SDS) is an anionic detergent which denatures proteins by “wrapping around” the polypeptide backbone—and SDS binds to proteins fairly specifically in a mass ratio of 1.4:1. In so doing, SDS confers a negative charge to the polypeptide in proportion to its length. Further, it is usually necessary to reduce disulphide bridges in proteins (denature) before they adopt the random-coil configuration necessary for separation by size; this is done with 2-mercaptoethanol or dithiothreitol (DTT). In denaturing SDS-PAGE separations therefore, migration is determined not by intrinsic electrical charge of the polypeptide, but by molecular weight. [0045] Determination of molecular weight is done by SDS-PAGE of proteins of known molecular weight along with the protein to be characterized. A linear relationship exists between the logarithm of the molecular weight of an SDS-denatured polypeptide, or native nucleic acid, and its Rf. The Rf is calculated as the ratio of the distance migrated by the molecule to that migrated by a marker dye-front. A simple way of determining relative molecular weight by electrophoresis (Mr) is to plot a standard curve of distance migrated vs. log 10MW for known samples, and read off the log Mr of the sample after measuring distance migrated on the same gel. [0046] In two-dimensional electrophoresis, proteins are fractionated first on the basis of one physical property, and, in a second step, on the basis of another. For example, isoelectric focusing can be used for the first dimension, conveniently carried out in a tube gel, and SDS electrophoresis in a slab gel can be used for the second dimension. One example of a procedure is that of O'Farrell, P. H., High Resolution Two-dimensional Electrophoresis of Proteins, J. Biol. Chem. 250:4007-4021 (1975), herein incorporated by reference in its entirety for its teaching regarding two-dimensional electrophoresis methods. Other examples include but are not limited to, those found in Anderson, L and Anderson, N G, High resolution two-dimensional electrophoresis of human plasma proteins, Proc. Natl. Acad. Sci. 74:5421-5425 (1977), Ornstein, L., Disc electrophoresis, L. Ann. N.Y. Acad. Sci. 121:321349 (1964), each of which is herein incorporated by reference in its entirety for teachings regarding electrophoresis methods. [0047] Laemmli, U.K., Cleavage of structural proteins during the assembly of the head of bacteriophage T4, Nature 227:680 (1970), which is herein incorporated by reference in its entirety for teachings regarding electrophoresis methods, discloses a discontinuous system for resolving proteins denatured with SDS. The leading ion in the Laemmli buffer system is chloride, and the trailing ion is glycine. Accordingly, the resolving gel and the stacking gel are made up in Tris-HCl buffers (of different concentration and pH), while the tank buffer is Tris-glycine. All buffers contain 0.1% SDS. [0048] One example of an immunoassay that uses electrophoresis that is contemplated in the current methods is Western blot analysis. Western blotting or immunoblotting allows the determination of the molecular mass of a protein and the measurement of relative amounts of the protein present in different samples. Detection methods include chemiluminescence and chromagenic detection. Standard methods for Western blot analysis can be found in, for example, D. M. Bollag et al., Protein Methods (2d edition 1996) and E. Harlow & D. Lane, Antibodies, a Laboratory Manual (1988), U.S. Pat. No. 4,452,901, each of which is herein incorporated by reference in their entirety for teachings regarding Western blot methods. Generally, proteins are separated by gel electrophoresis, usually SDS-PAGE. The proteins are transferred to a sheet of special blotting paper, e.g., nitrocellulose, though other types of paper, or membranes, can be used. The proteins retain the same pattern of separation they had on the gel. The blot is incubated with a generic protein (such as milk proteins) to bind to any remaining sticky places on the nitrocellulose. An antibody is then added to the solution which is able to bind to its specific protein. [0049] The attachment of specific antibodies to specific immobilized antigens can be readily visualized by indirect enzyme immunoassay techniques, usually using a chromogenic substrate (e.g. alkaline phosphatase or horseradish peroxidase) or chemiluminescent substrates. Other possibilities for probing include the use of fluorescent or radioisotope labels (e.g., fluorescein, 125 I). Probes for the detection of antibody binding can be conjugated anti-immunoglobulins, conjugated staphylococcal Protein A (binds IgG), or probes to biotinylated primary antibodies (e.g., conjugated avidin/streptavidin). [0050] The power of the technique lies in the simultaneous detection of a specific protein by means of its antigenicity, and its molecular mass. Proteins are first separated by mass in the SDS-PAGE, then specifically detected in the immunoassay step. Thus, protein standards (ladders) can be run simultaneously in order to approximate molecular mass of the protein of interest in a heterogeneous sample. [0051] The gel shift assay or electrophoretic mobility shift assay (EMSA) can be used to detect the interactions between DNA binding proteins and their cognate DNA recognition sequences, in both a qualitative and quantitative manner. Exemplary techniques are described in Ornstein L., Disc electrophoresis—I: Background and theory, Ann. NY Acad. Sci. 121:321-349 (1964), and Matsudiara, P T and D R Burgess, SDS microslab linear gradient polyacrylamide gel electrophoresis, Anal. Biochem. 87:386-396 (1987), each of which is herein incorporated by reference in its entirety for teachings regarding gel-shift assays. [0052] In a general gel-shift assay, purified proteins or crude cell extracts can be incubated with a labeled (e.g., 32 P-radiolabeled) DNA or RNA probe, followed by separation of the complexes from the free probe through a nondenaturing polyacrylamide gel. The complexes migrate more slowly through the gel than unbound probe. Depending on the activity of the binding protein, a labeled probe can be either double-stranded or single-stranded. For the detection of DNA binding proteins such as transcription factors, either purified or partially purified proteins, or nuclear cell extracts can be used. For detection of RNA binding proteins, either purified or partially purified proteins, or nuclear or cytoplasmic cell extracts can be used. The specificity of the DNA or RNA binding protein for the putative binding site is established by competition experiments using DNA or RNA fragments or oligonucleotides containing a binding site for the protein of interest, or other unrelated sequence. The differences in the nature and intensity of the complex formed in the presence of specific and nonspecific competitor allows identification of specific interactions. Refer to Promega, Gel Shift Assay FAQ, available at <http://www.promega.com/faq/gelshfaq.html> (last visited Mar. 25, 2005), which is herein incorporated by reference in its entirety for teachings regarding gel shift methods. [0053] Gel shift methods can include using, for example, colloidal forms of COOMASSIE (Imperial Chemicals Industries, Ltd) blue stain to detect proteins in gels such as polyacrylamide electrophoresis gels. Such methods are described, for example, in Neuhoff et al., Electrophoresis 6:427-448 (1985), and Neuhoff et al., Electrophoresis 9:255-262 (1988), each of which is herein incorporated by reference in its entirety for teachings regarding gel shift methods. In addition to the conventional protein assay methods referenced above, a combination cleaning and protein staining composition is described in U.S. Pat. No. 5,424,000, herein incorporated by reference in its entirety for its teaching regarding gel shift methods. The solutions can include phosphoric, sulfuric, and nitric acids, and Acid Violet dye. [0054] Radioimmune Precipitation Assay (RIPA) is a sensitive assay using radiolabeled antigens to detect specific antibodies in serum. The antigens are allowed to react with the serum and then precipitated using a special reagent such as, for example, protein A sepharose beads. The bound radiolabeled immunoprecipitate is then commonly analyzed by gel electrophoresis. Radioimmunoprecipitation assay (RIPA) is often used as a confirmatory test for diagnosing the presence of HIV antibodies. RIPA is also referred to in the art as Farr Assay, Precipitin Assay, Radioimmune Precipitin Assay; Radioimmunoprecipitation Analysis; Radioimmunoprecipitation Analysis, and Radioimmunoprecipitation Analysis. [0055] While the above immunoassays that utilize electrophoresis to separate and detect the specific proteins of interest allow for evaluation of protein size, they are not very sensitive for evaluating protein concentration. However, also contemplated are immunoassays wherein the protein or antibody specific for the protein is bound to a solid support (e.g., tube, well, bead, or cell) to capture the antibody or protein of interest, respectively, from a sample, combined with a method of detecting the protein or antibody specific for the protein on the support. Examples of such immunoassays include Radioimmunoassay (RIA), Enzyme-Linked Immunosorbent Assay (ELISA), Flow cytometry, protein array, multiplexed bead assay, and magnetic capture. [0056] Radioimmunoassay (RIA) is a classic quantitative assay for detection of antigen-antibody reactions using a radioactively labeled substance (radioligand), either directly or indirectly, to measure the binding of the unlabeled substance to a specific antibody or other receptor system. Radioimmunoassay is used, for example, to test hormone levels in the blood without the need to use a bioassay. Non-immunogenic substances (e.g., haptens) can also be measured if coupled to larger carrier proteins (e.g., bovine gamma-globulin or human serum albumin) capable of inducing antibody formation. RIA involves mixing a radioactive antigen (because of the ease with which iodine atoms can be introduced into tyrosine residues in a protein, the radioactive isotopes 125 I or 131 I are often used) with antibody to that antigen. The antibody is generally linked to a solid support, such as a tube or beads. Unlabeled or “cold” antigen is then adding in known quantities and measuring the amount of labeled antigen displaced. Initially, the radioactive antigen is bound to the antibodies. When cold antigen is added, the two compete for antibody binding sites—and at higher concentrations of cold antigen, more binds to the antibody, displacing the radioactive variant. The bound antigens are separated from the unbound ones in solution and the radioactivity of each used to plot a binding curve. The technique is both extremely sensitive, and specific. [0057] Enzyme-Linked Immunosorbent Assay (ELISA), or more generically termed EIA (Enzyme ImmunoAssay), is an immunoassay that can detect an antibody specific for a protein. In such an assay, a detectable label bound to either an antibody-binding or antigen-binding reagent is an enzyme. When exposed to its substrate, this enzyme reacts in such a manner as to produce a chemical moiety which can be detected, for example, by spectrophotometric, fluorometric or visual means. Enzymes which can be used to detectably label reagents useful for detection include, but are not limited to, horseradish peroxidase, alkaline phosphatase, glucose oxidase, β-galactosidase, ribonuclease, urease, catalase, malate dehydrogenase, staphylococcal nuclease, asparaginase, yeast alcohol dehydrogenase, alpha.-glycerophosphate dehydrogenase, triose phosphate isomerase, glucose-6-phosphate dehydrogenase, glucoamylase and acetylcholinesterase. For descriptions of ELISA procedures, see Voller, A. et al., J. Clin. Pathol. 31:507-520 (1978); Butler, J. E., Meth. Enzymol. 73:482-523 (1981); Maggio, E. (ed.), Enzyme Immunoassay, CRC Press, Boca Raton, 1980; Butler, J. E., In: Structure of Antigens, Vol. 1 (Van Regenmortel, M., CRC Press, Boca Raton, 1992, pp. 209-259; Butler, J. E., In: van Oss, C. J. et al., (eds), Immunochemistry, Marcel Dekker, Inc., New York, 1994, pp. 759-803; Butler, J. E. (ed.), Immunochemistry of Solid-Phase Immunoassay, CRC Press, Boca Raton, 1991); Crowther, “ELISA: Theory and Practice,” In: Methods in Molecule Biology, Vol. 42, Humana Press; New Jersey, 1995; U.S. Pat. No. 4,376,110, each of which is incorporated herein by reference in its entirety and specifically for teachings regarding ELISA methods. [0058] Variations of ELISA techniques are know to those of skill in the art. In one variation, antibodies that can bind to proteins can be immobilized onto a selected surface exhibiting protein affinity, such as a well in a polystyrene microtiter plate. Then, a test composition suspected of containing a marker antigen can be added to the wells. After binding and washing to remove non-specifically bound immunocomplexes, the bound antigen can be detected. Detection can be achieved by the addition of a second antibody specific for the target protein, which is linked to a detectable label. This type of ELISA is a simple “sandwich ELISA.” Detection also can be achieved by the addition of a second antibody, followed by the addition of a third antibody that has binding affinity for the second antibody, with the third antibody being linked to a detectable label. [0059] Another variation is a competition ELISA. In competition ELISA's, test samples compete for binding with known amounts of labeled antigens or antibodies. The amount of reactive species in the sample can be determined by mixing the sample with the known labeled species before or during incubation with coated wells. The presence of reactive species in the sample acts to reduce the amount of labeled species available for binding to the well and thus reduces the ultimate signal. [0060] Regardless of the format employed, ELISAs have certain features in common, such as coating, incubating or binding, washing to remove non-specifically bound species, and detecting the bound immunocomplexes. Antigen or antibodies can be linked to a solid support, such as in the form of plate, beads, dipstick, membrane or column matrix, and the sample to be analyzed applied to the immobilized antigen or antibody. In coating a plate with either antigen or antibody, one will generally incubate the wells of the plate with a solution of the antigen or antibody, either overnight or for a specified period of hours. The wells of the plate can then be washed to remove incompletely adsorbed material. Any remaining available surfaces of the wells can then be “coated” with a nonspecific protein that is antigenically neutral with regard to the test antisera. These include bovine serum albumin (BSA), casein and solutions of milk powder. The coating allows for blocking of nonspecific adsorption sites on the immobilizing surface and thus reduces the background caused by nonspecific binding of antisera onto the surface. [0061] In ELISAs, a secondary or tertiary detection means rather than a direct procedure can also be used. Thus, after binding of a protein or antibody to the well, coating with a non-reactive material to reduce background, and washing to remove unbound material, the immobilizing surface is contacted with the control clinical or biological sample to be tested under conditions effective to allow immunocomplex (antigen/antibody) formation. Detection of the immunocomplex then requires a labeled secondary binding agent or a secondary binding agent in conjunction with a labeled third binding agent. [0062] “Under conditions effective to allow immunocomplex (antigen/antibody) formation” means that the conditions include diluting the antigens and antibodies with solutions such as BSA, bovine gamma globulin (BGG) and phosphate buffered saline (PBS)/Tween so as to reduce non-specific binding and to promote a reasonable signal to noise ratio. [0063] The suitable conditions also mean that the incubation is at a temperature and for a period of time sufficient to allow effective binding. Incubation steps can typically be from about 1 minute to twelve hours, at temperatures of about 20° to 30° C., or can be incubated overnight at about 0° C. to about 10° C. [0064] Following all incubation steps in an ELISA, the contacted surface can be washed so as to remove non-complexed material. A washing procedure can include washing with a solution such as PBS/Tween or borate buffer. Following the formation of specific immunocomplexes between the test sample and the originally bound material, and subsequent washing, the occurrence of even minute amounts of immunocomplexes can be determined. [0065] To provide a detecting means, the second or third antibody can have an associated label to allow detection, as described above. This can be an enzyme that can generate color development upon incubating with an appropriate chromogenic substrate. Thus, for example, one can contact and incubate the first or second immunocomplex with a labeled antibody for a period of time and under conditions that favor the development of further immunocomplex formation (e.g., incubation for 2 hours at room temperature in a PBS-containing solution such as PBS-Tween). [0066] After incubation with the labeled antibody, and subsequent to washing to remove unbound material, the amount of label can be quantified, e.g., by incubation with a chromogenic substrate such as urea and bromocresol purple or 2,2′-azido-di-(3-ethyl-benzthiazoline-6-sulfonic acid [ABTS] and H 2 O 2 , in the case of peroxidase as the enzyme label. Quantitation can then be achieved by measuring the degree of color generation, e.g., using a visible spectra spectrophotometer. [0067] Protein arrays are solid-phase ligand binding assay systems using immobilized proteins on surfaces which include glass, membranes, microtiter wells, mass spectrometer plates, and beads or other particles. The assays are highly parallel (multiplexed) and often miniaturized (microarrays, protein chips). Their advantages include being rapid and automatable, capable of high sensitivity, economical on reagents, and giving an abundance of data for a single experiment. Bioinformatics support is important; the data handling demands sophisticated software and data comparison analysis. However, the software can be adapted from that used for DNA arrays, as can much of the hardware and detection systems. [0068] One of the chief formats is the capture array, in which ligand-binding reagents, which are usually antibodies but can also be alternative protein scaffolds, peptides or nucleic acid aptamers, are used to detect target molecules in mixtures such as plasma or tissue extracts. In diagnostics, capture arrays can be used to carry out multiple immunoassays in parallel, both testing for several analytes in individual sera for example and testing many serum samples simultaneously. In proteomics, capture arrays are used to quantitate and compare the levels of proteins in different samples in health and disease, i.e. protein expression profiling. Proteins other than specific ligand binders are used in the array format for in vitro functional interaction screens such as protein-protein, protein-DNA, protein-drug, receptor-ligand, enzyme-substrate, etc. The capture reagents themselves are selected and screened against many proteins, which can also be done in a multiplex array format against multiple protein targets. [0069] For construction of arrays, sources of proteins include cell-based expression systems for recombinant proteins, purification from natural sources, production in vitro by cell-free translation systems, and synthetic methods for peptides. Many of these methods can be automated for high throughput production. For capture arrays and protein function analysis, it is important that proteins should be correctly folded and functional; this is not always the case, e.g. where recombinant proteins are extracted from bacteria under denaturing conditions. Nevertheless, arrays of denatured proteins are useful in screening antibodies for cross-reactivity, identifying autoantibodies and selecting ligand binding proteins. [0070] Protein arrays have been designed as a miniaturization of familiar immunoassay methods such as ELISA and dot blotting, often utilizing fluorescent readout, and facilitated by robotics and high throughput detection systems to enable multiple assays to be carried out in parallel. Commonly used physical supports include glass slides, silicon, microwells, nitrocellulose or PVDF membranes, and magnetic and other microbeads. While microdrops of protein delivered onto planar surfaces are the most familiar format, alternative architectures include CD centrifugation devices based on developments in microfluidics (Gyros, Monmouth Junction, N.J.) and specialised chip designs, such as engineered microchannels in a plate (e.g., The Living Chip™, Biotrove, Woburn, Mass.) and tiny 3D posts on a silicon surface (Zyomyx, Hayward Calif.). Particles in suspension can also be used as the basis of arrays, providing they are coded for identification; systems include colour coding for microbeads (Luminex, Austin, Tex.; Bio-Rad Laboratories) and semiconductor nanocrystals (e.g., QDots™, Quantum Dot, Hayward, Calif.), and barcoding for beads (UltraPlex™, SmartBead Technologies Ltd, Babraham, Cambridge, UK) and multimetal microrods (e.g., Nanobarcodes™ particles, Nanoplex Technologies, Mountain View, Calif.). Beads can also be assembled into planar arrays on semiconductor chips (LEAPS technology, BioArray Solutions, Warren, N.J.). [0071] Immobilization of proteins involves both the coupling reagent and the nature of the surface being coupled to. A good protein array support surface is chemically stable before and after the coupling procedures, allows good spot morphology, displays minimal nonspecific binding, does not contribute a background in detection systems, and is compatible with different detection systems. The immobilization method used are reproducible, applicable to proteins of different properties (size, hydrophilic, hydrophobic), amenable to high throughput and automation, and compatible with retention of fully functional protein activity. Orientation of the surface-bound protein is recognized as an important factor in presenting it to ligand or substrate in an active state; for capture arrays the most efficient binding results are obtained with orientated capture reagents, which generally require site-specific labeling of the protein. [0072] Both covalent and noncovalent methods of protein immobilization are used and have various pros and cons. Passive adsorption to surfaces is methodologically simple, but allows little quantitative or orientational control; it may or may not alter the functional properties of the protein, and reproducibility and efficiency are variable. Covalent coupling methods provide a stable linkage, can be applied to a range of proteins and have good reproducibility; however, orientation may be variable, chemical derivatization may alter the function of the protein and requires a stable interactive surface. Biological capture methods utilizing a tag on the protein provide a stable linkage and bind the protein specifically and in reproducible orientation, but the biological reagent must first be immobilized adequately and the array may require special handling and have variable stability. [0073] Several immobilization chemistries and tags have been described for fabrication of protein arrays. Substrates for covalent attachment include glass slides coated with amino- or aldehyde-containing silane reagents. In the Versalinx™ system (Prolinx, Bothell, Wash.) reversible covalent coupling is achieved by interaction between the protein derivatised with phenyldiboronic acid, and salicylhydroxamic acid immobilized on the support surface. This also has low background binding and low intrinsic fluorescence and allows the immobilized proteins to retain function. Noncovalent binding of unmodified protein occurs within porous structures such as HydroGel™ (PerkinElmer, Wellesley, Mass.), based on a 3-dimensional polyacrylamide gel; this substrate is reported to give a particularly low background on glass microarrays, with a high capacity and retention of protein function. Widely used biological coupling methods are through biotin/streptavidin or hexahistidine/Ni interactions, having modified the protein appropriately. Biotin may be conjugated to a poly-lysine backbone immobilised on a surface such as titanium dioxide (Zyomyx) or tantalum pentoxide (Zeptosens, Witterswil, Switzerland). [0074] Array fabrication methods include robotic contact printing, ink-jetting, piezoelectric spotting and photolithography. A number of commercial arrayers are available [e.g. Packard Biosciences] as well as manual equipment [V & P Scientific]. Bacterial colonies can be robotically gridded onto PVDF membranes for induction of protein expression in situ. [0075] At the limit of spot size and density are nanoarrays, with spots on the nanometer spatial scale, enabling thousands of reactions to be performed on a single chip less than 1 mm square. BioForce Laboratories have developed nanoarrays with 1521 protein spots in 85 sq microns, equivalent to 25 million spots per sq cm, at the limit for optical detection; their readout methods are fluorescence and atomic force microscopy (AFM). [0076] Fluorescence labeling and detection methods are widely used. The same instrumentation as used for reading DNA microarrays is applicable to protein arrays. For differential display, capture (e.g., antibody) arrays can be probed with fluorescently labeled proteins from two different cell states, in which cell lysates are directly conjugated with different fluorophores (e.g. Cy-3, Cy-5) and mixed, such that the color acts as a readout for changes in target abundance. Fluorescent readout sensitivity can be amplified 10-100 fold by tyramide signal amplification (TSA) (PerkinElmer Lifesciences). Planar waveguide technology (Zeptosens) enables ultrasensitive fluorescence detection, with the additional advantage of no intervening washing procedures. High sensitivity can also be achieved with suspension beads and particles, using phycoerythrin as label (Luminex) or the properties of semiconductor nanocrystals (Quantum Dot). A number of novel alternative readouts have been developed, especially in the commercial biotech arena. These include adaptations of surface plasmon resonance (HTS Biosystems, Intrinsic Bioprobes, Tempe, Az.), rolling circle DNA amplification (Molecular Staging, New Haven Conn.), mass spectrometry (Intrinsic Bioprobes; Ciphergen, Fremont, Calif.), resonance light scattering (Genicon Sciences, San Diego, Calif.) and atomic force microscopy [BioForce Laboratories]. [0077] Capture arrays form the basis of diagnostic chips and arrays for expression profiling. They employ high affinity capture reagents, such as conventional antibodies, single domains, engineered scaffolds, peptides or nucleic acid aptamers, to bind and detect specific target ligands in high throughput manner. [0078] Antibody arrays have the required properties of specificity and acceptable background, and some are available commercially (BD Biosciences, San Jose, Calif.; Clontech, Mountain View, Calif.; BioRad; Sigma, St. Louis, Mo.). Antibodies for capture arrays are made either by conventional immunization (polyclonal sera and hybridomas), or as recombinant fragments, usually expressed in E. coli , after selection from phage or ribosome display libraries (Cambridge Antibody Technology, Cambridge, UK; BioInvent, Lund, Sweden; Affitech, Walnut Creek, Calif.; Biosite, San Diego, Calif.). In addition to the conventional antibodies, Fab and scFv fragments, single V-domains from camelids or engineered human equivalents (Domantis, Waltham, Mass.) may also be useful in arrays. [0079] The term “scaffold” refers to ligand-binding domains of proteins, which are engineered into multiple variants capable of binding diverse target molecules with antibody-like properties of specificity and affinity. The variants can be produced in a genetic library format and selected against individual targets by phage, bacterial or ribosome display. Such ligand-binding scaffolds or frameworks include ‘Affibodies’ based on Staph. aureus protein A (Affibody, Bromma, Sweden), Trinectins' based on fibronectins (Phylos, Lexington, Mass.) and ‘Anticalins’ based on the lipocalin structure (Pieris Proteolab, Freising-Weihenstephan, Germany). These can be used on capture arrays in a similar fashion to antibodies and may have advantages of robustness and ease of production. [0080] Nonprotein capture molecules, notably the single-stranded nucleic acid aptamers which bind protein ligands with high specificity and affinity, are also used in arrays (SomaLogic, Boulder, Colo.). Aptamers are selected from libraries of oligonucleotides by the Selex™ procedure and their interaction with protein can be enhanced by covalent attachment, through incorporation of brominated deoxyuridine and UV-activated crosslinking (photoaptamers). Photocrosslinking to ligand reduces the crossreactivity of aptamers due to the specific steric requirements. Aptamers have the advantages of ease of production by automated oligonucleotide synthesis and the stability and robustness of DNA; on photoaptamer arrays, universal fluorescent protein stains can be used to detect binding. [0081] Protein analytes binding to antibody arrays may be detected directly or via a secondary antibody in a sandwich assay. Direct labelling is used for comparison of different samples with different colours. Where pairs of antibodies directed at the same protein ligand are available, sandwich immunoassays provide high specificity and sensitivity and are therefore the method of choice for low abundance proteins such as cytokines; they also give the possibility of detection of protein modifications. Label-free detection methods, including mass spectrometry, surface plasmon resonance and atomic force microscopy, avoid alteration of ligand. What is required from any method is optimal sensitivity and specificity, with low background to give high signal to noise. Since analyte concentrations cover a wide range, sensitivity has to be tailored appropriately; serial dilution of the sample or use of antibodies of different affinities are solutions to this problem. Proteins of interest are frequently those in low concentration in body fluids and extracts, requiring detection in the pg range or lower, such as cytokines or the low expression products in cells. [0082] An alternative to an array of capture molecules is one made through ‘molecular imprinting’ technology, in which peptides (e.g., from the C-terminal regions of proteins) are used as templates to generate structurally complementary, sequence-specific cavities in a polymerizable matrix; the cavities can then specifically capture (denatured) proteins that have the appropriate primary amino acid sequence (ProteinPrint™, Aspira Biosystems, Burlingame, Calif.). [0083] Another methodology which can be used diagnostically and in expression profiling is the ProteinChip® array (Ciphergen, Fremont, Calif.), in which solid phase chromatographic surfaces bind proteins with similar characteristics of charge or hydrophobicity from mixtures such as plasma or tumour extracts, and SELDI-TOF mass spectrometry is used to detection the retained proteins. [0084] Large-scale functional chips have been constructed by immobilizing large numbers of purified proteins and used to assay a wide range of biochemical functions, such as protein interactions with other proteins, drug-target interactions, enzyme-substrates, etc. Generally they require an expression library, cloned into E. coli , yeast or similar from which the expressed proteins are then purified, e.g. via a His tag, and immobilized. Cell free protein transcription/translation is a viable alternative for synthesis of proteins which do not express well in bacterial or other in vivo systems. [0085] For detecting protein-protein interactions, protein arrays can be in vitro alternatives to the cell-based yeast two-hybrid system and may be useful where the latter is deficient, such as interactions involving secreted proteins or proteins with disulphide bridges. High-throughput analysis of biochemical activities on arrays has been described for yeast protein kinases and for various functions (protein-protein and protein-lipid interactions) of the yeast proteome, where a large proportion of all yeast open-reading frames was expressed and immobilized on a microarray. Large-scale ‘proteome chips’ promise to be very useful in identification of functional interactions, drug screening, etc. (Proteometrix, Branford, Conn.). [0086] As a two-dimensional display of individual elements, a protein array can be used to screen phage or ribosome display libraries, in order to select specific binding partners, including antibodies, synthetic scaffolds, peptides and aptamers. In this way, ‘library against library’ screening can be carried out. Screening of drug candidates in combinatorial chemical libraries against an array of protein targets identified from genome projects is another application of the approach. [0087] A multiplexed bead assay, such as, for example, the BD™ Cytometric Bead Array, is a series of spectrally discrete particles that can be used to capture and quantitate soluble analytes. The analyte is then measured by detection of a fluorescence-based emission and flow cytometric analysis. Multiplexed bead assay generates data that is comparable to ELISA based assays, but in a “multiplexed” or simultaneous fashion. Concentration of unknowns is calculated for the cytometric bead array as with any sandwich format assay, i.e. through the use of known standards and plotting unknowns against a standard curve. Further, multiplexed bead assay allows quantification of soluble analytes in samples never previously considered due to sample volume limitations. In addition to the quantitative data, powerful visual images can be generated revealing unique profiles or signatures that provide the user with additional information at a glance. [0088] In some embodiments, the selenoprotein can also be detected indirectly by assaying for its enzymatic activity. This generally involves the use of a colorimetric assay using an enzymatic substrate of the selenoprotein. For example, glutathione peroxidase (GPx) can be detected using a colorimetric assay kit, such as the Sigma-Aldrich Glutathione Peroxidase Cellular Activity Assay Kit (Sigma-Aldrich, St. Louis, Mo., USA). In this case, GPx converts reduced glutathione (GSH) to oxidized glutathione (GSSG) while reducing lipid hydroperoxides to their corresponding alcohols or free hydrogen peroxide to water. The generated GSSG is then reduced to GSH with consumption of NADPH by glutathione reductase (GR). The decrease of NADPH (easily measured at 340 nm) is therefore proportional to GPx activity. Colorimetric assays are available or can be developed for other selenoproteins. [0089] The disclosed methods are disclosed for use with any mycobacterium . In some cases, the mycobacterium is a slow growing mycobacterium . In some embodiments, the mycobacterium is selected from the group consisting of a Mycobacterium tuberculosis complex, a Mycobacterium avium complex (MAC), a Mycobacterium gordonae clade, a Mycobacterium kansasii clade, a Mycobacterium nonchromogenicum/terrae clade, a Mycolactone-producing mycobacteria, and a Mycobacterium simiae clade. In some embodiments, the mycobacterium is selected from the group consisting of M. bohemicum, M. botniense, M. branderi, M. celatum, M. chimaera, M. conspicuum, M. cookii, M. doricum, M. farcinogenes, M. haemophilum, M. heckeshornense, M. intracellulare, M. lacus, M. leprae, M. lepraemurium, M. lepromatosis, M. malmoense, M marinum, M. monacense, M. montefiorense, M. murale, M. nebraskense, M. saskatchewanense, M. scrofulaceum, M. shimoidei, M. szulgai, M. tusciae, M. xenopi, and M. yongonense. [0090] The Mycobacterium genus comprises more than 120 different species and is distributed worldwide. Among them are pathogenic species which can cause serious diseases in humans and animals. For example tuberculosis is caused by the Mycobacterium tuberculosis (TB) complex (i.e. M. tuberculosis, M. africanum, M. bovis, M. canettii, M. microti, M. caprae, M. orygis , and M. pinnipedii ). The classic Hansen's strain of leprosy is caused by Mycobacterium leprae. [0091] Nontuberculous Mycobacteria (NTM) refers to all the other species in the family of mycobacteria that may cause disease. Every year in the United States approximately two people per 100,000 population develop mycobacterioses caused by these lesser-known “cousins” of TB and leprosy. N™ produces the following major clinical disease syndromes: chronic bronchopulmonary disease, cervical or other lymphadenitis, skin and soft tissue disease, skeletal infection, disseminated infection, and catheter-related infections. Clinical features are dependent on the organism and the site of infection, but are usually chronic and have a progressive clinical course. Being classical opportunists, NTM predominantly infect patients already suffering from pulmonary diseases or immunodeficiency (e.g., HIV-infection) or other chronic antecedent illness. The number of mycobacterioses is increasing among immunocompetent person. Furthermore, NTM infections are emerging in previously unrecognized settings, with new clinical manifestations. [0092] Most infections appear to be acquired by ingestion, aspiration, or inoculation of the organisms from these natural sources; however the specific source of individual infections is usually not identified. No evidence of person-to-person transmission has been reported. Tap water is considered the major reservoir for the most common human NTMs. Species from tap water include M. gordonae, M. kansasii, M. xenopi, M. simiae, M. avium complex, and rapidly-growing Mycobacterium , especially M. mucogenicum. M kansasii, M. xenopi , and M. simiae are recovered almost exclusively from municipal water source [0093] Mycobacterium avium subspecies paratuberculosis (MAP) causes a chronic disease of the intestines in dairy cows and a wide range of other animals, including nonhuman primates, called Johne's (“Yo-knee's”) disease. At least 35% of cattle in USA are infected with MAP. MAP has also been consistently identified in humans with Crohn's disease. The research investigating the presence of MAP in patients with Crohn's disease has often identified MAP in the “negative” ulcerative colitis controls as well, suggesting that ulcerative colitis is also caused by MAP. [0094] Recent findings have also suggested that MAP infection could act as risk factor in favoring multiple sclerosis (MS) progression. [0095] The disclosed method can be used to predict the presence of a mycobacterium to diagnose a disease caused by a mycobacterium . In cases where a disease or disorder is a risk factor for mycobacterial infection, the disclosed methods can be used to make this determination. In some embodiments, the disclosed method can be used to distinguish a mycobacterial related bowel condition from a non-mycobacterial related bowel condition in a patient exhibiting symptoms of a bowel condition. In a specific example, the mycobacterial related bowel condition is inflammatory bowel disease (IBD). In an even more specific example, the bowel condition is Crohn's disease or ulcerative colitis. A patient exhibiting symptoms of a bowel condition typically will exhibit one or more of the following symptoms: abdominal pain, vomiting, diarrhea, rectal bleeding, severe internal cramps/muscle spasms in the region of the pelvis, weight loss and various associated complaints or diseases like arthritis, pyoderma gangrenosum, porridge-like stool, and primary sclerosing cholangitis. [0096] In some embodiments, the method further comprises assaying the sample to directly detect and confirm the presence of the mycobacterial infection if infection is predicted. For example, mycobacterial infection can be detected by culturing the sample in a mycobacterial culture medium (e.g., BACTEC 13A media), and then measuring a time to growth detection. [0097] In some cases, the mycobacterium is detected by a polymerase chain reaction (PCR) method. For example, PCR methods and primers for detecting the presence of Mycobacterium avium subspecies paratuberculosis (MAP) in a sample is described in U.S. Pat. No. 7,488,580 to Naser, which is incorporated by reference in its entirety for the teaching of these methods and primers. [0098] Compositions and method for detecting microbacterial organisms, including MAP, using magnetic relaxation nanosensor (hMRS) adapted to detect a target nucleic acid analyte, are disclosed in U.S. 2014/0220565 by Naser et al., which is incorporated by reference in its entirety for the teaching of these methods and nanosensors. [0099] Upon determining that the bowel condition is a mycobacterial related bowel condition, a therapeutically effective amount of an antibiotic composition can be administered to the patient. Mycobacterial infections are notoriously difficult to treat. The organisms are hardy due to their cell wall, which is neither truly Gram negative nor positive. In addition, they are naturally resistant to a number of antibiotics that disrupt cell-wall biosynthesis, such aspenicillin. Due to their unique cell wall, they can survive long exposure to acids, alkalis, detergents, oxidative bursts, lysis by complement, and many antibiotics. Examples of antibiotics that can in some embodiments be used to treat a mycobacterial infection, include, but are not limited to, metronidazole, ciprofloxacin, rifaximin, rifabutin, clarithromycin, and metronidazole/ciprofloxacin combination, vancomycin, azathioprine, infliximab, tobramycin, or combinations thereof. Most mycobacteria are susceptible to the antibiotics clarithromycin and rifamycin, but antibiotic-resistant strains have emerged. [0100] A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims. EXAMPLES Example 1 Oxidative Stress Due to Mycobacterium avium Subspecies Paratuberculosis (MAP) Infection Upregulates Selenium-Dependent GPx Activity [0101] Methods [0102] Bovine Samples [0103] Sera samples from healthy and MAP infected cattle were obtained. Bovine samples were confirmed for MAP infection using the IDEXX Mycobacterium paratuberculosis ( M. pt .) Antibody Test Kit (IDEXX Laboratories, Westbrook, Me., USA) following manufacturer instructions. A S/P less than or equal to 0.60 was considered negative and a S/P greater than or equal to 0.70 was considered positive. Sera from 21 MAP infected cattle and 21 healthy cattle were then included in this study. [0104] Human Samples [0105] Human blood samples were collected in two separate sets where each subject provided three 6.0-ml K2-EDTA tubes. All clinical samples were collected following University of Central of Florida-Institutional Review Board approval number IRB00001138. A total of 27 human blood samples were collected from CD patients along with 27 samples of their healthy biological family members (parents or siblings), those samples were collected at the University of Florida (UF). An additional randomized 100 blood samples used in earlier studies were also included. Clinical samples were collected blindly with no prior knowledge of MAP diagnosis or other health conditions. Buffy coat preparations and plasma samples were separated and stored at −20° C. [0106] DNA extraction for PCR analysis was performed on purified buffy coat samples. Each sample was re-suspended in 100 μL of TE buffer and then incubated at 100° C. for 30 min. The re-suspended solution was then placed in an ice bath for 15 min, after which it was centrifuged for 10 min at 4° C. at 12,000 rpm (18,500 g). After centrifugation, the supernatant was extracted in 200 μL of phenol/chloroform/isoamyl alcohol (1:1:24 v/v; Acros Organics, Morris Plains, N.J., USA) was added. The solution was mixed and centrifuged for 5 min at 4° C. at 12,000 rpm (18,500 g). The pellet, containing the nucleic acid, was then washed, dried, and re-suspended in 50 μL of sterile water [Cossu A, et al. Clin Immunol. 2011 141(1):49-57]. [0107] Detection of MAP DNA using nested PCR (nPCR) was based on the MAP-specific IS900 derived oligonucleotide primers [Cossu A, et al. Clin Immunol. 2011 141(1):49-57]. As shown in Table 1, P90 and P91 primers were used for the amplification of 398 bp in the first used to amplify a 298 bp internal sequence. Each primary PCR reaction used 10 μL of DNA template and 40 μL of PCR buffer, which consists of 5 mM MgCl2, 0.2 mM dNTP, 2 μM primers, and 2.5 U Platinum Taq polymerase (Invitrogen, Carlsbad, Calif., USA) or 1 U TFL DNA polymerase (Promega, Madison, Wis., USA). Each secondary round of PCR used the same ingredients, except different primers were used and 5 μL of the product of the primary round was used instead of the DNA template. Negative controls for the PCR were prepared in which sterile water or TE buffer was added instead of the DNA template (in the primary amplification) or the primary product (in the secondary amplification). These negatives were prepared in parallel with the samples. Positive controls were also prepared using MAP DNA from strain ATCC 43015. The amplification product size was assessed on 2% agarose gel. [0000] TABLE 1 Primers and amplification conditions used for PCR Product Primer Oligonucleotide sequence (5′-3′) Amplification conditions size (bp) P90, GTTCGGGGCCGTCGCTTAGG 95° C. for 5 min, then 34 398 P91 (SEQ ID NO: 1), cycles of 95° C. for 1 min, GAGGTCGATCGCCCACGTGA 58° C. for 1.5 min, 72° C. (SEQ ID NO: 2) for 1.5 min. Final extension of 10 min at 72° C. AV1, ATGTGGTTGCTGTGTTGGATGG 95° C. for 5 min, then 34 298 AV2 (SEQ ID NO: 3), cycles of 95° C. for 1 min, CCGCCGCAATCAACTCCAG 58° C. for 1.5 min, 72° C. (SEQ ID NO: 4) for 1.5 min. Final extension of 10 min at 72° C. [0108] Selenium-Dependent GPx Activity Measurement [0109] Glutathione peroxidase works by reducing peroxides by oxidizing glutathione. The glutathione is then restored for further cycles of catalysis ( FIG. 1 ). The rate-limiting step of this reaction is that in which the oxidized glutathione used to reduce the peroxide is restored via the oxidation of NADPH. NADPH absorbs at 340 nm. The selenium-dependent GPx activity was measured by using the Sigma-Aldrich GPx Cellular Activity Assay Kit (Sigma-Aldrich, St. Louis, Mo., USA) following manufacturer instructions. [0110] Statistical Analysis [0111] Samples were analyzed for significance using unpaired, two-tailed t tests. SigmaPlot software was used. P values of less than 0.05 were considered significant. [0112] Results [0113] MAP Prevalence in Human Samples [0114] nPCR was performed on DNA extracts isolated from all human blood samples in order to analyze for the presence of MAP-specific IS900 gene according to Naser et al. protocol [Naser S A, et al. Gut Pathog. 2013 5(1):14]. The overall prevalence of MAP among 154 human blood samples was 32%. MAP was positive in the blood of 40% of CD patients compared to 29.9% in non-CD patients. Specifically MAP was also positive in 11/27 (40%) of CD patients and in 2/27 (7%) in healthy biological family members. Interestingly, 33% (7 out of 21) of patients with type II diabetes and 44% (7 out of 16) pre-diabetic patients were also MAP positive. Patients were considered to be pre-diabetic if they had a fasting blood sugar level between 100 and 125 mg/dl, if the two-hour glucose levels was between 140 and 199 mg/dl in an oral glucose tolerance test, or if they had a glycated hemoglobin (A1C) level between 5.7 and 6.4. FIG. 2 illustrates the detection of MAP IS900 gene on 2% agarose gel following nPCR analysis of 100 randomized human blood samples (lanes 1-100). [0115] Selenium-Dependent GPx Levels were Elevated in MAP Infected Bovine Samples [0116] Bovine sera were confirmed for presence of anti-MAP IgG. Consequently, a total of 21 cattle sera samples from animals diagnosed with Johne's disease (MAP positive) and 21 sera from healthy cattle (MAP negative) were selected for the study. All 42 sera were analyzed for of GPx activity. The average level of GPx was 0.46907±0.28 units/ml in healthy cattle sera control compared to 1.590±0.65 units/ml in sera from cows infected with MAP, where a unit was defined as one mmol/minute. The MAP positive samples had a significantly higher activity level, with a difference in means of 1.122 (95% confidence interval 0.810-1.435; P<0.01) (Table 2). FIG. 3 a shows a scatter plot of selenium-dependent GPx activity for MAP negative and MAP positive samples. [0000] TABLE 2 GPx enzyme average activity and MAP presence in bovine and human blood samples Average Number of MAP Average GPx GPx activity samples/total Source diagnosis activity (units/ml) (units/ml) P value 21/42 Bovine Negative 0.469 ± 0.28 <0.01 21/42 Bovine Positive 1.590 ± 0.65 105/154 Human Negative  0.452 ± 0.176 <0.01  49/154 Human Positive 0.693 ± 0.30 16/27 CD Negative  0.389 ± 0.213 <0.05 patients 11/27 CD Positive 0.7593 ± 0.537 patients [0117] Selenium-Dependent GPx Activity was Elevated in MAP Infected Humans Among Crohn's Patients and their Healthy Relatives [0118] The average level of GPx activity was 0.80941±0.521 units/ml in the MAP positive samples, while the average enzyme activity in MAP negative samples was found to be 0.42367±0.229 units/ml. This result reveals that MAP infection has a significant influence on GPx activity, with a difference in means of 0.387 (95% confidence interval 0.182-0.592; P<0.01) ( FIG. 3 b ). [0119] The Difference Between Selenium-Dependent GPx Activity in Crohn's Disease and in Healthy Individuals was not Significant [0120] In order to confirm that the elevation of GPx activity level was due to MAP infection alone, and not due to CD status, the average of GPx activity was measured in healthy individuals and CD patients separately. The average GPx activity was found to be 0.54±0.414 units/ml and 0.493±0.301 units/ml in CD and healthy patients respectively. While the mean GPx enzymatic activity in CD patients was higher by 0.0469, results showed that there was no significant difference between both groups (95% confidence interval −0.245 to 0.151; P=0.636) ( FIG. 3 c ). The gender ratio and age distribution between the two groups was comparable between the two groups (Table 3). [0000] TABLE 3 Demographics of Crohn's patients and healthy relatives Group Age range Average age Gender ratio (M/F) Relatives 12-65 45 9/18 Crohn's 16-56 32 8/19 [0121] Selenium-Dependent GPx Activity was Elevated in MAP Infected Crohn's Patients [0122] As mentioned earlier, out of 27 CD patients, a total of 11 were tested as MAP positive, while 16 were MAP negative. The average GPx activity in CD patients who had the MAP infection was 0.7593±0.537 units/ml, while the GPx activity was found to be 0.389±0.213 units/ml in CD patients without MAP infection. The difference in means was 0.37 (95% confidence interval 0.07-0.675; P=0.019). (P=0.019) ( FIG. 3 d ). Furthermore only 2 of the 27 healthy relatives used as controls, or 7.4%, were infected with MAP. [0123] Selenium-Dependent GPx Activity was Elevated Among MAP Infected Humans in Randomized Field Study [0124] Among randomized blood samples from 100 subjects, 36 were determined to be MAP positive as shown in FIG. 2 . The average of GPx activity level in 36 MAP positive clinical samples was 0.6510±00.1665 units/ml compared 0.4702±0.1299 in 64 MAP negative clinical samples (P<0.01) (Table 2). The GPx activity in each clinical sample is illustrated in FIG. 3 e . The difference in GPx activity was further examined according to disease diagnosis, but there was no significant difference in MAP negative clinical samples between healthy controls and subjects with diseases. Disease states, including type 2 diabetes and pre-diabetes, were not found to have a significant impact on GPx activity. It is notable, however, that in all disease states MAP positive individuals still have higher enzymatic activity than MAP negative individuals ( FIG. 4 ). CONCLUSION [0125] The GPx enzymatic activity of selenium dependent GPx was significantly higher in both bovine and human serum samples infected with MAP. The consistent correlation between MAP infection and GPx activity may be used to predict MAP infection status. The presence of this bacterium causes systemic inflammation and oxidative stress, which on the long-term may cause disruptions in insulin signaling and have a deleterious effect on insulin sensitivity. Via this process MAP infection could be involved in the pathophysiology of insulin resistance and in the elevation of oxidative stress level in CD patients who are infected with MAP. [0126] Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of skill in the art to which the disclosed invention belongs. Publications cited herein and the materials for which they are cited are specifically incorporated by reference. [0127] Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims.

Compositions and methods for predicting the presence of a mycobacterial infection in a subject are provided. In some embodiments, the method further comprises assaying the sample to directly detect the presence of the mycobacterial infection if infection is predicted. However, as this is a time-consuming and expensive process, the disclosed methods can be used to predict the presence of the mycobacterium prior to confirmation by direct detection, thereby saving time and money. The disclosed method involves assaying a biological sample from the subject for detection of selenium, wherein the presence of selenium in the sample is an indication of mycobacterium in the sample. Once a mycobacterium is predicated, and optionally confirmed by direct detection, the method can further comprising treating the subject with a therapeutically effective amount of an antibiotic.

FIELD OF THE INVENTION [0001] The present invention relates to a surgical guide preparation tool for placing a dentistry implant at a predetermined position, and a method for preparing a surgical guide. BACKGROUND INFORMATION [0002] In recent years, dentistry treatments to form a denture by embedding an implant (artificial tooth root) in a tooth deficient portion have been performed. In such treatments, insertion holes for implant are drilled at tooth deficient portions by use of a drill attached to a drilling apparatus such as a handpiece, and at this time, a surgical guide is usually employed to drill a hole in order to guide the drill so that the hole for implant would be formed at a predetermined position and in a predetermined direction. [0003] Into this surgical guide, a metallic guide ring (guide tube) is fitted to guide the drill to the surgical guide supported by jawbone, etc. [0004] When the guide ring is employed to guide the drill for drilling a hole, it is required that adequate bone quantity is confirmed at the portion where the hole for implant is formed and no nerves or blood vessels are present at this portion. [0005] In order to satisfy such requirements, in usual, a CT scanning is conducted by use of an X-ray CT apparatus (Computed Tomography) in such a state that a surgical guide (a stent for diagnosis) is attached to the teeth of patient, and the examination results by the CT, scanned image is used to determine the insertion direction of the implant. [0006] Various methods have been proposed as a method for determining the insertion direction of implant. [0007] For example, European Patent No. 1043960 describes a method for processing a hole for implant by a numerically controlled boring machine which moves in relation with an X-ray CT apparatus. [0008] In this method, since the numerically controlled boring machine is additionally employed, the entire machine becomes large, the operation requires skillfulness and costs become high. [0009] Further, as described in JP-A-2006-141561, a method has been proposed in that the CT scanned image of a jaw bone area of tooth deficient portion is printed, the tooth deficient portion is cut out from the print, the cutout part is adhered to a teeth impression model, and then the adhered cutout part is given a mark showing the insertion position and direction of implant, and a hole for implant is drilled along this mark. [0010] However, in this method, many operations are required as described above and the hole for implant is processed while visually observing the mark, whereby there is a concern that the hole for implant may not be processed correctly. PRIOR ART DOCUMENTS Patent Documents [0000] Patent document 1: European Patent No. 1043960 Patent document 2: JP-A-2006-141561 DISCLOSURE OF THE INVENTION Problems that the Invention is to Solve [0013] The present invention is to solve such problems and provide a surgical guide preparation tool and a method for preparing the surgical guide, whereby a hole for implant can be formed at a predetermined position correctly and easily. Means of Solving the Problems [0014] The present invention provides a gauge body having a pair of marker members each of which has plural marks which are recognizable by a CT scanned image and disposed longitudinally and laterally at substantially regular intervals. Using a surgical guide preparation tool comprising the gauge body attached to a surgical guide body, predetermined marks are chosen from the plural marks on the marker members, and the direction connecting the chosen marks is used as the direction of the hole for implant. To the marker members, a support member for supporting the marker member is provided. [0015] Further, in the present invention, it is possible to detachably install an X-ray impermeable artificial tooth which can be recognized by a CT scanned image at the internal side of the gauge body, and confirm the positional relation between the direction of the hole for implant and the artificial tooth. [0016] Furthermore, the method for preparing a surgical guide of the present invention comprises a step of preparing the above gauge body; a step of installing the gauge body at a position of the surgical guide body that corresponds to a deficient tooth, capturing into a computer a CT scanned image obtained in such a state that the surgical guide body is positioned on the teeth, and reading the positions of marks of both marker members corresponding to the insertion direction of the implant by analysis with computer operation; a step of inserting a positioner into the internal side of the guide ring, inserting the guide ring into the internal side of the gauge body, and inserting a pin in such a direction connecting the axis of the positioner and the position of the marks of respective marker members from which the insertion direction of the implant has been read; a step of fixing the guide ring to the surgical guide body at such position where the pin is inserted, and then removing the pin, positioner and gauge body. [0017] In addition to the above steps, the method for preparing a surgical guide of the present invention further comprises a step of detachably installing the X-ray impermeable artificial tooth which can be recognized by a CT scanned image at the internal side of the gauge body, and removing the artificial tooth when the guide ring is inserted into the internal side of the gauge body; and a step of forming a slit on the guide ring so that a blade portion of a drill for boring a jaw bone can be inserted from the side face of the guide ring, and forming an opening portion of which the width is substantially the same as the slit or expands outwardly and more widely than the slit at a position of the surgical guide body corresponding to the slit. [0018] The surgical guide is a support having a guide ring, and this is classified into a type supported by jaw bone, a type supported by gum, and a type supported by teeth. All of the surgical guides of these types are generally made of a plastic material. If the surgical guide is made of a transparent material, the operation site can be easily seen. [0019] The guide ring to be installed in the surgical guide is made of a metal such as titanium or aluminum or a hard plastic material, with an inner diameter of about 4 mm to 9 mm and an outer diameter of about 5 mm to 10 mm so that it will suit the diameter of a guide member of a drill. However, the size is not limited to these ranges. [0020] At the side face of the guide ring, a slit is formed so that the front end portion of an implant medical instrument such as a blade portion of a drill, an implant and an adaptor for inserting the implant can be inserted from its sidewise direction. At a position of the surgical guide body corresponding to the slit, the surgical guide body is provided with an opening portion of which the width is substantially the same as the slit or expands outwardly and more widely than the slit. [0021] Since the diameter of the blade portion of the drill is generally about 2 mm to 5 mm to suit to the diameter of the implant, the width of the slit is about 4 mm to 6 mm which is a little larger than the maximum diameter of the implant to be used. However, the width of the slit is not limited to this range. [0022] If the upper part of the guide ring is outwardly expended in a tapered shape, the drill can be easily guided. [0023] The gauge body is installed in the surgical guide body. The gauge body has a pair of marker members opposing to each other, and the marker members may have a surface configuration of quadrilateral, rectangular, circular, elliptical, trapezoidal, etc. As the size of the gauge body, when it is used for one tooth deficient portion, the lengthwise and lateral widths are about 10 to 20 mm, the height is about 10 to 30 mm, and the thickness is about 1 to 2 mm. However, the size is not limited to these ranges. When it is used for adjoining plural teeth deficient portion, the width is of course adjusted suitably to the number of teeth. [0024] The surfaces of the pair of marker members of the gauge body are provided with marks which are recognizable by a CT scanned image and disposed longitudinally and laterally at substantially regular intervals. The marks may be provided on the side faces of the marker members. [0025] When the pair of marker members is made of an X-ray permeable member, for example, an X-ray permeable plastic material, grid-like lines or grooves are formed by coating the marker member surfaces with an X-ray impermeable material (e.g. barium sulfate, bismuth oxide, bismuth subcarbonate, etc.) and intersections of these lines or grooves are used as marks, or an X-ray impermeable material is embedded in grid-like or dot-like form on the marker member surface and the intersections of the grid or the dots are used as marks. In this instance, when a pigment, a coating, etc. is blended to the X-ray impermeable material for coloration, the marks can be further easily seen. [0026] The intersection portions may be provided with small holes, and a part of the small holes (a hole located at the center of the marker member, or a hole located at the end thereof) may be formed larger than others and used as a standard hole. The size of the small holes is about 1 mm in diameter, but may be of other diameter. [0027] On the other hand, when the pair of marker members is made of an X-ray impermeable material, for example, a metallic material or a plastic material having an X-ray impermeable material blended, small holes or standard holes are disposed at the positions as the intersections of grid-like lines, and such small holes are used as marks. In this instance, it is advisable that grid-like lines are given on the surfaces of the pair of marker members so that the grid-like lines can be visually observed. [0028] The position of mark is not limited to just on the grid-like lines, and it may be located at the intersections of appropriately shaped-lines such as a spider web-like or ripple-like shape so far as the position can be recognized by a CT scanned image. Further, a metallic mesh material may be used as the marker member, and in this instance, the holes of the mesh are used as the position of mark. [0029] The marks are formed at intervals of about 1 to 2 mm, but may have other intervals. Further, the marks are formed to have a depth of about 0.5 to 1 mm, but may have other depth. [0030] Since the internal side of the gauge body is space, the artificial tooth corresponding to the tooth deficient portion can be inserted into this space. The artificial tooth is temporarily fixed to the lower marker member, a support member, etc. of the gauge body, with a polymerizable resin, etc. Further, the surface of the artificial tooth is recognizable by the CT scanned image by coating the surface with an X-ray impermeable material or producing the artificial tooth integrally with an X-ray impermeable material. By installing the artificial tooth within the internal side of the gauge body, it is possible to observe the occluded condition of teeth in the insertion direction of implant and install the artificial tooth at the predetermined position and in the predetermined direction. The artificial tooth may sometimes be omitted. [0031] A surgical guide preparation tool comprising a surgical guide body and a gauge body attached thereto or a surgical guide preparation tool comprising a surgical guide body and a gauge body with the artificial tooth, attached thereto, is installed in a portion corresponding to the patient's deficient tooth, and subjected to CT scanning with an X-ray CT scanning machine to obtain a CT scanned image. This CT scanned image is captured into a computer, and analyzed by use of a CT scanned image analyzing software (for example, a software such as One Volume Viewer: J. MORITA MFG. CORP.), and while confirming the marks of respective marker members of the gauge body and the position of the artificial tooth, the position of mark corresponding to the insertion position and direction of implant is determined. The above CT scanned image may be at first stored in a recording medium such as CD or DVD and then captured into a computer; or the X-ray CT scanning machine may be connected to a computer, and the CT scanned image may be directly captured into the computer. [0032] After the CT scanning, the surgical guide preparation tool is removed from the patient, a pin made of a metal such as stainless steel or a tough plastic is inserted into a small hole as the mark of each marker member determined as above. If no small hole is formed, a small hole may be perforated by a pointed pin. The direction of this pin is used as the predetermined insertion direction of implant. [0033] Here, the pin is temporarily pulled out, a positioner is inserted into the guide ring, this guide ring is inserted into the internal space of the gauge body, and the pin is again inserted into the small hole as the mark and the hole at the center of the positioner. Under this condition, a fixing material such as a polymerizable resin is filled around the guide ring to fix the guide ring to the surgical guide body. [0034] After the fixing material is cured, the pin is removed, and then the gauge body and the positioner are removed to complete the surgical guide. The positioner is usually made of a plastic material (including a foamed material), but may be made of other materials. Effects of the Invention [0035] In the present invention, as described above, it is possible to correctly match the position and direction of the guide ring attached to the surgical guide with the insertion position and direction of the implant, and therefore the precision of implant treatment can be increased and costs can be reduced. Further, by using the preparation tool and preparation method of the present invention, it becomes possible to improve the safety in implant operation and shorten the operation time, whereby the mental burden of the patients, operators and medical staff can be reduced, treatment results can be improved, and the economic burden on patients and clinics can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS [0036] FIG. 1 is a perspective view of a surgical guide showing an example of the present invention. [0037] FIG. 2 is a perspective view of a surgical guide preparation tool. [0038] FIG. 3 is a perspective view of a lower jaw teeth impression model. [0039] FIG. 4 is a perspective view of a surgical guide body. [0040] FIG. 5 is a perspective view of a gauge body. [0041] FIG. 6 is a perspective view showing a state where a surgical guide preparation tool is attached to a lower jaw teeth impression model. [0042] FIG. 7 is a schematic view showing a CT scanned image taken when a surgical guide preparation tool is attached to the patient's teeth. [0043] FIG. 8 is a perspective view showing a state where a guide ring is inserted into the internal space of a gauge body. [0044] FIG. 9 is an enlarged perspective view of a positioner. [0045] FIG. 10 is an enlarged perspective view of a guide ring. [0046] FIG. 11 is an exploded perspective view of an assembled gauge body showing another example. [0047] FIG. 12 is an exploded perspective view of an assembled gauge body showing a further example. [0048] FIG. 13 is an exploded perspective view of a gauge body showing another example. [0049] FIG. 14 is a perspective view of a drill. [0050] FIG. 15 is a schematic view of a computer system for analysis of a CT scanned image. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0051] Hereinafter, the surgical guide preparation tool and the method for preparing the surgical guide will be explained. [0052] A surgical guide 1 shown in FIG. 1 has a guide ring 4 which guides a guide member 3 of a drill 2 shown in FIG. 14 . This guide ring 4 is attached to a surgical guide body 6 so that the installed position and direction of the guide ring would match the insertion position and direction of an implant. The attachment is carried out by a surgical guide preparation tool 7 comprising surgical guide body 6 (shown in FIG. 4 .) and a gauge body 5 (shown in FIG. 2 ) attached thereto, as shown below. [0053] As shown in FIG. 3 , firstly, a patient's lower jaw teeth impression model 8 and an artificial tooth 9 which corresponds to a deficient tooth are prepared; and a pin 10 is put into a hole 68 of the lower jaw teeth impression model 8 which is presumed to be bored at an appropriate position and in an appropriate direction, through a center hole 67 of the artificial tooth 9 , and then the artificial tooth 9 is temporarily fixed to the lower jaw teeth impression model 8 . The surface of the artificial tooth 9 is coated with an X-ray impermeable material. [0054] Then, the surgical guide body 6 is prepared by using the lower jaw teeth impression model 8 . At a portion of the surgical guide body 6 which corresponds to the deficient tooth, a hole 11 is formed so that a part of the upper portion of the artificial tooth 9 would be exposed as shown in FIG. 4 . [0055] As shown in FIG. 5 , the gauge body 5 comprises an upper marker member 12 , a lower marker member 13 and a support member 14 which connects the pair of marker members. The gauge body 5 is generally prepared integrally with a plastic material having X-ray impermeability. [0056] The surfaces of the marker members 12 , 13 are given grid-like lines 15 , and at the intersections of the lines, small holes 16 are bored. A hole at the center portion of the marker member is formed to have a larger diameter than that of small holes 16 and is used as a standard hole 17 . [0057] Here, as shown in FIG. 6 , the artificial tooth 9 and pin 10 are removed from the lower jaw teeth impression model 8 , and the artificial tooth 9 is inserted into an internal space 18 of the gauge body 5 and placed on the lower marker member 13 . And, the position of the gauge body 5 is determined by putting a pin 35 through the standard hole 17 of the gauge body 5 , a hole 67 at the center of the artificial tooth and a hole 68 of the lower jaw teeth impression model 8 . When the support member 14 of the gauge body 5 abuts on the side face of the surgical guide body 6 , a part of the side face portion of the surgical guide body 6 is removed. [0058] In this instance, in order to allow the lower marker member 13 of the gauge body 5 to be inserted into the lower side of the surgical guide body 6 , the lower portion of the artificial tooth 9 is preliminarily removed in such a thickness corresponding to the thickness of the lower marker member 13 to adjust the installation height of the artificial tooth 9 , and then the artificial tooth 9 is temporarily fixed at a predetermined position by use of a polymerizable resin, an adhesive, etc. Thereafter, the surgical guide body 6 and the gauge body 5 are fixed with fixing material 38 such as a polymerizable resin, and then the pin 35 is pulled out to complete the surgical guide preparation tool 7 . [0059] The thus prepared surgical guide preparation tool 7 is attached to the patient's teeth, and a CT scanned image 20 is obtained by CT scanning with an X-ray CT scanning machine 19 . [0060] As shown in FIG. 15 , the CT scanned image 20 is captured into a computer 21 (provided with a monitor 22 , a key board 23 and a mouse 24 ), the image is analyzed with use of a CT scanned image analyzing software installed in the computer 21 , and the positions of marks of the pair of marker members 12 , 13 which correspond to the insertion direction of implant are recognized. [0061] Namely, as shown in FIG. 7 , an axial section 25 , a panorama section 26 and an orthoradial section 27 are displayed by operation of the computer 21 , and while confirming the positions of respective marker members of the gauge body, a panorama cutting line 29 and an orthoradial cutting line 30 are moved on these sections in such a direction that the implant is to be inserted. After confirming that sufficient jaw bone is present in the directions of the panorama cutting line 29 and the orthoradial cutting line 30 on the panorama section 26 and the orthoradial section 27 and further confirming that nerves and blood vessels 31 , 32 are not present at these sites, these directions are determined to be an insertion direction of implant. [0062] In the determined direction, by moving an axial cutting line 28 , marks 33 , 34 of respective marker members positioned at the intersections of the above cutting lines are read as marks corresponding to the insertion direction of implant. At this instance, the positions of the marks 33 , 34 can be determined by reading the distance of the small holes or scale on the CT scanned image from the standard hole 17 . [0063] Next, as shown in FIG. 8 , a part of the surgical guide preparation tool 7 is removed and the artificial tooth 9 is taken out, and then the pin 35 is inserted into two holes formed at the marks 33 , 34 of respective marker members which have been read. Before the pin is inserted, a positioner 36 shown in FIG. 9 is inserted into the guide ring 4 shown in FIG. 10 , and this guide ring 4 is inserted into the internal space 18 of the gauge body 5 . And, the pin 35 is put into a hole 37 at the center of the positioner 36 . At both or either one of edge faces of the positioner 36 , a funnel-shaped convex face 69 is formed, and the front end part of the pin 35 can be guided with the convex face 69 and can be easily inserted into the hole 37 at the center of the positioner 36 . [0064] Under such condition, a fixing material 38 such as a polymerizable resin is filled around the guide ring 4 , and the guide ring 4 is connected to the surgical guide body 6 to integrate them. Thereafter, the pin 35 , positioner 36 and gauge body 5 are removed to complete the surgical guide 1 as shown in FIG. 1 . After removing the gauge body 5 , etc., if necessary, a fixing material such as a polymerizable resin may be supplied to a connecting portion of the guide ring 4 and the surgical guide body 6 . [0065] Around the guide ring 4 , a convex 39 or concave is formed, by which rotating motion of the guide ring 4 can be prevented. [0066] The surgical guide 1 is provided with an opening portion 41 expanding outwardly so that it would have a width larger than the width of a slit 40 of the guide ring as shown in FIG. 1 . The width of the slit 40 is at such a level of allowing a blade portion 59 for dentistry to pass therethrough as shown in FIG. 14 , and the inner diameter of the guide ring is at such a level of allowing the guide member 3 of the drill 2 to be slidably guided. [0067] The gauge body 5 shown in FIG. 11 is of an assembly type, and comprises an upper member 42 having an upper marker member 12 and a support member 14 integrally formed, a lower marker member 13 provided with a support plate 43 , and a base plate 44 for supporting the artificial tooth 9 . A support frame 45 extends from the lower end portion of the upper member 42 , and this support frame 45 engages in a dovetail groove 47 formed by a projection 46 disposed on the lower marker member 13 . Further, the base plate 44 engages in a dovetail groove 48 formed by the projection 46 disposed on the lower marker member 13 . On the surfaces of the upper marker member 12 and lower marker member 13 , marks 49 drawn in grid-like form with an X-ray impermeable material are indicated. In this example, a base plate 44 is disposed. However, in a case where the artificial tooth 9 is directly supported by the lower marker member 13 , the base plate 44 is omitted. [0068] The gauge body 5 shown in FIG. 12 shows another assembly type, and comprises an upper marker member 12 ; an upper frame member 52 having an upper frame 50 supporting the upper marker member 12 , and one support member 51 , integrally constituted; a lower marker member 13 ; a lower frame member 55 having a lower frame 53 supporting the lower marker member 13 , and another support member 54 , integrally constituted; and the artificial tooth 9 . The upper marker member 12 engages in a dovetail groove 60 disposed on the upper frame 50 , and the lower marker member 13 engages in a dovetail groove 61 disposed on the lower frame member 55 . Another support member 51 for the upper frame member 52 and another support member 54 for the lower frame member 55 are connected by engaging a concave-type projection 56 and a convex-type groove 57 formed on these support members, respectively. In this example, the upper frame member 52 and the lower frame member 55 are made of a transparent material; the positions of marks 58 obtained by analysis of a CT scanned image are indicated on the upper frame 50 and the lower frame 53 ; and the upper frame member 52 and the lower frame member 55 are used as expendable supplies, and the upper marker member 12 and the lower marker member 13 are reused as master pieces. [0069] The gauge body 5 shown in FIG. 13 comprises the upper marker member 12 ; an upper frame 63 which has a support portion 62 and supports the upper marker member 12 ; a lower marker member 13 ; a lower frame 64 which supports the lower marker member 13 ; and the artificial tooth 9 . The upper marker member 12 engages in a dovetail groove 65 disposed on the support portion 62 of the upper frame 63 , and the lower marker member 13 engages in a dovetail groove 61 disposed on the lower frame 64 . EXPLANATION OF NUMERALS [0000] 1 Surgical guide 4 Guide ring 5 Gauge body 6 Surgical guide body 8 Lower jaw teeth impression model 9 Artificial tooth 12 Upper marker member 13 Lower marker member 14 Support member 16 Small hole 17 Standard hole 19 X-ray CT scanning machine 20 CT scanned image 21 Computer 33 , 34 , 49 , 58 Marks 35 Pin 36 Positioner 40 Slit 41 Opening portion

The present invention provides an inexpensive surgical guide preparation tool by which an insertion hole for implant can be correctly and easily formed at a predetermined position. The surgical guide preparation tool has a pair of marker members opposing to each other and a gauge body which has a support member for connecting the marker members, and the gauge body is attached to a surgical guide body. The surface of each marker member is provided with grid-like lines which are recognizable by a CT scanned image and disposed longitudinally and laterally at substantially regular intervals; predetermined marks are chosen from intersections of the grid-like lines, and a guide ring is attached to the surgical guide body so that a direction connecting the chosen marks is used as an axial direction of the guide ring. The axial direction of the guide ring is used as an insertion direction for implant.

FIELD OF INVENTION [0001] The present invention relates to novel compounds of formula (I) and their pharmaceutically acceptable salts and compositions containing them, for treatment of various disorders that are related to Histamine H 3 receptors. [0000] BACKGROUND OF THE INVENTION [0002] Histamine H3 receptor is a G-protein coupled receptor (GPCR) and one out of the four receptors of Histamine family. Histamine H3 receptor is identified in 1983 and its cloning and characterization were done in 1999. Histamine H 3 receptor is expressed to a larger extent in central nervous system and lesser extent in the peripheral nervous system. [0003] Literature evidence suggests that Histamine H3 receptors can be used in treatment of cognitive disorders (British Journal of Pharmacology, 2008, 154(6), 1166-1181), dementia (Drug News Perspective, 2010, 23(2), 99-103), attention deficit hyperactivity disorder, epilepsy, sleep disorders, sleep apnea, obesity (Indian Journal of Pharmacology, 2001, 33, 17-28), schizophrenia (Biochemical Pharmacology, 2007, 73(8), 1215-1224), eating disorders (Investigational drugs for eating disorders, 1997, 6(4), 427-436) and pain (Pain, 2008, 138(1), 61-69). [0004] Patent publications US 2009/0170869, US 2010/0029608, US 2010/0048580, WO 2009/100120, WO 2009/121812 and WO 2009/135842 disclosed series of compounds as ligands at Histamine H3 receptors. While some Histamine H3 receptor ligands have been disclosed, no compound till date is launched in market in this area of research, and there still exists a need and scope to discover new drugs with novel chemical structures for treatment of disorders affected by Histamine H3 receptors. SUMMARY OF THE INVENTION [0005] The present invention relates to novel Histamine H 3 receptor ligand compounds of the formula (I), [0000] [0000] wherein, [0006] at each occurrence, R 1 is independently selected from hydrogen, hydroxy, hydroxyalkyl, halogen, alkyl, alkoxy, haloalkyl, haloalkoxy, cyano or —C(O)—NH 2 [0007] L is alkyl or [0000] [0008] X is C, O or N—R 2 ; [0009] Y is C or N; [0010] A is —C(O)— or —CH 2 ; [0011] R 2 is hydrogen, alkyl, —C(O)-alkyl or —S(O) 2 -alkyl; [0012] “r” is an integer ranging from 0 to 1; [0013] “p” is an integer ranging from 0 to 3; or a pharmaceutically acceptable salt thereof. [0014] The present invention relates to use of a therapeutically effective amount of compound of formula (I), to manufacture a medicament in the treatment of various disorders that are related to Histamine H3 receptors. [0015] Specifically, the compounds of this invention are useful in the treatment of various disorders such as cognitive disorders, dementia, attention deficit hyperactivity disorder, schizophrenia, epilepsy, sleep disorders, sleep apnea, obesity, eating disorders and pain. [0016] In another aspect, the invention relates to pharmaceutical compositions containing a therapeutically effective amount of at least one compound of formula (I), and their pharmaceutically acceptable salts thereof, in admixture with pharmaceutical acceptable excipient. [0017] In still another aspect, the invention relates to methods for using compounds of formula (I). [0018] In yet another aspect, the invention further relates to the process for preparing compounds of formula (I) and their pharmaceutically acceptable salts. [0019] Representative compounds of the present invention include those specified below and their pharmaceutically acceptable salts. The present invention should not be construed to be limited to them. N-[4-(1-Cyclobutyl piperidin-4-yloxy)phenyl]-2-(morpholin-4-yl)acetamide dihydrochloride; 2-[4-(1-Cyclobutyl piperidin-4-yloxy)phenylamino]-1-(morpholin-4-yl)ethanone hydrochloride; N-[4-(1-Cyclobutyl piperidin-4-yloxy)-2-fluoro-phenyl]-2-(morpholin-4-yl)acetamide dihydrochloride; N-[4-(1-Cyclobutyl piperidin-4-yloxy)benzyl]morpholine-4-yl amide; N-[4-(1-Cyclobutyl piperidin-4-yloxy)-3-fluoro phenyl]-2-(morpholin-4-yl)acetamide; N-[4-(1-Cyclobutyl piperidin-4-yloxy)-2-methyl phenyl]-2-(3,3-difluoro pyrrolidin-1-yl) acetamide; N-[4-(1-Cyclobutyl piperidin-4-yloxy)-2-trifluoromethyl phenyl]-2-(piperidin-1-yl)acetamide; N-[4-(1-Cyclopentyl piperidin-4-yloxy)phenyl]-2-(morpholin-4-yl)acetamide; N-[4-(1-Cyclobutyl piperidin-4-yloxy)-2-trifluoromethyl phenyl]-2-(morpholin-4-yl)acetamide; N-[4-(1-Isopropyl piperidin-4-yloxy)-2-methyl-phenyl]-2-(pyrrolidin-1-yl)acetamide; N-[4-(1-Cyclobutyl piperidin-4-yloxy)-2-methyl phenyl]-2-(pyrrolidin-1-yl)acetamide; N-[4-(1-Cyclopentyl piperidin-4-yloxy)-2-methyl phenyl]-2-(piperidin-1-yl)acetamide; N-[4-(1-Cyclobutyl piperidin-4-yloxy)-2-methyl phenyl]-2-(piperidin-1-yl)acetamide; N-[4-(1-Cyclobutyl piperidin-4-yloxy)phenyl]-N-methyl-2-(morpholin-4-yl)acetamide; N-[4-(1-Cyclopentyl piperidin-4-yloxy)-2-methyl phenyl]-2-(R-2-methylpyrrolidin-1-yl) acetamide; N-[4-(1-Cyclobutyl piperidin-4-yloxy)-2-methyl phenyl]-2-(R-2-methylpyrrolidin-1-yl) acetamide; N-[4-(1-Cyclobutyl piperidin-4-yloxy)-2-methoxy phenyl]-2-(morpholin-4-yl)acetamide; N-[4-(1-Cyclobutyl piperidin-4-yloxy)-2-trifluoromethyl phenyl]-2-(4-hydroxy piperidin-1-yl) acetamide; N-[4-(1-Cyclobutyl piperidin-4-yloxy)phenyl]-2-(4-hydroxy piperidin-1-yl)acetamide; N-[4-(1-Cyclopentyl piperidin-4-yloxy)-2-fluoro phenyl]-2-(morpholin-4-yl)acetamide dihydrochloride; N-[4-(1-Cyclobutyl piperidin-4-yloxy)phenyl]-2-(pyrrolidin-1-yl)acetamide; N-[4-(1-Isopropyl piperidin-4-yloxy)phenyl]-2-(morpholin-4-yl)acetamide; N-[4-(1-Cyclopropyl piperidin-4-yloxy)phenyl]-2-(morpholin-4-yl)acetamide; N-[4-(1-Cyclobutyl piperidin-4-yloxy)phenyl]-2-(4-isopropyl[1,4]diazepan-1-yl)acetamide; N-[4-(1-Cyclobutyl piperidin-4-yloxy)phenyl]-2-(2-hydroxymethyl morpholin-4-yl)acetamide; N-[4-(1-Cyclobutyl piperidin-4-yloxy)phenyl]-3-(morpholin-4-yl)propionamide; N-[4-(1-Cyclopentyl piperidin-4-yloxy)phenyl]-2-(piperidin-1-yl)acetamide dihydrochloride; N-[4-(1-Cyclopentyl piperidin-4-yloxy)phenyl]-2-(pyrrolidin-1-yl)acetamide dihydrochloride; N-[4-(1-Cyclobutyl piperidin-4-yloxy)phenyl]-2-(piperidin-1-yl)acetamide; N-[4-(1-Cyclobutyl piperidin-4-yloxy)-2-trifluoromethyl phenyl]-2-(pyrrolidin-1-yl)acetamide dihydrochloride; N-[4-(1-Cyclobutyl piperidin-4-yloxy)phenyl]-N-(2-morpholin-4-yl ethyl)acetamide; [4-(1-Cyclobutyl piperidin-4-yloxy)phenyl]-(2-morpholin-4-yl ethyl)amine; N-[4-(1-Cyclobutyl piperidin-4-yloxy)phenyl]-2-(R-2-hydroxymethylpyrrolidin-1-yl)acetamide L(+) tartarate; N-[2-(1-Cyclobutyl piperidin-4-yloxy)pyridin-5-yl]-N-[2-(morpholin-4-yl)ethyl]acetamide; N-[2-(1-Cyclobutyl piperidin-4-yloxy)pyridin-5-yl]-2-(piperidin-1-yl)acetamide; N-[2-(1-Cyclobutyl piperidin-4-yloxy)pyridin-5-yl]-2-(morpholin-4-yl)acetamide; N-[4-(1-Cyclobutyl piperidin-4-yloxy)-2-fluoro phenyl]-N-[2-(morpholin-4-yl)ethyl]acetamide; N-[4-(1-Cyclopropyl piperidin-4-yloxy)phenyl]-N-[2-(morpholin-4-yl)ethyl]acetamide L(+) tartarate; N-[4-(1-Cyclobutyl piperidin-4-yloxy)phenyl]-2-(1-acetyl piperazin-4-yl)acetamide dihydrochloride; N-[4-(1-Cyclobutyl piperidine-4-yloxy)-2-methyl phenyl]-2-(4-hydroxy piperidine-1-yl) acetamide; N-[4-(1-Cyclopropyl piperidin-4-yloxy)phenyl]-2-(R-2-hydroxymethylpyrrolidin-1-yl) acetamide; N-[4-(1-Cyclobutyl piperidin-4-yloxy)benzyl]-2-(morpholin-4-yl)acetamide; N-[4-(1-Cyclobutyl piperidin-4-yloxy)-2-fluoro benzyl]-2-(morpholin-4-yl)acetamide; N-[4-(1-Cyclobutyl piperidin-4-yloxy)phenyl]-2-(3-hydroxy azetidin-1-yl)acetamide; N-[4-(1-Cyclobutyl piperidin-4-yloxy)-2-fluoro phenyl]-2-(3-methoxy azetidin-1-yl)acetamide; N-[4-(1-Cyclobutyl piperidin-4-yloxy)-2-fluoro phenyl]-2-(2-hydroxymethylpyrrolidin-1-yl) acetamide; N-[2-Chloro-4-(1-cyclobutyl piperidin-4-yloxy)phenyl]-2-(morpholin-4-yl)acetamide; N-[2-Chloro-4-(1-cyclobutyl piperidin-4-yloxy)phenyl]-2-(piperidin-1-yl)acetamide; N-[4-(1-Cyclobutyl piperidin-4-yloxy)phenyl]-2-(tetrahydro pyran-4-yloxy)acetamide; 2-[4-(1-Cyclobutyl piperidin-4-yloxy)-2-fluoro phenylamino]-1-(morpholin-4-yl)ethanone; and N-[4-(1-Cyclobutyl piperidin-4-yloxy)-2-fluoro phenyl]-N-(2-morpholin-4-yl ethyl)acetamide; DETAILED DESCRIPTION OF THE INVENTION [0071] Unless otherwise stated, the following terms used in the specification and claims have the meanings given below: [0072] The term “halogen” means fluorine, chlorine, bromine or iodine. [0073] The term “alkyl” means straight chain or branched hydrocarbon radical consisting solely of carbon and hydrogen atoms, containing no unsaturation, having from one to eight carbon atoms, and which is attached to the rest of the molecule by a single bond. Exemplary “alkyl” groups include methyl, ethyl, n-propyl, iso-propyl and the like. [0074] The term “alkoxy” means an alkyl group attached via an oxygen linkage to the rest of the molecule. Exemplary “alkoxy” groups include methoxy, ethoxy, propyloxy, iso-propyloxy and the like. [0075] The term “haloalkyl” means straight or branched chain alkyl radicals containing one to three carbon atoms. Exemplary “haloalkyl” groups include fluoromethyl, difluoromethyl, trifluoromethyl, trifluoroethyl, fluoroethyl, difluoroethyl and the like. [0076] The term “haloalkoxy” means straight or branched chain alkoxy radicals containing one to three carbon atoms. Exemplary “haloalkoxy” groups include fluoromethoxy, difluoromethoxy, trifluoromethoxy, trifluoroethoxy, fluoroethoxy, difluoroethoxy and the like. [0077] The term “hydroxyalkyl” means hydroxy group is directly bonded to alkyl chain. Exemplary “hydroxyalkyl” groups include hydroxymethyl, hydroxyethyl and the like. [0078] The terms “treating”, “treat” or “treatment” embrace all the meanings such as preventative, prophylactic and palliative. [0079] The phrase “pharmaceutically acceptable salts” indicates that the substance or composition must be compatible chemically and/or toxicologically, with the other ingredients comprising a formulation, the mammal being treated therewith. [0080] The phrase “therapeutically effective amount” is defined as ‘an amount of a compound of the present invention that (i) treats or prevents the particular disease, condition or disorder (ii) attenuates, ameliorates or eliminates one or more symptoms of the particular disease, condition or disorder (iii) prevents or delays the onset of one or more symptoms of the particular disease, condition or disorder described herein. [0081] Commercial reagents were utilized without further purification. Room temperature refers to 25-40° C. Unless otherwise stated, all mass spectra were carried out using ESI conditions. 1 H-NMR spectra were recorded at 400 MHz on a Bruker instrument. Deuterated chloroform, methanol or dimethylsulfoxide was used as solvent. TMS was used as internal reference standard. Chemical shift values are expressed in parts per million (δ) values. The following abbreviations are used for the multiplicity for the NMR signals: s=singlet, bs=broad singlet, d=doublet, t=triplet, q=quartet, qui=quintet, h=heptet, dd=double doublet, dt=double triplet, tt=triplet of triplets, m=multiplet. Chromatography refers to column chromatography performed using 100-200 mesh silica gel and executed under nitrogen pressure (flash chromatography) conditions. Pharmaceutical Compositions [0082] In order to use the compounds of formula (I) in therapy, they will normally be formulated into a pharmaceutical composition in accordance with standard pharmaceutical practice. [0083] The pharmaceutical compositions of the present invention may be formulated in a conventional manner using one or more pharmaceutically acceptable excipient. The pharmaceutically acceptable excipient is carrier or diluent. Thus, the active compounds of the invention may be formulated for oral, intranasal or parenteral (e.g., intravenous, intramuscular or subcutaneous). Such pharmaceutical compositions and processes for preparing same are well known in the art (The Science and Practice of Pharmacy, D. B. Troy, 21st Edition, Williams & Wilkins, 2006). [0084] The dose of the active compounds can vary depending on factors such as the route of administration, age and weight of patient, nature and severity of the disease to be treated and similar factors. Therefore, any reference herein to a pharmacologically effective amount of the compounds of general formula (I) refers to the aforementioned factors. A proposed dose of the active compounds of this invention, for either oral or parenteral administration, to an average adult human, for the treatment of the conditions referred above. Methods of Preparation [0085] The compounds of formula (I) can be prepared by Scheme I as shown below. [0000] [0086] In above Scheme I, B is OH, Cl or Br; and all other symbols are as defined above. [0087] The compound of formula (I) is coupled with compound of formula (2) to form compound of formula (I). This reaction is preferably carried out in solvent such as tetrahydrofuran, toluene, ethyl acetate, dichloromethane, dimethylformamide, and the like or a mixture thereof and preferably by using dichloromethane and dimethylformamide. The reaction may be carried out in the presence of a base such as sodium hydride, sodium carbonate, potassium carbonate, diisopropylethylamine, sodium bicarbonate, sodium hydroxide or mixtures thereof and preferably by using potassium carbonate and diisopropylethylamine. The reaction may be affected in the presence of a coupling agent such as O-(Benzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium tetrafluoroborate. The reaction is carried out at temperature of 25° C. to 85° C. based on choice of solvent and base. The duration of the reaction may range from 4 to 18 hours, preferably from a period of 10 to 14 hours. [0088] The compounds of formula (1) and formula (2) may be commercially available or can be prepared by conventional methods or by modification, using known process. [0089] The compounds of formula (I) can also be prepared by using Scheme II as shown below [0000] [0090] In above Scheme II, all symbols are as defined above. [0091] The compound of formula (1) is converted to compound of formula (3). The compound of formula (3) is coupled with compound of formula (4) to form compound of formula (I). [0092] In the first step of the above preparation, the compound of formula (1) is converted to compound of formula (3). This reaction is preferably carried out in solvent such as tetrahydrofuran, toluene, ethyl acetate, dichloromethane, dimethylformamide, and the like or a mixture thereof and preferably by using dichloromethane. The reaction may be affected in the presence of a base such as triethylamine, potassium carbonate, diisopropylethylamine, pyridine and the like or a mixture thereof and preferable by using triethylamine. The reaction is carried out at temperature of −10° C. to 10° C. based on choice of solvent and base. The duration of the reaction may range from 0.5 to 2 hours, preferably from a period of 45 minutes to 1.5 hours. [0093] In the second step of the above preparation, the compound of formula (3) is coupled with compound of formula (4) to form compound of formula (I). This reaction is preferably carried out in solvent such as tetrahydrofuran, acetonitrile, toluene, ethyl acetate, dichloromethane, dimethylformamide, and the like or a mixture thereof and preferably by using acetonitrile. The reaction may be affected in the presence of a base such as triethylamine, potassium carbonate, diisopropylethylamine, pyridine and the like or a mixture thereof and preferable by using potassium carbonate. The reaction is carried out at temperature of 25° C. to 85° C. based on choice of solvent and base. The duration of the reaction may range from 3 to 7 hours, preferably from a period of 4 to 6 hours. [0094] The compounds of formula (1) and formula (4) may be commercially available or can be prepared by conventional methods or by modification, using known process. [0095] The compounds of formula (I) can also be prepared by using Scheme III as shown below [0000] [0096] In above Scheme III, all symbols are as defined above. [0097] The compound of formula (5) is coupled with compound of formula (4) to form compound formula (6). The compound of formula (6) is converted to compound of formula (I). [0098] In the first step of the above preparation, the compound of formula (5) is coupled with compound of formula (4) to form compound of formula (6). This reaction is preferably carried out in solvent such as acetonitrile, tetrahydrofuran, toluene, ethyl acetate, dichloromethane, dimethylformamide, and the like or a mixture thereof and preferably by using acetonitrile. The reaction may be affected in the presence of a base such as triethylamine, potassium carbonate, diisopropylethylamine, pyridine and the like or a mixture thereof and preferable by using potassium carbonate. The reaction is carried out at temperature of 25° C. to 70° C. based on choice of solvent and base. The duration of the reaction may range from 3 to 7 hours, preferably from a period of 4 to 6 hours. [0099] In the second step of the above preparation, the compound of formula (6) is subjected to deprotection followed by reductive cycloalkylation to form compound of formula (I). The deprotection reaction is preferably carried out in solvent such as acetonitrile, tetrahydrofuran, toluene, ethyl acetate, dichloromethane, dimethylformamide, methanol, ethanol, isopropanol and the like or a mixture thereof and preferably by using alcoholic solvent or dichloromethane. The reaction may be affected in the presence of an acid such as trifluoroacetic acid, sulfuric acid, acetic acid, perchloric acid, hydrochloric acid, and the like or a mixture thereof and preferable by using trifluoroacetic acid. The reaction is carried out at 25° C. to 60° C. The duration of the reaction may range from 4 to 10 hours, preferably from a period of 4 to 8 hours. After deprotection the isolated base is treated with a carbonyl compound like acetone, cyclobutanone or cyclopentanone in presence of solvent such as tetrahydrofuran, aceticacid, dichloromethane, dichloroethane and the like or a mixture thereof and preferably by using dichloroethane in presence of acetic acid. The reaction is effected in presence of a reducing agent such as sodium triacetoxy borohydride, sodium cyanoborohydride, lithium aluminium hydride, sodium borohydride and the like or a mixture thereof and preferably by using sodium triacetoxyborohydride. The reaction is carried out at temperature of 10° C. to 40° C. The duration of the reaction may range from 4 to 16 hours. [0100] The compounds of formula (4) and formula (5) may be commercially available or can be prepared by conventional methods or by modification, using known process. [0101] If necessary, any one or more than one of the following steps can be carried out, [0000] i) converting a compound of the formula (I) into another compound of the formula (I) or ii) forming a pharmaceutically acceptable salt. [0102] Process (i) may be performed by further chemical modifications using well known reactions such as oxidation, reduction, protection, deprotection, rearrangement, halogenation, hydroxylation, alkylation, alkylthiolation, demethylation, O-alkylation, O-acylation, N-alkylation, N-alkenylation, N-acylation, N-cyanation, N-sulfonylation, coupling and the like. [0103] In process (ii) pharmaceutically acceptable salts may be prepared conventionally by reaction with the appropriate acid or acid derivative. [0104] Suitable pharmaceutically acceptable salts will be apparent to those skilled in the art and include those described in J. Pharm. Sci., 1977, 66, 1-19, such as acid addition salts formed with inorganic acids like hydrochloric, hydrobromic, sulfuric, nitric or phosphoric acid and organic acids like succinic, maleic, acetic, fumaric, citric, malic, tartaric, benzoic, p-toluic, p-toluenesulfonic, methanesulfonic or benzenesulfonic acid. EXAMPLES [0105] The novel compounds of the present invention were prepared according to the following experimental procedures, using appropriate materials and appropriate conditions. Preparation 1: Preparation of 4[(1-Cyclobutyl-4-piperidinyl)oxy]aniline Step (i): Preparation of 1-Cyclobutyl-4-piperidinol [0106] A solution of 4-piperidinol (80 g, 0.792 moles) and cyclobutanone (67.2 g, 0.96 moles) in ethylene dichloride (1 L) was treated with sodium triacetoxyborohydride (251.1 g, 1.184 moles) portion wise and the mixture was stirred at room temperature for 5 hours. The reaction mixture was quenched in chilled water (1 L) and the resulting mass was basified with lye solution. The layers were separated, and the aqueous layer was extracted with dichloromethane (2×500 mL). The combined organic layers were washed with water, dried over sodium sulfate and concentrated to afford the title compound 100 g (Yield: 81.46%). [0107] 1 H-NMR (δ ppm): 1.55-2.02 (13H, m), 2.64-2.74 (2H, m), 3.68-3.70 (1H, m); [0108] Mass (m/z): 155.9 (M+H) + . Step (ii): Preparation of 1-Cyclobutyl-4-(4-nitrophenoxy)piperidine [0109] To a stirred solution of sodium hydride (24.76 g, 60% in mineral oil, 0.619 moles) in dimethylformamide (100 mL) was added 1-cyclobutyl-4-piperidinol (80 g, 0.516 moles, obtained in the above step) in dimethylformamide (300 mL) at 10° C. under a nitrogen atmosphere. The mass was stirred for 1 hour. A solution of 4-fluoronitrobenzene (87.3 g, 0.619 moles) in dimethylformamide (300 mL) was added drop wise to the above reaction mass at room temperature. After completion of reaction, the mass was quenched on to chilled water (2 L) and stirred for 1 hour. The obtained solids were separated and dissolved in ethyl acetate (1 L). The resulting ethyl acetate layer was washed with water, dried over sodium sulfate and concentrated under vacuum. The residue, thus obtained, was purified by flash chromatography (methanol:chloroform, 2:8) to afford the title compound 99.7 g (Yield: 70%). [0110] 1 H-NMR (δ ppm): 1.67-1.71 (2H, m), 1.83-1.91 (4H, m), 2.00-2.08 (4H, m), 2.11-2.19 (2H, m), 2.51-2.60 (2H, m), 2.71-2.78 (1H, m), 4.44-4.46 (1H, m), 6.93-6.95 (2H, d, J° 9.2 Hz), 8.17-8.20 (2H, d, J=9.2 Hz); [0111] Mass (m/z): 277.3 (M+H) + . Step (iii): Preparation of 4[(1-Cyclobutyl-4-piperidinyl)oxy]aniline [0112] Hydrogen gas was bubbled through a solution of 1-Cyclobutyl-4-(4-nitrophenoxy)piperidine (94.9 g, 0.344 moles, obtained in above step) over 10% Pd/C (95 g) in methanol (2 L) at room temperature, for 5 hours. The mixture was filtered through a pad of celite, and the filtrate was concentrated under vacuum to obtain the title compound 81 g (Yield: 95.7%). [0113] 1 H NMR (δ ppm): 1.62-2.07 (12H, m), 2.62-2.76 (3H, m), 3.43-3.47 (2H, m), 4.13-4.17 (1H, m), 6.61-6.63 (2H, d, J=8.7 Hz), 6.75-6.77 (2H, d, J=8.7 Hz); [0114] Mass (m/z): 247.5 (M+H) + . Preparation 2: Preparation of 4-(1-Cyclobutyl piperidin-4-yloxy)benzylamine Step (i): Preparation of 4-(4-Cyano phenoxy)piperidine-1-carboxylic acid tert-butyl ester [0115] A solution of 4-hydroxy benzonitrile (15 g, 0.126 moles), potassium carbonate (28.89 g, 0.208 moles) and 4-(Toluene-4-sulfonyloxy)piperidine-1-carboxylic acid tert-butyl ester (57.62 g, 0.162 moles) in dimethylformamide (150 mL) was stirred at 100° C. while monitoring the progress of the reaction by thin layer chromatography. After completion of reaction, the reaction mass was quenched on to water (400 mL) and extracted with ethyl acetate (3×300 mL). The resulting ethyl acetate layer was washed with brine solution, dried over sodium sulfate and concentrated under reduced pressure to obtain the crude residue, which was further purified by flash chromatography using (ethyl acetate:hexane, 1:9) to afford the title compound 21.25 g [0116] (Yield: 55.8%). [0117] 1 H-NMR (δ ppm): 1.47 (9H, s), 1.74-1.80 (2H, m), 1.91-1.96 (2H, m) 3.33-3.40 (2H, m), 3.66-3.72 (2H, m), 4.53-4.57 (1H, m), 6.94-6.96 (2H, d, J=8.78 Hz), 7.57-7.59 (2H, d, J=8.76 Hz); [0118] Mass (m/z): 303.4 (M+H) + . Step (ii): Preparation of 4-(1-Cyclobutyl piperidin-4-yloxy)benzonitrile [0119] To a stirred solution of 4-(4-Cyano phenoxy)piperidine-1-carboxylic acid tert-butyl ester (21.25 g, 0.0704 moles) in dichloromethane (300 mL) was added trifluoroacetic acid (81.4 g, 0.714 moles) and stirred the reaction mass overnight at room temperature. After completion of reaction, solvent was evaporated under vacuum and the residue, thus obtained, was basified with 10% caustic lye solution. The reaction mass was extracted with ethyl acetate twice, the combined organic layer was dried over sodium sulphate and evaporated under reduced pressure. The crude product, thus obtained, was treated with cyclobutanone (5.18 g, 0.074 moles), acetic acid (4.89 g, 0.0815 moles) in ethylene dichloride (100 mL), and stirred for 4 hours at room temperature. Sodium triacetoxyborohydride (35.06 g, 0.165 moles) was added to the reaction mass in a single lot and the mixture was stirred at room temperature for 2 hours. The reaction mixture was quenched in water and basified with lye solution. The layers were separated and the aqueous layer was extracted with dichloromethane twice. The combined organic layers were dried over sodium sulfate, concentrated under vacuum and the residual mass was further purified by flash chromatography (dichloromethane: triethylamine, 9.5:0.5) to obtain the title compound 10.92 g (Yield: 60.5%). [0120] 1 H-NMR (δ ppm): 1.67-1.76 (2H, m), 1.88-1.97 (2H, m), 2.04-2.14 (6H, m) 2.49 (2H, bs), 2.64-2.68 (2H, m), 2.85-2.91 (1H, m), 4.47-4.49 (1H, m), 6.92-6.94 (2H, d, J=8.8 Hz), 7.56-7.58 (2H, d, J=8.8 Hz); [0121] Mass (m/z): 257.4 (M+H) + . Step (iii): Preparation of 4-(1-Cyclobutyl piperidin-4-yloxy)benzylamine [0122] A solution of 4-(1-Cyclobutyl piperidin-4-yloxy)benzonitrile (8.22 g, 0.032 moles) in dry tetrahydrofuran (50 mL) was added to a stirred solution of lithium aluminium hydride (3.74 g, 0.098 moles) in dry tetrahydrofuran (30 mL), at 10 to 15° C. under nitrogen atmosphere. The resulting mass was further stirred for 20 minutes at ambient temperature and then refluxed for 4 hours. After completion of reaction, the mass was cooled to 10-15° C., quenched with water and basified with 4N sodium hydroxide solution. Reaction mass was filtered through celite and cake was washed with ethyl acetate. The separated organic layer was dried over sodium sulphate and concentrated under reduced pressure to obtain the title compound 7.17 g (Yield: 86.2%). [0123] 1 H-NMR (δ ppm): 1.65-1.72 (2H, m), 1.82-1.88 (4H, m), 1.96-2.05 (4H, m), 2.14 (2H, bs), 2.62 (2H, bs), 2.66-2.75 (1H, m), 3.79 (2H, m), 4.29-4.31 (1H, m), 6.85-6.88 (2H, d, J=8.5 Hz), 7.20-7.21 (2H, d, J=8.5 Hz); [0124] Mass (m/z): 261.4 (M+H) + . Preparation 3: Preparation of tert-Butyl 4-[4-(2-chloro acetylamino)-3-fluoro phenoxy]piperidine-1-carboxylate Step (i): Preparation of tert-Butyl 4-(3-fluoro-4-nitro phenoxy)piperidine-1-carboxylate [0125] 3-Fluoro-4-nitro phenol (5 g, 0.032 moles), potassium carbonate (6.34 g, 0.047 moles) and tert-Butyl 4-(toluene-4-sulfonyloxy)piperidine-1-carboxylate (14 g, 0.04 moles) in dimethylformamide (50 mL) were stirred at 100° C. After completion of reaction, the mass was quenched on to water (100 mL) and extracted with ethyl acetate (2×100 mL). The resulting organic layer was washed with brine solution, dried over sodium sulfate and concentrated under reduced pressure to obtain the crude residue, which was further purified by flash chromatography using (ethyl acetate:hexane, 0.5:9.5) to afford the title compound 9.23 g (Yield: 85%). [0126] 1 H-NMR (δ ppm): 1.47 (9H, s), 1.75-1.82 (2H, m), 1.94-1.99 (2H, m), 3.35-3.41 (2H, m), 3.67-3.73 (2H, m), 4.54-4.59 (1H, m), 6.72-6.77 (2H, m), 8.07-8.11 (1H, m); [0127] Mass (m/z): 341.3 (M+H) + . Step (ii): Preparation of tert-Butyl 4-(4-amino-3-fluoro phenoxy)piperidine-1-carboxylate [0128] tert-Butyl 4-(3-fluoro-4-nitro phenoxy)piperidine-1-carboxylate (9.22 g, 0.027 moles) was hydrogenated over 10% Pd/C (9.22 g) in methanol (92.2 mL) by bubbling hydrogen gas for 5 hours at ambient temperature. The mixture was filtered through a pad of celite, and the filtrate was concentrated under vacuum to obtain the title compound 7.54 g (Yield: 90%). The product was used as such in the next step without further purification. [0129] 1 H-NMR (δ ppm): 1.47 (9H, s), 1.75-1.82 (2H, m), 1.94-1.99 (2H, m), 3.35-3.41 (2H, m), 3.67-3.73 (2H, m), 4.54-4.59 (1H, m), 6.23-6.35 (3H, m); [0130] Mass (m/z): 311.6 (M+H) + . Step (iii): Preparation of tert-Butyl 4-[4-(2-chloro acetylamino)-3-fluoro phenoxy]piperidine-1-carboxylate [0131] tert-Butyl 4-(4-amino-3-fluoro phenoxy)piperidine-1-carboxylate (7.54 g, 0.024 moles) was dissolved in dichloromethane (100 mL) and added triethylamine (3.6 g, 0.036 moles) at room temperature. To the resulting mass, a solution of chloro acetyl chloride (2.9 g, 0.026 moles) in dichloromethane (15 mL) was added drop wise at room temperature. After completion of the reaction, the organic mass was washed with water, dried over sodium sulfate, and concentrated under reduced pressure to obtain the crude residue, which was further purified by flash chromatography using (ethyl acetate:hexane, 1:5) to afford the title compound 5.94 g (Yield: 64%). [0132] 1 H-NMR (δ ppm: 1.47 (9H, s), 1.72-1.76 (2H, m), 1.89-1.94 (2H, m), 3.31-3.37 (2H, m), 3.65-3.71 (2H, m), 4.21 (2H, s), 4.40-4.44 (1H, m), 6.70-6.74 (2H, m), 8.03-8.07 (1H, t, J=8 Hz), 8.32 (1H, s); [0133] Mass (m/z): 387.2 (M+H) + , 389.1 (M+H) + . Example 1 Preparation of N-[4-(1-Cyclobutyl piperidin-4-yloxy)phenyl]-2-(morpholin-4-yl)-acetamide dihydrochloride Step (i): Preparation of 2-Chloro-N-[4-(1-cyclobutyl piperidin-4-yloxy)phenyl]acetamide [0134] Triethylamine (66.5 g, 0.658 moles) was added to a solution of 4-[(1-Cyclobutyl-4-piperidinyl)oxy]aniline (81 g, 0.329 moles, obtained in preparation 1) in dichloromethane (1 L), at 0° C. under nitrogen atmosphere. Then the resulting mass was treated with a solution of chloro acetyl chloride (44.6 g, 0.395 moles) in dichloromethane (1 L) drop wise at 0° C. and stirred at 0° C. for 1 hour. The reaction mixture was washed with water, dried over sodium sulfate and concentrated under vacuum and the crude compound thus obtained was purified by flash chromatography (methanol:chloroform, 2:8) to obtain the title compound 76.1 g (Yield: 72%). [0135] 1 H-NMR (δ ppm: 1.55-1.99 (12H, m), 2.49-2.67 (3H, m), 4.19 (2H, s), 4.26-4.28 (1H, m), 6.88-6.90 (2H, d, J=8.9 Hz), 7.44-7.46 (2H, d, J=8.9 Hz), 10.13 (1H, s); [0136] Mass (m/z): 323.2 (M+H) + . Step (ii): Preparation of N-[4-(1-Cyclobutyl piperidin-4-yloxy)phenyl]-2-(morpholin-4-yl)acetamide [0137] A mixture of 2-Chloro-N-[4-(1-cyclobutyl piperidin-4-yloxy)phenyl]acetamide (76.0 g, 0.236, obtained in above step), morpholine (30.8 g, 0.353 moles) and potassium carbonate (98 g, 0.71 moles) in acetonitrile (1.5 L) was stirred for 5 hours at reflux temperature. The mixture was partitioned between ethyl acetate (1 L) and water (1 L). The layers were separated, and the aqueous layer was extracted with ethyl acetate (2×500 mL). The combined organic layers were washed with water twice, dried over sodium sulfate and concentrated under vacuum. The crude compound was purified by flash chromatography using (methanol:chloroform, 2:8) to afford the title compound 71 g (Yield: 80%). [0138] 1 H-NMR (δ ppm): 1.53-1.99 (12H, m), 2.46-2.68 (7H, m), 3.06 (2H, s), 3.60-3.63 (4H, m), 4.24-4.28 (1H, m), 6.85-6.88 (2H, d, J=8.9 Hz), 7.47-7.50 (2H, d, J=8.9 Hz), 9.5 (1H, s); [0139] Mass (m/z): 374.2 (M+H) + . Step (iii): Preparation of N-[4-(1-Cyclobutyl piperidin-4-yloxy)phenyl]-2-(morpholin-4-yl) acetamide dihydrochloride [0140] To a stirred solution of N-[4-(1-Cyclobutyl piperidin-4-yloxy)phenyl]-2-(morpholin-4-yl)acetamide (70 g, 0.187 moles) in diethyl ether (2.3 L) and methanol (350 mL) was treated with 31.5% w/v methanolic hydrochloric acid (54.36 mL, 0.469 moles). The reaction mass was further stirred 2-3 hours at room temperature. The solvent was decanted and the resulting solid mass was washed with ether (3×250 mL) and dried under reduced pressure to obtain title compound 70 g (Yield: 83.9%). [0141] IR (cm −1 ): 2983, 2934, 2499, 1688, 1604, 1553, 1509, 1243, 1234, 1120, 830; [0142] 1 H-NMR (δ ppm): 1.63-1.75 (2H, m), 1.89-2.01 (2H, m), 2.11-2.15 (4H, m), 2.34-2.39 (2H, m), 2.80-2.90 (2H, m), 3.17-3.20 (2H, s), 3.21-3.26 (2H, m), 3.43-3.57 (2H, m), 3.69-3.73 (1H, m), 3.90-3.92 (2H, m), 4.15-4.16 (2H, m), 4.20-4.22 (2H, m), 4.48-4.50 (1H, m), 6.97-7.03 (2H, m), 7.51-7.54 (2H, m), 10.57 (1H, bs), 10.78 (1H, bs), 11.11 (1H, bs); [0143] Mass (m/z): 374.2 (M+H) + ; [0144] HPLC: 99.54%; M.P: 249.2-251.5° C.; Salt content: 16.09% (as dihydrochloride); Example 2 Preparation of 2-[4-(1-Cyclobutyl piperidin-4-yloxy)phenylamino]-1-(morpholin-4-yl)ethanone hydrochloride Step (i): Preparation of 2-[4-(1-Cyclobutyl piperidin-4-yloxy)phenylamino]-1-(morpholin-4-yl)ethanone [0145] A mixture of 4-(1-Cyclobutyl piperidin-4-yloxy)aniline (0.5 g, 0.002 moles), 2-Chloro-1-(morpholin-4-yl)ethanone (0.5 g, 0.003) and potassium carbonate (0.56 g, 0.004 moles) in dimethylformamide (25 ml) was stirred at reflux temperature. After completion of reaction, the mixture was concentrated under reduced pressure and the residue was partitioned between ethyl acetate (250 mL) and water (250 mL). The combined organic layers were washed with brine solution, dried over sodium sulfate and concentrated under reduced pressure. The crude compound was purified by flash chromatography (chloroform: triethylamine, 9.5:0.5) to obtain the title compound 0.3 g (Yield: 40%). Step (ii): Preparation of 2-[4-(1-Cyclobutyl piperidin-4-yloxy)phenylamino]-1-(morpholin-4-yl)ethanone hydrochloride [0146] To a stirred solution of 2-[4-(1-Cyclobutyl piperidin-4-yloxy)phenylamino]-1-(morpholin-4-yl)ethanone (0.3 g, 0.804 mmoles) in diethyl ether (20 mL) was treated with 15% methanolic hydrochloride (0.23 mL, 0.965 mmoles). The reaction mass was stirred further for 1 hour at room temperature. The solvent was decanted, the resulting solids were washed with ether (2×10 mL) and dried under reduced pressure to obtain title compound 0.28 g (Yield: 85%). [0147] 1 H-NMR (δ ppm): 1.65-1.75 (2H, m), 1.96-2.01 (2H, m), 2.08-2.17 (4H, m), 2.36-2.37 (2H, m), 2.80-2.90 (2H, m), 3.15-3.19 (1H, m), 3.34-3.48 (5H, m), 3.55-3.67 (4H, m), 4.22-4.26 (3H, m), 4.45-4.48 (1H, m), 4.64-4.68 (1H, m), 6.99-7.01 (2H, d, J=8 Hz), 7.19-7.21 (2H, m), 11.15 (1H, bs); [0148] Mass (m/z): 374.4 (M+H) + Example 3 Preparation of N-[4-(1-Cyclobutyl piperidin-4-yloxy)-2-fluoro phenyl]-2-(morpholin-4-yl)acetamide dihydrochloride Step (i): Preparation of tert-Butyl 4-[3-fluoro-4-(2-(morpholin-4-yl)acetylamino) phenoxy]piperidine-1-carboxylate [0149] A mixture of tert-Butyl 4-[4-(2-Chloro acetylamino)-3-fluoro phenoxy]piperidine-1-carboxylate (3.31 g, 0.0085 moles, obtained in preparation 3), morpholine (0.89 g, 0.01 moles) and potassium carbonate (1.75 g, 0.012 moles) in acetonitrile (30 mL) was stirred for 5 hours at reflux temperature. The mixture was concentrated under reduced pressure and the residue, thus obtained, was partitioned between ethyl acetate (50 mL) and water (50 mL). The resulted aq. Phase was extracted with ethyl acetate (2×50 mL). The combined organic layers were washed with brine solution, dried over sodium sulfate and concentrated. The crude compound was purified by flash chromatography (ethyl acetate:hexane, 3:7) to obtain the title compound 3.1 g (Yield: 83.5%). [0150] 1 H-NMR (δ ppm): 1.47 (9H, s), 1.71-1.75 (2H, m), 1.89-1.92 (2H, m), 2.62-2.64 (4H, t, J=4 Hz), 3.16 (2H, s), 3.30-3.36 (2H, m), 3.65-3.71 (2H, m), 3.77-3.79 (4H, t, J=4 Hz), 4.39-4.42 (1H, m), 6.69-6.71 (2H, d, J=8 Hz), 8.11-8.18 (1H, t, J=8 Hz), 9.27 (1H, s); [0151] Mass (m/z): 438.2 (M+H) + . Step (ii): Preparation of N-[4-(1-Cyclobutyl piperidin-4-yloxy)-2-fluoro phenyl]-2-(morpholin-4-yl)acetamide [0152] To a stirred solution of tert-Butyl 4-[3-fluoro-4-(2-(morpholin-4-yl)acetylamino) phenoxy]piperidine-1-carboxylate (3.1 g, 0.007 moles, obtained in above step) in dichloromethane (25 mL) was added trifluoroacetic acid (8.1 g, 0.071 moles) and stirred reaction mass overnight at room temperature. After completion of reaction, solvent was evaporated under vacuum and the residue, thus obtained, was basified with 10% caustic lye solution. Extracted the reaction mass with ethyl acetate twice, the combined organic layer dried over sodium sulphate and evaporated under reduced pressure. The crude product, thus obtained, was treated with cyclobutanone (0.6 g, 0.008 moles), in ethylene dichloride (30 mL), and stirred for 4 hours at room temperature. Sodium triacetoxyborohydride (3 g, 0.014 moles) was added to reaction mass in a single lot and the mixture was stirred at room temperature for 2 hours. The reaction mixture was quenched in water and basified with lye solution. The layers were separated and the aqueous layer was extracted with dichloromethane twice. The combined organic layers were dried over sodium sulfate, concentrated under vacuum and the residual mass was further purified by flash chromatography (dichloromethane: triethylamine, 9.5:0.5) to obtain the title compound 1.52 g (Yield: 55%). [0153] 1 H-NMR (δ ppm): 1.64-1.68 (3H, m), 1.70-1.73 (2H, m), 1.82-1.91 (4H, m), 1.96-2.05 (4H, m), 2.14-2.15 (2H, m), 2.62-2.64 (4H, m), 3.16 (2H, s), 3.77-3.79 (4H, t, J=4.0 Hz), 4.25-4.26 (1H, m), 6.68-6.70 (2H, m), 8.12-8.16 (1H, t, J=8.0 Hz), 9.20 (1H, bs); [0154] Mass (m/z): 392.2 (M+H) + . Step (iii): Preparation of N-[4-(1-Cyclobutyl piperidin-4-yloxy)-2-fluoro phenyl]-2-(morpholin-4-yl)acetamide dihydrochloride [0155] Methanolic hydrochloride (2.08 ml, 0.009 moles, 15% w/v) was added to a stirred solution of N-[4-(1-Cyclobutyl piperidin-4-yloxy)-2-fluoro phenyl]-2-(morpholin-4-yl) acetamide (1.52 g, 0.004 moles) in diethyl ether (5 vol) and the reaction mass was further stirred for 2-3 hours at room temperature. The solvent was decanted; the resulting solids were washed with ether (2×10 mL) and dried under reduced pressure to obtain the title compound 1.6 g (Yield: 86.2%). [0156] 1 H-NMR (δ ppm): 1.63-1.72 (2H, m), 1.92-2.02 (2H, m), 2.13-2.21 (4H, m), 2.35-2.36 (3H, m), 2.80-2.89 (2H, m), 3.15-3.26 (4H, m), 3.56-3.70 (2H, m), 3.77-3.80 (2H, m), 3.90-3.91 (2H, m), 3.93-4.21 (2H, m), 4.55-4.76 (1H, m), 6.83-6.89 (1H, m), 7.04-7.07 (1H, m), 7.58-7.60 (1H, m), 10.39 (1H, bs), 10.55 (1H, bs), 11.05 (1H, bs); [0157] Mass (m/z): 392.2 (M+H) + . Example 4 Preparation of N-[4-(1-Cyclobutyl piperidin-4-yloxy)benzyl]morpholine-4-yl amide [0158] A solution of morpholine-4-carbonyl chloride (0.45 g, 0.003 moles), 4-(1-Cyclobutyl piperidin-4-yloxy)benzyl amine (0.5 g, 0.002 moles, obtain in preparation 2) and triethylamine (0.4 g, 0.004 moles) in dichloromethane (20 mL) was stirred at room temperature. After completion of reaction, the reaction mass was quenched on to water and extracted with dichloromethane. The combined organic layer was dried over sodium sulphate and concentrated under reduced pressure to obtain crude compound, which was further purified by flash chromatography (ethyl acetate: methanol, 98:2) to afford the title compound 0.45 g (Yield: 60%) [0159] 1 H-NMR (δ ppm): 1.66-1.78 (2H, m), 1.75-1.78 (2H, m), 2.07-2.19 (6H, m), 2.59 (2H, bs), 2.67-2.69 (2H, m), 2.93-2.97 (1H, m), 3.34-3.36 (4H, t, J=4.8), 3.67-3.69 (4H, t, J=4.5) 4.35-4.36 (2H, d, J=5.14), 4.41 (1H, bs) 4.66 (1H, bs), 6.84-6.86 (2H, d, J=8.4) 7.21-7.23 (2H, d, J=8.4); [0160] Mass (m/z): 374.3 (M+H) + . Examples 5-39 [0161] The compounds of Examples 5-39 were prepared by following the procedures as described in Examples 1 to 4, with some non-critical variations [0000] 5. N-[4-(1-Cyclobutyl 1 H-NMR (δ ppm): 1.42-1.87 (6H, m), 1.97-2.05 (8H, m), piperidin-4-yloxy)-3- 2.61-2.63 (4H, t, J = 4.4 Hz), 2.78-2.8 (1H, m), 3.13 (2H, s), 3.76-3.79 (4H, t, J = 4.4 Hz), fluoro phenyl]-2- 4.02 (1H, m), 6.93-6.98 (1H, t, J = 8.8 Hz), 7.11-7.14 (1H, (morpholin-4-yl) d, J = 8.6 Hz), 7.49-7.52 (1H, dd, J = 14.9, 2.4 Hz), 8.99 (1H, bs); acetamide Mass (m/z): 392 (M + H) + . 6. N-[4-(1-Cyclobutyl 1 H-NMR (δ ppm): 1.68-1.82 (6H, m), 2.01-2.05 (4H, m), piperidin-4-yloxy)-2- 2.0-2.1 (2H, m), 2.22 (3H, s), 2.34-2.4 (2H, m), 2.5-2.61 (2H, m), methyl phenyl]-2-(3,3- 2.71-2.73 (1H, m), 2.97-3.01 (2H, t), 3.07-3.13 (2H, t, J = 4.0 Hz), 3.33 (2H, s), difluoro pyrrolidin-1- 4.28 (1H, m), 6.76-6.77 (2H, m), 7.77-7.79 (1H, m), 8.75 (1H, bs); yl) acetamide Mass (m/z): 408 (M + H) + . 7. N-[4-(1-Cyclobutyl 1 H-NMR (δ ppm): 1.42-1.47 (2H, m), 1.62-1.67 (4H, m), piperidin-4-yloxy)-2- 1.72-1.79 (2H, m), 1.78-1.8 (2H, m), 2.0-2.05 (6H, m), 2.25-2.35 (2H, m), trifluoromethyl 2.37-2.55 (4H, m), 2.6-2.64 (2H, m), 2.83-2.86 (1H, m), 3.08 (2H, s), phenyl]-2-(piperidin-1- 4.36-4.38 (1H, m), 7.05-7.08 (1H, dd, J = 9, 2.6 Hz), 7.13-7.14 (1H, d, J = 2.7 Hz), yl) acetamide 8.22-8.24 (1H, d, J = 9 Hz), 9.85 (1H, bs); Mass (m/z): 440 (M + H) + . 8. N-[4-(1-Cyclopentyl 1 H-NMR (δ ppm): 1.45-1.56 (4H, m), 1.69-1.71 (2H, m), piperidin-4-yloxy) 1.86-1.90 (4H, m), 2.03-2.08 (2H, m), 2.41-2.45 (2H, m), 2.61-2.63 (4H, t, J = 4.46 Hz), phenyl]-2-(morpholin- 2.80-2.83 (2H, m), 3.13 (2H, s), 3.58-3.61 (1H, m), 4-yl) acetamide 3.76-3.78 (4H, t, J = 4.5 Hz), 4.13-4.31 (1H, m), 6.87-6.9 (2H, d, J = 8.8 Hz), 7.44-7.46 (2H, d, J = 8.8 Hz), 8.93 (1H, bs); Mass (m/z): 388 (M + H) + . 9. N-[4-(1-Cyclobutyl 1 H-NMR (δ ppm): 1.68-1.73 (2H, m), 1.80-1.90 (4H, m), piperidin-4-yloxy)-2- 1.97-2.06 (4H, m), 2.14-2.18 (2H, m), 2.63-2.65 (6H, m), 2.73-2.75 (1H, m), trifluoromethyl 3.15 (2H, s), 3.76-3.78 (4H, m), 4.32 (1H, m), 7.06-7.09 (1H, m), phenyl]-2-(morpholin- 7.14 (1H, d, J = 2.59 Hz), 8.19-8.21 (1H, d, J = 8.9 Hz), 9.65 (1H, bs); 4-yl) acetamide Mass (m/z): 442 (M + H) + . 10. N-[4-(1-Isopropyl- 1 H-NMR (δ ppm): 1.26-1.28 (6H, d), 1.84-1.87 (4H, m), 2.23 (3H, piperidin-4-yloxy)-2- s), 2.70-2.73 (4H, m), 2.39 (2H, m), 2.87-2.89 (2H, m), methyl phenyl]-2- 2.94-3.01 (5H, m), 3.49 (2H, s), 4.42-4.45 (1H, m), 6.47-6.77 (2H, m), (pyrrolidin-1-yl) 7.81-7.83 (1H, d, J = 9.2 Hz), 9.08 (1H, bs); acetamide Mass (m/z): 360.3 (M + H) + . 11. N-[4-(1-Cyclobutyl 1 H-NMR (δ ppm): 1.64-1.74 (5H, m), 1.85-1.86 (2H, m), piperidin-4-yloxy)-2- 1.87-1.90 (3H, m), 2.06-2.22 (4H, m), 2.22-2.27 (5H, m), 2.60-2.62 (2H, m), methyl phenyl]-2- 2.72-2.77 (5H, m), 3.31 (2H, s), 4.25-4.29 (1H, m), 6.75-6.77 (2H, (pyrrolidin-1-yl) m), 7.79-7.81 (1H, d, J = 8.0 Hz), 9.05 (1H, bs); acetamide Mass (m/z): 372 (M + H) + . 12. N-[4-(1-Cyclopentyl 1 H-NMR (δ ppm): 0.86-0.9 (2H, m), 1.54-1.72 (8H, m), piperidin-4-yloxy)-2- 1.85-1.87 (4H, m), 2.0-2.03 (3H, m), 2.23 (3H, s), 2.24-2.26 (2H, m), methyl phenyl]-2- 2.35-2.65 (6H, m), 2.78-2.80 (2H, m), 3.10 (2H, s), 4.12-4.28 (1H, m), (piperidin-1-yl) 6.76-6.78 (2H, m), 7.9-7.92 (1H, d, J = 8.8 Hz), 9.23 (1H, bs); acetamide Mass (m/z): 400 (M + H) + . 13. N-[4-(1-Cyclobutyl 1 H-NMR (δ ppm): 0.86-0.9 (2H, m), 1.49-1.50 (2H, m), piperidin-4-yloxy)-2- 1.61-2.01 (12H, m), 2.15-2.17 (2H, m), 2.25 (3H, s), 2.55-2.57 (6H, m), methyl phenyl]-2- 2.67-2.77 (1H, m), 3.10 (2H, s), 4.10-4.28 (1H, m), 6.75-6.78 (2H, m), (piperidin-1-yl) 7.89-7.91 (1H, d, J = 8.8 Hz), 9.23 (1H, bs); acetamide Mass (m/z): 386 (M + H) + . 14. N-[4-(1-Cyclobutyl 1 H-NMR (δ ppm): 1.67-1.74 (3H, m), 2.02-2.05 (7H, m), piperidin-4-yloxy) 2.19-2.21 (2H, m), 2.38-2.4 (3H, m), 2.63-2.65 (2H, m), 2.75-2.84 (2H, m), phenyl]-N-methyl-2- 2.90 (2H, s), 3.22 (3H, s), 3.68-3.70 (4H, m), 4.30-4.34 (1H, m), (morpholin-4-yl) 6.90-6.92 (2H, d, J = 8 Hz), 7.08-7.10 (2H, m); acetamide Mass (m/z): 388 (M + H) + . 15. N-[4-(1-Cyclopentyl 1 H-NMR (δ ppm): 1.13-1.15 (3H, d, J = 6.0 Hz), 1.42-1.46 (2H, m), piperidin-4-yloxy)-2- 1.54-1.57 (4H, m), 1.69-1.69 (2H, m), 1.78-1.86 (6H, m), methyl phenyl]-2-(R-2- 1.97-2.02 (2H, m), 2.22 (3H, s), 2.31-2.34 (2H, m), 2.39-2.44 (1H, m), methyl pyrrolidin-1-yl) 2.52-2.67 (2H, m), 2.7-2.79 (2H, m), 3.06-3.1 (1H, d, J = 16.9 Hz), acetamide 3.21-3.25 (1H, m), 3.45-3.49 (1H, d, J = 16.9 Hz), 4.23-4.27 (1H, m), 6.76-6.88 (2H, m), 7.84-6.86 (1H, d, J = 8.5 Hz), 9.21 (1H, bs); Mass (m/z): 400 (M + H) + . 16. N-[4-(1-Cyclobutyl 1 H-NMR (δ ppm): 1.13-1.14 (4H, d, J = 6.0 Hz), 1.67-1.82 (6H, m), piperidin-4-yloxy)-2- 1.89-2.06 (10H, m), 2.1-2.15 (2H, m), 2.22 (3H, s), 2.43-2.63 (2H, methyl phenyl]-2-(R-2- m), 3.06-3.1 (1H, d, J = 16.9 Hz), 3.20-3.23 (1H, m), 3.44-3.49 (1H, methyl pyrrolidin-1-yl) d, J = 16.9 Hz), 4.22-4.27 (1H, m), 6.75-6.78 (2H, m), acetamide 7.83-6.86 (1H, d, J = 8.7 Hz), 9.21 (1H, bs); Mass (m/z): 386 (M + H) + . 17. N-[4-(1-Cyclobutyl 1 H-NMR (δ ppm): 1.65-1.78 (2H, m), 1.91-1.94 (2H, m), piperidin-4-yloxy)-2- 2.08-2.17 (6H, m), 2.51-2.54 (2H, m), 2.62-2.64 (4H, t), 2.70-2.72 (2H, m), methoxy phenyl]-2- 2.92-2.96 (1H, m), 3.14 (2H, s), 3.77-3.85 (4H, t), 3.88 (3H, s), (morpholin-4-yl) 4.3-4.39 (1H, m), 6.46-6.49 (2H, m), 8.20-8.22 (1H, d, J = 9.2 Hz), acetamide 9.54 (1H, bs); Mass (m/z): 404 (M + H) + . 18. N-[4-(1-Cyclobutyl 1 H-NMR (δ ppm): 1.6-1.73 (9H, m), 2.02-2.06 (6H, m), piperidin-4-yloxy)-2- 2.17-2.19 (2H, m), 2.42-2.46 (2H, m), 2.58-2.61 (2H, m), 2.74-2.77 (1H, m), trifluoromethyl 2.84-2.87 (2H, m), 3.14 (2H, s), 3.79 (1H, m), 4.30-4.33 (1H, m), phenyl]-2-(4-hydroxy 7.06-7.09 (1H, dd, J = 12.0, 2.4 Hz), 7.14-7.15 (1H, d, J = 2.8 Hz), piperidin-1-yl) 8.22-8.23 (1H, d, J = 12 Hz), 9.74 (1H, bs); acetamide Mass (m/z): 456 (M + H) + . 19. N-[4-(1-Cyclobutyl 1 H-NMR (δ ppm): 1.66-1.76 (4H, m), 1.87-1.97 (4H, m), piperidin-4-yloxy) 2.03-2.05 (6H, m), 2.38-2.43 (4H, m), 2.64-2.65 (2H, m), 2.86-2.95 (4H, m), phenyl]-2-(4-hydroxy 3.11 (2H, s), 3.77-3.80 (1H, m), 4.30-4.33 (1H, m), 6.86-6.89 (2H, piperidin-1-yl) dd), 7.44-7.46 (2H, dd), 9.04 (1H, bs); acetamide Mass (m/z): 388 (M + H) + 20. N-[4-(1-Cyclopentyl 1 H-NMR (δ ppm): 1.53-1.55 (2H, m), 1.73-1.79 (4H, m), piperidin-4-yloxy)-2- 2.01-2.04 (5H, m), 2.09-2.21 (2H, m), 3.04-3.07 (2H, m), 3.20-3.37 (4H, m), fluoro phenyl]-2- 3.52-3.55 (2H, m), 3.80-3.97 (4H, m), 4.23 (2H, m), 4.58-4.60 (1H, (morpholin-4-yl) m), 6.85-6.94 (1H, m), 7.05-7.11 (1H, m), 7.59-7.63 (1H, m), acetamide 10.4 (1H, bs), 10.5 (1H, bs), 10.67 (1H, bs); dihydrochloride Mass (m/z): 406.2 (M + H) + . 21. N-[4-(1-Cyclobutyl 1 H-NMR (δ ppm): 1.65-1.72 (4H, m), 1.72-1.87 (8H, m), piperidin-4-yloxy)- 2.03-2.14 (2H, m), 2.62-2.65 (2H, m), 2.69-2.75 (7H, m), 3.26 (2H, s), phenyl]-2-(pyrrolidin- 4.25-4.27 (1H, m), 6.87-6.89 (2H, dd), 7.45-7.47 (2H, dd), 8.97 (1H, bs); 1-yl) acetamide Mass (m/z): 358 (M + H) + . 22. N-[4-(1-Isopropyl 1 H-NMR (δ ppm): 1.06-1.08 (6H, d, J = 6.48 Hz), 1.63 (2H, m), piperidin-4-yloxy)- 1.80-1.84 (2H, m), 2.01-2.02 (2H, m), 2.40 (2H, m), 2.61-2.64 (4H, t, J = 4.5 Hz), phenyl]-2-(morpholin- 3.13 (2H, s), 4.35 (1H, m), 3.77-3.79 (4H, t, J = 4.5 Hz), 4-yl) acetamide 4.26-4.27 (1H, m), 6.88-6.90 (2H, d, J = 8.8 Hz), 7.44-7.46 (2H, d, J = 8.8 Hz), 8.92 (1H, bs); Mass (m/z): 362.3 (M + H) + . 23. N-[4-(1-Cyclopropyl 1 H-NMR (δ ppm): 0.76-0.78 (2H, m), 1.13 (2H, m), 1.93-1.99 (2H, piperidin-4-yloxy) m), 2.16-2.19 (2H, m), 3.33-3.39 (6H, m), 3.42-3.44 (3H, m), phenyl]-2-(morpholin- 3.76-3.77 (2H, m), 3.80-3.83 (2H, m), 4.18 (2H, m), 4.51 (1H, m), 4-yl) acetamide 6.97-6.05 (2H, dd), 7.52-7.56 (2H, dd), 8.92 (1H, bs); Mass (m/z): 360.3 (M + H) + . 24. N-[4-(1-Cyclobutyl 1 H-NMR (δ ppm): 1.17-1.19 (6H, d, J = 6.54 Hz), 1.61-1.63 (3H, m), piperidin-4-yloxy) 1.90-1.98 (8H, m), 2.30-2.35 (2H, m), 2.49-2.55 (2H, m), phenyl]-2-(4- 2.70-2.72 (2H, m), 2.91-2.94 (2H, m), 3.01-3.07 (4H, m), 3.15-3.19 (5H, m), isopropyl[1,4]diazepan- 4.30-4.33 (1H, m), 6.88-6.99 (2H, dd, J = 8.9 Hz), 7.49-7.51 (2H, dd, 1-yl) acetamide J = 8.8 Hz), 8.95 (1H, bs); Mass (m/z): 429.1 (M + H) + . 25. N-[4-(1-Cyclobutyl 1 H-NMR (δ ppm): 1.68-1.72 (3H, m), 1.89-1.97 (3H, m), piperidin-4-yloxy) 2.13-2.19 (5H, m), 2.33-2.36 (2H, m), 2.80-2.86 (3H, m), 3.07-3.10 (1H, m), phenyl]-2-(2- 3.17-3.20 (3H, m), 3.69-3.72 (1H, m), 3.82-3.85 (2H, m), hydroxymethyl 3.99-4.01 (1H, m), 4.03 (1H, m), 4.48-4.51 (1H, m), 4.70 (1H, m), morpholin-4-yl) 6.97-7.03 (2H, dd), 7.51-7.54 (2H, dd), 8.83 (1H, bs); acetamide Mass (m/z): 404.5 (M + H) + . 26. N-[4-(1-Cyclobutyl 1 H-NMR (δ ppm): 1.63-1.68 (3H, m), 1.83-1.87 (1H, m), piperidin-4-yloxy) 1.97-2.02 (3H, m), 2.13-2.16 (3H, m), 2.30-2.35 (3H, m), 2.78-2.89 (4H, m), phenyl]-3-(morpholin- 3.06-3.09 (3H, m), 3.17-3.20 (2H, m), 3.58-3.61 (3H, m), 4-yl) propionamide 3.94-3.97 (2H, m), 4.67 (1H, m), 6.92-6.99 (2H, dd, J = 8.8 Hz), 7.49-7.51 (2H, dd, J = 8.8 Hz), 8.85 (1H, bs); Mass (m/z): 388.2 (M + H) + . 27. N-[4-(1-Cyclopentyl 1 H-NMR (δ ppm): 1.17-1.23 (2H, m), 1.31-1.32 (2H, m), piperidin-4-yloxy) 1.71-1.72 (9H, m), 1.74-1.77 (4H, m), 1.98-2.01 (2H, m), 3.01-3.06 (4H, m), phenyl]-2-(piperidin-1- 3.38-3.40 (4H, m), 4.06-4.07 (2H, m), 4.50-4.52 (1H, m), yl) acetamide 6.97-7.03 (2H, m), 7.50-7.54 (2H, m), 9.7 (1H, bs), 10.48 (1H, bs), 10.48 (1H, dihydrochloride bs); Mass (m/z): 386.5 (M + H) + . 28. N-[4-(1-Cyclopentyl 1 H-NMR (δ ppm): 1.52-1.60 (3H, m), 1.71-1.75 (2H, m), piperidin-4-yloxy) 1.80-1.81 (3H, m), 1.98-2.00 (8H, m), 2.97-3.11 (6H, m), 3.58-3.60 (3H, m), phenyl]-2-(pyrrolidin- 4.21 (2H, s), 4.49-4.54 (1H, m), 6.96-7.03 (2H, dd, J = 8.0 Hz), 1-yl) acetamide 7.52-7.52 (2H, dd, J = 8 Hz), 8.86 (1H, bs), 10.31 (1H, bs), 10.77 (1H, bs), dihydrochloride 10.99 (1H, bs); Mass (m/z): 372.1 (M + H) + . 29. N-[4-(1-Cyclobutyl 1 H-NMR (δ ppm): 1.68-1.73 (2H, m), 1.77-1.90 (4H, m), piperidin-4-yloxy) 2.01-2.13 (2H, m), 2.15-2.19 (4H, m), 2.33-2.37 (2H, m), 2.83-2.90 (2H, m), phenyl]-2-(piperidin-1- 3.01-3.03 (2H, m), 3.04-3.06 (2H, m), 3.17-3.20 (2H, m), yl) acetamide 3.34-3.39 (2H, m), 3.57-3.70 (1H, m), 4.07 (2H, s), 4.48-4.50 (1H, m), 6.97-7.03 (2H, dd, J = 12.0 Hz), 7.51-7.54 (2H, dd, J = 12.0 Hz), 8.93 (1H, bs); Mass (m/z): 372.4 (M + H) + . 30. N-[4-(1-Cyclobutyl 1 H-NMR (δ ppm): 1.68-1.73 (3H, m), 1.88-1.90 (3H, m), piperidin-4-yloxy)-2- 2.02-2.03 (5H, m), 2.39-2.40 (2H, m), 2.91-2.99 (2H, m), 3.06-3.10 (2H, m), trifluoromethyl 3.15-3.38 (2H, m), 3.55-3.58 (2H, m), 3.74-3.85 (2H, m), 4.23 (2H, phenyl]-2-(pyrrolidin- s), 4.70-4.71 (1H, m), 7.31-7.33 (1H, d, J = 8.0 Hz), 7.36-7.42 (2H, 1-yl) acetamide m), 9.51 (1H, bs), 10.29 (1H, bs), 10.36 (1H, bs), 11.35 (1H, bs); dihydrochloride Mass (m/z): 426.1 (M + H) + . 31. N-[4-(1-Cyclobutyl 1 H-NMR (δ ppm): 1.66-1.75 (7H, m), 1.87-1.88 (2H, m), piperidin-4-yloxy) 2.05-2.09 (6H, m), 2.43-2.48 (7H, m), 2.67 (2H, bs), 3.65-3.67 (4H, t, J = 4.4 Hz), phenyl]-N-(2- 3.78-3.81 (2H, t), 4.4 (1H, m), 6.89-6.91 (2H, d, J = 8.7 Hz), morpholin-4-yl ethyl) 7.10-7.13 (2H, d, J = 8.7 Hz); acetamide Mass (m/z): 402.4 (M + H) + . 32. [4-(1-Cyclobutyl 1 H-NMR (δ ppm): 1.64-1.72 (2H, m), 1.77-1.93 (6H, m), piperidin-4-yloxy) 2.02-2.05 (2H, m), 2.07-2.08 (2H, m), 2.47-2.5 (4H, m), 2.61-2.63 (4H, m), phenyl]-(2-morpholin- 2.70-2.74 (1H, m), 3.11-3.13 (2H, t), 3.71-3.73 (4H, t), 4.10 (1H, m), 4-yl ethyl) amine 6.57-6.60 (2H, d, J = 8.7 Hz), 6.79-6.82 (2H, d, J = 8.7 Hz); Mass (m/z): 360.4 (M + H) + . 33. N-[4-(1-Cyclobutyl 1 H-NMR (δ ppm): 1.81-1.91 (5H, m), 2.05-2.16 (5H, m), piperidin-4-yloxy) 2.30-2.35 (4H, m), 2.72-2.74 (1H, m), 3.05-3.17 (4H, m), 3.31-3.35 (2H, m), phenyl]-2-(R-2- 3.43-3.47 (1H, m), 3.62-3.71 (3H, m), 3.83-3.87 (1H, m), 4.40 (2H, hydroxymethyl s), 4.63-4.66 (1H, m), 6.97-6.99 (2H, dd, J = 8.2, 2.04 Hz), pyrrolidin-1-yl) 7.51-7.53 (2H, dd, J = 8.2, 2.00 Hz); acetamide L (+) Mass (m/z): 388.3 (M + H) + . tartarate 34. N-[2-(1-Cyclobutyl 1 H-NMR (δ ppm): 1.66-1.73 (6H, m), 1.89 (2H, m), 1.97-2.18 (6H, piperidin-4-yloxy) m), 2.42-2.48 (6H, m), 2.76 (2H, bs), 2.98-3.03 (2H, m), pyridin-5-yl]-N-[2- 3.60-3.66 (4H, m), 3.77-3.80 (2H, t), 4.55 (1H, m), 6.74-6.76 (1H, d, J = 8.6 Hz), (morpholin-4-yl) ethyl] 7.46-7.48 (1H, dd, J = 8.6, 2.6 Hz), 8.01-8.02 (1H, d, J = 2.4 Hz); acetamide Mass (m/z): 403.3 (M + H) + . 35. N-[2-(1-Cyclobutyl 1 H-NMR (δ ppm): 1.63-1.66 (8H, m), 1.81-1.83 (3H, m), piperidin-4-yloxy) 2.03-2.06 (6H, m), 2.18-2.13 (4H, m), 2.54-2.55 (4H, m), 3.08 (2H, s), 5.03 (1H, pyridin-5-yl]-2- m), 6.70-6.72 (1H, d, J = 8.8 Hz), 7.92-7.95 (1H, dd, J = 8.8, 2.6 Hz), (piperidin-1-yl) 8.18-8.19 (1H, d, J = 2.6 Hz), 9.15 (1H, bs); acetamide Mass (m/z): 373.3 (M + H) + . 36. N-[2-(1-Cyclobutyl 1 H-NMR (δ ppm): 1.51-1.95 (12H, m), 2.43-2.65 (7H, m), 3.06 (2H, piperidin-4-yloxy) s), 3.60-3.79 (4H, m), 5.22 (1H, m), 6.70-6.73 (1H, d, J = 8.8 Hz), pyridin-5-yl]-2- 7.98-8.00 (1H, dd, J = 8.5 Hz, 2.4 Hz), 8.16-8.18 (1H, d, J = 2.4 Hz), (morpholin-4-yl) 8.97 (1H, bs); acetamide Mass (m/z): 375.4 (M + H) + . 37. N-[4-(1-Cyclobutyl 1 H-NMR (δ ppm): 1.63-1.76 (7H, m), 1.85-1.89 (2H, m), piperidin-4-yloxy)-2- 2.05-2.09 (6H, m), 2.43-2.48 (7H, m), 2.67 (2H, bs), 3.65-3.67 (4H, t, J = 4.4 Hz), fluoro phenyl]-N-[2- 3.78-3.81 (2H, t), 4.4 (1H, m), 6.89-6.91 (2H, m), 7.10-7.8 (1H, (morpholin-4-yl)-ethyl] m); acetamide Mass (m/z): 420.4 (M + H) + . 38. N-[4-(1-Cyclopropyl 1 H-NMR (δ ppm): 0.81-0.85 (4H, m), 1.83 (3H, s), 1.90-2.02 (2H, piperidin-4-yloxy) m), 2.10-2.2 (2H, m), 2.40-2.50 (1H, m), 2.66-2.69 (6H, m), phenyl]-N-[2- 3.18-3.22 (2H, m), 3.36-3.39 (2H, m), 3.70-3.73 (4H, m), 3.86-3.90 (2H, (morpholin-4-yl) ethyl] m), 4.60-4.70 (1H, m) 7.07-7.09 (2H, d, J = 8.7 Hz), 7.26-7.28 (2H, acetamide L(+) d, J = 8.7 Hz); tartarate Mass (m/z): 388.4 (M + H) + . 39. N-[4-(1-Cyclobutyl 1 H-NMR (δ ppm): 1.69-1.74 (3H, m), 1.76-1.80 (3H, m), piperidin-4-yloxy) 2.01-2.10 (4H, m), 2.12 (3H, s), 2.59-2.64 (8H, m), 2.75-2.80 (1H, m), phenyl]-2-(1-acetyl 3.17 (2H, s), 3.53-3.56 (2H, m), 3.6-3.65 (2H, m), 4.3-4.4 (1H, m), piperazin-4-yl) 6.88-6.9 (2H, d, J = 8.88 Hz), 7.44-7.46 (2H, d, J = 8.84 Hz), 8.8 (1H, bs); acetamide Mass (m/z): 415.2 (M + H) + . Examples-40-51 [0162] The person skilled in the art can prepare the compounds of Examples-40-51 by following the procedures described above. [0000] 40. N-[4-(1-Cyclobutyl piperidine-4-yloxy)-2-methyl phenyl]-2-(4-hydroxy piperidine-1-yl) acetamide 41. N-[4-(1-Cyclopropyl piperidin-4-yloxy) phenyl]-2-(R-2-hydroxymethyl pyrrolidin-1-yl) acetamide 42. N-[4-(1-Cyclobutyl piperidin-4-yloxy) benzyl]-2-(morpholin-4-yl) acetamide 43. N-[4-(1-Cyclobutyl piperidin-4-yloxy)-2-fluoro benzyl]-2-(morpholin-4-yl) acetamide 44. N-[4-(1-Cyclobutyl piperidin-4-yloxy) phenyl]-2-(3-hydroxy azetidin-1-yl) acetamide 45. N-[4-(1-Cyclobutyl piperidin-4-yloxy)-2-fluoro phenyl]-2-(3-methoxy azetidin-1-yl) acetamide 46. N-[4-(1-Cyclobutyl piperidin-4-yloxy)-2-fluoro phenyl]-2-(2-hydroxymethyl pyrrolidin-1-yl) acetamide 47. N-[2-Chloro-4-(1-cyclobutyl piperidin-4-yloxy) phenyl]-2-(morpholin-4-yl) acetamide 48. N-[2-Chloro-4-(1-cyclobutyl piperidin-4-yloxy) phenyl]-2-(piperidin-1-yl) acetamide 49. N-[4-(1-Cyclobutyl piperidin-4-yloxy) phenyl]-2-(tetrahydro pyran-4-yloxy) acetamide 50. 2-[4-(1-Cyclobutyl piperidin-4-yloxy)-2-fluoro phenylamino]-1-(morpholin-4-yl) ethanone 51. N-[4-(1-Cyclobutyl piperidin-4-yloxy)-2-fluoro phenyl]-N-(2-morpholin-4-yl ethyl) acetamide Biological Assays Example 52 Binding and Functional Assays for Human or Rat Histamine H3 Receptor [0163] Compounds can be evaluated according to the following procedures. Materials and Methods: [0000] Receptor source: Rat brain frontal cortex or recombinant human cDNA expressed in CHO cells Radioligand: [ 3 H] R-α-methylhistamine Final ligand concentration—[3.0 nM] Non-specific determinant: R-α-methylhistamine (100 uM) Reference compound: R-α-methylhistamine Positive control: R-α-methylhistamine Incubation conditions: [0170] Increasing concentrations of test compounds or standard were incubated with membrane receptors and radioligand in 5 mM MgCl 2 and 50 mM TRIS-HCl (pH 7.4) for 60 minutes at room temperature. The reaction was terminated by rapid vacuum filtration onto the glass fiber filters. Radioactivity trapped onto the filters was determined and compared to the control values in order to ascertain any interactions of the test compound(s) with either cloned human or rat receptor binding site. [0000] Example Number K i (nM) 1. 8.7 2. 6.4 3. 14.9 7. 14.8 10. 8.4 11. 1.9 12. 7.5 13. 3.3 14. 4.9 15. 4 16. 2.4 19. 6.4 21. 1.1 22. 8.3 24. 1.0 25. 4.05 26. 6.7 27. 4.1 28. 3.8 29. 1.6 37. 9.73 38. 6.6 39 5.39 LITERATURE REFERENCE [0000] Millipore Data Sheet Example 53 Rodent Pharmacokinetic Study [0172] Male Wistar rats (230-280 grams) obtained from NIN (National Institute of Nutrition, Hyderabad, India) were used as an experimental animal. Three animals were housed in each cage. Animals were kept fasted over night and maintained on a 12 hours light/dark cycle. Three rats were dosed New chemical entity (NCE) orally (3 or 10 mg/kg) and intravenously (1 or 5 mg/kg) on day 0 and day 2. [0173] At each time point blood was collected by jugular vein. Blood was stored at 2-8° C. until analysis. The concentrations of the NCE compound in blood were determined using LC-MS/MS method. Schedule time points: Pre dose 0.08, 0.25, 0.5, 1, 2, 4, 6, 8 and 24 hours after dosing (n=3). The NCE compounds were quantified in blood by partially validated LC-MS/MS method using acetonitrile precipitation technique. NCE compounds were quantified in the calibration range of 1-2000 ng/mL in blood. Study samples were analyzed using calibration samples in the batch and quality control samples spread across the batch. [0174] Pharmacokinetic parameters were calculated by non-compartmental model using software WinNonlin version 5.0.1. [0000] Example Dose Route of C max\ T max AUC t T 1/2 Bioavailability Number Strain/Gender (mg/kg) Vehicle administration (ng/mL) (h) (ng · hr/mL) (h) (%) 1. Wistar/Male 1 Water Intravenous 263 ± 21 1.45 ± 0.24 79 ± 11 3 Water Per Oral 349 ± 35 0.42 ± 0.14  626 ± 118 1.53 ± 0.41 3. Wistar/Male 1 Water Intravenous 173 ± 60 0.56 ± 0.19 35 ± 5  3 Water Per Oral 129 ± 34 0.42 ± 0.14 174 ± 43 1.46 ± 0.75 11. Wistar/Male 5 Water Intravenous 3345 ± 656 26.31 ± 5.17  20 ± 9  10 Water Per Oral 122 ± 55  4.0 ± 1.76 1349 ± 569 10.75 ± 1.92  19. Wistar/Male 1 Water Intravenous 347 ± 44 17.00 ± 4.50  81 ± 12 3 Water Per Oral  67 ± 11 2.67 ± 1.15 838 ± 96 12.83 ± 2.48  22. Wistar/Male 1 Water Intravenous 340 ± 60 2.04 ± 0.45 85 ± 12 3 Water Per Oral 376 ± 27 0.42 ± 0.14 850 ± 61 2.47 ± 0.26 23. Wistar/Male 1 Water Intravenous 338 ± 29 1.13 ± 0.02 55 ± 10 3 Water Per Oral 389 ± 29 0.50 ± 0.00  556 ± 111 1.23 ± 0.53 37. Wistar/Male 1 Water Intravenous 68 ± 2 3.30 ± 0.42 32 ± 8  3 Water Oral  27 ± 11 0.50 ± 0.00  64 ± 16 3.59 ± 0.43 Example 54 Rodent Brain Penetration Study [0175] Male Wister rats (230-280 grams) obtained from NIN (National Institute of Nutrition, Hyderabad, India) was used as experimental animals. Three animals were housed in each cage. Animals were given water and food ad libitum throughout the experiment, and maintained on a 12 hours light/dark cycle. [0176] New chemical entity (NCE) was dissolved in suitable vehicle and administered orally (3 or 10 mg/kg). Around T max (i.e, 0.5 hour, 1.0 hour and 2.0 hours) animals were sacrificed. Blood and brain tissue were collected and brain was homogenized to yield 20% w/v. Blood was stored at 2-8° C. and brain homogenate was frozen at −20° C. until analysis. The concentrations of NCE in blood and brain were quantified using LC-MS/MS method. [0177] The NCE was quantified in blood and brain homogenate by partially validated LC-MS/MS method using acetonitrile precipitation technique. NCE compounds were quantified in the calibration range of 1-500 ng/mL in blood and brain homogenate. Study samples were analyzed using calibration samples in the batch and quality control samples spread across the batch. Extents of brain-blood ratio were calculated (C brian /C blood ) [0000] Brain Penetration Example Strain/ Dose Route of Ratio Number Gender (mg/kg) Vehicle administration (C brain /C blood ) 1. Wistar/ 3 Water Per Oral 0.93 ± 0.05 Male 3. Wistar/ 3 Water Per Oral 2.07 ± 0.07 Male 37. Wistar/ 3 Water Per Oral 1.24 ± 0.18 Male Example 55 Object Recognition Task Model [0178] The cognition enhancing properties of compounds of this invention were estimated by using this model. [0179] Male Wister rats (230-280 grams) obtained from N. I. N. (National Institute of Nutrition, Hyderabad, India) was used as experimental animals. Four animals were housed in each cage. Animals were kept on 20% food deprivation before one day and given water ad libitum throughout the experiment and maintained on a 12 hours light/dark cycle. Also the rats were habituated to individual arenas for 1 hour in the absence of any objects. [0180] One group of 12 rats received vehicle (1 mL/Kg) orally and another set of animals received compound of the formula (I) either orally or i.p., before one hour of the familiar (T1) and choice trial (T2). [0181] The experiment was carried out in a 50×50×50 cm open field made up of acrylic. In the familiarization phase, (T1), the rats were placed individually in the open field for 3 minutes, in which two identical objects (plastic bottles, 12.5 cm height×5.5 cm diameter) covered in yellow masking tape alone (a1 and a2) were positioned in two adjacent corners, 10 cms from the walls. After 24 hours of the (T1) trial for long-term memory test, the same rats were placed in the same arena as they were placed in T1 trial. Choice phase (T2) rats were allowed to explore the open field for 3 minutes in presence of one familiar object (a3) and one novel object (b) (Amber color glass bottle, 12 cm high and 5 cm in diameter). Familiar objects presented similar textures, colors and sizes. During the T1 and T2 trial, explorations of each object (defined as sniffing, licking, chewing or having moving vibrissae whilst directing the nose towards the object at a distance of less than 1 cm) were recorded separately by stopwatch. Sitting on an object was not regarded as exploratory activity, however, it was rarely observed. [0000] T1 is the total time spent exploring the familiar objects (a1+a2). T2 is the total time spent exploring the familiar object and novel object (a3+b). [0182] The object recognition test was performed as described by Ennaceur, A., Delacour, J., 1988, A new one-trial test for neurobiological studies of memory in rats—Behavioural data, Behay. Brain Res., 31, 47-59. [0000] Exploration time Example mean ± S.E.M (sec) Number Dose mg/kg, p.o. Familiar object Novel object Inference 1. 0.3 mg/kg   5.56 ± 0.81 15.36 ± 1.74 Active 3. 3 mg/kg 6.77 ± 0.44 12.49 ± 1.59 Active 22. 1 mg/kg 7.12 ± 1.51 16.50 ± 2.37 Active 37. 3 mg/kg 5.53 ± 1.67 14.18 ± 2.04 Active Example 56 Morris Water Maze [0183] The cognition enhancing properties of compounds of this invention were estimated by using this model. [0184] The water maze apparatus consisted of a circular pool (1.8 m diameter, 0.6 m high) constructed in black Perspex (TSE systems, Germany) filled with water (24±2° C.) and positioned underneath a wide-angled video camera to track animal. The 10 cm 2 perspex platform, lying 1 cm below the water surface, was placed in the centre of one of the four imaginary quadrants, which remained constant for all rats. The black Perspex used in the construction of the maze and platform offered no intramaze cues to guide escape behavior. By contrast, the training room offered several strong extramaze visual cues to aid the formation of the spatial map necessary for escape learning. An automated tracking system, [Videomot 2 (5.51), TSE systems, Germany] was employed. This program analyzes video images acquired via a digital camera and an image acquisition boards that determined path length, swim speed and the number of entries and duration of swim time spent in each quadrant of the water maze. [0000] Reversal of Scopolamine Induced Example Number amnesia 1. ≦1 mg/kg, p.o. Example 57 Inhibition of Food Intake [0185] The anti-obesity properties of compounds of this invention were estimated using this model. [0186] The experiment consisted of 6 days. The rats were adapted to the 18 hours fasting and 6 hours feeding pattern. The animals were housed in a group of three in the cages provided with the fasting grills and was fasted for 18 hours. After 18 hours fasting the rats were separated and placed individually in the cage. Weighed amount of feed was provided to rats for 6 hours and the feed intake at 1 hour, 2 hours, 4 hours and 6 hours was measured. [0187] Again the rats were regrouped and fasted for 18 hours. The above procedure was followed for 5 days. The average cumulative food intake by the rats on the last 3 days was calculated. Animals were randomized on the basis of their previous three days food intake. On the day of experiment the rats were orally treated test compounds or vehicle. After 60 minutes, the feed was provided to the rats and the food intake at 1 hour, 2 hours, 4 hours and 6 hours was measured. The food intake by the rats treated with test compound was compared with the vehicle treated group by using Unpaired Student's t test. [0000] Example Number Inhibition of food intake 13.    30 mg/kg, p.o. 16. ≧30 mg/kg, p.o. 21. ≧30 mg/kg, p.o. 22.    60 mg/kg, p.o.

The present invention relates to novel compounds of formula (I), and their pharmaceutically acceptable salts and compositions containing them. The present invention also relates to a process for the preparation of above said novel compounds, and their pharmaceutically acceptable salts. The compounds of formula (I) are useful in the treatment of various disorders that are related to Histamine H 3 receptors.

This is a division of application Ser. No. 07/196,996, filed May 20, 1988, now U.S. Pat. No. 4,950,684. BACKGROUND OF THE INVENTION A. Field Of The Invention This invention relates to novel compounds of Formula I having a 2,2-di-substituted chromanonyl (benzopyran) ring-structure which are antagonists of leukotriene D 4 (LTD 4 ) and the slow reacting substance of anaphylaxis (SRS-A). In particular, the compounds of this invention are useful as pharmaceutical agents to prevent or alleviate the symptoms associated with LTD 4 , such as allergic reactions and inflammatory conditions. LTD 4 is a product of the 5-lipoxygenase pathway and is the major active constitutent of slow reacting substance of anaphylaxis (SRS-A), a potent bronchoconstrictor that is released during allergic reactions. See R. A. Lewis and K. F. Austen, Nature, 293, 103-108 (1961). When administered to humans and guinea pigs, LTD 4 causes bronchoconstriction by two mechanisms: (1) directly, by stimulating smooth muscle; and (2) indirectly, through release of thromboxin A 2 which then causes contraction of respiratory smooth muscle. Because antihistamines are ineffective in the management of asthma, SRS-A and not histamine is believed to be a mediator of the bronchoconstriction occurring during an allergic attack. LTD 4 may also be involved in other inflammatory conditions such as rheumatoid arthritis. Furthermore, LTD 4 is a potent coronary vasoconstrictor and influences contractile force in the myocardium and coronary flow rate of the isolated heart. See F. Michelassi, et al., Science, 217, 841 (1982); J. A. Burke, et al., J. Pharmacol. and Exp. Therap., 221, 235 (1982). B. Prior Art Appleton, et al., J. Med. Chem., 20, 371-379 (1977) discloses a series of chromone-2-carboxylic acids having a single substituent in the 2-position, which are antagonists of SRS-A. Specifically, sodium 7-[3-(4-acetyl-3-hydroxy-2-propylphenoxy)-2-hydroxypropoxy]-4-oxo-8-propyl-4H-1-benzopyran-2-carboxylate (FPL 55712), appears to be the first reported specific antagonist of SRS-A and LTD 4 . Miyano, et al., (U.S. Pat. No. 4,546,194) discloses substituted chromanon-2-yl alkanols and derivatives thereof which are useful as LTD 4 inhibitors. In Miyano, the LTD 4 inhibitors have two substituents at the two position of their chromane ring, one of which is alkyl. Moreover, Miyano discloses a diether at position 7 which has 4-acetyl-3-hydroxy-2-propylphenoxy as the substitutent at its terminus. Similar references disclosing chromane compounds which are useful as LTD 4 antagonists are the following: European Patent Application Nos. 0079637, 129,906, and 150,447; U.S. Pat. No. 4,565,882; Japanese patent 60/42378; and C. A. 103(19) 160 389 G. SUMMARY OF THE INVENTION This invention encompasses a compound of the formula: ##STR8## or a pharmaceutically acceptable addition salt thereof, wherein R 1 is methyl, phenyl, ##STR9## wherein X 1 and X 2 may be the same or different and are hydrogen, --Cl, --Br, --CF 3 , --NH 2 , --NO 2 , or straight or branched chain alkyl of 1-3 carbon atoms; wherein m is an integer from 1-9; wherein n is an integer from 1-5; wherein V is >C═O, --CH(OH)--, or --CH 2 --; wherein W is hydrogen or straight or branched chain alkyl of 1-6 carbon atoms; wherein Y is hydrogen or --COCH 3 ; wherein Z is --CHO, --COOR 2 , --COR 3 , ##STR10## or CH 2 OR 4 with the proviso that when one Z moiety of Formula I is COOR 2 , the other Z moiety may optionally be COR 3 ; wherein R 2 is hydrogen, a pharmaceutically acceptable cation, straight or branched chain alkyl having 1-6 carbon atoms, ##STR11## or --CH(CH 2 OR 5 ) 2 with the proviso that when Z is --COOR 2 , the R 2 substituent in one --COOR 2 moiety may be the same or different from the R 2 substituent in the other COOR 2 moiety; wherein R 3 is ##STR12## and wherein R 7 and R 8 may be the same or different and are members of the group comprising hydrogen or straight or branched chain lower alkyl having 1-6 carbon atoms; or wherein N, R 7 and R 8 may together form a cyclic amine of the formula ##STR13## wherein p is 4 or 5; wherein R 4 is hydrogen, or ##STR14## wherein R 5 is hydrogen, benzyl-, or straight or branched chain alkyl of 1-3 carbon atoms; and wherein R 6 is a member of the group comprising straight or branched chain alkyl having 1-6 carbon atoms. DETAILED DESCRIPTION This invention relates to novel LTD 4 inhibitors of Formula I having a chromane ring structure and 2,2-disubstitution on the chromane ring. The disubstituents of the present invention are of the formula --(CH 2 ) m --Z wherein Z is a carbonyl containing moiety such as --CHO, --COOR 2 , or --COR 3 , i.e. an aldehyde, ester, or amide respectively; or an alcohol, i.e. the reduction product of the above carbonyls; or the corresponding lower alkyl ester of said alcohol. The term "lower alkyl" as used herein means straight or branched chain alkyl having 1-6 carbon atoms such as methyl, ethyl, propyl, butyl, pentyl, hexyl and the isomeric forms thereof. The term "pharmaceutically acceptable cation" as used to describe R 2 refers to cations such as ammonium, sodium, potassium, lithium, calcium, magnesium, ferrous, zinc, copper, manganous, aluminum, ferric, manganic, ammonium, tetraalkylammonium, and the like. The term "pharmaceutically acceptable addition salts" refers either to those base derived salts of any compound herein having a carboxylic acid function, or to those acid derived salts of any compound herein having an amide function. The base derived salts may be derived from pharmaceutically acceptable non-toxic inorganic or organic bases. Among the inorganic bases employed to produce said pharmaceutically acceptable salts are the hydroxide bases of the pharmaceutically acceptable cations disclosed above. Among the organic bases employed to produce said pharmaceutically acceptable salts are the pharmaceutically acceptable non-toxic bases of primary, secondary, and tertiary amines. Especially preferred non-toxic bases are isopropylamine, diethylamine, ethanolamine, dicyclohexylamine, choline, and caffeine. The acid derived salts may be derived from pharmaceutically acceptable non-toxic organic or inorganic acids. Suitable pharmaceutically acceptable organic acid salts include such salts as the maleate, fumarate, tartrate, (methane-, ethane-, and benzene) sulfonates, citrate, and the malate. Suitable inorganic (mineral) acid salts include such salts as the chloride, bromide, and sulfate. All the pharmaceutically acceptable non-toxic addition salts are prepared by conventional processes well known to those of ordinary skill in the art. LTD 4 acts by causing brochoconstriction in both guinea pigs and humans. The bronchoconstriction has two components: (1) a direct component, wherein LTD 4 stimulates the respiratory smooth muscle to constrict; and (2) an indirect component wherein LTD 4 causes the release of thromboxane A2 which also causes the construction of respiratory smooth muscle. The compounds of this invention act by antagonizing the direct constriction of respiratory smooth muscle by LTD 4 . The LTD 4 antagonistic activity of the compounds of this invention were determined by both in vivo and in vitro testing upon guinea pigs. In one in vivo assay, adult male fasted Hartly guinea pigs weighing 300-360 g were pretreated with pyrilamine and indomethacin to block the bronchoconstrictive effects of endogenous histamine and the synthesis of thromboxane A2 respectively. Compounds of the invention were administered IG (intragastrically) at approximate times prior to the IV (intravenous) administration of 2000 units of LTD 4 . Intratracheal pressure was monitored prior to and subsequent to LTD 4 administration in animals anesthetized with pentobarbital and attached to a rodent respirator. A compound was determined to antagonize the direct component of LTD 4 action on respiratory smooth muscle if the compound inhibited the intratracheal insufflation pressure increases caused by LTD 4 . The compounds of this invention were found to exhibit LTD 4 antagonistic activity at doses of 10 mg/kg. One of the in vitro assays utilized to determine the LTD 4 antagonistic activity of the compounds of this invention was performed on excised guinea pig ileum (smooth muscle). In this assay, control contractions of guinea pig ileum ("ileum") were incubated in a solution of LTD 4 and the number of contractions in response to the LTD 4 were determined. A solution or suspension containing a compound of this invention was substituted for the control solution and the item was allowed to incubate for 30 minutes. Thereafter, doses of LTD 4 were added and increased if necessary until contractions were obtained that are approximately equal to the control. A dose/test compound ratio was calculated from the results of each test. A concentration of the test compound was judged to be active if it produced a dose ratio that was significantly greater than that obtained in a series of blank treatment tests. Duplicate tests were conducted on each concentration of test compound. Initial screening of the compounds of this invention began at 3×10 -6 M. The compounds of the present invention were determined to exhibit LTD 4 antagonistic activity at test concentrations ranging from 3×10 -6 M to 1×10 -7 M. By virtue of their activity as LTD 4 inhibitors, the compounds of Formula I are useful in treating inflammatory conditions in mammals in which LTD 4 plays a role such as psoriasis, Crohn's disease, asthmatic bronchitis, ulcerative colitis and the like. A physician or veterinarian of ordinary skill can readily determine whether a subject exhibits the inflammatory condition. The preferred utility relates to treatment of ulcerative colitis. The compounds can be administered in such oral dosage forms as tablets, capsules, softgels, pills, powders, granules, elixirs, or syrups. The compounds may also be administered intravascularly, intraperitoneally, subcutaneously, intramuscularly, or topically using forms known to the pharmaceutical art. In general, the preferred form of administration is oral or in such a manner so as to localize the inhibitor. For example, for asthma, the compounds could be inhaled using an aerosol or other appropriate spray. In an inflammatory condition such as rheumatoid arthritis, the compounds could be injected directly into the affected joint. For the orally administered pharmaceutical compositions and methods of the present invention the foregoing active ingredients will typically be administered in admixture with suitable pharmaceutical diluents, excipients, or carriers (collectively referred to herein as "carrier" materials) suitably selected with respect to the intended form of administration, that is, oral tablets, capsules, softgels, elixirs, syrups, drops, and the like, and consistent with conventional pharmaceutical practices. For example, for oral administration in the form of tablets or capsules, the active drug components may be combined with any oral non-toxic pharmaceutically acceptable inert carrier such as lactose, starch, sucrose, cellulose, magnesium stearate, dicalcium phosphate, calcium sulfate mannitol, and the like, or various combination thereof. For oral administration in liquid forms, such as in softgels, elixirs, syrups, drops and the like, the active drug components may be combined with any oral non-toxic pharmaceutically acceptable inert carrier such as water, saline, ethanol, polyethylene glycol, propylene glycol, corn oil, cottonseed oil, peanut oil, sesame oil, benzyl alcohol, various buffers, and the like, or various combinations thereof. Moreover, when desired or necessary, suitable binders, lubricants, disintegrating agents, and coloring agents can also be incorporated in the mixture. Suitable binders include starch, gelatin, natural sugars, corn sweeteners, natural and synthetic gums such as acacia, sodium alginate, carboxymethylcellulose, polyethylene glycol, and waxes, or combinations thereof. Lubricants for use in these dosage forms include boric acid, sodium benzoate, sodium acetate, sodium chloride, and the like, or combinations thereof. Disintegrators include, without limitation, starch, methylcellulose, agar, bentonite, guar gum, and the like, or combinations thereof. Sweetening and flavoring agents and preservatives can also be included where appropriate. For intravascular, intraperitoneal, subcutaneous, intramuscular or aerosol administration, active drug components may be combined with a suitable carrier such as water, saline, aqueous dextrose, and the like. Regardless of the route of administration selected, the compounds of the present invention are formulated into pharmaceutically acceptable dosage forms by conventional methods known to those skilled in the art. The compounds may also be formulated using pharmacologically acceptable acid or base addition salts. Moreover, the compounds or their salts may be used in a suitable hydrated form. Regardless of the route of administration selected, a non-toxic but therapeutically effective quantity of one or more compounds of this invention is employed in any treatment. The dosage regimen for preventing or treating inflammatory conditions with the compounds of this invention is selected in accordance with a variety of factors, including the type, age, weight, sex, and medical condition of the patient, the severity of the inflammatory condition, the route of administration, and the particular compound employed in the treatment. A physician or veterinarian of ordinary skill can readily determine and prescribe the effective amount of the drug required to prevent or arrest the progress of the condition. In so proceeding, the physician or veterinarian could employ relatively low doses at first and subsequently increase the dose until a maximum response is obtained. The compounds of this invention are prepared by the general methods illustrated in Schemes A-E. In the discussion of these schemes, the conventional numbering of the chromane ring is employed as illustrated in Formula II below. ##STR15## In charts A to E, the various compounds and intermediates can be readily modified by methods known to those skilled in the art. For example, esters can be hydrolyzed to corresponding carboxylic acids (and their respective addition salts), or converted to corresponding amides by appropriate reactions with amines, or reduced to alcohols by such reagents as lithium aluminium hydride (LiAlH 4 ). Such products and intermediates can, of course, be similarly interconverted. As illustrated in Chart A, 2,4-dihydroxylacetophenones of Formula X, wherein W and Y are as defined herein, react readily with ketodiesters of Formula XI, such as dimethyl 4-oxopimelate where (n=2), to afford fused ring compounds of Formula XII or of Formulas XII and XIII depending upon reaction conditions. The preferred reaction conditions for condensation and cyclization to produce the compound of Formula XII includes heating Formulas X and XI in toluene, in the presence of a base such as pyrrolidine, with provisions for removal of the water with an apparatus such as a Dean-Stark trap. Alternatively, to produce the compounds of both Formulas XII and XIII, the condensation and cyclization is allowed to proceed overnight at room temperature in the presence of a secondary amine, such as pyrrolidine, and then at reflux for about 3-4 hours. The intermediates of Formulas XII and XIII may be used in reactions in Chart B without further modification or they may be converted to related intermediates of Formulas XIV and XV by methods known to those skilled in the art. For example, hydrogenation over palladium on carbon (Pd/C) will reduce the keto function of the dihydrobenzopyran-4-ones (Formulas XII or XIII) to the corresponding --CH 2 --, producing a dihydrobenzopyran of Formula XIV. Partial hydrogenation or reduction with NaBH 4 in a polar solvent will afford the corresponding 4-hydroxy compound of Formula XV. These latter two sequences of reactions provide the means for achieving the necessary diversity in "V" of Formula I. As illustrated in Chart B, alcohols of the formula R 1 OH (XVIa) may be alkylated to form ethers in the presence of an alkylating agent (XVIb) and a base. Preferably, the alcohol is methanol or hydroxyaryl. By "hydroxyaryl" is meant phenol, naphthol, 5,6,7,8-tetrahydronaphthols or substituted analogs thereof, wherein the substituents include --NH 2 , NO 2 , Cl, Br, CF 3 and lower alkyl from 1-4 carbon atoms. Preferably, the alkylating agent is a dihaloalkane of the formula X--(CH 2 ) m --X wherein X is Br, Cl or I and m is an integer from 1-9. Especially preferred as an alkylating agent is Br--(CH 2 ) m --Br. Preferred reaction conditions include reaction in dry dimethylformamide (DMF) in the presence of the anhydrous base, potassium carbonate. Intermediates of Formula XVII are typically purified by column chromatography on silica gel. The further reaction of XVII with 7-hydroxybenzopyran-4-ones of Formula XII in the presence of base in polar aprotic solvents afford the diester pyranone ethers (XVIII) of this invention. Similarly, diester pyran and pyranol ethers can be afforded by reaction of XVII with pyrans of Formula XIV and pyranols of Formulas XV, respectively. Preferred reaction conditions for this ether formation include reaction in dry DMF in the presence of an anhydrous base, such as potassium carbonate. Chart B further illustrates that the diesters XVIII may be hydrolyzed to the corresponding diacid salt XIX in the presence of a base. Preferably, the base is a hydroxide species having a pharmaceutically acceptable cation as disclosed herein. The preferred solvent system is aqueous alcohol, such as aqueous methanol. The resulting diacid salts XIX may be converted to the corresponding diacid species XX by acidification of XIX in an aqueous alcoholic solution. Preferred acidifying agents are the mineral acids such as HCl, H 2 SO 4 , H 3 PO 4 and the like. Chart C illustrates the preparation of the compounds of Formula XVIII using a variation of the method of Chart B. The compounds of Formula XII are first reacted with dihaloalkanes of the formula, X--(CH 2 ) m --X, preferably Br--(CH 2 ) m --Br, in the presence of base in a polar solvent to produce an intermediate of Formula XXI. As in Chart B, the preferred conditions for ether formation include reaction in dry dimethyl formamide (DMF) in the presence of anhydrous potassium carbonate (K 2 CO 3 ). By the same general procedure for ether formation just employed in converting Formula XII to XXI above, Formulas XXI and X react in the presence of base in a polar solvent to form the title compounds of this invention, Formula XVIII. Chart D illustrates a condensation reaction analogous to Chart A wherein 2,4-dihydroxyacetophenones of Formula X react with ketodienes of Formula XXX in the presence of a weak base in a nonpolar solvent with heat to afford the corresponding 2,2-bis-enylpyranones of Formula XXXI. Preferred reaction conditions include toluene as the solvent and pyrrolidine as the weak base. Formula XXXI reacts with a halide XVII in a polar solvent, preferably dimethylformamide (DMF), in the presence of a base, preferably K 2 CO 3 , via a nucleophilic substitution to form the corresponding bis-(enyl)ether XXXII. The enyl groups of XXXII are oxidized to the vicinal diols of XXXIII by OsO 4 in aqueous alcoholic tetrahydrofuran (THF) in the presence of N-methylmorpholine-N-oxide. Preferably, the alcoholic portion of the solvent is t-butanol. Chart E illustrates further reactions of the bis-diol XXXIII to yield the compounds of this invention. The bis-diol XXXIII may be esterified to a tetraester XXXIV by acetylation-reaction of the bis-diol with an excess of an alkyl or aryl anhydride such as acetic anhydride in the presence of a weak base, preferably pyridine. Alternatively, the bis-diol XXXIII can be oxidized to a bis-aldehyde, wherein the oxidized side chain loses one carbon atom. The preferred oxidizing agent is periodate (IO 4 -) associated with either H+ or an alkali metal cation. In another reaction sequence in Chart E, the diester XVIII is first converted to the diacyl chloride by reaction with thionyl chloride (SO 2 Cl) and then to the bis-(dibenzyl ester) XXXVI by reaction of the diacyl chloride with 1,3-dibenzyloxy-2-propanol. Partial hydrogenation of XXXVI over 10% Pd/C produces the tetra-ol XXXVII. Alternatively, the diester XVIII may be converted to the terminal bis-(diol ester) XXXVIII by reaction with glicidol in the presence of benzyl-trimethylammonium hydroxide. It is recognized that certain compounds of this invention may exist in L, D and D, L forms. These stereoisomers may be separated into their individual enantiomers by techniques well known in the art, such as recrystallization and chromatography of their optically active derivatives. The following examples are given by way of illustration only and should not be construed as limiting this invention either in spirit or in scope, as based upon the disclosure herein many variations will become obvious to those of ordinary skill in the art. ##STR16## DESCRIPTION OF THE PREFERRED EMBODIMENT EXAMPLE 1 diethyl 3,4-dihydro-4-oxo-7-hydroxy-8-propyl-2H-1-benzopyran-2,2-dipropanoate ##STR17## A stirred solution of 12.3 g (53.5 mmol) of diethyl 4-oxopimelate, 10.4 g (53.5 mmol) of 2,4-dihydroxy-3-propylacetophenone, and 3.8 g (55 mmol) of pyrrolidine in 62 ml of toluene was refluxed under a water separator. After 4 hours, the mixture was allowed to cool. The solvent was removed under reduced pressure and the resultant oil was chromatographed on silica gel using ethyl acetate-hexane as eluent. The titled diester (4.98 g) was found to be homogeneous by thin-layer chromatography (20% by volume ethyl acetate/hexane on silica gel plates) and was used in subsequent reactions without further purification. 1 H NMR (CDCl 3 ): δ8.13 (br s, 1H); 7.60 (d, J=9 Hz, 1H); 6.50 (d, J=9 Hz, 1H); 4.12(q, J=7 Hz, 4H); 2.65(br s, 2H); 2.53-1.83(m, 10H); 1.52 (m, 2H); 1.22(q, J=7 Hz, 6H); and 0.95(t,3H). EXAMPLE 2 Mixture of dimethyl 3,4-dihydro-4-oxo-7-hydroxy-8-propyl-2H-1-benzopyran-2,2-dipropanoate and ##STR18## methyl 3,4-dihydro-4-oxo-2-(3-oxo-3-[1-pyrrolidinyl]propyl)-8-propyl-7-hydroxy-2H-1-benzopyran-2-propanoate ##STR19## A stirred solution of 9.70 g (50 mmol) of 2,4-dihydroxy-3-propylacetophenone, 10.1 g (50 mmol) of dimethyl 4-oxopimelate, and 1.8 g of pyrrolidine in 62 ml of toluene was stirred overnight at room temperature, then refluxed under a water separator for 3.5 hours. The mixture was allowed to cool, and the solvent was removed under reduced pressure. Chromatography of the residue on silica gel using 20% ethyl acetate/toluene as eluent gave 1.39 g of the titled diester. The purified diester was found to be homogeneous by thin-layer chromatography (20% ethyl acetate/toluene by volume on silica gel plates) and was used in subsequent reactions without further purification. The titled ester-amide (590 mg) was obtained impure but was suitable for use in subsequent reactions. Diester: 1 H NMR (CDCl 3 ): δ0.99(t, 3H); 1.21-1.75(m, 2H); 1.91-2.75(m, 10H); 2.66(s, 2H); 3.68(s, 6H); 5.91(br s, 1H); 6.45(d, 1H) and 7.63(d, 1H). Ester-amide: 1 H NMR (CDCl 3 ): δ10.45(br s, 1H); 7.56(d, 1H); 6.64(d, 1H); 3.68(s, 3H); 2.82 (br s, 2H); 1.57(m, 2H); and 1.01(t, 3H). EXAMPLE 3 3-(4-chlorophenoxy)-1-bromopropane ##STR20## To a suspension of 1.53 g (63.8 mmol) of sodium hydride in 50 ml of dry dimethylformamide was added over thirty minutes a solution of 8.23 g (63.8 mmol) of 4-chlorophenol. After stirring for one hour at room temperature, 16 g (77 mmol) of 1,3-dibromopropane was added in one portion. The mixture was stirred for 68 hours, and the solvent removed under reduced pressure. The residue was dissolved in diethyl ether and washed with water. The aqueous layer was then extracted twice with ether. The combined organic extracts were washed three times with water, once with brine, then dried (MgSO 4 ). After filtration, the solvent was removed under reduced pressure. The residue was chromatographed on silica gel, using 10% methylene chloride/hexane as the eluent and produced 710 mg of the title compound, which was homogeneous by thin layer chromatography (10% by volume of methylene chloride/hexane on silica gel plates). 1 H NMR (CDCl 3 ): δ7.27(d, J=9 Hz, 2H); 6.85(t, J=9 Hz, 2H); 4.07(t, 2H), 3.60(t, 2H); and 2.28 (quintet, 2H). EXAMPLE 4 3-(2-naphthoxy)-1-bromopropane ##STR21## To a solution of 3.60 g (25 mmol) of 2-naphthol and 6.0 g (30 mmol) of 1,3-dibromopropane in dimethylformamide was added 7.25 g (52.5 mmol) of finely ground anhydrous potassium carbonate. The mixture was stirred vigorously overnight. Solvent was removed under reduced pressure. The residue was partitioned between ethyl acetate and water. The aqueous layer was further extracted twice with ethyl acetate. The combined organic extracts were dried over magnesium sulfate, and after filtration, the solvent was removed under reduced pressure. The residue was then chromatographed over silica gel using 10% methylene chloride/hexane as eluent to afford 1.66 g of the title compound, which was homogeneous by thin layer chromatography (5% by volume of ethyl acetate/hexane on silica gel plates). 1 H NMR (CDCl 3 ); δ7.73-6.90(m, 7H); 4.03(t, 2H); 3.50(t, 2H); and 2.22(quintet, 2H). EXAMPLE 5 3-(1-naphthyloxy)-1-bromopropane ##STR22## The title compound was prepared by the method of Example 4 using 1-naphthol, 1.80 g (12.5 mmol), in place of 2-naphthol. After chromatography there was obtained 0.80 g of the title compound, which was homogeneous by thin layer chromatography (10% by volume of toluene/hexane on silica gel plates). 1 H NMR (CDCl 3 ): δ8.40-6.67(m, 7H); 4.22(t, 2H); 3.65 (t, 2H); and 2.38(quintet, 2H). EXAMPLE 6 3-(3,4-dichlorophenoxy)-1-bromopropane ##STR23## A mixture of 3.26 g (20 mmol) of 3,4-dichlorophenol, 20.2 g (100 mmol) of 1,3-dibromopropane, 6.80 g (20 mmol) of tetra-n-butyl ammonium hydrogen sulfate, 40 ml of 1N sodium hydroxide, and 40 ml of methylene chloride was stirred rapidly at reflux. After 2 hours, the mixture was allowed to cool and the layers were separated. The organic layer was washed with water, dried over magnesium sulfate, filtered and the solvent removed under reduced pressure. The residue was chromatographed over silica gel using methylene chloride/hexane as eluent. The title compound (1.58 g) was found to be homogeneous by thin layer chromatography (10% by volume of methylene chloride/hexane on silica gel plates). 1 H NMR (CDCl 3 ); δ7.29(d, J=9 Hz, 1H); 6.97(d, J=3 Hz, 1H); 6.71(dd, J=3, J=9 Hz, 1H); 3.97(t, 3H); 3.57(t, 2H); 2.27(quintet, 2H). EXAMPLE 7 3-(4-bromophenoxy)-1-bromopropane ##STR24## The title compound was prepared and worked up by the method of Example 6 using 4-bromophenol in place of 3,4-dichlorophenol. After chromatography the title compound (3.45 g) was found to be homogeneous by thin layer chromatography (10% by volume of methylene chloride/hexane on silica gel plates). 1 H NMR (CDCl 3 ); δ7.31(d, 2H); 6.71(d, 2H); 3.98(t, 2H); 3.50(t, 2H); and 2.20(quintet, 2H). EXAMPLE 8 3-(4-chloro-1-naphthoxy)-1-bromopropane ##STR25## The title compound was prepared and worked up according to the method of Example 6 using 4-chloro-1-naphthol (1.79 g) in place of 3,4-dichlorophenol. After chromatography, the title compound (2.09 g) was found to be homogeneous by thin layer chromatography (10% by volume of methylene chloride/hexane on silica gel plates). 1 H NMR (CDCl 3 ); δ8.13(m, 2H); 7.47(m, 2H); 7.30(d, J=8 Hz, 1H); 6.50(d, J=8 Hz, 1H); 4.00(t, 2H); 3.55(t, 2H); and 2.27(quintet, 2H). EXAMPLE 9 3-(3-trifluoromethylphenoxy)-1-bromopropane ##STR26## The title compound was prepared and worked up according to the method of Example 6 using 3-trifluoromethylphenol (1.62 g) in place of 3,4-dichlorophenol. After chromatography, the title compound (1.24 g) was found to be homogeneous by thin layer chromatography (10% by volume of methylene chloride/hexane on silica gel plates). 1 H NMR (CDCl 3 ); δ7.40-6.93(m, 4H); 4.10(t, 2H); 3.57(t, 2H); and 2.30(quintet, 2H). EXAMPLE 10 3-(4-nitrophenoxy)-1-bromopropane ##STR27## The title compound was prepared and worked up according to the method of Example 6 using 4-nitrophenol (1.39 g) in place of 3,4-dichlorophenol. After chromography, the title compound (1.67 g) was found to be homogeneous by thin layer chromatography (10% or 20% by volume of ethyl acetate/hexane on silica gel plates). 1 H NMR (CDCl 3 ); δ8.16(d, 2H); 6.94(d, 2H); 4.22(t, 2H); 3.62(t, 2H); and 2.37(quintet, 2H). EXAMPLE 11 3-(2-propylphenoxy)-1-bromopropane ##STR28## The title compound was prepared by the method of Example 6 using 2-propylphenol (1.36 g) in place of 3,4-dichlorophenol. After chromatography, the title compound (1.59 g) was found to be homogeneous by thin layer chromatography (5% by volume of toluene/hexane on silica gel plates). 1 H NMR (CDCL 3 ); δ7.23-6.70(m, 4H); 4.07(t, 2H); 3.60(t, 2H); 2.60(t, 2H); 2.32(quintet, 2H); 1.55(m, 2H); and 0.95(t, 3H). EXAMPLE 12 3-(5,6,7,8-tetrahydro-1-naphthoxy)-1-bromopropane ##STR29## The title compound was prepared by the method of Example 6 using 5,6,7,8-tetrahydro-1-naphthol in place of 3,4-dichlorophenol. After chromatography, the title compound (1.49 g) was found to be homogeneous by thin layer chromatography (10% by volume of methylene chloride/hexane on silica gel plates). 1 H NMR (CDCl 3 ); δ7.05(dd, J=8 Hz, 1H); 6.68(d, J=8 Hz, 1H); 6.53(d, J=8 Hz, 1H); 4.03(t, 2H); 3.60(t, 2H); 2.68(m, 4H); 2.28(quintet, 2H); and 1.75(m, 4H). EXAMPLE 13 3-(4-acetoxyphenoxy)-1-bromopropane ##STR30## A mixture of 1.52 g (10 mmol) of 4-acetoxyphenol, 2.22 g (11 mmol) 1,3-dibromopropane, and 2.98 g (21 mmol) of anhydrous potassium carbonate in dimethylformamide was stirred rapidly at room temperature for 4 hours. Ethyl acetate was added, and the salts present were removed by filtration. The solvent was removed under reduced pressure, and the residue chromatographed over silica gel. Elution with 15% ethyl acetate-hexane gave 270 mg of the title compound, which was homogeneous by thin layer chromatography (15% by volume of ethyl acetate/hexane on silica gel plates). 1 H NMR (CDCl 3 ); δ6.87(m, 4H); 4.02(t, 3H); 3.53(t, 2H); 2.33(quintet, 2H); and 2.22(s, 3H). EXAMPLE 14 4-(3-bromopropoxy)-3-propyl-2-hydroxyacetophenone ##STR31## The title compound was prepared and worked up by the method of Example 6 using 25.0 g of 2,4-dihydroxy-3-propylacetophenone in place of 3,4-dichlorophenol. After chromatography, the title compound (8.60 g) was found to be homogeneous by thin layer chromatography (10% by volume of ethyl acetate/hexane on silica gel plates). 1 H NMR (CDCl 3 ); δ7.60(d, 1H); 6.47(d, 1H); 4.19(t, 2H); 3.62(t, 2H); 2.63(t, 2H); 2.56(s, 3H); 2.36(quintet, 2H); 1.57(m, 2H); and 0.94(t, 3H). EXAMPLE 15 2,2-bis(3-carboethoxypropyl)-7-hydroxybenzopyran-4-one ##STR32## A stirred solution of 4.62 g (30.4 mmol) of 2,4-dihydroxyacetophenone, 7.00 g (30.4 mmol) of diethyl 4-oxopimelate, and 2.2 g (30 mmol) of pyrrolidine in 38 ml of toluene was refluxed under a water separator for 3.5 hours. After the mixture was allowed to cool, it was chromatographed directly over silica gel using ethyl acetate/hexane as eluent to produce 3.82 g of the title compound as a solid, m.p. 108.5°-109.5° C. 1 H NMR (CDCL 3 ); δ8.30(br s, 1H); 7.76(d, J=8 Hz, 1H); 6.58(dd, J=8 Hz, J=2 Hz, 1H); 6.40(d, J=2 Hz, 1H); 4.20(q, 4H); 2.78(br s, 1H); 2.68-1.98(m, 8H); and 1.32(t, 3H). Analysis calculated for C 19 H 24 O 7 (MW=364.40): Calcd.: C, 62.62; H, 6.64. Found: C, 62.62; H, 6.39. EXAMPLE 16 dimethyl 3,4-dihydro-4-oxo-7-(3-phenoxypropoxy)-8-propyl-2H-1-benzopyran-2,2-dipropanoate ##STR33## A mixture of 1.00 g (2.65 mmol) of the title diester of Example 2, 684 mg (3.18 mmol) of 3-phenoxy-1-bromopropane, and 769 mg (5.57 mmol) of anhydrous potassium carbonate in 23 ml of dimethylformamide was stirred overnight at room temperature. After removal of solvent under reduced pressure, the residue was partitioned between 75 ml ethyl acetate and 25 ml water, and the aqueous layer separated. The aqueous layer was acidified with 3N hydrochloric acid, and the layer shaken again. The aqueous layer was further extracted with 25 ml ethyl acetate. The combined organic extracts were washed with brine, dried (MgSO 4 ), the drying agent removed by filtration, and the solvent removed on a rotary evaporator. The residue was chromatographed on silica gel using ethyl acetate as eluent. After removal of solvent, the product was crystallized from 3:1 ethyl acetate/hexane to yield 945 mg, m.p. 100°-100.5° C. Analysis for C 29 H 36 O 8 (MW=512.61): Calcd.: C, 67.95; H, 7.08. Found: C, 68.00; H, 7.11. EXAMPLE 17 3,4-dihydro-4-oxo-7-(3-phenoxypropoxy)-8-propyl-2H-1-benzopyran-2,2-dipropanoic acid ##STR34## A mixture of 611 mg (1.19 mmol) of the title product of Example 16, 0.72 ml of 50% aqueous sodium hydroxide, and 11.7 ml of water was stirred at reflux. After one hour, another 2 ml of water was added and the reaction mixture was heated for an additional 2 hours. The mixture was allowed to cool and then partitioned between 75 ml of ethyl acetate and 50 ml of 3N hydrochloric acid. The aqueous layer was further extracted twice with 25 ml aliquots of ethyl acetate. The combined organic extracts were washed with water, with brine, dried over magnesium sulfate, filtered, and solvent removed on a rotary evaporator to give 501 mg of title product, m.p. 161.5°-162° C. Analysis for C 27 H 32 O 8 (MW=484.55): Calcd.: C, 66.92; H, 6.66. Found: C, 67.10; H, 6.70. EXAMPLE 18 dimethyl 3,4-dihydro-4-oxo-7-(phenylmethoxy)-8-propyl-2H-1-benzopyran-2,2-dipropanoate ##STR35## A mixture of 378 mg (1.00 mmol) of the title product of Example 2, 190 mg (1.1 mmol) of benzyl bromide, and 290 mg (2.10 mmol) of anhydrous potassium carbonate in 10 ml of dimethylformamide was stirred at room temperature for 60 hours. The solvent was removed under reduced pressure, and the residue was partitioned between ethyl acetate and 3N hydrochloric acid. The aqueous layer was extracted with ethyl acetate. The combined organic extracts were dried over magnesium sulfate, the drying agent removed by filtration, and the solvent removed under reduced pressure. After flash chromatography on silica gel using 40% by volume of ethyl acetate/hexane as eluent, there was obtained 0.43 g of the title product as an oil. 1 H NMR (CDCl 3 ); δ7.69(d, 1H); 7.40(br s, 5H); 6.59(d, 1H); 5.11(s, 2H); 3.65(s, 6H); 2.64(br s, 2H); and 0.94(t, 3H). Analysis for C 27 H 32 O 7 (MW=468.55): Calcd.: C, 69.21; H, 6.88. Found: C, 69.17; H, 6.91. EXAMPLE 19 dimethyl 7-[3-[4-(acetyloxy)phenoxy]propoxy]-3,4-dihydro-4-oxo-8-propyl-2H-1-benzopyran-2,2-dipropanoate ##STR36## The title compound (660 mg), isolated as the 1/4 hydrate, was prepared by the method of Example 18 substituting the title product (380 mg, 1.43 mmol) of Example 13 for benzyl bromide. 1 H NMR (CDCl 3 ): δ7.70(d, 1H); 6.99(d, 2H); 6.79(d, 2H); 6.54(d, 1H); 4.19(t, 2H); 4.13(t, 2H); 3.63(s, 6H); 2.64(br s, 2H); 2.25(s, 3H); and 0.91(t, 3H). Analysis for C 31 H 38 O 10 .1/4H 2 O (MW=570.64): Calcd.: C, 64.72; H, 6.75. Found: C, 64.69; H, 6.84. EXAMPLE 20 3,4-dihydro-7-[3-(4-hydroxyphenoxy)propoxy]-4-oxo-8-propyl-2H-1-benzopyran-2,2-dipropanoic acid ##STR37## The title product of Example 19 (500 mg, 0.876 mmol) was stirred in 14 ml of methanol containing 0.85 ml of a 50% aqueous solution of sodium hydroxide for one hour. The mixture was partitioned between 40 ml of ethyl acetate and 30 ml of 3N hydrochloric acid, and the aqueous layer further extracted twice with 20 ml aliquots of ethyl acetate. The combined organic extracts were washed with brine, dried over magnesium sulfate (MgSO 4 ), the drying agent removed by filtration, and the solvent removed on a rotary evaporator. Crystallization of the residue from diethyl ether gave the title product (321 mg), m.p. 160°-166° C. Analysis for C 27 H 32 O 9 (MW=500.55): Calcd.: C, 64.78; H, 6.44. Found: C, 64.59; H, 6.84. EXAMPLE 21 diethyl 3,4-dihydro-7-[3-(4-chlorophenoxy)propoxy]-4-oxo-8-propyl-2H-1-benzopyran-2,2-dipropanoate ##STR38## The title compound (620 mg) was prepared by the method of Example 18 substituting the title product of Example 1 (512 mg) for the title product of Example 2, and substituting the title product of Example 3 (355 mg) for benzyl bromide. 1 H NMR (CDCl 3 ); δ7.70(d, 1H); 7.20(d, 2H); 6.79(d, 2H); 6.54(d, 1H); 4.09(q, 4H); 2.64(br s, 2H); 1.23(t, 6H); and 0.91(t, 3H). EXAMPLE 22 7-[3-(4-chlorophenoxy)propoxy]-3,4-dihydro-4-oxo-8-propyl-2H-1-benzopyran-2,2-dipropanoic acid ##STR39## The title compound (510 mg), m.p. 133°-134° C., was prepared by the method of Example 20 substituting the title product of Example 21 (620 mg) instead of the title product of Example 19, and carrying out the reaction for one hour at reflux instead of for two hours at room temperature. Analysis for C 27 H 31 ClO 8 (MW=519.00): Calcd.: C, 62.49; H, 6.02; Cl, 6.83. Found: C, 62.42; H, 5.81; Cl, 7.78. EXAMPLE 23 diethyl 3,4-dihydro-7-[3-(2-naphthalenyloxy)propoxy]-4-oxo-8-propyl-2H-1-benzopyran-2,2-dipropanoate ##STR40## The title compound (569 mg) was prepared by the method of Example 19 substituting the 406 mg of title product of Example 1 for the title product of Example 2, and further substituting the 299 mg of title product of Example 4 for benzyl bromide. 1 H NMR (CDCl 3 ); δ7.78-6.96(m, 7H); 7.70(d, 1H); 6.56(d, 1H); 4.09(q, 4H); 2.64(br s, 2H); 1.23(t, 6H); and 0.93(t, 3H). EXAMPLE 24 3,4-dihydro-7-[3-(2-naphthalenyloxy)propoxy]-4-oxo-8-propyl-2H-1-benzopyran-2,2-dipropanoic acid ##STR41## The title compound was prepared by the method of Example 22 substituting 539 mg of the title product of Example 23 for the title product of Example 21. Crystallization from 5:1 ethyl acetate:hexane yielded 303 mg, m.p. 157.5°-158° C. Analysis for C 31 H 34 O 8 (MW=534.61): Calcd.: C, 69.64; H, 6.41. Found: C, 69.49; H, 6.25. EXAMPLE 25 3,4-dihydro-4-oxo-7-(phenylmethoxy)-8-propyl-2H-1-benzopyran-2,2-dipropanoic acid ##STR42## The title compound, 102 mg, m.p. 202°-205° C., was prepared by the method of Example 22 substituting the title product of Example 18 (455 mg) for the title product of Example 21, and utilizing methylene chloride as the extraction solvent instead of ethyl acetate. Analysis for C 25 H 28 O 7 (MW=440.50): Calcd.: C, 68.17; H, 6.41. Found: C, 67.83; H, 6.25. EXAMPLE 26 diethyl 3,4-dihydro-4-oxo-7-(3-phenoxypropoxyl)-2H-1-benzopyran-2,2-dipropanoate ##STR43## The title compound (500 mg) was prepared by the method of Example 16 substituting the title product of Example 15 (364 mg) for the title product of Example 2. 1 H NMR (CDCl 3 ); δ7.74(d, J=8 Hz, 1H); 7.36-6.78(m, 5H); 6.53(dd, J=8 Hz, 1H); 6.34(d, J=2 Hz, 1H); 4.09(q, 4H); 2.64(br s, 2H); and 1.23(t, 6H). EXAMPLE 27 3,4-dihydro-4-oxo-7-(3-phenoxypropoxy)-2H-1-benzopyran-2,2-dipropanoic acid ##STR44## The title compound was prepared by the method of Example 22 substituting the title product of Example 26 for the title product of Example 21. Crystallization from 60% by volume ethyl acetate/hexane yielded 219 mg, m.p. 132°-133° C. Analysis for C 24 H 26 O 8 (MW=442.47): Calcd.: C, 65.15; H, 5.92. Found: C, 64.86; H, 5.77. EXAMPLE 28 diethyl 3,4-dihydro-7-[3-(1-naphthalenyloxy)propoxy]-4-oxo-8-propyl-2H-1-benzopyran-2,2-dipropanoate ##STR45## The title compound (549 mg) was prepared by the method of Example 18 substituting the title product of Example 1 (406 mg) for the title product of Example 2, and further substituting the title product of Example 5 (299 mg) for benzylbromide. 1 H NMR (CDCl 3 ); δ8.28-6.71(m, 7H); 7.70(d, 1H); 6.56(d, 1H); 4.09(q, 4H); 2.63(br s, 2H); 1.23(t, 6H); and 0.93(t, 3H). EXAMPLE 29 3,4-dihydro-7-[3-(1-naphthalenyloxy)propoxy]-4-oxo-8-propyl-2H-1-benzopyran-2,2-dipropanoic acid ##STR46## The title compound was prepared by the method of Example 22 substituting the title product of Example 28 (549 mg) for the title product of Example 21 to give, after crystallization from ethyl acetate, 141 mg, m.p. 164°-167° C. Analysis for C 31 H 34 O 8 (MW=534.61): Calcd.: C, 69.64; H, 6.41. Found: C, 69.64; H, 6.47. EXAMPLE 30 diethyl 7-[3-(3,4-dichlorophenoxy)propoxy]-3,4-dihydro-4-oxo-8-propyl-2H-1-benzopyran-2,2-dipropanoate ##STR47## The title compound (370 mg) was prepared by the method of Example 18 substituting 266 mg of the title product of Example 1 for the title product of Example 2, and further substituting 211 mg of the title product of Example 6 for benzyl bromide. EXAMPLE 31 7-[3-(3,4-dichlorophenoxy)propoxy]-3,4-dihydro-4-oxo-8-propyl-2H-1-benzopyran-2,2-dipropanoic acid ##STR48## The title compound, isolated as the hemihydrate, was prepared by the method of Example 22 substituting the title product of Example 30 (370 mg) for the title product of Example 21 to give, after trituration with methylene chloride, 174 mg, m.p. 136.5°-137° C. Analysis for C 27 H 30 Cl 2 O 8 .1/2H 2 O (MW=562.45): Calcd.: C, 57,65; H, 5.56; Cl, 12.61. Found: C, 57.62; H, 5.66; Cl, 12.77. EXAMPLE 32 diethyl 7-[3-(4-bromophenoxy)propoxy]-3,4-dihydro-4-oxo-8-propyl-2H-1-benzopyran-2,2-dipropanoate ##STR49## The title product (440 mg) was prepared by the method of Example 18, substituting the title product of Example 1 (406 mg) for the title product of Example 2, and further substituting the title product of Example 7 (353 mg) for benzyl bromide. 1 H NMR (CDCl 3 ); δ7.69(d, 1H): 7.35(d, 2H); 6.74(d, 2H); 6.54(d, 1H); 4.09(q, 4H); 2.64(br s, 2H); 1.23(t, 6H); and 0.91(t, 3H). EXAMPLE 33 7-[3-(4-bromophenoxy)propoxy]-3,4-dihydro-4-oxo-8-propyl-2H-1-benzopyran-2,2-dipropanoic acid ##STR50## The title product, isolated as the hydrate, was prepared by the method of Example 22 substituting the title product of Example 32 for the title product of Example 21 to give, after crystallization from ethyl acetate/hexane, 278 mg, m.p. 136°-136.5° C. Analysis for C 27 H 31 BrO 8 .H 2 O (MW=581.45): Calcd.: C, 57,35; H, 5.54; Br, 14.60. Found: C, 57.42; H, 5.54; Br, 14.70. EXAMPLE 34 diethyl 7-[3-[(4-chloro-1-naphthalenyl)oxy]propoxy]-3,4-dihydro-4-oxo-8-propyl-2H-1-benzopyran-2,2-dipropanoate ##STR51## The title compound (525 mg) was prepared by the method of Example 18 substituting the title product of Example 1 (406 mg) for the title product of Example 2, and further substituting the title product of Example 8 (360 mg) for benzyl bromide. 1 H NMR (CDCl 3 ); δ8.21(m, 2H); 7.70(d, 1H); 7.59(m, 2H): 743(d, 1H); 6.71(d, 1H); 6.56(d, 1H): 4.09(q, 4H): 2.63(br s, 2H); 1.23(t, 6H); and 0.91(t, 3H). EXAMPLE 35 7-[3-[(4-chloro-1-naphthalenyl)oxy]propoxy]-3,4-dihydro-4-oxo-8-propyl-2H-1-benzopyran-2,2-dipropanoic acid ##STR52## The title compound was prepared by the method of Example 22 substituting the title product of Example 34 (515 mg) for the title product of Example 21 to give, after trituration with diethylether, 352 mg as a solid, m.p. 170.5°-171° C. Analysis for C 31 H 33 ClO 8 (MW=569.06): Calcd.: C, 65.42; H, 5.84; Cl, 6.23. Found: C, 65.31; H, 5.77; Cl, 6.22. EXAMPLE 36 diethyl 3,4-dihydro-4-oxo-8-propyl-7-[3-[3-(trifluoromethyl)phenoxy]propoxy]-2H-1-benzopyran-2,2-dipropanoate ##STR53## The title compound (497 mg) was prepared by the method of Example 18 substituting the product of Example 1 (406 mg) for the product of Example 2, and further substituting the product of Example 9 for benzyl bromide. 1 H NMR (CDCl 3 ); δ7.70(d, 1H); 7.48-6.90(m, 3H); 6.54(d, 1H); 4.09(q, 4H); 2.63(br s, 2H); 1.23(t, 6H); and 0.90(t, 3H). EXAMPLE 37 3,4-dihydro-4-oxo-8-propyl-7-[3-[3-(trifluoromethyl)phenoxy]propoxy]-2H-1-benzopyran-2,2-dipropanoic acid ##STR54## The title compound was prepared by the method of Example 22 except that the title product of Example 36 (487 mg) was substituted for the title product of Example 21. Trituration with diethyl ether produced 267 mg of the titled compound as a solid, m.p. 129°-129.5° C. Analysis for C 28 H 31 F 3 O 8 (MW=552.55): Calcd.: C, 60.86; H, 5.66. Found: C, 60.74; H, 5.56. EXAMPLE 38 diethyl 3,4-dihydro-7-[3-(4-nitrophenoxy)propoxy]-4-oxo-8-propyl-2H-1-benzopyran-2,2-dipropanoate ##STR55## The title product (470 mg) was prepared by the method of Example 18 substituting 406 mg of the product of Example 1 for the product of Example 2, and further substituting 312 mg of the title product of Example 10 for benzyl bromide. 1 H NMR (CDCl 3 ); δ8.16(d, 2H); 7.70(d, 1H); 6.94(d, 2H); 6.54(d, 1H); 4.09(q, 4H); 2.65(br s, 2H); 1.24(t, 6H); and 0.91(t, 3H). EXAMPLE 39 3,4-dihydro-7-[3-(4-nitrophenoxy)propoxy]-4-oxo-8-propyl-2H-1-benzopyran-2,2-dipropanoic acid ##STR56## The title compound was prepared by the method of Example 22 substituting the title product of Example 38 (110 mg) for the title product of Example 21. Trituration with ethyl acetate/hexane produced 46 mg of the titled compound as a solid, m.p. 171°-172° C. Analysis for C 27 H 31 NO 10 (MW=529.55): Calcd.: C, 61.23; H, 5.90; N, 2.65. Found: C, 60.97; H, 5.78; N, 2.39. EXAMPLE 40 diethyl 3,4-dihydro-7-[3-(2-propylphenoxy)propoxy]-4-oxo-8-propyl-2H-1-benzopyran-2,2-dipropanoate ##STR57## The title compound (471 mg) was prepared by the method of Example 18 except that the title product of Example 1 (406 mg) was used instead of the title product of Example 2, and the title product of Example 11 (308 mg) was used instead of benzyl bromide. 1 H NMR (CDCl 3 ); δ7.70(d, 1H); 7.16-6.69(m, 4H); 6.55(d, 1H); 4.09(q, 4H); 2.63(br s, 2H); 1.21(t, 6H); and 0.90(t, 6H). EXAMPLE 41 3,4-dihydro-7-[3-(2-propylphenoxy)propoxy]-4-oxo-8-propyl-2H-1-benzopyran-2,2-dipropanoic acid ##STR58## The title compound was prepared by the method of Example 22 substituting the title product of Example 40 (446 mg) for the title product of Example 21. Crystallization from ethyl acetate/hexane produced 252 mg as a solid, m.p. 163°-165° C. Analysis for C 30 H 38 O 8 (MW=526.63): Calcd.: C, 68.42; H, 7.27. Found: C, 68.06; H, 7.18. EXAMPLE 42 diethyl 3,4-dihydro-4-oxo-8-propyl-7-[3-[(5,6,7,8-tetrahydro-1-naphthalenyl)oxy]propoxy]-2H-1-benzopyran-2,2-dipropanoate ##STR59## The title compound (460 mg) was prepared by the method of Example 18 substituting the title product of Example 1 (406 mg) for the title product of Example 2, and further substituting the title product of Example 12 (323 mg) for benzyl bromide. Crystallization from ethyl acetate gives the analytically pure title compound, m.p. 87.5°-88° C. Analysis for C 35 H 46 O 8 (MW=594.75): Calcd.: C, 70.68; H, 7.80. Found: C, 70.72; H, 7.94. 1 H NMR (CDCl 3 ): δ7.69(d, 1H); 7.00(dd, 1H); 6.63(d, 1H); 6.60(d, 1H); 6.54(d, 1H); 4.09(q, 4H); 2.64(br s, 2H); 1.24(t, 6H); and 0.91(t, 3H). EXAMPLE 43 3,4-dihydro-4-oxo-8-propyl-7-[3-[(5,6,7,8-tetrahydro-1-naphthalenyl)oxy]propoxy]-2H-1-benzopyran-2,2-dipropanoic acid ##STR60## The title compound was prepared by the method of Example 22 substituting the title product of Example 42 (445 mg) for the title product of Example 21. Trituration with ethyl acetate produced 317 mg of the titled compound as a solid, m.p. 126.5°-127.5° C. Analysis for C 31 H 38 O 8 (MW=538.64): Calcd.: C, 69.12; H, 7.11. Found: C, 69.14; H, 7.24. EXAMPLE 44 diethyl 3,4-dihydro-8-propyl-7-hydroxy-2H-1-benzopyran-2,2-dipropanoate ##STR61## The title product of Example 1 (4.19 g, 10.3 mmol) was dissolved in 50 ml of acetic acid, and then hydrogenated at 70° C. using 60 psi of hydrogen and 10% palladium on carbon as catalyst. After eight hours, the mixture was allowed to cool, and insolubles were removed by filtration. The filtrate was concentrated under reduced pressure. The residue was chromatographed on silicagel column. Elution with 20% ethyl acetate/hexane afforded the title compound (0.80 g). 1 H NMR (CDCl 3 ): δ6.67(d, 1H); 6.27(d, 1H); 5.47(br s, 1H); 4.10(q, 4H); 2.82-2.23(m, 8H); 2.10-1.40(m, 8H); 1.20(t, 6H); and 0.92(t, 3H). IR: One carboxyl absorption at 1718 cm -1 . EXAMPLE 45 bis(2,3-dihydroxypropyl) 3,4-dihydro-4-oxo-7-(3-phenoxypropoxy)-8-propyl-2H-1-benzopyran-2,2-dipropanoate ##STR62## A mixture of 250 mg (0.515 mmol) of the titled product of Example 17, 153 mg (2.06 mmol) of glycidol, and 9 mg of a 40% solution of benzyl-trimethylammonium hydroxide in methanol in 2.5 ml of dimethyl formamide under argon was stirred overnight at 70° C. After addition of another 153 mg of glycidol and one drop of 40% methanolic benzyltrimethylammonium hydroxide, the temperature was raised to 85°-90° C. with stirring. After stirring for 7 hours, the mixture was permitted to cool and was then partitioned between ethyl acetate and water. The aqueous layer was further extracted twice with ethyl acetate. The combined organic extracts were washed with brine, dried (Na 2 SO 4 ), the drying agent removed by filtration, and the solvent removed on a rotary evaporator. The residue was chromatographed on a silica gel column. Elution with 10% methanol/2.5% acetic acid/87.5% ethyl acetate as eluent afforded, after drying under vacuum for eight hours, the title product (170 mg), which was isolated as the hemihydrate. Analysis for C 33 H 44 O 12 .1/2H 2 O (MW=641.72): Calcd.: C, 61.77; H, 7.07. Found: C, 61.73; H, 6.99. EXAMPLE 46 bis[2-(phenylmethoxy)-1-[(phenylmethoxy)methyl]ethyl]3,4-dihydro-4-oxo-8-propyl-7-[3-[(5,6,7,8-tetrahydro-1-naphthalenyl)oxy]propoxy]-2H-1-benzopyran-2,2-dipropanoate ##STR63## A mixture of 500 mg (0.928 mmol) of the titled product of Example 43 and 0.5 ml of thionyl chloride in 10 ml of benzene was stirred at reflux for 1.5 hours. The mixture was allowed to cool, and the solvent was removed under reduced pressure. The residue was dissolved in 4 ml of methylene chloride (CH 2 Cl 2 ), a solution of 1.19 g (4.38 mmol) of 1,3-dibenzyloxy-2-propanol in 2 ml of methylene chloride and 2 ml of pyridine was added, and the mixture was stirred at room temperature for three days. To the mixture was added 50 ml of diethyl ether, and the resulting mixture washed successively with dilute hydrochloric acid, with water, and with brine. The solution was dried over magnesium sulfate, the drying agent removed by filtration, and the solvent was removed on a rotary evaporator. Chromatography over a silica gel column using a solvent gradient of 20% increasing to 50% of ethyl acetate/hexane gave 373 mg of the title compound. Analysis for C 65 H 74 O 12 (MW=1047.31): Calcd: C, 74.57; H, 7.12. Found: C, 74.51; H, 7.19. 1 H NMR (CDCl 3 ): δ7.71(d, 1H); 7.28(m, 20H); 7.04(dd, 1H); 6.69(d, 1H); 6.63(d, 1H); 6.56(d, 1H); 5.18(quintet, 2H); 4.49(s, 8H); 4.22(t, 2H); 4.13(t, 2H); 3.60(d, 8H); 2.73(br s, 2H); 2.62(m, 4H); 2.53(t, 2H); 2.28(quintet, 2H); 2.04(t, 4H); 1.75(m, 4H); 1.48(m, 2H); and 0.89(t, 3H). EXAMPLE 47 bis[2-hydroxy-1-(hydroxymethyl)ethyl]3,4-dihydro-4-oxo-8-propyl-7-[3-[(5,6,7,8-tetrahydro-1-naphthalenyl)oxy]propoxy]-2H-1-benzopyran-2,2-dipropanoate ##STR64## The titled product of Example 46 (0.258 g, 0.246 mmol) was dissolved in 25 ml of tetrahydrofuran, and then hydrogenated at room temperature using hydrogen at atmospheric pressure and 10% palladium on carbon (Pd/C) as catalyst. The insolubles were removed by filtration, and the solvent removed under reduced pressure. The residue was chromatographed on silica gel column. Elution with 5% methanol/ethyl acetate afforded 125 mg of the title compound. Analysis for C 37 H 50 O 12 (MW=686.80): Calcd.: C, 64.71; H, 7.35. Found: C, 64.35; H, 7.41. EXAMPLE 48 diethyl 7-[3-(4-aminophenoxy)propoxy]-3,4-dihydro-4-oxo-8-propyl-2H-1-benzopyran-2,2-dipropanoate ##STR65## A solution of 363 mg (0.62 mmol) of the title product of Example 38 in 45 ml of ethanol was treated with 36 mg of Raney nickel and then hydrogenated at atmospheric pressure and room temperature for 3.25 hr. The reaction mixture was filtered and the solvent was removed under reduced pressure. Chromotography of the residue over silica gel using 50-50 ethyl acetate/hexane as eluent gave the title compound as a white solid, m.p. 125.5°-127° C. Analysis for C 31 H 41 NO 8 (MW=555.68): Calcd.: C, 67.00; H, 7.44; N, 2.52. Found: C, 67,43; H, 7.29; N, 2.09. EXAMPLE 49 3,4-dihydro-N,N,N,N-tetraethyl-4-oxo-8-propyl-7-[3-[(5,6,7,8-tetrahydro-1-naphthalenyl)oxy]propoxy]-2H-1-benzopyran-2,2-dipropanamide ##STR66## A mixture of 500 mg (0.928 mmol) of the titled product of Example 43 and 1 ml of thionyl chloride was stirred at reflux for 1.5 hours. The mixture was permitted to cool, and the volatile components removed under reduced pressure. The residue was dissolved in benzene, and 1 ml of diethylamine was added. After stirring for 2 hours, the reaction mixture was washed with 3N hydrochloric acid and with water. The solution was dried (MgSO 4 ), the drying agent removed by filtration, and solvent removed on a rotary evaporator. The residue was chromatographed on a silica gel column. Elution with 5% methanol/methylene chloride gave the titled compound (214 mg) as an oil. Analysis for C 39 H 56 N 2 O 6 (MW=648.89): Calcd.: C, 72.18; H, 8.70; N, 4.32. Found: C, 72.29; H, 8.85; N, 4.26. EXAMPLE 50 3,4-dihydro-4-oxo-8-propyl-7-[3-[(5,6,7,8-tetrahydro-1-naphthalenyl)oxy]propoxy]-2H-1-benzopyran-2,2-dipropanoic acid monoethyl ester ##STR67## To a solution of the titled product of Example 43 (676 mg, 1.25 mmol) in 5 ml of dimethylformamide (DMF) was added 190 mg (1.25 mmol) of 1,8-diazabicyclo (5.4.0)undec-7-ene followed by 585 mg (3.75 mmol) of iodoethane. After stirring overnight at room temperature, the solvent was removed under reduced pressure. The residue was dissolved in CH 2 Cl 2 . The solution was then washed with 3N hydrochloric acid, dried (Na 2 SO 4 ), filtered, and the solvent removed on a rotary evaporator. The residue was chromatographed on a silica gel column. Elution with 35% ethyl acetate/61.5% hexane/2.5% acetic acid as eluent produced the title product which was crystallized from 3:1 hexane:ethyl acetate to give 183 mg, m.p. 83.5°-84.5° C. Analysis for C 33 H 42 O 8 (MW=566.70): Calcd.: C, 69.95; H, 7.47. Found: C, 69.83; H, 7.58. EXAMPLE 51 methyl 3,4-dihydro-4-oxo-2-(3-oxo-3-[1-pyrrolidinyl]propyl)-8-propyl-7-[3-[(5,6,7,8-tetrahydro-1-naphthalenyl)oxy]propoxy]-2H-1-benzopyran-2-propanoate ##STR68## A mixture of 500 mg (1.20 mmol) of the title amide-ester of Example 2, 483 mg (1.8 mmol) of the title product of Example 12, and 348 mg (2.52 mmol) of anhydrous potassium carbonate in 12 ml of dimethylformamide was stirred at 90° C. (oil bath) for three hours. The mixture was permitted to cool, and the solvent was removed under reduced pressure. The residue was partitioned between ethyl acetate and water, and the aqueous layer was further extracted with two portions of ethyl acetate. The combined organic extracts were washed with brine, dried over sodium sulfate, filtered, and the solvent removed under reduced pressure. Chromatography of the residue over silica gel, using methanol-methylene chloride as eluent, gave a solid which was triturated with diethyl ether to give the title compound (468 mg), m.p. 106°-107° C. Analysis for C 36 H 47 NO 7 (MW=605.78): Calcd.: C, 71.38; H, 7.82; N, 2.31. Found: C, 71.36; H, 8.00; N, 2.29. EXAMPLE 52 3,4-dihydro-4-oxo-2-[3-oxo-3-(1-pyrrolidinyl)propyl]-8-propyl-7-[3-[(5,6,7,8-tetrahydro-1-naphthalenyl)oxy]propoxy]-2H-1-benzopyran-2-propanoic acid ##STR69## To a solution of 240 mg (0.40 mmol) of the title product of Example 51 in 4 ml of methanol was added 0.15 ml of a 50% aqueous solution of sodium hydroxide and 1 ml of water. The mixture was stirred for 1 hour at reflux and then permitted to cool. The cooled reaction mixture was partitioned between ethyl acetate and 3N hydrochloric acid, and the aqueous layer was further extracted with two portions of ethyl acetate. The combined organic extracts were washed with brine, dried over sodium sulfate, filtered, and the solvent removed under reduced pressure. Chromatography of the residue over silica gel, using methanol/ethyl acetate/acetic acid as eluent, gave a glass which was triturated with diethyl ether to give the title compound (61 mg) as a solid, m.p. 160°-164° C. Analysis for C 35 H 45 NO 7 (MW=591.75): Calcd.: C, 71.04; H, 7.66; N, 2.37. Found: C, 70.60; H, 7.65; N, 2.29. EXAMPLE 53 3,4-dihydro-4-hydroxy-7-(3-phenoxypropoxy)-8-propyl-2H-1-benzopyran-2,2-dipropanoic acid ##STR70## To a stirred solution of 78 mg (2.1 mmol) of NaBH 4 in 2 ml of water at 0° C. is added over 3 minutes a solution of 250 mg (0.515 mmol) of the title product of Example 17 in 3 ml of tetrahydrofuran (THF). After 30 minutes at 0° C., the mixture was permitted to warm to room temperature, and a further 2 ml each of water and of THF were added. After one hour, the reaction mixture was acidified with 3N hydrochloric acid, and the mixture was extracted with three portions of ethyl acetate. The combined organic extracts were washed with brine, dried (Na 2 SO 4 ), the drying agent removed by filtration, and the solvent removed under reduced pressure. Crystallization of the residue from 50% ethyl acetate/hexane gave the title compound (150 mg), m.p. 131.5°-132.5° C. Analysis for C 27 H 34 O 8 (MW=486.57): Calcd.: C, 66.65; H, 7.04. Found: C, 66.78; H, 6.64. EXAMPLE 54 3,4-dihydro-4-hydroxy-8-propyl-7-[3-[(5,6,7,8-tetrahydro-1-naphthalenyl)oxy]propoxy]-2H-1-benzopyran-2,2-dipropanol ##STR71## To a stirred suspension of 319 mg (8.40 mmol) of LiAlH 4 in 12 ml of tetrahydrofuran (THF) at 0° C. was added a solution of 1.00 g (1.68 mmol) of the title product of Example 42 in 5 ml of tetrahydrofuran. After one-half hour, the mixture was permitted to warm to room temperature, and stirred further for two hours. The reaction was then quenched by sequentially adding 320 μl of water, 320 μl of 15% aqueous sodium hydroxide, and 960 μl of water. The formed salts were removed by filtration, and the solvent removed under reduced pressure to give the title compound (770 mg) as a white solid, m.p. 123°-123.5° C. Analysis for C 31 H 44 O 6 (MW=512.69): Calcd.: C, 72.62; H, 8.65. Found: C, 72.59; H, 8.79. EXAMPLE 55 diethyl 3,4-dihydro-7-(3-phenoxypropoxy)-8-propyl-2H-1-benzopyran-2,2-dipropanoate ##STR72## A mixture of 370 mg (0.941 mmol) of the title product of Example 44, 243 mg (1.13 mmol) of 1-bromo-3-phenoxypropane, and 273 mg (1.98 mmol) of anhydrous potassium carbonate in 10 ml of dimethylformamide was stirred overnight at room temperature. Thereafter, the solvent was removed under reduced pressure, and the residue was partitioned between ethyl acetate and water. The aqueous layer was separated, acidified with 3N hydrochloric acid, and the layers reshaken. The aqueous layer was further extracted with two portions of ethyl acetate. The combined organic extracts were dried over magnesium sulfate, and the solvent was removed under reduced pressure. The title compound (185 mg) was obtained after chromatography on silica gel using 20% ethyl acetate/hexane as eluent. Analysis for C 31 H 42 O 7 (MW=526.68): Calcd.: C, 70.69; H, 8.04. Found: C, 70.67; H, 7.95. EXAMPLE 56 3,4-dihydro-7-(3-phenoxypropoxy)-8-propyl-2H-1-benzopyran-2,2-dipropanoic acid ##STR73## The title compound (118 mg), m.p. 130.5°-132.5° C., was prepared by the method of Example 22 substituting the title product of Example 55 (140 mg) for the title product of Example 21. Analysis for C 27 H 34 O 7 (MW=470.57): Calcd.: C, 68.91; H, 7.28. Found: C, 68.54; H, 7.15. EXAMPLE 57 2-bromo-1-tetrahydropyranyloxyethane ##STR74## The title compound was prepared according to the method disclosed in J. Am. Chem. Soc., 1948, 70, 4187. EXAMPLE 58 2-(5,6,7,8-tetrahydro-1-naphthoxy)-1-tetrahydropyranyloxyethane ##STR75## A mixture of 1.48 g (10 mmol) of 5,6,7,8-tetrahydro-1-naphthol, 0.34 g (1.0 mmol) of tetra-n-butylammonium hydrogen sulfate, 6.27 (30 mmol) of the title product of Example 57, 20 ml of methylene chloride, 9 ml of water, and 11 ml of 1N sodium hydroxide was stirred vigorously overnight at reflux. The organic layer was separated, and the solvent removed under reduced pressure. The residue was triturated with diethyl ether and filtered to remove the insolubles. The ether solution was sequentially washed with two portions of dilute aqueous sodium hydroxide, with water, and then with brine. After drying over magnesium sulfate, the solution was filtered and the solvent was removed under reduced pressure. Chromatography of the residue on silica gel, using 5% ethyl acetate/hexane as eluent gave 730 mg of the title compound. 1 H NMR (CDCl 3 ): δ7.01(dd, J=7 Hz, J=7 Hz, 1H); 6.66(d, J=7 Hz, 1H); 6.64(d, J=7 Hz, 1H); 4.73(br s, 1H); 4.20-3.38(m, 6H); 2.69(m, 4H); and 1.90-1.45(m, 10H). EXAMPLE 59 2-(5,6,7,8-tetrahydro-1-naphthoxy)ethanol ##STR76## A solution of 700 mg (2.54 mmol) of the title product of Example 58 in a mixture of 9 ml of acetic acid, 3 ml of tetrahydrofuran, and 3 ml of water was stirred at 85°-90° C. After 3.5 hours, 4 drops of concentrated sulfuric acid were added and stirring continued for an additional one-half hour. The mixture was permitted to cool, and 4 g of sodium carbonate monohydrate was added. The resulting mixture was partitioned between diethyl ether and water. The organic layer was washed repeatedly with saturated aqueous sodium bicarbonate, with water, and then with brine. The solution was dried over magnesium sulfate, the drying agent was removed by filtration, and the solvent was removed under reduced pressure. Chromatography of the residue on silica gel, using 15% ethyl acetate/toluene as eluent, gave 216 mg of the title compound. 1 H NMR (CDCl 3 ): δ7.11(dd, J=7 Hz, J=7 Hz, 1H); 6.68(d, J=7 Hz, 1H); 6.61(d, J=7 Hz, 1H); 4.04(m, 4H); 2.70(m, 4H); 1.76(m, 4H); and 1.56(s, 1H). EXAMPLE 60 diethyl 3,4-dihydro-4-oxo-8-propyl-7-[2-[(5,6,7,8-tetrahydro-1-naphthalenyl)oxy]ethoxy]-2H-1-benzopyran-2,2-dipropanoate ##STR77## A solution of 202 mg (1.05 mmol) of the title product of Example 59 in 10 ml of CH 2 Cl 2 was cooled with stirring to 0° C. and treated sequentially with 370 mg (3.70 mmol) of triethylamine and 362 mg (3.15 mmol) of methanesulfonyl chloride. After one hour, the mixture was treated with another 370 mg of triethylamine and 362 mg of methanesulfonyl chloride. After one-half hour, the mixture was washed successively with water, aqueous sodium bicarbonate solution, dilute aqueous hydrochloric acid, and water. The organic phase was dried (MgSO 4 ), filtered, and the solvent removed under reduced pressure. The residue was taken up in 10 ml of dimethylformamide. To the resulting solution was added 406 mg (1.00 mmol) of the title product of Example 1 and 290 mg (2.10 mmol) of anhydrous potassium carbonate. The mixture was stirred overnight at room temperature. Another 290 mg of potassium carbonate was then added, and stirring was continued at 60° C. for six hours. The mixture was allowed to cool, and the solvent was removed under reduced pressure. The residue was partitioned between ethyl acetate and water. The aqueous layer was further extracted with two portions of ethyl acetate. The combined organic extracts were washed successively with water and with brine, dried (Na 2 SO 4 ), filtered, and the solvent removed under reduced pressure. The residue was chromatographed over silica gel. Elution with 15% ethyl acetate/toluene produced 152 mg of the title compound as a solid. 1 H NMR (CDCl 3 ): δ7.71(d, 1H); 7.04(d, 1H); 6.73(d, 1H); 6.70(d, 1H); 6.59(d, 1H); 4.34(m, 4H); 4.10(q, 4H); 2.85-1.43(m, 22H); 1.24(t, 6H); and 0.90(t, 3H). EXAMPLE 61 3,4-dihydro-4-oxo-8-propyl-7[2-[(5,6,7,8-tetrahydro-1-naphthalenyl)oxy]ethoxy]-2H-1-benzopyran-2,2-dipropanoic acid ##STR78## A mixture of 150 mg (0.277 mmol) of the titled product of Example 60, 3 ml of methanol, and 3 ml of 1N sodium hydroxide was stirred at reflux for one hour. The reaction mixture was permitted to cool and then partitioned between ethyl acetate and 3N hydrochloric acid. The aqueous layer was further extracted with two portions of ethyl acetate. The combined organic extracts were washed with brine, dried (MgSO 4 ), filtered, and the solvent removed under reduced pressure. Crystallization of the residue from ethyl acetate gave 24 mg of the title compound as a solid, m.p. 159.5°-161.5° C. Analysis for C 30 H 36 O 8 (MW=524.62): Calcd.: C, 68.68; H, 6.92. Found: C, 68.43; H, 6.96. EXAMPLE 62 N-(2-propylidine)cyclohexylamine ##STR79## The title compound was prepared by the method disclosed in J. Org. Chem., 19, 1054 (1954). EXAMPLE 63 nona-1,8-dien-5-one ##STR80## To a solution of 16.0 g (158 mmol) of diisopropylamine in 150 ml of tetrahydrofuran at 0° C. was added 158 ml of a 1.0M solution of n-butyllithium in hexane. The reaction mixture was cooled to -30° C., and to it was added a solution of 20.2 g (144 mmol) of the title product of Example 62 in 75 ml of tetrahydrofuran. After 1.0 hour at -30° C., the mixture was cooled to -70° C. To the resulting mixture was then added 26.1 g of allyl bromide in 38 ml of tetrahydrofuran. After 10 minutes, the mixture was permitted to warm to room temperature, and after 2 hours, it was poured into brine. The aqueous layer was further extracted with diethyl ether. After drying the combined extracts over sodium sulfate followed by filtration, the solvent was removed and the residue distilled to give a crude product (8.53 g) which was used without further purification. A solution of 4.14 g of the crude material in 13 ml of tetrahydrofuran was added to a mixture of 2.57 g of diisopropylamine, 25.4 ml of a 1.0M solution of n-butyllithium in hexane, and 25 ml of tetrahydrofuran at -30° C. The resulting mixture was kept for one hour at -30° C., and thereafter 3.0 g of allyl bromide was added. After stirring overnight at room temperature, the mixture was poured into brine, the aqueous layer extracted with diethyl ether, and the combined organic solutions dried over sodium sulfate. After filtration, the solvent was removed, and the residue was then stirred overnight in a mixture of 50 ml of diethyl ether and 50 ml of 3N hydrochloric acid. The mixture was then poured into brine and the aqueous layer was further extracted with diethyl ether. The combined organic extracts were dried over magnesium sulfate, and filtered. The solvents were removed by distillation through a Vigreaux column at atmospheric pressure. Distillation of the residue at 5 mm of pressure gave the title compound (719 mg), suitable for use in the next reaction step. H NMR (CDCl 3 ): δ6.05-4.83(m, 6H); and 2.68-2.05(m, 8H). IR (CHCl 3 ) 1715 cm -1 , 1642 cm -1 . EXAMPLE 64 2,2-bis(but-3-enyl)-2,3-dihydro-8-propyl-7-hydroxy-4H-1-benzopyran-4-one ##STR81## A mixture of 719 mg (5.21 mmol) of the title product of Example 63, 970 mg (5.00 mmol) of 2,4-dihydroxy-3-propylacetophenone, 360 mg (5.00 mmol) of pyrrolidine, and 5.5 ml of toluene containing 2.0 g of 3A molecular sieves was stirred at reflux for six hours, then kept overnight at room temperature. The solution was then decanted from the sieves, and the sieves were washed with methylene chloride. The solvent was then removed under reduced pressure. Chromatography of the residue over silica gel, using 14:5:1 methylene chloride:hexane:ethylacetate as eluent, gave the title compound (439 mg) as a solid. Analysis for C 20 H 20 O 3 (MW=314.43): Calcd.: C, 76.40; H, 8.34. Found: C, 76,31; H, 8.47. EXAMPLE 65 2,2-bis(but-3-enyl)-2,3-dihydro-8-propyl-7-[3-[(5,6,7,8-tetrahydro-1-naphthelenyl)oxy]propoxy]-4H-1-benzopyran-4-one ##STR82## A solution of 366 mg (1.17 mmol) of the title product of Example 64 and 695 mg (2.04 mmol) of the title product of Example 12 in 11 ml of dry dimethylforamide was treated with 338 mg (2.45 mmol) of anhydrous potassium carbonate. The mixture was stirred for 2 hours at 80° C., then permitted to cool. The solvent was removed under reduced pressure, and the residue was partitioned between ethyl acetate and water. The aqueous layer was extracted with a fresh portion of ethyl acetate. The combined organic extracts were washed with brine, dried over magnesium sulfate, filtered, and the solvent evaporated. The residue was chromatographed over silica gel to give 503 mg of the title compound. 1 H NMR (CDCl 3 ): δ7.70(d, 1H); 7.01(dd, 1H); 6.64(d, 1H); 6.58(d, 1H); 6.54(d, 1H); 6.01-4.81(m, 6H); 4.20(t, 2H); 4.13(t, 2H); 2.80-1.23(m, 24H); and 0.90(t, 3H). EXAMPLE 66 2,2-bis(3,4-dihydroxybutyl)-2,3-dihydro-8-propyl-7-[3-[(5,6,7,8-tetrahydro-1-naphthalenyl)oxy]propoxy]-4H-1-benzopyran-4-one ##STR83## To a solution of 500 mg (1.00 mmol) of the title product of Example 58 in a mixture of 4.8 ml of t-butanol and 1.5 ml of tetrahydrofuran (THF) was added successively 0.5 ml of water, 288 mg (2.13 mmol) of N-methylmorpholine-N-oxide, and 0.2 ml of a 1% solution of osmium tetraoxide (OsO 4 ) in t-butanol. After 2.5 hours, the reaction mixture was directly applied to a column of silica gel. Elution of the column with 15% methanol/methylene chloride gave a crude product which was triturated with diethyl ether to give the title compound (453 mg) as a hemihydrate, m.p.=113°-115° C. Analysis for C 33 H 46 O 8 .1/2H 2 O (MW=579.74): Calcd.: C, 68.38; H, 8.17. Found: C, 68.02; H, 7.93. EXAMPLE 67 3,4-dihydro-4-oxo-8-propyl-7-[3-[(5,6,7,8-tetrahydro-1-naphthalenyl)oxy]propoxy]-2H-1-benzopyran-2,2-dipropanal ##STR84## To a solution of 90 mg (0.158 mmol) of the title product of Example 66 in 3.7 ml of t-butanol was added a solution of 135 mg (0.629 mmol) of sodium periodate in 1.0 ml of H 2 O. After stirring at room temperature for 2 hours, the mixture was partitioned between diethyl ether and water and the aqueous layer extracted with a fresh portion of ether. The combined organic extracts were washed with brine, dried over magnesium sulfate, filtered, and the solvent removed under reduced pressure. The residue was triturated with diethyl ether to give the title compound (61 mg), m.p. 107°-108° C. Analysis for C 31 H 38 O 6 (MW=506.65): Calcd.: C, 73.48; H, 7.56. Found: C, 73.09; H, 7.76. EXAMPLE 68 undeca-1,10-dien-6-one ##STR85## To a solution of 10.7 g of diispropylamine in 100 ml of tetrahydrofuran at 0° C. was added 74.1 ml of a 1.43M solution of n-butyllithium in hexane. After 15 minutes the solution was cooled to -30° C. To the mixture was then added a solution of 13.5 g of the title product of Example 62 in 50 ml of tetrahydrofuran, and the resulting mixture was kept for 1 hour at -30° C. The mixture was then cooled to -65° C. and to it was added a solution of 19.6 g of 4-bromo-1-butene in 25 ml of tetrahydrofuran. The mixture was then permitted to warm to room temperature overnight. The mixture was poured into brine, and the aqueous layer was extracted with two portions of diethyl ether. The combined organic extracts were dried over sodium sulfate, filtered, and the solvent removed under reduced pressure. Distillation of the residue gave 10.68 g of material which was dissolved in 30 ml of tetrahydrofuran, then added to a cooled mixture (-30° C.) of 8.5 ml of diisopropylamine 42.7 ml of a 1.43M solution of n-butyllithium in hexane, and 50 ml of tetrahydrofuran. After 1 hour, the mixture was cooled to -65° C., and a solution of 11.2 g of 4-bromo-1-butene in 15 ml of tetrahydrofuran. After permitting the mixture to warm to room temperature overnight, the mixture was poured into brine, and the aqueous layer extracted with two portions of diethyl ether. The combined organic extracts were dried over magnesium sulfate, filtered, and the solvent removed in vacuo. The residue (13.8 g) was then stirred overnight in a mixture of 100 ml of diethyl ether and 100 ml of dilute hydrochloric acid. The layers were separated, and the aqueous layer was extracted with two portions of diethyl ether. The combined organic extracts were washed with brine, dried over magnesium sulfate, and filtered. The solvent was removed by distillation through a Vigreaux column at atmospheric pressure. Continued distillation gave the title compound (4.39 g), b.p. 85°-87° C. at 2.0 mm. Analysis for C 11 H 18 O (MW=166.27): Calcd.: C, 79.43; H, 10.91. Found: C, 79.54; H, 11.01. EXAMPLE 69 2,3-dihydro-2,2-bis(pent-4-enyl)-8-propyl-7-hydroxy-4H-1-benzopyran-4-one ##STR86## A mixture of 3.93 g (20.2 mmol) of 2,4-dihydroxy-3-propylacetophenone, 3.36 g (20.2 mmol) of the title product of Example 68, 1.44 g (20.2 mmol) of pyrrolidine, and 23.5 ml of toluene was stirred at reflux under a water separator containing 3A molecular sieves for 5 hours. The mixture was then permitted to cool, and the solvent was removed under reduced pressure. Chromatography of the residue over silica gel using 25% ethyl acetate/hexane as eluant gave the title compound (5.85 g) as a dark red oil. 1 H NMR (CDCl 3 ): δ8.33(br s, 1H); 7.62(d, 1H); 6.53(d, 1H); 6.02-4.73(m, 6H); 2.82-1.17(m, 18H); and 0.97(t, 3H). EXAMPLE 70 2,3-dihydro-2,2-bis(pent-4-enyl)-8-propyl-7-[3-[(5,6,7,8-tetrahydro-1-naphthalenyl)oxy]propoxy]-4H-1-benzopyran-4-one ##STR87## To a solution of 3.0 g (9.55 mmol) of the title product of Example 69 and 4.01 g (11 mmol) of the title product of Example 12 in 56 ml of dry dimethylformamide (DMF) was added 2.77 g (20.1 mmol) of anhydrous potassium carbonate. The resulting mixture was stirred overnight at room temperature. The solvent was removed in vacuo, and the residue was partitioned between ethyl acetate and 3N hydrochloric acid. The aqueous layer was further extracted with two portions of ethyl acetate. The combined organic extracts were washed with water and with brine, dried over magnesium sulfate, filtered, and the solvent removed under reduced pressure. Chromatography of the residue over silica gel, using 10% ethyl acetate/hexane as eluent, gave the title compound (4.19 g) as an oil. 1 H NMR (CDCl 3 ): δ7.68(d, 1H); 7.00(dd, 1H); 6.68(d, 1H); 6.65(d, 1H); 6.53(d, 1H); 6.00-4.76(m, 6H); 4.21(t, 2H); 4.13(t, 2H); 2.83-1.23(m, 28H); and 0.93(t, 3H). EXAMPLE 71 2,3-dihydro-2,2-bis(4,5-dihydroxypentyl)-8-propyl-7-[3-[(5,6,7,8-tetrahydro-1-naphthalenyl)oxy]propoxy]-4H-1-benzopyran-4-one ##STR88## To a solution of 1.00 g (1.99 mmol) of the title product of Example 70 in a mixture of 9.5 ml of t-butanol, 2.9 ml of tetrahydrofuran, and 0.95 ml of water was added 576 mg (4.26 mmol) of N-methylmorpholine-N-oxide followed by 0.4 ml of a 1% solution of osmium tetraoxide (OsO 4 ) in t-butanol. After 2.5 hours at room temperature, the reaction mixture was directly applied to a column of silica gel. Elution with 15% methanol/methylene chloride gave a glass which was triturated with diethyl ether to give the title compound (830 mg), m.p. 87°-88° C. Analysis for C 35 H 50 O 8 (MW=598.78): Calcd.: C, 70.21; H, 8.42. Found: C, 69.95; H, 8.41. EXAMPLE 72 3,4-dihydro-4-oxo-8-propyl-7-[3-[(5,6,7,8-tetrahydro-1-naphthalenyl)oxy]propoxy]-2H-1-benzopyran-2,2-dibutanal ##STR89## To a solution of 200 mg (0.350 mmol) of the title product of Example 71 in 9.8 ml of t-butanol was added with stirring a solution of 300 mg (1.40 mmol) of sodium periodate in 2.2 ml of water. After two hours, the mixture was partitioned between diethyl ether and water. The organic layer was washed with brine, dried over sodium sulfate, filtered, and the solvent removed under reduced pressure. The residue was chromatographed on a silica gel column, using ethyl acetate/hexane as eluent. Crystallization from diethyl ether/hexane gave 114 mg of the title compound, m.p. 72°-73° C. Analysis for C 33 H 42 O 6 (MW=534.70): Calcd.: C, 74.14; H, 7.92. Found: C, 74.25; H, 7.94. EXAMPLE 73 3,4-dihydro-4-oxo-8-propyl-7-[3-[(5,6,7,8-tetrahydro-1-naphthalenyl)oxy]propoxy]-2H-1-benzopyran-2,2-dibutanoic acid ##STR90## To a solution of 98 mg (0.183 mmol) of the title product of Example 72 in 3.1 ml of dioxane was added a solution of 87 mg (0.89 mmol) of sulfamic acid in 0.8 ml of water. The solution was cooled in an ice bath, and a solution of 84 mg of 80% sodium chlorate in 0.8 ml of water was added. After one hour, diethyl ether was added, and the organic layer was washed five times with water, once with brine. The solution was dried over magnesium sulfate, filtered, and the solvent removed in vacuo to give the title compound (92 mg), m.p. 138°-138.5° C. Analysis for C 33 H 42 O 8 (MW=566.70): Calcd.: C, 69.95; H, 7.47. Found: C, 69.93; H, 7.55. EXAMPLE 74 2,2-bis[4,5-bis(acetyloxy)pentyl]-2,3-dihydro-8-propyl-7-[3-[(5,6,7,8-tetrahydro-1-naphthalenyl)oxy]propoxy]-4H-1-benzopyran-4-one ##STR91## To a solution of 404 mg (0.708 mmol) of the title product of Example 71 in 4.4 ml of pyridine was added 0.70 ml (7.4 mmol) of acetic anhydride. After stirring overnight at room temperature, the mixture was taken up in ethyl acetate, and washed sequentially with two portions of aqueous sodium bicarbonate, water, and brine. The organic layer was dried over magnesium sulfate, filtered, and the solvent removed under reduced pressure. Chromatography of the residue over silica gel, using 40% ethyl acetate/hexane as the eluent, gave the title compound (314 mg). Analysis for C 43 H 58 O 12 (MW=766.93): Calcd.: C, 63.35; H, 7.62. Found: C, 67.23; H, 7.67. EXAMPLE 75 diethyl 3,4-dihydro-7-(octyloxy)-4-oxo-8-propyl-2H-1-benzopyran-2,2-dipropanoate ##STR92## The title compound (381 mg) was prepared by the method of Example 18 substituting the title product of Example 1 (406 mg; 1.00 mmol) for the title product of Example 2, and further substituting 1-bromooctane (232 mg; 1.20 mmol) for benzyl bromide. 1 H NMR (CDCl 3 ): δ7.69(d, 1H); 6.53(d, 1H); 4.10(q, 4H); 3.99(t, 2H); 2.64(br s, 2H); 1.24(t, 6H); 0.95(t, 3H); and 0.90(t, 3H). EXAMPLE 76 3,4-dihydro-7-(octyloxy)-4-oxo-8-propyl-2H-1-benzopyran-2,2-dipropanoic acid ##STR93## The title compound (231 mg), m.p. 147.5°-148.5° C., was prepared by the method of Example 20 substituting the title product of Example 75 (361 mg) for the title product of Example 19 and carrying out the reaction for 1.5 hours at reflux instead of for 2 hours at room temperature. Analysis for C 26 H 38 O 7 (MW=462.59): Calcd.: C, 67.51; H, 8.28. Found: C, 67,69; H, 8.48. EXAMPLE 77 diethyl 7-(decyloxy)-3,4-dihydro-4-oxo-8-propyl-2H-1-benzopyran-2,2-dipropanoate ##STR94## To a mixture of 406 mg (1.00 mmol) of the title product of Example 1, 190 mg (1.20 mmol) of 1-decanol, and 393 mg (1.50 mmol) of triphenylphosphine in 10 ml of dimethylformamide was added 261 mg (1.50 mmol) of diethyl azodicarboxylate. After stirring overnight at room temperature, the solvent was removed under reduced pressure. Chromatography of the residue on silica gel, using 20% ethyl acetate/hexane as eluent, gave 408 mg of the title compound. 1 H NMR (CDCl 3 ): δ7.70(d, 1H); 6.51(d, 1H); 4.09(q, 4H); 3.99(t, 2H); 2.63(br s, 2H); 1.23(t, 6H); 0.94(t, 3H); and 0.88(t, 3H). EXAMPLE 78 7-(decyloxy)-3,4-dihydro-4-oxo-8-propyl-2H-1-benzopyran-2,2-dipropanoic acid ##STR95## The title compound (198 mg), m.p. 144°-146° C., was prepared by the method of Example 20 substituting the title product of Example 77 for the title product of Example 19, and carrying out the reaction for two hours at reflux instead of for two hours at room temperature. Analysis for C 28 H 42 O 7 (MW=490.64): Calcd.: C, 68.55; H, 8.63. Found: C, 68.47; H, 8.66. EXAMPLE 79 diethyl 7-(hexyloxy)-3,4-dihydro-4-oxo-8-propyl-2H-1-benzopyran-2,2-dipropanoate ##STR96## The title compound (388 mg) was prepared by the method of Example 18 substituting the title product of Example 1 (406 mg; 1.00 mmol) for the title product of Example 2, and further substituting 1-bromohexane (198 mg, 1.20 mmol for benzyl bromide. 1 H NMR (CDCl 3 ): δ7.69(d, 1H); 6.51(d, 1H); 4.11(q, 4H); 3.99(t, 2H); 2.64(br s, 2H); 1.25(t, 6H); 0.95(t, 3H); and 0.91(t, 3H). EXAMPLE 80 7-(hexyloxy)-3,4-dihydro-4-oxo-8-propyl-2H-1-benzopyran-2,2-dipropanoic acid ##STR97## The title compound (168 mg) was prepared by the method of Example 20 substituting the title product of Example 79 for the title product of Example 19, and carrying out the reaction for 1 hour at reflux instead of for 2 hours at room temperature. The product was crystallized from ethyl acetate, m.p. 164.5°-165° C. Analysis for C 24 H 34 O 7 (MW 434.54): Calcd.: C, 66.35; H, 7.89. Found: C, 66.10; H, 7.97. EXAMPLE 81 diethyl 6-acetyl-3,4-dihydro-8-propyl-7-hydroxy-2H-1-benzopyran-2,2-dipropanoate ##STR98## To a solution of 790 mg (2.01 mmol) of the title product of Example 44 in 4 ml of acetic acid was added 547 mg (4.02 mmol) of anhydrous zinc chloride. The mixture was stirred for six hours at reflux, and then permitted to cool. The mixture was partitioned between ethyl acetate and dilute hydrochloric acid. The aqueous layer was further extracted with two portions of ethyl acetate. The combined organic extracts were washed successively with five portions of aqueous sodium bicarbonate, water, and then brine. The extracts were dried over sodium sulfate, filtered, and the solvent removed under reduced pressure. Chromatography of the residue over silica gel using 25% ethyl acetate/hexane as eluent gave the title compound, 230 mg. 1 H NMR (CDCl 3 ): δ12,55(s, 1H); 7.29(s, 1H); 4.13(q, 4H); 2.54(s, 3H); 2.90-1.43(m, 14H); 1.25(t, 6H); 0.95(t, 3H). EXAMPLE 82 diethyl 6-acetyl-3,4-dihydro-8-propyl-7-[3-[(5,6,7,8-tetrahydro-1-naphthalenyl)oxy]propoxy]-2H-1-benzopyran-2,2-dipropanoate ##STR99## A mixture of 204 mg (0.469 mmol) of the title product of Example 81, 378 mg (1.41 mmol) of the title product of Example 12, and 136 mg (0.985 mmol) of anhydrous potassium carbonate in 4 ml of dimethylformamide was stirred at 80° for six hours. A further 136 mg of potassium carbonate was added, and the mixture was heated for another six hours. The mixture was permitted to cool and was partitioned between ethyl acetate and dilute hydrochloric acid. The aqueous layer was further extracted with two portions of ethyl acetate. The combined organic extracts were washed with brine, dried over sodium sulfite, filtered, and the solvent removed under reduced pressure. Chromotography of the residue over silica gel using 15% ethyl acetate/toluene as eluent gave the title compound, 114 mg. Analysis for C 37 H 50 O 8 (MW=622.81): Calcd.: C, 71.36; H, 8.09. Found: C, 71.48; H, 8.08. EXAMPLE 83 6-acetyl-3,4-dihydro-8-propyl-7-[3-[(5,6,7,8-tetrahydro-1-naphthalenyl)oxy]propoxy]-2H-1-benzopyran-2,2-dipropanoic acid ##STR100## A mixture of 50 mg (0.080 mmol) of the title product of Example 77, 3 ml of methanol, and 1 ml of 1N aqueous sodium hydroxide was stirred at reflux for one hour. The mixture was allowed to cool, and was partitioned between ethyl acetate and dilute hydrochloric acid. The aqueous layer was further extracted with two portions of ethyl acetate. The combined organic extracts were washed with brine, dried over magnesium sulfate, filtered, and the solvent removed under reduced pressure to give the title compound (35 mg), as an oil. Analysis for C 33 H 42 O 8 (MW=566.70): Calcd.: C, 69.69; H, 7.47. Found: C, 70.28; H, 7.86. EXAMPLE 84 3,4-dihydro-4-oxo-7-(3-phenoxypropoxy)-8-propyl-2H-1-benzopyran-2,2-dipropanoic acid, dipotassium salt ##STR101## To a suspension of 250 mg (0.515 mmol) of the title product of Example 17 in 5 ml of water was added a solution of 71 mg (0.52 mmol) of anhydrous potassium carbonate in 5 ml of water. A 5 ml portion of methanol was added, and the resulting mixture was warmed to effect solution. The solvent was evaporated under a stream of nitrogen, and the residue was dried by azeotropic distillation with toluene to give the title compound, 269 mg, isolated as the hemihydrate. Analysis for C 27 H 30 K 2 O 8 .1/2H 2 O (MW=569.75): Calcd.: C, 56.91; H, 5.48. Found: C, 56.55; H, 5.71.

This invention relates to 2,2-di-substituted benzopyran compounds which possess leukotriene-D 4 (LTD 4 ) antagonistic activity. In particular this invention relates to LTD 4 antagonists of the formula: ##STR1## or a pharmaceutically acceptable addition salt thereof, wherein R 1 is methyl, phenyl, ##STR2## wherein X 1 and X 2 may be the same or different and are members of the group comprising hydrogen, --Cl, --Br, --CF 3 , --NH 2 , --NO 2 , or straight or branched chain alkyl of 1-3 carbon atoms; wherein m is an integer from 1-9; wherein n is an integer from 1-5; wherein V is >C═O, --CH(OH)--, or --CH 2 --; wherein W is hydrogen or straight or branched chain alkyl of 1-6 carbon atoms; wherein Y is hydrogen or --COCH 3 ; wherein Z is --CHO, --COOR 2 , --COR 3 , ##STR3## or --CH 2 OR 4 ; wherein R 2 is hydrogen, a pharmaceutically acceptable cation, straight or branched chain alkyl having 1-6 carbon atoms, ##STR4## or --CH(CH 2 OR 5 ) 2 with the proviso that when Z is --COOR 2 , the R 2 substituent in one --COOR 2 moiety may be the same or different from the R 2 substituent in the other COOR 2 moiety; wherein R 3 is ##STR5## and wherein R 7 and R 8 may be the same or differnt and are members of the group comprising hydrogen or straight or branched chain alkyl having 1-6 carbon atoms; or wherein N, R 7 and R 8 may together form a cyclic amine of the formula ##STR6## wherein p is 4 or 5; wherein R 4 is hydrogen, or ##STR7## wherein R 5 is hydrogen, benzyl-, or straight or branched chain alkyl having 1-3 carbon atoms; and wherein R 6 is straight or branched chain alkyl having 1-6 carbon atoms.

This invention relates in general to magazine fed container forming apparatus and deals more particularly with improvements in machines for forming paper receptacles. The invention is more particularly concerned with improvements in machines for cutting paper blanks used in magazine fed rotary turret type receptacle forming machines. In a receptacle forming machine of the latter type, precut blanks supported in vertically stacked relation within a magazine are successively fed from the bottom of the magazine to a forming station where each successive blank is wrapped onto an associated mandrel mounted on a rotary turret and seamed to form the body portion of a receptacle. The mandrel with the receptacle body thereon may then be indexed by the turret to a plurality of successive work stations where a pre-formed receptacle bottom is joined with the body portion of the receptacle and further edge forming operations are performed to complete the receptacle. The paper blanks from which receptacle bodies are formed are usually cut or otherwise shaped on another machine, stacked, and manually loaded into the magazine of the receptacle forming machine. Customarily, one machine operator may load and service several operating receptacle forming machines. However, when a service problem is encountered on one or more of the receptacle forming machines which interrupts the operator's normal machine loading cycle, the supply of receptacle blanks in the magazine or magazines of one or more of the other forming machines may become exhausted, causing the empty machine or machines to shut down resulting in costly machine down time. Accordingly, it is the general aim of the present invention to provide an improved magazine fed receptacle forming apparatus of the aforedescribed general type which eliminates manual magazine loading operations and assures a substantially continuous supply of receptacle blanks to a receptacle forming machine at all times. SUMMARY OF THE INVENTION In accordance with the present invention an improved apparatus is provided which comprises a paper receptacle forming machine which has a receptacle forming station, an upwardly open magazine for receiving and containing a supply of vertically stacked receptacle blanks, and means for feeding successive receptacle blanks from the magazine to the forming station. In accordance with the invention the apparatus further includes an improved separate blanking machine operable independently of the receptacle forming machine and having blanking means for forming a succession of receptacle blanks and blank guiding means forming a vertical extension of the magazine for receiving receptacle blanks from the blanking means. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a typical receptacle of the type made using apparatus embodying the present invention. FIG. 2 is schematic side elevational view of apparatus embodying the present invention. FIG. 3 is a perspective view of a vertical in-line blanking machine which comprises a part of the apparatus shown in FIG. 2. FIG. 4 is a somewhat enlarged schematic fragmentary side elevational view of a portion of the apparatus shown in FIG. 2. FIG. 5 is a fragmentary sectional view taken along the line 5--5 of FIG. 4. FIG. 6 is a somewhat schematic plan view of the die set shown in FIG. 4. FIG. 7 is a sectional view taken generally along the line 7--7 of FIG. 6. FIG. 8 is a somewhat further enlarged fragmentary plan view of a portion of a magazine which comprises part of another apparatus embodying the invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The present invention is hereinafter illustrated and described with reference to apparatus for forming paper receptacles and more particularly cup-shaped containers, such as the container or cup shown in FIG. 1 and indicated generally by reference numeral 10. The apparatus, shown schematically in FIG. 2 and indicated generally by reference numeral 12, essentially comprises an improved vertical in-line blanking machine, indicated generally at 14, and a magazine fed receptacle forming machine designated generally by the numeral 16. The blanking machine 14 cuts or punches receptacle blanks used to form the bodies of cup-shaped receptacles, such as the cup 10, and includes guide means which cooperate with and form a vertical extension of the magazine on the associated cup forming machine 14 for feeding receptacle blanks to the forming machine, all of which will be hereinafter more fully discussed. The illustrated container forming machine 16, comprises a rotary turret type machine which may be of single or double turret type. It includes an upwardly open magazine indicated generally at 18 and defined, at least in part, by a plurality of spaced apart and vertically upwardly extending magazine rods 20, 20. The magazine is adapted to receive and contain in vertically stacked relation a plurality of receptacle blanks B, B from which body portions of receptacles, such as the cup 10 are formed. The machine 16 further includes at least one turret 22 supported for indexable rotation about a vertical axis 24, best shown in FIG. 4. A plurality of mandrels 26, 26 mounted on fixed position on the turret 22 project radially outwardly from it, as best shown in FIG. 5. The number of mandrels may vary, however, the illustrated turret 22 carries 8 mandrels and is particularly adapted for indexable rotation in 45 degree angular increments about its axis 24 to present each individual mandrel at a first forming station indicated generally at 28 and aligned with the magazine 18. Each successive container blank B in the magazine 18 is fed from the bottom of the magazine by an associated feeding mechanism, such as the pusher mechanism, shown somewhat schematically in FIG. 4 and indicated generally by the reference numeral 30, and to the forming station 28 wherein associated mechanism which comprises a part of the machine 16 wraps the blank B around a mandrel 26 and forms a seam S along the overlapping edges of the blank to complete a body portion of a receptacle, such as the cup 10. Thereafter, the mandrel with an associated receptacle body portion thereon is indexed to a further work station or stations where a receptacle bottom is joined to the body portion and required edge forming operations are performed, in a manner well known in the receptacle making art. Receptacle forming machines of the aforedescribed general type are well known in the art. A typical double turret paper cup making machine of the type hereinbefore generally described is illustrated and described in somewhat more detail in U.S. Pat. No. 3,289,552 to Corazzo, assigned to the assignee of the present invention, and hereby adopted by reference as part of the present disclosure. Considering now the improved vertical in-line blanking machine 14 and referring particularly to FIGS. 2 and 3 of the drawings, the machine 14 is portable and includes a frame indicated generally at 31 which may, if desired, define a portion of the magazine 18. The frame 31 is mounted on a pair of front casters 32, 32 (one shown) and a pair of rear swivel casters 34, 34 (one shown) to facilitate travel along a substantially smooth horizontal floor surface. The machine 14 has a die set, indicated generally at 36, mounted on the upper forward end portion of the machine frame 31. The die set comprises a stationary die assembly 38 which includes a die and movable punch assembly 40 which includes a punch which complements the die. The punch is operated by an associated power driven toggle mechanism which moves it alternately toward and away from the die for punching blanks B,B from a web of paper W intermittently fed through the die set in timed relation to the operation of the die set. The machine 14 preferably includes means for loading a roll or web W of paper onto and supporting it on the machine frame 31. The web W is fed over and under a plurality of transversely extending rolls 42, 42 which are journalled on the frame 31 and cooperate to form a closed loop tensioning system. A decurling system which includes transversely extending decurling rolls 44, 44 flattens the curled web to assure the production of flat blanks B, B. First and second sets of drive rolls, indicated generally at 46, 46 and 48, 48 in FIG. 2, advance the web in a free loop through first guides 50 to a third set of drive rolls 52, 52 which advance the web through second guides 54 into and through the die set 36. Preferably, the machine also includes a suitable scanning device for detecting registration marks on the paper web W to control the web feed mechanism and assure proper positioning of printed material in registration with the die set, all of which is well known in the blanking machine art. In accordance with the present invention, the blanking machine 14 includes a guiding device, indicated generally at 56, which forms a vertical extension of the magazine 18 when the blanking machine 14 is properly positioned with respect to the receptacle forming machine 16. The presently preferred guiding device 56 comprises a plurality of parallel guide rods 58, 58 mounted on the stationary die assembly and depending from it. When the two machines are properly aligned the lower end portions of the guide rods 58, 58 are disposed between associated upper end portions of the magazine rods 20, 20 and cooperate with the magazine rods to form a vertically upwardly extending part of the magazine 18. The illustrated blanking machine 12 further includes a sensing device, indicated generally at 60 in FIG. 3, associated with the guiding device 56 and responsive to the vertical height of a stack of container blanks within the confines of said magazine for controlling operation of the blanking machine 14. In the illustrated embodiment of the apparatus 12 the sensing device 60 comprises a photosensor 61, such as a photocell, phototube, phototransister, or the like, and a light source 63 mounted on the blanking machine 14 in vertically adjustable relation to the guiding device 56 for detecting the height a stack of blanks B, B within the magazine, or more specifically within the portion of the magazine defined by the guide rods 58, 58. The sensing device 60 is preferably connected through an amplifier to the blanking machine drive to stop the machine 14 when the stack height reaches a predetermined level within the magazine. The sensing device 60 may be further arranged to restart the blanking machine 14 when the height of the stack of blanks B, B within the magazine 18 reaches a predetermined lower level, whereby to maintain a continuous supply of blanks B, B within the magazine 18 to assure uninterrupted operation of the container forming machine 16. Thus, for example, the sensing device 60 may include a suitable electrical switch operated by a timer for restarting the machine 14 after a predetermined shut-down time has elapsed. Preferably, and as shown, the blanking machine 14 further includes a blank engaging device for assuring separation of each successive cut blank B from the die set 36 and for urging the separated blank B into and through the guiding device 56 to a position at the top of the stack of blanks contained within the magazine 18. For this purpose, the illustrated blanking machine 14 further includes a plurality of fluid motors or pneumatic cylinders indicated generally at 62, 62 and mounted on the upper portion of the movable punch assembly 40 for movement with the punch assembly and relative to the die assembly 38. Each fluid motor 62 has a stationary part 64 which is mounted in fixed position on the punch assembly and a movable part or plunger 66 which extends through a vertical bore in the punch assembly and which is movable between retracted and extended positions, the latter positions being indicated respectively by full and broken lines in FIG. 7. The pneumatic cylinders 62, 62 are arranged for simultaneous operation and connected through a manifold 67 and a control valve 68 to a source of air under pressure, show schematically and indicated by the numeral 70. The control valve 68 operates in timed relation to the movement of the die set 36 and is or may be operated by the moving punch assembly 40. The extending plungers 66, 66 engage the upper surface of a blank B as it is cut from the web W by the downwardly moving punch and to simultaneously exert a downward thrust at various points upon the surface of the cut blank to positively separate it from the die and urge it downwardly into the magazine formed by the depending guide rods 58, 58 and upstanding magazine rods 20, 20. The plungers are timed to operate once during each blanking cycle to accelerate the downward movement of each cut blank B as it separates from the die set 36 so that the blank is in a substantially horizontal orientation as it enters and travels within the magazine. This arrangement assures proper stacking of blanks B, B and prevents the falling blanks from interferring with the normal operation of the sensing device 60 which controls the operation of the machine 14. Since the blanking machine 14 is wholly independent of the receptacle forming machine 16 which it serves, the blanking machine may be moved away from the forming machine to allow servicing of either machine. Preparatory to operating the apparatus 10 the blanking machine 14 is moved into position relative to the receptacle forming machine 16 so that the vertically extending portion of the magazine 18 defined by the depending guide rods 58, 58 is properly vertically aligned with the portion of the magazine defined by the magazine rods 20, 20. An alignment device is preferably provided to assure proper alignment of the two machines and may, for example, comprise a pin carried by one of the machines which enters a complementary adjustable alignment slot on the other of the machines. Since the magazine 18 is preferably adjustable to accommodate blanks which may vary in size and or shape the alignment device is preferably also adjustable. Preferably, the blanking machine 14 is anchored in fixed position relative to the receptacle forming machine 16 to assure proper alignment retention between the guide rods and the magazine rods at all times during operation of the apparatus 12. Ocassionally, it may be necessary to remove defective blanks from the magazine to prevent these blanks from being fed into the forming machine, as for example, blanks printed out of registry or not sufficiently flat due to improper adjustment of the blanking machine. To facilitate blank removal the magazine may be provided with a gate. Referring now to FIG. 8, another apparatus embodying the invention is indicated generally at 12a. More specifically, in FIG. 8 there is shown a fragmentary plan view of a lower portion of a magazine 18a which comprises the apparatus 12a and which includes a movable gate. The magazine 18a includes a base member 72 fastened to a surface plate on a forming machine 16a. A plurality of adjustable magazine rods designated 20a, 20b and 20c are fastened to the base member 72 and extend upwardly from it generally as previously described. The magazine rods 20b and 20c are carried by adjustable members 74 and 76 and may be fastened in selected positions of adjustment to accommodate blanks, such as the blank B' shown in phanthom, which may vary in size and or shape. The rod 20a is also adjustable, but comprises a movable gate carried by an elongated member 78 fastened to the base member 72 for pivotal movement about a vertical axis indicated at 80. The magazine rod 20a is spring biased toward a closed or full line position in FIG. 8 by a spring 82 but may be pivoted about its axis 80 to an open or broken line position to allow convenient removal of blanks, such as the blank B', from the magazine 18a, as necessary.

Apparatus for making paper receptacles includes a magazine fed rotary turret receptacle forming machine having a magazine defined by a plurality of spaced apart and upwardly extending magazine rods. An independently operable blanking machine continuously supplies receptacle blanks to the forming machine and includes a die set and a plurality of spaced apart guide rods which depend from the die set and form an upward extension of the magazine.

FIELD OF THE INVENTION The present invention relates generally to motor vehicles and, more particularly, to a system and method for providing wireless communication between vehicles. BACKGROUND OF THE INVENTION Many currently available automobiles offer an ambient light detection system that controls the on/off setting of the headlights. In particular, if the detected ambient light is below a certain threshold, then the headlights are turned on. Otherwise, the headlights remain off. In the absence of such a detection system, the driver manually turns the headlights on or off, such as with a switch or knob on the dashboard of the automobile. In some situations where the headlights should be turned on, the driver may fail or forget to do so. For example, if the driver starts the vehicle in a very well lit parking lot or garage or is driving in a very well lit area of a city, the absence of the headlights may not be noticeable. A driver may similarly forget to turn on the headlights when there is precipitation, such as snow or rain. By failing to turn on the headlights at a time when they should be on, the driver may not have optimum visibility. In particular, without the headlights on, other drivers may be unable to discern the presence of the vehicle, which can result in an accident and injuries to nearby drivers, passengers, and pedestrians. SUMMARY OF THE INVENTION Accordingly, it would be desirable to have a system for turning headlights on in certain situations. According to an aspect of the invention, a vehicle and a method for controlling headlight status in a first vehicle includes receiving status information from at least one vehicle other than the first vehicle located in a communication area surrounding the first vehicle, the status information including a headlight status of the at least one vehicle. A headlight status of the first vehicle is determined, and an action is initiated in the first vehicle based on the determined headlight status of the first vehicle and the received vehicle status of the at least one other vehicle. Further features, aspects and advantages of the present invention will become apparent from the detailed description of preferred embodiments that follows, when considered together with the accompanying figures of drawing. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a headlight control system consistent with the present invention. FIG. 2 is a flow diagram of a headlight control process consistent with the present invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Wireless communication between vehicles and to and from other structures and devices can provide for a significant increase in the amount and types of information available to vehicles and drivers, as well as the potential for a variety of new applications and systems ranging from crash avoidance to Internet entertainment systems. Systems such as telephony and Dedicated Short Range Communications (DSRC) are capable of supporting wireless communication between vehicles. For example, using a DSRC system, each vehicle is capable of generating and broadcasting a “Common Message Set” (CMS), which provides each vehicle's relevant kinematical and location information such as GPS/vehicle position, velocity, vehicular dimensions, and other related information. In addition, status information, such as headlight status (e.g., On, High Beams, Parking Lamps, Off) can also be provided. The DSRC system can broadcast messages between vehicles using a frequency between about 5 and 6 GHz. The CMS message can be broadcast as the most frequent message on the control or center channel of the DSRC band, although other messages can also be broadcast over this channel. Unicast messages (i.e., single-sender speaking directly to a single-receiver for mono-to-mono exchanges) can be directed to an alternate channel, and several channels can be designated as either urgent/safety-related channels or service-providing, non-urgent channels. This type of implementation permits OEM's to send messages only to vehicles of the same manufacturer or make, and create exchanges of information between them outside the central channel of communication. In view of this ability for information to be communicated between vehicles, it is possible to configure a system that enables a vehicle to modify its operation or settings and to notify a driver of settings, situations or conditions relevant to operating a vehicle. For example, it is possible to use information about the headlight status of vehicles to adjust the headlight setting of another vehicle. FIG. 1 is a block diagram of a headlight control system consistent with the present invention. As shown in FIG. 1 , there is a vehicle 1 and a vehicle 2 . The vehicle 1 includes an antenna controller 11 , a GPS antenna 12 , a DSRC antenna 13 , a DSRC processor 14 , a light sensor 15 , headlights 16 , and an interface 17 . The vehicle 2 has similar elements including an antenna controller 21 , a GPS antenna 22 , a DSRC antenna 23 , a DSRC processor 24 , and headlights 26 . Although the vehicle 2 is not shown as including a light sensor or an interface, the vehicle 2 can also include these elements. In addition, although only the two vehicles 1 and 2 are shown, it should be understood that the headlight control system is applicable to more than two vehicles. The antenna controller 11 controls the functioning of both the GPS antenna 12 and the DSRC antenna 13 . The GPS antenna 12 is configured to receive information regarding the location of the vehicle 1 . The DSRC antenna 13 is configured to receive information from other vehicles and devices and to transmit information from the vehicle 1 . The received information and the transmitted information can include, for example, kinematical and location information such as GPS/vehicle position, velocity, and vehicular dimensions, as well as status information, such as headlight status. The information can be transmitted and received in a predetermined message format such as the CMS. The predetermined message format may be unique to each manufacturer or be a common format for all vehicles. Even in the common format, the predetermined message may include a section or component identifying the manufacturer, which can enable a vehicle to send a message exclusively to other vehicles of the same manufacturer or make. To transmit a message or other information, the DSRC antenna 13 receives control instructions from the antenna controller 11 and transmits the message in accordance with the control instructions. Messages or other information received by the GPS antenna 12 and the DSRC antenna 13 are provided to the antenna controller 11 . In response to the received message, the antenna controller 11 can provide new control instructions to the GPS antenna 12 and the DSRC antenna 13 based on the content of the received message. In addition, the antenna controller provides the received message to the DSRC processor 14 . The DSRC processor 14 is configured to process messages provided from the antenna controller 11 and to generate messages to be transmitted by the DSRC antenna 13 . The DSRC processor 14 is also configured to control the setting of the headlights 16 and to provide signals and messages to the interface 17 . The DSRC processor 14 can include a processing unit, such as CPU or microprocessor, a non-volatile storage medium, such as an NVRAM or ROM, and a volatile storage medium, such as RAM. The non-volatile storage preferably includes instructions executed by the processing unit to perform the message processing and generation and other control functions, as will be described in more detail herein. The light sensor 15 is configured to detect ambient light external to the vehicle 1 . The light sensor 15 converts the detected ambient light into an electrical signal and provides the signal to the DSRC processor 14 and to the headlights 15 . The DSRC processor 14 uses the signal from the light sensor 15 as part of its message processing and generation and its control functions. The headlights 16 are lamps at the front of the vehicle 1 that illuminate the environment ahead of the vehicle 1 . The interface 17 receives messages or signals from the DSRC 14 and provides information to the driver based on the received messages or signals. The information provided by the interface 17 to the driver can include, for example, location, velocity, mileage, etc. The interface 17 can also provide information to the user based on messages provided from other vehicles, such as velocity and location. The data provided by the interface 17 to the driver, for example, can be communicated through a visual display showing text, graphical, and/or analog data. The interface 17 can also provide information to the driver audibly through a recorded or computerized voice. In addition to receiving data from the DSRC processor, the interface 17 can also provide data to the DSRC processor 14 , such as velocity and other operational conditions of the vehicle 1 that can be detected by various sensors implemented in the vehicle 1 . The components of the vehicle 2 are implemented and operate in the same manner as the corresponding components of the vehicle 1 . In particular, the antenna controller 21 , the GPS antenna 22 , the DSRC antenna 23 , the DSRC processor 24 , and the headlights 26 are implemented and operate in the same manner as the antenna controller 11 , the GPS antenna 12 , the DSRC antenna 13 , the DSRC processor 14 , and the headlights 16 , respectively. FIG. 2 is a flow diagram of a headlight control process consistent with the present invention. In the following description, the process is described in conjunction with the vehicles 1 and 2 of FIG. 1 . More specifically, the process is described from the standpoint of a message being transmitted from vehicle 2 and received by vehicle 1 , which responds to the received message. It is also assumed that the headlights 16 of the vehicle 1 are off. It should be understood, however, that the process is applicable to any vehicle capable of communicating wirelessly with other vehicles or transmitters. As shown in FIG. 2 , in the headlight control process, the vehicle 2 first prepares a CMS message (step 202 ). As described above, the CMS message can include kinematical and location information such as GPS/vehicle position, velocity, and vehicular dimensions, as well as status information, such as headlight status. With reference to FIG. 1 , the DSRC processor 24 of the vehicle 2 collects the information for forming the CMS message. The information collected includes, for example, a status of the headlights 26 , velocity data from a velocity sensor, location information received by the GPS antenna 22 , and other relevant information about the operation and settings of the vehicle 2 . The collected information is formatted into the CMS message format. Although the CMS message format is preferable, other message formats, either common to all automobile manufacturers or unique to particular manufacturers can be used instead. Further, in addition to the collected information, the message is formatted to include a unique identifier for the vehicle 2 so that other vehicles receiving the message can distinguish the origin of the message from messages received from other vehicles. The CMS message can be prepared at predetermined time intervals, such as every minute. The vehicle 2 broadcasts the CMS message (step 204 ). To broadcast the message, the DSRC processor 24 provides the CMS message to the antenna controller 21 , which controls the DSRC antenna 23 to broadcast the message. The CMS message is broadcast at least to vehicles in the vicinity of the vehicle 2 . Additionally, the CMS message can be broadcast to other structures, such as antenna towers or other communication devices, which can forward or broadcast the CMS message to more vehicles that may be outside of the broadcast range of the DSRC antenna 23 . The vehicles in the broadcast range of the DSRC antenna 23 , including the vehicle 1 , receive the CMS message from the vehicle 2 (step 206 ). At vehicle 1 , the CMS message is received by the DSRC antenna 13 and provided to the antenna controller 11 , which transfers the message to the DSRC processor 14 . The DSRC processor 14 is configured to understand the format and content of the received CMS message and to process it accordingly. The received CMS message includes an identifier of the vehicle transmitting the CMS message, in this case vehicle 2 . The identifier enables the DSRC processor 14 to distinguish which vehicle sent the CMS message and to collect the most up-to-date information about each vehicle transmitting CMS messages to the vehicle 1 . The information from the CMS messages can be stored in a memory coupled to or implemented in the DSRC processor 14 . When a new CMS message is received, the DSRC processor 14 can update the information stored in the memory or, if it is the first CMS message received from a vehicle, store all of the information in the memory. The information can be stored, for example, in the form of a spreadsheet or table with a line for each vehicle, each line having the identifier of the vehicle and some or all of the information in the CMS message. Accordingly, for each vehicle sending a CMS message to the vehicle 1 , the DSRC processor 14 may store each vehicle's location, speed, dimensions and other status settings, such as headlights. In response to the received CMS message, the DSRC processor 14 determines if the CMS message indicates that the headlights 26 of the vehicle 2 are on (step 208 ). If they are not on, then the DSRC processor 14 can check if information is already stored for the vehicle 2 and update the status of the headlights. If the headlights 26 of the vehicle 2 are on, however, the DSRC processor 14 can increment a headlight counter, which keeps track of the number of vehicles that have their headlights on. The DSRC processor 14 can also keep a total counter, which keeps track of the number of vehicles that are transmitting CMS messages to the vehicle 1 . Both the headlight counter and the total counter can be updated or adjusted to reflect up-to-date information and to account for vehicles no longer transmitting CMS messages to the vehicle 1 . For example, if a vehicle has not transmitted a CMS message within a predetermined period, such as five minutes, then the total counter is reduced by one to eliminate that vehicle from the total count, and if that vehicle's headlights were on, then the headlight counter is also reduced by one. Similarly, if a vehicle's headlight status changes from on to off, then the headlight counter is reduced by one. If the DSRC processor 14 determines that the headlights 26 of the vehicle 2 are on from the received CMS message, then it checks to determine if a threshold is satisfied (step 210 ). The threshold is used as a test to determine whether or not the headlights 16 of the vehicle 1 should be turned on. The threshold is used in conjunction with the headlight counter or the combination of the headlight counter and the total counter. For example, the threshold could be a predetermined number of vehicles having their headlights on, such as three. Thus, if the headlight counter is equal to or exceeds the predetermined number, then the threshold is satisfied. Alternatively, the threshold could be a predetermined percentage of vehicles having their headlights on, such as 75%. To compare to the threshold, a percentage is calculated by dividing the headlight counter by the total counter (and multiplying by 100). The predetermined percentage may also have a minimum total counter value before the threshold is applied, such as four vehicles sending messages. If the threshold is not satisfied, then no action is taken. If the threshold is satisfied, then the output of the light sensor 15 is compared to a light threshold (step 212 ). The light sensor 15 generates an electrical signal indicative of the amount of ambient light outside of the vehicle. If the amplitude of the electrical signal is proportional to the amount of light detected, then the amplitude is greater when it is light out and lower when it is dark out. In this case, if the amplitude is less than or equal to the light threshold, then it is indicative that it is sufficiently dark to turn on the headlights 16 . It is also possible for the amplitude to be inversely proportional, in which case a lower amplitude corresponds to it being light and vise versa. If inversely proportional, then if the amplitude is greater than or equal to the light threshold, it is indicative that it is sufficiently dark to turn on the headlights 16 . If the light threshold is not satisfied, then no action is taken. If the light threshold is satisfied, however, then the DSRC processor 14 enacts a response (step 214 ). There are a number of different responses that can be enacted. For example, one response is for the DSRC processor 14 to turn on the headlights 16 automatically. Alternatively, the DSRC processor 14 can provide an alert to the driver via the interface 17 that the headlights 16 should be turned on. The alert can be made visually by providing a message or signal on a display of the vehicle 1 , such as on the dashboard. The alert can also be made audibly, such as through a voice announcement to the interior of the vehicle 1 . Another possible response is to cause the parking lamps to periodically flash, which serves as a warning to other drivers in the area, as well as an alert to the driver of the vehicle 1 that the headlights 16 should be turned on. In general, the response should automatically turn on the headlights 16 , warn the driver to turn them on, and/or warn other drivers that the headlights 16 of the vehicle 1 are off. In accordance with the present invention, the headlight status of other vehicles is used to control a vehicle's headlight setting and/or provide a warning. The headlight statuses are communicated to the vehicle through a wireless communication channel. Based on the received headlight statuses, the vehicle can determine whether or not its headlights should be on. For example, if a predetermined number or percentage of other vehicles have their headlights on, then the vehicle can automatically turn its headlights on or advise the driver to do so. Further, before enacting a response based on the received headlight statuses, a light sensor can be used as an additional test to ensure that the ambient light is sufficiently low such that turning on the headlights is appropriate. The use of the light sensor as an additional test is not required. Rather, the response can be enacted based on the received headlight statuses only. The foregoing description of preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments (which can be practiced separately or in combination) were chosen and described in order to explain the principles of the invention and as practical applications to enable one skilled in the art to utilize the invention in various embodiments and with various modifications suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

A vehicle and a method for controlling headlight status in a first vehicle includes receiving status information from at least one vehicle other than the first vehicle located in a communication area surrounding the first vehicle, the status information including a headlight status of the at least one other vehicle. A headlight status of the first vehicle is determined, and an action is initiated in the first vehicle based on the determined headlight status of the first vehicle and the received vehicle status of the at least one vehicle.

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to fermented food products containing probiotic strains, and their preparation process. 2. Description of the Related Art The bifidobacteria belong to the dominant anaerobic flora in the colon. The main species present in the human colon are Bifidobacterium adolescentis, Bifidobacterium bifidum, Bifidobacterium longum ssp infantis, Bifidobocterium breve, Bifidobacterium longum. The bifidobacteria are probiotic bacteria of choice. Bacteria of the genus Bifidobacterium are used in numerous products currently on the market and are often added to dairy products already comprising the standard bacteria in yogurt ( Streptococcus thermophilus and Lactobacillus bulgaricus ). The consumption of bifidobacteria is recognized as being beneficial in the process of re-establishing the normal bifidobacteria population in individuals having undergone antibiotics therapy. This consumption also seems to make it possible to reduce constipation, prevent diarrhoea and reduce the symptoms of lactose intolerance. Probiotics are live bacteria. The use of these live bacteria in the manufacture of food products such as dairy products is tricky in particular with regard to the problem of survival of these bacteria in the product. 80% of the products currently on the market which contain bifidobacteria do not satisfy the criteria making it possible to maintain that they significantly improve the intestinal transit of the individuals consuming them. A daily intake of at least 10 8 to 10 9 viable cells has been recommended as the minimum dose making it possible to have a therapeutic effect (Silva A. M., Barbosa F. H., Duarte R., Vieira L. Q., Arantes R. M., Nicoli J. R., Effect of Bifidobacterium longum ingestion on experimental salmonellosis in mice, J. Appl. Microbiol. 97 (2004) 29-37). The required dose can be dependent on the probiotic strain used. In the case of the production of a bioactive food product containing bifidobacteria the problem therefore arises of obtaining a sufficient population of these bacteria in the product and maintaining it during the “life” of the product without resorting to technical solutions capable of altering the organoleptic qualities of the product. The problem of the numerical size of the population of probiotic strains in a fermented dairy product is a known problem (see in particular D. Roy, Technological aspects related to the use of bifidobacteria in dairy products, Lait 85 (2005) 39-56, INRA, EDP Sciences). Several reasons for this problem have been suggested, including the reduction in the population during storage, the disturbed growth of these bacteria starting from a certain pH or quite simply the poor ability of these bifidobacteria to grow, in particular in milk. It is known that the fructo-oligosaccharides, certain starches, certain sugars, glycerol and certain yeast extracts have significant bifidogenic effects. On the other hand oxygen is toxic to certain probiotic strains. The use of cysteine or ascorbate as an oxygen scavenger has therefore been described (A review of oxygen toxicity in probiotic yogurts: influence on the survival of probiotic bacteria and protective techniques. Talwalkar & Kailasapathy; Comprehensive Reviews in Food Science and Food Safety, 3 (3) 117-124; 2004), without it however having been demonstrated that the use of these substances makes it possible to obtain and maintain populations of bifidobacteria at the desired levels during storage. Moreover, the potentially negative effect of the cysteine on the final properties of a yogurt has been noted. Generally, the fermented food products having properties of relative maintenance of the populations of bifidobacteria during the preservation of said products, and which are described in the literature, do not generally have acceptable organoleptic properties, due to the fact in particular that substances such as yeast extract are present in a high concentration in the products. SUMMARY OF THE INVENTION The main purpose of the invention is to provide fermented food products having acceptable organoleptic properties and containing a high concentration of bifidobacteria at the end of the fermentation period and throughout the preservation period of said fermented food products. The main purpose of the invention is to provide fermented food products containing bifidobacteria in a good physiological state and having a significant survival rate during the period of preservation of said fermented food products, in particular up to the use-by date of the products. Another purpose of the invention is to provide preparation processes which are simple to implement, making it possible to obtain the above products. Another purpose of the invention is to promote the growth of the bifidobacteria in relation to the standard symbioses present in yogurts, these symbioses being constituted in a standard fashion by one or more strains of Streptococcus thermophilus and of Lactobacillus bulgaricus. The purposes of the invention are achieved thanks to the surprising finding made by the inventors that the incorporation of sulphur-containing amino acids in the starting substance during the preparation of fermented food products containing bifidobacteria, in a small enough quantity not to alter the organoleptic properties of the products, makes it possible to obtain rapidly, after fermentation of the populations, at least 5.10 7 or even 10 8 bifidobacteria per gram of product, and increased survival of the bifidobacteria up to the use-by date of the products, without necessarily modifying the growth of the other bacterial strains. The invention relates to the use of at least one sulphur-containing amino acid, at a total concentration of approximately 5 to approximately 75 mg/l, in particular approximately 5 to approximately 50 mg/l, in particular approximately 5 to approximately 30 mg/l, in particular approximately 5 to approximately 20 mg/l in the free form, for the implementation of a process for the preparation of a fermented food product using ferments containing bifidobacteria, which fermented food product has acceptable organoleptic properties, contains more than approximately 5.10 7 , in particular more than approximately 10 8 bifidobacteria per gram of fermented food product for a preservation period of at least 30 days, in particular at least 35 days and does not contain more than 0.5% of yeast extract or yeast autolysate. By “sulphur-containing amino acid” is meant cysteine (L-cysteine) or methionine as well as their derivatives, optionally in the form of a salt. In particular there can be used according to the invention monohydrated L-cysteine hydrochloride (monohydrated (R)-2-amino-mercaptopropionic acid monohydrochloride) or L-methionine ((S)-2-amino-4-methylthio-butyric acid), of the respective formulae: By “in the free form” is meant amino acids which are not bound to other amino acids by a peptide bond within peptides, polypeptides or proteins. Preferably, the sulphur-containing amino acids according to the invention are used in reduced form, i.e. the sulphhydryl group —SH is reduced. This preferred form of the sulphur-containing amino acids therefore excludes in particular cystine, the oxidized form of cysteine involving the combination of two cysteines via a disulphide bridge. The bifidobacteria being substantially without proteolytic activity, it is advantageous to use the abovementioned amino acids in the free form so that they can be directly assimilated by the bifidobacteria. The sulphur-containing amino acid or acids used according to the invention are advantageously filtered beforehand and/or autoclaved (or pasteurized, i.e. treated at a temperature above 50° C.) and/or irradiated, in order to take account of the constraints of use as regards microbiological contamination, i.e. so that they are substantially without microbial contaminants. If the sulphur-containing amino acids are used at a concentration above 75 mg/l, a degradation of the organoleptic properties of the food product is noted. If the sulphur-containing amino acids are used at a concentration below 5 mg/l, the population of bifidobacteria greater than 5.10 7 or 10 8 CFU per gram of product cannot generally be maintained during the preservation period of the product. It should be noted that the concentration of sulphur-containing amino acids used according to the invention relates to the sulphur-containing amino acid or acids especially added during the preparation of the products. This concentration does not take account of the possible bacterial production of sulphur-containing amino acids during the preparation nor even of the quantity of sulphur-containing amino acids in the free form which are naturally present in the starting substance which serves to prepare the food product (for example in milk) or in the adjuvants which can be used during the preparation. The typical concentration of sulphur-containing amino acids present in milk is 100 to 1300 mg/l including approximately 260 mg/l cysteine and 1020 mg/l methionine (Handbook of Milk composition, 1995, Academic Press). It should be noted that the vast majority of these sulphur-containing amino acids present in milk is in the bound form in peptide or protein chains. By “ferments” is meant a set of bacteria, in particular bacteria intended for fermentation and/or bacteria with probiotic value. By “acceptable organoleptic properties” is meant in particular the absence of an undesirable sulphur-type taste, as determined by a standard sensory analysis test, which can correspond to the protocol described hereafter. The sensory mechanism starts with the generation of a stimulus following the consumption of a product. This stimulus allows a perception which is dependent on genetic and physiological factors in the individual consumer. This perception is then verbalized (a list of words is proposed to the consumer) then quantified (use of ranges). The consumer then gives an overall assessment of the product that he has consumed (this assessment is influenced by his culture, his experiences) and says whether or not he would be prepared to buy this product (data such as cost, communication about this product can then be provided). Sensory analysis is a science based on perception (physiological and psychological) involving the five senses (taste, smell, sight, hearing, touch) and using very rigorous protocols. The consumers constituting the panel who carry out the sensory analyses are selected for their sensory abilities, their abilities in terms of verbalization, their abilities in terms of use of ranges for an assessment and their abilities to work in a group (in order to obtain a consensus). It is absolutely necessary to verify that the assessments of the panel members are repeatable, reproducible, with a homogeneity in terms of discrimination and in terms of classification. Tests making it possible to verify these pre-requisites are repeated several times. The choice of products is made according to three main criteria: according to the age of the product (products of the same age are chosen), these products must be representatives in the case of a standard assessment and the products are homogeneous (few differences between them). These products are presented anonymously and in coded form, in a certain order and homogeneously (same temperature etc.). The environmental conditions of the sensory analysis are important: the conditioned air, the lighting, the sound environment, the decoration (neutral if possible) and the odour of the room in which the analysis is carried out should be standardized. The panel members are separated by cubicles. They should not smoke, consume coffee or menthol in the hours preceding the analysis session. They should also not wear perfume or make-up. At the end of this analysis, a product is to be considered as having “acceptable organoleptic properties” if the panel members have not detected an undesired sulphur-type taste in this product. The preservation or storage period of the fermented food product is the period which immediately follows the end of the process of preparation of the fermented food product and its packaging. During this preservation period the fermented food product is usually preserved at a temperature comprised between approximately 4 and approximately 10° C. The abovementioned fermented food product contains more than 5.10 7 , in particular more than 10 8 bifidobacteria per gram of fermented food product in particular for a preservation period of at least 40 days. More particularly the above-mentioned fermented food product contains more than 5.10 7 , in particular more than 10 8 bifidobacteria per gram of fermented food product up to the use-by date of the product. The use-by dates depend on the legal preservation periods fixed by current legislation, which can typically vary from 15 to 50 days from the date of production. By way of example, the legal preservation period is generally 30 days for fresh dairy products. A population of bifidobacteria which is greater than or equal to 10 8 CFU/g at the use-by date of product preserved between 4 and 10° C. can be considered a sufficient population of bifidobacteria given the medical recommendations relating to the provision of bifidobacteria in food. By “does not contain more than 0.5% of yeast extract or yeast autolysate”, is meant in particular that the abovementioned fermented food product does not contain more than 0.5% of yeast extract or yeast autolysate at the end of its preparation process and/or that the abovementioned fermented food product does not contain more than 0.5% of yeast extract or yeast autolysate for the preservation period of at least 30 days, in particular at least 35 days, in particular at least 40 days or up to the use-by date of the abovementioned fermented food product. Moreover, the abovementioned fermented food product no longer contains a quantity greater than 0.5% of yeast extract or yeast autolysate during the process for the preparation of the product, and in particular at the time of the inoculation of the bacteria and throughout the fermentation. By “yeast extract” and “yeast autolysate” is meant concentrates of soluble compounds of yeast cells. In this regard reference may be made in particular to the article “Yeast extracts: production, properties and components” by Rolf Sommer (9 th International Symposium on Yeasts), from which the information below is extracted. Yeast extracts are mainly produced by autolysis, i.e. cell hydrolysis is carried out without the addition of other enzymes. The yeast extract or yeast autolysate are used mainly in the fermentation industry and in the agri-food industry. The main raw material used in order to produce the yeast extract is constituted by yeasts with a high concentration of proteins (strains of Saccharomyces cerevisiae ) cultured on media based on molasses or is constituted by yeasts from debittered beer (strains of Saccharomyces cerevisiae or Saccharomyces uvarum ). Other raw materials used are yeasts such as Kluyveromyces fragilis (fermented on lactoserum) or Candida utilis (cultured on carbohydrate-rich waste originating from of the timber industry or on ethanol) or also special strains of baker's yeasts, in order to produce yeast extract containing 5′-nucleotides. Autolysis is the dissociation process most frequently used in the production of yeast extract. During this process, the yeasts are degraded by their own endogenous enzymes. The autolysis process can be initiated by an osmotic shock or controlled temperature, causing cell death without inactivating the endogenous enzymes (in particular the proteases). A controlled pH, the temperature and the duration of the autolysis are decisive factors in a standardized autolysis process. By adding salts or enzymes (for example proteases or mixtures of proteases and peptidases) relative to the “standard” autolysis, the protein degradation of the yeast cells can be controlled. Besides autolysis, the yeast extract can be produced by thermolysis (for example by boiling the yeasts in water at 100° C.), plasmolysis (treatment with strong saline solutions at a temperature below 100° C.) and mechanical degradation (high-pressure homogenization or grinding). Then the soluble compounds are separated from the insoluble cell walls and concentrated with an evaporator with stirring or falling film evaporator, followed by optional stages of filtration, concentration under partial vacuum and rapid sterilization. Three types of yeast extract exist: liquid yeast extract (dried matter: 50 to 65%); viscous paste-type yeast extract (dried matter: 70 to 80%); dry yeast extract powder. Taking the example of a standard yeast extract powder used in the fermentation industry, the composition is the following: Protein content: 73-75% Sodium: less than 0.5% Polysaccharides: less than 5% Oligosacharides: less than 1% Lipids: less than 0.5% The protein content is typically distributed as follows: Free amino acids: 35-40% Di, tri and tetrapeptides (MW < 600 Da): 10-15% Oligopeptides (MW of 2000-3000 Da): 40-45% Oligopeptides (MW of 3000-100000 Da): 2-5% The typical cysteine content is 0.45%, and the typical methionine content is 1.12% (1.08% in the free form). The invention relates to the use of at least one sulphur-containing amino acid, at a total concentration of approximately 5 to approximately 30 mg/l, in particular approximately 10 to approximately 15 mg/l, in particular approximately 12 to approximately 15 mg/l, and in particular 12.5 mg/l, in the free form, for the implementation of a process for the preparation of a fermented food product using ferments containing bifidobacteria, which fermented food product has acceptable organoleptic properties, contains more than approximately 5.10 7 , in particular more than approximately 10 8 bifidobacteria per gram of fermented food product for a preservation period of at least 30 days, in particular at least 35 days and does not contain more than 0.5% yeast extract or yeast autolysate. Moreover, the invention also relates to a fermented food product, having acceptable organoleptic properties, containing ferments comprising more than approximately 5.10 7 , in particular more than approximately 10 8 bifidobacteria per gram of fermented food product for a preservation period of at least 30 days, in particular at least 35 days and having a total concentration of sulphur-containing amino acids in the free form of approximately 5 to approximately 50 mg/l, in particular approximately 5 to approximately 30 mg/l, in particular approximately 5 to approximately 20 mg/l, in particular approximately 10 to approximately 15 mg/l, in particular approximately 12 to approximately 15 mg/l, and in particular 12.5 mg/l. More particularly, said fermented food product contains ferments comprising more than approximately 5.10 7 , in particular more than approximately 10 8 bifidobacteria per gram of fermented food product for a preservation period of at least 40 days or up to the use-by date of the fermented food product. Advantageously, the fermented food product as defined above is such that the ratio of the number of bifidobacteria contained in the fermented food product at the end of the preservation period to the number of bifidobacteria contained in the fermented food product at the start of the preservation period of at least 30 days, in particular at least 35 days, is approximately 0.2 to approximately 0.8, in particular approximately 0.3 to approximately 0.7, in particular approximately 0.4 to approximately 0.5. In other words the survival rate of the bifidobacteria contained in the fermented food product between the start of the preservation period (i.e. the end of the preparation process) and the end of the preservation period is comprised between 20 and 80%, in particular between 30 and 70%, and in particular between 40 and 50%. Said preservation period is at least 30 days, in particular at least 35 days, but more particularly at least 40 days or extends at least up to the use-by date of the fermented food product. The invention also relates to a fermented food product preserved for a preservation period of at least 30 days, in particular at least 35 days, at a temperature of approximately 4 to approximately 10° C., having acceptable organoleptic properties and containing ferments comprising more than approximately 5.10 7 , in particular more than approximately 10 8 bifidobacteria per gram of fermented food product. More particularly the invention relates to a fermented food product preserved for a preservation period of at least 30 days, in particular at least 35 days, in particular at least 40 days, at a temperature of less than 12° C. or less than 10° C., having acceptable organoleptic properties and containing ferments comprising more than approximately 5.10 7 , in particular more than approximately 10 8 bifidobacteria per gram of fermented food product. Preferably, the invention relates to a fermented food product as defined above containing approximately 5 to approximately 50 mg/l, in particular approximately 5 to approximately 30 mg/l, in particular approximately 5 to approximately 20 mg/l, in particular approximately 10 to approximately 15 mg/l, in particular approximately 12 to approximately 15 mg/l, and in particular 12.5 mg/l, of sulphur-containing amino acids and in particular approximately 5 to approximately 50 mg/l, in particular approximately 5 to approximately 30 mg/l, in particular approximately 5 to approximately 20 mg/l, in particular approximately 10 to approximately 15 mg/l, in particular approximately 12 to approximately 15 mg/l, and in particular 12.5 mg/l of cysteine and/or approximately 5 to approximately 30 mg/l, in particular approximately 5 to approximately 15 mg/l, of methionine. In order to determine the cysteine, it is possible to use an amino acid analyzer such as the L-8800 High Speed Amino Acid Analyzer (Hitachi High Technologies). This analyzer combines ion-exchange chromatography with calorimetric detection at two wavelengths (570 and 440 nm) after reaction with ninhydrin. It is also possible to use gas chromatography coupled with mass spectrometry or high-performance liquid chromatography coupled with fluorimetric detection. The more particular use of cysteine is advantageous as it gives rise experimentally to a better bifidogenic effect than methionine. The more particular use of methionine is advantageous as its cost is lower than that of the use of the cysteine. Advantageously, said fermented food product contains less than approximately 0.5% (w/w) of substances containing more than approximately 1.7% of sulphur-containing free amino acids. More particularly said fermented food product contains less than approximately 0.5% (w/w) of yeast extract and/or yeast autolysate and/or milk, plant or soya protein hydrolysate. The possible presence of yeast extract or yeast autolysate type substances is easily detectable in the product by known methods. In particular, the glucans or the mannans provided by these substances are detectable. For example, the glucans and mannans being fibres, it is possible to use the total dietary fibre determination method, recommended by the AFSSA [French Agency for Food Safety] (method AOAC 985.29). The addition of yeast extract or a similar substance must also result in a complete modification of the content of all of the 20 amino acids in the product, as well as in a modification of the concentration of vitamins and minerals, relative to the normal composition of the product (for the example of milk, reference may in particular be made to the Handbook of milk composition, 1995, Academic Press). According to a preferred embodiment, the bifidobacteria contained in the fermented food product as defined above are of the type Bifidobacterium animalis , in particular Bifidobacterium animalis animalis and/or Bidifobacterium animalis lactis , and/or Bifidobacterium breve and/or Bifidobacterium longum and/or Bifidobacterium infantis and/or Bifidobacterium bifidum. Advantageously, the fermented food product as defined above is based on plant juice and in particular fruit juice or vegetable juice such as soya juice, or on a dairy product, and in particular on cow's milk and/or on goat's milk. Said fermented food product can also be based on sheep's milk, camel's milk or mare's milk. By plant juice is meant a juice produced from plant extracts, in particular soya, tonyu, oat, wheat, maize etc. Examples of vegetable juice are: tomato juice, beet juice, carrot juice etc. Examples of fruit juice are: apple, orange, strawberry, peach, apricot, plum, raspberry, blackberry, gooseberry, pineapple, lemon, citrus fruit, grapefruit, banana, kiwi fruit, pear, cherry, passion fruit, mango, exotic fruit juice, multifruit juice etc. According to a preferred embodiment, the ferments of the fermented food product as defined above contain lactic bacteria, in particular one or more bacteria of the genus Lactobacillus spp. and in particular Lactobacillus delbrueckii bulgaricus and/or Lactobacillus casei and/or Lactobacillus reuteri and/or Lactobacillus acidophilus and/or Lactobacillus helveticus and/or Lactobacillus plantarum , and/or bacteria of the type Lactococcus cremoris and/or Streptococcus thermophilus and/or Lactococcus lactis and/or one or more bacteria of the genus Leuconostoc. Advantageously, the fermented food product as defined above is such that the proportion of bifidobacteria in the ferments is approximately 20 to approximately 80%, in particular approximately 30 to approximately 70%, in particular approximately 40 to approximately 60%, and in particular approximately 50%. By “proportion of bifidobacteria in the ferments” is meant the proportion of bifidobacteria relative to the total number of bacteria included in the fermented food product, i.e. relative to all of the bifidobacteria and other bacteria, in particular the bacteria Lactococcus, Lactobacillus, Streptococcus etc. The good numerical balance between the bifidobacteria and the other bacterial strains in the fermented food product at the end of the preparation process, and the substantial maintenance of this balance throughout the preservation period, are essential guarantees of the quality of the food product. A proportion of 50% bifidobacteria constitutes a good compromise between the problem of cost (the bifidobacteria are expensive) and the problem of obtaining a correct population of bifidobacteria. According to a preferred embodiment, the fermented food product as defined above is presented in the form of a stirred fermented food product or a fermented food product for drinking or a firm fermented food product or an infant fermented food product. By “stirred [ . . . ] product” is meant a product, in particular a milk, seeded, fermented, mechanically stirred then packaged. The fermentation of such a product is carried out not in a pot but in bulk, in tanks. The curd is stirred then cooled down before being packed in pots, which are stored under refrigeration. By curd is meant a coagulate of proteins in particular of milk. By “[ . . . ] product for drinking” is meant a product in substantially liquid form. A product for drinking is a product which is such that, after the mechanical stirring stage, the product is beaten in the tanks before being packaged. By “firm [ . . . ] product” is meant a product (in particular a milk) seeded and directly packaged in pots where it ferments. After the seeding, the product is packaged in pots. These pots are generally placed in an oven for 3 hours. The bacteria reproduce and consume the lactose which is then partially converted to lactic acid which modifies the structure of the proteins, forming what is known as a “lactic gel”. Then, the products are placed in a ventilated cooler or cooling tunnel and stored at approximately 2-4° C. By “infant [ . . . ] product” is meant a product suited to an infant's needs, with a low protein and fat content. Said fermented food product can in particular be a yogurt or a firm, stirred or drinking yogurt or a bar containing a dairy substance, kefir, a biscuit with a dairy filling, a water containing probiotics etc Moreover the invention also relates to a process for the preparation of a fermented food product from a starting substance, comprising a stage of seeding a starting substance, optionally pasteurized, by inoculation with seeding ferments containing bifidobacteria, in order to obtain a seeded substance, a stage of fermentation of the seeded substance obtained in the preceding stage in order to obtain a fermented substance, a stage of incorporation of at least one sulphur-containing amino acid in the free form at a concentration of approximately 5 to approximately 75 mg/l in particular approximately 5 to approximately 50 mg/l, in particular approximately 5 to approximately 30 mg/l, in particular approximately 5 to approximately 20 mg/l, in particular approximately 10 to approximately 15 mg/l, in particular approximately 12 to approximately 15 mg/l, and in particular 12.5 mg/l, this stage of incorporation being able to occur either before the seeding stage, or substantially simultaneously with the seeding stage, or after the seeding stage and before the fermentation stage, providing that the fermented food product does not contain more than 0.5% (w/w) of yeast extract and/or yeast autolysate. By “fermentation” is meant a biochemical reaction which involves releasing energy from an organic substrate, under the action of micro-organisms. It is a conversion process of a raw material by the micro-organisms, this conversion then producing biomass and metabolites. In particular, lactic fermentation is an anaerobic process of the consumption of lactose by the bacteria in the ferments, which causes the formation of lactic acid and a lowering of the pH. The invention follows from the surprising finding made by the inventors that the incorporation of sulphur-containing amino acids within the abovementioned ranges, in the absence of yeast extract and/or yeast autolysate or in the presence of a low concentration of the latter, makes it possible to improve the resistance of the bifidobacteria and their ability to survive. The bidifobacteria contained in the fermented food product at the end of the preparation process of the invention are in a better physiological state than if the stage of incorporation of sulphur-containing amino acids were omitted, which allows a larger number of these bifidobacteria to survive during the preservation of the fermented food product which follows. Cysteine and/or methionine therefore have a specific bifidogenic effect. On the other hand the use of yeast extract and/or yeast autolysate, in particular at concentrations greater than 0.5% (w/w), has a tendency to stimulate all of the bacteria contained in the fermented food product, which can lead to an imbalance in the bacterial symbiosis to the detriment of the bifidobacteria, and in favour in particular, if they are present, of the lactic bacteria. The consequences of this imbalance are a modification of the pH, a production of acetic acid and/or of H 2 O 2 , all events which are detrimental to the quality of the product. Moreover it should be noted that from a concentration of sulphur-containing amino acids greater than 30 mg/l, in particular from a concentration of sulphur-containing amino acids greater than 50 mg/l, and more particularly from a concentration of sulphur-containing amino acids greater than 75 mg/l, a clear degradation of the organoleptic properties of the food products is noted. This degradation is noted by means of a standard taste test as described above, which reveals the existence of a sulphur taste capable of making the products unsuitable for consumption and marketing. It should be noted that the disagreeable sulphur taste occurs in particular in the case of incorporation of cysteine and/or of methionine at more than 75 mg/l, or even in certain cases at more than 50 or 30 mg/l, but also when the concentrations of sulphur-containing amino acids exceed such values due to the presence of additional substances, for example yeast extract or yeast autolysate, in particular at a level of more than 0.5% (w/w). Another important characteristic of the process of the invention is that the incorporation of the ferments containing the bifidobacteria is done directly into the starting substance intended to become the fermented food product, without necessarily resorting to artificial/synthetic intermediate growth media. According to a particular embodiment, the process as defined above does not comprise a stage of addition of additional substances containing one or more sulphur-containing amino acids. According to another particular embodiment, the process as defined above comprises a stage of addition of additional substances containing one or more sulphur-containing amino acids in the free form, the concentration of sulphur-containing amino acids in the free form in the additional substances being less than approximately 1.7%, preferably less than approximately 0.5%, and the concentration of said additional substances in the fermented food product being less than approximately 0.5%. More particularly, said stage of addition of additional substances can involve addition of a yeast extract and/or yeast autolysate and/or milk, plant or soya protein hydrolysate at a concentration of less than approximately 0.5% (w/w). Preferably, this stage of addition of additional substances takes place before the fermentation stage, for example substantially simultaneously with the seeding stage and/or simultaneously with the stage of incorporation of at least one sulphur-containing amino acid. The benefit of an addition substantially simultaneously with the seeding stage and/or simultaneously with the stage of incorporation of at least one sulphur-containing amino acid is of a practical nature. In this case, the additional yeast extract type substances are at least partially degraded during fermentation, as they serve to supply nutrients to the ferments. Thus the concentration of the additional yeast extract type substances varies during the fermentation. Advantageously, the process for the preparation of a fermented food product as defined above also comprises a pasteurization stage taking place before the seeding stage, making it possible to obtain a pasteurized starting substance from the starting substance. By “pasteurization” is meant the method usual in the field of food preservation involving a rapid heating without boiling, followed by rapid cooling, making it possible to destroy most of the bacteria while partially preserving the proteins. According to a particular embodiment, the stage of incorporation of at least one sulphur-containing amino acid takes place before the pasteurization stage, the sulphur-containing amino acid or acids being incorporated at a concentration of approximately 5 to approximately 75 mg/l, in particular approximately 5 to approximately 30 mg/l, in particular approximately 10 to approximately 15 mg/l, in particular approximately 12 to approximately 15 mg/l, and in particular 12.5 mg/l. The benefit of incorporation before the pasteurization stage is of a practical nature. According to another particular embodiment, the stage of incorporation of at least one sulphur-containing amino acid takes place substantially simultaneously with the seeding stage, the sulphur-containing amino acid or acids being incorporated at a concentration of approximately 5 to approximately 50 mg/l, in particular approximately 5 to approximately 30 mg/l, in particular approximately 5 to approximately 20 mg/l, in particular approximately 10 to approximately 15 mg/l, in particular approximately 12 to approximately 15 mg/l, and in particular 12.5 mg/l. The benefit of incorporation substantially simultaneously with the seeding stage is of an economic nature (the sulphur-containing amino acid or acids are not partially destroyed by any heat treatment or pasteurization before the seeding) and of a practical nature. According to another particular embodiment, the stage of incorporation of at least one sulphur-containing amino acid takes place after the seeding stage and before the fermentation stage, the sulphur-containing amino acid or acids being incorporated at a concentration of approximately 5 to approximately 50 mg/l, in particular approximately 5 to approximately 30 mg/l, in particular approximately 5 to approximately 20 mg/l, in particular approximately 10 to approximately 15 mg/l, in particular approximately 12 to approximately 15 mg/l, and in particular 12.5 mg/l. The benefit of incorporation after the seeding stage and before the fermentation stage is of a practical nature and ensures an increased survival of the bifidobacteria during the storage of the product. It should be noted that in the case where the incorporation of the sulphur-containing amino acid or acids takes place before the pasteurization stage, the quantity of sulphur-containing amino acids to be incorporated must be increased by approximately 30 to 50% with respect to the case where this incorporation takes place after the optional pasteurization stage, i.e. in particular substantially simultaneously with the seeding stage or after the seeding stage. In fact, in the first case some of the sulphur-containing amino acids are destroyed during the pasteurization. In other words, the top part of the concentration range for sulphur-containing amino acids of 50-75 mg/l which is included within the concentration range for sulphur-containing amino acids provided in the invention relates more specifically to the case where the incorporation of the sulphur-containing amino acids takes place prior to a pasteurization stage. It should be noted that it is possible to envisage dividing the stage of incorporation of sulphur-containing amino acids into two or more sub-stages, which can optionally occur at different times in the process according to the invention. The concentration of sulphur-containing amino acids which is indicated above then corresponds to the total concentration of sulphur-containing amino acids at the end of the different sub-stages of incorporation of sulphur-containing amino acids. According to a preferred embodiment, the process for the preparation of a fermented food product as defined above comprises a stage of addition of an intermediate preparation simultaneously with the seeding stage or between the seeding stage and the fermentation stage, so as to obtain, from the seeded substance, a completed seeded substance, or after the fermentation stage, so as to obtain, from the fermented substance, a completed fermented substance, said intermediate preparation comprising a preparation of fruits and/or cereals and/or additives such as flavourings and colourings, and said stage of addition of an intermediate preparation can take place simultaneously with the stage of incorporation of at least one sulphur-containing amino acid. The intermediate preparation can in particular contain thickeners (soluble and insoluble fibres, alginates, carragheenans, xanthan gum, pectin, starch, in particular gelatinized, gelan gum, cellulose and its derivatives, guar and carob gum, inulin) or sweeteners (aspartame, acesulphame K, saccharine, sucralose, cyclamate) or preservatives. Examples of flavourings are: apple, orange, strawberry, kiwi fruit, cocoa flavouring etc. Examples of colourings are: beta-carotene, carmine, cochineal red. Moreover, the preparation of the abovementioned fruits can comprise fruits which are whole or in pieces or in jelly or in jam, making it possible for example to obtain fruit yogurts. The intermediate preparation can also contain plant extracts (soya, rice etc.). According to another embodiment of the invention, the seeding stage comprises inoculation with seeding ferments containing approximately 10 6 to approximately 2.10 8 , more particularly approximately 10 6 to approximately 10 7 bifidobacteria, per ml (or per gram) of starting substance. If a quantity of bifidobacteria greater than this range is inoculated, undesired acetic acid type tastes can develop. If a quantity of bifidobacteria less than this range is inoculated, the final quantity of bifidobacteria is insufficient. Advantageously, in the process for the preparation of a fermented food product according to the invention, the bifidobacteria are chosen from bacteria of the type Bifidobacterium animalis , in particular Bifidobacterium animalis animalis and/or Bifidobacterium animalis lactis , and/or Bifidobacterium breve and/or Bifidobacterium longum and/or Bifidobacterium infantis and/or Bifidobacterium bifidum. Particularly preferably, in the process for the preparation of a fermented food product according to the invention, the bifidobacteria are chosen from bacteria of the type Bifidobacterium animalis. Advantageously, in the process for the preparation of a fermented food product according to the invention, the seeding ferments contain lactic bacteria, in particular one or more bacteria of the genus Lactobacillus spp. and in particular Lactobacillus delbrueckii bulgaricus and/or Lactobacillus casei and/or Lactobacillus reuteri and/or Lactobacillus acidophilus and/or Lactobacillus helveticus and/or Lactobacillus plantarum , and/or bacteria of the type Lactococcus cremoris and/or Streptococcus thermophilus and/or Lactococcus lactis and/or one or more bacteria of the genus Leuconostoc. According to an advantageous embodiment of the process for the preparation of a fermented food product as defined above, the proportion of bifidobacteria in the seeding ferments is approximately 20 to approximately 75%, in particular approximately 30 to approximately 50%, in particular approximately 35 to approximately 40%, in particular approximately 37.5%. By “proportion of the bifidobacteria in the seeding ferments”, is meant the proportion of the bifidobacteria relative to all of the inoculated bacteria in total during the seeding stage. This proportion corresponds to an optimum in terms of cost and final concentration of bifidobacteria, given that the higher the concentration of bifidobacteria at the start, the more competitive they are in terms of growth relative to the other strains in the ferments, and the more rapidly the optimum concentration of bifidobacteria is reached. According to a preferred embodiment of the process for the preparation of a fermented food product as defined above, the starting substance is based on plant juice and in particular fruit juice or vegetable juice such as soya juice, or on a dairy product, and in particular cow's milk and/or goat's milk. The starting substance can also comprise sheep's and/or camel's and/or mare's milk. In the case where the fermented food product is a dairy product, the starting substance can comprise milk, milk powder, sugar, a mixture of milk and plant juice, a mixture of milk and fruit juice, a mixture of milk and starch. Advantageously, the process for the preparation of a fermented food product according to the invention is such that the pasteurized starting substance is a pasteurized starting substance, which is held, optionally homogenized, and cooled down, obtained from a raw material, said process comprising, before the seeding stage, the following successive stages: a stage of standardization of fatty substances of the raw material so as to obtain a standardized substance, a stage of enrichment with dried matter of the standardized substance obtained in the preceding stage, so as to obtain an enriched substance, a stage of preheating of the enriched substance obtained in the preceding stage, so as to obtain a starting substance, a stage of pasteurization and holding of the starting substance obtained in the preceding stage, so as to obtain a pasteurized and held substance, an optional stage of homogenization of the pasteurized and held substance obtained in the preceding stage, so as to obtain a pasteurized, held and optionally homogenized substance, a stage of initial cooling of the pasteurized, held and optionally homogenized substance obtained in the preceding stage, so as to obtain a pasteurized starting substance, held, optionally homogenized, and cooled down. By “standardization of fatty substances” is meant a stage of bringing the quantity of fats present in the starting substance to a pre-determined level. Enrichment with dried matter involves the addition of proteins and fatty substance in order to modify the firmness of the curd. “Holding” involves a rapid thermization of the milk and makes it possible to destroy the vegetative microbial flora, including pathogenic forms. Its typical duration is from 4 to 10 minutes, in particular from 5 to 8 minutes, and in particular approximately 6 minutes. By “homogenization” is meant the dispersion of the fatty substances in the milk-type substance into small fat globules. The homogenization is carried out for example at a pressure of 100 to 280 bars, in particular 100 to 250 bars, in particular 100 to 200 bars, in particular approximately 200 bars. This homogenization stage is purely optional. It is in particular absent from the production process of products with 0% fatty substances. According to a particular embodiment, the process for the preparation of a fermented food product as defined above comprises a packaging stage between the seeding stage and the fermentation stage, said packaging stage making it possible to obtain, from the seeded substance obtained in the seeding stage, a seeded and packaged substance. This particular embodiment corresponds to the case of the firm-type fermented food products. More particularly, the process for the preparation of a fermented food product as defined above comprises: a stage of seeding a starting substance, optionally pasteurized, by inoculation with seeding ferments containing approximately 10 6 to approximately 2.10 8 bifidobacteria, more particularly approximately 10 6 to approximately 10 7 bifidobacteria per ml of starting substance, in order to obtain a seeded substance, a stage of packaging the seeded substance obtained in the preceding stage, in order to obtain a packaged seeded substance, a stage of fermentation of the packaged seeded substance obtained in the preceding stage, such that the temperature at the start of fermentation is approximately 36 to approximately 43° C., in particular approximately 37 to approximately 40° C., the temperature at the end of fermentation is approximately 37 to approximately 44° C., in particular approximately 38 to approximately 41° C., and the fermentation time is approximately 6 to approximately 11 hours, in order to obtain a fermented substance, a stage of final cooling of the fermented substance obtained in the preceding stage, such that the temperature at the start of the final cooling is less than approximately 22° C. and the temperature at the end of the final cooling is approximately 4 to approximately 10° C., so as to obtain a fermented food product. According to an alternative embodiment, not involving the preparation of firm-type products, the process for the preparation of a fermented food product according to the invention comprises the following successive stages after the fermentation stage: a stage of intermediate cooling of the fermented substance obtained in the fermentation stage, so as to obtain a pre-cooled substance, a stage of storage of the pre-cooled substance obtained in the preceding stage, so as to obtain a stored substance, a stage of final cooling of the stored substance obtained in the preceding stage, so as to obtain a fermented food product. According to a preferred embodiment, said fermentation stage is such that the temperature at the start of fermentation is of approximately 36 to approximately 43° C. and in particular approximately 37 to approximately 40° C., the temperature at the end of fermentation is approximately 37 to approximately 44° C. and in particular approximately 38 to approximately 41° C., and the fermentation time is approximately 6 to approximately 11 hours. Advantageously, said intermediate cooling stage is such that the intermediate cooling time is approximately 1 hour to approximately 4 hours and in particular approximately 1 hour 30 minutes to approximately 2 hours and the intermediate cooling temperature is approximately 4 to approximately 22° C. Preferably, said storage stage is such that the storage time is less than or equal to approximately 40 hours. Advantageously, said final cooling stage is such that the temperature at the start of final cooling is less than approximately 22° C. and the temperature at the end of final cooling is approximately 4 to approximately 10° C. According to a preferred embodiment, the process for the preparation of a fermented food product according to the invention comprises: a stage of seeding a starting substance, optionally pasteurized, by inoculation with seeding ferments containing approximately 10 6 to approximately 2.10 8 , more particularly approximately 10 6 to approximately 10 7 bifidobacteria per ml (or per gram) of starting substance in order to obtain a seeded substance, a stage of fermentation of the seeded substance obtained in the preceding stage, such that the temperature at the start of fermentation is approximately 36 to approximately 43° C., in particular approximately 37 to approximately 40° C., the temperature at the end of fermentation is approximately 37 to approximately 44° C., in particular approximately 38 to approximately 41° C., and the fermentation time is approximately 6 to approximately 11 hours, in order to obtain a fermented substance, a stage of intermediate cooling of the fermented substance obtained in the preceding stage, such that the intermediate cooling time is approximately 1 hour to approximately 4 hours, in particular approximately 1 hour 30 minutes to approximately 2 hours and the intermediate cooling temperature is approximately 4 to approximately 22° C., so as to obtain a pre-cooled substance, a stage of storage of the pre-cooled substance obtained in the preceding stage, such that the storage time is less than or equal to approximately 40 hours, so as to obtain a stored substance, a stage of final cooling of the stored substance obtained in the preceding stage, such that the temperature at the start of final cooling is less than approximately 22° C. and the temperature at the end of final cooling is approximately 4 to approximately 10° C. so as to obtain a fermented food product. According to a particular embodiment of the process for the preparation of a fermented food product as defined above, an additional stirring stage is provided between the fermentation stage and the intermediate cooling stage, making it possible to obtain, from the fermented substance obtained in the fermentation stage, a stirred fermented substance. By “stirring” is meant a process of mechanical stirring using a turbine or helical stirrer. It is a stage which determines the oiliness of the product in particular the dairy product. If the stirring is too violent, incorporation of air and separation of the serum can occur. If the stirring is insufficient, the product risks subsequently becoming too thick. According to a particular embodiment, the process for the preparation of a fermented food product according to the invention comprises, after the final cooling stage, a stage of preservation of the fermented food product at a temperature comprised between approximately 4 and approximately 10° C. The invention also relates to a fermented food product as obtained from the process as defined above. BRIEF DESCRIPTION OF THE DRAWING FIGURES FIG. 1 represents a comparison of the effects of cysteine and vitamin C on the acidification of milk by the ferment of Example 1. The time in minutes is shown along the x-axis, the pH along the y-axis. Curve A: control without vitamin C or cysteine; curve B: vitamin C; curve C: cysteine. FIG. 2 represents the development of the population of bifidobacteria in the control model during preservation at 10° C. Along the x-axis, the preservation time in days; along the y-axis, the population of bifidobacteria in CFU/ml. ▪: with 15 mg/l of filtered cysteine; ▴: without cysteine. FIG. 3 represents the development of the population of bifidobacteria in the milk as a function of the treatment of the stimulant. X-axis: preservation time in days; y-axis: population in CFU/ml. Conditions: ▪, control without cysteine or methionine; ∘, autoclaved cysteine; ●, filtered cysteine; □, autoclaved methionine; dotted curve, filtered methionine. FIG. 4 represents the monitoring of the population of bifidobacteria in the control model during preservation at 10° C. X-axis: preservation time in days; y-axis: population in CFU/ml. ▪: cysteine at 12 mg/l incorporated before pasteurization; ▴: control without cysteine. DETAILED DESCRIPTION OF THE INVENTION Examples Example 1 Study of the Mode of Action of Cysteine as a Stimulant A ferment comprising Streptococcus thermophilus (CNCM: I-1630)+ Lactobacillus delbreckii ssp. bulgaricus (CNCM: I-1632)+ Lactobacillus delbrueckii ssp. bulgaricus (CNCM: I-1519)+ Bifidobacterium animalis ssp lactis (CNCM: I-2494) is used. This example involves studying the mode of action of cysteine as a stimulant, and determining whether it has a metabolic or antioxidant effect. The growth of bifidobacteria in milk is measured in the presence of a solution of vitamin C (0.5 g/l) completely reducing the oxygen in the medium, and a solution of cysteine (50 mg/l). Constitution of the product model: Milex skimmed milk powder supplied by Arla food: 120 g Water: quantity sufficient for 1 kg A heat treatment is carried out involving pasteurization for 30 minutes at 95° C. in a bubbling water bath. The cysteine is supplied by Sigma. The solution is prepared at 500 g/l, filtered on a 0.2 μm Nalgène filter unit. This solution is used injected sterilely into the pasteurized model for a final concentration of 50 mg/l. The vitamin C is supplied by Sigma. The solution is prepared at 100 g/l, filtered on a 0.2 μm Nalgène filter unit (cat. 156-4020, Nalge Europe Ltd, Belgium). This solution is used injected sterilely into the pasteurized model for a final concentration of 0.5 g/l. The seeding doses of the product model are given in Table 1 which follows. TABLE 1 Seeding doses Volume for 1 l in μl Control Filtered cysteine Vitamin C I-1630 100 100 100 I-1519 + I-1632 220 220 220 I-2494 190 190 190 Cysteine 100 Vitamin C 5 ml The seeding is 5.10 6 CFU/ml of Streptococcus thermophilus and 5.10 6 CFU/ml of Lactobacillus bulgaricus. The monitoring of the acidification of the model at 37° C. is represented in Table 2 below as well as in FIG. 1 . TABLE 2 Monitoring of the acidification of the model Vitamin C Filtered cysteine Control Ta 86 90 83 Vmax −0.0079 −0.01046 −0.00791 pHm 5.96 5.82 6.06 Tmax 184 208 180 pH 0 6.5 6.6 6.7 TpH 5.5 260 248 270 TpH 5 391 354 412 TpH 4.8 479 417 506 D 0 CFU/ml 1.02 · 10 8 2.79 · 10 8 1.47 · 10 8 Ta = latency time (in minutes) Vmax = maximum rate (in pH units/minute) pHm = pH at the maximum acidification rate Tmax = time at Vmax (in minutes) pH 0 = pH at start of fermentation TpH 5.5 = time to arrive at pH 5.5 (in minutes) TpH 5 = time to arrive at pH 5 (in minutes) TpH 4.8 = time to arrive at pH 4.8 (in minutes) D 0 CFU/ml = quantity of bifidobacteria obtained at the end of the fermentation. It is noted that the acidification curve in the presence of cysteine differs from the acidification curve in the presence of vitamin C, which is itself virtually indistinguishable from the control acidification curve without vitamin C or cysteine. Given that vitamin C is an antioxidant, it is deduced from this that the stimulant effect of cysteine is not an antioxidant effect but is more certainly an effect of providing essential amino acid. Example 2 Determination of the Cysteine Stimulant Dose A ferment comprising Streptococcus thermophilus (CNCM: I-2272)+ Streptococcus thermophilus (CNCM: I-2773)+ Streptococcus thermophilus (CNCM: I-2130)+ Lactobacillus delbrueckii ssp. bulgaricus (CNCM: I-1519)-+ Bifidobacterium animalis ssp lactis (CNCM: I-2494) is used. “Milk models” are constituted by standard stirred yogurts comprising the ferment described above. The use of 0.2 μm-filtered cysteine was assessed in the “milk models” in proportions comprised from 5 mg/l to 50 mg/l (preferably from 5 to 20 mg/l). For the bifidobacteria counting method, reference may be made to M. Grand et al., Quantitative analysis and molecular identification of bifidobacteria strains in probiotic milk products, Eur. Food Res. Technol. 217:90-92 (2003). The population of bifidobacteria for the test containing the highest concentration of L cysteine is 3.10 8 CFU/ml at D+24 h, D corresponding to the time of packaging the product and remains stable after preservation for up to 28 days at 10° C. The standard control population (Control population D0: 1.10 8 CFU/ml) is 9.10 7 CFU/ml at 28 days of preservation at 10° C. The population of bifidobacteria for the test containing the lowest concentration of L cysteine is 1.10 8 CFU/ml at D+24 h. Certain products have an undesirable taste characterized by a sulphur note which can be detected as from 0.002% of added cysteine. Below this cysteine concentration the products are accepted: a dose of 0.0015% represents a good compromise between the organoleptic constraints and constraints in terms of a Bifidobacterium population >2.10 8 CFU/ml. Growth tests on milk carried out in the presence of 0.0015% i.e. 15 mg/l of filtered cysteine have made it possible to reach a Bifidobacterium I-2494 population of 2.8.10 8 CFU/ml after 28 days of preservation at 10° C. (the development of the population relative to the control without cysteine is represented in FIG. 2 ). From a sensory analysis point of view, the products produced do not have a detectable undesirable taste in comparison with the standard. Example 3 Acidification Kinetics The ferment described in Example 2 is used. The acidification kinetics of milk in the presence (15 mg/L) of the optimum dose of cysteine and in the absence of cysteine (control) show the absence of the effect of the cysteine on the overall kinetics. Example 4 Effect of the Type of Treatment of the Sulphur-Containing Amino Acid The impact of sterilization by filtration or thermization of the cysteine and methionine is assessed (final concentration used: 50 mg/l). The solutions are either filtered at 0.2 μm or autoclaved for 5 minutes at 121° C. then frozen in the form of beads in liquid nitrogen. Constitution of the model: Milex skimmed milk powder supplied by Arla food: 120 g Water: quantity sufficient for 1 kg Heat treatment: pasteurization for 30 minutes at 95° C. in a bubbling water bath Cysteine: supplier Sigma. The solution is prepared at 500 g/l, filtered on a 0.2 μm Nalgène filter unit or sterilized at 121° C. for 5 minutes by an autoclave controlled by temperature probe (Fetinge France S.A., reference KL 60/101). This solution is injected sterilely into the pasteurized model for a final concentration of 50 mg/l. Methionine: supplier Sigma. The solution is prepared at 300 g/l; the filtration or sterilization treatment is identical to that carried out for the cysteine solution. This solution is injected sterilely into the pasteurized model for a final concentration of 50 mg/l. The seeding doses are referred to in Table 3 below. TABLE 3 Seeding doses Volume for 1 l in μl Con- Filtered Autoclaved Filtered Autoclaved trol cysteine cysteine methionine methionine I-1630 100 100 100 100 100 I-1519 + 220 220 220 220 220 I-1632 I-2494 95 95 95 95 95 Filtered 100 cysteine Autoclaved 100 cysteine Filtered 100 methionine Autoclaved 100 methionine The seeding is 5.10 6 CFU/ml of Streptococcus thermophilus and 5.10 6 CFU/ml of Lactobacillus bulgaricus. The monitoring of the population of bifidobacteria in the model preserved at 4° C. as a function of the various conditions above is represented in FIG. 3 as well as in Table 4 below: TABLE 4 Development of the population of bifidobacteria D 0 D 10 D 24 D 29 CFU/ml CFU/ml CFU/ml CFU/ml Filtered 5.1.10 8 4.3 · 10 8 4.0 · 10 8 2.3   10 8 cysteine Autoclaved 3.1 · 10 8 5.2.10 8 2.8.10 8 1.7.10 8 cysteine Filtered 4.0.10 8 6.2 · 10 8 3.4 · 10 8 2.3 · 10 8 methionine Autoclaved 3.4.10 8 3.5 · 10 8 3.5 · 10 8 2.8 · 10 8 methionine Control 1.7.10 8   7 · 10 7   5 · 10 7   2 · 10 7 The reference time D0 corresponds to placing in pots (packaging). The measurements at D10, D24, D29 are carried out 10 days, 24 days, 29 days respectively after this placing in pots. In all cases the population of bifidobacteria is increased by the supply of cysteine or methionine. No effect of the heat treatment on the effectiveness of the stimulants can be observed under the test conditions. The heat treatment applied to the cysteine at 50 mg/l degrades only a part thereof, the residual concentration (not assessed) is sufficient to improve the population of bifidobacteria. Example 5 Development of the Population of Bifidobacteria During Preservation in the Case of Incorporation of Cysteine Before Pasteurization The dose of 12 mg/l of cysteine is defined as having a stimulant effect responding to the target population (2.10 8 CFU/ml) and responding positively in organoleptic terms (no detectable difference). This concentration was assessed on direct incorporation in the model and pasteurized composition (95° C., 30 minutes). The monitoring of the population of bifidobacteria in the product model during preservation at 10° C. is represented in FIG. 4 . The population of Bifidobacterium is 2.4.10 8 CFU/ml at D1 (i.e. 24 hours of storage) and remains stable after 44 days of preservation at 10° C. (above 1.4.10 8 CFU/ml). The stimulant effect is clearly demonstrated relative to the standard control (1.6.10 8 CFU/ml at D1; 7.65.10 7 CFU/ml at D8; 2.10 7 CFU/ml at D28; 1.8.10 7 CFU/ml at D35; 8.5.10 6 CFU/ml at D44) under these conditions: the population at D0 is higher when the sulphur-containing amino acids are used and the maintenance of the population during the life of the product is very much improved. This stimulant effect however remains less effective than the addition of 0.2 μm filtered cysteine to the model (3.10 8 CFU/ml), the heat treatment resulting in a degradation of the cysteine (residual concentration less than 15 mg/l). An initial overdosage of the quantity of cysteine is to be provided in the case where the cysteine undergoes a heat treatment. Conclusions relating to the conditions of utilization of cysteine: the utilization of directly filtered cysteine (with the ferment) preserves the cysteine; its addition to the composition of the heat-treated model produces a slightly less good result in terms of population but account must be taken of the degradation of the cysteine during the heat treatment (less available); its addition via a heat-treated dairy ingredient (for example GlycoMacroPeptide corresponding to the fragment 106-169 of kappa caseine) produces less good results (less available); its addition in the frozen form to the ferment is possible. Example 6 Production of a Fatty Stirred Yogurt According to the Invention on the Laboratory Scale (Micro-Production) 1. Composition of the Milk and Rehydration The stirred yogurt comprises the following ingredients: skimmed milk with 0% fat, cream with 40% fat and skimmed milk powder with 33% proteins. Firstly, all the ingredients are combined together in order to standardize the milk at a protein level (PL) of 4.4%, a fat level of 3.5% (FL) and a dried matter level of 15.8% with stirring of the medium for 60 minutes at approximately 750 rpm with a HEIDOLPH® stirrer in order for the proteins to rehydrate. Control of the standardization is carried out with a MILKOSCAN FT 120® infrared detector from FOSS®. Below, an example of the necessary quantities of each ingredient in order to obtain the targets characterizing the milk. Ingredients In % Skimmed milk 0% fat 87.5 Cream with 40% fat 8.7 Skimmed milk proteins 33% PL 3.8 TOTAL 100 2. Homogenization The milk is then heated between 50° C. and 60° C. in order to melt the fat globules. Once the temperature is reached, the 10 litres are homogenized with a MICROFLUIDIZER® from MICROCORPS®. This makes it possible to break up the fat globules by passing the capillary milk through a grid under a pressure of 350 bars. 3. Pasteurization A MEMMERT® water bath is prepared and adjusted to 103° C. The milk is transferred into 8 1-litre bottles, with a precise weighing of this quantity for each bottle. The bottles are immersed in the water bath up to the bottom of the neck at 103° C. for 35 minutes, then 10 minutes at 95° C. in the same water bath. 4. Cooling and Storage The bottles are cooled down in a cold water bath with a continuous flow, then stored at 4° C. in a refrigerator for 12 to 24 hours according to the test schedule envisaged. 5. Holding The milk bottles are removed from the refrigerator 45 minutes before the inoculation of the ferments and placed in a water bath at the considered fermentation temperature, i.e. 37° C. 6. Fermentation After inoculation of the ferments (5.10 6 CFU/ml of Streptococcus thermophilus; 5.10 6 CFU/ml of Lactobacillus bulgaricus; 5.10 6 CFU/ml of bifidobacteria) and L-cysteine (15 mg/l) at the fermentation temperature of 37° C., the bottles are re-immersed in the water bath, and the acidification is monitored by a CINAC® from YSEBAERT® up to a pH of 4.8. 7. Cutting of Coagulum and Smoothing The coagulum in the bottle is cut by hand. The yogurt with cut coagulum is poured into the hopper of the smoothing platform. The smoothing takes place via a metal grid with a porosity of 500 microns and the smoothed product is cooled down to 20° C. via an exchange circuit in iced water. 8. Packaging and Storage Packaging is carried out manually in 125-ml pots and the lid is heat-sealed with a DNV-100-25 PPV-A® heat sealer from FESTO®. The products are stored in a cooler at 10° C. throughout the test. Example 7 Assessment of the Dose of Cysteine to be Added in Order to Obtain a Product with Good Organoleptic Quality and Containing the Target Population of Bifidobacteria Different products were prepared with increasing doses of cysteine (see the table below). The control was the standard dairy product containing the ferment. Range: volume/1 L Cysteine dose 3.2 mL 0.0080% 80 mg/L 2 mL 0.0050% 50 mg/L 0.8 mL 0.0020% 20 mg/L 0.4 mL 0.0010% 10 mg/L 0.2 mL 0.0005%  5 mg/L Each product was tasted by 4 individuals who were very familiar with the reference product from an organoleptic point of view. These individuals gave their opinions in terms of the presence of bad tastes (sulphur taste, acid note), the reference being the standard product containing no cysteine. Results Test Populations (CFU/mL) Sensory assessment Time T0 T pH 4.8 Tf 495 min (n = 4) 1 4.40E+06 / 1.70E+08 Sulphur taste and/or acid note detected by all the tasters 0.008% 2 4.70E+06 1.90E+08 2.40E+08 Sulphur taste and/or acid note detected by all the tasters 0.005% 3 3.30E+06 2.50E+08 3.10E+08 Sulphur taste and/or acid note detected by all the tasters 0.002% 4 / / / Sulphur taste and/or acid note detected by all the tasters 0.0015%  5 3.10E+06 1.50E+08 2.40E+08 No unpleasant taste detected 0.001% 6 3.90E+06 1.10E+08 1.20E+08 No unpleasant taste detected 0.0005%  The 0.0015% dose not yet being optimum from an organoleptic point of view, the 0.00125% dose was tested. This dose represents a very good compromise between the constraint in terms of population maintenance and the constraint in terms of organoleptic quality. The sensory profile of a product with 0.00125% (12.5 mg/l) added cysteine was produced by a jury of experts comprising 15 individuals trained in this type of tasting. Two repetitions were carried out. The tasters had to judge the products on the basis of 23 descriptors. The results based on these descriptors (essential for defining the organoleptic quality of the product relative to the reference product) showed no significant harmful difference on the basis of these descriptors. These descriptors were the following: Product appearance Visual whey (visual assessment of the quantity of whey on the product surface) Texture on the spoon before stirring Shape holding ability (relates to the stability of the structure of the product) Texture on the spoon after stirring of the product Thickness (resistance to the movement of the spoon) Thread (continuity of the flow thread) Covering (quantity of product which covers the back of the spoon) Texture in the mouth after stirring of the product Melting away (speed of disappearance of the product in the mouth) Coating (coats the inside of the mouth) Fat (Sensation of fat in the mouth) Soft (Tactile sensation of softness in the mouth) Flavours Acid Sweet Bitter Astringent Milk flavourings Unpleasant tastes Cream Butter Milk Fromage frais Acetaldehyde Lactoserum Lactone Lemon Potato The sought result is an absence of significant difference between the control product and the product supplemented with cysteine. In the present case, a product according to the invention, supplemented with 12.5 mg/l of cysteine exhibits no significant difference in terms of appearance, texture, flavours and tastes relative to the control product.

The use of at least one sulphur-containing amino acid, at a total concentration of about 5 to 75 mg/ml, in particular of about 5 to about 50 mg/l, in particular of about 5 to about 30 mg/l, in particular of about 5 to about 20 mg/l, in free form, for implementing a method for preparing a fermented food product fermented by ferments containing bifidobacteria, the food product has acceptable sensory properties, contains more than about 5×10 7 , in particular more than about 10 8 bifidobacteria per gram of food product fermented for a shelf lifetime of at least 30 days, in particular a shelf lifetime of at least 35 days, and containing no more than 0.5% of yeast extract or of yeast autolysate.

BACKGROUND OF INVENTION [0001] 1. Field of Invention [0002] This invention relates to packaging for holding and displaying frangible items such as holiday ornaments. [0003] 2. Discussion of Related Art [0004] Decorative items such as holiday ornaments are customarily packaged in boxes that enable the ornaments to be only partially viewed without removing them from the packaging. Typically, the packaging includes a base, tray and cover. In some prior art packaging of this type, the base and cover are made of one piece of opaque material such as cardboard. Typically, the cover has a transparent plastic window, and the ornaments are supported on a tray inside the base. In other such prior art packaging, the base and cover are separately fabricated, and the cover made of a transparent material extends over the side walls of the base so that the ornaments inside the packaging can only be viewed through the top of the cover. In both forms of prior art described, the trays are made of opaque material, and the trays are provided with recesses that receive the ornaments in a position which leaves half or more of the surface of the ornament hidden from view. SUMMARY OF INVENTION [0005] In accordance with one aspect of this invention, the packaging enables substantially all of each ornament in the package to be viewed through the cover as the tray which supports the ornaments is made of a transparent material and the inner surface of the base is light reflective or mirror-like. In accordance with another aspect of this invention the ornaments sit in a relatively high position above the top of the side wall of the base, and the cover enables the ornaments to be viewed through the side as well as the top of the packaging. The elevated position of the ornament and the light properties of the materials from which the various components are made allow substantially all sides of the ornaments to be viewed through the cover without opening or removing the ornaments from the packaging. BRIEF DESCRIPTION OF DRAWINGS [0006] The accompanying drawings, are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings: [0007] FIG. 1 is a perspective view of ornament packaging embodying the present invention; [0008] FIG. 2 is a cross-sectional view of the packaging taken along section line 2 - 2 of FIG. 1 ; [0009] FIG. 3 is an exploded perspective view of the base and tray of one embodiment of the packaging, [0010] FIG. 4 is a perspective view of a partially erected base in accordance with one embodiment of this invention; [0011] FIG. 5 is a plan view of the blank from which the base of FIG. 4 is made; [0012] FIG. 6 is a perspective view of one embodiment of the cover in accordance with the present invention, and [0013] FIG. 7 is a plan view of the blank from which the cover of FIG. 6 is made. DETAILED DESCRIPTION [0014] This invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having,” “containing”, “involving”, and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. [0015] The packaging of the present invention includes three major elements, namely, a base 10 , cover 12 and tray 14 . The tray has one or more recesses 16 that receive the ornaments to be displayed in the packaging. As broadly described, packaging composed of a box, cover and tray are well known in the art. However, the packaging of the present invention includes modifications of several parts that markedly enhance the display of the glass ornaments or other products placed in the packaging. [0016] In accordance with one aspect of the present invention, the inner surfaces 17 of the base of packaging 10 are dark, and preferably black, and are light reflective, that is, they have a mirror-like quality that will reflect the ornaments or other items disposed before the surface. The base may be made of heavy paper, cardboard or other sheet product that preferably possesses enough stiffness to maintain the side walls of the box in a generally perpendicular position with respect to the base bottom wall. [0017] In accordance with one embodiment of the invention, the base 10 is made of cardboard cut as a single sheet in the configuration shown in FIG. 5 . The base blank shown has a pair of opposite side walls 18 attached to the bottom wall 20 along fold lines 22 , and flaps 24 extend from each end thereof at fold lines 26 . On the other two opposite sides of the bottom wall 20 are additional side walls 28 attached to those sides along fold lines 30 . This second set of opposite side walls 28 are formed so as to fold up and over the flaps 24 on the first pair of side walls and extend downwardly along their inner faces, and a flange 32 is provided at the edge of each of the second pair of side walls to frictionally engage the upper surface 17 of the bottom wall 20 when the box is erected. This particular configuration of the box is free of adhesive or other material which would detract from the clean unadorned box surfaces and add to its manufacturing costs. [0018] The tray 14 is made of transparent material such as PVC plastic and preferably is thermoformed. The tray is sized to fit within the base 10 and is complementary shaped so as to just fit within the base. The tray has side walls 36 whose lower edges 38 preferably rest on the base bottom wall 20 and flanges 32 , and the side walls are of a height to support the top wall 40 of the tray at or just below the rim 42 of the base. The wells 16 are shaped to complement the shape of the ornaments 44 or other items to be displayed in the package, and in the embodiment shown, as the ornaments are essentially round, the wells 16 are approximately hemi-spherical in shape. In the specific embodiment shown, as the wells are designed to receive decorative ornaments 44 that include a spherical body 46 and a short cylindrical collar 48 carrying the rings 50 by means of which the ornaments are hung, the wells 16 have generally semi-cylindrical extensions 52 that receive the collars. It is to be appreciated that while three wells are shown in the drawings, essentially any number may be provided, depending only on the size of the packaging and the size of the ornaments to be contained therein. [0019] In accordance with another aspect of the present invention, the ornaments 44 extend above the rim 42 of the base 10 . The portions of the ornaments extending above the tray 14 and base 10 are, however, enclosed by the cover 12 . [0020] In accordance with yet another aspect of the invention, the cover 12 is in the form of a sleeve (see FIG. 6 ) that fits snugly over the bottom 20 and side walls 18 and 28 of the base, but the top wall 60 of the cover is spaced substantially above the rim 42 of the base 10 and the top wall 40 of the tray 14 , so as to enclose the portions of the ornaments that extend above the tray. In accordance with one embodiment of the invention, the cover is made of a transparent material such as PVC. In the embodiment shown, the plastic from which the cover is made is formed as a sheet (see FIG. 7 ) and is provided with fold lines shown in broken lines in FIG. 7 , that define the top wall 60 and bottom walls 62 , opposite side walls 64 , and opposite end walls 66 , the latter each being composed of a pair of inner flaps 68 and a pair of outer flaps each composed of a female 70 and male 72 . The inner flaps 68 , two at each end of the cover, are integral with the side edges of the side walls 64 . The outer pair of flaps 70 and 72 are connected to the end edges 74 of the top and bottom walls 60 and 62 of the cover and in turn overlap one another and enclose the inner flaps 68 when the cover is erected. The outer flaps are releasably held in the cover forming configuration by means of tongues 76 , two carried on each of the male outer flaps 72 and threaded through a pair of slots 78 in the other outer flaps 70 . The assembly of the various end flaps is shown in FIGS. 1 and 2 . Obviously, other forms of closure may be used as well, such as single tongue and slot, interengaging slits, etc. [0021] In accordance with the embodiment of cover shown in FIGS. 6 and 7 , the cover is erected by bending the various walls along the fold lines (shown as broken lines) that connect them to adjacent walls of the cover blank. A narrow flange 80 is provided along the edge 82 of the lower wall 62 which is cemented to the one side wall 64 so as to permanently form the cover into a sleeve when the inner and outer pairs of flaps 68 , 70 and 72 are opened. Obviously such a flange could alternatively be provided along the edge 84 of the side wall 64 . In the configuration of an open ended sleeve, the sub-assembly of base 10 , tray 14 and ornaments 44 may be slipped within the cover through either end, and when the ends of the sub-assembly are aligned with the end edges of the top and bottom walls, the inner and outer end flaps may be detachably locked in the manner described. It will be appreciated that when the cover is assembled in that fashion on the sub-assembly of base, tray and ornaments with the end flaps closed, a secure package is formed that will not accidentally or unintentionally open and allow the contents of the cover to spill out. And when the cover is closed, with the base, tray, and ornaments disposed within the cover, all sides of each ornament may be readily viewed because of the transparency of the cover and tray and the light reflective quality of the inner surfaces of the base. Thus, when the package is on display, for example, in a store, display room or other facility, a potential customer viewing the package may quickly appreciate the full beauty of the ornaments on display by seeing all of their sides through the transparent cover and without opening the package. As is evident in FIGS. 1 and 2 , the ornaments may be viewed through the top wall 60 or the portions of the side walls 64 or of the end walls 66 of the cover that are disposed above the upper edges 42 of the side walls 18 and 28 of the base 10 as indicated by the reflected images 44 ′ and lines of sight 86 . [0022] While the preferred embodiment of the cover has been described in detail, it should be appreciated that other embodiments of covers made of transparent material may be used and achieve many of the advantages of the preferred embodiment described. [0023] For example, if the cover is of the same shape in plan view as the base and is sized to slip over a portion or all of the side and end walls of the base, and if this embodiment of cover is made of a transparent material, at least with respect to that portion of the cover which lies above the rim of the base, and further if the side walls of the cover extend above the top edges of the side walls of the base, the ornaments packaged therein will be easily viewed just as is described in connection with the preferred embodiment. However, such a cover would not provide a degree of protection provided by the preferred embodiment, and it may be too easy for a customer to open the box and handle the ornaments, and upon deciding to purchase the product, he/she may select another box as opposed to that which the customer opened. [0024] Alternative constructions are also available for the base. While in the preferred embodiment, the base is very conveniently erected without the use of any adhesive material. More conventional constructions may be employed with separate end and side walls on all sides thereof with such walls being cemented together. It is however, important that the inner surfaces of the walls including the bottom wall be mirror-like to enhance the visibility of the ornaments. [0025] It is also most advantageous to have the side walls of the tray made of a transparent material so as not to diminish the light reflecting quality of the inner surfaces of the base. However, as an alternative, the inner surfaces of the side walls of the tray may be made of a mirror-like material so as to substitute for the reflective qualities of the side walls of the base that are covered by the tray side walls. [0026] Having thus described several aspects of at least one embodiment of this invention, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of the invention. Accordingly, the foregoing description and drawings are by way of example only.

Packaging for enclosing and displaying frangible items has a base, tray and cover. The base has bottom and side walls that are opaque with their inner surfaces being mirroro-like. A tray sits in the base and is made of a transparent material and has recesses for supporting the items in a position wherein they extend above the side walls of the base. A cover extends beyond the side walls of the tray and extends over the tops of the items and is made of a transparent material enabling the items to be substantially fully viewed through the cover by virtue of the transparent cover, transparent tray and light reflecting side walls of the base.

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to U.S. Provisional Application No. 61/659,889 filed on Jun. 14, 2012. FIELD OF INVENTION [0002] The present invention relates to the field of instrument adapters for attaching medical instruments to handles, and more specifically to a highly secure instrument adapter mechanism which allows a surgeon to quickly change an instrument shaft to alter the function of the instrument during a surgical procedure. BRIEF DESCRIPTION OF THE DRAWINGS [0003] FIG. 1 is an exploded view of an exemplary secured instrument adapter mechanism. [0004] FIGS. 2 a and 2 b illustrate an exemplary receiver for a secured instrument adapter mechanism. [0005] FIGS. 3 a , 3 b and 3 c illustrate an exemplary sixty degree rotating collar for a secured instrument adapter mechanism. [0006] FIGS. 3 d and 3 e illustrate critical angles and measurements of the fingers. [0007] FIG. 4 illustrates an exemplary finger for a rotatable sixty degree rotating collar. [0008] FIGS. 5 a and 5 b illustrate perspective and side views, respectively, of an exemplary thrust washer. [0009] FIG. 6 illustrates an exemplary secured instrument adapter mechanism. [0010] FIG. 7 illustrates an exemplary secured instrument adapter mechanism with an instrument shaft inserted in the adapter. [0011] FIG. 8 a illustrates an exemplary secured instrument adapter mechanism in its unlocked position. [0012] FIG. 8 b illustrates an exemplary secured instrument adapter mechanism in its semi-engaged position. [0013] FIG. 8 c illustrates an exemplary secured instrument adapter mechanism in its locked position. [0014] FIG. 9 illustrates an exemplary rotatable sixty degree rotating collar with a slot and pin control. BACKGROUND [0015] Medical instrument handles utilize adapters to securely connect a variety of different instruments during surgical procedures. Most handles use adapters with locking and release mechanisms having intricate designs and multiple moving components. To prevent the locking and release mechanisms from damage and from exposure to bodily fluids and other debris, locking and release mechanisms are made interior to the handle. [0016] Most internal release mechanisms use an external collar which is pushed inward towards the handle to release the shaft of an instrument. One limitation of these internal release mechanisms, however, is the stability of the external collar. When an external collar is bumped at a certain position with enough force, instruments are inadvertently released from the handle. A positive locking device would not cause an instrument to accidently release from the handle because of bumping or other vibrations. [0017] Internal adapters known in the art also contain many components and moving parts which need to be manufactured separately and assembled. Additional parts mean additional manufacturing time and cost, as well as additional opportunities for parts to break and wear. [0018] It is desirable to develop an internal release mechanism that does not use a pushing release. [0019] It is desirable to develop an internal release mechanism that requires little physical effort to lock and release, yet provides a stable and secure connection between an instrument and the handle. [0020] It is desirable to develop an internal release mechanism that uses positive, impact-proof locking. Terms of Art [0021] As used herein, the term “assembly” means a plurality of mechanical parts which may or may not operate interdependently to perform a mechanical function. [0022] As used herein, the term “chamfer” refers to a beveled, angled or tapered edge which engages the edge of a second component to create a secured junction. [0023] As used herein, the term “finger” means a flexible or non-rigid protruding structure. [0024] As used herein, the term “inner contoured surface” refers to the inner surface of a finger which contains at least two distinctive sections having differing radii or angles. [0025] As used herein, the term “interior receiver channel diameter” refers to the aperture in a sixty degree rotating collar which engages a receiver. [0026] As used herein, the term “lead-in surface portion” refers to an initial portion of an inner contoured surface placed at an angle greater than that of a ramp surface portion. [0027] As used herein, the term “locking engagement” refers to the portion of an inner contoured surface which is adapted to engage a ball bearing. [0028] As used herein, the term “ramp surface portion” refers to a transitional portion of an inner contoured surface placed at an angle less than that of a lead-in surface portion. SUMMARY OF THE INVENTION [0029] The present invention is a highly secure instrument adapter with a rotating release rather than a pushing release. The device employs ball bearings and a small number of interlocking parts to achieve stability and positive, impact proof locking. DETAILED DESCRIPTION OF INVENTION [0030] For the purpose of promoting an understanding of the present invention, references are made in the text to exemplary embodiments of a secured instrument adapter mechanism, only some of which are described herein. It should be understood that no limitations on the scope of the invention are intended by describing these exemplary embodiments. One of ordinary skill in the art will readily appreciate that alternate but functionally equivalent structures and materials may be used. The inclusion of additional elements may be deemed readily apparent and obvious to one of ordinary skill in the art. Specific elements disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one of ordinary skill in the art to employ the present invention. [0031] It should be understood that the drawings are not necessarily to scale; instead, emphasis has been placed upon illustrating the principles of the invention. In addition, in the embodiments depicted herein, like reference numerals in the various drawings refer to identical or near identical structural elements. [0032] Moreover, the terms “substantially” or “approximately” as used herein may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. [0033] FIG. 1 is an exploded view of an exemplary embodiment of a highly secure instrument adapter 100 . As illustrated, highly secure instrument adapter 100 includes receiver 10 , rotating collar 30 , thrust washer 50 , interconnect tube 60 , handle core 65 that ends in cap 66 , locking ball bearing 70 , stabilizing ball bearings 92 and compression spring 94 . Handle 80 secures receiver 10 , rotating collar 30 , thrust washer 50 , interconnect tube 60 , handle core 65 with cap 66 , ball bearing 70 , stabilizing ball bearings 92 and compression spring 94 . In the exemplary embodiment shown, handle 80 , with handle cavity 82 , is illustrated as a simple handle designed to be easily grasped by one hand. However, in further exemplary embodiments, handle 80 may be any handle known in the art, including, but not limited to, torque-limiting handles. [0034] FIGS. 2 a and 2 b illustrate an exemplary receiver 10 in more detail. In the exemplary embodiment shown, receiver 10 is an internal threaded tubular body 11 with flat outside end surface 12 at the front of receiver 10 and centralized shaft cavity 15 creating a tubular passage completely through receiver 10 . Receiver 10 is adapted to receive the shaft of a medical instrument so that the medical instrument shaft may slide within centralized shaft cavity 15 . [0035] Receiver 10 also includes four locking apertures 18 a ( 18 b, 18 c and 18 d not shown) approximately half way up internal threaded tubular body 11 from flat outside end surface 12 . Locking apertures 18 a ( 18 b, 18 c and 18 d not shown) are configured to engage locking ball bearing 70 (not shown). In the exemplary embodiment shown, receiver 10 includes four equidistant and symmetrically arranged locking apertures 18 a ( 18 b, 18 c and 18 d not shown). However, in further exemplary embodiments, receiver may contain more or fewer locking apertures. In still further exemplary embodiments, locking apertures may not be equidistant from each other or may not be symmetrically arranged around internal threaded tubular body 11 . In yet further exemplary embodiments, locking apertures 18 a ( 18 b, 18 c and 18 d not shown) may be at a different distance along internal threaded tubular body 11 . [0036] In the embodiment shown, receiver 10 also includes an additional stabilizing aperture (not shown) in the top end of internal threaded tubular body 11 near flat outside end surface 12 that is designed to house at least one stabilizing ball bearing 92 and compression spring 94 . [0037] FIGS. 3 a , 3 b and 3 c illustrate an exemplary rotating collar 30 . FIG. 3 a is a perspective view of rotating collar 30 , illustrating radial frictional contours 32 around the perimeter of rotating collar 30 . Rotating collar 30 includes at least one stabilizing ball bearing groove 31 that partially spans the inner surface of rotating collar 30 . Receiver channel 34 runs the length of rotating collar 30 and has an internal diameter just larger than the external diameter of receiver 10 (not shown). In the exemplary embodiment shown, rotatable rotating collar 30 has an overall diameter just larger than the diameter for the front portion of handle 80 (not shown) near handle cavity 82 (not shown), so that handle 80 (not shown) is in contact with handle-contacting surface 38 . [0038] It is critical that one or more stabilizing design components and structures be utilized to ensure that instrument shaft 90 is stabilized and resistant to axial, transverse and angular movement during a surgical procedure. [0039] In the exemplary embodiment shown, a stabilizing ball bearing and spring assembly is utilized as the stabilizing component. In this exemplary embodiment, stabilizing ball bearings 92 and compression spring 94 exert a force to instrument shaft 90 when instrument shaft 90 is inserted into shaft cavity 15 and rotating collar 30 is rotated. When rotated collar 30 is rotated, a transverse force is applied to instrument shaft 90 by compressing compression spring 94 which engages a stabilizing ball bearing 92 against instrument shaft 90 . Rotating collar 30 includes at least one stabilizing contoured ball bearing groove 31 that partially spans the inner surface of rotating collar 30 . Stabilizing contoured ball bearing groove 31 is contoured so that it has a graduated variance in depth. Maximum force is applied to instrument shaft 90 when stabilizing ball bearing 92 is in contact with the shallowest portion of stabilizing contoured ball bearing groove 31 . [0040] In various embodiments, alternative stabilizing components such as springs, cams, contoured member, interlocking members, threaded components, protruberances and friction or pressure inducing members may be utilized to prevent movement of instrument shaft 90 during a surgical procedure. These alternatives may or may not be functionally equivalent to stabilizing ball bearing and spring assembly [0041] Also illustrated in FIG. 3 a , on the inner surface of rotating collar 30 , around receiver channel 34 , rotating collar 30 includes an inward projection 36 , which is designed to be in physical contact with the inner walls of handle cavity 82 (not shown) and terminates in flattened surface 37 . In the exemplary embodiment shown, inward projection 36 creates receiver channel 34 having an interior diameter of 0.540 inches. [0042] As illustrated in FIGS. 3 a , 3 b and 3 c , rotating collar 30 also includes a plurality of fingers 40 a, 40 b, 40 c, and 40 d which project outward from flattened surface 37 . In the exemplary embodiment shown, fingers 40 a, 40 b, 40 c and 40 d project 0.290 inches from flattened surface 37 and are 0.125 inches long. The length of fingers 40 a, 40 b, 40 c and 40 d however, may vary, as it is the radial measurement of contoured inner surface 47 portions which determine the exact length of fingers 40 a, 40 b, 40 c and 40 d. [0043] As illustrated, spacer structure 39 , a thinned down, flexible piece of material, holds fingers 40 a, 40 b, 40 c and 40 d a distance away from flattened surface 37 . In the exemplary embodiment shown, spacer structure 39 is approximately 0.019 inches thick. [0044] Alternating between fingers 40 a and 40 b, 40 b and 40 c, and 40 c and 40 d are circular apertures 44 a, 44 b and 44 c, respectively. As illustrated in FIG. 3 b , apertures 44 a and 44 c are identical and smaller than aperture 44 b. [0045] Looking specifically at fingers 40 a, 40 b, 40 c and 40 d, in the exemplary embodiments shown, each finger 40 a, 40 b, 40 c and 40 d has outer surface 45 , which is curved at a consistent radius, and smooth inner surface 46 , which is also curved at a consistent radius. [0046] Approximately halfway along fingers 40 a, 40 b, 40 c and 40 d, however, smooth inner surface 46 transitions to inner contoured surface 47 , which creates a tapered portion of fingers 40 a, 40 b, 40 c and 40 d with narrow end 48 gradually transitioning to wider end 49 . As illustrated most visibly in FIG. 3 b , contoured inner surface 47 of fingers 40 a, 40 b, 40 c and 40 d is not a consistent radius. [0047] In the exemplary embodiments shown, contoured inner surface 47 consists of three distinct portions, each having a distinct critical angle or radius. First is lead-in surface portion 47 a, near narrow end 48 , which transitions to ramp surface portion 47 b. Rample angle surface portion 47 b is flatter. Finally, locking engagement 47 c, near wider end 49 , is contoured to the radius of locking ball bearing 70 (not shown). [0048] In further exemplary embodiments, rotating collar 30 may contain more or fewer fingers, and fingers may be differently spaced around flattened surface 37 . In still further exemplary embodiments, fingers may be different dimesions, and the radii of contoured inner surfaces may differ to correspond to variations in receiver 10 (not shown) diameter or receiver channel 34 diameter. [0049] However, it is desirable to have as few parts and components as possible for manufacturing, while still maintaining the desired locking and securing properties. Four fingers strikes an appropriate balance between complexity in manufacturing and functionality. [0050] FIGS. 3 d and 3 e illustrate the critical angles and measurements of fingers 40 . Lead-in surface portion 47 a is placed at an angle of approximately 109.114 degrees as measured from the centerline A of receiver channel 34 . This angle is illustrated as θ A in FIG. 3 d . Ramp surface portion 47 b is placed at an angle of 86.502 degrees as measured from the centerline A of receiver channel 34 . This angle is illustrated as θ B in FIG. 3 d. [0051] Locking engagement 47 c has a radius of 0.070, which is also the radius of locking ball bearing 70 (not shown). In order to securely and stably engage, locking engagement 47 c and locking ball bearing 70 (not shown) must have corresponding radii. [0052] In further exemplary embodiments, the exact angles of lead-in surface portion 47 a and ramp surface portion 47 b, as well as the radius of locking engagement 47 c, may vary slightly. For example, the angle of ramp surface portion 47 b is 86.052 degrees, but may vary by plus or minus 20 degrees. This allows for gradual engement of a instrument shaft and an increase in pressure on the specific finger 40 which is touching a locking ball bearing 70 (not shown). The angle of lead-in surface portion 47 a may similarly vary by plus or minus 20 degrees. However, the exact radial measurement for locking engagement 47 c may vary within an amount determined by the diameter and shape of locking ball bearing 70 (not shown), as the two radii must properly correspond to provide secure and stable engagement. [0053] As illustrated in FIG. 3 e , there is a distance of approximately 42.642 degrees, illustrated as Θ C , between each finger 40 a, 40 b, 40 c and 40 d, with each finger 40 a, 40 b, 40 c and 40 d being approximately 47.358 degrees in ramp and engagement length. Further, finger 40 a is shifted approximately 10.679 degrees from center, such that 36.679 degrees (θ D ) of finger 40 a occurs counterclockwise from 0 degrees. As illustrated in FIG. 3 b , each subsequent finger 40 b, 40 c, 40 d is shifted approximately 10.670 degrees from 90 degrees, 180 degrees, and 270 degrees, respectively, to be equally spaced along flattened surface 37 . [0054] In still further exemplary embodiments, fingers 40 a, 40 b, 40 c and 40 d may be separated by between 20 and 70 radial degrees, depending on the number and size of fingers required or desired. For example, some exemplary embodiments may use between 2 and 8 fingers; the more fingers, the closer together fingers will be. [0055] FIG. 4 illustrates an exemplary finger 40 in further detail. Finger 40 has outer surface 45 and smooth inner surface 46 , each having a consistent radius corresponding to the inner and outer radii of outward projection 36 (not shown). Contoured inner surface 47 creates a tapered finger with a narrow end 48 and wider end 49 with its inconsistent radius. As illustrated, contoured inner surface 47 is divided into three sections, each having a different radius. Lead-in surface portion 47 a has a larger radius, resulting in a steep ramp, while ramp surface portion 47 b has a smaller radius, resulting in a flatter portion. Locking engagement 47 c has a radius corresponding to that of locking ball bearing 70 (not shown). [0056] FIGS. 5 a and 5 b illustrate perspective and side views, respectively, of an exemplary thrust washer 50 . [0057] FIG. 6 illustrates an exemplary highly secure instrument adapter 100 fully assembled without an instrument shaft. Receiver 10 is in receiver channel 34 (not shown) of rotating collar 30 , with internal threaded tubular body 11 adapted to engage threads on the exterior of interconnect tube 60 . Fingers 40 correspond to apertures 18 of receiver 10 , and thrust washer 50 is secured against the inner surfaces of fingers 40 . Both ends of interconnect tube 60 contain exterior threads, with the anterior end of interconnect tube 60 attaching to internal threaded tubular body 11 , and the posterior end of interconnect tube 60 attaching to handle core 65 (not shown) inside handle cavity 82 (not shown). Handle core 65 slides into handle cavity 82 from the posterior end of handle 80 (not shown) and is secured to handle 80 by its connection to interconnect tube 60 within handle cavity 82 . The posterior end of handle core 65 widens to form a cap 66 (not shown) that fits against the posterior end of handle 80 and covers the posterior end of handle cavity 82 . [0058] Also illustrated in FIG. 6 are the internal contours of shaft cavity 15 . Just inward from apertures 18 in the exemplary embodiment shown, centralizing chamfers 25 are triple square. However, in further exemplary embodiments, centralizing chamfers 25 may be any configuration, such as double square or hexagonal, to correspond to a particular instrument shaft. Interconnect tube 60 fits within end cavity 28 (not shown) of receiver 10 . [0059] FIG. 7 illustrates an exemplary highly secure instrument adapter 100 with instrument shaft 90 inserted and secured in shaft cavity 15 . As illustrated, instrument shaft 90 contains groove 93 which runs the circumference of instrument shaft 90 and engages stabilizing ball bearing 92 . [0060] FIGS. 8 a , 8 b and 8 c illustrate an exemplary adapter's 100 securing mechanism. [0061] FIG. 8 a shows highly secure instrument adapter 100 at rest. Locking ball bearing 70 is in one of apertures 44 , which are halfway between fingers 40 . Locking ball bearing 70 is freely rotatable in aperture 44 . As rotating collar 30 is rotated relative to instrument shaft 90 in a clockwise direction locking ball bearing 70 begins to be tightened between finger 40 and instrument shaft 90 . [0062] Because finger 40 is flexibly connected to rotating collar 30 at spacer structure 39 (not shown), finger 40 begins to flex outward from instrument shaft 90 as locking ball bearing 70 moves from lead-in surface portion 47 a through ramp surface portion 47 b, as illustrated in FIG. 8 a . As rotating collar 30 is rotated, the amount of force required to rotate rotating collar 30 increases. [0063] Once locking ball bearing 70 reaches locking engagement 47 c, the final change of radius along contoured inner surface 47 , locking ball bearing 70 locks into locking aperture 18 between instrument shaft 90 and finger 40 , as illustrated in FIG. 8 c. [0064] In the exemplary embodiments shown, instrument shaft 90 has groove 93 (not shown) around its circumference and aligned with locking ball bearing 70 when inserted into highly secure instrument adapter 100 . When in the locked position, as illustrated in FIG. 8 c , locking ball bearing 70 pushes inward on instrument shaft 90 , and is locked in groove 93 (not shown), thereby preventing instrument shaft 90 from being pulled outward from handle 80 (not shown). [0065] To release instrument shaft 90 , rotatable rotating collar 30 is forcibly rotated counterclockwise relative to instrument shaft 90 , returning securing mechanism to its resting, or unlocked, position as illustrated in FIG. 8 a . The flexibility provided by spacer structure 39 (not shown), which flexibly connects fingers 40 to rotating collar 30 , allows a user to force locking ball bearing 70 out of locking engagement 47 c to release instrument shaft 90 . [0066] The flexibility of spacer structure 39 , and the rotating design of highly secure instrument adapter 100 , also makes the locking functions impact-proof. For example, bumping instrument shaft 90 in any direction will not shake or move locking ball bearing 70 from the locked position, but may cause locking ball bearing 70 to flex finger 40 relative to instrument shaft 90 , while locking ball bearing 70 remains in its locked position (engaging locking engagement 47 c ). [0067] As illustrated in the exemplary embodiments shown in FIGS. 8 a , 8 b and 8 c , it takes very little rotating to go from unlocked ( FIG. 8 a ) to locked ( FIG. 8 c ). The high radius of lead-in surface portion 47 a of finger 40 causes locking ball bearing 70 to travel a greater distance over a smaller amount of rotation. Specifically, in the exemplary embodiment described, it is approximately 60 degrees from unlocked to locked position. In other words, it is 60 degrees from the center of locking ball bearing 70 at its resting position to the center of locking engagement 47 c. However, in further exemplary embodiments, highly secure instrument adapter 100 may be designed with approximately 50-70 degrees of rotation required between the unlocked and locked positions. [0068] The exemplary embodiment described in FIGS. 8 a , 8 b and 8 c uses a single locking ball bearing 70 . However, in further exemplary embodiments, four locking ball bearings 70 may be used to provide additional locking and securing stability for instrument shaft 90 . [0069] In the exemplary embodiments described, locking ball bearing 70 moves quickly over lead-in surface portion 47 a, and then moves gradually over ramp surface portion 47 b to locking engagement 47 c. Both fast and gradual motion is needed because, if all fingers 40 only provided gradual motion, fingers 40 would need to be longer and there would not be space for four, or even two or more, fingers 40 . [0070] With too gradual of motion, it would also require over 60 degrees of rotation to get ball bearing 70 to engage locking engagement 47 c. It is desirable to have as little rotation required as possible. [0071] FIG. 9 is an exemplary embodiment of rotating collar 30 with slot and pin control.

A highly secure instrument adapter includes a handle with an internal locking and release mechanism which does not use a pushing release and which requires little physical effort to lock and release, yet provides a stable and secure connection between an instrument and the handle. The locking mechanism is comprised an ergometric handle having an open handle cavity, a receiver having an internal threaded tubular body and a plurality of locking apertures, and a rotating collar having a limited range of rotation, a plurality of fingers that project outward from the flattened surface on a spacer structure, and a plurality of circular apertures placed alternately between said fingers.

BACKGROUND [0001] Graphic interfaces, such as graphic interfaces of web browsers, typically have security vulnerabilities in the form of visual spoofing. Such vulnerabilities can lead to malicious exploitations such as address bar spoofing and status bar spoofing. Such spoofing can lure even experienced users to perform unintended actions that result in serious security consequences. [0002] The computer-human interface or graphical user interface (GUI) plays an important role in systems security since a computer is simply a tool for people to perform real world activities, such as banking, trading, advertising and socializing. A user should be considered an “endpoint” of a communication channel between a server and client. Currently the trustworthiness of the “world wide web” is mainly to provide machine-to-machine trust over the Internet, so that the client (e.g., the browser computer) communicates to the intended server. Such a trust can be easily shattered by the last link between the client and its user (i.e., the “endpoint”), and thus the end-to-end security is compromised. [0003] The exposure of the machine user weakness is not limited to non-technical social engineering attacks where naive users are fooled to click on an arbitrary hyperlink and download malicious executables without any security awareness. Even for a technology savvy and security conscious user, vulnerabilities exist, and spoofing can take place. For example, even if an experienced user examines a status bar of the email client before the user clicks on a hyperlink, the user may not be able to tell that the status bar is spoofed and is navigated to an unexpected website. Furthermore, even if a user checks correspondence between a displayed uniform resource locator (URL) in a browser address bar and top level web page content, the user may not realize that the address bar is spoofed and that the displayed page comes from a malicious web site. Indeed, the combination of the email status bar spoofing and the browser address bar spoofing can give a rather “authentic” browsing experience to a faked web page. Spoofing can lead to numerous malicious acts, such as identity theft (i.e., “phishing”), malware installation, and faked news or information. [0004] A visual spoofing flaw is a generic term that refers to any flaw producing a misleading user interface or graphical user interface (GUI). Such flaws have been discovered in various commodity browsers (i.e., Internet browsers) including Internet Explorer (IE), Firefox, and Netscape Navigator. Visual spoofing flaws can be due to GUI logic flaws, where such flaws allow a malicious party to set “wrong” information in authentic security indicators, where authentic security indicators include email client status bars, the browser address bars and security warning dialog boxes. SUMMARY [0005] This summary is provided to introduce simplified concepts of uncovering logic flaws in graphical user interface, which is further described below in the Detailed Description. This summary is not intended to identify essential features of the claimed subject matter, nor is it intended for use in determining the scope of the claimed subject matter. [0006] In an embodiment, the methodology maps a visual invariant to a well-defined program invariant, which is a Boolean condition about user state and software state. This mapping is done based on an in-depth understanding of the source code of the software. The methodology is then to discover all possible inputs to the software which can cause the visual invariant to be violated. Resulting HTML tree structures can be used to craft instances of status bar spoofing. To systematically derive these scenarios, a formal reasoning tool may be used to reason about the well-defined program invariant. BRIEF DESCRIPTION OF THE CONTENTS [0007] The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference number in different figures indicates similar or identical items. [0008] FIG. 1 is a block diagram of an exemplary system that may be implemented to identify GUI logic flaws. [0009] FIG. 2(A) is a document object model tree representing a markup language source file. [0010] FIG. 2(B) is an element layout rendered by a browser based on a markup language source file. [0011] FIG. 2(C) is a graphical representation of an element stack based on a markup language source file. [0012] FIG. 3 is a block diagram of a message bubbling loop 300 that is performed when the browser receives a mouse message. [0013] FIG. 4 is a flow diagram of a user action sequence. [0014] FIG. 5 are exemplary document object model trees that cause status bar spoofing scenarios. [0015] FIG. 6 are element-stack representations of document object model trees. [0016] FIG. 7 is a browser window containing multiple frames. [0017] FIG. 8 is a flow diagram of an event sequence which loads a page in a current trident. [0018] FIG. 9 is a flow diagram of an event sequence of a history travel. [0019] FIG. 10 is a flow diagram of an event sequence of loading a new page into a new trident. [0020] FIG. 11 is a table of various locations and conditions for various address bar spoofing scenarios. [0021] FIG. 12 is a flow diagram of a spoofing scenario based on a race condition. [0022] FIG. 13 is a flow diagram of uncovering logic flaws as to a graphical user interface. [0023] FIG. 14 is a flow diagram for discovering spoofing scenarios. [0024] FIG. 15 is an illustration of a general computing environment for uncovering logic flaws in graphical user interface. DETAILED DESCRIPTION [0025] The following disclosure describes systems and methods for identifying graphical user interface (GUI) logic flaws. While aspects of described systems and methods to systematically examine logic of graphic interface design or implementation to identify semantic flaws can be implemented in any number of different computing systems, environments, and/or configurations, embodiments are described in the context of the following exemplary architectures. Overview [0026] Formal analysis techniques may be used in reasoning about program invariants such as the impossibility of buffer overrun in a program, guaranteed mutual exclusion in an algorithm, deadlock freedom, secrecy in a cryptographic protocol, etc. Such program invariants are provided with a well-defined mathematical meaning. In contrast, in uncovering graphical user interface (GUI) logic flaws may involve reasoning as to what the user sees. Therefore, an “invariant” in a user's vision does not have an immediately obvious mathematical meaning. For example, a visual invariant of the status bar may be that if the user sees the address “foo.com” on a status bar before a mouse click, then it is expected that “click” action navigates to the page “foo.com”. Therefore, a map is performed based on a visual invariant to a program invariant in order to apply formal reasoning. [0027] Mapping between a visual invariant and a program invariant relies on the logic of the GUI implementation - for example, a browser's logic for mouse handling and page loading. An in-depth understanding of the logic or logic “problems” allows the ability to derive the program invariant. The source code of a browser may be studied and browser pseudo code may be implemented to capture such logic. Furthermore, “system state” may be specified, where system state may include the browser's internal state and also the user's memory. The sequence of the user actions may also be considered in understanding GUI logic problems. For example, the user may move and click the mouse, or open a new page, and each action can change the system state. Another factor to specify may be execution context of the system. For example, a web page is an execution context for mouse handling logic. Therefore, the same logic and the same user action when executed on different web pages can produce different results. [0028] In certain exemplary embodiments, the methods described may include mapping a visual invariant, such as “the web site that a user navigates to must be the same as that indicated on the status bar”, to a well-defined program invariant, such as a Boolean condition about user state and software state. The mapping is done based on an in-depth understanding of the source code of the software (e.g., browser software). This can lead to discovering possible inputs to the software which can cause the visual invariant to be violated. In the example of finding status bar spoofing scenarios, a goal may be to discover all HTML document tree structures that can cause the inconsistency between the URL indicated on the status bar and the URL that the browser is navigating to upon a click event; the resulting HTML tree structures can be used to craft instances of status bar spoofing. To systematically derive these scenarios, a formal reasoning tool may be implemented to reason about the well defined program invariant. Exemplary System [0029] FIG. 1 shows an example system 100 that may be implemented to identify GUI logic flaws. The system 100 may be part of a larger system such as developmental station or computing system. The system 100 includes a real world subsystem 102 and developmental or formal world subsystem 104 . The real world subsystem 102 includes one or more real spoofing scenarios 106 , one or more visual invariants 108 , and browser (GUI) source code 110 . The formal world subsystem 104 includes a reasoning engine 112 and one or more potential spoofing scenarios 114 . The reasoning engine 112 further includes system program logic 116 and one or more program invariants 118 . The system program logic 116 includes a user's action sequence 120 , execution context 122 , and system state 124 . [0030] The visual invariant 108 and source code 110 may be first mapped from the real world subsystem 102 to the formal world subsystem 104 by formally specifying them on the reasoning engine 112 . The user action sequence 120 , the execution context 122 , and the system state 124 may also be formally specified. The reasoning engine 112 then performs mechanical reasoning to check whether the user action sequence 120 applied on a system running the system program logic 116 on the execution context 122 violates the program invariant 118 . Each discovered violation is output as a potential spoofing scenario 114 , which consists of the user action sequence 120 , the execution context 122 and the system state 124 or inference steps for the particular spoofing scenario 114 . The particular potential spoofing scenario 114 may then be mapped back to a particular real world spoofing scenario 106 . Mapping back to the particular real world spoofing scenario 106 may include constructing a real web page that sets up the execution context 122 which lures a user to perform the action sequence 120 . Reasoning Engine [0031] In order to uncover GUI logic flaws, a logical framework is implemented which includes the reasoning engine described above. The reasoning engine 112 may be based on “Maude”; however, it will become apparent that other systems and methods may also be implemented, such as theorem provers and model checkers. Maude is described herein as one exemplary implementation. [0032] Below is a simple system specified using Maude: the states of a system are represented by symbolic expressions, and the system transitions are specified by rewrite rules indicating how a state is transformed into another. For example, in order to specify a 24-hour clock marking only the hours, a state constructor operator clock can be declared such that for example, clock( 7 ) and clock( 21 ) are two different clock states. In this example, there is one rewrite rule “ticking” the clock to the next hour. The clock system is specified as follows: [0000] type CLOCK . operator clock : Int -> CLOCK . var T : Int . rule clock(T) => clock((T + 1) rem 24) [0033] In the pseudocode above, Int is a built-in data type of integers, a new type CLOCK of clock states is defined, and the state constructor clock is declared as an operator that takes an Int and produces a CLOCK. The clock “tick” transitions are specified by a rewrite rule introduced with the rule keyword, which rewrites a given clock marking time T to one marking time ((T+1) rem 24 ), that is, the remainder of (T+1) divided by 24. For example, clock( 23 ) will be rewritten to clock( 0 ). [0034] Once a system is specified, Maude's search command can be used to verify invariants. An invariant is a predicate that holds of an initial state and of states reachable from it. For example, if the initial state is clock( 0 ), and the invariant to verify is that the times it marks will always be greater than or equal to 0 and strictly smaller than 24. An invariant is verified by searching for any states violating it, or in other words for states satisfying the negation of the invariant. This can be done with the following search command: search clock( 0 )=>clock(T) such that ((T<0) or (T>=24)) [0036] For complex situations, such as interactions between a user and a browser, formal verification may be needed in practice. As further described below, a system such as Maude may be implemented such that for example, a browser's status bar and address bar logics are specified by rewrite rules by the system (e.g.,Maude), and the search command is used to search for spoofing scenarios. Status Bar Spoofing Based on Static HTML Example [0037] Web attacks, such as browser buffer overruns, cross-site scripting attacks, browser cross-frame attacks and phishing attacks, may “trick” a user to navigate to a malicious universal resource locator (URL). Therefore, the user should know the target URL that is invoked by his actions (i.e., a user mouse click action). As discussed, the status bar is supposed to be a trustworthy information source to display the target URL information; however, the status bar may be spoofed. A status bar spoof is especially damaging if it can be constructed using only static markup language or hypertext markup language (HTML) (i.e., without any active content, such as Java script), because (i) email clients, e.g., Outlook and Outlook Express, render static HTML, and email is an important media to propagate malicious messages; and (ii) blogging sites and social networking sites (e.g., mySpace.com) usually sanitize user-posted contents to remove scripts, but allow static HTML. The following examples reference the use of HTML; however, other markup languages and other programming languages may be implemented. [0038] The following is an example HTML source file as an example representation and the layout of an HTML page: [0000] <html>  <head><title>Page</title></head>  <body>   <a href=“http://microsoft.com”>    <img src=“a.jpg”>  </a>   <button>My button </button>  </body> </html> [0039] FIG. 2(A) shows a document object model tree (DOM) 200 representing the HTML source file. The element <html> 202 represents the HTML file and includes a <head> 204 , <title> 206 , <body> 208 , <a> 210 , <button> 212 , and <img> 214 . The element <html> 202 can be considered as a tree root with the element <head> 204 as a subtree and the element <body> 208 as another subtree. The <body> 208 subtree is rendered in a browser's content area as shown in FIG. 2(B) which shows an element layout 216 . Since status bar spoof is caused by user interaction with the content area, focus is made on the <body> 208 subtree. Conceptually, the elements of the <body> 208 subtree may be represented by the element stack shown in FIG. 2(C) , where the elements are visually stacked upwards towards the user, with <body> 208 sitting at the bottom. In this HTML example, <a> 210 represents an anchor, and <img> 214 represents an image. [0040] For status bar spoofing, mouse handling logic can play an important part. The following describes mouse handling logic. Such logic may be extracted from browser source code (i.e., browser source code 110 ). [0041] A pointing device or mouse can generate several raw messages. When a user moves the mouse onto an element and clicks on the element, the sequence of raw messages can consists of several MOUSEMOVE messages, an LBUTTONDOWN (i.e., left button down) message, and an LBUTTONUP (i.e., left button up) message. [0042] In the following example, core functions for mouse handling are described in the files OnMouseMessage and PumpMessage, which are not element specific. In addition, every element has specific virtual functions such as HandleMessage, DoClick and ClickAction to determine an element's behaviors. [0043] A raw mouse message may invoke an OnMouseMessage function or call as follows: [0000] OnMouseMessage(x,y,message) {  element=HitTestPoint(x,y)  if (element!= elementLastMouseOver)   PumpMessage(MOUSELEAVE,         elementLastMouseOver)  PumpMessage(message, element)  if (element!= elementLastMouseOver)    PumpMessage(MOUSEOVER, element)  elementLastMouseOver = element } [0044] The coordinates of the mouse are (x,y), and message can be either MOUSEMOVE, or LBUTTONDOWN, or LBUTTONUP. First, a HitTestPoint call is made to determine which element (denoted as “element” in the OnMouseMessage call) is immediately under the mouse. If “element” is different from elementLastMouseOver, which is the element immediately under the mouse in the most recent OnMouseMessage call, then a MOUSELEAVE message is pumped (i.e., sent) to elementLastMouseOver. Then the raw message (i.e., message) is pumped to “element”. Finally, if “element” is different from elementLastMouseOver, a MOUSEOVER message is pumped to “element”. [0045] The following describes a “PumpMessage” function or call. [0000] PumpMessage(message,element) {  btn = element.GetAncestor (BUTTON))  if (btn != NULL && message == LBUTTONUP)     element = btn  repeat   BubbleCanceled = loopElement->HandleMessage(message)   loopElement = loopElement->parent  until BubbleCanceled or loopElement is the tree root  if (message == LBUTTONUP)   element->DoClick( )  //handle mouse single click } [0046] In the function PumpMessage, btn is the closest “button ancestor” of “element”. If btn exists and the message is LBUTTONUP (i.e., a click), then “element” becomes the button btn. Any click on a descendant of a button may be treated as a click on the button. [0047] FIG. 3 shows a message bubbling loop 300 that is performed when “element” receives a mouse message. The message bubbling loop 300 begins at “element 3 ” 302 . The virtual function HandleMessage of every element, i.e., “element 3 ” 302 , “element 2 ” 304 , “element 1 ” 306 along the DOM tree path is invoked. Each HandleMessage call can cancel or continue the message bubbling loop 300 (i.e., break out of or continue the message bubbling loop 300 ) by setting a Boolean BubbleCanceled. After the message bubbling loop 300 completes, if a message is LBUTTONUP, the virtual function DoClick of “element” is invoked to handle a mouse click. Status Bar Spoofing Based on Static HTML Example [0048] An object class may be implemented for each type of HTML element, such as “Anchor”, “Form”, “Button”, “InputField”, “Label”, “Image”, etc. These object classes inherit from an AbstractElement base class. Three virtual functions of AbstractElement, in particular HandleMessage, DoClick and ClickAction, may be defined to implement default behaviors of real HTML elements. AbstractElement::DoClick (i.e., function DoClick of AbstractElement) implements a loop to invoke ClickAction of each element along the DOM tree path, similar to the bubbling in PumpMessage. HandleMessage and ClickAction of AbstractElement are considered as “placeholders”, since they simply return in order to continue the bubble. [0049] Each HTML element class can override these virtual functions to implement its specific behaviors. A subset of virtual functions of the “Anchor”, “Label” and “Image” elements are described in the following functions. [0000] Bool Anchor::HandleMessage(message) {  switch (message)  case LBUTTONDOWN    or LBUTTONUP:     return true; //cancel bubble   case MOUSEOVER:     SetStatusText(targetURL)     return false; //continue bubble   Other:     return false;  } Bool Anchor::ClickAction( ) {   FollowHyperlink(targetURL);   return true;  // cancel bubble } Bool Label::HandleMessage(message)  switch (message)   case MOUSEOVER    or MOUSELEAVE:     return true; //cancel bubble   Other:    return false; } Bool Label::ClickAction( ) {  pFor = GetForElement( )  if (pFor != NULL)   pFor->DoClick( );  return true; } Bool Image::HandleMessage(message) {  if a map is associated with this image   MapTarget = GetTargetFromMap( );   switch (message)    case MOUSEOVER:     SetStatusText(MapTarget)     return true;  else ... } Bool Image::ClickAction( ) {  if a Map is associated with this image    MapTarget = GetTargetFromMap( ); FollowHyperlink(MapTarget);  else pAnchor=GetContainingAnchor( );    pAnchor->ClickAction( );  return true; } [0050] The examples above demonstrate the complexity in mouse handling logic due to the intrinsic behavioral diversity of individual elements and the possible compositions. For example, when a mouse is over an anchor, the target URL of the anchor will be displayed on the status bar by calling SetStatusText, and the bubble continues, as indicated in Anchor::HandleMessage. When an anchor is clicked, FollowHyperlink is called to jump to the target URL, and the bubble is canceled, as indicated in Anchor::ClickAction. When the mouse is over a label, there is no SetStatusText call, and the bubble is canceled. According to the HTML specification, a label can be associated with another element in the page, which is called ForElement. Clicking on the label is equivalent to clicking on ForElement, as shown in Label: :ClickAction. An image element can be associated with a map, which specifies different regions on the image with different target URLs. When the mouse is over a region, the URL of the region is set to the status bar, as indicated in Image::HandleMessage. When the mouse clicks on the region, a FollowHyperlink call is made, as indicated in Image::ClickAction. If an image is not associated with a map, then the URL of the containing anchor of the image (i.e., the closest ancestor anchor of the image on the DOM tree) determines the status bar text and the hyperlink to follow Formalization of Status Bar Spoofing [0051] FIG. 4 is a flow diagram 400 shows a user action sequence. In particular, flow diagram 400 illustrates a function level view of status bar spoofing. Several MOUSEMOVE actions 402 ( 1 ) to 402 (N) take place before the mouse stops at coordinate (x n , y n ). A spoof is systematically explored, considering that a web page can be arbitrarily complex and the user's action sequence as shown in the actions 402 in FIG. 4 can be arbitrarily long. Flow diagram 400 particularly illustrates how the function call level view of a status bar spoof is obtained, the browser receives a sequence of MOUSEMOVE messages on coordinates (x 1 ,y 1 ) (x 2 ,y 2 ) . . . (x n ,y n ) (i.e., MOUSEMOVE actions 402 ), a user inspects the status bar and memorizes “benignURL” shown as block 404 . Then, a LBUTTONDOWN and a LBUTTONUP messages are received as shown in block 406 and 408 respectively, resulting in a FollowHyperlink(maliciousURL) call. [0052] An approach is based on “canonicalization”, where canonicalization is a common form of abstraction used in formal reasoning practice to handle a complex problem space. A set of user action sequences is mapped to a single canonical action sequence. Furthermore, a set of web pages is mapped to a single canonical DOM tree. Since any instance in an original problem space may only trivially differ from its canonical form, the canonical space is explored to find “representative” instances. [0053] For example, in order to perform canonicalization of the user action sequence shown in FIG. 4 , the number of “MOUSEMOVE” actions before the mouse stops at (x n , y n ), is n−1. Although n−1 can be arbitrarily large, it can be mapped to a canonical sequence where the value n−1=1 represents the original sequence. Although, a MOUSEMOVE can potentially update the status bar, the status bar is a memory-less object (i.e., a whole sequence of updates on the status bar is equivalent to the latest update before the user inspection). Assuming the update is invoked by a MOUSEMOVE action at (x i , y i ), a canonical action sequence can specified in the following function, using a system such as Maude, where O 1 and O 2 are elements immediately under coordinates (x i , y i ) and (x n , y n ). An Action List (ActionList) or AL can be denoted as [action 1 ; action 2 ; ; action n ]. [0000] operator CanonicalActionSeqence: Element Element -> ActionList . rule CanonicalActionSeqence(O1,O2) =>  [onMouseMessage(O1,MOUSEMOVE); onMouseMessage(O2,MOUSEMOVE) ;    Inspection ; onMouseMessage(O2,LBUTTONDOWN); onMouseMessage(O2,LBUTTONUP)] . DOM Tree Construction [0054] DOM trees are constructed per execution context. Since the canonical action sequence may contain only two MOUSEMOVEs, there may be no need in generating a DOM tree with more than two branches—a third branch would be superfluous as it does not receive any mouse message. In this example, a module in the particular Maude model may be implemented to enumerate all one-branch DOM trees up to four elements and all two-branch DOM trees up to five elements (excluding the tree root <body> element); five elements being the current search space. The DOM trees are considered as canonical DOM trees. An example may include the following HTML element classes: “AbstractElement”, “Anchor”, “Button”, “Form”, “Image”, “InputField” and “Label”. Each particular element has attributes. For example, the following term represents an “Anchor” anchor O, whose parent is O′: <O|class:anchor, parent:O′> [0056] HTML syntax has a set of restrictions for tree structures. For example, an anchor cannot be embedded in another anchor, an image and an input field can only be leaf nodes. Such restrictions may be specified as our tree enumeration rules. System State and State Transitions [0057] A system state includes the variables statusBar and the memorizedURL. State transitions are triggered by SetStatusBar calls and the user's Inspection action as below: [0000] const Inspection : Action . operator SetStatusText : URL -> Action . vars AL : ActionList . vars Url, Url′ : URL . rule [SetStatusBar(Url) ; AL] statusBar(Url′) => [AL] statusBar(Url) . rule [Inspection ; AL] statusBar(Url) memorizedURL(Url′) => [AL] statusBar(Url) memorizedURL(Url) . [0058] In the rules above, SetStatusText and Inspection are actions. “AL” is an arbitrary action list. Concatenating an action and AL using a semicolon also constitutes an action list. The first rule specifies that if the current action list starts with a SetStatusText(Url) call (followed by AL), and the status bar displays URL′, then this call is removed from the action list, and the status bar is updated to Url. This means that after SetStatusText(Url) completes, the status bar is changed to Url. The second rule specifies that if statusBar displays Url and the memorizedURL is Url′, and the action list starts with “Inspection”, then Inspection is removed from the action list, and memorizedURL becomes Url. The semantics of Inspection are to copy statusBar to the user's memory (i.e., memorizedURL). Modeling the Pseudo Code [0059] The above described function or calls OnMouseMessage, PumpMessage, and the virtual functions of the “Anchor”, “Label” and “Image” are typically a basic capability for most existing program analysis tools, because such functions contain only assignments, “if” statements, and loops with simple termination conditions, etc. Semantics of these program constructs may be implemented through Maude. The following are rules to specify HandleMessage and ClickAction of the Anchor element. vars M: Message O: Element AL:ActionList. [0000] Rule 1 rule [AnchorHandleMessage(O,M) ; AL]  /*** rule 1 ***/  => [cancelBubble ; AL]   If M == LBUTTONUP or M == LBUTTONDOWN. Rule 2 rule [AnchorHandleMessage(O,M) ; AL] < O | targetURL: Url , ...>  => [setStatusText(Url) ; AL] < O | targetURL: Url , ... >   if M == MOUSEOVER .    /*** rule 2 ***/ Rule 3 rule [AnchorHandleMessage(O,M) ; AL] /*** rule 3 ***/  => [no-op ; AL] if M is not LBUTTONUP, LBUTTONDOWN or MOUSEOVER . Rule 4 rule [AnchorClickAction(O) ; AL] < O | targetURL: Url , ... >  => [FollowHyperlink(Url) ; cancelBubble ; AL]    < O | targetURL: Url , ... >.  /*** rule 4 ***/ [0060] Rule 1 specifies that if an action list or AL starts with a AnchorHandleMessage(M,O) call, this call should rewrite to a cancelBubble, if M is LBUTTONUP or LBUTTONDOWN. Rule 2 specifies that if M is a MOUSEOVER, AnchorHandleMessage(M,O) should rewrite to setStatusText(Url), where Url is the target URL of the anchor. For any other type of message M, AnchorHandleMessage(M,O) should rewrite to no-op to continue the bubble, which is specified by rule 3 . Rule 4 rewrites AnchorClickAction(O) to the concatenation of FollowHyperlink(Url) and cancelBubble, where Url is the target URL of the anchor. Other elements may be modeled by similar such rules. The Program Invariant [0061] The program invariant to find spoofs is specified by the following “search” command: [0000] const maliciousUrl , benignUrl , empty : URL. vars O1, O2: Element Url: URL AL: ActionList . search CanonicalActionSequence(O1,O2)    statusBar(empty)    memorizedUrl(empty)  => [FollowHyperlink(maliciousUrl) ;    AL] statusBar(Url) memorizedUrl(benignUrl) . [0062] The above invariant provides a well-defined mathematical meaning to status bar spoof: “the initial term CanonicalActionSequence(O 1 ,O 2 ) statusBar(empty) memorizedurl(empty) can rewrite to the term [FollowHyperlink(maliciousUrl) ; AL] statusBar(Url) memorizedUrl(benignUrl)”, which indicates that the user memorizes benignURL, but FollowHyperlink(maliciousUrl) is the next action to be performed by the browser. Spoofing Scenarios Suggested by the Results [0063] FIG. 5 shows examples of DOM trees 500 . In particular, DOM trees 500 ( 1 ) to 500 ( 8 ) are example DOM tree structures that may be output in by the search command described above. The element <body> 502 is the root of the DOM trees 500 and may have one or more of the following leaves: <a> 504 , <form> 506 , <button> 504 , <input field> 510 , <img> 512 , and <label> 514 . [0064] The following function describes DOM tree 500 ( 2 ): [0000] <form action=“http://foo.com/” >  <a href=“http://microsoft.com”>   <input type=“image” src=“faked.jpg”>  </a> </form> [0065] FIG. 6 shows a graphical representation of DOM trees. In specific, 600 ( 1 ) represents DOM tree 500 ( 2 ); 600 ( 2 ) represents DOM tree 500 ( 3 ); and 600 ( 3 ) represents DOM tree 500 ( 4 ). In particular, the elements “input field” 602 , “anchor” 604 , “form” 606 , “img” 608 , “button” 610 , “label” 614 are illustrated. A graphical icon in the form of a mouse arrow 614 is shown. [0066] The scenario of DOM tree 500 ( 2 ) is represented by the following function: [0000] <form action=“http://foo.com/” >  <a href=“http://microsoft.com”>   <input type=“image” src=“faked.jpg”>  </a> </form> [0067] The scenario DOM tree 500 ( 2 ) has an input field which is a picture faked.jpg visually identical to an underlined text “http://microsoft.com”. When the mouse is over it, the HandleMessage of each element is called to handle the MOUSEOVER message that bubbles up to the DOM tree root. Only the anchor's HandleMessage writes its target URL microsoft.com to the status bar, but when the input field is clicked, its ClickAction method retrieves the target URL from the form element, which is foo.com. [0068] The scenario of DOM tree 500 ( 3 ) is represented by the following function: [0000] <form action=“http://foo.com/” >  <button type=submit>   <img src=“faked_link.jpg” USEMAP= “msft1”>  </button> </form> [0069] The scenario of DOM tree 500 ( 3 ) is different than that of the scenario of DOM tree 500 ( 2 ). An <img> element is associated with a map “msftIl”, and is on top of a button. The target URL of “msftl” is set to “http://microsoft.com”. When <img> gets a MOUSEOVER, it sets the status bar to microsoft.com and cancels the bubble. When the mouse is clicked on <img> , because <img> is a child of <button> , the click is treated as a click on the button, according to the implementation of PumpMessage( ). The button click leads to a navigation to foo.com [0070] The scenario of DOM tree 500 ( 4 ) contains a label embedded in an anchor as shown in 600 ( 3 ). When the mouse is moved toward the label, it must first pass over the anchor, and thus sets microsoft.com 616 on the status bar. When the label is clicked, the page is navigated to foo.com 618 , because the label is associated with an anchor 604 of foo.com 618 . An opposite scenario is shown 600 ( 4 ). Graphical representation 600 ( 4 ) shows an HTML page to lure a user to move over an image (child) and click on the label (parent). The <img> is associated with a map that sets microsoft.com 616 to the status bar when the mouse 614 is over it. Note that because HTML syntax only allows an image to be a leaf node, the parent-child relation in this example is mandatory. Therefore scenario 500 ( 4 ) and 500 ( 5 ) are significantly different. [0071] The scenarios of DOM trees 500 ( 6 ), 500 ( 7 ), and 500 ( 8 ) further illustrate varieties of DOM trees and layout arrangements that can be utilized in spoofing. For example DOM tree 500 ( 6 ) two leafs <a> 504 and <label> 514 side-by-side; DOM tree 500 ( 8 ) can implement a structure similar to Cascading Style Sheets (CSS). Address Bar Spoofing [0072] Address bar spoofing is another serious GUI logic flaw which can fool users to trust a current page when it comes from an un-trusted source. When combined with a status bar spoof, this becomes a powerful security threat. [0073] FIG. 7 shows webpage 700 in which multiple frames are hosted. In particular, a browser 702 displays a page from an address http://MySite. A browser process can create multiple browsers, where each browser is implemented as a thread. A browser may be built on the Object Linking and Embedding or OLE framework, in which the browser is a container (including a title bar, an address bar, a status bar, etc) hosting a client document in the content area. [0074] When a client document is of an HTML format, it may be called a trident object 704 . A trident 704 can host multiple frames, each displaying an HTML page downloaded from a URL. An HTML page is stored as a markup data structure. A markup consists of the URL and the DOM tree of the content from the URL. The top level frame or the frame associated with the entire content area is called the primary frame 706 of the trident 704 . In particular, in this example, the trident 704 has three frames: the primary frame or top level frame 706 ; a frame 708 from PayPal.com and frame 710 from MSN.com. Each of the frames 706 , 708 , and 710 is associated with a current markup and, during the navigation time, a pending markup. Upon navigation completion, the pending markup is switched in and becomes the current markup. Informally, the program invariant of the address bar correctness is that: ( 1 ) the content area is rendered according to the current markup of primary frame 706 , and ( 2 ) the URL on the address bar is the URL of the current markup of primary frame 706 . Overview of the Logic of HTML Navigation [0075] Using HTML as example, HTML navigation can consist of multiple tasks, such as loading HTML content, switching markup, completing navigation and rendering a page. A trident, such as trident 704 , can have an event queue to schedule such tasks. The event queue has a mechanism for handling events asynchronously, so that the browser is not blocked to wait for the completion of the entire navigation. [0076] Different types of navigation may be studied. The following three examples of navigation are discussed: (1) loading a page into the current trident; (2) traveling in the history of the current trident; and (3) opening a page in a new trident. [0077] FIG. 8 shows an event sequence 800 of loading a page in a current trident. The event sequence includes an event queue 802 . The event sequence 800 is initiated by a FollowHyperlink command 804 , which posts a start navigation event 806 in the event queue 802 . A function PostMan 808 is responsible for downloading new HTML content to a pending markup. Event ready 810 is posted to invoke Markup::Setlnteractive 812 , to make the downloaded contents effective. Markup::SetInteractive 812 first invokes Frame::SwitchMarkup 814 to replace the current markup with the pending markup, and then calls NavigationComplete 816 . If the downloaded markup belongs to a primaryFrame, a function SetAddressBar 818 is invoked to update its address bar. An Ensure 820 event is posted by Frame::SwitchMarkup 814 , which invokes View::EnsureView 822 to construct a View structure containing element layouts derived from the current markup of the primaryFrame. An operating system or OS may periodically post an OnPaint 824 event to paint the content area by calling View::RenderView 826 . [0078] FIG. 9 shows a flow diagram of an event sequence 900 of a history travel. History_Back 902 and Travel 904 look up a history log or call Load History 906 to initialize the navigation (i.e., posts to start navigation event 806 ). PostMan 808 , in this case, loads HTML contents from a persistent storage in local storage (e.g., a hard disk), rather than from the Internet. The remaining portion of the sequence is similar to the sequence of loading a new page. [0079] FIG. 10 shows a flow diagram of an event sequence 1000 of loading a new page into a new trident. WindowOpen 1002 is the starting point. WindowOpen 1002 calls the function CreatePendingDocObject 1004 to create a new trident (i.e., CreateTrident 1006 ). CreatePendingDocObject 1004 then calls SetClientSite 1008 . SetClientSite 1008 prepares a number of Boolean flags as the properties of the new trident, and calls InitDocHost 1010 to associate the trident with the browser (i.e., the container). The new trident at this moment is still empty. The Start Loading 1012 event invokes LoadDocument 1014 which first calls SetAddressBar 845 to set the address bar and then calls Load 1016 which calls LoadFromlnfo 1018 . CreateMarkup 1020 and SwitchMarkup 1022 are called from LoadFromlnfo 1018 before posting a download-content 1024 event to download the actual content for the newly created markup. The function PostMan 808 does the downloading as above. The remaining of the sequence 1000 is similar to event sequences 800 and 900 . Formalization of the Navigation Behaviors [0080] The following looks at modeling the system and system state. Because an address bar spoofing is by definition the inconsistency between the address bar and the content area of the same browser, “spoofability” is a property of the logic of a single browser; however, this does not mean that only one browser is allowed in a spoofing scenario. In other words, there can be other browsers to create a hostile execution context to trigger a logic flaw in one particular browser. Nevertheless, in this example, it is only needed to model the system as one browser and prove its logical correctness (or uncover its flaws), and model other browsers as part of the execution context. [0081] A system state of a browser includes the URL displayed in the address bar, the URL of the View in the content area, a travel log, and the primary frame. For the Maude system and language, a set of Frames and a set of Markups are further defined. For example, if Markup m 1 is downloaded from URL u 1 , and it is the currentMarkup of frame f 1 , where f 1 and u 1 can be specified as: [0000] <f1 | currentMarkup: m1, pendingMarkup: ...> <m1 | URL: u1, frame: f1, ...> [0082] A system state may also include a function call queue and an event queue. The function call queue may be denoted as [call 1 ; call 2 ; . . . ; call n .], and the event queue may be denoted as {event 1 ; event 2 ; . . . ; event n }. [0083] Boolean flags can affect the execution path, where such Boolean flags constitute an execution context of the system. Rules may be defined to assign both true and false values to the Boolean flags. Therefore the search command explores both paths at each branch in the pseudo code. The assignments of the Boolean flags, combined with the function call sequence, constitute a potential spoofing scenario. These may include false positive scenarios, as discussed above in reference to FIG. 1 , the mapping a potential spoofing scenario back to the real world is of value. [0084] Three types of actions are shown in FIGS. 8 , 9 , and 10 : calling a function, invoking an event handler, and posting an event. A function call is implemented as a term substitution in the function call queue. For example, the function call SetInteractive is specified by the following rule, where F is the frame of Markup M, and SetInteractive(F) can conditionally rewrite to SwitchMarkup(M,F) (if BOOLEXP 1 is false) followed by NavigationComplete(F) (if BOOLEXP 2 is true). The following is pseudo code and a rewrite rule of the function call SetInteractive. MARKUP::Setlnteractive( ) { if (BOOLEXP 1 ) return; this−> frame−>SwitchMarkup(this); if (BOOLEXP 2 ) NavigationComplete(frame) }var F: Frame M: Markup FQ: FunctionQueue rule [Setlnteractive(M) ; FQ]<M |frame: F, . . . > => [(if BOOLEXP 1 ≠true then SwitchMarkup(M,F) else noop fi); (if BOOLEXP 2 ==true then NavigationComplete(F) else noop fi); FQ]<M |frame: F, . . . > [0094] Posting of an event happens by appending the event to the event queue, for example, the function FollowHyperlink as shown below, is specified by removing itself from the function queue and adding a startNavigation event to the end of the event queue. var U:Url F:Frame FQ: FunctionQueue EQ: EventQueue rule [FollowHyperlink(U, F); FQ] {EQ } =>[FQ]{EQ; startNavigation(U, F) }. [0098] Another type of action is the invocation of an event handler. An event can be invoked when its previous event handler returns. To model this restriction, a rule of an event handler invocation specifies that the first event in the event queue can be dequeued and translated into a function call when the function call queue is empty. Below is a rule to specify the handling of the ready event, which invokes the handler SetInteractive. [0000] var EQ: EventQueue  rule [empty] { ready(M) ; EQ }  => [SetInteractive(M)] { EQ } [0099] To model address bar correctness a program invariant is provided, where the program invariant of the address bar is defined by the following rule: [0000] vars U: URL F: Frame M: Markup  rule goodState (addressBar(U) urlOfView(U) urlPaintedOnScreen(U) primaryFrame(F)    < F | currentMarkup: M , ...> < M | url: U , ...>)  => true . [0100] According to the definition of this rule, a good state is a state where the URL on the address bar matches the URL of the view and is also the URL of the content which is painted on a screen. Furthermore, the URL is the URL of the currentMarkup of the primaryFrame. Therefore, a spoofing state (defined as “not goodstate”) is one where there is a mismatch between any of these URLs. [0101] As to an initial system state, the search command can start from the following rule initialState: [0000] const f1: Frame m0: Markup url0: URL empty: EventQueue  rule initialState  => { empty } [ empty ]    primaryFrame(f1) < f1 | currentMarkup: m0 ,    pendingMarkup: nil > < m0 | url: url0 , frame: f1 >    addressBar(url0) urlOfView(url0) urlPaintedOnScreen(url0) . [0102] In this initial system state, both the event queue and the function call queue are empty; the primaryFrame is f 1 ; the currentMarkup of f 1 is m( ); the pendingMarkup of f 1 is uninitialized; m( ) is downloaded from URL( ); the address bar displays URL( ); the View is derived from URL( ); and the View is painted on the screen. [0103] As to a user action sequence, in the scenario of an address bar spoofing, the user's action is to access an untrusted HTML page. The page can contain a Java script calling the following navigation functions: FollowHyperlink, HistoryBack and/or WindowOpen. The behavior of the Java script is modeled by a rule that conditionally appends a navigation function to the function list. Each function generates a sequence of events as specified by the function semantics. In the case of Maude or other modeling system and language, all possibilities of interleaving event sequences can be exhaustively searched, because Maude explores all viable rewrite orders. Potential Spoofing Scenarios in the Results [0104] The search command described above can be used to find all execution paths in the model that start with the initial state and finish in a bad state. The search may be performed on two interleaving sequences, for example two FollowHyperlinks; two History_Backs; one FollowHyperlink with one History_Back; and one WindowOpen with one FollowHyperlink. [0105] FIG. 11 shows a table 1100 of various locations and conditions. Table 1100 includes a column identified by a heading number 1102 , a column identified by a heading location 1104 , and a column identified by a heading condition 1106 . The 18 example entries 1108 ( 1 ) to 1108 ( 18 ) may be suggested in one execution context of a potential spoofing scenario suggested in Maude or similar model. Certain function names in the location column 1104 are shown in FIGS. 8 , 9 , and 10 ; however, a model can be more detailed and include numerous functions. [0106] Table 1100 provides a roadmap for a systematic investigation by firstly verifying that when each of the conditions 1106 is manually set to true in the corresponding location using a debugger, the real browser executable will be forced to take an execution path leading to a stable bad state. Therefore, an investigation is focused on these conditions. Secondly other conditions that are present in the pseudo code are not listed in table 1100 , e.g., those in SwitchMarkup, LoadHistory and CreateTrident, since search result may have excluded them from being potential spoofing conditions. [0107] The following describes entries 1108 ( 2 ), 1108 ( 9 ), 1108 ( 11 ), and 1108 ( 18 ) as examples in constructing real spoofing scenarios. Scenarios based on entries 1108 ( 2 ) and 1108 ( 9 ), and their conditions 1106 may be considered entries based on silent return conditions. Function call traces associated with the conditions of entry 1108 ( 2 ) (i.e. GetPFD(url)=NULL) and entry 1108 ( 9 ) (i.e. CurrentURL=NULL) indicate similar scenarios: there are silent-return conditions along a call stack of an address bar update. If any one of these conditions is true, the address bar will remain unchanged, but the content area will be updated. Therefore, if the script first loads “paypal.com” and then loads “evil.com” that triggers the condition, the user will see “paypal.com” on the address bar and the content area from evil.com. [0108] The condition of entries 1108 ( 2 ) and 1108 ( 9 ) may be true when the URL of the page is of a certain special format. In each case, the function cannot handle the special URL, but instead of asserting the negation of the condition, the function silently returns when the condition is encountered. These two examples demonstrate a challenge in addressing atomicity in graphical interface design—once the pending markup is switched in, the address bar update should succeed. No “silent return” is allowed. Even in a situation where the atomicity is too difficult to guarantee, at the least there should be an assertion to halt the browser. [0109] Entry 1108 ( 11 ) is a scenario based on a race condition. The condition of entry 1108 ( 11 ) is associated with a function call trace which indicates a situation where two frames co-exist in a trident and compete to be the primary frame. FIG. 12 shows a flow diagram this scenario. [0110] The malicious script first loads a page 1204 from https://evil.com 1206 which is a phishing page. Then it intentionally loads an error page 1208 in order to make condition of entry 1108 ( 11 ) true when LoadHistory( ) is called later. The race condition is exploited at time t 1210 , where two navigations 1212 and 1214 start at the same time. The following event sequence results in a spoof: (1) the trident starts to navigate 1216 to https://paypal.com 1218 . At this moment, the primary frame is 1220 ; (2) the trident starts to travel back in the history log 1222 . Because condition of entry 1108 ( 11 ) is true, i.e., HTMLDoc=NULL, a new frame 1204 is created as the primary frame. This behavior is according to the logic of LoadHistory( ); (3) the markup of https://evil.com 1206 in the history log 1222 is switched in to frame 1204 ; (4) illustrated by 1202 , an address bar update is made to put https://evil.com 1206 onto the address bar; (5) the downloading of the https://paypal.com page is completed, so its markup is switched into the frame 1220 , where the frame 1220 is not the primary frame any more and will not be rendered in the content area; (6) the address bar is updated to https://www.paypal.com 1218 despite the fact that the frame 1220 is no longer the primary frame. When all these 6 events of the preceding event sequence, occur in such an order, the user sees http://www.paypal.com on the address bar, but the evil.com page 1204 in the content area. A secure socket layer (SSL) certificate may also be spoofed in this situation. [0111] This race condition of entry 1108 ( 11 ) can be exploited in various existing browsers and their particular versions, and succeeds with a high probability; however the race condition may not succeed in every trial because event (5) and event (6) may occur before event (3) and event (4), in which case the users sees the evil.com page 1204 with https://evil.com 1206 on the address bar. [0112] Scenario based on the condition of entry 1108 ( 18 ) (i.e., condition is a hostile environment) is described as follows. The conditions of entries 1108 ( 2 ) and 1108 ( 9 ) 2 exploit the failure of the address bar update, and condition of entry 1108 ( 18 ) targets the failure of the content area update. This scenario depends on the condition of entry 1108 ( 18 ) (i.e., RSFC=NULL). This can be true when a malicious script creates a hostile execution environment and launches a browser. As a result, the user will see for example, “http://cnn.com” (i.e., a correct URL) displayed on the address bar and the content from https://evil.com (i.e., a malicious URL) remaining in the content area. Similar to the scenarios described above, this scenario demonstrates the importance of atomicity in graphical interface implementations. In addition to the correctness of the internal logic of a browser, this spoofing scenario emphasizes the resilience against a hostile execution environment. Exemplary Methods [0113] Exemplary methods for uncovering GUI logic flaws are described with reference to FIGS. 1 to 12 . These exemplary methods may be described in the general context of computer executable instructions. Generally, computer executable instructions can include routines, programs, objects, components, data structures, procedures, modules, functions, and the like that perform particular functions or implement particular abstract data types. The methods may also be practiced in a distributed computing environment where functions are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, computer executable instructions may be located in both local and remote computer storage media, including memory storage devices. [0114] FIG. 13 illustrates an exemplary method 1300 for uncovering logic flaws as to a graphical user interface. The order in which the method is described is not intended to be construed as a limitation, and any number of the described method blocks can be combined in any order to implement the method, or an alternate method. Additionally, individual blocks may be deleted from the method without departing from the spirit and scope of the subject matter described herein. Furthermore, the method can be implemented in any suitable hardware, software, firmware, or combination thereof. [0115] At block 1302 , mapping is performed with a visual invariant to a program invariant. The visual variant is an object that is seen by a user, such as a page or website, or an element (object) in the page or website, an address that is presented on an address bar, etc. The program invariant is a well defined program invariant. Examples of program invariants include Boolean conditions about user state and software state. The program invariant may be further found in a logic or software of an interface (e.g. GUI) that includes the program invariant, where the program invariant relies on the logic (software) of the interface's implementation. For example, a browser's logic for mouse handling and page loading. [0116] At block 1304 , discovering is performed as to possible inputs to the logic or software which can cause the visual invariant to be violated. In an embodiment, the discovering includes all document object model tree structures that can cause the inconsistency between an address (URL) indicated on a status bar and the URL that a browser is navigating to upon a click event, where the resulting tree structures can be used to craft instances of status bar spoofing. Also, as discussed above, instances of address bar spoofing may also be crafted. [0117] At block 1306 , initiating an action sequence is performed, where discovering performed at block 1304 is directed to the action sequence. The action sequence may be a canonical action sequence as described above, and the tree structures in bock 1304 may be canonical DOM trees. [0118] FIG. 14 illustrates an exemplary method 1400 for discovering status bar or address bar spoofs. The order in which the method is described is not intended to be construed as a limitation, and any number of the described method blocks can be combined in any order to implement the method, or an alternate method. Additionally, individual blocks may be deleted from the method without departing from the spirit and scope of the subject matter described herein. Furthermore, the method can be implemented in any suitable hardware, software, firmware, or combination thereof. [0119] The techniques described above illustrate that status bar logic can be systematically explored. As discussed, the Maude model, system and language is one tool; however, the there are other tools, languages, and models that may be implemented. For example, a model checker, a theorem prover, and a binary code instrumentation tool may be implemented, such as “Detours”. [0120] The basic idea is that since a program invariant is known, and it is also known how to generate canonical user action sequences and canonical DOM trees, it is possible to generate real canonical HTML pages and pump real mouse messages to test the real browser status bar implementation. [0121] The advantage of an automated approach is that it does not require manual modeling of the behaviors of each element (e.g., HTML element), and therefore the process of redoing the model (i.e., remodeling) for different patch levels of the browser can be eliminated. Furthermore, the automated approach can allow the ability to find all spoofs known from any previous modeling. [0122] At block 1402 , generating of real pages (e.g., web pages written in HTML) is performed. Such real pages may be comprised of canonical DOM trees. The canonical DOM trees may further be stored in memory such as a hard disk. [0123] At block 1404 , loading of each page is performed by a browser, where an action sequence performed by the browser. The action sequence may be a canonical user action pumped by calling a routine, such as OnMouseMessage described above. [0124] At block 1406 , checking for spoofs is performed. The checking may done by intercepting the calls SetStatusText and FollowHyperlink described above. [0125] At block 1408 , block 1404 may be repeated for a next page. Exemplary Computer Environment [0126] FIG. 15 illustrates an exemplary general computer environment, which can be used to implement the techniques described herein, and which may be representative, in whole or in part, of elements described herein. The computer environment FIG. 15 is only one example of a computing environment and is not intended to suggest any limitation as to the scope of use or functionality of the computer and network architectures. Neither should the computer environment FIG. 15 be interpreted as having any dependency or requirement relating to any one or combination of components illustrated in the example computer environment FIG. 15 . [0127] Computer environment FIG. 15 includes a general-purpose computing-based device in the form of a computer FIG. 15 . Computer FIG. 15 can be, for example, a desktop computer, a handheld computer, a notebook or laptop computer, a server computer, a game console, and so on. The components of computer FIG. 15 can include, but are not limited to, one or more processors or processing units FIG. 15 , a system memory FIG. 15 , and a system bus FIG. 15 that couples various system components including the processor FIG. 15 to the system memory FIG. 15 . [0128] The system bus FIG. 15 represents one or more of any of several types of bus structures, including a memory bus or memory controller, a peripheral bus, an accelerated graphics port, and a processor or local bus using any of a variety of bus architectures. By way of example, such architectures can include an Industry Standard Architecture (ISA) bus, a Micro Channel Architecture (MCA) bus, an Enhanced ISA (EISA) bus, a Video Electronics Standards Association (VESA) local bus, and a Peripheral Component Interconnects (PCI) bus also known as a Mezzanine bus. [0129] Computer FIG. 15 typically includes a variety of computer readable media. Such media can be any available media that is accessible by computer FIG. 15 and includes both volatile and non-volatile media, removable and non-removable media. [0130] The system memory FIG. 15 includes computer readable media in the form of volatile memory, such as random access memory (RAM) FIG. 15 , and/or non-volatile memory, such as read only memory (ROM) FIG. 15 . A basic input/output system (BIOS) FIG. 15 , containing the basic routines that help to transfer information between elements within computer FIG. 15 , such as during start-up, is stored in ROM FIG. 15 . RAM FIG. 15 typically contains data and/or program modules that are immediately accessible to and/or presently operated on by the processing unit FIG. 15 . [0131] Computer FIG. 15 may also include other removable/non-removable, volatile/non-volatile computer storage media. By way of example, Fig FIG. 15 illustrates a hard disk drive FIG. 15 for reading from and writing to a non-removable, non-volatile magnetic media (not shown), a magnetic disk drive FIG. 15 for reading from and writing to a removable, non-volatile magnetic disk FIG. 15 (e.g., a “floppy disk”), and an optical disk drive FIG. 15 for reading from and/or writing to a removable, non-volatile optical disk FIG. 15 such as a CD-ROM, DVD-ROM, or other optical media. The hard disk drive FIG. 15 , magnetic disk drive FIG. 15 , and optical disk drive FIG. 15 are each connected to the system bus FIG. 15 by one or more data media interfaces FIG. 15 . Alternately, the hard disk drive FIG. 15 , magnetic disk drive FIG. 15 , and optical disk drive FIG. 15 can be connected to the system bus FIG. 15 by one or more interfaces (not shown). [0132] The disk drives and their associated computer-readable media provide non-volatile storage of computer readable instructions, data structures, program modules, and other data for computer FIG. 15 . Although the example illustrates a hard disk FIG. 15 , a removable magnetic disk FIG. 15 , and a removable optical disk FIG. 15 , it is to be appreciated that other types of computer readable media which can store data that is accessible by a computer, such as magnetic cassettes or other magnetic storage devices, flash memory cards, CD-ROM, digital versatile disks (DVD) or other optical storage, random access memories (RAM), read only memories (ROM), electrically erasable programmable read-only memory (EEPROM), and the like, can also be utilized to implement the exemplary computing system and environment. [0133] Any number of program modules can be stored on the hard disk FIG. 15 , magnetic disk FIG. 15 , optical disk FIG. 15 , ROM FIG. 15 , and/or RAM FIG. 15 , including by way of example, an operating system FIG. 15 , one or more application programs FIG. 15 , other program modules FIG. 15 , and program data FIG. 15 . Each of such operating system FIG. 15 , one or more application programs FIG. 15 , other program modules FIG. 15 , and program data FIG. 15 (or some combination thereof) may implement all or part of the resident components that support the distributed file system. [0134] A user can enter commands and information into computer FIG. 15 via input devices such as a keyboard FIG. 15 and a pointing device FIG. 15 (e.g., a “mouse”). Other input devices FIG. 15 (not shown specifically) may include a microphone, joystick, game pad, satellite dish, serial port, scanner, and/or the like. These and other input devices are connected to the processing unit 1504 via input/output interfaces FIG. 15 that are coupled to the system bus FIG. 15 , but may be connected by other interface and bus structures, such as a parallel port, game port, or a universal serial bus (USB). [0135] A monitor FIG. 15 or other type of display device can also be connected to the system bus FIG. 15 via an interface, such as a video adapter FIG. 15 . In addition to the monitor FIG. 15 , other output peripheral devices can include components such as speakers (not shown) and a printer FIG. 15 which can be connected to computer FIG. 15 via the input/output interfaces FIG. 15 . [0136] Computer FIG. 15 can operate in a networked environment using logical connections to one or more remote computers, such as a remote computing-based device FIG. 15 . By way of example, the remote computing-based device FIG. 15 can be a personal computer, portable computer, a server, a router, a network computer, a peer device or other common network node, and the like. The remote computing-based device FIG. 15 is illustrated as a portable computer that can include many or all of the elements and features described herein relative to computer FIG. 15 . [0137] Logical connections between computer FIG. 15 and the remote computer FIG. 15 are depicted as a local area network (LAN) FIG. 15 and a general wide area network (WAN) FIG. 15 . Such networking environments are commonplace in offices, enterprise-wide computer networks, intranets, and the Internet. [0138] When implemented in a LAN networking environment, the computer FIG. 15 is connected to a local network FIG. 15 via a network interface or adapter FIG. 15 . When implemented in a WAN networking environment, the computer FIG. 15 typically includes a modem FIG. 15 or other means for establishing communications over the wide network FIG. 15 . The modem FIG. 15 , which can be internal or external to computer FIG. 15 , can be connected to the system bus FIG. 15 via the input/output interfaces FIG. 15 or other appropriate mechanisms. It is to be appreciated that the illustrated network connections are exemplary and that other means of establishing communication link(s) between the computers FIG. 15 and FIG. 15 can be employed. [0139] In a networked environment, such as that illustrated with computing environment FIG. 15 , program modules depicted relative to the computer FIG. 15 , or portions thereof, may be stored in a remote memory storage device. By way of example, remote application programs FIG. 15 reside on a memory device of remote computer FIG. 15 . For purposes of illustration, application programs and other executable program components such as the operating system are illustrated herein as discrete blocks, although it is recognized that such programs and components reside at various times in different storage components of the computing-based device FIG. 15 , and are executed by the data processor(s) of the computer. [0140] Various modules and techniques may be described herein in the general context of computer-executable instructions, such as program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc. that performs particular tasks or implement particular abstract data types. Typically, the functionality of the program modules may be combined or distributed as desired in various embodiments. [0141] An implementation of these modules and techniques may be stored on or transmitted across some form of computer readable media. Computer readable media can be any available media that can be accessed by a computer. By way of example, and not limitation, computer readable media may comprise “computer storage media” and “communications media.” [0142] “Computer storage media” includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules, or other data. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by a computer. [0143] Alternately, portions of the framework may be implemented in hardware or a combination of hardware, software, and/or firmware. For example, one or more application specific integrated circuits (ASICs) or programmable logic devices (PLDs) could be designed or programmed to implement one or more portions of the framework. CONCLUSION [0144] The above-described methods and system describe simplified concepts of uncovering logic flaws in graphical user interface. Although the invention has been described in language specific to structural features and/or methodological acts, it is to be understood that the invention defined in the appended claims is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as exemplary forms of implementing the claimed invention.

To achieve end-to-end security, traditional machine-to-machine security measures are insufficient if the integrity of the graphical user interface (GUI) is compromised. GUI logic flaws are a category of software vulnerabilities that result from logic flaws in GUI implementation. The invention described here is a technology for uncovering these flaws using a systematic reasoning approach. Major steps in the technology include: (1) mapping a visual invariant to a program invariant; (2) formally modeling the program logic, the user actions and the execution context, and systematically exploring the possibilities of violations of the program invariant; (3) finding real spoofing attacks based on the exploration.

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2016-017959 filed Feb. 2, 2016. BACKGROUND Technical Field [0002] The present invention relates to an image forming apparatus. SUMMARY [0003] According to an aspect of the invention, there is provided an image forming apparatus including a cover member that opens and closes an opening formed in an image forming apparatus body, a unit that is removable from the image forming apparatus body through the opening, a latch member that is included in the unit in such a manner as to be capable of rotating about a rotation fulcrum portion, the latch member including a hook that is to be latched onto a to-be-latched portion of the image forming apparatus body from a downstream side in a mounting direction of the unit and that fixes the unit onto the image forming apparatus body and an operating portion that is disposed so as to oppose the hook across the rotation fulcrum portion and that is capable of being operated through the opening, and a hindering portion that is included in the cover member and that interferes, when the hook rotates in a direction in which the hook is separated from the to-be-latched portion in a state where the cover member closes the opening, with the operating portion and hinders the hook from rotating in the direction in which the hook is separated from the to-be-latched portion. BRIEF DESCRIPTION OF THE DRAWINGS [0004] An exemplary embodiment of the present invention will be described in detail based on the following figures, wherein: [0005] FIG. 1 is a schematic side view illustrating the overall configuration of an image forming apparatus according to an exemplary embodiment of the present invention; [0006] FIG. 2 is a schematic perspective view of a fixing unit of the image forming apparatus according to the exemplary embodiment; [0007] FIG. 3 is a schematic side view of the fixing unit that is mounted in and fixed to the image forming apparatus according to the exemplary embodiment; [0008] FIG. 4 is a schematic enlarged side view of a mounting and unmounting mechanism included in the fixing unit of the image forming apparatus according to the exemplary embodiment; [0009] FIG. 5 is a schematic enlarged side view of a portion of a latch member included in the mounting and unmounting mechanism of the fixing unit of the image forming apparatus according to the exemplary embodiment, the portion being on the side on which a hook is present; [0010] FIG. 6 is a schematic side view illustrating a state where the hook of the latch member is not separated from a to-be-latched portion even though an external force has acted on the image forming apparatus according to the exemplary embodiment; and [0011] FIG. 7 is a schematic side view illustrating a state where a cover member is not closed when the fixing unit of the image forming apparatus according to the exemplary embodiment is not completely mounted in the image forming apparatus body. DETAILED DESCRIPTION [0012] An exemplary embodiment of the present invention will be described in detail below with reference to the drawings. Note that, for convenience of description, arrow UP and arrow FR that are suitably illustrated in the drawings respectively indicate an upward direction and a forward direction of an image forming apparatus 10 . In addition, a direction toward the front side as viewed in FIG. 1 is a left direction of the image forming apparatus 10 , and the term “when seen from the side” refers to the case of seeing from a left-right direction that is perpendicular to a mounting (inserting) direction of a fixing unit 70 , which will be described later. [0013] As illustrated in FIG. 1 , an image processing unit 16 that performs image processing on image data, which is input, is disposed in the interior of an image forming apparatus body (hereinafter simply referred to as apparatus body) 12 , which serves as a housing of the image forming apparatus 10 . The image processing unit 16 processes image data, which has been input, into gradation data items of four colors of yellow (Y), magenta (M), cyan (C), and black (K), and an exposure device 18 that receives the processed gradation data items and performs image exposure by using laser beams L is disposed in a central area inside the apparatus body 12 . [0014] Four image forming units 20 Y, 20 M, 20 C, and 20 K, which respectively correspond to the colors Y, M, C, and K, are disposed above the exposure device 18 in such a manner as to be spaced apart from one another in a direction inclined with respect to the horizontal direction and are removable from the apparatus body 12 . Note that, in the following description, when it is not necessary to describe the image forming units 20 Y, 20 M, 20 C, and 20 K in such a manner as to be distinguished in terms of color, the letters Y, M, C, and K will be omitted. [0015] The image forming units 20 are configured in a similar manner. Each of the image forming units 20 includes an image carrier 22 that has a columnar shape and that is driven so as to rotate at a predetermined speed, a charging member 24 for first charging that charges the outer circumferential surface of the corresponding image carrier 22 , a developing device 26 that develops, with a predetermined color toner, an electrostatic latent image, which has been formed on the charged outer circumferential surface of the image carrier 22 by image exposure performed by the exposure device 18 , so as to visualize the electrostatic latent image as a toner image, and a cleaning blade (not illustrated) that cleans the outer circumferential surface of the image carrier 22 after the toner image has been transferred. [0016] In addition, toner supply devices 14 Y, 14 M, 14 C, and 14 K that supply toners to the corresponding developing devices 26 are disposed in the interior of the apparatus body 12 . In the exposure device 18 , four semiconductor lasers (not illustrated) each having the same configuration are disposed in such a manner as to correspond to the four image forming units 20 Y, 20 M, 20 C, and 20 K, and the laser beams L are to be emitted from the semiconductor lasers in accordance with the gradation data items. [0017] Note that each of the laser beams L, which have been emitted from the semiconductor lasers, is radiated onto a polygon mirror (not illustrated), which is a rotating polygon mirror, via a cylindrical lens (not illustrated) and is caused to be deflected and scanned by the polygon mirror. Then, each of the laser beams L, which have been caused to be deflected and scanned by the polygon mirror, is radiated onto an exposure point on the corresponding image carrier 22 via an imaging lens (not illustrated) and plural mirrors (not illustrated) and is caused to scan and irradiate the image carrier 22 . [0018] Since there is a possibility of toners and the like falling onto the exposure device 18 from the developing devices 26 and the like, which are included in the four image forming units 20 Y, 20 M, 20 C, and 20 K disposed above the exposure device 18 , the periphery of the exposure device 18 is hermetically sealed by a frame 28 having a substantially rectangular parallelepiped shape. An upper portion of the frame 28 is provided with a window 29 that is made of transparent glass and that transmits the four laser beams L onto the corresponding image carriers 22 . [0019] Meanwhile, a first transfer unit 30 is disposed above the image forming units 20 . The first transfer unit 30 includes an endless intermediate transfer belt 32 , a driving roller 34 around which the intermediate transfer belt 32 is wound and which drives the intermediate transfer belt 32 so that the intermediate transfer belt 32 moves circularly in the direction of an arrow in FIG. 1 , a tension-applying roller 36 around which the intermediate transfer belt 32 is wound and which exerts tension on the intermediate transfer belt 32 , a driven roller 38 that is disposed above the tension-applying roller 36 and that is driven so as to rotate by the intermediate transfer belt 32 , and first transfer rollers 40 Y, 40 M, 40 C, and 40 K each of which is positioned on the side opposite to the side on which a corresponding one of the image carriers 22 is disposed with the intermediate transfer belt 32 interposed therebetween. [0020] Toner images of the colors Y, M, C, and K, which have been sequentially formed on the image carriers 22 of the corresponding image forming units 20 Y, 20 M, 20 C, and 20 K, are transferred onto the intermediate transfer belt 32 in such a manner that the toner images are superposed with one another by the four transfer rollers 40 Y, 40 M, 40 C, and 40 K. Note that a cleaning blade 42 that cleans an outer peripheral surface of the intermediate transfer belt 32 is disposed so as to be positioned on the side opposite to the side on which the driving roller 34 is disposed with the intermediate transfer belt 32 interposed therebetween. [0021] A second transfer roller 44 is disposed so as to be positioned on the side opposite to the side on which the driven roller 38 is disposed with the intermediate transfer belt 32 interposed therebetween, and a portion where the intermediate transfer belt 32 and the second transfer roller 44 are in contact with each other serves as a second transfer position. Accordingly, the toner images of the colors Y, M, C, and K, which have been transferred to the intermediate transfer belt 32 in such a manner that the toner images are superposed with one another, are transported by the intermediate transfer belt 32 and are transferred in a second transfer process onto one of sheet members P, each of which is an example of a recording medium. [0022] The fixing unit 70 that fixes toner images that have been transferred to one of the sheet members P onto the sheet member P is disposed at a position downstream from the second transfer position in a transport direction of the sheet members P. Note that the term “in the transport direction of the sheet members P” will hereinafter be omitted when describing such a position downstream from something. The fixing unit 70 is an example of a unit that is removable from the apparatus body 12 , and details of mounting and unmounting mechanisms 80 (see FIG. 2 ) of the fixing unit 70 that are used for mounting and unmounting the fixing unit 70 on and from the apparatus body 12 will be described later. [0023] The fixing unit 70 includes a heating roller 74 and a pressure roller 76 , and toner images are fixed onto one of the sheet members P as a result of the sheet member P passing through a portion where the pressure roller 76 and the heating roller 74 are in contact with each other (as a result of applying heat and pressure to the sheet member P). Ejection rollers 46 that eject the sheet member P, to which the toner images have been fixed, to an ejecting section 48 that is formed in an upper portion of the apparatus body 12 are each disposed at a position downstream from the fixing unit 70 . [0024] Meanwhile, a sheet-feeding member 50 in which the sheet members P are accommodated is disposed in a lower area of the apparatus body 12 . A sheet-feeding roller 52 that sends out the sheet members P, which are accommodated in the sheet-feeding member 50 , to a sheet-transport path is disposed at a position downstream from the sheet-feeding member 50 , and a pair of separation rollers 54 that transport the sheet members P by separating the sheet members P one by one and are each disposed at a position downstream from the sheet-feeding roller 52 . [0025] A pair of registration rollers 56 that adjust a transfer timing are each disposed at a position downstream from the separation rollers 54 . Consequently, as a result of rotation of the registration rollers 56 , one of the sheet members P that has supplied from the sheet-feeding member 50 is sent out, at a predetermined transfer timing, to the second transfer position where the intermediate transfer belt 32 and the second transfer roller 44 are in contact with each other. [0026] Transport rollers 58 that transport one of the sheet members P to the registration rollers 56 again in the case of printing an image on the two surfaces of the sheet member P are disposed in front of the ejection rollers 46 . The sheet member P is flipped over as a result of being transported along a transport path for two-sided printing by the transport rollers 58 and is transported to the registration rollers 56 again. [0027] An image forming process to be executed by the image forming apparatus 10 will now be briefly described. [0028] First, gradation data items of different colors are sequentially output from the image processing unit 16 to the exposure device 18 , and each of the laser beams L, which are emitted from the exposure device 18 in accordance with the gradation data items of the different colors, is caused to scan and irradiate the outer circumferential surface of the corresponding image carrier 22 , which has been charged by the corresponding charging member 24 . As a result, electrostatic latent images are formed on the outer circumferential surfaces of the image carriers 22 . [0029] The electrostatic latent images that have been formed on the image carriers 22 are visualized as toner images of the colors Y, M, C, and K, respectively, by the corresponding developing devices 26 . Then, by the transfer rollers 40 Y, 40 M, 40 C, and 40 K of the first transfer unit 30 , which is arranged above the image forming units 20 Y, 20 M, 20 C, and 20 K, the toner images of the colors Y, M, C, and K that have been formed on the corresponding image carriers 22 are transferred onto the intermediate transfer belt 32 , which moves circularly, in such a manner that the toner images are superposed with one another. [0030] Meanwhile, one of the sheet members P is transported to the sheet-transport path from the sheet-feeding member 50 by the sheet-feeding roller 52 and the separation rollers 54 and is transported to the second transfer position at a predetermined transfer timing by the registration rollers 56 . The toner images of the different colors that have been transferred to the intermediate transfer belt 32 , which moves circularly, in such a manner that the toner images are superposed with one another are transferred in a second transfer process onto the sheet member P at the second transfer position. [0031] The sheet member P to which the toner images have been transferred is transported to the fixing unit 70 , and the toner images, which have been transferred to the sheet member P, are fixed onto the sheet member P by the heating roller 74 and the pressure roller 76 . The sheet member P to which the toner images have been fixed is ejected to the ejecting section 48 , which is formed in an upper portion of the apparatus body 12 , by the ejection rollers 46 . [0032] Note that, in the case of printing an image on the two surfaces of one of the sheet members P, the sheet member P having toner images fixed to one surface thereof by the fixing unit 70 will not be ejected to the ejecting section 48 by the ejection rollers 46 and is transported to the transport path for two-sided printing by the transport rollers 58 as a result of the transport direction of the sheet member P being switched. [0033] The sheet member P that has been flipped over as a result of being transported along the transport path for two-sided printing is transported to the registration rollers 56 again, and toner images are transferred and fixed onto the other surface of the sheet member P. The sheet member P having the toner images fixed to the two surfaces thereof in the above manner is ejected to the ejecting section 48 by the ejection rollers 46 . [0034] The mounting and unmounting mechanisms 80 of the fixing unit 70 that are used for mounting and unmounting the fixing unit 70 on and from the apparatus body 12 will now be described in detail. [0035] As illustrated in FIG. 1 , an opening 12 A is formed in the apparatus body 12 on the front side, and a cover member 60 , which is included in the apparatus body 12 , opens and closes the opening 12 A. A lower end portion (a portion positioned below protruding portions 64 , which will be described later) of the cover member 60 is rotatably supported by a support shaft 62 , which is an example of a rotary support portion having an axial direction parallel to the left-right direction, and accordingly, the cover member 60 is to be opened and closed in the direction of the other arrow in FIG. 1 . [0036] As illustrated in FIG. 3 , a pair of the protruding portions 64 , each of which is an example of a hindering portion, are integrally formed on the left and right sides of an intermediate portion of the inner surface of the cover member 60 in a height direction in such a manner as to protrude from the intermediate portion. When the cover member 60 closes the opening 12 A, each of the protruding portions 64 is inserted into a space between a lower surface 72 A of a housing 72 (described later) of the fixing unit 70 and an upper surface 86 A of a corresponding one of operating portions 86 . End surfaces of the protruding portions 64 , the end surfaces facing toward the rear side in a state where the cover member 60 closes the opening 12 A are flat or substantially flat surfaces 64 A (see FIG. 4 ). [0037] As illustrated in FIG. 2 and FIG. 3 , the fixing unit 70 includes the housing 72 having a long length in the left-right direction, and the heating roller 74 and the pressure roller 76 (see FIG. 1 ) are disposed in the housing 72 . The fixing unit 70 is removable from the apparatus body 12 by hand through the opening 12 A, which is formed as a result of the cover member 60 being opened, in a front-rear direction. [0038] A pair of left and right holding portions 78 that are to be pressed from above by thumbs of both hands are formed at the opposite upper ends of the housing 72 in the longitudinal direction of the housing 72 , the opposite upper ends being located on the side on which a surface of the housing 72 is present, the surface facing the front side and being exposed through the opening 12 A. Plural grooves 78 A each extending in the left-right direction are formed in upper surfaces of the holding portions 78 in order to prevent fingers from slipping. A pair of left and right latch members 82 that are to be pressed by index fingers of both hands are formed at the opposite lower ends of the housing 72 in the longitudinal direction, the opposite lower ends being located on the side on which the surface of the housing 72 is present, the surface facing the front side and being exposed through the opening 12 A. [0039] As illustrated in FIG. 2 and FIG. 4 , the longitudinal direction of the latch members 82 , which are included in the mounting and unmounting mechanisms 80 of the fixing unit 70 , is parallel to the front-rear direction, and a substantially central portion of each of the latch members 82 in the front-rear direction is a rotation fulcrum portion 84 having an axial direction parallel to the left-right direction. In other words, front side end portions (operating portions 86 , which will be described later) and rear side end portions (hooks 88 , which will be described later) of the latch members 82 rotate in a top-bottom direction about the corresponding rotation fulcrum portions 84 . [0040] The front side end portions (upstream side end portions in a mounting direction of the fixing unit 70 ) of the latch members 82 each have a reasonable width in the left-right direction and are the operating portions 86 that are to be pressed by index fingers from below (that are capable of being operated through the opening 12 A). Plural grooves 86 B each extending in the left-right direction are formed in lower surfaces of the operating portions 86 in order to prevent fingers from slipping. A surface of each of the operating portions 86 , the surface facing the front side, is an end surface 86 C. [0041] The operating portions 86 are urged downward by compression-coil springs 66 , each of which is an example of an urging member. In other words, upper ends of the compression-coil springs 66 are attached to the lower surface 72 A of the housing 72 , and lower ends of the compression-coil springs 66 are attached to the upper surfaces 86 A of the corresponding operating portions 86 in such a manner as to be located inside the upper surfaces 86 A in the left-right direction. [0042] Consequently, the operating portions 86 are constantly urged downward, and when the fixing unit 70 is mounted in (inserted into) the apparatus body 12 , each of the operating portions 86 is pressed upward against an urging force of the corresponding compression-coil spring 66 (is caused to rotate upward about the corresponding rotation fulcrum portions 84 ). [0043] Note that, as illustrated in FIG. 2 , recesses 72 B, each of which is recessed upward, may be formed in the lower surface 72 A of the housing 72 , and upper portions of the compression-coil springs 66 may be accommodated in the recesses 72 B while the upper ends of the compression-coil springs 66 are attached to top surfaces of the recesses 72 B. [0044] On the other hand, the rear side end portions (downstream side end portions in the mounting direction of the fixing unit 70 ) of the latch members 82 are the hooks 88 that are latched onto to-be-latched portions 68 , which are included in the apparatus body 12 . As illustrated in FIG. 5 , the to-be-latched portions 68 are fixed, in a so-called snap-fit manner, to support portions 13 that are included in the apparatus body 12 and each of which is substantially L-shaped when seen from the side by being inserted into the support portions 13 from the rear side. A rear end lower surface of each of the to-be-latched portions 68 is an arc-shaped or substantially arc-shaped surface 68 A that is an example of a contact surface formed so as to have an arc shape or a substantially arc shape when seen from the side. [0045] The hooks 88 protrude upward, and front lower portions of the hooks 88 are linear or substantially linear contact portions 88 A that are brought into contact with the arc-shaped or substantially arc-shaped surfaces 68 A of the corresponding to-be-latched portions 68 at a predetermined pressure (by the urging force of the corresponding compression-coil springs 66 ) from the rear side (the downstream side in the mounting direction of the fixing unit 70 ). With this configuration, the contact portions 88 A of the hooks 88 are secured to the arc-shaped or substantially arc-shaped surfaces 68 A of the corresponding to-be-latched portions 68 , and as a result, the fixing unit 70 is fixed to the apparatus body 12 . [0046] As illustrated in FIG. 5 , in a state where the contact portion 88 A of each of the contact portions 88 A is secured to the arc-shaped or substantially arc-shaped surface 68 A of the corresponding to-be-latched portion 68 , an angle θ 1 formed by a contact-portion imaginary line K 1 extending from the center of rotation of the corresponding rotation fulcrum portion 84 to the contact portion 88 A through a center O of a circle formed of the arc-shaped or substantially arc-shaped surface 68 A of the to-be-latched portion 68 and an imaginary line K 3 indicating an extending direction of the contact portion 88 A is set to be 90 degrees or about 90 degrees or larger. [0047] Front upper portions of the hooks 88 (tip portions of the hooks 88 located above the corresponding contact portions 88 A) are barb portions 88 B each of which overlaps a rear end upper surface of the corresponding to-be-latched portion 68 from the rear side (in such a manner as to pass through the imaginary line K 3 in a securing direction). An angle θ 2 formed by a barb-portion imaginary line K 2 extending from the center of rotation of one of the rotation fulcrum portions 84 to the corresponding barb portion 88 B and an imaginary line K 4 indicating an extending direction of the barb portion 88 B is set to be 90 degrees or about 90 degrees or smaller. Note that each of the barb portions 88 B is formed in such a manner that the angle θ 2 is 90 degrees or about 90 degrees or smaller whichever portion of the barb portion 88 B the barb-portion imaginary line K 2 passes through. [0048] Rear portions of the hooks 88 are inclined portions 88 C each of which is inclined forward and upward (rearward and downward) when seen from the side as illustrated in FIG. 5 . When, for example, the fixing unit 70 is mounted in the apparatus body 12 in a state where the operating portions 86 are not pressed upward, the inclined portions 88 C function as guide portions, which cause the corresponding hooks 88 to rotate downward about the corresponding rotation fulcrum portions 84 , by being brought into slidable contact with lower surfaces of the corresponding support portions 13 . [0049] Operation of the mounting and unmounting mechanisms 80 of the fixing unit 70 , which have the above-described configuration, will now be described. [0050] The cover member 60 opens the opening 12 A of the apparatus body 12 of the image forming apparatus 10 by rotating forward about the support shaft 62 . When mounting the fixing unit 70 in the apparatus body 12 , first, the holding portions 78 , which are formed in the upper portion of the housing 72 , and the operating portions 86 of the latch members 82 , which are formed in the lower portion of the housing 72 , are clamped by thumbs and index fingers. [0051] As a result, the operating portions 86 are pressed upward against the urging force of the corresponding compression-coil springs 66 and move (rotate) upward about the corresponding rotation fulcrum portions 84 . In other words, the hooks 88 move (rotate) downward about the corresponding rotation fulcrum portions 84 . In this state, the fixing unit 70 is inserted into (mounted in) the apparatus body 12 through the opening 12 A. [0052] The hooks 88 are moved downward as a result of moving the operating portions 86 upward about the rotation fulcrum portions 84 . Consequently, the hooks 88 are prevented from interfering with the corresponding support portions 13 through a process in which the fixing unit 70 is mounted in the apparatus body 12 . Note that, since each of the hooks 88 includes the inclined portion 88 C, even if the amount of downward movement of the hook 88 is not sufficient, the hook 88 moves downward while being guided by the lower surface of the corresponding support portion 13 . [0053] After the fixing unit 70 has been mounted in the apparatus body 12 , thumbs and index fingers are released from the holding portions 78 and the operating portions 86 . Then, the operating portions 86 are caused to move downward about the corresponding rotation fulcrum portions 84 by the urging force of the corresponding compression-coil springs 66 , and the contact portions 88 A of the hooks 88 are brought into contact with the arc-shaped or substantially arc-shaped surfaces 68 A of the corresponding to-be-latched portions 68 at a predetermined pressure (by the urging force of the compression-coil springs 66 ) from the rear side. As a result, the fixing unit 70 is fixed to the apparatus body 12 . [0054] Note that, in this case, the angle θ 1 formed by the contact-portion imaginary line K 1 extending from one of the rotation fulcrum portions 84 to the corresponding contact portion 88 A through the center O of the circle formed of the arc-shaped or substantially arc-shaped surface 68 A of the corresponding to-be-latched portion 68 and the imaginary line K 3 indicating the extending direction of the contact portion 88 A is set to be 90 degrees or about 90 degrees or larger (see FIG. 5 ). [0055] After the fixing unit 70 has been fixed to the apparatus body 12 in the above manner, the cover member 60 is caused to rotate about the support shaft 62 in a direction opposite to the above-mentioned direction so as to close the opening 12 A. [0056] When the cover member 60 closes the opening 12 A, each of the protruding portions 64 , which are formed on the inner surface of the cover member 60 in such a manner as to protrude from the inner surface, is inserted between the lower surface 72 A of the housing 72 and an area outside the upper surface 86 A of the corresponding operating portion 86 in the left-right direction (see FIG. 4 ). Here, in the case where an external force is applied to the fixing unit 70 in a direction in which the fixing unit 70 is separated from the apparatus body 12 (such as when, for example, the image forming apparatus 10 is dropped), the hooks 88 rotate in a direction in which the hooks 88 are separated from the corresponding to-be-latched portions 68 (see FIG. 6 ). [0057] However, as illustrated in FIG. 6 , since each of the protruding portions 64 is inserted between the lower surface 72 A of the housing 72 and the area outside the upper surface 86 A of the corresponding operating portion 86 in the left-right direction, when the hooks 88 rotate in the direction in which the hooks 88 are separated from the corresponding to-be-latched portions 68 in a state where the cover member 60 closes the opening 12 A, the operating portions 86 interfere with the corresponding protruding portions 64 , and the hooks 88 are hindered, by the protruding portions 64 , from rotating in the direction in which the hooks 88 are separated from the corresponding to-be-latched portions 68 . [0058] In other words, according to the mounting and unmounting mechanisms 80 of the fixing unit 70 of the present exemplary embodiment, the probability of the fixing unit 70 , which is removable from the apparatus body 12 , becoming separated from the apparatus body 12 due to an external force, such as vibration or a drop impact, is reduced, or the fixing unit 70 is prevented from becoming separated from the apparatus body 12 apparatus body 12 due to an external force, such as vibration or a drop impact, compared with the configuration in which the cover member 60 is not provided with the protruding portions 64 that hinder the corresponding hooks 88 from rotating in the direction in which the hooks 88 are separated from the corresponding to-be-latched portions 68 . [0059] In addition, since the angle θ 2 formed by the barb-portion imaginary line K 2 extending from one of the rotation fulcrum portions 84 to the corresponding barb portion 88 B and the imaginary line K 4 indicating the extending direction of the barb portion 88 B is set to be 90 degrees or about 90 degrees or smaller, each of the barb portions 88 B of the hooks 88 is less likely to be separated from the corresponding to-be-latched portion 68 compared with the configuration in which the angle θ 2 is larger than 90 degrees or about 90 degrees. [0060] As illustrated in FIG. 7 , when performing an operation for closing the cover member 60 in a state where the hooks 88 are not latched to the corresponding to-be-latched portions 68 , the flat or substantially flat surfaces 64 A of the protruding portions 64 come into surface contact with the end surfaces 86 C of the corresponding operating portions 86 , and accordingly, it is difficult to close the cover member 60 . Therefore, the likelihood of failure of mounting the fixing unit 70 in the apparatus body 12 is reduced, or failure of mounting the fixing unit 70 in the apparatus body 12 is prevented from occurring compared with the configuration in which the protruding portions 64 do not have the flat or substantially flat surfaces 64 A, which hinder the cover member 60 from closing the opening 12 A. [0061] In other words, a probability of occurrence of a problem in that the cover member 60 is closed in a state where the fixing unit 70 is not mounted in the apparatus body 12 is reduced, or a problem in that the cover member 60 is closed in a state where the fixing unit 70 is not mounted in the apparatus body 12 is prevented from occurring. Note that, in this case, the fixing unit 70 is pushed into the apparatus body 12 by forcibly closing the cover member 60 , and the hooks 88 are latched onto the corresponding to-be-latched portions 68 . Therefore, the likelihood of the failure of mounting the fixing unit 70 in the apparatus body 12 is further reduced, or the failure of mounting the fixing unit 70 in the apparatus body 12 is further prevented from occurring. [0062] Although the image forming apparatus 10 according to the present exemplary embodiment has been described above with reference to the drawings, the image forming apparatus 10 according to the present exemplary embodiment is not limited to that illustrated in the drawings, and design changes may be suitably made within the gist of the present invention. For example, the mounting and unmounting mechanisms 80 according to the present exemplary embodiment are not limited to being included in the fixing unit 70 and may be included in a different unit, such as the first transfer unit 30 , that is removable from the apparatus body 12 . [0063] In addition, the to-be-latched portions 68 are not limited to having the shape illustrated in the drawings as long as the rear end lower surfaces of the to-be-latched portions 68 , with which the contact portions 88 A of the corresponding hooks 88 are brought into contact, are the arc-shaped or substantially arc-shaped surfaces 68 A each of which is formed so as to have an arc shape or a substantially arc shape when seen from the side. Therefore, each of the to-be-latched portions 68 may be, for example, a columnar shaft (not illustrated). [0064] The foregoing description of the exemplary embodiment of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiment were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.

An image forming apparatus includes a cover that opens and closes an opening of an apparatus body, a unit removable from the apparatus body through the opening, a latch that is included in the unit and that is rotatable about a rotation fulcrum, the latch including a hook that is latched onto a latched portion of the apparatus body from downstream in a mounting direction of the unit to fix the unit onto the apparatus body and an operating portion that opposes the hook across the rotation fulcrum and that is operable through the opening, and a hindering portion that is included in the cover and that interferes, when the hook rotates in a separating direction in which the hook is separated from the latched portion in a state where the cover closes the opening, with the operating portion and hinders the hook from rotating in the separating direction.

BACKGROUND This invention relates to jet skis, and more particularly, to an improved grating for controlling the inlet of water to a pump impeller and jet nozzle on a jet ski. Recently, jet skiing has become a popular water sport. A jet ski provides its own motive power, and therefore the rider can ski without requiring the aid of others, such as in water skiing. A jet ski has a hull similar in shape to a boat, and the rider stands or crouches near the aft end of the hull when skiing. A gasoline engine mounted in the hull in front of the rider drives a pump impeller in the aft section of the hull. A well formed in the bottom of the hull is covered by a grating which aids in scooping water and directing it through the well and into the impeller blades. The impeller forces the water through a jet nozzle behind the impeller for providing motive power for the ski. The rider steers the jet ski by a steering mechanism which controls deflection of a steering nozzle at the aft end of the hull. At the present time, jet skis can travel over 30 miles an hour, and jet ski racing has recently become a popular form of competition. The present invention is based on a recognition that the speed of a jet ski can be increased significantly by an improved grating structure provided by this invention. The jet ski of this invention has proved to be an improvement over the jet ski Series JS 440-A manufactured by Kawasaki Motors Corp. SUMMARY OF THE INVENTION Briefly, this invention provides a jet ski having a hull with a generally flat bottom surface adjacent a well formed in the bottom of the hull, a pump aft of an opening in the well for providing motive power for the jet ski in water, and a grating secured over the well in front of the opening to the pump. The grating has a scoop for directing water through the opening and toward the pump. The scoop has a concavely curved bottom edge that projects below the plane of the hull bottom surface. The bottom edge of the scoop is generally at the point of maximum spacing between the bottom surface of the hull and the bottom surface of the grating. The concave edge of the scoop is continuous and uninterrupted across substantially the entire width of the scoop surface, providing an opening within the grating which is essentially entirely open from the scoop to the forward end of the grating. The grating structure results in increased speed of the jet ski when compared with the Kawasaki Series JS 440-A jet ski referred to above. These and other aspects of the invention will be more fully understood by referring to the following detailed description and the accompanying drawings. DRAWINGS FIG. 1 is a schematic view showing a jet ski; FIG. 2 is a fragmentary bottom elevation view taken on line 2--2 of FIG. 1 and showing a portion of a jet ski having a grating according to principles of this invention; FIG. 3 is a fragmentary semi-schematic side elevation view taken on line 3--3 of FIG. 2; FIG. 4 is a bottom elevation view taken on line 4--4 of FIG. 3 and showing the grating of this invention; FIG. 5 is a top elevation view taken on line 5--5 of FIG. 3; FIG. 6 is a side elevation view taken on line 6--6 of FIG. 5; and FIG. 7 is a cross-sectional view taken on line 7--7 of FIG. 5. DETAILED DESCRIPTION FIG. 1 shows a jet ski 10 having a hull 12 on which a rider 14 can stand when riding the jet ski. The rider operates a steering mechanism 16 which, in turn, controls deflection of a steering nozzle 18 (see FIG. 2) at the aft end of the hull. A gasoline engine (not shown) is mounted in the hull forward of where the rider stands. Referring to FIGS. 2 and 3, a drive shaft 20 driven by the engine extends toward the aft end of the hull where the shaft is coupled to an impeller 22. The impeller is contained in a pump housing 24 in the aft section of the hull behind a well 26 formed in the bottom of the hull. The well has an aft opening 28 to the pump housing so that water flowing through the well can pass through the opening toward the impeller. A jet nozzle (not shown) is coupled to the aft end of the pump housing, and the steering nozzle swivels about a vertical axis through the aft end of the jet nozzle. Water forced through the nozzles provides motive power for the hull in water. The hull has a generally flat bottom surface 30 extending fore and aft of the well. The flat bottom surface of the hull adjacent the aft end of the well is actually formed by a pump housing cover plate 32. The cover plate and the bottom surface portion of the hull forward of the well are in a common plane, as illustrated by the phantom line 34 in FIG. 3. The bottom surface of the hull adjacent the fore and aft ends of the well is flat essentially for approximately the same width as the well itself. This configuration is best depicted in FIG. 2. The lower portion of the well is covered by a grating 36 according to principles of this invention. The construction of the grating is understood best by referring to FIGS. 3 through 7. The grating comprises a piece of metal of generally long and narrow rectangular shape, with a long and narrow generally rectangular opening 38 extending through most of the length of the grating. A pair of long and narrow parallel side bars 39 extend along opposite sides of the grating. The side bars deflect large foalting debris during use to keep it from entering the pump. A generally narrow front mounting bar 40 at the forward end of the grating integrally connects the forward ends of the side bars 39. A generally rectangular aft mounting plate 42 at the aft end of the grating integrally connects the aft ends of the side bars 39. A separate threaded bore 44 extends through each end of the front mounting bar 40 near the corners formed between the mounting bar and the side bars 39. A single threaded bore 46 extends through the aft mounting plate 42 on the grating centerline and near the aft end of the grating. A scoop 48 is formed at the aft end of the opening 38 in the grating. The surface of the scoop faces toward the forward end of the grating and the surface of the scoop is angled so that it faces upwardly toward the well 26. Stated another way, the scoop surface intersects the bottom surface of the grating to form a curved bottom edge 50. The scoop surface is inclined upwardly and in the aft direction away from the curved bottom edge to form a correspondingly curved top edge 52 which intersects the top surface of the grating. The curved top and bottom edges of the scoop are curved concave inwardly toward the aft mounting plate 42 when the grating is viewed from above as in FIG. 5. The opening 38 in the grating is entirely uninterrupted from end-to-end, i.e., from the surface of the scoop 48 to the mounting bar 40 at the front end of the grating. The scoop surface also is continuous and uninterrupted from one side to the other, i.e., from its juncture with one side bar 39 to its juncture with the other side bar 39. In one embodiment, the concave bottom edge 50 of the scoop is continuous and uninterrupted for a distance of about 11/8 to 11/4 inches. The aft mounting plate 42 has a flat top surface 54 for contact with a corresponding flat surface 56 at the base of the pump housing, when the aft end of the grating is secured over the well. Similarly, the front mounting bar 40 has a flat top surface 58 for lying flat against a corresponding flat surface 60 inside a front portion of the well. As shown in FIG. 2, a fastener 62 secures the aft mounting plate of the grating to surface 56 at the base of the pump housing, and fasteners 64 secure the front mounting bar of the grating to the surface 60 near the forward end of the well. When the grating is viewed from the side, as in FIG. 6, the aft mounting plate 42 tapers wider from the aft end of the grating toward the bottom edge 50 of the scoop, and then the side bars 39 generally taper narrower away from the scoop bottom edge 50 toward the forward end of the grating. When the grating is secured over the well, as illustrated best in FIGS. 3 and 6, a tapering aft bottom surface 66 of the grating projects below the plane 34 of the hull bottom surface adjacent the aft side of the scoop bottom edge 50, and a tapering forward bottom surface 67 of the grating side bars projects below the plane 34 adjacent the forward side of the scoop. The aft bottom surface 66 of the grating which extends from the aft end of the grating toward the bottom edge 50 of the scoop gradually projects farther below the plane 34 of the hull bottom surface. The bottom edge 50 of the scoop is generally at the point of maximum vertical spacing between the plane 34 of the hull bottom surface and the bottom surface of the grating. The forward portion 67 of the grating bottom surface extending in a forward direction away from the scoop bottom edge 50 gradually tapers closer toward the plane 34 of the hull bottom surface. Thus, the curved bottom edge 50 projects below portions of the flat bottom surface of the hull both forward and aft of the well 26; and the curved bottom edge 50 is continuous and uninterrupted from one side to the other at the point of maximum spacing below the hull bottom surface, as shown in FIG. 7. Referring to FIG. 3, the grating is mounted over the well 26 so that the surface of the scoop projects in a forward direction away from the bottom of the opening 28 to the pump housing 24. The angle of the scoop surface deflects water upwardly toward the opening to the pump housing. The surface 56 to which the aft mounting plate 42 is attached is not quite parallel to the plane 34 of the hull bottom, and the surface 60 to which the front mounting bar 60 is secured is slightly askew to the hull bottom plane 34. When the grating is mounted over the well, the top surface of the front mounting bar 60 is about 0.35 inch above the top surface of the aft mounting plate 42. At the aft edge of the grating, the bottom surface of the grating lies in the plane 34 of the hull bottom surface. From that point forward, the bottom surface of the grating tapers progressively farther below the bottom of the hull up to the vicinity of the scoop bottom edge 50. Forward of the scoop bottom edge 50 the side bars 39 then progressively taper closer toward the plane of the hull bottom surface, and a substantial length of the side bars extends upwardly into the well above the plane of the hull bottom surface. In one embodiment of the grating, the grating is about 12 inches in overall length (dimension a in FIG. 4). The grating is about 3.10 inches in width at its front end (dimension b in FIG. 4) and about 2.95 inches in width at its aft end (dimension c in FIG. 4). The forward mounting bar 40 has a width of about 0.75 inch (dimension d in FIG. 4). The curved bottom edge 50 of the scoop (at its center) is approximately 2.25 inches in front of the aft end of the grating (dimension e in FIG. 4), and the top edge 52 of the scoop surface is approximately 1.6 inches from the aft end of the grating (dimension f in FIG. 5). This provides a scoop angle of about 45° with respect to a vertical line through the bottom edge of the scoop. In the embodiment shown, the depth of the grating bottom edge 50 below the top surface of the grating (dimension g in FIG. 6) is approximately 0.54 inch. The side bars 39 taper from a minimum width of about 0.20 inch (dimension h in FIG. 5) near the forward end of the grating to a width of about 0.325 inch (dimension i in FIG. 5) near the scoop. Thus, the opening 38 in the grating is generally about 9 inches long and about 2.3 inches wide. The grating is as streamlined as possible, with the top surface and bottom surface of the grating being generally continuous and uninterrupted from one end of the grating to the other. The side bars of the grating also are streamlined in that they are relatively narrow when viewed from above, as in FIG. 5; and when viewed in cross-section, as in FIG. 7, the side bars are smoothly and slightly curved convex outwardly on both sides of each arm. I have discovered that the jet ski of this invention has a significantly higher speed than the Kawasaki jet ski Series JS 440-A referred to above. In comparative tests in which my jet ski was raced with a Kawasaki jet ski over a one mile course, my jet ski, on the average, was about 200 yards ahead of the Kawasaki jet ski by the finish of the race. The only difference between the two jet skis was that my jet ski used the grating described above, whereas the Kawasaki jet ski used a standard grating now being sold with Kawasaki jet skis. The Kawasaki grating has two parallel outside bars and a central rib extending parallel to and between the side bars. The aft end of the central rib is integrally formed with the scoop surface, forming two interrupted side-by-side openings adjacent the scoop on opposite sides of the central rib. The bottom surface of the Kawasaki grating does not project below the plane of the hull bottom surface. I have discovered that superior performance over the Kawasaki jet ski is obtained when the uninterrupted bottom edge of the scoop in my jet ski projects below the hull bottom plane 34 by a vertical distance of between about 0.05 to 0.30 inch. Best performance is obtained when the vertical distance is between about 0.20 to 0.25 inch. I have also discovered that a shallower projection, i.e., in the neighborhood of about 0.05 to 0.1 inch below the plane of the hull, can provide increased performance over the Kawasaki jet ski for calm or smooth water conditions. However, for rough water conditions, as well as smooth water conditions, the 0.20 to 0.25 inch projection provides the best performance. It was surprising to me that such improved performance was obtained from the grating of this invention, since a projection below the hull bottom could be thought to increase resistance or turbulence in the opening to the pump housing and reduce the speed of the ski. It was discovered that a scoop that projects about 0.3 to 0.6 inch below the hull bottom does result in poorer performance, probably owing to the greater turbulence. The grating of this invention keeps the hull of the ski down in the water more than the Kawasaki grating. A jet ski with a powerful engine tends to hop out of the water when traveling at high speeds, which causes the pump impeller to jump free of the water and reduce speed. Since my grating tends to keep the jet ski lower in the water, the jet ski does not have the same tendency to hop or skip out of the water, resulting in the higher speed.

A jet ski has a hull, a motor mounted in the hull for driving a pump in an aft section of the hull, and a well formed in the bottom of the hull in front of an opening to the pump impeller. A grating which covers the well has a scoop below and in front of an opening to the pump housing for scooping water and directing it toward the impeller during use. Water from the impeller is forced under pressure through a jet nozzle aft of the impeller for providing motive power for the hull. The scoop has a concavely curved, inclined surface with a continuous and uninterrupted bottom edge projecting below the plane of the hull bottom surface, which results in increased velocity of the ski.

CROSS-REFERENCE TO RELATED APPLICATIONS Pursuant to 35 U.S.C. § 119(a), this application claims the benefit of earlier filing date and right of priority to Korean Application No. P05-013491, filed on Feb. 18, 2005 and Korean Application No. P05-030725, filed on Apr. 13, 2005, the contents of which are hereby incorporated by reference herein in their entirety. FIELD OF THE INVENTION The present invention relates to a multi-mode mobile terminal, and more particularly, to allowing a multi-mode mobile terminal, such as a mobile terminal for use in a broadband wireless access network system, a wireless local access network (LAN), a wired LAN, and a cellular system interface to effectively perform a handover function between heterogeneous networks. BACKGROUND OF THE INVENTION Currently, standards committee IEEE 802.21 conducts intensive research into the international standards associated with media independent handover (MIH) between heterogeneous networks. MIH provides not only a seamless handover but also a service continuity between the heterogeneous networks, resulting in greater convenience for a user carrying a mobile terminal. IEEE 802.21 defines a variety of functions (e.g., an MIH function, an event trigger function, and an information service (IS) function) as basic requirements. A mobile subscriber station (MSS) is indicative of a multi-mode node for supporting at least two interface types. The above-mentioned interface type may be determined to be one of a wired interface type (also called a wire-line interface type) such as the Ethernet based on an IEEE 802.3 standard specification, a wireless interface type based on IEEE 802.XX standard specifications (e.g., IEEE 802.11, IEEE 802.15, and IEEE 802.16), and other interface types defined by a cellular standardization organization (e.g., 3GPP or 3GPP2). However, it should be noted that the aforementioned interface types are not limited to the aforementioned wired interface type, wireless interface types, and other interface types, and are applicable to other examples as necessary. A general Media Independent Handover Function (MIHF) reference model is depicted in FIG. 1 . In the figure, MIHF architecture for interaction with other layers and with the remote MIHG is illustrated. In order for the MIHF to provide asynchronous and synchronous services to lower layers and higher layers, Service Access Points (SAPs) such as MIH_MGMT_SAP, MIH_SME_SAP and MIH_SAP along with primitives are defined. MIH_MGMT_SAP defines the interface between the MIHF and the management plane (Management Entity) of different network interfaces and is used for transporting MIH protocol messages between the MIHF and local link layer entities as well as peer MIHF entities. MIH_SAP defines the interface between the MIHF and higher layer entities such as device manager, handover policy control function, transport, layer 3 (L3) mobility management protocol, etc., and is used for MIH configuration and operation. MIH_SME_SAP defines the interface between the MIHF and the Station Management Entity or the Network Management System, and is used for MIG configuration and operation. FIG. 2 is a structural diagram illustrating a protocol layer of a multi-mode mobile terminal (also called a multi-mode MSS). Referring to FIG. 2 , the multi-mode mobile terminal includes a physical (PHY) layer and a Medium Access Control (MAC) layer for individual modes, and locates a Media Independent Handover (MIH) layer under an Internet Protocol (IP) layer. Media Independent Handover (MIH) must be defined between IEEE 802-series interfaces or between an IEEE 802-series interface and a non-IEEE 802-series interface, such as the aforementioned interface type defined by a cellular standardization organization (e.g., 3GPP and 3GPP2). Also, a protocol for supporting mobility of upper layers such as a mobile IP and a Session Initiation Protocol (SIP) must be supported for a handover function and continuity of services. The MIH function is located under the IP layer, and facilitates a handover process using input values (e.g., a trigger event and information associated with other networks) received from a second layer (Layer 2). The MIH function may include a plurality of input values based on both user policy and configuration which may affect the handover process. General interfaces among the mobile IP, a third layer (Layer 3) entity such as an SIP (Session Initiation Protocol), and the MIH layer are defined. In this case, the aforementioned interfaces provide the first layer (i.e., the physical layer), the second layer (i.e., the MAC layer), and mobility management information. The MIH function acquires information associated with a lower layer and a network using event and information service (IS) functions. An upper layer includes an upper management entity for monitoring states and operations of various links contained in a mobile terminal, such that it performs a handover control function and a device manager function. In this case, the handover control function and the device manager may be located at different locations independent of each other, or the handover control function and the device manager may be included as the upper management entities in the upper layer. FIG. 3 shows a mobile terminal function entity including the MIH function, a network function entity, and a transmission protocol. Dotted lines of FIG. 3 are indicative of primitive information and an event trigger, for example. In order to quickly perform a handover function, a network layer must use information generated from a link layer, such that the network layer can quickly re-establish a connection state. The link layer event is adapted to predict the movement of a user, and helps a mobile terminal and a network prepare the handover function. A trigger for the handover may be initiated from the physical (PHY) layer and the MAC layer. A source of the trigger may be a local stack or a remote stack. FIG. 4 is a block diagram illustrating a trigger model. An event trigger provides state information of a current signal, state change information of another network, and future predicted change information. The event trigger also includes change information of the physical and MAC layers or attribute change information of a specific network. The event types can be classified into a physical (PHY) layer event, a MAC layer event, a management event, a third layer (L3) event, and an application event, for example. The basic trigger events will hereinafter be described. A “Link_Up” event occurs when a second layer (L2) connection is established on a specific link interface and an upper layer is able to transmit third layer (L3) packets. In this case, it is determined that all L2 layers contained in a link have been completely configured. A source of the “Link_Up” event corresponds to a “Local MAC” and a “Remote MAC”. The following Table 1 shows parameters of the “Link_Up” event. TABLE 1 Name Type Description EventSource EVENT_LAYER_TYPE Source at which event occurs EventDestination EVENT_LAYER_TYPE Destination to which event is to be transmitted MacMobileTerminal MAC Address MAC address of Mobile Terminal MacOldAccessRouter MAC Address MAC address of old access router MacNewAccessRouter MAC Address MAC address of new access router NetworkIdentifier Media Specific Network ID used for detecting subnet change A “Link_Down” event occurs when the L 2 connection is released on a specific interface and L 3 packets cannot be transmitted to a destination. A source of the “Link_Down” event is indicative of a local MAC. The following Table 2 shows parameters of the “Link_Down” event. TABLE 2 Name Type Description EventSource EVENT_LAYER_TYPE Source at which event occurs EventDestination EVENT_LAYER_TYPE Destination to which event is to be transmitted MacMobileTerminal MAC Address MAC address of Mobile Terminal MacOldAccessRouter MAC Address MAC address of old access router ReasonCode Reason for released link A “Link_Going_Down” event occurs when it is expected that the L 2 connection will enter a “Link_Down” state within a predetermined time, and may serve as a signal for initializing a handover procedure. A source of the “Link_Going_Down” corresponds to a “Local MAC” and a “Remote MAC”. The following Table 3 shows parameters of the “Link_Going_Down” event. TABLE 3 Name Type Description EventSource EVENT_LAYER_TYPE Source at which event occurs EventDestination EVENT_LAYER_TYPE Destination to which event is to be transmitted MacMobileTerminal MAC Address MAC address of Mobile Terminal MacOldAccessRouter MAC Address MAC address of old access router MacNewAccessRouter MAC Address MAC address of new access router TimeInterval Time in msecs Predicted Link_Down time of link ConfidenceLevel % Link_Down level predicted at specific time UniqueEventIdentifier Use in event rollback occurrence A “Link_Going_Up” event occurs when it is expected that the L 2 connection will enter a “Link_Up” state within a predetermined time, and is used when a long period of time is consumed to initialize a network. A source of the “Link_Going_Up” event corresponds to a “Local MAC” and a “Remote MAC”. The following Table 4 shows parameters of the “Link_Going_Up” event. TABLE 4 Name Type Description EventSource EVENT_LAYER_TYPE Source at which event occurs EventDestination EVENT_LAYER_TYPE Destination to which event is to be transmitted MacMobileTerminal MAC Address MAC address of Mobile Terminal MacNewAccessRouter MAC Address MAC address of new access router TimeInterval Time in msecs Predicted Link_UP time of link ConfidenceLevel % Link_UP level predicted at specific time UniqueEventIdentifier Use in event rollback occurrence A “Link_Event_Rollback” event is formed by combining the “Link_Going_Down” event with the “Link_Going_Up” event. The “Link_Event_Rollback” event is indicative of a trigger generated when it is expected that the “Link_UP” event or “Link_Down” event will not be generated any more within a specific time on the condition that the “Link_Going_Up” event or “Link_Going_Down” event are transmitted to a destination. A source of the “Link_Event_Rollback” event corresponds to a “Local MAC” and a “Remote MAC”. The following Table 5 shows parameters of the “Link_Event_Rollback” event. TABLE 5 Name Type Description EventSource EVENT_LAYER_TYPE Source at which event occurs EventDestination EVENT_LAYER_TYPE Destination to which event is to be transmitted MacMobileTerminal MAC Address MAC address of Mobile Terminal MacNewAccessRouter MAC Address MAC address of new access router UniqueEventIdentifier Use in event rollback occurrence A “Link_Available” event is indicative of an available state of a new specific link, and indicates the possibility of allowing a new base station (BS) or a new Point of Attachment (POA) to provide a link superior in quality as compared to a current BS or a current POA to which a current mobile terminal is connected. A source of the “Link_Available” event corresponds to a “Local MAC” and a “Remote MAC”. The following Table 6 shows parameters of the “Link_Available” event. TABLE 6 Name Type Description EventSource EVENT_LAYER_TYPE Source at which event occurs EventDestination EVENT_LAYER_TYPE Destination to which event is to be transmitted MacMobileTerminal MAC Address MAC address of Mobile Terminal MacNewAccessRouter MAC Address MAC address of new access router MacOldAccessRouter MAC Address MAC address of old access router A “Link_Parameter_Change” event is indicative of an event generated when a change of a link parameter value is higher than a specific threshold level. The “Link_Parameter_Change” event includes link layer parameters, for example, a link speed (i.e., a link rate), a QoS (Quality of Service), and an encrypted value, etc. A source of the “Link_Parameter_Change” event corresponds to a “Local MAC” and a “Remote MAC”. The following Table 7 shows parameters of the “Link_Parameter_Change” event. TABLE 7 Name Type Description EventSource EVENT_LAYER_TYPE Source at which event occurs EventDestination EVENT_LAYER_TYPE Destination to which event is to be transmitted MacMobileTerminal MAC Address MAC address of Mobile Terminal MacAccessRouter MAC Address MAC address of new access router oldValueOfLinkParameter Old value of link parameters newValueOfLinkParameter New value of link parameters FIG. 5 exemplarily shows triggers generated until a new link is established when a quality of a current access link is deteriorated. An information service provides detailed information associated with a network required for both network discovery and network selection, and must be designed to be freely accessed by a user over any network. The information service must include a variety of information components, for example, a link access parameter, a security mechanism, a neighborhood map, a location, information indicative of a service provider and other access information, and a link cost (i.e., cost of link). The MAC layer of a link interface to which the multi-mode mobile terminal is connected transmits the “Link_Going_Down” trigger to the MIH when a signal quality of the currently connected link is deteriorated, and then performs a scanning process to determine the presence or absence of an accessible link in a homogeneous network. If the accessible link is not detected from the homogeneous network, the mobile terminal must perform the scanning process to determine the presence or absence of the accessible link in a heterogeneous network, but associated prior arts for the aforementioned scanning process have not yet been developed, such that a handover function between heterogeneous networks for the multi-mode mobile terminal cannot be effectively supported. SUMMARY OF THE INVENTION The present invention is directed to supporting media independent handover of a mobile terminal to a heterogeneous network. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the present invention is embodied in a method for supporting media independent handover of a mobile terminal to a heterogeneous network, the method comprising establishing a unified interface to an upper layer of the mobile terminal for managing messages to and from at least one of a homogeneous network and a heterogeneous network and requesting a scan of a heterogeneous network different from a current network of the mobile terminal via the unified interface to determine the presence of an accessible link of the heterogeneous network for performing the handover. Preferably, the step of requesting the scan is performed in the upper layer. Preferably, the heterogeneous network is periodically scanned. Preferably, the unified interface is a media independent handover function (MIHF) entity. Preferably, the upper layer comprises an upper management entity for managing homogeneous and heterogeneous network links associated with the mobile terminal. In one aspect of the present invention, the method further comprises discovering the accessible link of the heterogeneous network, informing the upper layer of the accessible link via the unified interface, and establishing a connection with the accessible link. Preferably, the step of informing the upper layer of the accessible link via the unified interface comprises informing the upper layer of a signal quality of the accessible link of the heterogeneous network. Preferably, the signal quality comprises at least one of a signal to interference plus noise ratio (SINR) and a received signal strength indication (RSSI). In another aspect of the present invention, the step of requesting a scan comprises at least one of identifying a source for where the request is generated, identifying a destination for where the request is to be transmitted, and providing an identification of the mobile terminal. In accordance with another embodiment of the present invention, a method for supporting media independent handover of a mobile terminal to a heterogeneous network comprises establishing a unified interface to an upper layer of the mobile terminal for managing messages to and from at least one of a homogeneous network and a heterogeneous network, scanning a current network for a link different from a current link of the mobile terminal for performing the handover, reporting availability status of the link different from the current link of the current network, receiving the report in an upper layer of the mobile terminal via the unified interface, and requesting a scan of a heterogeneous network different from the current network via the unified interface to determine the presence of an accessible link of the heterogeneous network for performing the handover when the link of the current network different from the current link is not available. Preferably, the step of requesting the scan is performed in the upper layer. Preferably, the heterogeneous network is periodically scanned. Preferably, the unified interface is a media independent handover function (MIHF) entity. Preferably, the upper layer comprises an upper management entity for managing homogeneous and heterogeneous network links associated with the mobile terminal. In one aspect of the present invention, the method further comprises discovering the accessible link of the heterogeneous network, informing the upper layer of the accessible link via the unified interface, and establishing a connection with the accessible link. Preferably, the step of informing the upper layer of the accessible link via the unified interface comprises informing the upper layer of a signal quality of the accessible link of the heterogeneous network. Preferably, the signal quality comprises at least one of a signal to interference plus noise ratio (SINR) and a received signal strength indication (RSSI). In another aspect of the present invention, the step of requesting a scan comprises at least one of identifying a source for where the request is generated, identifying a destination for where the request is to be transmitted, and providing an identification of the mobile terminal. In accordance with another embodiment of the present invention, a method for supporting media independent handover of a mobile terminal to a heterogeneous network comprises establishing a unified interface to an upper layer of the mobile terminal for managing messages to and from at least one of a homogeneous network and a heterogeneous network, requesting a search for an accessible link of a heterogeneous network different from a current network of the mobile terminal for performing the handover, receiving the request in the upper layer of the mobile terminal via the unified interface, and requesting a scan of the heterogeneous network via the unified interface to determine the presence of the accessible link for performing the handover. Preferably, the step of requesting the scan is performed in the upper layer. Preferably, the heterogeneous network is periodically scanned. Preferably, the unified interface is a media independent handover function (MIHF) entity. Preferably, the upper layer comprises an upper management entity for managing homogeneous and heterogeneous network links associated with the mobile terminal. In one aspect of the present invention, the method further comprises discovering the accessible link of the heterogeneous network, informing the upper layer of the accessible link via the unified interface, and establishing a connection with the accessible link. Preferably, the step of informing the upper layer of the accessible link via the unified interface comprises informing the upper layer of a signal quality of the accessible link of the heterogeneous network. Preferably, the signal quality comprises at least one of a signal to interference plus noise ratio (SINR) and a received signal strength indication (RSSI). In another aspect of the present invention, the method further comprises scanning the current network for an accessible link prior to requesting the search for the accessible link of the heterogeneous network different from the current network. Preferably, the step of requesting the search for the accessible link of the heterogeneous network different from the current network occurs when the presence of an accessible link in the homogeneous network is not detected. In a further aspect of the present invention, the step of requesting a search comprises at least one of identifying a source for where the request is generated, identifying a destination for where the request is to be transmitted, and providing an identification of the mobile terminal. In yet another aspect of the present invention, the step of requesting a scan comprises at least one of identifying a source for where the request is generated, identifying a destination for where the request is to be transmitted, and providing an identification of the mobile terminal. In accordance with another embodiment of the present invention, a mobile terminal for supporting media independent handover to a heterogeneous network terminal comprises a unified interface to an upper layer of the mobile terminal for managing messages to and from at least one of a homogeneous network and a heterogeneous network and means for requesting a scan of a heterogeneous network different from a current network of the mobile terminal via the unified interface to determine the presence of an accessible link of the heterogeneous network for performing the handover. In accordance with another embodiment of the present invention, a mobile terminal for supporting media independent handover to a heterogeneous network comprises a unified interface to an upper layer of the mobile terminal for managing messages to and from at least one of a homogeneous network and a heterogeneous network, means for scanning a current network for a link different from a current link of the mobile terminal for performing the handover, means for reporting availability status of the link different from the current link of the current network, means for receiving the report in an upper layer of the mobile terminal via the unified interface, and means for requesting a scan of a heterogeneous network different from the current network via the unified interface to determine the presence of an accessible link of the heterogeneous network for performing the handover when the link of the current network different from the current link is not available. In accordance with another embodiment of the present invention, a mobile terminal for supporting media independent handover to a heterogeneous network comprises a unified interface to an upper layer of the mobile terminal for managing messages to and from at least one of a homogeneous network and a heterogeneous network, means for requesting a search for an accessible link of a heterogeneous network different from a current network of the mobile terminal for performing the handover, means for receiving the request in the upper layer of the mobile terminal via the unified interface, and means for requesting a scan of the heterogeneous network via the unified interface to determine the presence of the accessible link for performing the handover. It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. Features, elements, and aspects of the invention that are referenced by the same numerals in different figures represent the same, equivalent, or similar features, elements, or aspects in accordance with one or more embodiments. FIG. 1 illustrates a general media independent handover function (MIHF) reference model. FIG. 2 is a structural diagram illustrating a conventional protocol layer of a multi-mode mobile terminal. FIG. 3 is a block diagram illustrating a conventional mobile-terminal function entity and a conventional network function entity, each of which includes an MIH function. FIG. 4 is a structural diagram illustrating a conventional trigger model. FIG. 5 shows conventional triggers generated until a new link is established when a quality of a link to which a mobile terminal is connected is deteriorated. FIG. 6 is a structural diagram illustrating a “Link Event” model and an “MIH Event” model in accordance with one embodiment of the present invention. FIG. 7 is a structural diagram illustrating a “Remote Link Event” model in accordance with one embodiment of the present invention. FIG. 8 is a structural diagram illustrating a “Remote MIH Event” model in accordance with one embodiment of the present invention. FIG. 9 is a structural diagram illustrating an “MIH command” model and a “Link command” model in accordance with one embodiment of the present invention. FIG. 10 is a structural diagram illustrating a “Remote MIH command” model in accordance with one embodiment of the present invention. FIG. 11 is a structural diagram illustrating a “Remote Link Command” model in accordance with one embodiment of the present invention. FIG. 12 is a structural diagram illustrating a protocol stack of a multi-mode mobile terminal in accordance with a preferred embodiment of the present invention. FIG. 13 is a flow chart illustrating an inventive procedure in accordance with a preferred embodiment of the present invention. FIG. 14 is a structural diagram illustrating a protocol stack of a multi-mode mobile terminal in accordance with another preferred embodiment of the present invention. FIG. 15 is a flow chart illustrating another inventive procedure in accordance with another preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to allowing a multi-mode mobile terminal to effectively perform a handover function between heterogeneous networks. Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. Preferably, a conventional event trigger model is extended to an event service and a command service. The event service is classified into an MIH event and a link event. The command service is classified into an MIH command and a link command. FIG. 6 is a structural diagram illustrating a “Link Event” model and an “MIH Event” model in accordance with one embodiment of the present invention. Referring to FIG. 6 , the MIH event is indicative of an event transmitted from the MIH to either the upper management entity or the upper layer, and corresponds to conventional event triggers. The link event is indicative of an event transmitted from a lower layer (i.e., a MAC layer or a physical (PHY) layer) to the MIH, and uses primitives for use in individual interface MAC- or physical-layers. FIG. 7 is a structural diagram illustrating a “Remote Link Event” model in accordance with one embodiment of the present invention. Referring to FIG. 7 , if a lower layer contained in a local stack generates an event and transmits the event to the MIH contained in a local stack, the MIH of the local stack transmits the aforementioned event to the MIH of a remote stack. Similarly, a lower layer contained in the remote stack generates an event and transmits the event to the MIH function of the remote stack, and the MIH function of the remote stack transmits a trigger signal to the MIH function of the local stack. FIG. 8 is a structural diagram illustrating a “Remote MIH Event” model in accordance with one embodiment of the present invention. Referring to FIG. 8 , the MIH function of the local stack generates a remote MIH event, and transmits the remote MIH event to a counterpart MIH function contained in a remote stack. The MIH function of the remote stack transmits the received event to an upper management entity or an upper layer contained in the remote stack. Similarly, the MIH function of the remote stack generates an event to the MIH function of the local stack, and the MIH function of the local stack transmits the aforementioned event to the upper layer of the local stack. FIG. 9 is a structural diagram illustrating an “MIH command” model and a “Link command” model in accordance with one embodiment of the present invention. Referring to FIG. 9 , the MIH command is generated from the upper management entity or the upper layer, and is then transmitted to the MIH function, such that it commands the MIH to perform a specific task. The link command is generated from the MIH function, and is then transmitted to the lower layer, such that it commands the lower layer to perform a specific task. FIG. 10 is a structural diagram illustrating a “Remote MIH command” model in accordance with one embodiment of the present invention. Referring to FIG. 10 , the remote MIH command is generated from the upper management entity or the upper layer, and is then transmitted to the MIH function. The MIH function transmits the received MIH command to a counterpart MIH function contained in a remote stack. Similarly, the upper layer contained in the remote stack generates a command and transmits the command to the MIH function of the remote stack, and the MIH function of the remote stack transmits the command to the MIH function of the local stack. FIG. 11 is a structural diagram illustrating a “Remote Link Command” model in accordance with one embodiment of the present invention. Referring to FIG. 11 , the MIH function contained in the local stack generates a remote link command, and transmits the remote link command to a counterpart MIH function contained in a remote stack. The MIH function contained in the remote stack transmits the remote link command to a lower layer contained in the remote stack. Similarly, the MIH function contained in the remote stack generates a command, and transmits the command to the MIH function of the local stack, and the MIH function of the local stack transmits the command to the lower layer of the local stack. FIG. 12 is a structural diagram illustrating a protocol stack of a multi-mode mobile terminal in accordance with a preferred embodiment of the present invention. Preferably, the aforementioned multi-mode is associated with either an interface between a broadband wireless access network system and a wireless LAN, or an interface between the broadband wireless access network system and a cellular network system. Referring to the reference character (a) of FIG. 12 , if the multi-mode mobile terminal periodically performs a scanning operation in a wireless LAN mode, an MIH function entity transmits a periodic scanning command to either a second layer (i.e., a MAC layer) of a broadband wireless access network system mode or a second layer (i.e., a MAC layer) of a 3G cellular mobile communication mode. Preferably, the MIH generates a scanning command link event “Scan_indication” to initiate other scanning operations of MAC/PHY layers, and transmits the “Scan_indication” event. Preferably, the link command transmitted from the MIH to lower MAC layers uses primitive information for use in individual interface networks. A variety of primitives can be used, for example, “M.scanning.request” information of the broadband wireless access network, “MLME-SCAN.request” information of the wireless LAN, and “CPHY-Measurement-REQ” or “CMAC-Measurement-REQ” information of the 3GPP, etc. Referring to the reference character (b) of FIG. 12 , if the multi-mode mobile terminal currently operated in the wireless LAN mode has no signal (i.e., no link) to be handed over in a homogeneous network, the MAC layer of the currently-operated wireless LAN mode generates a link search request event “Scan_Other_Link” indicating that no signal (i.e., no link) is detected from a homogeneous network, and transmits the “Scan_Other_Link” event to the MIH function entity. In this case, used primitives may correspond to primitive parameters which can indicate no available Point of Attachment (POA) in “MLME-SCAN.confirmation” information over a wireless LAN. The MIH function entity receiving the “Scan_Other_Link” event generates a scanning command “Scan_Indication” to initiate other scanning operations of MAC/PHY layers, such that it transmits the “Scan_indication” command to either a second layer (i.e., a MAC layer) of the IEEE 802.16 mode for use in the mobile terminal or a second layer (i.e., a MAC layer) of the 3G cellular mobile communication mode for use in the mobile terminal. For another example for initiating scanning operations of other modes, the MIH function generates a link command, such that it commands a second lower layer (i.e., a MAC layer) to initiate different scanning operations of the MAC/PHY layers. Preferably, primitives for use in individual interface networks are used as link commands. Preferably, a variety of primitives can be used, for example, “M.scanning.request” information of the broadband wireless access network, and “MLME-SCAN.request” information of the wireless LAN, etc. FIG. 13 is a flow chart illustrating a process for allowing the MIH to command the scanning operation in accordance with a preferred embodiment of the present invention. Referring to FIG. 13 , a MAC layer (i.e., LL old) of a current link to which a multi-mode mobile terminal is connected generates a “Link_Going_Down” trigger event when a signal quality of the current link is deteriorated, and transmits the “Link_Going_Down” trigger event to the MIH function entity. Preferably, the MIH function entity then performs a scanning process to determine whether a link accessible by a homogeneous network is present in the MAC layer of the current link at step S 61 . If no link accessible by the homogeneous network is detected when the MAC layer of the current link is scanned at step S 62 , the MAC layer of the current link generates a link search request event “Scan_otherlink_request”, and transmits the “Scan_otherlink_request” event to the MIH function entity at step S 63 . The MIH function entity then receives the “Scan_otherlink_request” event from the MAC layer of the current link, generates a scanning command link command “Scan_indication”, and transmits the “Scan_indication” command to a MAC layer (i.e., LL New) of a broadband wireless access network mode or a cellular mobile communication mode, such that it can command the “LL New” layer to scan an accessible heterogeneous link at step S 64 . Provided that the MAC layers of other modes different from the currently-connected mode perform the scanning process at step S 65 , and detect an accessible heterogeneous network link at step S 66 , the MAC layers of the above other modes control the aforementioned MIH function entity to trigger a “Link_Available” event at step S 67 . The MAC layers then establish a connection state with the aforementioned new accessible heterogeneous link. Preferably, signal quality information, such as Received Signal Strength Indication (RSSI) and Signal to Interference plus Noise Ratio (SINR), of a corresponding link may be included in the “Link_Available” event such that the “Link_Available” event including RSSI and SINR may be transmitted to a destination at steps S 68 ˜S 69 . FIG. 14 is a structural diagram illustrating a protocol stack of a multi-mode mobile terminal in accordance with another preferred embodiment of the present invention. In more detail, FIG. 14 shows an example in which an upper management entity commands the scanning operation. Preferably, the aforementioned multi-mode is associated with either an interface between a broadband wireless access network system and a wireless LAN, or an interface between the broadband wireless access network system and a cellular network system. Referring to the reference character (a) of FIG. 14 , if the multi-mode mobile terminal periodically performs a scanning operation in a wireless LAN mode (i.e., the IEEE 802.11 mode), an upper management entity transmits a periodic scanning command to either a second layer (i.e., a MAC layer) of a broadband wireless access network mode (i.e., the IEEE 802.16 mode) or a second layer (i.e., a MAC layer) of a 3G cellular mobile communication mode via the MIH. Preferably, the upper management entity generates an MIH command “Scan_indication” to initiate other scanning operations of MAC/PHY layers, and transmits the “Scan_Indication” event to the MIH. Preferably, the MIH receiving the MIH command generates link commands, and commands lower MAC layers to perform the scanning operation. The link commands transmitted from the MIH to the lower MAC layers use primitive information for use in individual interface networks. A variety of primitives can be used, for example, “M.scanning.request” information of the broadband wireless access network, and “MLME-SCAN.request” information of the wireless LAN, etc. Referring to the reference character (b) of FIG. 14 , if the multi-mode mobile terminal currently operating in the wireless LAN mode (i.e., the IEEE 802.11 mode) has no signal (i.e., no link) to be handed over in a homogeneous network, the MAC layer of the currently-operated wireless LAN mode generates a link event indicating that no signal (i.e., no link) is detected from the homogeneous network, and transmits the link event to the MIH function entity. Preferably, used primitives may correspond to “MLME-SCAN.confirmation” primitive which can indicate no available Point of Attachment (POA) in the “MLME-SCAN.confirmation” primitive using expressible primitive parameters of the wireless LAN. The MIH receiving the aforementioned “MLME-SCAN.confirmation” primitive generates a “Scan Other Link” event indicative of the MIH event, and transmits the “Scan Other Link” event to the upper management entity. The upper management entity receiving the MIH event generates a “Scan_Indication” event for commanding the MIH to scan other available POAs, and transmits the “Scan_Indication” event to the MIH. The MIH then generates a link event for commanding a second lower layer (i.e., a MAC layer) to scan MAC/PHY layers. FIG. 15 is a flow chart illustrating another inventive procedure in accordance with another preferred embodiment of the present invention. In more detail. FIG. 15 is a flow chart illustrating a process for allowing the upper management entity to command the scanning operation in accordance with one embodiment of the present invention. Referring to FIG. 15 , a MAC layer (i.e., LL old) of a current link to which a multi-mode mobile terminal is connected generates a “Link_Going_Down” trigger event when a signal quality of the current link is deteriorated, and transmits the “Link_Going_Down” trigger event to the upper management entity via the MIH function entity. In this case, the upper management entity performs a scanning process to determine whether a link accessible by a homogeneous network is present in the MAC layer of the current link at step S 71 . If no link accessible by the homogeneous network is detected when the MAC layer of the current link is scanned at step S 72 , the MAC layer of the current link generates a link event indicating that no signal (i.e., no link) is detected from the homogeneous network, and transmits the generated link event to the MIH function entity. Preferably, used primitives may correspond to “MLME-SCAN.confirmation” primitive. The “MLME-SCAN.confirmation” primitive can indicate no available POA in the aforementioned primitive using expressible primitive parameters of a corresponding wireless LAN. The upper management entity receiving the aforementioned “Scan_otherlink_request” primitive at step S 73 generates a “Scan_Indication” command acting as the MIH command in order to command the scanning operation. The upper management entity then transmits the “Scan_indication” command to the MIH, and transmits the “Scan_indication” command to a MAC layer (i.e., LL New) of the broadband wireless access network mode or a MAC layer (i.e., LL New) of the 3G cellular mobile communication mode, such that it commands individual “LL New” layers of individual modes to scan an accessible heterogeneous network link at step S 74 . Provided that the MAC layers of other modes different from the currently-connected mode perform the scanning process at step S 75 , and detect an accessible heterogeneous network link at step S 76 , the MAC layers of the above other modes control the aforementioned MIH function entity to trigger a “Link_Available” event at step S 77 . The MAC layers then establish a connection state with the aforementioned new accessible heterogeneous link at steps S 78 ˜S 79 . Preferably, signal quality information (i.e., RSSI and SINR) of a corresponding link may be included in the “Link_Available” event, such that the “Link_Available” event including RSSI and SINR may be transmitted to a destination. The following Tables 8 and 9 exemplarily show “Scan_otherlink_request” associated with an event service and “Scan_indication” associated with a command service. In more detail, the following Tables 8 and 9 exemplarily show “Scan_otherlink_request” and “Scan_indication” trigger event parameters. TABLE 8 Name Type Description EventSource EVENT_LAYER_TYPE Source at which event occurs EventDestination EVENT_LAYER_TYPE Destination to which event is to be transmitted MacMobileTerminal MAC Address MAC address of Mobile Terminal TABLE 9 Name Type Description CommandSource COMMAND_LAYER_TYPE Source at which command occurs CommandDestination COMMAND_LAYER_TYPE Destination to which command is to be transmitted MacMobileTerminal MAC Address MAC address of Mobile Terminal The following Table 10 shows a signal transmission example wherein RSSI and SINR indicative of signal quality information associated with a link are added to the “Link_Available” event, such that the resultant “Link_Available” event is transmitted to a destination. TABLE 10 Name Type Description EventSource EVENT_LAYER_TYPE Source at which event occurs EventDestination EVENT_LAYER_TYPE Destination to which event is to be transmitted MacMobileTerminal MAC Address MAC address of Mobile Terminal MacNewAccessRouter MAC Address MAC address of old access router MacOldAccessRouter MAC Address MAC address of new access router SINR Signal to Interference plus Noise Ratio (SINR) RSSI Received Signal Strength Indication As apparent from the above description, a mobile terminal and a method for performing a handover of the mobile terminal in accordance with embodiments of the present invention can effectively support a handover between heterogeneous networks in a multi-mode mobile terminal. Although the present invention is described in the context of mobile communication, the present invention may also be used in any wireless communication systems using mobile devices, such as PDAs and laptop computers equipped with wireless communication capabilities. Moreover, the use of certain terms to describe the present invention should not limit the scope of the present invention to certain type of wireless communication system, such as UMTS. The present invention is also applicable to other wireless communication systems using different air interfaces and/or physical layers, for example, TDMA, CDMA, FDMA, WCDMA, etc. The preferred embodiments may be implemented as a method, apparatus or article of manufacture using standard programming and/or engineering techniques to produce software, firmware, hardware, or any combination thereof. The term “article of manufacture” as used herein refers to code or logic implemented in hardware logic (e.g., an integrated circuit chip, Field Programmable Gate Array (FPGA), Application Specific Integrated Circuit (ASIC), etc.) or a computer readable medium (e.g., magnetic storage medium (e.g., hard disk drives, floppy disks, tape, etc.), optical storage (CD-ROMs, optical disks, etc.), volatile and non-volatile memory devices (e.g., EEPROMs, ROMs, PROMs, RAMs, DRAMs, SRAMs, firmware, programmable logic, etc.). Code in the computer readable medium is accessed and executed by a processor. The code in which preferred embodiments are implemented may further be accessible through a transmission media or from a file server over a network. In such cases, the article of manufacture in which the code is implemented may comprise a transmission media, such as a network transmission line, wireless transmission media, signals propagating through space, radio waves, infrared signals, etc. Of course, those skilled in the art will recognize that many modifications may be made to this configuration without departing from the scope of the present invention, and that the article of manufacture may comprise any information bearing medium known in the art. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

The present invention relates to supporting media independent handover of a mobile terminal to a heterogeneous network. Preferably, the present invention establishes a unified interface to an upper layer of the mobile terminal for managing messages to and from at least one of a homogeneous network and a heterogeneous network. Furthermore, the present invention requests a scan of a heterogeneous network different from a current network of the mobile terminal via the unified interface to determine the presence of an accessible link of the heterogeneous network for performing the handover.

BACKGROUND OF THE INVENTION The invention relates to vacuum cleaners, particularly hand-held vacuum cleaners. More particularly, the invention relates to vacuum cleaners of the type in which the space accommodating the drive motor is separate from the interior of the blower unit, so that the dust-laden air passing through the blower unit will not contact the drive motor. Vacuum cleaners of this general type are known. It is known to take the housing frame of such a vacuum cleaner and spray it around with hard foam material, the outer skin being made of a flexible material. At the same time, the motor and the blower unit are secured onto the housing frame and encased in hard foam material. The foam material in the vicinity of the air discharge outlet should be of larger pore size than elsewhere, in order to permit the sound-muffled and filtered air to leave the housing at this location. This known expedient is disadvantageous. Despite the purification of the air by means of a filter bag, fine dust particles are carried along and pass, together with the motor cooling air, over the drive motor. Because the large-pore-sized foam of the discharge outlet region of the housing acts as a supplemental after-connected filter, these fine particles become deposited in the interstices between the foam pores and gradually damp the through-flow of air. This action adds to the already present disadvantage that the expedient of direct encasing in foam material impedes the flow of air, to begin with. After a long period of use, the requisite cooling action for the motor no longer occurs. It is also known to separate the part of the interior space of the housing containing the motor unit from the part containing the blower unit. This is done to separate the dust-laden air flow of the blower unit from the cooling air flow for the motor unit. The motor is provided with a separate impeller for sucking in ambient air, and such air is passed over the motor to cool it and then discharged back into the atmosphere. The air passing through the blower unit, on the other hand, is sucked into the vacuum cleaner housing through an altogether different and independent opening and then discharged therefrom through another opening likewise independent from the discharge opening for the motor cooling air. A disadvantage of this known expedient is that cool ambient air must be continually sucked into contact with the motor and then, after it becomes heated as a result of such contact and laden with carbon dust discharged from the motor, returned to the outside. Additionally, this system can be used in vacuum cleaners only when inlet filters are employed. SUMMARY OF THE INVENTION It is a general object of the invention to provide a sound-muffled vacuum cleaner in which the space for the motor unit is separate from the space for the blower unit, but wherein the cooling of the motor unit does not necessitate the continual sucking of cool ambient air into contact with the motor followed by its return to the outside. It is another object to resort to a closed-volume closed flow circuit for the motor cooling air, with the circulating air in this closed flow circuit being continually regenerated and cooled. These objects, and others which will become more understandable from the description, below, of a preferred embodiment, can be met, according to one advantageous inventive concept by providing separate non-communicating spaces for the blower unit and for the motor unit, with the spaces being in heat-exchanging relationship with each other. In this way, the dust-laden air passing through the blower unit space does not contact the motor unit in the motor unit space, but nevertheless serves to cool the air in the motor unit space and thereby the motor itself. According to a further concept of the invention, the motor unit space has the form of air passages together forming a closed flow circuit for continually recirculated cooling air, with heat-exchanging means being provided for effecting a transfer of heat from the air in the motor unit space to the dust-laden air travelling through the blower unit space, and with dust-removing means being provided for continually removing from the air in the motor unit space the carbon dust being discharged by the motor into such air during motor operation. To make it possible for the vacuum cleaner housing to be closed on all sides and open only where the dust-laden air is to be sucked in and discharged, the closed flow circuit for the motor cooling air is separated from the ambient atmosphere and has no communication with it, with the air flow in the closed flow circuit being a fixed-volume forced flow. It should be noted that the expression closed flow circuit refers to the interconnection of the cooling passages, i.e., that they formed a loop around which air can flow; the word closed in the expression closed flow circuit does not of itself indicate that the flow circuit is to have no communication with the ambient environment, although this is in fact preferred. Advantageously, the heat exchange between the dust-laden air travelling through the blower unit and the motor cooling air travelling in the cooling air circuit is effected by means of cooling fins or projections provided on the external skin of the blower unit, preferably of one piece with such external skin. An electric motor having carbon brushes, or the equivalent, continuously discharges fine carbon dust during its operation. If the space containing the motor unit has the form of a closed flow circuit, and if it is desired to continually remove the carbon dust from the air circulating in such circuit, then it is contemplated according to the invention to provide dust-removing means including two distinct parts. One part is provided on the motor cooling-air impeller itself and has the form of catching surfaces and/or structures for catching and collecting the fine carbon dust. The other part is preferably a filter arrangement located downstream of the motor unit, for catching and collecting the fine dust not caught by the dust-removing means on the cooling-air impeller. Advantageously, the filter arrangement does not block the cooling-air circulation; i.e., the circulating cooling air is not constrained to pass through the filter arrangement. Instead, the filter arrangement is located alongside the flowing cooling air, so located that the warmed and carbon-dust-laden air discharged by the cooling-air impeller of the motor unit directly impinges upon the filter arrangement, without actually having to pass through the filter arrangement. This affords the advantage of dust filtration, without increasing the flow resistance against which the motor unit need work. Also to avoid unnecessary loading of the motor unit, the air passages forming the closed flow circuit upstream and downstream of the motor have cross-sectional areas such and include bends so few in number and dull in shape as to minimize the resistance to air flow. Advantageously, the separation of the warm air passage or passages (those located upstream of the main heat-exchanging means) from the cool air passage or passages (those located downstream of the main heat-exchanging means) is effected by means of separating surfaces or edges molded integral with the exterior surface of the blower unit and/or the interior surface of the housing accommodating the blower unit and the drive unit. In order that the heat-exchanging effect be as great as possible, it is contemplated not merely to provide cooling fins or the like on for example the main housing of the blower unit, but even to make the inlet and outlet conduits of the blower unit of thermally conductive material so that heat exchange can occur as between air inside and surrounding them too. Furthermore, it is contemplated to have all heat-exchanging surfaces of the blower unit in thermally conductive connection with one another as well. The carbon dust discharged by the electric drive motor should be removed from the circulating air in the closed cooling-air flow circuit as near as possible to the point at which it enters the flow, i.e., as near as possible to the point of discharge from the motor. This is to prevent the uncontrolled development of deposits of carbon dust along the surfaces bounding the cooling-air flow circuit, and especially to prevent such deposits upon the heat-exchanging fins and other heat-exchanging surfaces since such deposits could detract from the cooling action. Therefore, according to the invention, it is preferred that the carbon dust removing means be provided directly adjacent the warm air discharge location of the motor unit. The means for removing the carbon dust should remove it from the cooling air passing over the warm surfaces of the motor. To this end, the invention further contemplates providing the motor-unit cooling-air impeller itself with means, on the radially outward extending blades of the impeller, for catching and collecting carbon dust. Preferably, such means has the form of a collar which connects together the outer ends of the blades, with the collar having an angled transverse cross-sectional configuration. The collar can have a deflector portion and a collector portion, for respectively guiding carbon-dust-laden air and collecting carbon dust in the form of a growing deposit. Advantageously, the deflector portion extends generally parallel to the air travel direction whereas the collector portion is arranged relative thereto at an angle of at least 90°. Advantageously, the cooling-air impeller blades are provided with dust collecting recesses capable of accumulating a considerable deposit of carbon dust. The just-described means on the motor unit cooling-air impeller by itself will not suffice to remove all the carbon dust in the circulating cooling air. Accordingly, the invention contemplates the use of a supplemental filter arrangement. Advantageously, the supplemental filter arrangement is one through which the circulating cooling air need not actually pass, but against which the cooling air will merely impinge. One advantage that can be achieved utilizing various ones of the aforementioned inventive concepts is the formation of a completely closed housing around the motor and blower units, it being possible to make the housing of elastic material. If the motor unit space is a closed flow circuit for circulating cooling air, and if it is furthermore at no point in communication with the exterior of the housing, then the noise of the motor can be muffled to a very considerable extent, although it becomes necessary to continually remove the discharged carbon dust from the cooling-air circuit. Another advantage resulting from the use of various ones of the aforementioned inventive concepts is that the dimensions of the vacuum cleaner can be kept quite small, especially when the blower unit passage for dust-laden air passes through but does not communicate with the closed circuit for cooling air. Also, when a closed flow circuit not communicating with the housing exterior is employed, the operation of the vacuum cleaner is by comparison with similar older designs more hygienic, inasmuch as the carbon dust discharged by the electric drive motor during vacuum cleaner operation will not be discharged into the air in the room being cleaned. The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a longitudinal section through the main housing of vacuum cleaner, showing the closed flow circuit for the cooling air for the motor unit, the heat-exchange arrangement and the carbon-dust-removing arrangement; FIG. 2 is a plan view of the elastic-material housing of FIG. 1, with the blower unit and motor unit removed; FIG. 3 is a view corresponding to FIG. 2, but with the blower unit and motor unit inserted in place, showing how surfaces of the housing interior and surfaces of the exterior of the blower unit cooperate to separate the interior of the housing into two air passage sections; FIG. 4 shows the heat-exchanging or cooling fins mounted on the blower unit housing and also the heat-exchanging inlet and outlet conduits of the blower unit; FIG. 5 depicts a portion of the arrangement of FIG. 1 on a somewhat greater scale, showing in greater detail the carbon dust separating arrangement on the motor and the impingement filter on the wall of the cooling-air flow circuit; FIG. 6 is a top view of the motor unit cooling-air impeller, provided with means for catching and collecting carbon dust discharged by the motor during its operation; FIG. 7 is a transverse section through the impeller of FIG. 6, showing clearly the catching and separating portions; and FIG. 8 is a detail of the impeller, showing the size and orientation of one of the dust-collecting recesses on the radial outer end of an impeller blade. DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 depicts a vacuum cleaner housing 30 closed on all sides and provided with a matching cover 32. The interior 12 of the vacuum cleaner housing 30 contains the working aggregate 31 of the vacuum cleaner, including a motor unit 8 and a blower unit. The blower unit is comprised of a blower housing 6 containing a (non-illustrated) impeller, an inlet or suction conduit 20, and an outlet or discharge conduit 19. The motor unit 8 is located outside of the blower unit, so that the dust-laden air sucked into the blower unit at 20 and discharged (for instance into a dust receptacle) from 19 does not reach the motor unit 8. In other words, the interior 12 of housing 30 is divided into a first space and a second space which passes through the first space but does not communicate with the first space. The second space is constituted by the interior of the blower unit, including the interior of the inlet conduit 20, blower housing 6 and outlet conduit 19. The first space is the space inside housing 1 surrounding the blower unit and containing the motor unit 8. The exterior surfaces of the blower unit and the interior surfaces 1 of the housing together define a closed flow circuit 4 for the circulation of cooling air for the motor unit 8. The closed flow circuit 4 surrounds the blower unit and does not communicate with the exterior of the vacuum cleaner housing. Blower housing 6 is provided with a plurality of cooling fins together forming a heat-exchanging arrangement 5. The portion of the closed flow circuit 4 downstream of the heat-exchanging arrangement 5 constitutes a cold air passage 15, whereas the portion of the closed flow circuit 4 upstream of the heat-exchanging arrangement 5 constitutes a warm air passage 14. The direction of flow of cooling air in closed flow circuit 4 is indicated by the counterclockwise travelling arrows. The path taken by the air is determined in part by separating edges or surfaces 16 molded integral with the material of the interior of the housing and/or the exterior of the blower unit. In FIG. 1, a broken line is provided to show where the separating edge or surface 16 establishes a separation between the warm and cool air passages. In FIG. 3, which shows the blower unit in place in the housing, it will be seen that separating surfaces 16 of the blower unit and housing contact each other, to subdivide the space surrounding the blower unit into the warm and cool air passages 14 and 15. There can be additional engagement of this type along the outlet conduit 19, as indicated by the upper portion of the broken line in FIG. 1. For example, the outlet conduit 19 could be provided with outwardly extending fins corresponding to the upper portion of the broken line at 16, with the edges of these fins bearing against the inner surface of the housing and constituting separating surfaces or edges. The motor unit 8 is provided with an impeller 9 in addition to the (non-illustrated) impeller located inside the blower housing 6. Both impellers are driven by the motor unit 8, but it is clear that impeller 9 is located in the first space whereas the (non-illustrated) impeller of the blower unit is located in the second space. The impeller 9 serves to maintain the cooling air in the closed flow circuit 4 in continuous circulation during operation of motor unit 8. As cooling air circulates in circuit 4, driven by impeller 9, it passes over the cooling fins 6b on the exterior 6a of the blower housing 6, so that the heat imparted to the cooling air by the motor unit 8 will in turn be imparted to the dust-laden air passing through the blower unit 20, 6, 19. To maximize the heat-exchanging efficiency, heat exchange occurs not only at the cooling fins 6b but additionally all along the surfaces of inlet conduit 20 and outlet conduit 19, and also all along the surface 6a of blower housing 6. To this end, the conduits 19, 20 and the housing 6 are preferably all made of a thermally conductive material, such as a metal, and are all connected to one another in thermally conductive manner. The flow circuit 4 defined by the interior surface 1 of the housing and the exterior surface of the blower unit does not communicate with the exterior of the housing. As a result, the continuously recirculated air in circuit 4 must not only be continuously cooled, but also continuously regenerated. This is because carbon dust is continuously discharged from the carbon brushes of the electric motor of motor unit 8. If this carbon dust is not removed, it may interfere with motor operation. In any event, it would deposit itself upon the walls of the cooling-air circuit 4 and in particular on the aforedescribed heat-exchanging surfaces, thereby reducing the cooling action for the motor unit 8. To continually remove such discharged carbon dust from the motor cooling air in circuit 4, use is made of dust-removing means including means 7 on the cooling-air impeller 9 itself and further filter means 11, explained with reference to FIG. 5. FIG. 5 shows the arrangement of FIG. 1, on a larger scale. The cooling air passes over the motor unit 8, driven around circuit 4 by cooling-air impeller 9. The impeller 9 is located so as to be as close as possible to the place from which the carbon dust from the motor carbon brushes is discharged. Means is provided on the impeller 9 itself to catch and collect a great part of the discharged carbon dust, before such carbon dust can reach the aforedescribed heat-exchanging surfaces; the dust collecting means on impeller 9 will be discussed below, in connection with FIGS. 6 - 8. However, the dust removing means 7 on impeller 9 itself is not sufficient to remove all the discharged carbon dust. Accordingly, there is provided, just downstream of cooling-air impeller 9 a filter arrangement 11. The filter arrangement 11 is advantageously comprised of a body of porous material implanted in the wall of the flow circuit 4. However, instead of using a discrete filter body, it would be possible to simply make the wall of the flow circuit 4 of large-pore porous character at at least this location, i.e., by suitable choice of the composition of the surface portion 18 of the walling 17 of the housing. Filter arrangement 11 is arranged at an impingement location 28 such that the incompletely cleaned carbon-dust-laden air discharged by cooling-air impeller 9 will impinge directly against the filter arrangement 11. The residual carbon dust in this cooling air will be trapped in the porous structure of filter arrangement 11, so that the cooling air downstream of the filter arrangement will be substantially carbon-dust-free, thereby presenting no threat to the heat-exchanging surfaces. An important advantage of so positioning the filter arrangement 11 is that the cooling air is not actually constrained to pass through the filter arrangement; instead it is merely discharged against the filter arrangement. This serves to avoid an increase in the flow resistance of the circuit 4, and thereby minimize the loading on motor unit 8 attributable to the maintenance of the cooling air in circulation. For the same reason, the cross-sectional area of the warm and cool air passages 14, 15 is selected so great, and the number and sharpness of the bends 13 so low as not to significantly add to the flow resistance of the cooling-air flow circuit 4. The principal carbon-dust-removing means is provided on the cooling-air impeller 9 itself, as shown in FIGS. 6, 7 and 8. Cooling-air impeller 9 is provided at the radially outward ends 23 of its impeller blades with a collar or ring 24. Ring 24 is of angled transverse cross-sectional configuration. The junction of the blade ends 23 and collar 24 is provided with dust-catching recesses 27. When the motor unit 8 operates, the cooling-air impeller 9 will turn at motor speed, and the warmed and carbon-dust-laden cooling air will move through the blades 22. The rotation of the blades will cause the dust particles of larger size to be accelerated radially outward, by centrifugal force. Such larger carbon dust particles impact against the guide portion 25 of the collar and are held thereagainst by centrifugal force. Meanwhile, the axially travelling air stream causes these carbon dust particles to slide axially along guide portion 25 towards collecting portion 26 of collar 24, where they very gradually form a deposit. To maximize the dust-catching and -collecting efficiency, the cooling-air impeller 9 is additionally provided with deep dust-collecting recesses 27 (see FIG. 8). As shown particularly clearly in FIG. 4, the cooling fins 5b of the heat-exchanging-arrangement 5 are disposed with such an orientation as to present the least possible resistance to air flow, again to minimize the load placed upon motor 8 in driving cooling-air impeller 9. It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above. While the invention has been illustrated and described as embodied in a vacuum cleaner, particularly a hand-held vacuum cleaner, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.

A housing in a vacuum cleaner is subdivided into a first space and a separate second space which does not communicate with the first space but is in heat-exchanging relationship with the first space. An impeller is located in the second space for sucking dust-laden air into one end of the second space and discharging it out the other. The drive motor for the impeller means is located in the first space. Thus, the drive means is not contacted by the dust-laden air passing through the second space but is nevertheless cooled by such dust-laden air.

CROSS-REFERENCE TO RELATED APPLICATIONS The present application is related to patent application Ser. No. entitled, "Computer with Graphic Interface," application Ser. No. 07/827,076, filed on the same day as the present application, Jan. 28, 1992, and application Ser. No. 08/240,098, a continuation of application Ser. No. 07/827,076, filed May 9, 1994, each owned now, and at the time of the invention, by the same assignee. FIELD OF THE INVENTION The present invention relates to the field of infrared communications; and more particularly, to digital communication systems based on transmission and reception of infrared signals. BACKGROUND OF THE INVENTION Widespread use of frequencies in the infrared band for communication by telemetry has been made. Using an infrared signal in a business or household environment, however, has been hampered by the large amount of background infrared radiation present. Thus, the uses of infrared communications has been limited to remote control devices for home entertainment systems and the like which are required to communicate a relatively small set of codes with significant redundancy, and do not require the ability to communicate large amounts of digital data at a high rate of speed. The problem of using infrared communication systems for high speed digital communications is further complicated by the desire to transmit data between battery operated hand-held devices, and a host computer system. These battery operated devices must be able to communicate with relatively low power consumption, therefore, making long high power infrared communication signals impractical. Therefore, it is desirous to have an infrared communication system, which utilizes relatively low power and communicates data at a high rate of speed, sufficient for transferring files of digital information between the hand-held computer and a host system. SUMMARY OF THE INVENTION In the present invention, the transmitter generates an infrared signal that represents a bit stream of binary data. Each binary signal generated by the transmitter has a set of infrared pulses representing one state of the binary signal and a second set of infrared pulses representing a second state of the binary signal. The pulses associated with each state of the binary signal have specific characteristics which enable the receiver to distinguish the transmitted signal from any background radiation. The specific characteristics of each set of pulses, therefore, create in essence a signature which can be recognized by the receiver as implemented within an ASIC. In one aspect of an invention, a sequence of bits of digital information are generated by a transmitter in which the first binary state of the bit is represented by a sequence of a first signature set of infrared pulses, and the second binary state of the bit is represented by a second signature set of infrared pulses. The signature sets of pulses are detected by a receiver in which an electrical signal is generated by the receiver in response to the detected pulses. The electrical signal is then filtered to detect the signature sets of pulses generated by the transmitter. The signature sets of pulses are then decoded to reconstitute the binary digital signal. In another aspect, the signature sets of pulses are communicated according to a specific communications protocol for high speed communication of digital data, at greater than 30,000 bits per second. Other aspects and advantages of the present invention can be seen upon review of the drawings, the detailed description and the claims which follow. BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a perspective view of a portable computer using the present invention. FIG. 2 is a functional block diagram of the computer of FIG. 1 according to the present invention. FIG. 3 is a diagram of the infrared communications receiver of the present invention FIG. 4 is a block diagram of the power management and biasing and main sub-circuits of the communications receiver. FIG. 5 is a schematic of the power management and biasing circuits of the receiver. FIG. 6 is a schematic of the log pre-amp, high-pass filter, balanced compression amplifier, pseudo-differential low-pass filter amplifier and VCVS high-pass filter amplifier circuits of the receiver. FIG. 7 is a schematic of the active band-pass filter, two quadrant voltage-to-logarithmic current convertor, peak detector, comparator, analog output stage, and digital output stage circuits of the receiver. FIG. 8 is a timechart showing pulse sets representing bit 1. FIG. 9 is a timechart showing the transmission of 31,250 bits in one second and sets of pulses representing binary 1 and 0. FIG. 10 is a block representation of a data packet. FIG. 11 is a stylized diagram showing the timing relationships between the peaks of signal PKT on the upper voltage axis and the "crossing" of signals PKO and PKC on the lower voltage axis. DETAILED DESCRIPTION A detailed description of a preferred embodiment of the present invention is given with reference to the figures. FIG. 1 shows a perspective view of the computer system. FIG. 2 is a functional block diagram of the computer. The computer according to the preferred embodiment of the present invention is an extendable, portable, text and graphics processing system, which is small enough to fit into a pocket, such as the standard size breast pocket of a man's suit coat. Inside the casing, data storage, data processing, display, user interface, and communications systems are packaged along with a power supply and storage system. FIG. 1 shows a perspective view of the casing tablet 10. The tablet 10 can easily fit into a breast pocket of a coat. The external features of the tablet 10 include a top surface 11, which is dominated by an opening exposing a liquid crystal display 12 with touch sensitive overlay 18. Also, the single mechanical user control switch, called the attention button 15, is provided on the top surface. The bottom surface (not shown) of the casing incorporates a battery cover for a back-up lithium battery storage, to provide for real time clock power and long term memory retention. Also, on the bottom surface of the casing, an acoustic port is provided through which sound produced by the speaker may emanate to a user. A infrared lens 19 on a first end 13 of the casing 10 provides an optical port 14 whereby the infrared emitter/detector pair can communicate with compatible peripheral devices. The placement of the optical port 14 is on the end opposite the battery pack 17. The optical port 14 will be covered by a plastic material, attached to the casing 10, which is optically transparent in the frequency range of the infrared system and optically opaque in the visible light spectrum. At the second end 16, a battery pack is connected to the tablet. The battery pack shown in FIG. 1 is adapted to hold four AAA batteries. Alternative battery pack designs, such as for AA batteries, could be adapted to fit with the tablet 10. FIG. 2 is a functional block diagram of the computer system which is mounted within the casing 10 of FIG. 1. The system includes battery pack 50, a touch sensitive transparent overlay 51, an LCD display screen 52, the infrared transmitter 53, and an infrared receiver 54. Also, an attention button 55 is included in the circuit. The processing capability of the computer is provided by microcontroller 56, memory controller 57, LCD controller 58, communication controller 59, and a variety of other elements as shown in the circuit. The microcontroller, such as the NATIONAL SEMICONDUCTOR HPC46003, is a central processing unit. The HPC has a UART on chip, which is used to support the communications system. The microcontroller 56 is coupled to the memory control circuit 57 across bus 60. The memory control circuit 57 provides an interface across memory bus 80 to the storage unit, designated generally by the reference number 61. The storage unit 61 includes static RAM 62 used for a display RAM, a bank of static RAM 63, a bank of ROM 64, and a connector 65 for an external memory cartridge. The memory controller 57 also manages the input from the touch screen 51 across input bus 81, in combination with the LCD controller 58. The LCD controller 58 manages display refresh and display buffer 62 management. The batteries 50 of the removable battery pack are coupled to a voltage regulator 66, such as the Intercell ICL 7665S or equivalent, which generates a regulated output voltage for powering the circuits. The primary power is supplied by power packs 50 which provide nominal unregulated 6 voltage DC. A secondary battery 67, or "retention" power source, provides long term power for retention of memory in volatile storage elements on the system. This is supplied, for instance, by a lithium battery, such as EVERREADY CR2032 or the equivalent. The back-up battery 67, is coupled through diodes 68 and 69 to the output of the voltage regulator 66 and to the RAM bank 63 and clock/calendar 90 to provide back-up voltage. A clock/calendar chip 90 is included, such as the INTERCELL ICM 7170, NSC DP8573, or equivalent. This chip includes a comparer alarm, whereby the CPU designated time month/day, hour/minute is used to generate a clock interrupt, or power on the CPU. When the system is on, the clock/calendar chip 90 is powered by the primary power source. When the system is off, this chip draws power from the back-up lithium battery. Overlay row and column decoders 70, 71 are connected between the memory controller 57 and the transparent overlay 51 across bus 81. The 4.5V regulated output of the voltage regulator 66 is coupled to a DC to DC converter 82 to supply negative bias voltage to the LCD display module 52. The communication control circuit 59 is connected to the memory controller 57 on serial lines 83 and 84, and through the memory controller to UART 85 coupled with the microcontroller 56. A crystal oscillator 73 is coupled to the memory controller 57 for providing a clock signal. Infrared emitter 53 and detector 54 are provided for communications with external equipment. The transmitter and receiver have peak power at or near a wavelength of 940 nanometers. A speaker 72 is coupled to the microcontroller 56. The system speaker 72 is capable of generating audible tones under control of the CPU. The system includes a socket 65, interfaced via the memory controller chip, whereby an external ROM or RAM, or hybrid ROM+RAM card may be electronically inserted. This system is compatible with a card such as the ITT CANNON STAR CARD. These ROM/RAM cards could be available as masked ROM, one time programmable ROM, E2PROM, S/RAM, or other memory devices. The touch screen 51 overlays the liquid crystal display. It is a transparent resistive overlay controlled by the memory control block 57. It provides 9 bit by 9 bit resolution across the LCD screen. Touching the pad presents a finite resistance across the X and Y directions of the pad. Electrodes are provided for the purpose of interconnections to measure these resistances. When no pressure is applied, a very large or infinite resistance is provided to the electrodes. The attention button 55 is implemented with an electronically separate section of the touchscreen and acts as single pole, single throw, normally open push button. The button 55 is mounted directly onto the top of the tablet casing. Actuation of the button is accomplished by using a custom plastic piece which fits into the casing. The switch activates the primary power system when the system is off. When the system is on, the switch provides an interrupt to the CPU via the memory controller 57. The computer system, when mounted within the casing 10 of FIG. 1, is a monolithic electronic assembly powered by the power packs. The power packs can be provided in any number of configurations, based on variations of battery size. For instance, battery packs could be configured for four AAA alkaline batteries, four AA alkaline batteries, five AA nickel-cadmium batteries, or for attachments to any number of external power supplies. The user interface consists of the liquid crystal display 52 under the touch screen, the attention button 55, and an input control program as described below. The casing 10 and display 52 is designed to be held and operated in either a portrait or landscape orientation by either a right or left handed person. The user requests an "interactive power-on" via the attention button 55. Pressing this button will signal a power-up of the processing system. A power-on can also be initiated by reaching a specific date/time within the clock/calendar chip 90. When powering on automatically, the apparatus will inform the user via an alarm tone through the speaker and an event specific screen illustrating the reason for the power-on. The primary user interface on the apparatus is provided by "soft function-keys" as implemented using the bit mapped liquid crystal display 52 and an associated transparent touch sensitive overlay 51. The processing system is powered down under software control according to a power management scheme. Low battery capacity is detected by the system for both the primary and long term retention cells, and reported to the user under software control. As a battery saving feature, the unit will automatically turn itself to a low power data retention mode after the preset user adjusted interval, if no user command selection is made. Peripheral communication is provided by modulated infrared communication media exchanging information with peripheral devices, such as personal computers, modems, keyboards, and the like. The circuit provides a minimum of 256 kilobytes of 100 nanosecond OTP ROM. This ROM contains the code necessary to perform the basic functions and hardware diagnostics, and store necessary character fonts, hard coded displays, icons, symbols, et cetera. The ROM is accessed in 32 blocks of 8 kilobytes each, under control of the memory controller chip. A minimum of 128 kilobytes of non-volatile read/write memory (SRAM) is provided. This memory is arranged in 16 banks of 8 kilobytes using four 32 kilobyte static RAMs. While the system is active, the SRAMs are powered using the primary power source. While the system is quiescent, the SRAM is placed in low power mode and powered from the back-up power cell. Replacement of the back-up power cell can be accomplished only while the unit is connecting to its primary power source. The system further includes 32 kilobytes of display RAM. This RAM may be a volatile memory, if required. This display memory is utilized by the system as image buffers. The liquid crystal display provides a 400 by 192 pixel bit map display screen overlaid with a transparent touch sensitive pad. The CPU processes information in either a portrait or landscape orientation as selected by application code, and appropriate user information. As such, the contrast ratio for the LCD must be reasonably constant as the assembly is rotated through 360°. The outside dimensions of the LCD are about 6.259 inches by 3.252 inches by 0.315 inches. The viewing area is at least 4.724 inches by 2.267 inches. Center to center dot spacing of 0.3 millimeters is required for the 400 by 192 dot resolution. The panel provides a reflective type LCD with a grey background color. In the preferred system, the memory controller chip is an application specific integrated circuit. The chip provides bus control and memory segmentation, interrupt control and identification, power management, and direct memory access functions. Because the selected CPU provides linear addressing space of only 64 kilobytes, the processor segments memory into banks. A 16 bit address A15-A0 from the microcontroller is translated into a 21 bit memory address MA20-MA0 by means of the bank registers. The three high order bits A15-A13 of the microcontroller address are used to address the bank registers. Each bank register stores the eight high order bits of a given memory address MA20-MA13. Interrupts are generated in the system from the voltage monitor, the attention button, and the clock/calendar chip 90. Upon receipt of an interrupt, the memory controller circuit notifies the CPU of the event, performing a CPU "power-on", if required. The memory controller chip provides a method whereby the processor can uniquely identify the source of external interrupts. The memory controller chip also provides DMA services in a variety of contexts. Transfer from the image RAM to the LCD drivers, as well as from ROM and SRAM into the blitter, the memory controller provides a two-channel DMA circuit. The DMA is designed to minimize bus contention between the CPU, the blitter, and the LCD controller. This DMA utilizes real addresses, so that it is not constrained by the limited address space of the CPU. In the case of bus conflicts, the LCD controller channel prevails. Bus conflicts between the blitter and the CPU are resolved in favor of the blitter access. The LCD control chip integrates an LCD controller and the hardware blitter operations. The LCD controller 58 implements raster scan refresh of the LCD by synchronously accessing image data within the image RAM, serializing it, and shifting it out to the LCD drivers. The CPU provides a base address for a particular display, particularly within the display RAM. Also, this chip provides a blanking signal for disabling the LCD. The hardwater blitter is a registered barrel-shifter combined with a logical function selector. The hardware blitter is capable of read modify write operations between the image RAM and information contained in either the static RAM or the ROM of the processor. The blitter is capable of performing simple masking (and), merging (or), complimenting (not), filling with ones or clearing with zeros within the image RAM in conjunction with a barrel shifter. The memory control chip also implements the circuitry necessary to allow the CPU to periodically scan the touch screen. Registration of the dots of the liquid crystal display and dots on the touch screen is performed in software during user configuration session. The touch screen controller provides a mode whereby the sense of the user touch will awaken the CPU at completion of an X/Y read cycle. The CPU may initiate a touch screen scan based on an internal timer. 9 bits resolution in the long X axis of the touch sensitive screen and 9 bits resolution in the short Y axis is provided. The hand-held computer, according to the present invention, may be configured for use by either a left-handed or a right-handed user. Because of the location of the transmitter/receiver and because the center of gravity of the computer is such that its balance is better if held near the end having the battery pack, a right-handed user will tend to hold the computer so that the screen has a first orientation and a left-handed user will hold the computer so that the screen is turned over. The touch screen control and the LCD display refresh circuitry are adapted to accommodate either a left-handed or a right-handed user. In the preferred embodiment, the transmitter of a hand-held computer generates an infrared signal to be detected by a receiver in a personal computer interface or other peripheral device. As shown in FIGS. 8-9, the signal generated is a binary data stream 300, such that each piece of binary data consists of a signature set of two 5 microsecond pulses 302 spaced by 5 microseconds for binary zero 400, and a signature set of no pulses for a binary one 401. Each of these signature sets falls within a 32 microsecond window 301, so that the pulse pairs of successive binary zero signature sets will be separated by 17 microseconds. These signature sets of pulses provide the receiver with the capability of distinguishing the infrared signal sent by the transmitter from any background infrared radiation present, while accomplishing communication at speeds greater than 30,000 bits per second, high enough for communication of digital files by telemetry. Communication between the hand held computer and the personal computer interface or other peripheral device is according to a packet protocol. With reference to FIG. 10, each packet 500 communicated by the system consists of a preamble 501 and an optional body 502 of data appropriate, described as follows: ______________________________________PREAMBLE + [BODY]Every PREAMBLE contains;BitSync ByteSync Lead-InToID MyID Etype [EData] CRCWhere:BitSync = 20 0x00'sByteSync = 3 0xFF'sLead-In = 0x1DA1 (short packet) 0xA210 (long packet)ToID = 0 = packet for any unit listening; or = n (0<n<251) = packet for unit. with logical ID `n`MyID = n (1<n<255) = logical ID of the sending unitEType = Type of this packet preambled7-d4 = Preamble typed3 = Repeated transmissiond2-d0 = Number of preamble [Edata] bytes prior to preamble CRC0x12 = Broadcast Packet (future)0x22 = Diagnostic Packet (reserved)0x30 = SLAVE WRU0x40 = MASTER WRU (future)0x52 = IMA0x60 = ZIT (request for `ACK me`)0x70 = Solicit0x82 = ToYou0x91 = ACK0xA0 = (reserved)0xB0 = (reserved)0xC0 = Special 10xD0 = Special 20xE0 = Special 30XF0 = Special 4[EData] = Envelop data (optional)[AckStatus] . . . when EType is ACK[BodyLong] = Number of bytes of BODY contained within this packet. May be zero! Sent with ETypes: 0x12 = Broadcast Packet 0x22 = Diagnostic Packet 0x52 = IMA 0x82 = ToYouAck Status Bits are dedicated as follows:d7 = 0 Version 1.0d6 = 0 Version 1.0d5 = 1 EMPTYd4 = 1 HOST OFFLINEd3 = 1 NO HOST/NO CARRIERd2 = 1 BODY OVERFLOWd1 = 1 GARBAGEd0 = 1 FULL;Where:FULL: An indication that the unit initiating this ACK has no more buffers available for another packet.GARBAGE: An indication that the unit initiating this ACK received a packet with a bad BODY CRC. NOTE: This could also be an indication of a failure in the preamble CRC.BODY OVERFLOW: An indication that the unit initiating this ACK received a packet where the body `length` exceeded the available buffer size.NO HOST/NO CARRIER: Status bit indicating that the unit initiating this ACK does not currently have a host that is responding to any traffic. This is generated by the vPCI and MODEM peripherals only.HOST OFFLINE: Status bit indicating that the unit initiating this ACK is connected to a HOST but that the HOST has notified this unit that it is unavailable. This is typical when, for example, a Personal Computer Interface (PCI) is connected to a host, communications has occurred, but the host is not currently executing compatible code.EMPTY: Status bit indicating that the unit initiating this ACK has no filled and/or valid packets to report (or be solicited).The optional body of a packet has the followingformat:Start Type Dest Source Command Status Length Data CRCWhere:Start - varies from 0 to 255, used for synchronization of packet transfers. (One unique value could suffice.)Type - packet type1 = Data Packet2 = Command Packet (can have status from last xfer)3 = Status PacketECC long Pkt - (D7 on for the above types) (PC will never see this type)Destination Bit Assignments -1 = PC SPO2 = HH SPO3 = HH ATP10 = PCI ATP11 = Printer12 = Barcode13 = Modem20 = Network30 = KeyboardSource Bit Assignments -1 = PC SPO10 = HH SPO11 = PCI ATP12 = Printer13 = Barcode14 = Modem21 = Network31 = KeyboardCommand Bit Assignments -0 = Null Command (just more data in this packet)1 = Begin Session10 = End Session11 = Abort Session20 = HH Receiver ready21 = Resend NStatus - Bit Assignments1 = Ack0 = Nack10 = PCI Time-out on IR ( only issued to PC )11 = PCI Time-out on PC ( only issued to HH )20 = HH Time-out on PCI21 = PC Time-out on PCILength - length of Data Field (usually Zero for Status Packets)Data - variable lengthThe `Application Data` would employ a completesubstructure of what is being sent (all receivesare presumed to be preauthorized for sizeconstraints).CRC - of entire packet______________________________________ Example sessions between a hand held computer HH and a personal computer PC are set out below. ______________________________________HH to PC transfer:PC - Start Session CMDPCI - Waits for IR CMDHH - Start Session CMD (needed?)PCI - Acks HH if good CRC, else NACKPCI - sends to PCHH - sends dataPCI - as it's reading from IR, begins sending it up to the PC when it's all read in from the IR, and if CRC good, then ack HH (we're still shipping it to the PC)PC to HH transfer:PC - Start Session CMDPCI - Waits for IR CMDHH - HH receiver ready CMDPCI - Acks HH if good CRC, else NACKPCI - gets from PC, building CRC when done, Start shipping it to the HHHH - receiving dataPCI - as it's sending data to the HH, begins getting more from the PC when it's all sent to the IR, waits for Command or Status packet from HH. Could be CMD packet with ack status & and HH Receiver ready (for more data) or end session.______________________________________ Specific types of communications packets could be as follows: ______________________________________EDPKT + < Tabname > + < Subtab name > + < Flags:G-up, G-down > + < # of entries > + < RemoteEntryID, Entry Record > + . . . + < RemoteEntryID, Entry Record > + <EOP>______________________________________ This is the packet that is returned to the HH from the PC, after the HH had issued the REDPKT call for the computer system described in the above referenced application entitled "Computer with Graphic Interfaces". It consists of the Tab and Subtab names for the top line of the display, ghost flags, indicating whether to ghost the Up and/or Down buttons, the count of entry records in this packet, and the actual Remote Record ID's and Data. The PC only returns those records that can fit on the HH's display. The Entry data in this packet do reflect the Entry Record structure. PassCode Request Packet--(PC to HH) PCRQPKT+<EOP> This packet is returned to the HH when a passcode is required to access a Tab, Subtab, or Page display. The HH should put up the passcode gadget, get the user's passcode, stuff it in the request, and re-issue the call. Request Tab Display Packet--(HH to PC) RTDPKT+[optional Passcode]+CRC The HH issues this call after the user has selected the Remote button to get the Tab display of the Remote. The PC will either return a PCRQPKT or the Tab data with a TDPKT. Request Subtab Display Packet (HH to PC) RSDPKT+<Slot #>+[optional Passcode]+CRC The HH issues this call after the user has selected a Tab Slot to get the Subtab display of the Remote. The PC will either return a PCRQPKT or the Subtab data with a SDPKT. Request Form Packet--(HH to PC) RFMPKT+<Subtab Slot #>+CRC The application issues this call when the user has selected a Subtab to open. The PC will either return a PCRQPKT or the form data with a FMPKT. After the application has received the FMPKT, it should issue a REDPKT to get the first page of data. Request Entry Display Packet--(HH to PC) REDPKT+<Flags First Next Prev>+CRC The application issues this call when the user has selected a Subtab to open. The PC will either return a PCRQPKT or a page worth's of display data with a EDPKT. Request Export of Packet--(HH to PC) REXPKT+<Remote ID>+[optional passcode]+CRC When copying or moving, and after the user has selected where to move/copy the data to, the application should issue this call to actually get the record associated by the Remote ID. To get all of the data associated with a Tab or Subtab, the HH should walk the chain and request each record separately--the PC is not going to send back more than 1 record at a time. The PC sends the data back with the R4UPKT packet. Request Import of Packet--(HH to PC) RIMPKT+<Record Length>+<My Record ID>+<Remote Insert-after ID or Slot #>+<Record data>+CRC The HH uses this call to send a record to the PC. Again, as with the REXPKT call, to send all of the data associated with a Tab or Subtab, the HH should walk the chain and send each record separately--the PC hasn't any knowledge of the HH's linkages. If the Remote Insert-after ID is zero, then it goes at the beginning of the chain. This field can be a slot number if the HH is on a Tab or Subtab display. Record For You Packet--(PC to HH) R4UPKT+<Remote Record ID>+<Record Length>+<Record Data>+<EOP>+CRC The PC returns this packet with a record in it after the HH has made the REXPKT call. If a passcode is required, the PC will return the PCRQPKT function instead, and the application, after receiving the user's passcode, should re-issue the REXPKT call. From the perspective of the HH, since it's the master, these are the calls to the communications system: Tab Display Pkt--(PC to HH) TDPKT+<Slot#>,<Text>+....+<Slot #>, Text>+<EOP>+CRC This is the packet that is returned to the HH from the PC, after the HH had issued the RTDPKT call. It consists of the Slot Number and Tab Name for each of the allocated Tabs of the remote book. The data in this packet do not reflect the structure of allocated tabs in the current operating point. Subtab Display Pkt--(PC to HH) SDPKT+<Tabname>+<Remote SubID>+<Slot #, Text>+....+<Slot #, Text>+<EOP>+CRC This is the packet that is returned to the HH from the PC, after the HH had issued the RSDPKT call. It consists of the Tabname for the top line of the display, the remote Subtab ID, and the Slot Number and Subtab Name for each of the allocated Subtabs of the remote book. The data in this packet do not reflect a Subtab record structure. Form Packet--(PC to HH) FMPKT+<Remote FormID>.sub.-- ≦Form Record w/out p-code>+<EOP>+CRC This is the packet that is returned to the HH from the PC, after the HH had issued the RFMPKT call. It consists of the FormiD of the remote book's form for the slot the user selected on the remote Subtab display, and the form record data. The data in this packet does reflect the Form record structure, but without any p-code. The application (or RMGR) should check whether the HH already has this form by comparing the form's unique catalog number. If it does have the form, it should ignore the data. A detailed description of the preferred embodiment of the receiver in the personal computer interface or other peripheral device is given with reference to the figures. FIG. 3 shows the overall design of the Infrared communications receiver and signal processor 100. The circuit processes an analog IR signal A1 produced by diode D1 receiving an infrared signal, in such a way as to produce a digital representation IRIN at output D4 of the infrared signal. An infrared signal is detected by the IR detector diode D1. This diode D1 generates a series current approximately proportional to K(1/(DISTANCE).sup.2), where K is a circuit constant, and DISTANCE is the distance between the source of the IR signal and the IR diode surface. The series current is amplified, compressed, filtered, and converted to a digital signal that appears at output D4. The D4 output signal referred to as IRIN is coupled to the communication controller 59 of FIG. 2. The communication control 59, recovers and processes the digital bit stream from IRIN. Digital input signal IREN is used to put the receiver 100 circuit into a low power standby mode when not in the process of receiving a valid IR input signal. FIG. 3 also indicates external circuitry which is connected to the receiver 100. In this respect, external capacitor C1e is connected between pad 4 and analog ground. External capacitor C3e is connected between pad 5 and analog ground. External capacitor C4c is connected between pads 7 and 8. Pad 9 is connected to diode D1. In turn, diode D1 has a common connection between external capacitor C5c and external resistor R4c. External capacitor C5c is also connected to pad 10, and external resistor R4c is connected to analog ground. Connected between pad 11 and analog ground is external capacitor C3c. Connected between pad 14 and analog ground is external capacitor C4d. Pads 12, 13, 15, and 19 are all connected. Pad 12 is connected to a common connection between external capacitor C1c and external resistor R2c. Pad 13 is connected to external resistor R1c, which is, in turn, connected to a common connection between external capacitors C2c and C1c. Pad 15 is connected to external capacitor C3c, which is, in turn, connected to a common connection between external resistor R3c and external capacitor C2c. Pad 19 is connected to a common connection between external capacitor C2e, external resistor R3c, and external resistor R2c. External capacitor C2e is then connected to analog ground. Connected in parallel between pad 20 and analog ground are external capacitor C1d and external resistor R1d. Further connected to receiver 100 are +5 voltage supplies and ground connections. Analog+5 volts is connected to pad 3. Analog ground is connected to pad 6. Digital +5 volts is connected to pad 16. Digital ground is connected to pad 18. The internal circuitry of receiver 100 consists of power management and biasing 200, and the subcircuits 201-210 set forth in FIG. 4. Power management and biasing 200 and the main subcircuits in FIG. 4 are connected as follows: The power management and biasing subcircuit 200 establishes internal reference voltages A13a, A13b, VLOG, C1, and E5. The logarithmic pre-amp 201 receives the noninverted and inverted IR inputs A0 and A1, respectively. The internal reference nodes, A13a and E5 are also connected to pre-amp 201. It is further connected to node D7 from subcircuit 207 discussed below. The output PA0 of the logarithmic pre-amplifier 201 is connected to highpass filter 202. This highpass filter 202 is coupled to internal reference node NC1. From the highpass filter 202, the inputs to a balanced bridge compression amplifier 203 are BPI and BPR. The bridge amplifier 203 is also coupled to internal reference nodes E5, NC1, and A13b, and node D7. The bridge amplifier 203 output pair G5 and G9, is connected to the lowpass filter amplifier 204. This lowpass filter amplifier 204 is also coupled to reference node E5. Its output BPO is the input to the VCVS highpass filter 205. This filter is coupled to nodes NC1 and E5. The output of this VCVS highpass filter 203 is connected to the high impedance node PKI. The bandpass 206 filter is connected to the high impedance output PKI, to nodes NC1 and E5. The output PKT of the bandpass filter 206 is input of two quadrant log summer 207 and to the peak detector 210. The second output PKO of the bandpass filter 206 is input to the comparator 208. The two-quadrant log summer 207 has an input reference, VLOG; and establishes the voltage at node D7. The peak detector 210, as previously noted, has the input signal PKT. Its output signal, PKC, is input to the comparator 208 along with the output signal PKO of the band pass filter 206. The outputs of the comparator 208 are nodes D8 and D9. These nodes connect a reset-set (RS) current mode flip-flop and a shunt totem pole, referred to as output 209. The output 209 supplies a digital stream at the node DFG, which is labelled output D4 on receiver 100 in FIG. 3. The main subcircuits of the receiver 100, illustrated in FIG. 4 are described specifically as follows in FIGS. 5, 6, and 7: Set forth in FIG. 5 is power management and biasing. Key to meeting the design objectives of the receiver is the need to generate three reference voltages that have low stand-by power, track over temperature and quickly stabilize when the receiver is enabled. In this configuration, IREN is connected to resistor R11. The split collector of transistor Q18, the base of transistor Q17, and resistor R11 are connected. The split collector of the diode-connected transistor Q15 is connected to the emitter of transistor Q18. While the emitter of transistor Q15 is connected to DC+5. Resistor R13 is connected between DC+5 and the emitter of diode-connected transistor Q16. The split collector of transistor Q16 is connected to resistor R10. Node E6 connects resistor R10, the base of transistor Q18, and the emitter of transistor Q17. When the receiver 100 is in the inactive state (+5v), the power manager must reduce the internal bias currents to very low standby values while maintaining proper internal reference voltages. This must be done in such a way as to minimize the power consumption while maintaining a low turn-on latency time. When IREN is at +5, transistors Q15, Q16, Q17, and Q18 are current starved to where their collector currents are <10 na. In the active mode (IREN=0 volts), the base of transistor Q16, establishes a reference bias voltage at node E5. Connected to the node E5 is the external capacitor C3e. The voltage difference between node E5 and node E6 determines the active bias current used in the power supply, this current is mirrored in transistor Q22 and scaled by transistors Q6, Q9, Q8 and Q11. In the current mirror, the diode-connected transistor Q22 is connected to the collectors of transistor Q17 and to the bases of transistors Q6, Q9, QS, and Q11. Between the emitters of transistors Q6, Q9, QS, and Q11, and analog ground are the resistors R3, R4, R5, and R6. The collectors of transistors Q6, Q9, Q8, and Q11 are connected, respectively, to the internal reference voltages VLOG, NC1, A13a, and A13b. The E5 voltage also determines the bias currents used in the balance of IRT7. The internal reference voltage at node A13 is maintained via a temperature stabilized, shunt differential regulator 300 whose output voltage is roughly determined by the expression: A13=(R1+R2)/R2[V.sub.be Q5+1n(Q13/Q5) (R16/R7)(kT/q)] +VbeQ1. The exact voltage is determined by the emitter current density of transistors Q1, Q13, and Q13A and Q5, which affects their respective V be 's. The collector of transistor Q1 is connected to analog+5. In this circuit, the diode-connected transistor A14 is connected to the collectors of the parallel combination of transistors Q13 and Q13a. In this configuration, the collectors of transistors Q13 and Q13a are connected to the diode-connected transistor Q14. The emitters of transistors Q13 and Q13a are connected to resistor R7. Node E8 connects resistor R7, the emitter of transistor Q5, and resistor R16. R16 is then connected to analog ground. Connected between the emitter of transistor Q1 and node E3 is resistor R1. Connected between node E3 and analog ground is resistor R2. Also connected to node E3 are the gates of transistors Q13, Q13a, and Q5. The base of transistor Q1 and the collector of transistor Q5 are connected to node A13. The nominal A13 voltage at 27° C. is 3.236v. Transistor Q25 acts as a start-up circuit to force current into the transistor V be Q14 junction in the unlikely situation that the regulator does not initialize at power-up. Once the regulator is initialized, transistor Q25 is essentially inactive by virtue of its V be being<300 mv. For this function, transistor Q25 is connected in the same fashion as transistors Q13 and Q13a. The A13 node voltage is level shifted up through transistor Q2 and then down via transistors Q4 and Q7. This produces node voltages A13a and A13b with source impedances determined by the tail currents of transistors Q8 and Q11. This technique isolates the voltage at node A13 from switching transients generated in the preamplifier and bridge circuits. For this function, the diode-connected transistor Q2 and transistors Q4 and Q7 are connected in a current mirror arrangement. Further, the gate of transistor Q14 is connected to the gate-collector connection of transistors Q2, Q4, and Q7. The VLOG voltage is established by shifting node voltage A13 down one V be via transistor Q3. To do so, the gate of transistor Q3 is connected to node A13, the collector of transistor Q3 is connected to node analog+5, and the emitter of transistor Q3 is connected to node VLOG. Further, the node C1 is connected to the emitter of transistor Q12 and the collector of transistor Q9. The base of transistor Q12 is connected to node E9 and the collector of transistor Q12 is connected to analog +5. In the active receive mode, the 58 μamp flowing through resistors R3, R4, R5 and R6 determine the absolute emitter current density of transistors Q3, Q12, Q4 and Q7, this in turn sets the active output node voltages of VLOG, C1, A13a and A13b. Node voltages C1, A13a and A13b stabilize within a few micro-seconds (μS) while NC1 takes 600 μS. In the shut-down mode, the current through transistor Q22 is reduced to near zero, this reduces the emitter current density of transistors Q3, Q12, Q4, and Q7, which causes nodes VLOG, A13a and A13b to rise and track. External capacitor C1e is the main by-pass capacitor and serves to isolate all the reference voltages from each other. It is connected to Pad 4. The net result of maintaining the reference voltages while lowering the bias currents is to reduce the circuit recover time from large IR overdrive signals, while simultaneously having low standby power. It should be noted that the resistors values shown as 1 ohm are for reference purposes and do not physically exist in the design. Also note resistors shown as RXUN are approximately 40 ohms and are used in the circuit routing process. Indicated in FIG. 6 are the preamplifier, highpass bridge amplifier, lowpass amplifier, and VCVS filter circuits. The preamplifier itself is composed of transistors Q31, Q32, Q33, Q34, Q35, Q36, and Q37. It is important that this amplifier be, low noise, wide bandwidth and immune to gross overload signals. The design is a logarithmic current to voltage converter. It can convert a 100 khz current source signal with signal strengths of from 50 nanoamps, to 50 microamps, to a logarithmic voltage equivalent at node C2. In the preamplifier, the emitters of transistors Q31 and Q32 are connected to the collector of transistor Q37. The collector of transistor Q31 is connected to the diode-connected transistor Q33. The collector of transistor Q32 is connected to the node C2. The node C2 connects the collector of transistor Q33, capacitor C1, the base of transistor Q34, and the base of transistor Q35. Resistor R31 is connected between analog+5 and the emitter of transistor Q33. Connected to the base of transistor Q40 is the reference bias voltage E5. Resistor R38 is connected between analog+5 and the emitter of transistor Q40. The split collector of transistor Q40 is connected to the bases of transistors Q37 and Q36. The pre-amplifier is unconventional in that the noninverting input (A0) is AC coupled to the base of transistor Q31 via external capacitor C5c to the IR diode D1 resistor load R32, while the inverting input (A1) acts as a current summing node for IR signal current. The non-inverting inputs time constant, determined by resistor R32, external resistor R4C, and external capacitor C5c, working as a DC restoration circuit acts to increase the effective gain of the preamplifier by pushing the operating point of the logarithmic converter into a more sensitive operating range. In this circuit, external capacitor C5c is connected between diode D1 and through pad 10 to resistor R32. Resistor R32 is connected to resistor R33. Pad 9 connecting diode D1 and resistor R33 is connected to the base of transistor Q32. This increased sensitivity is only for signal frequencies that are above the input pole frequency. The voltage at the base of the logging transistor (Q34) is determined by its emitter current density. The current density is the sum of four currents. The first is the actual IR signal current, the second is the current developed through resistor R33 by virtue of the IR signal voltage appearing across external resistor R4c and resistor R32 in parallel, the third is the compression current injected by transistor Q38's collector, and the fourth is the base current of transistor Q32. The base-emitter voltage of transistor Q34 is V be Q34=(KT/Q)*[In(I e Q34/I o )], Where K is Boltzmanns Constant T is Absolute Temperature Q is charge on a electron I o is leakage current Ie is {IR}*[1+)R3 ||R32)/R33]+I c Q38+I b Q32 Resistor R31 is used to raise the output impedance of transistor Q33. Resistor R31 is connected to analog ground and then is connected to the emitter of transistor Q33. This provides higher gain accuracy in transistor Q32's collector circuit. The early voltage off-set caused by the split collector configuration of transistor Q33 is not sufficient to cause more then a few hundred micro volts of additional offset in the input differential pair. Transistor Q39 and resistor R37 form a current mirror that is scaled by transistor Q37 and R34. The diode-connected transistor Q39, is connected to transistor Q37. The emitters of transistors Q39 and Q37 are connected to resistors R37 and R34, respectively, which are in turn connected to ground. The tail current for the transistor Q31, Q32 pair is 160 μA. This configuration produces a logarithmic signal at the base of transistor Q34 that is relatively immune to signal overload and saturation effects. Transistors Q35 and Q36 form a unity gain voltage buffer that drives output PAC. The collector of transistor Q35 is connected to analog +5; the base of transistor Q35 is connected to the base of transistor Q34; and the emitter of transistor Q35 is connected to the collector of transistor Q36. The base of transistor Q36 is connected to the current mirror of transistors Q39 and Q37, while resistor R36 is connected between the emitter of transistor Q36 and analog ground. The output impedance should be a nominal 1000 ohms. Intrinsic to the operation of the receiver is the cumulative effect of the (phase) group delays in the bandpass and VCVS filters. It is these delays that develop the transient profile necessary for the decoder to track bit to bit amplitude changes. The highpass balanced bridge compression amplifier is composed of transistors Q47, Q48, Q41, Q42 and Q50. In this amplifier the gates of the bridge input pair of transistors Q47 and Q48 are connected to nodes BPI and BPR, respectively. Node BPI is connected to external capacitor C4c and is referenced to node C1 through resistor R39. Node BPR is referenced to node C1 through resistor R49. There is a common connection between the emitters of this input pair and the collector of transistor Q50. The gate of transistor Q50 is connected to node C6, while the emitter of this transistor is connected to resistor R43, which is, in turn, connected to analog ground. In the output bridge pair of transistors Q41 and Q42, the gates are referenced to node A13b, the collectors are connected to analog+5 and the emitters are connected to the nodes G5 and G9, respectively. This amplifier provides a nominal dynamic output load of 5K ohms. The impedance will range between 50 and 5K ohms under varying signal conditions. Transistors Q52 and Q53 collector currents provide the compression for character-to-character load adjustment to scale and shape the incoming signal. The collectors of transistors Q52 and Q53 are connected to the nodes G5 and G9, respectively. The gates of these transistors are connected to the emitter of transistor Q56, which, in turn, is biased by internal reference signal D7. The emitters of these transistors are connected to resistor R50, which is connected to analog ground. The amplifier also establishes a signal filter pole at approximately Frc=1/2*Pi*C4c*(R39+Q35)-53Khz, Where R39=5K ohms R.sub.e =1K ohms C4c=500pf The differential input pair, transistors Q47 and Q48, are referenced to voltage Cl. The output differential bridge pair consist of transistors Q41 and Q42. The reference voltage for transistors Q41 and Q42 is node voltage A13b. This isolates the signal currents and load impedances (R e Q41, R e Q42) from the power supply filter node (A13). The bridge output pair are DC coupled to a pseudo differential lowpass filter amplifier composed of transistors Q44, Q45, Q43, Q46, Q41 and Q49. In this configuration, the emitter of transistor Q43 is connected to analog+5. The diode-connected transistor Q43 is connected to the collector of transistor Q44. Node G1 connects the base of transistor Q43, the collector of transistor Q45, and the base of transistor Q46. Connected to node G9 are the emitter of transistor Q42 and the resistor R45. Node G6 connects resistor R45 and the gate of transistor Q45. Also connected by node G6 are resistor R46, and capacitors C32 and C33. Node BPO connects the emitter of transistor Q46, resistor R46, and capacitors C32 and C33. The emitters of transistors Q44 and Q45 are connected to transistor Q49. The gate of transistor Q49 is connected to node C6, and the emitter of this transistor is connected to resistor R1, which is connected to analog ground. The lowpass gain is equal to R46/(R45+ReQ42). Output signal BPO drives the input of the Voltage-Controlled Voltage Source (VCVS) highpass filter. The three pole VCVS highpass filter is composed of transistor Q55, Q54, external capacitors C1c, C2c, C3c, and external resistors R1c, R2c, R3c. Transistor Q55 forms a unity gain feedback buffer with transistor Q54 providing a tail current of 1/2 I(R47) or 38 ua. This yields an output feedback impedance of 685 ohms. In this configuration, node BPO is connected to external capacitors C3c and C2c, and external resistor R3c. Also connected are external capacitors C2c and C1c and external resistor R1c. Connected to node C1 are external resistors R3c and R2c. Connected by node PKI are external capacitor C1c, external resistor R2c, and the gate of transistor Q55. The collector of transistor Q5 is connected to node analog+5. Node F4 connects the emitter of transistor Q5, external resistor R1c, and the collector of transistor Q54. The gate of transistor Q54 is connected to node C6. Connected are the emitter of transistor Q54, the emitter of transistor Q51, and resistor R17. Resistor R17 is connected to analog ground. The filter is specifically referenced to C1 with its output being the high impedance node PKI, as opposed to the more conventional low impedance node F4. This configuration is necessary to ensure proper head-room and bias tracking of the succeeding stages. Over and above the logging action of the preamplifier and differential bridge, a scaling signal is used to prevent saturation of the remaining circuitry. This signal is applied to internal node D7. The resulting current, in resistors R40 and R35, is used to compress the logging range of their respective amplifiers. Note that the term Automatic Gain Control is deliberately avoided. AGC has a connotation that is inappropriate in this case. The distinction is that within the 66 db compression range, the logarithmic amplifiers can accurately process a 40 db bit-to-bit change that would be totally missed by "AGC". One may argue this is a matter of semantics, never the less, the entire circuit concept will not work with "AGC" alone, the receiver must be centered around the dynamic operating characteristic of the logarithmic converters. FIG. 7 contains a DC coupled active bandpass filter, a two quadrant voltage to logarithmic current converter, a peak detector, a tracking analog to digital converter (comparator) with current mode hysteresis and a differential to single end. The bandpass filter is composed of transistors Q67, Q68, Q63, Q70, Q87, and Q72. In this filter, the output of the VCVS highpass filter (PKI) is connected to the gate of transistor Q67. The collector of transistor Q67 is connected to the diode-connected transistor Q63. The emitter of transistor Q63 is connected to resistor R67, which is connected to analog ground. The split collector of transistor Q63 is further connected to node PKT. Also connected to node PKT are the gate of transistor Q87 and the collector of transistor Q68. The gate of transistor Q68 is connected to node D3. The emitters of transistors Q67 and Q68 are connected to the collector of transistor Q70. The emitter of transistor Q70 is connected to resistor R62, which is connected to analog ground. The collector of transistor Q87 is connected to analog+5. The emitter of transistor Q87 is connected to node PKO. Also connected to node PKO is the collector of transistor Q72. The emitter of transistor Q72 is connected to resistor R63, which is connected to analog ground. Finally, the gates of transistors Q70 and Q72 are connected to node D6. The bandpass voltage gain is approximately Av=(R70/R69) The actual gain, of course, is slightly lower and determined by the complex feedback impedance determined by resistors R70 and R69, capacitors C61 and C62, and external capacitor C4d. Except for external capacitor C4d, each of these is connected to node D3. C4d is connected to resistor R69 and then is connected to analog ground. The lower pole is set at Frc=1/2* Pi* C4d* (R69)-55Khz, Where R69=1.5K ohms C64d=1800pf The upper pole is set at Frc=1/2*Pi*CPAD*(R10)-350Khz, Where R70=90K ohms CPAD=(C61+C62)=5pf The non-inverting DC output level, PKO, tracks the static DC value of PKI, which is referenced to C1 via the VCVS highpass filter of the preceding stage. This tracking function is critical to the data detection scheme. When the receiver is active, and static, i.e. between IR pulses, the DC value of node PKT is very close to the value of reference voltage VLOG. This is accomplished by the DC offsets in resistor R70, external resistor R2c, and the emitter current density of transistor Q87. PKT must track the value of VLOG over supply voltage and temperature changes. The tail current provided by transistor Q72 is used to establish the proper current density in transistor Q87 as well as the drive current for the feedback impedance resistor R70 and CPAD. The two quadrant logarithmic converter is composed of transistors Q65, Q66, Q71, Q63, Q90 and Q92. The signal voltage at the collector of transistor Q68 is converted to a logarithmic current via the bipolar logging action of the complementary pair of transistors composed of transistors Q65 and Q66. The collector of transistor Q68 is connected to the emitters of transistors Q65 and Q66. The gates of transistors Q65 and Q66 are connected to internal reference VLOG. The collector of transistor Q65 is connected to the split collector of diode-connected transistor Q64. The emitter of transistor Q64 is connected to analog+5. Further connected are the split collector of transistor Q64, the split collector of transistor Q66, and the diode-connected transistor Q71. The collector current of transistor Q65 is mirrored via transistor Q64 and summed with the collector current of transistor Q66 in the collector of transistor Q71. This summing action, in effect, acts to "rectify and sum" the bipolar signal voltage at PKT into a logarithmically proportional unidirectional current in the collector of mirror transistor Q71. This signal dependent, pulsing current, is amplified further by the ratio of resistors R72 and R81, connected, respectively, to the emitters of transistors Q71 and Q91, and thereafter connected to analog ground. The amplified current is mirrored by transistor Q90 and drives node D7, where the emitter of transistor Q90 is connected to analog +5. The gate and split collector of transistor Q90 is connected to the collector of transistor Q91. The voltage at node D7 is determined by the instantaneous charge on external capacitor C3d. The instantaneous charge on external capacitor C3d is the result of the relatively low discharge current provided by transistor Q92 and the relatively high pulsing current provided by transistor Q90. In this configuration, the split collector of transistor Q90 is also connected to resistor R84. Connected by node D7 are resistor R84, external capacitor C3d, and the collector of transistor Q92. The gate of transistor Q92 is connected to node D6 and the emitter of transistor Q92 is connected to resistor R83, which is, in turn, connected to analog ground. E.sub.C3d -1/C2d(iQ90-iQ92)dt The voltage at D7 is used to generate the scaling current for the preamplifier and bridge amplifier. Gain stability, transient recovery time and suppression of substrate current for the bandpass amplifier is ensured by preventing the collector voltage of transistor Q68 from ever dropping below its own base voltage. This is accomplished by diverting transistor Q68's collector current through the emitter of transistor Q65 during large negative collector transients. As noted previously, both the emitter of transistor Q65 and the collector of transistor Q68 are connected to node PKT. Current source transistor Q62 uses split collectors to isolate the tail current mirrors used to drive the bandpass amplifier and comparator circuits. In this arrangement, the emitter of transistor Q62 is connected to resistor R73, which is connected to analog +5. The base of transistor Q62 is connected to internal reference voltage E5. The split collectors establish nodes D5 and D6, which are connected respectively to the gate and collector of transistors Q73 and Q69. Without the isolation provided by transistors Q69 and Q73, switching transients developed in the comparator and output stage will generate regenerative crosstalk via. the reference supplies and cause instability in the preceding stages. The tail current reference voltage, E5, is capacitively decoupled to ground. This helps to further isolate the internal current sources. The peak detector is composed of transistor Q88, resistor R71, external resistor R1d, and external capacitor C1d. As exemplified in FIG. 11, the outputs of nodes PKO 601 and PKC 602 track the signal value at node PKT via transistor Q87 and Q88 respectively. Transistor Q87 is configured as a voltage follower with tail current being provided by transistor Q72, its output node, PKO 601, follows node PKT with a DC offset determined by the emitter current density of transistor Q87. Node PKC 602 can follow PKT only to the extent that external capacitor C1d is charged via. resistor R71 and discharged by external resistor R1d. In this arrangement, the collector of transistor Q88 is connected to analog+5. The gate of transistor Q88 is connected to node PKT, and the emitter is connected to resistor R71. Resistor R71 is further connected to node PKC 602. Also connected to node PKC in parallel with digital ground are external capacitor C1d and external resistor R1d. The asymmetric charge and discharge results in the peak following characteristic. By comparing the relative values of PKO and PKC, it can be shown that for a given charge/discharge rate the two signals (PKO 601, PKC 602) will "cross" each other during the discharge interval 603 at a point in time 605 which is fixed relative to the actual peak 604 of PKT 600. In effect, the peak of PKT has been detected independently of its absolute signal amplitude. The differential comparator that detects the "crossing" difference of the signals at nodes PKO 601 and PKC 602 is composed of transistors Q74, Q75, and Q76. As nodes PKO and PKC cross each other, the tail current generated by transistor Q74 will switch to the transistor whose input is the most positive. In this arrangement, the collector of transistor Q74 and the emitters of transistors Q75 and Q76 are connected at node D4; the gates of transistors Q75 and Q76 are connected to nodes PKO and PKC, respectively; and the collectors of transistors Q75 and Q76 are connected to the output nodes of the comparator, D8 and D9, respectively. The emitter of transistor Q74 is connected to resistor R65, which is, in turn, connected to digital ground. Statically, the voltage at node PKC 602 is slightly higher than at node PKO 601, this ensures that the comparator output is held high during no signal intervals. This standoff voltage is determined by the Geometry and current density differences between transistors Q87 and Q88. The data is reconstructed by a Reset-Set (RS) current mode flip-flop composed of transistors Q77, Q78, Q79, and Q80. The collector currents of transistors Q75 and Q76 are mirrored via a single collector from transistors Q77 and Q80 respectively. Each mirrored current is ratioed by a factor of 3x, by the dual collectors of transistors Q78 and Q79 respectively, to the opposite members collector. In this arrangement, node D8 connects the collector of transistor Q75, the diode-connected transistor Q77, the collectors of transistor Q79, and the collector of transistor Q80; and node D9 connects the collector of transistor Q76, the collector of transistor Q77, the collectors of transistor Q78, the gate of transistor Q79, and the diode-connected transistor Q80. Connected to the emitters of transistors Q77, Q78, Q79, and Q80 are the resistors R75, R76, R77, and R74, respectively. Further, each of these resistors is connected to digital +5. This configuration produces an apparent voltage hysteresis at the base of transistors Q75 and Q76 by imbalancing their effective base offset voltage. The shunt totem pole stage is composed of transistors Q82, Q81, Q84, Q83, Q85, and Q86. The gate of current sources Q82 and Q81 are connected respectively to nodes D9 and D8. While the emitters of transistors Q82 and Q81 are connected respectively to resistors R75 and R79, both of which are connected to digital +5. Current source transistors Q82 and Q81 are driven differentially by nodes D8 and D9, respectively. The split collector of transistor Q82 is connected to the diode-connected transistor Q84, as well as the gates of transistors Q85 and Q86. The emitter of transistor Q84 is connected to resistor R66. Resistor R66, and the emitters of transistors Q85 and Q86 are all connected to digital ground. Node D2 connects the collector of transistor Q81, the gate of transistor Q83, and the collector of transistor Q85. The emitter of transistor Q81 is connected to resistor R79, and both resistor R79 and the collector of transistor Q83 are connected to digital +5, the output node DFG connects the emitter of transistor Q83, the collector of transistor Q86, and external capacitor C2d. The emitters of transistors Q85 and Q86, and external capacitor C2d are all connected to digital ground. The transistor Q82 collector current is mirrored by transistor Q84 and drives transistors Q85 and Q86 in parallel. Transistor Q85 provides an active discharge of node D2 while transistor Q86 pulls the output node DFG to digital ground. This configuration starves emitter current of transistor Q83, thus allowing all of transistor Q86 collector current to discharge the output node. The foregoing description of preferred embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in this art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.

An infrared communication system for transmitting a digital bit stream by telemetry in the presence of background radiation wherein each bit in the data stream is represented by a signature set of pulses designating either a binary one or a binary zero. A receiver detecting an infrared signal filters the signal to detect the signature sets of pulses generated by the transmitter. The pulses are transmitted according to a specific communications protocol.

This is a divisional application of Ser. No. 09/053,393 filed Apr. 1, 1998, now abandoned. BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to an improved stent and stent/graft deployment catheter. More particularly, the invention relates to a stent which is capable of being loaded into the delivery sheath of a stent/graft deployment catheter without suffering any structural damage and which is uniformly radially compressed during packing. 2. Description of the Prior Art An abdominal aortic aneurysm (AAA) is a sac caused by an abnormal dilatation of the wall of the aorta as it passes through the abdomen. The aorta is the main artery of the body, supplying blood to all organs and parts of the body except the lungs. It arises from the left ventricle of the heart, passes upward, bends over and passes down through the thorax and through the abdomen, and finally divides into the iliac arteries which supply blood to the pelvis and lower extremities. The AAA ordinarily occurs in the portion of the aorta below the kidneys. When left untreated, the aneurysm will eventually cause the sac to rupture with ensuing fatal hemorrhaging in a very short time. The repair of abdominal aortic aneurysms has typically required major abdominal surgery in which the diseased and aneurysmal segment of the aorta is bridged with a prosthetic device, such as a synthetic graft. As with all major surgeries, there are many disadvantages to the above mentioned surgical technique, the foremost of which is the high mortality and morbidity rate associated with surgical intervention of this magnitude. Other disadvantages of conventional surgical repair include the extensive recovery period associated with such surgery; difficulties in suturing the graft to the aorta; the unsuitability of the surgery for many patients, particularly older patients exhibiting comorbid conditions; and the problems associated with performing the surgical procedure on an emergency basis after the aneurysm has already ruptured. In view of the above mentioned disadvantages of conventional surgical repair techniques, techniques have been developed for repairing AAAs by intraluminally delivering an aortic graft to the aneurysm site through the use of a catheter based delivery system, and securing the graft within the aorta using an expandable stent. Since the first documented clinical application of this technique was reported by Parodi et al. in the Annals of Vascular Surgery, Volume 5, pages 491-499 (1991), the technique has gained more widespread recognition and is being used more commonly. Problems have been encountered accurately deploying the stent/graft. These problems are partially due to the method of packing the stent/graft into the delivery sheath of the deployment catheter. Currently, the stent/graft is manually radially compressed and pushed into the delivery sheath. This stent/graft compress and push method is problematic for a number of reasons. First, this process often leads to breakage of the stent struts. A stent with broken struts may not expand as designed, and as a result, will not properly bridge the AAA upon deployment. Second, this compress and push method of stent/graft packing produces a non-uniformly compressed stent. Unless all of the stent cells are equally compressed the stent/graft may not expand as designed upon exposure to the patient's blood, and as a result, the stent/graft will not adequately bridge the AAA. Another drawback of the present compress and push method of stent/graft packing is that it is very time consuming and difficult, and therefore, it is inappropriate for large scale production. Therefore, the need exists for an improved method for inserting a stent/graft into the delivery sheath of a deployment catheter. Furthermore, the need exists for an improved stent and a stent/graft deployment catheter which is capable of being loaded with a stent/graft using the improved stent/graft packing method. SUMMARY OF THE INVENTION Accordingly, it is an object of the invention to produce a method for inserting a stent/graft which overcomes the deficiencies of the prior art compress and push packing method. It is another object of the invention to produce a stent/graft deployment catheter capable of pulling a uniformly compressed stent/graft into its delivery sheath without damaging the stent/graft. It is a further object of the invention to produce a stent with V hooks capable of being pulled into the delivery sheath of the stent/graft deployment catheter. The invention is a method for inserting an improved stent into the delivery sheath of an improved stent/graft deployment catheter. The stent has V hooks on its proximal end which are positively engageable by projections attached to a stent/graft deployment catheter plunger. The proximal end of the stent is manually squeezed over the V hooks such that the V hooks engage the projections. The catheter is passed through the center of a funnel. While maintaining pressure on the stent and the V hooks, the plunger is withdrawn so as to pull the stent into the delivery sheath through the center of the funnel. The funnel guides the stent into the delivery sheath and uniformly compresses the stent as it approaches the delivery sheath. To the accomplishment of the above and related objects the invention may be embodied in the form illustrated in the accompanying drawings. Attention is called to the fact, however, that the drawings are illustrative only. Variations are contemplated as being part of the invention, limited only by the scope of the claims. BRIEF DESCRIPTION OF THE DRAWINGS In the drawings, like elements are depicted by like reference numerals. The drawings are briefly described as follows. FIG. 1 is longitudinal cross section of a distal portion of a prior art stent/graft deployment catheter. FIG. 2 is a plan view of a stent/graft being inserted into a delivery sheath via the prior art compress and push packing method. FIG. 3 illustrates a longitudinal cross section of the prior art catheter of FIG. 1 percutaneously inserted into a patient's blood vessel. FIG. 4 is a plan view of an unrolled stent having four V hooks. FIG. 5 is a plan view of an unrolled stent having two V hooks. FIG. 6 is perspective view of a stent/graft being compressed so as to positively engage the stent's V hooks with a plunger's L projections. FIG. 7 is a longitudinal cross section of a stent/graft which is partially inserted in a delivery sheath and partially enveloped by a funnel. FIG. 8 is a longitudinal cross section of a stent/graft having V hooks fully compressed and inserted into a delivery sheath. FIG. 9 illustrates a longitudinal cross section of a stent/graft deployment catheter having a grabber housing and without the inner tube and the tip. FIG. 10 illustrates a plan view of a distal surface of the grabber housing of FIG. 9 . FIG. 11 illustrates a longitudinal cross section of a distal portion of an alternative embodiment of the invention incorporating spring biased projections. FIG. 12 illustrates a perspective view of a stent/graft being loaded into the delivery sheath of the catheter illustrated in FIG. 11 . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates a longitudinal cross section of a co-axial prior art stent/graft deployment catheter 21 . Said catheter 21 is comprised of a catheter body 10 , a tip 50 , an inner tube 40 , a stent/graft 30 , and a plunger 20 , all of which are co-axial and have proximal and distal ends. Only the distal portion of the deployment catheter 21 is shown for clarity. The catheter body 10 is slidingly disposed about the inner tube 40 and has a delivery sheath 42 , a tube portion 43 , and an inner surface 70 . The plunger 20 is slidingly disposed about the inner tube 40 and is slidingly disposed within the catheter body 10 . The distal end of the inner tube 40 is attached to the tip 50 . The stent/graft 30 is slidingly disposed about the inner tube 40 and within the delivery sheath 42 of the catheter body 10 and is between the proximal end of the tip 50 and the distal end of the plunger 20 . The stent/graft 30 has an outer surface 60 and a lumen 52 extending from its proximal end to its distal end. The stent/graft lumen 52 is occupied by a distal portion 41 of the inner tube 40 . The delivery sheath 42 is located between the tip 50 and the tube portion 43 of the catheter body 10 . The inner and outer diameters of the delivery sheath 42 and the tube portion 43 are the same. FIG. 2 illustrates a perspective view of the stent/graft 30 being inserted by hand 38 into the delivery sheath 42 via the prior art compress and push method. The plunger 20 , the inner tube 40 , and a proximal portion 39 of the stent/graft 30 can be seen through the delivery sheath 42 wall as dotted lines. The catheter body 10 has been pulled back exposing the distal portion 41 of the inner tube 40 . The stent/graft 30 is disposed about the distal portion 41 of the inner tube 40 as is pinched by hand 38 and pushed into the delivery sheath 42 . The stent/graft 30 is made from a shape memory alloy, such as Nitinol, and is cooled below its transformation temperature allowing it to be compressed without permanent structural damage. The stent/graft deployment catheter 21 may be inserted percutaneously or via a surgical cut-down method into a blood vessel. FIG. 3 illustrates a longitudinal cross section of the prior art catheter 21 percutaneously inserted in a blood vessel 55 of a patient 54 . The delivery sheath 42 is still down stream of an aneurysm 56 in need of repair and has fully exited an insertion sheath 57 . If inserted percutaneously, as illustrated in FIG. 3, a guide wire 58 is first advanced through an insertion site 53 into the blood vessel 55 of the patient 54 . Next, a dilator sheath assembly (dilator not shown) is disposed about the guide wire 58 and the distal portion of the dilator is used to dilate the insertion site 53 . After dilation of the insertion site 53 the dilator is removed while the insertion sheath 57 is held in place in the blood vessel 55 of the patient 54 . Next, the catheter 21 is inserted into the introducer sheath 57 and is advanced forward into the blood vessel 55 of the patient 54 . Upon proper positioning of the tip 50 in the blood vessel 55 the plunger 20 is held in place while the catheter body 10 is pulled away from the tip 50 exposing the entire stent/graft 30 to blood. Upon contact with blood the stent/graft 30 expands such that the diameter of the stent/graft lumen 52 becomes larger than the outer diameter of the tip 50 . The expanded stent/graft 30 becomes fixed in place in the blood vessel 55 and thus bridges the aneurysm 56 . The inner tube 40 is then pulled away from the stent/graft 30 such that the tip 50 passes through the stent/graft lumen 52 . Finally, the catheter 21 is removed from the patient 54 . Note that there are many other types of self-expandable stent/grafts on the market including heat sensitive and spring-like stent/grafts. Note further that one major function of the introducer sheath 57 is to control bleeding at the insertion site 53 of the patient 54 during the entire procedure. The prior art compress and push packing method may damage the stent/graft 30 and produce a non-uniformly compressed stent which may not adequately bridge the aneurysm 56 upon deployment. FIG. 4 illustrates a plan view of an unrolled improved stent 2 having four V hooks 37 which is capable of being inserted in a uniformly compressed state and without structural damage. The stent 2 comprises nine parallel struts 36 which are connected by heart shaped cross members 35 . Each V hook 37 is connected to the end of two adjacent struts 36 . Stents that are 20 mm in diameter or greater generally require at least four V hooks for proper insertion into a delivery sheath. Stents that are less than 20 mm in diameter only require two V hooks. An unrolled stent 2 having only two V hooks 37 is illustrated in FIG. 5 . FIGS. 6-8 illustrate the improved method of packing the improved stent 2 (shown in FIG. 5) using an improved stent/graft deployment catheter 21 having two L projections 22 projecting from a distal end 107 of the plunger 20 . As can be seen in FIG. 6, the improved stent/graft deployment catheter 21 is first advanced through the center of a funnel 24 . The catheter body 10 is then pulled back exposing the distal portion 41 of the inner tube 40 and a distal portion 23 of the plunger 20 . The remaining portion of the plunger 20 is disposed within the catheter body 10 and is shown as dotted lines. Next, the L projections 22 are placed between the V hooks 37 . The stent/graft 30 is the compressed lightly by hand 38 such that the V hooks 37 are positively engaged by the L projections 22 . While maintaining said engagement the catheter 21 is moved to the left, relative to the catheter body 10 , such that the stent/graft 30 contacts the funnel 24 . Next, while holding the catheter body 10 , the plunger 20 is moved to the left forcing the stent/graft 30 into the delivery sheath 42 . As soon as the portion of the stent/graft 30 immediately to the right of the V hooks 37 is enveloped by the delivery sheath 42 the hand 38 releases the stent/graft 30 . The plunger 20 is pulled until the entire stent/graft 30 is disposed within the delivery sheath 42 , as illustrated in FIG. 8 . FIG. 8 illustrates a longitudinal cross section of a distal portion of the improved stent/deployment catheter 21 without the inner tube 40 after the stent/graft 30 has been completely inserted. Note that the stent/graft 30 may be made from a shape memory alloy, such as Nitinol. Prior to packing a shape memory alloy stent/graft, the body of the stent/graft must be cooled below its transformation temperature in order to allow it to be compressed without incurring any structural damage. FIG. 7 illustrates a longitudinal cross section of the stent/graft 30 partially inserted in the delivery sheath 42 and partially enveloped by the funnel 24 . The V hooks 37 are positively engaged by the L projections 22 . The funnel 24 guides the stent/graft 30 into the delivery sheath 42 . As the plunger 20 is moved left relative to the catheter body 10 , the funnel 24 uniformly compresses the stent/graft 30 . An alternate embodiment of the invention involves adding a component to the catheter 21 rather than altering the plunger 20 itself. FIG. 9 illustrates a longitudinal cross section of a distal portion of a stent/graft deployment catheter 21 without the inner tube 40 (shown in FIG. 6) and the tip 50 (shown in FIG. 6 ). A grabber housing 25 is attached to the distal end of the plunger 20 and is disposed about the inner tube 40 . The grabber housing 25 has two L projections projecting from a distal surface 26 . The stent/graft 30 is inserted in the same manner as illustrated in FIGS. 6-8. FIG. 10 illustrates a plan view of the distal surface 26 of the grabber housing 25 . An alternate embodiment of the grabber housing 25 or the improved stent/graft deployment catheter 21 may have the L projections 22 inset in the grabber housing 25 or the plunger 20 . Alternatively, the L projections 22 may comprise springs attached to the grabber housing 25 or plunger 20 , as illustrated in FIG. 11 . FIG. 11 illustrates a longitudinal cross section of a distal portion of an alternative embodiment of the invention incorporating spring biased projections. A proximal portion 27 of the L projection 22 is attached to the plunger 20 or to a grabber housing (not shown). A distal portion 28 of the L projection 22 is connected to the proximal portion 27 by a coil portion 29 . The coil portion 29 permits the distal portion 28 to move between a position generally parallel to a longitudinal axis 105 of the catheter 21 and a position at an angle to said axis 105 (the equilibrium position). The L projections 22 lie in grooves 106 in the plunger 20 when forced into apposition generally parallel to the axis 105 of the catheter 21 . FIG. 12 illustrates a perspective view of a stent/graft 30 being loaded into the delivery sheath 42 of the catheter 21 illustrated in FIG. 11 . During packing of the stent/graft 30 into the delivery sheath 42 the plunger 20 is positioned such that the L projections 22 are partially enveloped by the delivery sheath 42 . Next, the stent/graft 30 is manually compressed such that the V hooks 37 positively engage the L projections 22 . This engagement is accomplished by squeezing the portion of the stent/graft 30 adjacent to the V hooks 37 , placing said portion between the L projections 22 , and releasing the stent/graft 30 such that the L projections 22 and the V hooks positively engage when the stent/graft 30 partially springs back to its uncompressed state. Next, the plunger 20 is moved to the left relative to the catheter body 10 such that the L projections 22 are forced by the delivery sheath 42 towards the axis 105 of the catheter 21 and such that the delivery sheath 42 envelopes first the L projections 22 and then the stent/graft 30 . Note, that unlike the other embodiments of the invention described above, once the V hooks 37 are engaged by the L projections 22 and as long as a sufficient portion of the distal portion 28 is enveloped by the delivery sheath 42 , the stent/graft 30 no longer has to be manually compressed to maintain the positive engagement. Once the stent/graft 30 is enveloped by the delivery sheath 42 (after having passed through a funnel 24 , as described above) the L projections 22 apply a restoring force against the delivery sheath 42 . Upon deployment of the stent/graft 30 said restoring force causes the L projections 22 to spring open, i.e. away from the axis of the catheter 21 , disengaging the V hooks 37 , and thus, allowing the stent/graft 30 to expand unhindered. Note that the use of two, three, four or more L projections, in any of the above mentioned embodiments, to engage a multi-hooked stent is contemplated.

A method for inserting a stent into the delivery sheath of a stent/graft deployment catheter. The stent has V hooks on its proximal end which are positively engageable by projections attached to a stent/graft deployment catheter plunger. The proximal end of the stent is manually squeezed over the V hooks such that the V hooks engage the projections. The catheter is passed through the center of a funnel. While maintaining pressure on the stent and the V hooks, the plunger is withdrawn so as to pull the stent into the delivery sheath through the center of the funnel. The funnel guides the stent into the delivery sheath and gradually compresses the stent as it approaches the delivery sheath.

BACKGROUND OF THE INVENTION [0001] This invention relates generally to generation of electricity. More specifically, the invention relates to a generator that converts energy supplied by expanding gases and increased pressure into electrical energy. [0002] In satisfying energy needs for the future, increasing attention is being paid to smaller, localized power sources distributed through the power consuming community as an alternative to large centralized power plants. Large centralized power plants generally require large electrical distribution networks with long power transmission lines to provide the power produced to customers. Such large power transmission losses are typically associated with such distribution networks. [0003] The systems used in large centralized power plants often include rotating devices, such as steam or gas turbines or Pelton wheels. However, when scaled down for use in smaller power generation systems, high rotation speeds must be achieved to maintain acceptable system efficiencies. Such high rotations speeds often cannot be achieved without uncommon materials and/or precision machining, each of which results in increased system cost. [0004] Accordingly, a localized system of producing electrical energy that may operate with acceptable efficiencies without costly manufacturing processes is desirable. [0005] Greater attention is being paid to renewable energy sources, such as solar power, as an environmentally favorable alternative to fossil fuels. It is known in the art to capture solar energy and transform it into electrical power using photovoltaic systems However, photovoltaic systems traditionally have low efficiencies that often undermine the economic viability of such systems. Accordingly, energy production systems that utilize solar energy to produce electrical power while maintaining acceptable efficiencies are desirable. [0006] Moreover, it is desirable for an energy production system to utilize waste heat from other processes to produce electrical energy. The use of waste heat to generate electrical power that may be returned to an underlying process may increase the efficiency of the underlying process, require less energy input, and accordingly, less cost to operate. [0007] Power generation with mechanical devices that utilize a reciprocating piston are known, as are systems that utilize a second piston in a spool (e.g., a valve) to moderate a working piston. However, such systems are typically arranged in a manner that the electrical power that is produced is input into a rotating shaft that may drive an electrical generation device. As discussed above, rotating devices often require high rotating speeds and/or precision machining to achieve acceptable efficiencies [0008] Additionally, electrical generation by a magnetized piston reciprocating through a spool is also known. However, the force supplied to move the magnetized piston through the spool typically produced through mechanical means. [0009] It is accordingly desirable to provide a power generation system that utilizes heat and its corresponding effect on fluid to cause a magnetized piston to reciprocate through a coil in order to generate electrical power. The heat utilized in the power generation system may be dedicated heat, waste heat, or may be supplied by solar power. SUMMARY OF THE INVENTION [0010] Aspects of the invention may include systems and methods for generating electricity with an electronically moderated expansion electrical generator. An electrical generator according to a particular aspect of the invention may be used in conjunction with a heat exchange system having an evaporator and a condenser adapted for operating on a working fluid. The evaporator may have an evaporator intake port for receiving working fluid in a liquid state and an evaporator outflow port for transmission of working fluid in a gaseous state, and the condenser may have a condenser intake port for receiving working fluid in a gaseous state and a condenser outflow port for transmission of fluid in a liquid state. The electrical generator comprises a control circuit, a moderator and a working spool. The control circuit comprises an electrical storage module and a timing module. The moderator comprises a moderator cylinder having a moderator chamber and first, second and third moderator ports in fluid communication with the moderator chamber. The first moderator port is also in fluid communication with the evaporator outflow port and the third moderator port is also in fluid communication with the condenser intake port. The moderator further comprises a moderator coil surrounding at least a portion of the moderator cylinder. The moderator coil is in electrical communication with the control circuit. A moderator piston comprising a magnetic body is slidably disposed in the moderator chamber. The moderator piston is capable of translating between a first position wherein the first moderator port and the second moderator port are in fluid communication and a second position wherein the third moderator port and the second moderator port are in fluid communication. The working spool comprises a working spool cylinder having a working spool chamber and first, second and third working spool ports. The first working spool port is in fluid communication with the second moderator port, the second working spool port is in fluid communication with the condenser outflow port, and the third working spool port is in fluid communication with the evaporator inlet. A working spool coil surrounds at least a portion of the working spool cylinder. The working spool coil is in electrical communication with the control circuit. A working spool piston comprising a magnetic body is slidably disposed in the working spool chamber. The working spool piston divides the working spool chamber into a condenser side volume in fluid communication with the first working spool port and an evaporator side volume in fluid communication with the second working spool port. The working spool piston is capable of translating between a first position in which the second working spool port is in fluid communication with the condenser side volume and a second position wherein the second working spool port is closed. The first working spool port is configured and positioned so that when pressurized fluid is received through the first port, the pressurized fluid causes the working spool piston to translate from the first position to the second position. [0011] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed. The accompanying drawings constitute a part of the specification, illustrate certain embodiments of the invention and, together with the detailed description, serve to explain the principles of the invention. DESCRIPTION OF THE DRAWINGS [0012] In order to assist in the understanding of the invention, reference will now be made to the appended drawings, in which like reference characters refer to like elements. The drawings are exemplary only, and should not be construed as limiting the invention. [0013] FIG. 1 depicts a block diagram of an electrically moderated expansion electrical generator in accordance with some embodiments of the present invention. [0014] FIG. 2 depicts generalized schematic diagram of an electrically moderated expansion electrical generator in accordance with some embodiments of the present invention. [0015] FIG. 3 depicts an electrically moderated expansion electrical generator according to some embodiments of the invention. [0016] FIG. 4 depicts the electrical circuit of an electrically moderated expansion electrical generator according to some embodiments of the invention. [0017] FIG. 5 depicts an electrically moderated expansion electrical generator at time T 0 during a cycle according to some embodiments of the invention. [0018] FIG. 6 depicts an electrically moderated expansion electrical generator at time T 1 during a cycle according to some embodiments of the invention. [0019] FIG. 7 depicts an electrically moderated expansion electrical generator at time T 2 during a cycle according to some embodiments of the invention. [0020] FIG. 8 depicts an electrically moderated expansion electrical generator at time T 3 during a cycle according to some embodiments of the invention. [0021] FIG. 9 depicts an electrically moderated expansion electrical generator at time T 4 during a cycle according to some embodiments of the invention. [0022] FIG. 10 depicts an electrically moderated expansion electrical generator at time T 5 during a cycle according to some embodiments of the invention. [0023] FIG. 11 depicts an electrically moderated expansion electrical generator at time T 6 during a cycle according to some embodiments of the invention. [0024] FIG. 12 depicts an electrically moderated expansion electrical generator at time T 7 during a cycle according to some embodiments of the invention. [0025] FIG. 13 depicts an electrically moderated expansion electrical generator at time T 8 during a cycle according to some embodiments of the invention. [0026] FIG. 14 depicts an electrically moderated expansion electrical generator at time T 9 during a cycle according to some embodiments of the invention. [0027] FIG. 15 depicts an electrically moderated expansion electrical generator at time T 10 during a cycle according to some embodiments of the invention. [0028] FIG. 16 depicts an electrically moderated expansion electrical generator at time T 11 during a cycle according to some embodiments of the invention. DETAILED DESCRIPTION OF THE INVENTION [0029] Reference will now be made in detail to embodiments of the invention, examples of which are illustrated in the accompanying drawings [0030] With reference to FIG. 1 , a power generation system 10 in accordance with some embodiments of the present invention will now be discussed. The power generation system 10 may generally comprise a working spool 100 , a moderating spool 200 , an evaporator 300 , a condenser 400 , and a control circuit 600 . The working spool 100 comprises a piston that may be magnetized or may have magnets attached thereto disposed in a cylinder, and a coil surrounding the cylinder. The working spool 100 is fluidically connected to the moderating spool 200 , the evaporator 300 , and the condenser 400 . Such connections may be via tubing 500 , which may be any tubing, piping, or conduit sufficient to cause communication of fluids in both gaseous and liquid phases. [0031] Similar to the working spool 100 , the moderating spool 200 comprises a piston that may be magnetized or may have magnets attached thereto disposed in a cylinder, and a coil surrounding the cylinder. The moderating spool is also fluidically connected to the working spool 100 , the evaporator 300 , and the condenser 400 via tubing 500 . [0032] The evaporator 300 may be any body that contains a fluid that, when heat is applied, causes the fluid to evaporate from its liquid state to a gaseous state. The evaporator 300 is exposed to a heat source (not shown) and may be connected to the working spool 100 and moderating spool 200 via the tubing 500 . [0033] In contrast to the evaporator 300 , the condenser 400 is any body that causes a fluid in a gaseous state to cool and return to its liquid state. The condenser 400 may include a cooling device, such as but not limited to, a fan. The condenser 400 is also connected to the working spool 100 and moderating spool 200 . [0034] The control circuit 600 controls the interactions and the timing of the working spool 100 and the moderating spool 200 , and is electrically connected to the working spool 100 and the moderating spool 200 . The control circuit 600 may include various electronic components, including a power source and/or power storage device. [0035] With reference to FIGS. 1 and 2 , generalized operation of the power generation system 10 will now be discussed. Heat may be applied to the evaporator 300 , causing fluid therein to evaporate from its liquid state to a gaseous state. Such evaporation provides pressure through the open moderating spool 200 onto one surface of the a piston 10 in the working spool 100 . A small amount of electrical energy may be supplied from the control circuit 600 to the working spool coil 120 in order to prevent the working spool piston 110 from moving under the pressure. Once sufficient pressure has built up, the electrical current from the control circuit 600 is ceased, and the working spool piston 110 is subject to the increased pressure from the evaporator 300 . [0036] The increased pressure may cause the magnetized working spool piston 10 to slide in its cylinder and accordingly through the working spool coil 120 . As the working spool piston 110 slides through the working spool coil 120 , electrical energy is created, and may be captured by the control circuit 600 and stored in a power storage device (e.g., battery). Additionally, as the working spool piston 110 slides in its cylinder, it presents additional volume for the gaseous fluid to expand to. In order to maintain increased pressure, condensate from the condenser 400 may be fed to the evaporator 300 via the working spool 100 . Once the working spool piston 110 has completed its stroke, it obstructs the flow of condensate from the condenser 400 to the evaporator 300 . This prevents additional fluid pressure from being generated by the evaporator 300 . [0037] The moderating spool 200 may now be activated by the control circuit 600 . The control circuit 600 supplies electrical power to the moderating spool 200 , causing the magnetized moderating spool piston 210 to slide within its bore. When the moderating spool piston 210 has completed its travel, it opens a pathway from the working spool 100 to the condenser 400 . The gases trapped in the working spool 100 may therefore travel into the condenser 400 . The gases may be condensed to their liquid phase for later use. [0038] The control circuit 600 now supplies electrical power to the working spool 100 , in order to cause the working spool piston 100 to move within it bore and return to its starting position. By applying a current through the working spool coil 120 , the working spool piston 110 is caused to move. As the working spool piston 110 moves within its bore, it forces any additional gases out of the working spool cylinder and to the condenser 400 . During this motion, the working spool piston 110 may also draw condensate from the condenser 400 that is supplied to the evaporator 300 . Once the working spool piston 110 is back in its original position, the moderating spool piston 210 returns to its original position, either by utilizing electric power from the control circuit 600 , or by being forced back into its original position by the expanding gases of the evaporator 300 . Once the moderating piston is back to its original position, the system 10 is recharged and ready to repeat the process. [0039] The system described above is a closed loop system in which the working fluid is repeatedly caused to change phase through the use of an evaporator and a condenser. It will be understood, however, that some embodiments of the invention make use of an open system in which the working fluid is continually exhausted and replenished. In such embodiments, the evaporator may be replaced by any fluid source providing fluid at high pressure (and, in many cases, high temperature) and the condenser may be replaced by any exhaust environment at a lower pressure than that of the fluid source. Typically in such embodiments working fluid is not recaptured. One example of such a system is one in which the working fluid is the exhaust from an internal combustion engine and the exhaust environment is the atmosphere. [0040] With reference to FIG. 3 , power generation system in accordance with some embodiments of the present invention will now be discussed in more detail. A working spool 100 comprises a cylinder divided into two sides, a working evaporator side 130 and a working condenser side 140 . These sides are separated by a working spool piston 110 . The working spool piston 110 may be magnetized or may have magnets attached thereto. A working spool coil 120 surrounds at least a portion of the working spool cylinder. The working spool cylinder comprises a first port, a second port, and a third port. The first port provides communication between the working evaporator side 130 and the moderating spool 200 . The second port provides communication between the working condenser side 140 and the condenser 400 . The third port provides communication between the working condenser side 140 and the evaporator 300 . [0041] Similarly, the moderating spool 200 comprises a cylinder divided into two sides, a moderating evaporator side 230 and a moderating condenser side 240 . These sides are separated by moderating spool piston 210 . The moderating spool piston 210 may be magnetized or may have magnets attached thereto. A moderating spool coil 220 surrounds at least a portion of the moderating spool cylinder. The moderating spool cylinder may comprise a first port, a second port, and a third port. The first port provides communication between the moderating evaporator side 230 of the moderating spool and the evaporator 300 . The second port provides communication between the moderating evaporating side 230 of the moderating spool and the working evaporator side 130 of the working spool, via the working spool's first port. The third port provides communication between the moderating condenser side 240 of the moderating spool and the condenser 400 . [0042] Tubing 500 may connect the working condenser side 140 to the condenser 400 . Tubing 500 may connect the working condenser side 140 to the evaporator 300 . The tubing 500 from the condenser 400 to the working condenser side 140 and the tubing 500 from the working condenser side 140 to the evaporator 300 may be arranged such that there may be fluidic communication from the condenser 400 to the evaporator 300 via the working condenser side 140 . This fluidic communication may be prevented when the working spool piston 110 slides in the working spool cylinder into the working condenser side 140 . Alternatively, tubing 500 from the condenser 400 may connect directly to the evaporator 300 . [0043] The evaporator 300 is connected to the moderating spool 200 via additional tubing 500 . The moderating spool 200 is connected to the working spool 100 and the condenser 400 via additional tubing 500 . [0044] As can be seen from FIG. 3 , check valves 520 , 530 may be used to prevent fluids from passing through the tubing in an undesirable direction. A first check valve 520 prevents fluid from traveling from the working spool 100 to the condenser 400 , while a second check valve 530 prevents fluid from traveling from the evaporator to compression volume 140 of the working spool 100 . [0045] The electrical circuit 600 is used to regulate the power generation system, and may be used to store or transfer generated electrical power. The electrical circuit 600 is electrically connected to the working spool solenoid 120 and the moderating spool solenoid 220 . In this manner, the electrical circuit can provide electricity to, and receive generated electricity from, the working spool solenoid 120 and/or the moderating spool solenoid 220 . The specific orientation and components selected for the electrical circuit 600 may be any that allow the electrical circuit to control the working spool 100 and the moderating spool 200 , and selectively provide electricity to, and receive electricity from, the working spool 100 and the moderating spool 200 . [0046] With reference to FIG. 4 , the electrical circuit 600 generally comprises a power storage device (e.g., a battery) 620 , a diode 630 , a first and second resistor 640 , 670 , a capacitor 650 , and a transistor 660 . These components are connected via electrical wire 610 in such a manner so as to provide the functionality discussed above. [0047] With reference to FIGS. 4-16 , operation of a system in accordance with some embodiments of the present invention will now be discussed. FIG. 5 depicts an electrically moderated expansion electrical generator at time T 0 . At T 0 the working piston 110 may be disposed in the working spool 100 such that the working evaporator side 130 has a minimal volume while the working condenser side 140 has a maximum volume. In other words, the working piston 110 is positioned at one end of its stroke. At T 0 , the moderating piston 210 may be disposed in the moderating spool 200 such that the moderating evaporator side 230 has a maximum volume while the moderating condenser side 240 has a minimal volume. At T 0 fluid in its liquid phase flows through tubing 500 from the condenser 400 , through the check valve 520 , through the working condenser side 140 , and to the evaporator 300 . [0048] As shown in FIG. 6 , at time T 1 heat is applied to the evaporator 300 , causing the liquid in the evaporator 300 to boil and release and become pressurized gas. With reference to FIG. 7 , at time T 2 heat may be continually applied to the evaporator 300 and the pressurized gas may fill the tubing 500 leading from the evaporator 300 to the moderating spool 200 . [0049] At time T 3 and as illustrated in FIG. 8 , while heat is continually applied to the evaporator 300 , the pressurized gas enters and fills both the tubing 500 leading from the evaporator 300 to the moderating spool 200 and the moderating expansion volume 230 of the moderating spool 200 . [0050] As shown in FIG. 9 at time T 4 the pressurized gas flows to the working evaporator side 130 via the tubing 500 and the moderating evaporator side 230 . In order to keep the pressure elevated and constant, condensate may be provided to the evaporator 300 from the condenser 400 . As shown in FIG. 10 at time T 5 heat is applied to the evaporator 300 , and the pressurized gas fills the tubing 500 leading from the evaporator 300 to the moderating spool 200 , the moderating evaporator side 230 , the tubing 500 leading from the moderating spool 200 to the working spool 100 , and the available portion of the working evaporator side 130 . At this time, a small current may be applied from the electrical circuit 600 to the working spool coil 120 in order to resist initial movement of the working spool piston 110 . [0051] At time T 6 and with reference to FIG. 11 , increased fluid pressure in the closed system resulting from the increased heating of the fluid in the evaporator 300 may overcome the resisting force of the current applied by the working spool coil 120 to the working spool piston 110 , such that the working spool piston 110 begins to move in a direction that results in increased volume of the working condenser side 130 . As the working piston 110 moves through the working spool coil 120 , it generates a current in the working spool coil 120 that may be applied to the electrical circuit 600 . At this point, the generated current may not yet overcome the Zener diode in the electrical circuit 600 , and accordingly produced electricity may be prevented from being introduced to the full electrical circuit 600 . [0052] As shown in FIG. 12 at time T 7 the working spool piston 110 continues to move in its bore away from the pressurized fluid and through the working coil 120 , thereby creating a current in the working coil that may be applied to the electrical circuit 600 . Again, the generated current may not yet overcome the Zener diode in the electrical circuit 600 . [0053] FIG. 13 illustrates the system at time T 8 . The working piston 110 is continuing its travel through its cylinder and through the working coil 120 . At time T 8 , the current generated in the working coil 120 may overcome the Zener diode and may flow through the diode 630 and may charge the power storage device 620 (e.g., battery). The generated current may also begin to charge the capacitor 650 in the electrical circuit 600 . [0054] At time T 9 and with reference to FIG. 14 , the capacitor 650 that was charged by the electric current generated by the working coil 120 discharges, and a command current flows through the transistor 660 and to the moderating coil 220 . As the command current flows through the moderating coil 220 , a force is exerted on the moderating piston 210 , causing the moderating piston 210 to move in its bore in a manner to reduce the volume in the moderating condenser side 230 . In doing so, the moderating spool piston 210 blocks the tubing connecting the moderating spool 200 to the working spool 100 . This prevents additional gas pressure from being provided to the working spool 100 . [0055] As shown in FIG. 15 , at time T 10 the capacitor 650 discharges and the command current flows through the transistor 660 and to the moderating spool coil 220 . As the command current flows through the moderating spool coil 220 , a force may be applied to the moderating piston 210 , such that the moderating piston 210 moves in its bore in a manner to reduce the volume of the moderating evaporator side 230 . When the moderating piston 210 has moved toward the moderating evaporator side 230 a sufficient amount, fluidic communication exists between the working evaporator side 130 and the moderating spool condenser side 240 ; communication that was previously blocked by the moderating piston 210 . By opening up this communication, the addition of pressurized gas from the evaporator 300 to the working spool 100 is prevented. The pressurized gas in the working spool 100 may be released to the condenser 400 via the moderating condenser side 240 and the tubing 500 . The pressure in the working evaporator side 130 may now be lower, potentially at or near ambient atmospheric pressure. [0056] As shown in FIG. 16 , at time T 11 , a command current is applied to the working coil 120 , thereby causing the working piston 110 to slide within its bore in a manner to reduce the volume of the working spool expansion volume 120 . Such movement may push remaining gases to the condenser 400 via the moderating condenser side 240 and the tubing 500 , and may cause condensate from the condenser 400 to be drawn into the working condenser side 140 for use in the next cycle. [0057] Finally, a command current is applied to the moderating coil 220 , causing the moderating piston 210 to move in a manner to reduce the volume of the moderating condenser side 240 , and accordingly block fluidic communication between the moderating condenser side 240 and the working evaporator side 130 . The system is now reset and ready to repeat the cycle. [0058] The above description relates to the operation of a closed-loop system. It will be understood that a similar method may be used to operate an open system in which the working fluid is provided continuously from a fluid source at a particular pressure and temperature and is exhausted to an exhaust environment at a pressure lower than the fluid source pressure. [0059] It will be apparent to those skilled in the art that various modifications and variations can be made in the method, manufacture, configuration, and/or use of the present invention without departing from the scope or spirit of the invention.

An electrical generator for use in conjunction with a heat exchange system having an evaporator and a condenser is presented. The electrical generator comprises a control circuit, a moderator and a working spool. The moderator comprises a moderator cylinder having a moderator chamber and three moderator ports in fluid communication with the moderator chamber. The three moderator ports are respectively in fluid communication with the evaporator, the condenser and the working spool. The moderator and working spool each comprise a coil surrounding at least a portion of a cylinder having a piston slidably disposed therein. The working spool coil is configured for generating current upon movement of the working spool piston. Movement of the working spool piston is achieved through the selective admission of the working fluid to the working spool as controlled by the moderator and the control circuit.

FIELD OF THE INVENTION The present invention relates to masking pastes and methods for removing portions of the back electrode and photovoltaic junction from a photovoltaic laminate to create a partially transparent thin-film photovoltaic panel. Such panels may be useful in window and sun-roof applications. This method can be used to edge-delete and electrically isolate a photovoltaic panel, and to reduce the reflectivity of the sun-facing substrate surface of the photovoltaic panel. BACKGROUND A photovoltaic panel converts radiation energy into electrical energy. Of particular interest is the large-scale and cost-effective conversion of solar radiation (sunlight) into electricity using arrays of photovoltaic cells assembled into photovoltaic panels. Thin-film photovoltaic panels are typically manufactured via a multi-step process, one stage of which is the assembly of a photovoltaic laminate on a substrate. When a transparent substrate is used for the sun-facing side of a panel, it is desirable to reduce the reflectivity of the substrate surface in order to allow more sunlight to reach the photovoltaic cell and be converted to electricity. Photovoltaic laminates, which comprise one or more photovoltaic junctions disposed between front and back electrodes, are largely opaque to light transmission, due to the high light-absorption of the semiconductor junction and the presence of highly reflective metallic back electrode layers. During the manufacture of photovoltaic laminates, layers of the laminate are deposited on the substrate surface, often extending to the substrate edges. The laminate is conductive, and if not removed from the substrate edges, it can lead to electrical shorts with the panel frame. The edge region is also vulnerable to environmental corrosion. Therefore it is necessary to electrically isolate the edge region of the substrate from the interior of the laminate and remove the laminate from the panel edges. Electrical isolation of a photovoltaic panel is conventionally achieved by using a laser to cut isolation grooves of a few hundred microns width through the photovoltaic laminate around the panel edges. Edge-deletion from the substrate surface at the panel periphery (e.g., from the edge to up to 1.5 cm into the substrate) can be achieved by laser or mechanical means. Normally, light impinging on the panel can only transmit through the panel at the narrow scribe breaks where the back electrode/junction stack is divided. As a result, less than 1% of the sunlight is transmitted through the photovoltaic panel. In some applications, it is desirable to customize the degree of panel transparency and/or the light transmission pattern. For example, a significant amount of light transmission (20-50%) may be required for window or sun-roof installations. It may also be desirable to customize the color or tone of the transmitted light to match or contrast with the interior or exterior surroundings of the partially transparent photovoltaic panel. A semi-transparent photovoltaic panel has been described in which transparent conductive oxides are used for both the front and back electrodes of the laminate. The degree of transmission can be regulated by adjusting the semiconductor band gap and thickness. It is also known to fabricate a collection of holes or other polygonal apertures on at least the metallic back electrode to facilitate passage of light through the photovoltaic laminate. The junction layers can also be removed at the apertures to enhance light transmission. The apertures can be fabricated by photolithography using a photoresist layer. It is also known to fabricate a translucent photovoltaic sheet on flexible stainless steel or polymer substrates. When metallic or polymer substrates are used, light must impinge from the film side of the substrate through a transparent conductive oxide (TCO) electrode on the light-facing surface of the laminate, rather than through the substrate. Small round apertures passing through the semiconductor layers and the substrate let a portion of incident light pass through. Aperture formation can be achieved by wet etching, laser drilling or mechanical perforation. Partially transparent photovoltaic panels equipped with parallel slots cut into the opaque back electrode or electrode/junction stack have also been disclosed. A lift-off method, photolithographically defined etching, or laser drilling can be used to create the groove-shaped apertures. Reflectivity of the sun-facing substrate surface is conventionally reduced by use of a multi-layer dielectric coating, chemical etching, or sol-gel coating methods. Typically, an anti-reflective coating is created or deposited on the substrate surface prior to the deposition of the photovoltaic laminate. There remains a need for a method to produce partially transparent thin-film photovoltaic panels that is easy to use, cost-effective, efficient and adaptable to the specific application of the photovoltaic panels. There is also a need to streamline the separate processes required to electrically isolate, edge-delete, and reduce the reflectivity of the sun-facing side of the photovoltaic panel. SUMMARY One aspect of the invention is a method comprising: (a) providing a thin-film photovoltaic panel comprising: (i) a substrate; and (ii) a photovoltaic laminate comprising a front electrode disposed on the substrate, a back electrode, and one or more photovoltaic junctions disposed between the front electrode and the back electrode; (b) screen-printing a masking paste on the back electrode in a predetermined pattern to form a masked back electrode surface; (c) drying the masking paste; and (d) exposing the masked back electrode surface to an aqueous etching composition to form an etched photovoltaic laminate. This method can be used to remove portions of the back electrode not protected by the masking paste. Portions of the photovoltaic junction disposed between the unprotected portions of the back electrode and the front electrode are also removed. This method can be used to achieve partial light transparency, electrical isolation, edge-deletion, and/or reduce the reflectivity of the sun-facing surface of the photovoltaic panels. Another aspect of this invention is a masking paste comprising: a) 15-40 wt % of a copolymer of methyl methacrylate and methacrylic acid; b) 0-20 wt % phenol formal dehyde-cresol resin; c) 0-30 wt % inorganic filler; and d) 25-75 wt % of a high-boiling solvent. BRIEF DESCRIPTION OF THE FIGURES FIG. 1A is an illustration of a plan view of a thin-film photovoltaic panel after screen-printing a masking paste in a predetermined pattern. FIG. 1B is an illustration of a cross-sectional view of a thin-film photovoltaic panel after screen-printing a masking paste onto the back electrode surface. FIG. 2A is an illustration of a plan view of a thin-film photovoltaic panel after removing a portion of the back electrode and the photovoltaic junction, showing the resulting apertures in the back electrode/junction stack. FIG. 2B is an illustration of a cross-sectional view of a thin-film photovoltaic panel after removing a portion of the back electrode and the photovoltaic junction, showing the resulting apertures in the back electrode/junction stack. DETAILED DESCRIPTION One aspect of this invention is a method for achieving partial light transparency in a thin-film photovoltaic panel. As defined herein, “partial light transparency” means that 5-95% of the incident light is transmitted through the thin-film photovoltaic panel. This method can also be used to achieve electrical isolation and edge-deletion in some thin-film photovoltaic panels. It can also be used to reduce the reflectivity of the sun-facing surface of a thin-film photovoltaic panel. According to the present invention, the thin-film photovoltaic panel comprises a substrate and a photovoltaic laminate having a front electrode, a photovoltaic junction, and a back electrode. The front electrode is disposed on the substrate and the photovoltaic junction is disposed between the front and back electrodes. Glass, metal, or polymer can be employed as the substrate of the thin-film photovoltaic panel. The front electrode layer is disposed on one surface of the substrate and comprises one or more layers of metal (e.g., silver) or metal oxide (e.g., impurity-doped tin oxide, zinc oxide, or indium oxide). The back electrode comprises one or more layers of metal (e.g., silver or Ti) or metal oxide (e.g., ZnO). At least one of the front electrode and the back electrode is transparent. The photovoltaic junction comprises one or more layers of a thin-film semiconductor material. The photovoltaic junction may be a doped and/or intrinsic (i.e., undoped) semiconductor such as silicon and silicon alloys, and is disposed between the front and back electrodes. In one embodiment, the method comprises screen-printing a masking paste onto the back electrode of the photovoltaic laminate in a predetermined pattern; drying the masking paste; and exposing the photovoltaic laminate to an aqueous etching composition to remove portions of the back electrode and the photovoltaic junction that are not protected by the mask. In some embodiments, excess etchant and/or etching by-products are removed from the surface of the photovoltaic laminate, e.g., with an aqueous rinse. In some embodiments, the dried masking paste is removed after the etching step, e.g., with an aqueous stripper composition. In some embodiments, the masking paste is left in place after etching. The masking paste typically comprises high-boiling solvents (boiling point >180° C.), such as terpineol (1-methyl-4-(1-methylvinyl)cyclohexan-1-ol) or texanol (2,2,4-trimethyl-1,3-pentanediolmono(2-methylpropanoate)); acid-resistant polymers, such as co-polymers of methacrylic acid and methyl methacrylate, polyphenols and epoxy resins; optional thermal or photoinitiators; optional rheology modifiers, such as fumed silica or carbon black; optional acid-resistant fillers, such as graphite, TiO 2 , alumina, or tin oxide particles; optional pigment particles; optional surfactants; and optionally monomers containing two or more reactive groups. The masking paste is formulated to provide good screen-printed fine features, long on-screen time, high etchant resistance, and ease of aqueous stripping. Masking paste compositions can also be formulated to provide features such as good environmental durability, good adhesion to the back electrode and panel encapsulant. They may be customized for color and texture. A screen of appropriate size, tension, screen mesh, wire diameter, emulsion type, and emulsion thickness is used to print a predetermined pattern of the masking paste on the hack electrode surface of the photovoltaic laminate. The screen exhibits a pattern according to the desired percent transparency and aesthetic requirements. The pattern includes an etching pattern that can include features that define one or more isolation grooves, and edge-delete regions. The amount of light transmitted after etching the photovoltaic laminate depends on the etching pattern used and is roughly correlated with the area of the back electrode not in contact with the masking paste. In some embodiments, the pre-determined pattern of masking paste is screen-printed on 50-95%, or 60-90%), or 65-75%, and all ranges found there within of the back electrode. There are no limits on the types of patterns used, except that the pattern must preserve the series connectivity of the photovoltaic cells on the substrate. The predetermined pattern can comprise regular geometric shapes (e.g., lines, circles, regular polygons), irregular shapes, or mixtures thereof, arrayed in any pattern. A masking paste layer thickness of 10-50 microns is typically printed on the back electrode of the photovoltaic laminate. Paste rheology is controlled by formulation requirements such that the screen does not stick to the substrate surface, air bubbles and mesh marks release well from a wet print, and there is minimal paste reflow at rest and during drying to maintain printed fine features. To remove the high-boiling solvent from the wet print, the substrate can be heated by a hot plate, an oven, or by a heating lamp to about 100-150° C. for 5-10 minutes, or until the paste layer is dried. After the masking paste is dried to a typical thickness of 5-25 microns, the photovoltaic laminate is physically exposed by contacting the laminate with an aqueous etching composition in the form of a bath, a spray, or a gel coating for a predetermined dwell-time that is sufficient to etch through the back electrode and the photovoltaic junction in those areas not protected by the masking paste. Optionally, the front substrate surface is concurrently exposed to an etching composition in order to reduce the reflectivity of the front substrate surface. The amount of dwell-time required depends on the concentration of the etchant and the thicknesses of the back electrode and the photovoltaic junction. Typically, less than 1 minute to 10 minutes is sufficient dwell-time. Optionally, the etching composition can be heated to reduce the required dwell-time. In one embodiment, the temperature of the etching composition is between 20° C. and 65° C. Higher temperatures may also be used, provided that the temperature does not exceed the thermal stability limits of the substrate or the etching composition. The etching composition is typically an acidic, aqueous composition, comprising an acid such as nitric, sulfuric, hydrochloric, acetic, glycolic and/or hydrofluoric acids. The etching composition can further include fluorides (e.g., ammonium bi-fluoride) and metallic salts (e.g., silver nitrate) to improve etchant stability and durability, and acid-stable surfactants (e.g., fluorosurfactants) to improve overall etching performance. The etchant composition can be optimized for each laminate, depending on the materials used for the electrodes and semiconductor junction. The etchant composition can be further optimized to reduce the reflectivity of the front substrate surface. After etch-through, the photovoltaic laminate can be rinsed with water to wash off the etching composition and etching by-products. In some applications, the masking paste is left in place, while in others it is removed. To remove the masking paste, the laminate is exposed to an aqueous stripper composition in the form of a bath or a spray. The aqueous stripper composition typically comprises: an alkaline salt, such as sodium carbonate; bases, such as sodium hydroxide, potassium hydroxide or tetra-ammonium hydroxide; and optionally base-stable surfactants. Typically, less than 1 to 5 minutes is sufficient dwell-time for paste removal. Optionally, the temperature of the stripper composition can be increased to reduce the required dwell-time. In one embodiment, the temperature of the aqueous stripping composition is between 20° C. and 65° C. In some embodiments, a high-pressure spray of the stripper, followed by water, is used to remove the masking paste. In one embodiment, the front electrode is transparent fluorine-doped tin oxide (FTO), the back electrode is doped ZnO and silver, the substrate is glass and the photovoltaic junction layer is amorphous silicon. Because FTO is difficult to wet-etch, electrical isolation and edge-deletion of photovoltaic panels incorporating an FTO front electrode must be carried out in separate processes involving laser or mechanical means. The reflectivity of the substrate surface(s) can be reduced by dipping the panel in an etchant bath or spraying both sides of the panel with etchant. Due to a high light absorption of the amorphous silicon junction layer and the highly reflective silver back electrode layer, the resulting laminate is largely opaque to light transmission. Before etching, light impinging on such a panel can only transmit through the panel at the narrow scribe breaks. Since the scribe break is typically less than 100 microns in width, only a very small percentage of sunlight (<1%) is usually transmitted through the photovoltaic panel. However, partial light transparency can be achieved as described herein by screen-printing a masking paste onto the back electrode of the photovoltaic laminate in a predetermined pattern; drying the masking paste; and exposing the photovoltaic laminate to an aqueous etching composition to remove portions of the back electrode and the photovoltaic junction. In another embodiment, the front electrode is transparent aluminum-doped zinc oxide (AZO) the back electrode is ZnO and silver, the substrate is glass, and the photovoltaic junction layer is amorphous silicon. Since the AZO front electrode can readily be etched, electrical isolation grooves and edge-delete regions can be incorporated in the screen pattern. By exposing both sides of the panel to the aqueous etchant, the chemical etching process removes all layers of the laminate at regions not masked by the masking paste, achieving partial transparency, electrical isolation, edge-deletion, and reflectivity reduction in a single process. In another embodiment, the front and back electrodes are doped zinc oxide (ZnO), the substrate is glass and the junction layer is amorphous silicon. A masking paste formulated with TiO 2 particles and epoxy resins is printed on the back electrode surface. The printed pattern contains features for an isolation groove and edge-deletion, and may also contain features for partial transparency. Thermal curing of the epoxy resin produces a white mask layer that is left in place after chemical etching. This white coating also provides a light trapping function to improve solar energy conversion efficiency. The etching process can thus achieve one or more of electrical isolation, edge-deletion, reflectivity reduction, light-trapping, and partial transparency. In another embodiment, the front electrode is doped ZnO, the back electrode is doped ZnO and silver, the substrate is glass and the tandem photovoltaic junction layers are amorphous silicon and micro-crystalline silicon. Due to the substantially increased thickness of the photovoltaic junction layers, the masking paste is formulated with crosslinking monomers to allow for increased dwell-time for deep etching. Printed with the appropriate pattern of this masking paste, the etching process can achieve one or more of electrical isolation, edge-deletion, reduced reflectivity, and partial transparency for a tandem photovoltaic junction panel with high solar energy conversion efficiency. In another embodiment, the front electrode is doped ZnO, the back electrode is doped ZnO and silver, the substrate is glass and the triple photovoltaic junction layers are amorphous silicon, amorphous silicon-germanium alloy, and micro-crystalline silicon. Printed with the appropriate pattern of a high-performance masking paste, the etching process can achieve one or more of electrical isolation, edge-deletion, reflectivity reduction, and partial transparency for a triple photovoltaic junction panel with very high solar energy conversion efficiency. FIG. 1A illustrates a plan view of a thin-film photovoltaic panel after screen-printing a masking paste in a predetermined pattern and FIG. 1B illustrates a cross-sectional view of a thin-film photovoltaic panel after screen-printing a masking paste 15 onto the back electrode surface. The panel comprises a substrate 11 , a TCO front electrode 12 a disposed on the substrate 11 , and a plurality of breaks 12 b to divide the TCO layer into strips of cell electrodes. Also shown is an amorphous silicon junction layer 13 a that is at least partially disposed on the TCO front electrode 12 a and also makes contact with the substrate through breaks 12 b . The junction layer 13 a is separated into regions by breaks 13 b , A back electrode 14 a is at least partially disposed on junction layer 13 a and makes contact with the front electrode 12 a through breaks 13 b . Breaks 14 b through the junction layer 13 a and the back electrode 14 a divide the panel into strips of electrical series-connected cells. FIG. 2A is an illustration of a plan view of a thin-film photovoltaic panel after removing a portion of the back electrode and the photovoltaic junction, showing the resulting apertures 26 in the back electrode/junction stack. FIG. 2B is an illustration of a cross-sectional view of a thin-film photovoltaic panel after removing a portion of the back electrode and the photovoltaic junction, showing the resulting apertures 26 in the back electrode/junction stack and an anti-reflective front substrate surface 27 . The etching process allows additional light 28 to be transmitted through the photovoltaic panel. EXAMPLE A thin-film photovoltaic panel was prepared on a glass substrate by sequential depositions of an FTO front electrode, an amorphous silicon single photovoltaic junction, and a ZnO/silver back electrode. Three laser scribing steps were used to monolithically integrate two series-connected cells on the panel. A panel sample was supplied by DuPont Apollo, a subsidiary of E. I. du Pont de Nemours and Company. As prepared, the panel had near zero transparency. An open circuit voltage of 1.7 V and a short circuit current of 45.8 mA were measured with a Newport 91159 solar simulator equipped with a filter of Air Mass 1.5 Global (AM1.5G) at an intensity of 100 mW/cm 2 (or 1 sun). A masking paste was formulated by dissolving 3 g of an 80/20 copolymer of methylmethacrylate and methacrylic acid into 6 g of terpineol. Carbon black (0.5 g) was roll-milled into the copolymer solution to produce a printable masking paste. A screen with 20% closed- and 80% open-mesh areas was prepared with 250 count stainless steel wires and a 25 micron-thick emulsion. The pattern consisted of 200, 300, and 400 micron closed-mesh lines. The masking paste was printed on the back electrode surface using a manually operated screen-printer. The wet print was allowed to rest for 10 minutes, and then dried for 10 minutes on a 135° C. hotplate. An aqueous etchant was prepared by mixing 2 ml of 50 wt % HF, 20 ml of 70 wt % nitric acid, and 78 ml of water. The etchant was pre-heated to 60° C. The substrate coated with dried masking paste was dipped in the etchant for 1 minute, during which time the metallic back electrode and silicon junction were etched clean in areas that were not protected by the masking paste. The etched panel was rinsed in water and the masking paste was removed by dipping in an aqueous stripper consisting of 0.5 wt % sodium carbonate for 5 minutes at room temperature. The panel was rinsed in water and blow-dried with compressed air. Light-transparent regions consisting of approximately 200, 300, and 400 micron lines were evident on the etched panel. The percent reflection of the panel was measured with a Perkin-Elmer Lambda 900 UV/VIS/NIR spectrophotometer equipped with an integrating sphere. The percent reflection was found to be reduced by 1.3% after etching. As before, an open circuit voltage of 1.7 V at one sun was measured, indicating a well-functioning etched panel. A short-circuit current of 36.5 mA was also measured, giving 79.8% of the original value for a 20% see-thru panel. This confirms that no unexplained efficiency loss was encountered as a result of the etching process.

The present invention relates to masking pastes and methods for removing portions of the back electrode and photovoltaic junction from a photovoltaic laminate to create a partially transparent thin-film photovoltaic panel. Such panels may be useful in window and sun-roof applications. This method can be used to edge-delete and electrically isolate a photovoltaic panel and to reduce the reflectivity of the sun-facing substrate surface.

CROSS-REFERENCE TO RELATED APPLICATIONS AND OTHER DOCUMENTS [0001] This application claims the benefit of prior U.S. provisional application No. 62/085,509, filed 29 Nov. 2014, the contents of which are incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] This invention relates to systems and methods of rapid prototyping and production (or called additive manufacturing or 3D printing). Especially, this invention relates to fabricating 3D prototypes, articles, components and molds at improved surface finish and increased speed. [0003] Existing major rapid prototyping (also known as additive manufacturing or 3D printing) techniques include methods such as SLM (Selective Laser Melting) for making metal parts (for examples, EOS M400, referring to http://www.eos.info/systems_solutions/metal/systems_equipment/eos_m_400, 3D Systems SPro 250, see http://production3dprinters.com/sites/production3dprinters.com/files/downloads/sPro-125-250-SLM-Direct-Metal.pdf, or Renishaw AM250, referring to http://www.renishaw.com/en/am250-laser-melting-machine--15253)), and SLA ((Stereolithography) (for example, 3D Systems ProJet HD 7000, referring to http://printin3d.com/sites/printin3d.com/files/downloads/ProJet-6000-7000-USEN.pdf), FDM (Fused Deposition Modeling) (e.g. Stratasys FDM 900m, referring to http://www.fortus.com/Products/Fortus-900mc.aspx) and 3DP (3D Printing) (jetting binders to powder bed layer-by-layer) for making plastic parts. [0004] In general, these existing rapid prototyping methods apply a layer-by-layer construction methodology. Materials are dispensed in horizontal layers and within each layer joined by point scanning. Material build-up by horizontal layers, regardless of the 3D shape to be built, creates inevitable layered (stairs-like) surface feature, resulting in poor surface finish. Material joining by point scanning is basically “scanning a 3D body by one tiny point”, resulting in slow build-up rate. Combined operation of layer dispensing and point-scanning joining slows down the process further. FIG. 1 illustrates an example 3D part. FIG. 2 illustrates the fabrication of this example 3D part by the existing methodology. FIG. 2( a ) shows the blade portion and FIG. 2( b ) shows the cross-sectional view. Dotted lines 201 indicate the grid structure of horizontal layers and solid curves 203 indicate trajectories of point scanning. Stairs-like surface features at 214 and 212 are inevitable. [0005] When using the SLM technique to make a mold for plastic injection molding, the surface finish can be about 40 um Ra and a machining tolerance of 200˜500 um is generally required, which makes post machining cost significant. There are studies on post polishing using laser beams. (Referring to Lamikiz et al., “Laser polishing of parts built up by selective laser sintering”; International Journal of Machine Tools & Manufacture 47 (2007) 2040-2050). In order to improve forming speed, a so called “skin-core strategy” was developed, which uses a laser of small focal spot to scan edges of patterns in each layer and a larger focal spot to scan the interior. (Referring to (1) K. Wissenbach, “Fantasia Project Shows Selective Laser Melting Can Produce Complex Components Quickly and Cost Effectively”, http://www.ineffableisland.com/2010/05/fantasia-project-shows-selective-laser.html?showComment=1318241730096; (2) C. Hinke, “Direct, Mould-less Production Systems”, http://www.production-research.de/_C12577F20052BDC7.nsf/html/de_040d66b2c812b739c1257829005207de.html). But these methods also increase equipment costs. [0006] In the FDM technique, U.S. Pat. No. 5,121,329, which is incorporated herein for this current application by reference, describes methods of moving a material dispensing head along curved trajectories to produce curved surfaces or frames and of dispensing materials of variable thickness by changing material feed rate (referring to FIG. 10 and FIG. 12 of that patent). However, because the FDM method uses a fixed orifice size to dispense material, the effect of speed Increasing is likely to be limited. In another FDM related technique, U.S. Pat. No. 8,221,669, which is incorporated herein for this current application by reference, describes the use of ribbon (non-cylindrical) filament as material, in contrast to the cylindrical filament used in most current commercial systems, in order to reduce the so called “response time”, that is, the delay time from the start or stop of the feeding mechanism to the actual flow rate change at the tip of the extrusion tip of the liquefier. But it should be noted that faster material deposition is not the purpose nor mentioned in this patent. [0007] There are other methods developed or under development for making metal objects. [0008] For example, applying the FDM technique to make metal parts has been attempted. U.S. Pat. No. 7,942,987, which is incorporated herein for this current application by reference, describes a method of heating a metal alloy to a temperature between a solidus temperature and a liquidus temperature to obtain a semi-solid metal alloy with enough viscosity so that it can be extruded. However, the “point scanning” and “layer by layer” issues are not addressed in this approach. [0009] Another approach is called Laser Deposition Technology (LDT) or Laser Engineered Net Shape (LENS). Metal powder is injected into a focused beam of a high-power laser under tightly controlled atmospheric conditions. The focused laser beam melts the surface of the target material and generates a small molten pool of base material. Powder delivered into this same spot is absorbed into the melt pool, thus generating a deposit. By moving the laser beam and the deposition relative to the target material, 3D shapes can be built up. A description of the process can be found from http://www.rpm-innovations.com/laser_deposition_technology and related technical details can be seen in U.S. Pat. No. 4,323,756 and No. 5,043,548, which are incorporated herein by reference. A very similar method, except using wire metal instead of powder, was described in U.S. Pat. No. 5,578,227, which is incorporated herein by reference. In general, these approaches are basically still a “point scanning” based approach. Further, surfaces of built-up parts are usually rough. BRIEF SUMMARY OF THE INVENTION [0010] The basic principle of the Flexible 3D Freeform technique is to dispense a solidifiable material in a fluid state from a dispensing head onto a base member to build up the material, which solidifies under preset ambient conditions, in a basically continuous fashion according to a predetermined relative movement sequence between the dispensing head and the base member. Based on this principle, this invention comprises a feature of dispensing the solidifiable material along the tangential directions of the surface of the 3D article to be fabricated so that the layered surface feature in existing rapid prototyping processes is eliminated and the surface finish is improved. This invention also comprises a feature of enlarged width of dispensed materials and a corresponding new 3D forming procedure so that fabrication speed can be increased significantly. For these purposes, this invention includes a motion mechanism of multiple degrees of freedom to provide the required relative movement sequence between the dispensing head and the base member. Further, this invention includes a feature of adjusting the width, thickness and flow speed of the dispensed material according to needs from local geometry of a 3D article during the dispensing process. The dispensing head dispenses material in a few basic shapes including ribbon (band), wire and dot. When the geometry of the 3D object to be fabricated allows, wide, ribbon-shaped material can be dispensed so that building speed can be increased. Dispensed materials of wire- and dot-shapes can be applied to build up fine and complex features. Still further, this invention includes a differential molding means, which applies a solid or fluid means in contact with selected positions on dispensed material while it is solidifying, to restrict the flow of and to shape the solidifying material. By this means, good surface finish can be obtained. Curvature in the direction along the width of a ribbon-shaped dispensed material can also be made by this means. [0011] A variation of this invention is to dispense a joinable material in particulate form and simultaneously apply a joining means to the material dispensed at the target area such that the dispensed particulate material starts to join into an integral material. BRIEF DESCRIPTION OF THE DRAWINGS [0012] FIG. 1 depicts an example of 3D article. [0013] FIG. 2 illustrates the layer-by-layer construction methodology used in the prior arts. [0014] FIG. 3 explains the basic concept of this invention using the 3D object depicted in FIG. 1 as an example. [0015] FIG. 4 illustrates the spatial relationship between a material dispensing head of this invention and an example 3D surface. [0016] FIG. 5 illustrates two examples of mechanisms to provide the required relative movements between the material dispensing head and the base in this invention. [0017] FIG. 6 depicts two methods to form a 3D thin-shell surface from joining ribbon-shaped materials together by this invention [0018] FIG. 7( a ) illustrates an example embodiment of a material dispensing system for metal in this invention; (b)-(c) illustrates its cross-sectional views from side. [0019] FIG. 8 illustrates another example of the material supply unit in cross-sectional view, using an induction heating means to melt a metal wire, and operation of the differential molding means in this invention. [0020] FIG. 9 illustrates an example method of adjusting cross-sectional size of dispensed material during dispensing by adjusting dispensing head orientation in this invention. [0021] FIG. 10 illustrates another example method of adjusting cross-sectional size of dispensed material during dispensing by adjusting dispensing head orientation in this invention. [0022] FIG. 11 illustrates an example approach of adjusting cross-sectional size of dispensed material during dispensing by adjusting dimension of the exit of the dispensing head in this invention. [0023] FIG. 12 illustrates another example approach of adjusting cross-sectional size of dispensed material during dispensing by adjusting dimension of the exit of the dispensing head in this invention. [0024] FIG. 13 illustrates forming of an arbitrarily twisted ribbon shape by relative motions between the base and the dispensing head in this invention. [0025] FIG. 14 illustrates examples of operation of the differential molding means in this invention. [0026] FIG. 15 illustrates an example design of the differential molding means based on material deformation in this invention. [0027] FIG. 16 illustrates another example design of the differential molding means based on non-deformable shapes in this invention. [0028] FIG. 17 illustrates an example design of the differential molding means for controlling dimension of width of dispensed material in this invention. [0029] FIG. 18 illustrates another example design of the differential molding means based on fluid flow and pressure in this invention. [0030] FIG. 19 illustrates an example design of mounting and retracting mechanism of the differential molds system in this invention. [0031] FIG. 20 illustrates still another example approach of adjusting cross-sectional size of dispensed material during dispensing by adjusting dimension of the exit of the dispensing head in this invention. [0032] FIG. 21 illustrates still another example approach of adjusting cross-sectional size of dispensed material during dispensing by adjusting dimension of the exit of the dispensing head in this invention. [0033] FIG. 22 illustrates an example approach of using an arc-based heating unit for auxiliary and localized heating in this invention. [0034] FIG. 23 illustrates an example process of making a 3D article by this invention. [0035] FIG. 24 illustrates an example of making a mold core by the flexible mold surface forming technique in this invention. [0036] FIG. 25 illustrates another example of making a mold core by the flexible mold surface forming technique in this invention. [0037] FIG. 26 illustrates an example of making a mold cavity by this invention. [0038] FIG. 27 illustrates still another example approach of adjusting cross-sectional size of dispensed material during dispensing by adjusting dimension of the exit of the dispensing head in this invention. [0039] FIG. 28 illustrates still another example approach of adjusting cross-sectional size of dispensed material during dispensing by adjusting dimension of the exit of the dispensing head in this invention. DETAILED DESCRIPTION [0040] FIG. 3 explains the basic concept of the invention using the 3D object depicted in FIG. 1 as an example. When making the hub 102 , materials can be dispensed in horizontal layers and built up vertically, as shown by 310 of FIG. 3( b ) , similar to 212 of FIG. 1( b ) , because the inner wall of the hub is vertical. However, when making the outer wall, the preferred material dispensing direction is along the tangential direction of the wall, so that stair-like features can be eliminated and good surface finish can be obtained ( 312 ). Especially, when making the blades 103 , dispensing materials along the tangential direction of the curved blade geometry can improve surface finish very significantly ( FIG. 3( b ) 314 ). In FIG. 3 ( a ) , dotted-lines 301 depict the grid structure using this Flexible 3D Freeform technique. The grid structure has 3 layers stacked together and each layer is distributed along the tangential direction of the curved blade geometry. Materials dispensed according to the grid structure are shown as 318 a , 318 b and 318 c. [0041] Moving the dispensing head to trace arbitrary 3D surfaces relative to the base member requires a mechanism of multiple degrees of freedoms. In general, if the exit of the material dispensing head is just a single orifice, close to a spot or a point in geometry, then a motion means of 3 degree-of-freedom (DOF) is enough to allow a section of an arbitrary 3D surface to be traced by a point spot. However, if dispensing of wide band-shaped material is preferred, then a motion means of at least 4 DOF is preferred. FIG. 4( a ) illustrates the situation. The exit of the material dispensing head 403 has a long (width) edge 405 a and a short edge 405 b . In order to dispense material at maximal width, the dispensing head must move and trace the 3D surface 110 in a direction perpendicular to the edge 405 a . In order to accommodate the change of surface curvature perpendicular to the motion direction (which is x-direction in FIG. 4 ), one rotational DOF (A-axis, which rotates about x-direction) is needed. That is, the system has 3 independent linear DOFs (x, y, z) and one rotary DOF (A). A more preferred arrangement applies 3 independent linear DOFs (x, y, z) and 2 rotary DOF (A and B, which rotates about y-direction). This is illustrated in FIG. 4( b ) . The addition of B DOF allows the dispensing head to always maintain a fixed angle with respect to the target area. A still more preferred arrangement is to add a third rotary DOF C, which rotates about z-direction. This allows the dispensing head to move in basically any direction with maximal dispensing width, or with any reduced dispensing width, which will be further described in later texts. [0042] There are many options of mechanisms to provide the required relative movements between the material dispensing head and the base. FIG. 5( a ) illustrates one example, which is basically in a robotic arm configuration 520 . The rotations at 3 joints, J 1 , J 2 and J 3 , can place the end 521 of the robotic arm to basically any position (x, y, z) relative the base area 501 , whereas A. B and C 3 axes can rotate the material dispensing system 401 to any orientation. FIG. 5( b ) illustrates another example, which is basically a 5-DOF (5-axis) mechanism comprising 3 linear DOFs (X, Y, Z) and 2 rotational DOFs (A about X-axis and B about Y-axis). The base area 501 , carrying the base and the 3D article to be fabricated on the base, is attached to the A-axis rotary stage. The material dispensing system is attached to the Z-stage. The dispensing head can rotate about the Z-axis, forming the 6th DOF (C-axis). Other configurations and variations can be made by people skilled in the arts based on the teaching of this current document. [0043] Further, this invention includes the feature of adjusting width and thickness of the dispensed material according to needs from local geometric characteristics of a 3D article during the dispensing process. The dispensing head dispenses material in a few basic shapes including ribbon (band), wire and dot. When the geometry of the 3D object to be fabricated allows, wide, ribbon-shaped material can be dispensed so that building speed can be increased. If geometric features to be built are small and fine, then the width and thickness of the dispensed material can be reduced to dispense wires and dots accommodate the situation. [0044] For example, FIG. 6( a ) depicts a 3D thin-shell surface comprising 5 ribbon-shaped materials joined together ( 368 a - e ). 350 indicates the cross-sectional curve of an ideal smooth 3D curved surface. The curvature on one side ( 350 a ) is larger than that on the other side ( 350 b ). When this surface is fabricated using the current invention, the side with smaller curvature can be made by dispensing and joining wider ribbon materials, such as 368 d and 368 e , whereas the side with larger curvature requires ribbon materials of smaller width, such as 368 a and 368 b . Wider ribbons correspond to faster build rate, which speeds up the whole fabrication process. Accordingly, this feature allows maximization of material dispensing rate based on local geometry. [0045] There are at least 2 methods to adjust width and thickness of dispensed materials. The first method adjusts the orientation of the dispensing head together with the material flow rate to change size of cross-sections of dispensed materials. The second method applies a dispensing head with an adjustable exit. Details will be described in later texts. [0046] Still further, this invention includes a differential molding means, which applies a solid or fluid means in contact with selected positions on dispensed material while it is solidifying, to restrict the flow of and to shape the solidifying material. By this means, good surface finish can be obtained. A further variation of this means can create curvature in the direction along the width of a ribbon-shaped dispensed material, in order to match curvatures of local geometries. For example, in the 3D thin-shell surface depicted in FIG. 6( a ) , if the ribbon-shaped dispensed materials have rectangular cross-section, as illustrated as 3681 , then the fabricated surface will not completely match the ideal cross-sectional curve 350 . However, as illustrated in FIG. 6( b ) , if the dispensed ribbon-shaped material can be made to have curvature along its width direction, then every band ( 367 a - e ) can be made to match the local curvature of the ideal cross-sectional curve 350 , and the fabricated object will have 3D curvatures closely matching the ideal smooth 3D curved surface. [0047] Differential molding by solid means applies a small solid surface (called “differential mold”) in contact with selected portions of the dispensed material while it is solidifying, to restrict the flow of and to shape the solidifying material. This solid means further comprises mechanisms to change curvature in the width direction of the dispensed solidifying material. Differential molding by fluid means applies different pressures generated from fluid flows to achieve similar effects. Details are to be described in later texts. [0048] Combining a motion mechanism capable of multiple-DOF flexible 3D paths, a material dispensing head that can adjust the size of dispensed material, and a differential molding means that can shape curvature of the dispensed material in the width direction, fast fabrication of 3D curved surface can be realized. As illustrated in FIG. 3( b ) , each of the ribbon-shaped structures depicted by different tones of gray ( 318 a , 318 b , 318 c , and 318 d ) represent one band of ribbon-shaped material dispensed by the dispensing head in a single pass. For example, the light gray band structure 318 c is formed by a dispensing motion that basically sweeps a curve PQ along the direction of arrow 390 . This maximizes material deposition rate. [0049] Accordingly, this invention includes the following procedure of fabricating a 3D article: [0050] (1) Analyze the geometric shape and the requirements (such as surface finish, material forming direction or strength requirements etc.) of different portions of the 3D article and make a process plan. This process plan divides the geometric data of the 3D article into a number of zones and sets an order of sequence of fabrication of these zones. [0051] (2) Based on the process plan, disassemble the geometric data of the 3D article and generate a collection of Component Geometries that can be recombined to form the shape of the 3D article. The so called Component Geometries include geometric volumes of bands (ribbons), wires (lines) and dots (points). Further identify and select zones that require good surface finish and then disassemble and convert these selected zones into collections of band and wire Component Geometries. [0052] (3) For each Component Geometry generated in step (2), determine a corresponding set of forming parameters (including thickness, width, curvature and dispensing trajectory). [0053] (4) For each set of forming parameters generated in step (3), determine a set of process parameters, including material feed rate, ambient conditions (such as temperature), material dispensing rate, dispensing head speed etc. [0054] (5) Following the sequence determined in the process plan, dispensing material to form each Component Geometry. The forming method for each Component Geometry is to move the material dispensing system (including the dispensing head and the differential molding means) along the dispensing trajectory, relatively, and dispense solidifiable material according to the corresponding set of forming parameters. [0000] By forming each Component Geometry in sequence, all the Component Geometries combine to form the 3D article. [0055] Under proper situations, the dispensing head capable of adjusting exit size and the differential molding means for curvature formation do not need to be applied together. For example, the 3D thin-shell curved surface of FIG. 6( a ) can be fabricated without using the differential molding means for curvature formation. [0056] In the broadest sense, the solidifiable material of this invention includes any material that has a fluid state and can be converted into a solid state under specific environmental conditions. [0057] For example, many polymers exhibit the property. Most thermoplastics exhibit fluid state at elevated temperatures and solidify at lower temperatures. Typical examples include Nylon, PMMA and polystyrene (PS) such as ABS etc. Wax is another material that exhibits the property depending on temperature. Wax is another material that exhibits the solidifiable property based on temperature. [0058] Polymer materials can be dispensed by extruding, which corresponds to plastics extrusion processes in traditional bulk plastic processes, or by jetting (Injection from fluid state), which corresponds to injection molding. [0059] Photo-curable polymers, such as photoresist and liquid photo-lithographical polymer used in the SLA process, can also be used. In this case, the environmental condition that solidifies the polymers is mainly exposure of light, especially UV light. [0060] The solidifiable materials can be metals, which exhibit the solidifiable property based on temperature. In analogy to traditional bulk processes, such as casting, continuous casting and fusion welding, molten metal can be dispensed from a dispensing head, such as a tundish with a nozzle, and then be allowed to cool down and solidify. Molten metals, especially those of lower melting points, can also be dispensed by injection, in analogy to metal injections applied in die casting. Another method to dispense molten metal is to shoot metal droplets. [0061] Another form of solidifiable materials includes pastes, that is, the mixture of fine solid particles and a liquid state carrier. For example, in the prior art of the process of metal injection molding, metal particles are mixed with a fluid carrier made of polymer and wax at an elevated temperature. This mixture is then injected into a mold and cooled down and becomes a solid. The wax and the polymer are then removed in a melting and burning process, leaving a green part composed of metal powder, which is then sintered. In the current invention, a similar mixture of metal powder with wax and polymer in fluid state at elevated temperature can be used as the solidifiable material and temperature can be used as the main control of environmental condition. Solid parts can be dispensed by extrusion or by injection and be built up in the manner described previously. The same processes of wax/polymer removal and sintering can then be applied to make the final solid metal parts. [0062] Another example of paste includes ceramic slurry, which is basically a mixture of fine ceramic powder with water and binders. The mixture can be dispensed and built up in the manner described previously. Depending on the fluidity and viscosity of the mixture, the material can be dispensed either by jetting (injection), if the fluidity is high and viscosity is low, or by extrusion, if the fluidity is low and the viscosity is high. Simultaneously with the dispensing, a flow of heated air can be applied to the dispensed material at the target zone to quicken the drying process. A green part can thus be formed. The green part can then be sintered into a solid ceramic part. [0063] Still another example of paste is concrete. [0064] Another form of solidifiable material is glass. It can be extruded and temperature can be used as the main environmental control to solidify it. [0065] A variation of this invention is to dispense a joinable material in particulate form and simultaneously apply a joining means to the material dispensed at the target area such that the dispensed particulate material starts to join into an integral material. For example, metal or plastic powders can be used as the particulate joinable materials and a localized heating, which can be provided by a laser or an electric arc, can be used as the joining means. The dispensed powder is partially or fully melted by the localized heating and then, when out of the localized heat, cools down and re-solidifies into an integral part. For another example, a separate localized dispensing of binder material to the dispensed powder can be used as the joining means. Various binder materials used in processes such metal powder injection molding or ceramic powder molding can be used to join metal and ceramic powders. [0066] A system of this invention includes a material dispensing head, a motion mechanism of multiple-DOF, which can generate flexible 3D paths between the dispensing head and the base, a material supply system that can control material feed rate and an ambient condition control system. It can further include a differential molding means that can shape curvature of the dispensed material in the width direction. The processing method includes the process plan mentioned previously, the process of disassembling geometric data, the process of generating the forming parameters and processing parameters, as well as the procedure of controlling the operation of the material dispensing head and the differential molding means, and the procedure of controlling the multi-DOF motion mechanism. Examples of embodiment of the invention are further described below. Example 1 Molten Metal as Solidifiable Material, 3D Freeform by a Casting Based Means 1.1 the Material Dispensing System [0067] FIG. 7( a ) illustrates an example embodiment of a material dispensing system for metal, which includes a material supply unit 402 , a dispensing head 403 and an optional differential molding means 420 . FIG. 7( b )-( c ) illustrates its cross-sectional views from side. The material supply unit 402 , which includes a heating means (such as induction heating or electric arc heating) and a material feeding means (a metal wire powder can be used), sends the material into the dispensing head 403 . The dispensing head includes a material cell 404 with an exit 405 at the lower end. A heating means outside of the material cell keeps the metal in molten state 480 . A material not reactive to the molten metal is preferred for making the material cell. For example, aluminum oxide, graphite or other high temperature ceramics can be used to contain molten steel. Ceramics can also be used for metals of high melting points, such as titanium, cobalt, chromium and nickel alloys. Steel cells can be used to contain molten copper, aluminum can be used for molten tin; whereas molten aluminum can use titanium, titanium coated with boron nitride, or steel coated with nitralloy. The molten metal can flow out of the exit under the effect of gravity. Alternatively, a gas pressure from the top of the material cell can push the molten metal out of the exit. The actual size of the material cell and the exit depends on size of the 3D article to make, dimensional tolerance and materials. [0068] FIG. 8 illustrates a different example of the material supply unit 402 in cross-sectional view, wherein an Induction heating means 495 melts a metal wire 470 . The solid metal wire 470 is fed from rear end and can push and retract the molten metal 480 at the front like a piston. The material supply unit, the dispensing head 403 , and the heating means are packed inside a casing 497 and an inert gas 499 , such as argon or CO 2 , blows through the casing to cover the whole system including the material dispensing and solidification area to prevent oxidation of metal. [0069] As the molten metal flows out of the exit, it forms a droplet attached to the outside of the exit due to surface tension. By touching the droplet with the base (or solidified material on the base), the temperature of the droplet decreases due to thermal conduction and solidification starts. FIG. 7 and FIG. 8( b ) depict the initial stage of the material dispensing process, the metal droplet touches a metal plate 431 , which is attached to the base (metal frame 430 ) and is used as a starting point of the forming process. The base 430 together with the starting metal plate 431 then act as a heat sink and the metal droplet starts to solidify from the contact position 450 at the starting metal plate. The ambient condition control unit (not shown) controls the temperatures of the base and the starting metal plate within a proper range and the heating means around the material dispensing head 403 sets the temperature of the molten metal at an elevated, proper range. When the base with the starting metal plate moves along the direction indicated by arrow 490 , the metal can be dispensed, formed and solidified in a manner similar to continuous casting. Metal 453 close to the exit of the dispensing head is in molten state. A little away from the exit, there is a short solidification zone 452 wherein the molten metal solidifies. Further away from the exit and the solidification zone, solidified metal forms a band-shaped solid 451 , which extends to the initial solidification point 450 . Because of the effect of surface tension, as long as the temperatures and the speeds of motion and material supply are properly controlled, molten metal will flow out of the exit and follow the solidification path without dripping down. In the situation shown in FIG. 8( a ) , molten metal is dispensed onto the surface of previously dispensed and solidified metal 514 , which also becomes a part of the heat sink. 1.2 Motion System [0070] A motion system with multiple degrees of freedom is used to provide relative motion between the material dispensing head and a base member. This part has been described in previous sections related to FIG. 4 and FIG. 5 . For example, as shown in FIG. 13 , the base member (metal frame 430 ) is attached to a structure 610 on the base 501 of a motion system. By relative motions between the base and the dispensing head 403 , a surface of arbitrarily twisted shape 380 can be made. 1.3 Systems and Methods for Adjusting Cross-Sectional Size of Dispensed Material [0071] The first preferred method of adjusting cross-sectional size of dispensed material during dispensing is to adjust the angle of the dispensing head relative to the track of dispensing motion and adjust material flow rate. As depicted in FIG. 9 , changing the angle 702 of the leading edge 405 a of the exit of the dispensing head relative to the motion direction of dispensing 701 , with matched adjustment of material flow rate, band-shaped materials of the same thickness but different widths can be dispensed, as illustrates at 710 a , 710 b and 710 c . Depicted in FIG. 10 , reorient the dispensing head and changing the angle 703 of the leading edge 405 a relative to the vertical direction, with matched adjustment of material flow rate, vertical wall-shaped materials of the same thickness but different heights can be dispensed, as illustrated at 711 a , 711 b and 711 c. [0072] The second preferred method of adjusting cross-sectional size of dispensed material during dispensing is to use a gating mechanism to adjust the dimension of the exit of the dispensing head. FIG. 11 depicts one example design of the material dispensing head with adjustable exit size. The material-containing cell 404 in this design includes 3 main parts: a U-shaped main body 404 A 1 , a side-slab 404 A 3 that inserts into and slides in the main body and an exit lip 404 A 4 that slides over the exit 405 . (Restraining structures and bearings of the sliding mechanisms are not shown.) Pulling the slide slab along arrow 901 a increases the length of the exit 405 and moving the exit lip along arrow 902 a opens the exit to the maximal size, as illustrated in FIG. 11( a ) . Pushing the slide slab along arrow 901 b decreases the length of the exit 405 and moving the exit lip along arrow 902 a reduces the exit to the minimal size, as illustrated in FIG. 11( b ) . [0073] FIG. 12( a ) depicts, in exploded view, another example design of the material dispensing head with adjustable exit size. The material-containing cell 404 in this design includes 4 main parts: a main body 404 B 1 , a side-slab 404 B 3 , a cover 404 B 2 that covers the main cell space 404 B 10 and the side-slab, and an exit lip 404 B 4 that slides over the exit 405 . The side lab is basically restrained on 5 surfaces by the cover, the main body, two restraining structures 404 B 13 and 404 B 14 of the main body and the tip edge of the exit lip at 404 B 40 . Therefore, the side slab can slide linearly along arrow 903 . Restraining structures for the lip 404 B 4 can be of a similar design and is not shown. Similar to the design of FIG. 11 , the exit 405 is also opened and closed by the sliding motions of the slide slab 404 B 3 and the lip 404 B 4 . When the slide slab is pushed to the right along arrow 903 and the lip is pushed down along arrow 904 , the exit is closed down, as shown in FIG. 12( b ) . Near the exit 405 , the tip edges of the main body, the side slab and the lip are shaped into wedge-shapes, as depicted at 404 B 11 , 404 B 31 and 404 B 41 . This way, the exit opening 405 can always be kept at the lowest position of the assembly of the dispensing head. The possibility of mechanical interference or collision between parts of the dispensing head and the solidified workpiece can be minimized. [0074] The designs illustrated in FIG. 11 and FIG. 12 basically apply the principle of adjusting the area of the exit 405 from two different directions (specifically, perpendicular directions) by two independently adjusted gating members. This way allows the exit opening to be smoothly adjusted between a large maximal size and a very small minimal size. [0075] FIG. 27 depicts another example design of the material dispensing head with adjustable exit size. Compared to FIG. 11 , this design uses multiple side-slabs stacked together 404 F 3 , without an exit lip. By moving and positioning each side-slab ( 404 F 31 , 404 F 32 or 404 F 33 ) independently, the size of the exit 405 can be adjusted discretely in thickness direction but continuously in width direction. [0076] FIG. 28 depicts another example design of the material dispensing head. It uses a single side-slab 404 G 3 that has a recess feature 404 G 20 on its leading edge. When the slab is positioned to fully-closed position, this recess feature and the inside wall of the main body 404 A 1 form a nozzle structure with the cell space 404 G 10 at back and the orifice 405 G at the exit face, for dispensing materials in wire- and filament-shapes. [0077] The contacting surfaces between the main body and the side-slab (or the lip) need to have two functions: bearing function for sliding motion and sealing function for preventing liquid metal from leaking out. The bearing material can include graphite, ceramics such as aluminum oxide, silicon nitride, silicon carbide. Cast iron, brass, Nitralloy and Zerodur can also be used if the solidifiable material used is a non-ferrous metal. [0078] For non-wetting sliding surfaces, surface tension of the molten metal will basically prevent itself from seeping into the sliding interfaces. Further, the material feeding involves a pressure only slightly above normal atmospheric pressure. Therefore, leaking is generally not a major concern. 1.4 Differential Molding Means [0079] The material dispensing system can further include a differential molding means, which applies a small solid means (called differential mold) in contact with selected positions on dispensed material while it is solidifying, to restrict the flow of and to shape the solidifying material to obtain desired cross-sectional shape. By this means, good surface finish can be obtained. Curvature in the direction along the width of a ribbon-shaped dispensed material can also be made by this means. [0080] As depicted in FIG. 7 , by placing a small solid surface 420 underneath the solidification zone 452 , this solid surface together with the leading edge of the exit 405 a forms restrictions on both sides of the dispensed material so that the dispensed material solidifies into a band (ribbon) shape. The differential mold 420 can also be applied to the top side of the solidification zone to make the top surface of the dispensed material smooth. FIG. 8( a ) illustrates this situation. Part of the surface of the differential mold 420 touches previously solidified material at 451 , a small cavity 601 is formed by the remaining part of the differential mold surface together with restricting surfaces of previously dispensed and solidified materials at 451 and 514 . The dispensing head dispenses material to full this cavity. The newly dispensed material solidifies. Then the differential mold and the dispensing head move to the right to begin the next dispensing step. FIG. 8( b ) illustrates the situation when two differential molds are applied to opposite sides of dispensed material. Upper differential mold 420 a and lower differential mold 420 b together with previously solidified material 451 form a small cavity for receiving dispensed molten metal 452 . In principle, in order to have good bonding between newly dispensed material and previously solidified material, a small portion of the previously dispensed material needs to be re-melted and then re-solidified together with the newly dispensed material, as indicated by 452 R. By moving the upper and the lower differential molds together with the dispensing head, long, band-shaped solid can be formed. [0081] In general, the longitudinal direction of the differential mold is parallel to the solidification front of the melt and perpendicular to the track of the dispensing. Therefore, when a flat surface is used as the differential mold, a solid band (or ribbon) can be formed and the surface of the band in its transverse (width) direction is flat. This is illustrated in FIG. 14( a ) . Curved band 381 is formed by moving a differential mold from location 420 h , together with the operating dispensing head 403 , to location 420 i . The track of dispensing is indicated by the dashed curve 788 , which is generated by the multi-DOF motion mechanism. In the transverse (width) direction, indicated by dash lines 784 , the surface of the band is flat (straight line). Such bands can still be joined to approximate a 3D curved surface, as shown in FIG. 6( a ) . [0082] If the differential mold is made to be able to change its curvature along its length direction, then band-shaped geometry having curvature in its traverse (width) direction can be formed. As illustrated in FIG. 14( b ) , curved band 382 is formed by moving a differential mold from location 420 j , together with the operating dispensing head 403 , to location 420 k . The track of dispensing is indicated by the dashed curve 789 . In the transverse (width) direction, as illustrated, initially the differential mold is made to curve upward 420 J so the surface has a positive curvature (or bending upward) as indicated by dash lines 784 j . In the later stage of dispensing, the differential mold is made to curve downward 420 k so the surface has a negative curvature (or bending downward) as indicated by dash lines 784 k . As a result, combining this curvature capable differential mold with the multi-DOF motion mechanism, band-shaped geometry with curvatures in both directions (along the dispensing track as well as its transverse (width) direction) can be formed. 3D surfaces of almost arbitrary curvature can be formed by joining bands with variable curvature in both directions, as illustrated in FIG. 6( b ) . In FIGS. 14( a ) and ( b ) , the differential molds are depicted on top of the dispensed material stripes ( 381 , 382 ). They can also be under the dispensed material or on both the top and the underside of the dispensed material, depending on situations and needs, as described in previous paragraphs. [0083] It should be noted that the so called “minute size” of the differential mold is measured relative to the size of the object to be fabricated, rather than by an absolute standard. [0084] The differential mold that can change curvature along its longitudinal direction can be constructed by at least two approaches. The first approach applies a deformable member and an actuation means that changes the curvature of the member. FIG. 15 depicts one example by this method, which mainly comprises two bendable foils. These two deformable foils can be the two parts ( 420 A 1 a . 420 A 1 b ) of a single U-shaped foil 420 A 1 , as shown in FIG. 15( a ) . Two handles ( 420 A 2 , 420 A 3 ) are attached to the separate ends of the two foils and are connected at a pivot 420 A 4 . When a force opens the handles, as illustrated in FIG. 15( b ) at 1501 , both foils bends inward and become concave. When a force closes the handles, as illustrated in FIG. 15( c ) at 1502 , both foils bend outward and become convex. The curvature of the foil surfaces can be controlled by adjusting the extent of opening (or closing) of the handles. The open and close of the handles can be actuated by a suitable mechanism such as two co-axial worm gears of opposite spiral directions (not shown). This differential mold can be applied to the top surface of dispensed material by using the lower foil 420 A 1 b , or to the underside surface of the dispensed material by using the upper foil 420 A 1 a. [0085] The second approach uses a curved, non-deformable member and makes use of different portions on the member, each portion having different curvature, to make contact with dispensed material to meet the required curvature. FIG. 16 illustrates one example of this approach, which Includes a rotatable curved rod. The curved rod 420 B 1 is attached to a shaft 420 B 2 , which is rotatable about axis 1600 . For convenience of description, axis 1600 is oriented as parallel to the x-direction. The rod has a curved section that deviates away from axis 1600 toward one direction indicated by a marker 420 B 4 , with the largest deviation at 420 B 3 . When a dispensed material passes over the upper surface of the curved section of the rod in transverse direction, i.e. along y-direction, then depending on the orientation of the rod with respect to the rotational axis 1600 , the contacting surface between the rod and the underside of the material will have different curvatures. [0086] For example, in FIG. 16( a ) , the marker 420 B 4 points toward z-direction, indicating that the peak point of the curve 420 B 3 also points toward z-direction. Thus, the curved section of the rod acts as a differential mold of convex surface to the underside of the material and the curvature is equal to the curvature of the rod's curved section along x-direction. If the rod rotates so that the marker 420 B 4 points 90 degree away from z-direction, as shown in FIG. 16 ( b ) , then the peak of the curved section 420 B 3 points toward y-direction. That is, the curved rod now basically lies flat on a plane parallel to the x-y plane. Its top surface is basically also flat with respect to z-direction. As a result, the rod acts as a differential mold of flat surface to the underside of the material. If the rod rotates so that the marker 420 B 4 points 180 degree away from z-direction, as shown in FIG. 16 ( c ) , then the peak of the curved section 420 B 3 points toward −z direction. The rod acts as a differential mold with a concave surface to the underside of the material. Note that when the angle between the marker 420 B 4 and the +z direction is 0 or 180 degree, the rod has maximal curvature in the z-direction, convex or concave. [0087] FIG. 16( d ) depicts a general case when the rod rotates to an angle θ with respect to z-direction. To a dispensed material passing over the upper surface of the curved section of the rod in transverse direction, i.e. along y-direction, the curvature it experienced can be obtained from the projection of the rod curve 1602 onto the x-z plane 1605 , as shown as curve 1604 . The angle of rotation θ thus controls the curvature of the differential mold. The rotation can be actuated through a suitable mechanism such as a rack and pinion system (not shown). This differential mold can be applied to the top surface or to under-surface of the dispensed material. [0088] In order to control dimension of width of the dispensed material, the differential mold can include edge shaping features. FIGS. 17( a ), ( b ) and ( c ) illustrate a few examples of differential molds having a small perpendicular edge ( 4201 , 420 A 21 or 420 B 21 ) relative to the differential molding surface. This small vertical edge 4201 can restrict the material 452 in the width direction during solidification, when the main differential mold surface is on the top of or under the material. When forming thin structures of an object, such as the blades of FIG. 1 , the edges can be shaped and trimmed as a final step after the main portion of a blade is formed almost to the final dimension. The edges can then be formed with the help of an edge shaping mold that shapes only the edges but not the main surfaces of the blade. FIG. 17( d )-( e ) illustrates one such example of edge shaping differential mold. The end 420 C 1 has a step structure that can be applied to the underside of edge of a structure, while the opposite end 420 C 2 has a similar but upside down step structure, which can be applied to the topside of edge of a structure. By rotating the device about axis 1601 , the two opposite ends can be selected as needed. FIG. 17( f )-( g ) illustrates another example of edge shaping differential mold. This example has a short post 420 D 1 eccentrically attached to a shaft of larger diameter 420 D 2 . The joining area 420 D 21 forms edge shaping surfaces. Rotation of the shaft 420 D 2 can place the short post at bottom, as shown in FIG. 17( f ) , or at top, as shown in FIG. 17( g ) , or at any other angle relative to the center axis 1602 . [0089] In general, materials used for making the material cell 404 can also be used to make the differential mold, especially those made of non-deformable members. For examples, ceramics, carbon and their composites can be used to make the curved bars of FIGS. 16 and 17 . Ceramics can be used for metals of high melting points, such as steels, titanium, cobalt, chromium and nickel alloys. For differential molds based on deformable members, graphite sheets and metals can be used. Steels can be used for molten copper. Steels coated with Nitralloy can be sued for aluminum alloys. Aluminum can be used with tin. For handling molten steels, except graphite, metals of melting point higher than steel may also be used, such as refractory metal tungsten and molybdenum. These metals do form alloys with iron at elevated temperature. To avoid this, the metal surface can be coated with a thin layer of alumina by plasma spray technique, so that the alumina layer shields the metal base from direct contact with the molten steel. In metal coating industry, alumina coated refractory metal foils as thin as 0.01 mm have been used as “alumina coated boats” as evaporation sources. (For example, see products of Megatech of Cannock. Staffordshire, England, http://www.megatechlimited.co.uk/29-alumina-coated-boats). Such a thin foil can also provide the deformability required for curvature adjustment. [0090] The differential mold can also be based on the principle of fluid flow and pressure. The basic concept is to apply multiple channels of gas jets over the dispensed molten metal in the solidification zone and shape the surface of the molten metal by adjusting the flow speeds and pressures of different channels. An example system is depicted in perspective view in FIG. 18( a ) and in cross-sectional view (sectioned along the width direction of the dispensed material) in FIGS. 18( b ) and ( c ) . The system includes a bundle of small diameter tubing 420 E 1 . The exhaust end of the tubing bundle forms an array of gas outlets 420 E 2 , which is to be placed over the top of the dispensed molten materials in the solidification zone. The Inlets end of the tubing connects to a manifold 420 E 3 , which is supplied with an inert gas from inlet piping 420 E 4 . In the manifold, each tube in the bundle is connected to a different controllable flow restricting device. For examples, tube E 1 a is connected to restricting device E 3 a , and tube E 1 b to device E 3 b etc. The flow restricting device can be controlled through a mechanical or electro-mechanical mechanism, such as a piezo-electric actuator, so that the flow rate in the corresponding tube can be adjusted. When the array of gas outlets 420 E 2 is placed slightly off the top surface of the dispensed molten materials 452 in the solidification zone, the gas flow pushes the metal surface and forms a small gap. A higher flow rate in a tube will result in a higher pressure, and a larger gap, between the corresponding tube outlet and the molten metal surface and a larger gap. A lower flow rate will have a reverse effect. By adjusting different flow restricting devices, different flow rates in different tubes can be generated and different pressures can be provided over different parts of the molten metal surface, thereby shaping its cross-sectional profile. For example, in FIG. 18( b ) , flow rates in the central tubes, such as E 1 c , are higher than those in side tubes, E 1 a and E 1 e , resulting in higher pressure in the middle of the molten metal E 2 c . Thus, the metal surface is pushed down, forming a concave shape. FIG. 18( c ) illustrates an example of reversed situation, wherein a convex profile is formed by supplying higher flow rate in side tubes, D 2 a and D 2 e , than in central tubes. Argon, CO 2 or other inert gas can be used. One advantage of this gas flow system is that the molten metal does not touch the solid part of the differential mold. Therefore, the tubing can be made from various kinds of metals. [0091] When the size of dispensed molten metal is small, the effect of surface tension could surpass the effect of gravity and could cause problem in material dispensing and in the performance of the differential molds. In this case, the solutions include applying a pressure at the upstream of the molten metal (by a gas pressure or by a piston effect such as the one shown in FIG. 12 ) to “squeeze” the molten metal out and using upper and lower and even edge shaping differential molds simultaneously to confine the molten metal as it solidifies. [0092] FIG. 19 depicts an example design of the mounting and retracting mechanism of the differential molds system, with respect to the dispensing head 403 , which moves toward +x direction (right) when it dispenses materials. The upper differential mold 420 a and the lower differential mold 420 b are connected to two arms ( 422 a , 422 b ) respectively. Arm 422 a is mounted to a base 424 at axis 4291 . Arm 422 a can rotate about axis 4291 and move the upper differential mold to operation position at 420 a or to resting position at 420 ar . Similarly, arm 422 b can rotate about axis 4292 and move the lower differential mold to operation position at 420 b or to resting position at 420 br . Thus, the differential molds can be engaged or disengaged according to need. As described previously, the differential molds move together with the dispensing head relative to the dispensed material. In the case when the dispensing head needs to rotate about z-direction, the orientation of the differential molds can be adjusted accordingly by rotating the base 424 about z-direction, for example, along a track 4295 (rotary mechanism not shown). [0093] The ambient condition control unit includes means for controlling the temperature of the atmosphere surrounding the material dispensing area, such as using an air conditioner or a fan, if necessary. It can also include means for controlling the temperature of the base or members onto which the dispensed material attaches. Such examples include passing cooling or heated fluids through internal passages in the base to control its temperature. Electric heat or heated air or inert gas can also be used over the material dispensing area or over the whole workpiece and its base. Whenever needed, the temperature of the differential molds can also be controlled by similar means. These means for controlling temperatures of the ambient, the base and the differential molds apply to different solidifiable materials, not limited to molten metal. Example 2 Plastics (Polymer Material) as Solidifiable Material, 3D Freeform by an Extrusion-Based Means 2.1 the Material Dispensing System [0094] The material dispensing system is similar to the system of FIG. 8 . Metals, such as aluminum, copper or steel, can be used for the material supply unit 402 and the dispensing head 403 . The heating means can heat up the metal and then the metal can heat up the plastic material. Inert gas protection is generally not needed. 2.2 Means for Changing the Width of Dispensed Materials [0095] The means of changing the width of dispensed materials by using a dispensing head of adjustable exit size and the corresponding basic mechanisms, as depicted in FIGS. 11 and 12 , also apply to plastic materials. However, due to differences in properties between plastics and metals, the internal shapes of the material supplying unit and the dispensing head are different. [0096] In the case of metals, for example in FIG. 12( a ) , the flow speed of the molten metal 480 along the supply duct 402 B 1 in the material supply unit 402 B could decelerate at entering the material cell 404 B 10 , which has a cross-sectional area larger than that of the supply duct. But as long as the flow volume rate is kept constant along the flow path, the material cell can still be kept fully flooded and material dispensing rate can be maintained. That is, a single solid wire 470 acting as a piston to its melt in a supply duct of fixed cross-sectional area can provide various volume flow rates, by varying feed rate, to satisfy the need of dispensing of materials of different sizes (widths). [0097] However, in the case of extrusion of polymers, melt must be accelerated steadily and there should be no dead spots (stagnation zones) along the flow path, according to know-how from traditional bulk extrusion processes (see W. Michaeli. Extrusion Dies for Plastics and Rubber, 2nd ed., Hanser, Munich, 1992, p. 190, which is incorporated herein for this current invention by reference). Therefore, shapes of internal duct, cell space and gating members as well as gating mechanism should be designed to have (1) continuous lines without steps or jumps and (2) always decreasing cross-sectional areas along the flow path, even between parts having relative movements. Two example designs are described below. [0098] FIG. 20 depicts a first preferred system of the material supply unit and the dispensing head for polymer dispensing by extrusion. FIG. 20( a ) shows cross-sectional views and FIG. 20( b ) shows an exploded view. A wire of solid material 470 is fed into the material supply unit 402 D via a duct 402 D 1 and is heated to become melt 480 . The dispensing head includes a main body 404 D 1 , a cover part 404 D 2 and a side-slab 404 D 3 for adjusting the size of the exit 405 . The melt flows through the cell space (melt chamber) 404 D 10 and exits at exit 405 . The cell space is confined at left by the side-slab, which can rotate about an axis 2004 ( 2004 a ) to open up (e.g. position 404 D 3 a ) or close down (e.g. position 404 D 3 c ) the exit. The side-slab includes a shaft structure 404 D 31 that sliding fits into a bore 404 D 11 on the main body to allow such rotation. The cover part 404 D 2 has a raised structure 404 D 21 that, when the system is assembled, forms the space for the cell space and the space for motion of the side-slab. The leading edge of the raised structure at 2005 touches the top edge of the side-slab at 2006 , forming a contacting line and a mechanical seal so that the melt will be confined in the cell space and will not flow to the back of the side-slab. This contacting line 2004 is made to locate right on the rotation axis 2004 a of the side-slab mechanism, so that rotation of the side-slab does not change its location nor affect the sealing. This way, the flow lines of the melt are always continuous without steps or jumps regardless of angle of the side-slab. Further, the cross-section of the cell space is made to be always decreasing by decreasing cell gap sizes along the flow path, as illustrated in sectional views of A-A ( 2001 ), B-B ( 2002 ) and C-C ( 2003 ). The thickness of the side slab, which moves inside the gap, also varies along the flow direction accordingly. [0099] FIG. 21 depicts another preferred system of the material supply unit and the dispensing head for polymer dispensing by extrusion, which can dispense large amount of material whenever needed. FIG. 21( a ) shows an exploded view of the material supply unit 402 C (showing a cross-section without showing its opposing halt) and the dispensing head 404 C. FIG. 21( b ) illustrates the system assembled together. The dispensing head includes 2 parts, 404 C 1 and 404 C 2 . Part 404 C 2 can slide relative to 404 C 1 to open and close the exit 405 . Part 404 C 2 includes a curved feature 404 C 21 as one internal surface of the material cell 404 C 10 , so that the cell has a shrinking cross-section along the flow path. In the material supply unit, the material duct 402 C 1 can take multiple solid wires ( 470 a - d ) aligned in an array, as shown in FIG. 21( b ) . When part 404 C 2 opens to maximal position, the top of the curved feature 404 C 22 aligns to the edge of the lower end of the material duct 402 C 11 , such that the curvature is generally continuous. In addition, the curves at 404 C 22 and at 402 C 1 are made to approach the top surface of the dispensing head at 404 C 23 in a near asymptotic fashion so that when part 404 C 2 closes to a smaller exit size, as shown in FIG. 20( b ) , the flow direction of the melt does not change abruptly. As a result, the system has a combined internal shape of always decreasing cross-sectional area along the flow path and the dispensing head can still change its exit size. [0100] Solid wires ( 470 a - d ) can be fed into the material supply unit by using a set of rollers or gears ( 510 a - d , 511 a ). These rollers can be controlled independently so that material feed rate can be controlled to match dispensing volume rate. When the exit is opened to the maximal size, all solid wires can be fed at the same time to supply the required large volume flow rate. When the exit is closed down to the smallest size, only one solid wire needs to be fed to supply the minimal dispensing rate. [0101] By using adjustable exit described above, this invention can change material deposition rate and width as required by local geometry. The design of stacked multiple gating members of FIG. 27 and design of the recess feature and nozzle structure of FIG. 28 can also be applied. When the exit is closed down to minimal size, the system becomes basically similar to the FDM technique. In addition, the methods of changing the width of dispensed materials by adjusting the orientation of the dispensing head as depicted in FIGS. 9 and 10 apply to plastics as well. The design and operation of the differential molds, as depicted in FIGS. 14-19 , also apply to plastic materials. [0102] One issue in forming and shaping of polymer material is the so called die swell effect, which involves non-linear scale change when the mechanical boundary conditions around a polymer melt change. When the melt leaves the exit of the dispensing head, the material will expand and will not maintain the cross-sectional shape of the exit. To correct such dimensional change, the exit shape can be designed in anticipation of the die swell effect by referring to experiences and data form traditional polymer extrusion process, for example in the reference book by W. Michaeli, Extrusion Dies for Plastics and Rubber , New York: Oxford University Press, or by using polymer processing simulation software. Example 3 Molten Metal as Solidifiable Material, 3D Freeform by a Casting-Based Means, with Auxiliary on-Spot Heating [0103] If the temperature of the base material, which the solidifiable material to be dispensed onto, is too low or its heat sink is too large, the molten metal from the dispensing head may not be able to heat up the previously solidified material within a short time. In this case, the newly dispensed metal could solidify prematurely without good bonding to the base material. To resolve this issue, an auxiliary heating can be applied on spot, i.e. at the targeted dispensing location, to locally preheat the base material. The auxiliary heating source should be able to deliver concentrated heat in a relatively short time. Such a heating source can be constructed based on the principle of a few industrial fusion welding systems, such as gas tungsten-arc welding, plasma-arc welding, or laser welding. FIG. 22 depicts an example system of this invention with an auxiliary arc-based heating unit. 801 indicates an auxiliary heating unit based on the principle of plasma-arc welding torch. 802 is a tungsten electrode connected as negative electrode. Plasma gas 899 flows through an inner passage 804 , whereas shielding gas flows through an outside passage 803 . The housing of the dispensing head 403 is connected as positive electrode. As a result, the arc forms mainly in the space 810 between the tungsten electrode and the front end of the dispensing head housing 403 . However, high temperature plasma gas can still jet down to reach the target area 514 a , rather similar to the case of non-transferred plasma welding scenario. Because plasma arc could generate very high temperature at the core of the plasma gas, a high temperature material, such as graphite, should be used at the outside of the dispensing head housing as the positive electrode. Proper regulation and control small current pulses can generate just enough concentrate heat to heat up the target area. This arrangement allows the arc heating unit to be placed at a distance away from the workpiece (target area) with enough space for the dispensing head tip and the differential mold 420 a. Example 4 Plastics (Polymer Material) as Solidifiable Material, 3D Freeform by an Injection-Based Means [0104] Polymers in fluid state can be dispensed by methods other than extrusion. For example, the principle of a plastic injection molding machine, more specifically the injection-molding screw mechanism, can be applied to convert solid polymer pellets into melt. Such a mechanism is described in, for example, E. Lokensgard, Industrial Plastics: Theory and Applications, 5th ed., Delmar, Clifton Park, N.Y. 2010, p. 155-159, which is herein incorporated into this invention by reference. Example 5 Molten Metal as Solidifiable Material, 3D Freeform by an Injection-Based Means [0105] Molten metals, especially those of lower melting points, can also be dispensed by injection, in analogy to metal injections applied in die casting. Another method to dispense molten metal is to shoot metal droplets. M. Orme and R. F. Smith, “Enhanced Aluminum Properties by Means of Precise Droplet Deposition”, Journal of Manufacturing Science and Engineering , August 2000, vol. 122, p. 484-493 describes such a system for shooting aluminum droplets in details, which is incorporated to this current invention by reference. Example 6 Making a 3D Article [0106] FIG. 23 illustrates the process of making a 3D article, using the 3D part shown in FIG. 1 as an example. For simplicity and clarity, it is assumed that the base 501 a and the part do not move, whereas the material dispensing system 401 moves. From FIG. 23( a ) to FIG. 23( c ) , the material dispensing system dispenses materials on the base to make the interior of the hub. From FIG. 23( d ) to FIG. 23( e ) , the external surface of the hub is made. In FIG. 23( f ) , the roots 603 of the blades are made. This step is similar to the process of FIG. 10 . The roots serve as starting structure for blade making in the next step. In FIG. 23( g ) , blades are made. Material dispensing starts from the roots 603 and moves away from the hub. Depending on material and thickness, dispensed suspending component geometries could have enough stiffness to maintain their shapes without the need of external supports. Whenever external supports are needed, they can be pre-fabricated by the same process before the suspending portions of the part are made. For example, 610 indicates an external support frame attached to the base 501 a and the fixture frame 430 on the base, together with short support posts 605 connected to it. When the edge portion 601 of the blade is formed, material is dispensed to pass by and join with the short posts, so as to be supported. When the internal bands are formed, such as 602 , they can use adjacent previously dispensed and solidified portion as support. External supports can also be formed under the suspending structure, as what is usually done in the existing FDM process. Example 7 Making Mold Inserts, Especially Seamless Mold Inserts with Conformal Cooling Passages [0107] By applying the material dispensing process of this invention, a new method of making 3D article, especially metal molds, featuring combined additive and subtractive processes can be devised. The so called subtractive process is producing shapes by removing materials from a stock. The so called additive process is adding materials by this current flexible 3D freeform method. This new method is especially suitable for making seamless mold inserts with conformal cooling passages. This method can be called “flexible mold surface forming technique”. [0108] FIG. 24 illustrates the first example of making a mold insert by the flexible mold surface forming technique. A mold core 2401 is first produced by machining, as shown in cross-sectional view in FIG. 24( a ) . Its surface profile 2402 is close to but slightly smaller than the final mold profile. A system of connected ditches (recess structure) 2403 is then made into the surface by machining. A set of holes ( 2404 a - d ) are then drilled to connect to two ends of the ditch system. 2410 illustrates a portion of the mold core surface 2402 and the ditch 2403 in enlarged perspective view. In the next step, as illustrated in FIG. 24( b ) , the material dispensing process of this invention is applied to cover the mold core surface with a layer of material. 2411 shows a local scenario where the dispensed and solidified material ( 2408 , dashed lines) covers the original mold core surface 2402 as well as the ditch 2403 . The dispensed material 2408 becomes the new mold surface, covering all ditches. Therefore, the ditch system now becomes internal, conformal passages for cooling fluid. In the completed mold core, cooling fluid enters the core from inlet 2405 and flows into the covered ditch system through holes 2404 a - b . The cooling fluid then flows in the covered ditch system 2403 and circulates through the core right underneath the mold surface and then, through holes 2404 c - d , out of the outlet at 2406 . [0109] FIG. 25 illustrates the second example of making a mold insert by the flexible mold surface forming technique. The mold core 2401 is shown in cross-sectional view. 2413 depicts part of the mold core surface and the surface cooling duct (ditch) in enlarged perspective view. In comparison with FIG. 24 , the surface of the mold core 2402 is machined to a dimension very close to the final mold surface, leaving only allowance for final surface polishing. The spiral ditch structure around the core surface includes an additional recessed step feature 2403 a along both banks of the ditch 2403 . In the step of material dispensing, the solidifiable material is dispensed over the recess feature 2403 a to cover up the spiral ditch but not the core surface 2402 . In this way, much less material is needed and faster processing can be achieved. When the ditch is wide, in order to prevent dispensed material from falling into the ditch, especially in the case when materials in particulate form are dispensed, a lower differential mold 420 b can be applied under the dispensing head 403 and positioned between the two banks of the ditch at the level of the recessed step. The differential mold can thus block the opening of the ditch under the dispensing head so that the dispensed material flows to the recessed step but not into the ditch. This is illustrated in FIG. 25 ( b ) . The lower differential mold 420 b can be a separate device 420 or can be a part of the dispensing head, as depicted in FIG. 25 ( b ) . This method can also be applied to the case of FIG. 24 . Example 8 Making Seamless Mold Cavity [0110] This invention can also be applied to make seamless mold cavity. FIG. 26( a ) depicts a cross-sectional view of a mold insert 2601 with the mold cavity 2602 and cooling passages 2603 . Such geometry usually requires a slow process of die sinking using electric discharge machining (EDM) to make. FIG. 26( b ) illustrates a cross-sectional view of such a geometry made by using the current invention. The process starts with a starting block 2610 , which can be made by machining. Then a shell of the inner surface 2611 is made by using the current invention. FIG. 26( c )-( e ) depicts the process of making the inner shell 2611 . After the inner shell is made, additional layers of materials 2612 are added to the exterior as reinforcement. Internal cooling passages 2403 a can also be formed by leaving grooves and then covering them during the buildup of the layers of materials 2612 . [0111] Various fillers for tool steels can be used as the solidifiable materials for making mold inserts and information can found from publications such as Tool Steel Filler Metal Characteristics TIC Welding from http://www.stood.ind.com/Catalogs/FISC/05catpg394.pdf, and Welding - Tool - Steel:Difficult but Rewarding Task. Solutions with Effective, Practical Advice from http://www.welding-advisers.com/Welding-Tool-Steel.html, both documents are incorporated herein for this current invention by reference. [0112] In general, a mold is a tool. Other tools, such as cutting tools or cutting tool holders, with complex Internal cooling passages can also be made by the similar methods described in examples 7 and 8.

This invention relates to processes and systems of rapid prototyping and production. Its features includes flexible material deposition along tangential directions of surfaces of a part to be made, thereby eliminating stair-shape surface due to uniform horizontal layer deposition, increasing width of material deposition to increase build up rate, applying the principles of traditional forming/joining processes, such as casting, fusion welding, plastic extrusion and injection molding in the fabrication process so that various industrial materials can be processed, applying comparatively low cost heating sources, such as induction heating and arc-heating. Additional features include varying width and size of material deposition in accordance with geometry to be formed and applying a differential molding means for improved shape formation and surface finishing.

RELATED APPLICATIONS [0001] This application is a Continuation-in-part of co-pending U.S. application Ser. No. 12/897,564, filed on Oct. 4, 2010 claiming priority from U.S. Provisional Application No. 61/329,121, filed on Apr. 29, 2010 both which is incorporated herein by reference in their entirety. FIELD OF THE INVENTION [0002] The present invention relates generally to the field of keys, and more particularly, to keys with mutually compressible actuating elements. BACKGROUND OF THE INVENTION [0003] Embodiments of the present invention generally relate to entry security, and particularly to key assemblies and lock assemblies having elements capable of biasing locking pins and mechanical and design characteristics that substantially increase the number of key/lock combinations, thereby inhibiting the unauthorized replication of the key assembly. [0004] Locks are often intended to provide the security of permitting only authorized ingress and/or egress for a given entry. The existence of a locked entry and/or the inability to unlock a locked entry may indicate that unauthorized passage through the entry is prohibited and/or to deter such unauthorized passage. Locking such entries may therefore control when, who, and/or what passes through the entry. [0005] Various attempts may be made to gain unauthorized passage through a locked entry. For example, an individual lacking authorization may attempt to gain entry by breaking the door and/or breaking the lock. However, these actions suffer from many drawbacks, including, for example, the noise associated with breaking the door and/or lock, the resulting visual or audible indication that unauthorized ingress/egress may being occurring or has occurred, the potential need for tools to carry out the act of breaking the door and/or lock, and the time and energy associated with such a break. [0006] Another option for unauthorized entry that may not involve some of the challenges associated with physically breaking the lock or door is duplicating the key that unlocks the lock, or use other devices in an attempt to manipulate, or pick, the lock so as to unlock the lock. Duplicating keys for many types of locks merely requires duplicating the general physical shape of the blade of the key, recreating the profile of key bits and the shape and depth of holes or cavities in the key. Such unauthorized duplication may be achieved by filing, cutting, and/or machining a blank of material, such as a key blank or other blank that is or can be machined or manipulated to suitably match the shape and configuration of the key. [0007] Locks to an entry must, in addition to allowing authorized individuals to enter, have specific key profiles that prevent unauthorized key duplication, either by an unauthorized entrant or an unauthorized professional assembling the duplicate key. Additionally, a variety of top-secret institutions require keys with more combinations that are difficult to duplicate in order to avoid unauthorized entry. [0008] Present day flat blade keys often have depressions of different depths in the key blade or, in the cases of high-security entry, have holes that are of different shapes. Additionally, there are keys having a variety of shapes, such as round cross-sectioned keys; and keys having outward projecting bits; all for the purpose of preventing unauthorized entry and/or unauthorized key duplication. [0009] Thus, a need exists for key assemblies configured to prevent or deter successful unauthorized duplication of the key assembly. Further, a need exists to provide a key assembly that has mechanical properties and design requirements that increase the possible key/lock combinations that would inhibit unauthorized successful duplication of the key assembly, and thereby provide increased security against unauthorized ingress or egress through an entry. BRIEF SUMMARY OF THE INVENTION [0010] According to an aspect of the invention, a key assembly is provided that comprises a key blade, the key blade having a first surface and a second surface, the key blade configured to be inserted into a mating lock; an aperture in the key blade, the aperture having an axis; a cap having an outer surface, captured in the aperture for continuous axial travel between a first limit extending out of the first surface and a second limit recessed within the aperture; and a base having an outer surface, captured in the aperture for continuous axial travel between a first limit extending out of the second surface and a second limit recessed within the aperture; wherein the base is biased away from the cap. [0011] According to another aspect of the invention, a key assembly is provided wherein the key is positioned in a lock assembly, the key assembly, comprising: a key blade, the key blade having a first surface and a second surface, the key blade configured to be inserted into the lock; an aperture in the key blade, the aperture having an axis; a cap having an outer surface, captured in the aperture for continuous axial travel between a first limit extending out of the first surface and a second limit recessed within the aperture; and a base having an outer surface captured in the aperture for continuous axial travel between a first limit extending out of the second surface and a second limit recessed within the aperture; wherein the base is biased away from the cap; the lock assembly having a barrel, a column extending from the barrel, and a cylinder configured to rotate within the barrel, the cylinder including a guide way; the column having an aperture configured to receive the sliding movement of a first pin housing, the first pin housing configured to receive the sliding movement of a first pin; the cylinder including a cylinder aperture configured to receive the sliding movement of a second pin housing, the second pin housing configured to receive the sliding movement of a second pin, the first pin being inwardly biased against the second pin so as to place the first pin in the cylinder aperture when the key assembly is not positioned in the lock assembly; the key assembly configured to outwardly bias and move the cap or the base against the first pin when the key assembly is positioned in the lock assembly so that the second pin and the second pin housing are located inside the cylinder and the first pin and first pin housing are located outside of the cylinder. [0012] Additionally, according to another aspect the invention provides, in combination, a key assembly comprising: a key blade, the key blade having a first surface and a second surface, the key blade configured to be inserted into a mating lock; an aperture in the key blade, the aperture having an axis; a cap having an outer surface, captured in the aperture for continuous axial travel between a first limit extending out of the first surface and a second limit recessed within the aperture; and a base having an outer surface captured in the aperture for continuous axial travel between a first limit extending out of the second surface and a second limit recessed within the aperture; wherein the base is biased away from the cap; and a mating lock assembly, the lock assembly having a barrel, a column extending from the barrel, and a cylinder configured to rotate within the barrel, the cylinder including a guide way; the column having an aperture configured to receive the sliding movement of a first pin housing, the first pin housing configured to receive the sliding movement of a first pin; the cylinder including a cylinder aperture configured to receive the sliding movement of a second pin housing, the second pin housing configured to receive the sliding movement of a second pin, the first pin being inwardly biased against the second pin so as to place the first pin in the cylinder aperture when the key assembly is not positioned in the lock assembly; the key configured to outwardly bias and move the cap or the base against the first pin when the key assembly is positioned in the lock assembly so that the second pin and the second pin housing are located inside the cylinder and the first pin and first pin housing are located outside of the cylinder. BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS [0013] The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which: [0014] FIG. 1 illustrates an exploded view of a key assembly according to an embodiment of the present invention; [0015] FIG. 2 illustrates a perspective view of a key assembly and a lock assembly according to an embodiment of the present invention; [0016] FIG. 3 a illustrates a cross sectional view of the actuation element shown in FIG. 1 according to an embodiment of the present invention; and FIG. 3 b illustrates another embodiment containing a ball. [0017] FIG. 4 illustrates a cross sectional perspective view of a key assembly engaging a lock assembly according to an embodiment of the present invention; [0018] FIG. 5 illustrates a cross sectional view of a lock assembly prior ( 5 a ) to the insertion of a mating key assembly into a lock assembly containing a depression in the key way; FIG. 5 b shows the insertion of the key; and FIG. 5 c shows the key blade lifting a pin in the lock assembly according to an embodiment of the invention; [0019] FIG. 6 a illustrate a cross sectional view of a key assembly having multiple actuation elements positioned in a lock assembly according to an embodiment of the present invention. 6 b illustrates an enlarge view of an actuation element in FIG. 6 a engaging a second pin according to an embodiment of the present invention. 6 c illustrates a partial cross sectional view of key assembly having a contoured cap posited in a lock assembly that includes a second pin having a mating contoured tip according to an embodiment of the present invention; [0020] FIG. 7 illustrates a cross sectional view of a section of the lock assembly in which the key assembly has been inserted into the lock assembly according to an embodiment of the present invention; [0021] FIG. 8 illustrates a cross sectional view of a section of the lock assembly having a lower pin assembly in which the key assembly has been inserted into the lock assembly according to an embodiment of the present invention; [0022] FIG. 9 a illustrates a cross sectional view of a section of the lock assembly having a lower pin assembly in which the key assembly has been inserted into the lock assembly according to an embodiment of the present invention. 9 b illustrates a cross sectional view of a section of the key assembly having an actuator pin extending from the cap of the actuation element according to an embodiment of the present invention; [0023] FIG. 10 illustrates a cross sectional view of a key assembly and a lock assembly in which the actuation elements include a protruding ball according to an embodiment of the present invention; [0024] FIG. 11 illustrates a cross sectional view of a key assembly and lock assembly in which the protruding balls extend from the base of the actuation elements and the lock assembly includes a lock actuation assembly according to an embodiment of the present invention: [0025] FIG. 12 is an exploded view of an embodiment of the key blade where the biasing elements are magnets and mechanical; [0026] FIG. 13 is an illustration of an embodiment of the key and lock combination having both magnetic and mechanical biasing and locking elements and pins including a magnetic locking safety pin coaxial and diametrically opposed to a magnetic locking pin slidably movable in the lock's column; and [0027] FIG. 14 is a magnified view of an embodiment of the key and lock combination in FIG. 13 , illustrating the magnetic biasing elements in the embedded floating elements of the key blade, forcing the locking pin of the column and the locking safety pin of the barrel to their respective positions. [0028] The foregoing summary, as well as the following detailed description of the preferred embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the preferred embodiments of the present invention, the drawings depict embodiments that are presently preferred. It should be understood, however, that the present invention is not limited to the arrangements and instrumentality shown in the attached drawings. DETAILED DESCRIPTION OF THE INVENTION [0029] FIG. 1 illustrates an exploded view of a key blade ( 112 ), the key blade ( 112 ) having a first surface ( 106 ) and a second surface ( 108 ), the key blade configured to be inserted into a mating lock; an aperture ( 109 ) in the key blade ( 112 ), the aperture having an axis; a cap ( 120 ) having an outer surface ( 123 , FIG. 3 ), captured in the aperture ( 109 ) for continuous axial travel between a first limit extending out of the first surface ( 106 ) and a second limit recessed within the aperture ( 109 ); and a base ( 124 ) having an outer surface ( 131 ), captured in the aperture ( 109 ) for continuous axial travel between a first limit extending out of the second surface ( 108 ) and a second limit recessed within the aperture ( 109 ); wherein the base ( 124 ) is biased away from the cap ( 120 ). The key blade 112 may have various different general shapes and sizes, such as, for example, having a generally rectangular, cylindrical, square, triangular, or trapezoidal cross-section, among others. [0030] The blade 112 may also include recesses and protrusions forming one or more outwardly projecting key bit 116 . The key bit 116 may be located at various locations along the blade 112 , including for example along the sides 110 , first or second surfaces 106 , 108 , or in one or more key guide ways 118 in the blade 112 . The key blank 102 may be constructed from a variety of different resilient materials, such as, for example, metallic materials, including, but not limited to, metal, brass, bronze, stainless steel, or a combination thereof. [0031] FIG. 2 illustrates a perspective view of a key assembly 100 and a lock assembly 200 according to an embodiment of the present invention. The lock assembly 200 includes a column 202 and a barrel 204 . The barrel 204 includes a drum 206 that houses and permits the rotational movement of a cylinder 208 . The cylinder 208 includes a lock guide way 210 that is configured to receive the insertion and position mating key blade 112 of the key assembly 100 . For example, the shape of the lock guide way 210 may be similar to that of the cross-sectional shape of the blade 112 and may include recesses, grooves, or other characteristics that generally complement and mate with those of the key blade 112 . [0032] FIG. 3 illustrates a cross sectional view of an actuation element 104 according to an embodiment of the invention shown in FIG. 1 . The actuation element may include a cap 120 having an outer surface, a base 124 having an outer surface, wherein the cap 120 is biased away from the base 124 with the aid of a biasing means 122 such as a spring in one embodiment, or an elastic material, in another embodiment, or an identical-pole facing magnets, foam rubber, elastic cones or other similar mechanisms for biasing the cap 120 from the base 124 . According to one embodiment, the biasing means 122 may be a spring. However, different embodiments of the present invention allow for the use of different actuators, such as, for example, magnets and air pressure, or a combination thereof. The spring actuator 122 shown in FIG. 3 may provide a biasing force that may allow for the continuous altering in the linear distance between an upper portion of the cap 120 and the base 124 , regardless of whether the cap 120 or the base 124 is anchored by the aperture 109 in one embodiment, or the lock guide way 210 in another embodiment. For example, when the biasing means 122 is a spring, when the spring is extended, the distance between the upper surface portion of the cap 120 and the base 124 is greater than if the spring was compressed. [0033] According to the embodiment illustrated in FIG. 3 , the cap 120 and base 124 may be configured to provide a sliding engagement that allows for the continuous relative movement of the cap 120 and/or base 124 relative to each other. For example, the cap 120 may include at least one lower protrusion 121 that extends downwardly from an upper portion 123 of the cap 120 . At least a portion of the lower protrusion 121 may be configured to be received in a bore 125 of the base 124 . The lower protrusion 121 may include outwardly extending tabs 127 that mate with inwardly extending lips 129 of the base 124 that, in one embodiment retain the cap 120 and base 124 in a sliding engagement. Moreover, upper portion of the cap 123 , the lower protrusion 121 and the inwardly extending base lips 129 define a channel capable of being captured by the aperture 109 positioned in key blade's 112 . Further, this engagement assists in another aspect, in retaining the biasing means 122 within the actuation element 104 , as shown in FIG. 3 a . Therefore, in one embodiment, when the actuation element 104 attempts to extend the distance between an upper portion of the cap 120 and the base 124 , the inwardly extending lips of the base 124 and the outwardly extending tabs of the cap 120 provide interference that prevents the cap 120 from separating from the base 124 . The position of the tabs 127 and/or lips 129 may thus limit the distance the cap 120 may be biased away from the base 124 , the base 124 may be continuously biased away from the cap 120 and/or the cap 120 and the base 124 may be biased away from each other. Further, the tabs 127 and lip 129 may limit the distance the cap 120 and/or base 124 may extend from the first or second surface 106 , 108 . In one embodiment, a shelf 111 extending radially inside the aperture 109 engages the channel created by upper portion of the cap 123 , the lower protrusion 121 and the inwardly extending base lips 129 , thereby limiting the continuous axial motion of the element 104 , between predetermined limits above surface 106 and below surface 108 . In one embodiment, element 104 may freely and continuously move from a position wherein the cap 120 extends about 1 mm above surface 106 , to a position in which the base 124 extends about 1 mm below surface 108 . In one embodiment, the element 104 , is referred to as floating, or a floating element, between the upper and lower limits, capable of being continuously positioned anywhere along the aperture 109 axis with the cap 120 and the base 124 capable of being biased away from each other in a continuous manner, regardless of whether the cap 120 , or the base 124 are anchored. In one embodiment, the terms actuation element and floating element are interchangeable. [0034] Additionally, the cap 120 and/or base 124 may be sized or configured to limit how close the upper portion of the cap 120 can come to the outer lower surface 131 of the base 124 . For example, according to the embodiment shown in FIG. 3 a , the outer portion 123 of the cap 120 may be sized to allow for an interference with at least a portion of the base 124 at the lips 129 so as to limit the distance the cap 120 may travel when a compression force is applied to the actuator element 104 . These limitations in the distance the cap 120 may extend inwardly or outwardly from the base 124 according to certain embodiments of the present invention may provide an additional security against successful, unauthorized duplication of the key assembly 100 . [0035] As shown in FIG. 1 , the floating element 104 may be positioned along the blade 112 of the key blank 102 . According to one embodiment, element 104 may be captured in an aperture 109 defined by an opening in the key blank 102 thereby defining an internal surface having a shelf thereon 111 . The shelf 111 may be located anywhere along the axial dimension of the aperture 109 and may be used to capture the cap 120 , the base 124 or the channel created by upper portion of the cap 123 , the lower protrusion 121 and the inwardly extending base lips 129 , of floating element 104 . The aperture 109 may be a continuous aperture or may include one or more counter bores. [0036] The precise location of each floating element 104 and the number of floating elements 104 on the blade 112 may vary. Additionally, the blade 112 may include one or more floating elements 104 that may have the caps 120 positioned above or recessed in the first surface 106 , or the base 124 below or recessed in the second surface 108 , or a combination thereof. According to an embodiment illustrated in FIG. 1 , the cap 120 may be positioned along the first surface 106 . The base 124 may be positioned at, below or recessed to the second surface 108 . According to other embodiments, both the cap 120 and the base 124 are configured to be able to be biased away from each other and/or the adjacent surface of the blade 112 . [0037] Accordingly and in one embodiment, provided herein is key assembly 100 having a key blade 112 , the key blade 112 having a first surface 106 and a second surface 108 , the key blade 112 configured to be inserted into a mating lock 200 ; an aperture 109 in the key blade 112 , the aperture having an axis; a cap 120 having an outer surface 123 , captured in the aperture 109 for continuous axial travel between a first limit extending out of the first surface 106 and a second limit recessed within the aperture 109 ; and a base 124 having an outer surface 131 , captured in the aperture 109 for continuous axial travel between a first limit extending out of the second surface 108 and a second limit recessed within the aperture 109 ; wherein the base 124 is biased away from the cap 120 . [0038] FIG. 4 illustrates a cross sectional perspective view of a key assembly 100 engaging a lock assembly 200 according to an embodiment of the present invention. The column 202 may include at least one bore 222 that is configured for the sliding movement of a first pin housing 224 . An outer end of bore 222 may be closed, such as, for example, through the use of a plug 228 . An outer actuator 230 , such as a spring, may inwardly bias the first pin housing 224 , such as, for example, biasing the first pin housing 224 toward the cylinder 208 . [0039] A first pin 226 may be positioned for a sliding engagement within the first pin housing 224 . According to on embodiment, the first pin 226 may be inwardly biased from the pin housing 224 by an inner pin actuator 232 . According to an embodiment, the inner pin actuator 228 may be a spring. However, other actuators 232 may be used to bias the first pin 226 , including, for example, a magnet, an electromagnet, air pressure and the like in other embodiments. According to the embodiment illustrated in FIG. 4 , a distal end of the first pin 226 may engage the inner pin actuator 232 . [0040] As shown in FIG. 4 , the cylinder 208 includes at least one cylinder aperture 240 configured for the sliding movement of a second pin housing 242 . The second pin housing 242 may be configured to receive and allow the sliding movement of a second pin 244 . The second pin 244 includes a second pin upper surface 243 and a second pin lower surface 246 . The second pin upper surface 243 may be configured for engagement with the distal end 227 of the first pin 226 . [0041] Turning now to FIG. 5 illustrating a cross sectional view of a lock assembly 200 prior to the insertion and positioning of a mating key assembly 100 according to an embodiment of the invention. As shown, ( FIG. 5 a ) in one embodiment when a key blade 100 is not inserted into the lock assembly 200 , the outer actuator 230 biases the first pin housing 224 and first pin 226 downwardly or inwardly. Alternatively or in addition to the outer actuator 230 , the inner actuator 232 may also downwardly or inwardly force or bias the first pin 226 . These forces may move the first pin housing 224 and/or first pin 226 in a downwardly direction, so that at least a portion of the first pin housing 224 and/or first pin 226 enter into the cylinder 208 aperture 240 while another portion of the first pin housing 224 and/or first pin 226 , respectively, remains in the drum 206 , thereby preventing the rotation of cylinder 208 . As shown in FIG. 5 a , in one embodiment of the invention, when a depression 250 , is disposed in the guide way 210 of the cylinder 208 of lock assembly 200 , the bore in the cylinder 240 is configured to prevent the lower pin housing 242 from sliding into the depression 250 , likewise, pin housing 242 is configured to limit the downward motion of pin 244 into depression 250 in the guide way 210 of cylinder 208 in lock assembly 200 . As shown in FIG. 5 b , pin housing 242 and pin 244 are beveled in their distal end at an angle that is configured to interact with the angle at the distal end of key blade 112 , such that sliding key blade 112 into the guide way 210 engages the beveled distal end of pin housing 242 ( FIG. 5 b ), lifting the housing 242 from guide way 210 and then likewise proceed to engage pin 244 ( FIG. 5 c ) and lift pin 244 from guide way allowing the pin to align with floating element 104 (not shown). Absent the configuration shown in FIG. 5 , pin housing 242 and pin 244 would slide into depression 250 and prevent the insertion of key blade 112 , thereby, through the use of the right angle in beveling both the key blade 112 and the distal ends of pin housing 242 and pin 244 , in combination with a lock assembly 200 having a depression 250 disposed in the guide way 210 of the cylinder 208 , the inventors have added to the complexity and thereby the security of the key/lock combination. [0042] The presence of the first pin housing 224 and/or first pin 226 in both the cylinder aperture 240 and the drum 206 of the column 202 creates an interference that prohibits the rotational movement of the cylinder 208 about the barrel 204 . For the embodiment illustrated in FIG. 4 , when a key assembly 100 is positioned into the lock assembly 200 , and the floating element 104 is properly positioned on the blade 112 so that the cap 120 in floating element 104 engages the second pin housing and/or pin 242 , 244 , then when the biasing means 122 , such as a spring in one embodiment exerts the correct amount of force to counter the forces exerted on the actuator (such as forces created by outer actuator 230 and inner pin actuator 232 ) and to move at least a portion of the floating element 104 , such as for example the cap 120 , a proper distance, the first pin housing 224 and/or first pin 226 may be forced outside of the cylinder 208 without a portion of the second pin housing 242 and/or second pin 244 entering the bore 222 . If these criteria are satisfied, the first pin housing and pin 224 , 226 respectively and second pin housing and pin 242 , 244 respectively may be positioned so as to not inhibit the rotational movement of the cylinder 208 about the barrel 204 . If however the biasing means 122 in floating element 104 does not exert adequate force in one embodiment; and/or in another embodiment, the location of the base 124 along the aperture 109 axis is not anchored precisely as necessary; and/or, in another embodiment, the cap 120 is not biased away from the base 124 to a sufficient distance; or any combination thereof in other certain embodiments, at least a portion of the first pin housing 224 and/or first pin 226 may continue to be extended into the cylinder aperture 240 while the remainder of the first pin housing 224 and/or first pin 226 is in bore 222 of the column 202 , thereby creating an interference that inhibits the rotational movement of the cylinder 208 . Conversely, if the biasing means such as a spring in one embodiment exerts too large a force and/or in another embodiment, the location of the base 124 along the aperture 109 axis is not anchored precisely as necessary; and/or, in another embodiment, the cap 120 is biased away from the base 124 to an extended distance; or any combination thereof in other certain embodiments, at least a portion of the second pin housing 242 and/or second pin 244 may be pushed into bore 222 of the column 202 while the remainder of the second pin housing 242 and/or second pin 244 remains in the cylinder aperture 240 , thereby creating an interference that inhibits the rotational movement of the cylinder 208 . [0043] FIG. 5 illustrates the second pin housing 242 and second pin 244 touching the bottom of the lock guide way 210 prior to the insertion of the key assembly 100 . According to such an embodiment, the second pin housing 242 and second pin 244 and/or key assembly 100 may be configured to allow the second pin housing 242 and second pin 244 to be lifted outwardly when a key assembly 100 is inserted into the lock assembly 200 , such as, for example, through the use of tapered surfaces. Further, the second pin housing 242 and second pin 244 need not be touching the bottom of the lock guide way 210 prior to the corresponding key assembly 100 being inserted into the lock assembly 200 . Moreover, the second pin housing 242 and second pin 244 may be in the lock guide way 210 but above the bottom of the lock guide way 210 before the insertion of the key assembly 100 so as to minimize possible interference with the ability to position the key assembly 100 into the lock assembly 200 . [0044] FIG. 6 a illustrate a cross sectional view of a key assembly 100 having multiple floating elements 104 a , 104 b rotatably symmetrical, positioned in a lock assembly 200 according to an embodiment of the present invention. FIG. 6 b illustrates an enlarge view of floating element 104 a in FIG. 6 a engaging a second pin 244 according to an embodiment of the present invention. As shown, floating elements 104 a and 104 b may have caps 120 a , 120 b respectively positioned along or about the first and second surfaces 106 , 108 , respectively, of the key blade 112 . While floating elements 104 a , 104 b are illustrated as being next to each other, in certain other embodiments, floating elements 104 a , 104 b may be spaced apart at different locations along the length and/or width of the blade 112 . Further, although FIGS. 6 a , 6 b illustrate only a mating cylinder aperture 240 , pins 226 , 244 respectively, pin housings 224 , 242 respectively and actuators 230 , 232 respectively for one of the floating elements 104 a , the lock assembly 200 may also include similar components for other floating elements 104 b. [0045] As illustrated in FIG. 6 b , floating elements 104 a , 104 b may be positioned in apertures 109 a , 109 b respectively that have counter bores having a depth that allows the upper surface of the caps 120 a , 120 b and bottom surface of the base 124 a , 124 b to be flush, above, or recessed in the respective first or second surface 106 , 108 of key blade 112 . [0046] According to the embodiment illustrated in FIGS. 6 a , 6 b , when the key assembly 100 is properly positioned within the mating lock assembly 200 , floating element 104 a , cylinder aperture 240 , and bore 222 of the column 202 are aligned. The biasing means, such as a spring in one embodiment 122 a of the floating element 104 a may then be actuate. The extent the biasing means 122 a such as an identical-pole facing magnet in certain embodiment may be actuated depend in one embodiment on several design criteria. For example, the size and force of the biasing means 122 a may be countered by the size and force of the outer actuator 230 and/or inner pin actuator 232 , alone or in combination. Additionally, the tabs 127 a of the cap 120 a and lips 129 a of the base 124 a may limit the distance the cap 120 a may be biased away from the base 124 a . Each of these design criteria may be implemented in precisely controlling the distance or amount the may move the first pin housing 224 and first pin 226 and/or second pin housing 242 and second pin 246 so as to allow for the cylinder 208 to be rotated, and thereby operate the lock assembly 200 . [0047] In one embodiment, the key blade may comprise a combination of actuating means such as magnets and springs. FIG. 12 , shows an exploded view of such embodiment having four ( 4 ) symmetrically positioned floating elements wherein floating element ( 104 a ) in the key blade ( 112 ), where key blade ( 112 ) is having a first surface and a second surface ( 108 ), the key blade configured to be inserted into a mating lock; a first aperture ( 109 a ) in the key blade ( 112 ), the aperture having an axis; a cap ( 120 a ) having an outer surface ( 123 a , FIG. 3 ), captured in the aperture ( 109 a ) for continuous axial travel between a first limit extending out of the first surface ( 106 ) and a second limit recessed within the aperture ( 109 a ); and a base ( 124 a ) having an outer surface ( 131 a ), captured in the aperture ( 109 a ) for continuous axial travel between a first limit extending out of the second surface ( 108 ) and a second limit recessed within the aperture ( 109 a ); wherein the base ( 124 ) is biased away from the cap ( 120 ) with a biasing means ( 122 a ) which is a spring with ball bearing ( 260 a and 260 b ) disposed on opposite sides of the spring ( 122 a ) and protruding from both the base ( 124 a ) and the cap ( 120 a ); and wherein floating element ( 104 b ) is embedded in a second aperture ( 109 b ) in the key blade ( 112 ), the second aperture ( 109 b ) having an axis; a cap ( 120 b ) having an outer surface ( 123 b ), captured in the second aperture ( 109 b ) for continuous axial travel between a first limit extending out of the first surface ( 106 ) and a second limit recessed within the aperture ( 109 a ); and a base ( 124 b ) having an outer surface ( 131 b ), captured in the second aperture ( 109 b ) for continuous axial travel between a first limit extending out of the second surface ( 108 ) and a second limit recessed within the second aperture ( 109 b ); wherein the base ( 124 b ) having a magnet ( 122 b ′) associated therewith is biased away from the cap ( 120 b ) having a magnet ( 122 b ″) associated therewith, the magnets (,) positioned with the same poles facing facing adjacent surfaces thus creating a repelling force and biasing the cap ( 120 b ) from the base ( 124 b ). [0048] In one embodiment, provided herein is a key assembly ( 100 ) comprising: a key blade ( 112 ), the key blade being substantially flat and having a first surface ( 106 ) and a second surface ( 108 ), the key blade configured to be inserted into a mating lock ( 200 ); an aperture in the key blade ( 109 ), the aperture having an axis; a cap ( 120 ) having an outer surface ( 130 ), captured in the aperture ( 109 ) for continuous axial travel between a first limit extending out of the first surface ( 106 ) and a second limit recessed within the aperture ( 109 ); and a base ( 124 ) having an outer surface ( 131 ), captured in the aperture ( 109 ) for continuous axial travel between a first limit extending out of the second surface ( 108 ) and a second limit recessed within the aperture ( 109 ); and a magnet ( 122 ) associated with the base ( 124 ), the cap ( 120 ) or both, the magnet having sufficient magnetic strength to attract or repel a movable part in the key blade ( 112 ), or the lock ( 200 ) from a locking position to an unlocking position in the lock ( 200 ), or in both the key ( 100 ) and the lock ( 200 ). [0049] For example, in the embodiment illustrated in FIGS. 6 a , 6 b , the biasing means, 122 a such as a spring in one embodiment, may activate to allow cap 120 a to be biased outwardly against the mating second pin housing 242 and/or second pin 244 . Whether the cap 120 a engages either the second pin housing 242 , the second pin 244 , or both, may be determined by the size, shape, and/or configuration of the mating surfaces of the cap 120 a , second pin housing 242 , and second pin 244 . For example, as shown in FIGS. 6 b , the relative sizes of the cap 120 a , second pin housing 242 , and second pin 244 allow the cap 120 a to directly engage both the second pin housing 242 and second pin 244 . [0050] Additional combinations, and thereby security may be provided by requiring that the second pin housing 242 and second pin 244 mate a specific surface configuration of the cover 120 a . For example, FIG. 6 c illustrates a partial cross sectional view of key assembly 1100 having a contoured cap 1120 a posited in a lock assembly 1200 that includes a second pin 1244 having a mating contoured tip 1245 according to an embodiment of the present invention. In the embodiment shown in FIG. 6 c , the use of first and second pin housings have been eliminated. Therefore, the column 1202 includes a drum 1206 configured for the placement and sliding movement of a first pin 1226 , and the cylinder 1208 includes an aperture 1240 configured to receive and allow the sliding movement of a second pin 1244 . As illustrated, the second pin 1244 includes a tip 1245 that is configured to mate with the contoured surface of the cap 1120 a so that, when engaged, a portion of the tip 1245 fits within a recess 1125 in the cap 1120 a . If the portion of the tip 1245 were too large to properly fit all the way within the recess 1125 and thus not mate the recess 1125 , the second pin 1244 would sit too high on floating element 1104 a when the cap 1120 a is biased away from the base 1124 a , resulting in at least the upper surface 1243 of the second pin 1244 extending into the aperture 1222 of the column 1202 , thereby creating an interference that prohibits the rotational movement of the cylinder 1208 about the barrel 1204 . Conversely, if the size of the recess 1125 is too large and/or too deep, the second pin 1244 may sit too deep in the recess 1125 , resulting in the second pin 1244 being drawn to far into the floating element 1104 a when the cap 1120 a is biased away from the base 1124 a , resulting in a portion of the first pin 1226 being moved inwardly so that the first pin 1226 is in both in the drum 1206 of the cylinder 1208 and the aperture 1222 of the column 1202 . The presence of the first pin 1226 in both the bore 1222 of the column 1202 and the aperture 1240 of the cylinder 1208 creates an interference that inhibits the rotational movement of the cylinder 1208 , and thereby prohibits unlocking of the lock. Therefore, even a slight error in sizing in an unauthorized attempt to replicate and use the key assembly of the present invention unsuccessful. [0051] Referencing FIGS. 6 a , 6 b , the second pin housing 242 and/or second pin 244 may then be moved against the force of the outer actuator 230 and/or inner pin actuator 232 to move the first pin housing 224 and first pin 226 into the bore 222 of the column 202 while the second pin housing 242 and/or second pin 244 remain in the cylinder aperture 240 . More specifically, the engagement between the first pin housing and pin 224 , 226 with the second pin housing and pin 242 , 244 occurs at a distance equal to the diameter of the cylinder 208 so that the cylinder 208 can be rotated without prohibitive interference from the first pin housing and pin 224 , 226 and the second pin housing and pin 242 , 244 . This requires precise forces from the biasing means 122 such as a spring in one embodiment, and actuators 230 , 232 and tight tolerances for at least the fixed location of the floating element 104 along the aperture 109 axis, pins 226 , 244 , and pin housings 224 , 242 . Once the key assembly 100 is allowed to rotate in the cylinder 208 , the key assembly 100 may operate as a traditional key to unlock the lock assembly. [0052] Different types of actuators for biasing means 122 , outside actuator 230 , and/or inner pin actuator 232 may be used. More specifically, although the biasing means 122 , and actuators 230 , and 232 are illustrated in FIG. 6 a as springs, other types of actuators may be used, for example, a magnet or air pressure, among others. Moreover, biasing means 122 , and actuators 230 , and 232 may each individually provide a force alone or in conjunction with another biasing means. For example, in embodiments in which the biasing means 122 is an identical pole-facing magnet, a mating magnet in the locking assembly 200 may have a polarity that is identical that of the outer surface of biasing means 122 in the key assembly 100 , and thereby be rejected by the actuator 122 when the corresponding key assembly 100 is properly positioned in the lock assembly 200 . [0053] Further, rather than provide separate magnets, components of the floating element 104 , such as the cap 120 , among others, and components of the lock assembly, such as, for example, the second pin 242 , among others, may be construction from the necessary metallic materials or be imparted with a specific polarity for floating of the lock assembly 200 . [0054] Reference is made to FIG. 13 , provides a key assembly 100 positioned in a lock assembly 200 , the key assembly 100 , comprising wherein floating element ( 104 a ) in the key blade ( 112 ), where key blade ( 112 ) is having a first aperture ( 109 a ) in the key blade ( 112 ), the aperture having an axis; a cap ( 120 a ) having an outer surface ( 123 a , FIG. 3 ), captured in the aperture ( 109 a ) for continuous axial travel between a first limit extending out of the first surface ( 106 ) and a second limit recessed within the aperture ( 109 a ); and a base ( 124 a ) having an outer surface ( 131 a ), captured in the aperture ( 109 a ) for continuous axial travel between a first limit extending out of the second surface ( 108 ) and a second limit recessed within the aperture ( 109 a ); wherein the base ( 124 ) is biased away from the cap ( 120 ) with a biasing means ( 122 a ) which is a spring with a ball bearing ( 260 a ) protruding from both the cap ( 120 a ); and wherein floating element ( 104 b ) is embedded in a second aperture ( 109 b ) in the key blade ( 112 ), the second aperture ( 109 b ) having an axis; a cap ( 120 b ) having an outer surface ( 123 b ), captured in the second aperture ( 109 b ) for continuous axial travel between a first limit extending out of the first surface ( 106 ) and a second limit recessed within the aperture ( 109 a ); and a base ( 124 b ) having an outer surface ( 131 b ), captured in the second aperture ( 109 b ) for continuous axial travel between a first limit extending out of the second surface ( 108 ) and a second limit recessed within the second aperture ( 109 b ); wherein the base ( 124 b ) having a magnet ( 122 b ′) associated therewith is biased away from the cap ( 120 b ) having a magnet ( 122 b ″) associated therewith, the magnets ( 122 b ′, 122 b ″) are positioned with identical poles facing adjacent surfaces thus creating a repelling force and biasing the cap ( 120 b ) from the base ( 124 b ); the lock assembly 200 having a barrel 204 , a column 202 extending from the barrel 204 , and a cylinder 208 configured to rotate within the barrel 204 , the cylinder 208 including a guide way 210 ; the column 202 having an bore 222 configured to receive the sliding movement of a first pin housing 224 a , the first pin housing 224 a configured to receive the sliding movement of a first pin 226 a ; the cylinder 208 including a cylinder aperture 206 a configured to receive the sliding movement of a second pin housing 242 a , the second pin housing 242 a configured to receive the sliding movement of a second pin 244 a , the first pin 226 a being inwardly biased against the second pin 244 a so as to place the first pin 226 a in the cylinder aperture 206 when the key assembly 100 is not positioned in the lock assembly 200 ; the key assembly 100 configured to outwardly bias and move the cap 120 b or the base 124 b against the first pin 226 a using the magnetic biasing force of floating element 104 b when the key assembly 100 is positioned in the lock assembly 200 so that the second pin 244 a and the second pin housing 242 a are located inside the cylinder 208 and the first pin 226 a and first pin housing 224 are located outside of the cylinder 208 . In certain embodiment the second pin and pin housing are magnetic and the biasing of the second pin is done by the magnetic elements in the key blade such that absent the magnetic force generated by the magnets in the floating element, the lock remains in a locking position. [0055] In another embodiment, provided herein is a lock assembly 200 comprising: a barrel 204 ; a column 202 extending from the barrel, the column having at least two column apertures 222 a , 222 b ; a cylinder 208 configured to rotate within the barrel, the cylinder including a guide way 210 sized and configured to receive a key blade 112 , the cylinder 208 including a cylinder aperture axially registered with the column aperture 222 a when the lock assembly is locked, and movable out of registration with the column aperture with the key blade to unlock the lock assembly; a first and a second pin captured by one of the cylinder and the column, the pins having a first portion slidable in the cylinder aperture and a second portion slidable in the column aperture, the pins normally being biased to a locking position with the first portion within the cylinder aperture and the second portion within the column aperture to lock the cylinder relative to the barrel; a magnetically influenced part associated with the first pin, the magnetically influenced part being movable responsive to a magnetic field provided in the guide way to move the first pin to an unlocking position entirely outside one of the cylinder aperture and the column aperture; and a mechanically influenced part associated with the second pin, the mechanically influenced part being movable responsive to a non-magnetic force provided in the guide way to move the second pin to an unlocking position entirely outside one of the cylinder aperture and the column aperture. [0056] In one embodiment, locking safety pin is non-alligned with any locking pin in column 202 . Accordingly and in another embodiment, when key blade 112 , comprises floating elements 104 a , 104 b , 104 n in key blade 112 , one floating element having a magnet biasing means (see FIG. 13 , 14 ) will bias the cap 120 or the base 124 against the locking pin slidably movable in the column 202 aperture 222 , while its symmetric counterpart will repel or attract the safety locking pin thus allowing movement of the cylinder 208 in the barrel 206 . As shown in FIG. 14 , column 202 comprises and additional aperture containing a mechanically biased locking pin, a magnetically biased safety locking pin located within the cylinder and extending within an aperture located in the barrel 208 and an additional magnetic or non-magnetic locking pin. [0057] In one embodiment the magnetically influenced part of either the locking pin or the locking safety pin is integral with the pin and is positioned to repel or attract a magnetic field provided in the keyway. In one embodiment, the magnetically influenced part is associated with the safety locking pin and is slidable within the cylinder aperture adjacent to the keyway and is non-alligned with the locking key. In another embodiment the first locking pin is normally biased into its locking position by a resilient element. In one embodiment, the second column aperture 222 b is generally coaxial with the first column aperture and diametrically opposed to the first column aperture. In another embodiment, the magnet is movable normal to the direction of insertion of the key blade in the guide way. [0058] In one embodiment, the magnet 122 is further defined as a first magnet 122 ′, the invention further comprising a second magnet 122 ″ associated with the base or the cap, the second magnet being positioned to repel the first magnet normal to the direction of insertion of the key blade in the guide way. [0059] In another embodiment, the biasing means used to move the locking pins is a magnet that is further defined as a first magnet 122 b ′, the invention further comprising a second magnet 122 b ″ associated with the base or the cap, wherein the first and second magnets being movable with respect to the other magnet, the second magnet being positioned to be repelled by or repel the first magnet normal to the direction of insertion of the key blade in the guide way. In another embodiment the repelling magnets bear between the key blade and the pin to bias the pin into its unlocking position. [0060] For embodiments in which air pressure is used as an actuator, the floating element 104 may include at least one air passageway that is sized to deliver a predetermined amount of pressure to counter the pressure needed to be overcome by the floating element 104 to properly position the first and second pin housings 224 , 242 and first and second pins 226 , 244 along the interface of cylinder 208 and barrel 204 so as to allow the cylinder 208 to rotate. [0061] According embodiments of the present invention, when in the locked position prior to the insertion of a key assembly 100 , rather than creating an inference by moving a portion of the first pin housing 224 and/or first pin 226 into the cylinder aperture 240 , a portion of the second pin housing 242 and/or second pin 244 may instead be drawn into the bore 222 of the column 202 while another portion of the second pin housing 242 and/or second pin 244 , respectively, remains in the cylinder aperture 240 . According to such an embodiment, the floating element 104 may have a polarity opposite to a polarity in the lock assembly 200 that may draw the second pin housing 242 and/or second pin 244 out of the aperture 240 while retaining the first pin housing 224 and first pin 226 in the bore 222 of the column 202 so that the first and second pins and housings, 224 , 226 , 242 , 244 respectively do not inhibit the rotational movement of the cylinder 208 about the barrel 204 . According to one such embodiment, biasing means 122 and the first pin 224 , second pin 242 , first pin housing 226 , and/or second pin housing 244 may be construction of magnets or be imparted with polarities that, when properly mated, allow the first pin 226 , second pin 244 , first pin housing 224 , and second pin housing 242 be positioned in the lock assembly 200 so as to not inhibit the rotational movement of the cylinder 208 . [0062] In one embodiment, the invention provides a key assembly 100 positioned in a lock assembly 200 , the key assembly 100 , comprising: a key blade 112 , the key blade having a first surface 106 and a second surface 108 , the key blade 112 configured to be inserted into the lock 200 ; an aperture 109 in the key blade 112 , the aperture 109 having an axis; a cap 120 having an outer surface 123 , captured in the aperture 109 for continuous axial travel between a first limit extending out of the first surface 106 and a second limit recessed within the aperture 109 ; and a base 124 having an outer surface 131 captured in the aperture 109 for continuous axial travel between a first limit extending out of the second surface 108 and a second limit recessed within the aperture 109 ; wherein the base 124 is biased away from the cap 120 ; the lock assembly 200 having a barrel 204 , a column 202 extending from the barrel 204 , and a cylinder 208 configured to rotate within the barrel 204 , the cylinder 208 including a guide way 210 ; the column 202 having an bore 222 configured to receive the sliding movement of a first pin housing 224 , the first pin housing 224 configured to receive the sliding movement of a first pin 226 ; the cylinder 208 including a cylinder aperture 206 configured to receive the sliding movement of a second pin housing 242 , the second pin housing 242 configured to receive the sliding movement of a second pin 244 , the first pin 226 being inwardly biased against the second pin 244 so as to place the first pin 226 in the cylinder aperture 206 when the key assembly 100 is not positioned in the lock assembly 200 ; the key assembly 100 configured to outwardly bias and move the cap 120 or the base 124 against the first pin 226 when the key assembly 100 is positioned in the lock assembly 200 so that the second pin 244 and the second pin housing 242 are located inside the cylinder 208 and the first pin 226 and first pin housing 224 are located outside of the cylinder 208 . [0063] FIG. 7 illustrates a cross sectional view of a section of the lock assembly 200 in which the key assembly 100 has been inserted into the lock assembly 200 according to an embodiment of the present invention. In this embodiment, the lock guide way 210 includes a depression 250 in which the base 124 a is inserted when the key assembly 100 is positioned in the lock assembly 200 . The addition of the depression 250 and the limit the cap 120 a may be separated from the base 124 a by the tabs 127 and lip 129 may reduce the distance that the floating element 104 moves the first and second pins 226 , 244 and first and second housings 226 , 244 . For example, when activated, the base 124 a may be located in the depression 250 , and therefore be lower in the cylinder 208 than where the base 124 a is located in the embodiment illustrated in FIG. 6 . Thus, by lowering the base 124 , the cap 120 a may not extend from surface 106 the key blade 112 in the embodiment in FIG. 7 than the embodiment shown in FIG. 6 a . A longer second pin 244 and/or second pin housing 242 may therefore be required in the embodiment shown in FIG. 7 so that the engagement of the second housing and pin 242 , 244 and first housing and pin 224 , 226 occurs along the diameter of the cylinder 208 so as to allow for the cylinder 208 to be rotated, and thereby operate the lock assembly 200 . [0064] FIG. 8 illustrates a cross sectional view of a section of the lock assembly 200 having a lower pin assembly 300 in which the key assembly 100 has been inserted into the lock assembly 200 according to an embodiment of the present invention. The lower pin 302 moves through an opening 306 in the cylinder 208 and is under the force of a spring 308 . The lower pin assembly 300 includes a lower pin 302 and bottom cylinder 304 . As show in FIG. 8 , the base 124 a may have a contoured surface complementary to the tip 309 of the lower pin 302 . Moreover, these mating surfaces of the tip 309 and base 124 a allow the lower pin 302 to be properly position so that when activated, the lower pin assembly 300 does not extend beyond the outer diameter of the cylinder 208 . However, if the tip 309 is improperly configured for the contour of the base 124 , the tip may not properly mate the contour of the base 124 , but instead may abut against the bottom of the base 124 . Such an arrangement may prohibit the lock from operating, as the lower pin assembly 300 may extend beyond the diameter of the cylinder 208 , and thereby interfere with the rotation of the cylinder 208 . [0065] When the tip 309 does properly mate with the contour of the base 124 a , the lower pin assembly 300 may extend into the barrel 204 or the plug 310 of the lower actuating element 309 may be forced by a spring 308 into the cylinder 208 , both of which may inhibit rotational movement of the cylinder 208 . [0066] FIG. 9 a illustrates a cross sectional view of a section of the lock assembly 200 having a lower pin assembly 300 in which the key assembly 100 has been inserted into the lock assembly according to an embodiment of the present invention. In the embodiment illustrated in FIG. 9 a , the base 124 a includes an actuator pin 126 a , a portion of which may slide outwardly through an aperture in the outer surface 131 of base 124 a beyond the base 124 a . For example, the base 124 a may include an orifice through which at least a portion of the actuator pin 126 a may travel. The actuator pin 126 a includes a distal end 128 , a proximal end 130 , and at least one shoulder 132 . The distal end 128 engages the tip 309 of the lower pin 302 . According to one embodiment, the biasing means 122 a , such as a spring in one embodiment imparts a downward force against the shoulder 128 to direct the actuator pin 126 a downwardly against the lower pin 302 . Further, the shoulder 128 may limit the distance the actuator pin 126 a may travel out of the base 124 a and/or retain the actuator pin 126 a in the base 124 a thereby again, increasing the number of possible key/lock combination and adding to the security of the entry way. Due to the precision required in the depth that the bottom cylinder 304 and plug 310 must move to reach the proper position so as to not prohibit the cylinder 208 from moving, the configuration of the actuator pin 126 a may add further complexity to the ability to the unauthorized successful duplication of the key assembly 100 . [0067] FIG. 9 b illustrates a cross sectional view of a section of the key assembly 100 having an actuator pin 126 b extending from the cap 120 a of the floating element 104 a according to an embodiment of the present invention. The actuator pin 126 b shown in FIG. 9 b is similar to the actuator pin 126 a shown in FIG. 9 a , except, rather than extending from the base 124 a and exerting a force against the lower pin assembly 300 , the actuator pin 126 b in FIG. 9 b extends from the cap 120 and exerts a force against the second pin 244 . Additionally, the embodiment illustrated in FIG. 9 b includes the feature of a depression 250 , as previously discussed with reference to FIG. 7 . [0068] FIG. 10 illustrates a cross sectional view of a key assembly 100 and a lock assembly 200 in which the floating elements 104 a , 104 b include a protruding ball 260 a , 260 b according to an embodiment of the present invention. The partially protruding ball 260 a , 260 b may be retained in the floating elements 104 a , 104 b by a variety of different ways, including, for example, having in the cover 120 a , 120 b an opening smaller than the outer diameter of the partially protruding ball 260 a , 260 b . Biasing means 122 a , 122 b such as elastic materials in certain embodiments may force at least a portion of the protruding ball 260 a , 260 b to extend outwardly from the cap 120 , the base 124 as shown in FIG. 3 b and FIG. 14 , or both in floating elements 104 a , 104 b . For example, in the embodiment illustrated in FIG. 10 , the biasing mean 122 a may force at portion of the protruding ball 260 a to extend beyond the cover 120 a so that the partially protruding ball 260 a engages and moves the second pin 244 outwardly while the cover 120 a engages and moves the second housing 242 outwardly. The distance the protruding ball 260 a extends from the cover 120 a is configured so that the second pin 244 moves the distance required to move the first pin 226 out of the aperture 240 of the cylinder 208 and into the bore 222 of the column 202 while retaining the second pin 244 in the aperture 240 of the cylinder 208 . Additionally, because the partially protruding ball 260 a extends from the cover 120 a , the second pin 244 may have a different length than that of the second pin housing 242 , further complicating the unauthorized duplication of the key assembly 100 . [0069] FIG. 11 illustrates a cross sectional view of a key assembly 100 and lock assembly 200 in which the partially protruding balls 260 a , 260 b extend from the base 124 a , 124 b of floating elements 104 a , 104 b and the lock assembly 200 includes a lower lock actuating assembly 300 according to an embodiment of the present invention. Similar to the embodiment illustrated in FIG. 10 , the floating elements 104 a , 104 b may be configured to control the extent the protruding balls 260 a , 260 b may be outwardly biased when floating elements 104 a , 104 b are actuated, such as, for example, controlling the size of the aperture opening in the lower surface 131 a , 131 b of base 124 a , 124 b respectively, through which the balls 260 a , 260 b partially protrude. [0070] In the embodiment illustrated in FIG. 11 , when the floating element 104 a is actuated in at the proper location along the axis of the key blade 112 aperture 109 when inserted in the lock assembly 200 , the protruding ball 260 a engages a lower pin 400 . The lower pin 400 may slidingly move inside a lower housing 402 . The lower housing 402 may slide in a lower bore 404 of the cylinder 208 . The lower pin 400 may include a plunger 401 that engages a lower protruding ball 336 of a lock floating assembly 300 . In addition to the lower protruding ball 336 , the lock floating assembly 300 may include a cover 333 , an actuator 334 and a base 335 . The cover 333 and base 335 of the lock assembly 300 may be retained together in a manner similar to that described above with respect to the cover 120 a and base 124 a of the floating element 104 a of the key assembly 100 , such as, for example, the cover 333 having a lower protrusion 336 with taps 337 that engage the lips 338 of the base 335 . In use, when the lock biasing mechanism 300 inwardly extends into lower bore 404 of the cylinder or the lower pin 400 or lower pin housing 402 extends into the opening 210 in the barrel, an interference is created that inhibits the rotational movement of the cylinder 208 . When the proper forces are exerted on the lower pin 400 , lower pin housing 402 , and lock floating assembly 300 , and the protruding balls 260 a , 336 base 124 a , and cover 333 extend the proper distance, neither the lower pin 400 and lower pin housing 402 do not extend into the opening 210 nor does assembly 300 extend in the cylinder 208 so to not inhibit rotational movement of the cylinder 208 . [0071] In one embodiment, provided herein in combination; a key assembly 100 comprising: a key blade 112 , the key blade having a first surface 106 and a second surface 108 , the key blade 112 configured to be inserted into a mating lock; an aperture 109 in the key blade, the aperture having an axis; a cap 120 having an outer surface 123 , captured in the aperture 109 for continuous axial travel between a first limit extending out of the first surface 106 and a second limit recessed within the aperture 109 ; and a base 124 having an outer surface 131 captured in the aperture 109 for continuous axial travel between a first limit extending out of the second surface 108 and a second limit recessed within the aperture 109 ; wherein the base 124 is biased away from the cap; and a mating lock assembly 200 , the lock assembly having a barrel 204 , a column 202 extending from the barrel 204 , and a cylinder 208 configured to rotate within the barrel 204 , the cylinder 208 including a guide way 210 ; the column having an aperture configured to receive the sliding movement of a first pin housing 224 , the first pin housing configured to receive the sliding movement of a first pin 226 ; the cylinder 208 including a cylinder aperture 206 configured to receive the sliding movement of a second pin housing 242 , the second pin housing configured to receive the sliding movement of a second pin 244 , the first pin 226 being inwardly biased against the second pin 244 so as to place the first pin 226 in the cylinder aperture 206 when the key assembly 100 is not positioned in the lock assembly 200 ; the key configured to outwardly bias and move the cap 120 or the base 124 against the first pin 226 when the key assembly 100 is positioned in the lock assembly 200 so that the second pin 244 and the second pin housing 242 are located inside the cylinder 208 and the first pin 226 and first pin housing 224 are located outside of the cylinder 208 . [0072] While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

The present invention is directed to key assemblies and their mating locks, and more particularly, to keys with mutually compressible, actuating elements capable of being continuously positioned axially within apertures in a key blade.

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. provisional application No. 61/623,511, filed Apr. 12, 2012, and entitled “Self-Loading Mini Dolly”, which provisional application is incorporated by reference herein in its entirety. FIELD OF THE INVENTION The present disclosure generally relates to self-loading tow dollies, and more particularly to a self-loading mini dolly that can be used in a variety of towing applications. BACKGROUND OF THE INVENTION Tow truck operators commonly use self-loading tow dollies. When a tow truck is used to tow a vehicle, one end of the vehicle is lifted by the truck. The wheels on the other end of the vehicle typically remain on the pavement. Tow dollies may be used to lift the lower end of the towed vehicle such that the wheels of the tow dollies, instead of the wheels of the towed vehicle, contact the road. Accordingly, lifting all wheels of the towed vehicle from contact with the ground greatly diminishes the possibility of drive train damage and/or excessive wear to the towed vehicle during towing. This is especially true with all-wheel drive vehicles and electric motor driven vehicles. Tow dollies for raising pairs of coaxial vehicle wheels typically employ a pair of frame-like bases for supporting pairs of dolly wheels. Such dolly bases are placed outside two vehicle wheels of one axle to be lifted or elevated; the two bases being cross connected by parallel spaced tubular axles are typically longitudinally adjustable to accommodate variations in vehicle wheel lateral spacing. Suitable mechanisms are provided for positioning the dolly wheels between a lowered position and a raised towing position which serves to elevate the towed vehicle prior to the actual towing operation. Suitable locking devices are provided for maintaining dolly wheels in desired elevated or lowered positions for storing or towing operations, respectively. Other known mechanisms without separate ratchet systems are employed for maintaining dolly wheels in elevated positions. U.S. Pat. No. 5,941,675 to Orr, fully incorporated herein by reference, shows and describes an exemplary tow dolly. Tow dollies of the type described in U.S. Pat. No. 5,941,675 typically have several sections which are disengageable from one another for easy storage and transport of the tow dolly. For example, there are often two frame-like wheel assemblies where the dolly's wheels are mounted on spindle assemblies which are attached to the frame-like wheel assemblies. Brackets on the frame-like wheel assemblies accommodate axles that engage the wheels of the vehicle to be towed. Tow dollies must have sturdy components that articulate in a manner when a car is lifted off the ground in just a few moments. Spindle assemblies are typically made of steel as are the brackets where the steel rail ends of the axles are fitted to complete assembly. This “steel on steel” construction permits steel dolly components to be welded together and has proved to be sturdy in the field. Over a period spanning nearly forty years, the steel self-loading tow dolly became the industry standard. Using all steel components and welding steel components together on the dolly frame results, however, in a heavy tow dolly that an operator must carry from the tow truck to the towed vehicle. Even when disassembled, the pieces of current tow dollies are heavy and cause strain on tow truck operators which may lead to back injuries and other health problems. When tow truck operators hand carry self-loading tow dollies from and to a tow truck, weight is a key factor in eliminating back and other injuries. All steel constructed tow dollies are sturdy, but weight continues to be an issue. Thus, the need remains for an improved self-loading tow dolly configuration that is not only sturdy, but has the added benefit of weight reduction. Often vehicles or motorcycles which need to be winched up the bed of a car carrier lack a suitable location for placement of the tow hook on the vehicle or motorcycle without potential damage to the vehicle. Moreover, newer vehicles with all-wheel drive, hybrid vehicles, and all-electric vehicles whose transmissions are locked, incur potential damage when winched up the bed of a car carrier. Additionally, the front end of low-clearance vehicles incur potential damage because of the load angle of the car carrier bed. It is an object of my invention to provide a self-loading mini dolly system that solves these problems. SUMMARY OF THE INVENTION The disclosure is generally directed to a self-loading mini dolly. An illustrative embodiment of the self-loading mini dolly includes a dolly frame; a front dolly arm carried by the dolly frame; a wheeled front axle carried by the front dolly arm; a front dolly platform carried by the front dolly arm, the front dolly platform selectively deployable between lowered and raised positions by a leverage bar; a rear dolly arm carried by the dolly frame in spaced-apart relationship to the front dolly arm; a wheeled rear axle carried by the rear dolly arm; and a rear dolly platform carried by the rear dolly arm, the rear dolly platform selectively deployable between lowered and raised positions by a leverage bar. BRIEF DESCRIPTION OF THE DRAWINGS The disclosure will now be made, by way of example, with reference to the accompanying drawings, in which like reference numerals refer to similar elements and in which: FIG. 1 is a rear perspective view of an illustrative embodiment of the self-loading mini dolly deployed in a collapsed and fully extended configuration preparatory to placement around the vehicle tire (not illustrated) of a vehicle which is to be towed in exemplary application of the dolly; FIG. 2 is a rear perspective view of an illustrative embodiment of the self-loading mini dolly deployed in a raised and fully extended configuration preparatory to towing of a vehicle; FIG. 3 is a rear perspective view of an illustrative embodiment of the self-loading mini dolly deployed in a raised and fully retracted configuration for compact stowing; FIG. 4 is a front perspective view of an illustrative embodiment of the self-loading mini exemplary application of the dolly; FIG. 5 is an outside side perspective view of an illustrative embodiment of the self-loading mini dolly deployed in a collapsed and fully extended configuration preparatory to placement around the vehicle tire (not illustrated); FIG. 6 is an outside side perspective view of an illustrative embodiment of the self-loading mini dolly deployed in a raised and fully extended configuration preparatory to towing; FIG. 7 is an inside side perspective view of an illustrative embodiment of the self-loading mini dolly deployed in a collapsed and fully extended configuration preparatory to placement around the vehicle tire (not illustrated); FIG. 8 is an inside side perspective view of an illustrative embodiment of the self-loading mini dolly deployed in a raised and fully extended configuration preparatory to towing of a vehicle; FIG. 9 is an outside perspective view of an illustrative embodiment of the self-loading mini dolly deployed in a raised and partially-extended configuration; FIG. 10 is a rear perspective view of an alternative illustrative embodiment of the self-loading mini dolly deployed in a collapsed and fully extended configuration preparatory to placement around the vehicle tire (not illustrated) of a vehicle which is to be towed in exemplary application of the dolly; FIG. 11 is a perspective view of an exemplary vehicle tow bar which facilitates winching of a motorcycle or an automobile up a car carrier bed using one or a pair of self-loading mini dollies; FIG. 12 is a perspective view of an exemplary tow hook adaptor which facilitates winching of a motorcycle up a car carrier bed using a self-loading mini dolly; FIG. 13 is a perspective view of an automobile as the automobile is winched onto a car carrier bed, more particularly illustrating the front wheels of the automobile resting on a pair of self-loading mini dollies; FIG. 14 is a perspective view of the front of an automobile, with the front wheels of the vehicle resting on a pair of self-loading mini dollies and a vehicle tow bar attached to the self-loading mini dollies in winching of the automobile; FIG. 15 is a bottom perspective view of a self-loading mini dolly with the vehicle tow bar and the tow hook adaptor attached to the self-loading mini dolly preparatory to winching of a motorcycle ( FIG. 16 ); and FIG. 16 is a rear perspective view of the self-loading mini dolly with the vehicle tow bar and the tow hook adaptor attached to the self-loading mini dolly and a motorcycle secured to the self-loading mini dolly, the vehicle tow bar and the tow hook adaptor in towing of the motorcycle. FIG. 17 is a front perspective view of an illustrative embodiment of safety chocks which attach to the rear of the mini dollies to prevent sudden unintended rollback during winching. FIG. 18 is a rear perspective view of an illustrative embodiment of the safety chocks attached to the back of the self-loading mini dolly, deployed in a raised and fully retracted configuration; FIG. 19 is an illustrative embodiment of a leverage bar which may be used to raise and lower the self-loading mini dolly. DETAILED DESCRIPTION The following detailed description is merely exemplary in nature and is not intended to limit the described embodiments or the application and uses of the described embodiments. As used herein, the word “exemplary” or “illustrative” means “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” or “illustrative” is non-limiting and is not necessarily to be construed as preferred or advantageous over other implementations. All of the implementations described below are exemplary implementations provided to enable persons skilled in the art to practice the disclosure and are not intended to limit the scope of the appended claims. Moreover, the illustrative embodiments described herein are not exhaustive and embodiments or implementations other than those which are described herein and which fall within the scope of the appended claims are possible. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. Relative terms such as “front” and “rear” as used herein are intended for descriptive purposes only and are not necessarily intended to be construed in a limiting sense. Referring to FIGS. 1-10 of the drawings, an illustrative embodiment of the self-loading mini dolly is generally indicated by reference numeral 1 . The self-loading mini dolly 1 includes a generally elongated dolly frame 2 . A generally elongated front dolly arm 40 and a generally elongated rear dolly arm 42 may extend from the dolly frame 2 in spaced-apart relationship to each other. The front dolly arm 40 and the rear dolly arm 42 may each be generally perpendicular to the longitudinal axis of the dolly frame 2 and may be generally parallel to each other. In some embodiments, a frame handle 5 may be provided on the dolly frame 2 for carrying and handling purposes. A front dolly platform 8 may be provided on the front dolly arm 40 of the dolly frame 2 . The front dolly platform 8 may have a generally elongated, flat, rectangular, blade-shaped configuration. The longitudinal axis of the front dolly platform 8 may be parallel to the longitudinal axis of the front dolly arm 40 . Similarly, a rear dolly platform 24 is provided on the rear dolly arm 42 of the dolly frame 2 . The rear dolly platform 24 may have a generally elongated, flat, rectangular, blade-shaped configuration. The longitudinal axis of the rear dolly platform 24 may be parallel to the longitudinal axis of the rear dolly arm 42 . A front axle assembly 16 includes a front axle 12 provided on the front dolly arm 40 . In some embodiments, the front axle 12 may be attached to the front dolly arm 40 via a pair of spaced-apart front axle flanges 41 which extend from the front dolly arm 40 . A pair of front dolly wheels 13 is provided on the front axle 12 . Similarly, a rear axle assembly 30 includes a rear axle 26 provided on the rear dolly arm 42 . In some embodiments, the rear axle 26 may be attached to the rear dolly arm 42 via a pair of spaced-apart rear axle flanges 43 which extend from the rear dolly arm 42 . A pair of rear dolly wheels 27 is provided on the rear axle 26 . As illustrated in FIG. 2 , in some embodiments, a tow bar 14 may extend between the rear axle flanges 43 for purposes which will be hereinafter described. The front axle flanges 41 may pivotally engage the front dolly arm 40 and the front axle 12 . The rear axle flanges 43 may pivotally engage the rear dolly arm 42 and the rear axle 26 . Accordingly, as the front axle flanges 41 pivot relative to the front axle 12 and the front dolly arm 40 and the rear axle flanges 43 pivot relative to the rear axle 26 and the rear dolly arm 42 , the dolly frame 2 , with the front dolly platform 8 and the rear dolly platform 24 , can be selectively deployed between the lowered position illustrated in FIG. 1 and the raised position illustrated in FIG. 2 for purposes which will be hereinafter described. A front lever 17 is provided on the front axle 12 and engages one of the front axle flanges 41 to facilitate selective raising and lowering of the dolly frame 2 and front dolly platform 8 on the front axle 12 such as by use of a leverage bar 110 ( FIG. 19 ) having a leverage bar receptacle 112 on the end of an elongated leverage bar shaft 114 . A rear lever 31 is provided on the rear axle 26 and engages one of the rear axle flanges 43 to facilitate selective raising and lowering of the dolly frame and rear dolly platform 24 on the rear axle 26 by use of the leverage bar 110 ( FIG. 19 ). Accordingly, the leverage bar receptacle 112 receives the front lever 17 or the rear lever 31 as a user (not illustrated) grasps the leverage bar shaft 114 to selectively raise and lower the front axle assembly 16 or the rear axle assembly 30 , respectively. A front cam lock 36 is provided on the front axle flange 41 and engages the front lever 17 to selectively lock the front dolly platform 8 in the raised position. A rear cam lock 38 is provided on the rear axle flange 41 and engages the rear lever 17 to selectively lock the rear dolly platform 24 in the raised position. Therefore, the front axle lever 17 can be selectively manipulated to raise the front dolly platform 8 from the collapsed configuration illustrated in FIGS. 1 , 5 and 7 to the raised configuration illustrated in FIGS. 2 , 6 and 8 by use of the leverage bar 110 ( FIG. 19 ) until the front cam lock 36 engages the front axle lever 17 , thereby locking the front dolly platform 8 in the raised configuration. The rear axle lever 31 can likewise be manipulated to raise the rear dolly platform 24 from the collapsed configuration to the raised configuration by use of the leverage bar 110 ( FIG. 19 ) until the rear cam lock 38 engages the rear axle lever 31 , thereby locking the rear dolly platform 24 in the raised configuration. As illustrated in FIGS. 3 , 4 , 9 and 10 , in some embodiments, the dolly frame 2 may be selectively length-adjustable. Accordingly, the dolly frame 2 may include a generally elongated frame member receptacle 3 and a generally elongated frame member 20 which telescopically inserts into the frame member receptacle 3 . The front dolly platform 8 may extend from the front dolly arm 40 and the rear dolly platform 24 may extend from the frame member 20 . The frame member receptacle 3 may be selectively locked in non-sliding relationship to the frame member 20 to achieve a selected length of the dolly frame 2 by extending a lock pin 6 through a selected one of multiple receptacle openings 4 in the frame member receptacle 3 and through a selected registering frame member opening 11 ( FIG. 10 ) in the frame member 20 . As illustrated in FIGS. 9 and 10 , in other embodiments, the receptacle openings 4 may be provided in the frame member 20 and the frame member opening 11 may be provided in the frame member receptacle 3 . Alternative designs known by those skilled in the art may be used to render the dolly frame 2 length-adjustable. In exemplary application, a pair of self-loading mini-dollies 1 can be used to raise whichever pair of vehicle wheels that remains on the pavement after the other pair of vehicle wheels is raised by the wheel lift of the towing vehicle 80 . The front dolly platform 8 and the rear dolly platform 24 of each self-loading mini dolly 1 are initially placed beneath the front and rear portions, respectively, of the tire. The length of the dolly frame 2 may be adjusted to facilitate proper placement of the front dolly platform 8 and the rear dolly platform 24 beneath the tire. After the front dolly platform 8 and the rear dolly platform 24 have been properly placed and the length of the dolly frame 2 adjusted as necessary, the front axle lever 17 is manipulated by use of the leverage bar 110 ( FIG. 19 ) to raise the front dolly platform 8 from the collapsed configuration illustrated in FIGS. 1 , 5 and 7 to the raised configuration illustrated in FIGS. 2 , 6 and 8 until the front cam lock 36 engages the front lever 17 , illustrated in FIG. 4 . The rear axle lever 31 is likewise manipulated by use of the leverage bar 110 ( FIG. 19 ) to raise the rear dolly platform 24 from the collapsed configuration to the raised configuration until the rear cam lock 38 engages the rear lever 31 , as illustrated in FIG. 6 , thereby locking mini-dolly 1 in the raised configuration. Accordingly, the front dolly platform 8 and the rear dolly platform 24 raise and maintain the wheel of the vehicle in a raised position relative to the pavement (not illustrated) as the front dolly wheels 13 and the rear dolly wheels 27 support the raised dolly frame 2 and vehicle wheel above the pavement. With the cam locks 36 and 38 engaged to keep each mini-dolly 1 from inadvertently collapsing, the towing vehicle 80 is then operated to tow the towed vehicle 84 as the self-loading mini dollies 1 continue to maintain the vehicle wheels in a raised position and the front dolly wheels 13 and the rear dolly wheels 27 travel on the pavement during towing. Therefore, the self-loading mini-dollies 1 allow vehicles, the wheels of which are unable to rotate because of damage, or transmissions that are engaged, or wheels that are locked by electric drive motors, to be towed, preventing the likelihood of excessive wear and/or damage to the drive train or wheels of the vehicle as may otherwise be the case if the vehicle wheels traveled on the pavement during the towing operation. After the vehicle has arrived at the desired destination, the self-loading mini-dollies 1 can be collapsed ( FIG. 1 ) by operation of the leverage bar 110 ( FIG. 19 ) on the respective front lever 17 and rear lever 31 . The front dolly platform 8 and the rear dolly platform 24 are then lowered from beneath the vehicle tire as the mini-dolly is collapsed, after which the vehicle is lowered from the towing vehicle. It will be appreciated by those skilled in the art that the dolly frame 2 can be selectively shortened, as illustrated in FIG. 3 , for compact stowing when not in use. Referring next to FIGS. 11-16 of the drawings, the self-loading mini dolly 1 can be used in a variety of towing applications such as in the winching of a vehicle 84 ( FIGS. 13 and 14 ) or a motorcycle 88 ( FIG. 16 ) up the flat bed 81 of a towing vehicle 80 ( FIG. 13 ) for towing of the vehicle 84 or motorcycle 88 , for example and without limitation. Alternatively, a single mini dolly 1 may be used for lifting the disabled wheel or tire of a single vehicle or trailer for transport of the vehicle or trailer. As illustrated in FIGS. 11-14 , in vehicle towing applications, a pair of self-loading mini dollies 1 can be used in conjunction with a vehicle tow bar 50 which facilitates secure attachment of the mini tow dollies 1 to the towing vehicle 80 . As illustrated in FIG. 11 , the vehicle tow bar 50 may include a generally elongated tow bar frame 51 . A tow bar plate 52 may extend from a middle portion of the tow bar frame 51 . The tow bar plate 52 has a tow hook adaptor opening 54 . A pair of plate reinforcing members 55 may extend from the respective ends of the tow bar frame 51 to the opposite sides of the tow bar plate 52 to reinforce the tow bar plate 52 on the tow bar frame 51 . A pair of dolly attachment hooks 56 , 58 may be provided at the opposite ends of the tow bar frame 51 to facilitate attachment of the vehicle tow bar 50 to the respective mini tow dollies 1 as will be hereinafter described. As illustrated in FIG. 14 , in an exemplary towing application, a pair of mini tow dollies 1 is initially operated to raise the respective front wheels 85 of the towed vehicle 84 typically in the same manner as was heretofore described. The vehicle tow bar 50 may be attached to the mini tow dollies 1 by engagement of the tow bar hooks 56 , 58 to the cross bar 15 ( FIG. 2 ) on each tow dolly 1 . A tow hook 53 may be attached to the tow hook opening 54 in the tow bar plate 52 of the vehicle tow bar 50 . A winch cable may be attached to towing chain 66 which may be attached to the tow hook 53 . The winch cable attached to towing chain 66 is engaged by the vehicle winch 82 ( FIG. 13 ) on the flat bed 81 of the towing vehicle 80 . Accordingly, by operation of the vehicle winch 82 , the vehicle 84 is winched from the pavement up onto the flat bed 81 of the carrier vehicle 80 as the mini dollies 1 transport the front wheels 85 of the vehicle 80 . Additionally, two pair of mini dollies 1 may transport both front wheels 85 and rear wheels 86 of vehicle 80 . The carrier vehicle 80 may then haul the vehicle 84 to a suitable destination for repair, for example. After the vehicle 84 has arrived at the desired destination, the vehicle winch 82 is operated to lower the vehicle 84 from the flat bed 81 of the towing vehicle 80 onto the pavement. The tow hook 53 ( FIG. 14 ) may be detached from the tow bar plate 52 of the vehicle tow bar 50 , after which the vehicle tow bar 50 is removed from the cross bar 15 of the mini dollies 1 . The mini dollies 1 can then be collapsed by operation of the respective front levers 17 and rear levers 31 , thereby returning vehicle 84 to the pavement. The mini dollies 1 are then removed from beneath the vehicle tires. As illustrated in FIGS. 15 and 16 , in some applications, a mini dolly 1 can be used to tow a motorcycle 88 . Accordingly, the mini dolly 1 is initially deployed in the collapsed configuration. A tow hook adaptor 60 ( FIG. 12 ) may be attached to the cross bar 15 of the mini dolly 1 to facilitate attachment of the mini dolly 1 to the carrier vehicle 80 ( FIG. 13 ). As illustrated in FIG. 12 , the tow hook adaptor 60 may have a bracket opening 62 and a bracket clasp 64 . The tow hook adaptor 60 may be attached to the mini dolly 1 by engagement of the adaptor clasp 64 with the cross bar 15 ( FIG. 15 ). As illustrated in FIG. 15 , a vehicle tow bar 50 may be inverted and inserted between cross bar 15 and cross bar 14 in the front of mini dolly 1 and the tow hook adaptor 60 extended through the tow hook opening 54 in tow bar plate 52 , attaching adaptor clasp 64 ( FIG. 15 ), to cross bar 15 ( FIG. 15 ), on the front of mini dolly 1 . The front wheel 89 of the motorcycle 88 is placed on the mini dolly 1 and the rear wheel 90 typically remains on the pavement. The mini dolly 1 is then raised to lift the front wheel 89 off the pavement. A tow hook 53 is attached to the tow hook adaptor 60 by extending the tow hook 53 through the hook adaptor opening 62 and a towing chain 66 is attached to the tow hook 53 . The vehicle winch 82 ( FIG. 13 ) of the towing vehicle 80 is operated to pull the motorcycle 88 onto the flat bed 81 of the carrier vehicle 80 and the motorcycle 88 is transported to the desired destination. After the motorcycle 88 has arrived at the desired destination, the vehicle winch 82 is operated to lower the motorcycle 88 from the flat bed 81 of the carrier vehicle 80 onto the pavement. The tow hook 53 may be detached from the tow hook adaptor 60 , after which the vehicle tow bar 50 and tow hook adaptor 60 may be removed from the mini dolly 1 . The mini dolly 1 can then be collapsed by operation of the front lever 17 and rear lever 31 . The front dolly platform 8 and the rear dolly platform 24 are then removed from beneath the front wheel 89 of the motorcycle 88 . Referring next to FIGS. 17 and 18 of the drawings, the mini dolly 1 may include a safety chock 100 . The safety chock 100 may be attached to the rear axle 26 of the mini dolly 1 to prevent mini dolly 1 from sudden unexpected rollback down the carrier bed 81 ( FIG. 13 ) of the towing vehicle 80 during towing of the towed vehicle 84 . As illustrated in FIG. 17 , the safety chock 100 may include a pair of spaced-apart safety chock base members 102 . Each safety chock base member 102 may have a concave wheel-engaging surface 102 a . At least one elongated base member connecting rod 104 may connect the safety chock base members 102 . At least one dolly attachment member 106 may extend upwardly from the base member connecting rod 104 . Each dolly attachment member 106 may include an attachment member shaft 108 which extends from the dolly attachment member 106 and an attachment hook 109 which terminates the attachment member shaft 108 . Accordingly, as illustrated in FIG. 18 , prior to towing the towed vehicle 84 ( FIG. 13 ), a pair of the safety chock base members 102 may be placed on the flat bed 81 behind the respective self-loading mini dollies 1 . The rear dolly wheels 27 of the mini dolly 1 engage the wheel-engaging surfaces 102 a of the respective spaced-apart safety chock base members 102 . The attachment hooks 109 of the respective dolly attachment members 106 receive the rear axle 26 of the mini dolly 1 . Therefore, the safety chock 100 prevents each mini tow dolly 1 from inadvertently slipping downwardly on the flat bed 81 of the towing vehicle 80 during towing of the towed vehicle 84 . After towing of the vehicle 84 , the dolly attachment members 106 may be detached from the rear axle 26 prior to lowering the towed vehicle 84 from the flat bed 81 . While I have described my invention in connection with what I presently consider to be the most practical and preferred embodiment, it is to be understood that my invention is not limited to the described embodiments, but, on the contrary, I intend it to cover various modifications and equivalent arrangements included within the scope of the appended claims.

A self-loading mini dolly includes a dolly frame; a front dolly arm carried by the dolly frame; a wheeled front axle carried by the front dolly arm; a front dolly platform carried by the front dolly arm, the front dolly platform selectively deployable between lowered and raised positions; a rear dolly arm carried by the dolly frame in spaced-apart relationship to the front dolly arm; a wheeled rear axle carried by the rear dolly arm; and a rear dolly platform carried by the rear dolly arm, the rear dolly platform selectively deployable between lowered and raised positions.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to a method of detecting an ink residual quantity in an ink jet printer and, more particularly, to a method of detecting an ink residual quantity in an ink jet printer having a reciprocating carriage mounted with an ink jet head and an ink tank. 2. Related Background Art There are a variety of methods in ink jet printers. In any method, generally, a residual quantity of the ink within an ink tank is detected, and the user is warned of an ink exhaustion. The above-described method of detecting an ink residual quantity includes those of detecting an electric resistance value of the ink and optically detecting an ink liquid level. Herein, there arise the following problems inherent in the ink jet printer of such a type that a carriage mounted with the ink tank is reciprocated together with an ink jet head. Ink oscillations are caused because of the acceleration acting on the ink tank mounted on the carriage during bilateral turnabouts of the carriage. In this state, the ink residual quantity can not be accurately detected by any method. Hence, this type of ink jet printer has hitherto involved the step of detecting the ink residual quantity by setting the carriage in a home position after performing one-page printing or detecting the ink residual quantity by stopping the carriage similarly in the home position for a short period of time after performing the one-page printing. Further, some printers incorporate the liquid level oscillation preventive mechanism having a complicated structure so as not to cause the oscillations of the liquid level to prevent a sway of the ink. The foregoing method of detecting the ink residual quantity per page presents such a big problem that the ink is consumed up during printing when the page size is as large as A1 or A2. In addition, the method of detecting the ink residual quantity by stopping the carriage for the short time per line causes a problem wherein an accumulating total of the stop time exerts an influence on a printing efficiency as a loss of printing speed if the number of printing lines is large. SUMMARY OF THE INVENTION It is a general object of the present invention, which overcomes the problems inherent in the prior art, to provide a method of detecting an ink residual quantity in an ink jet printer, which is capable of eliminating a possibility of blank printing when effecting a print on the large-sized paper by detecting the ink residual quantity at a relatively high frequency and also keeping a good printing efficiency. It is another object of the present invention to provide a method of detecting an ink residual quantity in an ink jet printer, having a carriage mounted with an ink jet head and an ink tank, for effecting a print by reciprocating the carriage in a main scan direction, the method comprising the step of detecting the ink residual quantity in an equispeed motion area of the carriage. According to the present invention having the above-mentioned construction, the ink residual quantity can be detected per line with a stability without stopping the carriage or incorporating a special liquid level oscillation preventive mechanism. BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of the present invention will become apparent during the following discussion taken in conjunction with the accompanying drawings, in which: FIG. 1 is an entire plan view showing an embodiment of an ink jet printer to which an ink residual quantity detecting method according to the present invention is applied; FIG. 2 is a sectional view illustrating a state where an ink tank is mounted in the vicinity of a carriage of FIG. 1; FIG. 3 is a sectional view illustrating a state where the ink tank vicinal to the carriage is mounted; and FIG. 4 is a block diagram depicting an ink residual quantity detecting device for embodying the ink residual quantity detecting method of this invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An illustrative embodiment of the present invention will hereinafter be described with reference to the drawings. FIG. 1 is a plan view showing the whole of an embodiment of an ink jet printer to which an ink residual quantity detecting method of this invention is applied. Referring to FIG. 1, a cylindrical platen 2 is rotatably supported on a printer body through a rotary shaft 3 extending in the horizontal direction. This platen 2 is rotationally driven by a motor 4, whereby paper 5 wound on an outer periphery thereof is carried in a subscan direction. The printer body 1 in front of the platen 2 is mounted with a pair of carriage shafts 6, 6 each parallel to the rotary shaft 3. A carriage 7 is so supported on these two carriage shafts 6, 6 as to be possible of reciprocations along the platen 2. Then, the carriage 7 is reciprocated in a main scan direction along the platen 2 by means of a motor 8 rotationally drivable in forward and reverse directions. The carriage 7 is mounted with ink jet heads 9 for effecting a print by jetting inks on the paper 5 and ink tanks 10. In accordance with this embodiment, the ink involves the use of four colors such as cyan, magenta, yellow and black. The ink tanks and the printing heads 9 are provided by fours corresponding to the respective inks. FIGS. 2 and 3 are sectional views illustrating a vicinity of the carriage 7. FIG. 2 illustrates a state where the ink tank 10 for replacement is mounted. FIG. 3 depicts a state where the ink tank 10 is demounted. Referring to FIGS. 2 and 3, the carriage 7 is fitted with a holder for holding the ink tank 10. Attached to this holder 11 are an ink supply needle 12 and an air supply needle 13 each made of a conductive material in such a way that the needles are in point-contact with a metal plate 14 fixed to the holder 11 to absorb scatters in bending angles of the respective needles 12, 13. Note that the needles 12, 13 are electrically conductive to the metal plate 14. A bottom wall 10A of the ink tank 10 placed on the holder 11 is formed with an annular projection 15 communicating with the interior. Provided in an interior of this annular projection 15 is a rubber plug admitting penetrations of the ink supply needle 12 and the air supply needle 13 and also capable of preventing a leakage of the ink in the ink tank 10. Note that if an additive or the like of this rubber plug 16 is dissolved in the ink, there exists a possibility to deteriorate the performance of the ink jet head 9, and hence the upper surface of the rubber plug 16 is coated with a thin film 17 breakable by the needles 12, 13 to thereby prevent the rubber plug 16 from being wetted by an unused ink. Further, the annular projection 15 is covered with a cap 18. An ink supply tube 19 led to the ink jet head 9 is connected to the ink supply needle 12. Further, an air supply tube 20 led to an unillustrated air supply means is connected also to the air supply needle 13. Disposed upwardly of the portion of the rubber plug 16 through which the air supply needle 13 passes is a conduit pipe 21 for guiding the air supplied into the ink tank 10 via the air supply needle 13 to an upper edge inside the ink tank 10 so that the same pipe extends in the vertical direction. A liquid-waste filter 22 is fitted to an upper end of this conduit pipe 21, thereby preventing an infiltration of the ink into the conduit pipe 21. A metal leaf spring 23 is attached to the holder 11. On the other hand, a plug member 24 composed of an insulating material is formed on the bottom wall 10A of the ink tank 10. Fitted to this plug member 24 is an electrode pin 25 extending inwardly outwardly of the ink tank 10. Then, this electrode pin 25 contacts the leaf spring 23 when mounting the ink tank 10 on the holder 11. It is to be noted that a safety cover 26 for preventing human fingers from touching on the respective needles 12, 13 is so provided as to be biased downwards by an unillustrated spring. In accordance with this embodiment, the safety covers 26 and the springs are independently attached by fours corresponding to the respective colors. FIG. 4 is a block diagram illustrating an ink residual quantity detecting device for embodying the ink residual detecting method according to the present invention. This ink residual quantity detecting device detects variations in electric resistance between the ink supply needle 12 and the electrode pin 25 due to the residual quantity of the ink within the ink tank 10. The ink residual quantity detecting device includes a transistor 27, a collector C of which is connected to the metal plate 14. Further, a bias resistor 28 is connected to a base B of this transistor 27. In addition, the ink residual quantity detecting device has a comparator 29. A pair of voltage-dividing resistors 30, 30 for a reference value are connected to a reference input signal side of this comparator 29. On the other hand, a measurement input signal side of the comparator 29 is connected to the leaf spring 23. A voltage-dividing resistor 31 for measurement is connected to this measurement input signal side. An output compensation resistor 32 is connected to an output of the comparator 29. Connected further to this output is a printer control circuit 33 for controlling the whole ink jet printer. Then, when the ink has been consumed to such an extent that a liquid level of the ink within the ink tank 10 is a constant value or under, and when the electric resistance between the ink supply needle 12 and the electrode pin 25 exceeds a threshold value, the output of the comparator is switched over. As a consequence, the printer control circuit 33 temporarily stops the operation of the printer. Besides, a display unit 34 for informing the user of an ink exhaustion is connected to this printer control circuit 33. Next, the operation of the thus constructed embodiment will be explained. Printing is performed alternately by carrying the paper 5 with rotations of the platen upon driving the motor 4 and by jetting the inks on the paper 5 from the ink jet heads 9 mounted on the carriage 7 while moving the carriage 7 upon driving the motor 8. During turnabouts of the carriage 7 in the right-and-left directions in the printing stroke, the carriage 7 has to stop one time at the end of the stroke of the carriage 7. Besides, if the carriage 7 is not moved at a predetermined printing speed during printing, a printing efficiency decreases. Hence, the carriage 7 has to be accelerated or decelerated at the end of the printing stroke of the of the carriage 7. For this reason, the acceleration acts on the carriage 7. This state is demonstrated by FIG. 1. An a-d range in FIG. 1 is a printing stroke of the carriage 7. When moving the carriage 7 in an arrowed direction I of the FIGURE, an a-b range at the onset of motion of the carriage 7 is defined as an acceleration area. A b-c range subsequent thereto is defined as an equispeed area. Further, a c-d range just before the turnabout is defined as a deceleration area. Note that a printing area where printing is actually performed is within the equispeed area. Further, when moving the carriage 7 in an arrowed direction II of the FIGURE which is opposite to the arrowed direction I, the d-c range at the onset of motion of the carriage 7 serves as the acceleration area. The c-b area subsequent thereto serves as the equispeed area. Further, the b-a range just before the turnabout serves as the deceleration area. The acceleration acts on the carriage 7 in the acceleration and deceleration areas of the carriage 7. Therefore, the ink in the ink tank mounted on the carriage 7 sways. This sway of the ink ends immediately when the carriage 7 starts making the equispeed motion. Then, in accordance with this embodiment, every time the carriage moves in one direction, and during the equispeed motion of the carriage 7, a residual quantity of the ink within the ink tank 10 is detected. The ink residual quantity is detected concretely in a printing end position inwardly vicinal to the point c just before the deceleration in the case of printing in the arrowed direction I. The detection is also effected in a printing end position inwardly vicinal to the point b similarly just before the deceleration in the case of printing in the arrowed direction II. Next, the ink residual quantity detecting method will be explained by way of a concrete example. To start with, the number of printing pulses is counted to find out the ink residual quantity detecting positions, i.e., the printing end positions inwardly vicinal to the points b, c. The positions inwardly vicinal to b, c are thus detected. Then, when carriage 7 reaches to this position, a short-time bias current on the order of 500 μs flows to the base B of the transistor 27 shown in FIG. 4 at this point of time. The current is thereby flowed to the ink within the ink tank 10 via the voltage-dividing resistor 31. Just then, the output of the comparator 29 is switched over depending on whether the residual quantity of the ink within the ink tank 10 is large or small. Therefore, when the output of the comparator 29 is switched over with a reduction in the residual quantity of the ink within the ink tank 10, the printer control circuit 33 temporarily stops the operation of the printer. Simultaneously, the display unit 34 informs the user of the ink exhaustion. Accordingly, there is no possibility wherein printing continues while the ink has been consumed up. As described above, in accordance with this embodiment, the ink residual quantity is detected every time the carriage 7 moves in each direction during the printing process. Unlike the conventional detection of the ink residual quantity per page, there is no possibility in which printing continues in the as-exhausted state of the ink. Further, the ink residual quantity is detected during the equispeed motion of the carriage 7, with the result that the ink does not sway. It is therefore feasible to accurately detect the residual quantity. Moreover, an electrifying time to the ink is extremely short, and hence there exists no possibility in which the ink undergoes electrolysis. It should be noted that the present invention is not limited to the embodiment discussed above, and a variety of modifications may be effected as the necessity arises. For instance, according to the present invention, the ink residual quantity is detected in the carriage equispeed motion area. However, even when entering somewhat the carriage accelerating or decelerating motion area, and if the detection is done before causing the sway of the ink, this is, as a matter of course, included in the technical scope of the present invention. Further, as a timing of detecting the ink residual quantity, the quantity may be detected not at every carriage movement in each direction but at every carriage reciprocation; or alternatively, the detection may be effected every time a plurality of movements are performed. As discussed above, according to the present invention, the ink residual quantity is detectable after attenuating the oscillations of the liquid level of the ink during the bilateral turnabouts of the carriage. Hence, it is possible to stably detect the ink residual quantity per line without temporarily stopping the carriage or adding a special liquid level oscillation preventive mechanism.

A method of detecting an ink residual quantity in an ink jet printer, which is capable of eliminating a possibility of blank printing even when effecting a print on the large-sized paper by detecting the ink residual quantity at a high frequency and of keeping a good printing efficiency. The ink residual quantity is detected in an equispeed motion area of the carriage. The ink residual quantity can be stably detected per line without stopping the carriage and providing a special liquid level oscillation preventive mechanism.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a class of metallocene compounds, to a catalyst for the polimerization of olefins comprising said metallocenes and to processes for the polimerization of olefins carried out in the presence of said catalyst. The invention also relates to processes for the preparation of the ligands of said metallocenes, as well as to a class of novel bridged ligands. 2. Description of the Prior Art Metallocene compounds are known which are active as catalyst components in the olefin polymerization reactions. European patent application EP-A-35 242, for instance, discloses a process for the polymerization of ethylene and propylene in the presence of a catalyst system comprising (a) a cyclopentadienyl compound of a transition metal and (b) an alumoxane. European patent application EP-A-129 368 discloses a catalyst system for the polymerization of olefins comprising (a) a mono-, bi- or tri-cyclopentadienyl coordination complex with a transition metal and (b) an alumoxane. With this catalyst it is possible to prepare polyolefins of controlled molecular weight. European patent application EP-A-351 392 discloses a catalyst, which can be used in the preparation of syndiotactic polyolefins, comprising a metallocene compound with two cyclopentadienyl based rings linked with a bridging group in which one of the two cyclopentadiene rings is substituted differently from the other. The preferred compound indicated is isopropylidene(fluorenyl)(cyclopentadienyl)hafnium dichloride. EP-A-604 908 discloses a class of bis-fluorenyl compounds bridged with a one-atom-bridge. These metallocenes are useful as catalyst components for the polymerization of olefins and, especially, for the preparation of high molecular weight atactic polypropylene. SUMMARY OF THE INVENTION New metallocene compounds have now been found which can be advantageously used as catalyst components in the polymerization reactions of olefins. An object of the present invention consists of a new metallocene compound of formula (I) (YR p ) q (CP)(CP′)MX 2   (I) wherein Cp is a group selected from those of formula (II) and (III): wherein m and n, same or different from each other, are integer comprised between 2 and 6 and, preferably, comprised between 3 and 5; Cp′ is a group selected from those of formula (II), (III) e (IV): wherein (YR p ) q is a divalent group which bridges the two groups Cp and Cp′, Y being selected indifferently from C, Si, Ge, N and P; p is 1 when Y is N or P, and is 2 when Y is C, Si or Ge; q can be 0, 1, 2 or 3; M is a transition metal selected from Ti, Zr or Hf; the substituents X, same or different from each other, are halogen atoms, —OH, —SH, R, —OR, —SR, —NR 2 or —PR 2 ; the substituents R, same or different from each other, are hydrogen atoms, C 1 -C 20 alkyl radicals, C 3 -C 20 cycloalkyl radicals, C 2 -C 20 alkenyl radicals, C 6 -C 20 aryl radicals, C 7 -C 20 alkylaryl radicals or C 7 -C 20 arylalkyl radicals, optionally containing Si or Ge atoms and, additionally, two adjacent R substituents on Cp or Cp′ may form a C 5 -C 8 cycle and, further, two R substituents of the same YR 2 group or of two adjacent YR 2 groups may form a ring comprising from 3 to 8 atoms; when q=0, the R′ substituents are difined as the R substituents while, when q=1, 2 or 3, the two R′ substituents of the groups Cp and Cp′ together form the divalent group (YR p ) q . Another object of the present invention is a process for the preparation of a cyclopentadienylic compound of formula (II), which comprises reacting a cycloalkene of formula (V) with a cycloalkene derivative of formula (VI) to obtain a cyclopentenone of formula (VII), wherein n, m and R have the meaning given, and X is OH, OR, O(CO)R, Cl or Br, in accordance with the reaction scheme below: Still another object of the present invention is a process for the preparation of a cyclopentadienylic compound of formula (III), which comprises reacting a cycloalkene of formula (V′) with a benzene derivative of formula (VIII) to obtain a compound of formula (IX), wherein n, m, R and X have the meaning given, in accordance with the reaction scheme below: Yet another object of the present invention is a cyclopentadiene ligand of formula (XI): (YR p ) q (CP)(CP′)  (XI) wherein Cp, Cp′, (YR p ) q , Y, R, p and q have the meaning given. A further object of the present invention is a catalyst for the polymerization of olefins comprising the product of the reaction between: (A) a metallocene compound of formula (I), optionally as a reaction product with a organo-aluminium of formula AlR 4 3 or Al 2 R 4 6 , in which the substituents R 4 , same or different from each other are R 1 or halogen, and (B) an aluminoxane, optionally in admixture with a organo-aluminium compound of formula AlR 4 3 or Al 2 R 4 6 , in which the substituents R 4 , same or different from each other, are defined as above or one or more compounds capable of forming a alkyl metallocene cation. Still a further object of the invention consists of a process for the polymerization of olefins comprising the polymerization reaction of at least one olefinic monomer in the presence of the above described catalyst. Yet a further object of the present invention is a process for the oligomerization of propylene carried out in the presence of the above described catalyst. DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred R substituents are hydrogen, C 1 -C 10 alkyl radicals, more preferably C 1 -C 3 , C 3 -C 10 cycloalkyl radicals, more preferably C 3 -C 6 , C 2 -C 10 alkenyl radicals, more preferably C 2 -C 3 , C 6 -C 10 aryl radicals C 7 -C 10 alkaryl radicals or C 7 -C 10 aralkyl radicals. The alkyl radicals may be straight chain or branched in addition to cyclic. The divalent group (YR p ) q is preferably selected from CR 2 , SiR 2 , GeR 2 , NR, PR and (CR 2 ) 2 . More preferably it is a group selected from Si(CH 3 ) 2 , CH 2 , (CH 2 ) 2 and C(CH 3 ) 2 . The preferred transition metal M is Zr. The X substituents are preferably halogen atoms or R groups. More preferably they are chlorine or a methyl radical. Non limitative examples of ligands of formula (II) according to the invention are: octahydrofluorene, 9-methyl-octahydrofluorene, bis(cyclotrimethylene)cyclopentadiene. Non limitative examples of ligands of formula (III) according to the invention are: tetrahydrofluorene, 1,2-cyclo-hexamethylene-indene. Non limitative examples of ligands of formula (IV) according to the invention are: cyclopentadienyl, indenyl, tetrahydroindenyl. A particular class of metallocene according to the invention is those compounds of formula (I) in which q=0, and that is those in which the Cp and Cp′ groups are not linked to each other by a bridge. Non limitative examples of the above mentioned class of metallocenes are: bis(1,2-cyclotetramethyleneinden-1-yl)titanium dichloride, bis(1,2-cyclotetramethyleneinden-1-yl)zirconium dichloride, bis(1,2-cyclotetramethyleneinden-1-yl)hafnium dichloride, bis(1,2-cyclotetramethyleneinden-1-yl)titanium dimethyl, bis(1,2-cyclotetramethyleneinden-1-yl)zirconium dimethyl, bis(1,2-cyclotetramethyleneinden-1-yl)hafnium dimethyl, bis(octahydrofluorenyl)titanium dichloride, bis(octahydrofluorenyl)zirconium dichloride, bis(octahydrofluorenyl)hafnium dichloride, bis(octahydrofluorenyl)titanium dimethyl, bis(octahydrofluorenyl)zirconium dimethyl, bis(octahydrofluorenyl)hafnium dimethyl, (cyclopentadienyl)(1,2-cyclotetramethyleneinden-1-yl)titanium dichloride, (cyclopentadienyl)(1,2-cyclotetramethyleneinden-1-yl)zirconium dichloride, (cyclopentadienyl)(1,2-cyclotetramethyleneinden-1-yl)hafnium dichloride, (cyclopentadienyl)(1,2-cyclotetramethyleneinden-1-yl)titanium dimethyl, (cyclopentadienyl)(1,2-cyclotetramethyleneinden-1-yl)zirconium dimethyl, (cyclopentadienyl)(1,2-cyclotetramethyleneinden-1-yl)hafnium dimethyl, (cyclopentadienyl)(octahydrofluorenyl)titanium dichloride, (cyclopentadienyl)(octahydrofluorenyl)zirconium dichloride, (cyclopentadienyl)(octahydrofluorenyl)hafnium dichloride, (cyclopentadienyl)(octahydrofluorenyl)titanium dimethyl, (cyclopentadienyl)(octahydrofluorenyl)zirconium dimethyl, (cyclopentadienyl)(octahydrofluorenyl)hafnium dimethyl. Another particular class of metallocenes according to the invention is those compounds of formula (I) in which q is different from 0, and the groups Cp and Cp′, preferably same as each other, are selected from those of formula (II) and (III). Preferably, the divalent group (YR p ) q is a Si(CH 3 ) 2 group. Non limitative examples of above cited metallocenes are: dimethylsilanediylbis(2,3-cyclotetramethyleneinden-1-yl)titanium dichloride, dimethylsilanediylbis(2,3-cyclotetramethyleneinden-1-yl)zirconium dichloride, dimethylsilanediylbis(2,3-cyclotetramethyleneinden-1-yl)hafnium dichloride, dimethylsilanediylbis(2,3-cyclotetramethyleneinden-1-yl)titanium dimethyl, dimethylsilanediylbis(2,3-cyclotetramethyleneinden-1-yl)zirconium dimethyl, dimethylsilanediylbis(2,3-cyclotetramethyleneinden-1-yl)hafnium dimethyl, diphenylsilanediylbis(2,3-cyclotetramethyleneinden-1-yl)titanium dichloride, diphenylsilanediylbis(2,3-cyclotetramethyleneinden-1-yl)zirconium dichloride, diphenylsilanediylbis(2,3-cyclotetramethyleneinden-1-yl)hafnium dichloride, diphenylsilanediylbis(2,3-cyclotetramethyleneinden-1-yl)titanium dimethyl, diphenylsilanediylbis(2,3-cyclotetramethyleneinden-1-yl)zirconium dimethyl, diphenylsilanediylbis(2,3-cyclotetramethyleneinden-1-yl)hafnium dimethyl, isopropylidenebis(2,3-cyclotetramethyleneinden-1-yl)titanium dichloride, isopropylidenebis(2,3-cyclotetramethyleneinden-1-yl)zirconium dichloride, isopropylidenebis(2,3-cyclotetramethyleneinden-1-yl)hafnium dichloride, isopropylidenebis(2,3-cyclotetramethyleneinden-1-yl)titanium dimethyl, isopropylidenebis (2,3-cyclotetramethyleneinden-1-yl)zirconium dimethyl, isopropylidenebis(2,3-cyclotetramethyleneinden-1-yl)hafnium dimethyl, dimethylgermanedylbis(2,3-cyclotetramethyleneinden-1-yl)titanium dichloride, dimethylgermanedylbis(2,3-cyclotetramethyleneinden-1-yl)zirconium dichloride, dimethylgermanedylbis(2,3-cyclotetramethyleneinden-1-yl)hafnium dichloride, dimethylgermanedylbis(2,3-cyclotetramethyleneinden-1-yl)titanium dimethyl, dimethylgermanedylbis(2, 3-cyclotetramethyleneinden-1-yl)-zirconium dimethyl, dimethylgermanedylbis(2,3-cyclotetramethyleneinden-1-yl)-hafnium dimethyl, dimethylsilanediylbis(octahydrofluorenyl)titanium dichlioride, dimethylsilanediylbis(octahydrofluorenyl)zirconium dichloride, dimethylsilanediylbis(octahydrofluorenyl)hafnium dichloride, dimethylsilanediylbis(octahydrofluorenyl)titanium dimethyl, dimethylsilanediylbis(octahydrofluorenyl)zirconium dimethyl, dimethylsilanediylbis(octahydrofluorenyl)hafnium dimethyl. Yet another particular class of metallocenes according to the invention is those compounds of formula (I) in which q=1 and the group Cp′ is a non-substituted cyclopentadienyl group. Preferably, the divalent group (YP p ) q is a group >C(CH 3 ) 2 . Non limitative examples of the above cited class of metallocenes are: isopropylidene(cyclopentadienyl)(2,3-cyclotetramethyleneinden-1-yl)titanium dichloride, isopropylidene(cyclopentadienyl)(2,3-cyclotetramethyleneinden-1-yl)zirconium dichloride, isopropylidene (cyclopentadienyl)(2,3-cyclotetramethyleneinden-1-yl)hafnium dichloride, isopropylidene(cyclopentadienyl)(2,3-cyclotetramethyleneinden-1-yl)titanium dimethyl, isopropylidene(cyclopentadienyl)(2,3-cyclotetramethyleneinden-1-yl)zirconium dimethyl, isopropylidene(cyclopentadienyl)(2,3-cyclotetramethyleneinden-1-yl)hafnium dimethyl, isopropylidene(cyclopentadienyl)(octahydrofluorenyl)titanium dichloride, dichloride, isopropylidene(cyclopentadienyl)(octahydrofluorenyl)zirconium dichloride, isopropylidene(cyclopentadienyl)(octahydrofluorenyl)hafnium dichloride, isopropylidene (cyclopentadienyl)(octahydrofluorenyl)titanium dimethyl, isopropylidene(cyclopentadienyl)(octahydrofluorenyl)zirconium dimethyl, isopropylidene(cyclopentadienyl)(octahydrofluorenyl)hafnium dimethyl. Both the above indicated reactions for the preparation of a cyclopentadienylic compound of formula (II) or (III) are conducted in an acid medium. Suitable acid compounds which can be used, alone or in combination, are: mineral acids, such as polyphosphoric acid, phosphoric acid, sulfuric acid, hydrochloric acid, hydrobromic acid; organic acids and peracids, such as formic acid, acetic acid, trifluoroacetic acid, fluorosulfonic acid, methanesulfonic acid, p-toluenesulfonic acid; metal cations, such as silver tetrafluoroborate; trimethylsilyl iodide; phosphorus pentaoxide; polyphosphoric acid being the preferred. The above said reactions can be conducted in a solvent such as methanol, ethanol, acetic anhydride, methylene chloride, carbon tetrachloride, 1,2-dichloroethane, benzene, toluene. The reaction temperature is generally comprised in the range of −78° C. to 350° C., preferably of from 0° C. to 200° C. and, more preferably, of 65° C. to 100° C. The reaction time is generally comprised in the range of 2 minutes to 24 hours and, preferably, of 1 to 4 hours. The cycloalkenes (V) are commercially obtainable, while the 1-cycloalkene derivatives (VI) and the benzene derivatives (VIII) which either are commercially obtainable or can be prepared by known methods. The cyclopentenones (VII) and the compounds (IX) can successively be converted to cyclopentadienyl compounds of, respectively, formula (II) and (III) by means of different methods. For example, the cyclopentenone (VII) and the compound (IX) can be first reduced and then dehydrated to yield the cyclopentadiene (II). Reducing agents suitable for use in the reduction step are, for example, diisopropylaluminum hydride, diisobutyl-aluminum hydride, lithium aluminum hydride, aluminum hydride, 9-BBN. The dehydration step may be performed in the presence of an acid, SOCl 2 , POCl 3 . The conditions for these reaction are reported in J. Am. Chem. Soc., 82, 2498 (1960), and ibid. 83, 5003 (1961). Alternatively, the cyclopentenone (VII) and the compound (IX) can be directly transformed into the cyclopentadiene (II) by reaction with metallic Zn and trimethylsilyl chloride, as described in J. Chem. Soc. Chem. Comm., 935 (1973). According to another method, the cyclopentenone (VII) and the compound (IX), can be reacted with a substituted or unsubstituted p-toluensulfonhydrazide of formula (X) The reaction is carried out in a solvent such as, for example, alcohols, tetrahydrofurane (THF), ethers, benzene, toluene, in the presence or absence of acids, to yield a tosylhydrazone. The water formed during the above reaction may be removed. The thus obtained tosylhydrazone is thereafter reacted with a base to yield the desired products. The reaction is carried out in a solvent such as, for example, hexane, pentane, diethyl ether, N,N,N′,N′-tetramethyl-ethylenediamine. Bases suitable for use in the above reaction are, for instance, methyllithium, n-buthyllithium, s-buthyllithium, t-buthyllithium, lithium, sodium or potassium dialkylamide, potassium t-butoxide, lithium, sodium or potassium hexamethyldisilylazide, sodium hydride, potassium hydride. The preparation of the bridged ligands of the metallocene compounds of formula (I) wherein q is different from 0 and the group Cp is the same as the group Cp′, can be carried out by first reacting a compound of formula (II) or (III) with a compound able to form a delocalized anion on the cyclopentadienyl ring, and thereafter with a compound of formula (YR p ) q Z 2 , wherein Y, R, z and q are defined as above and the substituents Z, same or different from each other, are halogen atoms or tosylate groups. The preparation of the bridged ligands of the metallocene compounds of formula (I) wherein q is different from 0 and the group Cp is different from the group Cp′, can be carried out by reacting a symmetric or asymmetric fulvene with an anionic salt of the substituted Cp group. The metallocene compounds of formula (I) can be prepared by first reacting the bridged ligands prepared as described above, or the cyclopentadienylic compounds of formula (II) or (III), with a compound able to form a delocalized anion on the cyclopentadienyl rings, and thereafter with a compound of formula MZ 4 , wherein M and the substituents Z are defined as above. The metallocene compounds of formula (I) wherein q=0 and Cp is different from Cp′ can be prepared by reacting the dianion of the ligand with a tetrahalide of the metal M, said reaction being carried out in a suitable solvent. A particularly convenient method for preparing the metallocene compounds of formula (I), in which both Cp and Cp′ groups are selected from the groups of formula (II) wherein m=4, is the hydrogenation reaction of the corresponding metallocene compounds in which both Cp and Cp′ are selected from the groups of formula (III). The hydrogenation reaction is carried out in a solvent, such as CH 2 Cl 2 , in the presence of a hydrogenation catalyst, such as PtO 2, and hydrogen. The hydrogen pressures are preferably comprised between 1 and 100 bar, and the temperatures are preferably comprised between −50 and 50° C. In the case at least one X substituent in the metallocene compound of formula (I) to be prepared is different from halogen, it is necessary to substitute at least one substituent Z in the obtained metallocene with at least one X substituent different from halogen. The substitution reaction of substituents Z in the compound of formula (VI) with substituents X different from halogen is carried out by generally used methods. For example, when the substituents X are alkyl groups, the metallocenes can be reacted with alkylmagnesium halides (Grignard reagents) or with lithioalkyl compounds. Non limitative examples of compounds of formula (YR p ) q Z 2 are dimethyldichlorosilane, diphenyldichlorosilane, dimethyldichlorogermanium, 2,2-dichloropropane, 1,2-dibromoethane and the like. Non limitative examples of compounds of formula MZ 4 are titanium tetrachloride, zirconium tetrachloride, hafnium tetrachloride. According to an embodiment of the process according to the invention, the synthesis of the bridged ligands of the metallocene compounds of formula (I) wherein q is different from 0 and the group Cp is the same as the group Cp′ is suitably performed by adding a solution of an organic lithium compound in an aprotic solvent to a solution of the compound (II) or (III) in an aprotic solvent. Thus, a solution containing the compound (II) or (III) in the anionic form is obtained and this is added to a solution of the compound of formula (YR p ) q Z 2 in an aprotic solvent. From the so obtained solution, the bridged ligand is separated by generally used methods. This is dissolved in an aprotic polar solvent, and to this solution a solution of an organic lithium compound in an aprotic solvent is added. The bridged ligand thus obtained is separated, dissolved in an aprotic polar solvent and thereafter added to a suspension of the compound Mz 4 in an apolar solvent. At the end of the reaction the solid product obtained is separated from the reaction mixture by generally used techniques. During the whole process, the temperature is kept between −180° C. and 80° C. and preferably between −20° C. and 40° C. Not limitative examples of apolar solvents which can be used in the above described process are pentane, hexane, benzene and the like. Not limitative examples of aprotic polar solvents which can be used in the above described process are tetrahydrofurane, dimethoxyethane, diethylether, toluene, dichloromethane and the like. In the catalyst of the invention, the aluminoxane used as component (B) can be obtained by the reaction between water and the organo-aluminium compound of formula AlR 4 3 or Al 2 R 4 6 , in which substituents R 4 , same or different from each other are defined above, with the condition that at least one R 4 is not halogen. In this case, the molar ratios of Al/water in the reaction is comprised between 1:1 and 100:1. The molar ratio between aluminium and the metal from the metallocene is comprised between 10:1 and about 5000:1, and preferably between about 100:1 and about 4000:1. The alumoxane used in the catalyst according to the invention is believed to be a linear, branched or cyclic compound, containing at least one group of the type: wherein substituents R 5 , the same or different from each other, are R 1 or a group —O—Al(R 5 ) 2 . Examples of alumoxanes suitable for the use according to the present invention are methylalumoxane (MAO) and isobutylalumoxane (TIBAO). Mixtures of differents alumoxanes are suitable as well. Not limitative examples of aluminium compounds of formula AlR 3 or Al 2 R 4 6 are: Al(Me) 3 , Al(Et) 3 , AlH(Et) 2 , Al(iBu) 3 , AlH(iBu) 2 , Al(iHex) 3 , Al(C 6 H 5 ) 3 , Al(CH 2 C 6 H 5 ) 3 , Al(Ch 2 CMe 3 ) 3 , Al(CH 2 SiMe 3 ) 3 Al(Me) 2 iBu, Al(Me) 2 Et, AlMe(Et) 2 , AlMe(iBu) 2 , Al(Me) 2 iBu, Al(Me) 2 Cl, Al(Et) 2 Cl, AlEtCl 2 , A 2 (Et) 3 Cl 3 , wherein Me=methyl, Et=ethyl, iBu=isobutyl, iHex=isohexyl. Among the above mentioned aluminium compounds, trimethylaluminium (TMA) and triisobutylaminium (TIBAL) are preferred. Not limitative examples of compounds able to form a metallocene alkyl cation are compounds of formula Y + Z − , wherein Y + is a Bronsted acid, able to give a proton and to react irreversibly with a substituent R 2 of the compound of formula (I) and Z − is a compatible anion, which does not coordinate, which is able to stabilize the active catalytic species which originates from the reaction of the two compounds and which is sufficiently labile to be able to be removed from an olefinic substrate. Preferably, the anion Z − comprises one or more boron atoms. More preferably, the anion Z − is an anion of the formula BAr (−) 4, wherein substituents Ar, the same or different from each other, are aryl radicals such as phenyl, pentafluorophenyl, bis(trifluoromethyl)phenyl. Particularly preferred is the tetrakis-pentafluorophenyl borate. Furthermore, compounds of formula BAr 3 can be suitably used. The catalysts of the present invention can also be used on an inert support. That is by depositing the metallocene compound (A), or the reaction product of the metallocene (A) with component (B), or the component (B) and successively the metallocene compound (A), on the inert support such as for example, silica, alumina, styrene-divinylbenzene copolymers or polyethylene. The solid compound so obtained, in combination with further addition of the alkyl aluminium compound as such or pre-reacted with water if necessary, is usefully employed in the gas phase polymerization. The catalysts of the present invention can advantageously be used in a process for the homo- or copolymerization reaction of olefins. According to a particular embodiment of the above process, the catalysts of the present invention can be profitably used in the homo-polymerization reaction of olefins, in particular of ethylene for the preparation of HDPE, or of α-olefins such as propylene and 1-butene. When it is employed a bridged metallocene compound of formula (I) wherein q is different from 0 and the group Cp is the same as the group Cp′, the obtained α-olefin homopolymers have an atactic structure and, therefore, are substantially amorphous. In particular, with the catalyst of the present invention it is possible to prepare propylene oligomers which result to be endowed with allylic terminations; said oligomers can be suitably employed as comonomers in the copolymerization reactions of olefins. Alternatively, when it is employed a metallocene compound of formula (I) wherein q=1 and the group Cp′ is a non-substituted cyclopentadienyl group, the obtained α-olefin homopolymers have a predominantly syndiotactic structure. Another interesting use of the catalysts according to the present invention is for the copolymerization of ethylene with higher olefins. In particular, the catalysts of the invention can be used for the preparation of LLDPE. The LLDPE copolymers which are obtained have a content of ethylene units comprised between 80% and 99% by mols. Their density is comprised between 0.87 and 0.95 g/cc and they are characterized by a uniform distribution of the alpha-olefin comonomers. The olefins useable as comonomers comprise alpha-olefins of the formula CH 2 ═CHR wherein R is a straight, branched or cyclic alkyl radical containing from 1 to 20 carbon atoms, and cycloolefins. Examples of these olefins are propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-esadecene, 1-octadecene, 1-eicosene, allylcyclohexane, cyclopentene, cyclohexene, norbornene, 4,6-dimethyl-1-heptene. The copolymers may also contain small proportions of units deriving from polyenes, in particular from straight or cyclic, conjugated or non conjugated dienes such as, for example, 1,4-hexadiene, isoprene, 1,3-butadiene, 1,5-hexadiene, 1,6-heptadiene. The units deriving from the alpha-olefins of the formula CH 2 ═CHR, from the cycloolefins and/or from the polienes are present in the copolymers in amounts of from 1% to 20% by mole. The catalyst of the invention can also be used for the preparation of elastomeric copolymers of ethylene with alpha-olefins of the formula CH 2 ═CHR, wherein R is an alkyl radical having from 1 to 10 carbon atoms, optionally containing small proportions of units deriving from polyenes. The saturated elastomeric copolymers contain from 15% to 85% by mole of ethylene units, the complement to 100 being constituted by units of one or more alpha-olefins and/or of a non conjugated diolefin able to cylopolymerize. The unsaturated elastomeric copolymers contain, together with the units deriving from the polymerization of ethylene and alpha-olefins, also small proportions of unsaturated units deriving from the copolymerization of one or more polyenes. The content of unsaturated units can very from 0.1 to 5% by weight, and it is preferably comprised between 0.2 and 2% by weight. The elastomeric copolymers obtainable with the catalysts of the invention are endowed with valuable properties such as, for example, low content of ashes and uniformity of distribution of the comonomers within the copolymeric chain. Moreover, a valuable property of said elastomeric copolymers is that their molecular weights are high enough to be of practical interest. In fact, the intrinsic viscosity values (I.V.) of said copolymers are generally higher than 2.0 dl/g and can reach values of 3.0 dl/g and higher. This is a considerable and unpredictable advantage over the copolymers obtainable with a metallocene compound according to the cited EP-A-604 908. The useable alpha-olefins comprise, for example, propylene, 1-butene, 4-methyl-1-pentene. As non conjugated diolefins able to cyclopolymerize, 1,5-hexadiene, 1,6-heptadiene, 2-methyl-1,5-hexadiene can be used. Polyenes useable comprise: polyenes able to give unsaturated units, such as: linear, non-conjugated dienes such as 1,4-hexadiene trans, 1,4-hexadiene cis, 6-methyl-1,5-heptadiene, 3,7-dimethyl-1,6-octadiene, 11-methyl-1,10-dodecadiene; monocyclic diolefins such as, for example, cis-1,5-cyclooctadiene and 5-methyl-1,5-cyclooctadiene; bicyclic diolefins such as for example 4,5,8,9-tetrahydroindene and 6 and/or 7-methyl-4,5,8,9-tetrahydroindene; alkenyl or alkyliden norbornenes such as for example, 5-ethyliden-2-norbornene, 5-isopropyliden-2-norbornene, exo-5-isopropenyl-2-norbornene; polycyclic diolefins such as, for example, dicyclopentadiene, tricyclo-[6.2.1.0 2,7 ]4,9-undecadiene and the 4-methyl derivative thereof; non-conjugated diolefins able to cyclopolymerize, such as 1.5-hexadiene, 1,6-heptadiene, 2-methyl-1,5-hexadiene; conjugated dienes, such as butadiene and isoprene. A further interesting use of the catalysts according to the present invention is for the preparation of cycloolefin polymers. Monocyclic and polycyclic olefin monomers can be either homopolymerized or copolymerized, also with linear olefin monomers. Non limitative examples of cycloolefin polymers which can be prepared with the catalyst of the present invention are described in the European patent applications No. 501,370 and No. 407,870, the contents of which are understood to be incorporated in the present description as a result of their mention. Polymerization processes which use the catalysts of the invention can be carried out in liquid phase, in the presence or not of an inert hydrocarbon solvent, or in gaseous phase. The hydrocarbon solvent can be either aromatic such as, for example, toluene, or aliphatic such as, for example, propane, hexane, heptane, isobutane, cyclohexane. The polymerization temperature generally ranges from about 0° C. to about 250° C. In particular, in the processes for the preparation of HDPE and LLDPE, it is generally comprised between 20° C. and 150° C. and, particularly, between 40° C. and 90° C., whereas for the preparation of the elastomeric copolymers it is generally comprised between 0° C. and 200° C. and, particularly, between 20° C. and 100° C. The molecular weight of polymers can be varied by simply varying the polymerization temperature, the type or the concentration of the catalyst components or, and this represent an advantage of the invention, by using molecular weight regulators such as, for example, hydrogen. The fact that the catalysts of the invention are sensitive to hydrogen as a molecular weight regulator is unexpected in view of the fact that, if the polymerization is carried out in the presence of a metallocene compound according to the cited EP-A-604 908, the hydrogen has no effect on the molecular weight of the obtained polymers, even if used in relevant amounts. The molecular weight distribution can be varied by using mixtures of different cyclopentadienyl compounds, or by carrying out the polymerization in many steps which differ for the polymerization temperatures and/or for the concentrations of the molecular weight regulator. The polymerization yield depends on the purity of the metallocene components in the catalyst. Therefore the metallocene obtained by the process of the invention may be used as such, or subjected to purification treatments. Particularly interesting results are obtained when the components of the catalyst are contacted among them before the polymerization. The contact time is generally comprised between 1 and 60 minutes, preferably between 5 and 20 minutes. The pre-contact concentrations for the metallocene component (A) are comprised between 10 −2 and 10 −8 mol/l, whereas for the component (B) they are comprised between 10 and 10 −3 mol/l. The precontact is generally carried out in the presence of a hydrocarbon solvent and, optionally, of small amounts of monomer. The following examples are supplied for purely illustrative and not limiting purpose. Characterisations The intrinsic viscosity [η] has been measured in tetrahydronaphtalene at 135° C. The molecular weight distribution has been determined by GPC. using a WATERS 150 instrument in orthodiclorobenzene at 135° C. The Melt Index (MI) has been measured under the following conditions: Condition E (I 2 : ASTM D-1238) at 190° C. with a 2.16 kg load; Condition F (I 21 : ASTM D-1238) with a 21.6 kg load; the Melt Flow Ratio (MFR) is equal to I 21 /I 2 . The percentage by weight of comonomers in the copolymer has been determined according to Infra-Red (IR) techniques. The real density has been measured according to the ASTM D-1505 method by deeping of an extruded polymer sample in a density gradient column. The Differential Scanning Calorimetry (DSC) measurements have been carried out on a DSC-7 apparatus of Perkin Elmer Co. Ltd., according to the following procedure. About 10 mg of sample are heated to 180° C. with a scanning speed equal to 10° C./minute; the sample is kept at 180° C. for 5 minutes and thereafter is cooled with a scanning speed equal to 10° C./minute. A second scanning is then carried out according to the same modalities as the first one. Values reported are those obtained in the second scanning. The solubility in xylene at 25° C. has been determined according to the following modalities. About 2.5 g of polymer and 250 ml of xylene are placed in a round-bottomed flask provided with cooler and reflux condenser, kept under nitrogen. This is heated to 135° C. and is kept stirred for about 60 minutes. This is allowed to cool under stirring to 25° C. The whole is filtered off and after evaporation of the solvent from the filtrate until a constant weight is reached, the weight of the soluble portion is calculated. Preparation of the Ligands EXAMPLE 1 Synthesis of 2,3-cyclotetramethyleneindene A mixture of 50 g of benzoic acid (409 mmol) and 35.2 g of cyclohexene (428 mmol) was added to 200 g of polyphosphoric acid (Aldrich). After stirring at 80-90° C. for 3 hours, 300 ml of a saturated solution of ammonium sulphate was added to the reddish brown reaction mixture. The resulting mixture was then extracted three times with 200 ml of dichloromethane. Organic portions were combined and washed succesively with 300 ml of a 5% acqueous solution of ammonium hydroxide and 300 ml of saturated sodium carbonate. The organic layer then was dried over Na 2 SO 4 , concentrated and vaccuum distilled (boiling point 110° C. at 0.1 mmHg) to yield 31.2 g of 2,3-cyclotetramethyleneindan-1-one. 4.0 g of sodium borohydride (107 mmol) was added in portions to a mixture of 20.0 g (107 mmol) of 2,3-cyclotetramethyleneindan-1-one and 40 g (107 mmoli) of CeCl 3 .7H 2 O in 250 ml of methanol. A vigorous gas evolution occurred. After stirring at 40° C. for 3 hours, the reaction crude was neutralised with 10% aqueous HCl. The mixture was then extracted 3 times with 250 ml of ether, dried over Na 2 SO 4 , and concentrate to yield 16.0 g of white solid. The solid product was mixed with 0.16 g of p-toluenesulphonic acid monohydrate in 100 ml toluene and was refluxed at 110° C. After 2 hours the reaction crude was washed successively with 250 ml of a saturated aqueous solution of sodium bicarbonate and 250 ml of water. The organic then was dried over Na 2 SO 4 , concentrated, and vaccuum distilled (b.p. 100° C. at 0.15 mm Hg) to yield 12.86 g of a light yellow liquid, identified as pure 2,3-cyclotetramethyleneindene by its 1 H NMR spectra. A small amount of 1,2-cyclotetramethyleneindene was also detected in the product. EXAMPLE 2 Synthesis of 1,2-cyclotrimethyleneindene A mixture of 116.8 g of benzoic anhydride (513 mmol) and 69.8 g of cyclopentene (513 mmol) was added to 1000 g of polyphosphoric acid (Aldrich). After stirring at 70-80° for 3 hours, a saturated solution of ammonium sulfate (500 ml) was added to the reddish-brown reaction mixture. The resulting mixture was then extracted with dichloromethane (3×300 mL). Organic portions were combined and washed successively with aqueous ammonium hydroxide (5% solution, 500 mL) and saturated sodium carbonate (500 mL). The organic solution was then dried over Na 2 SO 4 , concentrated, and vacuum distilled (b.p. 125° C. at 6 mmHg) to yield 42 g of 2,3-cyclotrimethyleneindan-1-one. 1.06 g of sodium borohydride (28.3 mmol) was added in portions to a mixture of 4.87 g (28.3 mmol) of 2,3-cyclotrimethyleneindan-1-one and 10.6 g (28.3 mmoli) of CeCl 3 .7H 2 O in 250 ml of methanol. A vigorous gas evolutiom occurred. After stirring at 40° C. for 3 hours, the reaction crude was neutralised with 10% aqueous HCl. The mixture was then extracted 3 times with 250 ml of ether, dried over Na 2 SO 4 , and concentrate to yield 4.2 g of white solid. A mixture of the off-white solid above (4.2 g) and p-toluenesulfonic acid monohydrate (0.84 g) in benzene (100 mL) was refluxed at 80° C. After 2 hours, the reaction mixture was washed successively with saturated sodium bicarbonate (100 mL) and water (100 mL). The organic layer was then dried over Na 2 SO 4 , concentrated, and vacuum distilled (b.p. 100° C. at 5 mmHg) to yield 2,3 g of a light yellow liquid, identified as 1,2-cyclotrimethyleneindene by its 1 H-NMR spectrum. EXAMPLE 3 Synthesis of 1,2-cyclohexamethyleneindene A mixture of benzoic anhydride (85.0 g, 376 mmol) and cyclooctene (82.7 g, 751 mmol) was added to polyphosphoric acid (Aldrich, 200 g). After stirring at 80-90° C. for 3 hours, a saturated solution of ammonium sulfate (300 ml) was added to the reddish-brown reaction mixture. The resulting mixture was then extracted with dichloromethane (3×200 ml). Organic portions were combined and washed successively with aqueous ammonium hydroxide (5% solution, 300 ml) and saturated sodium carbonate (300 ml). The organic solution was then dried over Na 2 SO 4 , concentrated, and vacuum-distilled (b.p. 125-130° C. at 0.3 mmHg) to yield 60.5 g of 2,3-cyclohexamethyleneindan-1-one. 4.4 g of sodium borohydride (119 mmol) was added in portions to a mixture of 25.4 g (119 mmol) of 2,3-cyclohexamethyleneindan-1-one and 43.9 g of CeCl 3 .7H 2 O (119 mmol) in 250 ml of methanol. A vigorous gas evolution occurred. After stirring at 40° C. for 3 hours, the reaction crude was neutralized with 10% aqueous HCl, then extracted with Et2O (3×250 ml), dried over Na 2 SO 4 , and concentrated to yield 23.1 g of a white solid. A mixture of the white solid above (23.1 g) and p-toluenesulfonic acid monohydrate (1 g) in benzene (100 ml) was refluxed at 80° C. After 2 hours, the reaction mixture was washed successively with saturated sodium bicarbonate (250 ml) and water (250 ml). The organic layer was then dried over Na 2 SO 4 , concentrated, and vacuum-distilled (b.p. 115° C. at 0.2 mm Hg) to yield 14.6 g of a light yellow liquid, identified as pure 1,2-cyclohexamethyleneindene by its 1 H-NMR. EXAMPLE 4 Synthesis of octahydrofluorene In a 250 ml three neck round bottom flask, equipped with a mechanical stirrer, a thermometer and a reflux condenser 16.276 g of polyphosphoric acid was charged and heated to a temperature of 70° C. 16.276 g of 1-cyclohexenecarboxylic acid and 10.592 g of cyclohexane were added dropwise maintaining a temperature of the reaction mass below 100° C. The mixture was stirred at 78° C. for additional 4.5 hours. The dark brown reaction mass was was poured onto 237 g of ice and neutralised with 89 g aqueous ammonium sulphate solution in 474 g of water. The resulting mixture was then extracted 4 times with 300 ml of petroleum ether and 300 ml of diethyl ether. All organic layers were combined, washed successively with 5% aqueous ammonium hydroxide, brine dried over magnesium sulphate and concentrated in vacuum. Fractional distillation (b.p. 130° C. at 3.0 mmHg) of this crude product yielded 10.294 g of 1,2,3,4,4a,5,6,7,8,9a-decahydro-9H-fluoren-9-one. 1 H-NMR (CDCl 3 ): δ2.73 (q, J=7 Hz, 1H), 2.2-0.5 (m, 17H). A mixture of the above product (4.08 g, 21.47 mmol) and p-toluene-sulfonhydrazide (4.798 g, 25.76 mmol) in absolute ethanol (5 ml) was refluxed for 24.5 hours. The reaction mixture was allowed to cool to room temperature, the solid filtered, washed with absolute ethanol (4×5 ml) and air dried to yield 4.06 g (53%) of 1,2,3,4,4a,5,6,7,8,9a-decahydrofluoren-9-p-toluenesulfonhydrazone, m.p. 160-162° C. 1 H-NMR (CDCl 3 ): δ8.21 (broad d, J=8 Hz, 2H), 7.35 (broad s, 1H), 7.30 (broad d, J=8 Hz, 2H), 2.55 (dd, J=10 Hz, 2.8 Hz, 1H), 2.42 (3H), 2.07-2.04 (m, 4H), 1.9-1.55 (m, 8H), 1.30-1.10 (m, 5H). To a solution of this product (276.5 mg, 0.77 mmol) in Et2O (15 ml) was added 1.65 ml (2.35 mmol) of methyllithium 1.4 M in Et2O under nitrogen at 0° C. The resulting orange reaction mixture was kept at 0° C. for 2 hours and then stirred at ambient temperature for 15.5 hours. A mixture of pentane (15 ml) and water (5 ml) was added. The acqueous layer was extracted with pentane (4×20 ml). All organic layers were combined and concentrated to yield 109.0 mg of octahydrofluorene. 1 H-NMR (CDCl 3 ): δ5.6 (d, J=2.21 Hz, 1H), 2.62-0.8 (m, 17H). EXAMPLE 5 Synthesis of 9-methyl-octahydrofluorene To a solution of 1,2,3,4,4a,5,6,7,8,9a-decahydrofluoren-9-one (90.7 mg, 0.477 mmol) in tetrahydrofuran (5 ml), 0.35 ml (1.05 mmol) of methylmagnesium bromide (3.0 M in Et2O) was added dropwise under nitrogen at −78° C. The resulting cloudy mixture was kept at −78° C. for 3 hours and then allowed to warm to room temperature and stirred for 14 hours. The reaction mixture was acidified with 15% aqueous HCl (5 ml), followed by extraction in Et2O (4×20 ml). All organic layers were combined, washed with water, brine, dried over anhydrous magnesium sulfate, and concentrated in vacuo to give 82.5 mg (92%) of 2,3,4,4a,5,6,7,8-octahydro-9-methyl-1H-fluorene and 1,3,4,5,6,7,8,9a-octahydro-9-methyl-2H-fluorene in the ratio of 3 to 1. 1 H-NMR (CDCl 3 ): δ2.6-0.9 (m), 13C. NMR: 155.77, 136.49, 133.51, 111.70, 61.12, 50.29, 42.14, 29.74, 27.41, 25.46, 25.11, 23.38, 22.81. EXAMPLE 6 Synthesis of tricyclo [6.3.0.0 3,7 ] undeca-1,3(7)-diene A stirred suspension of 1-cyclopentene carboxylic acid (11.2 g, 100 mmol) and cyclopentene (13.6 g, 200 mmol) was added slowly to stirring polyphosphoric acid (Aldrich, 300 g) at 60° C. in a 250 mL flask. The reaction mixture was stirred at 70-80° C. for 4 hours under nitrogen. The dark brown reaction mixture was cooled to 30° C. and poured on 300 g of ice and vigorously stirred in a cooling bath. The brown mass was then neutralized with a saturated solution of ammonium sulfate (200 ml). The resulting mixture was then extracted with Et2O (5×200 mL). The combined organic layers were washed successively with water, saturated sodium bicarbonate solution and water. The washed organic extract was then dried over anhydrous MgSO4 and concentrated in vacuo. The residue was distilled at 130-135° C. at 4 mmHg to yield 3.5 g, 25%, about 90% purity. This product was chromatographed on silica gel using hexane and ethyl acetate as eluent to obtain pure cis-tricyclo[6.3.0.0 3,7 ]undec-1(8)-en-2-one. 1 H-NMR (CDCl 3 ): δ3.2 (m, 1 H), 3.1 (m, 1H), 2.5 (m, 2H), 2.4 (m, 4H), 1.9 (m, 1H), 1.6 (m, 4H), 1.3 (m, 1H). The above enone (1.6 g, 10 mmol) was dissolved in methanol (25 mL) and p-toluenesulfonhydrazide (2.4 g, 12.5 mmol) was added to the solution. The solution was refluxed for 4 hours under nitrogen. The solution was then concentrated in vacuo and the residue dissolved in methylene chloride (25 mL)and to the solution was added hexane (12 mL). The turbid solution was cooled to obtain off-white crystalline hydrazone (2.3 g). 1 H-NMR (CDCl 3 ): δ7.8-7.2 (m, 4H), 3.7-3.0 (m, 1H), 3.3-2.8 (ddd, 1H), 2.3 (3H), 2.2-1.2 (m, 12H). To a solution of the above hydrazone (0.7 g, 2 mmol) in dry THF (10 mL) was added 5 mL of 1.4 M methyl lithium solution in Et 2 O (7 mmol) slowly at −78° C. under nitrogen. The reaction mixture was stirred for 1 hour, then allowed to slowly warm to room temperature and finally stirred for additional 3 hours. The reaction mixture was quenched with saturated ammonium chloride solution (5 mL) and extracted with Et 2 O (20×3 mL). The organic extracts were combined and dried over anhydrous MgSO 4 , concentrated in vacuo and the residue chromatographed on neutral alumina using hexane as eluent to obtain tricyclo[6.3.0.0 3,7 ]undeca-1,3(7)-diene (130 mg). 1 H-NMR (CDCl 3 ): δ5.8 (d, 1H), 3.5-3.1 (m, 1H), 2.9-1.3 (m, 12H). EXAMPLE 7 Synthesis of dimethylbis(2,3-cyclotetramethyleneinden-1-yl)-silane 18.8 ml (2.5M in hexane) of n-butyl lithium was added dropwise to a mixture of 8.0 g (47 mmol) of 2,3-cyclotetramethyleneindene obtained from Example 1 in 100 mL of anhydrous ether at 0° C. The reaction mixture was allowed to stir at room temperature for 3 hours. It was then cooled to 0° C. and 3.0 g (23.5 mmol) of dichlorodimethylsilane was added. After stirring at room temperature for 17 hours, the reaction crude was filtered, concentrated and distilled. The product was crystallised twice in ethanol to yield 3.4 g of product having a melting point of 110-1120C. 1 H-NMR (CDCl 3 ): δ7.60-7.02 (m, 8H), 3.62 and 3.55 (2 broad s, 2H total), 2.80-1.40 (m, 16H), −0.20, −0.30 and −0.32 (3 s, 6H total). EXAMPLE 8 Synthesis of 1,2-bis(1,2-cyclotetramethyleneindenyl)ethane 21.2 ml (2.5M in hexane) of n-butyl lithium was added dropwise to a mixture of 9.0 g (53 mmol) of 2,3-cyclotetramethyleneindene obtained from Example 1 in 100 mL of anhydrous ether at 0° C. The reaction mixture was allowed to stir at room temperature for 3 hours. It was then cooled to −78° C. and 4.68 g (26.5 mmol) of dibromoethane was added. The mixture was warmed to room temperature and stirred for 30 hours. The reaction crude was washed with ammonium chloride, concentrated and distilled to remove any unreacted starting material. The product was then crystallised in ethanol to yield 3.2 g of product having a melting point of 170-173° C. 1 H-NMR (CDCl 3 ): δ7.3-7.0 (m, 8H), 3.15 (broad s, 2H), 2.75-1.2 (m, 20H). EXAMPLE 9 Synthesis of 2-cyclopentadienyl-2-(1,2-cyclotetramethyleneindenyl)propane n-Buthyllithium (2.5 M solution in hexane, 7.5 mmol) was added dropwise to a stirring solution of 2,3-cyclotetramethyleneindene (0.85 g, 5 mmol) in 40 mL THF at 0C. The solution was warmed to room temperature and stirred for an additional 16 hours. Solvents were evaporated and the solids remaining were washed with hexane. The solids were then resuspended in THF and 6,6-dimethylfulvene (Aldrich) was added dropwise at 0° C. to the stirred solution. After the addition was complete, the reaction was allowed to warm to room temperature and stirred an additional 12 hours. The reaction was quenched with a saturated solution of ammonium sulfate, the organic layer was collected and dried over MgSO 4 , then concentrated in vacuo. The oily product was further purified by distillation to remove the starting materials, and a final purification was done by treating the above oil with two equivalents of methyllithium in ether (1.4 M, 10 mmol), collecting the solids and washing away impurities with anhydrous Et2O. A pale yellow powder (1.33 g) was collected and identified by NMR as the dilithium salt of 2-cyclopentadienyl-2-(1,2-cyclotetramethyleneindenyl)propane. Preparation of the Metallocenes EXAMPLE 10 Synthesis of dimethylsilanediyl-bis(2,3-cyclotetramethyleneinden-1-yl)zirconium dichloride 2.2 g (5.5 mmol) of dimethylbis(2,3-cyclotetramethyleneinden-1-yl)silane was dissolved in 100 ml Et 2 O. The temperature was decreased to 0° C. and 8 ml of a 1.4 molar solution of methyllithium in Et 2 O was added dropwise to the stirred solution. After the addition was complete, the solution was warmed to room temperature and stirred for 17 hours. This solution was then cannulated into a stirred flask containing 1.3 g (5.5 mmol) of ZrCl 4 suspended in dry pentane at 0° C. The reaction mixture was then allowed to warm to room temperature and stirred for 8 hours before being filtered. The solids collected on the filter were washed with Et 2 O and pentane prior to being dried in vacuo. 2.58 g of a bright orange powder were obtained, which were further purified by extraction with dichloromethane. The solid, orange product obtained by solvent removal consists of a mixture of racemic and meso (about 1:1) dimethylsilanediylbis(2,3-cyclotetramethyleneinden-1-yl)zirconium dichloride, as shown by its 1 H-NMR spectrum (CDCl 3 ): δ7.7-6.7 (m, 8H), 3.2-1.3 (m, 16H), 1.4, 1.23, 1.1 (3 singlets in about 1:2:1 ratio, 6H total). EXAMPLE 11 Synthesis of dimethylsilanediyl-bis(octahydrofluorenyl)zirconium dichloride 1,749 g of dimethylsilanediyl-bis(2,3-cyclotetramethleneinden-1-yl)zirconium dichloride obtained in Example 10, 105 mg of Pt 2 O and 100 ml of freshly distilled, anhydrous CH 2 Cl 2 were charged in a 250 ml autoclave equipped with a magnetic stirbar and under nitrogen. The nitrogen atmosphere was replaced with 5 bar hydrogen and the mixture was stirred at room temperature for 4 hours. After releasing the pressure, the suspension was filtered under nitrogen, the residue washed with CH 2 Cl 2 until the washings were colourless, the latter reunited to the filtrate, and all volatiles removed in vacuo to leave 1,354 g of a yellow-green solid which was further purified by crystallization from toluene at −20° C., to yield 1,0 g of pure, crystalline dimethylsilanediyl-bis(octahydrofluorenyl)zirconium dichloride as shown by its 1 H NMR (CDCl 3 ): δ2.95-2.7 (m, 4H), 2.65-2.2 (m, 12H total), 2.05-1.3 (m, 16H), 0.85 (s, 6H). EXAMPLE 12 Synthesis of isopropyliden(cyclopentadienyl)(2,3-cyclotetramethyleneinden-1-yl)zirconium dichloride To a flask containing 1.33 g of the dilithium salt of 2-cyclopentadienyl-2-(1,2-cyclotetramethyleneindenyl)propane prepared as described in Example 9, 1.16 g (5 mmol) of ZrCl4 were added. The powders were suspended in fresh pentane and stirred overnight. Solids were collected by filtration and washed with pentane, then dried in vacuo. A light brown powder (1.82 g) was recovered, which was shown to be the title product by 1 H-NMR analysis. EXAMPLE 13 Synthesis of isopropyliden(cyclopentadienyl)(2 3-cyclotetramethyleneinden-1-yl)hafnium dichloride To a flask containing 1.67 g of the dilithium salt of 2-cyclopentadienyl-2-(1,2-cyclotetramethyleneindenyl)propane prepared as described in Example 9, 1.6 g (5 mmol) of HfCl 4 were added. The powders were suspended in fresh pentane and stirred overnight. Solids were collected by filtration and washed with pentane, then dried in vacuo. A yellow powder (2.22 g) was recovered, which was shown to be the title product by 1 H-NMR analysis. Polimerizations Methylaluminoxane (MAO) A commercial product (Schering, MW 1400) was used in solution of 30% by weight in toluene. After having removed the volatile fractions under vacuum the glassy material was finely crushed in order to obtain a white powder that is further treated under vacuum (0,1 mm Hg) for 4 hours at a temperature of 40° C. The so obtained powder shows good flowing properties. Isobutylaluminoxane (TIBAO) The commercial product (Schering) was used as such in a solution of 30% by weight in cyclohexane. Modified methylalumoxane (M-MAO) The commmercial (Ethyl) isopar C. solution (62 g Al/L) was used as received. Preparation of the Catalyst Solution The catalyst solution was prepared by dissolving a known amount of the metallocene in a known amount of toluene, then transferring an aliquot of this solution into a toluene solution containing the desired amount of the cocatalyst, obtaining a clear solution which was stirred for 5-10 min. at ambient temperature and then injected into the autoclave at the polymerization temperature in the presence of the monomer. EXAMPLE 14 Polymerization of ethylene In a Büchi autoclave with a glass body of 11, equipped with a jacket, helic stirrer and thermoresistance, and connected to a thermostat to control the temperature, degassed with a solution of AliBu 3 in hexane and heat dryed under a nitrogen stream, 0.4 l of n-hexane (purified by passing through an alumina column) was added in a nitrogen stream and the temperature was brought to 50° C. A toluene solution containing 0.1 mg of dimethylsilanediylbis(2,3-cyclotetramethyleneinden-1-yl)zirconiumdi chloride prepared as described in example 10 and 0.9 mmol as Al of TIBAO was injected in the autoclave at 50° C. under ethylene flow, the pressure raised to 4 bar, and the polymerization carried out at constant pressure and temperature for 1 hour. 8.5 g of polyethylene were isolated having an intrinsic viscosity of 13.4 dL/g. EXAMPLE 15 Polymerization of ethylene In a 1.35-L jacketed stainless-steel autoclave, equipped with an anchor stirrer and a thermoresistance, connected to a thermostat for temperature control, previously dried at 70° C. under a monomer stream, 45 mg H 2 O and 0.7 L of hexane (purified by passing through an activated alumina column) were charged under a flow of ethylene. The autoclave was then thermostated at 80° C. 5.7 mL of a toluene solution containing 0.56 mg of dimethylsilanediylbis(2, 3-cyclotetramethyleneinden-1-yl) zirconium dichloride prepared as described in example 10 and 5 mmol as Al of AliBu3 was injected in the autoclave through a stainless-steel vial, the pressure raised to 11 bar, and the polymerization carried out at constant pressure and temperature for 1 hour. 17.2 g of polyethylene were isolated having an intrinsic viscosity of 8.2 dL/g. EXAMPLE 16 Polymerization of ethylene The polymerization was carried out as in example 15, but using 90 mg of H 2 O and a catalyst prepared dissolving 1.13 mg of dimethylsilanediylbis(octahydrofluorenyl)zirconium dichloride as prepared in example 11 and 10 mmol as Al of AliBu3 in 11 mL of toluene. 15 g of polyethylene were isolated having an intrinsic viscosity of 2.4 dL/g. EXAMPLE 17 Polymerization of propylene 750 g of propylene were charged in a 2.3-L jacketed stainless-steel autoclave, equipped with stirrer and thermoresistance, connected to a thermostat for temperature control, previously dried at 70° C. in a stream of propylene. The autoclave was then thermostatted at 50° C. 25.8 mL of a toluene solution containing 5 mg of dimethylsilanediylbis(2,3-cyclotetramethyleneinden-1-yl)zirconium dichloride prepared as described in example 10 and 1.04 g of MAO were injected in the autoclave through a stainless-steel vial, and the polymerization carried out at constant temperature for 1 hour. 103 g of atactic polypropylene were isolated having an intrinsic viscosity of 0.26 dL/g. EXAMPLE 18 Oligomerization of propylene 750 g of propylene were charged in a 2.3-L jacketed stainless-steel autoclave, equipped with stirrer and thermoresistance, connected to a thermostat for temperature control, previously dried at 70° C. in a stream of propylene. The autoclave was then thermostatted at 50° C. 25.8 mL of a toluene solution containing 4.6 mg of dimethylsilanediylbis(octahydrofluorenyl)zirconium dichloride prepared as described in example 11 and 1.04 g of MAO were injected in the autoclave through a stainless-steel vial, and the polymerization carried out at constant temperature for 1 hour. 4 g of propylene oligomers were isolated which had an average oligomerization degree of 45. 1 H-NMR analysis showed the oligomers to be about 95% allyl-terminated. EXAMPLE 19 Polymerization of propylene 480 g of propylene were charged in a 1.35-L jacketed stainless-steel autoclave, equipped with stirrer and thermoresistance, connected to a thermostat for temperature control, previously dried at 70° C. in a stream of propylene. The autoclave was then thermostatted at 50° C. 14 mL of a solution containing 7 mg of isopropyliden(cyclopentadienyl)(2,3-cyclotetramethyleneinden-1-yl)zirconium dichloride prepared as described in example 12 and dissolved in 7 mL toluene and 7 mL of M-MAO solution in isopar C. were injected in the autoclave through a stainless-steel vial, and the polymerization carried out at constant temperature for 1 hour. 201 g of polypropylene were isolated which had intrinsic viscosity of 0.61 dL/g, melting point 108.8° C. with a ΔH of 26.4 J/g, and M w /M n =2.29. 13 C-NMR analysis showed that the polymer is prevailingly syndiotactic. EXAMPLES 20-23 Copolymerization of ethylene with 1-butene In a 2.62 1 steel autoclave equipped with blade stirrer, 3.8 mmol of water, 1.26 1 of liquid propane, and the quantities of ethylene, 1-butene and hydrogen indicated in Table 1 were introduced under anhydrous nitrogen atmosphere. The temperature was raised to 45° C., and 5 ml of a toluene solution of 7.7 mmol of triisobutyl aluminium (TIBAL) and the quantity of dimethylsilanylbis(2,3-cyclotetramethyleneinden-1-yl)zirconium dichloride indicated in Table 1, precontacted for 5 minutes in the absence of monomers, was introduced. Thereafter, the temperature was raised to 50° C. and the pressure of ethylene and hydrogen was kept constant for the whole test, carried out under stirring during 2 hours. After removal of the unreacted monomers, the polymer was separated by washing with methanol and drying under vacuum. The polymerization conditions and yields are reported in Table 1. The characterization data of the copolymers obtained are reported in Table 2. EXAMPLES 24-27 (COMPARISON) Copolymerization of ethylene with 1-butene It was worked according to the procedure described in Examples 20-23, but with the difference that dimethylsilanylbis(fluorenyl)zirconium dichloride was used instead of dimethylsilanylbis(2,3-cyclotetramethyleneinden-1-yl)zirconium dichloride, and that the polymerization was carried out at a temperature of 40° C. The polymerization conditions and yields are reported in Table 1. The characterization data of the copolymers obtained are reported in Table 2. By comparing these data with those of the copolymers obtained in Examples 20-23 it clearly appears that, while in these polymerizations the hydrogen has no effect on the molecular weight of the obtained polymers, the use of hydrogen in polymerization reactions carried out with the catalysts according to the invention,even if it is used in low amounts so that the yields of the process are not negatively affected, makes it possible to regulate the molecular weight of the obtained polymers up to Melt Index values of practical interest. EXAMPLES 28-30 Copolymerization of ethylene with propylene In a 4,25 litre autoclave equipped with a stirrer, manometer, temperature indicator, system for loading the catalyst, monomer feed lines and a thermostating jacket, purged with ethylene at 80° C., the amount of propylene and ethylene reported in Table 3 were loaded at room temperature. The autoclave was then brought to a temperature of 5° C. lower than the polymerization temperature. The catalyst solution was prepared as follows. A solution of TIBAO in toluene (0.2 gr TIBAO/ml solution) was added to a solution of dimethylsilanylbis(2,3-cyclotetramethyleneinden-1-yl)zirconium dichloride in toluene (3 ml toluene/mg metallocene). This was maintained under stirring at a temperature of 20° C. for 5 minutes, then the solution was injected into the autoclave under a pressure of an ethylene/propylene mixture in a ratio such to maintain in solution the relative concentrations as reported above. The temperature was then rapidly brought to values required for polymerization. The polymer obtained was isolated by removing non-reacted monomers, and then dried under vacuum. The polymerization conditions, the yields and the characterization data of the copolymers obtained are reported in Table 3. No melting point is detectable at the DSC. analysis. By comparing these data with those of the copolymers of Examples 1-5 of EP-A-632 066, obtained with a catalyst based on dimethylsilanylbis(fluorenyl)zirconium dichloride, it clearly appears that at a parity of comonomer content the intrinsic viscosities of the polymers of EP-A-632 066 are considerably lower than those of the polymers obtained with the catalyst of the invention. TABLE 1 zirconocene Al/Zr 1-butene ethylene H 2 yield activity EXAMPLE (mg) (mol) (ml) (bar) (bar) (g pol.) (Kg pol /g Zr h) 20 4.30 1000 220 17.3 0 172 122.1 21 4.00 1075 220 17.3 0.05 152 116.0 22 4.00 1075 140 18.9 0.06 205 156.4 23 4.00 1075 300 16.4 0.07 206 157.2 24 (COMP.) 6.00 1000 200 16.2 0.03 160 80.2 24 (COMP.) 6.00 1000 160 16.7 0.13 265 132.8 25 (COMP.) 6.00 1000 170 17.3 0.74 125 62.6 26 (COMP.) 6.00 1000 190 18.3 2.06 15 7.5 TABLE 2 Melt Index DSC xylene [η] I 2 I 21 1-butene density Tm(II) ΔH f soluble EXAMPLE (dl/g) (g/10′) (g/10′) MFR (w %) (g/ml) (° C.) (J/g) M 2 M n (w %) 20 1.91 n.d.  7.5 n.d. 10.7 0.9051 93 57 n.a. n.a. 21 1.78 0.57 16.5 28.9 11.1 0.9030 95 73 3.6 3.6 22 1.65 1.10 31.0 28.2  9.1 0.9165 106  88 3.6 n.a. 23 1.48 2.82 68.1 24.1 17.1 0.9026 88 57 n.a. 15.7  24 (COMP.) 3.66 n.d. n.d. n.d. 13.0 0.8940 78 23 n.a. n.a. 25 (COMP.) 4.45 n.d. n.d. n.d.  9.7 0.9100 92 73 2.9 n.a. 26 (COMP.) 3.82 n.d. n.d. n.d. 13.0 0.9032 92 77 n.a. 0.2 27 (COMP.) 3.09 n.d. n.d. n.d. n.a. n.a. n.a. n.a. n.a. n.a. n.d. = not determinable n.a. = not available TABLE 3 Zr C 2 liq. (mmols. Al/Zr phase P tot. T time yield activity C 2 units I.V. EXAMPLE 10 −3 ) (mol) (wt %) (bar) (° C.) (min) (g) (Kg pol /g Zr ) (wt %) (dl/g) 28 4.31 2610 20.00 29.3 40 120 48 849.4 48.0 2.04 29 4.31 2610 29.00 35.3 40 120 56 941.0 56.1 2.44 30 4.31 2610 34.14 32.0 30 120 80 658.7 64.7 3.07

A class of bridged or unbridged metallocene compounds is disclosed, wherein the cyclopentadienyl ligands have two or four adjacent substituents forming one or two alkylenic cycles of from 4 to 8 carbon atoms. These metallocenes are useful as catalyst components for the polymerization of olefins, particularly for the (co)polymerization of ethylene and for the polymerization of propylene.

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a candle structure, having a decorative animated sculpture, that is housed in a vented container that enhances the animated motion. More particularly the invention is directed to a candle housed in a vented container and a fan driven by rising heat from the burning candle. [0003] 2. Discussion of Related Art [0004] The fundamental concepts and processes for making candles are well known. Candles typically have both utility and ornamental appeal. For example, the warm glow of a candle may provide light and heat. A scented candle may also provide a scent or an aroma and may mask odors, and a candle may generally serve as a decorative device. However, it is desirable to develop new ways of imparting novel, functional and aesthetically pleasing characteristics to the basic candle structure. U.S. patent application Publication No. 20020066687, for example, discloses a container with a lid comprising a decorative member which is a sports-related item, wherein the container may hold candles. U.S. Pat. No. 5,032,360 discloses an apparatus comprising a base with a candle mounted on it, and a container open at both ends located above the candle, wherein the container houses activated charcoal to filter odor-filled air. [0005] The present invention further addresses the need to provide new functional and aesthetically pleasing characteristics to known candle structures. SUMMARY OF THE INVENTION [0006] The present invention provides for a candle structure having a decorative animated sculpture. The candle itself is housed in a vented container. At least one fan is mounted on the container above the candle, wherein heated air generated by and rising from the candle may continuously drive the fan. The fan may further serve to distribute the heat, and the scent or aroma generated by the candle. The fan may also serve to impart a new and aesthetically pleasing characteristic to the basic candle structure by carrying a decorative sculpture that rotates with it. The vents in the container permit air to readily reach the candle to aid in combustion of the candle fuel, and to enhance the flow of thus heated rising air to drive the fan. [0007] In accordance with one aspect, the present invention is directed to a candle structure having a container comprising a hollow body with a bottom wall, with the hollow body defining an opening opposite the bottom wall, the container further comprising a cover or lid that can be removably mounted on the opening in the hollow body. The container further houses a candle, and is formed with at least one side vent or opening. The lid comprises at least one top vent or opening at a point where the lid is mounted on the opening in the hollow body. At least one fan is mounted on the lid on a bearing to permit it to be driven to rotate by rising heated air from the burning candle. The hollow body, lid and fan may further incorporate decorative elements. For example, a decorative sculpture may be mounted on the fan to be rotated with it. The candle may further comprise decorative elements, and/or a scent. [0008] Thus, in accordance with this aspect, when the candle is lit, the surrounding air is heated, and the heated air rises and drives the fan. The air that aids combustion of the candle fuel can be readily replenished by unheated air drawn into the container through the vents in the hollow body, and vents in the lid, producing a “chimney-like” effect. In accordance with this aspect, the fan may further serve to distribute the scent and the heat from the candle. [0009] In accordance with another aspect, the present invention is directed to a candle structure having a container comprising a hollow body with a bottom wall, with the hollow body defining an opening opposite the bottom wall. The container is provided a cover or lid that can be removably mounted on the opening in the hollow body. The container further houses a candle, and is formed with at least one side vent or opening within the hollow body. At least one fan can be mounted through a bearing on the lid. The hollow body, lid and fan may incorporate decorative elements. The candle may further have decorative elements, and/or a scent. [0010] In accordance with this aspect, when the candle is lit, the surrounding air is heated, and the heated air rises and drives the fan. The air that aids combustion of the candle fuel is readily replenished by unheated air drawn into the container through the vents in the hollow body, again by a “chimney-like” effect. In accordance with this aspect, the fan may further serve to distribute the scent or heat from the candle. Movement of the fan may also move decorative elements. [0011] In accordance with yet another aspect, the present invention is directed to a candle structure having a container comprising a hollow body with a bottom wall, with the hollow body defining an opening opposite the bottom wall. The container carries a lid that can be removably mounted on the opening in the hollow body. The hollow body is formed with at least one side vent or opening within the hollow body. The lid is formed to provide at least one top vent or opening at a point where the lid is mounted on the opening in the hollow body. At least one fan can be carried for rotation on a bearing mounted with the lid. The hollow body, lid and fan may also incorporate decorative elements. [0012] In accordance with this aspect, when a candle is mounted in the vented container and lit, the surrounding air is heated, and the heated air rises and drives the fan to rotate. The air within the container is replenished by unheated air drawn into the container through the vents in the hollow body, and vents in the lid. In accordance with this aspect, the fan may also distribute scent and heat from the candle, and the fan can drive decorative elements carried on it. [0013] An advantage of the present invention is that the vents allow for continuous replenishment of the air within the container, thereby providing a continuous source of heated air to drive the fan and any decorative elements attached thereto. Another advantage of the present invention is that the rotating fan may distribute heat and scent generated by the burning candle. BRIEF DESCRIPTION OF THE DRAWINGS [0014] The foregoing and other aspects of the present invention will best be appreciated with reference to the detailed description of the invention taken in conjunction with the accompanying drawings, wherein: [0015] [0015]FIG. 1 is a perspective view of an exemplary embodiment of the candle structure having a container carrying at least one fan, in accordance with the present invention. Both the hollow body and the lid are formed with at least one vent, and decorative elements have been added to both the fan and the lid. [0016] [0016]FIG. 2 is an exploded perspective view of an exemplary embodiment of the candle structure, in accordance with the present invention, wherein the lid has been removed. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS [0017] The present invention is directed to a candle structure having an advantageously vented container and comprising at least one fan, wherein the heated air generated by a burning candle in the container may continuously drive the fan to rotate. The vents serve to continuously replenish the air in the container to aid combustion of the candle fuel. The fan may further serve to distribute the heat and the aroma generated by the candle. The fan may also serve to impart a new and aesthetically pleasing characteristic to the basic candle structure by concurrently rotating decorative elements mounted on it. [0018] While the present invention may take the form of a number of exemplary embodiments, for ease of explanation, one such embodiment will be described in detail. [0019] Referring to the figures, wherein like numerals indicate the same element throughout the views, there is shown in FIG. 1 a candle structure including a vented container 10 , comprising a hollow body 20 with a bottom wall 30 and a side wall 32 . As shown, the body is generally cylindrical, but, of course, may take other shapes. At least one and preferably a large number, such as eight, side vents 35 are formed in the side wall 32 of the hollow body 20 . [0020] As illustrated in FIG. 2, the hollow body 20 also defines a top opening 40 opposite the bottom wall 30 . [0021] The candle structure including a vented container 10 further comprises a cover or lid 50 that can be removably mounted in the opening 40 . The lid 50 includes a side wall 55 that also is generally cylindrical. However, the side wall 55 of the lid may take other shapes, such as one which matches that of the hollow body. The lid side wall 55 supports a frame 57 that includes a number of radially extending legs 59 that are joined at the central vertical axis of the lid. A needle 61 , which is one component of a needle bearing, is mounted on the junction of the legs 59 of the frame 57 to project upwardly substantially along the axis of the lid, and thus the hollow body 20 , when the lid 50 is mounted on it. [0022] As shown in FIG. 1, the lid 50 also includes a lightweight fan 65 having a number of blades 66 and a needle bearing socket 68 at its center that receives the needle 61 mounted on the legs 59 , as illustrated in FIG. 2. [0023] As illustrated in FIG. 1, the candle structure including a vented container 10 further comprises at least one top vent 80 at the location where the lid 50 is mounted in the opening 40 . As illustrated in FIG. 2, in this exemplary embodiment, the top vents 80 are formed by at least three feet 85 attached to the bottom 56 of the side wall 55 of the lid 50 . When the lid 50 is placed in the opening 40 of the hollow body 20 , the feet 85 elevate the lid 50 above the hollow body 20 , thereby creating the top vents 80 . [0024] As illustrated in FIG. 2, the candle structure 10 further comprises a candle 100 with a bottom portion 110 and a top portion 120 , wherein the bottom portion 110 of the candle 100 is substantially in contact with the bottom wall 30 of the hollow body 20 . The top portion 120 of the candle 100 comprises at least one wick 150 . The candle may further comprise an aroma or a scent. The candle structure 10 may further comprise a written message of the outer surface of the candle 100 , the hollow body 20 , and/or the lid 50 . [0025] As illustrated in FIG. 2, when the wick 150 in the top portion 120 of the candle 100 in the candle structure 10 is lit, the heated air generated around the flame rises, and is constantly replenished by ambient air drawn into the candle structure 10 , through the side vents 35 , and the top vents 80 . The rising hot air propels the fan 65 , on the lid 50 , as illustrated in FIG. 1. The fan 65 may then distribute the heat, and the scent or aroma generated by the candle, thereby generating a functional and aesthetically pleasing result. [0026] The hollow body 20 and the bottom wall 30 may be made in any suitable shape and/or configuration, and may be made from any suitable material, such as non-flammable plastic or glass. The hollow body 20 may be made in any suitable color or transparency, and is preferably clear. The hollow body 20 may comprise suitable decorative elements. The side vent 35 may be made in any suitable shape or configuration and is preferably round or oval. The side vent 35 may be of any suitable size, and is preferably of sufficient size to allow adequate replenishment of combustion air to the container. The opening 40 opposite the bottom wall 30 of the hollow body 20 may be of any suitable size, shape or configuration, and does not need to conform to the size, shape or configuration of the bottom wall 30 . [0027] The lid 50 may be of any suitable size, shape, configuration, color or transparency, and may comprise suitable decorative elements. The lid 50 may be made of any suitable material, and is preferably made of a non-flammable material. The fan 65 may be of any suitable configuration, and may comprise a number of different decorative elements. The top vent 80 is of any suitable shape or configuration, and is preferably also of sufficient size to allow adequate replenishment of the combustion air in the container. The top vents 80 may be created in any suitable manner, and may preferably be created by attaching feet 85 to the bottom 56 of the side wall 55 of the lid 50 . [0028] The candle 100 also can be made in any suitable configuration, including cylindrical, circular, quadrilateral and polygonal, and in any variation thereof, and is preferably cylindrical, which configuration is also known as a pillar candle or column candle. The candle 100 can be made from known materials, and is preferably made from wax or paraffin. The candle may comprise means for evenly or selectively melting the candle, such as the positioning of the one or more wicks 150 within the candle 100 , or this may be achieved by the composition of the candle 100 itself. [0029] Although shown and described are what are believed to be the preferred embodiments of the candle in accordance with the invention, it is apparent that departures from specific designs and methods described and shown will suggest themselves to those skilled in the art and may be used without departing from the spirit and scope of the invention. The present invention is not restricted to the particular constructions described and illustrated, but should be constructed to encompass all modifications that may fall within the scope of the following claims.

A candle structure comprises a fan, wherein the heated air generated by a candle may propel the fan. The candle is housed in a container having a bottom wall and a side wall. The side wall is formed with vents located above the candle so that adequate air needed to permit the candle to combust can be drawn through the vent, thereby to enhance propulsion of the fan. The fan serves to impart a new functional and aesthetically pleasing characteristic to the basic candle structure by distributing the heat and the scent generated by the candle, while concurrently rotating decorative elements.

TECHNICAL FIELD OF THE INVENTION [0001] The present invention relates to audiotext systems designed to provide full access to traditional databases and telecommunications systems, such as local area networks, the Internet, other external databases, telephones and fax machines, etc., and more specifically to audiotext personal ad services. BACKGROUND OF THE INVENTION [0002] Audiotext personal ad services are a popular way for people to meet, and are available in most newspapers and on many cable television systems. In a typical service, an advertiser calls a live operator and places a text personal ad. An advertiser then calls an audiotext system and records an audio message, often referred to as a greeting, which expands upon the advertiser's text ad by describing in more detail the advertiser and the type of person he is seeking. Personal ads are then published in a newspaper. A personal ad includes a 900 telephone number and an ad mailbox number permitting a caller to listen to an advertiser's voice greeting. A caller can respond to an ad by recording a reply voice mail message for the advertiser. An advertiser retrieves a message by calling the audiotext system and entering a password given at the time of ad placement. In another format, live operators are not used. Instead, an advertiser first records an audio greeting via a telephone. An operator then listens to the audio greeting off-line and writes a text summary of the audio greeting for publication in the newspaper. [0003] With the expansion of the Internet and other on-line services, personal ad services have been created to take advantage of this new medium. A typical service allows an advertiser to place a text personal ad that is published on the Internet on an HTML (HyperText Markup Language) page. An Internet user may respond to a personal ad by sending an advertiser a message via electronic mail. The limitation of this approach is that an Internet user cannot listen to an audio recording of an advertiser, a feature that is the central to audiotext personal ad services. Another limitation is that many people do not have Internet access, thus limiting the number of advertisers and respondents. [0004] In another format, an attempt is made to integrate audiotext personal ad services with the Internet. Using this approach, personal ads are published in both the newspaper and on the Internet. Each personal ad includes a 900 telephone number and an ad mailbox number permitting a caller to listen to an advertiser's voice greeting. This approach still has the disadvantage of not allowing an Internet user to listen to an advertiser's voice greeting via the Internet. Moreover, an Internet user can only respond to a personal ad via a telephone because this approach does not allow Internet users to exchange messages with telephone users. [0005] To summarize, existing Internet personal ad services are limited in that they lack many of the features available on audiotext personal ad services. Also, existing personal ad services do not provide a means for those using an audiotext personal ad service to effectively communicate with those using an Internet personal ad service and vice versa. Therefore, there is a need for a personal ad system that seamlessly integrates an audiotext system with an Internet server, allowing straightforward communication between those using a telephone and those using the Internet. Such a system has been disclosed in detail by the applicant in pending application Ser. No. 08/744,879. However, there still remains the need to address some of the problems inherent in an integrated audiotext and Internet based personal ad service. [0006] A basic problem is that when a person responds to a personal ad via a telephone, she must give the advertiser a way to be contacted. Similarly, when a person responds to a personal ad via the Internet, she must also give a way to be contacted. This typically consists of leaving a telephone number, street address, or electronic mail address. Many people are reluctant to give out this information to the advertiser. They prefer to be able to communicate anonymously with an advertiser until they are comfortable with giving out contact information. Therefore, the need arises for a system that allows respondents to instantaneously create a private mailbox at the point of responding to an ad. This feature must also support seamless communication between telephone users and Internet users. SUMMARY OF THE INVENTION [0007] The present invention allows telephone users to create a mailbox at the point of responding to an ad, regardless of whether the ad originated on the telephone or on the Internet. Similarly, Internet users can create a mailbox at the point of responding to a personal ad on the Internet, regardless of whether the ad originated on the telephone or via the Internet. By giving both advertisers and respondents a mailbox, they can communicate anonymously with each other until one or both are comfortable with giving out a means of contact. Moreover, said communication can occur regardless of whether a user is on a telephone or on the Internet. This useful feature provides additional safety to users of personal ad systems while preserving the ability for telephone users to seamlessly communicate with Internet users. The significant advantages provided by the present invention are apparent from the above description. BRIEF DESCRIPTION OF DRAWINGS [0008] For a more complete understanding of the present invention, reference is made to the following drawings, in which: [0009] FIG. 1 shows a schematic representation of the present invention. [0010] FIG. 2 shows a table of the fields used for storing personal data, including a brief description of the particular fields. [0011] FIG. 3 shows a table of the fields used for storing greetings data, including a brief description of the particular fields. [0012] FIG. 4 shows a table of the fields used for storing response data, including a brief description of the particular fields. [0013] FIG. 5 shows a table of the fields used for storing response data, including a brief description of the particular fields. [0014] FIG. 6 shows a flow diagram of an exemplary operation of the present invention, more specifically placing an ad through a telephone. [0015] FIG. 7 shows a flow diagram of an exemplary operation of the present invention, more specifically placing an ad through the Internet. [0016] FIG. 8 shows a flow diagram of an exemplary operation of the process of notifying an existing advertiser of new matches as accomplished by the present invention. [0017] FIG. 9 shows a flow diagram of an exemplary operation of the process of advertiser matching through a telephone as accomplished by the present invention. [0018] FIG. 10 shows a flow diagram of an exemplary operation of the process of advertiser matching through the Internet as accomplished by the present invention. [0019] FIG. 11 shows a flow diagram of an exemplary operation of the process of reviewing and summarizing ads as accomplished by the present invention. [0020] FIG. 12 shows personal ads as they would appear in a local newspaper. [0021] FIG. 13 shows a flow diagram of an exemplary operation of the process of responding to an ad through a telephone as accomplished by the present invention. [0022] FIG. 14 shows a flow diagram of an exemplary operation of the process of responding to an ad through the Internet as accomplished by the present invention. [0023] FIG. 15 shows a maximized personal ad as seen by the Internet user who chooses to expand the ad to full-page size. [0024] FIG. 16 shows a flow diagram of the response confirmation process, including the Response Confirmation Form which gives the Internet user instructions on how to enhance a response to an ad with, audio, video or a photograph. [0025] FIG. 17 shows a flow diagram of an exemplary operation of the process of notifying an advertiser of a response as accomplished by the present invention. [0026] FIG. 18 shows a flow diagram of an exemplary operation of the process of retrieving responses through a telephone as accomplished by the present invention. [0027] FIG. 19 shows a flow diagram of an exemplary operation of the process of retrieving responses through the Internet as accomplished by the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT [0028] As required, a detailed illustrative embodiment of the present invention is disclosed herein. However, telephone techniques, physical communication systems, data formats and operating structures in accordance with the present invention may be embodied in a wide variety of forms and modes, some of which may be quite different from those in the disclosed embodiment. Consequently, the specific structural and functional details disclosed herein are merely representative, yet in that regard, they are deemed to afford the best embodiment for purposes of disclosure and to provide a basis for the claims herein which define the scope of the present invention. [0029] Referring initially to FIG. 1 , a series of remote telephone terminals T 1 -Tn are represented. In addition, a series of remote computer terminals CT 1 -CTn are represented. The indicated terminals T 1 -Tn represent the multitude of telephone terminals existing in association with the public telephone network (PTN). The indicated computer terminals CT 1 -CTn represent the multitude of computer terminals connected to the Internet. [0030] The PTN, which accommodates the individual terminals T 1 -Tn, is coupled to an Interactive Voice Response System (IVR). The Internet, which accommodates individual computer terminals CT 1 -CTn, is coupled to an Internet Web Server (IWS). Individual callers use the individual telephone stations T 1 through Tn to interface the IVR through the PTN. Individual users at computer terminals CT 1 through CTn use the Internet to interface the IWS. Telephone callers and Internet users may record digital audio messages that can be listened to from any of the remote telephone terminals T 1 -Tn or from any of the remote computer terminals CT 1 -CTn. Internet users may also leave digital text messages that may be accessed from any of the remote telephone terminals T 1 -Tn using text to speech or from the remote computer terminals CT 1 -CTn via computer monitor. [0031] Considering the system of FIG. 1 in somewhat greater detail, it is to be understood that the PTN has multiplexing capability for individually coupling the terminals T 1 -Tn to the IVR on request. In the illustrative embodiment of the system, the individual terminals T 1 -Tn take the form of existing traditional or conventional telephone instruments. It is also to be understood that the Internet has the capability for individually connecting the computer terminals CT 1 -CTn to the IWS. In the illustrative embodiment of the system, the individual computer terminals CT 1 -CTn take the form of personal computers that comprise a central processing unit CPU, modem, monitor, keyboard, hard drive, sound card, speakers, and microphone. [0032] Considering the IVR in somewhat greater detail, the PTN is coupled to an IVR as shown in FIG. 1 . In the disclosed embodiment, from the PTN, forty-eight lines are connected to the IVR and, accordingly, the IVR may accommodate up to forty-eight simultaneous calls from the public telephone network PTN. The IVR contains a processor, an exemplary form of which is an Intel 166 MHz Pentium Processor. The forty-eight lines from the PTN are connected to the processor though an interface 15 , an exemplary form of which is a series of commercially available Dialogic (D240SC-T1) cards. The interface incorporates modems, tone decoders, switching mechanisms, Dialed Number Identification Service (DNIS) and Automatic Number Identification (ANI) capability. The Dialogic card stores audio information in the Dialogic .VOX format. [0033] Generally, DNIS capability is a function of the PTN to provide digital data indicating the called number. ANI capability is a similar function whereby the digital data indicates the calling number. [0034] Considering the IWS in somewhat greater detail, the IWS is coupled to the Internet via a DS 1 line to a local Internet provider service. The IWS may accommodate a multitude of simultaneous Internet users. As represented, the IWS is a micro computer programmed for Internet information server operations. The IWS contains a processor and Internet server software, exemplary forms of which are an Intel 166 Mhz Pentium Processor and Microsoft Internet Information Server software. [0035] The IWS is also loaded with RealAudio Server software from Progressive Network. RealAudio allows a Microsoft Windows .WAV file to be converted into a RealAudio .RA file, a compressed format that allows play back over the Internet in real time, as opposed to first downloading a file and then listening to it. RealAudio accomplishes this by playing an audio file while it is still downloading, using a process called data streaming. [0036] The IWS is also loaded with VDOLive Server software. VDOLive allows a video clip in the Microsoft Windows AVI, Apple Quicktime, or MPEG video file formats to be converted into a VDOLive .VDO format, a compressed format that allows play back over the Internet in real time, as opposed to first downloading a file and then listening to it. VDOLive also utilizes data streaming. [0037] The IVR and the IWS are coupled to a Database Server (DBS) via an Ethernet hub as shown in FIG. 1 . The system includes one or more Operator Workstations OW 1 -OWn, through which an operator can interact with and control the DBS, IVR and IWS. [0038] The DBS is a computer programmed for database operations. In the illustrated embodiment, the DBS manages a personal Ad Database which is comprised of multiple tables that manage ad creation, the audio greeting files, ad response files, photograph and video files. The Ad Database comprises an electronic equivalent of the personal classified ads placed via telephone and the Internet, and responses placed to ads. [0039] The IVR converts audio files received via telephone into the RealAudio .RA format for real time retrieval via the Internet. Conversely, the IWS converts audio files received via the Internet into Dialogic .VOX files for retrieval via telephone. Audio file conversions are done through audio file conversion software, an exemplary form of which is Sound Forge by Sonic Foundry. [0040] The DBS contains a processor and an SQL (Structured Query Language) relational database software, exemplary forms of which are the Intel 166 Mhz Pentium Processor and Microsoft SQL Server. [0041] The Operator Workstation (OW) is a conventional personal computer equipped with a sound card capable of playing the audio data and a video display capable of displaying digitally stored photographs and videos. An exemplary form of the OW is a microcomputer equipped with an Intel 166 Mhz Pentium Processor and a Creative Labs Sound Blaster sound card. Operators review all incoming advertiser files—text, audio, photograph, and video—to insure that their content is appropriate. Also, operators use advertisers' text messages and audio recordings to create summary text ads for publication in a newspaper. [0042] The following sections describe in greater detail the interaction between the IVR, the DBS, the IWS, and the OW. [0000] Placing an Ad Through a Telephone [0043] An exemplary operation of the system of the present invention, with regard to a specific telephone caller placing a personal advertisement will now be treated to accomplish the process as indicated in FIG. 6 . First, suppose a telephone caller at terminal T 1 makes a call to place a personal advertisement in response to an advertisement in XYZ newspaper. The assumed call involves the telephone caller actuating the buttons to input the number 1 800 555 3333, for example. As a result, signals are provided to the public telephone network resulting in a connection from the remote terminal T 1 to the IVR. Using standard DNIS techniques, the IVR associates the called number 1 800 555 3333 with a specific format, for example, a voice personals ad taking format. [0044] The caller is first prompted to create a profile of himself by answering a series of questions using the buttons on his touch tone phone. The profile contains data on the advertiser and the type of person the advertiser wishes to meet. Referring initially to FIG. 6 and FIG. 2 , upon receiving a call, the IVR cues the caller to enter his telephone number 801 . The IVR stores the telephone number 802 in the field AD_PHONE 203 . Next, the IVR cues the caller to enter his gender 803 . For example: “If you are a woman, press 1. If you are a man, press 2.” The IVR stores the caller's gender 804 in the field AD_GENDER 207 . Next, the IVR cues the caller for his marital status 805 . For example: “If you are single, press 1. If you are divorced, press 2. If you are widowed, press 3.” The caller responds' and the IVR stores the caller's marital status 806 in the field AD_MARITAL_STATUS 208 . Next, the IVR cues the caller for his age 807 . For example: “Please enter your age.” The caller's age is then stored 808 in the field AD_AGE 209 . [0045] Next, the caller is prompted to indicate the type of person he wishes to meet. The IVR first cues the caller for the martial status of the person he is seeking 825 . For example: “If you wish to meet someone who is single, press 1. If you wish to meet someone who is divorced, press 2. If you wish to meet someone who is widowed, press 3.” The martial status sought is then stored 826 in the field AD_MARITAL_SOUGHT 212 . Next, the IVR cues the caller to enter the lowest age of the person he wishes to meet 827 . For example: “Please enter the lowest age of the person you wish to meet.” The low age sought is them stored 828 in the field LOW_AGE_SOUGHT 213 . Finally, the IVR cues the caller to enter the highest age of the person he wishes to meet 829 . For example: “Please enter the highest age of the person you wish to meet.” The high age sought is then stored 830 in the field HIGH_AGE_SOUGHT 213 . It is to be understood that the actual questions asked about the caller and the person he is seeking are merely illustrative. The actual questions could vary greatly in both number and kind. [0046] Next, the IVR cues the caller to record an audio greeting 812 . The advertiser's audio greeting is then stored to a disk file on the IVR 813 and the Ad Database is updated 809 . Specifically, the AD_REVIEW_FLAG 210 in the AD_PERSONAL_TABLE of FIG. 2 is set to FALSE indicating that the ad must be reviewed by an operator. In addition, a new record is created in the AD_GREETINGS_TABLE of FIG. 3 and the field GR_REVIEW_FLAG 303 set to FALSE to indicate that the audio greeting has not been reviewed. In the new record, the fields GR_MAILBOX_NUMBER 301 , GR TYPE 302 , GR_FILENAME 304 , GR_DATE_TIME 305 in the AD_GREETINGS_TABLE of FIG. 3 are also populated to indicate the advertiser's mailbox number, the format of the audio file, the location of the audio file on the IVR, and the date and time the greeting was recorded. The field GR_TYPE is set to VOX to indicate that the audio recording is in the Dialogic .VOX file format. Finally, the field GR_CONVERSION_FLAG 506 is set to FALSE to indicate that the audio file must be converted from the Dialogic .VOX format to create a new audio file in the RealAudio RA format for playback on the Internet. [0047] The IVR then cues the caller to indicate if he wishes to record an e-mail address 816 . For example: “Press 1 to input an e-mail address. Press 2 to decline.” If the caller elects to leave an e-mail address, the IVR cues the caller to record his e-mail address 817 . The audio recording is stored to a disk file on the IVR 818 and the field AD_EMAIL_FILENAME 205 in AD_PERSONAL_TABLE of FIG. 2 is set, indicating that an e-mail audio file exists and its location on the IVR. [0048] Next, the IVR assigns the advertiser a five digit mailbox number 819 . For example: “Your 5-digit mailbox number is 12345.” The mailbox number is then stored 820 in the field AD_MAILBOX_NUMBER 201 . The IVR then cues the caller to enter a five digit password 821 , and the password is stored 822 in the field AD_PASSWORD 202 . [0049] In addition, the IVR stores the date the ad is taken in the field AD_DATE_TIME 206 , and updates the field AD_ORIGIN 211 to indicate that the personal ad originated on the telephone 823 . Finally, the IVR creates an electronic mailbox for the advertiser on the IWS 824 , using the mailbox number stored in the field AD_MAILBOX_NUMBER 201 as the electronic mailbox address, to allow respondents to submit audio, video and photographic files in response to the advertiser's ad. [0050] Finally, the IVR queries the Ad Database to determine if there are other existing advertiser's whose profile matches that of the new advertiser 831 . More specifically, there is a match if the values in the field AD_MARITAL_STATUS 208 and the values in the field AD_MARITAL SOUGHT 212 match for each ad, and if the value in the field AD_AGE 209 for each ad is within the range of values in the fields AD_LOW_AGE_SOUGHT 213 and AD_HIGH_AGE_SOUGHT 214 for the other ad. If the query finds one or more ads that match, the IVR speaks the number of matching ads to the caller 832 . For example: “The number of ads that match your preferences is 5.” The caller is then given both a 900 number 833 and an Internet address 834 that can be used to retrieve the matches, and the call is terminated 835 . If no matches are found, the call is terminated 835 . [0051] In addition, the mailbox numbers of matching ads are placed in a notification queue 835 , together with delivery information corresponding to the matching ad so that the existing advertisers can be notified that a new personal ad has come onto the system that matches the existing advertisers' profile. The delivery information includes the telephone number and e-mail address, if available, of the existing advertiser to be notified, together with mailbox number of the new ad coming onto the system. [0000] Placing an Ad Through the Internet [0052] An exemplary operation of the system, with regard to a specific Internet user placing a personal advertisement will now be treated to accomplish the process as indicated in FIG. 7 . First, suppose a Internet user at terminal CT 1 connects to the Internet to place a personal advertisement in response to an advertisement in XYZ newspaper. The assumed Internet user connects to the Internet and inputs a Uniform Reference Locator (URL), for example: http://www.personal_ads.com, resulting in a connection from the remote terminal CT 1 to a Home Page 1001 on the IWS. Referring to FIG. 7 , from the Home Page 1001 on the IWS, the Internet user selects an Ad Placement Form 1002 . The Ad Placement Form 1002 contains the following input fields corresponding to fields in the Ad Database as indicated: Gender 1003 AD_GENDER 207 Marital Status 1004 AD_MARITAL_STATUS 208 Age 1005 AD_AGE 209 Martial Sought 1034 AD_MARTIAL_SOUGHT 212 Low Age Sought 1035 AD_LOW_AGE_SOUHT 213 High Age Sought 1036 AD_HIGH_AGE_SOUGHT 214 E-mail address 1006 AD_EMAIL_ADDRESS 204 Phone Number 1007 AD_PHONE 203 Password 1008 AD_PASSWORD 202 Greeting Text 1014 GR_FILENAME 304 [0053] This process largely parallels the process of placing a personal ad via a telephone. The password 1008 is used by the advertiser to retrieve messages and the e-mail address 1006 and telephone number 1007 are used to contact the advertiser. The gender 1003 , age 1005 , and marital status 1004 fields create a profile of the advertiser. The marital sought 1034 , low age sought 1035 and high age sought 1036 fields complete the advertiser's profile by indicating the type of person the advertiser wishes to meet. Finally, the field Greeting Text 1014 comprises the advertiser's text personal ad. [0054] The Internet user completes the Ad Placement Form 1002 and presses the “Submit” button to submit her ad. The form is checked by the IWS for completeness 1016 . If the form is incomplete, the user is returned to the Ad Placement Form 1002 . If the form is complete, the IWS updates the Ad Database 1017 . This includes assigning the user a five digit mailbox number and storing it in the field AD_MAILBOX_NUMBER 201 . In addition, the advertiser's profile, contact information, password and greeting are added to the Ad Database. Also, the advertiser's text greeting is stored to a disk file on the IWS. Next, the AD_REVIEW_FLAG 210 in the AD_PERSONAL_TABLE of FIG. 2 is set to FALSE indicating that the ad must be reviewed by an operator 10 , a new record is created in the AD_GREETINGS_TABLE of FIG. 3 , and the field GR_REVIEW_FLAG 303 is set to FALSE to indicate that the text greeting has not been reviewed. In the new record, the fields GR_MAILBOX_NUMBER 301 , GR_TYPE 302 , GR_FILENAME 304 , GR_DATE_TIME 305 in the AD_GREETINGS_TABLE of FIG. 3 are also populated to indicate the advertiser's mailbox number, the file format, the location of the text file on the IWS, and the date and time the greeting was placed. Specifically, the field GR_TYPE is set to TEXT. Finally, the field GR_CONVERSION_FLAG is set to TRUE to indicate that the text does not need to be converted to a different format. [0055] Next, the IWS queries the Ad Database to determine if there are other existing advertiser's whose profile matches that of the new advertiser 1018 . The IWS then creates an Ad Confirmation Page 1020 . If the query finds one or more ads that match, the Ad Confirmation Page displays a text message of the number of matching ads 1027 . The text message is displayed as a hyper-link which can be followed by a browser to the actual matching ads. In addition, the Ad Confirmation Page 1020 confirms the advertiser's mailbox number 1021 , and gives the advertiser an e-mail address to submit an audio greeting 1022 , photograph 1023 , or video clip 1024 for inclusion with her personal ad. Also, the Internet Web Server stores the date and time the ad is taken in the field AD_DATE_TIME 206 , and updates the field AD_ORIGIN 211 to indicate that the personal ad originated on the Internet 1025 . Finally, In addition, the IWS creates an electronic mailbox for the advertiser 1026 , using the mailbox number stored in the field AD_MAILBOX_NUMBER as the electronic mail address, to allow respondents to submit audio, video and photographic files in response to the advertiser's ad. [0056] In addition, the mailbox numbers of matching ads are placed in a notification queue 1038 , together with delivery information corresponding to the matching ad so that the existing advertisers can be notified that a new personal ad has come onto the system that matches the existing advertisers' profile. The delivery information includes the telephone number and e-mail address, if available, of the existing advertiser to be notified, together with mailbox number of the new ad coming onto the system. [0000] Enhancing an Internet Ad With Audio, Photograph and Video [0057] A more detailed explanation of how an advertiser submits an audio greeting, photograph, or video clip via CT 1 will now be given. To submit an audio greeting, the advertiser first makes an audio recording using a WAV file editor and then saves the file using her five digit mailbox number as the file name 1030 FIG. 7 , for example: 44567.wav. The advertiser then submits the audio file using e-mail to an audio greeting electronic mailbox 1031 , for example: [email protected]. The advertiser's audio recording is stored to a disk file on the Internet Web Server. [0058] In addition, a new record is created in the AD_GREETINGS_TABLE of FIG. 3 and the Ad Database is updated 1032 . Specifically, the field GR_REVIEW_FLAG 303 is set to FALSE to indicate that the audio greeting has not been reviewed. Also, the fields GR_MAILBOX_NUMBER 301 , GR_TYPE 302 , GR_FILENAME 304 , GR_DATE_TIME 305 in the AD_GREETINGS_TABLE of FIG. 3 are also populated to indicate the advertiser's mailbox number, the format of the audio file, and the location of the audio file on the IWS, and the date and time the greeting placed. The field GR_TYPE is set to WAV to indicate that the audio recording is in the Microsoft .WAV file format. Finally, the field GR_CONVERSION_FLAG 306 is set to FALSE to indicate that the audio file must be converted from the Microsoft .WAV format to create two new audio files: one in the RealAudio .RA format for playback on the Internet, and another in the Dialogic .VOX format for playback via the telephone. [0059] To enhance a personal ad with a photograph, the advertiser first digitizes a photograph using a scanner or takes a photograph with a digital camera and then saves the image to a .GIF file using her five digit mailbox number as the file name 1037 , for example: 44567.gif The advertiser then submits the graphic file using e-mail to an photograph electronic mailbox, for example: [email protected] 1031 . [0060] The advertiser's photo is stored to a disk file on the IWS and the Ad Database is updated 1032 . Specifically, a new record is created in the AD_GREETINGS_TABLE of FIG. 3 and the field GR_REVIEW_FLAG 303 set to FALSE to indicate that the graphic file has not been reviewed. In each new record, the fields GR_MAILBOX_NUMBER 301 , GR_TYPE 302 , GR_FILENAME 304 , GR_DATE_TIME 305 in the AD_GREETINGS_TABLE of FIG. 3 are also populated to indicate the advertiser's mailbox number, the format of the graphic file, and the location of the graphic file on the IWS, and the date and time the photograph was received. The field GR_TYPE 302 is set to GIF to indicate that the graphic file is in the .GIF file format. Finally, the field GR_CONVERSION_FLAG 306 is set to TRUE to indicate that no file conversion is necessary as .GIF is the graphic file format used by the IWS. If other graphic formats were accepted, they might have to be converted to a .GIF format, depending on the file formats supported by the IWS. If file conversion were necessary, the field GR_CONVERSION_FLAG 306 would be set to FALSE. [0061] To enhance a personal ad with video, the advertiser first digitizes a video clip and then saves the image to a Microsoft .AVI file using her five digit mailbox number as the file name 1036 , for example: 44567.avi. Other video formats such as Apple Quicktime, or MPEG video could also be used. The advertiser then submits the graphic file using e-mail to an electronic mailbox, for example: [email protected] 1031 . [0062] The advertiser's video clip is stored to a disk file on the IWS and the Ad Database is updated 1032 . Specifically, a new record is created in the AD_GREETINGS_TABLE of FIG. 3 and the field GR_REVIEW_FLAG 303 set to FALSE to indicate that the video file has not been reviewed. In each new record, the fields GR_MAILBOX_NUMBER 301 , GR_TYPE 302 , GR_FILENAME 304 , GR_DATE_TIME 305 in the AD_GREETINGS_TABLE of FIG. 3 are populated to indicate the advertiser's mailbox number, the format of the video file, and the location of the video file on the IWS, and the date and time the video was received. Specifically, the field GR_TYPE 302 is set to AVI to indicate that the video clip is in the Microsoft .AVI file format. Finally, the field GR_CONVERSION_FLAG 306 is set to FALSE to indicate that the video file must be converted to the VDOLive format for real time playback on the Internet. [0000] Notifying an Existing Advertiser of New Matches [0063] FIG. 8 illustrates the notification routine that processes the records placed in the notification queue in step 836 of FIG. 6 and step 1038 of FIG. 7 . In step 7001 , the DBS scans the notification queue to determine if any notifications are scheduled to be made at the present time. As previously described, each notification record includes the telephone number and e-mail address, if available, of the advertiser to be notified, together with the mailbox number of the new matching personal ad that has come onto the system. In step 7003 , the DBS scans the notification record for an e-mail address. If an e-mail address is present, the DBS sends the record to the IWS 7004 . In step 7005 , the IWS sends an e-mail message to the advertiser informing him that a new ad has come onto the system that matches his profile. The e-mail message includes the mailbox number of the new ad. The mailbox number is also a hot link that can be followed to the actual ad for those retrieving their e-mail via a browser. Step 7006 sends the record to the IVR. In step 7007 , the IVR dials an advertiser's telephone number contained in the callback record and waits for a response. If a voice response is not received, then the IVR sends a corresponding message to the DBS. The DBS then marks the time of the attempted callback in the notification queue record, so that a set period of time can be established between callback attempts. A note could also be made if an e-mail message had been sent to avoid sending duplicate notifications. If a voice response is received 7008 , then, in step 7009 , the IVR sends a voice message informing the person that a new ad has come onto the system that matches the person's profile. The voice message also gives a 900 number and Internet address that can be used to receive the match. It may be desirable in certain applications to prompt the person who answers the telephone for a password and mailbox number to verify their identity. Also, it may be desirable to actually allow the person to listen and respond to his match during the call. [0000] Advertiser Matching Via Telephone [0064] An exemplary operation of the system of the present invention, with regard to an advertiser retrieving personal ads that match his preferences will now be treated to accomplish the process as indicated in FIG. 9 . First, suppose a telephone caller at terminal T 1 places a call to retrieve matches after having placed a personal ad or after having been notified of the existence of a new personal ad that match his preferences. The assumed call involves the advertiser actuating the buttons to input the number 1 900 777 4444, for example. As a result, signals are provided to the PTN resulting in a connection from the remote terminal T 1 to the IVR. Using standard DNIS techniques, the IVR associates the called number 1 900 777 4444 with a specific format, for example, a match retrieval format. [0065] Referring to FIG. 9 , upon receiving a call, the IVR sets the “logon attempts” equal to zero 8001 . The IVR then increments the “logon attempts” by one 8002 and cues the caller for a mailbox number and password 8003 . The IVR then queries the Ad Database to determine if the mailbox number and password are valid 8004 . If the entries are not valid, the IVR determines if the caller has exceeded the maximum number of logon attempts allowed 8005 . If the caller has exceeded the maximum number of logon attempts allowed, the call is terminated 8006 . If the maximum number of logon attempts allowed has not been exceeded, the IVR increments the “logon attempts” by one 8002 and again cues the caller for a mailbox number and password 8003 . [0066] If the entries are valid, the IVR then queries the Ad Database for existing, ads whose profile matches that of the caller 8008 . If there are no matches, the call is terminated 8006 . If the IVR finds a match, the IVR plays the greeting of the matching ad 8009 . If the greeting is in text form, the IVR uses text to speech to play the message. The IVR then prompts the caller to indicate if he wishes to respond to the ad 8010 . [0067] If the caller elects not to respond to the ad and there are no additional matches, the call is terminated 8015 . If the caller elects not to respond to the ad and there are additional matches, the caller is returned to block 8009 . [0068] If the caller elects to respond to the ad, the IVR next cues him to record his response 8011 . The IVR then stores the response to a disk file 8012 and updates the Ad Database 8013 . Specifically, the IVR creates a new record in the AD_RESPONSE_TABLE of FIG. 5 and populates the fields RSP_MAILBOX_NUMBER 501 , RSP_RMAILBOX_NUMBER 502 , RSP_DATE_TIME 503 , RSP_TYPE 504 , and RSP_FILENAME 505 to indicate the mailbox number of the ad responded to, the mailbox number of the respondent, the date and time of the response, the format of the response, and the location of the response file on the IVR. The field RSP_TYPE 504 is set to VOX to indicate that the audio recording is in the Dialogic .VOX file format. Finally, the field RSP_CONVERSION_FLAG 506 is set to FALSE to indicate that the audio must be converted from the Dialogic .VOX format to create a new audio file in the RealAudio .RA format for playback on the Internet. [0069] The IVR creates a new RealAudio .RA file from the Dialogic .VOX file and stores the RealAudio file to a disk file on the IWS and updates the Ad Database. Specifically, the IVR creates a new record in the AD_RESPONSE_TABLE of FIG. 5 and populates the fields RSP_MAILBOX_NUMBER 501 , RSP_RMAILBOX_NUMBER 502 , RSP_DATE_TIME 503 , RSP_TYPE 504 , and RSP_FILENAME 505 to indicate the mailbox number of the ad responded to, the mailbox number of the respondent, the date and time of the response, the format of the response, and the location of the response file on the IVR. The field RSP_TYPE 504 is set to RA to indicate that the audio recording is in the RealAudio .RA file format. [0070] Finally, the field RSP_CONVERSION_FLAG 506 is set to TRUE for both the audiotext .VOX file and the RealAudio .RA file to indicate that the audio files do not need to be converted. [0071] If there are additional matches, the caller is returned to block 8009 . Otherwise, the call is terminated 8015 . [0000] Advertiser Matching Via the Internet [0072] An exemplary operation of the system of the present invention, with regard to a specific advertiser retrieving her matches via the Internet will now be treated to accomplish the process as indicated in FIG. 10 . First, suppose an advertiser at terminal CT 1 connects to the Internet to find existing ads that match her profile. The assumed advertiser connects to the Internet and inputs a Uniform Reference Locator URL, for example: http://www.personal_ads.com, resulting in a connection from the remote terminal CT 1 to a Home Page 1301 on the Internet Web Server. [0073] Referring to FIG. 10 , from the Home Page 9001 on the Internet Web Server, the Internet user selects a Match Form 9002 . The Match Form 9002 instructs the advertiser to enter a mailbox number 9003 and password 9004 . The IWS then queries the Ad Database to determine if the mailbox number and password are valid 9005 . If the entries are not valid, the Internet user is presented with an Invalid Mailbox and Password Form 9006 . If the entries are valid, the IWS queries the Ad Database 9007 to find existing ads whose profile matches that of the advertiser. [0074] If the query does not find any matching ads, the advertiser is presented with a No Matches Page 9009 . If the query finds one or more matching ads, the IWS presents the advertiser with a Results Form 9010 . The Results Form 9010 shows the matching ads. Specifically, the Results Form shows the twenty word text ad that appears in the newspaper 9011 . In addition, each ad contains one or more icons that represent any additional text or multimedia files (audio, video, photograph) for the ads that are available on the IWS. These icons include an audio icon 9012 to denote the ad's audio greeting, a still camera icon 9013 to denote a photograph of the advertiser, a video camera icon 9014 to denote a video clip of the advertiser, or a paper icon 9015 to denote the ad's full text greeting, if the ad was placed on the Internet. It is to be understood that these icons are merely representative and that many other possibilities exist to denote the existence of text and multimedia files. By clicking on an icon, the Internet user can view or listen to the associated file. In addition, by selecting a maximize bar 9016 , the Internet user can expand an ad to a full page size, see FIG. 15 . [0075] The Internet user responds to an ad by selecting the “Respond” button 9017 . When the Internet user selects the respond button, she is presented with an Ad Response Form 9018 . The Internet user creates a response by typing in a response text field 9019 . After completing the Ad Response Form, the Internet user submits the form by pressing the “Submit” button 9020 . The advertiser is then presented with a Response Confirmation Form 9021 . The Response Confirmation Form gives the advertiser information on enhancing her response with an audio message, photograph, or video clip. [0076] The IWS then stores the response to a disk file and updates the Ad Database 9022 . Specifically, the IWS creates a new record in the AD_RESPONSE_TABLE of FIG. 5 and then populates the fields RSP_MAILBOX_NUMBER 501 , RSP_RMAILBOX_NUMBER 502 , RSP_DATE_TIME 503 , RSP_TYPE 504 , and RSP_FILENAME 505 to indicate the mailbox number of the ad responded to, the mailbox number of the respondent, the date and time of the response, the format of the response, and the location of the response file on the IWS. The field RSP_TYPE 504 is set to TEXT. Finally, the field RSP_CONVERSION_FLAG 506 is set to TRUE to indicate that the text does not need to be converted to a different format. [0077] The Internet user can return to the Results Form by using the “Back” key on her browser. [0000] Reviewing and Summarizing Ads [0078] All new personal ads are reviewed by an operator at an OW to insure that their content is appropriate. Also, each greeting submitted by an advertiser, whether it be an audio greeting recorded by an advertiser via a telephone or a text greeting placed by an advertiser via the Internet, is summarized by an operator to create a twenty word classified text ad for publication in a newspaper. The twenty word limit is a function of newspaper imposed space limitations. It should be noted that space limitations, if they exist at all, may vary widely from newspaper to newspaper. In another format, text ads that are published in the newspaper are first placed with a live operator via a telephone, precluding the need to summarize an audio recording. [0079] An exemplary operation of the process of reviewing and summarizing ads with regard to a specific operator at OW 1 will now be treated to accomplish the process as indicated in FIG. 11 . The operator first queries the Ad Database to determine if there are new ads to review 1800 . Specifically, the query looks for all ads in the AD_PERSONAL_TABLE of FIG. 2 where the field AD_REVIEW_FLAG 210 is set to FALSE. If the query finds a new ad, the operator first reviews the ad's greeting 1801 as found in the AD_GREETINGS_TABLE of FIG. 3 . If the ad was placed via telephone, this consists of listening to the ad's audio greeting. If the ad was placed via the Internet, this consists of reading the text greeting. The operator then determines if the greeting's contents are appropriate 1802 . If the greeting's contents are inappropriate, the ad is deleted and the record purged from the Ad Database 1803 and the operator is returned to block 1800 . If the greeting's contents are appropriate, the operator writes a twenty word summary of the greeting 1804 . The operator then queries the Ad Database to determine if the advertiser recorded an e-mail address 1805 . If an e-mail address audio recording is found, the operator transcribes the e-mail address 1806 . The operator then updates the Ad Database 1807 . [0080] Specifically, the advertiser's twenty word text summary is stored to a disk file on the IWS. The AD_REVIEW_FLAG 210 in the AD_PERSONAL_TABLE of FIG. 2 is set to TRUE indicating that the ad has been reviewed. In addition, a new record for the text summary is created in the AD_GREETINGS_TABLE of FIG. 3 and the field GR_REVIEW_FLAG 303 set to TRUE indicating that the record has been reviewed. In the new record, the fields GR_MAILBOX_NUMBER 301 , GR_TYPE 302 , GR_FILENAME 304 , GR_DATE_TIME 305 in the AD_GREETINGS_TABLE of FIG. 3 are also populated to indicate the advertiser's mailbox number, the file format, and the location of the text file on the IWS, and the date and time. The field GR_TYPE is set to TEXT Finally, the field GR_CONVERSION_FLAG 306 is set to TRUE to indicate that the text does not need to be converted to a different format. [0081] The operator then returns to block 1800 to continue processing ads. If no new ads are found, the operator queries the Ad Database to determine if any multimedia files (audio, video, or photo) have been submitted via the Internet to enhance a personal ad 1808 . Specifically, the query looks for all ads in the AD_PERSONAL_TABLE of FIG. 2 where the field AD_REVIEW_FLAG 210 is set to TRUE that has files in the AD_GREETING_TABLE of FIG. 3 where the GR_REVIEW_FLAG 303 is set to FALSE. If the query finds a multimedia file, the operator first reviews the file 1809 . If it is an audio file, this consists of listening to the ad's audio greeting. If it is a video or graphic file, this consists of viewing the file. The operator then determines if the greeting's contents are appropriate 1810 . If the greeting's contents are inappropriate, the filed is deleted and the record purged from the Ad Database 1811 . The operator is then returned to block 1808 to continue processing multimedia files. If the file's contents are appropriate, the operator approves the file 1812 and updates the Ad Database 1813 . Specifically, this consists of setting the field GR_REVIEW_FLAG 303 to TRUE to indicate that the file has been reviewed. [0082] If the file is an audio file, the OW converts the file to create a new RealAudio RA file and stores the file on the IWS. The OW also converts the file to create a Dialogic VOX file and stores the file on the IVR. For each new audio file, a new record is created in the AD_GREETINGS_TABLE of FIG. 2 and the fields GR_MAILBOX_NUMBER 301 , GR_TYPE 302 , GR_DATE_TIME 305 , and GR_FILENAME 304 are populated to indicate the mailbox number of the advertiser, the format of the file, the date and time, and the location of the audio file on the IVR Also, the field GR_REVIEW_FLAG 303 is set to TRUE to indicate that the file has been reviewed. Finally, the field GR_CONVERSION_FLAG is set to TRUE to indicate that the audio file does not need to be converted. [0083] If the file is a video file, the OW converts the Microsoft AVI file to create a new VDOLive file and stores the file on the IWS. Also, a new record is created in the AD_GREETINGS_TABLE of FIG. 2 and the fields GR_MAILBOX_NUMBER 301 , GR_TYPE 302 , GR_DATE_TIME 305 , and GR_FILENAME 304 are populated to indicate the mailbox number of the advertiser, the format of the file, the date and time, and the location of the video file on the IVR. Also, the field GR_REVIEW_FLAG 303 is set to TRUE to indicate that the file has been reviewed. Finally, the field GR_CONVERSION_FLAG 306 is set to TRUE to indicate that the video file does not need to be converted. [0084] The operator then returns to block 1808 to continue processing multimedia files. If no new multimedia files are found, the session is terminated 1814 . [0000] Publishing Ads in the Newspaper [0085] Each week, all the twenty-word summary text ads from personal ads submitted via telephone and via the Internet are published in a newspaper along with their five digit mailbox numbers. FIG. 12 depicts personal ads as they would appear in the local newspaper. Icons are included in each ad that represent the origin of an ad (via telephone or via the Internet) and what additional information or multimedia, if any, is available on the Internet. For example, an ad placed via the telephone contains a telephone icon 2001 ; an ad placed via the Internet contains a computer icon 2002 . If there is additional text on the Internet, an ad contains an icon denoting additional text 2004 . The presence of a photo or video clip is indicated respectively by a still camera 2004 and video camera 2005 icons. [0000] Responding to an Ad Through a Telephone [0086] An exemplary operation of the system of the present invention, with regard to a telephone caller responding to a personal advertisement will now be treated to accomplish the process as indicated in FIG. 13 . First, suppose a telephone caller at terminal T 1 places a call to respond to a personal ad advertised in XYZ newspaper. The assumed call involves the telephone caller actuating the buttons to input the number 1 900 777 3333, for example. As a result, signals are provided to the PTN resulting in a connection from the remote terminal T 1 to the IVR. Using standard DNIS techniques, the IVR associates the called number 1 900 777 3333 with a specific format, for example, a voice personals response format. [0087] Referring to FIG. 13 , upon receiving a call, the IVR sets the “invalid mailbox number count” equal to zero 2301 . The IVR then increments the “invalid mailbox number count” by one 2302 and cues the caller for a mailbox number 2303 . Upon the caller entering a mailbox number, the IVR queries the field AD_MAILBOX_NUMBER 201 to determine if the mailbox number is valid 2304 . If the mailbox number is invalid, the IVR determines if the caller has exceeded the maximum number of attempts allowed 2305 . If the caller has exceeded the maximum number of attempts allowed, the call is terminated 2306 . If the maximum number of attempts allowed has not been exceeded, the IVR increments the “invalid mailbox number count” by one 2302 and again cues the caller for a mailbox number 2303 . [0088] If the mailbox number is valid, the IVR queries the field AD_ORIGIN 211 to determine if the ad originated on the Internet 2307 . If the ad originated on the telephone, the IVR plays the ad's audio greeting 2311 . If the ad originated on the Internet, the IVR uses text to speech to play the ad's text greeting as placed on the Internet 2308 . The IVR then queries the AD_GREETINGS_TABLE of FIG. 2 to determine if the Internet advertiser also submitted an audio greeting 2309 . If the query does not find an audio greeting 2310 , the IVR prompts the caller to indicate if he wishes to respond to the ad 2312 . If the query finds an audio greeting 2310 , the IVR plays the audio greeting 2311 . The IVR then prompts the caller to indicate if he wishes to respond to the ad 2312 . [0089] If the caller elects not to respond to the ad, he is given the option of having the IVR find other ad that are similar to the one he just listened to 2324 . If the caller elects to respond to the ad, the IVR cues the caller to enter his five digit mailbox number or to enter “#” if he does not have a mailbox number 2332 . If the caller indicates that he does not have a mailbox number by entering the “#” key, the IVR assigns the respondent a five digit mailbox number 2327 . For example: “Your five digit mailbox number is 54321.” The mailbox number is then stored 2328 in the field PR_MAILBOX_NUMBER 401 . The IVR then cues the respondent to enter a five digit password 2329 . The password is then stored 2330 in the field PR_PASSWORD 402 . The Ad Database is then updated 2331 to include the date and time the mailbox is created. [0090] The IVR first cues the caller to record his response 2319 . The IVR then stores the response to a disk file and updates the Ad Database 2321 . Specifically, the IVR creates a new record in the AD_RESPONSE_TABLE of FIG. 5 populates the fields RSP_MAILBOX_NUMBER 501 , RSP_RMAILBOX_NUMBER 502 , RSP_DATE_TIME 503 , RSP_TYPE 504 , and RSP_FILENAME 505 to indicate the mailbox number of the ad responded to, the mailbox number of the respondent, the date and time of the response, the format of the response, and the location of the response file on the IVR. The field RSP_TYPE 504 is set to VOX to indicate that the audio recording is in the Dialogic .VOX file format. Finally, the field RSP_CONVERSION_FLAG 506 is set to FALSE to indicate that the audio must be converted from the Dialogic .VOX format to create a new audio file in the RealAudio .RA format for playback on the Internet. [0091] The IVR also creates a new RealAudio .RA file from Dialogic .VOX file and stores the RealAudio file to a disk file on the IWS. Specifically, the IVR creates a new record in the AD_RESPONSE_TABLE of FIG. 5 and populates the fields RSP_MAILBOX_NUMBER 501 , RSP_RMAILBOX_NUMBER 502 , RSP_DATE_TIME 503 , RSP_TYPE 504 , and RSP_FILENAME 505 to indicate the mailbox number of the ad responded to, the mailbox number of the respondent, the date and time of the response, the format of the response, and the location of the response file on the IVR. The field RSP_TYPE 504 is set to RA to indicate that the audio recording is in the RealAudio .RA file format. Finally, the field RSP_CONVERSION_FLAG 506 is set to TRUE for both the audiotext .VOX file and the RealAudio .RA file to indicate that the audio files do not need to be converted. [0092] In addition, the mailbox number of the personal ad responded to is placed in a notification queue 2322 , together with delivery information corresponding to the ad, so that the advertiser can be notified that a response has been left for her ad. The delivery information includes the telephone number and e-mail address, if available, of the advertiser to be notified. [0093] The caller is then asked if he wants the IVR to automatically find other ads that are similar to the one he just responded to 2325 . If the caller declines this option, the call is terminated 2326 . [0000] Response Matching Via Telephone [0094] If the caller chooses to have the IVR find other matching ads, the IVR queries the Ad Database to find other ads that are similar to the ad selected by the caller. Specifically, an ad is deemed to be similar if the age in the ad's profile is within five years of the profile of the ad selected by the caller and if the ads have the same gender and marital status. Its is to be understood that the criteria used to determine a similar ad could vary greatly in kind and quantity. [0095] If the query does not find any matches, the call is terminated 2326 . If the query returns a match, the caller is returned to block 2307 for processing. [0000] Responding to an Ad Through the Internet [0096] An exemplary operation of the system of the present invention, with regard to a specific Internet user responding to a personal ad via the Internet will now be treated to accomplish the process as indicated in FIG. 14 . First, suppose an advertiser at terminal CT 1 connects to the Internet to respond to a personal advertisement advertised in XYZ newspaper. The assumed Internet user connects to the Internet and inputs a URL, for example: http://www.personal_ads.com, resulting in a connection from the remote terminal CT 1 to a Home Page on the IWS. [0097] Referring to FIG. 14 , from the Home Page 2401 on the IWS, the Internet user selects an Ad Response Form 2402 . The Ad Response Form instructs the Internet user to enter the five digit mailbox number of the ad she wishes to respond to 2403 . Upon the Internet user entering her mailbox number, the IWS queries the field AD_MAILBOX_NUMBER in the Ad Database to determine if the mailbox number is valid 2404 . If the mailbox number is invalid, the Internet user is presented with an Invalid Mailbox Number Form 2405 . [0098] If the mailbox number is valid, the IWS presents the Internet user with a Results Form 2406 . The Results Form 2406 shows the ad the Internet user selected. Specifically, the Results Form shows the twenty word text ad that appears in the newspaper 2407 . In addition the ad contains one or more icons that represent any additional text or multimedia files (audio, video, photograph) for the ad that are available on the IWS and a path to other ads that match the ad to which the Internet user is responding. These icons include an audio icon 2408 to denote the ad's audio greeting, a still camera icon 2409 to denote a photograph of the advertiser, a video camera icon 2410 to denote a video clip of the advertiser, a paper icon 2411 to denote the ad's full text greeting, if the ad was placed on the Internet, and a matching icon to denote that the IWS has identified other ads that are similar to the one being responded to 2415 . It is to be understood that these icons are merely representative and that many other possibilities exist to denote the existence of text and multimedia files. By clicking on an icon, the Internet user can view or listen to the associated file. In addition, by selecting a maximize bar 2412 , the Internet user can expand an ad to full page size, as shown in FIG. 15 . The Internet user responds to an ad by selecting the “Respond” button 2413 . [0099] When the Internet user selects the respond button, she is transferred to an Ad Response Form 2414 . The Ad Response Form instructs the Internet user to enter her five digit mailbox number 2417 and to complete the response text field 2416 . [0100] If the Internet user does not have a mailbox number, she is instructed to create one by selecting the “Create New Mailbox” button 2426 . After selecting the “Create New Mailbox” button, the Internet users is presented with a Mailbox Confirmation Page 2418 that assigns the Internet user a five digit mailbox number and a five digit password 2419 . By selecting the “Complete Response” button 2420 , the Internet user can return to the Ad Response Form 2414 . The IWS then updates the Ad Database. Specifically, the IWS stores the Internet user's new mailbox number and password to the fields PR_MAILBOX_NUMBER 401 and PR_PASSWORD 402 in the AD_PERSONAL_RESPONSE_TABLE of FIG. 4 2421 along with the date and time the new mailbox is created. [0101] After completing the Ad Response Form, the Internet user submits the form by pressing the “Submit” button 2422 . The advertiser is then presented with a Response Confirmation Form 2423 which is illustrated in FIG. 16 . The Response Confirmation Form gives the advertiser information on enhancing her response with an audio message, photograph, or video clip. [0102] The IWS then stores the response to a disk file and updates the Ad Database 2424 . Specifically, the IWS creates a new record in the AD_RESPONSE_TABLE of FIG. 5 and populates the fields RSP_MAILBOX_NUMBER 501 , RSP_RMAILBOX_NUMBER 501 , RSP_DATE_TIME 503 , RSP_TYPE 504 , and RSP_FILENAME 505 to indicate the mailbox number of the ad responded to, the mailbox number of the respondent, the date and time of the response, the format of the response, and the location of the response file on the IWS. The field RSP_TYPE 504 is set to TEXT. Finally, the field RSP_CONVERSION_FLAG 506 is set to TRUE to indicate that the text does not need to be converted to a different format. [0103] In addition, the mailbox number of the personal ad responded to is placed in a notification queue 2425 , together with delivery information corresponding to the ad, so that the advertiser can be notified that a response has been left for her ad. The delivery information includes the telephone number and e-mail address, if available, of the advertiser to be notified. [0000] Enhancing a Response With Audio, Photograph and Video [0104] As already indicated, after a text response has been submitted via the Internet, the Internet user is shown a Response Confirmation Form 1501 as shown in FIG. 16 . The response confirmation form gives the Internet user instructions on how to enhance a response to an ad with audio, video, or a photograph. [0105] A more detailed explanation of how a respondent submits an audio response, photograph, or video clip via CT 1 will now be given. To submit an audio response, the Internet user first makes an audio recording using a WAV file editor and then saves the file 1503 , for example: response.wav. The Internet user then submits the audio file using e-mail to the recipient's electronic mailbox on the IWS 1504 , for example: [email protected] 1512 . The Internet user's audio response is stored to a disk file on the IWS and the Ad Database is updated 1505 . [0106] Specifically, the IVR creates a new record in the AD_RESPONSE_TABLE of FIG. 5 and populates the fields RSP_MAILBOX_NUMBER 501 , RSP_RMAILBOX_NUMBER 501 , RSP_DATE_TIME 503 , RSP_TYPE 504 , and RSP_FILENAME 506 to indicate the mailbox number of the ad responded to, the mailbox of the respondent, the date and time of the response, the format of the audio file, and the location of the audio file on the IVR. The field RSP_TYPE 504 is set to WAV to indicate that the audio recording is in the Microsoft .WAV file format. Also, the field RSP_CONVERSION_FLAG 506 is set to FALSE to indicate that the audio file must be converted from the Microsoft .WAV format to create two new audio response files: one in the RealAudio .RA format for playback on the Internet, and another in the Dialogic .VOX format for playback via the telephone. [0107] The IWS determines if conversion of audio files is needed 1506 , and then creates a new RealAudio .RA file and Dialogic .VOX file from the Microsoft .WAV file 1507 . The RealAudio file is stored on the IWS and the Dialogic file is stored on the IVR. The IWS also updates the Ad Database 1508 . Specifically, for each new audio file, the IWS creates a new record in the AD_RESPONSE_TABLE of FIG. 5 and populates the fields RSP_MAILBOX_NUMBER 501 , RSP_RMAILBOX_NUMBER 502 , RSP_DATE_TIME 503 , RSP_TYPE 504 , and RSP_FILENAME 505 to indicate the mailbox number of the ad responded to, the mailbox of the respondent, the date and time of the response, the format of the response, and the location of the response file on the IWS. Finally, the field RSP_CONVERSION_FLAG 506 is set to TRUE for both the source audio file (.WAV) and the target audio files (.VOX and .RA) to indicate that the audio files do not need to be converted 1509 . [0108] To send a photograph in response to an ad, the Internet user first digitizes a photograph using a scanner or takes a photograph with a digital camera and then saves the image to a .GIF file, for example: response.gif 1510 . The respondent then submits the graphic file using e-mail to the recipient's electronic mailbox, for example: [email protected] 1504 . The respondent's photo is stored to a disk file on the IWS and the Ad Database is updated 1505 . [0109] Specifically, the IWS creates a new record in the AD_RESPONSE_TABLE of FIG. 5 and populates the RSP_MAILBOX_NUMBER 501 , RSP_RMAILBOX_NUMBER 502 , RSP_DATE_TIME 503 , RSP_TYPE 504 , and RSP_FILENAME 505 to indicate the mailbox number of the ad responded to, the mailbox number of the respondent, the date and time of the response, the file format of the photograph, and the location of the file on the IWS. The field RSP_TYPE 504 is set to GIF to indicate that the graphic file is in the .GIF file format. Finally, the field RSP_CONVERSION_FLAG 506 is set to TRUE to indicate that no file conversion is necessary as .GIF is the graphic file format used by the IWS 1506 . It should be noted that file conversion may or may not be necessary depending on what file formats are supported by the IWS and IVR and in which formats the system allows users to submit files. [0110] To send an advertiser a video clip, the Internet user first digitizes a video clip and then saves the image to a Microsoft .AVI file 1510 , for example: 44567.avi. Other video formats such as Apple Quicktime, or MPEG video could also be used. The respondent then submits the graphic file using e-mail to the recipient's electronic mailbox, for example: [email protected] 150 . The respondent's video is stored to a disk file on the IWS and the Ad Database is updated 1505 . [0111] Specifically, the IVR creates a new record in the AD_RESPONSE_TABLE of FIG. 5 and populates the fields RSP_MAILBOX_NUMBER 501 , RSP_RMAILBOX_NUMBER 502 , RSP_DATE_TIME 503 , RSP_TYPE 504 , and RSP_FILENAME 505 to indicate the mailbox number of the ad responded to, the mailbox number of the respondent, the date and time of the response, the file format of the video clip, and the location of the video file on the IWS. Specifically, the field RSP_TYPE 504 is set to AVI to indicate that the audio recording is in the Microsoft .AVI file format. Finally, the field RSP_CONVERSION_FLAG 506 is set to FALSE to indicate that the VDOLive file must be converted to the VDOLive format for real time playback on the Internet. [0112] The IWS determines that the video file must be converted to VDOLive format 1506 . The IWS creates a new VDOLive file from the Microsoft .AVI file and stores the new file to a disk file 1507 on the IWS and updates the Ad Database 1508 . A new record in the AD_RESPONSE_TABLE of FIG. 5 is created and the IWS populates the RSP_MAILBOX_NUMBER 501 , RSP_DATE_TIME 503 , RSP_TYPE 504 , and RSP_FILENAME 505 fields to indicate the mailbox number of the ad responded to, the date and time of the response, the format of the video file, and the location of the video file on the IWS. Finally, the field RSP_CONVERSION_FLAG 506 is set to TRUE for both record formats (AVI and VDOLive) in the Ad Database to indicate that the video file(s) does not need to be converted 1509 . [0000] Response Matching Via the Internet [0113] As previously indicated, if the user selects the matching option 2415 in FIG. 14 , the IWS queries the Ad Database to find other ads that are similar to the ad selected by the caller. Specifically, an ad is deemed to be similar if the age in the ad's profile is within five years of the profile of the ad selected by the caller and if the ads have the same gender and marital status. Its is to be understood that the criteria used to determine a similar ad could vary greatly in kind and quantity. [0000] Notifying an Advertiser of a Response [0114] FIG. 17 illustrates the notification routine that processes the records placed in the notification queue in step 2322 of FIG. 13 and step 2425 of FIG. 14 . In step 3001 , the DBS scans the notification queue to determine if any callbacks are scheduled to be made at the present time. As previously described, each notification record includes the telephone number and e-mail address, if available, of the advertiser to be notified. In step 3003 , the DBS scans the notification record for an e-mail address. If an e-mail address is present, the DBS sends the record to the IWS 3004 . In step 3005 , the IWS sends an e-mail message to the advertiser informing him that a response has been made to his ad. The e-mail message includes a hot link that can be followed to the actual response for those retrieving their e-mail via a browser. Step 3006 sends the record to the IVR. In step 3007 , the IVR dials an advertiser's telephone number contained in the callback record and waits for a response. If a voice response is not received, then the IVR sends a corresponding message to the DBS. The DBS then marks the time of the attempted callback in the notification queue record, so that a set period of time can be established between callback attempts. Note could also be made if an e-mail message had been sent to avoid sending duplicate notifications. If a voice response is received 3008 , then in step 3009 , then the IVR sends a voice message informing the advertiser that a response has been made to his ad. The voice message also gives a telephone number and Internet address that can be used to retrieve the response. It may be desirable in certain applications to prompt the person who answers the telephone for a password and mailbox number to verify their identity. Also, it may be desirable to actually allow the person to listen to the response during the call. [0000] Retrieving Messages Through a Telephone [0115] An exemplary operation of the system, with regard to an advertiser retrieving response messages to his personal ad will now be treated to accomplish the process as indicated in FIG. 18 . First, suppose an advertiser at terminal T 1 places a call to retrieve messages left in response to his ad. The assumed call involves the advertiser actuating the buttons to input the number 1 900 777 4444, for example. As a result, signals are provided to the public telephone network resulting in a connection from the remote terminal T 1 to the IVR. Using standard DNIS techniques, the IVR associates the called number 1 900 777 4444 with a specific format, for example, a message retrieval format. [0116] Referring to FIG. 18 , upon receiving a call, the IVR sets the “logon attempts” equal to zero 2501 . The IVR then increments the “logon attempts” by one 2502 and cues the caller for a mailbox number 2508 and password 2503 . The IVR then queries the Ad Database to determine if the mailbox number and password are valid 2504 . If the entries are not valid, the IVR determines if the caller has exceeded the maximum number of logon attempts allowed 2505 . If the caller has exceeded the maximum number of logon attempts allowed, the call is terminated 2506 . If the maximum number of logon attempts allowed has not been exceeded, the IVR increments the “logon attempts” by one 2502 and again cues the caller for a mailbox number and password. [0117] If the entries are valid, the IVR then queries the AD_RESPONSE_TABLE of FIG. 5 to determine if the advertiser has any response messages 2507 . If the advertiser has no response messages, the call is terminated 2506 . If the IVR finds a response message, the IVR queries the field AD_ORIGIN 211 to determine if the response message originated on the Internet 2509 . If the response message originated on the telephone, the IVR plays the audio response message 2513 . If the response message originated on the Internet, the IVR uses text to speech to play the text response message as placed on the Internet 2510 . The IVR then queries the AD_GREETINGS_TABLE of FIG. 2 to determine if the Internet respondent also submitted an audio response message 2511 . If the query does not find an audio greeting 2512 , the IVR prompts the caller to indicate if he wishes to respond to the ad 2514 . If the query finds an audio greetings 2512 , the IVR plays the audio greetings 2513 . The IVR then prompts the caller to indicate if he wishes to respond to the ad 2514 . [0118] If the caller elects not to respond to the ad, the IVR queries the AD_RESPONSE_TABLE of FIG. 5 to determine if the advertiser has any additional response messages 2519 . If an additional response message is found, the caller is returned to block 2509 for processing. If an additional response message is not found, the call is terminated 2520 . If the caller elects to respond to the ad, the IVR cues the caller to record his response 2515 . The IVR then stores the response to a disk file 2516 and updates the Ad Database 2517 . Specifically, the IVR creates a new record in the AD_RESPONSE_TABLE of FIG. 5 populates the fields RSP_MAILBOX_NUMBER 501 , RSP_RMAILBOX_NUMBER 502 , RSP_DATE_TIME 503 , RSP_TYPE 504 , and RSP_FILENAME 505 to indicate the mailbox number of the system user to whom the response is directed, the mailbox number of the respondent, the date and time of the response, the format of the response, and the location of the response file on the IVR. The field RSP_TYPE 504 is set to VOX to indicate that the audio recording is in the Dialogic .VOX file format. Finally, the field RSP_CONVERSION_FLAG 506 is set to FALSE to indicate that the audio must be converted from the Dialogic .VOX format to create a new audio file in the RealAudio .RA format for playback on the Internet. [0119] The IVR also creates a new RealAudio .RA file from Dialogic .VOX file and stores the RealAudio file to a disk file on the IWS. Specifically, the IVR creates a new record in the AD_RESPONSE_TABLE of FIG. 5 and populates the fields RSP_MAILBOX_NUMBER 501 , RSP_RMAILBOX_NUMBER 502 , RSP_DATE_TIME 503 , RSP_TYPE 504 , and RSP_FILENAME 505 to indicate the mailbox number of the ad responded to, the mailbox number of the respondent, the date and time of the response, the format of the response, and the location of the response file on the IVR. The field RSP_TYPE 504 is set to RA to indicate that the audio recording is in the RealAudio .RA file format. Finally, the field RSP_CONVERSION_FLAG 506 is set to TRUE for both the audiotext .VOX file and the RealAudio .RA file to indicate that the audio files do not need to be converted. [0120] Next, the IVR queries the AD_RESPONSE_TABLE of FIG. 5 to determine if the advertiser has any additional response messages 2519 . If an additional response message is found, the caller is returned to block 2509 for processing. If no additional response messages are found, the call is terminated 2520 . [0000] Retrieving Messages Through the Internet [0121] An exemplary operation of the system of the present invention, with regard to an advertiser retrieving her messages via the Internet will now be treated to accomplish the process as indicated in FIG. 19 . First, suppose an advertiser at terminal CT 1 connects to the Internet to retrieve messages. The assumed Internet user connects to the Internet and inputs a Uniform Reference Locator URL, for example: http://www.personal_ads.com, resulting in a connection from the remote terminal CT 1 to a Home Page 1701 on the Internet Web Server. [0122] Referring to FIG. 19 , from the Home Page 1701 on the Internet Web Server, the advertiser selects a Message Retrieval Form 1702 . The Message Retrieval Form 1702 instructs the advertiser to enter a mailbox number 1703 and password 1704 . The IWS then queries the Ad Database to determine if the mailbox number and password are valid 1705 . If the entries are not valid, the Internet user is presented with an Invalid Mailbox and Password Form 1706 . If the entries are valid 1705 , the IWS queries the Ad Database 1707 to find responses to the advertiser's ad. [0123] If there are no responses, the IWS presents the advertiser with a No Responses Form 1709 . If the IWS finds one or more responses, the IWS presents the advertiser with a Personal Ad Messages Form 1710 . The Personal AD Messages Form 1709 shows any messages for the advertiser. Each message shows the date 1712 and time 1713 the message was received and contains one or more icons that represent the contents of the message. A text icon 1714 denotes a text message; an audio icon 1715 denotes an audio message; a still camera icon 1716 denotes a photograph; a video camera icon 1717 denotes a video clip. By clicking on an icon, the advertiser can view or listen to the associated file. The Internet user responds to a message ad by selecting its associated “Respond” button 1718 . [0124] When the Internet user selects the respond button, she is transferred to an Ad Response Form 1719 . The Internet user creates a response by completing a response text field 1720 . After completing the Ad Response Form, the Internet user submits the form by pressing the “Submit” button 1721 . The advertiser is then presented with a Response Confirmation Form 1722 which is illustrated in FIG. 16 . The Response Confirmation Form gives the advertiser information on enhancing her response with an audio message, photograph, or video clip. [0125] The IWS then stores the response to a disk file and updates the Ad Database 1723 . Specifically, the IWS creates a new record in the AD_RESPONSE_TABLE of FIG. 5 and populates the fields RSP_MAILBOX_NUMBER 501 , RSP_RMAILBOX_NUMBER 502 , RSP_DATE_TIME 503 , RSP_TYPE 504 , and RSP_FILENAME 505 to indicate the mailbox number of the system user to whom the response is directed, the mailbox number of the respondent, the date and time of the response, the format of the response, and the location of the response file on the IWS. The field RSP_TYPE 504 is set to TEXT. Finally, the field RSP_CONVERSION_FLAG 506 is set to TRUE to indicate that the text does not need to be converted to a different format.

The present invention relates to an electronic advertising system. More specifically, the present invention allows telephone users to create a “mailbox” at the point of responding to an ad, regardless of whether the ad originated on the telephone or on the Internet. Similarly, Internet users can create a “mailbox” at the point of responding to a personal ad on the Internet, regardless of whether the ad originated on the telephone or via the Internet. By giving both advertisers and respondents a “mailbox”, the present invention allows for anonymous communication until one or both are comfortable with giving out a means of contact. Moreover, the communication can occur regardless of whether a user is on a telephone or on the Internet. This provides additional safety for users of personal ad systems while preserving the ability for telephone users to communicate with Internet users.

This application is a Continuation of U.S. patent application Ser. No. 09/523,511, entitled SHIFT REGISTER CIRCUIT, IMAGE DISPLAY APPARATUS HAVING THE CIRCUIT, AND DRIVING METHOD FOR LCD DEVICES, filed Mar. 10, 2000 now U.S. Pat. No. 6,879,313; by Yasushi KUBOTA, Hajime WASHIO, Shigeto YOSHIDA (the inventors of the claims of this continuation application), Kazuhiro Maeda and Hiroshi Yoneda. TECHNICAL FIELD The present invention relates to a shift register circuit for transferring a digital signal in synchronization with a leading edge and a trailing edge of a clock signal. More particularly, the invention relates to a shift register circuit arranged such that a clock signal is locally input to thereby reduce the load on a clock signal line, with a view to increasing the operating margin and reducing power consumption, and also relates to an image display apparatus in which such a shift register circuit is applied to a data driver and/or a scan driver. The invention further relates to a driving method for active matrix type liquid crystal display devices to be used for TV monitors, portable information terminals and the like. More particularly, the invention relates to a driving method to be used for displaying a picture having such an aspect ratio as 16:9 on a liquid crystal display screen having such an aspect ratio as 4:3. BACKGROUND OF THE INVENTION As a conventional liquid crystal display (LCD) device, there has been known an LCD device of the active matrix driven system (hereinafter, referred to as “active matrix driven LCD device”). FIG. 19 shows an active matrix-driven LCD device 100 . The active matrix-driven LCD device 100 has a pixel array ARY, a scan driver GD and a data driver SD. The pixel array ARY has a plurality of scan signal lines GL, and a plurality of data signal lines SL intersecting the plurality of scan signal lines GL. One pixel is provided in a position surrounded by adjacent two scan signal lines GL and adjacent two data signal lines SL, so that pixels PIX are arranged totally in a matrix form. In synchronization with a timing signal such as a clock signal SCK, the data driver SD samples an input video signal DAT, and amplifies, as required, and supplies the sampled video signal DAT to the data signal lines SL. The scan driver GD, in synchronization with a timing signal such as a clock signal GCK, selects the scan signal lines GL sequentially to control the turn-on and -off of switching devices within the pixels PIX, whereby the video signal (data) supplied to the data signal lines SL is written to the pixels PIX. The pixels PIX function to retain the data written in the pixels PIX. FIG. 20 shows details of the pixel PIX. The pixel PIX has a field effect transistor SW as a switching device, and a pixel capacitor CI (made up of liquid crystal capacitor CL and auxiliary capacitor CS, the latter being added as necessary.). The field effect transistor SW has a drain, a source and a gate. Hereinafter, one of the drain and the source will be referred to as a first electrode and the other of the drain and the source as a second electrode. The first electrode of the field effect transistor SW is connected to the data signal line SL, and the second electrode is connected to an end “a” of the pixel capacitor CI. Also, the gate of the field effect transistor SW is connected to the scan signal line GL. An end “b” of the liquid crystal capacitor CL is connected to a common electrode line which is common to all the pixels PIX. By a voltage applied to the liquid crystal capacitor CL, the transmissivity or reflectance of the liquid crystals is modulated, and an image is displayed. In conventional active matrix type LCD devices, an amorphous silicon thin film formed on a transparent substrate of glass or the like is used as a material of the pixel transistor SW. Also, the scan driver GD and the data driver SD in conventional active matrix type LCD devices have been implemented by external integrated circuits (ICs), respectively. However, these days, to respond to demands for improvement in driving force of pixel transistors to keep up with larger-sized screens, reduction in mounting cost of driver ICs, or for reliability in mounting, pixel arrays and driver circuits are formed monolithically by using a polysilicon thin film. With a view to realizing even larger screens and further cost reduction of LCDs, there have been attempts to form such devices as field effect transistors with a polysilicon thin film on the glass substrate at process temperatures below the glass distortion point (about 600° C.). FIG. 21 shows an active matrix type LCD device 200 in which a pixel array and drivers are formed monolithically. In this active matrix type LCD device 200 , a pixel array ARY, a scan driver GD and a data driver SD are mounted on an insulative substrate SUB, and a timing signal generator CTL and a supply voltage generator VGEN are each connected to the scan driver GD and the data driver SD. The data driver SD receives signals such as a video signal DAT. In FIG. 21 , paths along which the video signal DAT and the like are transferred within the data driver SD are depicted in broken line. The scan driver GD receives signals such as a pulse signal GPS. In FIG. 21 , paths along which the pulse signal GPS and the like are transferred within the scan driver GD are depicted in broken line. As the data driver, there have been known data drivers of the dot sequential drive system and data drivers of the line sequential drive system, differing from each other depending on the method of writing a video signal into video signal lines. In polysilicon TFT panels in which the data driver has been integrated, the data driver of the dot sequential drive system is often used for the sake of configurational simplicity of the data driver. Now the construction of a typical data driver of the dot sequential drive system is explained with reference to FIG. 22 . FIG. 22 shows a data driver SD of the dot sequential drive system. In the dot sequential drive system, sampling switches AS are opened and closed in synchronization with output pulses from individual stages (latch circuits) of a shift register circuit SFC, which is made up of a plurality of latch circuits LATA, LATB. By the sampling switches AS being opened and closed, a video signal DAT supplied to the video signal line is written into the data signal lines SL. As shown in FIG. 22 , a buffer circuit BFC 1 is located between the shift register circuit SFC and the sampling switches AS. The buffer circuit BFC 1 fetches a pulse signal output from the shift register circuit SFC, and retains and amplifies the pulse signal and moreover, as required, generates an inverted signal of the pulse signal. The construction of the scan driver is explained below with reference to FIG. 23 . FIG. 23 shows a scan driver GD. This scan driver GD has a shift register circuit SFC composed of a plurality of latch circuits LATA and LATB, and a buffer circuit BFC 2 . The scan driver GD amplifies output pulse signals (or logical operation results with other signals if required) of individual stages (latch circuits) of the shift register circuit SFC, which is composed of the plurality of latch circuits LATA, LATB, and then, outputs the amplified output pulse signals as scan signals. As described above, both of the data driver SD and the scan driver GD use a shift register circuit SFC for sequentially transferring pulse signals. FIG. 24 shows a shift register circuit SFC. As shown in FIG. 24 , a plurality of latch circuits LATA, LATB are alternately connected to one another in series. In FIG. 24 , a start signal ST corresponds to the signal SSP of FIG. 22 and the signal GSP of FIG. 23 , and a clock signal CLK corresponds to the signal SCK of FIG. 22 and the signal GCK of FIG. 23 . FIG. 25B shows the clock signal CLK to be supplied to the shift register circuit SFC shown in FIG. 24 . In addition to the clock signal CLK, a clock signal/CLK inverted in phase relative to the clock signal CLK is also supplied to the shift register circuit SFC shown in FIG. 24 . FIG. 26 shows the latch circuit LATA forming part of the shift register circuit SFC. FIG. 27 shows the latch circuit LATB forming part of the shift register circuit SFC. Each of the latch circuit LATA and the latch circuit LATB has one inverter and two clocked inverters CICA and CICB. Clock signals CLK and/CLK opposite in phase to each other are supplied to the two clocked inverters CICA and CICB. FIG. 28 shows the clocked inverter CICA, and FIG. 29 shows the clocked inverter CICB. For example, in the clocked inverter CICA, when the clock signal CLK is at a high level, an inverted signal of a signal supplied to an input terminal IN of the clocked inverter CICA is output from an output terminal OUT of the clocked inverter CICA. Also, in the clocked inverter CICB, when the clock signal CLK is at a low level, an inverted signal of a signal supplied to an input terminal IN of the clocked inverter CICB is output from an output terminal OUT of the clocked inverter CICB. It is noted that in referring to a shift register circuit or a latch circuit in the present specification and the accompanying drawings, because clock signals opposite in phase to each other are supplied to those circuits, the description therefor is, in some cases, made by using only one CLK of these clock signals. In the shift register circuit SFC shown in FIG. 24 , because the clock signals CLK, /CLK are supplied to all the latch circuits LATA, LATB, the load of the clock signal lines CLKL, /CLKL becomes extremely large. As a result, external ICs (controller IC and the like) having large driving power need to be used in order to drive the clock signal lines CLKL, /CLKL, which would lead to increase in fabricating costs of the LCD device as well as increase in power consumption of the LCD devices. Japanese Patent Laid-Open Publication HEI 3-147598 (JP-A-3-147598) discloses an arrangement that only when output of stages (latch circuit) of the shift register circuit is significant (active), the clock signal is supplied to those latch circuits in order to reduce the load of the clock signal lines. More specifically, it is controlled by output signals of the individual latch circuits (or a sum signal of output signals of a plurality of adjacent latch circuits) whether or not the clock signal line and the latch circuit are disconnected from each other. However, in such an arrangement, upon power-on, since the internal node state (voltage level) of the shift register circuit is unstable (meaning that the internal node can take any state), it could be the case, in the worst, that all the internal nodes of the shift register circuit go active at the power-on. This state will continue until a signal corresponding to the inactive state scans all the stages of the shift register circuit (i.e., until the shift register circuit is initialized). Further, in that state, since the clock signal has been supplied to all the latch circuits, the load of the clock signal lines has become extremely large, as compared with the normal state (i.e., a state in which a clock signal is supplied to one to a few latch circuits when one pulse signal scans the shift register circuit). Therefore, with insufficient driving power (i.e., with the external IC optimized for small load), the clock signal lines could not be driven within a specified time duration, in which case the shift register circuit might be disabled. Accordingly, the external IC for supplying the clock signal is required to have such power as to enable the driving even for such a large load, whereas in the normal state, the load is small and such a large driving power is unnecessary. That is, the external IC needs to have a large driving power only for the initialization of the shift register circuit upon power-on, which has been an obstacle to an progress toward lower cost and lower power consumption. Japanese Patent Laid-Open Publication HEI 7-147659 (JP-A-7-147659) discloses a liquid crystal panel driver which drives an LCD device to perform black display in upper and lower parts of its screen. The term “black display” refers to a display as shown in FIG. 32 . In this liquid crystal panel driver, based on a vertical synchronous signal Vsync, a timing control circuit generates a gate clock signal GCLK, the frequency of which is same as the clock rate of an input video signal during the video effective period, as shown in FIGS. 33A , 33 B and 33 C. Meanwhile, during a return period between the video effective periods (vertical scan periods), the frequency of the gate clock signal GCLK is higher than the horizontal synchronous frequency. Then, during the return period, a black level is given to a data driver as a video signal. In this way, necessary black display is performed during a short return period. As is well known, liquid crystals need to be driven by AC voltage. Therefore, most liquid crystal panel drivers implement the drive by inverting the polarity of a voltage to be applied, every vertical scan line. In the aforementioned liquid crystal panel driver, for implementation of black display for a total of N horizontal lines in an upper black display area located in the upper part of the screen and a lower black display area in the lower part of the screen, the N horizontal lines are scanned during the return period as shown in FIGS. 33A–33C . However, in the case where the voltage to be applied is inverted in polarity every vertical scan line as described above, if the black display area is increased so that the value of N is increased, the frequency of the applied voltage becomes extremely high. In this case, it is difficult to accomplish the polarity inversion every vertical scan line. Thus, in such a case, the applied voltage will have to be inverted every black display area, although this may cause occurrence of flickers. Each time one vertical scan line is selected, a video signal of the black level voltage is output from the data driver. However, the output time of the black level voltage becomes shorter as N becomes larger, which makes it impossible to write the black level voltage enough into the vertical scan lines. Therefore, for example, whereas a black level voltage sampled by the data driver is written into pixels, as it is, at the first horizontal line out of n horizontal lines of the upper black display area, the sampled black level voltage would gradually decrease at the following horizontal lines so that the black level voltage would largely differ between the first horizontal line and the nth horizontal line. As a result, as shown in FIG. 34 , uniform solid black display is not performed in the black display area, but gradations appear. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is a first object of the present invention to provide an improvement on a shift register circuit arranged such that a clock signal is supplied locally for alleviation of the load on the clock signal line, the improvement being capable to operate normally even upon power-on, and also to provide an image display device which is provided with the improved shift register as part of a driver to realize reduction in power consumption and costs In order to achieve the object, a shift register circuit according to an aspect of the present invention comprises a plurality of latch circuits connected in series to sequentially transfer a pulse signal from one to another, a clock signal line transmitting a clock signal, and a plurality of switching circuits performing electrical connection and disconnection between the clock signal line and the plurality of latch circuits, and upon power-on, at least one of the switching circuits electrically disconnects at least one corresponding latch circuit from the clock signal line. In this shift register circuit, potentials at nodes of the plurality of latch circuits vary in accordance with the pulse signal transferred. The plurality of switching circuits each connect or disconnect corresponding latch circuits to or from the clock signal line in accordance with the potentials at the nodes of the corresponding latch circuits. In this shift register circuit, in which the clock signal is selectively supplied to only an active latch circuit and its neighboring latch circuits, the potential levels of the internal nodes of, for example, all the latch circuits are initialized upon turning on the power. The internal nodes of the shift register tend to become unstable especially immediately after the power is turned on. By limiting the initialization of the potential levels to the power-on time, there is no possibility that the initialization affects an operation in a normal operation period. With this arrangement, the load of the clock signal line is reduced, so that an external IC supplying a clock signal is not required to have a very large drive power. As a result, it is possible to produce such external ICs at lower costs and reduce power consumption. Furthermore, in this shift register circuit, in at least part of a period in which the pulse signal is transferred from a first latch circuit through a last latch circuit, the clock signal has a frequency which is lower than in a normal operation period and which gradually increases. Such a control of the clock signal for the initialization of the shift register circuit is achieved only by changing a timing (frequency) of a clock signal supplied from outside, and without requiring any additional circuit specialized for the initialization. Because the frequency of the clock signal used for the initialization is made to gradually increase, it is possible to complete the initialization in a shorter time than when a constant low frequency is used. Accordingly, other operations do not suffer from any restrictions or obstructions. In order to achieve the above object, there is also provided a shift register circuit, comprising: a plurality of latch circuits connected in series to sequentially transfer a pulse signal from one to another; a clock line transmitting a clock signal; and a plurality of switching circuits performing electrical connection and disconnection between the clock line and the plurality of latch circuits, wherein at least one of the switching circuits electrically disconnects at least one of the plurality of latch circuits from the clock line at regular intervals. In this shift register circuit as well, potentials at nodes of the plurality of latch circuits vary in accordance with the pulse signal transferred, and the plurality of switching circuits may connect or disconnect corresponding latch circuits to or from the clock line in accordance with the potentials at the nodes of the corresponding latch circuits. Then, in at least part of a period in which the pulse signal is transferred from a first latch circuit through a last latch circuit, the clock signal may preferably have a frequency lower than in a normal operation period. In addition, preferably, the frequency of the clock signal may gradually increases in the at least part of the period. In the shift register circuits according to the first and second aspects of the invention, the frequency of the clock signal in the at least part of the period can be from ½ to 1/16 of a frequency of the clock signal in the normal operation period. Because the time during which the shift register operates at such a low frequency of the clock signal is not very long, it is possible to suppress influences of the operation at the low frequency upon other operations. A frequency which is 1/n (n is an integer) of an original frequency can be readily obtained by frequency-dividing a normal clock signal. In either of the above shift register circuits, each latch circuit may have an internal node initialization circuit to which an initialization signal is supplied from outside. The initialization circuit will initialize the internal node of the latch circuit in response to the initialization signal. With such an arrangement, all the latch circuits can be initialized at the same time. Thus, the initialization time can be made shorter, and advantageously, it is less possible that the initialization operation affects other operations. The clock signal may have an amplitude smaller than an amplitude of a power-supply voltage of the shift register circuit. With this arrangement, a device size of the latch circuit receiving the clock signal tends to be large and thus the load is also large accordingly. In this case, adopting the design to supply the clock signal selectively to the latch circuits is very effective and advantageous. Either of the above shift register circuits may have a buffer circuit supplying the plurality of latch circuits with a clock signal received from outside. With this arrangement, by inputting only one of clock signals from outside, its inverse signal can be generated internally. Accordingly, this arrangement is effective in reducing terminals and external ICs. The size (drive power) of the buffer circuit depends on the load of the clock signal line. Therefore, reduction of the effective load will reduce the size of the buffer circuit. Furthermore, in either of the above shift registers, the clock signal received from outside may have an amplitude different from an amplitude of the clock signal supplied to the plurality of latch circuits, and the shift register circuit may further comprise a level shifter changing the amplitude of the clock signal received from outside. The size of such a level shifter and of the buffer circuit, which may be placed after the level shifter, depends on the load of the clock signal line. Accordingly, reduction of the effective load will lead to reduction of the size of the level shifter and/or the buffer circuit. Provision of the level shifter in the shift register circuit allows the voltage level of an input signal thereto to be lower than a drive voltage of the shift register circuit. Thus, it is possible to dispense with an external level shifting IC, which will lead to reduction of the external power consumption. According to a further aspect of the present invention, there is provided an image display device of active matrix type comprising any one of the aforementioned shift register circuit. More specifically, the image display device comprises: a plurality of pixels arranged in a matrix form; a data signal line supplying video data to be written to one of the plurality of pixels; a scan signal line for controlling the writing of the video data to one of the plurality of pixels; a data driver supplying the video signal to the data signal line in synchronization with a timing signal; and a scan driver supplying a pulse signal to the scan signal line in synchronization with a timing signal, wherein at least one of the data driver and the scan driver comprises any one of the above shift register circuits. For the reasons described above, if the scan driver has the shift register, it is possible to keep down the driving power of the external IC driving the clock signal line to be input to the scan driver while achieving a normal operation of the shift register circuit. Accordingly, it is possible to realize a high-definition image display device which is produced at lower costs and consumes less electricity. Similarly, if the data driver has the shift register, it is also possible to keep down the driving power of the external IC driving the clock signal line to be input to the data driver while achieving a normal operation of the shift register circuit. Accordingly, it is possible to realize a high-definition image display device which is produced at lower costs and consumes less electricity. In particular, in the case of the data driver, which is a part having a highest operational frequency in the image display device, reduction of the load of the clock signal line has a large effect. In one embodiment, the potential levels at each of the internal nodes of all the latch circuits in the shift register circuit of the data driver are initialized in synchronization with a vertical synchronous signal. With such an arrangement, either the vertical synchronous signal or a start signal for the scan driver generated from the vertical synchronous signal can be used as a signal triggering the initialization, so that no additional signal is required. In one embodiment, active devices included at least in the data driver comprise polysilicon thin-film transistors. Because the transistors are formed of a polysilicon thin-film, they have a characteristic of extremely high driving power, as compared with amorphous silicon thin-film transistors. As a result, in addition to the foregoing effects and advantages, there is an additional advantage that it is easy to form the pixels and the data driver on a same substrate. Thus, it is expected that production costs and assembly costs are reduced and that the non-defective assembly rate is increased. Furthermore, the driving power of the polysilicon thin-film transistor is smaller than the driving power of the amorphous silicon thin-film transistor by one or two orders of magnitude. Therefore, if the polysilicon thin-film transistors are used for both the scan driver and the data driver, it is necessary to form the transistors in increased size. This will lead to increase in the load of the clock signal line. Thus, the arrangement of this embodiment, from which the above effects are anticipated, is very effectual. If the polysilicon thin-film transistors are used further for the level shifter and/or the buffer circuit for the clock signal line, the initialization intended for decrease of the load of the clock signal line is very effectual and advantageous. If the polysilicon thin-film transistors are formed at a process temperature of 600° C. or lower, it is possible to use glass which has a low distortion temperature, but is cheap and easy to form a larger substrate. Accordingly, in addition to the above advantages, it is possible to, advantageously, produce a large-sized image display device at lower costs. A second object of the present invention is to provide a driving method for LCD devices which enables high-definition black display in, for example, upper and lower positions of a screen and which prevents drivers from malfunctioning. In order to achieve the object, according to a further aspect of the present invention, there is provided a driving method for an active-matrix liquid crystal display device, in which a pixel electrode is connected to a data signal line by a switching device based on a control signal supplied from a scan driver, and a data signal output from a data driver is supplied to the pixel electrode through the data signal line, so that a picture based on the data signal is displayed by a pixel matrix, wherein: in performing black display in an upper black display area provided in an upper position of a screen and in a lower black display area provided in a lower position of the screen, a stabilization period is provided, in one vertical scan period, between a first black display period in which black display is performed in the upper black display area and a video display period in which video display is performed in a video display area below the upper black display area and between the video display period and a second black display period in which black display is performed in the lower black display area below the video display area, the stabilization period being a period in which a frequency of a clock signal for operating a shift register included in the data driver is made lower than a frequency of the clock signal in the video display period such that a potential level at an internal node of the shift register is stabilized. This driving method is applicable to, for example, LCD devices having the conventional circuitry as shown in FIGS. 19 and 20 . With this driving method, in one vertical scan period, a stabilization period is provided between the video display period in which a picture is displayed in a middle zone of the screen and each of the first and second black display periods in which a black color is displayed in the upper and lower zones of the screen, respectively, and the frequency of the clock signal in the data driver is made lower in the stabilization period than in the video display period, whereby the potential level of an internal node of the shift register circuit in the data driver is stabilized. In this way, in a plurality of latch circuits included in the shift register, potential levels at their internal nodes are prevented from becoming unstable. If the frequency of the clock signal of the data driver in the stabilization period is from ½ to 1/32 of a frequency in the video display period, it is possible to surely stabilize all the internal nodes in the shift register circuit of the data driver. If a frequency of a clock signal in the scan driver is made higher in the black display periods than in the video display period, it is possible to surely display the black color in the upper and lower black display areas. Further, if an analog switching section included in the data driver to sample the data signal is always placed in an on state during the black display periods, horizontal lines in the black display areas will have an identical potential level. As a result, an uniform and stable black display is achieved. In one embodiment, the frequency of the clock signal for operating the shift register circuit in the scan driver in the first and second black display periods is 1.5–10 times as high as the frequency in the video display period With this arrangement, in displaying a picture at an aspect ratio of about 16:9 on a screen of an aspect ration of about 4:3, it is possible to well and surely perform a black display in the upper and lower black display areas and a video display in the video display area. In addition, polarity inversion of a voltage applied to the data signal line is well performed. The driving method of the invention can be used not only in an LCD device having shift register circuits both of which require stabilization of the internal node potential level, but also in an LCD device having shift register circuits both of which require no stabilization of the internal node potential level, and in an LCD device having both a shift register requiring stabilization of the internal node potential level and a shift register requiring no stabilization of the internal node potential level as well. In other words, the driving method of the invention can be used for an LCD device wherein at least one of a scan driver and a data driver has a shift register which comprises a plurality of latch circuits connected in series to transfer a pulse signal from one to another in synchronization with a clock signal and is designed such that the clock signal is supplied to only a latch circuit in which a pulse of the pulse signal is present and its neighboring latch circuits, as well as for an LCD device wherein at least one of a scan driver and a data driver has a shift register designed such that the clock signal is supplied to all the latch circuits. Other objects, features and advantages of the present invention will be obvious from the following description. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a shift register circuit according to an embodiment of the invention; FIGS. 2A , 2 B and 2 C show supply voltage Vcc, an example of a clock signal CLK supplied to the shift register circuit, and a clock signal CLKint inside the shift register circuit, respectively; FIGS. 3A , 3 B and 3 C show supply voltage Vcc, an example of a clock signal CLK supplied to the shift register circuit with the use of a clock signal supplying IC having large driving power, and a clock signal CLKint inside the shift register circuit, respectively; FIGS. 4A and 4B show supply voltage Vcc and a clock signal CLK received by the shift register circuit, respectively; FIGS. 5A , 5 B, 5 C and 5 D show supply voltage Vcc, a pulse signal PLS, an example of the clock signal CLK and an example of the clock signal CLKint inside the shift register circuit during an initialization period and a normal operation period, respectively; FIGS. 6A and 6B show supply voltage Vcc and a clock signal whose frequency at power-on is lower than its frequency at an end of the initialization period, respectively; FIGS. 7A , 7 B and 7 C show supply voltage Vcc, a pulse signal PLS and another example of the clock signal for driving the shift register circuit; FIG. 8 shows an example of circuitry of the latch circuit in the shift register circuit; FIG. 9 shows another example of circuitry of the latch circuit in the shift register circuit; FIGS. 10A , 10 B and 10 C show supply voltage Vcc, and an example of a reset signal RST and an example of the clock signal CLK with the use of the latch circuits shown in FIGS. 8 and 9 , respectively; FIGS. 11A , 11 B and 11 C show supply voltage Vcc, and another example of the reset signal RST and another example of the clock signal CLK with the use of the latch circuits shown in FIGS. 8 and 9 , respectively; FIG. 12 shows still another example of circuitry of the latch circuit in the shift register circuit; FIG. 13 shows still another example of circuitry of the latch circuit in the shift register circuit; FIG. 14 shows a shift register circuit according to another embodiment; FIG. 15 shows a shift register circuit according to still another embodiment; FIG. 16A shows an active matrix-driven LCD as an example of the image display apparatus equipped with the shift register circuit of the invention; FIG. 16B shows another example of the image display apparatus equipped with the shift register circuit of the invention; FIG. 17 is a view showing a structure example of a polysilicon thin-film transistor included in the shift register circuit according to an embodiment; FIGS. 18A , 18 B, 18 C, 18 D, 18 E, 18 F, 18 G, 18 H, 18 I, 18 J and 18 K are fabrication process diagrams of the polysilicon thin-film transistor; FIG. 19 shows a conventional active matrix-driven LCD device; FIG. 20 details a pixel PIX shown in FIG. 19 ; FIG. 21 shows another conventional active matrix-driven LCD device; FIG. 22 shows a data driver of the dot sequential drive system; FIG. 23 shows a scan driver of the dot sequential drive system; FIG. 24 shows a conventional shift register circuit; FIGS. 25A and 25B show supply voltage and a clock signal CLK supplied to the shift register circuit shown in FIG. 24 , respectively; FIG. 26 shows a latch circuit partly constituting the shift register circuit of FIG. 24 ; FIG. 27 shows another latch circuit partly constituting the shift register circuit of FIG. 24 ; FIG. 28 is a circuit diagram of a clocked inverter used in the latch circuits of FIGS. 26 and 27 ; FIG. 29 is a circuit diagram of another clocked inverter used in the latch circuits of FIGS. 26 and 27 ; FIGS. 30A , 30 B, 30 C, 30 D and 30 E are timing charts of one vertical scan period of individual signals for realizing the drive method for LCDs according of the invention; FIGS. 31A , 31 B, 31 C, 31 D and 31 E are timing charts different from FIGS. 30A–30E ; FIG. 32 shows an example of the screen in which black display is given in upper and lower parts; FIGS. 33A , 33 B and 33 C are timing charts of individual signals in the case where black display is performed in upper and lower parts of the screen by a conventional liquid crystal panel drive circuit; and FIG. 34 is an explanatory view of gradation that would appear in a wide black display area when the conventional liquid crystal panel drive circuit is used. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a shift register circuit 1 according to an embodiment of the invention. The shift register circuit 1 is made up of a plurality of latch circuits LATA, LATB having the arrangement shown in FIGS. 26 and 27 , a plurality of logical OR circuits OR, and a plurality of switches ASW. The foremost latch circuit of the shift register circuit 1 shown in FIG. 1 may be either a latch circuit LATA or a latch circuit LATB, and this is determined depending on an input clock signal. It is controlled by the logical OR circuits OR and the switches ASW whether or not clock signals CLK, /CLK are input to the latch circuits LATA, LATB. For example, a logical OR circuit OR belonging to one unit 2 receives a signal output from a latch circuit of a preceding stage to a latch circuit belonging to the one unit 2 as well as a signal output from the latch circuit belonging to the one unit 2 , and then computes a logical OR of those signals. Based on a signal which indicates a result of the computation, a switch ASW belonging to the one unit 2 goes conducting, or closed, so that clock signals CLK, /CLK are supplied to the latch circuit belonging to the one unit 2 . That is, a clock signal is input into a latch circuit belonging to one unit 2 only when at least one of this latch circuit or a latch circuit of the preceding stage is active. By this arrangement, most of the latch circuits are disconnected from the clock signal lines CLKL, /CLKL. As a result of this, loads of the clock signal lines CLKL, /CLKL become very small, compared with the shift register circuit SFC shown in FIG. 24 . Therefore, the shift register circuit 1 is allowed to use a clock signal supply IC of small driving power. However, as described before, at power-on, the state (potential level) of internal nodes of the latch circuits LATA, LATB becomes unstable. That is, the internal nodes of the latch circuits LATA, LATB can take any state. For this reason, there is a fear that all or most of the nodes of the latch circuits LATA, LATB become active. If all the nodes of the latch circuits LATA, LATB become active, the clock signal lines CLKL, /CLKL are connected to all the latch circuits LATA, LATB. The load of the clock signal lines CLKL, /CLKL in the state that all the latch circuits LATA, LATB are active is very large, as compared with the other states. If all the nodes of the latch circuits LATA, LATB are active, there is a possibility that a clock signal supply IC having such a driving power as to only perform a normal operation can no longer drive the shift register circuit. This is explained in more detail with reference to FIGS. 2A–2C . FIGS. 2A , 2 B and 2 C show a supply voltage, an example of a clock signal CLK supplied to the shift register circuit 1 and a clock signal CLKint inside the shift register circuit, respectively. In the state that the nodes of all the latch circuits LATA, LATB are active, because of a large load of the clock signal lines CLKL, /CLKL, the clock signal CLKint inside the shift register circuit shown in FIG. 2C is dulled in waveform, as compared with the clock signal CLK supplied to the shift register circuit. On this account, an amplitude enough to drive the shift register circuit cannot be ensured. As a result, the shift register circuit would not operate. In other words, the level of the internal nodes of the latch circuits LATA, LATB does not change. Therefore, the load of each of the clock signal lines CLKL, /CLKL continues assuming a large value, so that the shift register circuit cannot start operating. However, in the case of large load of the clock signal lines CLKL, /CLKL, if a clock signal supply IC having such power as can drive the clock signal lines CLKL, /CLKL is used, the shift register circuit operates. FIGS. 3B and 3C show an example of the clock signal CLK supplied to the shift register circuit with the use of a clock signal supplying IC having large driving power, and the clock signal CLKint inside the shift register circuit, respectively. Such large driving power is not required in a normal operating state, only entailing an increase in power consumption. Besides, a clock signal supply IC having large driving power naturally has a demerit of high cost. By lowering the frequency of the clock signal CLK during the initialization period below the frequency of the clock signal CLK during the normal operation period without changing the crest to trough ratio of pulses as shown in FIG. 4B , the problem that an amplitude large enough to drive the shift register circuit cannot be ensured can be solved even if a clock signal supply IC having small driving power is used. The term “initialization period”, in this embodiment, refers to a time period corresponding to a specified time elapse from power-on. The term “normal operation period” refers to periods other than the initialization period. FIGS. 5C and 5D show an example of the clock signal CLK and an example of the clock signal CLKint inside the shift register circuit 1 during the initialization period and the normal operation period. As shown in FIGS. 5C and 5D , the leading edge of the clock signal CLKint indeed is not sharp due to the load of the clock signal lines CLKL, /CLKL, yet it becomes over a specified level (threshold), so that the shift register circuit operates normally. Also, the shift register circuit 1 , upon entering the initialization period, reduces the clock frequency for a specified period. On this account, even if all the latch circuits LATA, LATB are active, the latch circuits LATA, LATB are disconnected from the clock signal lines CLKL, /CLKL successively from the first stage as the shift register circuit 1 is progressively initialized. Therefore, the load of the clock signal lines CLKL, /CLKL lowers gradually. It is noted that the frequency of the clock signal lines CLKL, /CLKL at power-on is determined depending on how much the load of the clock signal lines CLKL, /CLKL increases, and generally may be about ½ to 1/16 of the frequency of the clock signal lines CLKL, /CLKL during the normal operation period. Although the frequencies of the clock signals for initialization shown in FIGS. 4 and 5 are constants the frequency of the clock signal does not necessarily need to be constant. For example, the frequency of the clock signal for initialization may vary gradually. FIG. 6B shows a clock signal CLK whose frequency at power-on is lower than the frequency at an end of an initialization period. As an example, the clock frequency at power-on is ⅛ the frequency of the clock signal CLK during the normal operation period, the frequency of the clock signal CLK gradually increases, and the clock frequency at the end of the initialization becomes the frequency of the clock signal CLK during the normal operation period. For example, even if all the latch circuits LATA, LATB are active, the latch circuits LATA, LATB are disconnected from the clock signal lines CLKL, /CLKL successively from the first stage on as the shift register circuit 1 is progressively initialized, so that the load of the clock signal lines CLKL, /CLKL becomes gradually smaller. Therefore, even with increasing frequency, the shift register circuit can sufficiently be driven. By gradually increasing the frequency of the clock signal lines CLKL, /CLKL, the initialization period required for the initialization can be shortened. The frequency of the clock signals may be increased either continuously or discontinuously in several clock pulses. FIG. 7C shows another clock signal for driving the shift register circuit 1 . In the clock signal shown in FIG. 7C , the frequency is decreased in synchronization with an arbitrary pulse signal PLS supplied cyclically ( FIG. 7B ) and the decreased frequency is kept for a specified period. Therefore, the shift register circuit 1 is initialized every cycle. Even with the use of a clock signal supply IC having small driving power, the shift register circuit 1 operates normally. The cycle time may be a period for one frame of a picture. FIGS. 8 and 9 show other examples of the latch circuits of the shift register circuit 1 as LATA 1 , LATB 1 . In the latch circuits LATA 1 , LATB 1 , the internal nodes are forcedly reset. As a result of the reset, for example, signals output from the latch circuits go low level. FIGS. 10B , 10 C and FIGS. 11B , 11 C show clock signals CLK and reset signals RST for the latch circuits LATA 1 , LATB 1 . In the example of the signal waveform shown in FIGS. 10A–10C , the reset signal RST is supplied to the latch circuits LATA 1 , LATB 1 only when power is turned on, whereby the internal nodes of those latch circuits are initialized. In the example of the signal waveform shown in FIGS. 11A–11C , the reset signal RST is supplied to the latch circuits LATA 1 , LATB 1 in synchronization with the pulse signal PLS supplied cyclically at regular intervals, whereby the internal nodes of those latch circuits are initialized. As described above, by initializing the shift register circuit 1 , it becomes possible for the shift register circuit 1 to implement normal operation even with the use of a clock signal supply IC having small driving power. The cycle time may be a time period for one frame of a picture, as already described. FIGS. 12 and 13 show other circuitry examples of the latch circuits of the shift register circuit 1 as LATA 2 , LATB 2 . The latch circuits LATA 2 , LATB 2 each have transistors M 1 –M 8 . The clock signal to be supplied to the shift register circuit 1 having the latch circuits LATA 2 , LATB 2 may be a clock signal shown in FIG. 4 or FIG. 7 . The latch circuits LATA 2 , LATB 2 have a level shifting function. Even if a clock signal having an amplitude smaller than a voltage difference between a supply voltage Vcc and a ground voltage GND is supplied to the latch circuits LATA 2 , LATB 2 , the latch circuits LATA 2 , LATB 2 output signals having an amplitude equal to the voltage difference between the voltages Vcc and GND. For example, in the case where the supply voltage for the latch circuits LATA 2 , LATB 2 is 0 V/15 V, even if the clock signal line has a 0 V/5 V amplitude, signals having a 0 V/15 V amplitude are supplied from the latch circuits LATA 2 , LATB 2 . For the latch circuits LATA 2 , LATB 2 , it is necessary to reduce the on-resistance of the current path on the GND side. To achieve this, the size (channel width) of the transistors M 4 , M 6 , to which the clock signal is supplied, has to be increased. This leads to quite a large magnitude of the input current to the latch circuits, as viewed from the clock signal line. Thus, reduction in signal line load by locally supplying the clock signal is very significant and advantageous in the shift register circuit of the invention. Further, in the case where all the latch circuits are connected to the clock signal line, the effect of increase in load becomes so large that the effectiveness of the initialization of the shift register circuit becomes very large. FIG. 14 shows a shift register circuit 10 according to another embodiment. The shift register circuit 10 has a plurality of he latch circuits LATA, LATB shown in FIGS. 26 and 27 , a plurality of logical OR circuits OR, a plurality of switches ASW and a buffer circuit 11 . Only a signal CLKext, which is one phase of a clock signal, is supplied to the shift register circuit 10 from outside, and clock signals CLK, /CLK are supplied to the latch circuits via the buffer circuit 11 . The buffer circuit 11 has to have at least one inverter circuit INV. In this example, the buffer circuit 11 has three inverter circuits INV. In this embodiment, since the shift register circuit 10 includes the buffer circuit 11 , the number of signal lines connected to the shift register circuit 10 from external can be reduced. FIG. 15 shows still another shift register circuit 20 . The shift register circuit 20 has a plurality of latch circuits LATA, LATB shown in FIGS. 26 and 27 , a plurality of logical OR circuits OR, a plurality of switches ASW, a level shifter LS, and a buffer circuit 21 . The buffer circuit 21 has at least one inverter circuit INV. External clock signals CLKext, /CLKext supplied from external to the shift register circuit 20 have amplitudes smaller than amplitudes of the clock signals CLK, /CLK supplied to the shift register circuit 1 shown in FIG. 1 . The external clock signals CLKext, /CLKext supplied from external are supplied to the latch circuits LATA, LATB via the level shifter LS and the buffer circuit 21 . In the shift register circuit 20 , since the clock signals supplied from external are allowed to have a small amplitude thanks to the level shifter LS, the need of providing any external level shifter IC is eliminated and besides the power consumption can be reduced. If an image display apparatus incorporates the shift register circuit 1 , the shift register circuit 10 or the shift register circuit 20 in its data driver and/or scan driver, power consumption associated with the supply system for supplying clock signals can be reduced. FIG. 16A shows such an image display apparatus 300 . Each of a data driver 301 and a scan driver 302 of this image display apparatus 300 has the shift register circuit 1 , the shift register circuit 10 or the shift register circuit 20 . The circuitry other than the data driver 301 and the scan driver 302 is same as that of the image display apparatus 100 shown in FIG. 19 and so omitted in description. In general, the data driver is driven at frequencies several hundreds to thousands higher than that of the scan driver. Therefore, the effect of implementing the present invention in the data driver is larger than that of implementing the invention in the scan driver, although, needless to say, the invention, even when embodied with a scan driver, is advantageous. The vertical synchronous signal for the image display apparatus (alternatively, a start pulse for the scan driver) is supplied at a frame frequency (normally, 60 Hz). Therefore, this signal may also be used as a synchronizing signal to perform the initialization of the shift register circuit cyclically at regular periods or intervals. Use of the above signal eliminates the need of inputting a signal for specifying the timing of initialization from external of the image display apparatus. FIG. 16B shows an embodiment in which the invention is applied to an image display apparatus in which a data driver and a scan driver are formed on one substrate having pixels formed thereon (monolithic), like the image display apparatus shown in FIG. 21 . The image display apparatus 400 of this figure has the same component parts as in the conventional image display apparatus 200 shown in FIG. 21 , except a data driver 401 and a scan driver 402 . Component parts similar to the conventional ones are designated by the reference numerals of FIG. 21 and a detailed description thereon is omitted. Forming the drivers and the pixels monolithic makes it possible to reduce the fabrication cost and assembly cost of the image display apparatus and to produce an effect on reliability improvement, than making and mounting the drivers and pixels separately. In the image display apparatus 400 shown in FIG. 16B , the pixels PIX, the data driver 401 and the scan driver 402 are formed on the same substrate SUB (driver monolithic structure). The image display apparatus is driven by signals from an external control circuit CTL and driving power from an external supply voltage generator VGEN. Each of the data driver 401 and the scan driver 402 has the shift register circuit 1 , the shift register circuit 10 or the shift register circuit 20 described above. With the above constitution, the data driver 401 and the scan driver 402 are placed over a region generally equal in length to the screen (display area), and so the wiring length for clock signals and the like is extremely long. Therefore, since the load of the clock signal lines or the like is also quite large, the effect of reducing the load of the clock signal lines by locally inputting the clock signals also becomes quite large. FIG. 17 is a view showing an example of the structure of a polysilicon thin-film transistor included in the shift register circuit in the image display apparatus 400 . This polysilicon thin-film transistor is essentially made up of an insulative substrate 31 , silicon oxide 32 , metallic wiring 33 , a source region 34 , a drain region 35 , a polysilicon thin film 36 , a gate insulator 37 , a gate electrode 38 and an interlayer dielectric 39 . The polysilicon thin-film transistor is of a forward staggered (top-gate) structure using the polysilicon thin film on the insulative substrate as an active layer. However, this structure is not limitative, and the transistor may be of other structure such as a reverse staggered structure. By using the polysilicon thin-film transistor shown in FIG. 17 , a scan driver and a data driver having practical driving power can be made up on the substrate on which the pixel arrays are also formed, and by nearly the same fabrication process steps as those for the pixel arrays. Polysilicon thin-film transistors, which are lower in driving power by one to two orders of magnitude than single crystal silicon transistors (MOS transistors), need to be increased in size in implementing a shift register circuit. Thus, the input load tends to be increased accordingly. Therefore, locally inputting the clock signals is very effective in reducing load of the clock signal lines. Fabrication process steps of this polysilicon thin-film transistor are briefly explained with reference to FIGS. 18A–18K . On a glass substrate 31 , silicon oxide 32 is first formed and subsequently an amorphous silicon thin film is deposited ( FIGS. 18A , 18 B). Next, the amorphous silicon thin film is irradiated with excimer laser, forming a polysilicon thin film 36 ( FIG. 18C ). This polysilicon thin film 36 is patterned into a desired shape, by which an active region is formed ( FIG. 18D ), and then a gate insulator 37 made of silicon dioxide is formed ( FIG. 18E ). On this gate insulator 37 , a gate electrode 38 for a thin film transistor is formed of a metal such as aluminum ( FIG. 18F ). Next, impurities, or dopants (phosphorus for an n-type region and boron for a p-type region) are implanted into the polysilicon thin film 36 by using a resist pattern, with the result that a source region 34 and a drain region 35 are formed ( FIGS. 18G , 18 H). Next, an interlayer dielectric 39 made of silicon dioxide or silicon nitride is deposited ( FIG. 18I ). Then, contact holes ranging to the source region and the drain region are formed in the interlayer dielectric 39 and the gate insulator 37 ( FIG. 18J ), and metallic wiring is formed of aluminum or the like in these contact holes ( FIG. 18K ). Thus, the polysilicon thin-film transistor shown in FIG. 17 is completed. Because a temperature 600° C. used during the gate insulator formation process is the highest temperature used in the process steps shown in FIGS. 18A–18K , highly heat-resistant glasses such as 1737 Glass made by Corning Inc. of U.S. may be used as the glass substrate material. For fabrication of an LCD, subsequent to the above process, transparent electrodes (for transmission LCDs) or reflecting electrodes (for reflection LCDs) are formed via another interlayer dielectric. In this connection, because forming the polysilicon thin-film transistors at temperatures below 600° C. in the fabrication process as shown in FIG. 18 makes it possible to employ a low-price, large-area glass substrate, a reduction in price and an increase in area of the image display apparatus can be realized. Although several embodiments of the invention have been shown above, the present invention is not limited to these embodiments, but applicable to other cases such as combinations of the foregoing embodiments. The shift register circuit of the invention, although lending itself to use in various fields, has been described by taking examples of image display apparatus, particularly, LCDs hereinabove. However, the invention can also be utilized for similar objectives in other fields as well. FIGS. 30A–30F are timing charts of signals of a scan driver and a data driver in one vertical scan period for realizing the drive method for an LCD device according to an embodiment of the invention. This embodiment is described on a case where in an LCD device having a screen aspect ratio of generally 4:3, a video signal complying with the NTSC system is displayed at an aspect ratio of generally 16:9 with black display areas provided in upper and lower parts of the screen. However, the invention is not limited to those aspect ratios. The driving method of the embodiment is directed to an active matrix LCD device having the conventional circuitry shown in FIG. 19 . Each of the scan driver and the data driver of this LCD device may have either a shift register circuit designed such that a clock signal is supplied to a latch circuit in which a pulse signal to be transferred is present and its neighboring latch circuits only (e.g., the circuit shown in FIG. 1 ) or a shift register circuit designed such that a clock signal is supplied to all the latch circuits (e.g., the circuit shown in FIG. 24 ). First, for a first black display period in which black display is performed in the upper black display area on the upper side of the screen, the scan driver clock signal for activating the shift register circuit within the scan driver is set to a frequency of 39.4 kHz, 2.5 times as high as the frequency of 15.7 kHz of a video display period in which video, or pictures are displayed in the video display area of the screen. Further, a scan driver start signal to be supplied to the shift register circuit of the scan driver is supplied in synchronization with the leading edge of the vertical synchronous signal as shown in the figure. Although FIGS. 30A–30E take an example in which the shift register circuit is activated in synchronization with leading edges of clock pulses, yet for use of a shift register circuit which is activated in synchronization with trailing edges of the clock pulses, a start signal pulsing at timing appropriate for such a shift register circuit should be used. Also, although the scan driver clock signal during the first black display period is set to a frequency 2.5 times as high as that of the video display period with a view to enhancing the scan rate in this embodiment, yet the multiplier, or multiplication factor involved does not necessarily need to be 2.5 (×2.5). However, since this multiplication factor and the area of the black display area are inversely proportional to each other, there is a need of selecting a multiplication factor that is well balanced in terms of display. In many active matrix type LCDs, because alternating voltage is applied to liquid crystals, it is often the case that the applied voltage is alternated in polarity between positive and negative every vertical scan line. In this case, there is a need of alternating the polarity of the applied voltage every vertical scan line also in doing the black display. Taking this also into consideration, the multiplication factor for the scan driver clock signal needs to be determined so that black display can be done to all the horizontal lines in the upper black display area, and that the polarity of the applied voltage can be alternated every vertical scan line. The multiplication factor in this embodiment is set to 2.5 as described above, where the cycle period per vertical scan is 26.4 μs. If the cycle period is quite shorter than this, the time duration for which the voltage is applied to liquid crystals would be also shortened, which gives rise to a fear of insufficient write. Therefore, taking into consideration factors such as the balance of the black display area as described above, the multiplication factor for the scan driver clock signal is desirably about 1.5 to 10. Also in the first black display period in which black display is made in the screen upper part, the data driver clock signal for operating a shift register circuit within the data driver has a frequency equivalent to the frequency for the video display period. Further, the data driver start signal holds “H” level during the first black display period. In the data driver, a sampling pulse for sampling of video data is created based on the data driver start signal supplied to the shift register circuit. The sampling section, to which the sampling pulse is supplied, detects leading edges of the sampling pulses to do the sampling. In this case, during the first black display period, the data driver start signal is held at “H” level. By so doing, all analog switches of the sampling section are always ON state. As a result, a video signal always having the black level potential is output to all the data signal lines, resulting in that all the horizontal lines assume the same black level voltage even if the number of horizontal lines in the upper black display area becomes large. Therefore, nonuniformities in black display among the horizontal lines during the first black display period are eliminated, and a stable black display is performed. Besides, the voltage level of the internal nodes included in a plurality of latch circuits within the shift register circuit is stabilized. In this embodiment, the sampling section detects leading edges of the sampling pulses to perform sampling, as described above. However, in the case where the sampling section is activated at trailing edges of sampling pulses, the polarity of the data driver start signal to be supplied to the shift register circuit should be altered accordingly, though no large change is needed for the timing itself of the data driver start signal. Next, a first stabilization period after an end of the first black display period is described. In this first stabilization period, the scan driver clock signal to be supplied to the shift register circuit of the scan driver has d.c. components (level “L”) only. That is, during this first stabilization period, the shift register circuit within the scan driver does not operate, and no image data are written to the pixels of the liquid crystal panel. Further, during this period, the frequency of the data driver clock signal supplied to the shift register circuit within the data driver is ¼ the frequency of the data driver clock signal supplied during the video display period and the first black display period. This first stabilization period has a length corresponding to four horizontal scan periods, and in this period a process of stabilizing the voltage level of all the internal nodes of the shift register circuit of the data driver is performed. In this embodiment, the frequency of the data driver clock signal during the first stabilization period is set to ¼ times as high as that of the first black display period and the video display period, and the length of the first stabilization period is set to four horizontal scan periods, as already described. However, these values are nothing but an example. Nonetheless, the multiplication factor for frequency, if extremely large, would make it impossible to stabilize the internal nodes. Extremely small multiplication factors, conversely, would make it impossible to perform the stabilization process for all the internal nodes within one vertical scan period. Thus, the multiplication factor for frequency is desirably set to about ½ to 1/32. Also, the first stabilization period length is desirably set to two to 32 horizontal scan periods or so according to the multiplication factor for frequency. Further, the data driver start signal supplied to the shift register circuit of the data driver during the first stabilization period is a one-pulse signal such that, as shown in FIGS. 30D and 30E , after a sampling pulse has been supplied to the first-stage latch circuit of the shift register circuit based on the data driver clock signal lowered in frequency, no other sampling pulses are inhibited from being supplied thereto until the next video display period. Next, a video display period subsequent to the first stabilization period is described. Video display processing performed during this video display period is basically similar to the conventional video display processing performed by the conventional LCD driving method. However, it is assumed in this embodiment that in an LCD having a screen aspect ratio of roughly 4:3, a video signal complying with the NTSC system is displayed at an aspect ratio of roughly 16:9 for the video display area, with black display areas provided in upper and lower parts of the screen. Therefore, if an LCD having 230 scan signal lines is used, the number of scan signal lines in the video display area is generally around 170 because of the presence of the black display areas in upper and lower parts of the screen. However, since the video signal complies with the NTSC system, there arises a need of taking measures such as decimating the generally 230 effective horizontal scan lines and displaying a video image by using the remaining horizontal scan lines, or once writing the video signal complying with the NTSC system based on a write clock to a video field memory or the like and then reconstructing the video signal with a read clock of a frequency lower than the write clock. These techniques are well known and description about these is omitted here. Next, a second stabilization period subsequent to the video display period is described. Basically, the scan driver clock signal and the scan driver start signal to be supplied to the shift register circuit of the scan driver as well as the data driver clock signal and the data driver start signal to be supplied to the shift register circuit of the data driver are the same as those of the above-described first stabilization period. However, if there is no problem in terms of display, the data driver start signal to be supplied may be a signal having a polarity reverse to that in the first stabilization period ( FIG. 30 shows a case of reverse polarity). Also, the frequency of the data driver clock signal does not need to be the same as the frequency of the first stabilization period, and may be changed to any arbitrary frequency different from that of the first stabilization period. Next, a second black display period in which black display is performed in the lower black display area on the lower side of the screen subsequent to the second stabilization period is described. The scan driver clock signal and the scan driver start signal as well as the data driver clock signal and the data driver start signal for this second black display period may be the same as those of the first black display period. Further, the frequency of the scan driver clock signal may differ from the frequency of the first black display period unless the upper and lower black display areas go off-balance in breadth. As described above, in this embodiment, a first stabilization period is provided between a first black display period for performing black display in the upper black display area in upper part of the screen, and a video display period for displaying pictures in the video display area adjoining the upper black display area. Further, a second stabilization period is provided between the video display period and a second black display period for performing black display in the lower black display area adjoining the video display area. Then, during these stabilization periods, the operation of the shift register circuit of the scan driver is halted, while the frequency of the data driver clock signal is lowered to, for example, ¼ the frequency used in the first, second black display periods and the video display period. Thus, the voltage level of all the internal nodes of the shift register circuit of the data driver is stabilized. In the first black display period and the second black display period, the frequency of the scan driver clock signal is set to, for example, 2.5 times as high as the frequency of the video display period with a view to obtaining a higher scan rate, so that black display is securely implemented in the upper and lower black display areas. Further, the frequency of the data driver clock signal for these black display periods is set equivalent to the frequency for the video display period, while the data driver start signal is held at “H” level (or “L” level) By so doing, analog switches provided within the data driver for sampling the video signal are normally held at ON state, so that nonuniformities in black display during the first and second black display periods can be eliminated, and that a stable black display can be performed. Besides, the voltage level of the internal nodes included in a plurality of latch circuits within the shift register circuit is stabilized. Consequently, according to this embodiment, in performing black display in upper and lower parts of the display screen, a high-grade, stable black display free from black-display nonuniformities is achieved. Also, the voltage level of the internal nodes within the data driver is stabilized, and as a result, malfunctions of the data driver can be prevented. One example of the LCD driving method of the invention has been described as being directed to an LCD which requires the stabilization of internal nodes in the shift register circuit of the data driver, but the same driving method may be introduced into LCDs which do not require such processing, without any changes. Thus, LCD drivers employing the driving method of the embodiment can be used in LCD devices of any type. If such LCD drivers are prepared beforehand, they have only to be connected to desired LCD devices. As shown above, this embodiment has been described on a case where in an LCD having a screen aspect ratio of about 4:3, a video signal complying with the NTSC system is displayed at an aspect ratio of about 16:9 for the video display area with black display areas provided in upper and lower parts. However, in the case where the two aspect ratios are other than the above values and moreover the black display areas provided in upper and lower parts of the screen are relatively small, the frequency of the scan driver clock signal does not need to be as high as the frequency shown in FIG. 30C during the first and second black display periods, as is obvious from FIG. 31C . where similar effects can be obtained even if the shift register circuit of the scan driver is driven by the clock signal of a frequency same as that for the video display period. In the above embodiment a video signal of the NTSC system is used, although the invention may be applied also to other video signals such as the PAL system, the SECAM system, and besides, VGA (video graphics array) and XGA (extended graphics array) systems that are video formats for personal computers. To mention additionally, in various video signal formats such as the NTSC system, it is often the case that the signal level in an area corresponding to a vertical return period is generally at black level. Therefore, the above embodiment has been described by taking an example in which the vertical return period is utilized as it is. However, if a more assurable black level period is required, black level periods may be inserted positively into the vertical return periods. Further, LCDs, to which the driving method in this embodiment is applicable, are not particularly limited. The invention may be applied to any active matrix LCD in which pixel electrodes are connected to data signal lines by switching devices based on a control signal output from the scan driver and a video signal output from the data driver is supplied to the pixel electrodes via the data signal lines, and pictures based on the video signal are displayed at the pixel matrix. In such a case, at least one of the scan driver and the data driver may share the substrate with the pixel electrodes, so that the LCD can be downsized and reduced in cost (see FIG. 16B and FIG. 21 ). Also, the polysilicon thin-film transistors as the switching devices may be formed on a glass substrate at temperatures below 600° C., so that high-definition display and lower cost can be achieved. Such polysilicon thin films can be formed by using the process described before with reference to FIGS. 18A–18K . The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

A shift register circuit includes a plurality of latch circuits connected in series to sequentially transfer a pulse signal ST from one to another, a clock signal line transmitting a clock signal CLK, and a plurality of switching circuits performing electrical connection and disconnection between the clock signal line and the plurality of latch circuits. Upon turning on the shift register, at least one of the switching circuits electrically disconnects at least one of the latch circuits from the clock signal line. During an initialization period immediately after power has been turned on, the frequency of the clock signal CLK is lower than in a normal operation period and gradually increases toward the frequency used in the normal operation period.

[0001] This application claims benefit of U.S. Provisional Application Nos. 60/294,682, filed May 31, 2001, and 60/345,630, filed Jan. 3, 2002, the entirety of each of which is incorporated by reference herein. [0002] Pursuant to 35 U.S.C. §202(c), it is acknowledged that the U.S. Government has certain rights in the invention described herein, which was made in part with funds from the National Institutes of Health, Grant No. GM59348-02. FIELD OF THE INVENTION [0003] The present invention relates to the field of drug design and development for prevention and treatment of cell proliferative disease. Specifically, the invention features an assay for identifying peptides and peptidomimetics for promoting apotosis in cells, through a pathway involving the Inhibitor of Apoptosis Proteins (IAPs), exemplified by XIAP, and the mitochondrial protein Smac/DIABOLO (hereinafter Smac). The invention also features peptides and peptidomimetics identified through the use of the assay. BACKGROUND OF THE INVENTION [0004] Various scientific articles, patents and other publications are referred to throughout the specification. Each of these publications is incorporated by reference herein in its entirety. [0005] Apoptosis (programmed cell death) plays a central role in the development and homeostasis of all multi-cellular organisms. Alterations in apoptotic pathways have been implicated in many types of human pathologies, including developmental disorders, cancer, autoimmune diseases, as well as neuro-degenerative disorders. [0006] Thus, the programmed cell death pathways have become attractive targets for development of therapeutic agents. In particular, since it is conceptually easier to kill than to sustain cells, attention has been focused on anti-cancer therapies using pro-apoptotic agents such as conventional radiation and chemo-therapy. These treatments are generally believed to trigger activation of the mitochondria-mediated apoptotic pathways. However, these therapies lack molecular specificity, and more specific molecular targets are needed. [0007] Apoptosis is executed primarily by activated caspases, a family of cysteine proteases with aspartate specificity in their substrates. Caspases are produced in cells as catalytically inactive zymogens and must be proteolytically processed to become active proteases during apoptosis. In normal surviving cells that have not received an apoptotic stimulus, most caspases remain inactive. Even if some caspases are aberrantly activated, their proteolytic activity can be fully inhibited by a family of evolutionarily conserved proteins called IAPs (inhibitors of apoptosis proteins) (Deveraux & Reed, Genes Dev. 13: 239-252, 1999). Each of the IAPs contains 1-3 copies of the so-called BIR (baculoviral IAP repeat) domain and directly interacts with and inhibits the enzymatic activity of mature caspases. Several distinct mammalian IAPs including XIAP, survivin, and Livin/ML-IAP (Kasof & Gomes, J. Biol. Chem. 276: 3238-3246, 2001; Vucic et al. Curr. Biol. 10: 1359-1366, 2000; Ashhab et al. FEBS Lett. 495: 56-60, 2001), have been identified, and they all exhibit anti-apoptotic activity in cell culture (Deveraux & Reed, 1999, supra). As IAPs are expressed in most cancer cells, they may directly contribute to tumor progression and subsequent resistance to drug treatment. [0008] In normal cells signaled to undergo apoptosis, however, the LAP-mediated inhibitory effect must be removed, a process at least in part performed by a mitochondrial protein named Smac (second mitochondria-derived activator of caspases; Du et al. Cell 102: 33-42, 2000) or DIABLO (direct IAP binding protein with low pI; Verhagen et al. Cell 102: 43-53, 2000). Smac, synthesized in the cytoplasm, is targeted to the inter-membrane space of mitochondria. Upon apoptotic stimuli, Smac is released from mitochondria back into the cytosol, together with cytochrome c. Whereas cytochrome c induces multimerization of Apaf-1 to activate procaspase-9 and -3, Smac eliminates the inhibitory effect of multiple IAPs. Smac interacts with all IAPs that have been examined to date, including XIAP, c-IAP1, c-IAP2, and survivin (Du et al., 2000, supra; Verhagen et al., 2000, supra). Thus, Smac appears to be a master regulator of apoptosis in mammals. [0009] Smac is synthesized as a precursor molecule of 239 amino acids; the N-terminal 55 residues serve as the mitochondria targeting sequence that is removed after import (Du et al., 2000, supra). The mature form of Smac contains 184 amino acids and behaves as an oligomer in solution (Du et al., 2000, supra). Smac and various fragments thereof have been proposed for use as targets for identification of therapeutic agents. U.S. Pat. No. 6,110,691 to Wang et al. describes the Smac polypeptide and fragments ranging from at least 8 amino acid residues in length. However, the patent neither discloses nor teaches a structural basis for choosing a particular peptide fragment of Smac for use as a therapeutic agent or target. [0010] Similar to mammals, flies contain two IAPs, DLAP1 and DIAP2, that bind and inactivate several Drosophila caspases (Hay, Cell Death Differ. 7: 1045-1056, 2000). DIAP1 contains two BIR domains; the second BIR domain (BIR2) is necessary and sufficient to block cell death in many contexts. In Drosophila cells, the anti-death function of DIAP1 is removed by three pro-apoptotic proteins, Hid, Grim, and Reaper, which physically interact with the BIR2 domain of DIAP1 and remove its inhibitory effect on caspases. Thus Hid, Grim, and Reaper represent the functional homologs of the mammalian protein Smac. However, except for their N-terminal 10 residues, Hid, Grim, and Reaper share no sequence homology with one another, and there is no apparent homology between the three Drosophila proteins and Smac. [0011] In commonly-owned co-pending application Ser. No. 09/965,967 (the entirety of which is incorporated by reference herein), it is disclosed that the above described biological activity of Smac is related to binding of its N-terminal four residues to a featured surface groove in a portion of XIAP referred to as the BIR3 domain. This binding prevents XIAP from exerting its apoptosis-suppressing function in the cell. It was further disclosed that N-terminal tetrapeptides from LAP binding proteins of the Drosophila pro-apoptotic proteins Hid, Grim and Veto function in the same manner. [0012] The development of apoptosis-promoting therapeutic agents based on the IAP-binding peptide of Smac or its homologs from other species would be greatly facilitated by high throughput screening assays to identify useful molecules. Further, development of such therapeutic agents would be accelerated by the production of libraries of rationally designed candidate compounds. SUMMARY OF THE INVENTION [0013] The present invention features an assay for use in high throughput screening or rational drug design of agents that can, like the Smac tetrapeptide or its homologs in other species, bind to a BIR domain of an IAP, thereby relieving IAP-mediated suppression of apoptosis. These assays make use of the discoveries made in accordance with the invention disclosed in commonly-owned, co-pending U.S. application Ser. No. 09/965,967 that (1) the N-terminal tetrapeptide motif of Smac and other IAP binding proteins is sufficient for binding to IAPs and (2) the mammalian BIR3 domain and the Drosophila BIR2 domain comprise a specific binding groove for the tetrapeptide. [0014] The assay comprises the following basic steps: (a) providing a labeled mimetic of an IAP-binding tetrapeptide that binds to the appropriate BIR domain (preferably BIR3), wherein at least one measurable feature of the label changes as a function of the mimetic being bound to the IAP or free in solution; (b) contacting the BIR domain of an IAP with the labeled mimetic under conditions enabling binding of the mimetic to the BIR domain, thereby forming a BIR-labeled mimetic complex having the measurable feature; (c) contacting the BIR-labeled mimetic complex with the compound to be tested for BIR binding; and (d) measuring displacement of the labeled mimetic from the BIR-labeled mimetic complex, if any, by the test compound, by measuring the change in the measurable feature of the labeled mimetic, thereby determining if the test compound is capable of binding to the LAP. In a preferred embodiment, the labeled mimetic is AVPX (SEQ ID NO:1), wherein X is directly or indirectly linked to a fluorigenic dye. Preferably, it is AVPC (SEQ ID NO:2) attached to a badan dye. [0015] The present invention also provides a library of peptides or peptidomimetics that have been demonstrated by the methods of the invention to bind to the BIR3 domain of XIAP. In one embodiment, these peptides are composed of naturally-occurring amino acid residues. In another embodiment, the library is based on a peptidomimetic, which may be partially or fully non-peptide in nature, but which mimics the physicochemical features of the Smac peptide such that it is capable of binding IAP. BRIEF DESCRIPTION OF THE DRAWINGS [0016] FIG. 1 shows the chemical structure of AVPC-badan dye. [0017] FIG. 2 shows absorption and emission properties of AVPC-badan. FIG. 2A shows the absorption (solid line) and emission (dotted line) spectra of the molecule in water. FIG. 2B shows the solvatochromicity of AVPC-badan in acetonitrile (ACN), with respect to the emission spectrum. [0018] FIG. 3 shows the emission spectra of AVPC-badan in the presence of BIR3 at different concentrations of BIR3. Measurements were taken in 50 mM Tris buffer, pH 7.1, 100 mM NaCL, 2 mM DTT and 5.1 μM badan dye, excitation wavelength 387 nm. [0019] FIG. 4 shows emission spectra of samples from the binding assay described in the text, the results of which are shown in Table 2. All samples were 5 μM in both dye and protein, and 50 mM in the tetrapeptide. The buffer was 50 mM Tris at pH 7.1, 100 mM NaCl and 2 mM DTT. The AVPI (SEQ ID NO:3) tetrapeptide displayed was synthesized separately from the other samples. [0020] FIG. 5 shows (A) absorption (−) and emission ( - - - ) spectra of AVPC-badan in water (excitation at 387 nm) (These spectra are also shown in FIG. 2 ); and (B) titration of AVPC-badan with BIR3. The fraction of free AVPC-badan was determined by relating the difference of the observed fluorescence intensity and a maximum intensity where all of the dye is assumed to be bound, I v , to the difference between the intensity of the unbound dye and I v . Data are discussed in Example 1. [0021] FIG. 6 shows (A) emission spectra of AVPC-badan, AVPC-badan in the presence of BIR3 and AVPF (SEQ ID NO:4), AVPC-badan in the presence of BIR3 and ARPI (SEQ ID NO:5), AVPC-badan in the presence of BIR3 and AVPI (SEQ ID NO:3), AVPC-badan in the presence of BIR3 and GVPI (SEQ ID NO:6), AVPC-badan in the presence of BIR3 and AGPI (SEQ ID NO:7), and AVPC-badan in the presence of BIR3, in order of increasing emission intensity; and (B) correlation of hydrophobic interaction expressed as ΔG 1 (EtOH—H 2 O) (23) with ΔG b for a range of nonpolar amino acids (polar amino acids are not shown in this graph). Data are discussed in Example 1. DETAILED DESCRIPTION OF THE INVENTION [0022] The ability to quickly assay small molecules for their effectiveness in disrupting protein-protein interactions is critical to the development of viable drug candidates. One aspect of the present invention comprises an assay to test the binding affinity of a library of tetrapeptide molecules for the BIR3 domain of an inhibitor of apoptosis protein (LAP), particularly the mammalian XIAP. The assay is based on a detectable label, preferably a fluorogenic dye molecule. In preferred embodiments, the fluorophore is attached to a tripeptide, AVP, whose sequence matches the N-terminal three residues of Smac. The general structure of this molecule, therefore, is AVP[X], wherein X is the fluorophore. The molecule is referred to herein as an “AVP-dye”. The AVP-dye packs into the groove of the BIR3, causing a large shift in emission maximum and intensity when the environment of the dye changes from water to the hydrophobic pocket of the protein. If a molecule (e.g. the native Smac protein or a tetrapeptide mimic) displaces the dye, then emission will shift back to the spectrum observed in water. Since the emission intensity is related to the binding of the tetrapeptide, the intensity can be used to estimate the equilibrium constant, K, for displacement of the AVP-dye by the tetrapeptide. The larger the equilibrium constant, the greater affinity the tetrapeptide has for the BIR3. This allows the most promising inhibitors to be quickly determined, and structural information about effective inhibitors can be incorporated into the design of candidates for the next round of testing. [0023] It will be understood by those of skill in the art that, though the AVP dye-BIR3 system described above is exemplified and preferred for practice of the invention, various combinations of (1) LAP-binding tetrapeptides and mimetics, (2) BIR binding grooves and (3) detectable labels may be used interchangeably to create variations of the assay described above. Particular reference is given to the consensus tetrapeptide set forth in co-pending U.S. application Ser. No. 09/965,967, which is A-(V/T/I)-(P/A)-(F/Y/I/V) (SEQ ID NO:8). [0024] Without intending to be limited by any explanation as to mechanism, it is believed that the underlying factors influencing binding of the labeled tetrapeptide AVP-dye to the BIR binding groove include the following: 1. Recognition is achieved through hydrogen bond interactions and van der Waals contacts. 2. Eight inter- and three intra-molecular hydrogen bonds support the binding of AVPI in the surface groove on BTR3. 3. Three intermolecular contacts between the backbone groups of Val2/Ile4 in Smac and Gly306/Thr308 in BIR3 allow the formation of a 4 stranded antiparallel β sheet. 4. Ala1 donates 3 hydrogen bonds to Glu314 and Gln319, and its carbonyl makes contact with Gln319 and Trp323. 5. The methyl group of Ala1 fits tightly in a hydrophobic pocket formed by the side chains of Leu307, Trp310, and Gln319. 6. Val2 and Pro3 maintain multiple van der Waals interactions with Trp323, and Pro3 has an additional interaction with Tyr324. 7. The side chain of Ile4 interacts with Leu292, Gly306, Lys297 and Lys299. [0032] Accordingly, the AVP-dye may comprise any suitable detectable label, such as a fluorophore, such that binding of the label does not detrimentally affect binding of the dye to the BIR3, via any one or more of the foregoing factors. A particularly suitable dye for use in the AVP-dye is 6-Bromoacetyl-2-dimethylaminonaphthalene (badan) dye. Badan is a fluorogenic dye whose sensitivity to environmental changes has previously been made use of to probe protein binding interactions (Boxrud et al. J. Biol. Chem. 275: 14579-14589, 2000; Owenius et al., Biophys. J. 77: 2237-2250, 1999; Hiratsuka, T. J. Biol. Chem. 274: 29156-29163, 1999). [0033] The synthesis of NH 3 + -AVPC(badan)amide is described below, and its chemical structure is shown in FIG. 1 . Unless otherwise stated, materials were purchased from Aldrich Chemical Co. (Milwaukee, Wis.) or Fisher Scientific (Pittsburgh, Pa.) and used without further purification. Methylbenzhydrylamine (MBHA) solid-phase peptide synthesis resin and Fmoc amino acids were obtained from Advanced ChemTech (Louisville, Ky.) and NovaBiochem (San Diego, Calif.). Badan dye was obtained from Molecular Probes (Eugene, Oreg.). [0034] The peptide was synthesized on a hand shaker by Fmoc protocol on MBHA resin (Chan, W. C.; White, P. D. Fmoc Solid Phase Peptide Synthesis: A Practical Approach ; Oxford University Press: Oxford, 2000). The MBHA resin was chosen because the protocol requires that it be stable under both acidic and basic conditions. The Ala-Val-Pro-Cys peptide was synthesized using a trityl group to protect the Cysteine thiol. Prior to the deprotection of the Fmoc group of the alanine, the trityl group was removed by the addition of trifluoroacetic acid (TFA), and the cysteine was derivatized with badan in the presence of diisopropylethylamine (DIEA). The Fmoc group of the alanine was removed with piperidine and then cleavage from the resin was effected by treatment with anhydrous HF containing 10% v/v anisole as scavenger at 0° C. for 45 minutes. The labeled peptide was purified by HPLC on a Vydac C18 preparative column with gradient elution by solvents A (99% H 2 O; 1% CH 3 CN; 0.1% TFA) and B (90% CH 3 CN; 10% H 2 O; 0.1% TFA) and lyophilized to dryness prior to reconstitution in H 2 O. [0035] Absorption and emission properties of AVPC-badan are shown in FIG. 2 . FIG. 2A shows the absorption and emission spectra of the molecule in water. FIG. 2B shows the solvatochromicity of AVPC-badan in acetonitrile (ACN), with respect to the emission spectrum. FIG. 3 shows the emission spectra of AVPC-badan in the presence of BIR3 at different concentrations of BIR3. [0036] The aforementioned AVP-dye is used in an assay of test compounds that may, like the Smac tetrapeptide AVPI, bind to the BIR3 domain of XIAP, thereby relieving XIAP-mediated suppression of apoptosis. This is a high-throughput, cell-free assay, that is assembled as follows. A protein comprising the BIR3 domain of an IAP is placed in an assay medium comprising a suitable buffer, as described above. Preferably, this is a recombinant protein comprising the BIR3 domain, but a full IAP protein also may be used. An aliquot of the AVP-dye is added to the reaction mixture, in the presence of the test compound. Controls comprise the BIR3 and the dye in the absence of the test compound and, optionally, BIR3 and the dye in the presence of the naturally occurring tetrapeptide, AVPI. The fluorescence of the reaction mixture at a selected excitation and emission wavelength, e.g., 387 nm excitation, 545 nm emission, is measured. Alternatively, a emission spectrum is measured at the selected excitation wavelength. In one type of measurement, the test compound is added and an emission spectrum is measured by scanning from, e.g., 460-480 nm. In another type of measurement, the emission intensity at a particular wavelength, e.g., 470 nm, is measured. The emission spectrum of the dye bound to BIR3 is distinctly different from the spectrum of the dye in solution, as demonstrated in FIGS. 3 and 4 . Thus, the binding affinity of the test compound may be calculated as a function of its ability to displace the dye from the BIR3 domain, according to the following calculation: K relative = Fraction free 2 ⁡ [ badan ] total ( 1 - Fraction free ) ⁢ ( [ AVPX ] total - [ badan ] total ⁢ Fraction free ) [0037] Details of a typical assay are set forth below. [0000] Materials: [0000] 63 μM BIR3 in 50 mM Kphos buffer pH 7 100 mM NaCl2 mM DTT Four 0.5 ml aliquots of BIR3 stored at −70° C. and thawed over ice were used 43.8 μM AVPC-badan in H 2 O; chilled to 4° C. absorbance at 387 nm=0.9205; ε 387nm =21000 M −1 cm −1 50 mM tetrapeptide solutions in H 2 O; chilled to 4° C. 50 mM Kphos buffer pH 7 100 mM NaCl 2 mM DTT; chilled to 4° C. H 2 O (MilliQ purified); chilled to 4° C. Procedure [0045] Stock solution of badan, BIR3, and buffer were mixed: 2.5 ml of badan, 1.75 ml BIR3, and 15.25 ml of buffer were mixed in a glass vial which had been chilled to 4° C. Added 390 μL of the stock solution to 50 wells in the pre-chilled 96 well plate (wells A1-E2). [0046] Stock solution of badan and buffer were mixed: 150 μL badan and 1020 μL of buffer were mixed in a small glass vial (also chilled) and added to 3 wells on the plate in 390 μL aliquots (F1-F3). [0047] The 96 well plate was stored over ice in an insulated bucket while the emission spectra of the samples were taken. Fifty μL of the appropriate test solution (or water, for the control experiments) was added with a micropipet, the solution mixed with a Pasteur pipet before adding the sample to the fluorescence cuvette. While one sample was being scanned, the cuvette from the previous scan was washed with EtOH and then next sample was prepared. [0048] The PTI fluorometer settings were as follows: λ ex =387 nm; the emission spectrum was scanned from 420-650 nm slits=5 nm dispersion PMT voltage=750 mV The scan was done in 1 nm increments and the integration time was 1 s. [0052] Using the above assay, the inventors have screened a wide variety of peptides and peptide mimetics for their ability to bind to the BIR3 domain of XIAP. As an example, a tetrapeptide library was created, in which positions 1, 2 and 4 of the Smac tetrapeptide were substituted with other components. In one series of constructions, substitutions were as follows: 1. Position 1: XVPI (SEQ ID NO:9), where X=Serine, Glycine or Aminobutyric acid. 2. Position 2: AXPI (SEQ ID NO:10), where X=all twenty naturally occurring amino acids. 3. Position 4: AVPX (SEQ ID NO: 1), where X=all twenty naturally occurring amino acids. [0056] Samples of results of the assay performed on members of the aforementioned group are shown in Table 1. TABLE 1 SEQ ID: Sample Intensity (470 nm) Fraction free K relative 4 AVPF 16773 0.97410 31.5300 11 AVPW 23435 0.94176 23.1330 5 ARPI 29455 0.91253 4.3126 12 ALPI 38650 0.86789 3.5812 13 AbuVPI 34770 0.88673 3.0455 14 AIPI 44902 0.83754 2.6613 15 AVPY 39093 0.86574 2.5442 3 AVPI 54232 0.79224 2.5014 16 AHPI 41450 0.85430 2.2917 3 AVPI 26924 0.92482 2.2415 [0057] The tetrapeptides AVPF (SEQ ID NO:4), AIAY (SEQ ID NO:17) and AVAF (SEQ ID NO: 18) correspond in sequence to Drosophila homologs of Smac. Results showed that tetrapeptides containing these sequences bound strongly to BIR3 (AVPF shown in Table 1, other results not shown). [0058] The most successful modification at position 2 was ARPI (SEQ ID NO:5). The positive charge on the arginine residue may have contact with the surrounding negatively-charged residues in the binding pocket, resulting in the strong binding observed with ARPI (SEQ ID NO:5). [0059] As mentioned, a tetrapeptide library of position-4 modifications was created. Table 2 below sets forth binding constants obtained for each member of this library, as tested with the assay of the invention. TABLE 2 SEQ ID: Tetrapeptide K 4 AVPF >20 3 AVPI (std) 4.2149 15 AVPY 1.1692 11 AVPW 1.0817 19 AVPL 0.34232 3 AVPI 0.29080 20 AVPD 0.17988 21 AVPT 0.14300 2 AVPC 0.10340 22 AVPV 0.10111 23 AVPG 0.089481 24 AVPH 0.075209 25 AVPQ 0.066115 26 AVPA 0.055180 27 AVPM 0.052881 28 AVPE 0.037089 29 AVPN 0.015724 30 AVPS 0.013041 31 AVPP 0.010695 32 AVPK 0.0070200 33 AVPR 0.0014831 [0060] Emission spectra of samples from this binding assay are shown in FIG. 4 . As can be seen from FIG. 4 and the results set forth in Table 1 and Table 2, the tetrapeptide AVPF (SEQ ID NO: 4) bound strongly to the BIR3 domain, as evidenced by its ability to displace the AVP-dye. AVPW (SEQ ID NO11): and AVPY (SEQ ID NO:15) also showed binding at a strength equivalent to that of the naturally-occurring Smac peptide, AVPI (SEQ ID NO:3). By contrast, AVPK (SEQ ID NO:32) bound BIR3 only weakly. [0061] In summary, the assay described herein has been demonstrated effective in identifying compounds that are capable of binding to the BIR3 domain of XIAP. Certain tetrapeptides with greater binding ability than the naturally-occurring Smac tetrapeptide have been identified. These tetrapeptides may be developed as therapeutic agents for the promotion of apoptosis in treatment of diseases or pathological conditions in which cell proliferation plays a role. The assay may be further used in high throughput screening of large panels of compounds generated by combinatorial chemistry or other avenues of rational drug design. [0062] The following nonlimiting example is set forth to describe the invention in greater detail. The example contains data that replicate and supplement the data presented above. The example also describes additional tetrapeptide analogs, including N-methyl analogs and a dual substituted tetrapeptide, ARPF. EXAMPLE 1 Molecular Targeting of Inhibitor of Apoptosis Proteins Based on Small Molecule Mimics of Natural Binding Partners [0063] In this example, a fluorescence assay was used to test the binding of a library of tetrapeptides modeled on the Smac N-terminus to the surface pocket of the BIR3 region of XIAP. The results make it possible to parse the contribution of each residue of the tetrapeptide to the total binding energy of the interaction. Materials and Methods [0064] Materials. Unless otherwise stated, materials were purchased from Aldrich Chemical Co. (Milwaukee, Wis.) or Fisher Scientific (Pittsburgh, Pa.) and used without further purification. Methylbenzhydrylamine (MBHA) solid-phase peptide synthesis resin, Rink amide resin, and 9-Fluorenylmethoxycarbonyl (Fmoc) protected amino acids were obtained from Advanced ChemTech (Louisville, Ky.) and NovaBiochem (San Diego, Calif.). 6-Bromoacetyl-2-dimethylaminonaphthalene (badan) dye was obtained from Molecular Probes (Eugene, Oreg.). [0065] Synthesis of A VPC-badan. The peptide was synthesized by Fmoc protocol on MBHA resin. The MBHA resin was chosen because the protocol requires that the linkage to the solid support be stable under both acidic and basic conditions. The Ala-Val-Pro-Cys-NH 2 (AVPC; SEQ ID NO:2) peptide was synthesized using a trityl group to protect the cysteine thiol. The trityl group was removed by treatment with trifluoroacetic acid (TFA), and the cysteine was derivatized with badan in the presence of diisopropylethylamine (DIEA). The Fmoc group of the alanine was removed with piperidine and then cleavage from the resin was effected by treatment with anhydrous HF containing 10% v/v anisole as scavenger at 0° C. for 45 minutes. The labeled peptide was purified by HPLC on a Vydac C18 preparative column with gradient elution by solvents A (99% H 2 O; 1% CH 3 CN; 0.1% TFA) and B (90% CH 3 CN; 10% H 2 O; 0.1% TFA) and lyophilized to dryness prior to reconstitution in H 2 O. [0066] Synthesis of N-Fmoc-N-methyl-amino acids. N-methyl-amino acids were synthesized according to the methods of Freidinger et. al. (J. Org. Chem. 48: 77-81, 1983). The N-Fmoc-N-methyl-isoleucine and N-Fmoc-N-methyl phenylalanine were chromatographed over silica gel (5% methanol in chloroform as eluent); the N-Fmoc-N-methyl-valine was used without further purification. [0067] Synthesis of Tetrapeptide Libraries. With the exception of the position one library and A(N-Me)VPI, all of the library molecules were synthesized on an Advanced ChemTech 396 MPS automated peptide synthesizer by Fmoc protocol on Rink amide resin (Chan & White (2000) Fmoc Solid Phase Synthesis, A Practical Approach; Oxford University Press, Oxford). For the AVPX (SEQ ID NO:1) and the AXPI (SEQ ID NO:10) libraries, the X positions were substituted with all twenty naturally occurring amino acids. The side chains of the amino acids that are sensitive to side reactions were protected as follows: cysteine, histidine, asparagine, and glutamine were protected using a trityl group; aspartic acid, glutamic acid, serine, threonine, and tyrosine were t-butyl protected; lysine and tryptophan were protected by Boc groups; and a pentamethyldihydrobenzofuran group was used to protect the arginine. After the alanine was added, deprotection and cleavage of the tetrapeptides from the resin was effected by adding 1 ml of a 95% TFA, 2.5% water, and 2.5% triisopropylsilane (TIS) solution to each well, and shaking for 1 hour. The cleavage solution was collected and a further 0.5 ml of the cleavage solution was added to each well and mixed for another hour. The combined cleavage solutions were added to 20 ml of water, lyophilized to dryness, then taken up in 5 ml of water before being filtered through syringe filters (0.2 μ) and lyophilized again. [0068] The position one tetrapeptides and A(N-Me)VPI (SEQ ID NO:34) were synthesized on a hand shaker, also by Fmoc protocol on Rink amide resin. Cleavage and work up were done as described above. The presence of the desired tetrapeptide molecules was confirmed by mass spectroscopy. [0069] The tetrapeptides were reconstituted in water and test solutions were made that were approximately 200 mM in the tetrapeptides. Exact concentrations were determined for 10 representative test solutions by 1 H-NMR using a dioxane solution of known concentration as an external reference. The concentrations of the other test solutions were taken to be the average value of the known solutions from the same library synthesis. [0070] Expression and Purification of BIR3. Recombinant XIAP-BIR3 (residues 238-358) was overexpressed as a GST-fusion protein using pGEX-2T (Amersham Biosciences). The soluble fraction of the GST-BIR3 in the E. coli lysate was purified over a glutathione sepharose column, and further purified by anion exchange chromatography (Mono-Q, Amersham Biosciences). The fusion protein was cleaved by thrombin, and the GST portion was removed by the glutathione sepharose column. The BIR3 protein was further purified over a gel filtration column (Superdex 30, Amersham Biosciences). [0071] Fluorescence Experiments. Luminescence spectra were recorded using a Photon Technologies, Inc. fluorometer with a Xe arc lamp and a PMT detector. The absorbance of all solutions was less than 0.2 at the excitation wavelength (387 nm). The buffer used in all of the fluorescence experiments was 50 mM potassium phosphate, 100 mM NaCl, 2 mM 1,4-dithio-DL-threitol (DTT), pH 7. [0072] Determination of A VPC-badan binding constant to BIR3. 2 ml of a 2 μM AVPC-badan stock solution (buffer same as above) was titrated with a BIR3 stock solution from 0 to 10 μM in 15 μL increments. The dissociation constant for AVPC-badan and BIR3 was determined from the intensity observed at 470 μm after each addition of the protein. [0073] Assay of Tetrapeptide Libraries. The samples were prepared in a 96 well plate lined with glass tubes, to prevent adsorption of the dye to plastic. The plate was stored on ice in the dark between measurements. A small volume cuvette, with a path length of 2 mm, was used to collect the emission spectra. 2.5 ml of a 44 μM aqueous solution of AVPC-badan, 1.75 ml of a 63 μM BIR3 solution, and 15.25 ml of buffer were mixed to give a stock solution which was 5.6 μM in both AVPC-badan and BIR3. 390 μL of this stock solution were added to 50 wells of the 96 well plate. 50 μL of the test tetrapeptide solutions were added and mixed immediately prior to taking the emission spectra. The final solutions were 5 μM in both badan and BIR3, and approximately 20-30 μM in the tetrapeptide solutions. 50 μL of water were added to three of the wells by way of controls, to determine the intensity observed when the AVPC-badan was bound to BIR3. 190 μL of AVPC-badan and 1020 μL of buffer were mixed and added to three wells in 390 μL aliquots. 50 μL of water was added to these wells, again as controls, to determine the intensity of the unbound dye. Equilibrium constants were determined by relating the observed intensity of the test solution at 470 nm to the average values obtained from the control experiments. Results [0074] The binding of various tetrapeptide mimics to the BIR3 domain of XIAP was determined using a fluorescence-based competition assay. The assay is based on an environment-sensitive fluorogenic dye molecule, badan. Badan is a dye whose sensitivity to environmental changes has previously been used to probe protein binding interactions. A tetrapeptide based on the Smac binding motif, Ala-Val-Pro-Cys-NH 2 (AVPC; SEQ ID NO:2), was derivatized with the badan molecule to create a binding interaction with BIR3. When AVPC-badan binds to the surface groove of BIR3, changing the environment of the dye from water to the hydrophobic interior of the protein, the result is a large shift in both fluorescence maximum and intensity. The K D for the AVPC-badan/BIR3 complex, as determined from a fluorescence titration, is 0.31±0.04 μM. The AVPC-badan can be displaced from the binding pocket of the protein by any competing molecule. As the dye is displaced from the binding pocket by the test molecule, the emission shifts back towards the aquated spectrum. Thus, the observed emission intensity of the dye can be related to the degree of displacement of AVPC-badan by the test molecules. This allows the most promising inhibitors to be quickly determined, and structural information about effective inhibitors can be incorporated into the design of candidates for the next round of testing. [0075] Using the four N-terminal residues of Smac as a starting point, six libraries of related tetrapeptides were synthesized (Scheme 1) and evaluated in terms of their ability to displace AVPC-badan from the peptide binding groove on the surface of BIR3. The tetrapeptide libraries were designed to deconvolve the contribution of each amino acid to the binding of Smac to BIR3 (Scheme 1). The position one library only consisted of three members, reflecting the critical role that Ala1 plays in the recognition of the binding element by BIR3. The role of position three was explored using a tetrapeptide based on the N-terminal sequence of Reaper, one of the few natural binding partners without a proline in position three (Table 3). Libraries of positions two and four, over all twenty naturally occurring amino acids, were synthesized. The tetrapeptide ARPF (SEQ ID NO:35) was synthesized to investigate the possibility of additivity by modifying both positions simultaneously. [0076] There are two bonds in the tetrapeptide that are vulnerable to proteolysis; the peptide bond between position one and position two, and the peptide bond between position three and four. One means of rendering these bonds more resistant to proteolysis is to replace the hydrogen on the amide with a methyl group. Several tetrapeptide homologs were synthesized with N-methyl amino acids to explore the effect such modifications have on the affinity of these compounds for BIR3. [0077] The dissociation constants (K D ) for the library members are listed in Table 4. The tetrapeptide mimics displace badan from BIR3 with varying facility (Table 4, FIG. 6A ). The K D values ranged from 0.02 μM to greater than 100 μM. The conservation of sequence of the binding motif observed across the range of protein binding partners suggests that nature has optimized the appropriate sequence to some extent, but the variety of tetrapeptides tested in this assay explores the specific contribution made at each position to the overall binding interaction. [0078] TABLE 4 K D for Tetrapeptide Homologs (Numbers to the right of each sequence in parentheses are SEQ ID NOS) K D (μM) Natural Analogs AVPI (3) 0.48 AVPIAQKSE (36) 0.40 AVAF (46) 0.56 AVPF (4) 0.04 AVPY (15) 0.30 Position 1 AbuVPI (13) 0.24 GVPI (6) 9 SVPI (47) 27 Position 2 ARPI (5) 0.18 ALPI (12) 0.29 AHPI (16) 0.33 AIPI (14) 0.39 AKPI (48) 0.57 AYPI (49) 0.59 ACPI (50) 0.65 AMPI (51) 0.73 AFPI (52) 0.79 AQPI (53) 0.94 AWPI (54) 0.99 ATPI (55) 1.2 ASPI (56) 1.4 ANPI (57) 1.5 AEPI (58) 2.7 AAPI (59) 2.8 ADPI (60) 17 AGPI (7) 46 APPI (61) >100 Position 4 AVPW (11) 0.11 AVPL (19) 0.49 AVPC (2) 1.4 AVPV (22) 1.5 AVPT (21) 2.1 AVPM (27) 2.3 AVPS (30) 4.4 AVPG (23) 4.7 AVPP (31) 5.7 AVPD (20) 7.3 AVPH (24) 7.3 AVPA (26) 14 AVPK (32) 28 AVPE (28) 93 AVPR (33) >100 AVPN (29) >100 AVPQ (25) >100 Positions 2 and 4 ARPF (35) 0.02 N-methyl Analogs ARP(N-Me)F (62) 0.71 AVP(N-Me)F (63) 0.89 A(N-Me)VPF (64) 83 A(N-Me)VP(N-Me)F(65) 91 AVP(N-Me)I (66) 174 ARP(N-Me)I (67) 190 A(N-Me)VPI (68) 257 Discussion [0000] Residue 1 [0079] In previous studies, it was noted that mutations of the N-terminal amino acid of Smac completely abrogated the binding interaction between Smac and BIR3. The recognition between Smac and the surface groove of the BIR3 is based on a combination of eight intermolecular hydrogen bonds and van der Waals contacts. The necessity of the N-terminal alanine is obvious from the crystal structure. Ala1 donates three hydrogen bonds to nearby residues in the surface groove of BIR3, and its carbonyl group makes two additional contacts. The methyl group of Ala1 fits tightly into a hydrophobic pocket, and any modification of the alanine residue must be carefully designed to avoid steric hindrance in this pocket, or disruption of any of these essential hydrogen bonds. Although the next three residues contribute to the positioning of Ala1 in the binding pocket, their identity does not appear to be as critical as that of the Ala1. [0080] The position one library members demonstrate how sensitive the binding interaction is to any modification at this position. Binding is greatly diminished with GVPI (SEQ ID NO:6), consistent with an earlier report, and SVPI (SEQ ID NO:47) is also a diminished binder, but a slight enhancement in binding was observed with the unnatural amino acid, aminoisobutyric acid (Abu). [0000] Residue 3 [0081] AVAF (SEQ ID NO:46) has a binding affinity similar to that observed for the other natural analogs, AVPI (SEQ ID NO:3) and AVPIAQKSE (SEQ ID NO:36). However, this affinity is diminished by greater than a factor of ten relative to that observed for the AVPF (SEQ ID NO:4) tetrapeptide from the position two library. Previous studies have also noted a decrease in binding affinity when the proline is replaced by alanine. Based on that observation, and the relative homogeneity observed in the natural binding partners at position three (Table 3), it would seem that replacing the proline will diminish the binding affinity of the test tetrapeptide. [0000] Residue 2 [0082] As stated earlier, nature has already optimized the appropriate sequence to some extent. However, the position two library gives some surprising results. The high affinity of tetrapeptides such as ARPI (SEQ ID NO:5) and AHPI (SEQ ID NO:16) relative to the natural sequence of AVPI (SEQ ID NO: 3) would seem to indicate that positive charge at position two would increase the binding affinity of the peptide. This is not an unexpected result given the negatively charged residues that line the binding pocket of BIR3. Nonetheless, none of the natural binding partners of IAP listed in Table 3 has positively charged residues at position two. All the natural LAP interacting motifs that have been observed so far all contain b-branched amino acids at position two, such as valine, threonine, and isoleucine (Table 3). This result indicates that the natural sequence can be improved upon, and gives a basis for the structural design of the next set of potential binding partners. [0000] Residue 4 [0083] The X-ray structure of Smac binding to BIR3 indicates that there are no intermolecular hydrogen bonds to residue 4, and, of the four residues of the binding motif, residue 4 is the least sterically hindered. This would seem to make position four least sensitive to modification. Indeed, the K D that is observed for the AVPC (SEQ ID NO: 2) tetrapeptide (Table 4) is greater than that of the AVPC-badan, which indicates that binding is slightly enhanced by the presence of the dye. However, a much wider range of K D s is observed for the position four library than for the position two library. Although modification at this position can lead to the greatest enhancement in binding affinity that is observed, it can also essentially destroy the binding interaction. [0084] The AVPF (SEQ ID NO:4) tetrapeptide was by far the most strongly binding library member, closely followed by AVPW (SEQ ID NO:11). AVPY (SEQ ID NO:15) was also determined to have a binding affinity slightly greater than the natural analog, AVPI (SEQ ID NO:3). These results indicate that an aromatic group side chain on the amino acid at position four substantially enhances the binding affinity of the tetrapeptide for BIR3. This result is consistent with phylogenic data: other proteins that interact with LAPs have phenylalanine or tyrosine at position four (Table 3). [0085] When high affinity substitutions at position two and four were probed simultaneously using the ARPF tetrapeptide, the effects were found to be additive. Consequently, the detrimental effect on binding affinity observed with the N-methylated tetrapeptides could be somewhat counteracted by the increased affinity gained from the appropriate choice of amino acid. [0000] N-methyl Analogs [0086] N-methylation at the peptide bond between residues 1 and 2 disrupts a structurally defined hydrogen bond, and has a correspondingly large effect on binding. By contrast, N-methylation of residue 4 has a much smaller effect, consistent with structural data, which show no hydrogen bond to this amide. From a standpoint of molecular design, this relieves an important design constraint. Consideration of side chain contributions to the free energy of binding, ΔG b , using the free energy of transfer from ethanol to water, ΔG t (EtOH—H 2 O), to approximate the energy contribution of the side chain for hydrophobic amino acids, follows a clear general trend. More hydrophobic amino acids clearly bind more strongly, as indicated in FIG. 6B . The obvious correlation indicates that there is little specificity of interaction, but also suggests that the full hydrophobic effect is not realized. For example, the ΔG t of W is greater than that of F, but the ΔG b of AVPF (SEQ ID NO:4) is greater than that of AVPW (SEQ ID NO:11). A more detailed analysis can be obtained by modeling the various peptides onto the known structure and determining the solvent exposed surface area within the model. [0087] This invention is not limited to the embodiments described and exemplified above, but is capable of variation and modification within the scope of the appended claims.

Assays are disclosed for identifying peptides and peptidomimetics for promoting apotosis in cells, through a pathway involving the Inhibitor of Apoptosis Proteins (IAPs), exemplified by XIAP, and the mitochondrial protein Smac/DIABOLO (hereinafter Smac) and homologs thereof. Also disclosed are IAP-binding peptides and peptidomimetics identified through the use of the assay.

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of the filing date of U.S. Provisional Patent Application No. 61/304,941 filed Feb. 16, 2010, the disclosures of which are hereby incorporated herein by reference. SEQUENCE LISTING [0002] The instant application contains a Sequence Listing which has been submitted via EFS-Web and is hereby incorporated by reference in its entirety. Said ASCII copy, created on Jan. 31, 2011 is named Sequence Listing for Detecting Related Serotypes of HPV, and is 7.55 kilobytes in size. BACKGROUND OF THE INVENTION [0003] More than 80 types of human papillomaviruses (HPVs) have been identified. The different types of HPV cause a wide variety of biological phenotypes, from benign proliferative warts to malignant carcinomas (for review, see McMurray et al., Int. J. Exp, Pathol. 82(1): 15-33 (2001)). HPV6 and HPV11 are the types most commonly associated with benign warts, whereas HPV16 and HPV18 are the high-risk types most frequently associated with malignant lesions. Determination of the specific type of HPV in a clinical sample is, therefore, critical for predicting risk of developing HPV-associated disease. [0004] Several nucleic acid-based methods have been utilized to identify and quantify specific HPV types in clinical samples, such as detection of viral nucleic acid by in situ hybridization, Southern blot analysis, hybrid capture or polymerase chain reaction (PCR). The Hybrid Capture® II (Qiagen, Inc., Valencia, Calif.) assay utilizes antibody capture and non-radioactive signal detection, but detects only a single target of a given set of HPV types (See, e.g., Clavel et al., British J. Cancer 80(9): 1306-11 (1999)). Additionally, because the Hybrid Capture® II assay uses a cocktail of RNA probes (probe cocktails are available for high risk or low-risk HPV types), it does not provide information as to the specific HPV type detected in a sample, but rather provides only a positive or negative for the presence of high-risk or low-risk HPV. Similarly, many PCR-based methods often involve amplification of a single specific HPV target sequence followed by blotting the resulting amplicon to a membrane and probing with a radioactively labeled oligonucleotide probe. [0005] Other methods exploit the high homology between specific HPV genes of different types through the use of commercially available consensus primers capable of PCR amplification of numerous HPV types present in a sample. The presence of a specific HPV type is then identified using a type-specific oligonucleotide probe. See, e.g., Kleter et al., Journal of Clinical Microbiology 37(8): 2508-2517 (1999); Gravitt et al., Journal of Clinical Microbiology 38(1): 357-361 (2000). Similarly, assays that utilize degenerate PCR primers take advantage of the homology between HPV types, allowing detection of a greater number of HPV types than methods utilizing specific primer sets. See, e.g. Harwood et al., Journal of Clinical Microbiology 37(11): 3545-3555 (1999). Such assays also require additional experimentation to identify specific HPV types. [0006] The PCR methods described above can be associated with several problems. For example, differences in reaction efficiencies among HPV types can result in disproportionate amplification of some types relative to others. Additionally, the equilibrium for amplification will be driven towards those types that exist at higher copy numbers in a sample, which will consume the PCR reaction components, thus making amplification of the minor HPV types less likely. [0007] Also described in the art is a 5′ exonuclease fluorogenic PCR-based assay (Taq-Man PCR) which allows detection of PCR products in real-time and eliminates the need for radioactivity. See, e.g., U.S. Pat. No. 5,538,848; Holland et al, Proc. Natl. Acad. Sci. USA 88: 7276-7280 (1991). This method utilizes a labeled probe, comprising a fluorescent reporter (fluorophore) and a quencher that hybridizes to the target DNA between the PCR primers. Excitation of the fluorophore results in the release of a fluorescent signal by the fluorophore which is quenched by the quencher. Amplicons can be detected by the 5′-3′ exonuclease activity of the TAQ DNA polymerase, which degrades double-stranded DNA encountered during extension of the PCR primer, thus releasing the fluorophore from the probe. Thereafter, the fluorescent signal is no longer quenched and accumulation of the fluorescent signal, which is directly correlated with the amount of target DNA, can be detected in real-time with an automated fluorometer. [0008] Taq-Man PCR assays have been adapted for HPV type detection. Swan et al. (Journal of Clinical Microbiology 35(4): 886-891 (1997)) disclose a fluorogenic probe assay that utilizes type-specific HPV primers that amplify a portion of the L1 gene in conjunction with type-specific probes. The Swan et al. assay measures fluorescent signal at the end of a fixed number of PCR cycles (endpoint reading) and not in real-time. [0009] Josefsson et al. (Journal of Clinical Microbiology 37(3): 490-96 (1999)) report a Taq-Man assay that targets a highly conserved portion of the E1 gene in conjunction with type-specific probes labeled with different fluorescent dyes. A number of HPV types were amplified by utilizing a mixture of specific and degenerate primers. Josefsson et al. utilized up to three type-specific probes per assay, which were designed to detect a portion of the E1 gene from different HPV types. Unlike the Swan et al. assay, Josefsson et al. measured the accumulation of fluorescence in real-time. [0010] Tucker et al. (Molecular Diagnosis 6(1): 39-47 (2001)) describe an assay that targets a conserved region spanning the E6/E7 junction. Like the Josefsson assay, Tucker et al. employed real-time detection and type-specific fluorescent probes. Tucker et al. also utilized multiplex PCR to simultaneously detect HPV target sequences and either the actin or globin cellular loci in the same reaction tube. [0011] One of the particular challenges with HPV detection is the fact that there are many HPV types of clinical interest. Although multiplex assays for HPV detection are known, the multiplex assays are limited by the number of colorimetric channels for detection. These channels are various wavelengths of light (or ranges or bands of wavelengths). Each channel detects a signal emitted by a signal moiety that emits light at a specific channel wavelength. The number of HPV types that are detected is therefore limited by the number of different, distinctly detectable signal moieties in the assay. [0012] Despite the development of the HPV assays described above, it would be advantageous to develop a multiplex assay that is highly sensitive and reproducible, and that requires reduced man-hours compared to methods disclosed in the art. Given the many HPV types, it would be useful to detect more HPV types than there are detection channels of the assay. SUMMARY OF THE INVENTION [0013] The present invention is directed to a real-time PCR amplification that deploys Taq-Man chemistry to simultaneously detect more types of HPV than there are channels for detection. In other words, in an assay with N channels, the number of HPV types that are detected is at least N+1. [0014] The assay deploys a primer/probe set for detection of each type of HPV that the assay is configured to detect. Among the various serotypes susceptible for detection by the assay include, for example, HPV types 33, 39, 51, 56, 58, 59, and 68. The skilled person will appreciate that the probe/primer sets described herein might be combined with other primer/probe sets for other types of HPV (e.g. 16, 18, and 45). At least one type is detected using a single primer probe set. In the context of PCR amplification using a Taq-Man assay, the primer probe set is at least a forward primer, a reverse primer and a probe. At least two types are selected by a pair of primer probe sets with oligonucleotide sequences that are degenerate with respect to each other. “Degenerate sequences” as used herein, are two oligonucleotide primers or probes that are complementary to the same locus of the same gene of different closely related types and which have minor sequence variations with respect to each other to make them discriminatory between the two types. [0015] In one embodiment of the present invention, the degenerate primer probes sets are for detection of HPV types 39 and 68. The primer/probe set targets the same locus on the E6 gene of both types. The target length is 91 nucleotides and is illustrated in FIG. 1 . The target is only a segment of the entire E6 gene. The target for the degenerate primer/probe set for HPV types 39 and 68 is SEQ ID NO. 36. In a preferred embodiment the signal moieties for both probes is a cyanine dye label commercially available as CY5. [0016] In this embodiment, the primer probe set that is not degenerate discriminates for HPV Type 51. The primer/probe set for type 51 also targets the E6 gene, although in a different locus. In a preferred embodiment the signal moieties for this probe in this primer probe set is FAM, which is specifically identified below. [0017] In a second embodiment of the present invention, the degenerate primer/probes sets are for detection of HPV types 33 and 58. The primer/probe set targets the same locus on the E6 gene of both types. The target length is 138 nucleotides and is illustrated in FIG. 2 . The target is only a segment of the entire E6 gene. The target for the degenerate primer/probe set for HPV types 33 and 58 is SEQ ID NO. 37. In a preferred embodiment the signal moieties for both probes is FAM. [0018] In this embodiment, the primer probe set that is not degenerate discriminates for HPV Type 59. The primer/probe set for type 59 also targets the E6 gene, but not necessarily the same locus. In a preferred embodiment the signal moieties for this probe in this primer probe set is CY5, which is specifically identified below. [0019] In a third embodiment of the present invention, the degenerate primer/probes sets are for detection of HPV types 56 and 66. The primer/probe set targets the same locus on the E6 gene of both types. The target length is 79 nucleotides and is illustrated in FIG. 3 . The target is only a segment of the entire E6 gene. The target for the HPV type 56 and 66 degenerate primer/probe set is SEQ ID NO. 38. In a preferred embodiment the signal moieties for both probes is CY5. [0020] In this embodiment, the primer probe set that is not degenerate discriminates for HPV Type 59. The primer/probe set for Type 59 targets the E6 gene. In a preferred embodiment the signal moieties for this probe in this primer probe set is CY5, which is specifically identified below. In this embodiment, the same signal moiety that is used for HPV Type 59 is also used for HPV Types 56 — 66. Since the same dyes are on the same channel, there is no optical discrimination between HPV types 59 and 56 66 in this embodiment. [0021] This embodiment contemplates a multiplex assay that deploys yet another primer/probe set (either degenerate or discriminatory) for yet another HPV serotype (e.g. the degenerate primer/probe set for HPV serotypes 33 and 58). The signal moiety for this other HPV serotype is not CY5, and emits at a wavelength that is detectably different from the emission wavelength of Cy5 (e.g. FAM). [0022] In other embodiments, the signal moiety for the HPV Type 59 probe is FAM, which can be optically distinguished from the CY5 signal moiety for the degenerate primer/probe set for HPV serotypes 56 and 66. [0023] Alternate embodiments contemplate an assay or a probe set or a kit with any and all combinations of the primer/probe sets and the degenerate primer/probe sets described herein. Specifically, any of the primer/probe sets for HPV serotype HPV 51 or HPV 59 can be combined with any of the degenerated primer/probe sets for HPV serotypes HPV 39 — 68; HPV 33 — 58; and HPV 56 — 66. Specifically contemplated is an assay or probe set or a kit which combines the primer/probe set for HPV 51 with the degenerate primer probe set of one or more of HPV 39 — 68; HPV 33 — 58; and HPV 56 — 66. An assay or probe set or a kit which combines the primer/probe set for HPV 59 with the degenerate primer probe set of one or more of HPV 39 — 68; HPV 33 — 58; and HPV 56 — 66. Embodiments where the signal moieties for the probes are the same or different dyes are contemplated. Since a multiplex assay is contemplated, the primer/probe sets can be combined with other primer/probe sets configured to detect the presence or absence of other serotypes of HPV. In those embodiments where the signal moiety for the detector probe in the degenerate primer/probe sets is the same as the signal moiety for the primer/probe set for HPV serotype 51 or 59, it is contemplated that the multiplex assay would include a fourth primer/probe set for a fourth serotype of HPV (e.g. HPV 31, HPV 52, HPV 45, etc.) and that the fourth primer/probe set would have a signal moiety that is different from the signal moieties for the detector probes of the degenerate primer/probe sets and the HPV 51 or 59 primer/probe sets. Also, contemplated herein are multiplex assays in which two degenerate primer/probe sets are combined in one assay. For example, in one microwell, a first degenerate primer/probe set for detecting the present of HPV serotypes 33 and 58 can be combined with a second degenerate primer/probe set for detecting the presence or absence of HPV serotypes 56 and 66. In these embodiments the probes of the first degenerate primer probe set has a signal moiety that emits at wavelength that is detectably different from the emission wavelength of the signal moiety for the second degenerate primer/probe set. In this example the signal moiety for HPV serotypes 33 and 58 probes would be FAM and the signal moiety for HPV serotypes 56 and 66 probes would be CY5. [0024] In addition to the signaling moieties described above, the probes also have a non-fluorescent dark quencher. One example of a suitable dark quencher is BHQ™ 1 (Biosearch Technologies), which is suited for use with the FAM fluorophore. Another example of a suitable quencher is BHQ™ 2 (Biosearch Technologies), which is suited for use with the CY5 fluorophore. Other examples of signaling moieties are well known to those skilled in the art and are not described in detail herein. [0025] As used herein, the term “primer” refers to an oligonucleotide that is capable of acting as a point of initiation of synthesis along a complementary strand when placed under conditions in which synthesis of a primer extension product which is complementary to a nucleic acid strand is catalyzed. Such conditions include the presence of four different deoxyribonucleoside triphosphates and a polymerization-inducing agent such as DNA polymerase or reverse transcriptase, in a suitable buffer (“buffer” includes components which are cofactors, or which affect ionic strength, pH, etc.), and at a suitable temperature. As employed herein, an oligonucleotide primer can be naturally occurring, as in a purified restriction digest, or be produced synthetically. The primer is preferably single-stranded for maximum efficiency in amplification. [0026] As used herein, “primer pair” refers to two primers, a forward primer and a reverse primer, that are capable of participating in PCR amplification of a segment of nucleic acid in the presence of a nucleic acid polymerase to produce a PCR amplicon. The primers that comprise a primer pair can be specific to the same HPV gene, resulting in an amplicon that consists of a sequence of nucleotides derived from a single HPV gene. Alternatively, the primers that comprise a primer pair can be specific to different HPV genes that reside within close proximity to each other within the HPV genome, thereby producing amplicons that consist of a sequence of nucleotides derived from more than one gene. [0027] As used herein, “different imaging spectra,” in reference to the fluorophores of the present invention, means that each fluorophore emits energy at a differing emission maxima relative to all other fluorophores used in the particular assay. The use of fluorophores with unique emission maxima allows the simultaneous detection of the fluorescent energy emitted by each of the plurality of fluorophores used in the particular assay. [0028] As used herein, the term “discriminatory,” used in reference to the oligonucleotide primers and probes of the present invention, means that said primers and probes are specific to a single HPV type. It includes HPV primers and probes specific to a single HPV type, but that share some homology with other HPV types. “Discriminatory” primers and probes of the present invention include those oligonucleotides that lack 3′ homology with other HPV types in at least one nucleotide or more. Such a residue that is unique for the specific HPV type at the specific position and acts to discriminate the HPV type from the others in the alignment is referred to as a “discriminatory base”. The term “discriminatory,” in reference to oligonucleotides, does not include primers and probes that are specific to more than one HPV type, i.e. those that share full homology with greater than one HPV type. In this regard the degenerate primer/probe sets disclosed herein do not discriminate for the HPV type for which they are configured. For example, for the degenerate primer/probe set that targets HPV types 39 and 68, the primer/probe set for HPV type 39 has a preference for HPV type 39 over HPV type 68 but does not discriminate for HPV type 39 over HPV type 68. Because the degenerate primer/probe sets do not discriminate between the HPV types, the probes preferably have the same signal moiety. Since the assay is configured to determine the presence or absence of these HPV types in the aggregate, there is no need to use two optical channels for this purpose. Furthermore, when the degenerate primer/probe set is combined with other primer/probe sets in a single microwell for a multiplex assay, the signal moieties for the other primer/probe sets (either discriminatory or non-discriminatory) can be the same or different. The signal moieties for the assay are largely a matter of design choice. The skilled person will use the same signal moieties for primer/probe sets in the same microwell when it is necessary to know if the particular HPV type is present. The same signal moiety may be used on primer/probe sets for different HPV serotypes when it is sufficient to know if only one of those types is present. [0029] As used herein, “amplicon” refers to a specific product of a PCR reaction, which is produced by PCR amplification of a sample comprising nucleic acid in the presence of a nucleic acid polymerase and a specific primer pair. An amplicon can consist of a nucleotide sequence derived from a single gene of a single HPV type or an amplicon can consist of a nucleotide sequence derived from more than one gene of a single HPV type. [0030] As used herein, “primer/probe set” refers to a grouping of a pair of oligonucleotide primers and an oligonucleotide probe that hybridize to a specific nucleotide sequence of a single HPV type. Said oligonucleotide set consists of: (a) a forward discriminatory primer that hybridizes to a first location of a nucleic acid sequence of an HPV type; (b) a reverse discriminatory primer that hybridizes to a second location of the nucleic acid sequence of the HPV type downstream of the first location and (c) a fluorescent probe labeled with a fluorophore and a quencher, which hybridizes to a location of the nucleic acid sequence of the HPV type between the primers. In other words, an oligonucleotide set consists of a set of specific PCR primers capable of initiating synthesis of an amplicon specific to a single HPV type, and a fluorescent probe which hybridizes to the amplicon. [0031] As used herein, “plurality” means two or more. [0032] As used herein, “specifically hybridizes,” in reference to oligonucleotide sets, oligonucleotide primers, or oligonucleotide probes, means that said oligonucleotide sets, primers or probes hybridize to a nucleic acid sequence of a single HPV type. [0033] As used herein, “gene” means a segment of nucleic acid involved in producing a polypeptide chain. It includes both translated sequences (coding region) and 5′ and 3′ untranslated sequences (non-coding regions) as well as intervening sequences (introns) between individual coding segments (exons). For purposes of the description of the embodiments of the present invention, the HPV genome has a plurality of genes: e.g., L1, L2, and E1, E2, E4-E7. [0034] As used herein, “locus” refers to the position on a chromosome at which the gene for a trait resides. The term locus includes any one of the alleles of a specific gene. It also includes homologous genes from different HPV types. For example, PCR assays that detect the L1 gene in HPV16 and HPV6 are single-locus assays, despite the detection of sequences from different HPV types. Contrarily, for example, assays that detect the L1 gene and the E1 gene of a single HPV type are multiple locus assays, even though a single HPV type is detected. [0035] As used herein, “HPV” means human papillomavirus. “HPV” is a general term used to refer to any type of HPV, whether currently known or subsequently described. [0036] As used herein, “fluorophore” refers to a fluorescent reporter molecule which, upon excitation with a laser, tungsten, mercury or xenon lamp, or a light emitting diode, releases energy in the form of light with a defined spectrum. Through the process of fluorescence resonance energy transfer (FRET), the light emitted from the fluorophore can excite a second molecule whose excitation spectrum overlaps the emission spectrum of the fluorophore. The transfer of emission energy of the fluorophore to another molecule quenches the emission of the fluorophore. The second molecule is known as a quencher molecule. The term “fluorophore” is used interchangeably herein with the term “fluorescent reporter”. [0037] As used herein “quencher” or “quencher molecule” refers to a molecule that, when linked to a fluorescent probe comprising a fluorophore, is capable of accepting the energy emitted by the fluorophore, thereby quenching the emission of the fluorophore. A quencher can be fluorescent, which releases the accepted energy as light, or non-fluorescent, which releases the accepted energy as heat, and can be attached at any location along the length of the probe. [0038] As used herein “dark quencher” refers to a non-fluorescent quencher. [0039] As used herein, “probe” refers to an oligonucleotide that is capable of forming a duplex structure with a sequence in a target nucleic acid, due to complementarity of at least one sequence of the probe with a sequence in the target region, or region to be detected. The term “probe” includes an oligonucleotide as described above, with or without a fluorophore and a quencher molecule attached. The term “fluorescent probe” refers to a probe comprising a fluorophore and a quencher molecule. [0040] As used herein, “FAM” refers to the fluorophore 6-carboxy-fluorescein. [0041] Other embodiments of the invention use different oligonucleotide sequences that bind to the E6/E7 gene region of HPV. The oligonucleotides described herein have a sequence that is capable of binding to the target nucleic acid sequence (and its complementary strand). The oligonucleotides described herein may also be used, either alone or in combination, to facilitate detection through amplification of the HPV E6/E7 gene nucleic acid sequence. In one embodiment, the probes are designed to perform a Taq-Man® real-time PCR assay on the target portion of the gene. Examples of three degenerate probes sets used for Taq-Man® real-time PCR assays, described in terms of their oligonucleotide sequences, are described below. [0042] Specifically, in the first embodiment where the first degenerate primer/probe set is for HPV types 39 and 68, the primer/probe set that prefers HPV type 39 are SEQ ID NOS: 1, 3 and 5. The primer/probe set that prefers HPV type 68 are SEQ ID NOS. 2, 4 and 6. SEQ ID NOS 1 and 2 are both Taq-Man forward primers and are degenerate with respect to each other. SEQ ID NOS 3 and 4 are both Taq-Man reverse primers and are degenerate with respect to each other. SEQ ID NOS 5 and 6 are both Taq-Man probes and are degenerate with respect to each other. The degenerate primer/probe sets for HPV types 33 and 58 are SEQ ID NOS. 7-16, which include two alternative reverse primer sequences, SEQ ID NOS. 13 and 14 being preferred. The degenerate primer/probe sets for HPV types 56 and 66 are SEQ ID NOS. 17-23. The primer/probe sequences that select or discriminate for HPV serotype 51 are SEQ ID NOS. 24-29. The primer/probe sequences that select or discriminate for HPV Type 59 are SEQ ID NOS. 30-35. All the sequences referenced above are enumerated in Table 1 below. In the table below, “D” is detector, “FP” is forward primer, and “RP” is reverse primer. [0000] TABLE 1 SEQ ID NO. Name Description Oligonucleotide Sequence: 5′-3′ SEQ ID NO: 1 GR39_68E6 HPV 39 E6  CCACTAGCTGCATGCCAATC FP2 (39) Taq-Man Forward Primer SEQ ID NO: 2 GR39_68E6 HPV 68 E6 CCATTAGCTGCATGCCAATC FP2 (68) Taq-Man Forward Primer SEQ ID NO: 3 GR39_68E6 HPV 39 E6 CTAATGTAGTTGCATACACCGA RP4 (39) Taq-Man Reverse Primer SEQ ID NO: 4 GR39_68E6 HPV 68 E6 CTAATGTTGTTGCATACACCGA RP4 (68) Taq-Man Reverse Primer SEQ ID NO: 5 GR39_68D5 HPV 39 E6 GAGTAATATCGTAGCTCCCGTATTTT (39) Taq-Man Probe SEQ ID NO: 6 GR39_68D5 HPV 68 E6 GAGTAATATCGTAGTTCCCGTATTTT (68) Taq-Man Probe SEQ ID NO: 7 GR33_58FP2 HPV 33 E6 TGTGCCAAGCATTGGAGACA (33) Taq-Man Forward Primer SEQ ID NO: 8 GR33_58FP2 HPV 58 E6 TGTGTCAGGCGTTGGAGACA (58) Taq-Man Forward Primer SEQ ID NO: 9 GR33_58RP2 HPV 33 E6 CAAATGGATTTCCCTCTCTATA (33) Taq-Man Reverse Primer SEQ ID NO: 10 GR33_58RP2 HPV 58 E6 CAAATGGATTTCCATCTCTATA (58) Taq-Man Reverse Primer SEQ ID NO: 11 GR33_58RP3 HPV 33 E6 CCTCTCTATATACAACTGTTAAA (33) Taq-Man Reverse Primer SEQ ID NO: 12 GR33_58RP3 HPV 58 E6 CCATCTCTATACACTATTCTTAAA (58) Taq-Man Reverse Primer SEQ ID NO: 13 GR33_58RP4 HPV 33 E6 AAATGGATTTCCCTCTCTATATAC (33) Taq-Man Reverse Primer SEQ ID NO: 14 GR33_58RP4 HPV 58 E6 AAATGGATTTCCATCTCTATACAC (58) Taq-Man Reverse Primer SEQ ID NO: 15 GR33_58D1 HPV 33 E6 TCATATACCTCAGATCGTTGCAAAG (33) Taq-Man Probe SEQ ID NO: 16 GR33_58D1 HPV 58 E6 TCATATACCTCAGATCGCTGCAAAG (58) Taq-Man Probe SEQ ID NO: 17 MP56_66FP HPV 56 E7 ACCTAATACACGTACCTTGTT (56) Taq-Man Forward Primer SEQ ID NO: 18 MP56_66FP HPV 66 E7 ACCTAATTCACGTACCTTGTT (66) Taq-Man Forward Primer SEQ ID NO: 19 MP56_66RP HPV 56 E7 ACACGCAGGTCCTCTTTGGT (56) Taq-Man Reverse Primer SEQ ID NO: 20 MP56_66RP HPV 66 E7 ACACGTAGCTCCTCTTTGGT (66) Taq-Man Reverse Primer SEQ ID NO: 21 MP56_66D HPV 56 E7 TGTAAGTTTGTGGTGCAGTTGGACA (56) Taq-Man Probe SEQ ID NO: 22 MP56_66D HPV 56 E7 TGTGAGCTTGTGGTGCAGTTGGACA (66.1) Taq-Man Probe SEQ ID NO: 23 MP56_66D HPV 66 E7 TGTGAGTTGGTGGTGCAGTTGGACA (66.2) Taq-Man Probe SEQ ID NO: 24 51E6 FP HPV 51 E6 GCAGTATGCAAACAATGTTCAC Forward Primer SEQ ID NO: 25 51E6 RP HPV 51 E6 TAGTAATTGCCTCTAATGTAGTA Reverse Primer SEQ ID NO: 26 51E6 D HPV 51 E6 CCTGCTATAACGTCTATACTCTCTA Taq-Man Probe SEQ ID NO: 27 51E7 FP HPV 51 E7 CTCAGAGGAGGAGGATGAAG Forward Primer SEQ ID NO: 28 51E7 RP HPV 51 E7 TGAACACCTGCAACACGGAG Reverse Primer SEQ ID NO: 29 51E7 D HPV 51 E7 CTACCAGAAAGACGGGCTGGAC Taq-Man Probe SEQ ID NO: 30 59E6 FP HPV 59 E6 GGAGAAACATTAGAGGCTGAA Forward Primer SEQ ID NO: 31 59E6 RP HPV 59 E6 ATAGAGGTTTTAGGCATCTATAA Reverse Primer SEQ ID NO: 32 59E6 D HPV 59 E6 ACCGTTACATGAGCTGCTGATACG Taq-Man Probe SEQ ID NO: 33 59E7 FP HPV 59 E7 GAAGTTGACCTTGTGTGCTAC Forward Primer SEQ ID NO: 34 59E7 RP HPV 59 E7 ATTAACTCCATCTGGTTCATCTT Reverse Primer SEQ ID NO: 35 59E7 D HPV 59 E7 ATTACCTGACTCCGACTCCGAGAA Taq-Man Probe SEQ ID NO: 36 Target Region for 91 CCATTAGCTGCATGCCAATCATGTATTAAAT Degenerate Primer nucleotide TTTATGCTAAAATACGGGAACTACGATATTA Probe Sets for HPV Target Region CTCAGAATCGGTGTATGCAACAACATTAG Types 39 and 68 SEQ ID NO: 37 Target Region for 138 TGTGCCAAGCATTGGAGACAACTATACACAA Degenerate Primer nucleotide CATTGAACTACAGTGCGTGGAATGCAAAAAG Probe Sets for HPV Target Region ACTTTGCAACGATCTGAGGTATATGATTTTG Types 33 and 58 CATTTGCAGATTTAACAGTTGTATATAGAGA GGGAAATCCATTTG SEQ ID NO: 38 Target Region for 79 ACCTAATACACGTACCTTGTTGTXAGTGTAA Degenerate Primer nucleotide GTTTGTGGTGCAGTTGGACATTCAGAGTACC Probe Sets for HPV Target Region AAAGAGGACCTGCGTGT Types 56 and 66 The locations of the target regions for the primer/probe sets described in the above table are described in the following Table 1A: [0000] TABLE 1A Location of Target Regions Target Region Genotype GenBank Accession # Coordinates 39 M62849 287-377 68 EU918769 181-271 33 M12732 152-288 58 D90400 153-289 56 X74483 747-825 66 EF177190 747-825 [0043] While there is sequence homology between the target regions for the degenerate primer/probe sets, the coordinates of these regions are genotype dependent. [0044] In a further embodiment, the method includes treating a sample using at least one degenerate primer/probes set to select for two different but closely related HPV types and a primer/probe set that discriminates for a third HPV type, where the signal moiety for the degenerate probes emits a signal of the same wavelength and is, preferably, the same signaling moiety for the two degenerate probes. The signaling moiety of the primer/probe set that discriminates for the third HPV type emits signal at a wavelength that is different, and therefore separately detectable, from the wavelength emitted by the signaling moieties for the degenerate probes. These primer/probe sets are used in a nucleic acid amplification reaction for detecting the presence or absence of the amplified nucleic acid product. [0045] In another embodiment, a kit is provided for the detection of HPV. The kit includes at least one degenerate primer/probes set that selects for two different but closely related HPV types and a primer/probe set that discriminates for a third HPV type, where the signal moiety for the degenerate probes emits a signal of the same wavelength and is, preferably, the same signaling moiety for the two degenerate probes. The signaling moiety of the primer/probe set that discriminates for the third HPV type emits signal at a wavelength that is different, and therefore separately detectable, from the wavelength emitted by the signaling moieties for the degenerate probes. The primer/probe sets capable of amplifying a target sequence that may be used for detection of that organism. The kit is provided with one or more of the oligonucleotides and buffer reagents for performing amplification assays. [0046] In yet another aspect of the kit, oligonucleotides and reagents for purposes of Taq-Man PCR may be provided. In this aspect, three oligonucleotides are provided. Two of the three are amplification primers and the third oligonucleotide is configured as a detector. BRIEF DESCRIPTION OF THE DRAWINGS [0047] FIG. 1 illustrates the E6 gene target region for the HPV type 68 and schematically, the degeneracy of that target sequence among various mutations of HPV type 68, HPV type 39 and mutations of HPV type 39 along with the degenerate primer/probe set for HPV types 39 and 68; [0048] FIG. 2A-B illustrates the E6 gene target region for the HPV type 33 and schematically, the degeneracy of that target sequence among various mutations of HPV type 33, HPV type 58 and mutations of HPV type 33 along with the degenerate primer/probe set for HPV types 33 and 58; and [0049] FIG. 3 illustrates the E7 gene target for HPV type 66 and schematically, the degeneracy of that target sequence among various mutations of HPV type 66, HPV type 56 and mutations of HPV type 56 along with the degenerate primer/probe set for HPV types 56 and 66. DETAILED DESCRIPTION OF THE INVENTION [0050] The oligonucleotide probes and probes sets described herein are specifically designed to select for or discriminate between HPV types. Specifically, degenerate primer/probe sets that are somewhat selective for one of two closely related HPV types are combined with at least one other primer/probe set that discriminates for yet a third HPV type that is different from the closely related HPV types. [0051] The primer/probe sets provide a detectable signal when the specific HPV type is present in the sample. [0052] In the preferred embodiments, the PCR (e.g. Taq-Man PCR), method of detection is used although other methods (e.g. TMA, and LCR) are also contemplated. Further, a kit for detecting more HPV types than there are channels for detection is disclosed. [0053] Referring to FIG. 1 , the degenerate primer/probe sets specific for HPV types are described in terms of their alignment with the illustrate target region of the E6 gene. [0054] FIG. 1 illustrates the forward primer region 10, the Taq-Man Detection Region 20 and the reverse primer region 30. FIG. 1 also illustrates the degenerate forward primers 11, 12, degenerate reverse primers 31, 32 and degenerate probes 21 and in relation to their corresponding region on the target sequence 40. Only the variations in the target sequence 40 with respect to the forward primer region, reverse primer region and detector regions are illustrated in the boxes 60, 70 and 80. Sequence degeneracy between these regions are noted and from that it can be observed that these regions are less desirable because of increased sequence variation in these regions. [0055] For example, in box 60 note that there are single nucleotide polymorphisms (T, C) between the portion of the target sequence 40 delimited by box 60 and the same E6 portion of an HPV type 39 target. Boxes 60, 70 and 80 illustrate the nucleotide polymorphisms relative to target for different strains of HPV types 68 and 39. These different strains, and the number and location of the nucleotide polymorphisms (relative to target) are reported in Table 2. [0000] TABLE 2 Polymorphisms Illustrated in FIG. 1 Relative to Target Number of Polymorphisms Type/Strain (location from 5′) Type 68 68_A7_High_45240-DQ80079. seq 3 [T(@6); G(@66); T(@84)] 68_A7_High_45240-EU918769.seq None BD115-68 900bp.seq 3 [C(@21); A(@46); C(@81)] BD-637-68 900bp.seq 1 [G(@31)] T276-68 900bp.seq None T1177-68 900bp.seq 3 [T or C (@6); C(@81); T or T(@84) T1610-68 900bp 071309.seq 2 [G(@53); C(@81)] Type 39 23, A7, High, 10568, 6 [C(@4); A(@27); G (@51) M62849.seq G(@66); C(@69); T(@84)] S492-39 900bp.seq 8 [T(@3); C(@4); A(@27); G (@51) G(@66); C(@69); G(@80); T(@84)] T296-39 900bp.seq 7 [C(@4); A(@27); G (@51); C(@57); G(@66); C(@69); T(@84)] [0056] The forward primer 11 for HPV 39 has a single nucleotide polymorphism and is therefore degenerate with respect to the forward primer 12 for HPV 68. Forward primer 11 is SEQ ID NO. 1 and forward primer 12 is SEQ ID NO. 2. The degeneracy between the two sequences is readily observed: [0000] CCA C TAGCTGCATGCCAATC CCA T TAGCTGCATGCCAATC [0057] The respective degeneracy is indicated by underlining. [0058] The degeneracy makes forward primer prefer to bind to HPV type 39 and forward primer 12 prefer to bind to HPV type 68. The degenerate primer/probes sets prefer to bind to the target of one HPV type to the other type but do not discriminate. In terms of the Figures, the primer/probe sets are described in relation to the target. Boxes 60, 70 and 80 contain information about degeneracy among HPV types 39 and 68 with respect to the target region 40 delimited by the boxes 60, 70 and 80. This is a location reference and not a hybridization reference. Specifically, the reverse primers 31 and 32 (SEQ ID NOs. 3 and 4) have sequences that are the reverse complement of the sequence in their corresponding location on target 40. Similarly, detector probes 21 and 22 (SEQ ID NOS. 5 and 6) are the reverse complement of the sequence in their corresponding location on target 40. Forward primers 11 and 12 (SEQ ID NOS. 1 and 2) are homologous to the sequence in their corresponding location on target 40. [0059] FIG. 2A-B is similar to FIG. 1 , but for degenerate primer/probe sets that select for HPV types 33 and 58. Boxes 160, 170 and 180 illustrate the nucleotide polymorphisms relative to target for different strains of HPV types 33 and 58. These different strains, and the number and location of the nucleotide polymporphisms (relative to target) are reported in Table 3. The location of the polymorphisms is illustrated in FIG. 2 . [0000] TABLE 3 Polymorphisms Illustrated in FIG. 2A-B Relative to Target Type/Strain Number of Polymorphisms Type 33 33_A9_High_10586 EF422125.seq 3 [C(@30); A(@62); C(@63)] 33_A9_High_10586 EF422126.seq 3 [C(@62); C(@63); T(@52)] 33_A9_High_10586 EF566920.seq 3 [C(@62); C(@63); A(@99)] 33_A9_High_10586 EF566921.seq 2 [C(@62); C(@63)] 33_A9_High_10586 EF918766.seq 4 [G(@58); C(@62); C(@63); G(@122)] 33_A9_High_10586 GO374550.seq 1 [A(@62)] 33_A9_High_10586 GO374551.seq 2 [G(@54); A(@62)] 33_A9_High_10586 GO374552.seq 2 [T(@10); A(@62)] 33_A9_High_10586 M12732.seq 2 [A(@62); C(@63)] BD670 grp33 900bp.seq 1 [A(@62)] BD783-33 900bp.seq 3 [C(@62); C(@63); C(@92)] BD783-33 clone 900bp.seq 2 [C(@62); C(@63)] TI093-33 900bp.seq 2 [G(@54); A(@62)] Type 58 HPV_58 D60400.seq 23 [See FIGS. 2A-B for location] T-275-58 900bp.seq 22 [See FIGS. 2A-B for location] T-276-58 900bp.seq 24 [See FIGS. 2A-B for location] T-817-58 clone 900bp.seq 23 [See FIGS. 2A-B for location] 58_A9 High E6 10598 AF478160 23 [See FIGS. 2A-B for location] 58_A9 High E6 10598 AF478167 22 [See FIGS. 2A-B for location] 58_A9 High E6 10598 AF234531 23 [See FIGS. 2A-B for location] 58_A9 High E6 10598 AF478157 23 [See FIGS. 2A-B for location] 58_A9 High E6 10598 EU080239 25 [See FIGS. 2A-B for location] 58_A9 High E6 10598 FJ407192 24 [See FIGS. 2A-B for location] 58_A9 High E6 10598 GO248229 23 [See FIGS. 2A-B for location] 58_A9 High E6 10598 GO248253 22 [See FIGS. 2A-B for location] [0060] FIG. 2A-B illustrates the forward primer region 110, the Taq-Man Detection Region 120 and the reverse primer region 130. FIG. 2A-B also illustrates the degenerate forward primers 111, 112, degenerate reverse primers 131, 132 and degenerate probes 121 and 122 in relation to their corresponding region on the target sequence 140. Only the variations in the target sequence 140 with respect to the forward primer region, reverse primer region and detector regions are illustrated in the boxes 160 ( FIG. 2A ), 170 and 180 ( FIG. 2B ). [0061] For example, in box 160 note that there are single nucleotide polymorphisms (T, G, G) between the portion of the target sequence 140 delimited by box 60 and the same E6 portion of an HPV type 33 target. However, the forward primer 112 for HPV 58 has three single nucleotide polymorphisms and is therefore degenerate with respect to the forward primer 111 for HPV 33. Forward primer 111 is SEQ ID NO. 7 and forward primer 112 is SEQ ID NO. 8. The degeneracy between the two sequences is readily observed: [0000] TGTGCCAAGCATTGGAGACA TGTG T CA G GC G TTGGAGACA The respective degeneracy is indicated by underlining. [0062] The degeneracy makes forward primer 111 prefer to bind to HPV type 33 and forward primer 112 prefer to bind to HPV type 58. The degenerate primer/probes sets prefer to bind to the target of one HPV type to the other type but do not discriminate. In terms of the Figures, the primer/probe sets are described in relation to the target. Boxes 160, 170 and 180 contain information about degeneracy among HPV types 33 and 58 with respect to the target region 140 delimited by the boxes 160, 170 and 180. This is a location reference and not a hybridization reference. Specifically, the reverse primers 131 and 132 (e.g. SEQ ID NOs. 13 and 14) have sequences that are the reverse complement of the sequence in their corresponding location on target 140. Similarly, reverse probes 121 and 122 (SEQ ID NOS. 15 and 16) are the reverse complement of the sequence in their corresponding location on target 140. Forward primers 111 and 112 (SEQ ID NOS. 7 and 8) are homologous to the sequence in their corresponding location on target 140. [0063] FIG. 3 is similar to FIGS. 1 and 2 , but for degenerate primer/probe sets that select for HPV types 56 and 66. FIG. 3 illustrates the forward primer region 210, the Taq-Man Detection Region 220 and the reverse primer region 230. Boxes 260, 270 and 280 illustrate the nucleotide polymorphisms relative to target for different strains of HPV types 66 and 56. These different strains, and the number and location of the nucleotide polymporphisms (relative to target) are reported in Table 2. [0000] TABLE 4 Polymorphisms Illustrated in FIG. 3 Relative to Target Number of Polymorphisms Type/Strain (location from 5′) Type 66 66_A6_High_37119-EF177191 6 [T(@8); A(@24); G(@30) C(@33); G(@71); A(@74)] 66_A6_High_37119-EF177188 7 [T(@8); T(@9); A(@24); G(@30) C(@33); G(@71); A(@74)] 66_A6_High_37119-EF177186 6 [T(@8); A(@24); G(@30) G(@35); G(@71); A(@74)] Type 56 56_A6_High_37119-EF177176 2 [G(@24); C(@56)] 56_A6_High_37119-EF177178 3 [C(@20); C(@23); C(@24)] 56_A6_High_37119-EF177179 1 [C(@24)] 56_A6_High_37119-EF177180 1 [G(@24)] BD616grp56 E7 3[G(@24); T(@54); C(@56)] T1631-56 E7 1 [A(@24)] [0064] FIG. 3 also illustrates the degenerate forward primers 211, 212, degenerate reverse primers 231, 232 and degenerate probes 221 and 222 in relation to their corresponding region on the target sequence 240. Only the variations in the target sequence 240 with respect to the forward primer region, reverse primer region and detector regions are illustrated in the boxes 260, 270 and 280. [0065] For example, in box 260 note that there are two single nucleotide polymorphisms (T, C) between the portion of the target sequence 240 delimited by box 260 between and HPV target and an HPV 56 target. However, the forward primer 2112 for HPV 56 has a single nucleotide polymorphism and is therefore degenerate with respect to the forward primer 211 for HPV 66. Forward primer 211 is SEQ ID NO. 17 and forward primer 212 is SEQ ID NO. 18. The degeneracy between the two sequences is readily observed: [0000] ACCTAATACACGTACCTTGTT ACCTAAT T CACGTACCTTGTT The respective degeneracy is indicated by underlining. [0066] The degeneracy makes forward primer 211 prefer to bind to HPV type 56 and forward primer 212 prefer to bind to HPV type 66. The degenerate primer/probes sets prefer to bind to the target of one HPV type to the other type but do not discriminate. In terms of the Figures, the primer/probe sets are described in relation to the target. Boxes 260, 270 and 280 contain information about degeneracy among HPV types 56 and 66 with respect to the target region 240 delimited by the boxes 260, 270 and 280. This is a location reference and not a hybridization reference. Specifically, the reverse primers 231 and 232 (SEQ ID NOs. 19 and 20) have sequences that are the reverse complement of the sequence in their corresponding location on target 240. Similarly, probes 221 and 222 (SEQ ID NOS. 22 and 23) are the reverse complement of the sequence in their corresponding location on target 240. Forward primers 211 and 212 (SEQ ID NOS. 17 and 18) are homologous to the sequence in their corresponding location on target 140. While not specifically discussed, the degeneracy between the reverse primers and probes in the degenerate primer probe sets is readily observed. [0067] In addition to the examples of degenerate primer/probe sets described herein, the skilled person, based upon the description herein and the accompanying figures, would be able to identify other target regions of closely related serotypes for which degenerate primer/probe sets could be designed. As is readily observed by the Figures, desirable target regions will have few polymorphisms between the individual serotypes. Those polymorphisms that are present can be addressed in the design of the degenerate primer/probe set consistent with the manner described herein. [0068] As described below, primers and probes can bind to target sequences even though they are less than 100% complementary with those regions. The requisite degree of complementarity depends on a variety of factors including the stringency of the binding conditions. Depending upon the stringency conditions employed, the primers and probes may be modified to include different bases in their sequence and still be sufficiently complementary to bind to the target region of the nucleic acid. Sufficiently complementary, as used herein include complementarity of 70% or more. In preferred embodiments, the complementarity of the primers/probes to their target sequence is at least 80% over the length of the binding portion of the primers/probes. More preferably, the complementarity of the primers and probes to their target sequences is 90% or more. [0069] Said another way, the present invention contemplates primers and probes that have at least 70% homology with the primers and probes specifically identified herein by SEQ ID. In preferred embodiments, primers/probes that have at least 80% homology with the primers and probes specifically identified by SEQ ID herein are contemplated. More preferably, primers and probes that have at least 90% homology with the primers and probes specifically identified by SEQ ID herein are contemplated. [0070] While the oligonucleotides described herein must be sufficiently complementary to bind their respective portions of the HPV target for which they discriminate, it is recognized at some point the sequence of the oligonucleotide becomes less complementary to its target and may bind other nucleic acid sequences. Therefore, it is desirable that the oligonucleotide probes remain sufficiently complementary with its respective portion of the target gene, and not lose selectivity for its respective target binding site. [0071] The target binding sequence within the oligonucleotide amplification primer may generally be located at its 3′ end. The target binding sequence may be about 10-25 nucleotides in length and may have hybridization specificity to the amplification primer. Thus, it is understood that one skilled in the art may change the target binding sequence to effectively change hybridization specificity of the amplification primer and direct hybridization to an alternative sequence. [0072] It is understood to one skilled in the art that the oligonucleotides as used in amplification assays may be modified to some extent without loss of utility or specificity towards a target sequence. For example, as is known in the art, hybridization of complementary and partially complementary nucleic acid sequences may be obtained by adjustment of the hybridization conditions to increase or decrease stringency (i.e., adjustment of hybridization temperature or salt content of the buffer). Such minor modifications of the disclosed sequences and any necessary adjustments of hybridization conditions to maintain target-specificity require only routine experimentation and are within the ordinary skill in the art. [0073] As a general guide in designing oligonucleotides useful as primers, T m decreases approximately 1° C.-1.5° C. with every 1% decrease in sequence homology. Temperature ranges may vary between about 60° C. and 70° C., but the primers may be designed to be optimal at 60° C.±4° C. and the probes may be designed to be optimal at 70° C.±4° C. A further consideration when designing amplification primers may be the guanine and cytosine content. Generally, the GC content for a primer may be about 60-70%, but may also be less and can be adjusted appropriately by one skilled in the art. Annealing complementary and partially complementary nucleic acid sequences may be obtained by modifying annealing conditions to increase or decrease stringency (i.e., adjusting annealing temperature or salt content of the buffer). Modifications such as those to the disclosed sequences and any necessary adjustments of annealing conditions to maintain gene specificity require only routine experimentation and are within the ordinary skill in the art. [0074] Amplification reactions employing the primers described herein may incorporate thymine as taught by Walker, et al., supra, or they may wholly or partially substitute 2′-deoxyuridine 5′-triphosphate for TTP in the reaction to reduce cross-contamination of subsequent amplification reactions, e.g., as taught in EP 0 624 643. dU (uridine) is incorporated into amplification products and can be excised by treatment with uracil DNA glycosylase (UDG). These abasic sites render the amplification product not amplifiable in subsequent amplification reactions. UDG may be inactivated by uracil DNA glycosylase inhibitor (Ugi) prior to performing the subsequent amplification to prevent excision of dU in newly-formed amplification products. [0075] PCR DNA polymerase contemplated for use in the present invention has 5′-3′ exonuclease activity (e.g., Sequencing Grade Taq from Promega or Deep Vent R ™ (exo-) DNA from New England BioLabs) are used. The probe hybridizes to the target downstream from the PCR amplification primers. The probe is displaced as the downstream endonuclease synthesis proceeds from the primers between which the probe is disposed. As thermocycling is a feature of amplification by PCR, the restriction endonuclease is preferably added at low temperature after the final cycle of primer annealing and extension for end-point detection of amplification. However, a thermophilic restriction endonuclease which remains active through the high temperature phases of the PCR reaction could be present during amplification to provide a real-time assay. Linearization of the secondary structure and separation of the dye pair reduces fluorescence quenching, with a change in a fluorescence parameter such as intensity serving as an indication of target amplification. [0076] The change in fluorescence resulting from unfolding or linearizing of the detector oligonucleotides may be detected at a selected endpoint in the reaction. However, because linearized secondary structures are produced concurrently with hybridization or primer extension, the change in fluorescence may also be monitored as the reaction is occurring, i.e., in “real-time”. This homogeneous, real-time assay format may be used to provide semi quantitative or quantitative information about the initial amount of target present. When more initial copies of the target sequence are present, donor fluorescence more rapidly reaches a selected threshold value (i.e., shorter time to positivity). The decrease in acceptor fluorescence similarly exhibits a shorter time to positivity, detected as the time required for reaching a selected minimum value. In addition, the rate of change in fluorescence parameters during the course of the reaction is more rapid in samples containing higher initial amounts of target than in samples containing lower initial amounts of target (i.e., increased slope of the fluorescence curve). These or other measurements as is known in the art may be made as an indication of the presence of target or as an indication of target amplification. The initial amount of target is typically determined by comparison of the experimental results to results for known amounts of target. [0077] Assays for the presence of a selected target sequence according to the methods of the invention may be performed in solution or on a solid phase. Real-time or endpoint homogeneous assays in which the detector oligonucleotide functions as a primer are typically performed in solution. Hybridization assays using the detector oligonucleotides of the invention may also be performed in solution (e.g., as homogeneous real-time assays) but are also particularly well-suited to solid phase assays for real-time or endpoint detection of target. In a solid phase assay, detector oligonucleotides may be immobilized on the solid phase (e.g., beads, membranes or the reaction vessel) via internal or terminal labels using methods known in the art. For example, a biotin-labeled detector oligonucleotide may be immobilized on an avidin-modified solid phase where it will produce a change in fluorescence when exposed to the target under appropriate hybridization conditions. Capture of the target in this manner facilitates separation of the target from the sample and allows removal of substances in the sample which may interfere with detection of the signal or other aspects of the assay. [0078] For commercial convenience, oligonucleotides useful for specific detection and identification of HPV nucleic acids may be packaged in the form of a kit. Typically, such a kit contains at least one oligonucleotide described herein. Reagents for performing a nucleic acid amplification reaction may also be included with the HPV-specific oligonucleotides. For example, buffers, other oligonucleotides, nucleotide triphosphates, enzymes, etc. may be included. The components of the kit may be packaged together in a common container. Optionally instructions may be included that illustrate one described embodiment for performing a specific embodiment of the inventive methods. Other optional components may also be included in the kit, e.g., an oligonucleotide tagged with a label suitable for use as an assay probe, and/or reagents or means for detecting the label. [0079] Furthermore, the kit may include oligonucleotides and reagents in dried or liquid format. The components of the kit may be more stable and easily manipulated when in dried format. The dried components of the kit may be added or pre-treated to a solid phase such as microtiter plate, microarray, or other appropriate receptacle, where the sample and buffer need only be added. This format facilitates assaying multiple samples simultaneously and is useful in high-throughput methods. The BD ProbeTec™ and Viper™ XTR instruments may be used. [0080] The following Examples illustrate specific embodiments of the invention described herein. As would be apparent to skilled artisans, various changes and modifications are possible, and are contemplated within the scope of the invention described. [0081] A Taq-Man PCR System for Detecting HPV is further described below using the primer/probes sets in Table 1 as an Example. The Primer Sets of Primers/Probes described in Table 1 above were designed to perform Taq-Man PCR on for HPV types 39 and 68 and 51. Specifically, in the first embodiment where the first degenerate primer/probe set is for HPV types 39 and 68, the primer/probe set that prefers HPV type 39 are SEQ ID NOS: 1, 3 and 5. The primer/probe set that prefers HPV type 68 are SEQ ID NOS. 2, 4 and 6. [0082] Taq-Man real-time PCR is a type of quantitative PCR. Taq-Man uses a fluorogenic probe which is a single stranded oligonucleotide of 20-26 nucleotides and is designed to bind only the DNA sequence between the two PCR primers. In Taq-Man, reporter dyes and quencher dyes are attached to the probe. The probe is annealed to the DNA by alternating the temperature to denature and re-anneal the DNA. The Taq polymerase adds nucleotides to the target DNA and this removes the Taq-Man probe from the template DNA. When the reporter dye is separated from the quencher dye, the reporter dye emits energy which is detectable. The energy is quantified by a computer, which provides a signal indicating that the target was detected. Only the specific PCR product can generate the fluorescent signal in Taq-Man PCR. [0083] In the example herein, thermal cycling is contemplated. After an initial denature step at 95° C. for 15 minutes, the PCR mixture of primer/probe sets and sample for the detection of the presence or absence of target is subjected to the thermal cycle of 55° C. for 1 minute followed by 95° C. for 30 seconds for forty cycles. [0084] To practice Taq-Man PCR, two PCR primers with a preferred product size of 50-150 base pairs and a probe with a fluorescent reporter or fluorophore (e.g. 6-carboxyfluorescein (FAM) and tetrachlorofluorescin (TET)) and a quencher such as tetramethylrhodamine (TAMRA) or a dark quencher such as previously described is covalently attached to its 5′ and 3′ ends are used. Suitable fluorescent reporters and fluorophores are well known and not described in detail herein. [0000] TABLE 5 Examples of Taq-Man PCR Probes Sets for Taq-Man Assay of HPV Types 39, 68 and 51 ORF Location (bp) Genbank Accession in SEQ ID NO: Probe description Oligonucleotide 5′ Sequence 3′ () SEQ ID NO: 1 HPV 39 E6 CCACTAGCTGCATGCCAATC 287-306 Taq-Man (M62849) Forward Primer SEQ ID NO: 2 HPV 68 E6 CCATTAGCTGCATGCCAATC 181-200 Taq-Man (EU918769) Forward Primer SEQ ID NO: 3 HPV 39 E6 CTAATGTAGTTGCATACACCGA 356-377 Taq-Man (M62849) Reverse Primer SEQ ID NO: 4 HPV 68 E6 CTAATGTTGTTGCATACACCGA 250-271 Taq-Man (EU918769) Reverse Primer SEQ ID NO: 5 HPV 39 E6 GAGTAATATCGTAGCTCCCGTATTTT 326-351 Taq-Man (M62849) Probe SEQ ID NO: 6 HPV 68 E6 GAGTAATATCGTAGTTCCCGTATTTT 220-245 Taq-Man (EU918769) Probe SEQ ID NO: 24 HPV 51 E6 GCAGTATGCAAACAATGTTCAC 277-298 Forward Primer (M62866) SEQ ID NO: 25 HPV 51 E6 TAGTAATTGCCTCTAATGTAGTA 351-373 Reverse Primer (M62877) SEQ ID NO: 26 HPV 51 E6 CCTGCTATAACGTCTATACTCTCTA 315-339 Taq-Man (M62877) Probe SEQ ID NO: 27 HPV 51 E7 CTCAGAGGAGGAGGATGAAG 652-671 Forward Primer (M62877) SEQ ID NO: 28 HPV 51 E7 TGAACACCTGCAACACGGAG 738-757 Reverse Primer (M62877) SEQ ID NO: 29 HPV 51 E7 CTACCAGAAAGACGGGCTGGAC 692-713 Taq-Man (M62877) Probe [0085] The probes are designed to anneal to the ORF location in the HPV E6/E7 gene that is noted in the Table. In this regard, the ORF locations for the primer probe/set for HPV 59 for both the E6 and E7 genes are listed in the following table. [0000] TABLE 6 ORF Locations of E6/E7 for Primer/Probe Set for HPV Type 59 ORF Location (bp) Genbank Accession in SEQ ID NO: Probe description Oligonucleotide 5′ Sequence 3′ () SEQ ID NO: 30 HPV 59 E6 GGAGAAACATTAGAGGCTGAA 313-333 Forward Primer (X77858) SEQ ID NO: 31 HPV 59 E6 ATAGAGGTTTTAGGCATCTATAA 369-391 Reverse Primer (X77858) SEQ ID NO: 32 HPV 59 E7 ACCGTTACATGAGCTGCTGATACG 342-365 Taq-Man (X77858) Probe SEQ ID NO: 33 HPV 59 E7 GAAGTTGACCTTGTGTGCTAC 605-625 Forward Primer (X77858) SEQ ID NO: 34 HPV 59 E7 ATTAACTCCATCTGGTTCATCTT 660-682 Reverse Primer (X77858) SEQ ID NO: 35 HPV 59 E7 ATTAACTCCATCTGGTTCATCTT 631-654 Taq-Man (X77858) Probe [0086] In addition to the primers and probes, Taq-Man PCR requires reagents that are used for regular PCR (e.g. polymerase, free nucleotides) as well as a real-time PCR machine for analyzing the data. The reagents and equipment are well known to those skilled in the art and are not discussed in detail herein. [0087] Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the invention described herein. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the invention described herein as defined by the appended claims.

A real time Taq-Man PCR assay for detecting multiple serotypes of human papillomavirus (HPV) wherein the number of serotypes detected exceeds the number of colorimetric channels for detection. A biological sample is combined with three oligonucleotide primer/probe sets such that the probes and primers anneal to a target sequence. Each primer/probe set is at least preferential for a specific serotype of an organism. The first and second primer/probe sets are degenerate with respect to each other. The third primer/probe set is not degenerate with respect to the first and second primer/probe sets and discriminates for a third serotype. The third primer/probe set has a signal moiety that emits signal at a wavelength that is the same or different from the wavelength emitted by the signal moiety of the degenerate primer/probe set probes. The target sequences, if present, are amplified and detected.

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] This invention relates generally to the field of income estimation for lending purposes. [0003] 2. Description of the Prior Art [0004] In a conventional retail lending business, such as those involving mortgages, lender “documentation requirements” typically stipulate how the applicant must provide information about income and how the lender intends on using the information. Generally, full documentation remains the standard, where the applicant discloses income to the lender, the lender verifies the income, and then the lender uses the verified income in determining the applicant's ability to repay the loan. Formal verification, if required, typically includes the steps of the borrower's employer verifying employment and/or the borrower's bank verifying deposits. In order to save time, alternative documentation, such as copies of the borrower's original bank statements, W-2s, and paycheck stubs, may be used as surrogates. [0005] There are numerous conventional documentation programs in the mortgage lending business. Because many applicants are sometimes shut out of the market by excessively rigid documentation requirements, lenders realize the need for additional documentation programs, especially for those applicants who are self-employed or cannot easily document their income. In these situations, a stated income loan program is more commonplace, especially when the applicants disclose their income without verification. [0006] Stated income loans may be perceived to be riskier than full documentation loans. Without an adequate verification process, the lender risks that some applicants may overstate their income in order to achieve lower debt-to-income ratio, a key determinant of payment ability in the underwriting process, in order to obtain approval for a particular loan. As a result, applicants stating their income may compromise with higher rates, larger down payments, higher credit score requirements, or a combination thereof. From the lender's perspective, such tradeoffs may not justify the balance between risk and reward for stated income loans. From the applicants' perspective, higher rates and larger down payments are not desirable for those who honestly stated their actual income and opted for the stated income program in order to simplify the loan processing procedure or to maintain their privacy. [0007] Conventional income estimation systems are used in the fields of economics and social science, as well as by the U.S. government. However, these systems typically do not estimate an individual's income and do not use past credit and risk performance obtained from credit bureau attributes or an applicant's loan information. Various agencies of the U.S. government have developed different methodologies for estimating median income for the purpose of an area income census, housing affordability, or regional poverty levels. In one conventional system, the median household income for a small region was estimated as a function of various variables taken from administrative records. Although this method directly relates to income estimation, it does not translate to income estimation for an individual. In another non-analogous conventional system, an income estimation method correlates education levels with household income, which is not applicable in retail loan processing. Therefore, it is desirable to have a method and a system that estimates an applicant's income for a retail lending program by using credit bureau and loan attributes. SUMMARY OF THE INVENTION [0008] An automated method and system for estimating income of an individual loan applicant uses credit bureau information and loan attributes. The method and system can use the credit bureau and loan information to calibrate an applicant's debt-burden in cases where such information is not readily available or is unverifiable. The method and system can automatically verify income for applicants who choose to state their income in lieu of providing adequate documentation. Further, the method and system can be applicable to any retail lending business including, but not limited to, mortgage, auto loan, and credit cards, where credit bureau information forms a part of the data collection process and is available along with applicant's information. [0009] It is desirable that the method and system extract the relevant information from credit bureau and loan information to estimate an applicant's true income. Further, it is desirable to provide lenders with an option to extend an applicant the benefit of advantageous pricing in a stated income loan program based on a comparison between the applicant's stated income and the estimated income. [0010] The method and system described herein use techniques to select most predictive variables from a large pool of candidates, clean up the potential outliers/errors among a data set, and extracts the relevant information from the candidate predictors to build a final model to estimate the applicant's income. The parameters of a multivariate adaptive regression splines (“MARS”) based prediction system are estimated from a database consisting of borrower information on full-documentation loan consumers, where the actual income are known and have been verified. Development/hold-out/out-of-time validations along with bootstrap re-sampling techniques provide a model that attempts to minimize the error between actual income and predicted income. Furthermore, a cautious and systematic comparison is performed between stated debt ratio, i.e., debt-burden calculated from the applicant's stated income, and predicted debt ratio, i.e., debt-burden calculated from the estimated income. [0011] Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages. of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. [0012] It is to be understood that both the foregoing general description and the following detailed description are exemplary and are intended to provide further explanation of the invention as claimed. BRIEF DESCRIPTION OF THE DRAWINGS [0013] The present invention will be more clearly understood from a reading of the following description in conjunction with the accompanying exemplary figures wherein: [0014] FIG. 1 shows a flowchart of the method according to an exemplary embodiment of the present invention; [0015] FIGS. 2 a and 2 b show histograms of average months on file according to an exemplary embodiment of the present invention; [0016] FIG. 3 shows outlier detection according to an exemplary embodiment of the present invention; [0017] FIGS. 4 a and 4 b show outlier detection according to an exemplary embodiment of the present invention; [0018] FIG. 5 shows a bootstrapping chart according to an exemplary embodiment of the present invention; [0019] FIG. 6 shows a matrix of performance measures according to an exemplary embodiment of the present invention; [0020] FIG. 7 shows a confidence matrix according to an exemplary embodiment of the present invention; and [0021] FIG. 8 shows a table of performance according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION [0022] It will be recognized that the principles disclosed herein may extend beyond the realm of mortgages and that it may be applied to any lending process or other process requiring an estimation of income. [0023] Referring to FIG. 1 , a flowchart of the method according to an exemplary embodiment of the present invention is shown. In step 1 , applicant information is collected. The system collects information, such as credit bureau attributes and loan information, into a record. Preferably, the information is collected in or converted to a digital format. [0024] In step 2 , a database is formed. A valid case has full documentation applicants with verified income. These applicants' income values are used as a target dependent variable. Records corresponding to each valid case are stored in a database to be used for model construction, testing, and validation. [0025] Implementation of this system on a computer preferably utilizes a database, which can be hosted on a server that stores information on the borrowers in a digital format. Further, in order to replicate the model building steps involved in the methodology described below, the system preferably has a workstation having an installation (e.g., server/client or desktop) of any commonly available licensed commercial analytical/statistical software capable of running the techniques described herein or similar software or technique known to one of ordinary skill in the art. [0026] More specifically, in steps 1 and 2 , the system establishes a database of prior full-documentation applications along with corresponding loan and credit bureau attributes. The purpose of the full-documentation application is to build a valid model with a development sample having trusted and verified income as the target or dependent variable. This database also includes the applicants' loan application, as well as credit bureau attributes, which could be purchased from any or all of the three national credit bureaus: TransUnion, Equifax, or Experian. Accordingly, this database forms the basis of the system for income estimation development and validation. Preferably, the characteristics of the certified full documentation applications database closely resemble those of incoming stated income loan applications received within a reasonable time window, i.e., form a “representative sample.” [0027] In step 3 , the records are preprocessed to facilitate model construction by preliminary data cleansing and rearranging, which mainly focuses on defining a valid data scope and creating new predictive variables. The preprocessing step comprises four steps: ( 3 a ) defining valid data scope, i.e., focusing on the valid range for each field; ( 3 b ) missing values handling; ( 3 c ) recoding, i.e., generating valid values for each field; and ( 3 d ) variable transformation, i.e., defining new effective variables for model building. [0028] The system analyzes the data and its various characteristics in order to appropriately pre-process the data for extracting the maximum signal out of the available data. The system recognizes credit bureau attributes—all existing bureau coding rules that are used to replace the missing values or to represent ordinal categories—for examination and recoding in order to recreate valid values that can be used for model development. [0029] During this preprocessing step, the system defines a valid prediction scope for each variable and develops appropriate strategies for dealing with missing data fields. Additionally, the data is transformed or recreated to produce more effective variables under consideration. Examples would be—either converting one type of data to another, such as converting categorical values to numeric ones, or deriving new promising variables. We discuss these sub-steps in detail further. [0030] In step 3 a , a valid data scope is defined. Within different business scenarios, scopes for both dependent variables (e.g., income) and independent variables can be examined and the “normal acceptable range” can be extracted in accordance with the existing acceptable business criteria. For example, in the mortgage business, a loan-to-value (“LTV”) is an expression of the loan amount as a percentage of the total appraised value of a piece of real estate. Typically, the usual valid value of LTV ranges between 25 to 125%. Similarly, Debt ratios typically do not exceed 75%. Accordingly, all values beyond these ranges should be either truncated or discarded. [0031] In step 3 b , the system handles missing values. Because historical applicants' credit bureau attributes and loan information are used for income estimator development, missing values are almost unavoidable due to various underwriting system practices and/or data entry reasons. Various methodologies in literature can be applied to deal with missing values, such as single value substitution (mean/median/mode), class mean substitution, regression substitution, or other missing value replacement tools known to one of ordinary skill in the art. In this exemplary embodiment, the accounts with missing credit bureau attributes (i.e., no hits) are excluded from the development process, especially with adequate data in the available sample and instances of occurrence of such missing attributes are substantially negligible. [0032] In the data cleansing process of step 3 c , the system considers special coding rules for credit bureau attributes. For example, if an account has never had a record for certain numeric attributes, such as the common variable of number of open trades, the original bureau coding gives a value of “999” to this account. The value of “999” is not a valid number for model development. Accordingly, the system replaces the “999” coding with a “0.” [0033] In the variable transformation step 3d, new variables that can better predict income are generated from credit bureau attributes including, but not limited to, credit utilization, mortgage utilization, and months since bankruptcy. Credit Utilization %=(Total Credit Balance)/(Total Credit Limit)*100 Mortgage Utilization %=(Mortgage Balance)/(Mortgage Limit)*100 Months Since Bankruptcy=Interval (Bankruptcy Date, Application Date) [0034] In step 4, the system creates development, validation, and time validation sets. The system defines a time point beyond which all of the cases are used to form an out-of-time validation sample. Within the determined time point, all of the cases are split into a x % group, which is typically greater than 50%, e.g., 60%, for uses as a development sample and a 100-x % group for use as a hold-out validation sample. [0035] In step 5, a preliminary variable selection is performed. Important variables are selected out of a large pool of candidate variables obtained from the credit attributes and mortgage loan information. The system adopts techniques to choose a set of explanatory variables that have the maximum prediction power for creating the income estimator. Possible candidate predictors are created by combining credit bureau attributes, loan information, and newly created variables. In this exemplary embodiment, there are more than 150 possible candidate predictors. [0036] Various automatic variable selection methods can be applied to this income estimation process, such as stepwise selection under multivariate regression, partial least squares (“PLS”) regression with the variable importance in the projection (“VIP”) scores and estimated coefficients, genetic search driven by genetic algorithms (“GA”), classification and regression tree (“CART”), and Treenet, as well as any other variable selection methods known to one of ordinary skill in the art. Stepwise selection is commonly used due to its simplicity. However, when using stepwise selection, chosen predictors that look satisfactory in a sample can generalize poorly for “thru-the-door” data applied in practice. [0037] In this exemplary embodiment, prediction accuracy is comparatively more important than exploratory analysis of the relationship between income and other predictive variables. Treenet can be used in conjunction with CART as the main methodology to pre-select the most predictive variables, which are then used as the input variables for next-step MARS modeling. In addition, PLS Regression with the VIP Scores and Estimated Coefficients can also be used as a variable pre-selection method for building a competing Global Linear Regression, used in the experiments of prediction model building discussed below. [0038] Treenet is a gradient tree-boosting technique, which can select important variables out of complex data structures based on their relative prediction influence by using a slow learning process. Additionally, Treenet automates missing values handling and predictor selection, is substantially impervious to outliers, and self-tests to prevent over-fitting. Over-fitting occurs when the number of factors gets too large and the resulting model fits the sampled data, but fails to predict new data well. A Treenet model typically consists of hundreds of small additive regression trees, each of which contributes to the overall model. Its learning process can be a long series expansion, i.e., a sum of factors that becomes progressively more accurate as the expansion continues. The expansion can be written as: F ( X )= F 0 +β 1 T 1 ( X )+β 2 T 2 ( X )+. . . +β M T M ( X ) where F(X) represents the final Treenet model built from the underlying set of variables denoted by X and each T i (X) is a small tree with a limited number (e.g., restricted to 4-6) of leaf or terminal nodes and utilizes a suitable combination/subset of variables from the set X. F 0 represents the overall mean (i.e., average) value of the target variable and β i represent the corresponding additive weights (i.e., coefficients) of each tree as it related to the final Treenet model. [0039] By averaging the relative influences of each variable J j over the sum of the small trees, the final ranking of the variable importance is: J ^ j 2 ⁡ ( T ) = ∑ t = 1 L - 1 ⁢ I ^ t 2 ⁢ 1 ⁢ ( v t = j ) ( 1 ) J ^ j 2 = 1 M ⁢ ∑ m = 1 M ⁢ J ^ j 2 ⁡ ( T m ) ( 2 ) In equation (1), the summation is over the non-terminal nodes t of the L -terminal node tree T, v t is the splitting variable associated with node t, and Î t 2 is the corresponding empirical improvement in squared error as a result of the split. Equation (2) is the average value of J j over a collection of decision trees {T m } 1 M . The influence of the estimated most influential variable j* is arbitrarily assigned the value J j*= 100, and the estimated values of the others can be scaled accordingly. Top influential variables with relatively large influence values are selected as the candidate input variables for the next step of MARS model building. [0040] In PLS regression with the VIP scores and estimated coefficients, the regression coefficients represent the importance each predictor has in the prediction of the response and the VIP represents the value of each predictor in fitting the PLS model for both predictors and response. The variables, which have relatively larger coefficients (absolute value) and a large VIP score, are chosen as the pre-selected variables to build the Global Linear Regression model. [0041] In step 6, the system detects potential outliers and strange data values caused by possible typographical and uploading errors. Various methodologies in linear regression can be applied to this income estimation process to detect over-influential cases. Such methodologies include, but are not limited to, Euclidean distance in PLS model, studentized deleted residuals for detecting outlying dependent variable cases, hat matrix leverage values for detecting outlying independent variable cases, DFFITS, Cook's distance, and difference in betas (“DFBETAS”) for detecting influential cases in a linear regression model context, as well as other outlier detection tools, such as Random Forest. [0042] In this exemplary embodiment, a tail-capping rule can be applied to all Treenet-selected continuous variables. Additionally, Random Forest is used to detect potential outliers. Euclidean distance in PLS model is used to detect outliers for the Global Linear Regression model. [0043] To avoid seriously skewed distribution, extreme cases can be capped, e.g., capped at the 99 percentile value for all-important continuous variables. Thus, in this example, the 99 th percentile value of a continuous distribution leaves out the top 1 percent extreme values for the distribution. Referring to the histograms in FIGS. 2 a and 2 b , the distribution of average months on file before or after being capped is shown. [0044] The Random Forest classifier uses a large number of individual decision trees and decides the class by choosing the mode, i.e., most frequently occurring, of the classes as determined by the individual trees. Random Forest generates and combines decision trees into predictive models and display data patterns with a high degree of accuracy. Random Forest is a collection of CART trees that are not influenced by each other when constructed. The sum of the predictions made from decision trees determines the overall prediction of the forest. Two forms of randomization occur in Random Forests: (1) by trees and (2) by node. At the tree level, randomization takes place via observations. At the node level, randomization takes place by using a randomly selected subset of predictors. Each tree is grown to a maximal size and left unpruned, i.e., the tree is not scaled back into a simpler tree. The process is repeated until a user-defined number of trees is created. Once the forest of trees is created, the predictions for each tree are used in a “voting” process. The overall prediction is determined by voting for classification and by averaging for regression. [0045] In Random Forest, outliers are cases in which the proximity, as measured by an appropriately defined underlying distance metric, to all other cases in the data set exceeds an acceptance value or threshold. Referring to FIG. 3 , to apply Random Forest to the income estimation process, the system groups the monthly income value into a plurality of classes, e.g., four classes, according to equal percentile distribution, and outliers for each of the classes are found separately. [0046] In this embodiment, classes 1 to 4 represent four income groups in an ascending order. The cases that have large outlyingness are deleted from the development data set. [0047] The Euclidean distance from each case to the PLS model in both the standardized predictors and the standardized responses is used to check outliers for building the global linear multivariate regression model. Cases that are dramatically farther from the rest of the population are excluded from the model development sample as shown in the following FIGS. 4 a and 4 b. [0048] In step 7, the system experiments with varied modeling techniques such as global linear multivariate regression, regression tree and Treenet and MARS to create viable models. In this exemplary embodiment, MARS is selected as the final modeling paradigm. Because an applicant's monthly income is a continuous response variable, a variety of continuous response estimation or transfer function approximation techniques can be applied including, but not limited to, linear regression, regression tree, Treenet/MART and MARS. Predictive regression models can be built by using each of these regression-forecasting techniques. [0049] A global multivariate linear regression model, which is essentially a main-effects fit, can be built by using PLS regression with the VIP scores and estimated coefficients to pre-select input variables. By running another stepwise selection, insignificant variables can be further pruned in the model. The global multivariate linear regression model provides a moderate fit to the income estimation problem. The global multivariate linear regression model does not find appropriate variable transformations and interactions between variables, which can be a time-consuming, yet important step for building traditional multivariate linear regression models. There are other instances where the global multivariate linear regression model is preferable due to its simplicity and common appeal. [0050] A regression tree based model can be built on the data, e.g., using CART. Some other popular decision tree methods include, but are not limited to, chi-squared automatic interaction detector (“CHAID”), C5.0, as well as quick, unbiased, efficient statistical trees (“QUEST”). However, not all of these methods can handle regression class problems directly. As a result, usage of other algorithms can require some variation and adaptability on the practitioner's part. Regression tree is an interaction-based based non-parametric estimation method suitable to handle a continuous prediction problem. To prevent over-fitting of the model, the smallest optimal tree, which is the smallest tree within one standard error of the minimum cost tree, is preferable. In this exemplary embodiment, a regression tree has about 28 terminal nodes. A better accuracy performance can result from choosing a larger tree, but can also lead to an over-fitting problem. Without incorporating any main effects, regression tree has a non-desirable feature that it can only predict 28 discrete values for income for each of the terminal nodes. [0051] Treenet/Multiple Additive Regression Trees (“MART”), which is a gradient tree-boosting technique, can also predict applicants' income. In this embodiment, a sequence of MART models can be built by varying collections of number of trees from 100 to 500, with each having 6-8 terminal nodes. A fraction of the cases, e.g., 20%, can be set aside for validation testing. A Huber-M loss function can be adopted as the regression loss criterion, since it sums either squared deviation or absolute deviation for each observation depending on the relative magnitude of the deviation, and can perform in the presence of outliers. Although Treenet has a much better performance as compared with the other methods, it has a huge tree structure, which although explicitly defined, may not be as easily comprehensible. [0052] In comparison to the other methods identified herein, the global multivariate linear regression model has moderate prediction power without adding any transformations and interactions into the model. Compared with global multivariate linear regression model, the regression tree can automatically find interactions but cannot provide continuously predicted values for the dependent variable. The regression tree also lacks the inclusion of main effects and is interaction heavy, which can result in complex rule sets. Treenet/MART, although preferable to each method in performance, is extremely complex due to the large amounts of small trees. MARS allows both main and interaction effects to be automatically incorporated into the model, being a piecewise-linear adaptive regression procedure that can effectively approximate complex non-linear structures, if present. Additionally, due to the nature of MARS models, which fits into a variety of software capable of running or scoring multivariate regressions, the MARS models are easily portable across software platforms and computer systems. In this exemplary embodiment, MARS produced favorable results as compared to MART and negligible performance degradation when compared across the performance metrics defined in Step 10, below. In view of these comparisons, MARS is preferable as a modeling paradigm for this income estimation process. [0053] In step 8 , a MARS model is built. The multivariate adaptive regression splines (“MARS”) model building technique is developed to extract the best information from pre-selected prediction variables and to estimate the applicant's income in the final model. MARS is a piecewise-linear adaptive regression procedure. MARS is essentially a recursive-partitioning procedure, i.e., the partitioning process can be applied over and over again. [0054] The partitioning is done at points of the various explanatory variables defined as “knots” and overall optimization is achieved by performing knot optimization. Moreover, to achieve continuity across partitions, MARS employs a 2-sided power basis function of the form: b q ± ( x−t )=[±( x−t )] + q When using linear piecewise basis functions, q=1. The variable “t” is the knot around which the basis is formed. [0055] It is preferable to use an optimal number of basis functions to guard against possible overfit. By starting from a small number of maximal basis functions and building it up to a medium size number, the cost-complexity notion can be used to prune back and find a balance in terms of optimality, which can provide an adequate fit. In this exemplary embodiment, about 25-30 basis functions coupled with cost-complexity pruning is sufficient. [0056] Another important criteria which affects the pruning is the estimated degrees of freedom allowed. This can be done by using 10-fold cross validation from the data set for each model. [0057] There is no explicit way by which MARS can handle multi-collinearity. However, since Treenet can be leveraged as the main methodology to make the preliminary selection of input variables for MARS, multi-collinearity problem can be indirectly addressed from the variable selection process, based on the fact that Treenet can help to pick out the most predictive variable amongst several highly correlated variables. [0058] MARS also provides a penalty on added variables, which is a fractional penalty for increasing the distinct number of raw variables used (not basis functions) in the model. Using this parameter, the system can penalize the choice of multi-correlated variables in a downstream partition if a correlated brethren has been chosen earlier in the model building process. Accordingly, MARS works with the original parent, instead of choosing other alternates. In this exemplary embodiment, a medium penalty is used. [0059] In view of the regression model produced by MARS and the inherent cross-sectional nature of the dependent variable, i.e., income, the target dependent variable in its raw form does not follow a normal distribution, which can violate one of the basic assumptions of multivariate linear regression—that the errors from the regression would be homoscedastic, i.e., equal variance, and random normal. A sequence of random variables is homescedastic if all random variables in the sequence have the same finite variance. Heteroscedasticity is a distinct possible issue in the income estimation process. Heteroscedasticity is when a sequence of random variables have different variances. One consequence of heteroscedasticity is that the estimate variance is overestimates or underestimates the true variance. One efficient way to deal with heteroscedasticity is to find an appropriate transformation for the dependent variable, so that in the back-end the distribution of errors become random and homoscedastic in nature. In this exemplary embodiment, additivity and variance stabilization (“AVAS”), which is a nonparametric response transformation procedure, is implemented in a variety of statistical software, e.g., S-Plus, to find the best transformation of the dependent variable. However, AVAS does not produce the analytical form of the transformation, but provides back the transformed variable itself as an output. Nevertheless, one of ordinary skill in the art can experiment with known analytical forms that match the produced transformed shape and can closely approximate the optimal form to address the heteroscedasticity. [0060] An optimal result from AVAS substantially resembles a few variants of the log transformation. In this exemplary embodiment, a variant of the common logistic transformation is applied to a dependent variable (“DV”), with a cap, using a pseudo value Max DV , which should be at least larger, e.g., 10%, than the maximum observed DV value as experienced in the data set: Trans DV = Log ⁡ ( DV Max DV - DV ) [0061] This can limit the effective prediction range of the model to the choice of Max DV . The simple pure-logarithmic transformation overcomes that, but is not as efficient in solving the heteroscedasticity problem. Even after a transformation of the dependent variable has been applied, if heteroscedasticity still exists, an appropriate smearing factor can be added when retransforming the predicted value back to its original scale to get an unbiased estimation. [0062] In step 9 , a bootstrap re-sampling technique is used to refine the MARS basis functions to build a robust model and prevent any over-fitting. Bootstrapping is a method for estimating sampling distribution of an estimator by resampling with replacement from the original sample. With the explosion in power of computation, the use of resampling methods has become increasingly viable. This has opened up a new paradigm in the area of evaluation of robustness of estimates/statistics. One method is “bootstrapping” for estimating robustness. [0063] To further prevent overfitting issues in MARS, the bootstrap technique is used to further refine the chosen MARS basis functions in order to provide maximal model parsimony. More specifically, from the original development sample, bootstrap samples are drawn at random with replacement such that each observation within the sample has the same probability of being chosen. Each resample is typically of the same size as the original sample. Referring to FIG. 5 , based on bootstrapping results generated from these resamples, the system computes mean/median values and confidence intervals for the significances of each basis function within the context of the particular example. Only generically robust basis functions, which are significant on a consistent basis across all resamples and with smaller span of confidence intervals, i.e., tighter confidence), are kept in the final MARS model to ensure parsimony. [0064] In step 10 , the system evaluates model prediction performance by creating a Confidence Matrix computed using the actual debt ratio and the predicted debt ratio. Although the performance of the income estimator can be evaluated from the perspective of the magnitude of errors committed on the actual income, it can be more meaningful to compare it from the ultimate debt-burden notion. This is primarily for a retail-lending business, since lending criteria is most often based on debt-burden and lenders who make use of risk-based pricing often make use of this information. [0065] To evaluate the income estimation result created in the model development process, the predicted monthly income is translated into the predicted debt ratio by following formula: Predicted Debt Ratio=(Monthly Actual Debt)/(Predicted Monthly Income) [0066] Referring to FIG. 6 , a confidence matrix “M” having a dimensionality of k×k can describe the performance of an income estimator on a given data set. In confidence matrix M, k rows contain the set of actual debt ratio band defined and computed in accordance with existing underwriting guidelines and k columns contain the corresponding predicted debt ratio band. [0067] Agreement between the actual debt ratio band and the predicted debt ratio band occurs when the case falls on the main diagonal of matrix M, represented by cells 60 . A cell above or below the main diagonal contains approximate expanded matches between two debt ratio bands, represented by cells 62 . Cells 64 indicate strong disagreement between the debt ratio bands. [0068] In FIG. 7 , an exemplary annotated confidence matrix M is shown. M 1 represents the total number of absolute agreements between actual debt ratio band and predicted debt ratio band. M 2 represents the total number of expanded agreements between actual debt ratio band and predicted debt ratio band, and can have a ±5% debt-burden error. M 3 represents the total number of cases where actual debt ratio band is much lower than predicted debt ratio band, and can have a chosen threshold of at least 10% over-estimation of debt-burden. M 4 represents the total number of cases where actual debt ratio band is much higher than predicted debt ratio band, which are under estimation errors for cases where actual debt-burden value exceeds the absolute of 50% and error is in excess of 10%. M 5 represents the total number in the data set. [0069] The matrix M depicted in FIG. 6 illustrates the performance measures used in the evaluation of income estimator. There are six measures of performance. Absolute accuracy is the total number of absolute agreements as a percentage of total number of cases: AbsoluteAccuracy = M 1 M 5 Expanded accuracy is the total number of absolute agreements together with expanded agreements as a percentage of total number of cases: ExpandedAccuracy = M 1 + M 2 M 5 False positive error is the total number of cases where actual debt ratio band is much higher than predicted debt ratio band as a percentage of total number of cases: FalsePositiveError = M 4 M 5 False negative error is the total number of cases where actual debt ratio band is much lower than predicted debt ratio band as a percentage of total number of cases: FalseNegativeError = M 3 M 5 Relative error is the summation of false negative error and false positive error: RelativeError = M 3 + M 4 M 5 Relative accuracy is: RelativeAccuracy = 1 - M 3 + M 4 M 5 [0070] FIG. 8 depicts the performance of the MARS model on the training, validation and time validation data sets. As shown in FIG. 8 , the MARS model developed is substantially robust in consistency of performance across samples and performance measures. [0071] The embodiments described above are intended to be exemplary. Numerous alternative components and embodiments that may be substituted for the particular examples described herein and still fall within the scope of the invention.

An automated method and system estimates income of an individual loan applicant using credit bureau information and loan attributes. The method and system can use the credit bureau and loan information to calibrate an applicant's debt-burden in cases where such information is not readily available or is unverifiable. The method and system can automatically verify income for applicants who choose to state their income in lieu of providing adequate documentation. Further, the method and system can be applicable to any retail lending business including, but not limited to, mortgage, auto loan, and credit cards, where credit bureau information forms a part of the data collection process and is available along with applicant's information.

FIELD OF THE INVENTION The present invention relates to a method for accessing sets of data contained in mass memory, and to a device allowing the method-to be implemented. The device may be used particularly in magnetic tape players/recorders. BACKGROUND Mass memories are widely used to store relatively large quantities of data. A mass memory requires an information medium which may be formed, for example, by an optically or magnetically readable disk, a magnetic tape or even an electronic circuit on semiconductors. Depending on the mode of reading of the mass memory, and depending on the mode of arranging the data in the mass memory, access for reading the data may require more or less access time. The access time is caused, in large part, by the time which a read device takes to get into position to read the data to be read. The access times may reduce the efficacy of a mass memory when numerous data items arranged in this memory are to be accessed in a non-ordered way. This is the case, for example, of mass memory on a magnetic tape medium. The mass memory may contain data grouped together into sets of data, each set of data representing a song, for example. In order to gain access from one song to another song on the same magnetic tape, the songs being separated by a defined length of this magnetic tape, it is first of all necessary to make the entire defined length of magnetic tape move past the read device. The problem to which the present invention proposes to afford a solution is that of eliminating certain drawbacks due to the access times during access to data in mass memory. SUMMARY OF THE INVENTION One solution to the problem posed, and according to the present invention, is found in a method for accessing a determined set of data among sets of data contained in a mass memory on an information carrier which comprises the steps of: obtaining a command for access to the determined set of data, after obtaining the command for access, reading introduction data from an introduction memory distinct from the mass memory but on the information carrier, processing the introduction data read from the introduction memory, realizing an access operation to the determined set of data at the same time as the step of processing the introduction data. The processing of the introduction data may, for example, be the reproduction into music and/or into images when the introduction data are audio or video data. According to one preferred embodiment of the access method according to the invention, processing is carried out on introduction data which are specific to the set of data which is the subject of the access operation. The introduction data may, for example, constitute a subset of the set of data to be accessed. The solution to the problem posed may according to the invention also be seen in a device for accessing sets of data contained in mass memory on an information carrier, access to a determined set of data for reading taking place during an access time. The device comprises an introduction memory containing introduction data, the introduction memory being separate from the mass memory but on the same information carrier. The device further comprises reading means for reading from the introduction memory, command means for obtaining a command for access to the determined set of data and being at least connected to the introduction memory, and processing means for processing the read introduction data, the processing means acting particularly during the time for accessing the determined set of data. According to one preferred embodiment of the device according to the invention, the device comprises a temporary memory separate from the mass memory, transferring means for transferring at least a part of a set of data from the mass memory into the temporary memory while this set of data is read, further reading means for reading from the temporary memory and reproduction means for reproducing a set of data at a moment later than the reading of this set, these reproduction means being at least linked to the further reading means for reading from the temporary memory. When the reading of a set of data is coming to an end, it is possible to continue to reproduce the data in deferred mode while, for example, further access is gained to another set of data. Further characteristics and advantages of the present invention will emerge on reading the description given below of examples in accordance with the present invention, this description being given with reference to the attached drawings in which: BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 contains a flow chart of an access method according to the invention; FIG. 2 diagrammatically shows an access device according to the invention. DETAILED DESCRIPTION In FIG. 1, access to a set of data is triggered by an access command 1 . On completion of the access command 1 , introduction data from an introduction memory 2 are read during a read stage 3 . The introduction data read are then subjected to processing 4 , which consists, for example, in forwarding these data to a reproduction stage 5 . The access command 1 also triggers an operation 6 of accessing a set of data contained in mass memory 7 . The reading 3 and processing 4 take place at the same time as the access operation 6 . The access operation 6 signals the processing stage 4 after an access time. According to one embodiment of the processing stage 4 , the forwarding of the introduction data is interrupted, and it is the data of the set of data accessed which are forwarded to the reproduction stage 5 . According to another embodiment, the processing stage 4 forwards the whole of the introduction data read before forwarding the set of data. This is advantageous, for example, when the introduction data are an advertising item. The introduction memory 2 may contain introduction data which are specific to the sets of data. In this case, the read stage 3 recognises, in the access command 1 , which set has to be accessed, and it is introduction data specific to this set which are read from the introduction memory 2 . The specific introduction data may, for example, constitute a subset of the corresponding set of data, and even more precisely, the start of a song when the set is a song. As the time for accessing each song of the mass memory is variable, the processing stage 4 may be implemented in such a way as to forward to the reproduction 5 only a part of the song accessed during the access operation 6 which has not yet been forwarded during the forwarding of the introduction data at the moment when the access operation 6 terminates and when it signals the processing stage 4 . Thus the reproduction 5 of a set of data is uninterrupted and starts at the moment when the access command 1 is given. The specific introduction data may also consist of several subsets of sets of data, these subsets being related by a characteristic which is common with the set of data to be accessed. When the sets of data are songs, this common characteristic may, for example, be a type of song or a date when the song was published. Hence, during the time for accessing a song of type A, the processing stage 4 forwards to the reproduction 5 introduction data comprising extracts from songs of the same type A. FIG. 2 shows a sequential information medium 8 which may, for example, be a magnetic tape. On the information medium 8 , an introduction memory I stores introduction data 9 , and a mass memory M stores sets of data arranged sequentially, including a set 10 . The introduction data 9 and the set 10 can be read by the read device 11 when the latter is positioned in front of the medium at the appropriate position. A user 12 controls a control device 13 for accessing the set 10 . Following user's command, the read device 11 will read the introduction data 9 and the control device 13 stores the introduction data read in a random-access memory 14 . The introduction data are then processed from the random-access memory 14 by a data reproduction unit 15 at the same time as the read device 11 accesses the set 10 for reading. The access time required by the read device 11 to pass from reading the introduction data 9 to reading the set 10 varies particularly as a function of the distance D separating the data 9 and the set 10 on the medium 8 . The reproduction unit 15 and the random-access memory 14 are processing means for processing the introduction data. In the case in which the medium 8 is a magnetic tape for use in a music player, the reproduction unit 15 may be an audio data amplifier. The reproduction unit 15 may also be used to reproduce the data of the set 10 once they have been read. The control device 13 then transfers the data of the set 10 directly to the reproduction unit 15 . The introduction memory I may contain introduction data which are specific to the sets of data contained in the mass memory M. In this case, for example, only the introduction data specific to the set of data to be accessed are copied into the random-access memory 14 then reproduced. In one variant of the access device, all the specific introduction data are copied into the random-access memory 14 , and only the data specific to a set to be accessed are reproduced during the access. Hence the introduction memory does not need to be read every time a set of data has to be accessed. The specific introduction data may be subsets of the sets of data. Depending on the nature of the sets of data, the subsets may, for example, represent a musical extract, a film trailer, a software module, etc. In one variant of operation of the device shown in FIG. 2, the data read from the set 10 are still transferred into the random-access memory 14 then reproduced from the random-access memory. When the reading of the set 10 takes place more rapidly than the reproduction of the data from the random-access memory, the reproduction is delayed by comparison with the reading. When the set 10 has been read in its entirety, and when the next command from the control device 13 has to be carried out, the reproduction of the set 10 carries on while the command is being executed. While the invention has been described in detail with respect to numerous embodiments thereof, it will be apparent that upon a reading and understanding of the foregoing, numerous alterations to the described embodiment will occur to those skilled in the art and it is intended to include such alterations within the scope of the appended claims.

The invention relates to a method of access to data sets stored in a bulk memory. During an access time to a data set, the method provides for reading introduction data and exploiting these. This way the method overcomes the problem of long access times in a bulk memory. The method may notably be used when data sets are arranged sequentially on a sequential data carrier, which is for example the case for songs recorded on a magnetic tape. A device for implementing the method is also defined.

CONTINUING APPLICATION DATA The present application is filed as a Divisional Application of U.S. Ser. No. 10/341,538, filed on Jan. 13, 2003, and issued into U.S. Pat. No. 7,488,467, which was a Continuation of U.S. Ser. No. 10/062,225, filed on Jan. 30, 2002, now Abandoned, which was a Continuation of U.S. Ser. No. 09/974,550, filed on Oct. 10, 2001, now Abandoned, which claims priority under 35 U.S.C. §119 based upon U.S. Provisional Application No. 60/238,928 filed Oct. 10, 2000 and in-part based upon U.S. Provisional Application No. 60/264,977 filed Jan. 30, 2001. FIELD OF THE INVENTION The present invention generally relates to the fields of biochemistry and pharmacology and to the use of a genetic model organism labeled with fluorescent lipids to screen for drugs and genetic alterations related to phospholipid and/or cholesterol metabolism and, more particularly, to the use of optically clear zebrafish in conjunction with tagged or quenched lipids for studying lipid metabolism in vivo. BACKGROUND OF THE INVENTION Genetic analysis in zebrafish is a powerful approach for identifying genes that direct vertebrate development (1-3). Since the completion of the large-scale chemical mutagenesis screens in 1997, the phenotypic and molecular characterizations of many mutations have been reported (4-16). Analyses of mutations that affect early developmental processes, such as the specification of the embryonic axes and germ layers, have been particularly rewarding (7, 10, 17-27). Recently, related work with mutations that affect organogenesis has led to the recognition that the zebrafish is an important model system for biomedical research (28-31). Given the many aspects of organ physiology that have been conserved during vertebrate evolution, genetic screening to assay organ function in the optically transparent zebrafish is a valuable approach to understanding a variety of metabolic processes and disorders in vertebrates. By zebrafish chemical mutagenesis screening, nine recessive lethal mutations that perturb development of the digestive organs were identified (2, 31). Although the mutants were identified using morphological criteria, their phenotypic analysis suggests that in some cases the affected genes regulate developmental processes that are relevant to digestive physiology and other aspects of vertebrate metabolism. Through the analysis of these and other zebrafish mutants, the limitations inherent to genetic screens that are based solely on morphological criteria became apparent. First, not all organs are readily distinguished in zebrafish larvae, and mutations that perturb organ morphology are often overlooked. Second, since it is difficult to visualize specific cell populations within many larval organs, mutations that affect the development or function of these cells can be overlooked as well. Third, despite the transparency of the zebrafish larva, the function of few organs can be effectively assayed by visual inspection alone. For these reasons, it was concluded that, in most instances, morphology-based screens are best suited for the identification of genes that regulate specification and patterning of embryonic structures. By contrast, screens designed to address biomedical concerns are most effective when they assay physiological processes directly. Within the past few years, the discovery and analysis of zebrafish mutants affecting organogenesis has confirmed an important role for the zebrafish in biomedical research. The ability to apply high throughput genetic analyses to vertebrate organ physiology using this model system is unprecedented and will undoubtedly, over time, lead to the discovery of many genes that regulate vertebrate organ development and physiology. Such zebrafish research will complement research in other vertebrate model systems. By conducting a mutagenesis screen using fluorescent lipids, an undertaking not feasible with standard zebrafish screening strategies, the power of high throughput genetic analysis can be applied to lipid metabolism. This has important implications for human diseases such as, but not limited to, cancer, inflammatory and cardiovascular diseases, and congenital and acquired diseases of the intestine and liver. The fluorescent phospholipase A 2 (PLA 2 ) substrates described in the present invention are the first prototypes in this class of reagents. Although lipid metabolism in the digestive tract is complex and involves multiple organs the present invention discloses a method of assaying this pathway since gall bladder fluorescence represents one of the last steps in lipid processing. Because they serve as reporters of lipid processing, the fluorescently-tagged reagents of the instant invention provide a sensitive assay for a wide range of digestive developmental and physiological processes including, but not limited to, swallowing; lipid digestion, absorption, and transport; esophageal sphincter function; intestinal motility; organogenesis of the mouth and pharynx, esophagus, intestine, liver, gallbladder and biliary system, and exocrine pancreas and ducts; and the cellular and molecular biology of PLA 2 regulation, polarized transport, and secretion. Given the shared features of lipid processing in mammals and teleosts (82, 105), zebrafish mutagenesis screens using lipid reporters can be used to identify genes with functions relevant to human lipid metabolism and disease. Moreover, since both mammals and teleosts metabolize lipids in an analogous manner, the high throughput screens and fluorescent lipids disclosed in the instant invention can be employed using a variety of vertebrate model systems, including but not limited to, rodents, amphibia, and fish. The present invention involves utilizing fluorescent lipids to screen for phenotypes representing perturbations of lipid processing; to screen for mutations of specific genes that lead to disorders of phospholipid and/or cholesterol metabolism; and to screen for compounds designed to treat disorders of phospholipid and/or cholesterol metabolism, such as, but not limited to cancer, inflammatory and cardiovascular disease, and congenital and acquired diseases of the intestine and liver. ABBREVIATIONS “PLA 2 ” means “phospholipase A 2 ” “PLA 1 ” means “phospholipase A 1 ” “PLB” means “phospholipase B” “PLD” means “phospholipase D” “PED6” means “N-((6-(2,4-dinitrophenyl)amino)hexanoyl)-1-palmitoyl-2-BODIPY-FL-pentanoyl-sn-glycero-3-phosphoethanolamine” “hpf” means “hour post-fertilization” “dpf” means “day post-fertilization” “FRET” means “fluorescence resonance energy transfer” “PC” means “phosphatidylcholine” “TLC” means “thin layer chromatography” “cPLA 2 ” means “cytoplasmic PLA 2 ” “sPLA 2 ” means “secretory PLA 2 ” “COX” means “cyclooxygenase” “APC” means “adenomatous polyposis coli” “EP” means “early pressure” “ENU” means “ethylnitrosourea” “WT” means “wild-type” “SLR” means “single locus rate” “IVF” means “in vitro fertilization” “BAC” means “bacterial artificial chromosome” “PAC” means “P1-derived artificial chromosome” “YAC” means “bacterial artificial chromosome” “SSR” means “simple sequence report” “CSGE” means “conformation sensitive gel electrophoresis” “VLDL” means “very low density lipoprotein” “EM” means “embryo medium” “NBD cholesterol” means “nitrobenzoxadiazole cholesterol” BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 . Schematic of PED6, a quenched PLA 2 substrate. A. The dinitrophenol on the phospholipid headgroup effectively quenches any emission resulting from excitation at 505 nm of the BODIPY-labeled acyl chain. B. When the BODIPY-labeled acyl chain is liberated by PLA 2 mediated cleavage, the quencher is separated from the fluorophore and emission (515 nm) is observed. C. NDB-labeled cholesterol in which the fluorophore replaces the terminal segment of cholesterol's alkyl tail. FIG. 2 . Intestinal differentiation in 84 hpf larvae. A. Cross-section of posterior intestine. Desmin immunoreactivity of intestinal smooth muscle (green) and enteric neurons as indicated by zn6 immunoreactivity (red) demonstrate development of the enteric neuromuscular system. B. Transmission Electromicrograph showing mature apical junctional complexes in enterocytes in the intestinal epithelium. Arrow points to desmosomes; A: Adherens junction. T: tight junction. C. Histochemical detection of enterocyte aminopeptidase activity (red); anterior intestinal cross section. D. Histological detection of goblet cell mucin (purple) in the posterior intestine. Also present at this developmental stage, immunoreactive pancreatic polypeptide in enteroendocrine cells. FIG. 3 . PED6: a fluorescent lipid reporter. A. Bright-field image of a 5 dpf larva soaked in PED6 (3 μg/ml, 2 hr). B. Corresponding fluorescent image, with intestinal (arrow) and gall bladder (arrowhead) labeling. C. Larva soaked in BODIPY-C5-PC (0.2 μg/ml). In contrast to B, unquenched fluorescent lipid labels the pharynx (arrowhead), confirming that lipid is swallowed before gall bladder labeling (arrow). FIG. 4 . Rate of fluorescence after PED6 labeling. Larvae (n=5) were placed in medium containing PED6 (0.17 mg/ml) and tricaine. Images were captured at various times and fluorescence intensity was determined in specific structures. Organ fluorescence intensity determined at specific times was normalized to the observed intensity at 45 min. Data are expressed as Mean.+−.SEM. FIG. 5 . Lipid processing. A. and B. Atorvastatin (ATR) inhibits processing of PED6 (A) but not of BODIPY-FL-C5 (Molecular Probes). B. Larvae were bathed in fluorophore (0.6 μM) in the presence or absence of atorvastatin (Lipitor tablet suspension containing 1 mg/ml) (arrowhead, gall bladder). C. Mouse digestive organs. D. Gall bladder fluorescence after processing (t=30 min) of PED6 (1 μg), administered by gavage. Symbols: gb, ball bladder; d, common bile duct; lv, liver. Scale bars, 1.0 mm (C and D), 200 μm (other images). FIG. 6 . BODIPY FR-PC reveals both the substrate and PLA 2 cleavage product. Upon integration into cells, excitation at 505 nm results in an emission at 568 nm (orange) due to fluorescence resonance energy transfer (FRET). After cleavage by PLA 2 emission is observed only at 515 nm (green). FIG. 7 . Fluorescence emission spectrum of mixed micelles of 0.05 mol % BODIPY FR-PC in mixed-lipid vesicles. The fluorescence emission spectrum of BODIPY FR-PC (0.5 μM in ethanol; excitation, 505 nm) showed peaks at 514 nm and 568 nm with a ratio of 1.0 indicating FRET. An excitation scan (emission, 568 nm) showed peaks at 507 and 560 nm with a ratio (507/560) of 1.2. Solid line: before addition of PLA 2 . Dashed line: after addition of N naja PLA 2 . Vesicles were prepared by sonication of the dried lipids (from chloroform-methanol solution); 1.1 μM BODIPY FR-PC (0.05 mol %), 0.1 mM dimyristoylphosphatidycholine (46 mol %), 0.12 mM ditetradecylphospha-tidylmethanol (54 mol %), buffer (50 mM Tris, pH 8, 100 mM NaCl, 1 mM CaCl 2 ); excitation, 505 nm. FIG. 8 . BODIPY FR-PC is effective in paramecium. Paramecium incubated (1 hr) in BODIPY FR-PC (2.5 μg/ml) results in labeling of lipid droplets (orange). Digestion of the lipid results in green fluorescence. Excitation 505 nm, emission LP520. FIG. 9 . BODIPY FR-PC localizes to the intestinal epithelium. Fish were incubated (1-4 hr) in BODIPY FR-PC (2.5 μg/ml). BODIPY FR-PC metabolites are observed in gall bladder (green). Excitation 505 nm, mission LP520. A. Brightfield image. B. and C. Visualization of antigen presenting enterocytes in segment II of the larval zebrafish intestine after only 1 hr of labeling. Arrows mark segment II domain. D. 4 hr labeling with BODIPY FR-PC results in FRET effect throughout intestine. FIG. 10 . Lipid processing in intestinal mutants. A and C. Bright field images of 5 dpf mlt and pie larvae. B and D. Fluorescent images corresponding to A and C. Normal lipid processing of PED6 (0.3 μg/ml, 2 hr) in mlt larva (arrowhead marks gallbladder). D and E. Abnormal lipid processing in PED6 labeled pie and slj larvae; fluorescence is present in the intestinal lumen (white arrowhead) and reduced in the gallbladder (red arrowhead). FIG. 11 . Phospholipid processing and transport. A. Following uptake, PED6 is cleaved by PLA 2 liberating a labeled fatty acid. The fate and transport of this fatty acid remains unknown. B. TLC of fluorescent lipid standards. PED6 (black because it is quenched), D3803 (C5-BODIPY PC), and C5-fatty acid are easily resolved using a two solvent system silica gel plates (Whatman, LK5D). Solvent 1 (toluene, ether, ethanol, acetic acid; 25/15/2/0.2); Solvent 2 (chloroform, methanol, acetic acid, water; 25/15/4/2). FIG. 12 . Red BODIPY-PC given by gavage labels the gall bladder. Adult fish was anesthetized in tricaine, injected with 80 μg of D3806 (a BODIPY PC 582/593 nm), allowed to recover for 1 hr and dissected on ice. FIG. 13 . Larval zebrafish (5 dpf) labeled with NDB cholesterol—derivative labels gall bladder within 30 minutes of ingestion (3 μg/ml, solubilized with fish bile). DETAILED DESCRIPTION The present invention relates to a mutagenesis screen to identify genes that regulate lipid metabolism using fluorescently-tagged or quenched lipids such as cholesterol or lipids that are substrates for phospholipases such as PLA 2 . For example, cleavage of quenched phospholipid substrates by PLA 2 results in an increase in fluorescence intensity or alters the spectral properties of fluorescent emission thus allowing lipid metabolism to be followed in vivo. In one embodiment of the instant invention, optically transparent zebrafish larvae exposed to the fluorescently-tagged or quenched lipids display intense gallbladder fluorescence, which reflects lipid cleavage by intestinal PLA 2 and subsequent transport of the fluorescent cleavage products through the hepatobiliary system. The instant invention presents evidence demonstrating that in the context of a mutagenesis screen, fluorescent PLA 2 substrates and fluorescently-tagged cholesterol or other lipids have the potential to identify genes that affect many aspects of lipid metabolism. Consequently, when used in the context of a genetic screen these reagents provide a high throughput readout of digestive physiology that cannot be assessed using standard screening strategies. Given current understanding of the pathway of lipid processing in zebrafish, specifically its shared features with lipid processing in mammals, the present invention has relevance for biomedical research related to, among other things, cancer, inflammatory and cardiovascular diseases, and congenital and acquired diseases of the intestine and liver. Fluorescent Reagents to Assess Organ Physiology In Vivo The fluorescent lipids of the instant invention allow assaying of physiological processes. The reagents are fluorescent analogues of compounds that could serve as modifiable substrates in important metabolic and signaling pathways. The reagents of the instant invention were constructed by covalently linking fluorescent moieties to sites adjoining the cleavage site of phospholipids. Dye-dye or dye-quencher interactions modify fluorescence without impeding enzyme-substrate interaction (106). PLA 2 cleavage results in immediate unquenching and detectable fluorescence. Quenched phospholipids [N-((6-(2,4-dinitrophenyl)amino)hexanoyl)-1-palmitoyl-2-BODIPY-FL-pentano-yl-sn-glycero-3-phosphoethanolamine (PED6)] allow subcellular visualization of PLA 2 activity and reveal organ-specific activity (36). The evidence presented in the instant invention demonstrates that zebrafish larvae 5 days post-fertilization (dpf) bathed in PED6 show intense gall bladder fluorescence and, shortly thereafter, intestinal luminal fluorescence. Substrate modification allows localization of enzymatic activity by altering the emission spectrum of the fluorescent compounds. When used in the context of a genetic screen these fluorescent lipids provide a high throughput readout of organ function. The reagents of the instant invention facilitated the development of genetic screens that are more sensitive than the whole-mount in situ and antibody based screening protocols now used to assay gene expression. The fluorescent reagents are simpler to use since they can be administered to and assayed in a wide range of organisms, including, but not limited to rodents and teleosts, and they offer the opportunity to screen for hypomorphic mutations that alter gene function but do not affect levels of gene expression. By providing a visual assay of metabolic processes, these reagents can be used to identify mutations that affect more than just the single gene responsible for substrate modification. Visualization of the fluorescent signal also is dependent upon the delivery and uptake of the substrate as well as the storage, metabolism or secretion of its modified metabolites. Fluorescent PLA 2 Substrates PLA 2 s were chosen as the “target” enzymes to assay because of the important role these enzymes play in the generation of lipid signaling molecules (32-34). PLA 2 s are a large family of enzymes that can be categorized according to their cellular distribution, molecular weight, and calcium dependence (33). Some PLA 2 s also exhibit a preference for phospholipids with arachadonyl sn2 acyl side chains (34, 37, 38). Given the wide range of processes the PLA 2 family of enzymes is known or thought to regulate, the advantage of the fluorescent lipids as screening reagents is significant. cPLA 2 . For example, one PLA 2 gene family member, cytoplasmic PLA 2 (cPLA 2 ), regulates eicosanoid production. Eicosanoids are ubiquitous signaling molecules generated by the biochemical modification of arachidonic acid, the principal fatty acid liberated from membrane phospholipids by cPLA 2 s (42-44). cPLA 2 s have a strong preference for arachidonyl phospholipids and cPLA 2 cleavage of these phospholipids is known to be the rate-limiting step in eicosanoid synthesis (39, 41, 44-47). In comparison, secretory PLA 2 s (sPLA 2 s) exhibit little substrate preference and unlike cPLA 2 , the arachidonic acid generated through s PLA 2 activity is not directly coupled to eicosanoid production (37, 46). The two major classes of eicosanoids produced by vertebrate cells are leukotrienes and prostaglandins (48, 54). Prostaglandins are a large family of signaling molecules that are synthesized through the action of cyclooxygenases (COX) and prostaglandin-isomerases on PLA 2 generated arachidonic acid (48). Prostaglandins are especially important in vertebrate physiology as they regulate a myriad of physiological processes, including hemostasis, cell proliferation, fertility, and inflammation (48-50). The importance of prostaglandin in humans is underscored by the widespread use of COX inhibitors (e.g., aspirin) as medicinal agents. Given the focus of this invention, there is special interest in intestinal prostaglandins. Intestinal prostaglandins play an important role in regulating mucosal blood flow (51-54), and inhibition of prostaglandin synthesis by COX inhibitors, such as aspirin, is associated with the development of mucosal ulcerations (55). There is also strong evidence that intestinal prostaglandins regulate epithelial cell proliferation (56-58). COX inhibitors are known to have a chemopreventitive effect on several human digestive cancers, and COX-2 has been identified as a genetic modifier of APC, an important colon cancer gene. Because arachidonic acid release is the rate-limiting step in eicosanoid production, characterization of the cell specific regulation of cPLA 2 s is important (33, 34). Although the genes in some of the signaling pathways that activate cPLA 2 have been identified, this characterization is far from complete. A screen utilizing fluorescent lipid substrates will allow identification of mutations that perturb lipid processing and alter cPLA 2 activity. sPLA 2 . Another PLA 2 gene family member, s PLA 2 , plays a role in inflammation, host defenses, digestion, and cell proliferation (43, 70, 71). In comparison to cPLA 2 s, s PLA 2 s show little preference for arachidonic acid over other phospholipids sn2 acyl side chains (34). There is a large body of experimental and clinical evidence supporting the role of sPLA 2 s in inflammation. First, serum levels of sPLA 2 are increased in inflammatory conditions such as Rheumatoid Arthritis, Crohn's Disease, endotoxic shock, and atherosclerosis (32, 72-76). Second, sPLA 2 cleavage of arachidonyl phospholipids has been shown to augment cPLA 2 mediated eicosanoid production (46, 71, 77). Third, independent of its enzymatic activity, sPLA 2 has been shown to bind to a specific cellular receptor that plays a role in endotoxic shock (78) and other aspects of the inflammatory response (43, 79, 80). Like cPLA 2 , the regulation of inflammatory sPLA 2 s (Groups II and V) is an important area of biomedical research. Group IIA sPLA 2 recently has been shown to play a role in colon cancer tumorigenesis through its genetic interaction with APC in the min mouse, a colon cancer animal model (66-68). High levels of this gene are expressed in intestinal Paneth cells where it is also believed to function as an antimicrobial agent because of its ability to digest bacterial cell wall phospholipids (38, 76, 81). The precise mechanism of sPLA 2 's mitogenic effect is unclear. Since COX activity also has been shown to modify colon tumorigenesis in the min mouse, sPLA 2 may be acting via prostaglandins (69). This hypothesis is counter-intuitive, however, because in the min mouse, loss of sPLA 2 function is associated with a tumor promoting effect. An alternate hypothesis suggests that in the colon, sPLA 2 also may function as a cell-signaling molecule, independent of its enzymatic activity, through its interaction with the sPLA 2 receptor. The role of sPLA 2 s in the digestion and absorption of dietary phospholipids has been studied in many vertebrate species, including teleosts (82). Pancreatic sPLA 2 is the prototypical low molecular weight sPLA 2 -its proenzyme is secreted into the intestinal lumen where it is activated and cleaves dietary phospholipids that have been modified by bile salts (83). sPLA 2 activity also is present in the intestinal brush border and undoubtedly contributes to the digestion of dietary phospholipids (84, 85). Intestinal PLA 2 activity is present in the form of PLB, an enzyme that can function as a high molecular weight, calcium independent PLA 2 as well as a lysophospholipase (86-89). Regulation of lipid absorption and transport is an important area of biomedical research that has implications for metabolic, inflammatory, and cardiovascular diseases. Phospholipid Metabolism In fish, like mammals, dietary phospholipid is cleaved by intestinal and pancreatic PLA 2 s to form free fatty acid, lysolipid, and phosphoglycerol (82). These molecules are absorbed by enterocytes, presumably by simple diffusion (lysolipid, phosphoglycerol) and receptor mediated processes (fatty acid) (90). Within the enterocyte, the free fatty acids are processed according to their size: long carbon chain fatty acids are re-esterified to form triglycerides and phospholipids, packaged into lipoprotein particles (chylomicrons or VLDL) and enter the general circulation via the lymphatics; shorter chain fatty acids presumably can enter the circulation directly via the portal vein (90-92). Lipoprotein bound phospholipids enter cells in the periphery by binding to specific receptors or via endocytosis (90, 91). In comparison to the fatty acids, the fate of the phospholipid derived lysolipid and phosphoglycerol cleavage products are less certain. In mammals, they are largely re-esterified to form phospholipids, which then are incorporated into lipoproteins and absorbed via the lymphatics, like triglycerides (90-92). Vertebrate lipid absorption is further complicated by the existence of other intestinal phospholipases (PLD, PLA 1 ) that cleave the polar head group or sn1 fatty acid from lysolipids and phospholipids. This raises the possibility that phospholipids undergo extensive re-arrangement within the intestinal epithelium prior to absorption. In fish, there is experimental evidence supporting this observation (82). Materials, Methods, and Results Zebrafish: Zebrafish, Danio rerio, were housed in a separate facility consisting of approximately 500 tanks of varying sizes (1 liter, 3.75 liter, and 9 liter). Environmental conditions were carefully monitored for disease prevention and to maintain fish in perpetual breeding condition. Male and female fish were reared at a density of no more than 8 fish per liter at a constant temperature and light cycle (27-29° C. with the light/dark cycle kept at 14/10 hours) in pre-treated water (heated, charcoal-filtered and UV-sterilized). Fish were fed twice daily with a variety of dried and live foods. Zebrafish provide a relatively simple model system for more complex vertebrates, such as humans. They are small in size, easy to maintain and breed, and produce large numbers of progeny on a daily basis. Their embryos develop rapidly and are optically clear, permitting direct observation of the developing digestive system. Being vertebrates, zebrafish contain orthologues for almost all human genes. The species also is amenable to genetic methods so that one can screen for mutations that disrupt organ function or development. It is possible, therefore, to identify genes important for intestinal development and function by examining fish that carry random mutations. In addition, many techniques have been worked out for manipulating zebrafish, including in vitro fertilization, production of haploids and parthenogenic diploid embryos, mutagenesis, cell lineage and cell transplantation. Generation of Fluorescent PLA Substrates to Assay Lipid Processing: In the instant invention, a family of fluorescent phospholipids was generated with such phospholipids serving as substrates for PLA 2 . As previously noted, characterization of the genetic regulation of PLA 2 is an active area of biomedical research (67, 68), and the reagents described were developed to function as in vivo biosensors of PLA 2 activity that can be assayed using microscopy or simple biochemical techniques. When administered to zebrafish embryos and larvae, these reagents provide a rapid readout of a wide range of developmental and physiological processes that are amenable to high throughput genetic analyses. The fluorescent lipids described in this proposal are quenched fluorescent phosphatidylcholine analogues and NBD-labeled cholesterol ( FIG. 1 ). The phospholipid reagents differ in both their fluorescent emission and their specificity for different PLA 2 isoforms (93, 94). Cleavage of these phospholipids by PLA 2 generates a fluorescent fatty acid or lysolipid that can be used to localize and quantify PLA 2 activity in live fish (36, 94). It has been demonstrated that there is utility of these agents for revealing localized PLA 2 activity in developing zebrafish embryos (94). To determine whether these reagents could be used to study organ specific PLA 2 activity, the quenched fluorescent lipids were administered to zebrafish larvae at 5 dpf, a developmental stage when the major larval organ systems function ( FIG. 2 ). 5 dpf larvae soaked in PED6 uniformly developed intense gallbladder fluorescence 15-20 minutes after ingesting the lipid ( FIG. 3 ). Based upon established mechanisms of vertebrate lipid processing, it was theorized that the larval gallbladder fluorescence reflected ingestion of the lipid reagents followed by intestinal PLA 2 cleavage, intestinal absorption, transport to the liver and biliary excretion of the fluorescent cleavage product. This hypothesis was tested with three experiments. First, to establish that PED6 is swallowed by the larvae, an unquenched fluorescent lipid was administered to 5 dpf larvae, and the appearance of labeled lipid in the pharynx and intestinal lumen before the gallbladder was noted ( FIGS. 3C & 4 ). Second, that gallbladder fluorescence reflects hepatobiliary transport of the fluorescent cleavage products was shown by demonstrating the absence of PLA 2 activity in dissected adult gallbladders with and without bile (4785.+−.626 when full of bile vs. 7421.+−.2043 when empty, arbitrary fluorescence units ±.SEM, n=3). Dissected adult gall bladders were lysed in embryo medium (EM) (30 μl) containing BODIPY-FL-C 5 -PC (0.1 μg) to release bile. PLA 2 activity was determined as described (1). Measurements were compared with activity of bile-depleted gallbladders. Third, this finding was confirmed by demonstrating the early appearance of fluorescent cleavage products in the liver of larvae exposed to PED6 compared with the gallbladder ( FIG. 4 ). Larvae were labeled with PED6 (0.3 μg/ml) in EM, anesthetized (tricaine, 170 μg/ml), and placed in depression slides. Fluorescent images were captured over 1 hr using a Zeiss Axiocam 2 mounted on a Leica MZFL-III. Because PLA 2 activity was not detected in bile and fluorescent PED6 metabolites underwent rapid hepatobiliary transport, labeling the liver before the gall bladder, PED6 must be cleaved within the intestine. Moreover, PED6 labeling of the gall bladder was completely blocked by atorvastatin (Lipitor, Parke-Davis) ( FIG. 5A ), a potent inhibitor of cholesterol synthesis in humans (108). Because the addition of exogenous bile reversed this effect [Bile was obtained from freshly killed tilapia (Orechromis mossambicus) and extracted with three volumes of methanol:chloroform (1:2). The aqueous fraction was recovered, reduced to one volume under nitrogen, and added to EM (20 μl/ml)], and atorvastatin failed to inhibit processing of a water-soluble short-chain fatty acid (BODIPY-FL-C5, Molecular Probes Inc.) (105) ( FIG. 5B ), the data demonstrate that atorvastatin blocks the synthesis of cholesterol-derived biliary emulsifiers needed for dietary lipid absorption (109). These results, coupled with the rapid appearance of biliary fluorescence in mice fed PED6 ( FIG. 5D ), demonstrate that in zebrafish larvae, lipids are processed in a similar, if not identical, manner as other vertebrates and that gallbladder fluorescence reflects intestinal absorption and hepatic excretion of the lipid reagents and its metabolites. BODIPY FR-PC a Reporter of Both Substrate and Cleavage Product To further demonstrate that PED6 and other fluorescent lipids are processed by intestinal lipases prior to transport to the liver and gallbladder (as compared to being absorbed from the intestinal lumen, transported to the liver, and first cleaved by hepatic PLA 2 activity prior to biliary excretion) a new fluorescent lipid was developed ( FIG. 6 ). BODIPY FR-PC ( FIG. 6 ) is a substrate that can be used to determine the site of PLA 2 activity more precisely because it emits distinct fluorescent profiles before and after cleavage. This phospholipid contains two dyes that interact via fluorescence resonance energy transfer (FRET). Substrate and cleavage product possess unique spectral signatures, allowing their tissue distribution to be distinguished by fluorescence microscopy. Excitation (505 nm) of micelle-incorporated BODIPY FR-PC produces an orange emission (568 nm) ( FIG. 7 ) from the sn2 fluorophore via the FRET effect (18). Cleavage of the substrate purified by PLA 2 , however, releases the sn2 acyl chain and abolishes FRET ( FIG. 7 ). Excitation of the resultant lysolipid produces a green emission (515 nm). The fluorescence emission spectrum of BODIPY FR-PC was determined using mixed micelles of 0.05 mol % BODIPY FR-PC in dimyristoyl phosphatidylcholine (46 mol %) and ditetradecylphosphatidylmethanol (54 mol %) prepared in buffer (50 mM Tris, pH 8, 100 mM NaCl, 1 mM CaCl 2 ) by sonication of the dried lipids. Having established that BODIPY FR-PC behaves as anticipated in in vitro assays, its behavior in vivo was analyzed by exposing paramecia to the lipid for 1 hr, followed by excitation at 505 nm. As expected, FRET emission (orange) was observed from lipid droplets within individual paramecium soon after exposure, followed by the gradual appearance of BODIPY emission at 515 nm (green fluorescence) indicative of substrate cleavage ( FIG. 8 ). To further demonstrate the behavior of BODIPY FR-PC in vivo, 5 dpf zebrafish larvae were bathed in BODIPY FR-PC. Within 1 hr, larvae exposed to BODIPY FR-PC showed a bright green fluorescent gallbladder and orange fluorescence within the apical cytoplasm of posterior intestinal cells ( FIG. 9C ). These cells are known to absorb luminal macromolecules through pinocytosis (107). Orange fluorescence indicative of uncleaved substrate also was observed after 4 hr of incubation in the anterior intestine epithelium, the site of lipid absorption in fish (82, 95). FRET emission was never detected in the liver even after prolonged incubation ( FIG. 9D ), implying that gallbladder fluorescence following ingestion of labeled lipids is due to cleavage by intestinal PLA 2 s. The evidence of the instant invention is consistent with the predicted pathway of lipid processing observed in mammals since uncleaved substrate (orange) was seen only in the intestinal epithelium. Over time, continuous exposure to BODIPY FR-PC either overwhelms intestinal lipase activity or leads to the integration of BODIPY FR-PC into the cellular phospholipid pool. Regardless, the data of the present invention provide further evidence that in zebrafish, as in mammals, lipids are absorbed and modified in the intestine prior to transport to the liver. Lipid Processing in Zebrafish Intestinal Mutants To determine the utility of the fluorescent lipids as reagents in a genetic screen, PED6 was administered to mutants known to perturb intestinal morphology (31), and the pattern and timing of gallbladder fluorescence was examined ( FIG. 10 ). These mutations cause embryonic lethality and each of the affected genes regulate intestinal development in a region-specific manner. The mutations slim jim (slj) and piebald (pie) each cause degeneration of anterior intestinal epithelium and exocrine pancreas, whereas meltdown (mlt) results in cystic expansion of the posterior intestine. As shown in FIGS. 10B and 10C , mlt mutants retain PED6 processing in the anterior intestine and show normal levels of gall bladder fluorescence. In contrast, pie ( FIGS. 10D & 10E ) and slj ( FIG. 10F ) mutants display greatly reduced gall bladder labeling. Although slj and pie have similar histological phenotypes, gall bladder fluorescence was absent in pie larvae but visible in slj larvae, albeit at a reduced level compared with wild-type or mlt larvae ( FIGS. 10B & 10C ). Hence, fluorescent lipids can be used to identify mutants with abnormal digestive organ morphology. Screening for Mutations that Perturb Lipid Processing Using Fluorescent PLA 2 Substrates Lipid reporters also are effective tools for identifying mutations that perturb lipid metabolism without causing obvious morphological defects. In a pilot screen, larval progeny of individual F2 families derived from an ENU mutagenesis protocol were bathed in PED6 and screened for digestive organ morphology and phospholipid processing. PED6 fluorescent metabolites dramatically enhanced digestive organ structure, facilitating scoring of gallbladder development, intestinal folding, and bile duct morphology. From 190 genomes screened, two mutations were identified and confirmed in the subsequent generation. These mutations were recovered based on their pattern of gallbladder fluorescence, not morphological criteria, thereby supporting the use of the fluorescent lipids of the instant invention in large-scale mutagenesis screens. Lipid processing was examined further in the identified mutants using a fluorescent cholesterol analog ( FIG. 1 ). EXAMPLE 1 Characterize the Biochemical Pathways Responsible for the Metabolism of the Fluorescent PLA 2 Substrates in Zebrafish To characterize, biochemically, the identity of fluorescent compounds present in the bile of zebrafish following exposure to fluorescent PLA 2 substrates and other lipid molecules, zebrafish were exposed to a panel of fluorescent phospholipids and free fatty acids that differed in acyl chain length and fluorophore position. The experiments enabled the determination of the phenotypic significance of recovered mutants by identifying shared pathways of lipid metabolism in zebrafish and mammals. Identity of the Fluorescent Lipid in the Bile of Fish Labeled with PED6 To determine whether the fluorescence in the bile is due to a reacylated phospholipid (lacks the DNP quencher on the head group) or exists as a free BODIPY-labeled fatty acid, adult fish were labeled with PED6 by gavage. Adult fish were used because of the small amount of lipid in larvae bile. Under a fluorescence stereomicroscope, the gall bladders were easily identified by their intense fluorescence. The gall bladders were removed at various times post-gavage and placed in cold methanol, sonicated and extracted (97). The organic fraction was then subjected to TLC analysis as described to determine whether the fluorescent sn2 acyl chain was re-esterified prior to biliary excretion ( FIGS. 11A & 11B ) (36, 98). This procedure was performed on five fish using D3806 (a red BODIPY PC, 582/593) ( FIG. 12 ). Identity of the Fluorescent Lipids in the Bile of Fish Labeled with BODIPY-C5. C12, C16 Fatty Acids To ascertain whether short chain fatty acids are transported via the portal system, adult zebrafish are injected with C16, C12 and C5 BODIPY-labeled fatty acids and then the fluorescent bile characterized biochemically using TLC. Based on work in other vertebrates, only short-chain fluorescent fatty acids can pass directly into the bile, consistent with transport via the portal vein, following injection of C16 BODIPY fatty acid (82, 99). The profile and kinetics of labeling are very different with the shorter chain analogues. Labeling of 5 dpf Larvae with BODIPY Labeled Fatty Acids and Phospholipids To extend the findings from the adult bile assays to younger fish, the rate of gallbladder fluorescence in zebrafish larvae exposed to BODIPY-labeled fatty acids and phospholipids with different chain lengths is compared. Larvae are soaked in the identical BODIPY fatty acids injected into the adults, and the rate of gall bladder fluorescence is assayed. The labeling rate is determined by placing a fish in water containing the fluorescent substrate and capturing a digital image of a lateral view (Axiovision, Zeiss and ImageQuant, Molecular Dynamics Inc.). The gall bladder fluorescence is quantified at various time intervals to compute the rate of change over time. Delayed appearance of gallbladder fluorescence after exposure to long chain fatty acids and phospholipids lends further support to the hypothesis that acyl chain length plays a role in lipid transport in zebrafish. PLAN Isoform Mediation of PED6 Processing It is well established that cPLA 2 and some iPLA 2 isoforms exhibit acyl chain specificity and favor phospholipids that contain arachidonic acid, the precursor of eicosanoids (41, 44). Despite the fact that the fluorescent phospholipids do not contain arachidonic acid, the placement of the BODIPY moiety on the sn2 position results in significant cleavage by cPLA 2 (36, 94). The ability of the BODIPY moiety to disrupt the membrane and its hydrophobicity are both properties similar to arachidonic acid that enable cleavage by cPLA 2 (100). Secreted PLA 2 isoforms exhibit no acyl chain specificity (34). Fluorescent phospholipids that contain a saturated acyl chain on the sn2 position are fine sPLA 2 substrates but poor cPLA 2 ones. To identify which PLA 2 isoforms mediate the appearance of fluorescence in the gall bladder, the rate of gall bladder fluorescence is compared in larvae exposed to two types of substrates. Larvae are labeled with two phospholipid substrates that differ in their specificity for cPLA 2 : a PL with an sn1 BODIPY and an sn2 saturated acyl chain—a poor PLA 2 substrate, or BODIPY FR-PC—a good cPLA 2 substrate. If little difference is observed in the rates of gall bladder fluorescence using the two substrates, then the critical lipase important for the processing of these lipids is a secreted PLA 2 isoform, a promiscuous enzyme that exhibits little acyl chain preference (96). BODIPY FR-PC is used because no other available fluorescent phospholipid contains sn2 arachidonic acid. Taken together, the experiments clarify the relevant PLA 2 isoforms, the route(s) of phospholipid/fatty acid transport, and allow refinement of the screening reagents (e.g., by preparing cocktails of fluorophores to target specific transport processes). EXAMPLE 2 A Mutagenesis Screen to Identify Genes that Regulate Lipid Processing in Zebrafish In the instant invention a large-scale genetic screen for genes that regulate lipid processing in zebrafish using fluorescent PLA 2 substrates is disclosed. This screen leads to the recovery of mutations that regulate a wide range of developmental and physiological processes. As outlined, the screen identifies mutations that either resemble or are allelic to previously described intestinal mutations. Given the large number of steps required for processing of the fluorescent PLA 2 substrates, however, this screen leads to the recovery of genes that could not be identified using standard screening strategies. These include, but are not limited to, genes that directly regulate PLA 2 ; genes responsible for the development of the liver, biliary system, and the intestinal vasculature and lymphatics; and genes that play a direct role in lipid metabolism and transport. The mutagenesis and screening strategies of the instant invention incorporate several well established methodologies. First, adult male fish are mutagenized with ENU using established dosing schedules. Second, the F1 progeny of the mutagenized G0 fish will be bred to homozygosity using a classical 3 generation protocol (F3 screen), as well as parthenogenetically, using the early-pressure (EP) technique (103). Zebrafish larvae generated in this fashion are soaked in the BODIPY FR-PC, PED6, and/or NBD cholesterol ( FIG. 13 ) lipid reagents at 5 dpf and then screened for defects in lipid processing based upon the timing and pattern of fluorescence in the intestine, liver and gallbladder. Parallel F3 and EP screens are employed because they offer the best opportunity to maximize the use of resources. Although EP screens are in many ways less efficient than classical F3 screens, they are suited to moderate sized fish facilities and require less manpower because of the reduced number of matings required. ENU Mutagenesis For the EP screen, adult male fish from the “*AB” zebrafish line (this line of fish carries the fewest number of haplo-insufficient or lethal mutations of common lab strains) are exposed to ENU (3.5 mM) in a secluded fume hood for 30 minutes on 3 consecutive days. After taking the necessary precautions to remove adherent ENU, the fish are returned to the main fish facility and outcrossed to WT fish from the Wik genetic background 3 weeks after mutagenesis, and the F1 progeny are raised to sexual maturity. To improve the likelihood that the *AB mutagenized males do not carry significant mutations in their genetic background, mutagenized males are outcrossed only if 5 of their female siblings produce large clutches of viable EP embryos that survive to 5 dpf. The efficacy of ENU mutagenesis is determined prior to outcrossing by calculating the specific locus rate for new mutations at the alb, spa, and bra loci. One week after ENU exposure, the mutagenized G0 males are mated to double-mutant “tester” female carriers of the alb, spa, and bra mutations and their 32 hpf progeny are analyzed for clones of alb/alb, spa/spa, and bra/bra mutant pigmented cells. Based upon published SLR's for these loci using our ENU dosing schedule there is a need to analyze approximately 1500-2000 progeny from each mutagenized G0 fish to accurately determine the efficacy of mutagenesis. Screening for Mutations that Perturb Lipid Processing For screening, 5 dpf larvae derived from pair-wise matings of F2 families or EP treatment of F1 females are soaked fluorescent lipids for 1-10 hrs and analyzed for perturbation of lipid processing using a fluorescent stereo-microscope (Leica MZ FLIII). The BODIPY FR-PC and PED6 reagents used in the screen are purified via TLC, resuspended in ethanol/DMSO and tested in vivo using WT 5 dpf larvae prior to screening. The F3 5 dpf larvae for screening are derived from pair-wise matings of fish from F2 families, while 5 dpf larvae produced parthenogenetically are produced using standard EP protocols: briefly, eggs are collected from anesthetized F1 females (tricaine) and exposed to UV irradiated sperm following standard in vitro fertilization (IVF) protocols. Immediately after IVF (1.4 min.), the fertilized eggs are exposed to 13,000 psi in a French Press for 4-6 min, then slowly returned to ambient atmospheric pressure and allowed to develop until 5 dpf (103). Putative mutations that alter the pattern or rate of accumulation of lipid fluorescence in the digestive organs, as well as those that produce specific alterations in larval morphology, are recovered and outcrossed for future analysis. Mutations that result in a generalized delay in larval development are not analyzed given their high frequency of recovery in prior chemical mutagenesis screens. For the F3 screen, no less than 20, 5 dpf larvae are analyzed from ≧6 crosses per F2 family. Using this strategy, excluding lethal effects of haploinsufficiency in heavily mutagenized genomes, the theoretical chance of recovering a mutation present in the genome of an F2 family is ≧89%. For the EP screen, all of the viable progeny derived from each F1 female are analyzed. In contrast to the F3 screen, the statistical likelihood of recovering mutations in the genome of F1 females treated with EP is not predictable given the tendency to recover smaller viable clutches with this technique, and the potential for meiotic recombination to alter Mendelian inheritance patterns. Only those heritable defects that can be recovered in statistically significant Mendelian ratios when outcrossed, are considered mutations. The data and analysis of known intestinal mutants suggest that lipid processing mutations are not rare mutations. A total of approximately 750-2000 mutanized genomes are screened. EXAMPLE 3 Determination of the Physiological Significance and Molecular Nature of Recovered Mutations The instant invention discloses methods for characterizing, both phenotypically and molecularly, the generated mutations. Phenotypic analysis is approached first. Mutations that affect a wide range of developmental and physiological processes are recovered in the screen. Careful phenotypic analysis of these mutants is important for several reasons. First, it allows quantitation of the range and frequency of phenotypes actually recovered using the fluorescent lipid reagents. Second, it allows the performance of comprehensive complementation analyses so that hypomorphic alleles of interesting mutations are not overlooked. Third, it allow the selection of those mutations worthy of molecular analysis now versus mutations that may be of more immediate interest to other members of the zebrafish scientific community. The rationale for the molecular analysis of zebrafish mutations is well known to those of skill in the art. Recognition of the importance of phenotypic analyses of mutant phenotypes prior to molecular analyses is relevant given the large amount of work that is often required to identify the responsible gene. Phenotypic Analyses Mutant phenotypes recovered using the screen of the instant invention can be categorized into several broad categories. First, using morphological and histological criteria mutations that visibly perturb structural development of the pharynx, esophagus, intestine, liver and biliary tract are distinguished from those mutants that appear normal. The latter group is considered physiological mutants and is categorized based upon its handling of the panel of fluorescent lipids of the instant invention. This group encompasses, but is not limited to, mutations affecting the intestinal epithelium, liver, vasculature and lymphatics, enteric neuromusculature, and the tissue specific regulation of PLA 2 . Embryological and transient expression assays also are important studies that can aid phenotypic analyses of zebrafish mutants. Unfortunately, mutations affecting development of the zebrafish digestive organs are, in general, less easily analyzed using these techniques than mutations affecting early development. The short half-life of injected RNA transcripts and DNA expression constructs coupled with the mosaic distribution of the micro-injected DNA limits the utility of transient expression assays for mutations that are not recognizable until 4-5 dpf. In one embodiment of the instant invention, histological analyses are performed by fixing larvae in 4% paraformaldehyde, embedding the fixed larvae in glycolmethacrylate, and followed by sectioning. Sections are stained using toluene blue/azure II as described and analyzed using a Zeiss Axioplan compound microscope. When needed, selected immunocytochemical and molecular markers are employed to further categorize organ specific defects. If necessary ultrastructural studies are performed as well. For “physiological” mutations, affected larvae are sequentially soaked in the fluorescent lipids of the instant invention, thereby allowing a more detailed categorization. Molecular Analyses The molecular characterization of zebrafish mutations can be performed using techniques widely known to those of skill in the art. These techniques include, but are not limited to, use of an ever expanding array of physical and genetic markers, several large insert genomic DNA libraries, outstanding bioinformatics, and a successful EST program. Recent announcement of plans to physically map and sequence the zebrafish genome suggest that within 2-3 years molecular characterization of zebrafish mutants will be greatly simplified. One of the major advantages of working in zebrafish compared with other vertebrates is the potential to generate high-resolution maps of mutant loci. Since mutations can be confidently mapped to within 0.1 cM, the critical interval surrounding a mutant locus can be narrowed to include relatively few candidate genes. The recent identification of the genes responsible for several zebrafish mutants demonstrates this nicely. In one embodiment of the instant invention, the molecular characterization of identified mutations is accomplished by introducing mutations into a polymorphic genetic background and assigning a chromosomal location using either bulk segregant analyses and polymorphic markers from the 25 zebrafish linkage groups or using half tetrads and polymorphic centromeric markers. Concomitantly, DNA from large numbers of mutant progeny from the “map cross” are extracted and stored. Thereafter, the genetic map of the region surrounding the locus is refined using standard PCR based techniques and genetic markers from existing maps. The closest known genetic markers flanking the mutant locus are then used to screen large insert genomic libraries to identify more closely linked markers. For BAC and PAC clones this involves direct sequencing, whereas for YAC clones this requires rescue and sequencing of the zebrafish genomic DNA adjacent to the YAC arms. Ultimately, flanking markers within 0.1 cM of the mutant locus are identified, and a BAC or PAC clone spanning the locus is analyzed for the responsible gene. The latter is accomplished by direct sequencing, using the genomic insert to probe an appropriately staged genomic library and/or exon trapping. Confirmation of mutation is accomplished via expression analyses and mutant rescue, using transient analyses, if possible, or via transgenesis. Identification of tightly linked flanking markers generally involves a BAC, PAC, or YAC chromosomal walk, using markers mapped genetically and physically (radiation hybrid panel). In one embodiment of the instant invention, genetic mapping is performed using PCR based techniques. SSR polymorphisms are resolved using denaturing (SSR) polyacrylamide gel electrophoresis while single base-pair polymorphisms are resolved using Conformation Sensitive. Gel Electrophoresis (CSGE), a non-denaturing technique related to SSCP. DNA detection is accomplished using a Molecular Dynamics Fluorescent Scanner; PCRs use Cy-5 end-labeled primers. PCR fragments generated using non-fluorescent primers are visualized on polyacrylamide gels after staining with the fluorescent intercalating dye Syto-61 (Molecular Probes). For bulk segregant analyses, separate pools of DNA from 25 mutant larvae and 25 sibling WT larvae are generated and the segregation of SSR or single base pair polymorphic markers derived from ESTs analyzed. For physical mapping, the LN 540 (104) and Goodfellow Radiation Hybrid panels are employed. Markers are mapped using a PCR based strategy and computer assisted analysis of amplification patterns. Screening of genomic libraries, rescue of YAC ends, generation of YAC, BAC, and PAC clones is accomplished using the commercial suppliers or published protocols, which are known to those of skill in the art. All other molecular techniques outlined above employ published protocols, which also are known to those of ordinary skill in the art. EXAMPLE 4 Drug Screening Assays The invention provides methods for identifying compounds or agents that can be used to treat disorders characterized by (or associated with) aberrant or abnormal lipid and/or cholesterol metabolism. These methods are also referred to herein as drug screening assays and typically include the step of screening a candidate/test compound or agent for the ability to modulate (e.g., stimulate or inhibit) lipid and/or cholesterol metabolism. Candidate/test compounds or agents that have one or more of these abilities can be used as drugs to treat disorders characterized by aberrant or abnormal lipid and/or cholesterol metabolism. Candidate/test compounds or agents include, for example, (1) peptides such as soluble peptides, including Ig-tailed fusion peptides and members of random peptide libraries (see e.g., Lam, K. S. et al. (1991) Nature 354:82-84; Houghten, R. et al. (1991) Nature 354:84-86) and combinatorial chemistry-derived molecular libraries made of D- and/or L-configuration amino acids; (2) phosphopeptides (e.g., members of random and partially degenerate, directed phosphopeptide libraries, see, e.g., Songyang, Z. et al. (1993) Cell 72:767-778); (3) antibodies (e.g., polyclonal, monoclonal, humanized, anti-idiotypic, chimeric, and single chain antibodies as well as Fab, F(ab′) 2 , Fab expression library fragments, and epitope-binding fragments of antibodies); and (4) small-organic and inorganic molecules (e.g., molecules obtained from combinatorial and natural product libraries). In one embodiment, the invention provides a method for identifying a compound capable of use in the treatment of a disorder characterized by (or associated with) aberrant or abnormal lipid and/or cholesterol metabolism. This method typically includes the step of assaying the ability of the compound or agent to modulate lipid and/or cholesterol metabolism, thereby identifying a compound for treating a disorder characterized by aberrant or abnormal lipid and/or cholesterol metabolism. Disorders characterized by aberrant or abnormal lipid and/or cholesterol metabolism are described herein. The invention provides screening assays to identify candidate/test compounds or agents that modulate lipid and/or cholesterol metabolism. Typically, the assays include the steps of identifying at least one phenotypic perturbation of lipid and/or cholesterol metabolism in an organism, administering at least one quenched or fluorescently-tagged phospholipid, cholesterol or other lipid analogue to the organism having the phenotypic perturbation, administering a candidate/test compound or agent to the organism under conditions that allow for the uptake of the candidate/test compound or agent by the organism and wherein but for the presence of the candidate/test compound or agent the pattern of fluorescence would be unchanged, and detecting a change in the pattern of fluorescence by comparing the pattern of fluorescence prior to candidate/test compound or agent administration with that seen following administration of the candidate/test compound or agent. Mutagenesis screens using fluorescent lipids exploit the advantages of combining genetic analyses with imagining of enzymatic function. The existence of related lipid processing mechanisms in mammals and teleosts, and the finding that therapeutic drugs used to modify lipid metabolism in humans are active in zebrafish, establish that genetic screens can be designed to probe the mechanistic basis of acquired and heritable human disorders. The evidence of the instant invention demonstrates that lipid metabolism in mammals and fish can be monitored with fluorescent lipids, and that such organisms metabolize ingested fluorescent lipids in an analogous manner. Consequently, the methods for using the fluorescent lipids of the instant invention to study lipid metabolism, identify diseases of lipid metabolism, and/or to identify agents to treat therapeutically or prophylatically diseases or disorders of lipid metabolism and genetic screening are applicable to all vertebrate model organisms, including, but not limited to, rodents, amphibia, and fish. 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The present invention utilizes fluorescent lipids, particularly quenched phospholipid or cholesterol analogues, to facilitate screening for phenotypes representing perturbations of lipid and/or cholesterol processing in a vertebrate; screening for genetic mutations that lead to disorders of phospholipid and/or cholesterol metabolism; and screening of compounds designed to treat disorders of phospholipid and/or cholesterol metabolism in the vertebrate.

[0001] This application claims priority to U.S. Provisional application Ser. No. 60/862,350, filed Oct. 20, 2006 and U.S. Provisional application Ser. No. 60/735,429, filed Nov. 10, 2005 which are incorporated by reference herein in their entirety. FIELD OF THE INVENTION [0002] The present invention relates to compositions and methods for controlling splicing of pre-mRNA molecules and regulating protein expression with splice switching oligonucleotides or splice switching oligomers (SSOs). SSOs are not limited to nucleotides but include any polymer or molecule that is able to hybridize to a target RNA with sequence specificity and does not activate RNase H or otherwise lead to degradation of the target RNA. Specifically described embodiments concern receptors for the tumor necrosis factor (TNF) superfamily. BACKGROUND OF THE INVENTION [0003] The production of mRNA by eukaryotic cells is a two-stage process. First, a long contiguous transcript, pre-messenger RNA (pre-mRNA), is formed. The pre-mRNA contains sequences that code for protein (exons) interspersed with sequences that do not code for protein (introns). Second, the introns of the transcript are removed and the exons are joined by a process called splicing. This process is a key step in generation of mature, functional mRNA. The 5′ end of each intron contains a splice-donor site or 5′ splice site, and the 3′ end of each intron contains a splice acceptor or 3′ splice site. Processing of pre-mRNA involves a complex containing protein and RNA molecules, referred to collectively as the spliceosome, which carries out splicing and transport of mRNA from the nucleus. [0004] When alternative splice sites are present, the splicing step permits the synthesis of two or more (related) proteins from a single gene (See, e.g., Gist, A., 2005, Scientific American, April, p. 60). Among the genes that employ alternative splicing as a physiological mechanism are the cell-surface receptors for protein cytokines that influence the inflammatory and immune system. These proteins are expressed in an integral membrane form and transduce signals in response to cytokine ligand binding. Such cytokine receptors also exist as a secreted form that can bind cytokine and prevent signal transduction. These two receptor forms are produced by alternative splicing and differ by the deletion of the one or more exons needed to encode the membrane-spanning domain of the molecule. For some receptors, a soluble fragment of the receptors, distinct from the secreted splice variants, is produced by proteolytic cleavage of the extracellular domain from the integral membrane bound receptors. [0005] One such family of receptors is the TNF receptor (TNFR) superfamily. The TNFR superfamily currently consists of 29 receptors that mediate cellular signaling as a consequence of binding to one or more of the 19 ligands currently identified in the TNF superfamily. The TNFR superfamily is a group of type I transmembrane proteins, with a carboxy-terminal intracellular domain and an amino-terminal extracellular domain characterized by a common cysteine rich domain (CRD). The TNFR superfamily can be divided into two subgroups: receptors containing the intracellular death domain (DD) and those lacking it. The DD is an 80 amino acid motif that is responsible for the induction of apoptosis following receptor activation. Additionally, TNF-α receptor type I (TNFSFR1A, hereafter “TNFR1”, exemplified by GenBank accession number X55313 for human mRNA) and TNF-α receptor type II (TNFSF1B, hereafter “TNFR2”, exemplified by GenBank accession number NM — 001066 for human mRNA) have a unique domain in common, called the pre-ligand-binding assembly domain (PLAD) that is required for assembly of multiple receptor subunits and subsequent binding to TNF-α. Most members of the TNFR superfamily activate signal transduction by associating with TNFR-associated factors (TRAFs). The association is mediated by specific motifs in the intracellular domain of TNFR superfamily members. (Palladino, M. A., et al., 2003, Nat. Rev. Drug Discov. 2:736-46). Other members of the TNFR superfamily include RANK (TNFRSF11A), CD40 (TNFRSF5), CD30 (TNFRSF8), and LT-βR (TNFRSF3). [0006] TNF-α is a pro-inflammatory cytokine that exists as a membrane-bound homotrimer and is released into the circulation by the protease TNF-α converting enzyme (TACE). TNF-α is introduced into the circulation as a mediator of the inflammatory response to injury and infection. TNF-α activity is implicated in the progression of inflammatory diseases such as rheumatoid arthritis, Crohn's disease, ulcerative colitis, psoriasis and psoriatic arthritis (Palladino, M. A., et al., 2003, Nat. Rev. Drug Discov. 2:736-46). The acute exposure to high levels of TNF-α, as experienced during a massive infection, results in sepsis; its symptoms include shock, hypoxia, multiple organ failure, and death. Chronic low doses of TNF-α can cause cachexia, a disease characterized by weight loss, dehydration and fat loss, and is associated with malignancies. [0007] TNF-α activity is mediated primarily through two receptors coded by two different genes, TNFR1 and TNFR2. TNFR1 is a membrane-bound protein with a molecular weight of approximately 55 kilodaltons (kDal), while TNFR2 is a membrane-bound protein with a molecular weight of 75 kDal. The soluble extracellular domains of both receptors are shed to some extent from the cell membrane by the action of metalloproteases. Moreover, the pre-mRNA of TNFR2 undergoes alternative splicing, creating either a full length, active membrane-bound receptor (mTNFR2), or a secreted decoy receptor (sTNFR2) that lacks exons 7 and 8 which encompasses the coding sequences for the transmembrane (Lainez et al., 2004, Int. Immunol., 16:169). The sTNFR2 binds TNF-α but does not elicit a physiological response, thus reducing TNF-α activity. Although an endogenous, secreted splice variant of TNFR1 has not yet been identified, the similar gene structures of the two receptors strongly suggest the potential to produce this TNFR1 isoform. [0008] Knockout mice lacking both TNFR1 and TNFR2 treated with drugs that target the TNF signaling pathways indicate such drugs may be beneficial in treating stroke or traumatic brain injury (Bruce, et al., 1996, Nat. Med. 2:788). TNFR2 knockout mice were also used to establish a role for TNFR2 in experimentally-induced cerebral malaria (Lucas, R., et al., 1997, Eur. J. Immunol. 27:1719) and autoimmune encephalomyelitis (Suvannavejh, G. C., et al., 2000, Cell. Immunol., 205:24), models for human cerebral malaria and multiple sclerosis, respectively. [0009] TNFR2 is present at high density on T cells and appears to play a role in the immune responses that lead to alveolitis in the pulmonary microenvironment of interstitial lung disease (Agostini, C., et al., 1996, Am. J. Respir. Crit. Care Med, 153:1359). TNFR2 is also implicated in human metabolic disorders of lipid metabolism and has been associated with obesity and insulin resistance (Fernandez-Real, et al., 2000, Diabetes Care, 23:831), familial combined hyperlipidemia (Geurts, et al., 2000, Hum. Mol. Genet. 9:2067; van Greevenbroek, et al., 2000, Atherosclerosis, 153:1), hypertension and hypercholesterolemia (Glenn, et al., 2000, Hum. Mol. Genet, 9:1943). TNFR2 has recently been associated with human narcolepsy (Komata, T., et al., 1999, Tissue Antigens, 53:527). In addition, TNFR2 polymorphism appears to lead to susceptibility to systemic lupus erythematosus (Hohjoh, H., et al., 2000, Tissue Antigens, 56:446). [0010] Splice variants of CD40 (Tone, M., et al., 2001, Proc. Natl. Acad. Sci. 98:1751) (“Tone”), and CD95 (FAS) (Shen, L., et al., 2002, Am. J. Path. 161:2123), have been found in malignancies. Several of these splice variants result in loss of the transmembrane region due to deletion or due to mutations affecting the reading frame of exon 7. Whether these represent aberrant variants resulting from malignant transformation or physiological alternatives is not yet known. [0011] Because of the role played by excessive activity by TNF superfamily members, it would be useful to control the alternative splicing of TNFR receptors so that the amount of the secreted form is increased and the amount of the integral membrane form is decreased. The present invention provides splice switching oligonucleotides or splice switching oligomers (SSOs) to achieve this goal. SSOs are similar to antisense oligonucleotides (ASONs). However, in contrast to ASON, SSOs are able to hybridize to a target RNA without causing degradation of the target by RNase H [0012] SSOs have been used to modify the aberrant splicing found in certain thalassemias (U.S. Pat. No. 5,976,879 to Kole; Lacerra, G., et al., 2000, Proc. Natl. Acad. Sci. 97:9591). Studies with the IL-5 receptor α-chain (IL-5Rα) demonstrated that SSOs directed against the membrane-spanning exon increased synthesis of the secreted form and inhibited synthesis of the integral membrane form (U.S. Pat. No. 6,210,892 to Bennett; Karras, J. G., et al., 2000, Mol. Pharm, 58:380). [0013] The IL-5 receptor is a member of a receptor type that occurs as a heterodimer. The interleukin 5 receptor (IL-5R) is a member of the IL-3R family of receptors, which also includes interleukin 3 receptor (IL-3R) and GM-CSF. IL-3R family members are multisubunit receptors consisting of a shared common β chain, and a unique a chain that conveys cytokine ligand specificity. IL-3R family members are expressed in the hematopoietic system. In particular, IL-5 is expressed exclusively in eosinophils, basophils and B cells (Adachiand, T. & Alam, R., 1998, Am. J. Physiol. 275:C623-33). These receptors and the TNFR superfamily of the present invention have no sequence homology and operate in distinct signaling pathways. [0014] SSOs have been used to produce the major CD40 splice variant detected in Tone, in which deletion of exon 6, which is upstream of the transmembrane region, resulted in an altered reading frame of the protein. While the SSO resulted in the expected mRNA splice variant, the translation product of the variant mRNA appeared to be unstable because the secreted receptor could not be detected (Siwkowski, A. M., et al., 2004, Nucleic Acids Res. 32; 2695). SUMMARY OF THE INVENTION [0015] The present invention provides compositions and methods for controlling expression of TNF receptors (TNFR1 and TNFR2) and of other cytokine receptors from the TNFR superfamily by controlling the splicing of pre-mRNA that codes for the said receptors. More specifically, the invention causes the increased expression of the secreted form and the decreased expression of the integral-membrane form. Furthermore, the invention can be used in the treatment of diseases associated with excessive cytokine activity. [0016] The exon or exons that are present in the integral membrane form mRNA but are removed from the primary transcript (the “pre-mRNA”) to make a secreted form mRNA are termed the “transmembrane exons.” The invention involves nucleic acids and nucleic acid analogs that are complementary to either of the transmembrane exons and/or adjacent introns of a receptor pre-mRNA. Complementarity can be based on sequences in the sequence of pre-mRNA that spans the splice site, which would include, but is not limited to, complemtarity based on sequences that span the exon-intron junction, or complementarity can be based solely on the sequence of the intron, or complementarity can be based solely on the sequence of the exon. [0017] There are several alternative chemistries available and known to those skilled in the art. One important feature is the ability to hybridize to a target RNA without causing degradation of the target by RNase H as do 2′-deoxy oligonucleotides (“antisense oligonucleotides” hereafter “ASON”). For clarity, such compounds will be termed splice-switching oligomers (SSOs). Those skilled in the art appreciate that SSO include, but are not limited to, 2′ O-modified oligonucleotides and ribonucleosidephosphorothioates as well as peptide nucleic acids and other polymers lacking ribofuranosyl-based linkages. [0018] One embodiment of the invention is a method of treating an inflammatory disease or condition by administering SSOs to a patient or a live subject. The SSOs that are administered alter the splicing of a pre-mRNA to produce a splice variant that encodes a stable, secreted, ligand-binding form of a receptor of the TNFR superfamily, thereby decreasing the activity of the ligand for that receptor. In another embodiment, the invention is a method of producing a stable, secreted, ligand-binding form of a receptor of the TNFR superfamily in a cell by administering SSOs to the cell. [0019] The foregoing and other objects and aspects of the present invention are discussed in detail in the drawings herein and the specification set forth below. BRIEF DESCRIPTION OF THE DRAWINGS [0020] FIG. 1 depicts the structure of a portion of the tumor necrosis factor receptor pre-mRNA and spliced products for TNFR1 and TNFR2. These transcripts normally contain exon 7 and exon 8, which code for the transmembrane domain of the receptors. SSOs (bars) directed towards either or both of these exons elicit alternative splicing events, resulting in transcripts that lack the full transmembrane domain. [0021] FIG. 2 shows the splicing products of SSOs for murine TNFR1 in cell culture. NIH-3T3 cells were mock transfected [Lipofectamine® 2000 (LFA2000 Only)] or transfected with the indicated concentration of either an exon 7 skipping TNFR1 SSO, A7-5 or A7-10, alone or a combination of exon 7 skipping SSO and an exon 8 skipping SSO, A8-3. Total RNA was isolated and RT-PCR performed 24 hours later. The PCR primers were used to amplify from Exon 5 to Exon 9, so that “Full Length” TNFR1 is represented by a 475 bp band. Transcripts lacking exon 7 (Δ Exon 7) and lacking both exon 7 and exon 8 (Δ Exon 7/8) are represented by 361 bp and 332 bp bands, respectively. [0022] FIG. 3 shows the splicing products of SSOs for murine TNFR2 in cell culture. NIH-3T3 cells were mock transfected (LFA2000 Only) or transfected with the indicated concentration of either an exon 7 skipping TNFR2 SSO, B7-6 or B7-1, alone or a combination of exon 7 skipping oligonucleotide and an exon 8 skipping oligonucleotide, B8-4. Total RNA was isolated and RT-PCR performed 24 hours later. The PCR primers were used to amplify from Exon 5 to Exon 9, so that “Full Length” TNFR2 is represented by a 486 bp band. Transcripts lacking exon 7 (Δ Exon 7) and lacking both exon 7 and exon 8 (Δ Exon 7/8) are represented by 408 bp and 373 bp bands, respectively. [0023] FIGS. 4A and 4B present the sequences of exons 7 ( 4 A) and 8 ( 4 B) of murine TNFR1 and of the flanking introns. Also shown are the sequences of 2′O-Me-oligoribonucleoside-phosphorothioate SSOs that were assayed for splice switching activity. [0024] FIGS. 5A and 5B present the sequences of exons 7 ( 5 A) and 8 ( 5 B) of murine TNFR2 and of the flanking introns. Also shown are the sequences of 2′O-Me-oligoribonucleoside-phosphorothioate SSOs that were assayed for splice switching activity. [0025] FIG. 6 provides an alignment of the human and murine TNF receptor genes in the regions that encode the transmembrane exons. The murine sequences, SEQ ID Nos: 107, 108, 109, and 110, are homologous to the human sequences, SEQ ID Nos: 1, 2, 3, and 4, respectively. [0026] FIG. 7 shows the splicing products of SSOs for primary mouse hepatocyte cultures, in assays conducted as described in FIGS. 2 and 3 . [0027] FIGS. 8A-8D provide mouse and human TNFR2 (TNFRSF1B) ( 8 A and 8 B) and TNFR1 (TNFRSF1A) ( 8 C and 8 D) LNA SSO sequences from Tables 2 and 3. FIGS. 8A and 8C schematically illustrate the position of each SSO relative to the targeted exon. FIGS. 8B and 8D show the pre-mRNA sequence (5′ to 3′) and the SSOs (3′ to 5′) hybridized to it. [0028] FIG. 9 shows the splicing products for L929 murine cells treated with LNA SSOs. Cells were transfected with the indicated LNA SSO at a final concentration of 50 nM. After 24 hours, the cells were lysed and analyzed for splice switching by RT-PCR. Top panel, SSOs targeted to exon 7; bottom panel, SSOs targted to exon 8. FL, full length TNFR2 amplicon; Δ7, Δ8, Δ7/8, amplicons of the respective TNFR2 splice variants. [0029] FIG. 10 shows the splicing products for L929 murine cells using LNA SSO combinations targeted to TNFR2. L929 cells were treated with the indicated single or multiple LNA SSOs at 50 nM each and analyzed 24 hours later as described in FIG. 9 . [0030] FIG. 11 the splicing products for L929 murine cells using LNA SSO combinations targeted to TNFR1. L929 cells were treated with the indicated single or multiple LNA SSOs at 50 nM each and analyzed 24 hours later as described in FIG. 9 . [0031] FIG. 12 shows the splicing products for primary mouse hepatocytes treated with LNA SSOs. Primary mouse hepatocytes were transfected with 33 nM each final concentration of the indicated single or multiple LNA SSOs and analyzed as described in FIG. 9 . [0032] FIG. 13 graphically illustrates detection of secreted TNFR2 splice variants from L929 cells (left) and primary mouse hepatocytes (right). Cells were transfected with the indicated LNA SSOs. After 72 hours, the extracellular media was removed and analyzed by enzyme linked immunosorbant assay (ELISA) using antibodies from the Quantikine® Mouse sTNF RII ELISA kit from R&D Systems (Minneapolis, Minn.). The data are expressed as pg soluble TNFR2 per mL. [0033] FIG. 14 shows the splicing products for primary human hepatocytes treated with LNA SSOs targeted to TNFR2. Primary human hepatocytes were transfected with the indicated LNA SSO and analyzed for splice switching by RT-PCR after 24 hours as described in FIG. 9 . The PCR primers were used to amplify from Exon 5 to Exon 9, so that “Full Length” (FL) TNFR2 is represented by a 463 bp band. Transcripts lacking exon 7 (Δ Exon 7), lacking exon 8 (Δ Exon 8), and lacking both exon 7 and exon 8 (Δ exon 7/8) are represented by 385 bp, 428 bp, and 350 bp bands, respectively. [0034] FIG. 15 shows the splicing products for intraperitoneal (i.p.) injection of LNA 3274 (top) and 3305 (bottom) in mice. LNA 3274 was injected i.p. at 25 mg/kg/day for either 4 days (4/1 and 4/10) or 10 days (10/1). Mice were sacrificed either 1 day (4/1 and 10/1) or 10 (4/10) days after the last injection and total RNA from liver was analyzed for splice switching of TNFR2 by RT-PCR. LNA 3305 was injected at the indicated dose per day for 4 days. Mice were sacrificed the next day and the livers analyzed as with 3274 treated animals. [0035] FIG. 16 (top panel) graphically illustrates the amount of soluble TNFR2 in mouse serum 10 days after SSO treatment. Mice were injected i.p. with the indicated SSO or saline (n=5 per group) at 25 mg/kg/day for 10 days. Serum collected 4 days before injections began and the indicated number of days after the last injection. Sera was analyzed by ELISA as described in FIG. 13 . At day 10, mice were sacrificed and livers were analyzed for TNFR2 splice switching by RT-PCR (bottom panel) as described in FIG. 9 . [0036] FIG. 17 graphically illustrates the amount of soluble TNFR1 in the serum after TNFR2 SSO treatment. Mouse serum from FIG. 16 was analyzed for soluble TNFR1 by ELISA using antibodies from the Quantikine® Mouse sTNF RI ELISA kit from R&D Systems (Minneapolis, Minn.). [0037] FIG. 18 (top panel) graphically illustrates the amount of soluble TNFR2 in mouse serum 27 days after SSO treatment. Mice were treated as in FIG. 16 , except that serum samples were collected until day 27 after the last injection. LNA 3083 and 3272 are control SSOs with no TNFR2 splice switching ability. At day 27, mice were sacrificed and livers were analyzed for TNFR2 splice switching by RT-PCR (bottom panel) as described in FIG. 9 . [0038] FIG. 19 graphically depicts the anti-TNF-α activity in serum from LNA oligonucleotide-treated mice. L929 cells were treated with either 0.1 ng/mL TNF-α (TNF), or TNF-α plus 10% serum from mice treated with the indicated oligonucleotide (see also FIG. 18 ). Cell viability was measured 24 hours later and normalized to untreated cells (Untreated). [0039] FIG. 20 graphically compares the anti-TNF-α activity of serum from LNA oligonucleotide-treated mice to recombinant soluble TNFR2 (rsTNFR2) and to that of Enbrel® using the cell survival assay described in FIG. 19 . DETAILED DESCRIPTION OF THE INVENTION [0040] As used herein, the terms “tumor necrosis factor receptor superfamily” or “TNFR superfamily” or “TNFRSF” refer to a group of type I transmembrane proteins, with a carboxy-terminal intracellular domain and an amino-terminal extracellular domain characterized by a common cysteine rich domain (CRD). The TNFR superfamily consists of receptors, mediate cellular signaling as a consequence of binding to one or more ligands in the TNF superfamily. The TNFR superfamily can be divided into two subgroups: receptors containing the intracellular death domain (DD) and those lacking it. The DD is an 80 amino acid motif that is responsible for the induction of apoptosis following receptor activation. Members of the TNFR superfamily include, but are not limited to, TNFR1 (TNFRSF1A), TNFR2 (TNFRSF1B), RANK (TNFRSF11A), CD40 (TNFRSF5), CD30 (TNFRSF8), and LT-βR (TNFRSF3). [0041] As used herein, the terms “tumor necrosis factor superfamily” or “TNF superfamily” refer to the group of ligands that bind to one or more receptors in the TNFR superfamily. The binding of a TNF family ligand to its corresponding receptor or receptors mediate cellular signaling. Members of the TNF superfamily include, but are not limited to, TNF-α, RANKL, CD40L, LT-α, or LT-β. [0042] As used herein, the term “an inflammatory disease or condition” refers to a disease, disorder, or other medical condition that at least in part results from or is aggravated by the binding of a ligand from the TNF superfamily to its corresponding receptor or receptors. Such diseases or conditions include, but are not limited to, those associated with increased levels of the TNF superfamily ligand, increased levels of TNFR superfamily receptor levels, or increased sensitization of the corresponding signaling pathway. Examples of inflammatory diseases or conditions include, but are not limited to, rheumatoid arthritis, juvenile rheumatoid arthritis, psoriasis, psoriatic arthritis, ankylosing spondylitis, inflammatory bowel disease (including Crohn's disease or ulcerative colitis), hepatitis, sepsis, alcoholic liver disease, and non-alcoholic steatosis. [0043] As used herein, the term “hepatitis” refers to a gastroenterological disease, condition, or disorder that is characterized, at least in part, by inflammation of the liver. Examples of hepatitis include, but are not limited to, hepatitis associated with hepatitis A virus, hepatitis B virus, hepatitis C virus, or liver inflammation associated with ischemia/reperfusion. [0044] As used herein, the terms “membrane bound form” or “integral membrane form” refer to proteins having amino acid sequences that span a cell membrane, with amino acid sequences on each side of the membrane. [0045] As used herein, the term “stable, secreted, ligand-binding form” or as it is sometimes known “stable, soluble, ligand-binding form.” (where the terms “secreted” and “soluble” are synonymous and interchangeable herein) refer to proteins that are related to the native membrane bound form receptors, in such a way that they are secreted and stable and still capable of binding to the corresponding ligand. It should be noted that these forms are not defined by whether or not such secreted forms are physiological, only that the products of such splice variants would be secreted, stable, and still capable of ligand-binding when produced. [0046] The term “secreted” means that the form is soluble, i.e., that it is no longer bound to the cell membrane. In this context, a form will be soluble if using conventional assays known to one of skill in the art most of this form can be detected in fractions that are not associated with the membrane, e.g., in cellular supernatants or serum. [0047] The term “stable” means that the secreted form is detectable using conventional assays by one of skill in the art. For example, western blots, ELISA assays can be used to detect the form from harvested cells, cellular supernatants, or serum from patients. [0048] The term “ligand-binding” means that the form retains at least some significant level, although not necessarily all, of the specific ligand-binding activity of the corresponding integral membrane form. [0049] As used herein, the term “to reduce the activity of a ligand” refers to any action that leads to a decrease in transmission of an intracellular signal resulting from the ligand binding to or interaction with the receptor. For example, activity can be reduced by binding of the ligand to a soluble form of its receptor or by decreasing the quantity of the membrane form of its receptor available to bind the ligand. [0050] As used herein, the term “altering the splicing of a pre-mRNA” refers to altering the splicing of a cellular pre-mRNA target resulting in an altered ratio of splice products. Such an alteration of splicing can be detected by a variety of techniques well known to one of skill in the art. For example, RT-PCR on total cellular RNA can be used to detect the ratio of splice products in the presence and the absence of an SSO. [0051] As used herein, the term “complementary” is used to indicate a sufficient degree of complementarity or precise pairing such that stable and specific binding occurs between an SSO and a DNA or RNA containing the target sequence. It is understood in the art that the sequence of an SSO need not be 100% complementary to that of its target. There is a sufficient degree of complementarity when, under conditions which permit splicing, binding to the target will occur and non-specific binding will be avoided. [0052] The present invention employs splice switching oligonucleotides or splice switching oligomers (SSOs) to control the alternative splicing of receptors from the TNFR superfamily so that the amount of a soluble, stable, secreted, ligand-binding form is increased and the amount of the integral membrane form is decreased. The methods and compositions of the present invention can be used in the treatment of diseases associated with excessive TNF superfamily activity. [0053] Accordingly one embodiment of the invention is a method of treating an inflammatory disease or condition by administering SSOs to a patient. The SSOs that are administered alter the splicing of a pre-mRNA to produce a splice variant that encodes a stable, secreted, ligand-binding form of a receptor of the TNFR superfamily, thereby decreasing the activity of the ligand for that receptor. In another embodiment, the invention is a method of producing a stable, secreted, ligand-binding form of a receptor of the TNFR superfamily in a cell by administering SSOs to the cell. [0054] The following aspects of the present invention discussed below apply to the foregoing embodiments. [0055] The length of the SSO is similar to an antisense oligonucleotide (ASON), typically between about 10 and 24 nucleotides. The invention can be practiced with SSOs of several chemistries that hybridize to RNA, but that do not activate the destruction of the RNA by RNase H, as do conventional antisense 2′-deoxy oligonucleotides. The invention can be practiced using 2′O modified nucleic acid oligomers, such as 2′O-methyl or 2′O-methyloxyethyl phosphorothioate. The nucleobases do not need to be linked to sugars; so-called peptide nucleic acid oligomers or morpholine-based oligomers can be used. A comparison of these different linking chemistries is found in Sazani, P. et al., 2001, Nucleic Acids Res. 29:3695. The term splice-switching oligonucleotide is intended to cover the above forms. Those skilled in the art will appreciate the relationship between antisense oligonucleotide gapmers and SSOs. Gapmers are ASON that contain an RNase H activating region (typically a 2′-deoxyribonucleoside phosphorothioate) which is flanked by non-activating nuclease resistant oligomers. In general, any chemistry suitable for the flanking sequences in a gapmer ASON can be used in an SSO. [0056] The SSOs of this invention may be made through the well-known technique of solid phase synthesis. Any other means for such synthesis known in the art may additionally or alternatively be used. It is well known to use similar techniques to prepare oligonucleotides such as the phosphorothioates and alkylated derivatives. [0057] A particularly preferred chemistry is provided by locked nucleic acids (LNA) (Koshkin, A. A., et al., 1998, Tetrahedron 54:3607; Obika, S., et al., 1998, Tetrahedron Lett. 39:5401). LNA are conventional phosphodiester-linked ribonucleotides, except the ribofuranosyl moiety is made bicyclic by a bridge between the 2′O and the 4′C. This bridge constrains the conformation of ribofuranosyl ring into the conformation, the 3′-endo conformation, which is adopted when a oligonucleotide hybridizes to a complementary RNA. Recent advances in the synthesis of LNA are described in WO 03/095467. The bridge is most typically a methylene or an ethylene. The synthesis of 2′O,4′C-ethylene-bridged nucleic acids (ENA), as well as other LNA, is described in Morita, et al., 2003, Bioorg. & Med. Chem. 11:2211. However, alternative chemistries can be used and the 2′O may be replaced by a 2′N. LNA and conventional nucleotides can be mixed to form a chimeric SSO. For example, chimeric SSO of alternating LNA and 2′deoxynucleotides or alternating LNA and 2′O-Me or 2′O-MOE can be employed. An alternative to any of these chemistries, not merely the 2′-deoxynucleotides, is a phosphorothioatediester linkage replacing phosphodiester. For in vivo use, phosphorothioate linkages are preferred. [0058] When LNA nucleotides are employed in an SSO it is preferred that non-LNA nucleotides also be present. LNA nucleotides have such high affinities of hybridization that there can be significant non-specific binding, which may reduce the effective concentration of the free-SSO. When LNA nucleotides are used they may be alternated conveniently with 2′-deoxynucleotides. The pattern of alternation is not critical. Alternating nucleotides, alternating dinucleotides or mixed patterns, e.g., LDLDLD or LLDLLD or LDDLDD can be used. When 2′-deoxynucleotides or 2′-deoxynucleoside phosphorothioates are mixed with LNA nucleotides it is important to avoid RNase H activation. It is expected that between about one third and two thirds of the LNA nucleotides of an SSO will be suitable. For example if the SSO is a 12-mer, then at least four LNA nucleotides and four conventional nucleotides will be present. [0059] The bases of the SSO may be the conventional cytosine, guanine, adenine and uracil or thymidine. Alternatively modified bases can also be used. Of particular interest are modified bases that increase binding affinity. One non-limiting example of preferred modified bases are the so-called G-clamp or 9-(aminoethoxy)phenoxazine nucleotides, cytosine analogs that form 4 hydrogen bonds with guanosine. (Flanagan, W. M., et al., 1999, Proc. Natl. Acad. Sci. 96:3513; Holmes, S.C., 2003, Nucleic Acids Res. 31:2759). [0060] Numerous alternative chemistries which do not activate RNase H are available. For example, suitable SSOs may be oligonucleotides wherein at least one, or all, of the internucleotide bridging phosphate residues are modified phosphates, such as methyl phosphonates, methyl phosphonothioates, phosphoromorpholidates, phosphoropiperazidates, and phosphoroamidates. For example, every other one of the internucleotide bridging phosphate residues may be modified as described. In another non-limiting example, such SSO are oligonucleotides wherein at least one, or all, of the nucleotides contain a 2′ loweralkyl moiety (e.g., C1-C4, linear or branched, saturated or unsaturated alkyl, such as methyl, ethyl, ethenyl, propyl, 1-propenyl, 2-propenyl, and isopropyl). For example, every other one of the nucleotides may be modified as described. [See references in U.S. Pat. No. 5,976,879 col. 4]. [0061] The length of the SSO (i.e. the number of monomers in the oligomer) will be from about 10 to about 30 bases in length. In one embodiment, 20 bases of 2′O-Me-ribonucleosides phosphorothioates are effective. Those skilled in the art appreciate that when affinity-increasing chemical modifications are used, the SSO can be shorter and still retain specificity. Those skilled in the art will further appreciate that an upper limit on the size of the SSO is imposed by the need to maintain specific recognition of the target sequence, and to avoid secondary-structure forming self hybridization of the SSO and by the limitations of gaining cell entry. These limitations imply that an SSO of increasing length (above and beyond a certain length which will depend on the affinity of the SSO) will be more frequently found to be less specific, inactive or poorly active. [0062] SSOs of the invention include, but are not limited to, modifications of the SSO involving chemically linking to the SSO one or more moieties or conjugates which enhance the activity, cellular distribution or cellular uptake of the SSO. Such moieties include, but are not limited to, lipid moieties such as a cholesterol moiety, cholic acid, a thioether, e.g. hexyl-S-tritylthiol, a thiocholesterol, an aliphatic chain, e.g., dodecandiol or undecyl residues, a phospholipids, e.g., di-hexadecyl-rac-glycerol or triethylammonium 1,2-di-O-hexadecyl-rac-glycero-3-H-phosphonate, a polyamine or a polyethylene glycol chain, an adamantane acetic acid, a palmityl moiety, an octadecylamine or hexylamino-carbonyl-oxycholesterol moiety. [0063] It is not necessary for all positions in a given SSO to be uniformly modified, and in fact more than one of the aforementioned modifications may be incorporated in a single compound or even at a single nucleoside within an SSO. [0064] The SSOs may be admixed, encapsulated, conjugated, or otherwise associated with other molecules, molecule structures, or mixtures of compounds, as for example liposomes, receptor targeted molecules, oral, rectal, topical or other formulation, for assisting in uptake, distribution, and/or absorption. [0065] Those skilled in the art appreciate that cellular differentiation includes, but is not limited to, differentiation of the spliceosome. Accordingly, the activity of any particular SSO of the invention can depend upon the cell type into which they are introduced. For example, SSOs which are effective in cell type may be ineffective in another cell type. [0066] The methods, oligonucleotides, and formulations of the present invention are also useful as in vitro or in vivo tools to examine splicing in human or animal genes. Such methods can be carried out by the procedures described herein, or modifications thereof which will be apparent to skilled persons. [0067] The invention can be used to treat any condition in which the medical practitioner intends to limit the effect of a TNF superfamily ligand or the signalling pathway activated by such ligand. In particular, the invention can be used to treat an inflammatory disease. In one embodiment, the condition is an inflammatory systemic disease, e.g., rheumatoid arthritis or psoriatic arthritis. In another embodiment, the disease is an inflammatory liver disease. Examples of inflammatory liver diseases include, but are not limited to, hepatitis associated with the hepatitis A, B, or C viruses, alcoholic liver disease, and non-alcoholic steatosis. In yet another embodiment, the inflammatory disease is a skin condition such as psoriasis. [0068] The uses of the present invention include, but are not limited to, treatment of diseases for which known TNF antagonists have been shown useful. Three specific TNF antagonists are currently FDA-approved. The drugs are etanercept (Enbrel®), infliximab (Remicade®) and adalimumab (Humira®). One or more of these drugs is approved for the treatment of rheumatoid arthritis, juvenile rheumatoid arthritis, psoriasis, psotiatic arthritis, ankylosing spondylitis, and inflammatory bowel disease (Crohn's disease or ulcerative colitis). [0069] In a preferred embodiment, the receptor is either the TNFR1 or TNFR2 receptors. In other embodiments, the receptor is a member of the TNFR superfamily that is sufficiently homologous to TNFR1 and TNFR2, e.g., TNFRSF3, TNFRSF5, or TNFRSF11A, so that deletion of either or both exons homologous to exons 7 and 8 results in a secreted form. Those skilled in the art appreciate that the operability of the invention is not determined by whether or not such secreted forms are physiological, only that the products of such splice variants are secreted, stable, and capable of ligand-binding. [0070] The administration of the SSO to subjects can be accomplished using procedures developed for ASON. ASON have been successfully administered to experimental animals and human subjects by intravenous administration in saline in doses as high as 6 mg/kg three times a week (Yacysyhn, B. R., et al., 2002, Gut 51:30 (anti-ICAM-1 ASON for treatment of Crohn's disease); Stevenson, J., et al., 1999, J. Clinical Oncology 17:2227 (anti-RAF-1 ASON targeted to PBMC)). The pharmacokinetics of 2′O-MOE phosphorothioate ASON, directed towards TNF-α has been reported (Geary, R. S., et al., 2003, Drug Metabolism and Disposition 31:1419). The systemic efficacy of mixed LNA/DNA molecules has also been reported (Fluiter, K., et al., 2003, Nucleic Acids Res. 31:953). [0071] The systemic activity of SSO in a mouse model system was investigated using 2′O-MOE phosphorothioates and PNA chemistries. Significant activity was observed in all tissues investigated except brain, stomach and dermis (Sazani, P., et al., 2002, Nature Biotechnology 20, 1228). [0072] In general any method of administration that is useful in conventional antisense treatments can be used to administer the SSO of the invention. For testing of the SSO in cultured cells, any of the techniques that have been developed to test ASON or SSO may be used. [0073] Formulations of the present invention comprise SSOs in a physiologically or pharmaceutically acceptable carrier, such as an aqueous carrier. Thus formulations for use in the present invention include, but are not limited to, those suitable for parenteral administration including intraperitoneal, intravenous, intraarterial, subcutaneous, or intramuscular injection or infusion, as well as those suitable topical (including ophthalmic and to mucous membranes including vaginal delivery), oral, rectal or pulmonary (including inhalation or insufflation of powders or aerosols, including by nebulizer, intratracheal, intranasal delivery) administration. The formulations may conveniently be presented in unit dosage form and may be prepared by any of the methods well known in the art. The most suitable route of administration in any given case may depend upon the subject, the nature and severity of the condition being treated, and the particular active compound which is being used. [0074] Pharmaceutical compositions of the present invention include, but are not limited to, the physiologically and pharmaceutically acceptable salts thereof: i.e, salts that retain the desired biological activity of the parent compound and do not impart undesired toxicological effects thereto. Examples of such salts are (a) salts formed with cations such as sodium, potassium, NH 4 + , magnesium, calcium, polyamines such as spermine and spermidine, etc.; (b) acid addition salts formed with inorganic acids, for example, hydrochloric acid, hydrobromic acid, sulfuric acid, phosphoric acid, nitric acid and the like; (c) salts formed with organic acids such as, for example, acetic acid, oxalic acid, tartaric acid, succinic acid, maleic acid, fumaric acid, gluconic acid, citric acid, malic acid, ascorbic acid, benzoic acid, tannic acid, palmitic acid, alginic acid, polyglutamic acid, napthalenesulfonic acid, methanesulfonic acid, p-toluenesulfonic acid, napthalenedisulfonic acid, polygalacturonic acid, and the like; and (d) salts formed from elemental anions such as chlorine, bromine, and iodine. [0075] The present invention provides for the use of SSOs having the characteristics set forth above for the preparation of a medicament for increasing the ratio of a soluble form of a TNFR superfamily member to its corresponding membrane bound form, in a patient afflicted with an inflammatory disorder involving excessive activity of a cytokine, such as TNF-α, as discussed above. In the manufacture of a medicament according to the invention, the SSOs are typically admixed with, inter alia, an acceptable carrier. The carrier must, of course, be acceptable in the sense of being compatible with any other ingredients in the formulation and must not be deleterious to the patient. The carrier may be a solid or liquid. SSOs are incorporated in the formulations of the invention, which may be prepared by any of the well known techniques of pharmacy consisting essentially of admixing the components, optionally including one or more accessory therapeutic ingredients. [0076] Formulations of the present invention may comprise sterile aqueous and non-aqueous injection solutions of the active compounds, which preparations are preferably isotonic with the blood of the intended recipient and essentially pyrogen free. These preparations may contain anti-oxidants, buffers, bacteriostats, and solutes which render the formulation isotonic with the blood of the intended recipient. Aqueous and non-aqueous sterile suspensions can include, but are not limited to, suspending agents and thickening agents. The formulations may be presented in unit dose or multi-dose containers, for example, sealed ampoules and vials, and may be stored in freeze-dried (lyophilized) condition requiring only the addition of the sterile liquid carrier, for example, saline or water-for-injection immediately prior to use. [0077] In the formulation the SSOs may be contained within a lipid particle or vesicle, such as a liposome or microcrystal, which may be suitable for parenteral administration. The particles may be of any suitable structure, such as unilamellar or plurilameller, so long as the SSOs are contained therein. Positively charged lipids such as N-[1-(2,3-dioleoyloxi)propyl]-N,N,N-trimethyl-ammoniummethylsulfate, or “DOTAP,” are particularly preferred for such particles and vesicles. The preparation of such lipid particles is well known. [See references in U.S. Pat. No. 5,976,879 col. 6] [0078] The SSO can be targeted to any element or combination of elements that regulate splicing, including the 3′splice site, the 5′ splice site, the branch point, the polypyrimidine tract, exonic splicing ehancers, exonic splicing silencers, intronic splicing enhancers, and intronic splicing silencers. The determination of the sequence of the SSO can be guided by the following tables that shows the activities of the SSOs whose sequences and locations are found as depicted in FIGS. 4 , 5 , and 8 . The person skilled in the art will note that: 1) SSOs complementary to the exon need not be complementary to either the splice acceptor or splice donor sites, note SSOs A7-10, B7-7 and B7-9, Table 1; 2) SSOs complementary to sequences of the intron and as few as one nucleotide of the exon can be operative, note A8-5 and B7-6, Table 1; 3) SSOs complementary to the intron immediately adjacent to the exon can also be effective, note 3312, Table 2; and 4) efficacy of an oligonucleotide alone is usually predictive of the efficacy of the SSO in combination with other SSOs. [0079] Those skilled in the art can appreciate that the invention as directed toward human TNF-α receptors can be practiced using SSO having a sequence that is complementary to at least 10, preferably between 15 and 20 nucleotides of the portions of the TNFR1 or TNFR2 genes comprising exons 7 or 8 and their adjacent introns. It is further preferred that at least one nucleotide of the exon itself is included within the complementary sequence. SEQ ID Nos: 1-4 contain the sequence of Exons 7 and 8 of the TNFR1 (SEQ ID Nos: 1 and 2) and TNFR2 (SEQ ID Nos: 3 and 4) and 50 adjacent nucleotides of the flanking introns. When affinity-enhancing modifications are used, including but not limited to LNA or G-clamp nucleotides, the skilled person recognizes the length of the SSO can be correspondingly reduced. When alternating conventional and LNA nucleotides are used a length of 16 is effective. The pattern of alternation of LNA and conventional nucleotides is not important. [0080] Those skilled in the art will also recognize that the selection of SSO sequences must be made with care to avoid self-complementary SSO, which may lead to the formation of partial “hairpin” duplex structures. In addition, high GC content should be avoided to minimize the possibility of non-specific base pairing. Furthermore, SSOs matching off-target genes, as revealed for example by BLAST, should also be avoided. [0081] In some situations, it may be preferred to select an SSO sequence that can target a human and at least one other species. These SSOs can be used to test and to optimize the invention in said other species before being used in humans, thereby being useful for regulatory approval and drug development purposes. For example, SEQ ID Nos: 74, 75, 77, 78, 80, and 89, which target human TNFR2 are also 100% complementary to the corresponding Macaca Mullata sequences. As a result these sequences can be used to test treatments in monkeys, before being used in humans. [0082] It will be appreciated by those skilled in the art that various omissions, additions and modifications may be made to the invention described above without departing from the scope of the invention, and all such modifications and changes are intended to fall within the scope of the invention, as defined by the appended claims. All references, patents, patent applications or other documents cited are herein incorporated by reference. Example 1 Materials and Methods [0083] Oligonucleotides. [0084] All uniformly modified 2′-O-methyl-ribonucleoside-phosphorothioate (2′-OMe) 20-mers were synthesized by Trilink Biotechnologies, San Diego, Calif. Their sequences are listed in Table 1. Tables 2 and 3 show the sequences of chimeric LNA SSOs with alternating 2′deoxy- and 2′O-4′-(methylene)-bicyclic-ribonucleoside phosphorothioates. These were synthesized by Santaris Pharma, Denmark. For each LNA oligonucleotide, the 5′-terminal nucleoside was a 2′O-4′-methylene-ribonucleoside and the 3′-terminal ribonucleoside was a 2′deoxy-ribonucleoside. [0085] Cell Culture and Transfections. [0086] NIH-3T3 cells were maintained (37° C., 5% CO 2 ) in Dulbecco's modified Eagle's media (DMEM) supplemented with 10% Colorado fetal calf serum and antibiotic. L929 cells were maintained (37° C., 5% CO 2 ) in minimal essential media supplemented with 10% fetal bovine serum and antibiotic. For transfection, either NIH-3T3 or L929 cells were seeded in 24-well plates at 10 5 cells per well and transfected 24 hours later. Oligonucleotides were complexed, at the indicated concentrations, with 2 L of Lipofectamine™2000 transfection reagent (Invitrogen) as per the manufacturer's directions. The nucleotide/lipid complexes were then applied to the cells and incubated for hours. The media was then aspirated and cells harvested with TRI-Reagent™ (MRC, Cincinnati, Ohio). [0087] RT-PCR. [0088] Total RNA was isolated with TRI-Reagent (MRC, Cincinnati, Ohio) and TNFR1 or TNFR2 mRNA was amplified by RT-PCR using rTth polymerase (Applied Biosystems) following supplier directions. Murine TNFR1 mRNA was amplified using forward primer PS009 (SEQ ID No: 111) (5′-GAA AGT GAG TGC GTC CCT TGC-3′) and reverse primer PS010 (SEQ ID No: 112) (5′-GCA CGG AGC AGA GTG ATT CG-3′). Murine TNFR2 mRNA was amplified using forward primer PS003 (SEQ ID No: 113) (5′-GAG CCC CAA ATG GAA ATG TGC-3′) and reverse primer PS004 (SEQ ID No: 114) (5′-GCT CAA GGC CTA CTG CC-3′). Human TNFR2 mRNA was amplified using forward primer (SEQ ID No: 115) (5′-ACT GAA ACA TCA GAC GTG GTG TGC-3′) and reverse primer (SEQ ID No: 116) (5′-CCT TAT CGG CAG GCA AGT GAG-3′). A Cy5-labeled dCTP (GE Healthcare) was included in the PCR step for visualization (0.1 μL per 50 μL PCR reaction). Cycles of PCR proceeded: 95° C., 60 sec; 56° C., 30 sec; 72° C., 60 sec for 22 cycles total. The PCR products were separated on a 10% non-denaturing polyacrylamide gel, and Cy5-labeled bands were visualized with a Typhoon™ 9400 Scanner (GE Healthcare). Scans were quantified with ImageQuant™ (GE Healthcare) software. [0089] Mouse hepatocyte cultures. For hepatocyte collection, livers of mice were perfused with RPMI medium containing 0.53 mg/ml of collagenase (Worthington Type 1, code CLS). After perfusion, the cell suspension was collected and seeded in a stop solution of RPMI with 10% (vol/vol) FBS and 0.5% penicillin-streptomycin plus 1 nM insulin and 13 nM dexamethasone. Approximately 3×10 5 cells were seeded on a six-well collagen-coated plate. The seeding medium was replaced 1 hour later with maintenance medium consisting of seeding medium without the 10% (vol/vol) FBS. Varying amounts of oligonucleotide-lipid complexes were applied 24 hours later. Cells were lysed 24 hours after transfection with TRI-Reagent™. [0090] Human Hepatocyte Cultures. [0091] Human hepatocytes were obtained in suspension either from ADMET technologies, or from The UNC Cellular Metabolism and Transport Core at UNC-Chapel Hill. Cells were washed and suspended in RPMI 1640 supplemented with 10% FBS, 1 μg/mL human insulin, and 13 nM Dexamethasone. Hepatocytes were plated in 6-well plates at 0.5×10 6 cells per plate in 3 mL media. After 1-1.5 hours, non-adherent cells were removed, and the media was replaced with RPMI 1640 without FBS, supplemented with 1 g/mL human insulin, and 130 nM Dexamethasone. [0092] For delivery of LNA SSOs to hepatocytes in 6-well plates, 10 μL of a 5 M LNA stock was diluted into 100 μL of OPTI-MEM™, and 4 μL of Lipofectamine™ 2000 was diluted into 100 μL of OPTI-MEM™. The 200 μL complex solution was then applied to the cells in the 6-well plate containing 2800 μL of media, for a total of 3000 μL. The final LNA concentration was 17 nM. After 24 hours, cells were harvested in TRI-Reagent™. Total RNA was isolated per the manufacturers directions. Approximately 200 ng of total RNA was subjected to reverse transcription-PCR (RT-PCR). [0093] ELISA. To determine the levels of soluble TNFR2 in cell culture media or mouse sera, the Quantikine® Mouse sTNF RII ELISA kit from R&D Systems (Minneapolis, Minn.) was used. To determine the levels of soluble TNFR1 in cell culture media or mouse sera, the Quantikine® Mouse sTNF RI ELISA kit from R&D Systems (Minneapolis, Minn.) was used. Note, the antibodies used for detection also detect the protease cleavage forms of the receptor. [0094] For cell culture studies, extracellular media was collected at 72 hours post transfection. The assay was performed according to the manufacturer's guide, using 50 μL of undiluted media. The assay readings were performed using a microplate reader set at 450 nm, with wavelength correction set at 570 nm. [0095] For mouse in vivo studies, blood from the animals was clotted for 1 hour at 37° C. and centrifuged for 10 min at 14,000 rpm (Jouan BRA4i centrifuge). Sera was collected and assayed according to the manufacturer's guide, using 50 μL of mouse sera, diluted 1:10. The assay readings were performed using a microplate reader set at 450 nm, with wavelength correction set at 570 nm. [0096] L929 Cytotoxicity Assay. [0097] L929 cells plated in 96-well plates at 10 4 cells per plate were treated with 0.1 ng/mL TNF-α (TNF) and actinomycin D (ActD) in the presence of 10% serum from mice treated with the indicated oligonucleotide in 100 μL total cell culture media. Control lanes were plated in 10% serum from untreated mice. 24 hours later, cell viability was measured by adding 20 μL CellTiter 96® Aqueous Solution (Promega) and measuring absorbance at 490 nm with a microplate reader. Cell viability was normalized to cells untreated with TNF/ActD. Example 2 Testing of SSOs for Splice Switching Activity [0098] SSOs were synthesized, transfected into either NIH-3T3 or L929 cells. Total RNA from the cells was analyzed by RT-PCR to assess the splice switching ability of the SSO. Table 1 contains the sequences and the splice switching activities of 20 nucleotide 2′O-Me-ribonucleoside-phosphorothioate murine SSOs. Table 2 contains the sequences and the splice switching activities of 16 nucleotide chimeric LNA murine SSOs. Table 3 contains the sequences and the splice switching activities of 16 nucleotide chimeric LNA human SSOs. Each table also lists the target site for each SSO by complementary regions and number of nucleotides; e.g., I6:E7(8:8) means complementary to the 3′-most 8 nucleotides of intron 6 and the 5′-most 8 nucleotides of exon 7; E7(16) means complementary to 16 nucleotides in exon 7; and E8:I8(7:9) means complementary to the 3′-most 7 nucleotides of exon 8 and the 5′-most 9 nucleotides of intron 8. [0000] TABLE 1 2′O—Me-ribonucleoside-phosphorothioate mouse targeted SSO SEQ ID. Name* Sequence (5′-3′) Activity Target Site  5 A7-1 CCG CAG UAC CUG CAG ACC AG − I6:E7(6:14)  6 A7-2 GUA CCU GCA GAC CAG AGA GG − I6:E7(13:7)  7 A7-3 CUG CAG ACC AGA GAG GUU GC − I6:E7(18:2)  8 A7-4 ACU GAU GGA GUA GAC UUC GG + E7:I7(18:2)  9 A7-5 AGU CCU ACU UAC UGA UGG AG + E7:I7(8:12) 10 A7-6 CCA AAG UCC UAC UUA CUG AU − E7:I7(1:19) 11 A7-7 AGA UAA CCA GGG GCA ACA GC − E7(20) 12 A7-8 AGG AUA GAA GGC AAA GAC CU − E7(20) 13 A7-9 GGC ACA UUA AAC UGA UGA AG − E7(20) 14 A7-10 GGC CUC CAC CGG GGA UAU CG + E7(20) 15 A8-1 CUG GAG AAC AAA GAA ACA AG − I7:E8(19:1) 16 A8-2 AUC CCU ACA AAC UGG AGA AC − I7:E8(8:12) 17 A8-3 GGC ACG GGA UCC CUA CAA AC ++ E8(20) 18 A8-4 CUU CUC ACC UCU UUG ACA GG ++ E8:I8(12:8) 19 A8-5 UGG AGU CGU CCC UUC UCA CC + E8:18(1:19) 20 B7-1 CUC CAA CAA UCA GAC CUA GG +++ I6:E7(5:15) 21 B7-2 CAA UCA GAC CUA GGA AAA CG + I6:E7(11:9) 22 B7-3 AGA CCU AGG AAA ACG GCA GG − I6:E7(16:4) 23 B7-4 CCU UAC UUU UCC UCU GCA CC − E7:I8(14:6) 24 B7-5 GAG CAG AAC CUU ACU UUU CC ++ E7:I8(6:14) 25 B7-6 GAC GAG AGC AGA ACC UUA CU ++ E7:I7(1:19) 26 B7-7 UCA GCA GAC CCA GUG AUG UC ++ E7(20) 27 B7-8 AUG AUG CAG UUC ACC AGU CC + E7(20) 28 B7-9 UCA CCA GUC CUA ACA UCA GC ++ E7(20) 29 B7-10 CCU CUG CAC CAG GAU GAU GC ++ E7(20) 30 B8-1 UUC UCU ACA AUG AAG AGA GG − I7:E8(16:4) 31 B8-2 GGC UUC UCU ACA AUG AAG AG − I7:E8(13:7) 32 B8-3 UGU AGG CAG GAG GGC UUC UC ++ I7:E8(1:19) 33 B8-4 ACU CAC CAC CUU GGC AUC UC ++ E8:I8(14:6) 34 B8-5 GCA GAG GGA UAC UCA CCA CC − E8:I8(4:16) *SSOs with the prefix “A” are directed to TNFR1 and with “B” to TNFR2. [0000] TABLE 2 LNA-2′deoxy-ribonucleosidephosphorothioate chimeric mouse targeted SSO SEQ ID. Name Sequence 5′ to 3′ Activity Target Site TNFR2 Exon 7 35 3272 CAA TCA GAC CTA GGA A − I6:E7(7:9) 36 3303 CAA CAA TCA GAC CTA G − I6:E7(4:12) 37 3304 CAG ACC TAG GAA AAC G − I6:E7(11:5) 38 3305 AGC AGA CCC AGT GAT G ++ E7(16) 39 3306 CCA GTC CTA ACA TCA G + E7(16) 40 3307 CAC CAG TCC TAA CAT C + E7(16) 41 3308 CTG CAC CAG GAT GAT G + E7(16) 42 3309 ACT TTT CCT CTG CAC C + E7:I7(14:2) 43 3310 CCT TAC TTT TCC TCT G − E7:I7(8:8) 44 3311 CAG AAC CTT ACT TTT C ++ E7:I7(5:11) 45 3274 AGA GCA GAA CCT TAC T ++ E7:I7(1:15) 46 3312 GAG AGC AGA ACC TTA C ++ E7:I7(0:16) 47 3273 ACC TTA CTT TTC CTC T − E7:I7(9:7) TNFR2 Exon 8 48 3313 CTT CTC TAC AAT GAA G − I7:E8(11:5) 49 3314 CCT TGG CAT CTC TTT G − E8(16) 50 3315 TCA CCA CCT TGG CAT C + E8:I8(12:4) 51 3316 ACT CAC CAC CTT GGC A + E8:I8(10:6) 52 3317 GAT ACT CAC CAC CTT G + E8:I8(7:9) 53 3631 CTA CAA TGA AGA GAG G − I7(16) 54 3632 CTC TAC AAT GAA GAG A − I7:E8(14:2) 55 3633 AGG GAT ACT CAC CAC C + E8:I8(4:12) 56 3634 CAG AGG GAT ACT CAC C + E8:I8(1:15) 57 3635 CGC AGA GGG ATA CTC A + I8(16) 58 3636 GAA CAA GTC AGA GGC A − I7(16) 59 3637 GAG GCA GGA CTT CTT C − I7(16) TNFR1 Exon 7 60 3325 CGC AGT ACC TGC AGA C + I6:E7(8:8) 61 3326 AGT ACC TGC AGA CCA G − I6:E7(11:5) 62 3327 GGC AAC AGC ACC GCA G − E7(16) 63 3328 CTA GCA AGA TAA CCA G − E7(16) 64 3329 GCA CAT TAA ACT GAT G − E7(16) 65 3330 CTT CGG GCC TCC ACC G − E7(16) 66 3331 CTT ACT GAT GGA GTA G − E7:I7(11:5) 67 3332 CCT ACT TAC TGA TGG A − E7:I7(7:9) 68 3333 GTC CTA CTT ACT GAT G + E7:I7(5:11) TNFR1 Exon 8 69 3334 TCC CTA CAA ACT GGA G + E7:I7(5:11) 70 3335 GGC ACG GGA TCC CTA C + E8(16) 71 3336 CTC TTT GAC AGG CAC G + E8(16) 72 3337 CTC ACC TCT TTG ACA G − E8:I8(11:5) 73 3338 CCT TCT CAC CTC TTT G − E8:I8(7:9) [0000] TABLE 3 LNA-2′deoxy-ribonucleosidephosphorothioate chimeric human targeted SSO SEQ ID. Name Sequence 5′ to 3′ Activity Target Site TNFR2 Exon 7 74 3378 CCA CAA TCA GTC CTA G ++ I6:E7(4:12) 75 3379 CAG TCC TAG AAA GAA A ++ I6:E7(11:5) 76 3380 AGT AGA CCC AAG GCT G − E7(16) 77 3381 CCA CTC CTA TTA TTA G + E7(16) 78 3382 CAC CAC TCC TAT TAT T + E7(16) 79 3383 CTG GGT CAT GAT GAC A − E7(16) 80 3384 ACT TTT CAC CTG GGT C ++ E7:I7(14:2) 81 3385 TCT TAC TTT TCA CCT G − E7:I7(10:6) 82 3459 TGG ACT CTT ACT TTT C ++ E7:I7(5:11) 83 3460 AGG ATG GAC TCT TAC T − E7:I7(1:15) 84 3461 AAG GAT GGA CTC TTA C + I7(16) TNFR2 Exon 8 85 3462 CTT CTC TAT AAA GAG G − I7:E8(11:5) 86 3463 CCT TGG CTT CTC TCT G + E8(16) 87 3464 TCA CCA CCT TGG CTT C + E8:I8(12:4) 88 3465 ACT CAC CAC CTT GGC T + E8:I8(10:6) 89 3466 GAC ACT CAC CAC CTT G + E8:I8(7:9) TNFR1 Exon 7 90 3478 TGT GGT GCC TGC AGA C N/A I6:E7(8:8) 91 3479 GGT GCC TGC AGA CAA A N/A I6:E7(11:5) 92 3480 GGC AAC AGC ACT GTG G N/A E7(16) 93 3481 CAA AGA AAA TGA CCA G N/A E7(16) 94 3482 ATA CAT TAA ACC AAT G N/A E7(16) 95 3483 GCT TGG ACT TCC ACC G N/A E7(16) 96 3484 CTC ACC AAT GGA GTA G N/A E7:I7(11:5) 97 3485 CAC TCA CCA ATG GAG T N/A E7:I7(9:7) 98 3587 CCC ACT CAC CAA TGG A N/A E7:I7(7:9) 99 3588 CCC CCA CTC ACC AAT G N/A E7:I7(5:11) 100  3589 AAA GCC CCC ACT CAC C N/A E7:I7(1:15) TNFR1 Exon 8 101  3590 TTT CCC ACA AAC TGA G N/A I7:E8(5:11) 102  3591 GGT GTC GAT TTC CCA C N/A E8(16) 103  3592 CTC TTT TTC AGG TGT C N/A E8(16) 104  3593 CTC ACC TCT TTT TCA G N/A E8:I8(11:5) 105  3594 TCA TCT CAC CTC TTT T N/A E8:I8(7:9) Control 106  3083 GCT ATT ACC TTA ACC C N/A N/A Example 3 Effect of SSOs on L929 Mouse Cells [0099] Single LNA SSOs were transfected into L929 murine cells and analyzed for splice switching of TNFR2. FIG. 9 (top) shows the splice switching results of LNAs targeted towards mouse exon 7. Of the LNAs tested, at least 9 showed some activity. In particular, LNA 3312, 3274 and 3305 induced skipping of exon 7 to 50% or greater; LNA 3305 treatment resulted in almost complete skipping. FIG. 9 (bottom) shows the activity of SSOs targeted towards mouse exon 8. The data indicate that LNA 3315 and 3316 are equally potent at inducing an approximately 20% skipping of exon 8. Note that exon 8 is small (35 nts), and therefore the difference in exon 8-containing and exon 8-lacking PCR fragments is also small. Example 4 Effect of Multiple SSOs on L929 Mouse Cells [0100] LNA SSOs targeting exon 7 and 8 were transfected in combination into L929 cells to determine whether such treatment would result in generation of TNFR2 Δ7/8 mRNA. The data in FIG. 10 show that the combination of exon 8 targeted 3315 or 3316 with one of exon 7 targeted LNA 3305, 3309, 3312, or 3274 induced skipping of both exons simultaneously. In particular, the combination of LNAs 3305 and 3315 resulted in greater than 60% shift to the Δ7/8 mRNA, with the remainder being almost entirely Δ7 mRNA. Other combinations were also effective; 3274 with 3315 led to a 50% shift to the Δ7/8 mRNA. These data indicate that LNA SSOs are very effective at inducing alternatively spliced TNFR2 mRNAs. Similarly, combinations of LNA SSOs targeted to TNFR1 exon 7 and 8 also induced shifting of their respective exons in L929 cells ( FIG. 11 ). Example 5 Effect of LNA SSOs on Primary Mouse Hepatocytes [0101] The TNFR2 LNA SSOs were transfected into primary mouse hepatocytes, and were found to be equally effective in splice switching in these cells. In particular, treatment with LNA 3274 or 3305 in combination with LNA 3315 showed splice shifting profiles very similar to those found in L929 cells ( FIG. 12 ). These data confirm splice shifting occurs in intended in vivo cellular targets. Example 6 Secretion of TNFR2 Splice Variants from Murine Cells [0102] The ability of LNA SSOs to induce soluble TNFR2 protein production and secretion into the extracellular media was tested. L929 cells were treated with the LNA SSOs as above, and extracellular media samples were collected 48 hours after transfection. The samples were quantified by an ELISA specific for soluble TNFR2 (for either Δ7 and Δ7/8 protein isoforms). The FIG. 13 left panel indicates that the LNAs that best induced shifts in RNA splicing, also secreted the most protein into the extracellular media. In particular, LNAs 3305, 3312 and 3274 performed best, increasing soluble TNFR2 at least 3.5-fold over background, and yielding 250 pg/mL soluble splice variant. Increases were also seen in similarly treated primary mouse hepatocytes ( FIG. 13 , right panel). In these primary cells, treatment with LNA 3274 or 3305 alone gave approximately 2.5-fold increases in soluble TNFR2 in the extracellular media, yielding ˜200 μg/mL of the soluble splice variant, and the combination of 3274 or 3305 with 3315 also increased protein production. Consequently, induction of the splice variant mRNA correlated with production and secretion of the soluble TNFR2. Example 7 Effect of LNA SSOs on Primary Human Hepatocytes [0103] LNA SSOs for human TNFR2 pre-mRNA were transfected into cultured primary human hepatocytes. FIG. 14 shows that 7 of 10 SSOs targeted to exon 7 exhibited some splice switching activity. In particular, LNAs 3378, 3384 and 3479 showed at least 75% skipping of exon 7. Likewise, 4 of the 5 exon 8 targeted SSOs showed activity. Interestingly, LNAs 3464, 3465, or 3466 alone was sufficient to induce Δ7/8 splice removal, an observation not seen in mouse cells. Hence, only one SSO may be required to induce skipping of both exon 7 and exon 8. These data confirm splice shifting occurs in intended human therapeutic targets. Example 8 In Vivo Injection of LNA SSOs in Mice [0104] LNA 3305, at doses from 3 mg/kg to 25 mg/kg diluted in saline only, were injected intraperitoneal (i.p.) once a day for 4 days into mice. The mice were sacrificed on day 5 and total RNA from the liver was analyzed by RT-PCR. The data show splice switching efficacy similar to that found in cell culture. At the maximum dose of 25 mg/kg, LNA 3305 induced almost full conversion to Δ7 mRNA ( FIG. 15 , bottom panel). [0105] A similar procedure using LNA 3274 induced about 20% conversion to Δ7 mRNA. To optimize the induction of Δ7 mRNA LNA 3274, both the dose regimen and time between the last injection, and sacrifice of the animals was varied. LNA 3274, at 25 mg/kg diluted in saline only, were injected (i.p.) once a day for 4 days into mice. In mice analyzed on day 15, whereas those analyzed on day five demonstrated only a 20% shift to Δ7 mRNA ( FIG. 15 , top panel). Furthermore, mice given injections for 10 days, and sacrificed on day 11 showed a 50% induction of Δ7 mRNA ( FIG. 15 top). These in vivo data suggest that TNFR2 LNA SSOs can persist in the liver and induce splice switching for at least 10 days after administration. Example 9 Circulatory TNFR Splice Variants [0106] Induction of the Δ7 mRNA in liver should produce soluble TNFR, which can be secreted and accumulate in the circulation. Accordingly, mice were treated with LNA 3274, 3305, or the control 3083 alone i.p. at 25 mg/kg/day for 10 days. Mice were bled before injection and again 1, 5 and 10 days after the last injection. Serum was quantified for concentration of soluble TNFR2. FIG. 16 shows that LNA treatment induced 6000-8000 μg/mL of soluble TNFR2 (Δ7), which was significantly over background for at least 10 days. [0107] The same samples were assayed for production of soluble TNFR1. No increase in soluble TNFR1 was observed ( FIG. 17 ). [0108] To test the effects at longer time points, the same experiment was carried out, and mice were analyzed for soluble TNFR2 in the serum up to 27 days after the last injection. The results show only a slight decrease in soluble TNFR2 levels 27 days after the last LNA SSO injection ( FIG. 18 ). This data suggests that the effects of the LNAs persist for at least 27 days. Example 10 Measurement of Anti-TNF-α Activity of Mice Treated with LNA SSOs [0109] The anti-TNF-α activity of serum from LNA 3274 treated mice was tested in an L929 cytotoxicity assay. In this assay, serum is tested for its ability to protect cultured L929 cells from the cytotoxic effects of a fixed concentration of TNF-α. L929 cells were seeded in 96-well plates at 2×10 4 cells per well in 100 μL of complete MEM media (containing 10% regular FBS) and allowed to grow for 24 hours at 37° C. As shown in FIG. 19 , serum from mice treated with LNA 3274 but not control LNAs (3083 or 3272) increased viability of the L929 cells exposed to 0.1 ng/mL TNF-α. Hence, the LNA 3274 serum contained Δ7 TNFR2 TNF-α antagonist, sufficient to bind and inactivate TNF-α, and thereby protect the cells from the cytotoxic effects of TNF-α. This anti-TNF-α activity was present in the serum of animals 5 and 27 days after the last injection of the 3274 LNA. Example 11 Comparison of LNA SSOs to Other Anti-TNF-α Agents [0110] L929 cells were seeded as in Example 10. Samples were prepared containing 90 L of serum-free MEM, 0.1 ng/ml TNF-α (TNF) and 1 μg/ml of actinomycin D (ActD), with either (i) rsTNFR2 (recombinant soluble) (0.01-3 μg/mL), (ii) serum from LNA 3274 treated mice (1.25-10%, diluted in serum from untreated mice) or (iii) Enbrel® (0.45-150 μg/ml) to a final volume of 100 μl with a final mouse serum concentration of 10%. The samples were incubated at room temperature for 30 minutes. Subsequently, the samples were applied to the plated cells and incubated for ˜24 hours at 37° C. in a 5% CO 2 humidified atmosphere. Cell viability was measured by adding 20 μL CellTiter 96® Aqueous Solution (Promega) and measuring absorbance at 490 nm with a microplate reader. Cell viability, as shown in FIG. 20 , was normalized to cells untreated with TNF/ActD.

Methods and compositions are disclosed for controlling expression of TNF receptors (TNFR1 and TNFR2) and of other receptors in the TNFR superfamily using compounds that modulate splicing of pre-mRNA encoding these receptors. More specifically these compounds cause the removal of the transmembrane domains of these receptors and produce soluble forms of the receptor which act as an antagonist to reduce TNF-α activity or activity of the relevant ligand. Reducing TNF-α activity provides a method of treating or ameliorating inflammatory diseases or conditions associated with TNF-α activity. Similarly, diseases associated with other ligands can be treated in like manner. In particular, the compounds of the invention are splice-splice switching oligomers (SSOs) which are small molecules that are stable in vivo, hybridize to the RNA in a sequence specific manner and, in conjunction with their target, are not degraded by RNAse H.

BACKGROUND OF THE INVENTION There are known mobile solar panels that are provided to supply current to garden lamps, where the garden lamps are designed in the form of battery-powered units that can be electrically connected to solar panels. The known solar panels are relatively bulky so that transporting and storing them is costly and awkward. SUMMARY OF THE INVENTION The current invention with the features of claim 1 has the advantage that a relatively large-area solar panel can be changed from the large-area, bulky dimensions of its functional position to a small packing size for transport or for a functional position with a minimal current efficiency, and is therefore particularly reliable and easy to maneuver and is also mobile. The fact that the solar panel is comprised of individual panels similar to fan slats that can be pivoted around a common pivot axis or opened up like a fan, and can be folded back into a compact position from the fanned-out position, results in a simply designed, rugged solar panel that can be quickly, easily, and reliably transported. The fact that the solar panel is supported in folding fashion on a base with an inclined surface makes it possible for the solar panel to be quickly, easily, and reliably brought into an optimal angular position in which the solar panel is oriented toward the sun so that the greatest possible electrical efficiency is assured. The fact that the solar panel is fastened to a podium-like housing that supports the solar panel on the front side that constitutes the top panel of the podium and has a handle on the back side makes the solar panel a compact, particularly convenient box that can be rapidly and reliably set up. The fact that the housing has a plug opening in back for the plug contact of a battery pack, in particular for electric tools, allows the box with the solar panel to be used in a particularly advantageous way as a mobile, solar-powered battery-charging station for operation on construction sites that do not have a high-voltage network. The fact that the housing is equipped with charging electronics on the inside that are connected to the electric plug contacts in the plug opening makes the battery-charging station particularly rugged and insensitive to shock and impact under rough transportation conditions and with hard construction site use. The fact that the housing has a charge control indicator assures it of functioning reliably as a battery-charging station. Because the solar cell plates, which are arranged in a stack, are electrically coupled to one another and to the electrical contacts of the plug opening by means of electrical sliding contact, the solar panel has an effective maximal size, which results from the sum of the individual surface areas of the opened up solar cell plates. The fact that the housing of the solar battery-charging station has ventilation slots prevents an overheating of the electric and electronic components contained inside, in particular the charging electronics, even at high outdoor temperatures. BRIEF DESCRIPTION OF THE DRAWINGS The current invention will be explained in detail below in conjunction with an exemplary embodiment and the accompanying drawings. FIG. 1 shows a three-dimensional side view of the solar battery-charging station, FIG. 2 shows the solar battery-charging station from the left, FIG. 3 shows the solar battery-charging station from behind, FIG. 4 shows the solar battery-charging station from underneath, and FIG. 5 shows the front view of the solar battery-charging station, with the solar cell plates spread out in the shape of a fan. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a three-dimensional view of the solar battery-charging station, with a stack 16 of solar cell plates 20 folded into the compact position, the uppermost solar cell plate of which is exposed, can be activated by light, and, like the remaining solar cell plates, is supported so that it can pivot around a swivel pin 22 . The individual solar cell plates 20 can be moved independently of on another around the swivel pin 22 , but are electrically connected to one another. They have identical dimensions and are sized so that after being spread out by pivoting around the swivel pin 22 in the manner shown in FIG. 5 , they form a semicircular solar panel surface, which converts incident sunlight into electric current in proportion to its surface area. The stack 16 of solar cell plates 20 is situated on an inclined surface 24 of the housing 12 , which surface is similar to the top of a podium. The base 14 of the housing 12 can be securely placed on any surface. In order to spread out, the uppermost solar cell plate 20 is pivoted in relation to the symmetry axis 18 , all the way to the right or left while the remaining solar cell plates 20 axially adjacent to the uppermost one are “fanned out” 0 to the left or right, describing a semicircle. The inside of the housing 12 contains electrical connecting means and electronic elements, not shown, that are usually provided in connection with battery-charging units. The housing 12 has a handle 28 in back, which is designed in the form of a spade handle. FIG. 2 shows the details explained above in connection with FIG. 1 , but no further mention of these details is required. FIG. 2 shows the position of the pivot axis 23 and of the swivel pin 22 . It is also clear that the stack 16 is comprised of seven separate, identically designed solar cell plates 20 . FIG. 3 shows the back of the solar battery-charging station 10 , where the back of the inclined surface 24 and of the housing 12 can be seen, as well as the design of the handle 28 ; a plug opening 30 is also shown, into which is plugged the plug terminal of a battery pack of the kind used for battery-operated hand-held power tools. Ventilation slots 32 are also shown, as well as a charge control indicator 26 that indicates the charge state of a battery pack when one is plugged in. FIG. 4 shows the underside of the solar battery-charging station and the design of the handle 28 with a grasping opening 34 . FIG. 5 shows the front view of the solar battery-charging station 10 ; in addition to the details mentioned above, which are not discussed again here, FIG. 5 particularly shows the seven solar cell plates 20 , which are electrically connected to one another, spread out like a fan. On each solar cell plate, close to the swivel pin 22 , the figure also shows a slip ring contact 36 via which the individual solar cell plates are electrically coupled to one another like links in a chain. This produces a series connection of the individual solar cell plates so that a charging current is present at the plug opening or at the charging terminal for battery packs and the intensity of this charging current is proportional to the total surface area of all seven solar cell plates. If the solar battery-charging station according to FIG. 1 is folded together, then only a minimal charging current is present, which is proportional to the surface area of the top solar cell plate 20 . On their front side or top, the solar cell plates 20 have a light-converting layer, which feeds into a common electrical contact point. The back side, which is comprised of a mechanically stable substrate, is spaced apart from the neighboring solar cell plate 20 by an air gap to prevent the light-converting layer from being scratched when the stack 16 is spread out or folded together. The electrical contact point is disposed at the bottom end of each solar cell plate 20 and constitutes a slip ring contact 36 there. On the front side, this slip ring contact is embodied in the form of an arc-shaped connecting link and on the back side, it is embodied in the form of an electrically conductive protrusion. Thus, each protrusion of a solar cell plate 20 engages in the arc-shaped connecting link of a neighboring solar cell plate 20 disposed underneath it in the stack 16 .

A solar cell plate for generating electric current includes a number of individual plates that can be moved in relation to one another to produce a convenient packing size.

This application is a continuation-in-part of U.S. Ser. No. 07/903,368 filed on Jun. 24, 1992 by Melvin J. Schmidt et al, now U.S. Pat. No. 5,243,783. FIELD OF THE INVENTION This invention generally relates to a locking slide block for double-hung tilt-out type windows. BACKGROUND OF THE INVENTION Double-hung, tilt-out type windows have become increasingly popular. Much of this popularity is due to the tilt-out feature which allows both inside and outside surfaces of the window to be cleaned from the inside. Tilt-out windows have been equipped with locking slide blocks such as the one disclosed in U.S. Pat. No. 4,610,108 to Marshik. Marshik discloses a double-hung window having a frame with a set of parallel jamb channels on opposite sides of the frame. Within each jamb channel is a slidably mounted locking block. A spring counter-balance mechanism is attached to a headplate on each block. A pivot extends from proximate the lower end of opposite sides of a sash into a locking cam housed within the block. The pivots allow the sash, which holds a window pane, to be rotated or tilted toward the inside. As the pivots rotate, the cam forces serrated ends of a spring into opposite sides of the jamb channel to prevent the counter-balance spring from pulling up the blocks and sash while cleaning. U.S. Pat. No. 4,813,180 to Scalzi discloses another locking sliding block for double-hung windows. Like the '108 patent, a locking block is slidably mounted within jamb channels and a pivot extends from opposite sides of the sash into a pivot button or cam in each locking block. Unlike the '108 patent, however, the pivot has a slot which engages a retaining ridge in the pivot button. This is intended to prevent dislocation of the pivots during transport and installation of the window due to deflection or bowing of the frame away from the sash. The locking block disclosed by Scalzi, although allowing the sash to pivot inside for easy cleaning of the window pane, does not allow the window to be conveniently removed from the inside. SUMMARY OF THE INVENTION The invention addresses many of the problems associated with the prior art in providing a locking slide block which enables the sash of a double-hung, tilt-out type window to be tilted to the inside to facilitate the cleaning, insertion and removal of the window sash and panes from a window frame. A sash pivot retaining spring configuration is utilized thereon to provide reliable, simple and relatively effortless operation of a locking slide block during shipping and installation, as well as in normal use. In accordance with the invention, a locking slide block is provided for slidably and pivotably mounting a window sash to a side member of a window frame having a vertical jamb channel with oppositely disposed sides. The block has a housing with oppositely disposed sliding surfaces for guiding the housing in the jamb channel. Within the block is a locking means for selectively engaging the oppositely disposed sides of the jamb channel to lock the block in a fixed position relative to the jamb channel. A cam is disposed within the housing. The cam has at least one camming surface which selectively operates the locking means. The cam also has a sash pivot opening with an open top slot, for attaching a sash pivot thereto. Sash pivots are operatively connectable to each lower opposite side of a sash, for operatively connecting the sash to the cam. The locking slide block also has a sash pivot retainer spring having a first end operatively connected to the housing and a second end proximate the cam. The second end has a first position for allowing the sash pivot to be inserted or removed from the sash pivot opening through the open top slot. The second end also has a second position for preventing removal of the sash pivot through the open top slot. The second end is normally biased to the second position, and may be depressed to the first position. The locking slide block also preferably includes a second end retaining means. The second end retaining means is operatively connected to the housing, and it operates to restrict movement of the second end of the retainer spring past the second position in a direction opposite that of the first position. This protects the second end from deforming due to forces applied to the window sash in operation, and thus increases the overall reliability of the slide block. In a preferred embodiment, the second end retaining means utilizes at least one spring retaining flange which extends across a portion of a spring receiving recess to cooperatively about the second end of the spring in its second position. Further, cooperative flanges may also be utilized on the retainer spring to facilitate this abutting relationship between the spring and the spring retaining flange. These and other advantages and features, which characterize the invention, are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages and objectives attained by its use, reference should be made t drawing which forms a further part hereof and to the accompanying descriptive matter, in which there is described a preferred embodiment of the invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a double-hung window with a partially tilted sash. FIG. 2 shows an exploded perspective view of a locking slide block with sash pivot consistent with the invention, for use in the double-hung window in FIG. 1. FIG. 3 shows an assembled locking slide block without sash pivot with the invention. FIG. 4 shows a perspective view of the sash pivot. FIG. 5 shows a locking slide block in an unlocked position a jamb channel. FIG. 6 shows a locking slide block in a locked position a jamb channel. FIG. 7 shows a mirror image of the locking slide block of FIG. 5. FIG. 8 shows parallel jamb channels, one with a counter-balance spring cover and the other having a locking slide block with sash pivot. FIG. 9 shows a cross-section of the locking slide block shown in FIG. 6. FIG. 10 shows an exploded perspective view of an alternative housing and retaining spring consistent with the invention. FIG. 11 shows a perspective view of an assembled locking slide block without sash pivot, and with the housing and retaining spring of FIG. 10. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing, wherein like referenced numerals designate identical or corresponding parts throughout the several views, FIG. 1 shows a double-hung tilt-out window 10. The window 10 has a frame 12 and an upper sash 14 and a lower sash 16 supporting window panes 15 and 17, respectively. The frame 12 also has four jamb channels 18, one of which is shown in FIG. 1, on a side member 13 of frame 12. One jamb channel is proximate opposite sides of the upper sash 14, and one is proximate opposite sides of lower sash 16. As shown in FIG. 1, the lower sash 16 is partially tilted so that both sides of the window pane 17 within the lower sash 16 are accessible for cleaning from the same side of window 10. FIG. 2 shows an exploded view of a locking slide block, generally referred to as 20, and sash pivot 22 of the present invention. One locking slide block 20 is slidably mounted within each jamb channel 18. Fastened to lower opposite sides of each sash 14 and 16 is one sash pivot 22. These sash pivots 22 are supported for rotation by the locking slide blocks 20. Each sash is tiltable about a longitudinal axis through pivots 22 disposed on opposite sides of sashes 14 and 16. As shown in FIG. 2, locking slide block 20 has a housing 24, preferably of rigid plastic. This housing 24 has sliding surfaces 25 with slots 27. The housing 24 has an aperture 49 and a plate groove 51 for attaching a sash pivot retainer spring 26 and a metal plate 28, respectively. A counter-balance spring (not shown) is attached to metal plate 28. The housing 24 has a circular channel 30, which extends into housing 24 generally parallel to sliding surfaces 25, for receiving a locking cam 32 having camming surfaces 31. Housing 24 also has a box-like area for receiving locking spring 34 which has serrated end portions 35. Locking cam 32 has a head 35 which, as known to those skilled in the art, retains spring 34 in the box-like area of housing 24. Sash pivot retainer spring 26, as shown in FIG. 2, has a hooked first end 48 which is received by aperture 49 to operably connect retainer spring 26 to housing 24. Retainer spring 26 also has a free end 50. Retainer spring 26 is preferably constructed of spring steel. Locking cam 32, as shown in FIG. 2, has a sash pivot opening 33 with an open top slot 37. Located proximate a front side of locking cam 32, on opposite sides of sash pivot opening 33 are inwardly disposed cam flanges 39. FIG. 3 shows a perspective view of the assembled locking slide block 20 without sash pivot 22. Retainer spring 26 and plate 28 are shown installed within housing 24. Free end 50 of spring 26 is in a normal position proximate the front side of locking cam 32. Locking cam 32 is shown inserted within circular channel 30, and is retained within block 20 by a tab 38. FIG. 3 also shows one serrated end portion 35 of spring 34 retracted within slot 27 in sliding surface 25. FIG. 4 is a front view of sash pivot 22 having oppositely disposed flanges 21 at one end of an elongated portion 29, and a back 23. Sash pivots 22 are fastened to the lower opposite sides of sashes 14 and 16 so that the lengthwise axis of back 23 is parallel to the lengthwise axis of the sash side. FIG. 5 shows locking slide block 20 inserted in jamb channel 18 having sides 40. Sliding surfaces 25 of sliding locking block 20 are proximate side 40 of jamb channel 18. Locking slide block 20 is held within jamb channel 18 by a flexible raised jamb channel face 42 having opening 44. As shown in FIG. 6, the serrated portions of spring 34 are engaged with sliding surfaces 25 to prevent the counter-balance spring from pulling locking slide block 20 and sash 14 or 16 upward when sash 14 or 16, respectively, is tilted. When sash 14 or 16 and, thus back 23, is rotated from vertical, locking cam 32 rotates so that camming surfaces 31 force serrated end portions 35 of spring 34 out slots 27. In FIG. 6, back 23 is tilted to a horizontal position at approximately 90° to jamb channel 18. This position also corresponds to sash 14 or 16 tilted at 90° to jamb channel 18. Also shown in FIG. 6, sash pivot 22 is operably connected to locking cam 32 by rotating cam 32 (by a tool not shown) so that open top slot 37 opens upward beneath retainer spring 26. Sash pivot 22 is inserted into sash pivot opening 33 by depressing the free end 50 of retainer spring 26 inwardly away from the front side of locking cam 32 to a first depressed position. After sash pivot 22 is inserted in sash pivot opening 33, the free end of retainer spring 26 moves back to a normal, second position over opening 33. Once retainer spring 26 moves back over opening 33, sash pivot 22 cannot slip out of opening 33. Without retainer spring 26, sash pivot 22 might slip out of opening 33 when sash 14 or 16 is tilted. As best shown in FIG. 9, a cross-sectional view of cam 32 and sash pivot 22 taken from FIG. 6, when sash pivot 22 is inserted into sash pivot opening 33, the elongated portion 29 extends into the opening beyond cam flanges 39. Flanges 21 of sash pivot 22 are disposed widely enough that when sash pivot 22 is inserted in this manner, flanges 21 engage with cam flanges 39 so that sash pivot 22 cannot be pulled out of the pivot opening in a direction proximately parallel to a longitudinal axis of the elongated portion 29. This feature is particularly important during transport and installation of window 10. During transport and installation, side members 13 of frame 12 may bow outwardly away from sashes 14 and/or 16 so that without the engagement of flanges 21 with cam flanges 39, elongated portion 29 of sash pivot 22 could be pulled out of sash pivot opening 33. FIG. 7 shows back 23 of sash pivot 22 oriented vertically. This position of back 23 corresponds to the closed or vertical position of sash 14 or 16. Serrated end portions 35 of spring 34 are not engaged with sides 40 of jamb channel 18. Locking slide block 20 and sash 14 or 16 is thus free to slide vertically within jamb channel 18. The counter-balance spring (not shown) attached to plate 28 assists in sliding locking slide blocks 20 and sashes 14 or 16 upward in jamb channels 18. FIG. 8 shows a cross-sectional view of parallel jamb channels 18. In one of the jamb channels 18 is shown locking slide block 20 without serrated end portions 35 of spring 34 extending beyond sides 25 of locking slide block 20. As previously shown in FIG. 7, back 23 of sash pivot 22 is positioned vertically. Flexible jamb channel face 42 is engaged with a sash groove 46 to retain sash 16 vertically within frame 12 (not shown). FIGS. 10 and 11 show an alternative embodiment of the locking slide block consistent with the invention. It has been discovered that in certain instances, forces applied to a sash may be applied by a sash pivot to the retainer spring in a locking slide block, causing the retainer spring to "buckle" and bow outward from the force. In certain circumstances, this may result in the sash pivot becoming partially dislodged from the sash pivot opening in the cam, thereby jamming the slide block and preventing the sash from moving up or down in the jamb channel. For example, as best seen in FIG. 6, when sash 14 or 16 is tilted, open top slot 37 may be oriented upward and directly opposite retainer spring 26. An upward force on sash 14 or 16, for instance applied by gripping the sash on the sides near sash pivots 22, tends to urge elongated portion 29 of sash pivot 22 against the free end 50 of retainer spring 26. Since spring 26 extends generally away from housing 24 at the hooked first end 48, any force applied to free end 50 may induce this end to bow outward from housing 24. Given a sufficient force, free end 50 may buckle outward and allow sash pivot 22 to become partially dislodged from its operating position. The alternative embodiment shown in FIGS. 10 and 11 includes a retaining means for protecting the free end of a retainer spring from the upward forces that could possibly cause failure of the locking slide block. As shown in FIG. 10, locking slide block 20' includes an alternative housing 24' and retainer spring 26'. Housing 24' has a spring receiving recess 62 which extends into housing 24' for housing retainer spring 26' in operation. This recess 62 is integrally joined to the cam receiving channel 30' which, in operation, houses the locking cam. In order to protect retainer spring 26' from the above-described forces, a pair of spring retaining flanges 61a and 61b are provided which extend across a portion of recess 62. In the preferred embodiment, flanges 61a and 61b extend outward from walls 60a and 60b of recess 62. Other flange configurations may also be used in lieu of that shown for flanges 61a and 61b. Sash pivot retainer spring 26' has a hooked first end 48' which is received by aperture 49' to operably connect retainer spring 26' to housing 24'. Further, retainer spring 26' includes a free end 50', which has a pair of oppositely disposed and outwardly projecting spring flanges 52a and 52b. FIG. 11 shows an assembled locking slide block 20' without a sash pivot installed. Here, retainer spring 26' is installed, with metal plate 28' holding the spring in position. Free end 50' is housed within recess 62, proximate flanges 61a and 61b, and proximate cam 32'. In the configuration shown, when free end 50' is not depressed and in the normal position, spring flanges 52a and 52b cooperatively abut spring retaining flanges 61a and 61b. This cooperatively abutting relationship protects spring 26' when upward forces are applied to free end 50' by a sash pivot. Free end 50' is not capable of bowing outward in a direction opposite the normal direction in which free end 50' is depressed (such as when inserting or removing a sash pivot). Thus, the free end is substantially protected from deforming due to these forces. Returning to FIG. 10, it may also be seen that it is preferable to leave sufficient space, i.e., a channel 63, in between flanges 61a and 61b. This enables a sash pivot to be inserted and removed from locking slide block 20' through channel 63. One skilled in the art will appreciate that various modifications may be made without departing from the scope of the invention. For example, a number of different sizes and configurations of spring retaining flanges may be used to abut with free end 50' to protect it from bowing outward. In addition, other spring flanges could be incorporated into free end 50' to cooperatively abut with the flanges over recess 62. Further, spring flanges 52a and 52b could be eliminated altogether as long as flanges 61a and 61b extend a sufficient distance across recess 62 to abut with free end 50' during normal use. It is further not necessary that flanges 52a and 52b abut flanges 61a and 61b in normal operation, as the normal operating position of free end 50' may be disposed away from the plane of flanges 61a and 61b in its normal position. Although characteristics and advantages, together with details of structure and function, have been described in reference to the preferred embodiments herein, it is understood that the disclosure is illustrative. To that degree, various changes made, especially in matters of shape, size and arrangement, to the full extent extended by the general meaning of the terms in which the appended claims are expressed, are within the principles of the present invention.

The present invention is directed to a locking slide block slidably and pivotably mounting a window sash to a side member of a window frame having a vertical jamb channel. The locking slide block has a housing with oppositely disposed sliding surfaces for guiding the housing in the jamb channel. Operably connected to the housing is a locking means for selectively engaging the jamb channel and locking the housing in a fixed position, and a cam for selectively operating the locking means. A sash pivot operatively connected to the cam is operably connectable to the sash. The housing also has a sash pivot retainer spring. A retaining means is utilized to protect a free second end of the retainer spring from bowing and deforming due to forces applied to the window sash in operation.

FIELD OF THE INVENTION AND RELATED ART [0001] The present invention relates to a luminescence device, a metal coordination compound therefor and a display apparatus including the luminescence device. More specifically, the present invention relates to an organic (electro-)luminescence device employing a metal coordination compound having a formula (1) or (2) appearing hereinafter as a luminescence material, the metal coordination compound adapted for use in the luminescence device, and a display apparatus using the luminescence device. [0002] An organic electroluminescence (EL) device has been extensively studied as a luminescence device with a high responsiveness and high efficiency. [0003] The organic EL device generally has a sectional structure as shown in FIG. 1A or 1 B (e.g., as described in “Macromol. Symp.”, 125, pp. 1-48 (1997)). [0004] Referring to the figures, the EL device generally has a structure including a transparent substrate 15 , a transparent electrode 14 disposed on the transparent substrate 15 , a metal electrode 11 disposed opposite to the transparent electrode 14 , and a plurality of organic (compound) layers disposed between the transparent electrode 14 and the metal electrode 11 . [0005] Referring to FIG. 1, the EL device in this embodiment has two organic layers including a luminescence layer 12 and a hole transport layer 13 . [0006] The transparent electrode 14 may be formed of a film of ITO (indium tin oxide) having a larger work function to ensure a good hole injection performance into the hole transport layer. On the other hand, the metal electrode 11 may be formed of a layer of aluminum, magnesium, alloys thereof, etc., having a smaller work function to ensure a good electron injection performance into the organic layer(s). [0007] These (transparent and metal) electrodes 14 and 11 may be formed in a thickness of 50-200 nm. [0008] The luminescence layer 12 may be formed of, e.g., aluminum quinolinol complex (representative example thereof may include Alq3 described hereinafter) having an electron transporting characteristic and a luminescent characteristic. The hole transport layer 13 may be formed of, e.g., triphenyldiamine derivative (representative example thereof may include α-NPD described hereinafter) having an electron donating characteristic. [0009] The above-described EL device exhibits a rectification characteristic, so that when an electric field is applied between the metal electrode 11 as a cathode and the transparent electrode 14 as an anode, electrons are injected from the metal electrode 11 into the luminescence layer 12 and holes are injected from the transparent electrodes 14 . [0010] The thus-injected holes and electrons are recombined within the luminescence layer 12 to produce excitons, thus causing luminescence. At that time, the hole transport layer 13 functions as an electron-blocking layer to increase a recombination efficiency at the boundary between the luminescence layer 12 and the hole transport layer 13 , thus enhancing a luminescence efficiency. [0011] Referring to FIG. 1B, in addition to the layers shown in FIG. 1A, an electron transport layer 16 is disposed between the metal electrode 11 and the luminescence layer 12 , whereby an effective carrier blocking performance can be ensured by separating functions of luminescence, electron transport and hole transport, thus allowing effective luminescence. [0012] The electron transport layer 16 may be formed of, e.g., oxadiazole derivatives. [0013] In ordinary organic EL devices, fluorescence caused during a transition of luminescent center molecule from a singlet excited state to a ground state is used as luminescence. [0014] On the other hand, not the above fluorescence (luminescence) via singlet exciton, phosphorescence (luminescence) via triplet exciton has been studied for use in organic EL device as described in, e.g., “Improved energy transfer in electrophosphorescent device” (D. F. O'Brien et al., Applied Physics Letters, Vol. 74, No. 3, pp. 442-444 (1999)) and “Very high-efficiency green organic light-emitting devices based on electrophosphorescence” (M. A. Baldo et al., Applied Physics Letters, Vol. 75, No. 1, pp. 4-6 (1999)). [0015] The EL devices shown in these documents may generally have a sectional structure shown in FIG. 1C. [0016] Referring to FIG. 1C, four organic layers including a hole transfer layer 13 , a luminescence layer 12 , an exciton diffusion-prevention layer 17 , and an electron transport layer 16 are successively formed in this order on the transparent electrode (anode) 14 . [0017] In the above documents, higher efficiencies have been achieved by using four organic layers including a hole transport layer 13 of α-NPD (shown below), an electron transport layer 16 of Alq3 (shown below), an exciton diffusion-prevention layer 17 of BPC (shown below), and a luminescence layer 12 of a mixture of CPB (shown below) as a host material with Ir(ppy) 3 (shown below) or PtOEP (shown below) as a guest phosphorescence material doped into CBP at a concentration of ca. 6 wt. %. [0018] Alq3: tris(8-hydroxyquinoline) aluminum (aluminum-quinolinol complex), [0019] α-NPD: N4,N4′-di-naphthalene-1-yl-N4,N4′-diphenyl-biphenyl-4,4′-diamine (4,41-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl), [0020] CBP: 4,4′-N,N′-dicarbazole-biphenyl, [0021] BCP: 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, [0022] Ir(ppy) 3 : fac tris(2-phenylpyridine)iridium (iridium-phenylpyridine complex), and [0023] PtEOP: 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphine platinum (platinum-octaethyl porphine complex). [0024] The phosphorescence (luminescence) material used in the luminescence layer 12 has attracted notice. This is because the phosphorescence material is expected to provide a higher luminescence efficiency in principle. [0025] More specifically, in the case of the phosphorescence material, excitons produced by recombination of carriers comprise singlet excitons and triplet excitons presented in a ratio of 1:3. For this reason, when fluorescence caused during the transition from the singlet excited state to the ground state is utilized, a resultant luminescence efficiency is 25% (as upper limit) based on all the produced excitons in principle. [0026] On the other hand, in the case of utilizing phosphorescence caused during transition from the triplet excited state, a resultant luminescence efficiency is expected to be at least three times that of the case of fluorescence in principle. In addition thereto, if intersystem crossing from the singlet excited state (higher energy level) to the triplet excited state is taken into consideration, the luminescence efficiency of phosphorescence can be expected to be 100% (four times that of fluorescence) in principle. [0027] The use of phosphorescence based on transition from the triplet excited state has also been proposed in, e.g., Japanese Laid-Open Patent Application (JP-A) 11-329739, JP-A 11-256148 and JP-A 8-319482. [0028] An iridium-phenylpyrimidine complex having a methyl substituent has been described in “Preprint for the 61-th Academical Lecture of the Applied Physics Society of Japan”, the third volume, P.1117, 6p-ZH-1 (2000) (“Document 1”). Further, an iridium-phenylpyrimidine complex having 4-, 5-fluorine substituents (herein, referred to as a “metal coordination compound A” has been described in “Polymer Preprints”, 41(1), pp. 770-771 (2000) (“Document 2”). [0029] However, the above-mentioned organic EL devices utilizing phosphorescence have accompanied with a problem of luminescent deterioration particularly in an energized state. [0030] The reason for luminescent deterioration has not been clarified as yet but may be attributable to such a phenomenon that the life of triplet exciton is generally longer than that of singlet exciton by at least three digits, so that molecule is placed in a higher-energy state for a long period to cause reaction with ambient substance, formation of exciplex or excimer, change in minute molecular structure, structural change of ambient substance, etc. [0031] Accordingly, the (electro)phosphorescence EL device is expected to provide a higher luminescence efficiency as described above, while the EL device is required to suppress or minimize the luminescent deterioration in energized state. SUMMARY OF THE INVENTION [0032] An object of the present invention is to provide a luminescence device capable of providing a high-efficiency luminescent state at a high brightness (or luminance) for a long period while minimizing the deterioration in luminescence in energized state. [0033] Herein, although evaluation criteria for “high efficiency” and “high brightness (luminance) for a long period” may vary depending on luminescent performances required for an objective luminescence device (EL device), for example, a luminescence efficiency of at least 1 cd/W based on an inputted current value may be evaluated as “high efficiency”. Further, a luminance half-life of, e.g., at least 500 hours at the time of luminescence at an initial luminance of 100 cd/m 2 may be evaluated as “high brightness (luminance) for a long period” or a smaller luminance deterioration in energized state. [0034] Another object of the present invention is to provide a metal coordination compound as a material suitable for an organic layer for the luminescence device. [0035] According to the present invention, there is provided a luminescence device, comprising: an organic compound layer comprising a metal coordination compound represented by the following formula (1): [0036] wherein M denotes Ir, Rh or Pd; n is 2 or 3; and X1 to X8 independently denote hydrogen atom or a substituent selected from the group consisting of halogen atom; nitro group; trifluoromethyl group; trialkylsilyl group having three linear or branched alkyl groups each independently having 1-8 carbon atoms; and a linear or branched alkyl group having 2-20 carbon atoms capable of including one or at least two non-neighboring methylene groups which can be replaced with —O—, —S—, —CO—, —CO—O—, —O—CO—, —CH═CH— or —C≡C— and capable of including hydrogen atom which can be replaced with fluorine atom; with the proviso that at least one of X1 to X8 is a substituent other than hydrogen atom, and X2 and X3 cannot be fluorine atom at the same time. [0037] According to the present invention, there is also provided a metal coordination compound, adapted for use in a luminescence device, represented by the following formula (1): [0038] wherein M denotes Ir, Rh or Pd; n is 2 or 3; and X1 to X8 independently denote hydrogen atom or a substituent selected from the group consisting of halogen atom; nitro group; trifluoromethyl group trialkylsilyl group having three linear or branched alkyl groups each independently having 1-8 carbon atoms; and a linear or branched alkyl group having 2-20 carbon atoms capable of including one or at least two non-neighboring methylene groups which can be replaced with —O—, —S—, —CO—, —CO—O—, —O—CO—, —CH═CH— or —C≡C— and capable of including hydrogen atom which can be replaced with fluorine atom; with the proviso that at least one of X1 to X8 is a substituent other than hydrogen atom, and X2 and X3 cannot be fluorine atom at the same time. [0039] The present invention provides a luminescence device, comprising: an organic compound layer comprising a metal coordination compound represented by the following formula (2): [0040] wherein M denotes Ir, Rh or Pd; n is 2 or 3; Y denotes an alkylene group having 2-4 carbon atoms capable of including one or at least two non-neighboring methylene groups which can be replaced with —O—, —S— or —CO— and capable of including hydrogen atom which can be replaced with a linear or branched alkyl group having 1-10 carbon atoms; and X1 and X2 independently denote hydrogen atom; halogen atom; nitro group; trialkylsilyl group having 1-8 carbon atoms; or a linear or branched alkyl group having 1-20 carbon atoms capable of including one or at least two non-neighboring methylene groups which can be replaced with —O—, —S—, —CO—, —CO—O—, —O—CO—, —CH═CH— or —C≡C— and capable of including hydrogen atom which can be replaced with fluorine atom. [0041] The present invention also provides a metal coordination compound, adapted for use in a luminescence device, represented by the following formula (2): [0042] wherein M denotes Ir, Rh or Pd; n is 2 or 3; Y denotes an alkylene group having 2-4 carbon atoms capable of including one or at least two non-neighboring methylene groups which can be replaced with —O—, —S—or —CO— and capable of including hydrogen atom which can be replaced with a linear or branched alkyl group having 1-10 carbon atoms; and X1 and X2 independently denote hydrogen atom; halogen atom; nitro group; trialkylsilyl group having 1-8 carbon atoms; or a linear or branched alkyl group having 1-20 carbon atoms capable of including one or at least two non-neighboring methylene groups which can be replaced with —O—, —S—, —CO—, —CO—O—, —O—CO—, —CH═CH— or —C≡C— and capable of including hydrogen atom which can be replaced with fluorine atom. [0043] The present invention further provides a display apparatus including the above-mentioned luminescence device and drive means for driving the luminescence device. [0044] These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0045] [0045]FIGS. 1A, 1B and 1 C are respectively a schematic sectional view of a layer structure of a luminescence device. [0046] [0046]FIG. 2 is a graph showing a relationship between a Hammett's substitution constant a and a peak (maximum) emission wavelength λ PE . DESCRIPTION OF THE PREFERRED EMBODIMENTS [0047] In the case where a luminescence layer for an organic EL device is formed of a carrier transporting host material and a phosphorescent guest material, a process of emission of light (phosphorescence) may generally involve the following steps: [0048] (1) transport of electron and hole within a luminescence layer, [0049] (2) formation of exciton of the host material, [0050] (3) transmission of excited energy between host material molecules, [0051] (4) transmission of excited energy from the host material molecule to the guest material molecule, [0052] (5) formation of triplet exciton of the guest material, and [0053] (6) emission of light (phosphorescence) caused during transition from the triplet excited state to the ground state of the guest material. [0054] In the above steps, desired energy transmission and luminescence may generally be caused based on various quenching and competition. [0055] In order to improve a luminescence efficiency of the EL device, a luminescence center material per se is required to provide a higher yield of luminescence quantum. In addition thereto, an efficient energy transfer between host material molecules and/or between host material molecule and guest material molecule is also an important factor. [0056] Further, the above-described luminescent deterioration in energized state may presumably relate to the luminescent center material per se or an environmental change thereof by its ambient molecular structure. [0057] For this reason, our research group has extensively investigated an effect of use of various metal coordination compounds as the luminescent center material and as a result, has found that the metal coordination compound represented by the above-mentioned formula (1) or (2) allows a high-efficiency luminescence with a high brightness (luminance) for a long period (i.e., a decreased luminescent deterioration in energized state). [0058] The metal coordination compound of formula (1) may preferably have substituents X1 to X8 in which at least two of X1 to X8 are substituents other than hydrogen atom. Further, in the formula (1), at least one of X5 to X8 may preferably be a substituent other than hydrogen atom and/or at least two of X1 to X4 may preferably be substituents other than hydrogen atom. [0059] The metal coordination compound represented by the formulas (1) causes phosphorescence (luminescence) and is assumed to have a lowest excited state comprising a triplet excited state liable to cause metal-to-ligand charge transfer (MLCT* state). The phosphorescent emission of light (phosphorescence) is produced during the transition from the MLCT* state to the ground state. [0060] The metal coordination compound of formula (1) according to the present invention has been found to provide a higher phosphorescence yield of 0.1-0.9 and a shorter phosphorescence life of 1-60 μsec. [0061] A phosphorescence yield (P(m)) is obtained based on the following equation: P(m)/P(s)=(S(m)/S(s))×(A(s)/A(m)), [0062] wherein P(m) represents a phosphorescence yield of an (unknown) objective luminescent material, P(s) represents a known (standard) phosphorescence yield of standard luminescent material (Ir(ppy) 3 ), S(m) represents an integrated intensity of (photo-)excited emission spectrum of the objective material, S(s) represents a known integrated intensity of the standard material, A(m) represents an absorption spectrum of an excited light wavelength of the objective material, and A(s) represents a known absorption spectrum of the standard material. [0063] The shorter phosphorescence life is necessary to provide a resultant EL device with a higher luminescence efficiency. This is because the longer phosphorescence life increases molecules placed in their triplet excited state which is a waiting state for phosphorescence, thus lowering the resultant luminescence efficiency particularly at a higher current density. [0064] Accordingly, the metal coordination compound of formula (1) according to the present invention is a suitable luminescent material for an EL device with a higher phosphorescence yield and a shorter phosphorescence life. [0065] Further, we have found that it is possible to control an emission wavelength of the metal coordination compound of formula (1) by appropriately modifying the substituents X1 to X8 thereof. In this regard, as a result of our investigation on various phosphorescence metal coordination compounds for a blue luminescence material required to have a peak (maximum) emission wavelength of at most 490 nm, we have found that it is very effective to introduce at least one substituent having a Hammett's substituent constant of at least 0.2 into the metal coordination compound of formula (1) in order to provide a shorter peak emission wavelength. [0066] More specifically we investigated a relationship between Hammett's substituent constants a of substituents X2, X3 and X4 with respect to carbon atom connected to iridium of an iridium complex (metal coordination compound) shown below and peak emission wavelengths λ PE in toluene at 25° C. [0067] With respect to the Hammett's substituent constant σ, a Hammett's substituent constant σm for meta-position was used for the substituents X2 and X4 and a Hammett's substituent constant op for para-position was used for the substituent X3. When two or more substituents other than hydrogen atom were present at X2 to X4, a sum of σm and σp was used as a Hammett's substituent constant σ. [0068] In the present invention, specific values of σm and σp described on pages 96-103 (Table 1) of “Correlation between Structure and Activation of Drugs”, Chemical Region Extra Edition 122, issued by Nanko-do (Japan) were used as those for X2 to X4. A part of σm and σp described therein is shown in Table 1 below. TABLE 1 Substituent σp σm F 0.06 0.34 Cl 0.23 0.37 CF 3 0.54 0.43 [0069] For example, a metal coordination compound (Example Compound No. (121) appearing hereinafter, X2=F, X3=CF 3 , X4=H) has a Hammett's substituent constant σ=0.34+0.54=0.88. In a similar manner, Hammett's substituent constants σ of several metal coordination compounds (Ex. Comp. Nos. (1), (32), (122) and (111) described later and the metal coordination compound A described in the above-mentioned Document 2) are calculated and shown in Table 2 below together with corresponding peak emission wavelength λ PE in toluene at 25° C. The results of Table 2 are also shown in FIG. 2. TABLE 2 Compound σ λ PE (nm) Ex. Comp. No. (1) 0.06 522 Metal coordination 0.40 505 compound A Ex. Comp. No. (32) 0.54 487 Ex. Comp. No. (122) 0.68 471 Ex. Comp. No. (121) 0.88 466 Ex. Comp. No. (111) 0.91 479 [0070] As apparent from Table 2 and FIG. 2, introduction of substituent(s) having a larger Hammett's substituent constant is very effective to shorten the peak emission wavelength. Specifically, the metal coordination compound having the sum of peak emission wavelengths of at least 0.41, particularly at least 0.50 is suitable as the blue luminescent material. A similar effect can be expected also for metal coordination compounds other than the metal coordination compound of formula (1) of the present invention. [0071] As described above, the metal coordination compound of formula (1) is a suitable luminescent material for the EL device. [0072] Further, as shown in Examples appearing hereinafter, it has been substantiated that the metal coordination compound of formula (1) of the present invention has an excellent stability in a continuous energization test. [0073] This may be attributable to introduction of particular substituents (X1 to X8) allowing control of intermolecular interaction with a host luminescent material (e.g., CBP described above) and suppression of formation of associated exciton leading to thermal quenching, thus minimizing quenching to improve device characteristics. [0074] In this regard, the methyl group of methyl-substituted iridium-phenylpyrimidine complex described in the above-mentioned Document 1 has a smaller bulkiness than ethyl group and methoxy group and a smaller electronic effect than halogen atom, trifluoromethyl group and methoxy group. As a result, the effect of controlling intermolecular interaction in the present invention cannot be expected. [0075] Further, compared with 4-, 5-fluorine (substituted) iridium-phenylpyrimidine complex (metal coordination compound A) described in the above-mentioned Document 2, it has been substantiated that a luminescence device using the metal coordination compound of formula (1) according to the present invention has a higher durability, i.e., a higher luminance stability for a long period, shown in Examples described later. [0076] Further, in the case of phosphorescent (luminescent) material, luminescent characteristics are largely affected by its molecular environment. On the other hand, principal characteristics of the fluorescent material are studied based on photoluminescence. [0077] For this reason, results of photoluminescence of the phosphorescent material do not reflect luminescent characteristics of the resultant EL device in many cases since the luminescent characteristics in the case of the phosphorescent material depend on a magnitude of polarity of ambient host material molecules, ambient temperature, presence state of the material (e.g., solid state or liquid state, etc. Accordingly, different from the fluorescent material, it is generally difficult to expect the resultant EL characteristics for the phosphorescent material by simply removing a part of characteristics from photoluminescence results. [0078] Next, the metal coordination compound of formula (2) according to the present invention will be described. [0079] The metal coordination compound of formula (2) may preferably have hydrogen atom(s) as at least one of X1 and X2 in the formula (2). [0080] Similarly as the metal coordination compound of formula (1), the metal coordination compound of formula (2) also causes phosphorescence (luminescence) and is assumed to have a lowest excited state comprising a triplet excited state liable to cause metal-to-ligand charge transfer (MLCT* state). The phosphorescent emission of light (phosphorescence) is produced during the transition from the MLCT* state to the ground state. [0081] The metal coordination compound according to the present invention has been found to provide a higher phosphorescence yield of 0.15−0.9 and a shorter phosphorescence life of 1-40 μsec, as a result of a luminescence test based on photo-luminescence by photo-excitation. [0082] The shorter phosphorescence life is necessary to provide a resultant EL device with a higher luminescence efficiency. This is because the longer phosphorescence life increases molecules placed in their triplet excited state which is a waiting state for phosphorescence, thus lowering the resultant luminescence efficiency particularly at a higher current density. [0083] Accordingly, the metal coordination compound of formula (2) according to the present invention is a suitable luminescent material for an EL device with a higher phosphorescence yield and a shorter phosphorescence life. [0084] Further, by appropriately modifying the alkylene group Y and/or the substituents X1 and X2, emission wavelength control can be expected for the resultant metal coordination compound of formula (2). [0085] As described above, the metal coordination compound of formula (2) is a suitable luminescent material for the EL device. [0086] Further, as shown in Examples appearing hereinafter, it has been substantiated that the metal coordination compound of formula (2) of the present invention has an excellent stability in a continuous energization test. [0087] This may be attributable to introduction of particular alkylene group and/or substituents (Y, X1, X2) allowing control of intermolecular interaction with a host luminescent material (e.g., CBP described above) and suppression of formation of associated exciton leading to thermal quenching, thus minimizing quenching to improve device characteristics. [0088] The luminescence device (EL) device according to the present invention employs the above-mentioned metal coordination compound in an organic layer, particularly a luminescence layer. [0089] Specifically, the luminescence device may preferably include the organic layer comprising the metal coordination compound of formula (1) or formula (2) between a pair of oppositely disposed electrodes comprising a transparent electrode (anode) and a metal electrode (cathode) which are supplied with a voltage to cause luminescence, thus constituting an electric-field luminescence device. [0090] The liquid crystal of the present invention has a layer structure shown in FIGS. 1A to 1 C as specifically described above. [0091] By the use of the metal coordination compound of formula (1) or formula (2) of the present invention, the resultant luminescence device has a high luminescence efficiency as described above. [0092] The luminescence device according to the present invention may be applicable to devices required to allow energy saving and high luminance, such as those for display apparatus and illumination apparatus, a light source for printers, and backlight (unit) for a liquid crystal display apparatus. Specifically, in the case of using the luminescence device of the present invention in the display apparatus, it is possible to provide a flat panel display apparatus capable of exhibiting an excellent energy saving performance, a high visibility and a good lightweight property. With respect to the light source, it becomes possible to replace a laser light source of laser beam printer currently used widely with the luminescence device according to the present invention. Further, when the luminescence device of the present invention is arranged in independently addressable arrays as an exposure means for effecting desired exposure of light to a photosensitive drum for forming an image, it becomes possible to considerably reducing the volume (size) of image forming apparatus. With respect to the illumination apparatus and backlight (unit), the resultant apparatus (unit) using the luminescence device of the present invention is expected to have an energy saving effect. [0093] The metal coordination compound of formula (1) may generally be synthesized through the following reaction scheme. [0094] (Iridium complex) [0095] (Rhodium complex) [0096] Rh complex may be synthesized in the same manner as in Ir complex shown above. [0097] (Palladium complex) [0098] Specific and non-exhaustive examples of the metal coordination compound of formula (1) may include those (Example Compound Nos. (1-1) to (1-180)) shown in Tables 3-8 wherein Ex. Comp. Nos. (1-1) to (1-180) are simply indicated as (1) to (180), respectively. TABLE 3 No. M n X 1 X 2 X 3 X 4 X 5 X 6 X 7 X 8  (1) Ir 3 H H F H H H H H  (2) Ir 3 H F H H H H H H  (3) Ir 3 H H Cl H H H H H  (4) Ir 3 H H F H H OCH 3 H H  (5) Ir 3 H H F H H H Br H  (6) Ir 3 H C 2 H 5 H H H H H H  (7) Ir 3 H H NO 2 H H H H H  (8) Ir 3 H H NO 2 H H H CF 3 H  (9) Ir 3 H H NO 2 H H NO 2 H H (10) Ir 3 H H NO 2 H H OC 11 H 23 H H (11) Ir 3 H H C 3 H 7 H H H H H (12) Ir 3 H C 2 H 5 OCH 3 H H H H H (13) Ir 3 H H C 3 H 7 H H OC 4 H 9 H H (14) Ir 3 H C 20 H 41 H H H H H H (15) Ir 3 H H OCH 3 H H H H H (16) Ir 3 H OCH 3 OCH 3 H H H H H (17) Ir 3 H H OCH(CH 3 ) 2 H H H H H (18) Ir 3 H H OC 5 H 11 H H H H H (19) Ir 3 H H OC 16 H 33 H H H H H (20) Ir 3 H H OCH 3 H H OCH 3 H H (21) Ir 3 H H OCH(CH 3 ) 2 H H OCH 3 H H (22) Ir 3 H H OC 10 H 21 H H NO 2 H H (23) Ir 3 H H OCH(CH 3 ) 2 H H H CF 3 H (24) Ir 3 H H SCH 3 H H H H H (25) Ir 3 H OCH 2 CH═CH 2 H H H H H H (26) Ir 3 H H OCH 2 C≡CCH 3 H H H H H (27) Ir 3 H H COCH 3 H H H H H (28) Ir 3 H H COCH 3 H H NO 2 H H (29) Ir 3 H H COCH 3 H H H CF 3 H (30) Ir 3 H H COCH 3 H H OCH 3 H H [0099] [0099] TABLE 4 No. M n X 1 X 2 X 3 X 4 X 5 X 6 X 7 X 8 (31) Ir 3 H H COC 9 H 19 H H H H H (32) Ir 3 H H CF 3 H H H H H (33) Ir 3 H H CF 3 H H H CF 3 H (34) Ir 3 H H CF 3 H H NO 2 H H (35) Ir 3 H H CF 3 H H OCH(CH 3 ) 2 H H (36) Ir 3 H C 3 F 7 H H H H H H (37) Ir 3 H H OCF 3 H H H H H (38) Ir 3 H OCF 3 H H H H H H (39) Ir 3 H H OCF 3 H H NO 2 H H (40) Ir 3 H H OCF 3 H H H CF 3 H (41) Ir 3 H H OCF 3 H H OCH 3 H H (42) Ir 3 H H OCH 2 C 3 F 7 H H H H H (43) Ir 3 H O(CH 2 ) 3 C 2 F 5 H H H H H H (44) Ir 3 H H O(CH 2 ) 3 OCH 2 C 2 F 5 H H H H H (45) Ir 3 H H COOC 2 H 5 H H H H H (46) Ir 3 H OCOCH 3 H H H H H H (47) Ir 3 H H O(CH 2 ) 2 C 3 F 7 H H H C 5 F 11 H (48) Ir 3 H H H H H OCH 3 H H (49) Ir 3 H H H H H H CF 3 H (50) Ir 3 H H H H H H NO 2 H (51) Ir 3 H H Si(CH 3 ) 3 H H H H H (52) Ir 3 H H Si(CH 3 ) 2 C 4 H 9 H H H H H (53) Ir 3 H Si(CH 3 ) 2 C 8 H 17 H H H H H H (54) Ir 3 H H Si(C 2 H 5 ) 3 H H H H H (55) Ir 3 H H H H H Si(CH 3 ) 2 C 8 H 13 H H (56) Ir 3 H C 2 H 5 OCH 3 H H OCH 3 H H (57) Ir 3 H F H F H OCH 3 H H (58) Ir 3 H F H F H OCH 3 CF 3 H (59) Ir 3 H H Si(CH 3 ) 3 H H H Br H (60) Ir 3 H Si(CH 3 ) 2 C 7 H 15 OCH 3 H H H H H [0100] [0100] TABLE 5 No. M n X 1 X 2 X 3 X 4 X 5 X 6 X 7 X 8 (61) Rh 3 H H F H H H H H (62) Rh 3 F F H H H H H H (63) Rh 3 H H F H H OCH 3 H H (64) Rh 3 H H NO 2 H H H H H (65) Rh 3 H H NO 2 H H OC 8 H 17 H H (66) Rh 3 H H C 2 H 5 H H H H H (67) Rh 3 H C 2 H 5 OCH 3 H H H H H (68) Rh 3 H C 12 H 25 H H H H H H (69) Rh 3 H C 3 H 7 H H H OCH 3 H H (70) Rh 3 H H OCH(CH 3 ) 2 H H H H H (71) Rh 3 H H OC 15 H 31 H H H H H (72) Rh 3 H H OC 6 H 13 H H NO 2 H H (73) Rh 3 H H OCH 3 H H OCH 3 H H (74) Rh 3 H H OCH(CH 3 ) 2 H H H CF 3 H (75) Rh 3 H H OCH 2 CH═CH 2 H H H H H (76) Rh 3 H OC≡CC 4 H 9 H H H H H H (77) Rh 3 H H SC 2 H 5 H H H H H (78) Rh 3 H H SCH 3 H H OCH 3 H H (79) Rh 3 H SCH 3 SCH 3 H H H H H (80) Rh 3 H H COCH 3 H H H H H (81) Rh 3 H H COCH 3 H H OCH 3 H H (82) Rh 3 H H CF 3 H H H H H (83) Rh 3 H H CF 3 H H OCH(CH 3 ) 2 H H (84) Rh 3 H H OCF 3 H H H CF 3 H (85) Rh 3 H H OCH 2 C 4 F 9 H H H H H (86) Rh 3 H H O(CH 2 ) 6 C 2 F 5 H H H H H (87) Rh 3 H H H H H OCH 3 H H (88) Rh 3 H H Si(CH 3 ) 3 H H H H H (89) Rh 3 H Si(CH 3 ) 2 C 6 H 13 H H H H H H (90) Rh 3 H Si(CH 3 ) 2 C 7 H 15 OCH 3 H H H H H [0101] [0101] TABLE 6 No. M n X 1 X 2 X 3 X 4 X 5 X 6 X 7 X 8  (91) Pd 2 H H F H H H H H  (92) Pd 2 H F H F H H H H  (93) Pd 2 H H F H H OC 7 H 15 H H  (94) Pd 2 H H NO 2 H H H H H  (95) Pd 2 H H NO 2 H H OC 5 H 11 H H  (96) Pd 2 H C 2 H 5 OCH 3 H H H H H  (97) Pd 2 H H C 5 H 11 H H OCH 3 H H  (98) Pd 2 H C 15 H 31 H H H H H H  (99) Pd 2 H H OCH(CH 3 ) 2 H H H H H (100) Pd 2 H H OC 3 H 7 H H H H H (101) Pd 2 H H COC 8 H 17 H H H H H (102) Pd 2 H H CF 3 H H H H H (103) Pd 2 H H CF 3 H H OCH(CH 3 ) 2 H H (104) Pd 2 H H OCF 3 H H H CF3 H (105) Pd 2 H H Si(CH 3 ) 3 H H H H H (106) Pd 2 H H F H H OC 5 H 11 H H (107) Pd 2 H H NO 2 H H OC 3 H 7 H H (108) Pd 2 H H C 2 H 5 H H OCH 3 H H (109) Pd 2 H C 10 H 21 H H H H H H (110) Pd 2 H H COCH 3 H H H H H (111) Ir 3 H Cl CF 3 H H H H H (112) Ir 3 H Cl CF 3 H H H CF3 H (113) Ir 3 H Cl CF 3 H H OCH3 H H (114) Rh 3 H Cl CF 3 H H H H H (115) Rh 3 H Cl CF 3 H H H CF3 H (116) Rh 3 H Cl CF 3 H H CF3 H H (117) Rh 3 H Cl CF 3 H H OCH3 H H (118) Rh 3 H Cl CF 3 H H C 2 H 5 H H (119) Pd 2 H Cl CF 3 H H H H H (120) Pd 2 H Cl CF 3 H H H CF3 CF3 [0102] [0102] TABLE 7 No. M n X 1 X 2 X 3 X 4 X 5 X 6 X 7 X 8 (121) Ir 3 H F CF 3 H H H H H (122) Ir 3 H F H F H H H H (123) Ir 3 H CF 3 H CF 3 H H H H (124) Ir 3 H CF 3 H F H H H H (125) Ir 3 H CF 3 CF 3 H H H Br H (126) Ir 3 F C 2 H 5 H H H H H H (127) Ir 3 F H NO 2 H H H H H (128) Ir 3 F H NO 2 F H H CF 3 H (129) Ir 3 F H NO 2 H H NO 2 H H (130) Ir 3 F H NO 2 H H OC 11 H 23 H H (131) Ir 3 F H C 3 H 7 H H H H H (132) Ir 3 F C 2 H 5 OCH 3 H H H H H (133) Ir 4 F H C 3 H 7 H H OC 4 H 9 H H (134) Ir 3 H C 20 H 41 H F H H H H (135) Ir 3 H H OCH 3 F H H H H (136) Ir 3 H OCH 3 OCH 3 F H H H H (137) Ir 3 H H OCH(CH 3 ) 2 F H H H H (138) Ir 3 H H OC 5 H 11 F H H H H (139) Ir 3 H H OC 16 H 33 F H H H H (140) Ir 3 H H OCH 3 F H OCH 3 H H (141) Ir 3 H H OCH(CH 3 ) 2 H F OCH 3 H H (142) Ir 3 H H OC 10 H 21 H F NO 2 H H (143) Ir 3 H H OCH(CH 3 ) 2 H F H CF 3 H (144) Ir 3 H H SCH 3 H C 2 H 5 H H H (145) Ir 3 H OCH 2 CH═CH 2 H H C 2 H 5 H H H (146) Ir 3 H H OCH 2 C≡CCH 3 H H H H F (147) Ir 3 H H COCH 3 H H H H F (148) Ir 3 H H COCH 3 H H NO 2 H F (149) Ir 3 H H COCH 3 H H H CF 3 F (150) Ir 3 CF 3 H COCH 3 H H OCH 3 H H [0103] [0103] TABLE 8 No. M n X 1 X 2 X 3 X 4 X 5 X 6 X 7 X 8 (151) Ir 3 F H COC 9 H 19 H H H H H (152) Ir 3 H CF 3 H F H H H H (153) Ir 3 F H CF 3 H H H CF 3 H (154) Ir 3 H H CF 3 F H NO 2 H H (155) Ir 3 H H CF 3 F H OCH(CH) 2 H H (156) Ir 3 H C 3 F 7 H CF 3 H H H H (157) Ir 3 H H OCF 3 H CF 3 H H H (158) Ir 3 H OCF 3 H H C 2 H 5 H H H (159) Ir 3 H CF 3 H CF 3 H H H H (160) Ir 3 H H OCF 3 H F H CF 3 H (161) Ir 3 H H OCF 3 H H OCH 3 H F (162) Ir 3 H H OCH 2 C 3 F 7 H H H H F (163) Ir 3 H O(CH 2 ) 3 C 2 F 5 H H H H H F (164) Ir 3 H H O(CH 2 ) 3 OCH 2 C 2 F 5 Cl H H H H (165) Ir 3 H H COOC 2 H 5 F H H H H (166) Rh 3 H OCOCH 3 H H F H H H (167) Rh 3 H H O(CH 2 ) 2 C 3 F 7 H C 2 H 5 H C 5 F 11 H (168) Rh 3 H H H H H OCH 3 H F (169) Rh 3 H H H H H H CF 3 F (170) Rh 3 H H H H H H NO 2 F (171) Rh 3 H H Si(CH 3 ) 3 H H H H F (172) Rh 3 H H Si(CH 3 ) 2 C 4 H 9 H H H H F (173) Rh 3 H Si(CH 3 )C 8 H 17 H F H H H H (174) Rh 3 H H Si(C 2 H 5 ) 3 F H H H H (175) Rh 3 H H H F H Si(CH 3 )C 6 H 13 H H (176) Pd 2 H C 2 H 5 OCH 3 F H OCH 3 H H (177) Pd 2 F H F F H OCH 3 H H (178) Pd 2 F H F F H OCH 3 CF 3 H (179) Pd 2 F H Si(CH 3 ) 3 H H H Br H (180) Pd 2 F Si(CH 3 ) 2 C 7 H 15 OCH 3 H H H H H [0104] The metal coordination compound of formula (2) may generally be synthesized through the following reaction scheme. [0105] (Iridium complex) [0106] (Rhodium complex) [0107] Rh complex may be synthesized in the same manner as in Ir complex shown above. [0108] (Palladium complex) [0109] Specific and non-exhaustive examples of the metal coordination compound of formula (2) may include those (Example Compound Nos. (2-1) to (2-200) shown in Tables 9-15 wherein Ex. Comp. Nos. (2-1) to (2-200) are simply indicated as (1) to (200), respectively. [0110] In Tables 9-15, symbols A to C′ for alkylene group Y represents alkylene groups shown below. [0111] A: —CH 2 CH 2 — [0112] D: —CH 2 OCH 2 — TABLE 9 No M n Y R 1 R 2 X 1 X 2  (1) Ir 3 A — — H H  (2) Ir 3 A — — OCH 3 H  (3) Ir 3 B H — H H  (4) Ir 3 B H — OCH 3 H  (5) Ir 3 B H — H CF 3  (6) Ir 3 B H — H Cl  (7) Ir 3 B CH 3 — H H  (8) Ir 3 B CH 3 — F H  (9) Ir 3 B CH 3 — NO 2 H (10) Ir 3 B C 2 H 5 — H H (11) Ir 3 B C 3 H 7 — H CF 3 (12) Ir 3 B C 2 H 5 (CH 3 )CHCH 2 — H H (13) Ir 4 B C 6 H 13 — OCH(CH 3 ) 2 H (14) Ir 3 B C 10 H 21 — Si(CH 3 ) 3 H (15) Ir 3 C H H H H (16) Ir 3 C H H OCH 3 H (17) Ir 3 C H H H CF 3 (18) Ir 3 C H H F H (19) Ir 3 C H H NO 2 H (20) Ir 3 C H H OC 5 H 11 H (21) Ir 3 C H H O(CH 2 ) 2 C 3 F 7 H (22) Ir 3 C H H H Si(C 2 H 5 ) 3 (23) Ir 3 C H H H Br (24) Ir 3 C H H CH 3 H (25) Ir 3 C CH 3 H CH 3 H (26) Ir 3 C H CH 3 H H (27) Ir 3 C CH 3 CH 3 H H (28) Ir 3 C C 3 H 7 H Si(CH 3 ) 3 H (29) Ir 3 C H C 5 H 11 H H (30) Ir 3 C C 8 H 17 H Cl H [0113] [0113] TABLE 10 No M n Y R 1 R 2 X 1 X 2 (31) Ir 3 C C 2 H 5 C 2 H 5 H C 7 F 15 (32) Ir 3 C H C 6 H 13 NO 2 H (33) Ir 3 C C 10 H 21 H CF 3 H (34) Ir 3 C H C 9 H 19 H OC 4 H 9 (35) Ir 3 D — — H H (36) Ir 3 D — — OCH 3 H (37) Ir 3 E H — H H (38) Ir 3 E H — H NO 2 (39) Ir 3 E CH 3 — H H (40) Ir 3 E CH 3 — OCH 3 H (41) Ir 3 E CH 3 — H CF 3 (42) Ir 3 E CH 3 — NO 2 H (43) Ir 3 E CH 3 — OC 3 H 7 H (44) Ir 3 E C 2 H 5 — H H (45) Ir 3 E C 2 H 5 — H CF 3 (46) Ir 3 E C 3 H 7 — H H (47) Ir 3 E C 3 H 7 — OC 5 H 11 H (48) Ir 3 E (CH 3 ) 2 CHCH 2 CH 2 — H H (49) Ir 3 E C 5 H 11 — H C 4 F 9 (50) Ir 3 E C 6 H 13 — H H (51) Ir 3 E C 6 H 13 — H Br (52) Ir 3 E C 6 H 13 — NO 2 H (53) Ir 3 E C 8 H 17 — H H (54) Ir 3 E C 9 H 19 — OCH 2 C≡CCH 3 H (55) Ir 3 E C 10 H 21 — H H (56) Ir 3 E C 10 H 21 — OCH 2 CH═CH 2 H (57) Ir 3 F H — OCH 3 H (58) Ir 3 F CH 3 — H H (59) Ir 3 F CH 3 — OCH 3 H (60) Ir 3 F C 2 H 5 — H CF 3 [0114] [0114] TABLE 11 No M n Y R 1 R 2 X 1 X 2 (61) Ir 3 F C 6 H 13 — OCH(CH 3 ) 2 H (62) Ir 3 F C 8 H 17 — Si(CH 3 ) 2 C 8 H 17 H (63) Ir 3 G H — OCH 3 H (64) Ir 3 G H — H CF 3 (65) Ir 3 G H — O(CH 2 ) 3 OCH 2 C 2 F 5 H (66) Ir 3 G CH 3 — H H (67) Ir 3 H H H H H (68) Ir 3 H CH 3 H Si(CH 3 ) 3 H (69) Ir 3 H H CH 3 H Cl (70) Ir 3 I H H H H (71) Ir 3 I H H OCH 3 H (72) Ir 3 I H H H CF 3 (73) Ir 3 I H H H CH 3 (74) Ir 3 I C 2 H 5 H COOC 2 H 5 H (75) Ir 3 I H C 5 H 11 OCH 2 CH═CH 2 H (76) Ir 3 J H — H H (77) Ir 3 J H — NO 2 H (78) Ir 3 J CH 3 — OCH 3 H (79) Ir 3 K H — H H (80) Ir 3 K H — H Si(CH 3 ) 3 (81) Ir 3 K C 3 H 7 — H CF 3 (82) Ir 3 L H H H H (83) Ir 3 L CH 3 H SC 2 H 5 H (84) Ir 3 L H CH 3 OC 6 H 13 H (85) Ir 3 M H H H H (86) Ir 3 M C 2 H 5 H COOC 3 H 7 H (87) Ir 3 M H C 2 H 5 H O(CH 2 ) 3 C 2 F 5 (88) Ir 3 N — H H H (89) Ir 3 N — C 2 H 5 H NO 2 (90) Ir 3 N — C 6 H 13 Cl H [0115] [0115] TABLE 12 No M n Y R 1 R 2 X 1 X 2  (91) Ir 3 O H — H H  (92) Ir 3 O H — H Si(C 2 H 5 ) 3  (93) Ir 3 O C 8 H 17 — OCH(CH 3 ) 2 H  (94) Ir 3 P H — H H  (95) Ir 3 P C 3 H 7 — H COOCH 3  (96) Ir 3 P C 6 H 13 — H H  (97) Ir 3 Q H — H H  (98) Ir 3 Q C 4 H 9 — O(CH 2 ) 3 CH═CH 2 H  (99) Ir 3 R — — H H (100) Ir 3 R — — H CF 3 (101) Ir 3 S — — H H (102) Ir 3 S — — OC 2 H 5 H (103) Ir 3 T H — H Br (104) Ir 3 T C 2 H 5 — H H (105) Ir 3 U — — H H (106) Ir 3 U — — H C 7 F 15 (107) Ir 3 V H — H H (108) Ir 3 W — — OCH 2 C≡CCH 3 H (109) Ir 3 X CH 3 — H H (110) Ir 3 Z — H O(CH 2 ) 2 CH(CH 3 ) 2 H (111) Ir 3 Z — C 3 H 7 H H (112) Ir 3 A′ H H H H (113) Ir 3 B′ H — H NO 2 (114) Ir 3 B′ CH 3 — H H (115) Ir 3 C′ H C 9 H 19 OCH 3 H (116) Pt 2 A — — H H (117) Pt 2 B H — H H (118) Pt 2 B H — H C 4 F 9 (119) Pt 2 B CH 3 — OCH 3 H (120) Pt 2 B C 3 H 7 — H CF 3 [0116] [0116] TABLE 13 No M n Y R 1 R 2 X 1 X 2 (121) Pt 2 B C 8 H 17 — H H (122) Pt 2 C H H H H (123) Pt 2 C H H H CF 3 (124) Pt 2 C CH 3 CH 3 H H (125) Pt 2 C C 2 H 5 H H H (126) Pt 2 C C 10 H 21 H OCH 3 H (127) Pt 2 D — — H H (128) Pt 2 E H — H H (129) Pt 2 E CH 3 — H H (130) Pt 2 E CH 3 — H H (131) Pt 2 E CH 3 — H NO 2 (132) Pt 2 E C 6 H 13 — OC 2 H 5 H (133) Pt 2 F CH 3 — H H (134) Pt 2 F C 2 H 5 — H CF 3 (135) Pt 2 G H — H H (136) Pt 2 G H — H Si(CH 3 ) 3 (137) Pt 2 G C 4 H 9 — H (138) Pt 2 H H C 6 H 13 H H (139) Pt 2 I H H H H (140) Pt 2 I C 2 H 5 H H Si(C 2 H 5 ) 3 (141) Pt 2 J — H H H (142) Pt 2 K C 5 H 11 — H H (143) Pt 2 L C 7 H 17 H SC 2 H 5 H (144) Pt 2 N — H H H (145) Pt 2 O H — H H (146) Pt 2 P H — H H (147) Pt 2 Q H — H CH 3 (148) Pt 2 R — — H H (149) Pt 2 U — — H H (150) Pt 2 V H — NO 2 H [0117] [0117] TABLE 14 No M n Y R 1 R 2 X 1 X 2 (151) Pt 2 W — — H H (152) Pt 2 X CH 3 — H H (153) Pt 2 Z — H H H (154) Pt 2   A′ H H H H (155) Pt 2   B′ H — OCH 3 H (156) Pt 2   C′ H H H CF 3 (157) Rh 3 B H — H Br (158) Rh 3 B H — OC 6 H 13 H (159) Rh 3 B CH 3 — H H (160) Rh 3 C H H H H (161) Rh 3 C H H OCH 3 H (162) Rh 3 C H H NO 2 H (163) Rh 3 C H CH 3 H H (164) Rh 3 C C 6 H 13 H H Si(CH 3 ) 3 (165) Rh 3 D — — H H (166) Rh 3 E H — COOC 2 H 5 H (167) Rh 3 E CH 3 — H H (168) Rh 3 E CH 3 — H O(CH 2 ) 6 C 2 F 5 (169) Rh 3 E C 3 H 7 — H H (170) Rh 3 E C 10 H 21 — H H (171) Rh 3 F C 8 H 17 — H H (172) Rh 3 G H — OCH 2 CH═CH 2 H (173) Rh 3 G CH 3 — H CF 3 (174) Rh 3 H H H H H (175) Rh 3 I H H H H (176) Rh 3 K C 2 H 5 — Cl H (177) Rh 3 M H H H H (178) Rh 3 N — H H H (179) Rh 3 P CH 3 — H NO 2 (180) Rh 3 S — — H H [0118] [0118] TABLE 15 No M n Y R 1 R 2 X 1 X 2 (181) Rh 3 V H — H H (182) Rh 3 X H — SC 5 H 11 H (183) Rh 3   C′ H OC 7 H 15 H (184) Pd 2 B C 6 H 13 — H H (185) Pd 2 C H H OCH 3 H (186) Pd 2 C H H H H (187) Pd 2 D — — H H (188) Pd 2 E H — H CF 3 (189) Pd 2 E CH 3 — H H (190) Pd 2 F C 3 H 7 — H H (191) Pd 2 G H — H H (192) Pd 2 G H — Si(CH 3 ) 3 H (193) Pd 2 I CH 3 H NO 2 H (194) Pd 2 J — H H H (195) Pd 2 L H H H H (196) Pd 2 M H H C 4 F 9 H (197) Pd 2 O H — H C 4 H 9 (198) Pd 2 T H — H H (199) Pd 2 W — — OCH 3 OCH 3 (200) Pd 2   A′ CH 3 H H Cl [0119] Hereinbelow, the present invention will be described more specifically based on Examples with reference to the drawing. EXAMPLES I-1-I-10 [0120] In these examples, metal coordination compounds of formula (1) (Ex. Comp. Nos. (I-4), (I-7), (I-17), (I-18), (I-21), (I-23), (I-32), (I-56), (I-67) and (I-74) were used in respective luminescence layers for Examples I-1-I-10, respectively. [0121] Each of luminescence devices having a structure shown in FIG. 1B were prepared in the following manner. [0122] On a glass substrate (transparent substrate 15 ), a 100 nm-thick film (transparent electrode 14 ) of ITO (indium tin oxide) was formed by sputtering, followed by patterning to have an (opposing) electrode area of 3 mm 2 . [0123] On the ITO-formed substrate, three organic layers and two metal electrode layers shown below were successively formed by vacuum (vapor) deposition using resistance heating in a vacuum chamber (10 −4 Pa). [0124] Organic layer 1 (hole transport layer 13 ) (40 nm): α-NPD [0125] Organic layer 2 (luminescence layer 12 ) (20 nm): mixture of CBP: metal coordination compound of formula (1) (95:5 by weight) [0126] Organic layer 3 (electron transport layer 16) (30 nm): Alq3 [0127] Metal electrode layer 1 (metal electrode 11 ) (15 nm): Al—Li alloy (Li=1.8 wt. %) [0128] Metal electrode layer 2 (metal electrode 11 ) (100 nm): Al [0129] Each of the thus-prepared luminescence devices was taken out of the vacuum chamber and was subjected to a continuous energization test in an atmosphere of dry nitrogen gas stream so as to remove device deterioration factors, such as oxygen and moisture (water content). [0130] The continuous energization test was performed by continuously applying a voltage at a constant current density of 70 mA/cm 2 to the luminescence device having the ITO (transparent) electrode (as an anode) and the Al (metal) electrode (as a cathode), followed by measurement of luminance (brightness) with time so as to determine a time (luminance half-life) required for decreasing an initial luminance (70-120 cd/m 2 ) to ½ thereof. [0131] The results are shown in Table 16 appearing hereinafter. COMPARATIVE EXAMPLE I-1 [0132] A comparative luminescence device was prepared and evaluated in the same manner as in Example I-1 - I-10 except that the metal coordination compound of formula (1) was changed to Ir-phenylpyrimidine complex (Ir(ppy) 3 ) shown below. [0133] The results are shown in Table 16 below. TABLE 16 Luminance Ex. No. Ex. Comp. No. half-life (Hr) I-1 (I-4)  750 I-2 (I-7)  500 I-3 (I-17) 900 I-4 (I-18) 850 I-5 (I-21) 850 I-6 (I-23) 500 I-7 (I-32) 600 I-8 (I-56) 700 I-9 (I-67) 400  I-10 (I-74) 450 Comp Ex. Ir(ppy) 3 350 I-1 [0134] As is apparent from Table 16, compared with the conventional luminescence device using Ir(ppy) 3 , the luminescence devices using the metal coordination compounds of formula (1) according to the present invention provide longer luminance half-lifes, thus resulting in an EL device having a high durability (luminance stability) based on a good stability of the metal coordination compound of formula (1) of the present invention. EXAMPLES I-11-I-13 [0135] In these examples, metal coordination compounds of formula (1) (Ex. Comp. Nos. (I-1), (I-32) and (I-49) were used in respective luminescence layers for Examples I-11-I-13, respectively. [0136] Each of luminescence devices having a structure shown in FIG. 1C were prepared in the following manner. [0137] On a glass substrate (transparent substrate 15), a 100 nm-thick film (transparent electrode 14) of ITO (indium tin oxide) was formed by sputtering, followed by patterning to have an (opposing) electrode area of 3 mm 2 . [0138] On the ITO-formed substrate, three organic layers and two metal electrode layers shown below were successively formed by vacuum (vapor) deposition using resistance heating in a vacuum chamber (10 −4 Pa). [0139] Organic layer 1 (hole transport layer 13 ) (40 nm): α-NPD [0140] Organic layer 2 (luminescence layer 12 ) (20 nm): mixture of CBP: metal coordination compound of formula (1) (93:7 by weight) [0141] Organic layer 3 (exciton diffusion prevention layer 17 ) (10 nm): BCP [0142] Organic layer 4 (electron transport layer 16 ) (30 nm): Alq3 [0143] Metal electrode layer 1 (metal electrode 11 ) (15 nm): Al—Li alloy (Li=1.8 wt. %) [0144] Metal electrode layer 2 (metal electrode 11 ) (100 nm): Al [0145] Separately, each of the metal coordination compounds of formula (1) (Ex. Comp. Nos. (I-1), (I-32) and (I-49)) for the thus-prepared luminescence devices was subjected to measurement of photoluminescence spectrum in order to evaluate a luminescent characteristic of the metal coordination compounds of formula (1) (Ex. Comp. Nos. (I-1), (I-32) and (I-49)). Specifically, each of the metal coordination compounds was dissolved in toluene at a concentration of 10 −4 mol/l and subjected to measurement of photo-luminescence spectrum at 25° C. by using excited light (ca. 350 nm) and a spectrophoto-fluorometer (“Model F4500”, mfd. by Hitachi K.K.). [0146] The results are shown in Table 17 appearing hereinafter. [0147] The values of photoluminescence spectrum of the metal coordination compounds (Ex. Comp. Nos. (I-1), (I-32) and (I-49)) were substantially equivalent to those in the luminescence devices under voltage application as shown in Table 17, whereby it was confirmed that luminescence caused by the luminescence device was based on luminescence of the metal coordination compound used. [0148] EL characteristics of the luminescence devices using the metal coordination compounds of formula (1) (Ex. Comp. Nos. (I-1), (I-32) and (I-49)) were measured by using a microammeter (“Model 4140B”, mfd. by Hewlett-Packard Co.) for a current density under application of a voltage of 12 volts (current-voltage characteristic), using a spectrophotofluoro-meter (“Model SR1”, mfd. by Topcon K.K.) for a peak emission wavelength λ PE (luminescence spectrum), and using a luminance meter (“Model BM7”, mfd. by Topcon K.K.) for a luminescence efficiency (luminescence luminance). Further, an energy conversion efficiency was obtained according to the following equation: [0149] Energy conversion efficiency (lm/W) [0150] =(π×luminescence efficiency [0151] (cd/A))/applied voltage (V). [0152] All the above-prepared luminescence devices showed a good rectification characteristic. [0153] The results are shown in Table 17. COMPARATIVE EXAMPLE I-2 [0154] A comparative luminescence device was prepared and evaluated in the same manner as in Example I-2 - I-13 except that the metal coordination compound of formula (1) was changed to Ir-phenylpyrimidine complex (Ir(ppy) 3 ) shown below. [0155] The results are shown in Table 17 below. TABLE 17 Energy Ex. λPE in conversion Luminescence Comp. toluene λPE efficiency efficiency Current density Luminance Ex. No No. (nm) (nm) (Im/W) (cd/A) (mA/cm 2 at 12 V) half-life (Hr) I-11 (I-1) 522 525 4.0 13.6 170 300 I-12 (I-32) 487 525 0.4 2.4 130 400 I-13 (I-49) 537 545 2.1 7.0  25 250 Comp. Ir(ppy) 3 510 510 6.0 19.0  20 150 Ex. I-2 [0156] As shown in Table 17, compared with the luminescence device using Ir(ppy) 3 (Comparative Example I-2) showing λ PE= 510 nm, the luminescence devices using the metal coordination compound of formula (1) according to the present invention showed longer peak emission wavelengths (λ PE =525-545 nm) by 15-35 nm, thus resulting in smaller relative luminous efficiencies. [0157] Smaller energy conversion efficiencies (0.4-4.0 lm/W) and luminescence efficiencies (2.4-13.6 cd/A) of the luminescence devices of the present invention compared with those (6.0 lm/W and 19.0 cd/A) of the luminescence device using Ir(ppy) 3 may be attributable to the smaller relative luminous efficiencies due to the longer peak emission wavelengths, thus not resulting in essentially inferior luminescent characteristics of the luminescence devices using the metal coordination compound of formula (1) of the present invention. [0158] As apparent from the results of the luminance half-lifes of the luminescence devices, compared with the luminescence device using Ir(ppy) 3 showing the luminance half-life of 150 hours, the luminescence devices using the metal coordination compounds of formula (1) according to the present invention showed considerably longer luminance half-lifes of 250-400 hours. EXAMPLE I-14 (Synthesis of Ex. Comp. No. (I-1)) [0159] [0159] [0160] In a 1 liter-three necked flask, 20.0 g (126.6 mM) of 2-bromopyridine, 17.7 g (126.4 mM) of 3-fluorophenylbronic acid, 130 ml of toluene, 65 ml of ethanol and 130 ml of 2M-sodium carbonate aqueous solution were placed and stirred in a nitrogen gas stream at room temperature. Under stirring, to the mixture, 4.60 g (3.98 mM) of tetrakis (triphenyl-phosphine) palladium (0) was added, followed by heat-refluxing for 6 hours under stirring in nitrogen gas stream. [0161] After the reaction, the reaction mixture was cooled, followed by extraction with cool water and toluene. The organic layer was washed with water until the system showed neutral, followed by distilling off of the solvent under reduced pressure to obtain a residue. The residue was purified by silica gel column chromatography (eluent: toluene/ethyl acetate=5/1) to obtain 6.0 g of 2-(3-fluorophenyl)pyridine (pale brown liquid) (Yield: 34.6%). [0162] In a 100 ml-four necked flask, 50 ml of glycerol was placed and heat-stirred for 2 hours at 130-140{square root} C. while supplying nitrogen gas therein in the form of bubbles, followed by cooing to 100° C. by standing. To glycerol, 1.04 g (6.00 mM) of 2-(3-fluorophenyl)pyridine and 0.50 g (1.02 mM) of Iridium (III) acetylacetonate were added, followed by heat-refluxing for 10 hours under stirring in nitrogen gas stream. [0163] After the reaction, the reaction mixture was cooled to room temperature and poured into 300 ml of 1N-HCl. The resultant precipitate was recovered by filtration and washed with water, followed by drying for 5 hours at 100° C. under reduced pressure and purification by silica gel column chromatography (eluent: chloroform) to obtain 0.22 g of Iridium (III) tris[2-(3-fluorophenyl)pyridine] (yellow powder) (Yield: 31.0%). EXAMPLE I-15 (Synthesis of Ex. Comp. No. (I-32)) [0164] [0164] [0165] In a 1 liter-three necked flask, 20.8 g (131.6 mM) of 2-bromopyridine, 25.0 g (131.6 mM) of 3-trifluoromethylphenylbronic acid, 130 ml of toluene, 65 ml of ethanol and 130 ml of 2M-sodium carbonate aqueous solution were placed and stirred in a nitrogen gas stream at room temperature. Under stirring, to the mixture, 4.76 g (4.12 mM) of tetrakis (triphenyl-phosphine) palladium (0) was added, followed by heat-refluxing for 7 hours under stirring in nitrogen gas stream. [0166] After the reaction, the reaction mixture was cooled, followed by extraction with cool water and toluene. The organic layer was washed with water until the system showed neutral, followed by distilling off of the solvent under reduced pressure to obtain a residue (pale brown liquid). The residue was purified by silica gel column chromatography (eluent: toluene/hexane=1/1) to obtain 6.0 g of 2-(3-trifluoromethylphenyl)pyridine (pale brown liquid) (Yield: 21.1%). [0167] In a 200 ml-four necked flask, 100 ml of glycerol was placed and heat-stirred for 2 hours at 130-140° C. while supplying nitrogen gas therein in the form of bubbles, followed by cooing to 100° C. by standing. To glycerol, 2.68 g (12.0 mM) of 2-(3-trifluoromethylphenyl)pyridine and 1.00 g (2.04 mM) of Iridium (III) acetylacetonate were added, followed by heat-refluxing for 10 hours under stirring in nitrogen gas stream. [0168] After the reaction, the reaction mixture was cooled to room temperature and poured into 600 ml of 1N-HCl. The resultant precipitate was recovered by filtration and washed with water, followed by drying for 5 hours at 100°°C. under reduced pressure. The precipitate was dissolved in chloroform and the insoluble matter was removed by filtration, followed by purification by silica gel column chromatography (eluent: chloroform) and recyrstallization from a mixture solvent (chloroform/methanol) to obtain 0.62 g of Iridium (III) tris[2-(3-trifluoromethylphenyl)-pyridine] (yellow powder) (Yield: 35.3%), which showed a peak emission wavelength λ PE in toluene at 25° C. of 487 nm. EXAMPLE I-16 (Synthesis of Ex. Comp. No. (I-49)) [0169] [0169] [0170] In a 1 liter-three necked flask, 25.6 g (141.0 mM) of 2-chloro-5-trifluoromethylpyridine, 17.2 g (141.0 mM) of phenylbronic acid, 140 ml of toluene, 70 ml of ethanol and 140 ml of 2M-sodium carbonate aqueous solution were placed and stirred in a nitrogen gas stream at room temperature. Under stirring, to the mixture, 5.10 g (4.41 mM) of tetrakis (triphenyl-phosphine) palladium (0) was added, followed by heat-refluxing for 6 hours under stirring in nitrogen gas stream. [0171] After the reaction, the reaction mixture was cooled, followed by extraction with cool water and toluene. The organic layer was washed with water until the system showed neutral, followed by distilling off of the solvent under reduced pressure to obtain a residue. The residue was purified by silica gel column chromatography (eluent: toluene/hexane=5/1). The resultant creamy crystal was purified by alumina column chromatography (eluent: toluene) and recrystallized from ethanol to obtain 13.1 g of 2-phenyl-5-trifluoromethylpyridine (colorless crystal) (Yield: 41.6%). [0172] In a 200 ml-four necked flask, 100 ml of glycerol was placed and heat-stirred for 2 hours at 130-140° C. while supplying nitrogen gas therein in the form of bubbles, followed by cooing to 100° C. by standing. To glycerol, 2.68 g (12.0 mM) of 2-phenyl-5-trifluoromethylpyridine and 1.00 g (2.04 mM) of Iridium (III) acetylacetonate were added, followed by heat-refluxing for 8 hours under stirring in nitrogen gas stream. [0173] After the reaction, the reaction mixture was cooled to room temperature and poured into 600 ml of 1N-HCl. The resultant precipitate was recovered by filtration and washed with water, followed by drying for 4 hours at 100° C. under reduced pressure and purification by silica gel column chromatography (eluent: chloroform) to obtain 0.43 g of Iridium (III) tris-(2-phenyl-5-trifluoromethylpyridine) (orange powder) (Yield: 24.5%). EXAMPLE I-17 (Synthesis of Ex. Comp. No. (I-122)) [0174] [0174] [0175] In a 100 ml-three necked flask, 3.16 g (19.9 mM) of 2-bromopyridine, 3.16 g (20.0 mM) of 2,4-difluorophenylbronic acid, 15 ml of toluene, 7.5 ml of ethanol and 15 ml of 2M-sodium carbonate aqueous solution were placed and stirred in a nitrogen gas stream at room temperature. Under stirring, to the mixture, 0.72 g (0.62 mM) of tetrakis (triphenyl-phosphine) palladium (0) was added, followed by heat-refluxing for 8 hours and 40 minutes under stirring in nitrogen gas stream. [0176] After the reaction, the reaction mixture was cooled, followed by extraction with cool water and ethyl acetate. The organic layer was washed with water followed by distilling off of the solvent under reduced pressure to obtain a residue. The residue was purified by silica gel column chromatography (eluent: toluene/ethyl acetate=10/1) to obtain 3.28 g of 2-(2,4-difluorophenyl)pyridine (pale yellow oily product) (Yield: 86.0%). [0177] In a 100 ml-four necked flask, 50 ml of glycerol was placed and heat-stirred for 2 hours at 130-140° C. while supplying nitrogen gas therein in the form of bubbles, followed by cooing to 100° C. by standing. To glycerol, 0.96 g (5.02 mM) of 2-(2,4-difluorophenyl)pyridine and 0.50 g (1.02 mM) of Iridium (III) acetylacetonate were added, followed by heat-refluxing for 10 hours under stirring in nitrogen gas stream. [0178] After the reaction, the reaction mixture was cooled to room temperature and poured into 300 ml of 1N-HCl. The resultant precipitate was recovered by filtration and washed with water, followed by drying for 5 hours at 100° C. under reduced pressure and purification by silica gel column chromatography (eluent: chloroform) and recrystallization from a mixture solvent (chloroform/methanol) to obtain 0.25 g of Iridium (III) tris[2-(4,6-difluorophenyl)-pyridine] (yellow powder) (Yield: 32.1%), which showed a peak emission wavelength λ PE in toluene at 25° C. of 471 nm. EXAMPLE I-18 (Synthesis of Ex. Comp. No. (I-121)) [0179] [0179] [0180] In a 500 ml-three necked flask, 11.0 g (45.3 mM) of 5-bromo-2-fluorobenzotrifluoride and 90 ml of dry tetrahydrofuran (THF) were placed and stirred in a nitrogen gas stream at room temperature. Under stirring, to the mixture, 2.60 g (2.25 mM) of tetrakis(triphenylphosphine) palladium (0) was added, followed by cooling to 20-21° C. (inner temperature) on an ice bath in nitrogen gas stream. At that temperature, 90 ml of 0.5 M-THF solution of 2-pyridylzinc bromide was gradually added dropwise to the mixture in nitrogen gas stream, followed by stirring for 4 hours at that temperature. [0181] After the reaction, the reaction mixture was poured into cool water, followed by addition of ethyl acetate to remove the insoluble matter by filtration. The organic layer was washed with water and dried with anhydrous sodium sulfate, followed by distilling-off of the solvent under reduced pressure to obtain a residue. [0182] The residue was purified by silica gel column chromatography (eluent: hexane/ethyl acetate=20/1) to obtain 1.80 g of 2-(4-fluoro-3-trifluoromethyl-phenyl)pyridine (pale brown oily product) (Yield: 16.6%) [0183] In a 100 ml-four necked flask, 50 ml of glycerol was placed and heat-stirred for 2 hours at 130-140° C. while supplying nitrogen gas therein in the form of bubbles, followed by cooing to 100°°C. by standing. To glycerol, 1.21 g (5.02 mM) of 2-(4-fluoro-3-trifluoromethylphenyl)pyridine and 0.50 g (1.02 mM) of Iridium (III) acetylacetonate were added, followed by heat-refluxing for 10 hours under stirring in nitrogen gas stream. [0184] After the reaction, the reaction mixture was cooled to room temperature and poured into 300 ml of 1N-HCl. The resultant precipitate was recovered by filtration and washed with water, followed by drying for 5 hours at 100° C. under reduced pressure and purification by silica gel column chromatography (eluent: chloroform) and recrystallization from a mixture solvent (chloroform/methanol) to obtain 0.20 g of Iridium (III) tris[2-(4-fluoro-5-trifluoromethyl-phenyl)pyridine] (yellow powder) (Yield: 21.5%), which showed a peak emission wavelength λ PE in toluene at 25° C. of 466 nm. EXAMPLE I-19 (Synthesis of Ex. Comp. No. (I-111)) [0185] [0185] [0186] In a 500 ml-three necked flask, 11.8 g (45.5 mM) of 5-bromo-2-chlorobenzotrifluoride and 90 ml of dry tetrahydrofuran (THF) were placed and stirred in a nitrogen gas stream at room temperature. Under stirring, to the mixture, 2.60 g (2.25 mM) of tetrakis(triphenylphosphine) palladium (0) was added, followed by cooling to 13.5-14° C. (inner temperature) on an ice bath in nitrogen gas stream. At that temperature, 90 ml of 0.5 M-THF solution of 2-pyridylzinc bromide was gradually added dropwise to the mixture in nitrogen gas stream, followed by stirring for 3 hours at ca. 20° C. [0187] After the reaction, the reaction mixture was poured into cool water, followed by addition of ethyl acetate to remove the insoluble matter by filtration. The organic layer was washed with water and dried with anhydrous sodium sulfate, followed by distilling-off of the solvent under reduced pressure to obtain a residue. The residue was purified by silica gel column chromatography (eluent: hexane/ethyl acetate=10/1) to obtain 3.70 g of 2-(4-chloro-5-trifluoro-methylphenyl)pyridine (pale brown oily product) (Yield: 31.9%). [0188] In a 100 ml-four necked flask, 50 ml of glycerol was placed and heat-stirred for 2 hours at 130-140° C. while supplying nitrogen gas therein in the form of bubbles, followed by cooing to 100° C. by standing. To glycerol, 1.29 g (5.01 mM) of 2-(4-chloro-3-trifluoromethylphenyl)pyridine and 0.50 g (1.02 mM) of Iridium (III) acetylacetonate were added, followed by heat-refluxing for 8 hours under stirring in nitrogen gas stream. [0189] After the reaction, the reaction mixture was cooled to room temperature and poured into 300 ml of 1N-HCl. The resultant precipitate was recovered by filtration and washed with water, followed by drying for 5 hours at 100° C. under reduced pressure and purification by silica gel column chromatography (eluent: chloroform) and recrystallization from a mixture solvent (chloroform/hexane) to obtain 0.25 g of Iridium (III) tris[2-(4-chloro-3-trifluoromethylphenyl)pyridine] (yellow powder) (Yield: 25.4%), which showed a peak emission wavelength λ PE in toluene at 25° C. of 479 nm. COMPARATIVE EXAMPLE I-3 (Synthesis of metal coordination compound A) [0190] A metal coordination compound A (iridium (III) tris[2-(4,5-difluoromethylphenyl)pyridine described in Polymer Preprints, 41(1), pp. 770-771 (2000)) was prepared in the same manner as in Example 17 except that 2,4-difluorophenylbronic acid was changed to 3,4-difluorophenylbronic acid. [0191] The metal coordination compound A showed a peak emission wavelength λ PE in toluene at 25° C. of 505 nm. EXAMPLE I-20 AND COMPARATIVE EXAMPLE I-4 [0192] Two luminescence devices were prepared and evaluated in the same manner as in Examples I-1 to I-10 except that the metal coordination compound was changed to one (Ex. Comp. No. (122)) prepared in Example 1-18 (for Example I-20) and the metal coordination compound A prepared in Comparative Example 3 (for Comparative Example 4), respectively. [0193] The results are shown in Table 18 below. TABLE 18 Luminance Ex. No. Ex. Comp. No. half-life (Hr)  I-20 (I-122) 630 Comp. Ex. Metal 310 I-4 coordination compound A [0194] As apparent from Table 18, the luminescence device using the metal coordination compound of formula (1) according to the present invention exhibited a luminance half-life considerably longer than that of the luminescence device using the metal coordination compound A, thus resulting in an EL device excellent in durability (luminance stability). [0195] As described hereinabove, the metal coordination compound of formula (1) according to the present invention provides a higher phosphorescence efficiency and a shorter phosphorescence life and allows control of its emission wavelength by appropriately modifying the substituents X1 to X8, thus being suitable as a luminescent material for EL device. [0196] The result EL device (luminescence device) having an organic layer containing the metal coordination compound of formula (1) exhibits excellent characteristics including a high efficiency luminescence, a high luminance for a long period, and a decreased luminescence deterioration in energized state. EXAMPLES II-1-II-15 [0197] In these examples, metal coordination compounds of formula (1) (Ex. Comp. Nos. (II-10), (II-15), (II-17), (II-21), (II-39), (II-43), (II-46), (II-85), (II-96), (II-122), (II-131), (II-146), (II-163), (II-177) and (II-182) were used in respective luminescence layers for Examples II-1-II-15, respectively. [0198] Each of luminescence devices having a structure shown in FIG. 1B were prepared in the following manner. [0199] On a glass substrate (transparent substrate 15), a 100 nm-thick film (transparent electrode 14 ) of ITO (indium tin oxide) was formed by sputtering, followed by patterning to have an (opposing) electrode area of 3 mm 2 . [0200] On the ITO-formed substrate, three organic layers and two metal electrode layers shown below were successively formed by vacuum (vapor) deposition using resistance heating in a vacuum chamber (10 −4 Pa). [0201] Organic layer 1 (hole transport layer 13) (40 nm): α-NPD [0202] Organic layer 2 (luminescence layer 12 ) (20 nm): mixture of CBP: metal coordination compound of formula (2) (95:5 by weight) [0203] Organic layer 3 (electron transport layer 16 ) (30 nm): Alq3 [0204] Metal electrode layer 1 (metal electrode 11 ) (15 nm): Al—Li alloy (Li=1.8 wt. %) [0205] Metal electrode layer 2 (metal electrode 11 ) (100 nm): Al [0206] Each of the thus-prepared luminescence devices was taken out of the vacuum chamber and was subjected to a continuous energization test in an atmosphere of dry nitrogen gas stream so as to remove device deterioration factors, such as oxygen and moisture (water content). [0207] The continuous energization test was performed by continuously applying a voltage at a constant current density of 70 mA/cm 2 to the luminescence device having the ITO (transparent) electrode (as an anode) and the Al (metal) electrode (as a cathode), followed by measurement of luminance (brightness) with time so as to determine a time (luminance half-life) required for decreasing an initial luminance (60-220 cd/m 2 ) to ½ thereof. [0208] The results are shown in Table 19 appearing hereinafter. COMPARATIVE EXAMPLE II-1 [0209] A comparative luminescence device was prepared and evaluated in the same manner as in Example II-1-II-15 except that the metal coordination compound of formula (2) was changed to Ir-phenylpyrimidine complex (Ir(ppy) 3 ) shown below. [0210] The results are shown in Table 19 below. TABLE 19 Luminance Ex. No. Ex. Comp. No. half-life (Hr) II-1 (II-10) 750 II-2 (II-15) 950 II-3 (II-17) 800 II-4 (II-21) 850 II-5 (II-39) 900 II-6 (II-43) 750 II-7 (II-46) 900 II-8 (II-85) 500 II-9 (II-96) 650  II-10  (II-122) 650  II-11  (II-131) 600  II-12  (II-146) 550  II-13  (II-163) 600  II-14  (II-177) 450  II-15  (II-182) 450 Comp. Ex. Ir(ppy) 3 350 II-1 [0211] As is apparent from Table 19, compared with the conventional luminescence device using Ir(ppy) 3 , the luminescence devices using the metal coordination compounds of formula (2) according to the present invention provide longer luminance half-lifes, thus resulting in an EL device having a high durability (luminance stability) based on a good stability of the metal coordination compound of formula (2) of the present invention. EXAMPLES II-16-II-17 [0212] In these examples, metal coordination compounds of formula (2) (Ex. Comp. Nos. II-15 and II-17 were used in respective luminescence layers for Examples II-16-II-17, respectively. [0213] Each of luminescence devices having a structure shown in FIG. 1C were prepared in the following manner. [0214] On a glass substrate (transparent substrate 15 ), a 100 nm-thick film (transparent electrode 14 ) of ITO (indium tin oxide) was formed by sputtering, followed by patterning to have an (opposing) electrode area of 3 mm 2 . [0215] On the ITO-formed substrate, three organic layers and two metal electrode layers shown below were successively formed by vacuum (vapor) deposition using resistance heating in a vacuum chamber (10 −4 Pa). [0216] Organic layer 1 (hole transport layer 13 ) (40 nm): α-NPD [0217] Organic layer 2 (luminescence layer 12 ) (20 nm): mixture of CBP: metal coordination compound of formula (2) (93:7 by weight) [0218] Organic layer 3 (exciton diffusion prevention layer 17 ) (10 nm): BCP [0219] Organic layer 4 (electron transport layer 16 ) (30 nm): Alq3 [0220] Metal electrode layer 1 (metal electrode 11 ) (15 nm): Al-Li alloy (Li=1.8 wt. %) [0221] Metal electrode layer 2 (metal electrode 11 ) (100 nm): Al [0222] Separately, each of the metal coordination compounds of formula (2) (Ex. Comp. Nos. (II-15 and (II-17))) for the thus-prepared luminescence devices was subjected to measurement of photoluminescence spectrum in order to evaluate a luminescent characteristic of the metal coordination compounds of formula (2) (Ex. Comp. Nos. (II-15) and (II-17)). Specifically, each of the metal coordination compounds was dissolved in toluene at a concentration of 10 −4 mol/l and subjected to measurement of photo-luminescence spectrum at 25° C. by using excited light (ca. 350 nm) and a spectrophoto-fluorometer (“Model F4500”, mfd. by Hitachi K.K.). [0223] The results are shown in Table 20 appearing hereinafter. [0224] The values of photoluminescence spectrum of the metal coordination compounds (Ex. Comp. Nos. (II-15) and (II-17)) were substantially equivalent to those in the luminescence devices under voltage application as shown in Table 20, whereby it was confirmed that luminescence caused by the luminescence device was based on luminescence of the metal coordination compound used. [0225] EL characteristics of the luminescence devices using the metal coordination compounds of formula (1) (Ex. Comp. Nos. (I-1), (I-32) and (I-49)) were measured by using a microammeter (“Model 4140B”, mfd. by Hewlett-Packard Co.) for a current density under application of a voltage of 12 volts (current-voltage characteristic), using a spectrophotofluoro-meter (“Model SR1”, mfd. by Topcon K.K.) for a peak emission wavelength λ PE (luminescence spectrum), and using a luminance meter (“Model BM7”, mfd. by Topcon K.K.) for a luminescence efficiency (luminescence luminance). Further, an energy conversion efficiency was obtained according to the following equation: [0226] Energy conversion efficiency (lm/W) [0227] =(π×luminescence efficiency [0228] (cd/A))/applied voltage (V). [0229] All the above-prepared luminescence devices showed a good rectification characteristic. [0230] The results are shown in Table 20. COMPARATIVE EXAMPLE II-2 [0231] A comparative luminescence device was prepared and evaluated in the same manner as in Example II-16-II-17 except that the metal coordination compound of formula (1) was changed to Ir-phenylpyrimidine complex (Ir(ppy) 3 ) shown below. [0232] The results ate shown in Table 20 below. TABLE 20 Energy Ex. λPE in conversion Luminescence Comp. toluene λPE efficiency efficiency Current density Luminance Ex. No No. (nm) (nm) (Im/W) (cd/A) (mA/cm 2 at 12 V) half-life (Hr) II-16 (II-15) 524 565 0.9 7.5 70 250 II-17 (II-17) 554 565 3.4 9.6 180  300 Comp. Ir(ppy) 3 510 510 6.0 19.0  20 150 Ex. II-2 [0233] As shown in Table 20, compared with the luminescence device using Ir(ppy) 3 (Comparative Example II-2) showing λ PE =510 nm, the luminescence devices using the metal coordination compound of formula (2) according to the present invention showed longer peak emission wavelengths (λ PE =565 nm) by 55 nm, thus resulting in smaller relative luminous efficiencies. [0234] Smaller energy conversion efficiencies (0.9 -3.4 lm/W) and luminescence efficiencies (7.5-9.6 cd/A) of the luminescence devices of the present invention compared with those (6.0 lm/W and 19.0 cd/A) of the luminescence device using Ir(ppy) 3 may be attributable to the smaller relative luminous efficiencies due to the longer peak emission wavelengths, thus not resulting in essentially inferior luminescent characteristics of the luminescence devices using the metal coordination compound of formula (2) of the present invention. [0235] As apparent from the results of the luminance half-lifes of the luminescence devices, compared with the luminescence device using Ir(ppy) 3 showing the luminance half-life of 150 hours, the luminescence devices using the metal coordination compounds of formula (2) according to the present invention showed considerably longer luminance half-lifes of 250-300 hours. EXAMPLE II-18 (Synthesis of Ex. Comp. No. (II-15)) [0236] [0236] [0237] In a 5 liter-three necked flask, 169.5 g (1.28 M) of 1,2,3,4-tetrahydronaphthalene and 3 liters of acetic acid were placed and stirred at room temperature. Under stirring, to the mixture, 650 g (1.67 M) of benzyltrimethylammonium bromide and 244.8 g (1.80 M) of zinc chloride were successively added, followed by stirring for 5.5 hours at 70° C. After the reaction, the reaction mixture was cooled to room temperature and poured into 3 liters of ice water, followed by extraction with methyl t-butyl ether. The organic layer was successively washed with 5%-NaHSO 3 aqueous solution, 5%-NaOH aqueous solution and distilled water, followed by distilling-off of the solvent under reduced pressure to obtain 243.2 g of a dark brown liquid. The liquid was subjected to vacuum distillation (distillation under reduced pressure) (boiling point=108-110° C. at 667 Pa) to obtain 130.2 g of 6-bromo-1,2,3,4-tetrahydronaphthalene (Yield: 48.1%). [0238] In a 5 liter-three necked flask, 67.55 g of 6-bromo-1,2,3,4-tetrahydronaphthalene and 1480 ml of dry tetrahydrofuran (THF) were placed and cooled to −70 to −68° C. on a dry ice-acetone bath in a dry nitrogen gas atmosphere. At that temperature, to the mixture, 200 ml of 1.6 M-butyllithium solution in hexane was added dropwise, followed by stirring for 2 hours at −67° C. or below. To borate in 435 ml of dry THF was added dropwise at −70°to −68° C., followed by stirring for 2 hours at −67° C. or below. The reaction mixture was gradually warmed to room temperature and left standing overnight. The resultant reaction mixture was gradually added dropwise to a mixture of 108 ml of HCl and 438 ml of water kept at 10° C. or below, followed by stirring for 1 hour at that temperature. Thereafter, the mixture was subjected to extraction with toluene. The organic layer was washed with water, followed by distilling-off of the solvent under reduced pressure to obtain a residue. The residue was purified by silica gel column chromatography (eluent: toluene/ethyl acetate=2/1) and recrystallized from hexane to obtain 30.4 g of 1,2,3,4-tetrahydronaphthalene-6-boronic acid (Yield: 54.0%). [0239] In a 1 liter-three necked flask, 17.8 g (114 mM) of 2-bromopyridine, 20.0 g (127 mM) of 1,2,3,4-tetrahydronaphthalene-6-bronic acid, 160 ml of toluene, 80 ml of ethanol and 160 ml of 2M-sodium carbonate aqueous solution were placed and stirred in a nitrogen gas stream at room temperature. Under stirring, to the mixture, 4.05 g (3.5 mM) of tetrakis (triphenylphosphine) palladium (0) was added, followed by heat-refluxing for 7 hours under stirring in nitrogen gas stream. [0240] After the reaction, the reaction mixture was cooled, followed by extraction with cool water and toluene, and distilling off of the solvent under reduced pressure to obtain a residue. The residue was purified by silica gel column chromatography (eluent: toluene/hexane=2/1) to obtain 9.2 g of 6-(pyridine-2-yl)-1,2,3,4-tetrahydronaphthalene (yellow liquid) (Yield: 38.6%). [0241] In a 100 ml-four necked flask, 50 ml of glycerol was placed and heat-stirred for 2 hours at 130-140° C. while supplying nitrogen gas therein in the form of bubbles, followed by cooing to 100° C. by standing. To glycerol, 1.30 g (6.21 mM) of 6-(pyridine-2-yl)-1,2,3,4-tetrahydronaphthalene and 0.50 g (1.02 mM) of Iridium (III) acetylacetonate were added, followed by heat-refluxing for 5 hours under stirring in nitrogen gas stream. [0242] After the reaction, the reaction mixture was cooled to room temperature and poured into 100 ml of 1N-HCl. The resultant precipitate was recovered by filtration and washed with water, followed by washing with acetone and purification by silica gel column chromatography (eluent: chloroform) to obtain 0.14 g of Iridium (III) tris[6-(pyridine-2-yl)-1,2,3,4-tetrahydronaphthalene] (orange powder) (Yield: 16.8%). EXAMPLE II-19 (Synthesis of Ex. Comp. No. (II-17)) [0243] [0243] [0244] In a 200 ml-four necked flask, 5.16 g (28.4 mM) of 2-chloro-5-trifluoromethyl, 5.00 g (28.4 mM) of 1,2,3,4-tetrahydronaphthalene-6-bronic acid, 25 ml of toluene, 12.5 ml of ethanol and 25 ml of 2M-sodium carbonate aqueous solution were placed and stirred in a nitrogen gas stream at room temperature. Under stirring, to the mixture, 1.02 g (0.88 mM) of tetrakis (triphenylphosphine) palladium (0) was added, followed by heat-refluxing for 3.25 hours under stirring in nitrogen gas stream. [0245] After the reaction, the reaction mixture was cooled, followed by extraction with cool water and toluene, and distilling off of the solvent under reduced pressure to obtain a residue. The residue was purified by silica gel column chromatography (eluent: toluene/hexane=1/1) and alumina column chromatography (eluent: toluene) and recrystallized from methanol to obtain 3.14 g of 6-(5-trifluoro-methylpyridine-2-yl)-1,2,3,4-tetrahydronaphthalene (colorless crystal) (Yield: 39.9%). [0246] In a 100 ml-four necked flask, 50 ml of glycerol was placed and heat-stirred for 2 hours at 130-140° C. while supplying nitrogen gas therein in the form of bubbles, followed by cooing to 100° C. by standing. To glycerol, 1.72 g (6.20 mM) of 6-(5-trifluoromethylpyridine-2-yl)-1,2,3,4-tetrahydronaphthalene and 0.50 g (1.02 mM) of Iridium (III) acetylacetonate were added, followed by heat-refluxing for 7 hours under stirring in nitrogen gas stream. [0247] After the reaction, the reaction mixture was cooled to room temperature and poured into 100 ml of 1N-HCl. The resultant precipitate was recovered by filtration and washed with water, followed by washing with acetone and purification by silica gel column chromatography (eluent: chloroform) to obtain 0.11 g of Iridium (III) tris[6-(5-trifluoromethylpyridine-2-yl)-1,2,3,4-tetrahydronaphthalene] (orange powder) (Yield: 10.5%). [0248] As described hereinabove, the metal coordination compound of formula (2) according to the present invention provides a higher phosphorescence efficiency and a shorter phosphorescence life and allows control of its emission wavelength by appropriately modifying the alkylene group Y and/or substituents X1 and X2, thus being suitable as a luminescent material for EL device. [0249] The result EL device (luminescence device) having an organic layer containing the metal coordination compound of formula (2) exhibits excellent characteristics including a high efficiency luminescence, a high luminance for a long period, and a decreased luminescence deterioration in energized state.

A luminescence device is principally constituted by a pair of electrodes and an organic compound layer disposed therebetween. The layer contains a metal coordination compound represented by the following formula (1): wherein M denotes Ir, Rh or Pd; n is 2 or 3; and X1 to X8 independently denote hydrogen atom or a substituent selected from the group consisting of halogen atom; nitro group; trifluoromethyl group trialkylsilyl group having three linear or branched alkyl groups each independently having 1-8 carbon atoms; and a linear or branched alkyl group having 2-20 carbon atoms capable of including one or at least two non-neighboring methylene groups which can be replaced with —O—, —S—, —CO—, —CO—O—, —O—CO—, —CH═CH— or —C≡C— and capable of including hydrogen atom which can be replaced with fluorine atom; with the proviso that at least one of X1 to X8 is a substituent other than hydrogen atom, and X2 and X3 cannot be fluorine atom at the same time.

BACKGROUND OF THE INVENTION [0001] The use of hydrogel-based wound dressings for the promotion of wound healing is accepted clinical practice for wounds that have low to medium exudate. These dressings are typically applied to the skin as an adhesive bandage. Hydrogel-based wound dressings are cross-linked polymer gels in sheet form, having a gauze or an impervious polymer backing with an adhesive component provided for skin adhesion. Examples include, hydropolymer dressings impregnated with petroleum gauze or having water-resistant permeable polyurethane backing, paste dressings containing zinc oxide and calamine, waterproof foam dressing made of polyurethane film, gauze-based stretchable dressing, alginate-based dressings, collagen-based dressings and silver dressings. Hydrogel sheets are available from several commercial sources, including Tegagel (3M), Vigilon (Bard), Clearsite (Conmed Corporation), AQUASORB (DeRoyal), FLEXDERM (Bertek), NU-GEL (Johnson & Johnson), and CURAGEL (Kendall). These adhesive gauze or patch products, however, remain intact and have the disadvantage of being difficult to remove when peeling off from the skin. [0002] Hydrogels have also been employed to increase ocular residence time and enhance bioavailability for drugs applied to the eye. The hydrogels were found to provide better tolerability and less blurring of vision than ointments. Hydrogels used for ocular application are either pre-formed gels or are formed in situ. The pre-formed gels comprise, for example, cellulose derivatives, such as hydroxyethyl cellulose, hydroxymethyl cellulose, carboxymethyl cellulose; polyacrylic acids; cross-linked acrylic acid derivatives (carbomer); polyarcylamides; carbophil; gelatin; hyaluronic acid; polyvinyl alcohol; polyvinyl pyrrolidone; or xanthan gum. [0003] The in situ-forming gels typically comprise cellulose acetate phthalate, polaxomers, ethylene diamine derivative of polaxamine; psuedolatexes prepared by the incorporation of pilocarpine in cellulose acetate phthalate; various copolymers, such as PEO-PLLA and PEG-PLGA-PEG; cellulose acetophalate latex; Gelrite; carbopol; Matrigel; polyethylene oxide, polyoxypropylene, or gellan gum. However, most require a high (>20%) polymer concentration for in situ gel formation. Thermally gelling polymers (Poloxamer, Pluronics, PEO-PLLA diblock copolymer, PEG-PLGA-PEG triblock copolymer, and Matrigel) have a disadvantage of gelling before administration due to temperature change during packaging or storage, and can require manipulation of the temperature before administration. Furthermore, many of these polymers (e.g., Poloxamer and Pluronics) form a hydrogel which is a viscous, but still flowing solution and therefore are not readily applicable for use at a particular site on body surfaces. [0004] An in situ gelling polyvinyl alcohol (PVA)-based, fast cross-linking hydrogel system in the form of a spray, and suitable as a wound dressing, has been disclosed by Bohl Masters, et al., Wound Repair and Regeneration 10 (5), 286-294, 2002; and Bourke, et al., AAPS PharmSci 2003; 5(4) article 33. The PVA is functionalized by reacting with the acrylamide derivatives and are cross-linked by UV irradiation. The hydrogel provides a protective barrier on the skin but the cross-linking is irreversible. Accordingly, these hydrogel systems are not readily soluble and have to be peeled off to be removed them from the site. BRIEF SUMMARY OF THE INVENTION [0005] A hydrogel which can form in situ and is readily soluble, i.e., has reversible cross-linkage, can provide certain advantages as a wound dressing or drug delivery device at the site of application. These advantages include being relatively easy and painless to remove from the site of application, as well as being highly conformable to the site of application, such as a wound, the eye, or surrounding tissue. In addition, an in situ-forming hydrogel that can be administered as a spray can provide an advantageous method of application to the site. A spray-on gel for the topical delivery of drug to the eye, and having the drug or drugs linked to RGD peptides, which exhibit adhesive properties, can enhance the ocular residence time for the linked drugs. [0006] The subject invention concerns compositions, drug delivery devices and methods relating to in situ-forming hydrogels useful to form a protective covering over a wound or damaged area of the skin, such as cut or abrasion, a surgical site, or a blistered surface resulting from disease or trauma, such as a burn. An in situ-forming hydrogel composition of the subject invention can also be useful as a carrier for a drug or drugs administered by topical or transdermal application, including ocular application. The hydrogels of the subject invention can be adherent, i.e., the composition, itself, can have adherent or adhesive properties. [0007] Thus, the subject invention concerns a wound or ocular dressing comprising a first component comprising a hydrophilic polymer having a sulfhydryl, thiol, or mercaptan moiety; and a second component comprising a cross-linker, said cross-linker forming reversible cross-linkages with the hydrophilic polymer. The first and second components form a material that adheres to skin of a mammal and acts as a wound dressing. Preferably, the polymer is polyethylene glycol, and more preferably, the polyethylene glycol comprises a sulfhydryl, thiol, or mercaptan moiety to form disulfide bonds. The composition can also include a peptide, such as RGD peptide, the RGD peptide preferably being derivatized to the polyethylene glycol component. The composition can alternatively or additionally include a drug or combination of drugs or a growth factor. [0008] The subject invention also concerns a method of treatment for delivering a drug to a corneal surface of an eye. This method comprises the steps of: a. providing a reversibly cross-linked hydrogel composition of claim 14 , and b. removing the hydrogel by dissolving said cross-links in the hydrogel composition. [0011] Removal of the hydrogel dressing preferably comprises reversing the cross-links using a reducing agent wherein the reducing agent is preferably cysteine or derivatives thereof, cysteine ethyl ester, cysteine methyl ester, gluthatione, cysteine hydrocholoride, dithiothretol, N-Ethylmalemide, phosphine derivatives tetrakis-hydroxymethyl phosphonium chloride and tris-diethylaminomethyl phosphine trialkylphosphine agents, such as Tris[2-carboxyethyl] phosphine and mercaptoethanols, 2,3-dimercapto-1-propanol, dinitrobenzoic acid, a thiol, a mercaptan, a sulfite or bisulfite or ammonium or sodium salts thereof, thioglycolic acid, thiolactic acid, cysteine, thioglycerol, thioglycolic hydrazide, thioglycolamide, glycerol monothioglycolate, beta-mercapto-propionic acid, N-hydroxyethyl mercapto-acetamide, N-methyl mercapto-acetamide, beta-mercapto-ethylamine, beta-mercapto-propionamide, 2-mercapto-ethanesulfonic acid, dimercapto-adipic acid, dithiothreitol, homocysteinethiolactone, and a polythiol derivative formed by the addition of cysteamine onto a maleic anhydride-alkylvinylether copolymer, and is most preferably glutathione or cysteine. [0012] The subject invention further includes a method of preparing a cross-linked hydrogel composition for application to the skin, said method comprising: a. providing a polymer in solution, b. providing in a separate solution a cross-linker that forms reversible cross-links, c. administering both solutions concomitantly from at least one nozzle permitting mixing of the polymer and cross-linking solutions in order to provide rapid gelation of the reversibly cross-linked hydrogel at the site of administration. [0016] A preferred embodiment of a composition of the subject invention comprises novel cross-linkers, such as RGD-derivatized PEG, and further can comprise RGD-linked drug. A hydrogel composition of the subject invention can comprise additional components or ingredients, including polyvinylpyrrolidone (PVP), propylene glycol, low molecular weight PEG (<6000 Da), glycerin, or cellulose derivatives such as hydroxypropyl cellulose, hydroxylpropyl methylcellulose, methylcellulose, or the like, as necessary to provide desired properties for the hydrogel in accordance with the functionalities as recognized in the art. [0017] The polymeric PEG component of the subject composition preferably comprises a sulfhydryl, thiol, or mercaptan moiety capable of forming a reversible disulfide bond or bridge for cross-linkage of the polymer. A preferred composition of the hydrogel according to the subject invention comprises a thiol-terminated PEG and several substances that are useful for cross-linking the thiol groups. Alternately, a PEG having a maleimide, thiopyridine or vinylsulfone termination can be used. At physiological pH and temperatures, cross-linking of PEG into a hydrogel can occur in about 1-3 minutes. The use of PEG offers several other advantages, including its chemoselective properties, its capability to form reversible and non-reversible cross-links, its free thiol group for covalently linking to drug, its property of blocking proteolytic enzymes and immune system components that can cause an inflammatory reaction, and its commercial availability in numerous forms. [0018] More preferably, the sulfhydryl or thiol or mercaptan-terminated PEG can reversibly bond to a sulfur-terminated moiety of a peptide, such as a peptide comprising the amino acid chain Arg-Gly-Asp (RGD) or a sulfur-containing amino acid, such as Cys. Thus, one preferred peptide used in accordance with the subject invention comprises Cys attached to the Asp amino acid of the RGD peptide. Use of a PEG-based polymer allows the hydrogel to be functionalized using these peptides to enhance the wound healing and the adhesive properties of the gel. Peptides typically used for this purpose include those having the sequence ‘Arg-Gly-Asp,’ or RGD, in cyclic or linear form. The heretofore undisclosed PEG polymers derivatized to include RGD peptide useful as cross-linker in a spray-on gel can advantageously provide bioadhesive and wound-healing properties to the formed hydrogel. [0019] In a preferred wound dressing embodiment of the subject invention, the PEG and cross-linker can be provided as separate solutions, being mixed during administration to the site, for example, provided as streams of solutions from separate sources or containers and administered simultaneously, allowing the gel and cross-linker solutions to mix together during administration, so that the cross-linked gel matrix sets in less than 30 minutes, and preferably less than 10 minutes. The disulfide bonds of the resultant cross-linked hydrogel matrix can provide the support to maintain the integrity of the gel, as well as the capability to adsorb into the gel the exudate from the wound or other site. The cross-linking within the polymeric composition can be readily reversed using a reducing agent. Such spray-on hydrogels having reversible cross-links for advantageous application to skin have not been previously disclosed. A preferred object of the invention is to provide enhanced patient compliance for a wound dressing by applying a hydrogel having reversible cross-links, e.g., cross-links containing disulfide bridges, so that the hydrogel wound dressing can be readily washed off by dissolution of the hydrogel rather than physical removal, such as peeling off, of the intact dressing. [0020] The drugs and other active components used in accordance with the subject invention can be dissolved or dispersed in the cross-linked polymeric matrix. Drugs which can provide anesthetic, antimicrobial, or wound healing properties are preferred for use in an embodiment directed to a protective covering for a wound. Alternatively, the drugs can be linked to an RGD peptide derivatized onto the PEG polymer. [0021] Another feature of the present invention is that hydrogel, cross-linked with RGD derivatized PEG cross-linker, can provide dermal retentive properties when applied to the skin, thereby providing prolonged release properties for the drug released from the hydrogel. This embodiment of a hydrogel of the subject invention can also enhance the cell adhesion of the drugs onto a corneal surface. [0022] The subject invention preferably comprises a hydrogel which is formulated to be applied or administered, preferably as a liquid and more preferably as a spray, wherein the formed gel comprises a reversibly cross-linked polymeric matrix or network. The cross-linking component is also preferably formulated as a liquid and more preferably as a spray. The hydrogel and cross-linking components are therefore preferably applied concomitantly as separate liquids and more preferably administered as a spray wherein the two liquids are mixed during the application thereof. [0023] By comprising a reversible cross-link, the hydrogel is soluble, and can be dissolved and easily removed from the site rather than requiring the gel to be removed intact, e.g., peeled, from the skin. More preferably, the spray formulation for the gel of the subject invention comprises cross-linked, water-soluble polyethylene glycol (PEG) polymers. PEG is advantageously a hydrogel-forming component that is well known for its safe and non-toxic properties. [0024] It is yet another object of the present invention to provide a rapidly gelling hydrogel network which can be sprayed into the eye to treat inflammation, allergic response or to treat infection. Further, the spray gel can be applied onto a wound or other traumatized area of the skin to aid the healing process. Preferably, gelation should occur in less than 30 minutes, more preferably within about 10 minutes, and most preferably in less than about 4 minutes. It is still another object of the invention to provide an in situ-forming hydrogel which results in gelation in less than one minute. [0025] It is another object of the present invention to provide a spray-on hydrogel system comprising a dual-source nozzle, such as a dual barrel syringe or a pressurized spray can, capable of concomitant spraying of a stream of polymeric solution and a stream of cross-linker solution. This spray-on hydrogel system can provide advantageous topical delivery to the eye or skin of an in situ-forming hydrogel containing a drug or drugs. [0026] A further object of the invention is to provide a controlled-release drug delivery system comprising a hydrogel wherein the drug or drugs are delivered from or through the hydrogel composition for a sustained or extended period of time. Preferably, the drug or drugs can be linked to RGD peptides incorporated into a PEG-based hydrogel. Linkage of drug to the RGD peptide component of the hydrogel can increase residence time in the ocular region or on the skin cells to increase their residence time at the site of application, thereby providing relatively high local concentrations and prolonged release and action of the drug or drugs. [0027] Yet another object of the invention is to provide a kit for applying a wound or ocular dressing or a hydrogel capable of delivering drug to the site of application. The kit can comprise a polymer-forming composition and a reversible cross-linking composition, wherein the polymer-forming and cross-linking compositions can be mixed to form a reversible, cross-linked hydrogel which rapidly gels to form a wound dressing or drug delivery device at the site of application. The kit can also include a composition containing drug, growth factor or other wound-healing enhancer, either separate from the polymer-forming composition and the cross-linking composition, or drug can be incorporated into either of these compositions. In addition, the kit can comprise a separately contained reducing agent to reverse the cross-linkage of the formed hydrogel, thereby providing a means for dissolving the hydrogel for its easy removal from the site without having to remove the hydrogel intact. BRIEF DESCRIPTION OF THE DRAWINGS [0028] FIG. 1 depicts formation of disufide bridges (cross-links) leading to hydrogel based on 8-armPEG-SH and 8-armPEG-S-TP (thiopyridine). [0029] FIG. 2 depicts formation of disufide bridges (cross-links) leading to hydrogel based on 4-armPEG-SH and 4-armPEG-S-TP (thiopyridine). [0030] FIG. 3 depicts formation of disufide bridges (cross-links) leading to hydrogel based on 8-armPEG-SH and 4-armPEG-S-TP (thiopyridine). [0031] FIG. 4 depicts formation of disufide bridges (cross-links) leading to hydrogel based on 4-armPEG-SH and 8-armPEG-S-TP (thiopyridine). [0032] FIG. 5 depicts formation of disufide bridges (cross-links) leading to hydrogel based on 4-armPEG-SH and H 2 O 2 [0033] FIG. 6 depicts formation of disufide bridges (cross-links) leading to hydrogel based on 8-armPEG-SH and H 2 O 2 . [0034] FIG. 7 depicts formation of thioether bonds (cross-links) leading to hydrogel based on 8-armPEG-SH and BMPEO 3 . [0035] FIG. 8 depicts formation of thioether bonds (cross-links) leading to hydrogel based on 8-armPEG-SH and BMPEO 2 . [0036] FIG. 9 depicts formation of hydrogel from a dual barrel syringe containing a polymer component and a cross-lining component in the respective barrels. [0037] FIG. 10 depicts removal of the gel using the reducing agent solution to cleave the disulfide bonds. [0038] FIG. 11 shows the DSC results for the melting of the 8-arm PEG-S-TP product. [0039] FIG. 12 depicts attaching the RGD peptide on the 8-arm-Peg-SH. [0040] FIG. 13 shows the DSC results for the melting of the RGD attached at 5 sites of 8-arm PEG-S-TP. [0041] FIG. 14 shows the DSC results for the melting of the RGD attached at 2 sites of 8-arm PEG-S-TP. [0042] FIGS. 15A and 15B shows the Rheology of hydrogels of 8-arm Peg-SH and H 2 O 2 in buffer (A) and Rheology of hydrogel with additives (B). [0043] FIGS. 16A and 16B shows the Rheology of hydrogels of 8-arm Peg-SH and 8-arm Peg-S-TP in buffer (A) and Rheology of hydrogel with additives (B). [0044] FIG. 17 shows the ESI-MS spectrum of the Olvanil-Cysteine product. [0045] FIG. 18 shows the MALDI-TOF spectrum of the PEG-Olvanil-Cysteine product. DETAILED DESCRIPTION OF INVENTION [0046] The subject invention concerns a composition comprising a drug or other active ingredient, a polymeric hydrogel-forming component and a cross-linker, providing in situ formation of the hydrogel when sprayed topically onto an area of the body. The subject hydrogel composition advantageously has bioadhesive properties and reversible cross-links. [0047] A preferred embodiment of the subject composition comprises a poly(ethylene glycol), or PEG, hydrogel that, when applied topically, provides an adhesive gel which adheres well to a body surface such as the cornea or the skin. Further, the subject composition can provide modulated drug release from the hydrogel so that drug can be released over a prolonged period of time, e.g., several hours or days, or up to about a week. The hydrogel composition of the subject invention preferably comprises RGD peptide-derivatized components, including (a) RGD peptide linked to the PEG to provide cell adhesive and wound-healing properties for the composition, or (b) RGD peptide linked to a drug or drugs used in the compositions to provide increased retention of drug at site of application and for prolonged release of drug to promote or enhance wound healing. By “RGD peptide”, it is meant a peptide comprising RGD. [0048] In a preferred use, the polymeric hydrogel and cross-linker are formulated as separate solutions and concomitantly introduced, e.g., sprayed, onto the target site such that the polymer and cross-linker solutions adequately mix to form in situ a cross-linked hydrogel network or matrix. Active drug or drugs can be incorporated into one or both of the solutions, and are preferably linked to the hydrogel forming polymer through an RGD peptide linkage wherein the RGD peptide is incorporated or derivatized into the polymer. The cross-linked hydrogel so formed can provide a protective barrier on an injured or affected area, thereby serving as a wound dressing, or can provide a composition for topical drug delivery. [0049] Preferably, the hydrogel base comprises PEG (polyethylene glycol) or PEG derivatives. A hydrogel formed from PEG is advantageously flexible, elastic and strong, enabling attachment on the eye, skin and or injured parts thereof. In addition, certain derivatized PEGs, such as PEGs derivatized with an RGD peptide, can enhance wound healing, anchor onto the injured site and deliver the drugs for extended periods of time ranging from hours, to days, or up to about a week. A PEG-based hydrogel is highly permeable, allowing diffusion of incorporated drugs, salts, water and gases. Satisfactory gel formation can be achieved using a ratio of polymer to cross-linker from about 5:1 to about 1:5. The concentration of PEG can be varied from about 2% to about 30% (w/w) in the hydrogel, and in certain embodiments is preferably about 8% to about 10%. The polymer and cross-linker are preferably dissolved in buffer in the pH range 4-9 and preferably in the pH range 5-8 to obtain the gels. [0050] The hydrogel composition, such as PEG-based composition, can provide a platform technology suitable for use with various types of drugs to be delivered. The drugs can be either physically entrapped or modified drugs with cleavable bonds can be physically incorporated or covalently linked into the hydrogel to provide controlled release, which is otherwise not possible for highly hydrophilic drugs which traverse easily through the gel. [0051] A composition according to the present invention can also be applied to skin for burns associated with fire, sunburn and chemical irritants, as well as physical injuries such as bed sores by providing a scaffold for seeding and repair of the damaged skin. A distinctive feature of the hydrogel of the subject invention is the formulation of reversible cross-linking such that the hydrogel matrix can be dissolved and readily washed off. This feature can advantageously minimize disruption of newly formed skin when removing the reversibly cross-linked hydrogel dressing, offering advantages over the typical gel bandages, which are required to be physically removed intact, e.g., by peeling off of the dressing, which can cause discomfort or further trauma to the wound site. [0052] The hydrogel composition can further comprise one or more drugs for delivering drug for treatment at the site. The drug or drugs can be physically entrapped within the matrix of the formed hydrogel or can be covalently linked to hydrogel, such as by the RGD peptide. Such drug or drugs can be wound healing enhancers, such as RGD peptides, antiseptics or antibiotics, anti-inflammatories, anesthetics, pain relievers, or drugs useful for in situ treatment, such as drugs for treating glaucoma at an ocular site, and growth factors. These drugs include, but are not limited to lidocaine, benzocaine, butamben, dibucaine, oxybuprocaine, pramoxine, proparacaine, proxymetacaine, novocaine, procaine, tetracaine, doxycycline, minocycline, oxytetracycline, sancycline, dedimethylamino tetracycline, indomethacin, diclofenac, ibuprofen, naproxen, ketoprofen, dexamethasone, a vallinoid, olvanil, capsaicin, benzalkonium chloride, an antiglaucoma medication, pilocarpine, timolol, levobunolol, betaxolol, or carbacol. The invention is not limited to the use of the drugs mentioned above and can be extended to other therapeutic agents which aid in wound healing processes when used for topical skin delivery or drugs used in ocular treatments, such as drugs used to treat glaucoma. [0053] Alternatively, or in addition to comprising a drug or drugs, a hydrogel of the subject invention can include a growth factor for promoting wound healing. The growth factors useful in accordance with the subject invention include the cytokines such as epidermal growth factor (EGF), including all members of the EGF family of proteins having one or more repeats of the conserved amino acid sequence: CX7CX4-5CX10-13CXCX8GXRC (where X represents any amino acid), transforming growth factor alpha (TGF-alpha), Transforming Growth Factor beta (TGF-b), keratinocyte growth factor (KGF-2), fibroblast growth factor fibronectin, fibrinogen, Granulocyte-Monocyte Colony Stimulating Factor (GM-CSF) and platelet-derived growth factor (PDGF). [0054] The subject invention preferably comprises a hydrogel which is formulated to be applied or administered, preferably as a liquid and more preferably as a spray, wherein the formed hydrogel comprises a reversibly cross-linked polymeric matrix or network. By comprising a reversible cross-link, the hydrogel is soluble, and can be dissolved and easily removed from the site rather than requiring the gel to be removed intact, e.g., peeled, from the skin. The cross-linking within the polymeric composition can be readily reversed using a reducing agent. For purposes of the subject invention, substances that have the ability to reduce other substances are said to be reductive and are known as reducing agents, reductants, or reducers. As is well-known in the art, reducing agents can transfer electrons to another substance, and is thereby, itself, oxidized. Because reducing agents “donate” electrons, they are also called electron donors. [0055] The reduction of a typical disulfide bond, as in an embodiment of the subject invention, proceeds by two sequential thiol-disulfide exchange reactions. Thiol-disulfide exchange is the principal reaction by which disulfide bonds are formed and rearranged. Disulfide reshuffling is a faster reaction. Thiol-disulfide exchange is a chemical reaction in which a thiolate group S— attacks a sulfur atom of a disulfide bond —S—S—. The original disulfide bond is broken, and its other sulfur atom is released as a new thiolate, carrying away the negative charge. Meanwhile, a new disulfide bond forms between the attacking thiolate and the original sulfur atom. The transition state of the reaction is a linear arrangement of the three sulfur atoms, in which the charge of the attacking thiolate is shared equally. The protonated thiol form —SH is unreactive, i.e., thiols cannot attack disulfide bonds, only thiolates. Typically, the thiolate of a redox reagent such as glutathione or dithiothreitol attacks the disulfide bond. [0056] The several reducing agents that either block or reverse the disulfide bridges forming the cross-linkage in accordance with the subject invention include cysteine, cysteine ethyl ester, and cysteine methyl ester, gluthatione, cysteine hydrocholoride, dithiothretol, N-Ethylmalemide, phosphine derivatives tetrakis-hydroxymethyl phosphonium chloride and tris-diethylaminomethyl phosphine trialkylphosphine agents, such as Tris[2-carboxyethyl] phosphine and mercaptoethanols, 2,3-dimercapto-1-propanol, and dinitrobenzoic acid. The reducing agents appropriate for use in accordance with the subject invention are not limited to these and can be any compound having thiols or mercaptan groups as well as sulfites and/or bisulfites. Mercaptans and thiols which can be used to reverse the disulfide linkages in a reversibly cross-linked hydrogel of the subject invention include thioglycolic acid, thiolactic acid, cysteine, thioglycerol, thioglycolic hydrazide, thioglycolamide, glycerol monothioglycolate, beta-mercapto-propionic acid, N-hydroxyethyl mercapto-acetamide, N-methyl mercapto-acetamide, beta-mercapto-ethylamine, beta-mercapto-propionamide, 2-mercapto-ethanesulfonic acid, dimercapto-adipic acid, dithiothreitol, homocysteinethiolactone, cysteine derivatives, and polythiol derivatives formed by the addition of cysteamine onto a maleic anhydride-alkylvinylether copolymer. The sulfites and/or bisulfites which can be used are the sodium and ammonium salts. [0057] Preferred reducing agents of the present invention are cysteine or cysteine derivatives and glutathione. Various concentrations of these agents will be effective in degrading the hydrogel matrix. The higher the concentration, the faster the degradation. However, the lowest effective concentration is preferably used in order to minimize adverse tissue reactions. [0058] A hydrogel composition of the present invention is further suitable for application as an ocular gel. A hydrogel composition of the subject invention can comprise an RGD-containing peptide having bioadhesive properties, linked to the polymeric (e.g., PEG) component for enhancing the adhesion to the cells. Further, RGD-linked drugs incorporated in the gels provide prolonged ocular residence times, enhancing the ocular bioavailability of the drugs. Examples of the Preferred Embodiments, Including Best Mode [0059] Examples of the compositions, components thereof, and properties of embodiments of the subject invention are provided hereinbelow Example 1 Hydrogel Formation [0060] The hydrogel network or matrix composition is obtained by formation of disulfide bridges or formation of thioether bonds in the PEG (polyethylene glycol) having a thiol group (reduced sulfhydryls groups ‘SH’) at each terminus. The cross-linking of PEG with thiol terminal groups is achieved by reacting the same with H 2 O 2 , maleimide cross-linkers (like bis-maleimido di/triethylene glycol derivatives eg. BMPEO 2 (bis-maleimido diethylene glycol) and BMPEO 3 (bis-maleimido triethylene glycol) BMOE (Bis-Maleimidoethane), BMH (bismaleimidohexane)) or PEG having a thiopyridine (TP) groups at the terminus or PEG having vinyl sulfone terminal groups or any other compound capable of forming the disulfide or thioether bonds with ‘SH’ terminated PEGs. The PEG polymers having thiol terminus groups include 2-, 3-, 4-, 8-arm or multiple arm thiol PEGs in the molecular weight range of 2,000 to 100,000 Da. Alternately the hydrogels can be obtained by cross-linking the PEG having a maleimide or thiopyridine terminated groups with compounds having thiol functionality. [0061] A. Thiol-Terminated Polymer and Hydrogen Peroxide Cross-Linker [0062] One of the embodiments of the present invention includes the gels based on thiol terminated PEGs (e.g., 8-arm-PEG-SH) cross-linked with H 2 O 2 . The in situ forming hydrogel was obtained by spraying the solution of the thiol terminated PEG and the cross linker: H 2 O 2 , in phosphate buffer pH 8 from a dual barrel syringe to obtain the hydrogel. [0063] Formulations according to the subject invention, having various concentrations of hydrogel component, mixed with varying volumes of 3% H 2 O 2 as a cross-linker, and their relatively rapid gelling time, are shown in Tables 1-3. [0000] TABLE 1 Hydrogel (6% w/v) with H 2 O 2 as cross-linker pH = 8 8 PBS Equiv- Arm- Buffer 3% H 2 0 2 alence of Gelling PEG- Volume Volume H 2 0 2 for Excess of Time SH In μL In μL one SH H 2 0 2 in Sec 10 mg 166 μL 33.2 μL 6.6 5.6 30 (0.9 μL H 2 0 2 ) 10 mg 166 μL 16.6 μL 3.3 2.3 33 (0.45 μL H 2 0 2 ) 10 mg 166 μL 8.3 μL 1.65 0.65 36 (0.22 μL H 2 0 2 ) 10 mg 166 μL 4.15 μL 0.82 (−0.18) 40 (0.11 μL H 2 0 2 ) [0000] TABLE 2 Hydrogel (3% w/v) with H 2 O 2 as cross-linker pH = 8- 8 PBS arm- Buffer 3% H 2 0 2 Equiv- PEG- Volume Volume alence of Excess of Gelling SH In μL In μL H 2 0 2 H 2 0 2 Time 5 mg 166 μL 33.2 μL 13.2 12.2 32 Sec (0.9 μL H 2 0 2 ) 5 mg 166 μL 16.6 μL 6.6 5.6 50 Sec (0.45 μL H 2 0 2 ) 5 mg 166 μL 8.3 μL 3.3 2.3 68 Sec (0.22 μL H 2 0 2 ) 5 mg 166 μL 4.15 μL 1.65 0.65 2.4 min (0.11 μL H 2 0 2 ) [0000] TABLE 3 Hydrogel (1.5% w/v) with H 2 O 2 as cross-linker pH = 8- 8 PBS arm- Buffer 3% H 2 0 2 Equiv- PEG- Volume Volume alence of Excess of Gelling SH In μL In μL H 2 0 2 H 2 0 2 Time 2.5 mg 166 μL 33.2 μL 26.4 25.4 38 Sec (0.9 μL H 2 0 2 ) 2.5 mg 166 μL 16.6 μL 13.2 12.2 110 Sec (0.45 μL H 2 0 2 ) 2.5 mg 166 μL 8.3 μL 6.6 5.6 4.20 min (0.22 μL H 2 0 2 ) 2.5 mg 166 μL 4.15 μL 3.3 2.3 6.0 min (0.11 μL H 2 0 2 ) [0064] B. Thiol Terminated Polymer and Maleimide Cross-Linker. [0065] Another embodiment of the present invention includes hydrogels of thiol terminated PEGs (e.g. 8-arm-PEG-SH) cross-linked with maleimide cross-linkers. The in situ forming hydrogel was obtained by mixing the solutions of the thiol terminated PEG and the cross-linker having a maleimide termination BMPEO 3 (bis-maleimido triethylene glycol) in phosphate buffer pH 5.38 and 7.4 to obtain the hydrogels. The hydrogel forms by the formation of the thioether bonds and gels almost instantaneously as shown in Table 4. [0000] TABLE 4 Hydrogel (4% w/v) with BM(PEO) 3 as cross-linker 8-Arm- BM(PEO) 3 PB Glycerin Gelling S. No PEG-SH wt pH % Time 1 8 mg 2 mg 5.38 25 10 sec 2 8 mg 2 mg 5.38 50 10 sec 3 8 mg 2 mg 7.4 25  2 sec 4 8 mg 2 mg 7.4 50  2 sec [0066] C. Sulfhydryl-Terminated Polymer and Thiopyridine Cross-Linker. [0067] Yet another embodiment of the present invention is a gel based on the 4-arm-PEG-SH and 8-arm-PEG-SH cross-linked with 4-arm and 8-arm-PEG respectively having thiopyridine terminal groups. The thiol terminated PEG (4 and 8-arm PEG-SH) is treated with three fold excess of dithiodipyridine (aldrithiol) in alcohol under mild acidic conditions overnight at room temperature. The product, a thiopyridine terminated PEG (4 arm PEG-S-TP and 8-arm PEG-S-TP) so obtained is purified using the size exclusion chromatography. This PEG-S-TP product is used for the gel formation. [0068] NMR for the Thiopyridine Terminated PEG. [0000] PEG-SH: 1H-NMR (CDCl 3 , 500 MHz) δ 3.50 (t, 2H, J=2, 4 Hz, OCH 2 ) 3.60-3.67 (m, nH, OCH 2 —CH 2 —O) PEG-S-TP: 1H-NMR (CDCl 3 , 500 MHz) δ 3.17 (t, 1H, J=2, 4 Hz, —CH—S-TP) 3.50 (t, 2H, J=2, 4 Hz, OCH 2 ) 3.60-3.67 (m, nH, OCH 2 —CH 2 —O), 3.8 (t, 1H, J=2, 4 Hz, —CH—S-TP) 7.64 (t, 1H, J=2.4 Hz, Ar) 8.40 (t, 1H, J=2.6 Hz, Ar) 8.47 (d, 1H, J=3 Hz, Ar) 8.62 (d, 1H, J=3 Hz, Ar). [0069] The in situ forming hydrogel was obtained by spraying the solution of the thiol terminated PEG and the cross-linker: having a thiopyridine termination developed in-house, from a dual barrel syringe to obtain the hydrogel. The solution of polymer and cross-linker were made in phosphate buffer pH 8. The formulation comprising PEG with 4 and 8 terminal thiol groups, respectively, was used for the formation of hydrogel as shown in Table 5. The thiopyridine terminated cross-linker was obtained from the 4- and 8-arm thiol terminated PEG, respectively, as also shown in Table 5. [0000] TABLE 5 Hydrogel with PEG-S-TP as cross-linker Concen- tration of polymer Gelation S. No Composition (% w/v) Ratio Time 1 4-arm-PEG-S-TP + 8 1:1 15-30 sec 4-arm-PEG-SH 6 1:1 15-30 sec 5 1:1 15-30 sec 2 8-arm-PEG-S-TP + 8 1:1 15-30 sec 8-arm-PEG-SH 6 1:1 15-30 sec 5 1:1 15-30 sec 3 8-arm-PEG-S-TP + 8 1:1 15 sec 4-arm PEG-SH 6 1:1 15 sec 5 1:1 15 sec 4 4-arm-PEG-S-TP + 8 1:1 15 sec 8-arm PEG-SH 6 1:1 15 sec 5 1:1 15 sec [0070] The concentration of the polymer solution and the cross-linker was varied to yield the hydrogel almost instantaneously, as shown in Table 6. The hydrogel is obtained by the formation of the disulfide bridges either inter or intramolecular in the thiol terminated PEG. [0000] TABLE 6 Hydrogel with PEG-S-TP as cross-linker (different ratios) 8-arm PEG-SH (compound A) + 8-arm PEG-S-TP (compound B) Compound Ratio Gelling S. No % w/v A:B time 1 8 1:1 20-30 sec 2 8 2:1 20-30 sec 3 8 1:2 20-30 sec 4 6 1:1 30 sec 5 6 2:1 30 sec 6 6 1:2 30 sec 7 5 1:1 30 sec 8 5 2:1 30 sec 9 5 1:2 30 sec Example 2 Adhesion [0071] To enhance the adhesion of the gel to eye and the skin the cell adhesive component is incorporated in the gel. Accordingly, one of the embodiments of the present invention discloses the use of the peptide sequence, Arg-Gly-Asp (RGD), which is naturally present in many proteins involved in adhesion of cells to other cells and to basement membrane. As a result of better contact, this provides better transfer of a drug from the gel to the site of application. Furthermore, the presence of RGD sequences can be recognized by cellular receptors, thereby serving as attachment sites on the corneal epithelial cells or keratinocytes cells on the skin. The RGD is known to accelerate skin and wound repair. [0072] RGD peptide comprising the ‘Arg-Gly-Asp’ sequence, such as the linear peptide Arg-Gly-Asp-Cys, Gly-Arg-Gly-Asp-Ser, Gly-Arg-Gly-Asp-Ser-Pro, or as the cyclic peptide Cyclo-Arg-Gly-Asp-Try-Lys, were used to enhance the adhesion of the gel on the cells and were synthesized as described below. [0073] Synthesis of the RGD Derivatized PEG Cross-Linker: Step 1: The thiol terminated PEG (8-arm PEG-SH) (1 g) was treated with three fold excess of dithiodipyridine (aldrithiol) (3 g) in alcohol (methanol, 20 ml) under mild acidic conditions overnight at room temperature. The DSC results for the melting of the 8-arm PEG-S-TP product are shown in FIG. 11 . Step 2: The thiopyridine terminated PEG obtained from Step 1 was reacted with the RGD peptide having Arg-Gly-Asp-Cys sequence ( FIG. 12 ). The thiopyridine terminated PEG was reacted with the RGD peptides in alcohol under mild basic conditions. The amount of RGD is taken proportional to the sites at which it is required to be appended e.g., the 8-arm PEG-TP (200 mg) was reacted with 1 equivalent of RGD to appended the RGD on one arm (36 mg), and the 8-arm PEG-TP (200 mg) was reacted with 3 equivalents of RGD (108 mg) to appended the RGD on three arms. The DSC for the RGD-PEG-S-TP is shown in FIGS. 13 and 14 . [0076] The hydrogel was obtained by spraying the solution of thiol terminated PEG (8-armPEG-SH) and the cross-linker consisting of PEG having partial thiopyridine and RGD terminal groups (RGDC-8-armPEG-S-TP), in phosphate buffer pH 8. The hydrogel composition is shown in Table 7. [0000] TABLE 7 Hydrogel compositions having Adhesive RGD peptide % w/v of polymers in PB Gelling S. No. Polymers (pH 8) Ratio time 1 8-armPEG-SH + 5 1:1 ~10 min 2 RGDC-8-armPEG-STP 6 1:1 ~10 min 3 (5arm) 8 1:1 ~6 min 4 8-armPEG-SH + 5 1:1 ~6 min 5 RGDC-8-armPEG-STP 6 1:1 ~5 min 6 (2arm) 8 1:1 ~5 min 7 8-armPEG-SH + 5 1:1 ~4 min 8 RGDC-8-armPEG-STP 6 1:1 ~3 min 9 (1arm) 8 1:1 ~3 min [0077] In another embodiment of the invention, a spray-on hydrogel was obtained by spraying the solution of thiol terminated PEG (8-arm PEG-SH) and along with the cross-linker solution consisting of (a) thiopyridine terminated PEG (8-arm PEG-S-TP) and (b) PEG having partial thiopyridine and RGD terminal groups (RGDC-8-armPEG-S-TP). The solution of polymer and cross-linker were mixed in phosphate buffer pH 8. The hydrogel results instantaneously. The hydrogel compositions are shown in Table 8. [0000] TABLE 8 Hydrogel compositions with Adhesive (RGD peptide) % w/v polymer A and (B + C) in Ratio Ratio Gelling Polymer A Polymer B Polymer C PB (pH 8) A:B + C B:C time 8-armPEG- RGDC-8- 8-arm PEG- 5 1:1 1:1 ~30-40 sec SH arm PEG- STP 6 1:1 1:1 ~30-40 sec STP (5arm) 8-armPEG- RGDC-8- 8-arm PEG- 5 1:1 1:1 ~30-40 sec SH arm PEG- STP 6 1:1 1:1 ~30-40 sec STP (2arm) 8-armPEG- RGDC-8- 8-arm PEG- 5 1:1 1:1 ~30-40 sec SH arm PEG- STP 6 1:1 1:1 ~30-40 sec STP (1arm) Example 3 Formulations with Additives [0078] A spray-on hydrogel was obtained by dissolving the thiol terminated PEG (4-arm-PEG-SH and 8-arm PEG-SH) and the thiopyridine terminated PEG (4-arm-PEG-S-TP and 8-arm PEG-S-TP) (Formulation in accordance with Example 1c), and an additive comprising a solution of polyvinyl pyrrolidone (PVP) in phosphate buffer pH 8. The concentration of PVP was varied from 1.5-2% w/v as shown in Table 9. [0000] TABLE 9 Hydrogel Compositions with additive PVP Conc. Conc. Of Ratio of Of PVP polymers S. No Compositions polymers (% w/v) (% w/v) 1 4-arm-PEG-S-TP + 1:1 — 5 4-arm-PEG-SH 8-arm-PEG-S-TP + 1:1 — 5 8-arm-PEG-SH 8-arm-PEG-S-TP + 1:1 — 5 4-arm PEG-SH 2 4-arm-PEG-S-TP + 1:1 1.5 5 4-arm-PEG-SH 8-arm-PEG-S-TP + 1:1 8-arm-PEG-SH 8-arm-PEG-S-TP + 1:1 4-arm PEG-SH 3 4-arm-PEG-S-TP + 1:1 2 5 4-arm-PEG-SH 8-arm-PEG-S-TP + 1:1 8-arm-PEG-SH 8-arm-PEG-S-TP + 1:1 4-arm PEG-SH [0079] Two spray-on hydrogels were obtained by dissolving the thiol terminated PEG (8-arm PEG-SH) and the thiopyridine terminated PEG (8-arm PEG-S-TP) (in accordance with a formulation of Example 1c) with additives comprising (a) a solution of 2% w/v polyvinylpyrrolidone (PVP) and 5% v/v of glycerin in phosphate buffer pH 8, and (b) by solution of 2% w/v polyvinyl pyrrolidone (PVP), 5% v/v of glycerin and 5% v/v of polyethylene glycol (MW 600) in phosphate buffer pH 8. These are shown in Table 10. [0000] TABLE 10 Hydrogel Compositions with additive Glycerin and PEG (MW 600) S. No 1 Conc. Of 8 arm PEG Conc. Of Ratio of (MW 20,000) Glycerin Compositions polymers (% w/v) (% v/v) 8-arm-PEG-S-TP + 1:1 6 5 8-arm-PEG-SH Dissolved in Phosphate buffer pH 8 containing PVP (2% w/v)) S. No 2 Conc. Of Conc. Of PEG (MW 600) 8 arm PEG (% v/v) Ratio of (MW 20,000) (+Glycerin Compositions polymers (% w/v) 5% v/v) 8-arm-PEG-S-TP + 1:1 6 5 8-arm-PEG-SH Dissolved in Phosphate buffer pH 8 containing PVP (2% w/v) [0080] A spray-on hydrogel was obtained by dissolving the thiol terminated PEG (4-arm-PEG-SH and 8-arm PEG-SH) and the thiopyridine terminated PEG (4-arm-PEG-S-TP and 8-arm PEG-S-TP) in a solution of polyvinylpyrrolidone (PVP) and hydroxypropyl methylcellulose (HPMC) in phosphate buffer pH 8. The concentration of PVP was varied from 1.5-2% w/v as shown in Table 11. [0000] TABLE 11 Hydrogel Compositions with additives PVP and HPMC Conc. Conc. Conc. Of Ratio of Of PVP Of HPMC polymers S. No Compositions polymers (% w/v) (% w/v) (% w/v) 1 4-arm-PEG-S-TP + 1:1 1.5 0.5 5 4-arm-PEG-SH 8-arm-PEG-S-TP + 1:1 8-arm-PEG-SH 8-arm-PEG-S-TP + 1:1 4-arm PEG-SH 2 4-arm-PEG-S-TP + 1:1 2 1.0 5 4-arm-PEG-SH 8-arm-PEG-S-TP + 1:1 8-arm-PEG-SH 8-arm-PEG-S-TP + 1:1 4-arm PEG-SH Example 5 Formulations Including Drug [0081] A. Lidocaine and Doxycycline Hyclate. [0082] The drugs Lidocaine and Doxycycline Hyclate were incorporated in the hydrogel by dissolving the drugs in the polymer solution (8-arm PEG-SH) as shown in Table 12. The drug incorporated polymer solution was cross-linked using the thiopyridine terminated PEG (8-arm PEG-S-TP) in phosphate buffer pH 8. Also, The drug incorporated polymer solution was cross-linked using the thiopyridine terminated PEG (8-arm PEG-S-TP) in a solution of 2% w/v polyvinyl pyrrolidone (PVP) and 5% v/v of glycerin in phosphate buffer pH 8 as shown in Table 12. [0000] TABLE 12 Hydrogel Compositions with Doxycycline Hyclate, Lidocaine HCL and Benzalkonium Chloride Conc. Ratio of Of PEG Drugs S. No Compositions polymers (% w/v) % w/v 1 8-arm-PEG-S-TP + 8-arm- 1:1 6 2.5% Lidocaine PEG-SH HCL and (Dissolved in phosphate 0.15% buffer pH 8) Benzalkonium HCL 2 8-arm-PEG-S-TP + 8-arm- 1:1 6 2.5% Lidocaine PEG-SH HCL and Dissolved in Phosphate 0.15% buffer pH 8 containing Benzalkonium Other additives: HCL PVP (2% w/v) PEG Mw 600 (5% v/v) Glycerin (5% v/v) 3 8-arm-PEG-S-TP + 8-arm- 1:1 8 0.34% PEG-SH Doxycycline (Dissolved in phosphate hyclate buffer pH 8) 4 8-arm-PEG-S-TP + 8-arm- 1:1 8 0.34% PEG-SH Doxycycline Dissolved in Phosphate hyclate buffer pH 8 containing Other additives: PVP (2% w/v) PEG Mw 600 (5% v/v) Glycerin (5% v/v) [0083] B. Doxycycline [0084] In another embodiment, the drug Doxycycline Hyclate was incorporated in the hydrogel by dissolving the drug in the polymer (8-arm-PEG-SH) solution in phosphate buffer pH 8. The drug incorporated polymer solution was cross-linked using the H 2 O 2 solution as shown in Table 13. [0000] TABLE 13 Hydrogel compositions cross-linked by H 2 0 2 with Doxycycline Hyclate Wt of pH = 8 PBS 8-arm- Buffer 3% H 2 0 2 Equiv- Doxycycline PEG-SH Volume Volume alent of Hyclate (mg) In μL In μL H 2 0 2 % w/v 8 mg 200 μL 1.8 μL 0.5 0 8 mg 200 μL 1.8 μL 0.5 0.5 8 mg 200 μL 1.8 μL 0.5 0.25 8 mg 200 μL 1.8 μL 0.5 0.12 12 mg 200 μL 5.4 μL 0.5 0.5 12 mg 200 μL 5.4 μL 0.5 0.25 12 mg 200 μL 5.4 μL 0.5 0.122 12 mg 200 μL 5.4 μL 0.5 0.061 16 mg 200 μL 5.4 μL 0.5 0.5 16 mg 200 μL 5.4 μL 0.5 0.25 16 mg 200 μL 5.4 μL 0.5 0.122 [0085] C. Indomethacin. [0086] The drug indomethacin was incorporated in the hydrogel by dissolving the drug in the polymer solution (8-arm PEG-SH) as shown in Table 14. The drug incorporated polymer solution was cross-linked using the thiopyridine terminated PEG (8-arm PEG-S-TP) in phosphate buffer pH 8. Also, The drug incorporated polymer solution was cross-linked using the thiopyridine terminated PEG (8-arm PEG-S-TP) in a solution of 2% w/v polyvinylpyrrolidone (PVP) and 5% v/v of glycerin in phosphate buffer pH 8 as shown in Table 14. [0087] Synthesis of the RGD Linked to Indomethacin Step 1: The RGD peptide having sequence Arg-Gly-Asp-Cys would be treated with three fold excess of dithiodipyridine (aldrithiol) in alcohol under mild acidic conditions overnight at room temperature, to obtain the protected peptide. Step 2: The indomethacin (1 eq) would be linked thiopyridine protected peptide (1 eq) in the presence of coupling agents coupling agents 4-dimethylaminopyridine and 1(3-dimethylaminopropyl) 3-ethylcarbodiimide (1 eq) in solution of dry dimethylformamide and using hydroxyl-terminated PEG as a spacer. The reaction would be carried out overnight at room temperature and the product would be separated by size exclusion chromatography using Sephadex LH 60 packing. The indomethacin-PEG-RGD conjugate would be linked to the 8-arm PEG-SH through the disulfide bond formation at the cysteine terminal of the peptide in phosphate buffer (pH 7.4) with stirring overnight and the product would be obtained by lyophilization of the reaction mixture for 12-24 hrs. [0000] TABLE 14 Hydrogel Compositions with Indomethacin Conc. Ratio of Of PEG Drugs S. No Compositions polymers (% w/v) % w/v 1 8-arm-PEG-S-TP + 8- 1:1 6 0.4% arm-PEG-SH Indomethacin (Dissolved in phosphate buffer pH 8) 2 8-arm-PEG-S-TP + 8- 1:1 6 0.4% arm-PEG-SH Indomethacin Dissolved in Phosphate buffer pH 8 containing Other additives: PVP (2% w/v) PEG Mw 600 (5% v/v) Glycerin (5% v/v) [0090] D. Doxycycline Conjugated to RGD. [0091] Doxycycline-RGD-PEG was incorporated in the hydrogel by dissolving the same in the polymer solution (8-arm PEG-SH) as shown in Table 15. The drug incorporated polymer solution was cross-linked using the thiopyridine terminated PEG (8-arm PEG-S-TP) in phosphate buffer pH 8. Also, The drug incorporated polymer solution was cross-linked using the thiopyridine terminated PEG (8-arm PEG-S-TP) in a solution of 2% w/v polyvinylpyrrolidone (PVP) and 5% v/v of glycerin in phosphate buffer pH 8 as shown in Table 15. The Doxycycline-RGD-PEG component was synthesized and the synthetic procedure is given below. [0092] Synthesis of the RGD-Linked Drug Composition Step 1: The RGD peptide having sequence Arg-Gly-Asp-Cys was treated with three fold excess of dithiodipyridine (aldrithiol) in alcohol under mild acidic conditions overnight at room temperature. To obtain the protected peptide Step 2: The Doxycycline (1 eq) was linked thiopyridine protected peptide (1 eq) in the presence of coupling agents 4-dimethylaminopyridine and 1(3-dimethylaminopropyl) 3-ethylcarbodiimide (1 eq) in solution of dry dimethylformamide. The reaction was carried out overnight at room temperature and the product was separated by size exclusion chromatography using Sephadex LH 60 packing. The PEG-ylation of Doxycycline-RGD conjugate was carried out using 8-arm PEG-SH in phosphate buffer (pH 7.4) with stirring overnight. The ratio of Doxycycline-RGD to 8-arm PEG-SH was taken (1:1 per arm). The Doxycycline-RGD-PEG so synthesized was obtained by lyophilization of the reaction mixture for 12-24 hrs. [0095] The different sizes of PEG (10-20 KDa) and with different number of thiol termination (2,4 and 8-arm Peg-SH) can be used. Further, the amount of Doxycycline-RGD can be taken proportional to the number of arms/sites at which it is required to be appended on the 4 or 8-arm PEG-SH. [0000] TABLE 15 Hydrogel Compositions with Doxycycline-RGD-PEG Conc. Ratio of Of PEG Drugs S. No Compositions polymers (% w/v) % w/v 1 8-arm-PEG-S-TP + 8- 1:1 6 Doxycycline- arm-PEG-SH RGD-PEG (Dissolved in (equivalent phosphate buffer pH 8) to 0.34%) 2 8-arm-PEG-S-TP + 8- 1:1 6 Doxycycline- arm-PEG-SH RGD-PEG Dissolved in (equivalent Phosphate buffer pH 8 to 0.34%) containing Other additives: PVP (2% w/v) PEG Mw 600 (5% v/v) Glycerin (5% v/v) [0096] The different sizes of PEG (10-20 KDa) and with different number of thiol termination (2,4 and 8-arm Peg-SH) can be used. Further, the amount of indomethacin-PEG-RGD can be taken proportional to the number of arms/sites at which it is required to be appended on the 4 or 8-arm PEG-SH. [0097] E. Olvanil. [0098] The drug olvanil was be incorporated in the hydrogel by dispersing the drug in the polymer solution (8-arm PEG-SH). The drug incorporated polymer solution was cross-linked using the thiopyridine terminated PEG (8-arm PEG-S-TP) in phosphate buffer pH 8. Also, the drug incorporated polymer solution was cross-linked using the thiopyridine terminated PEG (8-arm PEG-S-TP), both the polymer and cross-linker were dissolved in a solution of 2% w/v polyvinylpyrrolidone (PVP) and 5% v/v of glycerin in phosphate buffer pH 8 as shown in Table 15. [0099] The PEG-Olvanil-Cysteine was incorporated in the hydrogel by dissolving the same in the polymer solution (8-arm PEG-SH). The drug incorporated polymer solution was cross-linked using the thiopyridine terminated PEG (8-arm PEG-S-TP) in phosphate buffer pH 8. Also, the drug incorporated polymer solution was cross-linked using the thiopyridine terminated PEG (8-arm PEG-S-TP) in a solution of 2% w/v polyvinylpyrrolidone (PVP) and 5% v/v of glycerin in phosphate buffer pH 8. [0100] The PEG-Olvanil-Cysteine component was synthesized and the synthesis procedure is given below. [0101] Synthesis of the PEG-Olvanil-Cysteine [0102] Step 1: The 3-fold excess of Fmoc-Cysteine(S-Trt)-COOH was reacted with Olvanil in presence of diisopropylcarbodiimide under basic conditions by adding pyridine in dimethyl formamide. The formation of the Olvanil-Cysteine product was analyzed using ESI-MS as shown in FIG. 17 . [0103] Step 2: Olvanil-Cys(trt) ester was linked to 5 kDa-PEG-NHS in the presence of N N-Diisopropylethylamine by dissolving in dimethyl formamide by stirring overnight. The product so obtained was purified by Size exclusion chromatography using G-25 Sephadex beads. The formation of the product was analyzed using MALDI-TOF as shown in FIG. 18 . Example 6 Drug Delivery [0104] One of the embodiments of the present invention includes a therapeutic agent or drug, such as lidocaine (a topical anesthetic), benzalkonium chloride (a topical antiseptic), olvanil (an anti-inflammatory agent), doxycycline (an antibiotic), pilocarpine or protease inhibitors incorporated into the hydrogel composition. [0105] Formulations incorporating the drugs into the hydrogel composition are shown in Tables 12-15. For prolonged retention of drugs at the site of application, drugs linked to RGD peptide appended onto PEG were incorporated in the hydrogel composition, e.g., doxycycline as disclosed in Example 5. D. The RGD peptide, comprising the ‘Arg-Gly-Asp’ sequence, such as the liner peptide or the cyclic peptides are disclosed. The examples of the linear peptide include Arg-Gly-Asp-Cys, Gly-Arg-Gly-Asp-Ser, Gly-Arg-Gly-Asp-Ser-Pro, and the cyclic peptide include, Cyclo-Arg-Gly-Asp-Try-Lys but are not so limited, and can be extended to any peptide having the sequence ‘Arg-Gly-Asp’. These prodrugs are designed to provide cell adhesive and retentive properties to enhance binding to corneal epithelial cells or to the extracellular matrix of the injured skin for slow-release the active drug. Example 7 Reversible Cross-Links [0106] The reversible nature of the disulfide bridges to enable easy wash-off of the gel was established in-vitro and in-vivo using a solution of reducing agent like Glutathione. The concentration of Glutathione was varied from 1-5% w/v in phosphate buffer pH 8. The hydrogels having the varied compositions are shown in Table 16 and they showed a reversible nature of the disulfide linkages resulting in the hydrogel to convert from gel to sol. [0107] The hydrogel having a composition 6% w/v of 8-arm-PEG-SH and 8-arm-PEG-S-TP was sprayed on the mice and thereafter the hydrogel was washed off using a solution of Glutathione having a concentration 5% w/v as shown in FIG. 10 . [0000] TABLE 16 Evaluation of concentration of Glutathione required to reverse the disulfide cross-links in hydrogel Conc. Of Ratio of polymers Conc. of Glutathione (% w/v) S.No Composition polymers (% w/v) 1 3 5 1 4-arm-PEG-S-TP + 1:1 5 30 min 20 min 10-15 min 4-arm-PEG-SH 1:1 6 30 min 20-25 min 15 min 1:1 8 40-45 min 25-30 min 15-20 min 2 8-arm-PEG-S-TP + 1:1 5 40-45 min 20-25 min 15 min 8-arm-PEG-SH 1:1 6 Not investigated 20-25 min 15-20 min 1:1 8 Not investigated 30-35 min 15-20 min 3 8-arm-PEG-S-TP + 1:1 5 35-40 min 15 min 10-12 min 4-arm PEG-SH 1:1 6 Not investigated 15-20 min 10-12 min 1:1 8 Not investigated 15-20 min 10-15 min 4 4-arm-PEG-S-TP + 1:1 5 30-40 min 15 min 10-12 min 8-arm PEG-SH 1:1 6 Not investigated 15 min 10-12 min 1:1 8 Not investigated 20-30 min 15 min [0108] By exposure to or application of a reducing agent, such as cysteine or glutathione, to the cross-linked hydrogel composition, the composition can be completely dissolved and washed away. One of the embodiments of the present invention is to show the reversible nature of the cross-links and easy wash off of the gel. This is exemplified in the present invention using the normal skin of mice and using in vitro experiments ( FIG. 10 ). Example 7 Physical Properties [0109] A preferred hydrogel composition of the subject invention must be strong and flexible. It should not dry out too fast nor swell/shrink excessively. These properties were tested using rheology instrumentation and manual inspection of the gel. One of the embodiments of the present invention comprises 0.2-5% w/v polyvinyl pyrolidone (PVP), 0.2-5% w/v cellulose derivatives, such as hydroxypropyl methylcellulose, hydroxypropyl cellulose, 0.5-5% v/v PEG(6000 Da) and 0.4-25% v/v glycerin. Other additives that can be included in the hydrogel composition include phospholipids such as soybean phospholipids, eggyolk phospholipids, lecithins, soy lecithins, sphingomyelins, phosphatidylcholine, phosphatidylglycerol, phosphatidic acid, phosphatidylethanolamine, phosphatidyl serines, and PEG-ylated phospholipids. When sprayed on a Petri dish, this formulation produces a gel that forms a uniform layer without running of excess liquid ( FIG. 9 ). The gel may be peeled from the dish without tearing. Furthermore, the gel appears to be useful for up to 4 days. Based on these physical properties, a gel having a formulation as shown in Tables 9 or 10 or 11 may serve as the entire wound dressing when applied to skin, obviating the use of a gauze bandage. [0110] Rheological measurements were performed on a 4 and 6% w/v gel of 8-arm PEG-SH cross-linked by H 2 O 2 using a Rheometrics rheometer using RSI orchestrator software at 37° C. with cone plate geometry (plate diameter of 25 mm, gap of 3 mm and 2° angle). Samples were equilibrated on the plate for 5 min to reach the running temperature before each measurement. All rheological determinations were made at least in triplicate for each hydrogel using separate samples. Rheological test parameters like storage/elasticity (G′) and loss (G″) moduli were obtained under dynamic conditions of non-destructive oscillatory tests. The hydrogels of 8-arm Peg-SH and H 2 O 2 formed in phosphate buffer and phosphate buffer containing 2% w/v polyvinyl pyrrolidone, 5% v/v glycerin and 5% v/v polyethylene glycol (MW 600) was measured. The results for the rheology are shown in FIG. 15 . [0111] Additional rheological measurements were performed on a 5% w/v gel of 8-arm PEG-SH cross-linked by 8-arm PEG-S-TP using a Rheometrics rheometer using RSI orchestrator software at 37° C. with cone plate geometry (plate diameter of 25 mm, gap of 3 mm and 2° angle). Samples were equilibrated on the plate for 5 min to reach the running temperature before each measurement. All rheological determinations were made at least in triplicate for each hydrogel using separate samples. Rheological test parameters like storage/elasticity (G′) and loss (G″) moduli were obtained under dynamic conditions of non-destructive oscillatory tests. The hydrogels of 8-arm PEG-SH cross-linked by 8-arm PEG-S-TP formed in phosphate buffer and phosphate buffer containing 2% w/v polyvinyl pyrrolidone, 5% v/v glycerin and 5% v/v polyethylene glycol (MW 600) was measured. The results for the rheology are shown in FIG. 16 .

Described is a spray-on hydrogel comprising water-soluble PEG polymers that cross-link in situ to form a hydrogel such that the cross-links are reversible. The hydrogel can be useful as a drug delivery composition, wound dressing or surgery adjuvant. Polyethylene glycol polymer and cross-linker solutions are sprayed simultaneously through a common orifice. Cross-linking via formation of thioether or disulfide bonds is initiated upon mixing, providing rapid gelation. The hydrogel components can be derivatized with RGD peptides or analogs thereof to promote retention in/on a body compartment such as the skin, surface of the eye, or a mucosa such as the vaginal mucosa. The cross-links are reversed using a reducing solution enabling easy removal of the hydrogel by dissolution. Processes for preparation of the cross-linker, RGD derivatized PEG and RGD-linked agents are also disclosed.

INCORPORATION BY REFERENCE [0001] This application is a continuation of U.S. patent application Ser. No. 13/402,889, Method and System for Self-Administering a Visual Examination Using a Mobile Computing Device, filed on Feb. 23, 2012, by Nikoo Iravani and Brian Chou, that claims the benefit of priority under 35 U.S.C. 119(e) to the filing date of U.S. provisional patent application No. 61/446,011 Method of Self-Administering a Visual Acuity Measurement Using Smart Phone, filed on Feb. 23, 2011. The foregoing applications are herein incorporated by reference. FIELD OF THE INVENTION [0002] The present invention relates to the field of vision monitoring and screening testing tools that may be used individually or in combination to create vision monitoring and testing systems that improve patients' ability to recognize visual anomalies as well as changes in vision over time. The improvement of the identification of acute or chronic visual conditions may lead to earlier diagnosis by an eye care specialist and earlier treatment and therefore reduced likelihood of severe vision damage or loss. BACKGROUND OF THE INVENTION [0003] Vision loss is disruptive to the individual affected, their family and society. There are many causes of vision loss and vision impairment. Many of these conditions however are treatable if detected earlier. [0004] Age-related macular degeneration (AMD) is a leading cause of irreversible legal blindness in the western world. Over 12 million Americans have some type of AMD, and millions of others suffer from other retina issues. Currently, home self-monitoring tools for retina diseases fail to adequately indicate a changing vision, resulting in delayed treatment and higher incidences of severe vision loss. [0005] Other ophthalmic conditions ranging from refractive error to cataracts to glaucoma also respond to intervention. Unfortunately, many people affected by these disorders suffer needlessly because they are either unaware of their condition or they do not respond to their symptoms with sufficient promptness. This often leads to a delay in presentation after the onset of a visual change, which creates a delay in clinical diagnosis and therefore a delay in the start of treatment. This delay may lead to more severe vision impairment, or even permanent and unrecoverable vision loss. [0006] Furthermore, for a variety of occupations, visuals tests have been proposed for the assessment of various aspects of visual performance. For example, color vision screening has previously been used as a means for detecting color deficiencies, and as a means for assessing the severity of a user's color vision loss. [0007] Color vision testing has also been used to determine whether a user's vision meets the color vision requirements for a given occupation (e.g. aviation, transportation, or police and fire services); to assist in the detection of diseases (such as diabetes or multiple sclerosis) that can affect visual performance; to assist in the diagnosis of specific diseases of the eye (e.g. optic neuritis, age related macular degeneration, photoreceptor dystrophies, etc.); to facilitate disease management and treatment monitoring; and to enable the monitoring of eye-related side-effects in pharmaceutical drug trials. [0008] One classic illustrative vision test involves the measurement of high contrast Visual Acuity (VA). Visual Acuity is a quantitative assessment of the ability to resolve high contrast optotypes. In the United States, the measurement is recorded in a ratio, such as 20/20, 20/40, 20/200, and so on. The ratio 20/20 indicates that at 20 feet, an individual is able to resolve a high contrast black letter which subtends 5 minutes of arc against a white background. From a test distance of 20 feet away, the 20/20 letter is 8.87 mm tall. The ratio 20/40 indicates that the individual can resolve a letter which is twice the size as the 20/20 benchmark. The ratio 20/200 means that the individual can resolve a letter that is ten times the size as the 20/20 benchmark. [0009] In a visual acuity test, a user is asked to locate the orientation of the gap in a Landolt C optotype. The user's visual acuity is assessed on the basis of the smallest, high contrast Landolt C for which the user can resolve and locate the orientation of the gap. The test is carried out with both bright and dark targets and the results provide a measure of visual acuity similar to that measured with Snellen letter charts in optometric practices, but with improved accuracy and the use of a single target. The test can also be used to assess the effect of “visual crowding” when the test target is surrounded by other targets. [0010] These types of tests are usually undertaken by displaying computer generated images to a subject via a monitor, typically a cathode ray tube, liquid crystal display, or a projector. The patient attends to the images presented on the display and responds to the stimuli they observe on the screen. For example, in a test where the user might be required to identify the location of a gap in a Landolt C optotype, the user may be required to respond accordingly to the quadrant of the image (top left, bottom left, right or bottom right) in which the gap in the Landolt C optotype is located. Once the user has responded to the particular image being displayed, a new image is presented to the user to which the user responds. This process continues until a series of optotypes of varying sizes have been presented and corresponding patient responses have been noted. The computer program then determines the user's visual performance based on their responses to the image displayed. [0011] Government agencies use visual acuity guidelines for several matters. The Department of Motor Vehicles, for example, uses visual acuity to determine eligibility for motorist licensure. The Internal Revenue Service uses visual acuity to determine whether the taxpayer is legally blind in allowing an increased standard deduction on the federal tax return. Certain occupations, for example pilots and law enforcement, have a minimum visual acuity requirement. Schools frequently have nurses administer visual acuity measurements at specific grade levels to detect reduced vision, which can interfere with academic and athletic performance. Visual acuity is also routinely measured during routine physical exams. Reduced visual acuity can signal uncorrected refractive error, which can be managed with glasses, contacts, or refractive surgery. It can also signal conditions such as amblyopia and the presence of diseases such as cataracts, glaucoma, and macular degeneration. For these collective aforementioned reasons, there is consumer interest in having the ability to perform a self-guided visual acuity screening. Moreover, due to some perceived burden and associate costs, most consumers delay in scheduling an eye examination for obtaining baseline vision information. Therefore, a visual acuity examination that can be self-administered at any time and any place, such as that disclosed by the present invention, is practical, useful and preventive of many eye related conditions and diseases. [0012] While older known systems have been shown to be effective in vision testing and have accurately assessed the patients' visual performance, it is generally the case that the equipment (in particular the display) required to perform these tests is typically large and expensive, and hence tends to only be accessible at hospitals or research centers. As the equipment may not to be easily and universally available, patients may neglect to travel to a facility to undertake these tests. Furthermore, in less developed regions of the world, traveling to these facilities can be problematic for less able users. The use of such other tests for mass screening of eye conditions, on a regular basis is therefore very limited. [0013] It is also the case that in less developed regions of the world, the cost of equipment is such that some hospitals may simply forego the purchase of the equipment when possible. One unfortunately consequence of this is that many patients continue to endure conditions that could perhaps be treated if their vision were to be properly screened and investigated. [0014] It would be highly advantageous, therefore, if a simple and free method of vision screening could be proposed, wherein this method would be more accessible to patients and would be more likely to be implemented on a wider scale. Simple vision screening could be mitigated through properly devised testing apparatus and method that utilized commonly available visual equipment (such as a cellular phone screen, tablets, iPad screen, or any screen touch devices) for the display of tests to users, Vision Screening tests such as measuring visual acuity, color blindness and monitoring Macular Degeneration are carefully designed to require particular visual parameters such as proper distance of displayed symbols from the subject, or the proper orientation of the displayed symbols. As such, any self-administered visual test must be able to reasonably ensure that the test is properly administered from user to user with consistency. [0015] The present invention has been conceived with the aim of addressing one or more of the aforementioned problems. More specifically, the present invention boosts a subject's ability to accurately and confidently self-monitor their vision in any environment, which enables improved detection of eye disease symptoms. Self-tests and monitoring enhances a subject's ability to seek an eye care professional at an earlier stage of the condition, which enables earlier clinical diagnosis of onset or progression of diseases as well as earlier start of treatments. As a result, routine eye health evaluation is promoted and ultimately fewer people experience suboptimal vision and unnecessary vision impairment or vision loss. [0016] Currently, there are several competitive mobile applications, which also attempt to measure visual acuity. The majority of these applications are deficient in that they are mostly static eye charts without any dynamic self-administration algorithm which correctly measures one's visual acuity. When the eye charts are static, the variation in distance is fixed (typically 20 feet) and it becomes cumbersome to administer the test by the user himself. Specifically, it almost always requires an additional person to help assist in determining if user is identifying the optotypes correctly. In addition, the visual acuity cannot be determined accurately without an algorithm. The present invention disclosed herein, however, avoids the problem discussed above, as well as providing other improvements. Likewise, the field is in shortage of effective portable solution which allows an user to self administer color blindness screening examination using a mobile computing device. Furthermore, the current art is also deficient in effective portable solution which allows an user to self administer macula degeneration screening examination using a mobile computing device. OBJECTIVE OF THE INVENTION [0017] Accordingly, it is the object of the invention to provide a self-administered dynamic vision screening and monitoring testing tool. [0018] It is an object of the invention that the vision testing methods described below may be used individually or in combination with each other to create vision monitoring and testing system to improve a user's ability to recognize visual anomalies as well as their change in vision over time. [0019] It is an object of the invention that the vision testing method allows improved identification of baseline visual acuity [0020] It is an object of the invention that the vision testing method is a program or application for use in conjunction with a mobile computer device such as a smart phone and a tablet device. The vision testing application is a self-contained application that is downloaded, installed, and used with any smart phones and tablet devices. [0021] It is an object of the invention to measure Distance visual acuity which screens for myopia or near sightedness. [0022] It is an object of the invention to measure Near visual acuity which screens for hyperopia and presbyopia, commonly referred to as Far-sightedness. [0023] It is an object of the invention to provide the user the ability to use the vision test at a more convenient distance [0024] It is an object of the invention to provide a predetermined period of time to adjust his or her location relative to the mobile device. This allows the vision test application to accommodate the user in self-administering the visual acuity test. [0025] It is an object of the invention to display symbols on the mobile computer device that is suitable for determining the visual acuity of a user. [0026] It is an object of the invention to provide for the use of the “Landolt C” for the visual acuity test. The advantages of using the Landolt C is that it can also work for individuals who are illiterate and it is easier to score as there are only four (4) possible choices. [0027] It is an object of the invention to provide a formula or algorithm in the vision test application to allow for intelligent and intuitive response, wherein the smaller letters are subsequently presented after correct response by the user and larger letters are subsequently presented after incorrect response by the user. [0028] It is an object of the invention to provide for the vision testing application to be fully automated, wherein no calculation is required to be performed by the user for obtaining the results of the tests. [0029] It is an object of the invention to provide the user with a score of the visual acuity test, wherein the score is a scoring standard used by eye care specialists and professionals. [0030] It is an object of the invention to provide the user with a solution for self administering screening for color blindness using a mobile computing device such as smart phone, tablet, ipad or any touch screen portable computing device. [0031] It is an object of the invention to provide the user with a Macula Test in which the user can screen for Age-related macular degeneration (AMD), a medical condition relating to the loss of vision in the center of the visual field because of damage to the central part of retina (macula). [0032] It is an object of the invention to provide the user with a grid in which to test for AMD and to allow the user to mark the distorted areas on the mobile computer device's screen. [0033] It is an object of the invention to provide for the macula test to save marked distortions by the user. [0034] It is an object of the invention to provide for the macula test to allow the user to access the test history in order to keep track of marked distortions over time and monitor the progression of Macula Degeneration. [0035] It is an object of the invention to provide for the macula test to allow the user to share and review the macula degeneration test history with their eye care practitioner to better assess the condition. SUMMARY OF THE INVENTION [0036] To overcome the limitation in the prior art described above, the present invention discloses a dynamic method of administering a visual acuity test using a mobile computing device such as a smart phone and a tablet device. [0037] Specifically, the present invention disclosed is a method and system to perform vision screening comprising a program or application to be used in conjunction with a smart phone and a tablet device. An exemplary embodiment is a vision testing application that can be downloaded, installed, and used with any smart phone and tablet device. [0038] In one embodiment, the user can administer the eye vision examination by him or herself for near visual acuity test and/or distance acuity test without the aid of another person. There is no need for another person to be at the other side of the room to determine whether the response provided by the user correctly matches the displayed symbol/s. [0039] In one embodiment, the user has an option of selecting a near visual acuity test. Near acuity test measures hyperopia and presbyopia, commonly known as farsightedness or long-sightedness. In one embodiment, the user has an option of selecting a distance visual acuity test. Distance acuity test measures myopia, commonly known as nearsightedness or short-sightedness. [0040] In one embodiment, upon selection of a visual acuity test, the user is allowed a predetermined period of time to adjust his or her location relative to the mobile device or smart phone. After adjusting to the corresponding position, the user will be shown on the mobile device or smart phone display symbols that are suitable for determining the visual acuity of the user. Next, the user is requested to identify the display symbol among a number of symbols, one of which is the displayed symbol. Finally, based on the user's response to the requests, the user's visual acuity score is displayed on the mobile device. [0041] In one embodiment, the Landolt C is preferred over the Tumbling E, as the Landolt C provides better rotational symmetry which minimizes refractive error bias, and that even those who are illiterate can participate in the eye vision examination. [0042] In one embodiment, the eye vision screening method and system comprises a formula or algorithm to provide intuitive and intelligent response. As such, the displayed Landolt C becomes progressively smaller with correct responses, whereas the displayed Landolt C becomes progressively larger with incorrect responses from the user. [0043] In one embodiment, the eye vision screening method and system provides a visual acuity score or ratio to the user. As such, the user is able to determine and monitor, with accuracy and without the help of an eye care professional, his or her visual acuity over time. [0044] In one embodiment, the eye vision examination method and system is fully automated, requiring no user determination and calculation of the scores. Upon completion of the visual acuity screening, a visual acuity score or ratio will be provided to the user. [0045] In one embodiment, the program provides for a Macula Test, which screens for age-related macular degeneration (AMD), in which the user can keep track of any distortion of his or her vision over time. [0046] In another aspect of the invention, a method to administer visual acuity examination by a user is disclosed comprising providing a mobile computer device; embedding an application within the mobile device wherein the application comprises an activation module to initiate the visual acuity examination by the user; a displaying module displaying one or more symbol for user to visually identify; an input module for the user to input the result of the identification of the optotypes; an algorithm to determine visual acuity based on the input provided by the user. [0047] In one embodiment, the application further comprises a time delay module for the user to place the mobile computer device at a predetermined distance from the user. In one embodiment, the displaying module alters the size of the symbol based on the input provided by the user in accordance to predetermined algorithm. In one embodiment, the symbol is a Landolt C optotype. In one embodiment, the optotype is a Landolt C facing upward. [0048] In one embodiment, the optotype is a Landolt C facing downward. In one embodiment, the optotype is a Landolt C facing leftward. In one embodiment, the optotype is a Landolt C facing rightward. In one embodiment, the time delay module delays a time range of 1 second to 10 seconds. In one embodiment, the time delay module delays a time range of 5 second. In one embodiment, the predetermined distance is ranged from 1 to 20 feet. In one embodiment, the predetermined distance is 10 feet. In one embodiment, the symbol is 3.32 mm in height for a 20/15 optotype; 4.43 mm in height for a 20/20 optotype; 5.54 mm in height for a 20/25 optotype; 6.65 mm in height for a 20/30 optotype; 8.87 mm in height for a 20/40 optotype; 11.09 mm in height for a 20/50 optotype; 13.29 mm in height for a 20/60 optotype; 17.74 mm in height for a 20/80 optotype; 22.15 mm in height for a 20/100 optotype; 44.30 mm in height for a 20/200 optotype; 88.60 mm in height for a 20/400 optotype. [0049] In one embodiment, the visual acuity is a 20/x number. In one embodiment, the mobile computer device is selected from the group consisting of a laptop, a smartphone and a mobile touch screen device. [0050] Another aspect of the invention is disclosed wherein a system for administration of eye acuity by a user comprising a mobile computer device; an application embedded within the mobile device wherein the application comprising: an activation module to initiate the visual acuity examination by the user; a displaying module displaying one or more symbol for user to visually identify; an input module for the user to input the result of the identification of the symbols; an algorithm to determine visual acuity based on the input provided by the user. In one embodiment, the application further comprises a time delay module for the user to place the mobile computer device at a predetermined distance from the user. [0051] In one embodiment, the displaying module alters the size of the symbol based on the input provided by the user in accordance to predetermined algorithm. In one embodiment, the symbol is a Landolt C optotype. In one embodiment, the optotype is a Landolt C facing upward. [0052] In one embodiment, the optotype is a Landolt C facing downward. In one embodiment, the optotype is a Landolt C facing leftward. In one embodiment, the optotype is a Landolt C facing rightward. In one embodiment, the time delay module delays a time range of 1 second to 10 seconds. In one embodiment, the time delay module delays a time range of 5 second. In one embodiment, the predetermined distance is ranged from 1 to 20 feet. In one embodiment, the predetermined distance is 10 feet. In one embodiment, the symbol is 3.32 mm in height for a 20/15 optotype; 4.43 mm in height for a 20/20 optotype; 5.54 mm in height for a 20/25 optotype; 6.65 mm in height for a 20/30 optotype; 8.87 mm in height for a 20/40 optotype; 11.09 mm in height for a 20/50 optotype; 13.29 mm in height for a 20/60 optotype; 17.74 mm in height for a 20/80 optotype; 22.15 mm in height for a 20/100 optotype; 44.30 mm in height for a 20/200 optotype; 88.60 mm in height for a 20/400 optotype. In one embodiment, the visual acuity is a 20/x number. In one embodiment, the mobile computer device is selected from the group consisting of a laptop, a smartphone and a mobile touch screen device. [0053] In another aspect of the invention, a method to administer color blind examination by an user is disclosed comprising: providing a mobile computer device; embedding an application within the mobile device the application comprises: an input module to initiate the examination; a displaying module displaying PseudoIsochromatic Plate for user to recognize; an answering module for user to input answers; an algorithm to determine color blindness based on the input provided by the user. [0054] In another aspect of the invention, a system for administration of color blind examination by a user is disclosed comprising: a mobile computer device; an application embedded within the mobile device the application comprises: an activation module to initiate the examination; a displaying module displaying PseudoIsochromatic Plate for user to recognize; an answering module for user to input answers; an algorithm to determine color blindness based on the input provided by the user. [0055] In another aspect of the invention, a method to administer macular degeneration test by the user is disclosed comprising providing a mobile computer device; embedding an application within the mobile device wherein the application comprising: an activation module to initiate the macular degeneration test by the user; a displaying module displaying the Amsler grid for the user to identify wherein the user would identify the grid if the user sees the grid as blurry, wavy or distorted; an input module for the user to input the identified grid; a recordation module to record the result of the input. [0056] In one embodiment, the application further comprises retrieval module for the user to retrieve the content which has been inputted. In one embodiment, the user provides the input by marking on one or more grids. In one embodiment, the user provides the input by marking on one or more grids by touching a touch screen device of the mobile computer device. [0057] In another aspect of the invention, a system to administer macular degeneration test of an user by the user comprising a mobile computer device; an application embedded within the mobile device wherein the application comprising: an activation module to initiate the macular degeneration test by the user; a displaying module displaying one or more grids for the user to identify wherein the user would identify the grid if the user sees the grid as blurry; an input module for the user to input the identified grid; a recordation module to record the result of the input. [0058] In another aspect of the invention, the application further comprises retrieval module for the user to retrieve the inputted. In another aspect of the invention, the user provides the input by marking on the one or more grids. In another aspect of the invention, the user provides the input by marking on the one or more grids by touching a touch screen device of the mobile computer device. [0059] In one other aspect of the invention, a method of administering a visual acuity examination by a user is disclosed comprising embedding an application within a mobile computing device wherein the application comprises: initiating the visual acuity examination by the user; displaying one or more symbols for the user; the user inputting his/her response to the displayed symbol into the mobile computer device; and determination of the visual acuity of the user by the mobile computer device based on the user's input. [0060] In one embodiment, the application further comprises a time delay module for delaying display of symbols to the user until the user has moved a predetermined distance away from the mobile computer device. In another embodiment, the size of the symbols are changed in accordance to a predetermined algorithm based on input provided by the user. [0061] In one other aspect of the invention, a mobile computer device for administration of an eye acuity examination by a user is disclosed comprising: an application embedded within the mobile device, the application comprising an activation module to initiate the visual acuity examination by the user; a display module displaying one or more symbols for user; an input module for inputting the users response to the displayed symbol into the mobile computer device; and an algorithm for determination of the visual acuity of the user by the mobile computer device based on the user's input. BRIEF DESCRIPTION OF THE DRAWINGS [0062] These and other features and advantages of the invention will not be described with reference to the drawings of certain preferred embodiments, which are intended to illustrate and not to limit the invention, and in which: [0063] FIG. 1 is an illustrative view of the application loading screen. [0064] FIG. 2 is an illustrative view of the disclaimer screen. [0065] FIG. 3 is an illustrative view of the menu screen. [0066] FIG. 4 is an illustrative view of the screen containing other vision tests. [0067] FIG. 5 is an illustrative view of the visual acuity menu screen. [0068] FIG. 6 is an illustrative view of the distance acuity starting screen. [0069] FIG. 7 is an illustrative view of the time delay module screen. [0070] FIG. 8 is an illustrative view of the screen of a visual acuity test in progress. [0071] FIG. 9 is an illustrative view of the screen prompting user's response in a visual acuity test. [0072] FIG. 10 is an illustrative view of the screen displaying the results of a visual acuity test. [0073] FIG. 11 is an illustrative view of color vision test menu screen. [0074] FIG. 12 is an illustrative view of the screen of a color vision test in progress. [0075] FIG. 13 is an illustrative view of the screen prompting user's response in a color vision test. [0076] FIG. 14 is an illustrative view of the screen displaying the result of the color vision test. [0077] FIG. 15 is an illustrative overview of the application, the visual acuity test, and the color vision test. [0078] FIG. 16 is an actual screen shot of the application menu. [0079] FIG. 17 is an actual screen shot of the menu of other available vision tests. [0080] FIG. 18 is an actual screen shot of the distance acuity test in progress. [0081] FIG. 19 is an actual screen shot of the near acuity test in progress. [0082] FIG. 20 is an actual screen shot of the color vision test in progress. [0083] FIG. 21 is an illustrative view of the screen displaying the Macula Test menu screen. [0084] FIG. 22 is an illustrative view of the screen of the Macula Test in progress via the use of a grid to test for age-related macular degeneration (AMD). DETAILED DESCRIPTION OF THE INVENTION [0085] In one aspect, the present invention is a method and system for the self-administration of visual acuity measurement comprising of a near and distance visual acuity tests. The ability to self-administer and monitor visual acuity over time is valuable in many respects. For example, patients who have had laser vision correction are often interested in monitoring their own visual acuity after the correction surgery. Myopic children in grade school frequently experience progression in myopia with a corresponding decrease in distance visual acuity. Furthermore, People over the age of forty (40) are expected to have changes in their ability to change visual focus between distance and near objects. The present invention can be used to measure and assess the visual acuity in various circumstances. [0086] The present invention is a method and system to perform vision screening comprising a software program or application wherein the application can be downloaded, installed, and used with any one of various smart phones and tablet devices. The application allows the user to administer a self guided vision screening without the aid of another person. Because the application is fully automated and designed to be fully functional for use by one user, there is no need for another person to be at the other side of the room to determine whether the response provided by the user correctly matches the displayed symbol. [0087] In one embodiment, the user has an option of selecting a distance visual acuity test, which measures myopia, or commonly known as nearsightedness or short-sightedness. Under the distance visual acuity test option, the user can perform and self-administer the visual acuity examination at a distance of only ten (10) feet rather than the traditional twenty (20) feet away. In another embodiment, the user can perform and self-administer the visual acuity examination at variation of a distance rather than the traditional twenty (20) feet away wherein the algorithm will determine and display various sizes of the letters based on the distance. This difference in distance is highly advantageous in many circumstances where space may be limited. [0088] In the visual acuity examination, after the test begins, the application counts down from five seconds allowing the user to step back ten (10) feet away. Then a letter “C” is briefly displayed with a timer bar simultaneously shown at the top of the screen which provides the user with approximately four (4) seconds to gaze at the displayed letter, after which the displayed symbol disappears. Thereafter, the application requests the user to indicate with the touch screen in which direction the gap in the “C” was observed. The user is provided with six (6) options for responding to the automatic prompt: (1) up, (2) down, (3) left, (4) right, (5) “show again” or (6) “I'm not sure”. The test is repeated between one to thirteen times and preferably between six to thirteen times in order to provide a resulting visual acuity score. The symbol letter size display begins at the size that user initially selects and can range from 20/15 to 20/200. If on the first presentation of a particular letter size, the user incorrectly identifies the orientation of the letter “C”, a progressively larger letter size is displayed. Conversely, if the user correctly identifies the 20/20 optotype, the application will begin displaying 20/15 optotypes. [0089] In one embodiment of the distance visual acuity test at which the display is ten (10) feet away from the user at eye level, the letters should have the following sizes: [0000] 20/15 letter=3.32 mm tall 20/20 letter=4.43 mm tall 20/25 letter=5.54 mm tall 20/30 letter=6.65 mm tall 20/40 letter=8.87 mm tall 20/50 letter=11.09 mm tall 20/60 letter=13.29 mm tall 20/80 letter=17.74 mm tall 20/100 letter=22.15 mm tall 20/200 letter=44.30 mm tall 20/400 letter=88.60 mm tall [0090] In one embodiment, the user has an option of selecting a near visual acuity test, which measures hyperopia, and/or presbyopia or commonly known as farsightedness or longsightedness. Under the near visual acuity test option, the user can perform and self-administer the visual acuity examination at a distance of only sixteen (16) inches. That is, the user can sit at a desk, set up the program on the smart phone, and administer the examination by placing the smart phone at sixteen (16) inches away. The near visual acuity test is similar to the distance visual acuity test with the exception of three elements. First, the user is instructed to hold the smart phone at only approximately sixteen (16) inches away. Second, the application preferably begins by assessing the user's approximate threshold near visual acuity to determine the subsequent letter size to display, rather than automatically starting at the 20/20 level. Third, the time delay in displaying the symbol can be set at less than 4 seconds, reflecting the fact that there is no need for the user to step back ten (10) feet away from the mobile computer device. [0091] In one embodiment, the Landolt C is preferred over the Tumbling E, as the Landolt C provides better rotational symmetry which minimizes refractive error bias, and that even those who are illiterate can participate in the eye vision examination. For determining the visual acuity of a user, the eye vision examination uses the Landolt C, where the letter “C” is displayed either with the gap in the “C” pointing up, down, left, or right. The advantage of the Landolt C is that even an illiterate (e.g. child, those with language barrier, etc.) can successfully perform this measurement with the aid of another individual. Secondly, unlike the “Tumbling E” where the letter “E” is displayed either up, down, left, or right orientations, the letter C has greater rotational symmetry to the optotype. Rotational symmetry is important in minimize refractive error bias. As an example, an individual with significant against-the-rule astigmatism (e.g. p1-2.00×090) would more likely demonstrate reduced visual acuity with the Landolt C versus Tumbling E. Hence, the Landolt C has greater sensitivity in detecting astigmatic refractive error. [0092] In one embodiment, the vision screening method and system comprises a formula or algorithm to provide intuitive and intelligent response. More specifically, the formula or algorithm logically displays the optotype (i.e. letter, symbol, or number) with the size of the optotype (“letter-size”) based on user response. As such, the displayed Landolt C becomes progressively smaller with correct responses, whereas the displayed Landolt C becomes progressively larger with incorrect responses from the user. This formula or algorithm correctly provides, based on the optotype displayed and the user's response corresponding to the optotype displayed, the necessary information for determining the visual acuity of the user. [0093] In one embodiment, the vision screening method and system provides a visual acuity score or ratio to the user. When the distance or near visual acuity testing is completed, the application provides a visual acuity score, for example 20/20 +2 , or 20/40, etc. As such, the user is able to determine and monitor, with accuracy and without the help of an eye care professional, his or her visual acuity over time. [0094] In one embodiment, all users are shown a 20/40 letter and must provide a response for each letter shown. If the user provides the correct response, the program will provide them with progressively smaller letters from 20/30, to 20/20, to 20/15. For example, if the user correctly identifies the 20/40 letter, then correctly identifies the 20/30 letter, but then misses the 20/25 letter, then the user will be shown five more 20/30 letters. At that point, the goal near the end of the measurement is to always present six letters in a given visual acuity line. If the user gets five of the six 20/30 letters corrected, then the final acuity score is 20/30 −1 . [0095] If, as another example, the user provides the correct response to all six 20/30 letters correct, then the program will display 20/25 letters. If the user gets two of the six 20/25 letters correct, then the final acuity score is 20/30 +2 . In the same scenario, however, if the user provides the correct responses to all six 20/30 letters and then get three of the six 20/25 letters correct, then the final acuity score is 20/30 +3 . In this case, it is also correct for the program to indicate an acuity score of 20/25 −3 , even though technically the acuity score is 20/30 +3 because the program displayed 20/30 letters and the user responded correctly rather than having displayed all the 20/20 letters and having the user provide incorrect responses to all six of the 20/20 letters. In general, however, in no instances should the program provide +4, −4, +5, or −5 after the acuity measurement—it should only be within the range of and including −3 and +3. [0096] Visual acuity is a threshold measurement. That is, if done correctly, the user is pushed to the limit of what they can or cannot see. At the end, the users should be guessing and missing some of the letters. A common clinical mistake by novice technicians is to allow the patients to easily read all the letters correctly on one line and claim that the patient cannot see anything more and quit the measurement. This usually ends up with an under-estimated visual acuity score, unless the patient is encouraged to try to proceed to read the next line of letters. [0097] In one embodiment, the vision screening method and system is fully automated, requiring no user determination and calculation of the scores. Whereas other available eye examination methods requires calculation of the visual acuity score or ratio based on distance, the present invention disclosed herein does the calculation automatically and thus providing greater convenience and minimal error rates. [0098] In another aspect of the invention, the eye vision examination also includes a Macular Test in which Age-related macular degeneration (AMD) is tested. AMD is a medical condition which usually affects older adults and results in a loss of vision in the center of visual field (the macula) because of damages to the retina. In the macular test, the user's eye are tested separately by covering one eye at a time. If the user uses glasses for near-sightedness or myopia, then the user will wear glasses in order for the testing results to be accurate. [0099] First, the user will preferably keep the display approximately twelve (12) inches from his or her eye. In an embodiment, at the beginning of the test, the program will display a grid with a dot at the center. The user is to keep his or her focus on the center dot. The program then prompts the user to provide responses indicating (1) whether the user can see all four corners of the large square; (2) whether the user can see all the small squares; and (3) whether any of the small squares or lines are blurry, wavy, or distorted. Assuming that a certain portion of the grid is seen as distorted by the user, the user can mark it with his or her finger directly on the touch screen and save it. The program will save the information and the user can access the information via test history and see if the user's distortion is increasing over time. [0100] In another aspect of the invention, the eye vision examination also includes a Macular Test in which Age-related macular degeneration (AMD) is tested. AMD is a medical condition which usually affects older adults and results in a loss of vision in the center of visual field (the macula) because of damages to the retina. In the macular test, the user's eye are tested separately by covering one eye at a time. If the user uses glasses for near-sightedness or myopia, then the user will wear glasses in order for the testing results to be accurate. [0101] In another aspect of the invention, a method to administer color blind examination by an user is disclosed comprising: providing a mobile computer device; embedding an application within the mobile device the application comprises: an input module to initiate the examination; a displaying module displaying PseudoIsochromatic Plate for user to recognize; an answering module for user to input answers; an algorithm to determine color blindness based on the input provided by the user. [0102] In another aspect of the invention, a system for administration of color blind examination by a user is disclosed comprising: a mobile computer device; an application embedded within the mobile device the application comprises: an activation module to initiate the examination; a displaying module displaying PseudoIsochromatic Plate for user to recognize; an answering module for user to input answers; an algorithm to determine color blindness based on the input provided by the user. DETAILED DESCRIPTION OF THE DRAWINGS [0103] The invention will be described in the context of a preferred embodiment. Referring to FIG. 1 , an eye examination software or application is loaded onto a smart phone from a server coupled to the smart phone. The screen 100 displays the title 101 of the program or application, the company name 102 , and indication of the status of the program 103 , that is, the application is loading. Then, referring to FIG. 2 , the screen 200 displays a disclaimer 201 of liability notifying the user who is about to administer the eye examination. The user can either accept 202 the terms of the disclaimer or disagree and quit 203 the application. Referring to FIG. 3 , in the main menu screen 300 , various options are provided to the user for selection, such as but not limited to “visual acuity” 301 , “color” 302 , “more tests” 303 , “doctor finder” 304 and “about” 305 . Referring to FIG. 4 , the “more tests” option takes the user to another menu screen, wherein there are tests for astigmatism 401 , Amsler Grid 402 , and other tests 403 . [0104] Referring to FIG. 5 , upon the selection of the “visual acuity” option, the application proceeds to where the process of self-administered visual acuity examination begins. The user is then provided with the option of “near” 501 and “far” 502 . The “near” 501 option is the near visual acuity test which examines for myopia or near-sightedness, whereas the “far” 502 option is the distance visual acuity test which examines for hyperopia or far-sightedness. The visual acuity tests 501 , 502 provide the ability to self-administer a visual acuity examination using the user's smart phone. Referring to FIG. 6 , choosing the far or distance acuity test takes the user to the distance acuity test screen 600 and the user can choose when to start the test by pressing the “begin” button 601 . Referring to FIG. 7 , upon the start of the distance visual acuity test, the application provides the user a screen 700 showing the user a count down 701 of when the next letter will be displayed. Referring to FIG. 8 , the application displays on the screen 800 a Landolt C oriented in a particular orientation for the user to identify in the pre-determined time period as indicated by the time bar 802 . Then, referring to FIG. 9 , the user is taken to the response screen 900 , wherein the user is asked to indicate which orientation of the Landolt C was displayed 901 . The user is given four (4) choice of orientation of the Landolt C: (1) C with the gap facing upward 902 ; (2) C with the gap facing rightward 903 ; (3) C with the gap facing leftward 904 ; and (4) C with gap facing downward 905 . Finally, referring to FIG. 10 , a screen 1000 providing the result of the visual acuity test in the form of a score or ratio 1001 is automatically provided to the user after the completion of the visual acuity examination. Furthermore, the user also has the option to “find a doctor” 1002 or simply return to the main menu 1003 . [0105] Similarly, referring to FIG. 11 , the “color” option allows for the user to self-administer a color-blind test and brings the user to the color vision test screen 1100 . The color vision test will only begin upon the user pressing the “begin” button 1101 . Referring the FIG. 12 , upon starting the color vision test, the user is shown a screen 1200 displaying a group of colored dots in a circle 1201 where a number or letter is displayed with a background suitable for testing for color blindness where in the number or letter is buried in the background. Then, the user is asked 1201 to identify and respond by indicating what number or letter was displayed 1201 . Next, referring to FIG. 13 , the user's response can be done in various ways, such as presenting a number of options 1301 to the user, wherein the options includes the correct response among incorrect responses. Upon the user's selection of one of the options, the user's response is recorded, and the user can move on to the next screen by pressing the “next” button 1302 . Referring to FIG. 14 , upon the completion of the colored vision test, a screen 1400 displaying the results is provided. The user is informed that if the user chose any incorrect selections, then the user should seek a doctor 1401 . The application further provides an option to find a doctor nearby 1402 or to return to the main menu 1403 . [0106] FIG. 15 is an illustrative overview of a block diagram showing a method of self-administering an eye examination with accordance with the present invention disclosed herein. [0107] FIG. 16 is a screen shot showing the menu displaying the title “EyeXam” 1601 of the program or application and various options for the user to select, such as but not limited to “Visual Acuity” 1602 , “Color Vision” 1603 , “More Tests” 1604 , “Doctor Finder” 1605 , “Eye Anatomy & Conditions” 1606 , and “About EyeXam” 1607 . [0108] FIG. 17 is a screen shot of the “more tests” option, which takes the user to another menu screen 1700 . The menu screen 1700 displays the tests for Astigmatism 1701 , Macula Test 1702 , Eye Alignment 1703 , Eye Exercise 1704 , and Eye Dominance 1705 . [0109] FIG. 18 is a screen shot 1800 of the distance acuity test, wherein the user is given a certain amount of time as indicated by the time bar 1801 to identify the orientation of the Landolt C 1802 shown on the display. Then, the application prompts the user to provide response to the previously displayed image. [0110] Similarly, FIG. 19 is a screen shot 1900 of the application screen prompting the user to provide a response to the previously displayed image for a near acuity test. The application prompts 1901 the user and provides the user with four (4) choice of orientation of the Landolt C: (1) C with the gap facing upward 1902 ; (2) C with the gap facing rightward 1903 ; (3) C with the gap facing leftward 1904 ; and (4) C with gap facing downward 1905 . Alternatively, the user can also choose for the application to “show again” 1908 the previously displayed image of the Landolt C or to simply choose “I'm not sure” 1909 to indicate that the user is unsure of the previously displayed image of the Landolt C. The application also indicates to the user his or her current visual acuity score or ratio 1906 as well as indicating the number of questions asked and number of questions responded correctly 1907 . [0111] FIG. 20 is a screen shot 2000 of the color vision test, wherein upon starting the color vision test, the user is shown a group of colored dots in a circle 2001 where a number or letter is displayed with a background suitable for testing for color blindness where in the number or letter is buried in the background. Then, the user is expected to identify the number or letter as shown in the circle, upon which the user can click on the “show results” button 2002 to determine if the user's identification was correct. [0112] FIG. 21 is an illustrative screen 2100 of the Macular Test, wherein upon starting the test to test for age-related macular degeneration (AMD), the user is shown a simple direction instruction 2101 to guide the user. The user is also prompted by the program to keep track of three details 2102 : (1) whether the user can see all four corners of the large square; (2) whether the user can see all the small squares; and (3) whether any of the small squares or lines are blurry, wavy, or distorted. The user is also informed 2103 that a normally the user would be able to see all four corners of the large square and all the small squares, and that none of the small square or lines are blurry, wavy, or distorted. Once the user is comfortable with the directions, the user may proceed to the next step to test for AMD by pressing the “Begin Test” 2104 button. [0113] FIG. 22 is an illustrative screen 2200 of the Macular Test in progress to test for age-related macular degeneration (AMD). The user is shown a black and white grid 2201 with a dot 2202 in the center of the grid. The user is to focus his or her eyes on the dot 2202 and to indicate whether the user can see all four corners of the large square as well as whether the use can see all the small squares. Furthermore, the user is to mark all, if any, of the small square or lines are blurry, wavy, or distorted. One embodiment of providing such marking is by touch the mobile device that contains a touch screen. Any mistake in marking by the user to of any small square or lines are blurry, wavy, or distorted can be undone via the “Undo” button 2203 . A history of the user's markings can be saved 2204 and can be accessed by the user later on via “Test History” 2205 . The user can then keep track of any changes in vision via the test history. Specifically, the user can retrieve previously saved file to compare with the presently save file to see if the distortion has worsen.

Novel vision monitoring and screening testing tools and help-seeking enablers that may be used individually as or in combination with vision monitoring and screening testing systems that improves patients' ability to recognize onset and progression of visual changes over time. Patients' ability to identify acute or chronic visual conditions on their own may drive earlier help-seeking behavior by the patient, enable earlier clinical diagnosis by an eye care specialist, and therefore resulting in earlier treatment and reduced likelihood of severe vision loss.

CROSS REFERENCE TO RELATED APPLICATION [0001] This application is a divisional of U.S. patent application Ser. No. 14/046,924, which was filed on Oct. 5, 2013, and entitled “Prosthesis for Partial and Total Joint Replacement. TECHNICAL FIELD [0002] The present invention relates to prosthetic joints. More specifically, a prosthetic joint having an improved connection to the medullary canals is provided. Additionally, a prosthetic joint that may be used for either partial or total joint replacement is provided. BACKGROUND INFORMATION [0003] There are three bones in the elbow: the humerus, the ulna, and the radius. These three bones articulate in the ulnohumeral, radiohumeral and radioulnar joints. Each of the joint surfaces is covered with articular cartilage and motion occurs at these articulations with distinct motion profiles. The cartilage allows the bones to slide easily against one another as the joint moves through its range of motion. The ulnohumeral joint is most essential for transmitting forces through the elbow. [0004] Degenerative joint diseases such as Osteoarthritis as well as inflammatory arthritides such as Rheumatoid arthritis commonly affect the elbow joints and causes articular degeneration and marginal bone formation. In post-traumatic settings, where surgical efforts have failed to restore adequate alignment, post-traumatic arthritis may set in and become symptomatic with patients experiencing pain and a loss of range of motion. Whether idiopathic, inflammatory or post-traumatic, elbow arthritis is often painful and may interfere with function of the entire arm. [0005] Initial non-operative intervention often includes splinting and steroid injections. Elbow joint synovectomy and debridement of arthritic spurs are surgical options when the cartilage damage is limited. Arthodesis (i.e., joint fusion) is an option for very damaged joints and is rarely used as elbow range of motion is sacrificed. Functional requirements of the patient often necessitate a durable solution that maintains range of motion. Accordingly, numerous prior efforts have been undertaken to replace this joint. [0006] Whereas degenerative joint diseases usually affect patients after the fifth decade of life, traumatic conditions may cause elbow joint impairment in younger age groups. Elbow fractures such as of the distal humerus or olecranon often exhibit intra-articular involvement, which can lead to permanent cartilage damage despite the best surgical reconstruction efforts. This is particularly true when anatomic reconstruction of the joint surfaces is not successful or if osteochondral portions are missing as may occur in open injuries. In these settings, consideration for a primary joint replacement as an option may be given. Often, only a portion of the elbow joint is injured such as the distal humerus and it may benefit from reconstruction. High energy injuries such as Motorcycle accidents may damage the distal humerus of younger patients and leave the ulna and radius relatively uninjured. Thus, the ability to replace either the distal humerus only (hemiarthroplasty) or the entire elbow (total arthroplasty) is quite helpful. [0007] Initial joint replacement efforts were done as early as 1947, when surgeons employed custom made hinges to replace elbow joints. However, the results of these early efforts were characterized by implant loosening, instability and poor clinical results. Hurri L, Pulkki T, Vainio K. Arthroplasty of the Elbow in Rheumatoid Arthritis , ACTA CHIR SCAND 964; 127:459-465; Dee R. Total Replacement Arthroplasty of the Elbow for Rheumatoid Arthritis , J BONE JOINT SURG BR 1972; 54 (1):88-95; Cross M B, Sherman S L, Kepler C K et al. The Evolution of Elbow Arthroplasty: Innovative Solutions to Complex Clinical Problems , J BONE JOINT SURG AM 2011; 92 Suppl 2:98-104. In the 1970s, the first simple hinged elbow prostheses were implanted using cementing techniques. Cross M B, Sherman S L, Kepler C K et al. The Evolution of Elbow Arthroplasty: Innovative Solutions to Complex Clinical Problems , J BONE JOINT SURG AM 2011; 92 Suppl 2:98-104. This improved the stability of the construct, but still resulted in rates of loosening of up to 50%. Garrett J C, Ewald F C, Thomas W H et al. Loosening Associated with G.S.B. Hinge Total Elbow Replacement in Patients with Rheumatoid Arthritis , CLIN ORTHOP RELAT RES 1977; (127):170-174. As a result of these observations, different design concepts have emerged: linked, unlinked, convertible and modular elbow prostheses. [0008] Linked, or “semi-constrained,” prostheses are commonly used implants and employ a “sloppy hinge” mechanism that allows for some varus, valgus, and rotational movement. The linked design offers superior stability and dislocations of these joints are rare, however, the constrained design transfers forces through the bone-cement or bone-implant interface which then results in significant loosening rates. [0009] Unlinked or “unconstrained” prosthesis designs work without a mechanical linkage between the components. These prostheses can be implanted while maintaining good bone stock and offer decreased polyethylene wear when compared to their linked counterparts. Since there is no mechanical linkage between the components, the stability of the construct relies greatly on the soft tissues around the elbow. It is believed that a well-balanced soft tissue envelope reduces stress at the bone-cement and bone-implant interfaces which results in lower loosening rates compared to linked designs. Understandably, this reliance on soft tissues to maintain stability results in higher rates of instability and joint dislocation compared to linked designs. These characteristics prevent the use of an unlinked prosthesis in situations where soft tissue integrity is poor or extensive bone loss has occurred. [0010] Total elbow arthroplasty systems have been developed that allow intra-operative decision making with regards to what type of implant may be best suited. “Convertible” systems have been developed that allow the placement of either a semi-constrained or an unconstrained construct based on the soft tissue integrity of the patient. These designs allow intraoperative conversion between unlinked and linked inplants as dictated by the integrity of the soft tissues and bone. [0011] Modular arthroplasty relates to replacement of a portion of the elbow joint. Total elbow arthroplasty may not be an ideal solution for younger patients. This group may benefit from replacement of only those regions that are damaged while preserving unaffected joint surfaces. On occasion, the distal humerus is severely injured with relative sparing of the proximal ulna or radius. In some instances, such as high energy motor vehicle accidents, the distal humerus is not salvageable. Thus, the ability to replace either the distal humerus only (hemiarthroplasty) or the entire elbow (total arthroplasty) is quite helpful. A modular system would then also allow the surgeon to add implants at a later time as subsequent wear and tear of the remaining native joint surfaces may occur. [0012] A currently available modular elbow arthroplasty system is the UNI-Elbow Radio Capitellum System (Small Bone Innovations) that allows for replacement of the radio-humeral joint in isolation. It is a Uni-compartmental arthroplasty of the elbow where the lateral side of the elbow is replaced in isolation. Additionally, the Latitude Total Elbow prosthesis (Tornier, USA) is a total elbow replacement system whose distal humerus component matches native anatomy closely and can be used in isolation (hemiarthroplasty) in instances where the ulna is in good condition. [0013] In a case series on hemiarthroplasty for distal humerus fractures in elderly patients using the Latitude System mainly good to excellent short-term results based on a Mayo score and good functional results were achieved. None of the complications required implant removal and only in one case did progressive osteoarthritis of the proximal ulna and radius occur. These results only represented a mean follow-up of 12.1 months, however, and therefore must be interpreted cautiously. Burkhart K J, Nijs S, Mattyasovszky S G et al. Distal Humerus Hemiarthroplasty of the Elbow for Comminuted Distal Humeral Fractures in the Elderly Patient , J TRAUMA 2011; 71 (3):635-642. The use of the Kudo prosthesis for hemiarthroplasty purposes has been described in a small case series with reasonable functional outcome after a mean of 4 years status after implantation. However, radiographic signs of attrition indicate that this implant may not be ideally suited for this role. Adolfsson L, Nestorson J. The Kudo Humeral Component as Primary Hemiarthroplasty in Distal Humeral Fractures , J SHOULDER ELBOW SURG 2012; 21 (4):451-455. [0014] At this time, all commercially available implants whether linked, unlinked, convertible or modular are cemented in place. Even though this offers a quick, reliable, and relatively durable bone-to-implant fixation, there are significant limitations. The most noteworthy is that the implant and cement mantle is difficult to remove if this is required such as in the face of an infection or peri-prosthetic fracture. If the implant is merely loose and improved fixation is required, then the cement can be removed where it is loose and left in place where it is often quite inaccessible. It is when eradicating an infection, however, when the entire cement mantle needs to be accounted for and eliminated, that the surgical effort to accomplish this becomes quite involved. Damage to the soft tissues as well as neurovascular structures can occur and, even in the best of circumstances, significant bone stock is removed along with the cement. To address the subsequent bone loss, Zimmer (Warsaw, Ind., USA) markets a method whereby new bone is introduced through impaction grafting around a repeat cement mantle when a second implant is placed in a revision arthroplasty setting. With patients living longer and more active lives, it is of paramount importance to offer an implant that can be rigidly placed but then also removed without undue trauma to the bones and the soft tissue envelope into which they gain fixation. [0015] The use of cement has the potential added drawback of causing thermal osteonecrosis. The cement is inserted at room temperature into the intramedullary canal to secure an implant and employs an exothermic reaction to become hard. This high temperature may damage the surrounding bone and potentially compromise its ability to heal after implant installation. It may also hinder new bone growth advantageous to helping secure the implant after installation. [0016] Elbow arthroplasty carries serious potential complications. The most dire complication is the development acute, subacute, or chronic infections. The soft tissue envelope that surrounds the elbow is thin, thereby making this location vulnerable to this complication. The incidence of deep infections after Total Elbow Arthroplasty lies between 3 and 8%. Kim J M, Mudgal C S, Konopka J F et al. Complications of Total Elbow Arthroplasty , J AM ACAD ORTHOP SURG 2011; 19 (6):328-339; Tachihara A, Nakamura H, Yoshioka T et al., Postoperative Results and Complications of Total Elbow Arthroplasty in Patients with Rheumatoid Arthritis: Three Types of Nonconstrained Arthroplasty , MOD RHEUMATOL 2008; 18 (5):465-471; Gschwend N, Simmen B R, Matejovsky Z. Late Complications in Elbow Arthroplasty , J SHOULDER ELBOW SURG 1996; 5 (2 Pt 1):86-96. The causative organism is usually Staph. Aureus or Epidermidis. Staph. Epidermidis is considered more virulent due to its ability to form biofilms. In most patients the time span between index arthroplasty and revision is more than three weeks and spontaneous drainage after ten days may be indicative of deep bacterial colonization. Kim J M, Mudgal C S, Konopka J F et al. Complications of Total Elbow Arthroplasty , J AM ACAD ORTHOP SURG 2011; 19 (6):328-339. [0017] Infections after Total Elbow Arthroplasty should be managed aggressively and resection arthroplasty may be warranted. Resistant infections are managed by hardware removal and debridement of all affected structures including bone, soft tissues and bone cement. Because of the significant recurrence rate, re-implantation should only be performed cautiously given that prosthesis survival is significantly diminished in those cases (77% 3-year, 48% 8-year survival). Kim J M, Mudgal C S, Konopka J F et al. Complications of Total Elbow Arthroplasty , J AM ACAD ORTHOP SURG 2011; 19 (6):328-339. Given that the cement must be removed in addition to the implant in order to eradicate the infection, the likelihood of having reasonable bone stock remaining after the implant and bone cement has been removed is low. Realizing the low survival rate of the second implant, the decision to re-implant a new arthroplasty is often met with significant resistance. Most patients do not want to undergo a re-implantation effort. Having an implant system that contains no cement and can be removed much more easily when compared to its cemented brethren would minimize the bone loss associated with implant removal and increase the likelihood of subsequent re-implantation. [0018] Peri-prosthetic loosening may occur after implantation and often requires revision surgical efforts. Bennett J B, Mehlhoff T L. Total Elbow Arthroplasty: Surgical Technique , J HAND SuRG AM 2009; 34 (5):933-939. To ensure longevity, patients must be willing to accept a lifelong 5-lb lifting restriction to that extremity. Bennett J B, Mehlhoff T L. Total Elbow Arthroplasty: Surgical Technique , J HAND SURG AM 2009; 34 (5):933-939. In general, the ulnar components are at the highest risk for aseptic loosening and this risk is associated with the quality of fixation. An estimated 7 to 17% of all total elbow arthroplasties show clinical loosening, whereas the rate of radiographic loosening is even higher. Kim J M, Mudgal C S, Konopka J F et al. Complications of Total Elbow Arthroplasty , J AM ACAD ORTHOP SURG 2011; 19 (6):328-339. Tachihara A, Nakamura H, Yoshioka T et al. Postoperative Results and Complications of Total Elbow Arthroplasty in Patients with Rheumatoid Arthritis: Three Types of Nonconstrained Arthroplasty , MOD RHEUMATOL 2008; 18 (5):465-471; Gschwend N, Simmen B R, Matejovsky Z. Late Complications in Elbow Arthroplasty , J SHOULDER ELBOW SURG 1996; 5 (2 Pt 1):86-96. The design of a semi-constrained elbow prosthesis, allowing for an element of varus-valgus laxity, is thought to reduce the incidence of aseptic loosening. Ensuring both accurate implant positioning as well as excellent cement fixation are crucial to minimize stress on the implant as well as the development of aseptic loosening. Kim J M, Mudgal C S, Konopka J F et al. Complications of Total Elbow Arthroplasty , J AM ACAD ORTHOP SURG 2011; 19 (6):328-339. Revision arthroplasty should be considered in the setting of instability and pain. When this happens, both the prosthesis and cement should be removed using adequate instruments. Sometimes an osteotomy or the creation of bone windows is needed. Cementless implantation is rarely employed. Uncemented elbow arthroplasty in rheumatoid arthritis patients was described utilizing the Kudo prosthesis which demonstrated a high rate of aseptic loosening (7 of 49) within the ulnar component ultimately leading to an inability to recommend this implant without the use of cement fixation. Brinkman J M, de Vos M J, Eygendaal D. Failure Mechanisms in Uncemented Kudo Type 5 Elbow Prosthesis in Patients with Rheumatoid Arthritis: 7 of 49 Ulnar Components Revised Because of Loosening After 2-10 years , ACTA ORTHOP 2007; 78 (2):263-270. [0019] Periprosthetic fracture after primary total elbow arthroplasty occurs with an incidence of 5 to 29% with underlying causes including direct trauma, osteoarthritis, or aseptic loosening. Kim J M, Mudgal C S, Konopka J F et al. Complications of Total Elbow Arthroplasty , J AM ACAD ORTHOP SURG 2011; 19 (6):328-339. Tachihara A, Nakamura H, Yoshioka T et al. Postoperative Results and Complications of Total Elbow Arthroplasty in Patients with Rheumatoid Arthritis: Three Types of Nonconstrained Arthroplasty , MOD RHEUMATOL 2008; 18 (5):465-471; Hildebrand K A, Patterson S D, Regan W D et al. Functional Outcome of Semiconstrained Total Elbow Arthroplasty , J BONE JOINT SURG AM 2000; 82-A (10):1379-1386; O'Driscoll S W, Morrey B F. Periprosthetic Fractures about the Elbow , ORTHOP CLIN NORTH AM 1999; 30 (2):319-325. Periprosthetic elbow fracture treatment has been characterized in the literature. O'Driscoll S W, Morrey B F. Periprosthetic Fractures about the Elbow , ORTHOP CLIN NORTH AM 1999; 30 (2):319-325; Foruria A M, Sanchez-Sotelo J, Oh L S et al. The Surgical Treatment of Periprosthetic Elbow Fractures Around the Ulnar Stem Following Semiconstrained Total Elbow Arthroplasty , J BONE JOINT SURG AM 2011; 93 (15):1399-1407; Sanchez-Sotelo J, O'Driscoll S, Morrey B F. Periprosthetic Humeral Fractures After Total Elbow Arthroplasty: Treatment with Implant Revision and Strut Allograft Augmentation , J BONE JOINT SURG AM 2002; 84-A (9):1642-1650. [0020] Not all fractures require surgical treatment and immobilization may be sufficient in some cases. With significant displacement, open reduction and internal fixation should be performed. In these cases the bone stock at the fracture site dictates the technique used such as cerclage wiring or plate fixation. A significant hardship when treating periprosthetic fractures involves the cement mantle that surrounds the implant. As it lies within the fractured bone and exhibits no healing capability, the cement often has to be removed and then the void filled with bone graft. Not all periprostetic fractures are associated with implant loosening yet frequently these two occur in combination mandating a revision-arthroplasty effort in addition to the fracture open reduction and internal fixation. Sanchez-Sotelo J, O'Driscoll S, Morrey B F. Periprosthetic Humeral Fractures After Total Elbow Arthroplasty: Treatment with Implant Revision and Strut Allograft Augmentation , J BONE JOINT SURG AM 2002; 84-A (9):1642-1650. Some cases even require two-staged treatment where fracture union is achieved first and revision arthroplasty is done in a second step. Tokunaga D, Hojo T, Ohashi S et al. Periprosthetic Ulnar Fracture After Loosening of Total Elbow Arthroplasty Treated by Two - Stage Implant Revision: A Case Report , J SHOULDER ELBOW SURG 2006; 15 (6):e23-26. If significant loss of bone stock is present within the distal humerus or proximal ulna, successful surgical revision may not be possible leading to salvage options such as an arthrodesis or leaving the elbow flail or even consideration of an amputation. [0021] Other complications may occur that are unrelated to the method of component fixation. For example, ulnar nerve irritation is a concern with any extensive surgery around the elbow and triceps insufficiency may occur either in the acute or later stages. [0022] Bone cement implantation syndrome (BCIS) is a unique problem associated with cement fixation of an implant. It occurs primarily in association with cemented Total Hip arthroplasty. It is characterized by hypoxia, hypotension or both and/or unexpected loss of consciousness occurring around the time of cementation, prosthesis insertion, reduction of the joint or, occasionally, limb tourniquet deflation in a patient undergoing cemented bone surgery. Bone cement implantation syndrome (BCIS) is poorly understood and yet is an important cause of intraoperative mortality and morbidity in patients undergoing cemented hip arthroplasty and may also be seen in the postoperative period in a milder form causing hypoxia and confusion. Currently, when preparing for cementation, the anesthesiologist is informed that the cementation process is being started so as to closely monitor any adverse intra-operative effect. Our design does not include cement fixation at all and, thereby, eliminates this risk. A. J. Donaldson, H. E. Thomson, N. J. Harper and N. W. Kenny. Bone cement implantation syndrome , BR J ANAESTH 2009; 102: 12-22. [0023] Different devices for the prosthetic treatment of the elbow joint have been developed. Commercially available systems for elbow arthroplasty at the present time include: 1. Solar® total elbow system, sold by Stryker Orthopaedics, which is a linked hinge design that employs cement fixation. 2. GBS III Elbow System, sold by Sulzer Orthopedics, which is an unlinked, cemented total elbow system. 3. Coonrad/Morrey Total Elbow, sold by Zimmer Inc., which is a linked hinge system that employs cement fixation. 4. Discovery elbow system, sold by Biomet, which is a linked, cemented total elbow system. 5. IBP Elbow System, sold by Biomet, which is a linked, cemented total elbow system. 6. Biomet Huene BiAxial Elbow System, sold by Biomet, which is a linked, cemented total elbow system. 7. DePuy Pritchard ERS (DePuy, USA)—not currently marketed 8. Latitude Total Elbow, which is a modular, convertible, cemented total elbow system. 9. Stryker Howmedica Souter-Strathclyde, which is sold by Stryker, and which is not currently marketed. 10. Stryker Howmedica Kudo type 5 elbow prosthesis, sold by Stryker, and which is not currently marketed. 11. Stryker Osteonics elbow prosthesis, sold by Styker, which is a linked, cemented total elbow system. This system is not currently marketed. 12. Volz AHSC elbow prosthesis, which is not presently marketed. 13. Wright Sorbie-Questor Total Elbow Systems, sold by Wright, which is an unlinked, cemented total elbow system. This system is not currently marketed. 14. Acclaim Total Elbow System, sold by DePuy, which is a convertible, cemented total elbow system. This system is not currently marketed. 15. Biopro Total Elbow System, which is sold by Biopro Inc., USA. This system is not currently marketed. [0039] All of the above elbow prostheses are secured to the respective bones with bone cement and, therefore, carry all of the disadvantages inherent in bone cement. [0040] Numerous other elbow prostheses have been proposed. For example, U.S. Pat. No. 2,696,817 discloses a prosthetic elbow joint comprising two threaded shafts that are separately inserted into the medullary canals. The threads of each shaft cut mating threads or grooves in the walls of the bone cavity to prevent axial displacement and rotational displacement. After installation into the respective bones, these shafts are connected with a low friction bearing. [0041] U.S. Pat. No. 3,547,115 discloses a prosthetic replacement of the articular surface of the distal humerus that is attached by trimming the bone to match the inner surface of the prosthesis and is locked in place by a keyhole-type mechanism. An intramedullary stem fixation method is not intended. This patent only replaces the distal humerus. [0042] U.S. Pat. No. 3,708,805 discloses a prosthetic elbow joint. The humeral member and ulnar member are connected to form a hinge. The male portion of the hinge corresponds to the surface of the female portion of the hinge to avoid tissue being trapped therein. The stems used to cement each component to the bone are non-round to prevent rotation, and tapered to facilitate removal. The ulnar stem is curved eight inches, and the humerus stem is curved three inches. The elbow joint itself is angled to correspond to a natural elbow. This joint is designed for assembly prior to insertion. The hinge appears to prohibit any varus and valgus laxity. [0043] U.S. Pat. No. 3,772,709 discloses an elbow prosthesis having a humeral component made of steel, and an ulnar component made of silicone. The components are held together using a metal pin, and are secured to the respective bones using cement. [0044] U.S. Pat. No. 3,816,854 discloses a prosthesis for total arthroplasty of the elbow joint. The humeral and ulnar components are cemented to the bones with stems having a square cross-section. The ulnar component includes a cylindrical polyethylene bearing that articulates with a mating concave cylindrical surface defined by the humeral component. [0045] U.S. Pat. No. 3,852,831 discloses an endoprosthetic elbow joint. The elbow joint includes a humeral component including a cylindrical bearing surface that is widest at its ends, tapering to a narrow center. This component articulates with an ulnar component that is saddle shaped. The wear surface of the ulnar component can be releasably connected with a dovetail connection. The humeral and ulnar components are retained together by the patient's joint capsule, making this an unconstrained joint. [0046] U.S. Pat. No. 3,868,730 discloses a knee or elbow prosthesis. This prosthesis incorporates a coupled ball and socket connection. Although the title indicates that either an elbow or knee could be replaced, this reference is directed primarily towards knee replacement. A ball on a connecting rod extending upwardly from the tibial component is enclosed by a high density polyethylene socket insert retained within the bottom of the femoral component. The joint is designed to permit a slight degree of twisting or wobbling. [0047] U.S. Pat. No. 3,919,725 discloses a hingeless endoprosthetic device for the elbow joint that comprises humeral and ulnar components. The cylindrical humeral surface is intramedullary fixed. The complementary ulnar component is made from silicone and sits within the ulna. The absence of long stems going into the bone is described as an advantage by this reference, providing for ease of installation and less removal of bone. The hingeless design is called advantageous due to the ease of installation and reduced chances of loosening. This unconstrained device requires that the patient's natural soft tissues are functional. [0048] U.S. Pat. No. 3,939,496 discloses an endoprosthetic joint. The joint includes a humeral component having a pair of spherical bearing members. The ulnar component has a bearing block. Each component is secured on the bone by a long, grooved stem that is anchored by acrylic cement. The grooves key the stem to the acrylic. When installed, a pin passes through the bearings and bearing block to form a hinge. Once the joint capsule heals, the pin is removed to reduce distraction stresses. This joint is, therefore, convertible between a constrained and unconstrained design. [0049] U.S. Pat. No. 3,990,117 discloses an implantable elbow prosthetic joint with cemented stems that articulate in a simple hinged mechanism. Varus and valgus forces are accounted for by allowing “wobble” to avoid damaging the pin assembly, and to place these forces between the shoulders of the implant. [0050] U.S. Pat. No. 3,991,425 discloses a prosthetic joint. The prosthetic joint includes ceramic components having mating concave and convex condylar surfaces. Intersecting lands are provided for stopping motion at the joint's extended and contracted positions. Each of the mating components also includes a stem for implantation in the appropriate medullary canals. [0051] U.S. Pat. No. 4,008,495 discloses a prosthetic bone joint. This joint is designed for minimal bone removal. The humeral component is a pair of frustoconical shapes joined at their narrow ends, which is installed by wedging the component into the intracondylar notch. The ulnar component is made from polymer, and includes a convex bearing surface. The ulnar component is held in place by a bone screw as well as acrylic cement. [0052] U.S. Pat. No. 4,057,858 discloses an elbow prosthesis. This prosthesis includes a humeral component defining a groove in the shape of the helix for mating with a concave surface of the ulnar component. The obliquity of the groove within the trochlea allows the ulnar implant to move into valgus during elbow extension and varus in flexion. A second groove may mate with a radial component. This prosthesis is therefore unconstrained. All components include stems that are secured to the bone by cement. [0053] U.S. Pat. No. 4,079,469 discloses an elbow joint endoprosthesis. The humeral component defines a T-shaped channel for receiving an I shaped portion of the ulnar component. The humeral component includes short longitudinal and transverse keys for securing to the bone. The humeral component also includes a surface for bearing against a radial component. The humeral component is made from polymer, and the ulnar component is made from chrome cobalt. The joint allows minimal varus and valgus yet allows for flexion and extension motion. [0054] U.S. Pat. No. 4,129,902 discloses an elbow prosthesis. The humeral component is connected to an ulnar component by a shaft on the humeral implant and a sleeve on the ulnar implant, providing for hinged articulation between these components. Both implants include tapered stems that are cemented into the bone. A radial implant includes a metal shaft that rotates within a polymer sleeve, and is connected to the humeral component by a chain. [0055] U.S. Pat. No. 4,131,956 discloses an elbow prosthesis. The humeral component includes a U-shaped section holding a non-rotatable polyethylene head. The ulnar component includes a corresponding curved surface for forming an unconstrained joint. Both components include spikes that are cemented into the bone. [0056] U.S. Pat. No. 4,224,695 discloses an endoprosthetic elbow joint. The joint provides a hinged connection between the humeral component, ulnar component, and radial component. The radial component permits rotation around the axis of the radius as well as around the hinge joint. No varus and valgus laxity is allowed between the humerus and ulna. [0057] U.S. Pat. No. 4,242,758 discloses an elbow prosthesis. The humeral components are a tube shaped metal piece with three generally spherical surfaces. A very accurate reproduction of the distal humerus articular surface is provided. It can be used either with an ulnar or a radial replacement or in isolation in which it acts as a hemi-arthroplasty. The ulnar component includes a concave plastic bearing surface with a metal support. The radial component includes a metal pin with a plastic, concave bearing surface. The joint appears unconstrained. [0058] U.S. Pat. No. 4,280,231 discloses an elbow prosthesis. The humeral component includes a pair of sides connected by a cylindrical cross member. The ulnar component has a hook for engaging the cylindrical cross member. Both components include stems for securing to the bones with acrylic cement. The humeral member also includes a surface for engaging the radius. [0059] U.S. Pat. No. 4,293,963 discloses an unconstrained elbow prosthesis. The prosthesis includes a humeral component having an elongated stem and a substantially cylindrical, convex articulating surface. The ulnar component includes a metal retainer with a polyethylene bearing. The metal retainer includes an elongated stem depending from a metal base, and which is slightly curved. The bearing includes a concave cylindrical cavity for receiving the cylinder of the humeral component. A limited amount of medial-lateral motion in addition to flexion and extension is allowed. [0060] U.S. Pat. No. 4,383,337 discloses an elbow prosthesis. The humeral member has a stem and a flange on either side for retaining a bushing as well as a spherical surface for engaging a radial member or a radius. The ulnar member has a stem, a concave surface, and a central projection ending in a cylinder. The projection fits within the bearing. The radial member includes a concave surface. This implant is intended to be a semi constrained joint. The patent claims that the joint is capable of handling up to 50 kg of force. [0061] U.S. Pat. No. 4,538,306 discloses an elbow prosthesis having a humeral component consisting of a sleeve with a circumferential slot. A cylindrical sliding member fits inside the sleeve, abutted by the sides of a slot cut into the humerus. The shaft is inserted through the slot in the sleeve, and secured to the sliding member. The shaft is secured within a hole in the ulna. The shaft and sliding member can, therefore, pivot with respect to the sleeve, forming a hinge. The shaft includes ridges for better retention within the ulna. [0062] U.S. Pat. No. 4,681,590 discloses a femoral stem prosthesis. The prosthesis includes an elongated stem portion, and a ball shaped head. The stem portion includes one or more elongated resilient spring strips which are acted upon by an adjustable screw to cause the spring strips to bow outwardly into engagement with the canal walls. [0063] U.S. Pat. No. 4,840,633 discloses a cementless endoprosthesis. The prosthesis includes a stem that is tapered towards its distal end. A pair of windows are defined the proximal area of the stem. The endoprosthesis further includes a screw spindle having a broad flanged thread in the form of a helix. The thread projects from the windows on either side of the endoprosthesis. Turning the screw spindle causes the helical broad flanged thread to cut into the adjacent bone structure, thereby securing the implant in place. This endoprosthetic stem provides for a load transmission exclusively into the proximal portion of the bone, while the distal portion is free of axial loads. [0064] U.S. Pat. No. 5,167,666 discloses an endoprosthesis for a femur. The endoprosthesis includes a stem that is hollow, slotted, flexible and intended to avoid placing pressure on the bone at this point. A collar and clamping cone are located at the upper end of the endoprosthesis. A tension anchor includes a screw that passes through the femur and is fastened to the prosthesis collar. [0065] U.S. Pat. No. 5,314,484 discloses a biaxial elbow joint replacement. The joint replacement includes a hinge block having an ulnar pivot as well is a humerus pivot. Each pivot permits movement through about 90°. A spike is attached to each pivot for cementing within the respective bone. The design is intended to minimize the transfer of stresses from one component to the other. [0066] U.S. Pat. No. 5,376,121 discloses a dual constraint elbow prosthesis. The prosthesis includes humeral and ulnar members consisting of a spike for insertion into the bone, and the yoke for connecting to a connecting link. The spikes are intended to be secured with cement. The pivot dimensions for the ulnar member are intended to permit a slight sideways rocking, while the humeral member is more constrained. The prosthesis permits 16° of varus and valgus laxity as well as 10° of rotational laxity between the humeral and ulnar components with the hope that this would decrease polyethylene wear. Pivotal rotation that decreases torque is described. By using two axes of rotation, this design reproduces the anterior translocation of the ulna during motion. [0067] U.S. Pat. No. 5,458,654 discloses a screw fixed femoral component for a hip joint prosthesis. The prosthesis includes an intramedullary stem as well as a portion for receiving a ball head. The stem has lateral screw holes defined therein. The stem is secured to the bone by drilling holes into the bone corresponding to the screw holes in the stem, and then driving screws into these holes. [0068] U.S. Pat. No. 5,667,510 discloses a system for fusing the middle and distal phalanx bones in the finger. [0069] U.S. Pat. No. 5,723,015 discloses an elbow prosthesis. The prosthesis includes an ulnar component having a head for receiving the spindle of the humeral components. A ring-like clip retains the spindle within the head. Both components have stems that are cemented into the intramedullary canal. Some play is permitted between the spindle and the clip. [0070] U.S. Pat. No. 5,782,923 discloses an endoprosthesis for an elbow joint. The endoprosthesis includes hingedly connected humeral and ulnar components, each of which having a shaft for engagement in the bone canal. The ulnar component includes a lateral flange having a socket for guiding a sliding member. A radial component has a head portion that is swingingly mounted in the sliding member, thereby providing ball and socket articulation. The radial portion is, therefore, both swingable and displaceable with respect to the ulnar portion. The stems for the humeral, ulnar and radial components are cemented. [0071] U.S. Pat. No. 5,879,395 discloses a total elbow prosthesis. The prosthesis includes cooperating humeral and ulnar elements. A radial element is provided with a ball that fits within a concave surface defined within the humeral element. [0072] U.S. Pat. No. 6,027,534 discloses a modular elbow. The elbow includes humeral and ulnar components having stems for implantation in the intramedullary canals of the respective bones, and body portions that are each designed to receive bearings. The humeral member includes a pair of arms with a pivot extending therebetween, upon which one of the bearings may be placed. The ulnar member includes a slot for receiving a bearing member. The elbow may be used in an unconstrained manner by placing a generally cylindrical bearing on the humeral portion and a bearing having a concave surface on the ulnar portion. Alternatively, the implant may be used in a constrained manner by using a single bearing connected to both the humeral and ulnar components. A similar device is disclosed in U.S. Pat. No. 6,290,725 and U.S. Pat. No. 6,699,290. [0073] U.S. Pat. No. 6,126,691 discloses a bone prosthesis fixation device. The mechanism includes a main body for implantation within the canal of a bone. The main body includes an internal passageway, as well as a plurality of openings extending between the passageway and the exterior of the main body. A plurality of bone engaging members are reciprocally positioned within each opening. When a plunger is passed into the internal passageway, the bone engaging members are pushed outward, thereby engaging the bone and securing the prosthesis into the bone. A second embodiment also provides a prosthetic device implantable into skeletal bone and has an elaborate gear system that rotates screws that gain fixation into the intramedullary canal. [0074] U.S. Pat. No. 6,162,253 discloses a total elbow arthroplasty system that is intended for use in dogs, but for which the patent also recites possible use in humans. The device includes a combined radio-ulnar component having stems for installation into the canals of both the radius and the ulna. A concave surface on this component mates with a convex surface on the humeral components. [0075] U.S. Pat. No. 6,306,171 discloses a total elbow arthroplasty system that is intended primarily for use in dogs, but for which the patent also recites possible use in humans. The implant includes a radial component having an isometric ball component that fits within a corresponding humeral component to form an unconstrained joint. [0076] U.S. Pat. No. 6,379,387 discloses an elbow prosthesis. The elbow prosthesis includes a humeral component having a substantially cylindrical articulating surface that is concave, with its narrowest portion near the center of the part that interacts with the ulnar component. An ulnar component includes a second articulating surface having a concave portion structured to articulate with the humeral component, and having a convex surface to correspond to the surface of the cylindrical articulating surface. Varus and valgus movement is, therefore, permitted while retaining contact between the humeral and ulnar articulating surfaces. The ulnar component further includes a locking element forming an additional articulating surface, so that the total articulating surface of the ulnar component can extend over more than 180° of the humeral articulating surface. The locking element may be omitted if the surgeon realizes that the tendons and ligaments of the joint are in good condition. A portion of the humeral component's articulating surface extends beyond the retaining arms and interfaces with a radial component. A similar elbow prosthesis is disclosed in U.S. Pat. No. 6,760,368. [0077] U.S. Pat. No. 6,475,242 discloses a plastic joint assembly. The joint assembly includes a flexible U-shaped connector that is secured to adjacent bones by threaded connectors. [0078] U.S. Pat. No. 6,514,288 discloses a prosthetic femoral stem with a strengthening rib. [0079] U.S. Pat. No. 6,517,541 discloses an axial intramedullary screw for the ostia synthesis of long bones. The screw is used for connecting pieces of fractured bones. The screw includes two tips at opposing ends for interfacing with a screwdriver, and threads across the remainder of its length for cutting into the cortical bone of the medullary canal. The screw can be threaded into one portion of a bone fragment and then, after connecting another bone fragment at the fracture site, screwed in the opposite direction into the second fragment. [0080] U.S. Pat. No. 6,716,248 discloses a prosthetic joint that may be utilized to form either a single axis joint or a double axis joint, permitting the surgeon to decide which type to construct from the kit once the elbow has been exposed during surgery. A similar device is disclosed in U.S. Pat. No. 6,997,957. [0081] U.S. Pat. No. 6,890,357 discloses an elbow prosthesis similar to that of U.S. Pat. No. 6,379,387. The elbow prosthesis includes a humeral component having a substantially cylindrical articulating surface that is concave, with its narrowest portion near the center of the part that interacts with the ulnar component. An ulnar component includes a second articulating surface having a concave portion structured to articulate with the humeral component, and having a convex surface to correspond to the surface of the cylindrical articulating surface. Varus and valgus movement is, therefore, permitted while retaining contact between humeral and ulnar articulating surfaces. The ulnar component further includes a locking element forming an interconnection with an additional articulating surface, so that the total articulating surface of the ulnar component can extend 360°. The locking element may be omitted if the surgeon realizes that the tendons and ligaments of the joint are in good condition. A portion of the humeral component's articulating surface extends beyond the retaining arms, and interfaces with a radial component or native radial head. [0082] U.S. Pat. No. 7,247,170 discloses an elbow prosthesis. The ulnar component includes a pair of concave spherical bearing surfaces that interface with a pair of convex spherical bearing surfaces on the humeral components. An axis passing through the ulnar component connects the two bearing surfaces of the humeral components. The spherically shaped bearing surfaces are intended to transmit load over a relatively large area rather than at a point or over a line of contact. The surgeon may employ a modular flange for compressing a bone graft, a tissue fastener for securing soft tissue to a portion of the prosthetic joint, a cam for limiting the amount by which the prosthetic joint articulates or a bearing insert for tailoring the degree of varus/valgus constraint. [0083] U.S. Pat. No. 7,850,737 discloses a prosthetic elbow replacement. The elbow replacement includes a humeral component having a stem dimension to fit within a medullary canal of a humorous, as well as a J shaped flange for providing additional support of the implant with respect to the humerus. Both the stem and the J shaped flange include porous surface sections into which bone tissue can grow and/or bone cement can infiltrate. The humeral component also includes a yoke terminating in a pair of arms having a pivot connected therebetween. The pivot includes a through hole for use in attaching an ulnar component. The ulnar component also includes an ulnar stem having a porous surface portion. Varus and valgus motion is provided by movement of the ulnar component with respect to the through hole of the pivot. [0084] US 2005/0049710 discloses a prosthesis for partial replacement of an articulating surface on bone. The surfaces that are to be replaced are for the coronoid and the radial head. The fixation of these partial prostheses is done with headless and regular screws. [0085] US 2007/0185584 discloses a method and apparatus for digit joint arthroplasty. The method includes drilling and tapping the intramedullary canal, and then utilizing a threaded rod to secure the implants in place. The implant is intended to replace the articular surface of the bone with a similarly shaped metal surface, thereby avoiding the use of a hinge joint with a constant center of rotation, and maintaining the mechanical advantage of the flexor and extensor tendons in the same manner as the natural joint structure. Additionally, reproducing normal physiologic motion has the added benefit of limiting the stresses transmitted through the prosthesis to the stem-bone interface. [0086] US 2010/0179661 discloses an elbow prosthesis. The ulnar component includes a pair of concave spherical bearing surfaces that interface with a pair of convex spherical bearing surfaces on the humeral components. An axis passing through the ulnar component connects the two bearing surfaces of the humeral component. The spherically shaped bearing surfaces are intended to transmit load over a relatively large area rather than at a point or over a line of contact. The prosthesis is provided in the form of a joint kit having a plurality of interchangeable bearing inserts which permit the surgeon to tailor the degree of varus/valgus constraint. Some examples can be linked together without fasteners or other hardware. [0087] US 2012/0109322 discloses a prosthesis to replace at least a portion of a comminuted bone fracture. The prosthesis reproduces the articular surface of a comminuted distal humerus fracture in order to restore joint viability and articulation. [0088] From the above description, it is clear that the vast majority of elbow prostheses are secured utilizing bone cement and, therefore, carry all of the inherent disadvantages of bone cement. Of the minority that are secured by screws, the hinge components of many of these implants must be turned along with the threaded shaft, preventing the hinge portion of the implant from being pulled precisely into the correct position and orientation within the bone. Furthermore, threaded attachments are subject to loosening if not further secured by some additional means. Accordingly, there is a need for a mechanical fastener that pivots with respect to the hinge component of the implant, thereby positioning the hinge portion in the correct position at whatever point the mechanical fastener reaches its maximum depth. There is a further need for a threaded or other mechanical attachment for securing implant components to bone that includes both a major loadbearing portion, and a secondary securing portion to ensure the stability of the major loadbearing portion. [0089] Although it is often difficult for a surgeon to know whether a hemiarthroplasty or total arthroplasty will be required prior to commencing surgery, very few of the implants described above may be used for either type of surgery. Accordingly, there is a need for a prosthetic elbow that may be interchangeably used for hemiarthroplasty and total arthroplasty, permitting the surgeon to decide between the two operations mid-surgery. [0090] Numerous methods have been proposed for permitting varus/valgus movements, thereby reducing stresses on the elbow prosthesis as well as the bones to which the prosthesis is attached. However, none of these methods has included any type of ligament reconstruction that would essentially reproduce that which was present in the elbow prior to injury or deterioration. Accordingly, there is a need for an elbow prosthesis that is installed in a manner that includes ligament reconstruction. [0091] All mechanical devices are subject to wear. It is, therefore, helpful to have specific, easily replaceable components that are subject to wear in preference to other, more critical, and more difficult to replace components. Structures which are designed to wear in preference to other structures, and which are easily replaced during simple follow-up surgeries, are therefore needed. SUMMARY [0092] The above needs are met by a prosthetic joint. One example of the prosthetic joint has a first component having a first intramedullary stem and a first connection portion. The first intramedullary stem is externally threaded and being pivotally secured to the first connection portion. The prosthetic joint further includes a second component having a second intramedullary stem and a second connection portion. The second intramedullary stem being externally threaded and being pivotally secured to the second connection portion. The second connection portion is structured to be movably secured to the first connection portion. [0093] Another example of the prosthetic joint includes a first component having a first intramedullary bone securing portion and a first connection portion. The first connection portion is structured so that it can mate with a natural second bone end or a reconstructed second bone end without modification to the first connection portion. [0094] Yet another example of the prosthetic joint includes a first joint component that is structured for attachment to a first bone. The first joint component being structured to secure a portion of a ligament reconstruction member. The prosthetic joint further includes a second joint component that is structured for attachment to a second bone. The second joint component is structured to secure a portion of a ligament reconstruction member. [0095] A method of installing a prosthetic joint is also provided. One example of the method is carried out by first providing a prosthetic joint having first and second assemblies. The first assembly has a first threaded intramedullary securing member rotatably secured to a first connection portion. The second assembly has a second threaded intramedullary securing member rotatably secured to a second connection portion. The intramedullary canal of the first bone is broached, drilled, and tapped. The first threaded intramedullary securing member is installed into the intramedullary canal of the first bone. The first threaded intramedullary securing member is used to draw the first connection portion into the intramedullary canal of the first bone. The intramedullary canal of the second bone is broached, drilled, and tapped. The second threaded intramedullary securing member is installed into the intramedullary canal of the second bone. The second threaded intramedullary securing member is used to draw the second connection portion into the intramedullary canal of the second bone. [0096] Another example of the method of installing a prosthetic joint between a first bone and a second bone begins by attaching a first joint component to the first bone. A second joint component is attached to the second bone. At least one tendon is removed. A portion of the tendon is secured to the first joint component. Another portion of the tendon is secured to the second joint component. [0097] These and other aspects of the invention will become more apparent through the following description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0098] FIG. 1 is an isometric view of a prosthetic joint. [0099] FIG. 2 is an isometric view of the hinge portion of a prosthetic joint. [0100] FIG. 3 is a side view of the prosthetic joint. [0101] FIG. 4 is a partially cutaway isometric view of a second prosthetic joint component, showing the second prosthetic joint component engaging a spool attached to a first prosthetic joint component. [0102] FIG. 5 is an isometric view of a base for a connection portion of a second joint components for a prosthetic joint. [0103] FIG. 6 is an isometric view of a bearing retaining bracket. [0104] FIG. 7 is a cross-sectional side view of a broaching process for installation of a prosthetic joint component. [0105] FIG. 8 is a cross-sectional side view of a drilling process for installation of a prosthetic joint component. [0106] FIG. 9 is a cross-sectional side view of a tapping process for installation of a prosthetic joint component. [0107] FIG. 10 is a cross-sectional side view of a prosthetic joint component being installed within a bone. [0108] FIG. 11 is a cross-sectional side view of a spool for a prosthetic joint component being installed. [0109] FIG. 12 is a cross-sectional front view of a broaching process for installation of a prosthetic joint component. [0110] FIG. 13 is a cross-sectional front view of a drilling process for installation of a prosthetic joint component. [0111] FIG. 14 is a cross-sectional front view of a tapping process for installation of a prosthetic joint component. [0112] FIG. 15 is a cross-sectional front view of a prosthetic joint component being installed within a bone, showing the prosthetic joint component partially installed. [0113] FIG. 16 is a cross-sectional front view of a prosthetic joint component being installed within a bone, showing the final position of the prosthetic joint component. [0114] FIG. 17 is a cross-sectional side view showing the insertion of ligament reconstruction members through the first prosthetic joint component. [0115] FIG. 18 is a cross-sectional side view showing the attachment of ligament reconstruction members to the second prosthetic joint component, as well as the installation of cross locking members. [0116] FIG. 19 is a cross-sectional side view of a ligament reconstruction for a prosthetic joint. [0117] FIG. 20 is a cross-sectional front view of a prosthetic joint after installation for a hemiarthroplasty. [0118] FIG. 21 is a cross-sectional front view of a prosthetic joint after installation for a total arthroplasty. [0119] FIG. 22 is an isometric view of a connection portion for a humeral component of a prosthetic joint. [0120] FIG. 23 is an isometric view of a bearing for a prosthetic joint. [0121] FIG. 24 is a side elevational view of the bearing of FIG. 23 . [0122] Like reference characters denote like elements throughout the drawings. DETAILED DESCRIPTION [0123] Referring to the drawings, an example of a prosthetic joint 10 is illustrated. As shown in FIG. 1 , the illustrated example of the prosthetic joint 10 is a hinge joint, with the specific example illustrated being an elbow joint. The prosthetic joint 10 includes a first component 12 , which in the illustrated example is a humeral component utilized for reconstruction of the distal end of a humerus. The prosthetic joint 10 further includes a second component 14 , which in the illustrated example is an ulnar components for use in reconstructing the proximal end of an ulna. [0124] The humeral component 12 includes an intramedullary stem 16 that is rotatably and removably secured to a connection portion 18 . The intramedullary stem 16 is structured for uncemented, mechanical securing within the intramedullary canal of the humorous. The illustrated example of the intramedullary stem 16 includes a threaded portion 20 disposed at one end, that is structured to engage a portion of the intramedullary canal that has been tapped with corresponding threads as described in greater detail below. The opposite end of the intramedullary stem 16 includes a head 22 , which in the illustrated example has a slightly larger diameter than the immediately adjacent portion of the intramedullary stem 16 . The tip 24 of the head 22 includes actuator engaging structures 26 that are structured to engage a rotatable actuation school. For example, the actuator engaging structures 26 could be a slot for a slotted screwdriver, a cross shaped slot for a Phillips head screwdriver, a hexagon shaped hole for an Allen wrench, a star shaped hole for a Torx screwdriver, or any other conventional actuator engaging structure. [0125] Referring to FIGS. 1-4 and 22 , the connection portion 18 of the humeral component 12 in the illustrated example includes a yoke 28 having first and second legs 30 , 32 , respectively, extending therefrom. The yoke's base 34 defines a channel 36 therein. As shown in FIG. 3 , the channel 36 includes a narrow portion 38 that is a suitable diameter to receive the majority of the intramedullary stem 16 , but is too narrow to receive the head 22 . The channel 36 further includes a wider portion 40 having a sufficient diameter to receive the head 22 . The intramedullary stem 16 may therefore be placed within the channel 36 , where it is free to rotate, but where the head 22 is prevented from passing into the narrow portion 38 of the channel 36 . A hole 35 is defined within the connection portion 18 for securing a cross locking member 33 , as described in more detail below. [0126] The distal ends 42 , 44 of the legs 30 , 32 , respectively are structured to removably secure a spool 46 therebetween. In the illustrated example, openings 48 , 50 are defined within the distal ends 42 , 44 of the legs 30 , 32 . The holes 48 , 50 are each structured to receive a fastener such as the illustrated screws 52 ( FIG. 7 ) passing therethrough and into corresponding threaded holes 53 defined within the spool 46 . The spool 46 is generally cylindrical, and has a generally concave bearing surface 54 extending between its ends. The end 56 of the spool 46 corresponding to the leg 32 is generally flat, and the end 58 of the spool 46 corresponding to the leg 30 is partially spherical. The spool 46 therefore has a shape that generally corresponds to the shape of the distal end of an undamaged humerus. A central bore 53 passes through the spool 46 , with corresponding holes 55 , 57 being defined within the distal ends 42 , 44 of the legs 30 , 32 , respectively. [0127] Referring to FIGS. 20 and 22 , the humeral portion 12 includes a cross locking member 33 . In the illustrated example, the cross locking member 33 is a screw passing through a corresponding opening 35 defined within the connection portion 12 . The screw 33 is secured at the opposite and of the hole 35 by a nut 37 . [0128] Referring to FIGS. 1-6 , the ulnar component 14 includes in intramedullary stem 60 and a connection portion 62 . The intramedullary stem 60 is structured for mechanical, cementless installation into the intramedullary canal of an ulna. In the illustrated example, the distal end 64 of the intramedullary stem 60 is threaded, so that it may engage corresponding threads that have been tapped into the ulna intramedullary canal. The proximal end of the intramedullary stem 60 includes a head 66 , having a larger diameter than adjacent portions of the intramedullary stem 60 . The tip 68 of the head 66 includes actuator engaging structures 70 that are structured to engage a rotatable actuation school. For example, the actuator engaging structures 70 could be a slot for a slotted screwdriver, a cross shaped slot for a Phillips head screwdriver, a hexagon shaped hole for an Allen wrench, a star shaped hole for a Torx screwdriver, or any other conventional actuator engaging structure. [0129] The connection portion 62 includes a base 72 . The base 72 defines a channel 74 therein. The channel 74 includes a narrow portion 76 that is structured to receive the intramedullary stem 60 , but not the head 66 . A wider portion 78 of the channel 74 is structured to receive the head 66 . The intramedullary stem 60 may therefore be placed within the channel 74 , and rotatably secured therein, in a manner that prevents the head from passing into the narrow portion 76 . The illustrated example includes a threaded hole 80 which, in the illustrated example, is coaxial with the channel 74 , and whose purpose will be explained below. [0130] The connection portion 72 further includes a bearing retention structure 82 . The bearing retention structure 82 includes a concave, generally circular interior surface 84 . A bearing retaining flange 86 is disposed at one and of the interior surface 84 . The other end of the interior surface 84 terminates adjacent to the threaded hole 80 . Referring specifically to FIGS. 5-6 , a pair of locating flanges 88 , 90 are disposed on either side of the threaded hole 80 . A bearing retaining bracket 92 , which is best illustrated in FIG. 5 , defines a generally circular surface 94 that is structured to form a continuation of the surface 84 , and terminating in a bearing retaining flange 96 . The opposite end of the bracket 92 defines a hole 98 therethrough, corresponding to the threaded hole 80 . A pair of slots 100 , 102 on either side of the hole 98 correspond to the locating flanges 88 , 90 , respectively, facilitating precise placement of the bracket 92 in the desired location. With the bracket in this position, a bearing 104 may be retained by the connection portion 14 . A screw 106 passing through the hole 98 and engaging the threaded hole 80 secures the bearing retaining bracket 92 to the base 72 . [0131] Referring to FIGS. 1-4 and 23-24 , the bearing 104 is generally half doughnut shaped, defining an interior, generally semicircular surface 108 , and an exterior, generally semicircular surface 110 . The bearing 104 preferably extends around at least about half of the spool 46 , but defines a sufficient opening to allow for easy installation of the bearing 104 on the spool 46 , for example, within a range of about 180° to about 270°. The bearing 104 in the illustrated example extends around about 236°. The interior surface 108 is generally convex, having a shape corresponding to the shape of the spool 46 . The exterior surface 110 defines a channel 111 therein for receiving the bearing retention structure 82 as well as the bracket 92 . The channel 111 is angled with respect to the circumference of the bearing 104 to accommodate the angle made by the bearing 104 with respect to the ulnar component 14 , which in the illustrated example is about 7°. The retaining flanges 86 , 96 are wider than the channel 111 so that the bearing 104 is properly retained. The bearing 104 is preferably made from a material having a wear resistance that is less than the wear resistance of the components with which it interfaces, so that the bearing 104 will experience wear in preference to other portions of the prosthetic joint. In the illustrated example, the bearing 104 is preferably made from polyethylene. [0132] Referring to FIGS. 17-20 , a cross locking assembly 114 for the ulnar component 14 is illustrated. The cross locking assembly 114 includes a plurality of cross locking members 116 , which in the illustrated example are screws. The cross locking screws 116 pass through corresponding holes 118 ( FIG. 4 ) defined it within the base 72 , and are retained by corresponding nuts 120 disposed on the opposite sides of the holes 118 . The screws 116 and nuts 120 also retain the bars 122 , 124 in place against the base 72 , for a purpose that will be described in greater detail below. [0133] A method of installing the first joint component within the first bone (installing the humeral portion within the distal end of the humerus 126 in the illustrated example) is illustrated in FIGS. 7-11 . This method remains the same regardless of whether a hemiarthroplasty or total arthroplasty is being performed. Initially, the damaged distal end of the humerus is cut with a saw. Next, as illustrated in FIG. 7 , the intramedullary canal 128 is broached to remove marrow, as well as to provide adequate room for a drilling jig, as well as ultimately for the humeral implant 12 . In some examples, three different sizes of brooches 130 may be utilized. [0134] As shown in FIG. 8 , a jig 132 is inserted into the intramedullary canal 128 , and is used to guide a drill 134 in further clearing the marrow from the intramedullary canal 128 . Successively larger drill bits are used until proprioceptive and or audible indications of drilling solid bone are heard. Once solid bone has been reached, the intramedullary canal 128 is tapped using a handheld tap 136 , as shown in FIG. 9 , thereby providing threads corresponding to the threads 20 of the intramedullary stem 16 . [0135] Referring to FIG. 10 , an appropriately sized intramedullary stem 16 and connection portion 18 are selected. It is anticipated that different sizes of intramedullary stem 16 and connection portion 18 may be provided, thereby accommodating patients of different sizes. Because the intramedullary stem 16 is removably secured to the connection portion 18 , the appropriate combination of parts may be selected. The intramedullary stems 16 is placed within the channel 36 , and is then threaded until secured within the intramedullary canal utilizing an appropriate screwdriver 138 or other suitable hand tool. Because the intramedullary stem 16 is rotatable with respect to the connection portion 18 , the connection portion 18 remains in the appropriate position for proper seating within the distal humerus 126 well-being drawn tightly into place by turning the intramedullary stem 16 . During this operation, the spool 46 is detached from the connection portion 18 in order to facilitate access by the tool 138 . [0136] Once the connection portion 18 is firmly seated in place, as shown in FIG. 11 , a hole corresponding to the hole 35 is drilled into the humerus 126 , and the cross locking screw 33 is inserted into the hole 35 . The nut 37 is added to complete the humeral cross locking structure. Next, the spool 46 is positioned between the legs 30 , 32 , and secured in place using the screws 52 . At this point, the end is surface of the distal humerus 126 has been restored, and may be utilized for either a hemiarthroplasty utilizing an undamaged proximal ulna, or a total arthroplasty by installing an ulnar component as described below. [0137] Referring to FIGS. 12-16 , a method of installing the ulnar joint portion 14 is illustrated. Initially, the proximal end of the ulna 140 is broached utilizing a hand-held broach 142 to remove marrow from the intramedullary canal 144 , as shown in FIG. 12 . Next, a jig 146 is positioned within the proximal end of the intramedullary canal 144 to guide a drill 148 into the intramedullary canal 144 as shown in FIG. 13 . Successively larger drill bits 148 are utilized until the marrow has been removed from a portion of the intramedullary canal to be tapped, and proprioceptive or audible indications that solid bone has been engaged are felt or heard. At this point, the intramedullary canal is tapped as shown in FIG. 14 by a handheld tap 150 to produce threads corresponding to the threads and 64 of the intramedullary stem 60 . At this point, the ulna 140 is prepared for installation of the prosthetic joint portion 14 . [0138] An appropriately sized intramedullary stem 60 is paired with an appropriately sized base 72 , as shown in FIG. 15 . Different sized, interchangeable intramedullary stems 16 and bases 72 may be selected depending on the characteristics of the patient. The intramedullary stem 60 is placed within the channel 74 , and the threads 64 are brought into engagement with the threads that were tapped into the intramedullary canal 144 . An appropriate tool, which in the illustrated example is the screwdriver 152 , is inserted into the threaded hole 80 and brought into engagement with the actuator engaging structures 70 within the head 66 of the intramedullary stem 60 . The screwdriver 152 is turned to pull the prosthetic joint portion 114 into the ulna 140 . Because the intramedullary stem 60 is rotatable with respect to the base 72 , the base 72 may remain in a proper orientation as the intramedullary stem 60 is turned, thereby permitting the turning of the intramedullary stem 60 to draw the base 72 tightly into position within the ulna, as shown in FIG. 16 . [0139] Once the prosthetic joint component 14 has been installed within the ulna, a bearing 104 is placed against the interior surface 84 of the base 72 ( FIGS. 4-6 ). The bearing retaining bracket 92 is positioned against the base 72 . The screw 106 is then secured within the threaded hole 80 , thereby securing the bracket 92 and bearing 104 in position within the prosthetic joint component 14 . At this point, the prosthetic joint components 12 , 14 are ready to be joined together. Also, at this time, holes are drilled in the ulna 140 to correspond to the holes 118 in the base 72 . [0140] Regardless of whether hemiarthroplasty or total arthroplasty is being performed, the illustrated example substantially mimics the movement and stability of a natural joint through a system of ligament reconstruction. Joint stability is defined as the resistance to subluxation under physiologic stress and is the result of the mechanical interaction of the articular contours, the dynamic support of the investing musclotendinous units, and the static viscoelastic constraint of the capsuloligatmentous structures. In order to be useful to the patient, the design of the prosthetic joint 10 must preserve this stability. Given that this design aims to replicate the native elbow bony anatomy and does not utilize a mechanical hinge to resist varus and valgus forces, the stability requirements are placed on the soft tissues. [0141] Collateral ligaments are complex structures whose individual fascicles are under differential tension and whose properties depend on joint position and load. The collateral ligaments of the elbow, by virtue of their medial and lateral locations, have a mechanical advantage in resisting medially and laterally directed forces that would cause joint subluxation. In an effort to gain joint visualization during arthroplasty surgery, these ligaments are detached and then re-inserted once the implants have been placed. Reattachment is difficult to do particularly when the ligament integrity is compromised such as in the joints of elderly patients. Patients suffering from post-traumatic arthritis often sustained soft tissue as well as bony trauma making a subsequent collateral ligament repair more tenuous. Therefore, tendons taken from the patient or allograft tendons are utilized as ligament reconstruction members, as described below. [0142] Initially, tendons are selected from the patient for use in reconstructing the ligaments. The specific tendon or tendon portion selected are chosen because its loss will have minimal or no impact on the patient. Tendons that may be advantageously utilized include a longitudinal strip of triceps tendon or the Palmaris Longus tendon. Alternatively, toe extensors or the Plantaris tendon or even half of the Flexor Carpi Radialis tendon can be used. Allograft tendon material may also be utilized. [0143] With the appropriate ligament reconstruction members 154 obtained, the humeral joint portion 12 and ulna (in the case of hemiarthroplasty) or ulnar joint portion 14 (in the case of total arthroplasty) are placed against each other as shown in FIG. 17 . The ulnar articulating surface will be native cartilage if a hemiarthroplasty is being performed, or the bearing 104 if total elbow arthroplasty is being performed. The ligament reconstruction members 154 are utilized to connect the humeral joint portion 12 and ulnar joint portion 14 by securing a portion of the ligament reconstruction members 154 to the humeral portion 12 , and another portion of the ligament reconstruction members 154 to the ulnar portion 14 . In the illustrated example, a central portion 156 of the ligament reconstruction members 154 is passed through the central bore 53 of the spool 46 , as well as the holes 55 , 57 defined within the distal ends 42 , 44 of the legs 30 , 32 of the yoke 28 . The end portions 158 of the ligament reconstruction members 154 are then tensioned in order to remove their viscous properties, and secured to either the ulna (in the case of a hemiarthroplasty) or to the base 72 of the ulnar joint component 14 (in the case of a total arthroplasty) by securing the ends of the ligament reconstruction members 154 underneath the plates 122 , 124 . The plates 122 , 124 in the illustrated example are held in place by the cross locking screws 116 and nuts 120 , so cross locking of the ulnar component is also accomplished during this step. The tendon to bone fixation is, thereby, accomplished through the creation of compressive force exerted between the ulna and the plate. This method will maintain the appropriate tension within the tendons while bone to tendon healing occurs, and thereby ensures the stability of the reconstructed joint. This design also maintains the dynamic support of the extensor and flexor tendon insertions, which is accomplished by leaving the lateral and medial epicondyles intact. [0144] The prosthetic joint described above provides numerous advantages over the prior art. The present design does not include cement fixation at all, and thereby eliminates the risk of bone cement implantation syndrome, as well as the other disadvantages of using bone cement. It is anticipated that, as the bones heal, they will grow into and/or around the various components of the prosthetic joint, thereby enhancing the security with which the prosthetic joint components are attached to the respective bones. Avoiding bone cement removes the exothermic curing process that may damage bone secondary to thermal osteonecrosis. In the event of infection, removal and replacement of prosthetic joint components is greatly simplified. [0145] The attachment of the prosthetic joint components to the respective bones is particularly secure, and is anticipated to be able to withstand forces imparted to the biomechanical construct in excess of those which could be withstood by prior prosthetic joints. The use of relatively long intramedullary stems increases the surface area against which forces are applied, thereby reducing the pressure applied for an equivalent force. A screw that gains purchase in the threaded intra-medullary canal can pull the implant into the bone and create a very stable intra-medullary fixation based construct by distributing the forces over a sizeable number of threads. By leveraging the length of the humerus and ulna as well as the high cortical to cancellous bone ratio within the middle thirds of the humerus and ulna, the proposed method of fixation will make secure un-cemented implant fixation possible in a safe and reproducible manner. By distributing the forces over multiple threads, fixation through the intra-medullary screw is possible and reproducible even in bone that is fragile as is seen in osteoporotic patients. The use of interchangeable intramedullary stems and connection portions makes it possible to provide different length threaded rods that would not over-penetrate the far cortex beyond where it is achieving fixation. The use of cross locking members resists any tendency of the intramedullary stems to loosen over time. [0146] The prior art method of constraining a total elbow arthroplasty resides in either using a hinge device in the implant (constrained) or repairing the ligaments after elbow replacement (unconstrained). No commercially available or previously marketed design attempts to provide stability through reconstruction of the elbow ligaments. Conversely, in the present design, the elbow is stabilized in a manner that most closely approximates how it functions in vivo. Secure ligament reconstruction is particularly advantageous as the patient populations that frequently receives this type of surgery often suffer from inflammatory arthritis and may not have a soft tissue envelope that can be relied on to provide stability when reattached after implantation. The use of autograft or allograft ligament reconstruction members provides a means of accommodating varus/valgus movement by transferring forces to the medial and lateral ligaments of the elbow similar to what is experienced in vivo. [0147] The prosthetic joint described above further provides for simplified surgery. The surgeon need not decide between hemi arthroplasty and total arthroplasty prior to performing the surgery, and can instead make this intraoperative decision. An easily replaced bearing is designed to wear in preference to components that are more difficult to replace. When the bearing wears out, which is anticipated to be a period of years, a relatively simple surgery may be used to replace the bearing. [0148] A variety of modifications to the above-described embodiments will be apparent to those skilled in the art from this disclosure. For example, other methods of attaching ligament reconstruction methods between the respective joint components could be utilized without departing from the scope of the invention. Additionally, other hinge joints, such as knees, fingers, etc., may be repaired using a prosthetic joint described herein. Additionally, a ball and socket joint such as a shoulder or hip would equally benefit from the cementless attachment methods taught herein, as well as variations of ligament reconstruction utilizing tendons from the patient to secure the mating joint components. Thus, the invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The particular embodiments disclosed are meant to be illustrative only and not limiting as to the scope of the invention. The appended claims, rather than to the foregoing specification, should be referenced to indicate the scope of the invention.

A prosthetic joint is secured to the bones forming the original joint by utilizing strictly mechanical fasteners, for example, a threaded rod engaging a tapped intramedullary canal. Cross locking members may be provided. The need for bone cement is avoided. The prosthetic joint may be used to replace one end of one bone forming the joint, utilizing the naturally occurring end of the other bone. Alternatively, both bone ends may be replaced with prosthetic joint portions. The decision to replace one or both bone ends may be made mid-surgery. The prosthetic joint portions are secured together utilizing ligament reconstruction members made from portions of the patient's tendons or allograft tendons. A bearing forming the interface between the two joint portions is designed to wear in order to protect the remaining components from wear, and to be easily replaced in relatively simple future surgeries.

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a display device and a method for controlling the backlight thereof. [0003] 2. Description of the Prior Art [0004] Generally, a display device, especially a liquid crystal display (LCD) apparatus, is provided with a backlight device functioning as a light emitting device to provide images sufficient brightness such that the visibility of the display device can be enhanced under dim lighting conditions. Furthermore, relevant techniques have been developed to control the illuminance of the backlight device based on the ambient lighting condition, thereby the visibility of the LCD apparatus can be improved, allowing devices having LCD apparatus, such as mobile phones, cameras and personal digital assistances (PDAs), to be used under a wide range of lighting conditions. [0005] The Japanese Patent Published No. 2005-24796 discloses a backlight constructed as a multilayer structure. In this case, the backlight is controlled by detecting brightness of surroundings of the liquid crystal display device with a photosensor. [0006] The range of brightness of the detected external light may be quite wide (e.g. in a range from 10 to 10000 lux), thus it is impossible to cover the entire range of light intensity with an output level only. Therefore, the photosensor must switch among a plurality of sensitivity ranges to output the most appropriate signal range so as to obtain the signals. [0007] FIG. 1 is a schematic view showing the structure of a conventional LCD apparatus that utilizes the output of a photosensor to control the backlight thereof according to the prior art. The backlight device 1 is disposed at the bottom of the structure, and the photosensor 11 is disposed on a glass substrate 10 of the LCD panel to generate corresponding light intensity signals based on the detected light intensity. The selection and measurement device for sensitivity range 12 is constructed by four standard switches SW 1 -SW 4 to select the light intensity among the four sensitivity ranges so as to output the most appropriate sensitivity range. In order to select a most appropriate sensitivity range, the switches have to operate to perform the switching among various sensitivity ranges as follows, so as to determine within which sensitivity range the current signal falls. [0008] The control device 20 is configured to access the outputted sensitivity range and to control the illuminance of the backlight based thereon. [0009] When the backlight is turned on, the photosensor will check the light intensity and thus fail to accurately measure the intensity of the external light. In this case, the backlight has to be turned off to accurately measure the external light. [0010] FIG. 2 is a flowchart showing the process of selecting the most appropriate sensitivity range according to the prior art. In such process, four sensitivity ranges of different levels A, B, C and D are used to cover the entire sensitivity range of the external light, so as to determine that the level of the external light falls within which sensitivity range at the time when each image shot (approximately 16 milliseconds) starts to be displayed. [0011] In Step S 1 , the backlight is firstly turned off. As the sensitivity range A is selected, the switch SW 1 is turned on and the data are being accessed. In order to access the data unaffected by the backlight, the backlight must be turned off for a period of time, e.g. 500 microseconds. Then, the process proceeds to Step S 2 where the control device determines whether the accessed data fall within the sensitivity range A. If the determination in Step S 2 is negative, the process proceeds to Step S 3 where the backlight remains off, the switch SW 2 is turned on, and the data are being accessed. After that, the process proceeds to Step S 4 where a determination is made as to whether the accessed data fall within the sensitivity range B. The sensitivity ranges C and D will be selected sequentially and similar steps will be repeated so as to obtain correct data on the sensitivity range (Steps S 5 ˜S 8 ). If the control device determines that the data fall within one of the four sensitivities ranges, correct data will be obtained, and then the backlight will be turned on (Step S 10 ). Meanwhile, if the control device is unable to determine which sensitivity range the data fall within, error data will be obtained, but still the backlight will be turned on (Step S 9 ). The aforementioned steps are repeated after a duration of image phase passes (Step S 11 ). [0012] As the conventional LCD apparatus adopts four sensitivity ranges, the backlight will be turned off for 500×4=2000 microseconds during each image shot until the most appropriate data are obtained. Even if the most appropriate sensitivity range is obtained and the process of determining whether the data fall within the rest of sensitivity ranges stops, the average turn-off period of the backlight still lasts more than 1000 microseconds. [0013] As it takes longer time to determine which sensitivity range the data fall within in the prior art, the backlight needs to be turned off for a long period of time. This results in a decrement in the luminescent efficiency of the backlight and the brightness of the image. SUMMARY OF THE INVENTION [0014] It is an object of the present invention to provide a display device and a method for controlling the backlight thereof. The method is capable of promptly determining within which intensity range the light intensity signal outputted from the selection and measurement device the intensity of the external light falls, so that the turn-off period of the backlight can be reduced to prevent the brightness thereof from decreasing. [0015] According to a first aspect of the present invention, a display device is provided, which includes a display panel; a backlight device disposed under the display panel wherein the illuminance of the backlight device is adjustable; a selection and measurement device for light intensity which is configured to measure the ambient light intensity of the display panel at a prescribed frequency when light intensity signals of a sensitivity range selected from a plurality of prescribed sensitivity ranges are outputted; and a control device determining whether a latest prescribed light intensity signal falls within a upper portion, a lower portion of a remaining portion of one of the plurality of prescribed sensitivity ranges. The control device includes a memory device for sequentially memorizing the light intensity signals; a first average device obtaining a first average value of a first prescribed number of light intensity signals read out from the memory device; a second average device for obtaining a second average value of a second prescribed number of light intensity signals read out from the memory device, wherein the second prescribed number is larger than the first prescribed number; and a calculation and control device. [0016] The calculating is performed with the selection and measurement device and accordingly controlling the illuminance of the backlight device. When the control device determines that all of the first prescribed number of light intensity signals fall within the upper portion and the first average value is greater than the second average value, the calculating is performed based upon the sensitivity range adjacent to said upper portion of said prescribed sensitivity range. When the control device determines that all of the first prescribed number of light intensity signals fall within the lower portion and the first average value is smaller than the second average value, the calculating is performed based upon the sensitivity range adjacent to the lower portion of the sensitivity range. Moreover, the calculating is performed based upon the sensitivity range when the control device determines that all of the first prescribed number of light intensity signals fall within neither the upper portion nor the lower portion. [0017] Furthermore, in accordance with a second aspect of the present invention, a backlight control method for a display device is provided. The method includes steps of measuring the ambient light intensity of a display panel with a prescribed cycle; outputting light intensity signals of a sensitivity range selected from a plurality of prescribed sensitivity ranges; memorizing the light intensity signals sequentially; determining whether a latest light intensity signal falls within a upper portion, a lower portion or a remaining portion of one of the plurality of prescribed sensitivity ranges; obtaining a first average value of a first prescribed number of the memorized light intensity signals; obtaining a second average value of a second prescribed number of the memorized light intensity signals, wherein the second prescribed number is larger than said first prescribed number; and calculating and accordingly controlling the illuminance of a Illuminance-adjustable backlight device disposed under the display panel, wherein when the control device determines that all of the first prescribed number of light intensity signals fall within the upper portion and the first average value is greater than the second average value, the calculating is performed based upon the sensitivity range adjacent to said upper portion of said prescribed sensitivity range. When the control device determines that all of the first prescribed number of light intensity signals fall within the lower portion and the first average value is smaller than the second average value, the calculating is performed based upon the sensitivity range adjacent to the lower portion of the sensitivity range. Moreover, the calculating is performed based upon the sensitivity range when the control device determines that all of the first prescribed number of light intensity signals fall within neither the upper portion nor the lower portion. [0018] The display device of the present invention is capable of controlling the illuminance of the backlight thereof corresponding to the ambient lighting condition and reducing the turn-off period required for measuring the external light, thereby to maintain sufficient brightness and good visibility. BRIEF DESCRIPTION OF THE DRAWINGS [0019] FIG. 1 is a schematic view showing the structure of a conventional LCD apparatus with backlight according to the prior art. [0020] FIG. 2 is a flowchart showing the details of steps of determining the sensitivity range as illustrated in FIG. 1 . [0021] FIG. 3 is a schematic view showing the structure of a display device and the intensity determination steps according to a first embodiment of the present invention. [0022] FIG. 4 is a flowchart showing the details of the intensity determination steps as illustrated in FIG. 3 . [0023] FIG. 5 is a visualized presentation showing the adjustment of the sensitivity range. [0024] FIG. 6 is a schematic view showing the structure of a display device and the intensity determination steps according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0025] The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. It is to be noted that this invention may, however, be embodied in many different forms and should not be construed as limitations to the embodiments set forth herein. [0026] FIG. 3 is a schematic view showing the structure of a display device and the intensity determination steps according to a first embodiment of the present invention. In this embodiment, the display device is an LCD apparatus with backlight. The components the same as those illustrated in FIG. 1 are provided with the same reference numerals and are not repeated for clarity. [0027] The LCD panels illustrated on the left side of FIGS. 1 and 3 are exactly the same, while the control devices 20 and 30 , which are illustrated on the right side of FIGS. 1 and 3 respectively, are completely different in structure. [0028] The light intensity signals from the photosensor 11 , such as a photoelectric switch, are firstly sent to the control device 30 and then stored in a first-in-first-out (FIFO) memory 31 . In some embodiment, the FIFO memory 31 can memorize approximately 100 data entries. [0029] The three latest data entries memorized in the FIFO memory 31 are sent to a first average calculating unit 32 to produce an average data (short-time average value), and meanwhile the 60 latest data entries memorized in the FIFO memory 31 are sent to a second average calculating unit 33 to produce an average data (long-time average value). [0030] The calculation and control device 34 will execute the steps of the flowchart illustrated in FIG. 4 . [0031] In Step S 101 , the backlight is turned off when an image starts to be displayed, and the light intensity signals associated with a particular sensitivity range are being accessed. For example, FIG. 3 shows four sensitivity ranges A, B, C and D among which the lower sensitivity range B may be selected as the initial condition. It is to be noted that any one of the four sensitivity ranges may be selected at the initial stage. [0032] Then, the process proceeds to Step S 102 where the calculation and control device 34 determines whether the inputted light intensity data fall within the selected sensitivity range. [0033] The backlight will be turned on (Steps S 103 and S 104 ) and remain on throughout the successive steps no matter the inputted data are identified as error data (Step S 103 ) or correct data (Step S 104 ). [0034] Then, the current data, the data prior to an image (previous data 1 ) and the data prior to two images (previous data 2 ) will be examined to determine whether the three data entries fall within the upper portion, the middle portion or the lower portion of the sensitivity range. In this embodiment, the upper portion accounts for one fourth of the sensitivity range, so does the lower portion. [0035] In Step S 105 , a determination is made as to whether the three data entries are less than one fourth of the sensitivity range, i.e. fall within the lower portion of the sensitivity range. [0036] If the determination in Step S 105 is negative, the process proceeds to Step S 106 where a determination is made as to whether the three data entries are larger than three fourth of the sensitivity range, i.e. fall within the top portion. [0037] If the three data entries do not fall within either the top portion or the lower portion, they will be deemed as falling within the middle portion of the sensitivity range and kept within the sensitivity range (Step S 107 ). [0038] If the determination in Step S 105 is affirmative, the process proceeds to Step S 108 where a determination is made as to whether the short-time average value produced by the first average calculating unit 32 is smaller than the long-time average value produced by the second average calculating unit 33 . If the determination in Step S 108 is affirmative, which indicates the value of the current data tends to decrease, the process proceeds to Step S 109 where a lower sensitivity range is selected. [0039] If the determination in Step S 106 is affirmative, the process proceeds to Step S 110 where a determination is made as to whether the short-time average value produced by the first average calculating unit 32 is greater than the long-time average value produced by the second average calculating unit 33 . If the determination in Step S 110 is affirmative, which indicates the value of the current data tends to increase, the process proceeds to Step S 111 where a higher sensitivity range is selected. The switch SW 12 will then be turned on based on the command issued by the calculation control device 34 illustrated in FIG. 3 . [0040] If the determinations in Steps S 108 and S 110 are both negative, the sensitivity range remains unchanged. [0041] FIG. 5 is a visualized presentation showing the adjustment of the sensitivity range. Referring to FIG. 5 a , there are four sensitivity ranges A, B, C and D. For example, the light intensity is measured three times in a cycle of 16 milliseconds to generate three measured values D 1 , D 2 and D 3 . If the sensitivity range B is selected and all of the three measured values D 1 , D 2 and D 3 fall within the top one fourth of the sensitivity range B, it fulfills the conditions that the determinations in Steps S 106 and S 110 are both affirmative. Consequently, a higher sensitivity range (the sensitivity range C) is selected. [0042] Referring to FIG. 5 b , all of the three measured values D 1 , D 2 and D 3 fall within the bottom one fourth of the sensitivity range B, thus it fulfills the conditions that the determinations in Steps S 105 and S 108 are both affirmative. Consequently, a lower sensitivity range (the sensitivity range A) is selected. [0043] When the sensitivity range of the external light is obtained, the calculation and control device 34 can easily adjust the illuminance of the backlight device correspondingly. [0044] All the aforementioned steps are executed during an image phase (16 milliseconds). When the backlight is turned off for 500 microseconds, an appropriate sensitivity range can be selected so as to have the backlight provide sufficient illuminance. [0045] FIG. 6 is a schematic view showing the structure of a display device and the intensity determination steps according to the second embodiment of the present invention. The only difference between FIGS. 3 and 6 is that the display device illustrated in FIG. 6 adopts four different photosensors 11 A˜ 11 D instead of the photosensor that switches among four sensitivity ranges and the switch among the switches SW 21 -SW 24 is performed based on the command issued by the calculation and control device 34 thereby to select the sensitivity range. [0046] The remaining steps shown in FIG. 6 are the same as those illustrated in FIGS. 3-5 , and hence are not repeatedly illustrated. In this embodiment, a more appropriate photosensor can be selected corresponding to the sensitivity range, thus the intensity of the external light can be more accurately measured and the illuminance of the backlight device can be properly controlled. [0047] In the aforementioned embodiments, the respective proportions of the upper and lower portions that serve as determination bases can be appropriately defined when the sensitivity range is altered. Though either of the upper portion and the lower portion accounts for 25% of the sensitivity ranges in the aforementioned embodiments, an equivalent proportion of 33% or a proportion less than 25% can be adopted as well. In addition, though the middle portion, which means the sensitivity range remains unchanged, is the largest among the three portions, it can be set to be narrower than the upper portion or the lower portion. [0048] The number of data entries used to calculate the average value is not limited to three as described in the aforementioned embodiments. The average value can be calculated using any number of data entries more than two so as to determine the sensitivity range. [0049] In addition, the number of data entries used to calculate the short-time and long-time average values can be appropriately selected as well. As the short-time average value stands for the current distribution tendency and the long-time average value indicates the distribution tendency for a longer period of time, the number of data entries used to calculate the long-time average value can be ten times that of data entries used to calculate the short-time average value when the denominator is the long-time average value, thereby to calculate the average value. [0050] The control device introduced in the embodiments can be assembled through hardware, which is generally a programmable integrated circuit. [0051] Though an LCD apparatus with backlight is described in the embodiments, the present invention is applicable to a variety of display devices with backlight.

A display device having backlight and the backlight control method thereof is provided. Through the provided method, it is capable of fast determining which intensity range the intensity signal from the means for measuring the intensity of external light falls in, so that the turn-off period of backlight is reduced to avoid the decrement of brightness.

BACKGROUND OF THE INVENTION The present invention relates to a test method for screwers and to devices applying this method. Powered screwers (of the electromechanical, pneumatic and other types) must give a precise torque wrench setting in use. Therefore, availability of test devices is required which enable periodical checking of the torque wrench setting expressed by a screwer, so as to be able to establish whether adjustment, repair or replacement of those screwers that are no longer in conformity with specifications is required. Precise standards exist giving regulations for measurement of screwer performances. For example, standard ISO 5393-81 describes a test method for evaluating pneumatic screwer performances and provides instructions on the statistical evaluation of measurements. Obviously, since in normal use a screwer torque increases during rotation, any test for torque performances in a screwer must be conducted using simulators having a controlled torque gradient, so as to simulate the actual screwing down of a screw and enable the torque supplied by the screwer under a significant condition to be measured. For example, standard ISO 5393 presently requires that the tool should be tested under two limit conditions, in which the torque increase of 50% to 100% of the rated torque develops through a rotation of 360° and 30° respectively. In these value ranges (that in any case can be subjected to variations), standards ISO impose that the torque opposed by the simulator should increase according to a substantially linear law relative to rotation. Simulators of the simplest conception are mere mechanical joint simulators. However, since the screwer calibration can be set to a variety of values, theoretically a variety of simulators should be provided or the simulator features should be susceptible of variation, which is generally rather complicated: therefore, mechanical simulators apply to the cases in which averaged out conditions are acceptable, but they do not exactly reflect features required by standards. In addition, the use of mechanical joint simulators has the drawback of requiring the screw to be unscrewed after each calibration so that a new test may be carried out. In order to obviate the above drawbacks, as described in DE 33 05 457, test systems have been accomplished that use electromagnetic brakes of different types to simulate the torque-angle relationships required by standard ISO, by means of a modulation of the feed current to the brake coil. The main defect in these systems is due to the fact that braking takes place by friction elements that, owing to their own nature, undergo feature variations as a result of heating and wear of the friction surfaces. Therefore a constant reliability overtime cannot be ensured. In order to obviate the above inconvenience, the use of braking devices that do not operate by friction has been also mentioned, such as in the case in which current generators driven in rotation by the screwer are employed, which generators generally do not have appropriate electromechanical features. In any case, there is a defect which is common to all the above devices, both those provided with traditional brakes and those involving current generators, i.e. the high moment of inertia of the braking unit which can be too high for quick screwers when calibrated to a low torque. In this case, the test cannot be carried out in that the static torque for driving the system in rotation exceeds the maximum torque for which the screwer is calibrated, so that the latter disconnects. The general object of the present invention is to eliminate the above mentioned drawbacks by providing a test method and devices for screwers enabling specifications of the international standards to be accurately followed and constant results to be achieved even when screwers having particular features of low torque and/or high speed are concerned. SUMMARY OF THE INVENTION In view of the above object, in accordance with the invention, a test method for a screwer has been devised which comprises the steps of connecting the screwer to a rotatable attachment element, screwing down the screwer, measuring the attachment element speed, power-supplying an electric motor to bring it to a speed close to said measured speed, connecting the shaft of the electric motor to the attachment element, causing the motor to follow a braking ramp while the torque transmitted from the screwer to the driving shaft is measured. To apply the above method, a test device for a screwer has been also conceived which comprises a rotatable attachment element to which the screwer to be tested is applied, a braking element connected to the attachment element for its controlled braking according to a predetermined law and torque measuring means connected for measurement of the transmitted torque between the attachment element and braking element, characterized in that the braking element is an electric motor connected to the attachment element by releasable coupling means connecting the motor to the attachment element upon achieving a motor speed close to that of the attachment element. BRIEF DESCRIPTION OF THE DRAWINGS For better explaining the innovative principles of the present invention and the advantages it offers as compared to the known art, possible embodiments applying these principles will be described hereinafter by way of non-limiting example, with reference to the accompanying drawings, in which: FIG. 1 is a diagrammatic view partly in section of a first embodiment of a test device in accordance with the invention; FIG. 2 is a view, similar to that shown in FIG. 1, of a second embodiment applying the inventive principles. DETAILED DESCRIPTION OF THE INVENTION With reference to the drawings, shown in FIG. 1 is a test device, generally identified by 10, comprising a rotatable attachment element 11 jutting out of the plane 12 of a test bed the remaining part of which is not shown. The attachment element 11 is intended for coupling with the head of a screwer 13 to be tested and therefore will have a known shape adapted to the particular screwer. For instance, in the drawings the attachment element 11 is shown as a square male clutch, but it can take any other, male or female, polygonal or different shape. The attachment element may be detachable from a chuck 14, so that it can be easily replaced. Below the bed plane, the attachment element 11 is connected by measurement means 15 and drive clutch means 20, to an electric motor 16 which can be an asynchronous motor for example, advantageously a motor of the so-called brushless type. The measurement means 15 comprises a known rotating torque transducer 17, for measurement of the torque transmitted between the motor 16 and attachment element 11 (and consequently the screwer) and an encoder 18 for measurement of the angular rotation of the attachment element and its rotation speed. Encoder 18 can be a separate element connected to, as shown in the figure through belts and pulleys 19, or integrated into, the torque transducer. The clutch means 20, disposed between the measurement unit comprising the encoder and motor, is of known type which is operable for drivingly connecting and disconnecting the driving shaft to and from the attachment element 11 in the form of the clutch 11. For example, use of a known electromagnetic clutch provided with teeth, a so-called claw clutch 21 has been found advantageous, so as to have a reduced moment of inertia, for example relative to a friction clutch of same transmissible torque. The possibility of using a claw clutch arises from the particular operation of the test device in accordance with the invention, as described in the following. An electronic control system 23, a computerized system for example, substantially belonging to the known art, receives signals from the torque sensor, the encoder and a speed sensor or resolver 24 of motor 16, and outputs drive signals for the clutch device 20 and, through a known appropriate power device 25, for motor 16, as better described later. The device 23 may comprise a display screen and a keyboard to display information about the test course and receive commands from the operator. In use, first the clutch means 20 is uncoupled and motor 16 is therefore disconnected from the attachment element 11. The operator fits a screwer to be tested into the attachment element 11 and starts it. The mass in rotation connected to the attachment element 11 is at present very low and to such an extent that it produces a static torque lower than the torque for which the screwer is adjusted. The screwer substantially rotates freely and therefore at full speed. The encoder 18 measures the rotation speed of the screwer and transmits the information to the control system 23 that, in turn, starts rotation of motor 16 until it brings it to a speed close to the screwer's (with a difference not exceeding 5% for example) and in any case to such a speed that the screwer does not exceed the torque for which it is set, when it is connected to the motor. Advantageously, the motor speed (measured by sensor 24) can be brought to be the same as the screwer speed, so that the claw clutch can be operated without slippage to make the motor and screwer integral with each other through the torque transducer 17. At this point the system powers the motor to supply a predetermined braking ramp, in order to follow the already mentioned test standards for screwers, for example. As is obvious for a person skilled in the art, the braking ramp can be easily accomplished so as to produce a linear relationship between the generated torque and angular rotation of the screwer head, as prescribed by standards ISO. For this purpose, the braking ramp can be practically expressed as torque-time. To do this, it is necessary to carry out a first identification test of the torque-time feature for the particular screwer. During this step, the encoder 18 is used to measure the torque-angle ratio corresponding to a given set time so that a braking adjusted against time and taking place at the desired angle can then be obtained. The system 23 will store the obtained curve, associating it with the particular screwer. After that, it is possible to carry out the true test as described above, both immediately and after a period of time, on which occasion the system will provide the motor with a characteristic braking curve based on the torque-time ratio of the particular screwer and capable of maintaining the torque-angle ratio linear. In other words, the braking ramp is carried out with a torque gradient controlled in time, based on previously established parameters during mapping of the screwer features, that have been stored in the system and are used for that specific screwer. During the braking test step measurement of torque against angle takes place instant by instant so as to detect the predetermined characteristic curve. In the case of tests spaced in time the system will be therefore capable of determining whether the characteristic torque-time curve of that screwer has undergone variations relative to the desired torque-angle curve and, should not the braking angle be the desired one, it will automatically vary the ramp against time in order to restore the desired conditions. At the end of the test the system will then be able to signal the screwer correspondence to the starting specifications. The braking ramp can also be expressed in torque-angle, the starting test being eliminated while the test is directly executed with the torque sensor and encoder supplying feedback for drive of the motor braking in order to keep the relationship between torque and rotation angle linear, thereby applying the test method provided in standards ISO5393 to the letter. Either in the case of the braking ramp expressed in torque-time, or in the case of a braking ramp expressed in torque-angle, the test result is in any case in conformity is with the prescribed regulations. At the end of the test, the clutch 20 disconnects the motor from the screwer and the system is ready for the next test. Obviously, the control system can process the test outcome or the outcome of several tests, and supply statistical results, graphs, etc., as a person skilled in the art can easily conceive. In the use of an electric motor as the braking element a practical problem may arise. Actually, rotation of the motor used as a brake can become unstable close to a zero speed. In other words, the motor could tend to oscillate about the zero speed, continuously reverting its running until it is completely stationary. The torque-time (or torque-angle) graph therefore should no longer be linear close to the stop point (i.e. the point of maximum torque). In order to solve the above problem in a simple manner, advantageously inserted between the motor and clutch 21 is a freewheel device 22 enabling rotation of the driving shaft only in one direction (the direction concordant with the normal screwer rotation) and acting as a non-return device in the opposite rotation direction. Thus it is possible to supply a braking ramp having a torque greatly higher than that supplied by the screwer, thereby obtaining a linear course until stopping. The torque surplus exceeding that required for stopping the screwer is absorbed by the freewheel, which prevents the motor rotation in the opposite direction due to the torque surplus. The freewheel also has an accident-prevention function, avoiding the reverse rotation of the motor and therefore preventing the motor from driving the whole screwer in the contrary direction. For explaining the principles of the invention in a still clearer manner, a second embodiment of a test device applying these principles will be now described with reference to FIG. 2. Elements similar to those of the embodiment in FIG. 1 in terms of structure or function will be hereinafter denoted by same reference numerals used in FIG. 1 increased by one hundred. Therefore, there is a test device generally denoted by 110, comprising a clutch attachment element 111 jutting out of the plane 112 of a test bed and adapted for engagement with the head of a screwer to be tested. The attachment element is detachable from a chuck 114 so that it can be replaced with ease. Below the bed plane, the attachment element 111 is connected, through measurement means 115 and clutch means 120 disposed in series, to an electric motor 116 that can be an asynchronous motor for example, advantageously a motor of the so-called brushless type. The measurement means 115 comprises a known rotating torque transducer 117 for measurement of the torque transmitted between the motor 116 and the attachment element 111 and an encoder 118 connected to the attachment element through a drive 119, for measurement of the angular rotation and rotation speed of the attachment element. Alternatively, the encoder can be integrated into a torque meter. Unlike the embodiment in FIG. 1, the clutch means 120 consists of a mere freewheel device 121, of a size adapted to transmit the maximum required torque, keyed onto the motor shaft to disconnect it from the attachment element 111 when the rotation speed of the motor is higher than the clutch speed. An electronic control system 123, a computerized system for example, substantially belonging to the known art, receives signals from the torque sensor, the encoder and a speed sensor or resolver 124 of motor 116 and, through an appropriate known power device 125, operates motor 116 as explained in the following. The device 123 may comprise a display screen and a keyboard to display information about the test course and receive commands from the operator. Also present on the motor shaft is a second freewheel 122 connecting the motor shaft to the device framework to provide the same effects as described for the freewheel 22. During operation of the device, motor 116 is first set in rotation at a higher speed than that of the maximum speed of the screwer to be tested (typically 2000 revolutions per minute). For example, a single speed higher than the fastest screwer that is likely to be tested may be selected. Under these conditions, the attachment element 111 does not rotate by virtue of the action of the freewheel 121. At this point, the screwer can be connected to the attachment element 111 and operated. The freewheel is still uncoupled because the idling speed of the screwer is surely lower than that of motor 116. The encoder 118 measures the rotation speed of the screwer and transmits the information to system 123 which, in turn, carries out decreasing of the rotation speed of motor 116 until a speed slightly higher than the screwer's (not exceeding the screwer speed by no more than 3-5%, for example) is reached Once this condition has been achieved, the system powers the motor so that it can have a braking ramp as already described in the preceding embodiment. During braking the freewheel 121 follows a rotation direction contrary to the starting direction, so that it makes the motor 116 and clutch 111 integral with each other through the torque transducer 117. At the end of the test cycle the motor rotates again to the starting high speed, releasing the freewheel 121 and thus making the device ready for the subsequent test. By virtue of the use of a freewheel, instead of a controlled clutch as in the previous embodiment, the moment of inertia weighing on the attachment element 111 before fitting of the clutch means 120 is further reduced. The second embodiment can be therefore advantageously employed for testing screwers at low torque and high number of revolutions (typically in the range of 0.5-10 Nm with a speed higher than 1500 revolutions/minute). At this point it is apparent that the intended purposes have been achieved. By the described method of starting in advance a motor adapted for a controlled braking action, to bring it to a speed close to the idling speed of the screwer, and only subsequently fitting the screwer thereon, tests on screwers with which a surplus moment of inertia could prevent starting in rotation of the screwer is also possible without any problem. It is to note that braking takes place without mechanical friction and therefore without wear, therefore ensuring a prolonged duration of its useful lifetime, in addition to measurement accuracy and repeatability. Obviously, the above description of embodiments applying the innovative principles of the present invention is given by way of example only and must not be considered as a limitation of the scope of the invention rights as herein claimed. For instance, the exact mechanical structure and sizes of the different elements of the test device will vary depending on the practical specific requirements. The clutch means between the motor and screwer can be made differently from those shown and be operated electrically, pneumatically, etc. The rotation speed meter of the attachment element can be different from an encoder having a suitably processed signal. The angle sensor and speed sensor can also be two separate devices, as is obvious to a technician. In addition, the torque transducer too can be made by adopting other known means and be differently positioned.

A test method for a screwer performs the steps of connecting the screwer to a rotatable attachment element, screwing down the screwer, measuring the attachment element speed, power-supplying an electric motor to bring it to a speed close to the measured speed, connecting the shaft of the electric motor to the attachment element, and causing the motor to follow a braking ramp while the torque transmitted from the screwer to the driving shaft is measured. A device in accordance with this method includes a rotatable attachment element to which the screwer to be tested is applied, and an electric motor connected to the attachment element through a releasable coupling connecting the motor to the attachment element on achievement of a motor speed close to that of the attachment element. The motor is controlled for following a braking ramp based on a predetermined law, while a transducer measures the transmitted torque between the attachment element and braking element.

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation of U.S. application Ser. No. 10/497,697, filed Jun. 4, 2004, which is a national phase application based on PCT/EP02/13447, filed Nov. 28, 2002, and claims the priority of International Application No. PCT/IB01/02326, filed Dec. 6, 2001, and European Patent Application No. 02003650.5, filed Feb. 18, 2002, all of which are herein incorporated by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to an optical fiber comprising at least one epoxidized polyolefin based coating layer, and to a crosslinkable composition which can be applied as said coating. [0004] More particularly, the present invention relates to an optical fiber comprising at least one epoxidized polyolefin based primary coating layer and at least one secondary coating layer deposited around said primary coating, and to a crosslinkable composition which can be applied as said primary coating. [0005] 2. Description of the Related Art [0006] Optical fibers commonly consist of a glass portion (typically with a diameter of about 125 μm), inside which the transmitted optical signal is confined, and of a coating, typically polymeric, arranged around the glass portion for substantially protective purposes. This protective coating typically comprises a first coating layer positioned directly onto the glass surface, known as the “primary coating” or “primary” for short, typically having a thickness of between about 25 μm and about 35 μm. In turn, this primary coating is generally covered with a second coating layer, known as the “secondary coating” or “secondary” for short, typically having a thickness of between about 10 μm and about 30 μm. [0007] These polymer coatings may be obtained from compositions comprising oligomers and monomers that are generally crosslinked by means of UV irradiation in the presence of a suitable photo-initiator. The two coatings described above differ, inter alia, in terms of the modulus of elasticity of the crosslinked material. As a matter of fact, whereas the material which forms the primary coating is a relatively soft material, with a relatively low modulus of elasticity at room temperature, the material which forms the secondary coating is relatively harder, having higher modulus of elasticity values at room temperature. The combination of said two layers of coating ensures adequate mechanical protection for the optical fiber. [0008] The optical fiber thus composed usually has a total diameter of about 250 μm. However, for particular applications, this total diameter may also be smaller; in this case, a coating of reduced thickness is generally applied. [0009] The crosslinking of the abovementioned compositions, depending on the reactive groups present in the compounds (oligomers and monomers) to be crosslinked, may take place, for example, via a free-radical or cationic route. Typically, the crosslinking of compounds comprising epoxide groups takes place cationically. [0010] For example, patent application EP 124 057 describes a cationically crosslinkable liquid composition comprising a polyepoxide, a polysiloxane bearing a plurality of hydroxyalkyl groups in the molecule, and a photo-initiator and/or a photo-sensitizer. According to the assertions made in the application, said composition is capable of providing a coating for optical fibers that is capable of maintaining low modulus of elasticity values at low temperatures (−60° C.) so as to avoid the phenomenon known as “microbending”, with consequent attenuation of the transmitted signal. [0011] Patent application EP 533 397 describes an optical fiber with a coating which includes at least one layer comprising a cationically crosslinkable composition. Said composition comprises a resin containing cationically crosslinkable end groups, a diluent containing cationically crosslinkable end groups, and a photo-initiator. Resins that are useful for this purpose may be selected from vinyl ether resins and epoxy resins. According to the assertions made in the application, said cationic crosslinking leads to the formation of an acid medium in contact with the glass portion of the optical fiber, making it possible to obtain an optical fiber with improved mechanical strength. [0012] Patent U.S. Pat. No. 6,042,943 describes a radiation-crosslinkable composition which may be used as primary coating for an optical fiber, comprising: (a) a compound comprising (i) a saturated aliphatic chain, and (ii) at least one epoxide group at one end and at least one reactive function, which may be selected from acrylates, vinyl ethers, hydroxyls, or combinations thereof, at the other end; (b) a blend of acrylate-type monomers comprising (iii) a first monomer containing an acrylate group, and (iv) a second monomer containing at least two acrylate groups; and (c) a photo-initiator. According to a further embodiment, (b) is a blend of monomers comprising (iii) a first monomer containing an acrylate group or a vinyl ether group, and (iv) a second monomer containing at least two functional groups which may be selected from acrylates, epoxides, vinyl ethers and hydroxyls. According to a further embodiment, (b) is a blend of monomers of vinyl ether type comprising (iii) a first monomer containing a vinyl ether group, and (iv) a second monomer containing at least two vinyl ether groups. According to a further embodiment, (b) is a monoacrylate residue containing from 6 to 20 carbon atoms. [0013] Patent U.S. Pat. No. 5,993,965 describes a fiber with a coating based on a hydrophobic material derived from the photo-polymerization of a composition comprising at least one epoxidized polydiene oligomer, at least one photo-initiator and, optionally, a reactive diluent of monomeric type. According to the assertions made in the patent, the fibers thus coated are said to have improved mechanical behaviour. In particular, said coating is used in optical fibers. [0014] As observed by the Applicant, the use of reactive diluents of monomeric type, that are generally required to obtain compositions whose viscosity allows them to be applied to optical fibers at room temperature, may present some drawbacks. For example, the relatively low molecular weight of these monomer components is connected with a relatively high volatility, with a consequent contamination of other materials and/or risks to the environment and to the health of the workers. In addition, following the crosslinking by UV irradiation, residues of unreacted components may remain in the final resin. The presence of these unreacted monomer residues within the polymer network may result in unwanted phenomena of extraction by water and/or waterblocking fillers commonly used in optical cables to prevent or limit the entry of water into the structure of the cable. This extraction entails a worsening in the mechanical properties and may also result in the initiation of the phenomenon of delamination of the fiber, i.e. detachment of the polymer coating from the glass portion of the fiber, with possible generation of the phenomenon known as “microbending”. SUMMARY OF THE INVENTION [0015] The Applicant has now found that the use of a hydrogenated polydiene oligomer comprising at least one reactive function, preferably at least one reactive end function, makes it possible to obtain compositions with an acceptable viscosity at room temperature, with little or no use of conventional diluent monomers. The use of a composition according to the invention makes it possible to obtain a polymer coating for an optical fiber, in particular a primary coating, with improved properties such as, for example, relatively low modulus of elasticity values at the normal working temperatures of said fiber, in particular at low temperatures. Said compositions show reduced toxicity by virtue of the lower volatility of the components and, thus, fewer risks not only as regards the contamination of other materials, but also as regards the environment and the health of the workers. In addition, said compositions show improved behaviour both in the presence of water and in the presence of waterblocking fillers. [0016] The Applicant has also observed that, while conventional polymer coatings are applied at room temperature, the use of the abovementioned oligomer instead of the abovementioned reactive diluents of the monomeric type makes it possible to work at higher application temperatures. The possibility of working at higher temperatures without the risk of volatilization of the low molecular weight components makes it possible also to use compositions that, at room temperature, have a viscosity that is higher than those normally used, to increase the crosslinking rate and to avoid a further crosslinking treatment (“post-curing”) of the already-coated optical fiber. Higher application temperatures allows also to avoid cooling the fiber at room temperature before the application of the coating. [0017] In particular, the abovementioned oligomer is advantageously used as a blend with an epoxidized polydiene oligomer comprising at least one hydrocarbon chain that is substantially free of ethylenic double bonds. [0018] According to a first aspect, the present invention thus relates to an optical fiber comprising at least one epoxidized polyolefin based polymer coating, characterized in that said coating is formed from a crosslinkable composition comprising: (a) at least one epoxidized polydiene oligomer having a first and a second end, said oligomer comprising at least one hydrocarbon chain that is substantially free of ethylenic double bonds, at least one epoxide group at said first end and at least one reactive functional group at said second end; (b) at least one hydrogenated polydiene oligomer comprising at least one reactive functional group capable of reacting with said epoxide groups; (c) at least one photo-initiator. [0022] According to a preferred embodiment of the present invention, said composition optionally comprises at least one adhesion promoter (d). [0023] According to a further preferred embodiment, said polymer coating is a primary coating, preferably coated with a secondary coating. [0024] According to a further aspect, the present invention relates to a crosslinkable composition comprising: (a) at least one epoxidized polydiene oligomer having a first and a second end, said oligomer comprising at least one hydrocarbon chain that is substantially free of ethylenic double bonds, at least one epoxide group at said first end and at least one reactive functional group at said second end; (b) at least one hydrogenated polydiene oligomer comprising at least one reactive functional group capable of reacting with said epoxide groups; (c) at least one photo-initiator. [0028] According to a preferred embodiment of the present invention, said composition optionally comprises at least one adhesion promoter (d). [0029] According to a further embodiment of the present invention, said composition optionally comprises at least one reactive diluent monomer (e). [0030] According to a preferred embodiment, said crosslinkable composition has a modulus of elasticity, at room temperature, of less than about 4 MPa, preferably between 1 MPa and 3 MPa. [0031] According to a further preferred embodiment, said crosslinkable composition has a modulus of elasticity, at −40° C., of between 5 MPa and 350 MPa, preferably between 10 MPa and 50 MPa. [0032] Said modulus of elasticity is measured using DMTA apparatus (Dynamic Mechanical Thermal Analyser from Reometrics Inc.), in traction, at a frequency of 1 Hz and at a heating rate of 2° C./min.: further details regarding the analysis method will be described in the examples given hereinbelow. [0033] According to a further aspect, the present invention relates to a method for applying an epoxidized polyolefin based polymer coating to an optical fiber, which comprises: drawing a glass preform placed in a suitable furnace; cooling the fiber leaving the furnace; applying said coating; crosslinking said coating; characterized in that the application of said coating layer is carried out at a temperature of not less than 60° C., preferably between 80° C. and 120° C. [0038] Preferably, the abovementioned coating is formed from a crosslinkable composition comprising: (a) at least one epoxidized polydiene oligomer having a first and a second end, said oligomer comprising at least one hydrocarbon chain that is substantially free of ethylenic double bonds, at least one epoxide group at said first end and at least one reactive functional group at said second end; (b) at least one hydrogenated polydiene oligomer comprising at least one reactive functional group capable of reacting with said epoxide groups; (c) at least one photo-initiator. [0042] Generally, said epoxidized polydiene oligomer (a) (referred to hereinbelow for simplicity as “epoxidized compound (a)”) is, at room temperature, in the form of a viscous liquid. [0043] The epoxidized compound (a) is generally prepared by anionic (co)polymerization of conjugated diene monomers to give a polydiene according to known techniques as described, for example, in patents U.S. Pat. No. 5,247,026, U.S. Pat. No. 5,536,772, U.S. Pat. No. 5,264,480, U.S. Pat. No. 6,042,943 and patent application EP 516 203. [0044] For example, said (co)polymerization may be carried out in bulk, in solution or in emulsion. In general, in the solution (co)polymerization, an initiator selected, for example, from metals belonging to group IA of the Periodic Table of the Elements, or alkyl, amide, silanol, naphthyl, biphenyl, anthracenyl derivatives thereof, is used, and the polydiene is obtained by (co)polymerizing, simultaneously or sequentially, the conjugated diene monomers. The (co)polymerization reaction is generally carried out at a temperature of between about −150° C. and about 300° C., preferably between 0° C. and 100° C., in a suitable solvent. Preferably, the (co)polymerization initiator is selected from organic compounds of alkali metals such as, for example, organolithium compounds represented by the following general formula: RLi n in which R represents an aliphatic, cycloaliphatic or aromatic hydrocarbon, said aromatic hydrocarbon optionally being substituted with alkyl groups containing from 1 to 20 carbon atoms, and n is an integer between 1 and 4. The polydiene thus obtained may be functionalized by reacting the residual organometallic groups derived from said initiator by reaction with suitable terminating agents such as, for example, low molecular weight alkylene oxides in the presence of small amounts of aliphatic tertiary amines such as, for example, N,N,N 1 ,N 1 -tetramethylene-ethylenediamine. [0045] The polydiene thus obtained is then hydrogenated and epoxidized according to known techniques as described, for example, in patent U.S. Pat. No. 4,879,349. The process described in said patent involves the (co)polymerization of substituted or unsubstituted conjugated dienes and the subsequent hydrogenation of the copolymer, working under conditions such that the unsubstituted ethylenic unsaturations present in the copolymer are selectively hydrogenated, while the substituted ethylenic unsaturations present in said copolymer remain substantially non-hydrogenated. The partially hydrogenated polydiene thus obtained is subsequently epoxidized according to known techniques, for example by reaction with an organic peracid (for example peracetic acid or perbenzoic acid). [0046] The hydrogenation and the epoxidation may be carried out in any order. Preferably, the polydiene is first hydrogenated and then epoxidized. [0047] According to a preferred embodiment, the epoxidized compound (a) is obtained by anionic (co)polymerization of conjugated diene monomers containing from 4 to 24, preferably from 4 to 12 carbon atoms selected, for example, from: isoprene, 1,3-butadiene, 2-ethyl-1,3-butadiene, 2-butyl-1,3-butadiene, 2-pentyl-1,3-butadiene, 2-hexyl-1,3-butadiene, 2-heptyl-1,3-butadiene, 2-octyl-1,3-butadiene, 2-nonyl-1,3-butadiene, 2-decyl-1,3-butadiene, 2-dodecyl-1,3-butadiene, 2-tetradecyl-1,3-butadiene, 2-hexadecyl-1,3-butadiene, 2-isoamyl-1,3-butadiene, 2-phenyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 2-methyl-1,3-hexadiene, 2-methyl-1,3-heptadiene, 2-methyl-1,3-octadiene, 2-methyl-6-methylene-2,7-octadiene, and mixtures thereof. Disubstituted conjugated diene monomers such as, for example, 2,3-dimethyl-1,3-butadiene, 2,3-dimethyl-1,3-pentadiene, 2,3-dimethyl-1,3-hexadiene, 2,3-dimethyl-1,3-heptadiene, 2,3-dimethyl-1,3-octadiene, or mixtures thereof, may also be used. Alternatively, difluorinated conjugated diene monomers such as, for example, 2,3-difluoro-1,3-butadiene, 2,3-difluoro-1,3-pentadiene, 2,3-difluoro-1,3-hexadiene, 2,3-difluoro-1,3-octadiene, or mixtures thereof, may be used. 1,3-butadiene and isoprene are preferred. [0048] The conjugated diene monomers may optionally be copolymerized with other ethylenically unsaturated monomers such as, for example: α-olefins containing from 2 to 12 carbon atoms (for example ethylene, propylene, 1-butene), monovinylarenes containing from 8 to 20 carbon atoms (for example styrene, 1-vinylnaphthalene, 3-methylstyrene), vinyl esters, in which the ester group contains from 2 to 8 carbon atoms (for example vinyl acetate, vinyl propionate, vinyl butanoate), alkyl acrylates and alkyl methacrylates in which the alkyl contains from 1 to 8 carbon atoms (for example ethyl acrylate, methyl acrylate, t-butyl acrylate, n-butyl acrylate), acrylonitrile, or mixtures thereof. [0049] Preferably, the epoxidized compound (a) is prepared by sequential anionic (co)polymerization working as follows: (a) anionic polymerization of a first conjugated diene monomer, in particular isoprene; (b) anionic copolymerization of the polymer obtained in stage (a) with a second conjugated diene monomer, in particular 1,3-butadiene, thus obtaining a block copolymer; (c) functionalization of the block copolymer obtained in stage (b) with a suitable terminating agent, in particular ethylene oxide; (d) subsequent selective hydrogenation and epoxidation of the functionalized block copolymer obtained in stage (c). [0054] According to a preferred embodiment, the epoxidized compound (a) is a diblock copolymer comprising a first block comprising at least one epoxide group, obtained by the polymerization of a first conjugated diene monomer, in particular isoprene, which is subsequently epoxidized, and a second block formed from a hydrocarbon chain that is substantially free of ethylenic double bonds, obtained by the polymerization of a second conjugated diene monomer, in particular 1,3-butadiene, subsequently terminated with at least one reactive functional group and hydrogenated. In this case, the hydrocarbon chain that is substantially free of ethylenic double bonds is a poly(ethylene/butylene) chain. [0055] Groups selected, for example, from: aliphatic groups, cycloaliphatic groups, aryl groups, or combinations thereof, may optionally be inserted into the hydrocarbon chain that is substantially free of ethylenic double bonds. Said groups are not incorporated into the main hydrocarbon chain that is substantially free of ethylenic double bonds, but are present in a side chain. In this case, in the epoxidized compound (a), the hydrocarbon chain that is substantially free of ethylenic double bonds may be, for example, poly(ethylene/butylene/styrene). [0056] Preferably, said hydrocarbon chain that is substantially free of ethylenic double bonds has an average (number-average) molecular weight, which may be determined for example by gel permeation chromatography (GPC), of between 2,000 daltons and 10,000 daltons, preferably between 3,000 daltons and 6,000 daltons. [0057] As stated above, the epoxidized compound (a) contains at least one epoxide group at the first end. The number of epoxide groups present in the epoxidized compound (a) may vary according to the epoxidation process used. [0058] According to a preferred embodiment, from 5 to 15 epoxide groups, preferably from 9 to 11 epoxide groups are present in the epoxidized compound (a), at the first end. [0059] As stated above, the epoxidized compound (a) contains at least one reactive functional group at the second end. The expression “reactive functional group” means a group that can react with compounds such as, for example, acrylates, vinyl ethers, epoxides, alcohols or isocyanates. Said reactive functional group may be selected, for example, from hydroxyl, acrylate, epoxy, vinyl ether, mercaptan. When two or more reactive functional groups are present, said groups may be identical to or different from each other. [0060] According to a preferred embodiment, in the epoxidized compound (a), the reactive functional group present at the second end is a hydroxyl group. [0061] When the reactive functional group is a hydroxyl, said group may be converted into other reactive functional groups using techniques known in the art. [0062] The epoxidized compound (a) may be prepared in various forms according to the technique used. [0063] According to a preferred embodiment, the epoxidized compound (a) is a linear, star or radial polymer. The epoxidized compound (a) is preferably a linear polymer. [0064] According to a further preferred embodiment, the epoxidized compound (a) has an average (number-average) molecular weight of between 3,000 daltons and 15,000 daltons, preferably between 5,000 daltons and 7,000 daltons. Said average molecular weight may be determined as described above. [0065] According to a further preferred embodiment, the epoxidized compound (a) has a viscosity, measured at 30° C., of less than 1,000 poise, preferably less than 600 poise, up to 100 poise. Said viscosity may be determined, for example, using a viscometer of Brookfield type, model DV-III, equipped with a configuration 29 . [0066] Epoxidized compounds (a) which may be used in the present invention are commercially available, for example, under the brand name Kraton Liquid™ Polymer from Kraton Polymer. Kraton Liquid™ EKP-207 is particularly preferred. [0067] The substantial absence of ethylenic double bonds in the hydrocarbon chain of the epoxidized compound (a) is particularly preferred for the purposes of the present invention, since their presence can cause degradation phenomena (thermal or oxidative degradation or degradation by exposure to ultraviolet light) of said compound. Any degradation might in its turn involve a worsening in the mechanical properties of the polymer coating of the optical fiber. In addition, unwanted phenomena of coloration of said coating might be encountered. [0068] According to a preferred embodiment, the hydrogenated polydiene oligomer (b) (referred to hereinbelow for simplicity as “hydrogenated compound (b)”) generally comprises a base polymer structure of synthetic or natural origin, which is derived from the (co)polymerization of one or more conjugated diene monomers, optionally copolymerized with other ethylenically unsaturated monomers. [0069] Conjugated diene monomers that are particularly preferred for the purposes of the present invention are those containing from 4 to 24 carbon atoms, preferably from 4 to 12 carbon atoms, selected, for example, from: 1,3-butadiene, isoprene, piperylene, methylpentadiene, phenylbutadiene, 3,4-dimethyl-1,3-hexadiene, 4,5-diethyl-1,3-octadiene, or mixtures thereof. 1,3-butadiene and isoprene are particularly preferred. [0070] Ethylenically unsaturated monomers that are particularly preferred according to the present invention are, for example: α-olefins containing from 2 to 12 carbon atoms (for example ethylene, propylene, 1-butene), monovinylarenes containing from 8 to 20 carbon atoms (for example styrene, 1-vinylnaphthalene, 3-methylstyrene), vinyl esters in which the ester group contains from 2 to 8 carbon atoms (for example vinyl acetate, vinyl propionate, vinyl butanoate), alkyl acrylates and alkyl methacrylates in which the alkyl contains from 1 to 8 carbon atoms (for example ethyl acrylate, methyl acrylate, methyl methacrylate, t-butyl acrylate, n-butyl acrylate), acrylonitrile, or mixtures thereof. [0071] According to a preferred embodiment, in the hydrogenated compound (b), the reactive functional group may be selected, for example, from: hydroxyl, acrylate, epoxy, vinyl ether, mercaptan. When two or more reactive functional groups are present, said groups may be identical to or different from each other. Preferably, said reactive functional group is a hydroxyl group, more preferably it is a hydroxyl group in an end position. Preferably, the hydrogenated compound (b) has a hydroxyl functionality of between about 0.5 and about 2.6. Said hydroxyl functionality may be determined, for example, according to ASTM standard E222-00. [0072] According to a further preferred embodiment, the hydrogenated compound (b) has a viscosity, measured at 30° C., of between about 10 poise and about 1,000 poise, more preferably between about 20 poise and about 400 poise. Said viscosity may be determined as described above. [0073] According to a further preferred embodiment, the hydrogenated compound (b) has an average (number-average) molecular weight of between about 500 daltons and about 20,000 daltons, more preferably between about 2,000 daltons and about 10,000 daltons. Said average molecular weight may be determined as described above. [0074] According to a further preferred embodiment, the hydrogenated compound (b) containing at least one hydroxyl end function has a hydroxyl-equivalent weight of between about 250 and about 20,000, preferably between about 500 and about 10,000. Said hydroxyl-equivalent weight may be determined, for example, according to ISO standard 3001:1999. [0075] Hydrogenated compounds (b) that may be used in the present invention are commercially available, for example, under the brand name Kraton Liquid™ Polymer from Kraton Polymer. Kraton Liquid™ L-1203 Polymer and L-2203 Polymer are particularly preferred. [0076] The hydrogenated compound (b) may be prepared according to known techniques. For example, the base polymer may be prepared by (co)polymerization of the corresponding monomers in emulsion, in suspension or in solution. In particular, the base polymers obtained by anionic polymerization in the presence of an organometallic initiator (in particular an organolithium initiator) may be functionalized by reacting the residual organometallic groups derived from said initiator by reaction with suitable terminating agents such as, for example, alkylene oxides or low molecular weight epoxides in the presence of small amounts of aliphatic tertiary amines such as, for example, N,N,N 1 ,N 1 -tetramethyleneethylenediamine. Further details regarding the preparation of the hydrogenated polydiene oligomers described above are given, for example, in patents U.S. Pat. No. 4,039,593 and U.S. Pat. No. 5,916,941. [0077] According to a preferred embodiment, the photo-initiator (c) may be selected from salts that are capable of. forming strong acids when subjected to UV irradiation so as to initiate the cationic crosslinking. [0078] Specific examples of photo-initiators (c) which may be used in the present invention are: hexafluorophosphorus triarylsulphonium salts, hexa-fluoroantimony triarylsulphonium salts, (tolylcumyl)tetrakis(pentafluorophenyl)iodonium salts, diaryl-iodonium hexafluoroantimonate salts, or mixtures thereof. [0079] As stated above, the crosslinkable composition according to the present invention may optionally comprise a reactive diluent monomer (e). [0080] According to a preferred embodiment, said reactive diluent monomer (e) may be selected from vinyl ethers such as, for example, n-butyl vinyl ether, n-dodecyl vinyl ether, or mixtures thereof. [0081] For the purposes of limiting the problems outlined above relating to the use of reactive diluent monomers, it is preferable for the amount of reactive diluent monomer added to the crosslinkable composition to be not greater than 20 parts by weight, preferably between 0 parts by weight and 10 parts by weight relative to 100 parts by weight of (a)+(b). [0082] As stated above, the crosslinkable composition according to the present invention may optionally comprise at least one adhesion promoter (d). The adhesion promoter (d) provides increased adhesion between the glass fiber and the primary coating. As observed by the Applicant, while the adhesion between the crosslinked composition and the glass is generally acceptable, in particular on the freshly manufactured optical fiber, this adhesion may nevertheless be impaired upon ageing, with possible undesirable reduction of said adhesion strength. The use of a suitable adhesion promoter thus allows to maintain the value of adhesion strength at an acceptable value, also upon ageing of the optical fiber. [0083] Said adhesion promoter (d) is preferably an organo-functional silane. [0084] For the purpose of the present description and the claims, the term “organo-functional silane” is intended to indicate a silyl compound with functional groups that facilitate the chemical or physical bonding between the glass surface and the silane, which ultimately results in increased or enhanced adhesion between the primary coating and the glass fiber. [0085] Specific examples of organo-functional silanes that may be used in the present invention are: octyltriethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, tris(3-trimethoxysilylpropyl)-isocyanurate, vinyltriethoxysilane, vinyltrimethoxysilane, vinyl-tris(2-methoxyethoxy)silane, vinylmethyl-dimethoxysilane, gamma-methacryloxypropyltrimethoxysilane, beta(3,4-epoxycyclohexyl)ethyltrimethoxy-silane, gamma-glycidoxypropyltrimethoxysilane, gamma-mercapto-propyltrimethoxysilane, organo-modified polydimethylsiloxane, gamma-ureidopropyltrialkoxysilane, gamma- ureidopropyltrimethoxysilane, gamma-isocyanate-propyltriethoxysilane, or mixtures thereof. gamma-Glycidoxypropyltrimethoxysilane, beta(3,4-epoxycy-cloexhyl)ethyltrimethoxysilane and gamma-mercaptopropyl-trimethoxysilane, are particularly preferred. gamma-Mercaptopropyltrimethoxysilane is more particularly preferred. [0086] Other examples of organo-functional silanes that may be used in the present invention may be identified, for example, by the following structural formula (I): (R) 3 Si—C n H 2n —X  (I) in which the groups R, which may be identical to or different from each other, are chosen from: alkyl, alkoxy or aryloxy groups or from halogen atoms, on condition that at least one of the groups R is an alkoxy or aryloxy group; n is an integer between 1 and 6 inclusive; X is a group selected from: nitrous, mercapto, epoxide, vinyl, imido, chloro, —(S) m C n H 2n Si—(R) 3 in which m and n are integers between 1 and 6 inclusive and the groups R are defined as above. Among these, bis(3-trimethoxysilylpropyl)disulfane and bis(3-tri-ethoxysilylpropyl)disulfane, are particularly preferred. [0087] Adhesion promoters (d) that may be used in the present invention are commercially available, for example, under the brand name Silquest® A-187 and Silquest® A-186 from OSi Specialties, Dynasylan® MTMO and Si® 266 from Degussa-Hüls. [0088] The adhesion promoter is preferably added to the crosslinkable composition in an amount of from 0.1 parts by weight to 2.5 parts by weight, more preferably of from 0.3 parts by weight to 1,5 parts by weight relative to 100 parts of (a)+(b). [0089] Conventional additives may be added for the purpose of improving the fundamental characteristics of the abovementioned composition. For example, solvents, plasticizers, surfactants capable of improving the wettability (“wetting”) of the coating on the glass portion of the optical fiber, devolatilizing agents, rheological agents, antioxidants, UV stabilizers capable of not interfering with the crosslinking operations may be added. [0090] According to one preferred embodiment, the crosslinkable composition comprises: (a) about 20-80 parts by weight of at least one epoxidized polydiene oligomer having a first and a second end comprising at least one hydrocarbon chain that is substantially free of ethylenic double bonds, at least one epoxide group at said first end and at least one reactive functional group at said second end; (b) about 20-80 parts by weight of at least one hydrogenated polydiene oligomer comprising at least one reactive functional group capable of reacting with said epoxide groups; (c) about 0.05-5 parts by weight relative to 100 parts of (a)+(b) of a photo-initiator. [0094] According to a further preferred embodiment, said crosslinkable composition further comprises about 0.1 parts by weight to 2.5 parts by weight relative to 100 parts of (a)+(b) of an adhesion promoter (d). [0095] As stated above, the abovementioned crosslinkable composition is particularly useful as a primary coating for an optical fiber. Said primary coating is then coated with a secondary coating that is compatible therewith. For example, a secondary coating formed from a crosslinkable composition comprising an epoxidized polydiene oligomer, a reactive diluent monomer and at least one photo-initiator may be used. [0096] The epoxidized polydiene oligomer generally represents from 30% to 70% by weight of the secondary coating composition. The epoxidized polymer is preferably a hydrocarbon polyol such as, for example, partially hydrogenated and epoxidized polybutadiene containing two hydroxyl end groups and internal epoxide groups along the chain. [0097] The reactive diluent monomer present in the composition of the secondary coating is generally used in an amount of up to 400 parts per 100 parts by weight of epoxidized polymer, preferably in an amount of between 40 and 200 parts by weight of epoxidized polymer. Reactive diluent monomers of epoxide type that may advantageously be used are, for example: 3,4-epoxy-cyclohexylmethyl-3,4-epoxycyclohexane carboxylate, limonene epoxide, cyclohexene epoxide, 1,2-epoxydodecane. Reactive diluent monomers of vinyl ether type that may advantageously be used are, for example: triethylene glycol divinyl ether, 1,4-butanediol monovinyl ether, 1,4-bis(vinyloxymethyl)cyclohexane. Reactive diluent monomers of oxetane type such as, for example: trimethylene oxide, 3,3-dimethyloxetane, 3,3-dichloromethyloxetane, 3-ethyl-3-phenoxymethyloxetane, bis(3-ethyl-3-methyloxy)butane, or mixtures thereof, may also advantageously be used. [0098] The photo-initiator present in the composition of the secondary coating is generally used in an amount of up to 10 parts per 100 parts by weight of epoxidized polymer, preferably in an amount of between 0.01 and 10 parts. Photo-initiators that may advantageously be used are: hexafluorophosphorus triarylsulphonium salts, hexafluoroantimony triarylsulphonium salts, (tolylcumyl)tetrakis(pentafluorophenyl)iodonium salts, diaryliodonium hexafluoroantimonate salts, or mixtures thereof. [0099] Further additives may be added for the purpose of improving the fundamental characteristics of the composition of the secondary coating. For example, solvents, levelling agents, surface tension modifiers, attrition coefficient modifiers, plasticizers, surfactants, devolatilizing agents, rheological agents, antioxidants, and UV stabilizers capable of not interfering with the crosslinking operations may be added. [0100] Said composition of the secondary coating preferably has a modulus of elasticity at room temperature of less than 2,500 MPa, preferably between about 300 MPa and about 2,000 MPa. Said modulus of elasticity may be determined by means of a DMTA analyser as described above. [0101] Compositions of the type described above which may be used as a secondary coating according to the present invention are described, for example, in patent U.S. Pat. No. 5,993,965. BRIEF DESCRIPTION OF THE DRAWINGS [0102] The present invention may be understood more clearly with reference to the following attached figures: [0103] FIG. 1 : is a cross section of an optical fiber according to the invention; [0104] FIG. 2 : is the general scheme of a system (spinning tower) for producing an optical fiber according to the invention. DETAILED DESCRIPTION OF THE INVENTION [0105] FIG. 1 shows an optical fiber according to the present invention, comprising a glass portion ( 101 ) covered with a primary coating ( 102 ) which may be produced according to the present invention, and which in its turn is covered with a secondary coating ( 103 ). [0106] An optical fiber according to the present invention may be produced according to the usual spinning techniques, using, for example, a system such as the one schematically illustrated in FIG. 2 . [0107] This system, commonly known as a “drawing tower”, typically comprises a furnace ( 302 ) inside which is placed a glass optical preform to be drawn. The bottom part of said preform is heated to the softening point and drawn into an optical fiber ( 301 ). The fiber is then cooled, preferably to a temperature of not less than 60° C., preferably in a suitable cooling tube ( 303 ) of the type described, for example, in patent application WO 99/26891, and passed through a diameter measurement device ( 304 ). This device is connected by means of a microprocessor ( 313 ) to a pulley ( 310 ) which regulates the spinning speed; in the event of any variation in the diameter of the fiber, the microprocessor ( 313 ) acts to regulate the rotational speed of the pulley ( 310 ), so as to keep the diameter of the optical fiber constant. Then, the fiber passes through a primary coating applicator ( 305 ), containing the coating composition in liquid form, and is covered with this composition to a thickness of about 25 μm-35 μm. As stated above, the application of the primary coating is preferably carried out at a temperature of at least 60° C., preferably between 80° C. and 100° C. The coated fiber is then passed through a UV oven (or a series of ovens) ( 306 ) in which the primary coating is crosslinked. The fiber covered with the crosslinked primary coating is then passed through a second applicator ( 307 ), in which it is coated with the secondary coating and then crosslinked in the relative UV oven (or series of ovens) ( 308 ). Alternatively, the application of the secondary coating may be carried out directly on the primary coating before the latter has been crosslinked, according to the “wet-on-wet” technique. In this case, a single applicator is used, which allows the sequential application of the two coating layers, for example, of the type described in patent U.S. Pat. No. 4,474,830. The fiber thus covered is then crosslinked using one or more UV ovens similar to those used to crosslink the individual coatings. [0108] Subsequently to the coating and to the crosslinking of this coating, the fiber may optionally be made to pass through a device capable of giving a predetermined torsion to this fiber, for example of the type described in international patent application WO 99/67180, for the purpose of reducing the PMD (“Polarization Mode Dispersion”) value of this fiber. The pulley ( 310 ) placed downstream of the devices illustrated previously controls the spinning speed of the fiber. After this drawing pulley, the fiber passes through a device ( 311 ) capable of controlling the tension of the fiber, of the type described, for example, in patent application EP 1 112 979, and is finally collected on a reel ( 312 ). [0109] An optical fiber thus produced may be used in the production of optical cables. The fiber may be used either as such or in the form of ribbons comprising several fibers combined together by means of a common coating. [0110] Although the present invention has been described with particular reference to a primary coating which is in turn coated with a secondary coating, according to the abovementioned description it is apparent to those skilled in the art that a crosslinkable formulation according to the present invention may be suitably formulated so as to be used as a secondary coating, or as a single coating for an optical fiber. [0111] The present invention will be further illustrated hereinbelow by means of a number of implementation examples that are provided purely as a guide and are non-limiting on the invention. EXAMPLES 1-5 Preparation of Compositions for Primary Coating [0112] Compositions for the primary coating according to the invention were prepared: the amounts of the components (parts by weight except where otherwise mentioned) are given in Table 1. TABLE 1 COMPOSITIONS COMPONENTS 1 (*) 2 (*) 3 4 5 Poly Bd ® 605 76 — — — — Kraton ® Liquid — 80 50 50 50 L-207 Kraton ® Liquid — — 50 — 30 L-1203 Kraton ® Liquid — — — 50 20 L-2203 Rapicure ® HBVE 24 — — — — Rapicure ® CHVE — 20 — — — UVI ® 6974  1  1  1  1  1 (*): comparative Poly Bd ® 605: epoxidized polybutadiene sold by Elf Atochem; Kraton Liquid ™ EKP-207: linear oligomer containing a poly(ethylene/butylene) aliphatic chain, a hydroxyl group at one end and epoxide groups at the other end, sold by Kraton Polymer; Kraton Liquid ™ L-1203: hydroxy-terminated hydrogenated polydiene oligomer sold by Kraton Polymer; Kraton Liquid ™ L-2203: dihydroxy-terminated hydrogenated polydiene oligomer sold by Kraton Polymer; Rapicure ® HBVE: 4-hydroxybutyl vinyl ether sold by ISP; Rapicure ® CHVE: cyclohexane dimethanol vinyl ether sold by ISP; UVI ® 6974: hexafluoroantimony triarylsulphonium salt, a photo-initiator sold by Union Carbide, as a 50% dispersion in propylene carbonate (the amount given is relative to 100 parts of the other components). [0113] The components given in Table 1 were placed in a 100 ml beaker and kept under stirring, at room temperature, for 1 hour. They were then left to stand overnight in order to obtain a homogeneous composition free of bubbles. EXAMPLE 6 Mechanical and Chemical-Physical Analyses [0114] The compositions of Examples 1-5 were subjected to the following mechanical and chemical-physical analyses. [0000] Viscosity [0115] The viscosity of the non-crosslinked compositions obtained according to Examples 1-5 was measured, at 30° C. and at 80° C., using a viscometer of Brookfield type, model DV-III, equipped with a configuration 29 . The results obtained are given in Table 2. [0000] Modulus of Elasticity Values [0116] Films were obtained from the abovementioned compositions by working as follows. A film 70 μm in thickness and 120 mm in width was spread onto a glass plate using the “Bird” filmograph at a speed of 2 m per minute; the crosslinking of the film was carried out using a Fusion UV curing System device, model F600 and lamp with spectrum H, applying a UV dose of 1.25 J/cm 2 . At the end of the crosslinking, the films were removed from the glass plate. [0117] The film obtained from the composition of Example 2 was not subjected to further analyses since said composition was found to have undergone little crosslinking; as a matter of fact, said composition had a sticky appearance and left residues on the surface of the glass at the time of removal. [0118] The films thus obtained were conditioned for 24 hours, at 25° C. and at 50% relative humidity, and were then subjected to measurement of the modulus of elasticity by means of a DMTA (Dynamic Mechanical Thermal Analyser from Reometrics Inc.), in traction, at a frequency of 1 Hz and at a heating rate of 2° C./min over the temperature range between −60° C. and 120° C. [0119] The results obtained, relating to the modulus values measured at room temperature (20° C.) and at −40° C., are given in Table 2. [0000] H 2 O Absorption of the Crosslinked Films [0120] The films obtained as described above, predried in an atmosphere flushed with dry air for 48 hours, were subjected to, controlled absorption of H 2 O. To this end, the Igasorp machine from Hiden Analytical was used, working at a temperature of 55° C., with a relative humidity of 95%, until an asintotic value in the absorption of the water content was reached. [0121] The results obtained, expressed as a percentage absorption of absorbed water, are given in Table 2. [0000] Thermal Ageing [0122] The films obtained as described above were subjected to ageing for 8 days, at 80° C. The reduction in mechanical characteristics, in particular the elongation at break and the stress at break were then evaluated: the results obtained (the percentage variation is reported) are given in Table 2. [0123] To this end, the mechanical characteristics were measured using an INSTRON 4502, Series 9 dynamometer, at a traction speed of 25 mm/mm, on punches 150 mm in height and 20 mm in width obtained from the abovementioned films preconditioned at 25° C., with a humidity of 50%, for 24 hours. For comparative purposes, the mechanical characteristics were also measured on punches obtained from non-aged films. [0124] The percentage variation in the mechanical characteristics was calculated relative to the value of said characteristics measured on punches obtained from the comparative (non-aged) films. [0000] Amount (%) of Extractable Materials after Crosslinkinq [0125] The amount of extractable materials was measured as follows. The films obtained as described above were immersed in distilled water contained in 250 ml beakers, said beakers were covered so as to limit the evaporation of the water and were then placed in an oven thermostatically maintained at 60° C. The treatment was continued for 15 days, filling up, if necessary, with distilled water when the level decreased. At the end, the extracted material (E) was calculated according to the following formula: E = W 0 - W 1 W 0 * 100 in which: W 0 represents the weight of the original film dried at 60° C. for 24 hours; W 1 represents the weight of the film subjected to the abovementioned treatment and then dried at 60° C. for 24 hours. [0128] The results obtained are given in Table 2. TABLE 2 COMPOSITIONS 1 (*) 2 (*) 3 4 5 Viscosity at 30° C. 12.5 80.0 445 650 505 (poise) Viscosity at 80° C. — — 19.0 27.0 20.8 (poise) Modulus at 20° C. 102 — 1.3 2.7 2.1 (MPa) Modulus at −40° C. 2540 — 36 30 34 (MPa) H 2 O absorption 2.3 — 0.45 0.70 0.50 (%) Elongation at break  −94% —  +6% −15 +10 (% variation) Stress at break +414% — +21% +60 +39 (% variation) Extractable 0.9 — 0.1 0.1 0.1 materials (%) (*): comparative [0129] The data given in Table 2 show that the crosslinkable composition according to the present invention (Examples 3, 4 and 5) is better than the comparative composition (Examples 1 and 2). In particular, the crosslinkable composition according to the present invention shows: lower modulus values at low temperatures; less water absorption; less variation in the elongation at break and in the stress at break; smaller amount of extractable materials. EXAMPLES 7-11 Preparation of Compositions for Primary Coating with Adhesion Promoter [0134] Compositions for primary coating with adhesion promoter according to the invention were prepared: the amounts of the components (parts by weight except where otherwise mentioned) are given in Table 3. TABLE 3 COMPOSITIONS COMPONENTS 7 8 9 10 11 (a) Kraton ® Liquid 50 50 50 50 50 L-207 (b) Kraton ® Liquid 50 50 50 50 50 L-1203 BYK ® 361 0.5 0.5 0.5 0.5 0.5 Silquest ® A-187 — 1.0 — — — Silquest ® A-186 — — 1.0 — — Dynasylan ® MTMO — — — 1.0 — Si ® 266 1.0 UVI ® 6974 0.5 0.5 0.5 0.5 0.5 Kraton Liquid ™ EKP-207: linear oligomer containing a poly(ethylene/butylene) aliphatic chain, a hydroxyl group at one end and epoxide groups at the other end, sold by Kraton Polymer; Kraton Liquid ™ L-1203: hydroxy-terminated hydrogenated polydiene oligomer sold by Kraton Polymer; BYK ® 361: polyacrylate copolymer sold by BYK-Chemie [the amount given is relative to 100 parts of the components (a) + (b)]; Silquest ® A-I87: gamma-glycidoxypropyltrimethoxysilane sold by OSi Specialties [the amount given is relative to 100 parts of the components (a) + (b)]; Siliquest ® A-I86: beta(3,4-epoxycycloexyl)ethyl-trimethoxysilane sold by OSi Specialties [the amount given is relative to 100 parts of the components (a) + (b)]; Dynasylan ® MTMO: gamma-mercaptopropyltrimethoxysilane sold by Degussa-Hüls [the amount given is relative to 100 parts of the components (a) + (b)]; Si ® 266: bis(3-triethoxysilypropyl)disulfane sold by Degussa-Hüls [the amount given is relative to 100 parts of the components (a) + (b)]; UVI ® 6974: hexafluoroantimony triarylsulphonium salt, a photo-initiator sold by Union Carbide, as a 50% dispersion in propylene carbonate (the amount given is relative to 100 parts of the components). [0135] The components given in Table 3 were placed in a 100 ml beaker and kept under stirring, at room temperature, for 1 hour. They were then left to stand overnight in order to obtain a homogeneous composition free of bubbles. EXAMPLE 12 Preparation of a Composition for Secondary Coating [0136] A composition for the secondary coating was prepared: the amounts of the components (parts by weight except where otherwise mentioned) are given in Table 4. TABLE 4 COMPONENTS COMPOSITION (1) Poly Bd ® 605 50 (2) Cyracure UVR ® 6105 40 (3) Cyracure UVR ® 6000 10 (4) UVI ® 6974 1.5 (5) BIK ® 361 0.5 Poly Bd ® 605: epoxidized polybutadiene sold by Elf Atochem; Cyracure ® UVR-6125: 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate sold by Union Carbide; Cyracure ® UVR-6000: 3-ethyl-3(hyrdoxymethyl)oxetane sold by Union Carbide; UVI ® 6974: hexafluoroantimony triarylsulphonium salt, photo-initiator sold by Union Carbide as a 50% dispersion in propylene carbonate [the amount given is relative to 100 parts of the components (1) + (2) + (3)]; BYK ®-361: polyacrylate copolymer sold by BYK-Chemie [the amount given is relative to 100 parts of the components (1) + (2) + (3)]. [0137] The components given in Table 4 were placed in a 100 ml beaker and were kept under stirring for 1 hour at room temperature. They were then left to stand overnight so as to obtain a homogeneous composition free of bubbles. [0138] The composition obtained was subjected to the following analyses: viscosity and modulus of elasticity values, working as described above in Example 1. The results obtained are given in Table 5. TABLE 5 COMPONENTS COMPOSITION Viscosity at 26° C. 20.1 (poise) Modulus at 20° C. 2010 (MPa) Modulus at −40° C. 2760 (MPa) EXAMPLES 13 Glass Adhesion Measurement [0139] The compositions of Examples 7-12 were subjected to the following analysis. [0140] Glass plates coated with films made from the compositions of Examples 7 to 11 (primary coating) and from the composition of Example 12 (secondary coating) were obtained by working as follows. A film of primary coating (70 μm thick and 100 mm width) was spread onto a glass plate previously conditioned at 130° C. for 10 hours using the “Bird” filmograph at a speed of 1 m per minute; the crosslinking of the film was carried out using a Fusion UV curing System device, model F600 and lamp with spectrum H, applying a UV dose of 1.5 J/cm 2 . At the end of the crosslinking, a composition for secondary coating prepared according to Example 12, was spread as a film (70 μm thick and 120 mm width) onto the said cross-linked film and was subjected to the crosslinking operating at the working conditions above disclosed. [0141] The glass plates thus obtained were conditioned for 24 hours, at 25° C. and at 50% relative humidity, and were subsequently immersed in distilled water for 24 hours at 25° C. (aged samples). At the end of said ageing treatment, the glass plates were subjected to glass adhesion measurement. To this end, from the above mentioned glass plates samples having about 140 μm in thickness and 40 mm in width were obtained. A traction force in a direction perpendicular to the glass surface at a traction speed of 50 mm/mm was applied to said samples, using an INSTRON 4502, Series 9 dynometer equipped with a movable platform and a load cell of 10 N. In order to work in water saturation conditions, said measurements were carried out not more than 10 minutes after the glass plates were extracted from the water. For comparative purposes, the glass adhesion measurement was also carried out on samples obtained from non-aged films. [0142] The results obtained, expressed in Newton/meter (N/m), are given in Table 6. TABLE 6 NON-AGED FILMS AGED FILMS COMPOSITIONS (N/m) (N/m) 7 62.5 5.0 8 67.3 32.5 9 84.3 21.2 10 113.3 58.0 11 68.1 83.9 [0143] The data given in Table 6 show that the addition of an adhesion promoter to the crosslinkable composition according to the present invention improve the adhesion between the glass fiber and the primary coating, in particular upon ageing of the coating. EXAMPLE 14 Production of Optical Fibers [0144] Two optical fibers were produced according to the techniques known in the art, comprising a primary coating according to the present invention (compositions of Examples 7 and 10) and a secondary coating prepared according to Example 12. The primary coating was applied at a temperature of 80° C. as the secondary coating was applied, at a temperature of 26° C. The spinning speed was 14 m/s. The primary coating and the secondary coating were applied to a thickness of 30 μm each. EXAMPLE 15 Strip Test [0145] Two test specimens of the optical fibers obtained as disclosed in Example 14 were subjected to a strip test according to the Bellcore standard GR-20-CORE, July 1998, section 4.4.2. To this end, the specimens were conditioned at room temperature, with a humidity of 50%, for 7 days and subsequently were immersed in water at 20° C. and at 60° C. for 7 days (aged samples). For comparative purposes, the strip test was also carried out on samples obtained from non-aged specimens. [0146] The result obtained, which are the average of 5 different tests, are given in Table 7. TABLE 7 STRIP FORCE VALUE (N) Example 7 Example 10 NON-AGED 1.00 1.82 AGED 0.00 1.00 (7 days at 20° C.) AGED 0.00 0.78 (7 days at 60° C.) [0147] The data given in Table 7 show that the addition of an adhesion promoter to a crosslinkable composition according to the present invention improve the adhesion between the glass fiber and the primary coating, in particular upon ageing of the coating. EXAMPLE 16 Attenuation Measurement [0148] A 1 000 m skein of the optical fiber obtained as disclosed in Example 14 comprising a primary coating according to the present invention (composition of Example 7) and a secondary coating prepared according to Example 12, was subjected to attenuation measurements using an OTDR (optical time domain reflectometer) from ANRITSU, model MW 90-60 A. [0149] The attenuation measurements carried out at 20° C. and at 1550 nm gave a value of 0.20 dB/km, while the attenuation measurements carried out at 20° C. and at 1330 nm gave a value of 0.35 dB/km. The use of the primary coating according to the present invention thus gives the optical fiber good attenuation characteristics.

An optical fiber having at least one epoxidized polyolefin based polymer coating. The coating is formed from a crosslinkable composition having (a) at least one epoxidized polydiene oligomer having a first and a second end, the oligomer having at least one hydrocarbon chain that is substantially free of ethylenic double bonds, at least one epoxide group at the first end and at least one reactive functional group at the second end; (b) at least one hydrogenated polydiene oligomer having at least one reactive functional group capable of reacting with the epoxide groups; and (c) at least one photo-initiator. Preferably, the coating is a primary coating coated with a secondary coating.

BACKGROUND OF THE INVENTION The present invention relates to a nuclear reactor cooled by a liquid metal of the type comprising a vessel filled with liquid metal, whose upper part is sealed by a rigid slab which supports the heat exchangers and the pumps of the primary circuit. More specifically the invention relates to an integrated fast neutron nuclear reactor, i.e. of the type in which the complete primary circuit of the reactor is housed in the vessel. In this type of reactor, the core thereof containing the fuel assemblies rests on the bottom of the vessel or on its periphery by means of a support for the supply of liquid metal (generally sodium) and a plate system. The liquid sodium is heated in the core by the fission reaction of the nuclear fuel before entering a hot collector placed above the core. It then circulates in heat exchangers in which it transmits a large part of its heat to the fluid (generally sodium) flowing in the secondary circuits. The cooled primary sodium leaving the lower part of the heat exchangers in a cold collector is sucked in by primary pumps, which reinject it into the support. In this type of reactor, the exchangers and primary pumps are generally suspended on the slab sealing the reactor vessel. The same applies with regards to a certain number of other members necessary for the operation or safety of the reactor, including the exchangers for cooling the reactor when it is shut down. In known manner the slab sealing the vessel is constituted by a welded sheet metal structure forming a group of concrete-filled cavities in order to constitute a neutron protection and contribute to the rigidity of the slab. The lower face of the slab is provided with a cooling circuit and a lower thermal insulation covering immersed in the neutral gas above the liquid metal at approximately 500° C. This face can then be kept at a temperature which does not exceed e.g. 100° C. The thickness of the slab, which is fixed in such a way that an adequate strength and displacements which are sufficiently reduced during the temperature variations of the lower face are obtained is approximately 2.50 m for large reactors with an electric power of 1000 to 1500 MW. The exchangers and primary pumps are installed in a group of orifices or vertical shafts passing through the slab and having a diameter which is sufficient to permit their vertical introduction. In their part corresponding to the thickness of the slab, these components have sealing, as well as thermal and neutron protection members ensuring a functional continuity with the slab. The heads of these components, which are specific to their operation (motors for the pumps, connections to the secondary circuits, etc.) are positioned above the slab, as well as the system of circuits. A slab formed in this way is considered to be thin because every effort is made to reduce the heights devoted to neutron insulation and supporting functions, both with respect to the slab in order to facilitate the overall design and on the components, whose total height considerably influences the cost and ease of handling. A structure formed in this way with a thin slab in stages and an upper area for the heads of the components suffers from several disadvantages. Firstly the group of equipment and heads of components above the slab are vulnerable to impacts and shocks taking place during the handling of heavy objects above the slab. In addition, the thus heightwise exposed heads of exchangers can only be protected from possible secondary sodium leaks leading to a fire by adding a doubling envelope, which is onerous and makes it more difficult to regularly inspect the main wall. Moreover, for a given strength, the thinness of the slab makes it necessary to use more steel than if freedom existed with regards to the thickness. Furthermore, to limit heightwise displacements linked with expansion of the lower plate, this thinness imposes severe constraints with regards to its temperature. Finally the cavities within the slab, which are entirely filled with concrete cannot be inspected. BRIEF SUMMARY OF THE INVENTION The present invention relates to a liquid metal-cooled nuclear reactor, which obviates the disadvantages referred to hereinbefore in connection with the hitherto known reactors with a relatively thin slab. More specifically the invention relates to the construction of a reactor in which the slab sealing the vessel substantially forms a flat floor preventing any risk of impact during handling operations above the slab, whilst ensuring an individual confinement of the heads of the exchangers permitting a direct inspection of the primary wall. To this end the present invention proposes a liquid metal-cooled nuclear reactor comprising a vessel filled with liquid metal and whose upper part is sealed by a rigid slab having a central opening in which is housed at least one rotary plug overhanging the reactor core and first peripheral openings arranged in the form of a ring around the central opening and by which are suspended heat exchangers, wherein at least one of said first peripheral openings has, in the thickness of the slab, a lower part by which is suspended one of the heat exchangers and a first upper housing by which is confined the exchanger head, said first housing being sealed by a cover above the exchanger head. It is clear that in a reactor constructed in this way due to the individual confinement of the exchanger heads a high degree of safety and reliability is obtained with respect to sodium leaks and impacts due to handling operations carried above the slab. In addition, these characteristics make it possible to simplify the heads of the exchangers by eliminating their double-walled fairing so that the primary wall can be directly inspected e.g. by a television camera. Moreover, the increase in the thickness of the slab compared with the prior art reactors, which increase is rendered necessary by the use of the above-indicated housings, makes it possible for a given mass of metal, to increase the strength and the rigidity of the slab, subject to maintenance of the necessary strength of the radial positions which exist between the housings on the whole height of the slab. This increase of the thickness of the slab, e.g. until 6 m, also makes it possible to much more easily perform the protective fillings because it makes the metal structures of the slab much more easily accessible for human intervention. Finally these characteristics make it possible to construct a flat floor around the rotary plug, which facilitates operation. The housings in which the exchanger heads are received can be extended radially for the passage of the pipes of the secondary cooling circuit, until a cylindrical wall surrounding the slab, said wall being traversed by the pipes through external tight packings. The exchanger heads and the pipes being thus confined within these housings, the double walls required in the prior art reactors can be suppressed. According to another feature of the invention, the slab having in its thickness second peripheral openings by which are suspended pumps, at least one of these second peripheral openings having, in the thickness of the slab, a lower part by which is suspended one of said pumps, and a second upper housing by which is confined the head of said pump, constituted by the going out of the pump shaft and by the required tightness, and at least a position of the driving members constituted by a drive shaft, possibly a flywheel, and a motor, this second housing being sealed by a cover above the pump head. It is favourable to locate the flywheel in the housing to limit the consequences of possible breaking. According to the particular case, the motor driving the rotating shaft can either be confined in the second housing, or can be placed outside said housing above the cover. The latter solution has the advantage of cooling the motor and of not excessively increasing the thickness of the slab due to the overall dimensions of such motors. According to another feature of the invention in the thickness of the slab there is a third housing for handling fuels, said third housing being connected to the interior of the vessel and to a fuel handling installation by two transfer devices. According to yet another feature of the invention it is also possible to cover the rotary plug of a detachable cover fixed to the slab, said cover being more particularly shaped like a dome. BRIEF DESCRIPTION OF THE DRAWINGS The invention is described in greater detail hereinafter relative to non-limitative embodiments and with reference to the attached drawings, wherein show: FIG. 1 a sectional view of the slab of a fast neutron nuclear reactor according to the invention, showing the installation of a primary pump and an intermediate exchanger. FIG. 2a a diagrammatic sectional view of a reactor slab according to the invention hollowed out for receiving a device for the transfer of fuel elements identical to that in a reactor, whose slab is in accordance with the prior art. FIG. 2b a diagrammatic sectional view of a reactor slab according to the invention, integrating a modified transfer device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS It is assumed that the general design of an integrated sodium-cooled, fast neutron nuclear reactor is known and a detailed description thereof is provided in the Journal "Nuclear Engineering International", vol. 23, No. 272, June 1978. The complete reactor below the slab is not shown, it only being possible to see its main attachments to the slab. It is assumed that the reactor is contained in a hot vessel attached beneath the slab. However, the description can easily also relate to other types of support. According to the prior art the complete primary circuit is confined in a vertically axed main vessel 10 with a hot wall connected to the slab 12 kept cool by a ferrule 10a having a thermal gradient. Vessel 10 is externally provided with a thermal insulation layer 14 and it is surrounded by a normally cold, safety vessel 16 which is also attached to slab 12. A cylindrical steel skirt 18 surrounds safety vessel 16 and supports the slab 12 as from the not shown bed or floor of the installation. Skirt 18 is cooled by a not shown device and it is surrounded by a concrete neutron protection cylinder 20 rising up round slab 12. Slab 12 is perforated by a group of openings or vertical shafts used for the fixing of large components. The central opening 22 overhanging the core of the reactor (not shown) serves to carry a large rotary plug 24, which itself carries the small rotary plug 26, traversed by the control plug 28 equipped with not shown control rods and by at least one vertical fuel handling apparatus 30. As a result of the combined rotations of the two rotary plugs 24 and 26, apparatus 30 makes it possible to transfer fuel elements from the reactor between a not shown fixed base located to the side of the core and any desired location in the latter. The drawing shows one of the shafts or peripheral openings 32 in slab 12 fixing an intermediate exchanger 34 supplied with tepid secondary sodium by means of pipe 36 and externally supplying hot secondary sodium by means of pipe 38. It is also possible to see one of the shafts or peripheral openings 40 in slab 12 fixing the primary pump 42, which is driven by electric motor 44, a flywheel 46 being fixed to the shaft in order to ensure a slow decrease of pumping in the case of an electric failure. The slab is constructed from welded steel sheets, constituting recesses or internal spaces and each recess is provided in its floor with a lining of neutron-absorbing material. The internal spaces other than the shafts are at least partly lined with neutron-absorbing materials, such as concrete 48. The lower face 12a protected by a thermal insulation covering 50 is cooled by a not shown cooling circuit. All the above arrangements are in accordance with the prior art. According to the present invention the thickness of slab 12 is increased compared with the prior art. It can be close to 6 m instead of 2.50 m in the known reactors of this type. As illustrated by FIG. 1, this feature makes it possible to provide in the slab thickness above each of the shafts 32 in which are fixed the exchangers 34, a housing 32a for the corresponding exchanger head, and above each of the shafts 40 in which are fixed the primary pumps 42, a housing 40a for the head of the corresponding pump and its flywheel 46. The plane shape of each housing is conditioned by the mechanical conception of the rigid slab, the metallic partitions connecting the lower face 12a to the upper face 12b, said partitions being for example purely radial and thus delimiting adjacent housings surrounding the central opening for the rotary plugs. Such plane partitions are indicated on FIG. 1 for the housings 32a and 40a. Each housing 32a is sealed by a detachable cover 32b flush with the upper face 12b of the slab. For each of the exchangers 34, the secondary sodium pipes 36, 38 move radially away from the reactor, whilst traversing the lateral metal wall 12c of the slab by orifices 52 and 54 equipped with metal sealing bellows between the wall and the pipes in order to ensure the seal with respect to the outside of housing 32a and so as to be able to fill it with inert gas. Each housing 40a comprises an upper portion of revolution, the wall of which portion being only at a limited distance from the corresponding flywheel 46 in order to reduce impact in the case of any fracture of the latter. Housings 40a are subdivided into two in the heightwise direction by a sealing floor 56 integral with the pump head and positioned below flywheel 46, so as to support the shattered flywheel during its deceleration. Moreover, each housing 40a is closed in its upper part by a cover 40b integral with motor 44 in the represented variant. Obviously motor 44 can be placed above the cover, as shown in FIG. 1, or in housing 40a if the dimensions of the latter permit. It is possible to visit housing 40a as a result of manhole 58 and gallery 60. The central opening 22 for the rotary plugs can be provided with a detachable dome-shaped cover 62 in order to provide a supplementary confinement if this is considered useful. All the other vertical penetrations existing in the relatively thin slabs according to the prior art can be reproduced with the present thick slab by modifications which are obvious to the Expert. In particular in an integrated reactor under construction, there are transfer ramps for the fuel elements leading to a swinging or tilting system placed above the slab. FIG. 2a diagrammatically shows a main reactor vessel 10 surmounted by a thick slab 12 according to the invention, which is laterally hollowed out to receive a swinging system 70 identical to that of the prior art. However, preference may be given to an arrangement according to FIG. 2b, which instead has a laterally extended fixing slab for defining a housing cavity 72 for the swinging device. Obviously the thick slab can be adapted so as to receive other fuel element transfer devices and ingenuity can be used for reducing the neutron shielding constraints of such apparatus by reducing their height and concealing them completely beneath the flat upper floor 12b of slab 12. In particular the following advantages result from the slab of the reactor according to the invention: The individual protection of the exchanger heads, each in a cavity sealed by a cover, means that they are not exposed to impacts which could result from handling errors in connection with heavy objects. The individual confinement of the exchanger heads, each of which is positioned in its own cavity, can easily be effected in neutral gas to eliminate any fire risk, without it being necessary to add a special fairing and whilst permitting continuous inspection by a television camera. The heads of the pumps and their flywheels are also not exposed to accidental impacts and only the pump motors could be exposed. The embedding of the pump flywheels in robust cavities provides security against their possible shattering. The requisite heights in each large component for ensuring an appropriate neutron protection can be reduced because said component is surrounded and surmounted by additional protection. The increased thickness of the slab 12 makes it possible, bearing in mind the relatively reduced dimensions of the housings for the component heads, to increase its strength and rigidity for a given steel mass and to reduce the sag linked with the heating of the underface. This increased thickness facilitates the construction and inspection of the metal part, as well as the introduction of the concrete filling. By separating the problem of the strength of the slab from that of the construction of the components, a better evolution of the design of projects is possible.

The invention relates to a fast neutron nuclear reactor in which the primary pumps and exchangers are suspended on the rigid slab sealing the vessel containing the reactor core. The slab has in its thickness housings of reduced dimensions in which are confined the heads of the exchangers and the primary pumps. The flywheels of the pumps and part of the pipes of the secondary circuits are also contained in the housings. Other housings can be provided in the slab, particularly for the handling of fuels. Application to the improvement of the safety and reliability of fast neutron reactors is taught.

TECHNICAL FIELD OF THE INVENTION [0001] The present invention pertains in general to investment fund accounting methods, and in particular to the ability of such funds to use shares or other units (collectively, “shares”) which maintain a uniform (although fluctuating) value while tracking and equitably distributing various fees and credits associated with investments in such funds, such as performance fees (“PFs”) and reversals thereof, differently among investors. The invention also permits tracking differential features applicable to each individual investor's investment. The method can be performed by any number of techniques, although a computer implemented method is preferred. BACKGROUND OF THE INVENTION [0002] The typical United States based private investment fund sponsor operates funds organized both under the laws of the United States and under the laws of one or more offshore jurisdictions—Ireland, Bermuda, Guernsey, the Cayman Islands, the Bahamas, etc. U.S. taxable investors invest in the domestic fund, while non-U.S. investors and U.S. tax-exempt investors invest in the offshore fund. The offshore fund structure (typically either a company or a trust) provides tax advantages to U.S. tax-exempt investors, is attractive to offshore investors, and facilitates compliance with the Investment Company Act of 1940. [0003] The typical U.S. private investment fund is formed as a partnership or a limited liability company and provides U.S. investors with the equitable (in terms of effecting financial and tax allocations among different investors)-i.e., partnership-accounting including the equitable investor-by-investor allocation of fees and credits which differ among different investors (e.g., PFs). In the partnership context, differential fees and credits do not present the accounting problem which the present invention resolves in the case of offshore funds, as in the partnership context there is no perceived or actual need to maintain a uniform quantum of investment (i.e., a “share” or a “unit”). Partnership accounting methods maintain an individual capital account for each investor, potentially with a value different than the capital account of each other investor, and these capital accounts are maintained on an aggregate and non-quantized basis—as a simple dollar (or other currency) amount. Offshore, however, the perceived or actual need to maintain a uniform value per share has necessitated adoption of entirely different accounting systems in which, for example: (i) differential fees and credits have been allocated through requiring additional payments by investors subject to subsequent reversal; (ii) the persons who would otherwise be recipients of differential credits have been required to waive payment of a portion of such credits; (iii) calculating fees which should properly differ from certain investors but not others on an overall find basis, effectively requiring all investors to pay a portion of such fees; and (iv) other complicated, economically inefficient and/or inequitable and administratively burdensome accounting mechanisms. [0004] The bifurcation between domestic and offshore fund accounting can be both onerous and expensive, as well as in many cases inequitable. The present invention enables investments in offshore companies to be accounted for on the same basis as investments in partnerships while maintaining a uniform asset value per share. Not only does this make possible the equitable allocation of differential fees and credits among investors, but it may also permit the use of a single accounting system for all funds organized by a given sponsor, whether formed as domestic partnerships or offshore companies or trusts. Definitions [0005] Performance Fee (PF): The fee owed to a fund manager (also called an advisor or) equal to a portion of the positive performance of an investment over a specified PF calculation period (typically a quarter or a year). For purposes of the examples and illustrations in this Application, a 20% PF is assumed. However, clearly any percentage or even non-percentage based method of payment could be chosen. PFs could also represent any item of cost or expense, or other items of profit and loss, which accrues differentially as between different investors. [0006] Depreciation Deposit (DD): An amount paid by investors in certain offshore funds, accounted for using the current art, equal to the PF due on gains which, in the case of certain other earlier investors, are less than or equal to their loss carryforwards. [0007] Asset value (AV): The total value of an asset, such as a “share,” without reduction for accrued PFs. [0008] Equalization Factor (EF): An amount paid by certain investors in investment funds, accounted for using the current art, equal to the difference between the asset value and the net asset value of the shares they acquire. [0009] Net asset value (NAV): The asset value of an asset, less any accrued PFs. In other words, the asset value of a share reduced any applicable PF=net asset value. [0010] Total asset value (TAV) of a fund: The sum of the asset values of all the shares in the fund. [0011] Loss carryforward: The amount of any losses incurred by an investor's interest in the fund since the end of the most recent PF calculation period as of which such interest was subject to a PF (or date of initial investment if no PF has been due). The loss carryforward (as adjusted for withdrawals made by the investor in question) must generally be earned back before an additional PF can be earned by the advisor in respect of such investor's interest. However, the use of the loss carryforward calculation is not a necessary feature of the invention; the loss carryforward is simply one commonly used component in the calculation of the PF. [0012] The following hypothetical illustrates one of the difficulties of maintaining uniform share values in an environment of differentially accruing fees and credits. As mentioned above, several methods for dealing with these difficulties have been used in the past, certain of which are outlined below. However, each of these methods has potentially material drawbacks associated with it, drawbacks which are minimized or eliminated by the present invention. TABLE 1 T 1 T 2 T 3 I 1 $100 $90 $95 I 2 $90 $95 TAV $100 $180  $190  [0013] Table 1 is a simplified representation of an investment fund which has two investors, investor I 1 and investor I 2 . T 1 , T 2 , and T 3 represent three different points in time during the initial PF calculation period for the investment fund. [0014] One common requirement or desired result for offshore funds is that they must maintain a uniform value per share (as in an operating company). Therefore, at any given point in time, a share owned by investor I 1 must have the same “value” (a concept which requires differentiating net asset value and asset value) as a share owned by investor I 2 . This constraint creates difficulties when, for example, investors invest in a fund at different points in time, as illustrated in Table 1. [0015] Referring now to Table 1, investor I 1 buys one share for $100 at T 1 . At T 2 , the value of the share has dropped to $90. At T 3 , the value of the share has increased to $95. With regard to the second investor, investor I 2 buys one share at T 2 , when the value of a share is $90. Then, at T 3 , the share owned by I 2 is worth $95. The total asset value of the fund at T 1 ,is $100, the total asset value at T 2 is $180, and the total asset value at T 3 is $190. [0016] Looking now at T 3 , it is clear that investor I 1 has a net loss of $5 since the inception of his investment, which has declined in value from $100 to $95. For investor I 2 , however, the value of his investment has increased from $90 to $95, representing a net increase of $5. Under this scenario, investor I 1 should owe no PF to the advisor since investor I 1 has no gain on his investment. Investor I 2 , however, should owe a PF to the advisor. In this example, assuming a 20% PF, investor I 2 's $5 net gain should result in a $1 PF owed to the advisor. [0017] At T 3 the advisor is entitled to a $1 PF. However, recall the requirement/desire to maintain a uniform net asset value per share. Because of this, one cannot simply deduct $1 from investor I 2 's share, since then investor I 2 's share would be worth $94, while investor I 1 's share would be worth $95. In order to maintain uniformity in the value of each share, one solution would require the allocation of the $1 PF equally between both I 1 and I 2 , resulting in both shares having an asset value of $94.50. However, it is inequitable to charge investor I 1 a $0.50 PF because he has actually lost $5 since he first invested. Likewise, equally distributing the PF between the two investors would be an unwarranted windfall for investor 12 , who would be paying only one-half of the full 20% PF due on his investment gain of $5. [0018] The art has heretofore dealt with this problem in a variety of ways. [0019] One solution has been simply to prohibit future investors from investing in a fund after it has been established; in other words, either by eliminating investor I 2 or causing T 2 =T 1 . This approach has material adverse economic consequences as funds typically raise most of their capital after they have been operating for some time and have performed favorably. [0020] Another possible solution has been for the advisor (fund manager) to waive a portion of his PF, so that investor I 2 has a “free (PF) ride” on the first $10 of gain. However, this inflicts a clear economic loss to the advisor who is denied his otherwise rightfully earned PF and giving investor I 2 a windfall. [0021] Various accounting schemes have been developed to avoid the potentially materially adverse effects of either prohibiting subsequent investors in a fund or imposing a “free (PF) ride” on the advisor. These schemes have addressed some, but not all, of the associated problems which are resolved by the present invention. [0022] The simplest of these schemes eliminates the problem by compelling the investors to accept the risk of an inequitable allocation of PF. The investment fund as a whole pays a PF based on its overall performance and that PF reduces the asset value per share equally for all shares, irrespective of when they were issued or their investment experience in the fund. This method is widely disfavored due to its obvious inequity (potentially both to the investors and to the advisors, depending on the interrelationship of find performance and subscriptions/redemptions). [0023] Another such scheme compels later investors to pay an EF or a DD, depending on the status of the fund at the time of the later investments. TABLE 2 T 1 T 2 T 3 I 1 NAV $100  $108  $108 PF 0  2  2 AV 100 110 110 I 2 NAV X 108 108 EF X  2  2 INVESTMENT 110 [0024] Table 2 illustrates the use of an EF when a second investor invests during a PF calculation period, and at a time when an earlier investor has accrued gains. In this hypothetical, investor I 1 purchases a share for $100 at T 1 . At this time, the net asset value and asset value are both $100, since no PF has yet accrued. By T 2 , the asset value of the share has risen to $110. Because the advisor is entitled to a PF (again, assume 20%), the net asset value at T 2 is $108, and the accrued PF is $2. At T 3 , the value of the share has not changed since T 2 , thus meaning that the net asset value of the share remains $108, and the accrued PF for the advisor remains $2. [0025] Now assume that investor I 2 purchases a share at T 2 . At T 2 , while the net asset value of investor I 1 's share is only $108, since $2 is contingently owed to the advisor (subject to possible reversal in the event of subsequent losses during the current calculation period), investor I 1 nevertheless has $110 invested in the fund, as the contingent PF is not yet due. As a result, this scheme requires investor I 2 to invest not $108—the net asset value per share—but $110, so that I 2 has as much risk as I 1 . The $2 difference between the amount invested and the net asset value per share is called the EF. [0026] The EF is held in an account in the name of I 2 and participates in the fund's profits and losses. At T 3 —the end of the PF calculation period—investor I 1 owes $2 to the advisor (i. e., the PF is no longer accrued, but due). However, at T 3 , investor I 2 owes nothing to the advisor, since his investment has not appreciated since he purchased his share at T 2 . After payment of the $2 PF, the net asset value per share at T 3 is $108. The $2 EF attributable to investor 12 is then invested in additional shares so that investor I 2 holds 1 {fraction (2/108)} shares with a net asset value per share of $108, and investor I 1 holds one share with a net asset value per share of $108. [0027] On the other hand, had there been losses subsequent to T 2 , I 2 's EF would be reduced, thereby preventing I 2 from unfairly benefiting from the reversal of the PF accrued with respect to I 1 's shares. If, for example, the fund lost $10 in the period T 2 -T 3 , this would result in the net asset value per share declining, on a preliminary basis, to $103. However, the $5 loss attributable to I 1 would cause the PF accrued against his share to decrease from $2 to $1. Accordingly, the net asset value of his share would be $104, not $103. Had I 2 invested at T 2 at a net asset value of $108, in order to maintain a uniform net asset value per share the $1 decrease in the accrued PF would have to be allocated equally between I 1 's and I 2 's shares. This would result in a net asset value per share of $103.50, not $104. I 1 would have lost $0.50 unfairly. The EF is used to prevent this by being reversed, and increasing the aggregate net asset value of the fund in an amount sufficient to ensure that I 1 receives the full benefit of the reversal of the PF attributable to I 1 's shares. Accordingly, at T 3 , investor I 1 would have one share with a net asset value of $104 and a $1 accrued PF, and I 2 would have one share with a net asset value of $104 and a remaining EF of $1. This $1 would then be invested in new shares; I 1 would hold 1-{fraction (1/104)} shares, and I 2 would hold one share, all with a net asset value per share of $104. [0028] In this way, share value uniformity is achieved, while eliminating inequities in terms of the payment of PFs. However, the EF mechanism has been the source of considerable confusion among investors and fund sponsors alike. [0029] Furthermore, the EF/DD scheme has a clear economic cost in the case of investors who acquire shares when a loss carryforward exists. If investor I 2 invests at a point in time when I 1 has sustained a net loss, then the EF/DD scheme has forced I 2 to provide a DD—a situation illustrated by Table 3. TABLE 3 T 1 T 2 T 3 I 1 NAV $100  $90  $100  PF  0  0  0 AV 100 90 100 I 2 NAV X 90 100 DD X  2  2 92 102 [0030] Referring to Table 3, at T 1 , a share has a net asset value of $100. At T 2 , the net asset value has dropped to $90. Then, by T 3 , the net asset value of a share has again risen back to its starting point, $100. In this illustration, investor I 1 purchases one share at T 1 , and investor I 2 purchases one share at T 2 . However, even though the net asset value is $90 at T 2 , I 2 does not simply pay $90 for one share at T 2 , since if he did so, there would be a potential non-uniformity in share value at T 3 , unless the advisor for the fund agreed to waive the PF due on I 2 's share. Accordingly, at T 2 , investor I 2 is required to pay, in addition to the asset value/net asset value (which are equal at T 2 as there is no accrued PF), a DD equivalent to the PF that would be payable on a gain on I 2 's share equal to the amount of the loss carryforward for investor I 1 at T 2 (i.e., 20% of $10, or $2). At T 3 , investor I 2 's DD is used to pay the PF for I 2 's gains, while investor I 1 , who has no net gain, pays no fee. Because the DD is kept outside of the share accounting system, a uniform net asset value per share is maintained. At T 3 , after payment of the PF, the total asset value of the fund is $200, with each of investor I 1 and investor I 2 owning a single share, each share with a net asset value of $100, and each of I 1 and I 2 has paid a PF commensurate with his investment experience in the fund. [0031] There is, however, an economic loss for investor I 2 from the DD. In order to ensure its availability to pay the PF potentially due from I 2 but not from I 1, as well as that I 2 not have more at risk than I 1 having to fund the DD, the DD does not participate in the profit and loss of the fund but rather is invested in T-bills or other “riskless” short-term deposits. I 2 effectively pays the cost of maintaining a uniform asset value per share by being required to fund the non-participating DD. [0032] Another past scheme used to address the differential PF/uniform share value problem has involved the issuance of additional shares and/or the adjustment of the number of current shares held as at the end of each PF calculation period. TABLE 4 T 1 T 2 T 3 I 1 NAV $100  $108  $100  PF  0  2  0 AV 100 110 100 I 2 NAV X 108  98 [0033] Referring now to Table 4, investor I 1 purchases one share at $100 at T 1 . At T 2 , the value of the share has appreciated to $110, $2 of which is an accrued PF. By T 3 , the share has again dropped to $100, and the PF has reversed. [0034] Assume investor I 2 , acquires a share at T 2 . In this case—unlike in the EF scheme, in which I 2 would invest the full $110 asset value per share prior to any PF accrual—I 2 purchases a share at the net asset value of $108. At T 2 , the uniform net asset value per share is $108, the asset value of the fund is $218, and there is a $2 accrued PF attributable to investor I 1 . At T 3 , the net asset value of each share has preliminarily dropped from $108 to $98, a loss of $10 per share. The total asset value of the fund at T 3 is $198—the total paid for the two shares ($100 plus $108), plus the initial $10 gain, less the $20 loss, at T 3 . [0035] At T 3 , the share value is determined by that of the most recently acquired share (I 2 's), i.e., $98 per share. At T 3 , investor I 1 's total investment is $100. At $98 per share, this means that investor I 1 has a total of 1 {fraction (2/98)} shares. Investor I 2 's total investment is $98. At $98 a share, this means that investor I 2 will have exactly one share. TABLE 5 T 1 T 2 T 3 I 1 NAV $100  $90  $100  PF  0  0  0 AV 100 90 100 I 2 NAV $90  $98 PF  0  2 AV 90 100 [0036] Referring now to Table 5, investor I 1 purchases one share for $100 at T 1 . At T 2 , the asset value/net asset value per share has dropped from $100 to $90. By T 3 , the asset value/net asset value per share has recovered to its starting point, $100. Investor I 2 purchases one share at T 2 . The purchase value of that share is $90. By T 3 , his $90 share has appreciated to $100 in asset value, $98 net asset value due to the $2 accrued PF. [0037] Shares are then reallocated at T 3 . After the $2 PF is paid to the advisor by investor I 2 , the total asset value of the fund is $198. The value per share is that of the most recently acquired share, i.e., $98. Using this new value per share ($98), investor I 1 , has invested $100 and holds 1 {fraction (2/98)} shares. Similarly, investor I 2 's total investment is now $98 ($100, minus the $2 PF). At $98 a share, this means that investor I 2 holds exactly one share. [0038] The foregoing scheme, while complicated, achieves the correct result without the opportunity cost of the DD, provided that no investor acquires shares at more than one time. However, if an investor does acquire shares at more than one time, this scheme has no capability of adjusting for the fact that even though there is a profit on a later acquired tranche of shares the investor in fact should owe no PF due to counterbalancing losses on an earlier acquired tranche. In fact, each of the aforementioned schemes that involves EFs/DDs, as well as that involving the revaluation and issuance of new shares (sometimes referred to as “equalization shares”), are blind to subsequent investments by existing investors. By way of contrast, in partnership accounting the investor who acquires an investment interest at more than one time is equitably treated. He is not subject to a PF until his overall investment is profitable. In the equalization share method, if I 1 and I 2 were the same investor, the net asset value per share would still be calculated as if a PF were due on the increase in the value of the share acquired at T 2 . However, there should be no such PF until the loss carryforward with respect to the share acquired at T 1 , had been earned back. The aforementioned schemes have the common failing of tracking PF by tranche of share, not by investor. [0039] When analyzing multiple investments by a single investor, it is important to recognize that in a partnership accounting system, investments are typically tracked person-by-person, rather than by investment-by-investment. One reason for this is simply illustrated. TABLE 6 T 1 T 2 T 3 I 1 Series A $100 $90 $95 Series B $90 $95 [0040] Referring to Table 6, a single investor (investor I 1 ) invests in the same fund at two different points in time, T 1 and T 2 . At T 1 , the value of a share is $100. At T 2 , the value has fallen to $90 a share, and by T 3 , the share value has risen back to $95. Referring to investor I 1 's first purchase as “Series A” stock, and referring to his second investment as “Series B” stock, if these investments were treated separately, the advisor would be entitled to a PF on the Series B stock, which had appreciated from $90 to $95 (at a 20% PF, this fee would equal $1). However, overall, investor 11 has merely broken even, since his Series A stock has actually decreased in value. Under this scenario, tracking investment-by-investment rather than investor-by-investor is inequitable to investor I 1 . SUMMARY OF THE INVENTION [0041] The problems of (i) accounting for the possibility of multiple investments by the same investor, (ii) equitably allocating PFs, (iii) maintaining a uniform asset value per share, and (iv) avoiding economic loss for the advisor (the “loss carryforward free ride”) or the investor (the DD) are all addressed by the present invention. [0042] In order to ensure equitable treatment of each investor in all investment fund performance scenarios, it is necessary to track accrued PFs, loss carryforwards, and the like, investor-by-investor, rather than investment-by-investment. The art, as described above, does not do so. The invention does, while also maintaining a uniform asset value per share. [0043] The first embodiment of the present invention is a computer implemented accounting system which permits investment sponsors to maintain the uniformity and fungibility of the shares acquired by different investors while equitably allocating differential fees and credits among such investors. [0044] By preserving the fungibility of the shares despite material differences among the fees and credits applicable to various shareholders, the invention permits private investment funds to accommodate numerous different investors, make individualized arrangements with all or substantially all the investors while, nevertheless, maintaining wholly uniform and fungible shares. [0045] Another embodiment of the present invention is an accounting system which permits maintaining different categories of an individual shareholder's shares, without differentiating among the shares designated to each of these different categories. This permits accounting for each individual shareholder's overall shareholding as itself being subdivided into shares subject to different redemption and other terms (“categories” being the term used herein to refer to shares subject to such different terms), while maintaining the fungibility of such shares and obviating the need to identify specific shares as belonging to specific categories. By tracking the categories solely as bookkeeping entries, the present invention permits shares to be redeemed, transferred, etc., against the bookkeeping balance in a category without any share itself having to be identified to or incorporating the characteristics of any given category. [0046] The present invention can enable fund sponsors to maintain uniform and wholly fungible shares despite a wide range of differential variables applicable to the shares held by different shareholders as well as by each individual shareholder. BRIEF DESCRIPTION OF THE DRAWINGS [0047] For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings. [0048] [0048]FIG. 1 is a schematic representation of the first embodiment of the apparatus of the present invention. [0049] [0049]FIG. 2 is a schematic illustration of a method of the present invention as implemented in a software flow diagram, whereby the realizable value (or net asset value) of the investment held by each investor in a fund is calculated. [0050] [0050]FIG. 3 is a sequential flow diagram as used in software illustrating the recomputation and reallocation of shares to individual investors upon the occurrence of a realization event. [0051] [0051]FIG. 4 is a schematic representation of the second embodiment of the present invention. [0052] [0052]FIG. 5 is a schematic representation of the method of a second embodiment of the present invention implemented in a software flow diagram, wherein a given investor's shares are divided into different categories, and wherein redemptions, transfers, debits, credits, or the like are attributed to the various categories of shares held by such investor pursuant to a predetermined formula. DETAILED DESCRIPTION [0053] The present invention consists of a system of accounting for all shares on an “asset value” basis—i.e., a value unreduced by differential fees and credits—while confining the differential fees and credits applicable to different investors to agreements extraneous to the fund's accounting system. By divorcing share value accounting from the differential fees and credits—as well as from different categories of shares held by the same investor in the second embodiment of the invention—the present invention easily permits a single series of shares of equal asset value to be held by all investors. Multiple classes or series may also be issued if necessary or desirable for regulatory or other reasons, in which case the uniformity and fungibility of the shares is maintained within each such class or series. [0054] A net asset value monitor tracks the differential fees and credits on an investor-by-investor basis. This system generates a balance due from or to each shareholder which reduces or increases the realizable value of such shareholder's overall investment, i.e., the net asset value of such investment. However, all differential fees and credits are extraneous to the asset value per share, which by definition does not reflect any such fees and credits. The asset value per share of all shares is the same; however, investments held by two different shareholders with the same number of shares can have materially different realizable (net asset) values. The net asset value monitor also tracks whether the same investor has purchased shares at more than one time. If so, the net asset value monitor calculates differential fees and credits based on the shareholder's overall investment in the fund, not on the basis of the different tranches of shares acquired at different times (as in the other methods of accounting, using EFs/DDs and equalization shares, outlined above). Consequently, even immediately after a tranche of shares is issued, the realizable value (net asset value) of such shares in the hands of one investor may differ from such value in the hands of another investor, although all shares are fungible on an asset value basis. [0055] Each time share cancellations are generated by the net asset value monitor, a signal is sent to the fund's periodic reporting system to disclose the cancellation—both by dollar and share amount—to the affected investor in the immediately following periodic investor report. [0056] By storing differential fees and credit data by individual shareholder identifiers, the net asset value monitor is able to accommodate any number of different sources of differential fees and credits for different investors, as well as interim changes and adjustments to such differential fees and credits, while entirely insulating the value per share accounting from these individualized inputs. Consequently, fund sponsors are given the added flexibility that these inputs may be modified or eliminated from time to time without impacting the fund's valuation systems. [0057] The second embodiment of this invention permits an investor's shares to be divided into different categories for a variety of different functions, for example, for purposes of determining when the shares can be redeemed. These categories may be individualized to each investor or may be common among different groups of investors. A category allocator distributes the differential characteristics among the different categories for purposes of achieving the share differentiations for which the categories have been developed, and signals the fund's periodic reporting system to communicate this information to investors in the immediately following periodic investor report. As a final step, the category allocator distributes the asset value of the individual investor's shares among the different categories so that the sum of the asset value of the categories equals the asset value of the investor's overall shareholding. In addition, the distribution of asset value among the different categories permits the calculation of the number of shares of each category which must be cancelled or acquired when an event occurs causing the differential fees and/or credits maintained in the net asset value monitor to become due. The category allocator has the capability of maintaining the fungibility of all shares while also maintaining material distinctions among the categories. Individual shares are not identified to a category; rather, shares are redeemed, transferred, etc., as debits or credits against the bookkeeping balances in such categories. The uniformity of the shares irrespective of the materially different categories to which a shareholder's overall investment is distributed is consistent with the calculation of differential fees and credits on the basis of a shareholder's overall investment, not share by share. [0058] Both embodiments of the present invention are capable of incorporating a wide range of different variables. The functionality of the present invention is independent of the type or number of these variables. [0059] [0059]FIG. 1 illustrates a first embodiment of the apparatus of the present invention. Included in the apparatus are a stored data 125 and processing modules 127 . The general market inputs 101 are not part of the apparatus, but rather are data relating to the performance of the investment fund which is utilized by the apparatus. Processing modules 127 comprise at least three aspects. First is an asset value monitor 102 . The asset value monitor is used to determine the total asset value of the fund at a given point in time. Also included in the processing modules 127 is a net asset value monitor 105 . The net asset value monitor 105 tracks and computes the net asset value of each investor's investment based on the performance of the fund as a whole. Also included in the processing modules 127 is a registrar 103 . The registrar 103 performs various functions, including the computation of the total investment value for a given investor, as well as the realizable value (or net asset value) for each individual investor. It should be apparent that the important aspect of processing modules 127 is their ability to compute and track the various information discussed herein. It is not essential that the various functionalities be separated into the various subcomponents listed herein. [0060] The apparatus also contains a stored data 125 . The stored data 125 includes information relating to the investment fund as a whole 120 . This information would include data such as the total number of outstanding shares in the fund, total capitalization of the fund, and the like. In addition, stored data 125 also includes information on each of the specific investor's investments 104 . This individual investor information 104 would include data such as the number of shares owned by a particular investor, when each of those shares was purchased, and the like. As discussed previously, the stored data 125 and processing modules 127 operate using general market inputs 101 to perform the various steps of the methods of this invention. [0061] Referring now to FIG. 2, FIG. 2 is a flow diagram of the method of the first embodiment of the present invention. Although the steps do not have to be performed in this order, the order discussed herein is the preferred embodiment. The first step 501 is to monitor the general market inputs. After monitoring these inputs, such as the value of the various holdings of the fund and the like, the next step 505 determines the total value of the fund's portfolio. Next, using the total value of the fund just determined, in conjunction with the value representing the total number of outstanding shares 202 in the fund, step 507 determines the asset value (i.e., not altered by differential fees or credits) per share. This value can then be reported to stock exchanges, individual investors and others. Once the asset value per share has been determined at step 507 , the next step 509 is to determine the asset value of each investor's shares. This is determined by using information on each investor's investments 104 , such as the number of shares 204 held by each investor. [0062] As a separate, parallel functionality, the method of the present invention at step 520 also tracks information specific to each investor's investments 520 using the general market inputs 101 and the information on each investors investment 104 . Using this information, the next step 522 is to determine the differential fees or credits, if any, owed by or to each investor. Using the value of the fees and credits determined in step 522 in conjunction with the total asset value of each investor's shares determined in step 509 , the next step 511 is to determine the net asset value, or realizable value, for each investor. In this way, the true value of the investor's investment to that investor is determined by subtracting out the fees and adding the credits to the total asset value of his shares. [0063] [0063]FIG. 3 illustrates the additional steps of the present method which are performed upon the occurrence of a realization event 601 . Note, however, that the steps outlined in FIG. 2 also need not be performed until the occurrence of the realization event 601 . However, upon occurrence of a realization event, and assuming that the process has proceeded through step 511 , namely the determination of the net asset value for each investor 650 , that value is used in conjunction with the value per share 652 which was determined in step 507 , to determine at step 610 the new number of shares held by each investor. As before, not all of these steps need be performed in a particular order, unless the value from the previous step is required to perform the subsequent step. Next, the number of shares which should be cancelled from or added to each investor, if any, is determined at step 612 . For each investor owing a PF, the number of such investor's shares to be cancelled to provide for the payment of such PF is known, and such shares shall, in face, be cancelled to provide for the payment of the PF (accrual) at step 616 . For each investor entitled to a credit, step 614 provides for the allocation of new shares to be issued to such investor. [0064] [0064]FIG. 4 is a schematic representation of the apparatus of a second embodiment of the present invention. Note that, as with the first embodiment illustrated in FIG. 1, the second embodiment also comprises a stored data 125 and processing modules 128 . Note also, that the processing modules 128 of the second embodiment also include a category allocator 301 . As before, the various elements contained within the processing modules 128 designate functionalities rather than separate mechanisms. As such, the invention is intended to encompass an apparatus which performs the functions described herein, notwithstanding the mechanisms or labeling of the subsystems of that apparatus. [0065] [0065]FIG. 5 shows the steps involved in the present invention which are triggered upon the occurrence of a realization event 701 . The first step 710 is to determine the net asset value for each individual investor. Note that this can be accomplished in much the same way as the steps leading up to step 511 illustrated in FIG. 2. Following step 710 , in step 712 the cancelled shares are applied toward the payment of any PFs (fees/accruals) that may be due. Finally, in step 714 , the remaining shares, i.e., those not applied toward the payment of PFs, are redistributed among the various categories of shares held by the investor. This redistribution or reallocation can be performed by any input or predetermined method, and can be included among the information on each investor's investments 104 contained in stored data 125 . As before, the methods can also contain the additional step of reporting the new number of shares in each category to each investor (not shown). The categories may be distinguished from each by any number of different characteristics as the fund manager may determine. [i would strike the “or additional” from box 714 ] [0066] The present invention achieves the objective of maintaining entirely fungible and uniform shares in a fund, while permitting virtually infinite variety in the terms applicable differentially to each investor's investment in such fund, by tracking such different terms outside of the share asset value accounting system and then combining such tracking with a share asset value accounting system which maintains such entirely fungible and uniform shares. EXAMPLE 1 [0067] [0067] TABLE 8 T 1 T 2 T 3A T 3B Uniform Asset $100 $110 $110 $110 Value per Share I 1 Shareholding 1 1 1 108/110 I 2 Shareholding 0 1 1 1 [0068] In Example 1 (Table 8) of the present invention, two investors each purchase one share in the same fund at different points in time. By monitoring general market inputs (FIG. 2, step 501 ), the total value of the fund can be determined (FIG. 2, step 505 ), and from that the asset value per share can be determined (FIG. 2, step 507 ). In this example, the asset value per share is determined to be $100 at T 1 , $110 at T 2 , and $110 at T 3 (note that T 3A refers to the time just prior to a realization event, and T 3B refers to the time immediately following the realization event). Investor I 1 purchases one share for $100 at T 1 , while investor I 2 purchases one share at T 2 , at which time the share asset value is $110. Again, these numbers are asset value figures, not net asset value figures. By T 3 , the asset value per share has held steady at $110 each. [0069] Under the method of the present invention, a separate accounting is kept (FIG. 2, step 520 ), and at T 3 , the system recognizes that investor I 1 owes $2 in PFs, and that investor I 2 owes nothing (FIG. 2, step 522 ). Therefore, at the beginning of the next period, represented as T 3B , assuming a realization event has occurred between T 3A and T 3B (FIG. 3, 601), this method cancels shares of investor I 1 in payment of the PFs due at T 3 (FIG. 3, step 612 ). In this case, at T 3B , investor I 1 's total investment, after deduction of $2 of PFs, is $108. With a $110 share value, investor I 1 holds {fraction (108/110)} of a share (FIG. 3, steps 610 and 614 ). Similarly, investor I 2' s total investment is $110, since he has paid no PFs. At $110 a share, investor I 2 thus holds exactly one share. The {fraction (2/110)} share cancelled from investor I 1 is then applied toward the payment of the $2 accrued PF (FIG. 3, step 616 ). EXAMPLE 2 [0070] [0070] TABLE 9 T 1 T 2 T 3 T 4A T 4B Uniform Asset $100 $90 $90 $95 $95 Value per Share I 1 Shareholding 1 1 1 1 1 I 1 loss 0 10 10 5 5 carryforward I 2 Shareholding 0 1 1 1 94/95 I 2 loss 0 0 0 0 0 carryforward [0071] The example shown in Table 9 demonstrates another feature of the present invention. Importantly, the cancellation of shares does not occur until a realization event, in this case, a payment of PFs. Accrued fees, as opposed to fees when paid, do not affect the share accounting system, but rather are stored in the individual investor identifier systems. This is appropriate because until an accrued PF is actually due, the amount of the accrual still represents investor assets at risk and should be included in making the fund's accounting allocations. In the example illustrated in Table 9, the asset value per share at T 1 is $100, at T 2 is $90, at T 3 is $90, and at T 4 is $95. Again, T 4A and T 4B refer to times immediately prior to, and immediately subsequent to, the realization event, respectively. They are separated to show the difference in shareholdings before and after the realization event. Investor I 1 purchases one share at T 1 , while investor I 2 purchases one share at T 2 . At T 4A , investor I 2 has a net gain of $5, and thus owes a $1 PF to the advisor (again, assuming a 20% PF). However, the asset value of both I 1 's and I 2 's share is a uniform $95. The individual investor identifier system, however, recognizes that investor I 1 has a net loss of $5 since the inception of his investment. Under these circumstances, investor I 1 has a $5 loss carryforward. Therefore, if a PF realization event occurs at T 4 , investor I 1 retains one share at a $95 asset value. Investor I 2, however, has a total investment of $94, and has $1 worth of asset value shares cancelled to pay the $1 PF owed by I 2 . At $95 a share, this means that investor I 2 will retain {fraction (94/95)} of a share. EXAMPLE 3 [0072] [0072] TABLE 10 T 1 T 2 T 3 T 4A T 4B Asset Value $100 $90 $90 $100 $100 per Share I 1 Shareholding 1 2 1 1 99/100 I 1 loss 0 $10 $5 $5 0 carryforward I 1 accruals (at 0 0 0 $1 ($(10-5) × 0 20%) 20%) I 2 Shareholding 1 1 1 1 1 I 2 loss 0 $10 $10 0 0 carryforward I 2 accruals (at 0 0 0 0 0 20%) [0073] The example shown in Table 10 demonstrates how the method of the present invention can successfully track multiple investments by multiple investors. In the example illustrated in Table 10, the asset value per share at T 1 , is $100, at T 2 is $90, at T 3 is $90, and at T 4 is $100. For purposes of Example 3, assume that investor I 1 purchases one share at T 1 , and a second share at T 2 . Assume further that investor I 1 redeems his second share at T 3 . Investor I 2, on the other hand, purchases one share at T 1 , and does not redeem it. [0074] Upon redemption of a share at T 3 , investor I 1 loses one-half of his loss carryforward according to typical fund accounting practices, since he has redeemed one-half of his investment (one out of two shares). Therefore, beginning at T 3 , investor I 1 's loss carryforward is $5, although the asset value of his single remaining share is $10 below the purchase price at T 1 , of $100. Thus, at T 4A (immediately prior to the realization event), investor I 1 has gained $10, and has only a $5 loss carryforward, thus yielding a net increase subject to the PF of $5. Assuming a 20% PF, investor I 1 owes $1 to the advisor. [0075] According to the present invention, investor I 1 's investment in the fund at T 4B (after occurrence of the realization event) is $99 ($100, minus the $1 PF). At an asset value of $100 a share, investor I 1 retains {fraction (99/100)} share at T 4B . As for investor I 2 , he still has a $100 stake in the fund at T 4B . Therefore, at $100 a share, he owns exactly one share at T 4B . [0076] The present invention can be modified to adopt to any manner of PF (or other) calculations, irrespective of how many times, or in what patterns, an investor invests, redeems and reinvests in a fund. EXAMPLE 4 [0077] [0077] TABLE 11 T 1 T 2 T 3A T 3B Asset Value Per $100 $110 $110 $110 Share I's share 1 2 1 1* holdings I's loss 0 0 0 0 carryforward I's accruals (at 0 $2 $1 $1 20%) #109/110 share at T 3B . [0078] Table 11 illustrates another example of an investor buying shares at two different times in the same fund in accordance with the present invention. In this case, referring to Table 11, the asset value per share is $100 at time T 1 , $110 at T 2 , and $110 at T 3 (Note that T 3A refers to the time just prior to a realization event, and T 3B refers to the time immediately following this realization event). The investor purchases one share at T 1 and retains it. That same investor purchases another share at T 2 , and redeems it at T 3 . [0079] The PF accrued by this investor at T 3 is $2 (20% of the $10 increase experienced by the first share he purchased). Since the investor has redeemed half of his shares, according to typical fund accounting practices, he owes half of the PF (½×$2=$1), even though there is no gain whatsoever on the share purchased at T 2 . In this case, after payment of the $1 PF from the $110 redemption proceeds, the investor's total net assets in the fund are $109, one $110 asset value share, less the remaining $1 accrued PF. Alternatively, the present invention can be adjusted so that the redemption proceeds of $ 110 are paid out and an additional fractional share canceled to pay the PF, with the investor retaining {fraction (109/110)} share. [0080] Note that despite the number of shares held by an investor being subject to change, under the present invention the change in the uniform asset value per share from T X to T X+1 correctly reflects the performance of the fund, gross of PFs, for such period. [0081] An embodiment of the present invention which relates to the attribution of the shares held by a single investor or a plurality of investors to different categories (which could reflect a wide variety of possible variables) addresses the problem of distributing among such categories quantities—such as PF accruals or reversals—which apply not category-by-category but investor-by-investor. There is a fundamental discontinuity between a quantity calculated on the basis of a shareholder's overall investment in a fund (for example, PFs) and categories which potentially are, by definition, only a portion of such overall investment. [0082] For example, assume that a fund offers shares that are redeemable either quarterly or annually and that the same investor may hold both types. Problems generally analogous to those which arise under the EF/DD and/or “equalization share” schemes when the same investor purchases shares at multiple times arise in the case of different categories of shares acquired by the same investor at different times (in this case quarterly and annual redemption shares). Assume an investor is holding annual shares on which PFs have accrued at the time that the same investor acquires quarterly redemption shares. If the fund subsequently has neither profits nor losses, and the quarterly shares are redeemed prior to the end of the current PF calculation period, part of the PF accrued on the annual shares will become payable. This creates the accounting issue of whether payment of that PF should reduce the number of annual shares and/or quarterly shares held by the shareholder or the proceeds of the quarterly redemption. Analogous attribution issues arise if annual shares are redeemable at different anniversary dates since, among other things, one must decide from which category (or subcategory), if any, of annual redemption shares should shares be cancelled to pay the PF. [0083] Any accounting system which attempts to track categories into which an individual shareholder's investments are divided separately while also applying certain quantities, e.g., PFs, on the basis of the shareholder's overall investments will in certain scenarios be required to make allocations contrary to those which would be made to any individual category considered in isolation. The present invention resolves this problem by accounting for the categories not as independent subsets of an investor's shareholding to which specific shares are identified, but rather as pro rata percentages of such shareholding. EXAMPLE 5 [0084] [0084] TABLE 12 T 1 T 2 T 3 T 4A T 4B Uniform $100 $110 $110 $110 $110 Asset Value per Share No. Annual Shares 2 2 2 2 1.976 No. Quarterly Shares 0 1 0.5 0.5 0.494 [0085] Example 5 (Table 12) illustrates a second embodiment of the present invention. In this hypothetical, the asset value per share is $100 at T 1 , $110 at T 2 , $110 at T 3 , and $110 at T 4 . At T 4 , a realization event occurs (the payment of PFs). T 4A represents the status of the investor's shares just prior to occurrence of the realization event, while T 4B represents the status of the investor's shares immediately following the realization event and reallocation of shares according to the present invention. [0086] In this example, an investor purchases two annual redemption shares for $100 each at T 1 . By T 2 , these shares have an asset value of $110 each. At T 2 , the investor purchases one quarterly redemption share (which of course also has an asset value per share of $110). At T 3 , the investor redeems ½ of a quarterly share. One-half of the quarterly share has an asset value of $55 ($110×½ =$55). At T 3 , the investor's total gain on his investment is $20 ($10 on each of his two annual shares, purchased at T 1 ). Therefore, the total accrued PF at T 3 , assuming again a 20% PF, is $4 ($20×20%=$4). Since the investor has redeemed ⅙ of his total investment (½ share out of 3 shares total), he only owes ⅙ of the accrued PF upon his redemption of ½ of a quarterly share. Thus, the investor owes $0.67 in PFs at T 3 ($4×⅙=$0.67). In this example, this amount is assumed to be paid out of redemption proceeds. [0087] As mentioned previously, a realization event then occurs at T 4 , namely the payment of the accrued PF to the fund manager (FIG. 5, 701). As a result, the investor's shares must be redistributed between the two types of shares he holds, annual and quarterly shares (FIG. 5, step 714 ). At T 4A , the investor's total asset value is $275 (2.5 shares×$110share). Since the asset value per share has not changed from T 3 to T 4 , the investor's total gains are still $20. However, the investor has already paid $0.67 of the $4 PF owed on this $20 gain. Thus, at T 4A , the investor owes $3.33 in PFs ($4−$0.67 =$3.33). Therefore, after the payment of accrued PFs (i.e., at T 4B ), the investor's total investment will be $271.67 ($275-$3.33) (FIG. 5, step 710 ). The $3.33 will be paid through the cancellation of shares (FIG. 5, step 712 ). [0088] According to this embodiment of the present invention, the $271.67 must then be allocated between the investor's two different types of shares. Just prior to the realization event (i.e., at T 4A ), the investor had 2 annual redemption shares and ½ of a quarterly redemption share. Thus, ⅘ of his investment was in annual redemption shares, and ⅕ of his investment was in quarterly redemption shares. In this example, these percentages should remain constant after occurrence of the realization event. Therefore, at T 4B , the investor should be reallocated annual redemption shares worth $217.34 (⅘×$271.67) and quarterly redemption shares worth $54.33 (⅕×$271.67). With an asset value per share of $110, the investor is thus allocated 1.976 annual redemption shares ($217.34÷$110 share) and 0.494 quarterly redemption shares ($54.33 ÷$110/share). [0089] Combining the first and second embodiments of the present invention creates a highly flexible, multi-dimensional accounting system which can accommodate virtually any permutation of both (i) investor versus investor differentials and (ii) differential characteristics defining different subsets of each individual investor's own shares—all in a computerized, fully-automated functionality which maintains wholly fungible and uniform shares at all times, without path dependence with respect to either the pattern of fund performance or of investors' subscriptions. [0090] The examples contained herein are merely illustrative of the invention as a whole, and are not intended in any manner to limit the scope of the claimed invention. As should be clear to any person of ordinary skill in the art, numerous modifications could be made which would still be encompassed by this invention.

A method for maintaining a uniform asset value per share and complete fungibility among all shares in investment funds while providing for differential fees and credits, as well as any other factors which may be differentially applicable to different investors, separately in respect of each investor. The method also permits accounting for a single investor's shares to be classified into different categories in respect of such factors as redemption rights or fees due, while maintaining a complete fungibility among such shares so that it is not necessary to identify any particular shares as belonging to any specific category. The present invention also makes it possible to program a single accounting method for both domestic investment funds organized as partnerships, typically not classifying investments in such entities into any uniform quanta, and offshore investment funds organized as corporations, trusts or other entities, typically classifying investments in such entities into uniform quanta such as shares or units.

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] The present invention is a Continuation Application of U.S. Non-provisional application Ser. No. 13/920,753, titled APPARATUS AND METHOD FOR IMPLANTATION OF DEVICES INTO SOFT TISSUE filed on Jun. 18, 2013 which claims the benefit of U.S. Provisional Application Ser. No. 61/690,044 filed Jun. 18, 2012, which is incorporated by reference herein. STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT [0002] This invention was made with partial government support under DARPA grant N660011114025. The government has certain rights in this invention. FIELD OF THE INVENTION [0003] The invention relates to apparatus and methods for the surgical implantation into soft tissue of devices, such as (1) prosthetic neural interfaces between computers and the machinery they control and biological tissue, for example neurons and the nodes of Ranvier on axons in nerve bundles, (2) optical fibers for the localized stimulation of neurons and other cell types, and (3) drug delivery catheters, among others. The micrometer-scale interfaces being surgically implanted can be used for recording from the soft tissue in which they are embedded or stimulating the soft tissue in which they are embedded. The invention relates to the accurate and minimally invasive placement of prosthetic micron-scale implants at a predetermined depth, location and orientation based on the profile of the tissue, for example the vasculature of the brain, and the use of implantation-specific data like soft tissue compression force prior to penetration and frictional force between the micrometer-scale implant and the tissue after penetration to optimize final placement of the interface. The invention relates to the use of ultrasonic oscillatory motions superimposed on the main trajectory to tailor the trajectory of the implantation to realize the reduction in insertion forces and soft tissue compression, which prevents effective insertion and increases tissue damage. The invention relates to the use of multi-unit cartridges for the implantation of multiple micrometer-scale interfaces during a single surgery without retooling, to reduce surgery time and minimize the handling of the prosthetic interfaces. The invention also relates to precise control of insertion speed, and tools for visual and sensor-based inspection of insertion characteristics such as initial tissue contact and forces during insertion. BACKGROUND OF THE INVENTION [0004] Many implantable devices that interact with tissue, including those used in surgical procedures, in-vitro tests, and in-vivo implantations, require special care for accurate positioning (location and orientation) of the implantation device. Furthermore, a critical issue is to ensure that implantation occurs satisfactorily; that is, the device is inserted in at the required depth without device failure. Manual insertions of devices cannot provide this level of control in positioning and insertion, therefore leading to high rate of device failure during insertion, over-design of devices with larger-than-needed foreign materials, and functional failures. An important need is to have automated mechanisms for insertion, that provide precision in positioning (cellular-scale, approximately 20 μm), orientation (±0.5°), and speed control (±1%), as well as allow feedback and evaluation through visual and sensor-based in-situ characterization capability. [0005] An illustrative example of this need arises from the insertion of the neural probes for brain-computer interfaces (BCI). Research on BCI and brain-machine interfaces (BMI) in recent years has demonstrated the feasibility of driving motor prostheses for the upper limbs of amputees and for restoring mobility to quadriplegics and tetraplegics whose condition arose due to injury or disease. More recently, research has begun to focus on providing feedback loops between the brain and other nervous tissue and the computers and machines to which they are interfaced by stimulating the tissue with signals from the external equipment to return sensation to BMI and BCI recipients. In this way, an injured or diseased individual can control an external prosthetic and receive sensation from it in a way that naturalistically mimics the limb they lost or the biological function that is impaired. [0006] BCIs and BMIs comprise: 1. an interface to the soft tissue that records the electrical, chemical or mechanical activity of the soft tissue and transduces it to a signal in a suitable energy domain, typically electrical, 2. a decoder that extracts the information from the signals received from the tissue, 3. a transmitter that sends out the decoded signals, 4. a receiver of the decoded signal, 5. a computer or machine that acts under the instructions carried in the decoded signals, 6. a sensor array that detects changes in the environment caused by the action of the computer or the machine and transduces it to a signal in a suitable energy domain, 7. an encoder that receives the output of the sensor array and converts it to a sensory signal for transmission, 8. a transmitter that sends out the encoded sensory signals, 9. a receiver of the encoded sensory signals, and 10. an interface that transduces the encoded sensory signals to an electrical, chemical or mechanical signal for stimulation of the soft tissue in which the interface is embedded. [0007] The interface is a critical feature of BMIs and BCIs and its placement must be as close as possible to the biological signal sources without damaging them in order to maximize the information extracted from the soft tissue and minimize the amount of energy needed to transmit sensory information back into the soft tissue. The most common interface is the electrode. Typically, this is an insulated, electrically conductive material with a small surface exposed to the soft tissue environment. Electrodes have dimensions ranging from 10 s of micrometers to 100 s of micrometers. The effectiveness, stability and reliability of these interfaces has been identified in the literature, in part, as dependent on the method of implantation and the accuracy of their placement. Interface reliability is a critical research area where progress is needed prior to transitioning BMI and BCI technology for practical restoration of motor and sensory functions in humans. Two key issues are 1) the inability of current interfaces to reliably obtain accurate information from tissue over a period of decades, and 2) currently measured signals from tissue cannot be reliably used to control high degree-of-freedom (DOF) prostheses with high speed and resolution. [0008] Failure of biological soft tissue interfaces may be caused by several issues. After implantation, current probes are surrounded by reactive microglia and reactive astrocyte scarring as shown pictorially in FIG. 1( a ) . In the brain, damage to the neural vasculature causes a breach in the blood-brain barrier (BBB) that is associated with reactive soft tissue responses. Tissue reaction with the probe results in encapsulation that insulates the electrode by impeding diffusion of chemical and ionic species and may impede current flow from the soft tissue to the interfaces. Encapsulation increases the distance of the electrode from active neurons. For viable recording, the distance of the electrode from active neurons must be less than 100 μm. Progressive death and degeneration of neurons in the zone around the inserted probe due to chronic inflammation may eliminate neural electrophysiological activity. Lastly, interconnects may fatigue and break due to stresses. Experiments in animals have resulted in some neural electrode sites failing while others keep working for several years. This variability in outcome is believed to be due to several factors including variable BBB damage, variable scar formation, mechanical strain from micromotion, inflammation, microglial condition and disconnected neurons. [0009] Tissue interfaces employed today for BMI and BCI applications come in a variety of shapes made of many materials and apparatus and methods for implanting these interfaces must have the functional and design flexibility to handle the multiplicity of devices available today and accommodate the designs and forms that become dominant as the technology matures and moves into widespread human use. In the next few paragraphs, the challenge presented by the range of device types and materials will be established by reviewing the devices described in the literature. [0010] Historically, the interfaces have been stiff needles usually made from wires, silicon or glass. Metal wire neural probes are typically 50-100 μm in diameter and usually made of platinum or iridium and insulated with glass, Teflon, polyimide or parylene. [0011] Silicon-mounted interfaces made with MEMS fabrication were first introduced by Ken Wise and Jim Angell at Stanford in 1969. Ken Wise's group at the University of Michigan subsequently developed a series of silicon probes and probe arrays with multi-site electrodes. [0012] A 2D probe array was developed at the University of Utah in 1991, known as the Utah Electrode Array (UEA). The UEA has become a favored interface in human applications in the central nervous system (CNS) and for research in the peripheral nervous system (PNS). [0013] Polycrystalline diamond (poly-C) probes with 3 μm thick undoped poly-C on a ˜1 μm SiO 2 layer have been fabricated by Dr. Aslam's group at Michigan State University. [0014] Research groups have created more compliant probes made with thin-film wiring embedded in polymer insulating films. Flexible CNS probes have been made in polyimide, SU 8 /parylene and all parylene. These probes are still extremely stiff in both axial and transverse directions relative to brain tissue, which has a Young's modulus of approximately 30 kPa. Any axial force transmitted through the external cabling directly acts on the probe and creates shear forces at the electrode-tissue interfaces. Such forces may come from external motion or from tissue growth around the implant. To address this issue, a group from Carnegie Mellon University and the University of Pittsburgh have developed a parylene-coated Pt probe with a thickness of 2.5 μm and width 10 μm that provides axial strain relief in the brain through a meandered design ( FIG. 1( b ) ). The cables external to the brain are also meandered to further reduce transmission of brain-skull relative motion to the embedded probe. Because of the size and compliance of the meandered probes they are embedded in a biodissolvable delivery vehicle which provides the stiff structure for implantation. [0015] A team from Drexel Univ., the Univ. of Kentucky and SUNY created ceramic-based multisite microelectrode arrays on alumina substrates with thickness ranging from 38 to 50 μm, platinum recording sites of 22 μm×80 μm, and insulation using 0.1 μm ion-beam assisted deposition of alumina. [0016] Y.-C. Tai's group at Caltech produced parylene-coated silicon probes with integral parylene cabling, shown in FIG. 2( a ) . The shanks were up to 12 mm long. A primary innovation was a flexible 10 μm-thick, 830 μm-wide, 2.5 mm-long parylene cable. [0017] Flexible polyimide probe arrays ( FIG. 2( c ) ) have been made with gold electrodes. These probes must be inserted by first creating an insertion hole with a scalpel or needle. A later polyimide probe array incorporated silicon for selected locations along the length of the shank, with polyimide connectors to create enhanced compliance, as shown in FIG. 2( b ) . [0018] An innovative all-polymer probe design incorporated a lateral lattice-like parylene structure attached to a larger SU8 shank to reduce the structural size close to the electrodes. The lattice structure, shown in FIG. 2( e ) , included a 4 μm-wide, 5 μm-thick lateral beam located parallel to the main shank. Encapsulating cell density around the lateral beam was reduced by one-third relative to the larger shank. While the structure was non-functional, it is presumed that placing electrode sites on the smaller beam would result in superior recording performance. [0019] U.S. patent application 20090099441 from Dr. Giszter's Drexel group describes biodegradable stiffening wires 1 braided with electrode wires 2 (see FIG. 2( f ) ) where flexible wires 2 are braided onto a maypole structure 4 with stiff biodegradable strands 1 . When the biodegradable strands 1 dissolve, the flexible wiring 2 is left in the brain tissue. These braided composite electrodes are similar in spirit to present invention. However, reliable and manufacturable connections to the braided wires become difficult when scaled to arrays. [0020] Olbricht et al has reported on flexible microfluidic devices supported by biodegradable insertion scaffolds for convection-enhanced neural drug delivery. The device consists of a flexible parylene-C microfluidic channel that is supported during its insertion into tissue by a biodegradable poly(DL-lactide-co-glycolide) (PLGA) scaffold. The scaffold is made separately by hot embossing the PLGA material into a mold. [0021] Tyler et al, have developed a neural probe made from a polymer nanocomposite of poly(vinyl acetate) (PVAc) and tunicate whiskers, inspired by the sea cucumber dermis. The probe material exhibits a real part of the elastic modulus (tensile storage modulus) of 5 GPa after fabrication. When exposed to physiological fluid conditions, its modulus decreases to 12 MPa. [0022] The trend in devices is towards more compliant materials and structures that will have stringent implantation requirements in terms of speed, force and placement. In the following paragraphs, the state-of-the-art in soft tissue interface insertion technology is described. [0023] Manual implantation or stereotaxic assisted implantation by a skilled surgeon is the most common method of implantation of the variety of interfaces and interface delivery vehicles described above. Manual implantation means the procedure is done by hand and stereotaxic assisted implantation means it is done through the use of a stereotaxic frame that holds the interface delivery vehicle and provides a hand operated screwdrive to position and insert the interface. Positioning is usually performed with the assistance of a stereomicroscope that provides some measure of depth perception. With this technique, there is no control over the speed of insertion and only gross sensitivity to the profile of the underlying soft tissue, both of which could contribute to the variability observed in the outcomes of soft tissue interface implantations. Insertions of the Michigan probe array are done using this method. [0024] The low velocity of manual insertions, either by hand or using stereotaxic frames, results in observable soft tissue dimpling prior to penetration of the tissue. Dimpling was found to be accompanied by soft tissue compression that resulted in damage to the tissue and reduced signal extraction. [0025] To improve outcomes by reducing manual variability and increasing insertion speed, research groups adopted a hand-held pneumatic insertion device invented by Normann et al. and experimentally demonstrated by Rousche and Normann. The pneumatic inserter has a piston mechanism that is actuated pneumatically to strike an endpiece rod on which is adhered the device to be implanted. The burst of pressure accelerates the piston and its momentum is transferred to the endpiece rod which is driven toward the brain at speeds of 8 m/s, which was found to be required for the 10 electrode×1 electrode interface to penetrate the soft tissue. An adverse effect of the mechanism is recoil of the endpiece due to the return spring which can lead to retraction of the interface device if it remains adhered to the endpiece. Researchers using the UEA avoid this effect by resting the interface on the tissue into which it will be implanted and using the endpiece to strike the back of the interface device. This technique does not allow for accurate placement of the interface in soft tissue because there is no visibility of the contact points between the interface and the tissue. House et al. achieved a measure of control over the spatial relationship between the endpiece and the device to be inserted by mounting the pneumatic inserter on a stereotaxic manipulator. They found the impact between the endpiece and the backside of the interface often led to damage of the interface, so they added a “footplate” to the device. However, because the device is not mechanically connected to a fixed reference structure, it is subject to elastic recoil from the soft tissue into which it is implanted and this can lead to retraction of the interface from the tissue. To overcome retraction the interface must be over-driven into the soft tissue so that after recoil, the full length of the interface remains in the tissue. The literature does not have detailed studies on the impact of over-driving the insertion on the health of the recipient. [0026] The literature reports other insertion mechanisms of varying levels of complexity and functionality. Rennaker et al. reported a manually positioned spring-driven hammer mechanism for insertions up to 1.5 m/s for microwires mounted on the insertion device using a locking screw. Jensen et al. reported a hydraulically driven micromanipulator with manual positioning and force sensing and a speed of 2 mm/s. Dimaio and Salcudean used a robotic manipulator to implant 17 gauge epidural needles with force sensing but did not report the insertion speeds they achieved. Bjornsson et al. used stepper motors to implant Si microneedles at up to 2 mm/s with force sensing. Sharp et al. electronically controlled a micromanipulator with an in-line load cell to achieve insertion speeds from 11 μm/s to 822 μm/s for evaluation of penetration mechanics in cerebral cortex. In each of these cases and others in the literature, fine positioning, if done, was performed by visually locating the interface over the soft tissue to be implanted. [0027] Accurate placement of the interface requires referencing of the tissue height, maintaining the relative height between the interface mounted on the insertion apparatus and the tissue as the tissue surface moves under pulsatile and respiratory motion, mapping and identifying the insertion location with an overlay of the interfaces and positioning the interface in space with respect to the tissue surface. This is an area where the literature is very sparse. Kozai et at used two photon imaging to map the cortical vasculature to identify target locations prior to interface implantation and found that when this is done the trauma of implantation can be reduced by 73% for surface vasculature compared to the case when vasculature is targeted. SUMMARY OF THE INVENTION [0028] The present invention describes an apparatus and method for implanting devices into soft tissue with accuracy and precision in three dimensions as well as in prescribed insertion speed and trajectory, and reduces the damage that occurs to the soft tissue into which the device is implanted. [0029] The invention apparatus comprises several sub-systems that provide the functionality to achieve accuracy, precision and damage reduction. These subsystems are: 1. an actuator, such as the M272 piezo motor sold by PI of Auburn, Mass., that moves at a controlled high velocity along a single, longitudinal axis (i.e the implantation trajectory) with a large travel range up to 50 mm and better than 20 micron positional accuracy; 2. an actuator, such as that made from K-740 PZT by Piezo Technologies, Indianapolis, IN that can impart an oscillatory motion at frequencies between 18 kHz and 30 kHz in two directions, corresponding to the transverse directions to the insertion direction, or the single, longitudinal axis) for reduction of insertion forces; 3. a load cell, such as the Sensotec Model 31 sold by Honeywell of Morristown, N.J., that measures the force between the device being implanted and the tissue surface during implantation; 4. a contact sensor for accurate detection of the point and time of contact between the soft tissue and the device being implanted, which can be achieved by monitoring the electrical characteristics of the piezo-actuator described in subsystem 2 ; 5. a laser ranging system, like the Hokuyo URG-04LX-UG01 with a Sokuiki sensor, for referencing the position and motion of the tissue with respect to the insertion system and the device being implanted; 6. an imaging system, such as the SE-1008-400X video microscope from Selectech Electronics of Guangdong, China, for identifying the optimal insertion location to minimize mechanical damage to tissue vasculature; 7. a clamping mechanism, such as an MGP800 series clamp from Sommer Automatic of Ettlingen, Germany, to hold the device being implanted, that is operated in coordination with the actuator; 8. a set of clamping surfaces with a design that is customized to the form of the device being implanted; 9. a cartridge for holding multiple devices with a design that is customized to the form of the device being implanted; 10. a dispenser that moves devices from the cartridge to the clamp, with a design that is customized to the form of the device being implanted, or an operating sequence in which the cartridge is stationary and the actuator and clamp execute a predefined sequence to move to the next device to be implanted and pick it up in the clamp; and 11. the action of the system and its various subsystems are coordinated using software such as Labview from National Instruments of Austin, Tex. which can provide a graphical user interface for ease of use, data acquisition from the various subsystems for real-time monitoring of the insertion procedure and offline analysis for diagnostic and clinical evaluation. A software like Matlab's Image Processing module from Mathworks of Natick, Mass., can provide the capability of capturing and manipulating image data and processing them according to a variety of algorithms that identify sensitive tissue structures, overlay images of the implantation sites and compute overlap area of sensitive tissue structures and implantation sites. [0030] The method of the invention in summary is: 1. device loading; 2. device referencing; 3. implantation location identification; 4 optional surgeon final adjustment; 5. tissue height referencing; 6. implantation; 7. device release; and 8. actuator retraction. BRIEF DESCRIPTION OF THE DRAWINGS [0031] FIGS. 1A and 1B show schematics of soft tissue reactions to an implantable device in neural tissue based on its dimensions; [0032] FIGS. 2 a - f show a variety of implantable devices to illustrate the range of shapes and sizes the implantation apparatus must be capable of handling; [0033] FIG. 3 shows one embodiment of an apparatus for the implantation of devices into soft tissue; [0034] FIGS. 4A and 4B show the displacement vs. time trajectory of the device during implantation with a small amplitude ultrasonic oscillation in various planes overlaid on it; [0035] FIG. 5 shows schematic drawings of an embodiment of the apparatus with all sub-systems shown; [0036] FIGS. 6A, 6B and 6C show schematic drawings of the referencing procedure for device and tissue surface and the translation and rotation of the actuator from its initial location to its optimal location; [0037] FIG. 7A and 7B show an image of the surface of the field of view of an implantation location in the brain and a virtual representation of the implantation sites overlaid on the surface of the brain. [0038] FIG. 8 shows an open section of a cartridge for holding a number of devices in preparation for implantation; [0039] FIGS. 9 A and B show side views and face views of each side of clamping jaws used to hold the devices to be implanted; [0040] FIG. 10 is a process flow diagrams of an exemplary process of the present invention in which the device to be implanted is loaded onto an actuator and referenced for implantation into soft tissue; [0041] FIGS. 11A and 11B is a process flow diagram of an exemplary process of the present invention in which the optimal implantation location for the device being implanted is identified; [0042] FIG. 12 is a process flow diagram of an exemplary process of the present invention in which signals from force and contact sensors are used as feedback to modify the trajectory of the actuator implanting the device into tissue; [0043] FIG. 13 is a process flow diagram of and exemplary process of the present invention in which the system is operated at a high level [0044] FIG. 14 is a block diagram illustrating the interconnection and functional relationships between the components and sub-systems of the apparatus DETAILED DESCRIPTION OF THE INVENTION [0045] The present invention addresses the problem of the accurate and precise placement and depth of devices implanted into human tissue with reduced soft tissue damage. Now turning to FIGS. 5 and 14 , the present invention is an apparatus 10 279430 . 132 Con for holding, referencing, targeting, and implanting devices of various sizes, shapes and materials into soft tissue and the method that must be followed for the achievement of accuracy, precision and reduced damage using the apparatus. The apparatus 10 , by way of representation and not invention limitation, can include an actuator 12 , laser ranging sub-system 30 , contact sensor 16 , load cell 20 , imaging sub-system 28 , clamp mechanism 18 with clamp surface 22 , processor 40 , memory 42 , and display 44 for implantation of device 14 into tissue surface 32 ( FIG. 6B ) of a patient. The high level operation of the apparatus and the method for executing implantations is detailed in the process flow diagram in FIG. 13 . The step numbers are labels and are not necessarily in ordered sequence in relation to other figures, unless there is an express indication that two or more figures are related (for example, FIGS. 11A and 11B ). [0046] Step 38 : Prepare the patient surgically for device implantation by making an incision in the body and exposing the implantation vicinity in a tissue of interest. [0047] Step 39 : Position the apparatus 10 in proximity of the patient. [0048] Step 40 : Power on the apparatus 10 and configure it for the tissue type into which the device 14 will be implanted (for example, neural tissue in the brain), including entering the device implantation depth into the apparatus. [0049] Step 41 : Load the dispense cartridge sub-system 25 with the devices 14 to be implanted ( FIG. 8 ). [0050] Step 42 : Load a device 14 to be implanted into the clamp surface 22 ( FIG. 8 ). [0051] Step 43 : Reference the height D 2 of the device 14 to be implanted ( FIG. 6A ). [0052] Step 44 : Position the device 14 to be implanted above the incision that defines the implant vicinity ( FIG. 6B ). [0053] Step 45 : Locate the optimal implant location ( FIG. 7 ). [0054] Step 46 : Reference the tissue height ( FIG. 6B ). [0055] Step 47 : Implant the device 14 into the tissue surface 32 . [0056] Step 48 : Open the clamp mechanism 18 and withdraw the actuator 12 leaving the device 14 in the tissue. [0057] Step 49 : Are there more devices to be implanted? If yes, then go to back Step 42 repeat steps 42 to 49 until all devices are implanted. If no, then continue to Step 50 . [0058] Step 50 : Shutdown the apparatus 10 . [0059] Now turning to FIGS. 3, 5, and 14 , the apparatus 10 of the present invention comprises a number of sub-systems that serve particular purposes in the successful achievement of accuracy, precision and reduced soft tissue damage. Each subsystem, the function it performs and its role in the implantation method is described in detail in the following paragraphs. [0060] The implantation is achieved with an actuator 12 that moves at a controlled high velocity along a single, longitudinal axis with a variable travel range (for example, several centimeters), and high precision and accuracy in the insertion trajectory (both displacement and velocity). For example, if the device 14 is to be implanted in neural tissue, which has the most stringent placement requirements, a placement accuracy of <50 microns is necessary to ensure the correct cortical neuronal layer has been implanted. The implantation orientation is also critical and should be normal to the surface being implanted to ensure no torque is applied to the device as it is implanted. In one embodiment, an orientation accuracy of ±1° to normal is preferred in the case of micron-scale, needle-shaped devices. In one embodiment of the invention (See FIG. 3 ), the actuator 12 is a piezomotor (like the PI M272 with a maximum velocity of 200 mm/s and a force output of 8 N) but it can be substituted with a screw-drive, a stepper motor, or another actuator (linear and/or rotational) depending on the force and velocity conditions required by the device implantation. Attached to the actuator 12 is a load cell 20 for sensing the force on the device 14 being implanted during the implantation procedure, a contact sensor 16 for detecting contact between the device 14 being implanted and the referencing tab 24 ( FIG. 6A ) or the tissue surface 32 ( FIG. 6B ), and contact been the clamping mechanism 18 , that holds the device 14 , and the referencing tab 24 ( FIG. 6A ) or the tissue surface 32 ( FIG. 6B ), during the referencing and implantation procedure. The dispense cartridge sub-system 25 that holds the devices 14 prior to loading into the clamping mechanism 18 is shown in FIG. 8 as a standalone component, but could be integrated into the actuator or another part of the system. The actuator 12 in some embodiments is capable of moving with a small amplitude ultrasonic oscillation overlaid on the implantation trajectory (See FIG. 4 a ). The force of implantation of a micron-scale device 14 , like the devices that this apparatus 10 will be used to implant, can be reduced by applying ultrasonic oscillations in the range from 18 kHz to 30 kHz during implantation into soft tissue. The oscillation can be either in the direction parallel to the implantation trajectory (i.e. longitudinal), or it could be parallel to the plane of the surface of the tissue being implanted (i.e. transverse) (See FIG. 4 b ), Additional ultrasonic actuators can be added to achieve the oscillation, or the oscillation could be generated by modifying the drive signal of the implantation actuator to include, for example, an overlaid sinusoidal or step signal 12 . [0061] Attached to the actuator 12 is a clamping mechanism 18 , which can be electrically, pneumatically or magnetically driven, depending on the embodiment. In the particular embodiment shown in FIG. 3 , the clamping mechanism 18 is a Techno Sommer MGP800 series pneumatic clamp. The clamping mechanism 18 has clamping jaws 22 mounted to it that is used to hold the device 14 being implanted so that it cannot change its spatial position and orientation during referencing and targeting. The process flow of loading and referencing the device 14 to be implanted is shown in FIG. 10 : [0062] Step 1 : Initialize the apparatus 10 to bring all mechanical axes to their home position (initial horizontal and initial vertical positions); [0063] Step 2 : Move the actuator 12 to the horizontal position of the first device 14 in the dispense cartridge sub-system 25 ; [0064] Step 3 : Open the clamping jaws 19 ; [0065] Step 4 : Move the actuator 12 through the vertical distance between the actuator 12 and the dispense cartridge sub-system 25 ; [0066] Step 5 : Close the clamping jaws 19 to hold the device 14 ( FIG. 8 ); [0067] Step 6 : Withdraw the actuator 12 to its initial vertical position; [0068] Step 7 : Move the actuator 12 to the horizontal position of the height reference tab 24 ( FIG. 6A ); [0069] Step 8 : Move the actuator 12 in the vertical direction until contact between the device 14 and the reference tab 24 is detected; [0070] Step 9 : Store the vertical position at which contact with the reference tab 24 was detected; and [0071] Step 10 : Return the actuator 12 to its initial vertical height and horizontal position. [0072] The various in-plane motions described in FIG. 10 and hereafter are to be understood by those versed in the art as being executed by robotic actuators with limit stops or manually through the use of locating pins. [0073] Now turning to FIGS. 9A and 9B , the clamping jaws 22 can be formed from a number of different materials, depending on the application. In the particular embodiment shown in FIG. 3 , the clamping jaws 22 are made of stainless steel, but materials of varying stiffness could be used. The clamping jaws 22 have two clamping surfaces 19 on opposing faces of each jaw 22 as shown in FIG. 9 a and FIG. 9 b . Each clamping surface 19 has contours 34 that are designed to fix the position and orientation of the device 14 to be implanted while it is penetrating the tissue into which it is being implanted to minimize relative motion of device 14 within clamping jaw 22 . On one clamping surface 19 , the contour 34 is a recess 36 ( FIG. 9 a ) and on the other face the contour 34 is a protrusion 38 ( FIG. 9 b ), wherein protrusion 38 can be received into recess 36 . Alternative embodiments of the clamping surfaces 19 can include a coating with materials that would modify their surface conditions to reduce or eliminate sticking, for example Teflon. The device 14 to be implanted can be placed manually between the clamping surfaces 19 and the clamp mechanism 18 can be closed. Alternatively, the dispense cartridge sub-system 25 shown schematically in FIG. 8 can be used to load a single device 14 and, after the device 14 has been implanted, the next device 14 will be automatically loaded from the dispense cartridge sub-system 25 into the clamping mechanism 18 until all the desired implantations are complete. [0074] A load cell module 20 , containing such load cells as the Sensotec Model 31 , mounted on the actuator 12 (See schematic in FIG. 5 ) measures the force between the tissue and the device 14 being implanted during implantation. Knowledge of the force is a useful diagnostic for assessing soft tissue damage and implantation success and can be used during implantation as a feedback signal to control the actuator 12 , either to maintain, increase or reduce the amount of force to ensure precision in depth control. [0075] The contact sensor 16 detects the contact of the device 14 being implanted with the tissue into which it is being implanted and the signal obtained can be used to modify the implantation conditions to ensure precision in depth control. For some devices 14 , implantation must be done in a single try and their tips 26 , which are extremely sharp to reduce implantation force and soft tissue dimpling during implantation would be damaged if force feedback through the load cell 20 is used to detect contact of the device 14 with a reference stage during the referencing operation so a sensor optimized for contact detection is required. Contact sensors 16 , such as the ones from Kistler of Novi, Mich., have the ability to detect contact between two structures with a force of approximately 2 mN, which is below the force level that would lead to damage of the tips 26 of the device 14 being implanted. In the embodiment shown schematically in FIG. 5 , the contact sensor 16 is mounted on the outer side of the clamping surfaces 19 to achieve the optimal signal to noise ratio for the contact sensor 16 . After the device 14 being implanted is loaded in the clamping mechanism 18 , the actuator 12 moves laterally or rotationally to a reference tab 24 and moves in the implantation direction through a distance D 1 until contact with the reference tab 24 is sensed (see schematic in FIG. 6A ). The distance D 1 is measured through the software that controls the actuator 12 . The position at which contact is sensed is used as a reference for the tip 26 of the device 14 being implanted to ensure the spatial relationship between the device tip 26 and the tissue surface 32 it will be implanted through is known to the positional accuracy of the actuator 12 (see FIG. 12 ). The distance from the laser ranging system 30 to the base of the clamp 18 is fixed by design at a distance D 4 . The distance from the base of the clamp 18 to the recess 36 ( FIG. 9A ) on the clamping surface 19 of the clamp jaws 22 is fixed by design at D 3 . The distance from the recess 36 on the clamping surface 19 of the clamp jaws 22 to the reference tab 24 is fixed by design at D 5 . When contact between the tip 26 of the device 14 and the reference tab 24 is detected after the actuator 12 has travelled a distance D 1 , the device 14 length D 2 can be calculated by D 5 −D 1 . After D 2 has been calculated the distance from the laser ranging system 30 to the tip of device 26 is known (D 2 +D 3 +D 4 ). [0076] After device referencing, the surgeon performing the implantation or a processor 40 executing an automated routine uses the imaging sub-system 28 to position the device 14 being implanted above the tissue surface being implanted (see schematic in FIG. 6B ), which is shown in a process flow diagram in FIGS. 11A and 11B . It is to be understood by those versed in the art that the movement of the actuator 12 during the procedure described in FIGS. 11A and 11B can be achieved using user-guided robotic control: [0077] Step 11 : It is assumed at this step that the actuator 12 is in its initial position following the procedure in FIG. 10 and that the imaging system 28 is in its low magnification state which can be on the order of 0.5× to 5×; [0078] Step 12 : Move the actuator 12 to the implantation vicinity as determined by a magnified video image; [0079] Step 13 : Determine the vertical distance and angular relationship between the actuator 12 and the surface 32 of the tissue in the implantation vicinity; [0080] Step 14 : Adjust the position of the actuator 12 to zero the angular displacement between the longitudinal axis of the actuator 12 and the normal to the tissue surface 32 at the implantation vicinity; [0081] Step 15 : Increase the magnification to a point where the area of the spatial range of the implantation sites is 25% of the field of view 46 in the video image ( FIG. 7A ); [0082] Step 16 : Capture an image of the tissue surface 32 in this field of view 46 ( FIG. 7A ); [0083] Step 17 : Process the raw image of this field of view 46 to delineate tissue structures subject to damage by device implantation, based on parameters, for example the veins 48 visible in FIGS. 7A and 7B ; [0084] Step 18 : Overlay on the processed image a to-scale projection of the implantation sites 50 for the device 14 to be implanted based on the current position of the actuator 12 , as shown in FIG. 7B , this is the initial implantation location; [0085] Step 19 : Compute the total area of overlap between the implantation sites 50 and the tissue structures subject to damage by device 14 implantation; [0086] Step 20 : Displace the virtual representation of the implantation sites 50 by a user-defined fraction of the dimension of a single implantation site and by a user defined step angle to a subsequent implantation location, for example, if the implantation site is 80 microns in diameter, the horizontal displacement could be 10 microns and the step angle (or angular displacement) could be 0.5° (see FIG. 6C for an illustration); [0087] Step 21 : Repeat Steps 19 and 20 until every horizontal and angular position of the implantation sites in the entire field of view 46 has a computed overlap area; [0088] Step 22 : Identify the horizontal and angular position of the implantation sites 50 that leads to the minimum overlap area between the implantation sites 50 and the tissue structures subject to damage by device implantation, this is called the optimal implantation location; [0089] Step 23 : Overlay the projection of the implantation sites 50 at the optimal implantation location onto the live video image of the field of view 46 , overlay can be color coded for ease of recognition; [0090] Step 24 : Prompt the surgeon to accept this implantation location or make a manual adjustment of the software projection of the implantation sites 50 on the live video image (optional); [0091] Step 25 : Finalize the implantation location (optional); [0092] Step 26 : Move the actuator to the optimal implantation location and overlay the virtual representation of the implantation sites 50 on the live video image; [0093] Step 27 : Determine the vertical distance and angular relationship between the actuator 12 and the surface of the tissue at the implantation location using the laser ranging subsystem; [0094] Step 28 : Adjust the position and orientation of the actuator so the longitudinal axis of the actuator is normal to the tissue surface at the optimal implantation location, based on the vertical distance and angular relationship; [0095] Step 29 : Prompt the surgeon to make a final refinement of the implantation location, accept the current position and orientation or restart the mapping process at Step 16 (optional); and [0096] Step 30 : Finalize the implantation location and move the actuator to that position and orientation if a manual refinement occurred (optional). [0097] The imaging sub-system 28 , such as the Selectech SE-1008-400X video microscope, has a magnification range from 0.5× to 400× that enables the identification of the implantation vicinity at low magnification and the identification of the exact implantation location at high magnification. The implantation vicinity could correspond to a hole drilled through the skull, or a vertebra, with a scale of several millimeters in diameter. The exact implantation location could be 10's of microns in diameter and a small area within the implantation vicinity. The multiple magnification scales are necessary to allow the surgeon doing the implantation to locate the small implantation location within the larger implantation vicinity. As higher magnifications also result in smaller fields of view, it is necessary to have low magnification imaging for orienting to the implantation vicinity. Through a software like Matlab's Image Processing module, a video image of the tissue surface at the implantation location, in the visual region of the electromagnetic spectrum, or the infrared region, is captured ( FIG. 7 a ) and a virtual representation of the initial implantation site, or sites for multi-shank devices, based on the current position of the actuator 12 are overlaid on the video image of the tissue surface, as shown in FIG. 7 b . The laser ranging sub-system 30 references the surface of the tissue into which the device 14 is being implanted and monitors the fine motions of the tissue due to, for example, respiratory and pulsatile motions. A laser ranging sub-system 30 , such as the Hokuyo URG-04LX-UG01 Sokuiki sensor, is mounted to the body of the linear actuator 12 as shown schematically in FIG. 6B . This system works by reflecting laser beams off of the surface of the tissue, collecting the reflected light and determining variations in time taken for the light to travel from the source to the detector. [0098] Optionally, when the surgeon is satisfied with the targeting of the device, the surgeon initiates a command to the linear actuator 12 to move with a predetermined speed to a predetermined depth from the surface 32 of the tissue based on the reference heights of the tissue surface 32 and the tip 26 of the implantation device 14 . The speed and depth of the implantation must be predetermined in a separate procedure that is beyond the scope of this invention and is typically performed in either a research environment on animal models or through extensive imaging studies using technologies such as fMRI (function magnetic resonance imaging). In the embodiment shown in FIG. 3 , the maximum speed is 200 m/s with a positional accuracy of 10 microns. During implantation the signals from the load cell 20 and the contact sensor 16 are used to control the trajectory of the actuator and compensate for the difference between predicted insertion forces and contact points and measured insertion forces and contact points. The algorithm for controlling the trajectory of the actuator is laid out in FIG. 12 . [0099] Step 31 : At this step, the actuator 12 is at the optimal implant location, the tissue height has been referenced and the laser ranging sub-system 30 has a measure of the dynamic distance from the tissue surface 32 to the tip 26 of the device 14 to be implanted, based on the motion of the tissue surface 32 due to pulsatile and respiratory motions [0100] Step 32 : The surgeon or processor 40 initiates the implantation procedure and the actuator 12 moves toward the tissue surface 32 at a predefined speed that incorporates the dynamic motion of the tissue. [0101] Step 33 A: The contact sensor 16 detects contact and signals the processor 40 . [0102] Step 33 B: The load cell 20 detects the force the tissue is exerting on the device 14 during implantation and signals the processor 40 . [0103] Step 34 A: The processor 40 compares the actual distance the actuator 12 travelled when contact was detected to the expected value based on the tissue reference height and the length D 2 of the device 14 to be implanted. [0104] Step 34 B: The processor 40 compares the actual force on the device 14 being implanted to the expected force. [0105] Step 35 : The processor 40 adjusts the speed of the actuator 12 and the remaining distance it will travel to reach the implantation depth based on the output of Step 34 A and 34 B. [0106] Step 36 : The final travel distance of the actuator 12 , the contact height and the load cell output are stored in memory 42 for diagnostic purposes. [0107] Step 37 : Once implantation is completed, the clamp mechanism 18 releases the clamping surface 22 and the actuator 12 retracts to its home position in anticipation of the next device 14 being used. [0108] Another embodiment of the invention monitors body function and movement (e.g., breathing, pulse, muscle twitching or spasms, etc.) of the patient and the target tissue's relative movement to the device 14 as a function of the body function and movement. The aforementioned sub-systems (laser ranging sub-system 30 , imaging sub-system 28 ) of the apparatus 10 can be used as monitors, but any commercially available component that performs such monitoring tasks is acceptable. The processor 40 will analyze the body functions and movements to generate a dynamic system equation or equations to synchronize the actuation of the actuator 12 for placement of the device 14 into the tissue. [0109] While the disclosure has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the embodiments. Thus, it is intended that the present disclosure cover the modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents.

Apparatus and method for surgeon-assisted rapid surgical implantation of devices into soft tissue. The apparatus comprises several subsystems that enable the referencing of the spatial position and orientation of the device being implanted with respect to the soft tissue into which it is being implanted and then the controlled implantation of the device at a predefined speed with higher positional accuracy and precision and a reduction in soft tissue damage, provided by ultrasonic assisted motion, compared to current state-of-the-art implantation methods and devices. The method includes automated loading of the device being implanted into a clamping mechanism from a cartridge holding a number of implants, referencing of the device position and orientation, referencing of the surface of the tissue into which the device is being implanted, monitoring of the tissue motion, identification of desirable implant location based on the soft tissue profile, allowance of surgeon selection and fine adjustment of the final implant location, high-speed implantation, device release and implant actuator retraction.

FIELD OF THE INVENTION [0001] The present invention relates to an introducer or deployment assembly for deploying implants and other prostheses within a patient, and in particular to the catheter or cannula which carries the implant or other prosthesis. BACKGROUND OF THE INVENTION [0002] A typical endoluminal introducer or deployment system includes an inner catheter or cannula, which may also be arranged as a pusher and/or dilator (hereinafter referred to as an inner catheter or catheter element) and a sheath covering the inner catheter. An implant or prosthesis is carried on the inner catheter and is fixed thereto by means of the covering sheath and with or without one or more restraining wires or any of a number of other known retention systems. [0003] The implant or prosthesis might be a stent, a stent graft, a vena cava filter, an occlusion device or any other implantable device of such a nature. [0004] Once the distal end of the catheter has been positioned inside a patient, typically at the site of the patient's vasculature to be treated, the device is released and deployed in the desired position. The deployment operation involves retracting the covering sheath so as to expose the device to be implanted, which device is then deployed, either by self-expansion or by means of an expansion device such as an inflatable balloon. In the case where the device is also held by restraining wires, these are withdrawn, typically after retraction of the sheath. Restraining wires may or may not be used in such apparatus, generally in dependence upon the nature of the device to be deployed, size restrictions and the particular medical application or intervention procedure. [0005] The step of retracting the covering sheath from the inner catheter has been known to compress or otherwise deform the device to be implanted. This can affect the positioning of the device at the deployment site and can in some circumstances damage the device itself. These problems can be experienced particularly in the case of delicate implants such as some stents. [0006] Various systems have been proposed to deal with this problem. For example, US Patent Publication No. 2004/0106977 discloses in some embodiments the provision of one or more bands of an adhesive on the outer surface of the inner catheter, which is intended to hold a stent until its deployment, and in other embodiments ridges or stepped walls on the outer surface of the inner catheter which engage struts of the stent to prevent longitudinal movement thereof along the inner catheter as the covering sheath is retracted. [0007] A problem with providing adhesive on the inner catheter is that this is another material to which a patient is exposed, even if only temporarily. It also requires a constant compressive force on the device held on the inner catheter for the glue to perform its function fully. The pressure required to compress the stent reliably into the adhesive layer results in there being a higher friction between the sheath and the stent, which provides an undesirable compromise in such devices. [0008] The mechanical holding function provided by ridges or stepped walls on the inner catheter can be significantly better at holding the device firmly on the inner catheter during the deployment operation. However, there are risks that the ridges on the outer surface of the inner catheter can snag on the device once this has been deployed or on the inner surfaces of the patient's vasculature as it is retracted from within the patient. This can cause movement or damage to the implanted device or irritation or damage to the patient's vasculature or organs. The risks are increased where the device to be implanted is small and/or particularly delicate and when the device is implanted in or near a tortuous part of a patient's vasculature. SUMMARY OF THE INVENTION [0009] The present invention seeks to provide an improved deployment assembly and an improved inner catheter or cannula. [0010] According to an aspect of the present invention, there is provided a catheter element for an introducer designed to carry a medical device to be implanted in a patient, which medical device includes a structure with one or more interstices therein; the catheter element including an elongate device support region on which a device can be located and at least one flexible member arranged on at least a portion of said support region, said flexible member extending radially outwardly from said support region and being partially deformable by a said medical device carried on the catheter element so as to be at least partially locatable in the interstice or interstices of the medical device. [0011] The device support element is typically a portion of the catheter designed to hold the device to be implanted. [0012] The flexible fingers, which are preferably of a fibrous or filamentary type, are able to engage with the device being carried so as to provide support to the device in the longitudinal direction of the catheter, particularly upon the removal of a covering sheath. The flexible nature of the fingers prevents or substantially eliminates the risk of damage to the device or to the patient during withdrawal of the catheter once the device has been deployed. In particular, even with fingers which are substantially evenly flexible throughout their length, the tips of the fingers will be able to deflect more than their bases, with the result that if they come into contact with the deployed device or the walls of the patient's vasculature or organ, they will brush against these without causing damage. [0013] It is to be understood that the term catheter element as used herein is intended to encompass all forms of device for carrying such implants and prostheses endoluminally in a patient, including inner catheters, cannulae and devices acting as pushers and/or dilators. [0014] The fingers may be substantially flat, they may be substantially round or oval in cross-section or may have any other suitable cross-sectional shape. [0015] In some embodiments, the fingers extend substantially perpendicularly to the longitudinal axis of the device support region. In other embodiments, the fingers extend at an angle to the transverse direction. A preferred embodiment has fingers which extend towards a distal end of the catheter, for example at 45° or at any angle between 20° to 80°, more preferably 30° to 60°. [0016] It is envisaged that there could be a variety of different sets of fingers, arranged at different angles to one another. [0017] Preferably, the fingers extend in a radial direction of the device support region. [0018] The fingers may be substantially straight but they could be curved. Again, the catheter could be provided with a mixture or straight curved fingers. [0019] In some embodiments, at least some of the fingers have hooked ends. [0020] Preferably, the fingers are formed from the same material as the elongate element. This allows the fingers to be moulded with the device support region. [0021] In another embodiment, the fingers are formed from a material different from the device support region and the catheter. [0022] The length of the fingers will be dependent upon the particular dimensions of the catheter and of the device to be held thereby. In the preferred embodiment, the fingers are arranged on the device support region in sets. They may be grouped radially around the device support region or they may be grouped longitudinally along the device support region. In a particular embodiment, the fingers are grouped both in the radial and in the longitudinal direction. [0023] According to another aspect of the present invention, there is provided an introducer system including a catheter element as specified herein, a sheath and a device to be deployed in a patient. [0024] Preferably, the device is a stent, a stent graft, a vena cava filter or an occlusion device. DESCRIPTION OF THE DRAWINGS [0025] Embodiments of the present invention are described below, by way only, with reference to the accompanying drawings, in which: [0026] FIG. 1 is a side elevational view of an example of known stent delivery device which can be modified to include a catheter element according to the teachings herein; [0027] FIGS. 2 and 3 show the stent delivery device of FIG. 1 during deployment of a stent; [0028] FIG. 4 is a side elevational view of the distal end of an embodiment of a catheter; [0029] FIG. 5 is a view of the catheter of FIG. 4 from its distal end; [0030] FIG. 6 is a side elevational view of another embodiment of a catheter having hooked fingers; [0031] FIG. 7 is a side elevational view of an embodiment of a catheter having fingers at an angle of between 20° to 80° relative to the longitudinal direction of the catheter; [0032] FIG. 8 is a side elevational view of another embodiment of a catheter having a plurality of sets of fingers arranged in the longitudinal direction of the catheter; [0033] FIG. 9 is a view of another embodiment of a catheter having a plurality of sets of fingers arranged in the radial direction of the catheter; [0034] FIG. 10 is a side elevational view of another embodiment of a catheter having curved fingers; [0035] FIG. 11 is an elevational view in cross-section of the embodiment of a catheter of FIG. 4 with a stent located thereon; and [0036] FIG. 12 is a perspective view of another embodiment of a catheter. DESCRIPTION OF THE PREFERRED EMBODIMENTS [0037] It is to be understood that the Figures are schematic and do not show the various components in their actual scale. In many instances, the Figures show scaled up components to assist the reader. [0038] In this description, when referring to an introducer or deployment assembly, the term distal is used to refer to an end of a component which in use is furthest from the surgeon during the medical procedure, including within a patient. The term proximal is used to refer to an end of a component closest to the surgeon and in practice in or adjacent an external manipulation part of the deployment of treatment apparatus. [0039] On the other hand, when referring to an implant such as a stent or stent graft, the term proximal refers to a location which in use is closest to the patient's heart, in the case of a vascular implant, and the term distal refers to a location furthest from the patient's heart. [0040] The example of delivery system shown in FIGS. 1 to 3 is the applicant's delivery system for its Zilver™ stent and in particular for its Zilver biliary stent. [0041] The delivery assembly 10 shown in FIG. 1 includes a tubular handle 12 , conventionally made of a plastics material, and a hub 14 , also made of a plastics material. A safety lock 16 is removably fitted into a portion of the handle 12 , for purposes to be described below. [0042] An introducer catheter 18 , made of any of the conventional or otherwise suitable catheter materials known in the art, extends from and is attached to the handle 12 , in this example by a threaded nut 15 . Housed within the introducer catheter 18 is an inner catheter 36 (visible in FIG. 3 ) which carries stent 30 and which is provided at its distal end with a flexible dilator tip 20 . The inner catheter 36 has a bore passing therethrough for the introduction of a guide wire 34 , shown in FIGS. 2 and 3 . [0043] The handle 12 is provided with a side arm flushing port 22 , of conventional form, for flushing the space inside the introducer catheter 18 . [0044] The hub 14 is fixed to a metal cannula 24 which is itself attached to the inner catheter 36 . [0045] The introducer system 10 is provided with radiopaque markers 26 . In this example, the proximal marker 26 is located on the introducer catheter 18 , while the distal marker 26 is provided on the inner catheter 36 , as will be apparent from FIG. 3 . [0046] The hub 14 is provided with an inner support stylet 28 operable to receive and support a guide wire 34 , which guide wire 34 passes through the inner stylet 28 , the hub 14 , the metal cannula 24 , the inner catheter 26 and out of distal end of the introducer tip 20 . [0047] The distal end of the inner catheter 36 , adjacent the dilator tip 20 , supports a stent 30 , in this example a Zilver™ biliary stent obtainable from the applicant. The introducer catheter 18 overlies and acts as a holding sheath for the stent 30 . This stent 30 is provided, in this example, with its own radiopaque markers 32 , in a form known in the art. [0048] The safety lock 16 acts to lock the metal cannula in an extended position relative to the handle 12 , as shown in FIG. 1 , and thus to lock the introducer catheter over the inner catheter 36 , until the time of deployment. [0049] Referring now to FIGS. 2 and 3 , a stent is deployed, in this case in a biliary tract of a patient, by first introducing a guide wire 34 through an access catheter (not shown) across the distal segment of the target lesion 40 of the biliary tract. Once the guide wire 34 is in place, the introducer catheter 18 is fed over the guide wire 34 until the distal end of the introducer catheter is over the target lesion 40 . During this process the introducer catheter is flushed with saline solution through the side arm flushing port 22 . [0050] Once the introducer catheter 18 has been located at the deployment site, the stent 30 held by the device 10 is ready to be deployed. This position of the introducer assembly 10 is shown in FIG. 2 , with the two fluorescent markers 26 appearing either side of the target lesion site 40 . [0051] In order to deploy the stent 30 , the safety lock 16 is removed, which allows the handle 12 to be slid over the metal cannula 24 . In other words, once the safety lock 16 has been removed, the handle 12 can be pulled back whilst holding the hub 14 steady. This action of pulling back the handle 12 retracts the introducer catheter 18 from the inner catheter 36 with the result that the stent 30 is exposed and allowed to expand gradually as the introducer catheter 18 moves backwards relative to the inner catheter 36 . FIG. 3 shows the introducer catheter 18 fully withdrawn and the stent 30 fully deployed at the target lesion 40 . [0052] Once the stent 30 has been deployed, the delivery assembly can be withdrawn by pulling the handle 12 and the hub 14 together in a withdrawal direction, that is out of the patient. This procedure is known in the art in particular in connection with deployment of the applicant's Zilver™ stent. [0053] As has been explained above, in some instances, it is possible that friction can develop between the introducer catheter 18 and the stent 30 with the result that the stent 30 can in some instances become deformed as the introducer catheter 18 is withdrawn, typically by compression of the stent. [0054] FIG. 4 shows in side elevation the distal end of an embodiment of catheter 100 for use in the assembly of FIG. 1 . The catheter 100 is of a structure substantially similar to conventional inner catheters or cannulae, including those arranged with pushers and/or dilators and other elements used to deploy devices intraluminally and within organs of a patient. [0055] In the embodiment of FIG. 4 , the device holding region or element 102 of the catheter 100 , that is the region on which the device to be implanted is fitted for deployment, is provided with a plurality of flexible fingers 104 extending outwardly from the holding region 102 of the catheter 100 . [0056] The holding region 102 is typically a portion of the catheter 100 designed to hold the device to be implanted and may, for example, have a smaller outer diameter than the remainder of the catheter 100 and may be provided with a shoulder at its proximal end for applying a pushing pressure to the device carried thereby. [0057] The flexible fingers 104 are able to engage with a device being carried on the catheter 100 so as to provide support to the device in the longitudinal direction of the catheter. This is described in more detail below in connection with FIG. 11 . [0058] The fingers 104 are preferably substantially uniform throughout their length but it is envisaged that in some embodiments these may have varying flexibilities, for example to become more flexible towards their tips 106 . This may be achieved by tapering the thickness or diameter of the fingers 104 towards their tips 106 although it is envisaged that this could also be achieved by use of different materials within each finger. [0059] The fingers 104 may be substantially flat, they may be substantially round or oval in cross-section or may have any other suitable shape. [0060] It is preferred that the array of fingers 102 extends for at least the length of the holding region. In some embodiments, the array of fingers 104 might extend for only a portion of the holding region 102 . In fact, in some applications it is not necessary for the fingers 104 to extend over the full length of a device to be carried on the holding element 102 . [0061] FIG. 6 shows an embodiment of catheter 200 in which at least some of the fingers 204 have hooked ends 206 . These can have the function of hooking over the strut of a stent located on the holding region such as to hold the stent better on the catheter 200 . This can reduce the force required to be applied by the sheath to compress the stent, particularly in the case where restraining wires are not used, and thus reduce the friction between the sheath and the stent. [0062] It is preferred that the hooked fingers 204 provide a restraining force which is not sufficient to hold the device in a compressed state on the catheter 200 , thus allowing the device to expand normally once the sheath is withdrawn. [0063] FIGS. 4 and 5 in particular show the fingers 104 extending substantially perpendicularly from longitudinal axis of the holding region 102 of the catheter 100 . In some embodiments, some or all of the fingers 102 could extend at another angle. FIG. 7 shows an embodiment of catheter 300 in which the fingers 304 extend outwardly and towards the distal end 308 of the catheter 300 . This angle may be, for example, 45° or 60° or any angle between 20° to 80°, more preferably 30° to 60°. [0064] It is envisaged that there could be a variety of different sets of fingers 304 , set at different angles to one another. [0065] The fingers 104 are shown in FIGS. 4 and 5 to be substantially evenly spaced along and around the holding region 102 . However, other embodiments are envisaged. FIG. 8 , for example, depicts an embodiment of catheter 400 having a plurality of sets 404 of fingers which are spaced from one another in the longitudinal direction of the catheter 400 . FIG. 9 shows an end view of an embodiment of catheter 500 having a plurality of sets 504 of fingers which are spaced from one another in the radial direction of the catheter 500 . It is also envisaged that the fingers may be grouped both in the radial and in the longitudinal direction. [0066] The fingers 104 may be substantially straight, as shown in FIGS. 4 and 5 , but they could equally be curved as shown in FIG. 10 , preferably in a direction towards the distal end 608 of the catheter 600 . In some embodiments, the catheter 600 could be provided with a mixture or straight curved fingers. Equally, in some embodiments there could be fingers which curve away from the distal end 608 . [0067] In another embodiment, the fingers may be arranged in one or more helixes around the elongate element 102 . [0068] The fingers may be formed from the same material as the elongate element 102 , and in practice as the catheter 100 . This allows the fingers to be moulded with the catheter. [0069] It is also envisaged that the fingers could be are formed from a material different from the elongate element and the catheter, such as of a fibrous material such as metal, metal alloy, Nitinol, nylon. In this case, the fingers could be embedded, welded or adhered onto the holding portion of the catheter. [0070] The length of the fingers will be dependent upon the particular dimensions of the catheter and of the device to be held thereby. In some embodiments, the fingers will be of a length to touch the inner surface of the outer sheath. They may also be longer than this. [0071] The fingers need not be the same length as one another. They could, for example, decrease in length from one end of the element 102 to the other or could decrease in length towards or away from its centre. [0072] FIGS. 4 and 5 show a plurality of rows of fingers 104 extending along the elongate element 102 , in particular eight rows. In other embodiments a different number of rows may be provided, including just two located diametrically opposite one another. [0073] FIG. 11 shows a cross-sectional view of the embodiment of catheter 100 of FIGS. 4 and 5 with a stent 110 thereon. The stent 110 is formed of a plurality of interconnected struts 112 which sit between adjacent fingers 104 of the catheter 100 . The fingers 104 have the effect of providing resistance to longitudinal movement of the stent 110 when the sheath 114 is retracted during the deployment operation and in many embodiments also resistance against twisting of the stent 110 in a radial direction, caused for example by twisting or bending of the catheter 100 or the sheath 114 during withdrawal of the sheath 114 . [0074] Given the flexible nature of the fingers 104 , as a stent is being compressed onto the catheter 100 during the assembly process, the fingers 104 will tend to deflect out of their way, in a manner shown in FIG. 11 . [0075] Furthermore, flexible nature of the fingers prevents or substantially eliminates the risk of damage to the stent or to the patient during withdrawal of the catheter once the stent has been deployed. In particular, even with fingers which are substantially evenly flexible throughout their length, the tips 106 of the fingers will be able to deflect more than their bases, with the result that if they come into contact with the deployed device or the walls of the patient's vasculature or organ, they will brush against these without causing damage. [0076] Although FIG. 11 shows a stent 110 carried on the catheter 100 , any other device could likewise be carried, including for example a stent graft, a vena cava filter or an occlusion device. [0077] In another embodiment, in place of fingers 104 , there may be provided one or more discs on the elongate member 102 , as shown in FIG. 12 . The discs 700 are made from a flexible material such as silicon, nylon or any other suitable biocompatible material. The discs 700 extend annually around the elongate carrier element 102 at spaced intervals. The discs are sufficiently thin to be able to fold when a stent is compressed onto the elongate carrier 102 , such that parts of the discs 700 not directly under a stent strut are not completely compressed and extend into spaces between the stent struts to hold the stent on the elongate carrier 102 . [0078] In an alternative embodiment, the discs could instead be in the form of an annular connector for fixing to the elongate carrier, with formed integrally thereon a series of fingers extending annularly from the annular connector so as to fan out from the connector. [0079] Thus, in the described embodiments, the flexible member, that is the fibres, fingers of disks, are able to flex in such a manner as to extend into the interstices of the medical device so as to hold this in position longitudinally on the carrier. [0080] It will be appreciated that the various features of the fingers disclosed herein, including but not limited to the features of curvature, hooked ends, flexibilities and placement in sets may be combined with one another as desired by the skilled person and not restricted to the particular embodiments in which they are described. [0081] The skilled person will also appreciate that there are many methods available in the art for producing such catheter structures with fingers or discs thereon, including for example moulding, adhesion, welding and the like. It is therefore not necessary to describe any such methods in detail herein. [0082] Moreover, although the preferred embodiments have been described in relation to the applicant's Zilver™ stent and delivery system, the teachings herein are applicable to all other catheter or cannula based delivery systems suitable for delivering stents, stent-grafts, filters, occlusion devices and other implants.

A catheter for use in an endoluminal delivery assembly includes a device holding region or element on which there is provided a plurality of flexible fingers extending outwardly therefrom. The fingers act to maintain a device to be deployed in the correct position on the catheter and act to resist deformation of the device during deployment.

FIELD OF THE INVENTION [0001] This invention relates generally to the control of pathogenic bacteria in animals raised for human consumption and more particularly to the control of Salmonella enterica serovar Typhimurium DT104 and Salmonella enterica serovar Newport by administering probiotic bacteria to the animals. BACKGROUND OF THE INVENTION [0002] Salmonella spp. are widespread with in the environment. Their primary habitat is the intestinal tracts of birds, reptiles, animals (especially those on the farm), humans, and occasionally insects. They may also be found in other parts of the body from time to time, for example in the spleen, liver, bile, mesenteric and portal lymph nodes, diaphragm, and pillar in slaughterhouse pigs. Jay, J. M., Modern Food Microbiology, 6th ed. Aspen Publishers, Gaithersburg, Md. (2000). [0003] Serovars that cause human salmonellosis are most often found in foods of animal origin, such as pork and poultry meats, and dairy products. Oosterom, J., Int. J. Food Microbiol. 12:41-52 (1991). The persistence of salmonellae in slaughterhouses and meat processing facilities continues due to the exposure of livestock to environmental sources of contamination, contaminated feeds, and parental transmission of infection. The feces of infected humans and animals contaminate water sources, which subsequently infect farm animals, then contaminate meat during slaughter, and subsequently infect humans, beginning the cycle anew. This cycle is augmented by the practice of international shipping of animal products and feed, which has lead to the worldwide distribution of salmonellosis. [0004] In the 1980s, surveillance data of cattle and human isolates indicate that Salmonella enterica serovar Typhimurium DT104 emerged worldwide. S. Typhimurium DT104 typically is resistant to the antibiotics ampicillin, chloramphenicol, streptomycin, sulphonamides and teracycline (R-type ACSSuT). Threlfall, E. J. et al., Vet. Rec. 134:577 (1994). Currently, data suggest that a multi-resistant Salmonella enterica serovar Newport is emerging in the United States. S. Newport typically is resistant to at least nine antibiotics. Recent studies revealed that 3.5% of retail ground beef was positive for Salmonella spp. of which 35.6% was S. Typhimurium DT104. Zhao T. et al., J. Food Prot. 65:403-407 (2002). Between January and April 2002, a five-state outbreak of S. Newport occurred. Exposure to raw or undercooked ground beef was implicated as the vehicle of transmission. Cattle are thought to be a primary reservoir through which both these multi-resistant pathogens can enter the food supply. [0005] Clinical symptoms of S. Typhimurium DT104 in humans include diarrhea, fever headache, nausea, vomiting and abdominal pain. One-fourth of patients infected in a case-control study had bloody diarrhea, 41% of patients required hospitalization, and 3% of patients died. This is much higher than the case-fatality rate associated for non-typhoid Salmonella infections, which other than for DT104, is approximately 0.1%. Aldina, J. E. et al., J. Am. Vet. Med. Assoc. 214:790-798 (1999). [0006] Surveys of feedlot cattle in the United States done in 1998 revealed that 38% of feedlots were Salmonella spp. positive, and 5.5% of all fecal samples collected were positive for Salmonella spp. S. Typhimurium DT104 was detected in 2.6% of the feedlots, and 2.9% of the positive fecal samples. Fedorka-Cray, P. J. et al., J. Food Prot. 61:525-530 (1998). A similar study conducted on beef cattle in 2000 revealed that 11.2% of all operations tested positive for Salmonella spp., and 1.4% of all fecal samples were positive. Dargatz, D. A. et al., J. Food Prot. 63:1648-1653 (2000). There are clear associations between S. Typhimurium DT104 infection in food production animals and humans. Davis, A. et al., Communicable Disease Report CDR Rev. 6:159-162 (1996). SUMMARY OF THE INVENTION [0007] Strains of probiotic bacteria, their isolation, characteristics and methods of use to prevent or treat carriage by a food production animal of Salmonella that causes human salmonellosis are provided. A non-limiting example of Salmonella strains that cause human salmonellosis are Salmonella enterica Typhimurium DT104 or Newport. By “probiotic” it is meant bacteria having the property of preventing establishment of Salmonella in a food production animal previously administered an effective dose of said probiotic bacteria. Strains of probiotic bacteria that inhibit the growth of Salmonella strains that cause human salmonellosis can be strains of E. coli and Bacillus circulans. [0008] The present invention also provides a method for preventing the carriage by a food production animal of Salmonella strains that cause human salmonellosis. The method comprises the step of administering an effective amount of a strain or combination of strains of probiotic bacteria to the food production animal prior to exposure to Salmonella strains that cause human salmonellosis. [0009] The invention further provides a method for reducing or eliminating from a food source animal Salmonella strains that cause human salmonellosis by administering an effective amount of a strain or combination of strains of probiotic bacteria. The method is useful to maintain herds or flocks of animals free of Salmonella strains that cause human salmonellosis and reduce carriage and fecal shedding of Salmonella strains that cause human salmonellosis prior to slaughter. [0010] The administration of probiotic bacteria is accomplished by feeding a feed supplement or additive which comprises an effective amount of probiotic bacteria, or by supplying a water treatment additive or inoculum to the animals' drinking water. The invention therefore provides a feed supplement composition comprising probiotic bacteria and a water additive comprising probiotic bacteria. [0011] Additional objects, advantages, and features of the present invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0012] The various advantages of the present invention will become apparent to one skilled in the art by reading the following specification and subjoined claims and by referencing the following drawings in which: [0013] FIG. 1A is a photograph of a paper disk assay showing the zones of inhibition of S. Typhimurium DT104 by isolate 36-1 on TSA agar; [0014] FIG. 1B is a photograph of a paper disk assay showing the zones of inhibition of S. Typhimurium DT104 by isolate 36-1 on XLD agar; [0015] FIG. 2A is a photograph of a agar-spot assay showing the zones of inhibition of S. Typhimurium DT104 by isolate 59-9 on TSA agar; [0016] FIG. 2B is a photograph of a agar-spot assay showing the zones of inhibition of S. Typhimurium DT104 by isolate 59-9 on MAC agar; [0017] FIG. 3 shows the an agarose gel of the comparison of PFGE DNA pulsotype of gram-negative competitive inhibition isolates from cattle; [0018] FIG. 4A is a graph showing the growth of Salmonella sp. at 37° C. in bovine feces with a low inoculum of DT104 and probiotic bacteria; [0019] FIG. 4B is a graph showing the growth of Salmonella sp. at 37° C. in bovine feces with a high inoculum of DT104 and probiotic bacteria; [0020] FIG. 4C is a graph showing the growth of Salmonella sp. at 37° C. in bovine feces with S. Newport and probiotic bacteria; [0021] FIG. 5A is a graph showing the growth of Salmonella sp. at 21° C. in bovine feces with a low inoculum of DT104 and probiotic bacteria; [0022] FIG. 5B is a graph showing the growth of Salmonella sp. at 21° C. in bovine feces with a high inoculum of DT104 and probiotic bacteria; and [0023] FIG. 5C is a graph showing the growth of Salmonella sp. at 21° C. in bovine feces with S. Newport and probiotic bacteria;. DETAILED DESCRIPTION OF THE INVENTION [0024] Strains of probiotic bacteria, their isolation, characteristics and methods of use to prevent or treat carriage by a food production animal of Salmonella that causes human salmonellosis are provided. The probiotic bacteria and methods of the present invention are especially effective for preventing and or treating carriage of Salmonella strains that cause human salmonellosis and have multiple antibiotic resistence. A non-limiting example of Salmonella strains that cause human salmonellosis are Salmonella enterica Typhimurium DT104 or Newport. [0025] “Food production animal” is used herein to describe any mammal or avian that is prepared and used for human consumption. A food production animal can be, but not limited to, a ruminant animal such as beef and dairy cattle, pigs, lamb, chicken, turkey or any other fowl. [0026] “Probiotic” is used herein as an adjective to describe bacteria isolated from a natural source and having the property of inhibiting the growth of Salmonella strains that cause human salmonellosis. The test of an inhibition used herein was an in vitro test on solid medium in which culture supernatants of candidate isolated bacteria were observed for their property of inhibiting Salmonella enterica Typhimurium DT104 or Newport growth when applied to the surface of the solid medium. Typically, a paper disc impregnated with the culture supernatant of a candidate strain was placed on the surface of an agar plate seeded with either Salmonella enterica Typhimurium DT104 or Newport. Probiotic bacterial supernatants caused a ring of clear agar or of reduced growth density indicating inhibition of Salmonella enterica Typhimurium DT104 or Newport in the vicinity of the disc. There are other tests for inhibition which are available or could be devised, including direct growth competition tests, in vitro or in vivo which can generate a panel of probiotic bacteria similar to that described herein. The bacterial strains identified by any such test are within the category of probiotic bacteria, as the term is used herein. [0027] The term “dominant probiotic” is applied to probiotic bacteria which persist in, and are re-isolatable from an animal to which the bacteria have been administered. For example, bovine calves can be fed a mixture of probiotic strains, then from a variety of tissues, digestive contents and feces are sampled 26 days post-inoculation. Recovered strains are designated dominant probiotic strains. Other criteria can be employed, including shorter or longer time periods between inoculation and sampling. It is advisable to choose a time period sufficiently long that persistence of dominant probiotic strains can provide useful reduction of the amount of Salmonella strains that cause human salmonellosis carried by the animal. [0028] Isolation of probiotic bacteria can be carried out by those of ordinary skill in the art, following the principles and procedures described herein. Of 1097 colonies isolated from cattle feces and tissues, six gram-positive isolates and 24 gram-negative isolates were identified as probiotic bacteria. Eight of the isolates, 31-6, 47-10, 50-10, 58-9, 59-9 small, 59-9 big, 71-8 and 76-9 were better at inhibiting Salmonella enterica Typhimurium DT104 or Newport. Therefore, the testing of similar numbers of independent isolates is reasonably likely to successfully yield probiotic bacteria. Probiotic bacteria isolates 31-6, 76-9 and 58-9 have been deposited with the American Type Culture Collection (ATCC), 1080 University Boulevard, Manassas, Va. 20110-2209, under the terms of the Budapest Treaty, and has been accorded the ATCC designation numbers , ,and , respectively. The deposit will be maintained in the ATCC depository, which is a public depository, for a period of 30 years, or 5 years after the most recent request, or for the effective life of a patent, whichever is longer, and will be replaced if the deposit becomes depleted or nonviable during that period. Samples of the deposit will become available to the public and all restrictions imposed on access to the deposit will be removed upon grant of a patent on this application. [0029] The probiotic bacteria can be any type of bacteria and may not necessarily be a different strain of Salmonella . For example, of the probiotic bacteria described herein, 22 of the isolates were identified as E. coli , and 7 were identified as Bacillus circulans . Administration of probiotic bacteria can be accomplished by any method likely to introduce the organisms into the digestive tract. The bacteria can be mixed with a carrier and applied to liquid or solid feed or to drinking water. The carrier material should be non-toxic to the bacteria and the animal. Preferably, the carrier contains an ingredient that promotes viability of the bacteria during storage. The bacteria can also be formulated as an inoculant paste to be directly injected into an animal's mouth. The formulation can include added ingredients to improve palatability, improve shelf-life, impart nutritional benefits, and the like. If a reproducible and measured dose is desired, the bacteria can be administered by a rumen cannula. The amount of probiotic bacteria to be administered is governed by factors affecting efficacy. When administered in feed or drinking water the dosage can be spread over a period of days or even weeks. The cumulative effect of lower doses administered over several days can be greater than a single larger dose thereof. By monitoring the numbers of Salmonella strains that cause human salmonellosis in feces before, during and after administration of dominant probiotic bacteria, those skilled in the art can readily ascertain the dosage level needed to reduce the amount of Salmonella strains that cause human salmonellosis carried by the animals. One or more strains of dominant probiotic bacteria can be administered together. A combination of strains can be advantageous because individual animals may differ as to the strain which is most persistent in a given individual. [0030] Probiotic bacteria can be administered as a preventive, to prevent animals not presently carrying Salmonella strains that cause human salmonellosis from acquiring the strains by exposure to other animals or environments where the strains are present. Young and mature food production animals about to be transferred to a new location, such as a feed lot, are attractive candidates for preventive administration. [0031] Treatment of animals carrying Salmonella strains that cause human salmonellosis can be accomplished to reduce or eliminate the amount of the strains carried by the animals, by administering probiotic bacteria to animals infected with Salmonella strains that cause human salmonellosis. Animals known to be shedding the strains in feces, or those raised where the strains are known to exist are suitable candidates for treatment with probiotic bacteria. [0032] The methods for administering probiotic bacteria are essentially the same, whether for prevention or treatment. Therefore, the need to first determine whether the undesired Salmonella strains are being carried by the animals is removed. By routinely administering an effective dose to all the animals of a herd, the risk of contamination by the undesired Salmonella strains can be substantially reduced or eliminated by a combination of prevention and treatment. [0033] The foregoing and other aspects of the invention may be better understood in connection with the following examples, which are presented for purposes of illustration and not by way of limitation. EXAMPLE 1 Isolation and Identification of Salmonella spp. From Bovine Feces [0000] Methods: [0034] Sample collection. A total of 108 fecal samples were collected in the middle Georgia region from September 2001 though January 2002. Samples were obtained from 28 dairy cattle, 80 beef cattle and five calves between four months and one year of age. Ten grams of feces was collected into Cary Blair with indicator fecal transport system (Corpimex, Miami, Fla.), and immediately transported at 5° C. Samples were stored at 4° C. for 0 to 7 days until use. [0035] Salmonella isolation and identification. Each fecal sample (10 g) was preenriched in 90 ml of lactose broth (Becton Dickinson, Sparks, Md.) for 24 hours at 35° C. After preenrichment, 1-ml volumes of enrichment culture were transferred, for selective enrichment, to 10 ml of selenite cystine broth (Becton Dickinson, Sparks, Md.) and incubated for 24 hours at 37° C., to 10 ml of tetrathionate broth (Becton Dickinson, Sparks, Md.) and incubated for 48 hours at 37° C., and to 10 ml of Rappaport-Vassiliadis R10 broth (Becton Dickinson, Sparks, Md.) and incubated for 24 hours at 42° C. After selective enrichment, a 10-μl loopful from each broth was plated in duplicate on to the surface of bismuth sulfite agar (BSA), Hektoen enteric agar (HEA), xylose lysine deoxycholate agar (XLD) and xylose lysine tergitol 4 agar (XLT4) (all Becton Dickinson, Sparks, Md.) plates. Plates were incubated for 24 hours at 37° C. Colonies with typical Salmonella spp. morphology were selected from all plates, no more than 10 colonies per plate, and transferred into triple sugar iron agar and lysine iron agar (both Becton Dickinson, Sparks, Md.) slants and incubated for 24 hours at 35° C. All presumptive Salmonella isolates were tested by the Salmonella latex agglutination assay (Oxoid Ltd., Basingstoke, Hampshire, UK). All isolates positive with the Salmonella latex agglutination assay were tested with the API 20E assay (bioMerieux, Hazelwood, Mo.) for biochemical characteristics for the identification of Salmonella . Zhao, T. et al., J. Food Prot. 65:403-407 (2002). Serotyping was conducted at the U.S. Department of Agriculture-Animal and Plant Health Inspection Service (APHIS) National Veterinary Services Laboratories, Ames, Iowa. Antibiotic resistance profiles were conducted at the U.S. Department of Agriculture-Agricultural Research Service, Athens, Ga. [0000] Results [0036] Salmonella spp. were isolated from 10 of 108 fecal samples. All positive samples were from beef cattle over one year of age (Table 1), and were collected from an auction market. Two samples were collected on Oct. 16, 2001, three samples were collected Jan. 15, 2002, and five samples were collected Jan. 29, 2002. TABLE 1 Serotype, serogroup and antibiotic resistance of Salmonella spp. isolates Isolate Antibiotic No. Date isolated Serotype Serogroup resistance ab 55 Oct. 16, 2001 Newport C2 AAmCeCfCpC SSuT 57 Oct. 16, 2001 Newport C2 AAmCeCfCpC SSuT 73 Jan. 15, 2002 Bareilly C1 None 74 Jan. 15, 2002 Mbandaka C1 None 78 Jan. 15, 2002 Newport C2 AAmCeCfCpC STTr 88 Jan. 29, 2002 Newport C2 AAmCeCfCpC SSuTTr 90 Jan. 29, 2002 Montevideo C1 None 92 Jan. 29, 2002 Meleagridis E None 102 Jan. 29, 2002 Monophasic B None 103 Jan. 29, 2002 Monophasic B None a A = ampicillin, Am = amoxicillin/clavulanic acid, Ce = cefoxitin, Cf-ceftiofur, Cp = cephalothin, C = chloramphenicol, S = streptomycin, Su = sulphamethoxazole, T = tetracycline Tr = trimethoprim/sulphamethoxzole b Screened against, amikacin, amoxicillin/clavulanic acid, ampicillin, apramycin, cefoxitin, ceftiofur, ceftriazone, cephalothin, chloramphenicol, ciprofloxacin, gentamicin, inipenem, kanamycin, nalidixic acid, streptomycin, sulphamethoxazole, tetracycline, trimethoprim/sulphamethoxazole [0037] The positive isolates included serogroups B, C1, C2, and E, four of which were serotyped as Salmonella Newport, two as monophasic Salmonella sp., one as Salmonella Bareilly, one as Salmonella Mbandaka, one as Salmonella Montevideo, and one as Salmonella Meleaglidis. [0038] Antimicrobial resistance profiles indicated that all four of the Salmonella Newport isolates were resistant to amoxicillin/clavulanic acid, ampicillin, cefoxitin, ceftiofur, cephalothin, chloramphenicol, streptomycin, and tetracycline. Isolates S55 and S57 were additionally resistant to sulphamethoxazole, and isolate S78 was also resistant to trimethoprim/ sulphamethoxazole. Isolate S88 was additionally resistant to sulphamethoxazole and trimethoprim/sulphamethoxazole, and had intermediate resistance to ceftriazone. All other Salmonella isolates had intermediate resistance to tetracycline, but were sensitive to all other antibiotics. All isolates were sensitive to amikaxin, apramycin, ciprofloxacin, gentamicin, imipenem, kanamycin, and naladixic acid. EXAMPLE 2 Isolation and Identification of Competitive Inhibition Bacteria [0000] Methods [0039] Isolation of potential competitive inhibition bacteria. Salmonella -negative fecal samples were serially diluted (1:10) in 0.1% peptone buffer, 0.1 ml of each dilution was plated in duplicate onto MacConkey agar (MAC) and tryptic soy agar (TSA) (both Becton Dickinson, Sparks, Md.), and the plates were incubated for 24 hours at 37° C. Seven colonies were randomly selected from MAC agar plates, and three colonies were randomly selected from TSA plates. Each colony was transferred to a test tube containing 10 ml of trypic soy broth (TSB) (Becton Dickinson, Sparks, Md.) and incubated for 24 hours at 37° C. [0040] Screening of cultures for anti- Salmonella Typhimurium DT104 properties. A three-strain mixture of Salmonella enteritidis serovar Typhimurium DT104 from our culture collection, including strains 8748A-1 (cattle isolate, R-type ACSSuT), 11942A-1 (cattle isolate, R-type ACSSuT), and 62 (ground beef isolate, R-type ASSuT), were initially used to screen cultures for anti- Salmonella Typhimurium DT104 activity. Two methods were used to screen for activity, the disk method (Zhao, T. et al., J. Clin. Microbiol. 36:641-647 (1998)) and the agar spot test (Schillinger, U. et al., [0041] Appl. Environ. Microbiol. 55:1901-1906 (1989)). [0042] Approximately 10 7 S. Typhimurium DT104 cells of approximately equal populations of each strain in 0.1 ml were plated onto the surfaces of XLD and TSA plates and allowed to dry for at least 30 minutes. Supernatant fluid from each culture was filter sterilized (0.2-μl-pore-size cellulose acetate membrane: Nalgene Co., Rochester N.Y.) for determination of anti- S. Typhimurium DT104 activity. Two disks (12 mm diameter, Dispens-O-Disc, Difco Laboratories, Detroit, Mich.) were placed on the surface of both the TSA and XLD plates, and 0.1 ml of the filter-sterilized supernatant fluid from a single culture was applied to the surface of the disk. In addition, filter-sterilized supernatant fluid from E. coli ATCC 14763 (produces colicin V) and 70% ethanol were used as positive controls, and filter-sterilized TSB was used as the negative control. Cultures were incubated for 24 hours at 37° C. and observed for zones of growth inhibition. Competitive inhibition bacteria were selected as those that produced a clear zone of at least 1 mm around the disk. [0043] Isolates were streaked onto TSA for single colonies and incubated for 24 hours at 37° C. Single colonies were spot inoculated onto TSA and MAC plates and incubated for 24 hours at 37° C. for colony development. Five milliliters of brain heart infusion broth (BHI) (Becton Dickinson, Sparks, Md.) with 0.5% agar (Becton Dickinson, Sparks, Md.) containing approximately 106 CFU of the three strain S. Typhimurium DT104 mixture at 50° C. was applied onto the surface of each plate, without disturbing the colony, and allowed to cool. Plates were incubated for 24 hours at 37° C., and observed for zones of growth inhibition. Competitive inhibition bacteria were selected as those that produced a clear zone of at least 1 mm around the disk. [0044] Competitive inhibition cultures were then screened, using the methods described above, against nine additional strains of S. Typhimurium DT104, obtained from the collection of P.J. Fedorka-Cray, U.S. Department of Agriculture-Agricultural Research Service, Athens, Ga. All strains were cattle isolates, and included from 1998 strains 526-K, 2848-K and 12993-K, from 1999 strains MH25382, 99-103712-5 and 12-410 and from 2000 strains 4698-K, NE14055, IA45025. Competitive inhibition cultures were screened against 10 Salmonella spp. isolates obtained during the screening process of this study. [0045] The pH of TSB was determined before and after culture growth. The pH of TSB and MAC plates was determined before colony growth, and after colony growth, both near the colony and 2 cm away from the colony following 24 hours of growth at 37° C. Growth curves for the competitive inhibition isolates strains and Salmonella were performed and generation times were calculated. [0046] Identification of competitive inhibition bacteria. Initially competitive inhibition isolates were characterized by Gram staining. Gram-positive strains were subjected to catalase tests, oxidase tests, and to biochemical testing using the API 50CH Assay (bioMerieux, Hazelwood, Mo.) with both the CHL media for lactic acid bacteria, and the CHB/E media for Bacillus spp. Spore formation was determined by holding overnight cultures at 80° C. with agitation at 190 rpm for 10 minutes, then streaking the cultures in duplicate onto TSA plates and incubating for 24 hours at 37° C. [0047] Gram-negative isolates were subjected to biochemical testing using the API 20E Assay (bioMerieux, Hazelwood, Mo.), and subtyping by PFGE using procedures similar to those described previously (Meng, J. et al., J. Med. Microbiol. 42:258-263 (1995)) and those used by the Centers for Disease Control and Prevention. This involved growing isolates on TSA plates for 24 hours at 37° C., then suspending cells of each culture in Cell Suspension Buffer (CSB) (100 mM Tris: 100 MM EDTA, pH 8.0) with a sterile swab to a cell populations having an optical density of 1.3-1.4 at 610 nm (SPEC). The bacterial suspension, 0.2 ml, was mixed with 10 μl of 20 mg proteinase K/ml and 0.2 ml 1% SeaKem Gold: 1% SDS agarose in TE buffer (1 mM Tris:1 mM EDTA, pH 8.0). The mixture was dispensed into sample moulds and the agarose plugs were digested with 0.1 mg proteinase K/ml in lysis buffer (20 mM Tris:50 mM EDTA, pH 8.0+1% Sarcosine at 54° C. for 2 hours. The plugs were then washed at 50° C., three times in sterile water and three times in TE buffer. Plugs were cut to 2.5 mm wide, prerestricted with IX restriction buffer for 10 minutes at 37° C., then restricted using 50U Xbal for 2 hours at 37° C. The reaction was stopped by the removal of reaction buffer and the addition of 0.5×Tris-borate EDTA buffer (TBE). The DNA samples were electrophoresed in 1% SeaKem gold agarose in 0.5×TBE buffer with a contour-clamped homogeneous electric field device (CHEF MAPPER, Bio-Rad, Hercules, Calif.). After electrophoresis for 18 hours at 6.0 V/cm with pulse times of 2.16 to 54.17 seconds, linear ramping and an electric field angle of 120 at 14° C., the gels were stained with ethidium bromide. The bands were visualized and photographed with UV transillumination. [0048] Antibiotic resistance profiles of all unique isolates were obtained using Sensititre gram-positive and gram-negative MIC plates (TREK Diagnostic Systems, Inc. Westlake, Ohio). [0000] Results [0049] A total of 1097 bacterial colonies were isolated from the feces of cattle determined not to excrete Salmonella spp. These bacteria were initially screened for their ability to inhibit the growth of, or kill a three-strain mixture of S. Typhimurium DT104 in vitro, and 45 were determined to be inhibitory (Table 2), one through the paper disk assay ( FIGS. 1A and 1B .), and 44 via the agar-spot test 9 ( FIGS. 2A and 2B .). The size and clarity of the zones of inhibition varied with the type of media and the competitive inhibition candidate. TABLE 2 Initial screening of potential competitive inhibition bacteria with inhibitory activity against 3 strains of S. Typhimurium DT104 a . Overlay Isolate Date of Disk Assay b Assay c No. Source Isolation XLD TSA MAC TSA 1-1 Dairy cow Sep. 10, 2001 − − + − 3-7 Dairy cow Sep. 10, 2001 − − − + 4-4 Dairy cow Sep. 10, 2001 − + + − 4-5 Dairy cow Sep. 10, 2001 − − + + 5-3 Dairy cow Sep. 10, 2001 − − + − 6-8 Dairy cow Sep. 10, 2001 − − − + 7-7 Dairy cow Sep. 10, 2001 − − + − 8-7 Dairy cow Sep. 10, 2001 − − + − 9-2 Dairy cow Sep. 10, 2001 − − + − 11-1  Dairy cow Sep. 10, 2001 − − + − 12-5  Dairy cow Sep. 10, 2001 − − + − 13-2  Dairy cow Sep. 10, 2001 − − + − 13-6  Dairy cow Sep. 10, 2001 − − + − 15-3  Dairy cow Sep. 10, 2001 − − + − 15-6  Dairy cow Sep. 10, 2001 − − + − 16-2  Dairy cow Sep. 10, 2001 − − + − 16-6  Dairy cow Sep. 10, 2001 − − + − 16-10 Dairy cow Sep. 10, 2001 − − + − 18-4  Dairy cow Sep. 10, 2001 − − + − 18-6  Dairy cow Sep. 10, 2001 − − + − 21-6  Dairy cow Sep. 10, 2001 − − + − 21-9  Dairy cow Sep. 10, 2001 − − + − 23-5  Dairy cow Sep. 10, 2001 − − + − 24-2  Dairy cow Sep. 10, 2001 − − + − 25-10 Beef calf Oct. 16, 2001 − − + + 29-5  Beef calf Oct. 16, 2001 − − + + 30-1  Beef calf Oct. 16, 2001 − − + + 30-5  Beef calf Oct. 16, 2001 − − + + 31-6  Beef cow Oct. 16, 2001 ++ ++ − − 35-3  Beef cow Oct. 16, 2001 − − + − 39-3  Beef cow Oct. 16, 2001 − − + − 44-2  Beef cow Oct. 16, 2001 − − + − 44-4  Beef cow Oct. 16, 2001 − − + − 47-10 Beef cow Oct. 16, 2001 − − − ++ 50-10 Beef cow Oct. 16, 2001 − − − ++ 51-2  Beef cow Oct. 16, 2001 − − + + 58-7  Beef cow Oct. 16, 2001 − − + + 58-9  Beef cow Oct. 16, 2001 − − − ++ 59-9  Beef cow Oct. 16, 2001 − − − ++ small 59-9  Beef cow Oct. 16, 2001 − − − ++ big 66-3  Beef cow Jan. 15, 2002 − − + − 71-8  Beef cow Jan. 15, 2002 − − + +++ 76-9  Beef cow Jan. 15, 2002 − − ++ 101-1  Beef cow Jan. 29, 2002 − − + + 106-2  Beef cow Jan. 29, 2002 − − + + a Strains include: 8748A-1, 11942A-1, 62 b Zone of inhibition: ++ = >2.0 mm, + = <2.0 mm, −= no zone c Zone of inhibition: +++ = >10 mm, ++ = >5.0 mm, + = <5.0 mm, −= no zone [0050] The 45 candidates were screened for in vitro inhibitory activity against an additional nine isolates of S. Typhimurium DT104, and 30 were determined to be inhibitory (Table 3 and Table 4), one through the paper disk assay, and 29 through the agar-spot assay. These 30 candidates were then screened for antimicrobial activity against the isolated Salmonella spp. isolates from the bovine feces. Only six gram-positive bacteria produced any degree of inhibitory activity against all 10 strains as demonstrated by the agar spot test. Three gram-negative isolates were inhibitory to five of the ten isolated strains (Table 5 and Table 6). TABLE 3 Screening of potential competitive inhibition bacteria with inhibitory activity against 5 strains of S. Typhimurium DT104 a . Isolate Disk Assay b Overlay Assay c No. XLD TSA MAC TSA  1-1 − − + −  3-7 − − + −  4-4 − − + −  4-5 − − + −  5-3 − − + +  6-8 − − + −  7-7 − − + −  8-7 − − − −  9-2 − − + −  11-1 − − + −  12-5 − − + −  13-2 − − + −  13-6 − − + −  15-3 − − + −  15-6 − − + −  16-2 − − + −  16-6 − − + −  16-10 − − − −  18-4 − − + −  18-6 − − + −  21-6 − − + −  21-9 − − − +  23-5 − − + −  24-2 − − + +  25-10 − − + −  29-5 − − + −  30-1 − − + −  30-5 − − + +  31-6 ++ ++ + −  35-3 − − + −  39-3 − − − −  44-2 − − − −  44-4 − − − −  47-10 − − − +++  50-10 − − − −  51-2 − − + −  58-7 − − + −  58-9 − − − +++  59-9 small − − − +++  59-9 big − − − +++  66-3 − − + −  71-8 − − − +++  76-9 − − − +++ 101-1 − − + − 106-2 − − + − a Strains include: AI45025, MH2538, 99-103712-5, NE14055, 12-410 b Zone of inhibition: ++ = >2.0 mm, + = <2.0 mm, − = no zone c Zone of inhibition: +++ = >10 mm, ++ = >5.0 mm, + = <5.0 mm, − = no zone [0051] TABLE 4 Screening of potential competitive inhibition bacteria with inhibitory activity against 4 strains of S. Typhimurium DT104 a . Isolate Disk Assay b Overlay Assay c No. XLD TSA MAC TSA  1-1 − − + −  3-7 − − + +  4-4 − − + −  4-5 − − + −  5-3 − − − +  6-8 − − + −  7-7 − − + −  8-7 − − − −  9-2 − − + −  11-1 − − + −  12-5 − − + −  13-2 − − + −  13-6 − − + −  15-3 − − − +  15-6 − − + −  16-2 − − + −  16-6 − − + +  16-10 − − − −  18-4 − − + −  18-6 − − − −  21-6 − − − −  21-9 − − − +  23-5 − − − −  24-2 − − − −  25-10 − − − −  29-5 − − − −  30-1 − − + −  30-5 − − + −  31-6 ++ ++ + −  35-3 − − + −  39-3 − − + −  44-2 − − + −  44-4 − − − −  47-10 − − − +++  50-10 − − − −  51-2 − − + −  58-7 − − + −  58-9 − − − +++  59-9 small − − − +++  59-9 big − − − +++  66-3 − − + −  71-8 − − − +++  76-9 − − − +++ 101-1 − − + + 106-2 − − + − a Strains include: 12993-k, 2748-k, 520-k, 4698-k b Zone of inhibition: ++ = >2.0 mm, + = <2.0 mm, − = no zone c Zone of inhibition: +++ = >10 mm, ++ = >5.0 mm, + = <5.0 mm, − = no zone [0052] TABLE 5 Screening of potential competitive inhibition bacteria with inhibitory activity against 5 strains of Salmonella spp. a isolated from beef cattle in Georgia. Isolate Disk Assay b Overlay Assay c No. XLD TSA MAC TSA  1-1 − − − −  3-7 − − − −  4-4 − − − −  4-5 − − − −  5-3 − − − −  6-8 − − − −  7-7 − − − −  8-7 − − − −  9-2 − − − −  11-1 − − − −  12-5 − − + −  13-2 − − − −  13-6 − − − −  15-3 − − − −  15-6 − − − −  16-2 − − − −  16-6 − − − −  16-10 − − − −  18-4 − − − −  18-6 − − − −  21-6 − − − −  21-9 − − − −  23-5 − − − −  24-2 − − − −  25-10 − − − −  29-5 − − − −  30-1 − − − −  30-5 − − − −  31-6 ++ ++ + −  35-3 − − − −  39-3 − − − −  44-2 − − − −  44-4 − − − −  47-10 − − − +++  50-10 − − − −  51-2 − − − −  58-7 − − − −  58-9 − − − +++  59-9 small − − − +++  59-9 big − − − +++  66-3 − − − −  71-8 − − − +++  76-9 − − − +++ 101-1 − − + − 106-2 − − − − a Strains include: S. Newport 55, S. Newport 57, S. Bareilly 73, S. Mbandaka 74, S. Newport 88 b Zone of inhibition: ++ = >2.0 mm, + = <2.0 mm, − = no zone c Zone of inhibition: +++ = >10 mm, ++ = >5.0 mm, + = <5.0 mm, − = no zone [0053] TABLE 6 Screening of potential competitive inhibition bacteria with inhibitory activity against 5 strains of Salmonella spp. a isolated from beef cattle in Georgia. Isolate Disk Assay b Overlay Assay c No. XLD TSA MAC TSA  1-1 − − − −  3-7 − − − −  4-4 − − − −  4-5 − − − −  5-3 − − − −  6-8 − − − −  7-7 − − − −  8-7 − − − −  9-2 − − − −  11-1 − − − −  12-5 − − − −  13-2 − − − −  13-6 − − − −  15-3 − − − −  15-6 − − − −  16-2 − − − −  16-6 − − − −  16-10 − − − −  18-4 − − − −  18-6 − − − −  21-6 − − − −  21-9 − − − −  23-5 − − − −  24-2 − − − −  25-10 − − − −  29-5 − − − −  30-1 − − − −  30-5 − − − −  31-6 − − − −  35-3 − − − −  39-3 − − − −  44-2 − − − −  44-4 − − − −  47-10 − − − +++  50-10 − − − −  51-2 − − − −  58-7 − − − −  58-9 − − − +++  59-9 small − − − +++  59-9 big − − − +++  66-3 − − − −  71-8 − − − +++  76-9 − − − +++ 101-1 − − − − 106-2 − − − − a Strains include: S. Newport 88, S. Montevideo 90, S. Meleagridis 92, and monophasic Salmonella spp. 102 and 103. b Zone of inhibition: ++ = >2.0 mm, + = <2.0 mm, − = no zone c Zone of inhibition: +++ = >10 mm, ++ = >5.0 mm, + = <5.0 mm, − = no zone [0054] The initial pH of TSB was 7.38, the pH of the medium decreased from 0.82 to 1.70 pH units occurred with the growth of each of the 30 competitive inhibition isolates that were active against all 12 strains of S. Typhimurium DT104. A decrease in pH also occurred with the growth of 12 S. Typhimurium DT104 strains and ranged from 1.10 to 1.37 pH units. The pH on MAC plates either increased slightly or decreased slightly near the competitive inhibition colonies, with a maximum pH increase of 0.22 pH units, and a maximum pH decrease of 0.54 pH units. The pH on TSA plates also increased slightly with the growth of some competitive inhibition candidates and decreased slightly with others, with a maximum pH increase of 0.34 pH units, and a maximum pH decrease of 0.08 pH units. [0055] Generation times of S. Typhimurium DT104 in TSB averaged 25 minutes, those of gram-negative competitive inhibition isolates ranged from 25 minutes to 50 minutes. The generation times of gram-positive competitive inhibition isolates ranged from 38 minutes to 52 minutes. [0056] The six gram-positive bacteria isolates were catalase-positive and oxidase-negative (Table 7). The API 50CH gave only doubtful profiles with the CHL media. With the CHB/E media gave very good identification of isolate 71-8 as Bacillus circulans , good identification of isolates 58-9 and 76-9 as Bacillus circulans , acceptable identification of 47-10 as Bacillus circulans , low discrimination for isolate 59-9 small as Bacillus circulans , and a doubtful profile for 59-9 big as Bacillus circulans . Each isolate was confirmed to be a spore producer. Antibiotic resistance profiles varied, with all strains being resistant to cefoxitin and ceftiofur, some strains being resistant to streptomycin, varying strains having intermediate resistance and resistance to ceftriaxone, all strains having intermediate resistance to tetracycline and some strains having intermediate resistance to chloroamphenicol. TABLE 7 Selected characteristics of potential gram-positive competitive inhibition bacteria with inhibitory activity against 12 strains of S. Typhimurium DT104, and 10 strains of Salmonella spp. isolated from cattle. Isolate No. Identification Antibiotic resistance ab 47-10 Bacillus circulans CeCfCtS 58-9 Bacillus circulans CeCfCS 59-9 small Bacillus circulans * CeCfS 59-9 big Bacillus circulans * CeCfS 71-8 Bacillus circulans CeCfCtS 76-9 Bacillus circulans CeCfS a Ce = cefoxitin, Cf = ceftiofur, Ct = cefiriaxone, S = streptomycin, C = chloroamphenicol b Screened against, amikacin, amoxicillin/clavulanic acid, ampicillin, apramycin, cefoxitin, ceftiofur, ceftriazone, cephalothin, chloramphenicol, ciprofloxacin, gentamicin, inipenem, kanamycin, nalidixic acid, streptomycin, sulphamethoxazole, # tetracycline, trimethoprim/sulphamethoxazole *Doubtful profiles/low discrimination by API 50 CH screening [0057] The 24 gram-negative competitive inhibition (CI) bacteria were identified through biochemical testing using the API 20E Assay (Table 8). Twenty-two E. coli , one Serratia fonticola , and one Enterobacter cloacae were identified. Genomic DNA subtyping revealed 17 different profiles among the 22 E. coli isolates. FIG. 3 shows the resulting electrophoretic pattern of the DNA samples wherein lanes 1 and 8 are E. coli O157:H7, G5244, lane 2 is isolate 5-3, lane 3 is isolate 12-5, lane 4 is isolate 13-6, lane 5 is isolate 13-2, lane 6 is isolate 30-5, lane 7 is isolate 30-1, lane 9 is isolate 15-6, lane 10 is isolate 16-2 and lane 11 is isolate 18-4. Antibiotic resistance profiling revealed that all the strains had some level of resistance to tetracycline. Other resistance to antibiotics varied among strains. TABLE 8 Selected characteristics of potential gram-negative competitive inhibition bacteria with inhibitory activity against 12 strains of S. Typhimurium DT104 and isolated from cattle. PFGE DNA Antibiotic Isolate No. Identification subtype a resistance bc  1-1 E. coli Unique None  3-7 S. fonticola Unique None  4-5 E. cloacae Unique Am, A, Ce, Cp  5-3 E. coli Unique None  6-8 E. coli Unique None  7-7 E. coli Unique None  9-2 E. coli Unique None  11-1 E. coli Unique None  12-5 E. coli Same as 5-3 None  13-2 E. coli Unique SSuT  13-6 E. coli Same as 13-2 SsuT  15-6 E. coli Unique None  16-2 E. coli Same as 15-6 None  16-6 E. coli Unique None  18-4 E. coli Same as 15-6 None  30-1 E. coli Unique Intermediate C  30-5 E. coli Same as 30-1 Intermediate C  31-6 E. coli Unique T  44-2 E. coli Unique Intermediate C  51-2 E. coli Unique None  58-7 E. coli Unique None  66-3 E. coli Unique Su 101-1 E. coli Unique A, Cp 106-2 E. coli Unique None a DNA subtyping as determined by PEGE; unique indicates that the PFGE pulsotype is different from those of the other strains in this study b Am = amoxicillin/clavulancic acid, A = ampicillin, C = chloramphenicol, Ce = cefoxitin, Cp = cephalothin, S = streptomycin, Su = sulphamethoxazole, T = tetracycline c Screened against, amikacin, amoxicillin/clavulanic acid, ampicillin, apramycin, cefoxitin, ceftiofur, ceftriazone, cephalothin, chloramphenicol, ciprofloxacin, gentamicin, inipenem, kanamycin, nalidixic acid, streptomycin, sulphamethoxazole, # tetracycline, trimethoprim/sulphamethoxazole EXAMPLE 3 Competitive Growth in Feces [0000] Methods [0058] Preparation of competitive inhibition bacteria for inoculation into feces. To facilitate enumeration of the competitive inhibition bacteria, all gram-negative bacterial isolates were selected for resistance to nalidixic acid (50 μg/ml) by exposure to serially (1:2) increased concentrations (0.1, 0.2, 0.4, 0.8, 1.6, 3.2, 6.4, 12.8, 25 and 50 μg/ml) of nalidixic acid in TSB every 24 hours at 37° C. A single colony of each strain of nalidixic acid-resistant, gram-negative, competitive inhibition bacteria was transferred to 10 ml of TSB containing nalidixic acid (50 μg/ml) and incubated for 24 hours at 37° C. A 0.1 ml portion was transferred to 10 ml of TSB and incubated for 16 hours at 37° C. Bacteria were then sedimented by centrifugation (4000×g, 10 min), washed three times in 0.1% phosphate buffered saline, pH 7.2 (PBS) and then resuspended in PBS to an optical density of 0.5 at 640 nm (ca. 10 8 CFU/ml). Nineteen gram-negative isolates were combined at equal populations. Two levels of inocula (10 5 and 10 8 CFU of gram-negative competitive inhibition isolates strains per g of feces) were used. [0059] Gram-positive competitive inhibition isolates were transferred to 10 ml of TSB and incubated for 16 hours at 37° C. Bacteria were then sedemented by centrifugation (4000×g, 10 min), washed three times in 0.1% phosphate buffered saline, pH 7.2 (PBS) and then resuspended in PBS to an optical density of 0.5 at 640 nm (ca. 10 8 CFU/ml). Six gram-positive strains were combined at equal populations. Two levels of inocula (10 5 and 10 8 CFU of gram-positive competitive inhibition isolates per g of feces) were used. [0060] A four-strain mixture of S. Typhimurium DT104, including strains 4698-K, 11942A1, 8748A1 and 62, which were previously described, was used. Each strain was grown in 10 ml of TSB held for 16 hours at 37° C. Bacteria were then sedimented by centrifugation (4000×g, 10 min), washed three times in 0.1% phosphate buffered saline, pH 7.2 (PBS) and then resuspended in PBS to an optical density of 0.5 at 640 nm (ca. 10 8 CFU/ml). The four S. Typhimurium DT104 strains were combined at equal populations. Two levels of inocula (10 3 and 10 5 CFU of S. Typhimurium DT104 per g of feces) were used. [0061] A four strain mixture of Salmonella enteritidis serovar Newport, including, strains S55, S57, S78, and S88, which were all characterized in this study, was used. The four-strain cell suspension was prepared according to the same procedures described above for S. Typhimurium DT104. Two levels of inocula (10 5 and 10 8 CFU of S. Newport per g of feces) were used. [0062] Feces. Ten healthy beef cattle over the age of one year were used as the sources of feces. Fecal samples, which were obtained in June, were collected into 50 ml Falcon tubes, and transported to the laboratory at 5° C. All samples were screened for Salmonella spp. by the procedure described above. All feces were mixed well in stomacher bags at medium speed for 5 minutes. [0063] Inoculation of the feces with S. Typhimurium DT104, S. Newport and competitive inhibition bacteria. The inocula of S. Typhimurium DT104 or S. Newport, and gram-negative competitive inhibition bacteria or gram-positive competitive inhibition bacteria (total 2 ml) mixtures at the appropriate dilution were added to 18 g of feces in sterile stomacher bags and mixed in a stomacher at medium speed for five minutes to obtain the desired bacterial concentrations. [0064] Fecal sample inoculations included, 10 5 S. Typhimurium DT104/g and 10 8 gram-negative competitive inhibition bacteria/g, 10 3 S. Typhimurium DT104/g and 10 5 gram-negative competitive inhibition bacteria/g, 105 S. Typhimurium DT104/g and 10 8 gram-positive competitive inhibition bacteria/g, 10 3 S. Typhimurium DT104/g and 10 5 gram-positive competitive inhibition bacteria/g, 105 S. Newport/g and 10 8 gram-positive competitive inhibition bacteria/g, and 10 3 S. Newport/g and 10 5 gram-positive competitive inhibition bacteria/g. Controls included both inoculation levels of gram-negative competitive inhibition bacteria, gram-positive competitive inhibition bacteria, S. Typhimurium DT104, S. Newport and total aerobic counts. [0065] Incubation and Sampling. Inoculated fecal samples were held under aerobic conditions at 21° and 37° C. Duplicate samples were obtained at 0, 1, 3, 5, 7, 14 and 21 days post-inoculation. Fecal samples (1 g) were serially diluted (1:10) in 0.1% peptone and assayed for S. Typhimurium DT104 or S. Newport counts by direct plating 0.1 ml portions onto XLD containing ampicillin (32 μg/ml), tetracycline (16 μg/ml) and streptomycin (64 μg/ml) (XLD+). Plates were incubated for 24 hours at 37° C. When Salmonella was not detectable by direct plating, 1 g samples of feces mixed with 0.1% peptone were added to 10 ml of double strength lactose broth for enrichment cultures at 35° C. for 24 hours. Enrichment cultures were subsequently plated onto XLD+ and incubated at 37° C. for 24 hours. Gram-negative competitive inhibition bacteria were enumerated by direct plating 0.1 ml portions onto MAC containing nalidixic acid (50 μg/ml). Plates were incubated for 24 hours at 37° C. Gram-positive competitive inhibition bacteria were enumerated by direct plating 0.1 ml portions onto TSA, incubating for 24 hours at 37° C., and subtracting total aerobic counts obtained for that day of the study. pH values were determined for 1 g fecal samples mixed with 9 ml of 0.1% peptone. All tests were performed in duplicate and the entire study was performed in triplicate. [0066] Statistical analysis. The Statistical Analysis System (SAS) computer statistical package (SAS Institute, Cary, N.C.) was used for analysis of data with Duncan's multiple range tests to determine if significant differences (P<0.05) in populations of S. Typhimurium DT104 exist between mean population values. [0000] Results [0067] The average initial aerobic plate count of the fecal samples was 2.6×10 9 CFU/g, and the average initial pH was 7.1. No Salmonella serovars were detected in the feces before inoculation. At 37° C., all the Salmonella populations increased about 2 log 10 CFU/g one-day post inoculation ( FIGS. 4A-4C , wherein open diamonds represent DT104, closed triangle represent S. Newport, low inoculum and open triangles represent S. Newport, high inoculum). No significant differences were observed with either of the inoculations of competitive inhibition bacteria against S. Typhimurium DT104 at both inoculation levels during the 21-day period ( FIGS. 4A and 4B , wherein open squares represent DT104 with gram-negative CI bacteria and closed circles represent DT104 with gram-positive CI bacteria). At 37° C., a significant difference (P>0.05) was observed with the low-level inoculations of gram-positive competitive inhibition isolates with S. Newport at days 3 and 5, and at the high level inoculation at day 21 ( FIG. 4C , wherein x represents S. Newport with gram-positive low inoculum and ζ represents S. Newport with gram-positive high inoculum). The pH of the feces increased slightly (ca. pH of Salmonella only−7.25, pH Salmonella and CI bacteria=7.58) for all samples during the incubation period. [0068] At 21° C., a population increase of 1 to 4 log 10 Salmonella /g was seen following the first day of growth ( FIGS. 5A-5C , wherein open diamonds represent DT104, closed triangle represent S. Newport, low inoculum and open triangles represent S. Newport, high inoculum). The low-level inoculation of gram-negative competitive inhibition bacteria did not significantly reduce (P>0.05) S. Typhimurium DT104 growth when compared to the control ( FIG. 5A , wherein open squares represent DT104 with gram-negative CI bacteria and closed circles represent DT104 with gram-positive CI bacteria). The high inoculation level of gram-negative competitive inhibition bacteria significantly reduced S. Typhimurium DT104 populations at day 5 only ( FIG. 5B , wherein open squares represent DT104 with gram-negative CI bacteria and closed circles represent DT104 with gram-positive CI bacteria). A significant reduction (P>0.05) of S. Typhimurium DT1 04 occurred at day five of the low inoculation level of gram-positive competitive inhibition bacteria. No significant reductions occurred at this temperature with the high inoculation level of gram-positive competitive inhibition bacteria. The gram-positive competitive inhibition bacteria did not significantly reduce (P>0.05) the growth/survival of S. Newport at 21° C. ( FIG. 5C , wherein x represents S. Newport with gram-positive low inoculum and ζ represents S. Newport with gram-positive high inoculum). The pH increase slightly for all Salmonella control samples (ca. pH=7.49), and decreased slightly for Salmonella and CI bacteria samples (ca. pH=7.02 ) during the incubation period. [0069] While the disclosure is susceptible to various modifications and alternative forms, specific exemplary embodiments thereof have been shown by way of example in the drawings and has herein be described in detail. It should be understood, however, that there is no intent to limit the disclosure to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure. [0070] There are a plurality of advantages of the present disclosure arising from the various features of the apparatus and methods described herein. It will be noted that alternative embodiments of the apparatus and methods of the present disclosure may not include all of the features described yet still benefit from at least some of the advantages of such features. Those of ordinary skill in the art may readily devise their own implementations of an apparatus and method that incorporate one or more of the features of the present disclosure and fall within the spirit and scope of the present disclosure.

Strains of pro-biotic bacteria, their isolation, characteristics and methods of use to prevent or treat carriage by a food production animal of Salmonella that causes human salmonellosis are provided. Methods for isolating and characterizing the probiotic bacteria are also provided. The present invention further provides methods for using the probiotic bacteria to prevent or treat Salmonella strains that cause human salmonellosis found in food production animals.

BACKGROUND OF THE INVENTION This invention relates generally to frequency measuring apparatus and more particularly to instantaneous frequency measurement (IFM) devices which are adapted for use in measuring the frequency of radio frequency signals. As is known in the art, instantaneous frequency measurement (IFM) devices are used in a variety of applications as where it is desired to measure the frequency of individual pulsed or continuous wave (CW) radio frequency input signals. These devices generally include a wide bandwidth radio frequency limiter circuit fed by the radio frequency input signals where the IFM device is to operate over a dynamic range of 50 dB or greater. The limited radio frequency signals are then fed to at least one delay line discriminator to provide an unambiguous measurement of the frequency of the input signals. Each delay line discriminator generally includes a power divider for separating the limited radio frequency signals into two quadrature channels, each channel having two electrical paths, the signal in one such path being delayed in phase with respect to the signal in the other path, such phase delay being related to the frequency of the input signals. The outputs of the two quadrature channels are combined and detected to form two baseband frequency output signals which have amplitudes which are proportional to the sine and cosine of the phase difference between the signals in the pairs of electrical paths and hence related to the frequency of the input signals. While such an IFM device is adequate for many applications, such devices are relatively expensive because of the large number of microwave devices included for power splitting, power combining and detection. Also, poor sensitivity results because of the large number of power splits prior to detection. For example, in an IFM device of the type discussed herein where say three delay line discriminators are used, each having a different ambiguity-free frequency range over the wide band of frequencies, only one-twelfth of the input power (less insertion losses) would be delivered to each one of twelve detectors. In addition, each detector is generally followed by its own baseband amplifier, thereby introducing additional baseband noise. Also, predetection noise due to the delay line included in the delay line discriminator and the quadrature channel signal combining is uncorrelated, each detector thereby increasing the baseband noise level. Further, because the microwave limiter fed by the input signal generally limits signals having moderately high signal levels, it is sometimes necessary to amplify the input signals to such high levels and then deliberately attenuate the limiter output to return to the range of the detectors, thereby increasing the cost of the IFM device. It is also noted that such an IFM device has numerous error sources, such as independent amplitude and phase error (frequency dependent) introduced by each power divider or power combiner and imperfections in the balance and matching of the detection. SUMMARY OF THE INVENTION With this background of the invention it is therefore an object of this invention to provide an improved instantaneous frequency measurement device adapted for use with radio frequency signals. This and other objects are attained generally by providing an instantaneous frequency measurement device comprising: Mixer means fed by an input signal and a reference signal for producing a pair of signals, such signals being the upper and lower sideband frequency signals separated by a fixed offset frequency, 2f o , related to the frequency of the reference signal; means, fed by the pair of signals, for providing a differential time delay between the upper and lower sideband frequency signals, shifting the phase of one of such sideband frequency signals an amount, -φ, related to the frequency of the input signal; and, means for combining and detecting the differentially time delayed upper and lower sideband frequency signals producing a signal having a frequency related to the frequency, 2f o , and a phase angle related to the amount of phase shift, -φ. BRIEF DESCRIPTION OF THE DRAWINGS The above-mentioned and other features of the invention will become more apparent by reference to the following description taken together in conjunction with the accompanying drawings, in which: FIG. 1 is a block diagram of an instantaneous frequency measurement device according to the invention; FIG. 2 is a curve useful in understanding the instantaneous frequency measurement device of FIG. 1; FIG. 3 is a block diagram of an alternative embodiment of an instantaneous frequency measurement device according to the invention; FIG. 4 is curves useful in understanding the instantaneous frequency measurement device of FIG. 3; and FIG. 5 is a logic section used in the IFM device of FIG. 3. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, an instantaneous frequency measurement device 10 is shown to include a single sideband modulator 12 adapted for coupling to a radio frequency input signal source 14 and a reference signal source 16, as shown. The device 10 is adapted to measure the frequency, f s , of the input signal produced by the source 14. The frequency f o of the reference signal produced by the source 16 is relatively small compared to the frequency f s . Here, for example, the frequency f o is 20 MHz and the frequency f s is a frequency in a band which extends from f L = 2500 MHz to f H = 4000 MHz. The single sideband modulator 12 includes a 2:1 power divider 18 which couples the input signal to a pair of mixers 20, 22, as shown. A 90° hybrid coupler 24 is provided to produce a pair of quadrature signals, e + (j2πf.sbsp.o t ) and e +j (2πf.sbsp.o t- π/2) to mixers 20, 22, respectively. It follows then that mixers 20, 22 produce a pair of signals, each having upper and lower sideband frequency signals separated by a fixed offset frequency, i.e. the frequency 2f o . The pair of signals is fed to a 90° hybrid coupler 25 to produce a pair of signals at output ports 26, 28 which may be represented as e.sup.+j[2π(f.sbsp.s.sup.+f.sbsp.o.sup.)t-π/2] and e +j [2πf.sbsp.s -f .sbsp.o.sup.)t], respectively. The signals produced by the single sideband modulator 12 are fed to a delay line and detector section 29, as shown. In particular, output port 28 is coupled to port 30 of 90° hybrid coupler 32 and port 26 is coupled to port 34 of such coupler 32 through a delay line 36. Here the electrical length of the delay line 36 is selected so that the phase of the signals at port 34 will change, linearly, through 2π radians as the frequency of the signal at such port 34 varies linearly over the frequency band B = f H -f L , here 1500 MHz (FIG. 2), that is, K = 2π/B, here 2π/(1500 × 10 6 ), the delay line length being 1/(1500 × 10 6 ). Generally, however, in order to avoid any undesired ambiguities at the extremes of the band, the phase shift will be made less than 2π radians over the band. It follows, then, that the phase of the signals at port 34 will be related (i.e. substantially proportionally) to the frequency of such signals (i.e. f s + f o ) and hence related (i.e. substantially linearly related) to the frequency of the input signal, i.e. the frequency f s . The signals at ports 34, 30 may be represented as e.sup.j2π[(f.sbsp.s.sup.+f.sbsp.o.sup.)t-π/2-φ] and e.sup.j[2π(f.sbsp.s.sup.-f.sbsp.o.sup.)t], respectively. That is, the delay line 36 provides a differential time delay between the upper sideband frequency signals (i.e. the signals at port 34) and the lower sideband frequency signals (i.e. the signals at port 30), shifting the phase of the upper sideband frequency signals an amount, -φ, related to (i.e. substantially linearly related to) the frequency, f s , of the input signal. The differentially delayed upper and lower sideband frequency signals are combined in the 90° hybrid coupler 32 to produce a pair of signals at ports 40, 42, which may be represented as: e.sup.+j[2π(f.sbsp.s.sup.-f.sbsp.o.sup.)t] + e.sup.+j[2π(f.sbsp.s.sup.+f.sbsp.o.sup.)t + π-φ] and e.sup.+j[2π(f.sbsp.s.sup.+f.sbsp.o.sup.)t-π/2-φ] + e.sup.+j[2π(f.sbsp.s.sup.-f.sbsp.o.sup.)t - π/2], respectively. The signals at ports 40, 42 are fed to detectors 44, 46 to produce a pair of signals which may be represented as e.sup.+j[2π(2f.sbsp.o.sup.)t + π-φ] and e.sup.+j[2π(2f.sbsp.o.sup.)t - φ], respectively. Additionally, DC components and harmonic components of 2f o are produced by the detector; however, as further described below, these are rejected for reasons to be discussed. It is noted that the desired output at frequency 2f o is obtained independent of the power law of the detector used. Therefore, either a square law or linear detector may be used for detectors 44, 46. It is noted that the signals at the outputs of detectors 44, 46 have the same frequency, 2f o , have a 180° phase difference and a phase -φ (or π-φ) which is a function of the frequency f s of the input signal, i.e. φ = -K (f.sub.s +f.sub.o) = -(2π/B) (f.sub.s +f.sub.o) where K is a proportionality constant related to the electrical length of the delay line 36. Further, the electrical length of the delay line 36 is selected so that the phase shift -φ varies nearly 2π radians over the operating band of the instantaneous frequency measurement device 10, (i.e. here 2500 to 4000 MHz), (FIG. 2). It is noted that the signals produced at the output of the delay line and detector section 29 have a relatively low frequency, i.e. 2f o , here 40 MHz, and therefore the remaining signal processing is accomplished using relatively low frequency, inexpensive components. The signals produced by the delay line and detector section 29 are fed to a differential amplifier and limiter section 50, as shown. Such section 50 includes a differential amplifier 52 fed by the signals produced at the outputs of detectors 44, 46, respectively, as shown. The differential amplifier 52 removes any DC or harmonic components of 2f o on the signals produced by detectors 44, 46 and reinforces the components having the frequency 2f o produced by such detectors. The signal produced at the output of differential amplifier 52 may be represented as e.sup.+j[2π(2f.sbsp.o.sup.)t - φ] The signal produced at the output of differential amplifier 52 is fed to a limiting amplifier 54, as shown. Such limiting amplifier 54 amplifies and limits the signals fed thereto to produce a constant amplitude signal, having the frequency 2f o , over a wide input signal level dynamic range, say a 50 dB or greater dynamic range. That is, the 90° hybrid coupler 32, detectors 44, 46, differential amplifier 52 and limiting amplifier 54 combine the differentially time delayed upper and lower sideband frequency signals at ports 30, 34, producing a signal at the output of limiting amplifier 54 which has a frequency 2f o related to the frequency of the reference signal and a phase angle related to the phase shift -φ, such phase shift -φ being related to the frequency, f s , of the input signal. The signal produced by the limiting amplifier 54 is fed to a phase comparator section 58. Also fed to such phase comparator section 58 is a signal having a frequency 2f o . Such signal having frequency 2f o is shown as being produced by passing the reference signal produced by source 16 through an ×2 frequency multiplier 60. The signal produced by multiplier 60 is fed to a phase shifter 61. Such phase shifter 61 provides a phase shift θ to such produced signal. Here θ = - 2π[(f L + f o )/B] radians. Therefore, the signal produced at the output of phase shifter 61 serves as a reference signal which is in phase with the signal produced at the output of limiter 54 at the frequency f L . Such reference signal has the same frequency as the signal produced by limiting amplifier 54 and is fed to phase comparator section 58 to produce a pair of DC signals having levels proportional to sin(-φ+θ) and cos(-φ+θ). In particular, referring to FIG. 1, phase comparator section 58 includes a 90° hybrid junction 62 fed by the limiting amplifier 54 to produce, at ports 64, 66, signals which may be represented as e.sup.+j[2π(2f.sbsp.o.sup.)t - π/2 - φ+θ] and e.sup.+j[2π(2f.sbsp.o.sup.)t - φ-θ], respectively. The signals at ports 64, 66 are fed to mixers 68, 70, respectively, as shown. The signal produced by phase shifter 61 is fed to mixers 68, 70 through 2:1 power divider 71, as shown. It follows then that the signals produced by mixers 68, 70, after passing through low pass filters 72, 74, respectively, may be represented as: sin(φ-θ) and cos(φ-θ), respectively. The signals produced by the phase comparator 58 are fed to a utilization device 75, here a computer which includes a pair of analog-to-digital converters (A/D converters) (not shown) for converting the signals produced by comparator 58 to corresponding digital words, and a read only memory (ROM) (not shown) which converts such digital words according to the equation ##EQU1## to produce a digital word representative of the phase angle (φ-θ) The computer, not shown, calculates the frequency of the input signal according to ##EQU2## where digital words representative of f o , f L and K are stored in such computer. The digital word representative of f s is here displayed on a conventional display, not shown, included in the utilization device 75. It is noted that the phase shift θ was added to enable the frequency f s to be f L when φ-θ = 0. Referring now to FIG. 3, an alternative embodiment of the invention is shown to include an instantaneous frequency measurement device 10'. It is noted that elements identical to those described in connection with FIG. 1 are shown with common numerical notation. The device 10' is designed to resolve the frequency of the source 14, i.e. the frequency f s , to a greater precision than obtainable with the IFM device 10 (FIG. 1). Here the IFM device 10' (FIG. 3) includes a delay line and detector section 29' which is fed by the single sideband modulator 12. The delay line and detector section 29' includes a pair of power dividers, here a pair of 2:1 power dividers 80, 82 coupled to ports 26, 28 of single sideband modulator 12 (FIG. 1), respectively as shown. A pair of signals produced at the output of power divider 80 is fed to a pair of delay lines 36, 36', as shown. Delay line 36 is identical to the delay line 36 of FIG. 1 and the characteristics of such delay line are shown again in FIG. 4 by the curve labeled 84. The electrical length of delay line 36' is selected so that the phase signals fed to such line will change, linearly, through nearly 4π radians as the frequency of such signal varies linearly over the frequency level B=f H -f L , here 2500 MHz to 4000 MHz. That is, ##EQU3## K 1 = 4π/B. The characteristics of such delay line 36' are shown in FIG. 4 by the line labeled 85. The signals produced by delay line 36 and at one output port of power divider 82 and the signals produced by delay line 36' and at the other output port of power divider 82 are fed to a pair of 90° hybrid junctions 32, 32', respectively, as shown. Hybrid junction 32 is coupled to a pair of detectors 44, 46, a differential amplifier and limiter network 50 and a phase comparator section 58 as discussed in connection with FIG. 1. The output of phase comparator section 58 therefore produces a pair of signals which may be represented as sin(φ-θ) and cos(φ-θ) as discussed. The signals produced at the output of hybrid junction 32' are fed to a pair of detectors 44', 46', a differential amplifier and limiter section 50' (equivalent to section 50) and a phase comparator section 58' (equivalent to section 58'). Also fed to phase comparator section 58' is a reference signal having a frequency 2f o and a phase angle θ 1 provided by phase shifter 61', such phase angle θ 1 being here θ.sub.1 = -4π[f.sub.l + f.sub.o)/b] radians. Therefore, the signal produced at the output of phase shifter 61' serves as a reference signal which is in phase with the signal produced at the output of differential amplifier and limiter section 50' at the frequency f L . The output of phase comparator section 58' therefore produces a pair of signals which may be represented as sin (φ.sub.1 -θ.sub.1) = sin [2(φ-θ)] cos (φ.sub.1 -θ.sub.1) = cos [2(φ-θ)] The signals produced by phase comparator 58' are fed to utilization device 75', here a computer which includes a pair of A/D converters (not shown) for converting the signals produced by comparators 58, 58' to corresponding digital words and a ROM (not shown) produces a pair of digital words representative of the phase angles (θ-φ) and (θ 1 -φ 1 ), respectively. The frequency f s is then calculated in the following manner: if [(φ-θ)/K] +f L -B/2 is positive the frequency f s = B/2 + [(φ 1 -θ 1 )/K 1 ]+f L and, if negative, f s = [(φ 1 -θ 1 )/K 1 ] +f L . Such calculation is here implemented in a logic section 90 (FIG. 5) which is included in utilization device 75'. A register 92 stores a digital word representative of B/2, a register 94 stores a digital word representative of [(φ-θ)/K]+f L , as calculated by the computer in utilization device 75' and a register 96 stores a digital word representative of [(φ 1 -θ 1 )/K 1 ]+f L as calculated by such computer. Register 92 is fed to a comparator 98 and to an adder 100. Register 94 is fed to comparator 98. Register 96 is fed to adder 100. The output of comparator 98 is fed to AND gate means 104 along with the output of the adder 100 and to the AND gate means 105 through inverter 107. The output of AND gate means 104 and 105 feed OR gate means 102. The output of OR gate means 102 feeds a display 106, as shown. Therefore, in operation, if the contents of register 94 are greater than (or equal to) the contents of register 92, the output of comparator 98 goes high and enables the output of adder 100 to pass to display 106. Conversely, if the contents of register 94 are less than the contents of register 92, the contents of register 96 pass to display 106. Having described preferred embodiments of the invention, numerous modifications and variations will now become readily apparent to those of skill in the art. For example, frequency bands other than the frequency band herein described may be used. Further, the frequency of a signal in a selected frequency band may be further resolved by similarly increasing the number of delay lines used in the delay line and detector section and appropriately increasing the number of sections 50, 58 and modify the utilization device 75. Further, a source 16 which produces a reference signal having a frequency 2f o may be used where the ×2 multiplier 60 is removed and a divide by 2 circuit is included between the reference signal source 16 and the reference signal to mixers 20, 22 (FIG. 1). It is felt, therefore, that the invention should not be restricted to the disclosed embodiments, but should be limited only by the spirit and scope of the appended claims.

Frequency measuring apparatus wherein a single sideband modulator is fed by an input signal, the frequency of which is to be determined, and a reference signal having a predetermined frequency f o to produce upper and lower sideband frequency signals separated in frequency by 2f o . A delay line shifts the phase of one of such signals φ relative to the other one of such signals, such phase shift being related to the frequency of the input signal. The signals are then combined and detected to produce a signal having a frequency 2f o and a phase angle related to the phase shift φ. A phase comparator, responsive to the reference signal and the later produced signal, detects the phase of the later signal thereby providing an indication of the frequency of the input signal. With such an arrangement relatively fewer and less costly devices may be used for the frequency measuring apparatus.

CROSS REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority from Taiwan patent application TW 103 124 194, filed Jul. 14, 2014, the contents of which are herein incorporated by reference. BACKGROUND OF THE INVENTION The present invention relates to a pulley for an alternator, and in particular, to a pulley for an automotive alternator. An alternator is a type of generator that can produce an alternating current by converting mechanical energy into electrical energy. An automotive alternator converts mechanical energy of an engine into electrical energy to charge a battery, so as to supply electrical power to other electrical appliances on the automobile, and start a motor to rotate the engine. An alternator generally has an annular stator and a rotor received in the annular stator. A wire is wound on the stator, and the rotor rotates rapidly in the stator so that the wire moves relative to a magnetic field generated by the rotor, and an induced electromotive force (voltage) is generated in the wire. An automotive alternator is usually utilized by an engine driving a belt. The belt is wound on a pulley, and the pulley is connected to a rotor so as to drive the rotor to rotate. However, in conventional alternator design, when an engine starts, or accelerates or decelerates quickly in an instant, a waveform changes significantly at the moment the generator charges a battery, and it cannot be stabilized. In addition, one side of the belt wound on the pulley is tight, and the other side thereof is slack. The tension of the slack-side belt is low, and therefore a tensioner is disposed thereon to adjust the tension of the belt. However, when a rotation speed at which the engine transmits power changes suddenly, because the pulley of the generator is locked by a nut and the belt is made of a flexible material and cannot reflect the rotation speed immediately, a slip is easily caused between the belt and the pulley. Moreover, the fluctuation of the rotation speed causes the belt to bear not only a repeated stress but also a centrifugal force that is applied on the belt when the pulley rotates. The value of the centrifugal force changes with the rotation speed, and therefore the belt is often affected by adverse factors of an internal micro tension, which pulls the belt, and external large-amplitude shaking. SUMMARY The present invention provides a pulley for an alternator, which includes an outer wheel, provided with an axle hole at the center; a clutch wheel, fixedly disposed in the axle hole of the outer wheel and having a pivot hole; a hollow connecting shaft, having a first end and a second end, where the first end is rotatably disposed in the pivot hole of the clutch wheel, so that the hollow connecting shaft maintains a co-rotational relationship with the outer wheel in a first relative rotation direction by means of the clutch wheel, while in a second relative rotation direction, the hollow connecting shaft is disassociated from the co-rotational relationship with the outer wheel, and presents an idling state; and the second end of the hollow connecting shaft is provided with a first protruding portion; a hollow core shaft, having a first end and a second end, where the hollow core shaft is rotatably received in the outer wheel, and the second end of the hollow core shaft is rotatably arranged at the second end of the hollow connecting shaft; the second end of the hollow core shaft is provided with a second protruding portion, and the second protruding portion corresponds to the first protruding portion; the number of one of the first protruding portion and the second protruding portion is at least one, and the number of the other of the first protruding portion and the second protruding portion is at least two; and an elastic element, disposed between the second end of the hollow connecting shaft and the second end of the hollow core shaft. When an external force drives the outer wheel to rotate, the outer wheel rotates relative to the hollow connecting shaft in the first relative rotation direction, and drives, through the clutch wheel, the hollow connecting shaft to rotate synchronously; the second end of the hollow connecting shaft presses the elastic element, and while being pressed, the elastic element pushes the second end of the hollow core shaft, thereby driving the hollow core shaft to rotate; and if a rotation angle of the hollow connecting shaft relative to the hollow core shaft exceeds a predetermined value at this time, the first protruding portion of the hollow connecting shaft contacts the second protruding portion of the hollow core shaft, thereby stopping relative rotation between the hollow connecting shaft and the hollow core shaft, so as to prevent the elastic element from being pressed excessively, and to set the hollow connecting shaft and the hollow core shaft in a synchronous co-rotational relationship. When the external force decreases or stops driving the outer wheel to rotate, the hollow core shaft continues to rotate due to inertia, and stretches the elastic element, and while being stretched, the elastic element pulls the second end of the hollow connecting shaft, thereby driving the hollow connecting shaft to rotate relative to the outer wheel in the second relative rotation direction, so that the hollow connecting shaft is disassociated from the co-rotational relationship with the outer wheel, and idles in the clutch wheel; and if a rotation angle of the hollow connecting shaft relative to the hollow core shaft exceeds a predetermined value at this time, the first protruding portion of the hollow connecting shaft contacts the second protruding portion of the hollow core shaft, thereby stopping relative rotation between the hollow connecting shaft and the hollow core shaft, so as to prevent the elastic element from being stretched excessively, and to set the hollow connecting shaft and the hollow core shaft in a synchronous co-rotational relationship. According to another preferred embodiment of the present invention, the hollow core shaft passes through the hollow connecting shaft, and the first end of the hollow core shaft protrudes from the first end of the hollow connecting shaft; a tight-fit component is sleeved over an outer circumferential wall surface of the first end of the hollow core shaft in a tight-fit manner, and the tight-fit component is also tightly fit with an end surface of the first end of the hollow connecting shaft; therefore, the hollow connecting shaft and the hollow core shaft are made to corotate coaxially under a friction between the tight-fit component and the hollow connecting shaft and a friction between the tight-fit component and the hollow core shaft, and when the external force decreases or stops driving the outer wheel to rotate, the hollow core shaft continues to rotate due to inertia, and drives, through the tight-fit component, the hollow connecting shaft to rotate relative to the outer wheel in the second relative rotation direction, so that the hollow connecting shaft is disassociated from the co-rotational relationship with the outer wheel and idles in the clutch wheel. According to another preferred embodiment of the present invention, the tight-fit component is a C-shaped retaining ring. According to another preferred embodiment of the present invention, a first ball bearing is sleeved over the first end of the hollow core shaft, a second ball bearing is sleeved over the second end of the hollow core shaft, and the first ball bearing and the second ball bearing are disposed between the hollow core shaft and the outer wheel, so that the hollow core shaft is rotatable relative to the outer wheel. According to another preferred embodiment of the present invention, three grooves are provided in a concave manner on an inner circumferential wall surface of the outer wheel, and an anaerobic adhesive is coated in the grooves, so that the clutch wheel, the first ball bearing, and the second ball bearing are separately tightly fit in the grooves, and are fixedly glued in the outer wheel by using the anaerobic adhesive. According to another preferred embodiment of the present invention, a positioning casing is further sleeved over the first ball bearing, and an axial position of the pulley on the alternator is limited by the positioning casing. According to another preferred embodiment of the present invention, an outer circumferential wall surface of the outer wheel is provided with a belt groove, for a belt to be wound on. According to another preferred embodiment of the present invention, the belt is connected to a mechanical energy generating source, and the mechanical energy generating source provides an external force to drive the belt, thereby driving the outer wheel to rotate. According to another preferred embodiment of the present invention, the mechanical energy generating source is an engine. According to another preferred embodiment of the present invention, an inner circumferential wall surface of the hollow core shaft is provided with a threaded surface, the threaded surface is screwed with a joint lever having corresponding threads, and the joint lever is connected to a rotor, so that the hollow core shaft and the rotor corotate synchronously. According to another preferred embodiment of the present invention, an inner circumferential wall surface of the outer wheel is provided with a step portion, for the clutch wheel to abut against, thereby limiting an axial displacement of the clutch wheel. According to another preferred embodiment of the present invention, one end of the clutch wheel is provided with a positioning member, to limit an axial position of the clutch wheel, and the positioning member is a C-shaped retaining ring. According to another preferred embodiment of the present invention, the elastic element is a torque spring, and a wire profile of the torque spring is circular, elliptical, or rectangular. According to another preferred embodiment of the present invention, when the wire profile of the torque spring is rectangular, two end surfaces of the torque spring are grinded, so as to enhance axial positioning of the torque spring and control a free length of the torque spring more precisely. According to another preferred embodiment of the present invention, two sides of the clutch wheel are each provided with an oil seal element, so as to prevent liquid in the clutch wheel from flowing into the outer wheel. According to another preferred embodiment of the present invention, one side of one of the oil seal elements is provided with a positioning member, and the positioning member is sleeved over an inner side wall surface of the outer wheel in a tight-fit manner, to limit axial positions of the oil seal elements. According to another preferred embodiment of the present invention, the positioning member is a C-shaped retaining ring. According to another preferred embodiment of the present invention, an end, corresponding to the second end of the hollow core shaft, of the outer wheel is arranged with a dust cover, so as to prevent external dust from entering the outer wheel. The present invention further provides a pulley for an alternator, which includes an outer wheel, provided with an axle hole at the center; a clutch wheel, fixedly disposed in the axle hole of the outer wheel and having a pivot hole; a hollow connecting shaft, having a first end and a second end, where the first end is rotatably disposed in the pivot hole of the clutch wheel, so that the hollow connecting shaft maintains a co-rotational relationship with the outer wheel in a first relative rotation direction by means of the clutch wheel, while in a second relative rotation direction, the hollow connecting shaft is disassociated from the co-rotational relationship with the outer wheel, and presents an idling state; and the second end of the hollow connecting shaft is provided with a first protruding portion; a hollow core shaft, having a first end and a second end, where the hollow core shaft is rotatably received in the outer wheel, and the hollow core shaft passes through the hollow connecting shaft; the first end of the hollow core shaft protrudes from the first end of the hollow connecting shaft, and the second end of the hollow core shaft is rotatably arranged on the second end of the hollow connecting shaft; the second end of the hollow core shaft is provided with a second protruding portion, and the second protruding portion corresponds to the first protruding portion; the number of one of the first protruding portion and the second protruding portion is at least one, and the number of the other of the first protruding portion and the second protruding portion is at least two; an elastic element, disposed between the second end of the hollow connecting shaft and the second end of the hollow core shaft; and a tight-fit component, sleeved over an outer circumferential wall surface of the first end of the hollow core shaft in a tight-fit manner and tightly fit with an end surface of the first end of the hollow connecting shaft, so that the hollow connecting shaft and the hollow core shaft corotate coaxially under a friction between the tight-fit component and the hollow connecting shaft and a friction between the tight-fit component and the hollow core shaft. When an external force drives the outer wheel to rotate, the outer wheel rotates relative to the hollow connecting shaft in the first relative rotation direction, and drives, through the clutch wheel, the hollow connecting shaft to rotate synchronously, and the hollow connecting shaft drives, through the tight-fit component, the hollow core shaft to rotate; if the friction provided by the tight-fit component is insufficient to drive the hollow core shaft to rotate at this time, the second end of the hollow connecting shaft presses the elastic element, and while being pressed, the elastic element pushes the second end of the hollow core shaft, thereby driving the hollow core shaft to rotate; and if a rotation angle of the hollow connecting shaft relative to the hollow core shaft exceeds a predetermined value at this time, the first protruding portion of the hollow connecting shaft contacts the second protruding portion of the hollow core shaft, thereby stopping relative rotation between the hollow connecting shaft and the hollow core shaft, so as to prevent the elastic element from being pressed excessively, and to set the hollow connecting shaft and the hollow core shaft in a synchronous co-rotational relationship. When the external force decreases or stops driving the outer wheel to rotate, the hollow core shaft continues to rotate due to inertia, and drives, through the tight-fit component, the hollow connecting shaft to rotate relative to the outer wheel in the second relative rotation direction; and if the friction provided by the tight-fit component is insufficient to drive the hollow connecting shaft to rotate at this time, the hollow core shaft rotates relative to the hollow connecting shaft until the first protruding portion of the hollow connecting shaft contacts the second protruding portion of the hollow core shaft, thereby stopping relative rotation between the hollow connecting shaft and the hollow core shaft, and setting the hollow connecting shaft and the hollow core shaft in a synchronous co-rotational relationship. According to another preferred embodiment of the present invention, when the external force decreases or stops driving the outer wheel to rotate, the hollow core shaft continues to rotate due to inertia, and drives, through the tight-fit component, the hollow connecting shaft to rotate relative to the outer wheel in the second relative rotation direction; if the friction provided by the tight-fit component is insufficient to drive the hollow connecting shaft to rotate at this time, the hollow core shaft stretches the elastic element, and while being stretched, the elastic element pulls the second end of the hollow connecting shaft, thereby driving the hollow connecting shaft to rotate relative to the outer wheel in the second relative rotation direction, so that the hollow connecting shaft is disassociated from the co-rotational relationship with the outer wheel; and if a rotation angle of the hollow connecting shaft relative to the hollow core shaft exceeds a predetermined value, the protruding portion of the hollow connecting shaft contacts the protruding portion of the hollow core shaft, thereby stopping relative rotation between the hollow connecting shaft and the hollow core shaft, so as to prevent the elastic element from being stretched excessively, and to set the hollow connecting shaft and the hollow core shaft in a synchronous co-rotational relationship. According to another preferred embodiment of the present invention, the tight-fit component is a C-shaped retaining ring. According to another preferred embodiment of the present invention, a first ball bearing is sleeved over the first end of the hollow core shaft, a second ball bearing is sleeved over the second end of the hollow core shaft, and the first ball bearing and the second ball bearing are disposed between the hollow core shaft and the outer wheel, so that the hollow core shaft is rotatable relative to the outer wheel. According to another preferred embodiment of the present invention, three grooves are provided in a concave manner on an inner circumferential wall surface of the outer wheel, and an anaerobic adhesive is coated in the grooves, so that the clutch wheel, the first ball bearing, and the second ball bearing are separately tightly fit in the grooves, and are fixedly glued in the outer wheel by using the anaerobic adhesive. According to another preferred embodiment of the present invention, a positioning casing is further sleeved over the first ball bearing, and an axial position of the pulley on the alternator is limited by the positioning casing. According to another preferred embodiment of the present invention, an outer circumferential wall surface of the outer wheel is provided with a belt groove, for a belt to be wound on. According to another preferred embodiment of the present invention, the belt is connected to a mechanical energy generating source, and the mechanical energy generating source provides an external force to drive the belt, thereby driving the outer wheel to rotate. According to another preferred embodiment of the present invention, the mechanical energy generating source is an engine. According to another preferred embodiment of the present invention, an inner circumferential wall surface of the hollow core shaft is provided with a threaded surface, the threaded surface is screwed with a joint lever having corresponding threads, and the joint lever is connected to a rotor, so that the hollow core shaft and the rotor corotate synchronously. According to another preferred embodiment of the present invention, an inner circumferential wall surface of the outer wheel is provided with a step portion, for the clutch wheel to abut against, thereby limiting an axial displacement of the clutch wheel. According to another preferred embodiment of the present invention, one end of the clutch wheel is provided with a positioning member, to limit an axial position of the clutch wheel, and the positioning member is a C-shaped retaining ring. According to another preferred embodiment of the present invention, the elastic element is a torque spring, and a wire profile of the torque spring is circular, elliptical, or rectangular. According to another preferred embodiment of the present invention, when the wire profile of the torque spring is rectangular, two end surfaces of the torque spring are grinded, so as to enhance axial positioning of the torque spring and control a free length of the torque spring more precisely. According to another preferred embodiment of the present invention, two sides of the clutch wheel are each provided with an oil seal element, so as to prevent liquid in the clutch wheel from flowing into the outer wheel. According to another preferred embodiment of the present invention, one side of one of the oil seal elements is provided with a positioning member, and the positioning member is sleeved over an inner side wall surface of the outer wheel in a tight-fit manner, to limit axial positions of the oil seal elements. According to another preferred embodiment of the present invention, the positioning member is a C-shaped retaining ring. According to another preferred embodiment of the present invention, an end, corresponding to the second end of the hollow core shaft, of the outer wheel is arranged with a dust cover, so as to prevent external dust from entering the outer wheel. The present invention further provides an alternator having the pulley according to the present invention. According to another preferred embodiment of the present invention, the alternator is used on a vehicle. For better understanding of the detailed description of the present invention, the features and technical advantages of the present invention are described generally above. The following describes the additional features and advantages of the present invention. Persons skilled in the art should be aware that the disclosed concept and specific implementation manner can be easily used as a basis for modifying or designing other structures for implementing objectives the same as the present invention. Persons skilled in the art should also be aware that such equivalent structures do not depart from the spirit and scope of the present invention which are claimed in the patent application scope. BRIEF DESCRIPTION OF THE DRAWINGS For a more thorough understanding of the present invention and advantages of the present invention, the following descriptions are provided with reference to the accompanying drawings, where: FIG. 1 is a three-dimensional exploded view of a pulley for an alternator according to the present invention; FIG. 2 is a sectional assembled view of a pulley for an alternator according to the present invention; FIG. 3 is a schematic structural view of a hollow connecting shaft according to the present invention; FIG. 4 is a schematic structural view of a hollow core shaft according to the present invention; and FIG. 5 is a schematic view of a rotor of an alternator according to the present invention. MEANING OF REFERENCE NUMERALS 10 Pulley 20 Joint lever 30 Rotor 110 Outer wheel 111 Axle hole 112 Belt groove 113 Step portion 120 Clutch wheel 121 Pivot hole 122 Housing 123 Rolling member 124 Elastic member 125 Cap 130 Hollow connecting shaft 131 First end of the hollow connecting shaft 132 Second end of the hollow connecting shaft 133 First protruding portion 134 Stop wall of the hollow connecting shaft 140 Hollow core shaft 141 First end of the hollow core shaft 142 Second end of the hollow core shaft 143 First ball bearing 144 Second ball bearing 145 Protruding ring of the hollow core shaft 146 Second protruding portion 147 Stop wall of the hollow core shaft 148 Threaded surface 150 Elastic element 160 Tight-fit component 161 Positioning gasket 162 C-shaped retaining ring 170 Positioning casing 171 Protruding ring of the positioning casing 181 Oil seal element 182 Oil seal element 183 Positioning member 184 Dust cover 185 Positioning member DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS The following embodiments describe the present invention in further detail. The embodiments are merely used to describe the present invention and illustrate the advantages of specific embodiments of the present invention, but it does not mean that the present invention is limited to such implementations. FIG. 1 and FIG. 2 are respectively a three-dimensional exploded view and a sectional assembled view of a pulley for an alternator according to the present invention. As shown in FIG. 1 and FIG. 2 , a pulley 10 for an alternator according to the present invention mainly includes an outer wheel 110 , a clutch wheel 120 , a hollow connecting shaft 130 , a hollow core shaft 140 , an elastic element 150 , and a tight-fit component 160 . The outer wheel 110 is a wheel-shaped member provided with an axle hole 111 at the center, and is provided with a belt groove 112 on an outer circumferential wall surface thereof and a step portion 113 on an inner circumferential wall surface thereof. The clutch wheel 120 is annular, provided with a pivot hole 121 at the center, and fixedly disposed in the axle hole 111 of the outer wheel 110 . For example, a groove may be provided in a concave manner on the inner circumferential wall surface of the outer wheel 110 , and an anaerobic adhesive is coated in the groove so that the clutch wheel 120 can be fixedly connected to an inner circumferential wall surface of the axle hole 111 of the outer wheel 110 by means of tight fit and adhesion of the anaerobic adhesive. One end of the clutch wheel 120 abuts against the step portion 113 of the outer wheel 110 to limit an axial position of the clutch wheel 120 and to ensure that an end surface of the clutch wheel 120 is perpendicular to the hollow connecting shaft 130 and the hollow core shaft 140 , prevent axial displacement of the clutch wheel 120 during high-speed rotation, and moreover, provide an axial positioning reference during assembly of components in the outer wheel 110 , which facilitates positioning during the assembly. The hollow connecting shaft 130 has a first end 131 and a second end 132 . The first end 131 is rotatably disposed in the clutch wheel 120 so that the hollow connecting shaft 130 can maintain a co-rotational relationship with the outer wheel 110 in a first relative rotation direction by means of the clutch wheel 120 (for example, the hollow connecting shaft 130 rotates anticlockwise relative to the outer wheel 110 ), and it is disassociated from the co-rotational relationship with the outer wheel 110 in a second relative rotation direction to enter an idling state (for example, the hollow connecting shaft 130 rotates clockwise relative to the outer wheel 110 ), and at this time, the hollow connecting shaft 130 rotates independently of the outer wheel 110 . The hollow connecting shaft 130 is provided with a first protruding portion 133 on the second end 132 , as shown in FIG. 3 . In a preferred embodiment of the present invention, the clutch wheel 120 has a housing 122 , a plurality of rolling members 123 , a plurality of elastic members 124 , and two caps 125 . The clutch wheel 120 is provided with a positioning member 185 on an end opposite to the end abutting against the step portion 113 to limit the axial position of the clutch wheel 120 and prevent the caps 125 of the clutch wheel 120 from falling off. The positioning member may be a C-shaped retaining ring. For the detailed structure and operating principle of the clutch wheel 120 , reference may be made to Taiwan Patent Application No. 098129945 filed by the applicant on Sep. 4, 2009. However, the clutch wheel of the present invention is not limited thereto, and any speed-difference clutch apparatus capable of implementing the functions of the clutch wheel 120 described in the present invention may be designed as the clutch wheel 120 of the present invention. Moreover, in the present invention, two ends of the clutch wheel 120 are each provided with an oil seal element 181 / 182 so as to prevent a liquid (for example, a lubricating oil) in the clutch wheel 120 from permeating and polluting the interior of the pulley 10 . Furthermore, a positioning member 183 may be sleeved over one side of the oil seal element 182 . The positioning member 183 may be a C-shaped retaining ring, and may be sleeved over an inner side wall surface of the outer wheel 110 in a tight-fit manner, to limit axial positions of the oil seal elements 181 and 182 and the clutch wheel 120 . The hollow core shaft 140 is disposed in the outer wheel 110 and has a first end 141 and a second end 142 . A first ball bearing 143 is sleeved over the first end 141 , and a second ball bearing 144 is sleeved over the second end 142 . The first ball bearing 143 and the second ball bearing 144 are both fixedly connected to the inner circumferential wall surface of the outer wheel 110 (for example, the outer wheel 110 may be provided with two grooves on the inner circumferential wall surface in a concave manner, and an anaerobic adhesive is coated in the grooves so that the first ball bearing 143 and the second ball bearing 144 can be fixedly connected to the inner circumferential wall surface of the axle hole 111 of the outer wheel 110 by means of tight fit and adhesion of the anaerobic adhesive) so that the hollow core shaft 140 is rotatable relative to the outer wheel 110 . In addition, the hollow core shaft 140 passes through the hollow connecting shaft 130 , and the first end 141 of the hollow core shaft 140 protrudes from the first end 131 of the hollow connecting shaft 130 . A protruding ring 145 is annularly arranged at the second end 142 of the hollow core shaft 140 . The protruding ring 145 is rotatably arranged on the second end 132 of the hollow connecting shaft 130 . A second protruding portion 146 is provided in a protruding manner in a direction towards the hollow connecting shaft 130 , and the second protruding portion 146 corresponds to the first protruding portion 133 so that after the hollow connecting shaft 130 and the hollow core shaft 140 rotate by a particular degree relative to each other, the first protruding portion 133 of the hollow connecting shaft 130 contacts the second protruding portion 146 of the hollow core shaft 140 , thereby stopping relative rotation between the hollow connecting shaft 130 and the hollow core shaft 140 . For example, when the hollow connecting shaft 130 is provided with two first protruding portions 133 at the second end 132 , and when the hollow core shaft 140 is provided with three second protruding portions 146 at the second end 142 , the hollow core shaft 140 can only rotate clockwise or anticlockwise by 120 degrees relative to the hollow connecting shaft 130 after being sleeved over the hollow connecting shaft 130 because relative rotation between the hollow connecting shaft 130 and the hollow core shaft 140 is stopped when the first protruding portions 133 contact the second protruding portions 146 . The elastic element 150 is disposed between the second end 132 of the hollow connecting shaft 130 and the second end 142 of the hollow core shaft 140 . In a preferred embodiment of the present invention, the elastic element is a torque spring, and a wire profile of the torque spring may be circular, elliptical, or rectangular. When the wire profile of the torque spring is rectangular, two end surfaces of the torque spring may be grinded so as to enhance an axial positioning capability of the torque spring and control a free length of the spring more precisely. The hollow connecting shaft 130 is provided with a stop wall 134 in a concave manner on an inner circumferential wall surface of the second end 132 (as shown in FIG. 3 ) so that one end of the elastic element 150 can abut against the stop wall 134 , and the elastic element 150 may also be fixedly connected to the stop wall 134 . In addition, The hollow core shaft 140 is also provided with a stop wall 147 on an inner side of the protruding ring 145 of the second end 142 (as shown in FIG. 4 ) so that the other end of the elastic element 150 can abut against the stop wall 147 , and the elastic element 150 may also be fixedly connected to the stop wall 147 . When the two ends of the elastic element 150 are fixedly connected to the stop wall 134 of the hollow connecting shaft 130 and the stop wall 147 of the hollow core shaft 140 , relative rotation between the hollow connecting shaft 130 and the hollow core shaft 140 presses or stretches the elastic element 150 ; when the two ends of the elastic element 150 merely abut against but are not fixedly connected to the stop wall 134 of the hollow connecting shaft 130 or the stop wall 147 of the hollow core shaft 140 , relative rotation between the hollow connecting shaft 130 and the hollow core shaft 140 only presses the elastic element 150 . The tight-fit component 160 is a C-shaped retaining ring; the C-shaped retaining ring is sleeved over the outer circumferential wall surface of the first end 141 of the hollow core shaft 140 in a tight-fit manner, and is tightly fit with a tail end surface of the first end 131 of the hollow connecting shaft 130 . Therefore, under a friction between the tight-fit component 160 and the end surface of the first end 131 of the hollow connecting shaft 130 and a friction between the tight-fit component 160 and the outer circumferential wall surface of the first end 141 of the hollow core shaft 140 , the hollow connecting shaft 130 and the hollow core shaft 140 drive each other and corotate coaxially, as shown in FIG. 3 . A positioning casing 170 is further sleeved over the first ball bearing 143 , and the positioning casing 170 is a hollow annular pipe provided with a protruding ring 171 at one end; therefore, the protruding ring 171 penetrates the first ball bearing 143 and provides an abutting and cushioning function when the pulley 10 is installed on an alternator, and an axial position of the pulley 10 on the alternator is limited by the positioning casing 170 . The hollow core shaft 140 is provided with a threaded surface 148 on an inner circumferential wall surface thereof, the threaded surface 148 may be screwed with a joint lever 20 having corresponding threads, and the joint lever 20 is connected to a rotor 30 of the alternator so that the hollow core shaft 140 and the rotor 30 corotate synchronously (as shown in FIG. 5 ). In addition, an end, corresponding to the second end 142 of the hollow core shaft 140 , of the outer wheel 110 is arranged with a dust cover 184 so as to prevent external dust from entering the outer wheel 110 . With the structure described above, when a mechanical energy generating source provides an external force to drive the outer wheel 110 to rotate, the outer wheel 110 rotates relative to the hollow connecting shaft 130 in the first relative rotation direction and drives, through the clutch wheel 120 , the hollow connecting shaft 130 to rotate synchronously, and with the friction provided by the tight-fit component 160 , the hollow connecting shaft 130 drives the hollow core shaft 140 to rotate. At this time, if the friction provided by the tight-fit component 160 is insufficient to drive the hollow core shaft 140 to rotate, the hollow connecting shaft 130 rotates relative to the hollow core shaft 140 , which causes the stop wall 134 at the second end 132 of the hollow connecting shaft 130 to press the elastic element 150 , and while being pressed, the elastic element 150 pushes the stop wall 147 at the second end 142 of the hollow core shaft 140 , thereby driving the hollow core shaft 140 to rotate. At this time, if a relative rotation angle between the hollow connecting shaft 130 and the hollow core shaft 140 exceeds a predetermined value (for example, 120 degrees), the first protruding portion 133 of the hollow connecting shaft 130 contacts the second protruding portion 146 of the hollow core shaft 140 , thereby stopping relative rotation between the hollow connecting shaft 130 and the hollow core shaft 140 so as to avoid pressing the elastic element 150 excessively and damaging the structure thereof, and to set the hollow connecting shaft 130 and the hollow core shaft 140 in a synchronous co-rotational relationship; the hollow core shaft 140 also drives the rotor 30 to rotate so that the alternator generates an induced current. In addition, if the outer wheel 110 is originally in a rotation state, when the mechanical energy generating source provides an external force to accelerate the rotation of the outer wheel 110 , an operating principle of the pulley 10 of the present invention is substantially the same as the aforementioned operating principle in the case of starting the outer wheel 110 to rotate, and therefore it is not repeated herein. On the contrary, when the external force stops driving the outer wheel 110 to rotate, the hollow core shaft 140 continues to rotate due to inertia of the rotor 30 . At this time, the hollow core shaft 140 drives, by using the friction provided by the tight-fit component 160 , the hollow connecting shaft 130 to rotate relative to the outer wheel 110 in the second relative rotation direction so that the hollow connecting shaft 130 is disassociated from the co-rotational relationship with the outer wheel 110 . At this time, if the friction provided by the tight-fit component 160 is insufficient to drive the hollow connecting shaft 130 to rotate, the hollow core shaft 140 rotates relative to the hollow connecting shaft 130 ; if the elastic element 150 merely abuts against but is not fixedly connected to the hollow connecting shaft 130 and the hollow core shaft 140 , the hollow core shaft 140 keeps rotating relative to the hollow connecting shaft 130 until the second protruding portion 146 of the hollow core shaft 140 contacts the first protruding portion 133 of the hollow connecting shaft 130 , thereby stopping relative rotation between the hollow connecting shaft 130 and the hollow core shaft 140 and setting the hollow connecting shaft 130 and the hollow core shaft 140 in a synchronous co-rotational relationship so that the hollow connecting shaft 130 and the hollow core shaft 140 rotate relative to the outer wheel 110 in the second relative rotation direction. If the elastic element 150 is fixedly connected to the hollow connecting shaft 130 and the hollow core shaft 140 , when the friction provided by the tight-fit component 160 is insufficient to drive the hollow connecting shaft 130 to rotate, the hollow core shaft 140 rotates relative to the hollow connecting shaft 130 and stretches the elastic element 150 , and while being stretched, the elastic element 150 pulls the second end 132 of the hollow connecting shaft 130 , thereby driving the hollow connecting shaft 130 to rotate relative to the outer wheel 110 in the second relative rotation direction so that the hollow connecting shaft 130 is disassociated from the co-rotational relationship with the outer wheel 110 . At this time, if rotation of the hollow connecting shaft 130 relative to the hollow core shaft 140 exceeds a predetermined value (for example, 120 degrees), the first protruding portion 133 of the hollow connecting shaft 130 contacts the second protruding portion 146 of the hollow core shaft 140 , thereby stopping relative rotation between the hollow connecting shaft 130 and the hollow core shaft 140 so as to avoid stretching the elastic element 150 excessively and damaging the structure thereof, and to set the hollow connecting shaft 130 and the hollow core shaft 140 in a synchronous co-rotational relationship so that the hollow connecting shaft 130 and the hollow core shaft 140 rotate relative to the outer wheel 110 in the second relative rotation direction. In addition, if the external force driving the outer wheel 110 decreases, the operating principle of the pulley 10 of the present invention is substantially the same as the aforementioned operating principle in the case in which the outer wheel 110 stops rotating, and therefore it is not repeated herein. In the pulley 10 of the present invention, a belt (not shown in the figure) may be wound on the belt groove 112 of the outer wheel 110 so that the mechanical energy generating source can provide an external force to drive the belt, thereby driving the outer wheel 110 to rotate. In addition, the pulley 10 of the present invention is applicable to an alternator system, such as a power generation system and an alternator system of a vehicle. The pulley of the present invention is especially suitable to be used as a stator structure of an automotive alternator. When the pulley of the present invention is applied to an automotive alternator, the mechanical energy generating source is an automobile engine. In a preferred embodiment of the present invention, the tight-fit component 160 of the pulley 10 of the present invention may be omitted, and two ends of the elastic element 150 are fixedly connected to the stop wall 147 at the second end 142 of the hollow core shaft 140 and the stop wall 134 at the second end 132 of the hollow connecting shaft 130 . In this manner, when an external force drives the outer wheel 110 to rotate, the outer wheel 110 rotates relative to the hollow connecting shaft 130 in the first relative rotation direction and drives, through the clutch wheel 120 , the hollow connecting shaft 130 to rotate synchronously; the second end 132 of the hollow connecting shaft 130 presses the elastic element 150 , and while being pressed, the elastic element 150 pushes the stop wall 147 at the second end 142 of the hollow core shaft 140 , thereby driving the hollow core shaft 140 to rotate. At this time, if a rotation angle of the hollow connecting shaft 130 relative to the hollow core shaft 140 exceeds a predetermined value, the first protruding portion 133 of the hollow connecting shaft 130 contacts the second protruding portion 146 of the hollow core shaft 140 , thereby stopping relative rotation between the hollow connecting shaft 130 and the hollow core shaft 140 so as to prevent the elastic element 150 from being pressed excessively, setting the hollow connecting shaft 130 and the hollow core shaft 140 in a synchronous co-rotational relationship, and drive the rotor 30 to rotate. On the contrary, when the external force decreases or stops driving the outer wheel 110 to rotate, the hollow core shaft 140 continues to rotate due to inertia of the rotor 30 and stretches the elastic element 150 , and while being stretched, the elastic element 150 pulls the second end 132 of the hollow connecting shaft 130 , thereby driving the hollow connecting shaft 130 to rotate relative to the outer wheel 110 in the second relative rotation direction so that the hollow connecting shaft 130 is disassociated from the co-rotational relationship with the outer wheel 110 and idles in the clutch wheel 120 . At this time, if a rotation angle of the hollow connecting shaft 130 relative to the hollow core shaft 140 exceeds a predetermined value, the first protruding portion 133 of the hollow connecting shaft 130 contacts the second protruding portion 146 of the hollow core shaft 140 , thereby stopping relative rotation between the hollow connecting shaft 130 and the hollow core shaft 140 so as to prevent the elastic element 150 from being stretched excessively, and to set the hollow connecting shaft 130 and the hollow core shaft 140 in a synchronous co-rotational relationship, in which the hollow connecting shaft 130 and the hollow core shaft 140 idle in the outer wheel 110 . In addition, in a preferred embodiment of the present invention, in the pulley 10 of the present invention, the first protruding portion 133 and the second protruding portion 146 may not be disposed, the protruding ring 145 at the second end 142 of the hollow core shaft 140 is directly sleeved over the second end 132 of the hollow connecting shaft 130 , and two ends of the elastic element 150 are fixedly connected to the stop wall 147 at the second end 142 of the hollow core shaft 140 and the stop wall 134 at the second end 132 of the hollow connecting shaft 130 . Therefore, when an external force drives the outer wheel 110 to rotate, the outer wheel 110 rotates relative to the hollow connecting shaft 130 in the first relative rotation direction and drives, through the clutch wheel 120 , the hollow connecting shaft 130 to rotate synchronously, and the hollow connecting shaft 130 drives, through the tight-fit component 160 , the hollow core shaft 140 to rotate. At this time, if the friction provided by the tight-fit component 160 is insufficient to drive the hollow core shaft 140 to rotate, the stop wall 134 at the second end 132 of the hollow connecting shaft 130 presses the elastic element 150 , and while being pressed, the elastic element 150 pushes the stop wall 147 at the second end 142 of the hollow core shaft 140 , thereby driving the hollow core shaft 140 to rotate, so as to drive the rotor 30 of the alternator to rotate. On the contrary, when the external force decreases or stops driving the outer wheel 110 to rotate, the hollow core shaft 140 continues to rotate due to inertia of the rotor 30 and drives, through the tight-fit component 160 , the hollow connecting shaft 130 to rotate relative to the outer wheel 110 in the second relative rotation direction. At this time, if the friction provided by the tight-fit component 160 is insufficient to drive the hollow connecting shaft 130 to rotate, the hollow core shaft 140 stretches the elastic element 150 , and while being stretched, the elastic element 150 pulls the second end 132 of the hollow connecting shaft 130 , thereby driving the hollow connecting shaft 130 to rotate relative to the outer wheel 110 in the second relative rotation direction so that the hollow connecting shaft 130 is disassociated from the co-rotational relationship with the outer wheel 110 and idles in the clutch wheel 120 . Further, in a preferred embodiment of the present invention, in the pulley 10 of the present invention, the tight-fit component 160 , the first protruding portion 133 , and the second protruding portion 146 may not be disposed; the protruding ring 145 at the second end 142 of the hollow core shaft 140 is directly sleeved over the second end 132 of the hollow connecting shaft 130 , and two ends of the elastic element 150 are fixedly connected to the stop wall 147 at the second end 142 of the hollow core shaft 140 and the stop wall 134 at the second end 132 of the hollow connecting shaft 130 . In this manner, when an external force drives the outer wheel 110 to rotate, the outer wheel 110 rotates relative to the hollow connecting shaft 130 in the first relative rotation direction and drives, through the clutch wheel 120 , the hollow connecting shaft 130 to rotate synchronously; the stop wall 134 at the second end 132 of the hollow connecting shaft 130 presses the elastic element 150 , and while being pressed, the elastic element 150 pushes the stop wall 147 at the second end 142 of the hollow core shaft 140 , thereby driving the hollow core shaft 140 to rotate. On the contrary, when the external force decreases or stops driving the outer wheel 110 to rotate, the hollow core shaft 140 continues to rotate due to inertia of the rotor 30 and stretches the elastic element 150 , and while being stretched, the elastic element 150 pulls the second end 132 of the hollow connecting shaft 130 , thereby driving the hollow connecting shaft 130 to rotate relative to the outer wheel 110 in the second relative rotation direction so that the hollow connecting shaft 130 is disassociated from the co-rotational relationship with the outer wheel 110 and idles in the clutch wheel 120 . Although the present invention and advantages thereof are described in detail above, it should be understood that variations, alternative solutions, and modifications can be made herein without departing from the spirit and scope of the present invention which are defined in the appended patent application scope. Moreover, the scope of the present invention is not limited to the specific implementations of the process, machine, product, material composition, means, method, and steps described in the specification. For example, persons skilled in the art can easily learn from the disclosure of the present invention that existing or to-be-developed processes, machines, products, material compositions, means, methods and steps that substantially implement the same function or substantially achieve the same result as the corresponding implementation manner described herein may be used. Correspondingly, the appended patent application scope is intended to cover such processes, machines, products, material compositions, means, methods or steps.

The present invention relates to a pulley for an alternator, and in particular, to a pulley applicable to an automotive alternator. The pulley effectively mitigates the problem that a belt and a tension pulley of an alternator vibrate because a rotation speed of a vehicle engine changes, thereby improving the overall operating efficiency of the alternator and the service life of the working belt and the tension pulley.

CROSS REFERENCE TO RELATED APPLICATIONS The present application is a continuation application of U.S. patent application Ser. No. 12/941,702, filed Nov. 8, 2010, now U.S. Pat. No. 9,028,454, which is a continuation application of U.S. patent application Ser. No. 12/320,189, filed Jan. 21, 2009, now U.S. Pat. No. 7,850,662, which is a continuation application of U.S. patent application Ser. No. 11/520,598, filed Sep. 14, 2006, now U.S. Pat. No. 7,935,088, which is a continuation application of U.S. patent application Ser. No. 10/790,866, filed Mar. 3, 2004, abandoned, and claims priority to GB Patent Application No. 0304822.0, filed Mar. 3, 2003, the entire contents of each of which are incorporated herein by reference. TECHNICAL FIELD The present invention relates to drive mechanisms suitable for use in drug delivery devices, in particular pen-type injectors, having dosage setting means, enabling the administration of medicinal products from a multi-dose cartridge. In particular, the present invention relates to such drug delivery devices where a user may set the dose. BACKGROUND Such drug delivery devices have application where regular injection by persons without formal medical training occurs, i.e., patients. This is increasingly common amongst those having diabetes where self-treatment enables such persons to conduct effective management of their diabetes. These circumstances set a number of requirements for drug delivery devices of this kind. The device must be robust in construction, yet easy to use in terms of the manipulation of the parts, understanding by a user of its operation and the delivery of the required dose of medicament. Dose setting must be easy and unambiguous. In the case of those with diabetes, many users will be physically infirm and may also have impaired vision requiring the drive mechanism to have low dispensing force and an easy to read dose setting display. Where the device is to be disposable rather than reusable, the device should be cheap to manufacture and easy to dispose of (preferably being suitable for recycling). To meet these requirements the number of parts required to assemble the device and the number of material types the device is made from need to be kept to a minimum. User operated drug delivery devices are well known within the medical field. In U.S. Pat. No. 5,304,152 a dispensing device is disclosed which has a body length to plunger length ratio of about 1:1 in order to allow the dispensing of relatively large doses. Whilst this device provides many improvements over the prior art the easy correction of a set overdose remains unresolved without either dispensing the set amount of fluid or dismantling the cartridge. WO 9938554 A2 teaches an injection syringe for apportioning set doses of a medicine from a cartridge wherein a drive mechanism comprising a unidirectional coupling (i.e., a ratchet) is disclosed which allows correction of a set overdose without dispensing the set amount of fluid or requiring the dismantling of the cartridge. Surprisingly it was found that the drive mechanism according to instant invention without having a unidirectional coupling provides a valuable technical alternative for drive mechanisms, wherein reduced force is needed to actuate the mechanism. This is achieved by the introduction of a clutch means as defined by instant invention. The drive mechanism according to instant invention further provides the advantage of intuitive and easy to use correction of a set dose. SUMMARY According to a first aspect of the present invention, a drive mechanism for use in a drug delivery device is provided comprising: a housing having a helical thread; a dose dial sleeve having a helical thread engaged with the helical thread of the said housing; a drive sleeve releasibly connected to the said dose dial sleeve; and a clutch means located between the dose dial sleeve and the drive sleeve; characterized in that, a) when the dose dial sleeve and the drive sleeve are coupled, the dose dial sleeve and the drive sleeve are allowed to rotate with respect to the housing; and b) when the dose dial sleeve and the drive sleeve are de-coupled, rotation of the dose dial sleeve with respect to the housing is allowed, whilst rotation of the drive sleeve with respect to the housing is not allowed, whereby axial movement of the drive sleeve is allowed so that a force is transferred in the longitudinal direction to the proximal end of the drug delivery device. In a preferred embodiment of the drive mechanism of instant invention the said drive mechanism further comprises a piston rod adapted to operate through the housing and transfer the said force in the said longitudinal direction to the proximal end of the drug delivery device. In another preferred embodiment of the drive mechanism of instant invention the said dose dial sleeve further comprises a helical thread, which has the same lead as the lead of the helical thread of the said drive sleeve. In a more specific embodiment of instant invention, the drive mechanism further comprises a nut, which is rotatable with respect to the drive sleeve and axially displaceable but not rotatable with respect to the housing. The term “drug delivery device” according to instant invention shall mean a single-dose or multi-dose, or re-useable device designed to dispense a selected dose of a medicinal product, preferably multiple selected doses, e.g. insulin, growth hormones, low molecular weight heparins, and their analogues and/or derivatives etc. Said device may be of any shape, e.g. compact or pen-type. Dose delivery may be provided through a mechanical (optionally manual) or electrical drive mechanism or stored energy drive mechanism, such as a spring, etc. Dose selection may be provided through a manual mechanism or electronic mechanism. Additionally, said device may contain components designed to monitor physiological properties such as blood glucose levels, etc. Furthermore, the said device may comprise a needle or may be needle-free. In particular, the term “drug delivery device” shall mean a disposable multi-dose pen-type device having mechanical and manual dose delivery and dose selection mechanisms, which is designed for regular use by persons without formal medical training such as patients. Preferably, the drug delivery device is of the injector-type. The term “housing” according to instant invention shall preferably mean any exterior housing (“main housing”, “body”, “shell”) or interior housin9 (“insert”, “inner body”) having a helical thread. The housing may be designed to enable the safe, correct, and comfortable handling of the drug delivery device or any of its mechanism. Usually, it is designed to house, fix, protect, guide, and/or engage with any of the inner components of the drug delivery device (e.g., the drive mechanism, cartridge, plunger, piston rod) by limiting the exposure to contaminants, such as liquid, dust, dirt etc. In general, the housing may be unitary or a multipart component of tubular or non-tubular shape. Usually, the exterior housing serves to house a cartridge from which a number of doses of a medicinal product may by dispensed. In a more specific embodiment of instant invention, the exterior housing is provided with a plurality of maximum dose stops adapted to be abutted by a radial stop provided on the dose dial sleeve. Preferably, at least one of the maximum dose stops comprises a radial stop located between a helical thread and spline means provided at a second end of the housing. Alternatively; at least one of the maximum dose stops comprises a part of a raised window portion provided at a second end of the housing. The term “engaged” according to instant invention shall particularly mean the interlocking of two or more components of the drive mechanism/drug delivery device, e.g. a spline, thread; or meshed teeth connection, preferably the interlocking of helical threads of components (“threadedly engaged”). The term “helical thread” according to instant invention shall preferably mean a full or part thread, e.g., a cylindrical spiral rib/groove, located on the internal and/or external surface of a component of the drug delivery device, having an essentially triangular or square or rounded section designed to allow continuous free rotational and/or axial movement between components. Optionally, a thread may be further designed to prevent rotational or axial movement of certain components in one direction. The term “dose dial sleeve” according to instant invention shall mean an essentially tubular component of essentially circular cross-section having either: a) both an internal and external thread, or b) an internal thread, or c) an external thread. Preferably, the dose dial sleeve according to instant invention comprises a helical thread having a lead, which is similar to, preferably the same as the lead of the helical thread of the drive sleeve. In yet another preferred embodiment the dose dial sleeve is designed to indicate a selected dose of a dispensable product. This may be achieved by use of markings, symbols, numerals, etc., e.g. printed on the external surface of the dose dial sleeve or an odometer, or the like. In a more specific embodiment of instant invention, the dose dial sleeve is provided with a plurality of radially extending members adapted to abut a corresponding plurality of radial stops provided at a second end of the housing. The term “lead” according to instant invention shall preferably mean the axial distance a nut would advance in one complete revolution; preferably “lead” shall mean the axial distance through which a component having a helical thread, i.e. dose dial sleeve, drive sleeve, piston rod, etc., of the drive mechanism travels during one rotation. Therefore lead is a function of the pitch of the thread of the relevant component. The term “pitch” according to instant invention shall preferably mean the distance between consecutive contours on a helical thread, measured parallel to the axis of the helical thread. The term “drive sleeve” according to instant invention shall mean any essentially tubular component of essentially circular cross-section and which is further releasibly connected to the dose dial sleeve. In a preferred embodiment the drive sleeve is further engaged with the piston rod. In a more particular embodiment of instant invention, the drive sleeve is provided at a first end with first and second flanges with an intermediate helical thread between the first and second flanges, having a nut disposed between the first and second flanges and keyed to the housing by spline means. Optionally, a first radial stop may be provided on a second face of the nut and a second radial stop may be provided on a first face of the second flange. The term “releasibly connected” according to instant invention shall preferably mean that two components of instant mechanism or device are reversibly joined to each other, which allows coupling and decoupling, e.g. by means of a clutch. The term “piston rod” according to instant invention shall mean a component adapted to operate through/within the housing, designed to translate axial movement through/within the drug delivery device, preferably from the drive sleeve to the piston, for the purpose of discharging/dispensing an injectable product. Said piston rod may be flexible or not. It may be a simple rod, a lead-screw, a rack and pinion system, a worm gear system, or the like. The “piston rod” shall further mean a component having a circular or non-circular cross-section. It may be made of any suitable material known by a person skilled in the art. In a preferred embodiment, the piston rod comprises at least one, more preferably two, external and/or internal helical threads. In another preferred embodiment of the piston rod according to instant invention, a first helical thread is located at a first end and a second helical thread is located at a second end of the said piston rod, whereby the said threads may have the same or, preferably, opposite dispositions. In another preferred embodiment the piston rod of instant invention comprises threads having the same leads at the first and the second end. In yet another preferred embodiment of instant invention the lead of the first helical thread of the piston rod shall be greater than the lead of the second helical thread. More preferred, the ratio of the leads of the helical threads of the said first and the second helical threads is 1:1, 01 to 1:20, even more preferred 1:1, 1 to 1:10. Preferably, one of the said threads is designed to engage with the drive sleeve. Alternatively, in another preferred embodiment of the piston rod of instant invention, the piston rod is designed to have attached, optionally by means of a journal bearing, a toothed gear, and wherein said toothed gear is designed to mesh with the threads of the drive sleeve and the teeth of a toothed rack, whereby said toothed rack is fixed to the housing. The term “first end” according to instant invention shall mean the proximal end. The proximal end of the device or a component of the device shall mean the end, which is closest to the dispensing end of the device. The term “second end” according to instant invention shall mean the distal end. The distal end of the device or a component of the device shall mean the end, which is furthest away from the dispensing end of the device. The term “clutch means” according to instant invention shall mean any means, which releasibly connects the dose dial sleeve and the drive sleeve and which is designed to allow rotation of the dose dial sleeve and the drive sleeve with respect to the housing when the dose dial sleeve and the drive sleeve are coupled and, when both are de-coupled, allows rotation of the dose dial sleeve with respect to the housing, but does not allow rotation of the drive sleeve with respect to the housing and allows axial movement of the drive sleeve. Preferably, the clutch means releasibly connects the drive sleeve to the housing. Accordingly, the term clutch means is any clutch engaging for the purpose of reversibly locking two components in rotation, e.g., by use of axial forces to engage a set of face teeth (saw teeth, dog teeth, crown teeth) or any other suitable frictional faces. In a more specific embodiment of instant invention, a second end of the clutch means is provided with a plurality of dog teeth adapted to engage with a second end of the dose dial sleeve. In an alternative embodiment, the clutch means of instant invention is a locking spring, operable, e.g., by means of a dose dial button, between a first, relaxed position, in which the dose dial sleeve is locked with respect to rotation with the drive sleeve and a second, deformed position, in which the dose dial sleeve is locked with respect to rotation with the housing. In still another embodiment of instant invention, the drive mechanism further comprises a clicker means, optionally disposed between the clutch means and spline means provided on the housing. Optionally, the clicker means comprises a sleeve provided at a first end with a helically extending arm, a free end of the atm having a toothed member; and at a second end with a plurality of circumferentially directed saw teeth adapted to engage a corresponding plurality of circumferentially saw teeth provided on the clutch means. Alternatively, the clicker means comprises a sleeve provided at a first end with at least one helically extending arm and at least one spring member, a free end of the arm having a toothed member, and at a second end with a plurality of circumferentially directed saw teeth adapted to engage corresponding plurality of circumferentially directed saw teeth provided on the clutch means. In still another embodiment of the drive mechanism of the invention, the drive mechanism is provided with a first stop means, preferably in the form of an external flange on the dose dial sleeve, adapted to engage limiting means associated with the housing, preferably in the form of an internal flange in the housing, to limit the maximum dose which can be dialed. In yet another embodiment of the drive mechanism of the invention, the drive mechanism is further provided with a second stop means, preferably in the form of an external flange on the drive sleeve, adapted to engage limiting means, preferably in the form of a limiting nut keyed to the housing and mounted for rotation on an external threaded section of the drive sleeve, to provide an end of life stop. A second aspect of instant invention provides an assembly for use in a drug delivery device comprising the drive mechanism according to instant invention. A third aspect of the present invention provides a drug delivery device comprising the drive mechanism or the assembly according to instant invention. A fourth aspect of the present invention provides a method of assembling a drug delivery device comprising the step of providing a drive mechanism or an assembly according to instant invention. A fifth aspect of instant invention is the use of a drug delivery device according to instant invention for dispensing a medicinal product preferably dispensing a pharmaceutical formulation (e.g. solution, suspension etc.) comprising an active compound selected from the group consisting of insulin, growth hormone, low molecular weight heparin, their analogues and their derivatives. BRIEF DESCRIPTION OF THE FIGURES Without any limitation, the instant invention will be explained in greater detail below in connection with a preferred embodiment and with reference to the drawings in which: FIG. 1 shows a sectional view of a first embodiment of the drug delivery device in accordance with the present invention in a first, cartridge full, position; FIG. 2 shows a sectional view of the drug delivery device of FIG. 1 in a second, maximum first dose dialed, position; FIG. 3 shows a sectional view of the drug delivery device of FIG. 1 in a third, maximum first dose dispensed, position; FIG. 4 shows a sectional view of the drug delivery device of FIG. 1 in a fourth, final dose dialed, position; FIG. 5 shows a sectional view of the drug delivery device of FIG. 1 in a fifth, final dose dispensed, position; FIG. 6 shows a cut-away view of a first detail of the drug delivery device of FIG. 1 ; FIG. 7 shows a partially cut-away view of a second detail of the drug delivery device of FIG. 1 ; FIG. 8 shows a partially cut-away view of a third detail of the drug delivery device of FIG. 1 ; FIG. 9 shows the relative movement of parts of the drug delivery device shown in FIG. 1 during dialing up of a dose; FIG. 10 shows the relative movement of parts of the drug delivery device shown in FIG. 1 during dialing down of a dose; FIG. 11 shows the relative movement of parts of the drug delivery device shown in FIG. 1 during dispensing of a dose; FIG. 12 shows a partially cut-away view of the drug delivery device of FIG. 1 in the second, maximum first dose dialed, position; FIG. 13 shows a partially cut-away view of the drug delivery device of FIG. 1 in the fourth, final dose dialed, position; FIG. 14 shows a partially cut-away view of the drug delivery device of FIG. 1 in one of the first, third or fifth positions; FIG. 15 shows a cut-away view of a first part of a main housing of the drug delivery device of FIG. 1 ; and FIG. 16 shows a cut-away view of a second part of the main housing of the drug delivery device of FIG. 1 ; FIG. 17 shows a sectional view of a second embodiment of the drive mechanism according to instant invention in a first, cartridge full, position. FIG. 18 shows a sectional side view of a third embodiment of the drug delivery device in accordance with the present invention in a first, cartridge full, position; FIG. 19 shows a sectional side view of the drug delivery device of FIG. 18 in a second, maximum first dose dialed, position; FIG. 20 shows a sectional side view of the drug delivery device of FIG. 18 in a third, maximum first dose dispensed, position; FIG. 21 shows a sectional side view of the drug delivery device of FIG. 18 in a fourth, final dose dialed, position; FIG. 22 shows a sectional side view of the drug delivery device of FIG. 18 in a fifth final dose dispensed, position; FIG. 23 shows a fragment of the drug delivery device of FIG. 18 in a larger scale; and FIG. 24 shows a further fragment of the drug delivery device of FIG. 18 in a larger scale. DETAILED DESCRIPTION Example 1 Referring first to FIGS. 1 to 5 , there is shown a drug delivery device in accordance with the present invention in a number of positions. The drug delivery device comprises a housing having a first cartridge retaining part 2 , and second main (exterior) housing part 4 . A first end of the cartridge retaining means 2 and a second end of the main housing 4 are secured together by retaining features 6 . In the illustrated embodiment, the cartridge retaining means 2 is secured within the second end of the main housing 4 . A cartridge 8 from which a number of doses of a medicinal product may be dispensed is provided in the cartridge retaining part 2 . A piston 10 is retained in a first end of the cartridge 8 . A removable cap 12 is releasably retained over a second end of the cartridge retaining part 2 . In use the removable cap 12 can be replaced by a user with a suitable needle unit (not shown). A replaceable cap 14 is used to cover the cartridge retaining part 2 extending from the main housing 4 . Preferably, the outer dimensions of the replaceable cap 14 are similar or identical to the outer dimensions of the main housing 4 to provide the impression of a unitary whole when the replaceable cap 14 is in position covering the cartridge retaining part 2 . In the illustrated embodiment, an insert 16 is provided at a first end of the main housing 4 . The insert 16 is secured against rotational or longitudinal motion. The insert 16 is provided with a threaded circular opening 18 extending there through. Alternatively, the insert may be formed integrally with the main housing 4 having the form of a radially inwardly directed flange having an internal thread. A first thread 19 extends from a first end of a piston rod 20 . The piston rod 20 is of generally circular section. The first end of the piston rod 20 extends through the threaded opening 18 in the insert 16 . A pressure foot 22 is located at the first end of the piston rod 20 . The pressure foot 22 is disposed to abut a second end of the cartridge piston 10 . A second thread 24 extends from a second end of the piston rod 20 . In the illustrated embodiment the second thread 24 comprises a series of part threads rather than a complete thread. The illustrated embodiment is easier to manufacture and helps to reduce the overall force required for a user to actuate the device when dispensing the medicinal product. The first thread 19 and the second thread 24 are oppositely disposed. The second end of the piston rod 20 is provided with a receiving recess 26 . A drive sleeve 30 extends about the piston rod 20 . The drive sleeve 30 is generally cylindrical. The drive sleeve 30 is provided at a first end with a first radially extending flange 32 . A second radially extending flange 34 is provided spaced distance along the drive sleeve 30 from the first flange 32 . An intermediate thread 36 is provided on an outer part of the drive sleeve 30 extending between the first flange 32 and the second flange 34 . A helical groove (thread) 38 extends along the internal surface of the drive sleeve 30 . The second thread 24 of the piston rod 20 is adapted to work within the helical groove 38 . A first end of the first flange 32 is adapted to conform to a second side of the insert 16 . A nut 40 is located between the drive sleeve 30 and the main housing 2 , disposed between the first flange 32 and the second flange 34 . In the illustrated embodiment the nut 40 is a half-nut. This assists in the assembly of the device. The nut 40 has an internal thread matching the intermediate thread 36 . The outer surface of the nut 40 and an internal surface of the main housing 4 are keyed together by splines 42 ( FIGS. 10, 11, 15 and 16 ) to prevent relative rotation between the nut 40 and the main housing 4 , while allowing relative longitudinal movement therebetween. A shoulder 37 is formed between a second end of the drive sleeve 30 an extension 47 provided at the second end of the drive sleeve 30 . The extension 47 has reduced inner and outer diameters in comparison to the remainder of the drive sleeve 30 . A second end of the extension 47 is provided with a radially outwardly directed flange 39 . A clicker 50 and a clutch 60 are disposed about the drive sleeve 30 , between the drive sleeve 30 and a dose dial sleeve 70 (described below). The clicker 50 is located adjacent the second flange 34 of the drive sleeve 30 . The clicker 50 is generally cylindrical and is provided at a first end with a flexible helically, extending arm 52 ( FIG. 6 ). A free end of the arm 52 is provided with a radially directed toothed member 54 . A second end of the clicker 50 is provided with a series of circumferentially directed saw teeth 56 ( FIG. 7 ). Each saw tooth comprises a longitudinally directed surface arid an inclined surface. In an alternative embodiment (not shown) the clicker further includes at least one spring member. The at least one spring member assists in the resetting of the clutch 60 following dispense. The clutch 60 is located adjacent the second end of the drive sleeve 30 . The clutch 60 is generally cylindrical and is provided at a first end with a series of circumferentially directed saw teeth 66 ( FIG. 7 ). Each saw tooth comprises a longitudinally directed surface and an inclined surface. Towards the second end 64 of the clutch 60 there is located a radially inwardly directed flange 62 . The flange 62 of the clutch 60 is disposed between the shoulder 37 of the drive sleeve 30 and the radially outwardly directed flange 39 of the extension 38 . The second end of the clutch 60 is provided with a plurality of dog teeth 65 ( FIG. 8 ). The clutch 60 is keyed to the drive sleeve 30 by way of splines (not shown) to prevent relative rotation between the clutch 60 and the drive sleeve 30 . In the illustrated embodiment, the clicker 50 and the clutch 60 each extend approximately half the length of the drive sleeve 30 . However, it will be understood that other arrangements regarding the relative lengths of these parts are possible. The clicker 50 and the clutch 60 are engaged as shown in FIG. 7 . A dose dial sleeve 70 is provided outside of the clicker 50 and clutch 60 and radially inward of the main housing 4 . A helical groove 74 is provided about an outer surface of the dose dial sleeve 70 . The main housing 4 is provided with a window 44 through which a part of the outer surface of the dose dial sleeve may be seen. The main housing 4 is further provided with a helical rib (thread) 46 , adapted to be seated in the helical groove (thread) 74 on the outer surface of the dose dial sleeve 70 . The helical rib 46 extends for a single sweep of the inner surface of the main housing 4 . A first stop 100 is provided between the splines 42 and the helical rib 46 ( FIG. 15 ). A second stop 102 , disposed at an angle of 180° to the first stop 100 is formed by a frame surrounding the window 44 in the main housing 4 ( FIG. 16 ). Conveniently, a visual indication of the dose that may be dialed, for example reference numerals (not shown), is provided on the outer surface of the dose dial sleeve 70 . The window 44 conveniently only allows to be viewed a visual indication of the dose currently dialed. A second end of the dose dial sleeve 70 is provided with an inwardly directed flange in the form of a number of radially extending members 75 . A dose dial grip 76 is disposed about an outer surface of the second end of the dose dial sleeve 70 . An outer diameter of the dose dial grip 76 preferably corresponds to the outer diameter of the main housing 4 . The dose dial grip 76 is secured to the dose dial sleeve 70 to prevent relative movement there between. The dose dial grip 76 is provided with a central opening 78 . An annular recess 80 located in the second end of the dose dial grip 76 extends around the opening 78 . A button 82 of generally “T” section is provided at a second end of the device. A stem 84 of the button 82 may extend through the opening 78 in the dose dial grip 76 , through the inner diameter of the extension 47 of the drive sleeve 30 and into the receiving recess 26 of the piston rod 20 . The stem 84 is retained for limited axial movement in the drive sleeve 30 and against rotation with respect thereto. A head 85 of the button 82 is generally circular. A skirt 86 depends from a periphery of the head 85 . The skirt 86 is adapted to be seated in the annular recess 80 of the dose dial grip 76 . Operation of the drug delivery device in accordance with the present invention will now be described. In FIGS. 9, 10 and 11 arrows A, B, C, D, E, F and G represent the respective movements of the button 82 , the dose dial grip 76 , the dose dial sleeve 70 , the drive sleeve 30 , the clutch 60 , the clicker 50 and the nut 40 . To dial a dose ( FIG. 9 ) a user rotates the dose dial grip 76 (arrow B). With the clicker 50 and clutch 60 engaged, the drive sleeve 30 , the clicker 50 , the clutch 60 and the dose dial sleeve 70 rotate with the dose dial grip 76 . Audible and tactile feedback of the dose being dialed is provided by the clicker 50 and the clutch 60 . Torque is transmitted through the saw teeth 56 , 66 between the clicker 50 and the clutch 60 . The flexible arm 52 deforms and drags the toothed member 54 over the splines 42 to produce a click. Preferably, the splines 42 are disposed such that each click corresponds to a conventional unit dose, or the like. The helical groove 74 on the dose dial sleeve 70 and the helical groove 38 in the drive sleeve 30 have the same lead. This allows the dose dial sleeve 70 (arrow C) to extend from the main housing 4 and the drive sleeve 30 (arrow D) to climb the piston rod 20 at the same rate. At the limit of travel, a radial stop 104 ( FIG. 12 ) on the dose dial sleeve 70 engages either the first stop 100 or the second stop 102 provided on the main housing 4 to prevent further movement. Rotation of the piston rod 20 is prevented due to the opposing directions of the overhauled and driven threads on the piston rod 20 . The nut 40 , keyed to the main housing 4 , is advanced along the intermediate thread 36 by the rotation of the drive sleeve 30 (arrow D). When the final dose dispensed position ( FIGS. 4, 5 and 13 ) is reached, a radial stop 106 formed on a second surface of the nut 40 abuts a radial stop 108 on a first surface of the second flange 34 of the drive sleeve 30 , preventing both the nut 40 and the drive sleeve 30 from rotating further. In an alternative embodiment not shown) a first surface of the nut 40 is provided with a radial stop for abutment with a radial stop provided on a second surface of the first flange 32 . This aids location of the nut 40 at the cartridge full position during assembly of the drug delivery device. Should a user inadvertently dial beyond the desired dosage, the drug delivery device allows the dosage to be dialed down without dispense of medicinal product from the cartridge ( FIG. 10 ). The dose dial grip 76 is counter rotated (arrow 13 ). This causes the system to act in reverse. The flexible arm 52 preventing the clicker 50 from rotating. The torque transmitted through the clutch 60 causes the saw teeth 56 , 66 to ride over one another to create the clicks corresponding to dialed dose reduction. Preferably the saw teeth 56 , 66 are so disposed that the circumferential extent of each saw tooth corresponds to a unit dose. When the desired dose has been dialed, the user may then dispense this dose by depressing the button 82 ( FIG. 11 ). This displaces the clutch 60 axially with respect to the dose dial sleeve 70 causing the dog teeth 65 to disengage. However the clutch 60 remains keyed in rotation to the drive sleeve 30 . The dose dial sleeve 70 and associated dose dial grip 76 are now free to rotate (guided by the helical rib 46 located in helical groove 74 ). The axial movement deforms the flexible arm 52 of the clicker 50 to ensure the saw teeth 56 , 66 cannot be overhauled during dispense. This prevents the drive sleeve 30 from rotating with respect to the main housing 4 though it is still free to move axially with respect thereto. This deformation is subsequently used to urge the clicker 50 , and the clutch 60 , back along the drive sleeve 30 to restore the connection between the clutch 60 and the dose dial sleeve 70 when pressure is removed from the button 82 The longitudinal axial movement of the drive sleeve 30 causes the piston rod 20 to rotate though the opening 18 in the insert 16 , thereby to advance the piston 10 in the cartridge 8 . Once the dialed dose has been dispensed, the dose dial sleeve 70 is prevented from further rotation by contact of a plurality of members 110 ( FIG. 14 ) extending from the dose dial grip 76 with a corresponding plurality of stops 112 formed in the main housing 4 ( FIGS. 15 and 16 ). In the illustrated embodiment, the members 110 extend axially from the dose dial grip 76 and have an inclined end surface. The zero dose position is determined by the abutment of one of the axially extending edges of the members 110 with a corresponding stop 112 . Example 2 In another embodiment of the invention ( FIG. 17 ) there is seen a drive mechanism comprising a second main housing 4 ′ having a first end and a second end. A cartridge, containing medicinal product, can be mounted to the first end of the second main housing 4 ′ and retained by any suitable means. The cartridge and its retaining means are not shown in the illustrated embodiment. The cartridge may contain a number of doses of a medicinal product and also typically contains a displaceable piston. Displacement of the piston causes the medicinal product to be expelled from the cartridge via a needle (also not shown). In the illustrated embodiment, an insert 16 ′ is provided within the main housing 4 ′. The insert 16 ′ is secured against rotational and axial motion with respect to the second main housing 4 ′. The insert 16 ′ is provided with a threaded circular opening extending there through. Alternatively, the insert may be formed integrally with the second main housing 4 ′. An internal housing 154 is also provided within the second main housing 4 ′. The internal housing 154 is secured against rotational and axial motion with respect to the second main housing 4 ′. The internal housing 154 is provided with a circular opening extending through its length in which a series of longitudinally directed splines are formed. A helical thread 150 extends along the outer cylindrical surface of the internal housing 154 . Alternatively, the internal housing may be formed integrally with the second main housing 4 ′ and/or with the insert 16 ′. A first thread 19 ′ extends from a first end of a piston rod 20 ′. The piston rod 20 ′ is of generally circular section. The first end of the piston rod 20 ′ extends through the threaded opening in the insert 16 ′ and the first thread 19 ′ of the piston rod 20 ′ is engaged with the thread of the insert 16 ′. A pressure foot 22 ′ is located at the first end of the piston rod 20 ′. The pressure foot 22 ′ is disposed to abut a cartridge piston (not shown). A second thread 24 ′ extends from a second end of the piston rod 20 ′. The first thread 19 ′ and the second thread 24 ′ are oppositely disposed. A drive sleeve 30 ′ extends about the piston rod 20 ′. The drive sleeve 30 ′ is generally cylindrical. The drive sleeve 30 ′ is provided at a first end with a first radially extending flange 32 °. A second radially extending flange 34 ′ is provided, spaced a distance along the drive sleeve 30 ′ from the first flange 32 ′. An external helical thread (not shown) is provided on the outer part of the drive sleeve 30 ′ extending between the first flange 32 ′ and the second flange 34 ′. An internal helical thread extends along the internal surface of the drive sleeve 30 ′. The second thread 24 ′ of the piston rod 20 ′ is engaged with the internal helical thread of the drive sleeve 30 ′. A nut 40 ′ is located between the drive sleeve 30 ′ and the internal housing 154 , disposed between the first flange 32 ′ and the second flange 34 ′ of the drive sleeve 30 ′. The nut 40 ′ can be either a ‘half-nut’ or a ‘full-nut’. The nut 40 ′ has an internal thread that is engaged with the external helical thread of the drive sleeve 30 ′. The outer surface of the nut 40 ′ and an internal surface of the internal housing 154 are keyed together by means of longitudinally directed splines to prevent relative rotation between the nut 40 ′ and the internal housing 154 , while allowing relative longitudinal movement there between. A clicker 50 ′ and a clutch 60 ′ are disposed about the drive sleeve 30 ′, between the drive sleeve 30 ′ and the internal housing 154 . The clicker 50 ′ is located adjacent the second flange 34 ′ of the drive sleeve 30 ′. The clicker 50 ′ includes at least one spring member (not shown). The clicker 50 ′ also includes a set of teeth (not shown) having a triangular profile disposed towards the second end of the drive mechanism. When compressed, the at least one spring member of the clicker 50 ′ applies an axial force between the flange 34 ′ of the drive sleeve 30 ′ and the clutch 60 ′. The outer surface of the clicker 50 ′ and an internal surface of the internal housing 154 are keyed together by means of longitudinally directed splines to prevent relative rotation between the clicker 50 ′ and the internal housing 154 , while allowing relative longitudinal movement there between. The clutch 60 ′ is located adjacent the second end of the drive sleeve 30 ′. The clutch 60 ′ is generally cylindrical and is provided at its' first end with a plurality of teeth of triangular profile disposed about the circumference (not shown), that act upon the teeth of the clicker 50 ′. Towards the second end of the clutch 60 ′ there is located a shoulder 158 . The shoulder 158 of the clutch 60 ′ is disposed between the internal housing 154 and a radially inwardly directed flange of the dose dial grip 76 ′ (described below). The shoulder 158 of the clutch 60 ′ is provided with a plurality of dog teeth (not shown) extending in the direction of the second end of the drive mechanism. The clutch 60 ′ is keyed to the drive sleeve 30 ′ by way of splines (not shown) to prevent relative rotation between the clutch 60 ′ and the drive sleeve 30 ′. A dose dial sleeve 70 ′ is provided outside of the internal housing 154 and radially inward from the second main housing 4 ′. A helical thread is provided on an inner surface of the dose dial sleeve 70 ′. The helical thread of the dose dial sleeve 70 ′ is engaged with the helical thread 150 of the internal housing 154 . The second main housing 4 ′ is provided with a window (not shown) through which part of the outer surface of the dose dial sleeve 70 ′ may be viewed. Conveniently, a visual indication of the dose that may be dialed, for example reference numerals (not shown), is provided on the outer surface of the dose dial sleeve 70 ′. Conveniently, the window of the second main housing 4 ′ allows only the dose that is currently dialed to be viewed. A dose dial grip 76 ′ is located towards the second end of the drive mechanism. The dose dial grip 76 ′ is secured against rotational and axial motion within respect to the dose dial sleeve 70 ′. The dose dial grip 76 ′ is provided with a radially inwardly directed flange 160 . The radially inwardly directed flange 160 of the dose dial grip 76 ′ is provided with a plurality of dog teeth (not shown) extending in the direction of the first end of the drive mechanism to abut the dog teeth of the clutch 60 ′. Coupling and decoupling of the dog teeth of the dose dial grip 76 ′ with the dog teeth of the clutch 60 ′ provides a releasable clutch between the dose dial grip 76 ′ and the clutch 60 ′. A button 82 ′ of generally “T” shaped cross-section is provided at a second end of the drive mechanism. A cylindrical feature of the button 82 ′ extends towards the first end of the drive mechanism, through an opening in the dose dial grip 76 ′ and into a recess in the drive sleeve 30 ′. The cylindrical feature of the button 82 ′ is retained for limited axial movement in the drive sleeve 30 ′ and agah1st rotation with respect thereto. The cylindrical feature of the button 82 ′ has lugs extending radially (not shown) that abut the second surface of the shoulder 158 of the clutch 60 ′. The second end of the button 82 ′ is generally circular arid has a cylindrical skirt about its' periphery that descends towards the first end of the drive mechanism. The skirt of the button 82 ′ is located radially inward from the dose dial grip 76 ′. Operation of the drive mechanism in accordance with the present invention will now be described. To dial a dose, a user rotates the dose dial grip 76 ′. The spring member of the clicker 50 ′ applies an axial force to the clutch 60 ′ in the direction of the second end of the drive mechanism. The force exerted by the spring member of the clicker 50 ′ couples the dog teeth of the clutch 60 ′ to the dog teeth of the dose dial grip 76 ′ for rotation. As the dose dial grip 76 ′ is rotated, the associated dose dial sleeve 70 ′, the drive sleeve 30 ′ and the clutch 60 ′ all rotate in unison. Audible and tactile feedback of the dose being dialed is provided by the clicker 50 ′ and the clutch 60 ′. As the clutch 60 ′ is rotated, torque is transmitted from the teeth at the first end of the clutch 60 ′ and the teeth of the clicker 50 ′. The clicker 50 ′ cannot rotate with respect to the internal housing 154 , so the at least one spring member of the clicker 50 ′ deforms allowing the teeth of the clutch 60 ′ to jump over the teeth of the clicker 50 ′ producing an audible and tactile ‘click’. Preferably; the teeth of the clicker 50 ′ and the teeth of the clutch 60 ′ are disposed such that each ‘click’ corresponds to a conventional unit of the medicinal product, or the like. The helical thread of the dose dial sleeve 70 ′ and the internal helical thread of the drive sleeve 30 ′ have the same lead. This allows the dose dial sleeve 70 ′ to advance along the thread 150 of the internal housing 154 at the same rate as the drive sleeve 30 ′ advances along the second thread 24 ′ of the piston rod 20 ′. Rotation of the piston rod 20 ′ is prevented due to the opposing direction of the first thread 19 ′ and the second thread 24 ′ of the piston rod 20 ′. The first thread 19 ′ of the piston rod 20 ′ is engaged with the thread of the insert 16 ′ and so the piston rod 20 ′ does not move with respect to the second main housing 4 ′ while a dose is dialed. The nut 40 ′, keyed to the internal housing 154 , is advanced along the external thread of the drive sleeve 30 ′ by the rotation of the drive sleeve 30 ′. When a user has dialed a quantity of medicinal product that is equivalent to the deliverable volume of the cartridge, the nut 40 ′ reaches a position where it abuts the second flange 34 ′ of the drive sleeve 30 ′. A radial stop formed on the second surface of the nut 40 ′ contacts a radial stop on the first surface of the second flange 34 ′ of the drive sleeve 30 ′, preventing both the nut 40 ′ and the drive sleeve 30 ′ from being rotated further. Should a user inadvertently dial a quantity greater than the desired dosage, the drive mechanism allows the dosage to be corrected without dispense of medicinal product from the cartridge. The dose dial grip 76 ′ is counter-rotated. This causes the system to act in reverse. The torque transmitted through the clutch 60 ′ causes the teeth at the first end of the clutch 60 ′ to ride over the teeth of the clicker 50 ′ to create the clicks corresponding to the dialed dose reduction. When the desired dose has been dialed, the user may then dispense this dose by depressing the button 82 ′ in the direction of the first end of the drive mechanism. The lugs of the button 82 ′ apply pressure to the second surface of the shoulder 158 of the clutch 60 ′, displacing the clutch 60 ′ axially with respect to the dose dial grip 76 . This causes the dog teeth on the shoulder 158 of the clutch 60 ′ to disengage from the dog teeth of the dose dial grip 76 ′. However, the clutch 60 remains keyed in rotation to the drive sleeve 30 ′. The dose dial grip 76 ′ and associated dose dial sleeve 70 ′ are now free to rotate (guided by the helical thread 150 of the internal housing 154 ). The axial movement of the clutch 60 ′ deforms the spring member of the clicker 50 ′ and couples the teeth at the first end of the clutch 60 ′ to the teeth of the clicker 50 ′ preventing relative rotation there between. This prevents the drive sleeve 30 ′ from rotating with respect to the internal housing 154 , though it is still free to move axially with respect thereto. Pressure applied to the button 82 ′ thus causes the dose dial grip 76 ′ and the associated dose dial sleeve 70 ′ to rotate into the second main housing 4 ′. Under this pressure the clutch 60 ′, the clicker 50 ′ and the drive sleeve 30 ′ are moved axially in the direction of the first end of the drive mechanism, but they do not rotate. The axial movement of the drive sleeve 30 ′ causes the piston rod 20 ′ to rotate though the threaded opening in the insert 16 ′, thereby to advance the pressure foot 22 °. This applies force to the piston, causing the medicinal product to be expelled from the cartridge. The selected dose is delivered when the dose dial grip 76 ′ returns to a position where it abuts the second main housing 4 ′. When pressure is removed from the button 82 ′, the deformation of the spring member of the clicker 50 ′ is used to urge the clutch 60 ′ back along the drive sleeve 30 ′ to re-couple the dog teeth on the shoulder 158 of the clutch 60 ′ with the dog teeth on the dose dial grip 76 ′. The drive mechanism is thus reset in preparation to dial a subsequent dose. Example 3 Referring to FIGS. 18 to 22 there may be seen a drug delivery device in accordance with the present invention. The drug delivery device comprises a two-part housing 2 ″ within which are located a cartridge 4 ″ containing a medicinal product, means for setting or selecting the dose of medicinal product to be expelled and means for expelling the selected dose of medicinal product. The housing 2 ″ is generally cylindrical in shape and houses a rack 6 ″ to be described in more detail below. The cartridge 4 ″ is located within a first part 8 ″ of the housing 2 ″. The dose setting means and the means for expelling the selected dose of medicinal product are retained, that is held, within a second part 10 ″ of the housing 2 ″. The first part 8 ″ of the housing 2 ″ and the second part 10 ″ of the housing 2 ″ may be secured together by any suitable means The cartridge 4 ″ may be secured in position in the first part 8 ″ of the housing 2 ″ by any suitable means. A needle unit may be secured to a first end of the cartridge 4 ″. A temporary covering 12 ″ is shown in this position in the Figures. The cartridge 4 ″ further comprises a displaceable piston 14 ″. Advancing the piston 10 ″ towards the first end of the cartridge 4 ″ causes the medicinal product to be expelled from the cartridge 4 ″ through the needle unit. A cap 16 ″ is provided to cover the needle unit when the drug delivery device is not in use. The cap 16 ″ may be releasably secured to the housing 2 ″ by any suitable means. The dose setting means and the means for expelling the selected dose of medicinal product will now be described in more detail. The rack 6 ″ is located within a drive sleeve 18 ″ located within the housing 2 ″ and is fixed both axially and rotationally with respect to the housing 2 ″ by any suitable means. The drive sleeve 18 ″ comprises an internally threaded portion 20 ″, which extends along substantially the entire internal surface of the sleeve. An internal toothed gear 22 ″ is located within the drive sleeve 18 ″ and has helical teeth which match the pitch of the internal thread of the drive sleeve 18 ″. The internal thread of the drive sleeve 18 ″ is a multi-start thread with a lead which is the same as the lead of the helical thread of the dose dial sleeve, which will be described later. The drive sleeve 18 ″ terminates in an externally threaded section 24 ″ which extends from an end of the sleeve as far as an external circumferential flange 26 ″ which projects from the drive sleeve 18 ″. A limiting nut 28 ″ is mounted for rotation on the externally threaded section 24 ″ of the sleeve 14 ″. The limiting nut 28 ″ is keyed to the housing 2 ″ by means of a plurality of longitudinally extending splines 30 ″ which extend along the internal surface of the first portion 8 ″ of the housing 2 ″. In the Illustrated embodiment, the limiting nut 28 ″ is shown as a half-nut, but a full nut could be used. A piston rod 32 ″ is provided extending along the length of the rack 6 ″ and through a hole in the end of the rack 6 ″. The piston rod 32 ″ is generally elongate and, is provided with a pressure foot 34 ″. In use the pressure foot 34 ″ is disposed to abut the cartridge piston 14 ″. The toothed gear 22 ″ is mounted on the end of the piston rod 32 ″ remote from the pressure foot 34 ″ in a journal bearing (not shown). A dose dial sleeve 36 ″ of generally cylindrical form comprises a first section 38 ″ of first diameter and a second section 40 ″ of larger second diameter: The first section is located within the housing 2 ″. The second section 40 ″ of the dose dial sleeve 36 ″ is preferably of the same outer diameter as the housing 2 ″. The second part 10 ″ of the housing 2 ″ comprises an external sleeve portion 42 ″ surrounding a coaxial internal sleeve portion 44 ″. The external sleeve portion 42 ″ is closed to the internal sleeve portion 44 ″ at a circular internal flange portion 46 ″. The first section 38 ″ of the dose dial sleeve 36 ″ is located within the second part 10 ″ of the housing 2 ″, between the external sleeve portion 42 ″ and the internal sleeve portion 44 ″. An inner surface of the first section 38 ″ and the outer surface of the internal sleeve portion 44 ″ are provided with inter engaging features to provide a helical thread 48 ″ between the internal sleeve portion 44 ″ of the second part 10 ″ of the housing 2 ″ and the dose dial sleeve 36 ″. This helical thread 48 ″ has the same lead as the internal thread of the drive sleeve 18 ″, as noted above. Within the helical track, a helical rib provided on the inner surface of the dose dial sleeve 36 ″ may run. This enables the dose dial sleeve 36 ″ to rotate about and along the housing 2 ″. The second section 40 ″ of the dose dial sleeve 36 ″ is provided with an end wall 50 ″ adjacent its free end, which defines a central receiving area 52 ″ between the end wall 50 ″ and the free end of the dose dial sleeve 36 ′″. A through hole 54 ″ is provided in the end wall 50 ″. A dose button 56 ″ of generally “T” shaped configuration is provided, the head 58 ″ of which is retained within the receiving area 52 ″ and the stem 60 ″ of which is sized to pass through the through hole 54 ″. The stem 60 ″ of the button 56 ″ is provided with a plurality of fingers 62 ″ that are deformable to pass through the through hole 54 ′″ of the end wall 50 ″ only in the direction away from the free end of the dose dial sleeve 36 ″. The drive sleeve 18 ″ is closed at its end remote from the externally threaded section 24 ″ by an apertured end wall 64 ″ from which a plurality of engagement features 66 ″ project external to the drive sleeve 18 ″. A substantially U-shaped locking spring 68 ″ comprising first and second legs 70 ″, 72 ″ joined by a link portion 74 ″ is provided for longitudinal mounting on the exterior of the drive sleeve 18 ″. The link portion 74 ″ is of a length which is substantially equal to the external diameter of the drive sleeve 18 ″. Each of the legs 70 ″, 72 ″ of the locking spring 68 ″ terminates in a latch portion 76 ″, the function of which will be described later. When the device is assembled, the locking spring 68 ″ urges the dose button 56 ″ axially away from the piston rod 32 ″ and drive sleeve 18 ″, towards the inside of the end wall 50 ″ of the dose dial sleeve 36 ″. In this position, the dose button 56 ″ is locked with respect to rotation with the dose dial sleeve 36 ″. The dose button 56 ″ is also permanently locked with respect to rotation with the drive sleeve 18 ″. An outer surface of the first section of the dose dial sleeve 36 ″ is provided with graphics 82 ″. The graphics are typically a sequence of reference numerals. The housing 2 ″ is provided with an aperture or window 84 ″ through which a portion of the graphics, representing a dosage value selected by the user, may be viewed. The graphics 82 ″ may be applied to the dose dial sleeve 36 ″ by any suitable means. The graphics 82 ″ may be printed directly on the dose dial sleeve 36 ″ or may be provided in the form of a printed label encircling the dose dial sleeve 36 ″. Alternatively the graphics may take the form of a marked sleeve clipped to the dose dial sleeve 36 ″. The graphics may be marked in any suitable manner, for example by laser marking. The external circumferential flange 26 ″ which projects from the drive sleeve 18 ″ is provided with a pair of diametrically opposed through apertures 78 ″ sized to receive the corresponding latch portions 76 ″ of the locking spring 68 ″. A clicker projection 80 ″ from the outer edge of the flange 26 ″ is associated with each through aperture 78 ″. In FIG. 18 , the drug delivery device is provided with a filled cartridge 4 ″. To operate the drug delivery device a user must first select a dose. To set a dose the dose dial sleeve 36 ″ is rotated with respect to the housing 2 ″ until the desired dose value is visible through the window 84 ″. The drive sleeve 18 ″ is linked to the dose dial sleeve 36 ″ and spirals out at the same rate during dialing. During the dialing of a dose, the locking spring 68 is straight and urges the dose button 56 ″ axially away from the piston rod 32 ″ and drive sleeve 18 ″, towards the inside of the end wall 50 ″ of the dose dial sleeve 36 ″, thereby providing a clutch mechanism. The drive sleeve 18 ″ therefore rotates over the toothed gear 22 ″ that is located inside it. The relative rotation between the drive sleeve. 18 ″ and the housing 2 ″ causes an audible confirmation of the dose being dialed by engagement of the two clicker projections 80 ″ with the splines 30 ″ which extend along the internal surface of the first portion 8 ″ of the housing 2 ″. The limiting nut 28 ″ climbs up the drive sleeve 18 ″ in proportion to the dose dialed. The position of the limiting nut 28 ″, which only moves along the external thread of the drive sleeve 18 ″ when there is relative rotation between the drive sleeve 18 ″ and the housing 2 ″, corresponds to the amount of medicinal product remaining in the cartridge 4 ″. Once a desired dose has been set (as shown for example in FIG. 19 ), to deliver the dose the user depresses the dose button 56 ″ to urge the button 56 ″ against the locking spring 68 ″. As the dose button 56 ″ pushes down on the spring 68 ″, the clutch between the dose button 56 ″ and the dose dial sleeve 36 ″ is disengaged. The axial force applied from the dose button 56 ″ onto the dose dial sleeve 36 ″ causes the dose dial sleeve 36 ″ to spin into the housing 2 ″ on the helical thread between the dose dial sleeve 36 ″ and the housing 2 ″. The locking spring 68 ″ deforms and the legs of the spring move axially down the drive sleeve 18 ″. The latch portions 76 ″ of the locking spring 68 ″ engage in the through apertures 78 ″ on the external flange 26 ″ which projects from the drive sleeve 18 ″ and maintain engagement between the clicker projections 80 ″ of the flange 26 ″ with the grooves between the splines 30 ″, locking the drive sleeve to the housing 2 ″ and preventing the drive sleeve 18 ″ from rotation relative to the housing 2 ″ during dispensing of the dose. The drive sleeve 18 ″ is thus prevented from spinning and moves axially in, causing the toothed gear 22 ″ to rotate against the fixed rack 6 ″. The toothed gear 22 ″, together with the piston rod 32 ″ on which it is mounted, move along the rack 6 ″ a distance corresponding to one half of the distance by which the drive sleeve 18 ″ moves axially, creating a 2:1 mechanical advantage. This has the two-fold benefit of allowing the display on the dose dial sleeve 36 ″ to be larger for a given amount of travel of the piston 14 ″ within the cartridge 4 ″, that is for a given amount of medicament to be dispensed and secondly of halving the force required to dispense the dose. The piston rod 32 ″ is driven through the drive sleeve 18 ″ towards the first end of the drug delivery device, thereby to advance the cartridge piston 14 ″ and expel the desired dose of medicinal product. The piston rod 32 ″ continues to advance until the drive sleeve 18 ″ and dose dial sleeve 36 ″ have returned to their initial positions ( FIG. 20 ). It can be seen that the dose selecting means and the dose expelling means extend beyond a second end of the housing 2 ″ as the dose is selected and are returned within the housing 2 ″ as the selected dose is expelled. Further dosages may be delivered as required. FIG. 21 shows an example of a subsequently selected dosage. As noted above, the position of the limiting nut 28 ″ along the external thread of the drive sleeve 18 ″ corresponds to the amount of medicinal product remaining in the cartridge 4 ″; such that when the nut 28 ″ reaches the external flange 26 ″ and can rotate no further this corresponds to no medicinal product remaining in the cartridge 4 ″. It will be seen that if a user seeks to select a quantity of medical product greater than that remaining in the cartridge 4 ″, this cannot be done since when the nut 28 ″ stops rotating against the drive sleeve 18 ″, the drive sleeve 18 ″ and the housing 2 ″ will become locked together preventing rotation of the drive sleeve 18 ″ and hence the dose dial sleeve 36 ″. This prevents the setting of a larger dose than the amount of medical product remaining within the cartridge 4 ″. FIG. 22 shows a drug delivery device according to the present invention in which the entire medicinal product within the cartridge 4 ″ has been expelled. The illustrated embodiment of the device according to the invention further comprises a maximum dosage dial end stop. When the dose dial sleeve 36 ″ is dialed fully out, the external flange 26 ″ on the drive sleeve 18 ″ engages the internal flange 46 ″ in the housing 2 ″. It will be seen that if the user tries to dial beyond the maximum dosage, this cannot be done. When the drive sleeve 18 ″ stops rotating against the housing 2 ″, the dose dial sleeve is also prevented from rotating. The reaction between the external flange 44 ″ and the internal flange 86 ″ indicates to the user that the maximum dose has been dialed.

A drive mechanism suitable for use in drug delivery devices is disclosed. The drive mechanism may be used with injector-type drug delivery devices, such as those permitting a user to set the delivery dose. The drive mechanism may include a housing, a dose dial sleeve, and a drive sleeve. A clutch is configured to permit rotation of the drive sleeve and the dose dial sleeve with respect to the housing when the dose dial sleeve and drive sleeve are coupled through the clutch. Conversely, when the dose dial sleeve and drive sleeve are in a de-coupled state, rotation of the dose dial sleeve with respect to the housing is permitted and rotation of the drive sleeve with respect to the housing is prevented. In the de-coupled state, axial movement of the drive sleeve transfers force in a longitudinal direction for actuation of a drug delivery device.

CROSS REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application No. 62/001,725, filed on May 22, 2014, the content of which is hereby incorporated by reference in its entirety BACKGROUND Phosphatidylserine (PS), a membrane phospholipid, is typically localized to the internal surface of the membrane of a healthy cell. Under certain circumstances, PS is also found on the external surface. See Leventis et al., Annu. Rev. Biophys. 2010, 39, 407-27. More specifically, PS is exposed on the external surface of cancer cells. See Thorpe et al., Breast Cancer Res Treat 1995, 36(2), 237-51; Ran et al., Int. J. Radiat. Oncol. Biol. Phys. 2002, 54(5), 1479-84; and Thorpe, Thromb. Res. 2010, 125 Suppl 2, S134-137. Further, recent studies found that PS exists in tumor vasculatures and tumor-derived microvessels. See Stafford et al., Neoplasia. 2011, 13, 299-308; and Yin et al., Cancer Immunology Research 2013, 1, 1-13. Moreover, in many pathogenic particles such as bacteria and viruses, PS is exposed at high levels on the external surface. See Huang et al., Cancer Res. 2005, 65(10), 4408-16; and White et al., Bioconjug. Chem. 2010, 21(7), 1297-1304. Finally, PS has been found on the outer surface of cells in which cell death pathways have been dysregulated. For example, in addition to cancer, conditions such as neurodegenerative disorders, cardiovascular disease, autoimmune diseases, and metabolic disorders demonstrate surface localization of PS. See Smith et al., Mol. Pharm. 2011, 8(2), 583-90. Thus, PS provides a valuable target for delivery of therapeutic agents for treating the conditions mentioned above. Protein Annexin V is currently used to deliver therapeutic agents via binding to PS. However, this binding requires high levels of Ca 2+ , which might activate “scramblases” that could externalize PS in nearby normal cells, resulting in undesired targeting of the normal cells. There is a need to develop a delivery agent that selectively associates with disease-relevant PS to achieve site-specific delivery of a therapeutic agent. SUMMARY This invention is based on an unexpected discovery that certain dipicolylamine derivatives are effective in delivery a therapeutic agent to a target disease site that has phosphatidylserine on the external surfaces of cell membranes. In one aspect, this invention relates to compounds of formula (I) shown below: In this formula, each of A 1 , A 2 , A 3 , A 4 , A 5 , A 6 , and B 1 , independently, is a C 1 -C 6 bivalent aliphatic radical, a C 1 -C 6 bivalent heteroaliphatic radical, a bivalent aryl radical, or a bivalent heteroaryl radical; B 2 is a bond, a C 1 -C 6 bivalent aliphatic radical, a C 1 -C 6 bivalent heteroaliphatic radical, a bivalent aryl radical, a bivalent heteroaryl radical, D 1 -NR 1 —C(O)-D 2 , D 1 -C(O)NR 1 -D 2 -NR 1 ′—C(O)-D 3 , D 1 -D 2 -C(O)—NR 1 —C(O)-D 3 , or D 1 -D 2 -D 3 , each of D 1 , D 2 , D 3 , independently, being a C 1 -C 6 bivalent aliphatic radical, a C 1 -C 6 bivalent heteroaliphatic radical, a bivalent aryl radical, a bivalent heteroaryl radical, a C 1 -C 10 bivalent aralkyl radical, or a C 1 -C 10 bivalent heteroaralkyl radical, and each of R 1 and R 1 ′, independently, being H, a C 1 -C 6 bivalent heteroaliphatic radical, a bivalent aryl radical, a bivalent heteroaryl radical, or a C 1 -C 10 bivalent aralkyl radical; each of L 1 and L 2 , independently, is a bond, NR 2 , NR 2 C(O), NR 2 C(S), NR 2 CR 3 R 4 , NR 2 SO 2 , NR 2 C(O)NR 3 or NR 2 C(S)NR 3 , each of R 2 , R 3 , and R 4 , independently, being H, a C 1 -C 6 monovalent aliphatic radical, a C 1 -C 6 monovalent heteroaliphatic radical, a monovalent aryl radical, a monovalent heteroaryl radical, a C 1 -C 14 monovalent aralkyl radical, a C 1 -C 14 monovalent heteroaralkyl radical, C(s)R′ or C(O)R′, in which R′ is a C 1 -C 6 monovalent aliphatic radical, a C 1 -C 6 monovalent heteroaliphatic radical, a monovalent aryl radical, a monovalent heteroaryl radical, a C 1 -C 14 monovalent aralkyl radical, or a C 1 -C 14 monovalent heteroaralkyl radical, provided that at least one of L 1 and L 2 is not a bond; each of W 1 , W 2 , W 3 , W 4 , W 5 , W 6 , W 7 , and W 8 , independently, is N or CR 5 , R 5 being H, halo, cyano, amino, hydroxyl, nitro, sulfhydryl, a C 1 -C 6 aliphatic radical, a C 1 -C 6 heteroaliphatic radical, or a haloaliphatic radical; X is a bond, O, S, or NR 6 , R 6 being H, a C 1 -C 6 monovalent aliphatic radical, a C 1 -C 6 monovalent heteroaliphatic radical, a monovalent aryl radical, a monovalent heteroaryl radical, a C 1 -C 14 monovalent aralkyl radical, or a C 1 -C 14 monovalent heteroaralkyl radical; Y is a aryl ring or a heteroaryl ring; and Z is a therapeutic moiety. Each of the aliphatic radical, the heteroaliphatic radical, the aralkyl radical, and the heteroaralkyl radical is unsubstituted or substituted with halo, cyano, amino, hydroxyl, nitro, sulfhydryl, C 1 -C 6 alkoxy, C 1 -C 6 alkylamino, C 1 -C 12 dialkylamino, and C 1 -C 6 haloalkyl; and each of the aryl radical and the heteroaryl radical is unsubstituted or substituted with halo, cyano, amino, hydroxyl, nitro, sulfhydryl, a C 1 -C 6 aliphatic radical, a C 1 -C 6 heteroaliphatic radical, or a haloaliphatic radical. A subset of the compounds described above are those of formula (I), in which Y is Referring to formula (I) again, another subset are those, in which each of W 1 , W 2 , W 3 , and W 4 is N, and each of W 5 , W 6 , W 7 , and W 8 is CH; or in which each of W 1 , W 2 , W 3 , and W 8 is N, and each of W 4 , W 5 , W 6 , and W 7 is CH. Still another subset are those of formula (I), in which each of A 1 , A 2 , A 3 , A 5 , A 5 , and A 6 is methylene. Further, in the compounds of formula (I), B 1 can be ethylene, propylene, butylene, or hexylene; X can be O or NH; L 2 can be C(O). Also, in the above-described compounds, L 1 can be a bond, NH, NHCH 2 , NHC(O), NHSO 2 , NHC(O)NH, Moreover, in the compounds of formula (I), B 2 can be a bond, ethylene, phenylene, In compounds of formula (I), Z, a therapeutic moiety, is formed from a therapeutic drug. It is connected to L 2 via a bond, e.g., an amide bond or an ester or thioester bond. Upon release from formula (I) via enzymatic hydrolysis, Z is converted to a therapeutic drug that exerts a cytotoxic effect, e.g., anti-proliferation. Preferably, Z is an anticancer therapeutic moiety, an antivirus therapeutic moiety, an antibiotic therapeutic moiety, an immuno-stimulatory therapeutic moiety, an immuno-suppressive therapeutic moiety, a therapeutic moiety for treating a cardiovascular disease, or a cytotoxic moiety. Examples of Z include, but are not limited to, The term “aliphatic” herein refers to a saturated or unsaturated, linear or branched, acyclic, cyclic, or polycyclic hydrocarbon moiety. Examples include, but are not limited to, alkyl, alkylene, alkenyl, alkenylene, alkynyl, alkynylene, cycloalkyl, cycloalkylene, cycloalkenyl, cycloalkenylene, cycloalkynyl, and cycloalkynylene moieties. The term “heteroaliphatic” herein refers to an aliphatic moiety containing at least one heteroatom selected from N, O, P, B, S, Si, Sb, Al, Sn, As, Se, and Ge. The term “haloaliphatic” herein refers to an aliphatic moiety substituted with one or more halogen atoms. The term “alkyl” herein refers to a straight or branched hydrocarbon group, containing 1-20 (e.g., 1-10 and 1-6) carbon atoms. Examples include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, and t-butyl. The term “alkylene” refers to bivalent alkyl. Examples include —CH 2 —, —CH 2 CH 2 —, —CH 2 CH 2 CH 2 —, —CH 2 (CH 3 )CH 2 —, and —CH 2 CH 2 CH 2 CH 2 —. The term “haloalkyl” refers to alkyl substituted with one or more halogen (chloro, fluoro, bromo, or idodo) atoms. Examples include trifluoromethyl, bromomethyl, and 4,4,4-trifluorobutyl. The term “haloalkylene” refers to bivalent haloalkyl. The term “heteroalkylene” refers to a bivalent alkyl group, in which one or more carbon atoms are replaced by a heteroatom (e.g., O, N, P, and S). The term “alkoxy” refers to an —O-alkyl group. Examples include methoxy, ethoxy, propoxy, and isopropoxy. The term “haloalkoxy” refers to alkoxy substituted with one or more halogen atoms. The term “alkenyl” refers to a straight or branched hydrocarbon group, containing 2-20 (e.g., 2-10 and 2-6) carbon atoms and one or more double bonds. The term “cycloalkyl” refers to a saturated and partially unsaturated monocyclic, bicyclic, tricyclic, or tetracyclic hydrocarbon group having 3 to 12 carbons. Examples of cycloalkyl groups include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclopentenyl, cyclohexyl, cyclohexenyl, cycloheptyl, and cyclooctyl. The term “cycloalkylene” refers to bivalent cycloalkyl. The term “heterocycloalkyl” refers to a nonaromatic 5-8 membered monocyclic, 8-12 membered bicyclic, or 11-14 membered tricyclic ring system having one or more heteroatoms (e.g., O, N, P, and S). Examples of heterocycloalkyl groups include, but are not limited to, piperazinyl, imidazolidinyl, azepanyl, pyrrolidinyl, dihydrothiadiazolyl, dioxanyl, morpholinyl, tetrahydropuranyl, and tetrahydrofuranyl. The term “heterocycloalkylene” refers to bivalent heterocycloalkyl. The term “aryl” refers to a 6-carbon monocyclic, 10-carbon bicyclic, 14-carbon tricyclic aromatic ring system wherein each ring may have 1 to 5 substituents. Examples of aryl groups include phenyl, naphthyl, and anthracenyl. The term “arylene” refers to bivalent aryl. The term “aralkyl” refers to alkyl substituted with an aryl group. The term “aralkenyl” refers to alkenyl substituted with an aryl group. The term “heteroaryl” refers to an aromatic 5-8 membered monocyclic, 8-12 membered bicyclic, or 11-14 membered tricyclic ring system having one or more heteroatoms (e.g., O, N, P, and S). Examples include triazolyl, oxazolyl, thiadiazolyl, tetrazolyl, pyrazolyl, pyridyl, furyl, imidazolyl, benzimidazolyl, pyrimidinyl, thienyl, quinolinyl, indolyl, thiazolyl, and benzothiazolyl. The term “heteroaralkyl” refers to an alkyl group substituted with a heteroaryl group. The term “heteroaralkenyl” refers to an alkenyl group substituted with a heteroaryl group. The term “heteroarylene” refers to bivalent heteroaryl. The term “halo” refers to a fluoro, chloro, bromo, or iodo radical. The term “amino” refers to a radical derived from amine, which is unsubstituted or mono-/di-substituted with alkyl, aryl, cycloalkyl, heterocycloalkyl, or heteroaryl. The term “alkylamino” refers to alkyl-NH—. The term “dialkylamino” refers to alkyl-N(alkyl)-. The term “acyl” refers to —C(O)-alkyl, —C(O)-aryl, —C(O)-cycloalkyl, —C(O)-heterocycloalkyl, or —C(O)-heteroaryl. Alkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, aralkyl, heteroaralkyl, alkoxy, and aryloxy mentioned herein include both substituted and unsubstituted moieties. Examples of substituents include, but are not limited to, halo, hydroxyl, amino, cyano, nitro, mercapto, alkoxycarbonyl, amido, carboxy, alkanesulfonyl, alkylcarbonyl, carbamido, carbamyl, carboxyl, thioureido, thiocyanato, sulfonamido, alkyl, alkenyl, alkynyl, alkyloxy, aryl, heteroaryl, cycloalkyl, and heterocycloalkyl, in which alkyl, alkenyl, alkynyl, alkyloxy, aryl, heteroaryl cycloalkyl, and heterocycloalkyl may further substituted. Herein, the term “compound” refers to the compounds described above, as well as their salts, solvates, and metal complexes. A salt can be formed between an anion and a positively charged group (e.g., amino) on a compound; examples of a suitable anion include chloride, bromide, iodide, sulfate, nitrate, phosphate, citrate, methanesulfonate, trifluoroacetate, acetate, malate, tosylate, tartrate, fumurate, glutamate, glucuronate, lactate, glutarate, and maleate. A salt can also be formed between a cation and a negatively charged group; examples of a suitable cation include sodium ion, potassium ion, magnesium ion, calcium ion, and an ammonium cation such as tetramethylammonium ion. A salt further includes those containing quaternary nitrogen atoms. A solvate refers to a complex formed between an active compound and a pharmaceutically acceptable solvent. Examples of a pharmaceutically acceptable solvent include water, ethanol, isopropanol, ethyl acetate, acetic acid, and ethanolamine. A metal complex can be formed of a compound and a metal ion. The metal ion is a cation having two or more charges. The metal complex is typically formed via chelation of a metal ion and a compound of formula (I). Examples of the metal ion include Zn 2+ , Cu 2+ , Ca 2+ , Mg 2+ , Mn 2+ , Ni 2+ , Co 2+ , Fe 2+ , Cd 2+ , and a combination thereof. This invention also features use of one of the above-described compounds for the manufacture of a medicament for treating PS-related conditions. Thus, this invention also relates to use of such a compound for treating a PS-related condition by administering to a subject in need of the treatment an effective amount of a compound of this invention and an effective amount of one or more other active agents. Also within the scope of the present invention is a pharmaceutical composition containing a pharmaceutically acceptable carrier and a complex of a metal ion and one of the compounds of formula (I) described above. The pharmaceutical composition can further contain another therapeutic agent for treating PS-related conditions. Active agents include, but are not limited to, immunomodulatory agents, such as interferons α, β, and γ; antiviral agents such as ribavirin and amantadine; therapeutic agents target in any PS-related conditions. Such an active agent and a compound of this invention may be applied to a subject at two separate times or simultaneously but in two dosage forms. Alternatively, they can be combined in a composition as described above for use as a single dosage form. A composition for oral administration can be any orally acceptable dosage form including capsules, tablets, emulsions and aqueous suspensions, dispersions, and solutions. In the case of tablets, commonly used carriers include lactose and corn starch. Lubricating agents, such as magnesium stearate, are also typically added. For oral administration in a capsule form, useful diluents include lactose and dried corn starch. When aqueous suspensions or emulsions are administered orally, the active ingredient can be suspended or dissolved in an oily phase combined with emulsifying or suspending agents. If desired, certain sweetening, flavoring, or coloring agents can be added. Oral solid dosage forms can be prepared by spray dried techniques; hot melt extrusion strategy, micronization, and nano milling technologies. A nasal aerosol or inhalation composition can be prepared according to techniques well known in the art of pharmaceutical formulation. For example, such a composition can be prepared as a solution in saline, employing benzyl alcohol or other suitable preservatives, absorption promoters to enhance bioavailability, fluorocarbons, and/or other solubilizing or dispersing agents known in the art. A composition having an active compound can also be administered in the form of suppositories for rectal administration. The carrier in the pharmaceutical composition must be “acceptable” in the sense that it is compatible with the active ingredient of the composition (and preferably, capable of stabilizing the active ingredient) and not deleterious to the subject to be treated. One or more solubilizing agents can be utilized as pharmaceutical excipients for delivery of an active compound. Examples of other carriers include colloidal silicon oxide, magnesium stearate, cellulose, sodium lauryl sulfate, and D&C Yellow #10. Still within the scope of this invention is a method of treating a condition associated with cells containing inside-out phosphatidylserine. In this condition, normally intracellular phosphatidylserine is exposed on the outer surface of the cells. The method includes administering an effective amount of one of the compounds described above to a subject in need thereof. The compound of formula (I) can be administered as a complex formed of the compound and a metal ion having two or more positive charges (e.g., Zn 2+ ). The condition exists in viral infection, bacterial infection, inflammatory disease, cancer, misregulation of cell death in organ transplant, misregulation of cell death in neurodegenerative disease, and misregulation of cell death in cardiovascular disease. The term “treating” refers to application or administration of the compound to a subject with the purpose to cure, alleviate, relieve, alter, remedy, improve, or affect the disease, the symptom, or the predisposition. “An effective amount” refers to the amount of the compound which is required to confer the desired effect on the subject. Effective amounts vary, as recognized by those skilled in the art, depending on route of administration, excipient usage, and the possibility of co-usage with other therapeutic treatments such as use of other active agents. The details of one or more embodiments of the invention are set forth in the description below. Other features, objects, and advantages of the invention will be apparent from the description and from the claims. DETAILED DESCRIPTION Shown below are 51 exemplary compounds synthesized following the procedures described in Examples 1-51 and tested following the procedures described thereafter. All compounds listed below include their racemates (i.e., equal amounts of left- and right-handed enantiomers of a chiral molecule) unless otherwise specified. Com- pound num- Compound structures bers  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 The compounds of this invention can be prepared by synthetic methods well known in the art. See R. Larock, Comprehensive Organic Transformations (2 nd Ed., VCH Publishers 1999); P. G. M. Wuts and T. W. Greene, Greene's Protective Groups in Organic Synthesis (4 th Ed., John Wiley and Sons 2007); L. Fieser and M. Fieser, Fieser and Fieser's Reagents for Organic Synthesis (John Wiley and Sons 1994); and L. Paquette, ed., Encyclopedia of Reagents for Organic Synthesis (2 nd ed., John Wiley and Sons 2009) and subsequent editions thereof. The syntheses of Compounds 1-51 and their analytical data are shown below. Synthesis of Dipicolylamine Intermediate (DPA, Structure Shown Below) A dipicolylamine intermediate DPA was prepared according to the following steps: Step 1 To a stirred solution of 5-hydroxyisophthalic acid (25 g, 137 mmol, 1 eq.) in 200 mL of methanol at room temperature, 2,2-dimethoxypropane (1.2 eq.) and p-toluenesulfonic acid (TsOH, 0.2 eq.) were added. After stirring at 60° C., methanol was removed by evaporation. The resultant crude mixture was partitioned in ethyl acetate (EtOAc)/water. The organic layer was dried with magnesium sulfate (MgSO 4 ) and concentrated to give a crude product, which was purified by silica-column chromatography to yield 2,2-dimethoxypropane (23 g, 79%). 1 H NMR (300 MHz, CDCl 3 ) δ 3.96 (s, 6H), 7.77 (s, 2H), 8.26 (s, 1H). Step 2 To a solution of dimethyl 5-hydroxyisophthalate (28 g, 133 mmol, 1 eq.) in 1400 mL of dry tetrahydrofuran (THF) at ice-bath temperature, lithium aluminum hydride (LiAlH 4 or LAH, 4 eq.) was slowly added with stirring. The resultant mixture was allowed warm to 40° C., stirred at this temperature for 16 hours, and then was added an ammonium chloride (NH 4 Cl) aqueous solution to quench the reaction. After stirring for 1.5 hours, the mixture was filtered with celite, washed with THF. Organic volatiles were evaporated and the residue was partitioned between water and EtOAc. The aqueous phase was extracted with EtOAc three times. The combined EtOAc layers were dried over MgSO 4 to give product (5-hydroxy-1,3-phenylene)dimethanol (17 g, 82%). 1 H NMR (400 MHz, CDCl 3 ) δ 4.57 (s, 6H), 6.71 (s, 2H), 6.80 (s, 1H). Step 3 To a stirred solution of (5-hydroxy-1,3-phenylene)dimethanol (7.27 g, 47 mmol, 1 eq.) in 200 mL of acetonitrile at room temperature, 2-(4-bromobutyl)isoindoline-1,3-dione (1.2 eq.) and potassium carbonate (K 2 CO 3 , 2 eq.) were slowly added. The resultant mixture was then heated at reflux for 8 hours, after which the volatiles were removed, and the residue was partitioned between EtOAc and water. The EtOAc layer was washed with brine and dried over MgSO 4 . Evaporation of EtOAc gave 2-(4-(3,5-bis(hydroxymethyl)phenoxy)butyl)isoindoline-1,3-dione (13 g, 78% yield). 1 H NMR (400 MHz, CDCl 3 ) δ 1.67-1.65 (m, 2H), 1.86-1.81 (m, 2H), 3.75 (t, J=5.6 Hz, 2H), 4.00 (t, J=6.0 Hz, 2H), 4.63 (s, 2H), 4.64 (s, 2H), 6.81 (s, 2H), 6.91 (s, 1H), 7.71-7.69 (m, 2H), 7.84-7.82 (m, 2H). Step 4 To a stirred solution of 2-(4-(3,5-bis(hydroxymethyl)phenoxy)butyl)isoindoline-1,3-dione (7.44 g, 21 mmol, 1 eq.) in 420 mL of anhydrous dichloromethane (CH 2 Cl 2 ) in an ice bath, triphenylphosphine (PPh 3 , 2.3 eq.) and carbon tetrabromide (CBr 4 , 4.5 eq.) were slowly added. The resultant reaction mixture was allowed to warm to room temperature, stirred for 16, and added methanol (MeOH) to quench the reaction. After CH 2 Cl 2 and MeOH were evaporated, the residue was partitioned in CH 2 Cl 2 /water. The CH 2 Cl 2 layer was dried over MgSO 4 and concentrated by evaporation to give a crude product, which was purified by silica-column chromatography to yield product (5.2 g, 51%). 1 H NMR (300 MHz, CDCl 3 ) δ 1.90-1.81 (m, 4H), 3.77 (t, J=6.6 Hz, 2H), 4.00 (t, J=5.7 Hz, 2H), 4.41 (s, 4H), 6.82 (s, 2H), 6.98 (s, 1H), 7.74-7.70 (m, 2H), 7.86-7.84 (m, 2H). Step 5 To a stirred solution of 2-(4-(3,5-bis(bromomethyl)phenoxy)butyl)isoindoline-1,3-dione (3.86 g, 8.06 mmol, 1 eq.) in 25 mL of dry dimethylformamide (DMF) at room temperature, bis(pyridin-2-ylmethyl)amine (2 eq.) and K 2 CO 3 (5 eq.) were slowly added. After stirring for 16 hours, DMF was evaporated. The resultant crude mixture was partitioned in CH 2 Cl 2 /water. The CH 2 Cl 2 layer was dried over MgSO 4 , and concentrated to give a crude product, which was purified by silica-column chromatography to yield product A (4.8 g, 83%). 1 H NMR (400 MHz, CDCl 3 ) δ 1.89-1.82 (m, 4H), 3.61 (s, 4H), 3.78-3.74 (m, 10H), 3.96 (t, J=6.0 Hz, 2H), 6.82 (s, 2H), 7.03 (s, 1H), 7.12-7.08 (m, 4H), 7.63-7.53 (m, 8H), 7.69-7.67 (m, 2H), 7.82-7.80 (m, 2H), 8.48 (d, J=4.8 Hz, 4H). Step 6 To a stirred solution of compound A (5.9 g, 8.23 mmol, 1 eq.) in 200 mL of ethanol (EtOH) at room temperature, hydrazine (H 2 N—NH 2 , 10 eq.) was slowly added. The resultant reaction mixture was stirred for 16 hours, heated at reflux for 2 hours, and then cooled to room temperature. Removal of EtOH gave a crude mixture, which was extracted by CH 2 Cl 2 twice. The CH 2 Cl 2 solutions were combined, dried over MgSO 4 , and concentrated to afford DPA (4.1 g, 85%). 1 H NMR (300 MHz, CDCl 3 ) δ 1.65-1.55 (m, 2H), 1.84-1.75 (m, 2H), 2.75 (t, J=6.9 Hz, 2H), 3.56 (s, 4H), 3.78 (s, 8H), 3.94 (t, J=6.6 Hz, 2H), 6.84 (s, 2H), 7.04 (s, 1H), 7.13-7.08 (m, 4H), 7.63-7.55 (m, 8H), 8.48 (d, J=4.5 Hz, 4H). Synthesis of Nine DPA Linkers, DL-1 to DL-9 DL-1 DPA (400 mg, 0.681 mmol, 1 eq.) and triethylamine (1 mL) were dissolved in CH 2 Cl 2 (40 mL), followed by addition of ethyl 4-chloro-4-oxobutanoate at 0° C. The resultant solution, after stirring at 0° C. for 2 hours, was washed with a saturated ammonium chloride aqueous solution three times (3×40 ml). The CH 2 Cl 2 layers were dried over MgSO 4 and concentrated under reduced pressure to yield DL-1. 1 H NMR (400 MHz, CDCl 3 ) δ 1.27-1.19 (m, 3H), 1.70-1.67 (m, 2H), 1.84-1.78 (m, 2H), 2.44 (t, J=6.4 Hz, 2H), 2.77 (t, J=6.4 Hz, 2H), 3.43-3.29 (m, 2H), 3.64 (s, 4H), 3.79 (s, 8H), 3.96 (t, J=6 Hz, 2H), 4.16-4.09 (m, 2H), 6.83 (s, 2H), 7.05 (s, 1H), 7.14-7.11 (m, 4H), 7.64-7.57 (m, 8H), 8.50 (d, J=4.4 Hz, 4H). DL-2 DL-1 (487 mg, 0.68 mmol, 1 eq.) was dissolved in MeOH (4 mL) and a LiOH aqueous solution (4 mL, 0.5 N), and then stirred at room temperature for 15 hours. After removal of MeOH, the resultant residue was extracted with CH 2 Cl 2 (100 mL). The CH 2 Cl 2 solution was then washed with a saturated ammonium chloride aqueous solution twice (2×100 mL), dried over MgSO 4 , and concentrated under reduced pressure to yield DL-2 (380 mg). 1 H NMR (300 MHz, CDCl 3 ) δ 1.71-1.67 (m, 2H), 1.82-1.79 (m, 2H), 2.48 (m, 2H), 2.68 (m, 2H), 3.34 (m, 2H), 3.63 (s, 4H), 3.80 (s, 8H), 3.96 (t, J=8 Hz, 2H), 6.83 (s, 2H), 6.90 (s, 1H), 7.15-7.11 (m, 4H), 7.66-7.54 (m, 8H), 8.51 (d, J=4.8 Hz, 4H). DL-3 To a solution of DPA (400 mg, 0.68 mmol, 1 eq.) in CH 2 Cl 2 (40 mL) were added triethylamine (2 mL) and methyl 3-(chlorocarbonyl) benzoate at 0° C. The resultant reaction mixture, after stirring at 0° C. for 2 hours, was diluted with CH 2 Cl 2 (100 mL) The CH 2 Cl 2 solution was washed with a saturated aqueous solution of NH 4 Cl twice (2×100 mL), dried over MgSO 4 , and concentrated under reduced pressure to give a crude product, which is purified by column chromatography (silica gel; MeOH:CH 2 Cl 2 =1:13) to yield DL-3 (280 mg, 55%). 1 H NMR (400 MHz, CDCl 3 ) δ 1.91-1.84 (m, 4H), 3.58-3.54 (m, 2H), 3.63 (s, 4H), 3.78 (s, 8H), 3.91 (s, 3H), 4.02 (t, J=5.2 Hz, 2H), 6.85 (s, 2H), 7.05 (s, 1H), 7.13-7.10 (m, 4H), 7.50-7.46 (m, 1H), 7.63-7.56 (m, 8H), 8.00 (d, J=7.6 Hz, 1H), 8.12 (d, J=8 Hz, 1H), 8.36 (s, 1H), 8.49 (d, J=4.4 Hz, 4H). DL-4 DPA (1 g, 1.7 mmol, 1 eq.) and methyl 4-formylbenzoate (840 mg, 5.12 mmol, 3 eq) were dissolved in MeOH (20 mL) and stirred at 65° C. for 15 hours. After the solution was cooled to 0° C., sodium borohydride (1 g, 26 mmol, 15 eq) was added. The mixture was stirred at 0° C. for another hour. Removal of MeOH under reduced pressure gave a residue, which was extracted with CH 2 Cl 2 (100 mL) The CH 2 Cl 2 solution was washed with a saturated aqueous solution of NH 4 Cl twice (2×100 mL), dried over MgSO 4 , and concentrated under reduced pressure. The resultant residue was purified by column chromatography (silica gel; MeOH:CH 2 Cl 2 =1:9) to yield DL-4 (700 mg, 56%). 1 H NMR (300 MHz, CDCl 3 ) δ 1.90-1.68 (m, 4H), 2.71 (t, J=7.2 Hz, 2H), 3.63 (s, 4H), 3.79 (s, 8H), 3.82 (s, 2H), 3.86 (s, 3H), 3.95 (t, J=6 Hz, 2H), 6.83 (s, 2H), 7.04 (s, 1H), 7.14-7.09 (m, 4H), 7.40 (d, J=8.1 Hz, 2H), 7.63-7.55 (m, 8H), 7.98 (d, J=8.1 Hz, 2H), 8.48 (d, J 4.2 Hz, 4H). DL-5 DL-4 (600 mg, 0.82 mmol, 1 eq) and di-tert-butyl dicarbonate (360 mg, 1.65 mmol, 2 eq) were dissolved in CH 2 Cl 2 (60 mL) and stirred at room temperature for 15 hours. After CH 2 Cl 2 was removed, a residue was obtained and purified by column chromatography (silica gel; MeOH:CH 2 Cl 2 =1:13) to yield DL-5 (550 mg, 81%). 1 H NMR (300 MHz, CDCl 3 ) δ 1.45-1.40 (m, 9H), 1.72 (m, 2H), 1.89 (m, 2H), 3.31-3.21 (m, 2H), 3.64 (s, 4H), 3.79 (s, 8H), 3.89 (s, 3H), 3.92 (m, 2H), 4.47 (m, 2H), 6.82 (s, 2H), 7.07 (s, 1H), 7.14-7.09 (m, 4H), 7.27 (d, J=9 Hz, 2H), 7.63-7.56 (m, 8H), 7.98 (d, J=8.7 Hz, 2H), 8.50 (d, J=4.8 Hz, 4H). DL-6 DL-4 (300 mg, 0.41 mmol) was dissolved in MeOH (3 mL) and an aqueous LiOH solution (3 mL, 0.5 N). The resultant mixture was stirred at room temperature for 15 hours. Removal of MeOH gave a residue, which was extracted with CH 2 Cl 2 (100 mL) The CH 2 Cl 2 solution was then washed with a saturated aqueous solution of NH 4 Cl twice (2×100 mL), dried over MgSO 4 , and concentrated under reduced pressure to yield DL-6 (260 mg, 88%). DL-7 DL-5 (550 mg, 0.66 mmol) was dissolved in MeOH (6 mL) and an aqueous LiOH solution (6 mL, 0.5 N). The resultant mixture was stirred at room temperature 15 hours. MeOH was removed to give a residue, which was extracted with CH 2 Cl 2 (100 mL). The CH 2 Cl 2 solution was washed with a saturated aqueous solution of NH 4 Cl twice (2×100 ml), dried over MgSO 4 , and concentrated under reduced pressure to yield DL-7 (480 mg, 89%). 1 H NMR (300 MHz, CDCl 3 ) δ 1.50-1.26 (m, 13H), 3.29-3.23 (m, 2H), 3.65 (s, 4H), 3.81 (m, 10H), 4.53 (s, 2H), 6.77 (s, 2H), 6.93 (s, 1H), 7.15-7.11 (m, 4H), 7.38 (m, 2H), 7.63-7.53 (m, 8H), 8.10 (d, J=7.8 Hz, 2H), 8.54 (d, J=4.2 Hz, 2H) DL-8 DL-6 (260 mg, 0.36 mmol, 1 eq), K 2 CO 3 (745 mg, 5.40 mmol, 15 eq), 4-chloro-7-nitrobenzo[c][1,2,5]oxadiazole (100 mg, 0.50 mmol), and CH 2 Cl 2 (30 mL) were mixed and stirred at 40° C. for 15 hours. The resultant reaction mixture was then extracted with CH 2 Cl 2 (100 mL) Subsequently, the CH 2 Cl 2 solution was washed with water twice (2×100 mL), dried over MgSO 4 , and concentrated under reduced pressure. The resultant residue was purified by column chromatography (silica gel; MeOH:CH 2 Cl 2 =1:1) to yield DL-8 (200 mg, 63%) 1 H NMR (400 MHz, DMSO) δ 1.36 (m, 1H), 1.69-1.51 (m, 3H), 3.13 (m, 2H), 3.54 (s, 4H), 3.66 (m, 10H), 3.98 (m, 2H), 6.68 (m, 1H), 6.79 (d, J=4.4 Hz, 2H), 7.04 (d, J=5.6 Hz, 1H), 7.21-7.17 (m, 4H), 7.35-7.25 (m, 2H), 7.54-7.51 (m, 4H), 7.71-7.63 (m, 4H), 7.86 (d, J=8.4 Hz, 2H), 8.38 (m, 1H), 8.44 (d, J=5.2 Hz, 4H). DL-9 A solution of DL-3 (0.37 mmol) in MeOH (3 mL) and an aqueous LiOH solution (3 mL, 0.5 N) was stirred at room temperature for 15 hours. MeOH was removed under reduced pressure to give a residue, which was extracted with CH 2 Cl 2 (100 mL). The CH 2 Cl 2 solution was then washed with a saturated aqueous solution of NH 4 Cl twice (2×100 mL), dried over MgSO 4 , and concentrated under reduced pressure to yield DL-9 (240 mg, 88%). 1 H NMR (300 MHz, CDCl 3 ) δ 1.97-1.86 (m, 4H), 3.64 (m, 6H), 3.80 (s, 8H), 4.14 (m, 2H), 7.08 (s, 2H), 7.20-7.12 (m, 5H), 7.62-7.51 (m, 8H), 8.21 (d, J=7.2 Hz, 2H), 8.47 (s, 1H), 8.56 (d, J=4.8 Hz, 4H). EXAMPLE 1 Preparation of Compound 1 Compound 1 of this invention was prepared following the procedure described below. To a solution of DL-2 (200 mg, 0.29 mmol, 1 eq) in DMF (20 mL) were added 4,11-diethyl-4,9-dihydroxy-1H-pyrano[3′,4′:6,7]indolizino[1,2-b]quinoline-3,14 (4H,12H)-dione (170 mg, 0.44 mmol, 1.5 eq), hydroxybenzotriazole (117 mg, 0.87 mmol, 3 eq), N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (170 mg, 0.87 mmol, 3 eq), and N-methylmorpholine (175 mg, 1.74 mmol, 6 eq). After stirring at room temperature for 15 hours, the resultant reaction mixture was extracted with CH 2 Cl 2 (300 mL) Subsequently, the CH 2 Cl 2 solution was washed with a saturated aqueous solution of NaHCO 3 (300 mL) and water (5×300 mL), dried over MgSO 4 , and then concentrated under reduced pressure to give a residue. Compound 1 (130 mg, 42%) was obtained by purifying the residue with column chromatography (silica gel; MeOH:CH 2 Cl 2 =1:13). 1 H NMR (400 MHz, CDCl 3 ) δ 1.01 (t, J=7.2 Hz, 3H), 1.34 (t, J=7.6 Hz, 3H), 1.74-1.67 (m, 2H), 1.94-1.77 (m, 4H), 2.62 (t, J=6.4 Hz, 2H), 3.00 (t, J=6.4 Hz, 2H), 3.11-3.06 (m, 2H), 3.39-3.34 (m, 2H), 3.61 (s, 4H), 3.76 (s, 8H), 3.92 (t, J=j=6.0 Hz, 2H), 5.20 (s, 2H), 5.28 (d, J=16.4 Hz, 1H), 5.71 (d, J=16.4 Hz, 1H), 6.77 (s, 2H), 7.04 (s, 1H), 7.12-7.09 (m, 4H), 7.63-7.50 (m, 10H), 7.77 (d, J=2.4 Hz, 1H), 8.14 (d, J=9.2 Hz, 1H), 8.47 (d, J=4.8 Hz, 4H). Mass: (EM+2H + )/2. found 532.27. EXAMPLES 2-51 Preparation of Compounds 2-51 The synthesis of Compound 42 is described immediately below. As for compounds 2-41 and 43-51, they were obtained following a similar procedure or a procedure similar to that described in Example 1 above. Scheme 1 below depicts a synthetic sequence of preparing a linker, i.e., 42-Linker, from commercially available B via intermediates C and D. Synthesis of 42-Linker, a Linker for Use in Preparing Compound 42: Synthesis of Compound C: To a solution of the commercial available B (15 g, 101.21 mmol) in CH 2 Cl 2 (300 mL) was added trimethylamine (TEA, 1 eq.), followed by di-tert-butyl dicarbonate (Boc 2 O, 0.5 eq). The reaction was stirred at room temperature for 3 hours, after which time the solvent was removed in vacuo. The crude was partitioned between H 2 O and DCM. The layers were separated, and the organics were dried over sodium sulfate (Na 2 SO 4 ) and concentrated to a transparent oil. To the transparent oil in 200 ml of MeOH was added methyl 4-formylbenzoate (15 g, 91.35 mmol, 0.9 eq.). The sodium borohydride (3.7 g, 97.80 mmol, 0.9 eq.) was added after stirring at room temperature for 3 hours. The MeOH was removed and the residue dissolved in 200 ml CH 2 Cl 2 . The protonated product was extracted from CH 2 Cl 2 with 200 ml NH 4 Cl (aq) . The organic layers were combined, dried with Na 2 SO 4 , filtered and the solvent evaporated. Purification of the crude residue by flash chromatography on silica gel eluting with EtOAc/Hexane (2:1) to give 12.03 g of product C as a transparent oil (30.36 mmol, 30%). Synthesis of Compound D: To the compound C (12.03 g, 30.36 mmol) in 200 ml CH 2 Cl 2 was added 1-(4-Chlorophenyl)cyclo-hexanecarbonyl chloride (11.57 g, 45.54 mmol, 1.5 eq.) and triethylamine (10 ml, 43.08 mmol). The reaction was stirred for 2 hours at room temperature. The protonated product was extracted from 200 ml CH 2 Cl 2 with 200 ml NH 4 Cl (aq) . The organic layer was dried with Na 2 SO 4 , filtered, and the solvent evaporated. Purification of the crude residue by flash chromatography on silica gel eluting with EA/Hexane (2:1) gave 13.11 g of compound D as a transparent oil (21.25 mmol, 70%). Synthesis of Compound 42-Linker: To the compound D (13.11 g, 21.25 mmol) in MeOH (200 mL) was added 4 M hydrochloric acid (HCl) in dioxane (10 mL). The reaction was stirred at room temperature for 2 hours, after which time it was concentrated in vacuo. The crude was partitioned between NaH 4 Cl (aq) and DCM. The layers were separated, and the organics were dried (Na 2 SO 4 ) and concentrated to obtain compound 46-Linker as a transparent oil (7.68 g, 14.87 mmol, 70%). Scheme 2 below depicts a synthetic sequence of preparing Compound 42 from the intermediate DPA via intermediates E, F, G, H, and I. Synthesis of Compound 42: Synthesis of Compound E: To the above-mentioned DPA (10 g, 17.01 mmol) in 200 ml of MeOH was added methyl 4-formylbenzoate (5 g, 30.45 mmol, 1.8 eq.). Sodium borohydride (3.7 g, 97.80 mmol, 5.7 eq.) was added after stirring at room temperature for 3 hours. MeOH was removed and the residue was dissolved in 200 ml of CH 2 Cl 2 . The protonated product was extracted from CH 2 Cl 2 with 200 ml of 1M HCl (aq) . The aqueous layer was neutralized and the product was extracted into 200 ml of CH 2 Cl 2 . The organic layers were combined, dried with Na 2 SO 4 , and filtered, and the solvent was evaporated to give 11.26 g of product E as a yellow oil (15.30 mmol, 90%). 1 H NMR (300 MHz, CDCl 3 ): δ 1.70-1.78 (m, 2H), 1.80-1.86 (m, 2H), 2.71 (t, J=6.8 Hz, 2H), 3.62 (s, 4H), 3.78 (s, 8H), 3.87 (s, 2H), 3.89 (s, 3H), 3.95 (t, J=6.4 Hz, 2H), 6.82 (s, 2H), 7.03 (s, 1H), 7.03-7.13 (m, 4H), 7.40 (d, J=8.0 Hz, 2H), 7.55-7.62 (m, 8H), 7.98 (d, J=8.0 Hz, 2H), 8.48 (d, J=8.0 Hz, 2H). Synthesis of Compound F: To the compound E (11.26 g, 15.30 mmol) in 200 ml of CH 2 Cl 2 was added 1-(4-Chlorophenyl)cyclo-hexanecarbonyl chloride (7.71 g, 30.00 mmol, 2 eq.) and trimethylamine (5 ml, 21.54 mmol). The reaction was stirred for 2 hours at room temperature. The protonated product was extracted from 200 ml of CH 2 Cl 2 with 200 ml of 1M HCl (aq) . The aqueous layer was neutralized and the product was extracted into 200 ml of CH 2 Cl 2 . The organic layer was dried with Na 2 SO 4 , filtered, and the solvent was evaporated to give 13.17 g of product F as a yellow oil (13.77 mmol, 90%). 1 H NMR (300 MHz, CDCl 3 ): δ 1.62 (brs, 12H), 2.24 (brs, 2H), 2.90 (brs, 1H), 3.23 (brs, 1H), 3.63 (s, 4H), 3.78 (s, 8H), 3.88 (s, 3H), 0.3.92 (m, 2H), 4.02-4.14 (m, 2H), 6.78 (s, 2H), 6.95-7.39 (m, 11H), 7.55-7.63 (m, 8H), 7.93 (d, J=7.2 Hz, 2H), 8.48 (d, J=6.4 Hz, 4H). Synthesis of Compound G: To the compound F (13.17 g, 13.77 mmol) in 300 ml of MeOH was added 50 ml of 0.5M LiOH (aq) . The reaction mixture was stirred at room temperature for 15 hours. The solvent was removed and the residue was redissolved in CH 2 Cl 2 . The insoluble residue was filtered off. The filtrate was washed with water, dried over MgSO 4(s) ) and the solvent was removed under vacuum. The product G was obtained as yellowish powder (11.68 g, 12.39 mmol, 90%), which was directly used for the next step. Synthesis of Compound H: A solution containing G (11.68 g, 12.39 mmol) in 40 ml of DMF was heated to 40° C. EDCI (2 g, 12.8 mmol) and HOBt (2 g, 14.8 mmol) were added and the resulting reaction was allowed to stir at room temperature for 30 minutes, compound 42-Linker, 4-({{2-[2-(2-Amino-ethoxy)-ethoxy]-ethyl}-[1-(4-chloro-phenyl)-cyclohexanecarbonyl]-amino}-methyl)-benzoic acid methyl ester (9.6 g, 18.58 mmol) was added followed by addition of N-methylmorpholine (NMM, 5 ml, 45.5 mmol). The reaction was stirred at room temperature for 15 hours, after which time it was diluted with H 2 O. The aqueous solution was separated and extracted with 200 ml of CH 2 Cl 2 . The combined extracts were washed with brine (4×100 mL), dried over Na 2 SO 4(s) , filtered, and evaporated. Purification of the crude residue by flash chromatography on pH=7 silica gel eluting with MeOH/CH 2 Cl 2 (1:9) gave rise to ester compound H (7.14 g, 4.95 mmol, 40%). Synthesis of Compound I: To the compound H (7.14 g, 4.95 mmol) in 200 ml of MeOH was added 30 ml 0.5M LiOH (aq) . The reaction mixture was stirred at room temperature for 15 hours. The solvent removed and the residue was redissolved in 100 ml CH 2 Cl 2 . The insoluble residue filtered off. The filtrate was washed with water, dried over MgSO 4(s) ) and the solvent removed under vacuum. The product compound I was obtained as white powder (5.83 g, 4.08 mmol, 82%), which was directly used for the next step. Synthesis of Compound 42: A solution of I (5.83 g, 4.08 mmol) in 20 ml of DMF was heated to 40° C. 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDCI, 1 g, 6.4 mmol, 1.5 eq.) and hydroxybenzotriazole (HOBt, 1 g, 7.2 mmol, 1.7 eq.) were added and the reaction allowed to stir. After stirring at room temperature for 30 min, 4,11-diethyl-4,9-dihydroxy-1H-pyrano[3′,4′:6,7]indolizino[1,2-b]quinoline-3,14-(4H,12H)-dione (3 g, 7.64 mmol, 1.87 eq.) was added followed by N-methylmorpholine (NMM, 5 ml, 45.5 mmol). The reaction was stirred at room temperature for 15 hours, after which time it was diluted with H 2 O. The aqueous solution was separated and extracted with 100 ml of CH 2 Cl 2 . The combined extracts were washed with brine (4×100 mL), dried over Na 2 SO 4(s) , filtered, and evaporated. Purification of the crude residue by flash chromatography on pH=7 silica gel eluting with MeOH/CH 2 Cl 2 (0.5:9.5) gave rise to white power ester Compound 42 (2.21 g, 1.22 mmol, 30%). Compound 2 was prepared from DL-9 at a yield of 40%. 1 H NMR (400 MHz, CD 3 OD) δ 1.02 (t, J=7.6 Hz, 3H), 1.39 (t, J=7.6 Hz, 3H), 1.93-1.98 (m, 6H), 3.21-3.23 (m, 2H), 3.57 (m, 2H), 3.78 (s, 4H), 3.96 (d, J=16 Hz, 4H), 4.11 (m, 2H), 4.34 (d, J=16 Hz, 4H), 5.32 (s, 2H), 5.38 (d, J=16.4 Hz, 1H), 5.58 (d, J=16.4 Hz, 1H), 6.72 (s, 1H), 6.81 (s, 2H), 7.60 (d, J=7.6 Hz, 4H), 7.65 (s, 1H), 7.67-7.76 (m, 4H), 8.11-8.22 (m, 6H), 8.39 (d, J=7.2 Hz, 1H), 8.69 (d, J=4 Hz, 4H). Mass: (EM+2H + )/2. found 555.27. Compound 3: 1 H NMR (400 MHz, DMSO) δ 0.86 (t, J=6.8 Hz, 3H), 1.24 (t, J=7.6 Hz, 3H), 1.45 (m, 4H), 1.71 (m, 4H), 1.85 (m, 2H), 2.67 (m, 2H), 3.14-3.16 (m, 2H), 3.55 (s, 4H), 3.67 (s, 8H), 3.94 (m, 2H), 5.30 (s, 2H), 5.42 (s, 2H), 6.80 (s, 2H), 7.04 (s, 1H), 7.20-7.23 (m, 4H), 7.31 (s, 1H), 7.54 (d, J=7.6 Hz, 4H), 7.61 (d, J=9.2 Hz, 1H), 7.68-7.72 (m, 4H), 7.95 (s, 1H), 8.16 (d, J=8.8 Hz, 1H), 8.45 (d, J=5.6 Hz, 4H). Mass: (EM+2H + /2. found 510. Compound 4: 1 H NMR (300 MHz, CDCl 3 ) δ 1.05 (t, J=7.2 Hz, 3H), 1.39 (t, J=7.5 Hz, 3H), 1.97-1.83 (m, 6H), 3.13 (q, J=7.5 Hz, 2H), 3.50 (s, 4H), 3.54 (s, 8H), 3.60-3.64 (m, 2H), 4.04 (m, 2H), 5.28 (d, J=11.7 Hz, 2H), 5.30 (d, J=16.8 Hz, 1H), 5.74 (d, J=16.2 Hz, 1H), 6.80 (s, 2H), 7.12 (s, 1H), 7.31-7.18 (m, 12H), 738-7.41 (m, 8H), 7.55-7.60 (m, 1H), 7.66-7.68 (m, 2H), 7.93 (d, J=2.1 Hz, 1H), 8.06 (d, J=7.8 Hz, 1H), 8.27 (d, J=9 Hz, 1H), 8.34 (d, J=7.5 Hz, 1H), 8.63 (s, 1H). Mass: (EM+2H + )/2. found 553.74. Compound 5: 1 H NMR (300 MHz, CDCl 3 ) δ 1.05 (t, J=7.2 Hz, 3H), 1.41 (t, J=7.8 Hz, 3H), 1.83-1.97 (m, 6H), 2.78 (t, J=7.2 Hz, 2H), 3.13-3.21 (m, 2H), 3.65 (s, 4H), 3.80 (s, 8H), 3.96-4.00 (m, 4H), 5.27 (s, 2H), 5.31 (d, J=16.2 Hz, 1H), 5.76 (d, J=16.2 Hz, 1H), 6.84 (s, 2H), 7.07 (s, 1H), 7.10-7.15 (m, 4H), 7.52-7.66 (m, 11H), 7.69 (d, J=2.1 Hz, 1H), 7.95 (d, J=1.8 Hz, 1H), 8.21 (d, J=7.8 Hz, 2H), 8.28 (d, J=9 Hz, 1H), 8.50 (d, J=4.8 Hz, 4H). Mass: (EM+2H + )/2. found 549. Compound 6: 1 H NMR (300 MHz, CDCl 3 ): δ=8.61 (t, J=1.5 Hz, 1H), 8.49 (dt, J=4.8, 1.2 Hz, 4H), 8.34 (dt, J=7.8, 1.5 Hz, 1H), 8.25 (d, J=9.0 Hz, 1H), 8.07 (dt, J=8.1, 1.5 Hz, 1H), 7.92 (d, J=2.1 Hz, 1H), 7.67-7.63 (m, 3H), 7.62-7.56 (m, 9H), 7.41 (d, J=7.5 Hz, 1H), 7.30-7.27 (m, 5H), 7.25-7.18 (m, 1H), 7.14-7.10 (m, 4H), 7.07 (s, 1H), 6.80 (s, 2H), 6.15-6.11 (m, 1H), 5.73 (d, J=16.5 Hz, 1H), 5.31-5.25 (m, 3H), 4.84 (dd, J=14.0, 8.0 Hz, 1H), 3.89 (t, J=5.6 Hz, 2H), 3.79 (s, 8H), 3.64 (s, 4H), 3.36-3.10 (m, 6H), 1.97-1.83 (m, 2H), 1.66-1.57 (m, 4H), 1.40 (t, J=7.6 Hz, 3H), 1.04 (t, J=7.4 Hz, 3H). Mass: (EM+2H + )/2. found 629. Compound 7: 1 H NMR (300 MHz, CDCl 3 ): δ=8.46 (d, J=4.5 Hz, 4H), 8.28 (d, J=8.4 Hz, 2H), 8.24 (d, J=9.3 Hz, 1H), 7.97 (d, J=8.4 Hz, 2H), 7.87 (s, 1H), 7.66-7.55 (m, 10H), 7.11-7.07 (m, 4H), 7.04 (s, 1H), 6.79 (s, 2H), 5.68 (d, J=16.5 Hz, 1H), 5.27-5.22 (m, 3H), 3.95-3.89 (m, 2H), 3.77 (s, 8H), 3.62 (s, 4H), 3.10-3.08 (m, 4H), 1.90-1.72 (m, 6H), 1.35 (t, J=7.5 Hz, 3H), 0.98 (t, J=7.2 Hz, 3H). Mass: (EM+2H + )/2. found 574. Compound 8: 1 H NMR (400 MHz, CDCl 3 ): δ=8.48 (d, J=4.4 Hz, 4H), 8.38 (s, 1H), 8.04-8.00 (m, 2H), 7.76-7.71 (m, 3H), 7.60-7.57 (m, 4H), 7.54-7.51 (m, 5H), 7.48 (dd, J=9.2, 1.6 Hz, 1H), 7.30 (t, J=8.0 Hz, 1H), 7.11-7.08 (m, 4H), 6.96 (s, 1H), 6.83 (s, 2H), 6.06 (m, 1H), 5.68 (d, J=16.0 Hz, 1H), 5.22 (d, J=16.0 Hz, 1H), 5.19 (d, J=27.2 Hz, 1H), 5.14 (d, J=27.2 Hz, 1H), 3.99 (t, J=6.0 Hz, 2H), 3.76 (s, 8H), 3.60 (s, 4H), 3.39-3.36 (m, 2H), 3.00 (q, J=7.2 Hz, 2H), 1.92-1.81 (m, 4H), 1.74 (q, J=6.8 Hz, 2H), 1.32 (t, J=7.6 Hz, 3H), 0.99 (t, J=7.2 Hz, 3H). Mass: (EM+2H + )/2. found 563.25. Compound 9: 1 H NMR (400 MHz, CDCl 3 ): δ=8.65 (s, 1H), 8.49 (d, J=4.4 Hz, 4H), 8.41 (s, 1H), 8.26 (d, J=8 Hz, 1H), 8.16-8.08 (m, 3H), 8.01 (d, J=8 Hz, 1H), 7.87 (d, J=2.4 Hz, 2H), 7.64-7.51 (m, 8H), 7.14 (t, J=6 Hz, 4H), 7.00 (s, 1H), 6.79 (d, J=4.4 Hz, 2H), 5.45 (dd, J=172, 16.4, 2H), 5.21 (s, 1H), 5.08 (s, 2H), 5.03 (s, 1H), 3.88-3.82 (m, 10H), 3.66 (s, 4H), 3.58-3.46 (m, 4H), 3.25-3.22 (m, 2H), 3.10-2.95 (m, 4H), 2.58-2.51 (m, 2H), 1.94-1.83 (m, 2H), 1.70-1.57 (m, 4H), 1.36 (t, J=8 Hz, 3H), 1.02 (t, J=8 Hz, 3H). Mass: (EM+2H + )/2. found 667.29. Compound 11: 1 H NMR (300 MHz, CDCl 3 ): δ=8.47 (dd, J=5.1, 0.9 Hz, 4H), 8.22-8.19 (m, 2H), 7.85-7.82 (m, 2H), 7.64-7.52 (m, 16H), 7.43-7.30 (m, 6H), 7.11-7.04 (m, 5H), 6.85 (s, 2H), 5.71 (d, J=16.2 Hz, 1H), 5.27 (d, J=16.2 Hz, 1H), 5.22 (s, 2H), 4.68 (s, 2H), 4.05 (m, 2H), 3.76 (s, 8H), 3.61 (4H), 3.57 (m, 2H), 3.09 (q, J=7.5 Hz, 2H), 1.93-1.83 (m, 6H), 1.35 (t, J=7.8 Hz, 3H), 1.02 (t, J=7.5 Hz, 3H). Mass: (EM+2H + )/2. found 646.29. Compound 12: 1 H NMR (300 MHz, CDCl 3 ) δ 1.03 (t, J=7.5 Hz, 3H), 1.39 (t, J=7.5 Hz, 3H), 1.85 (m, 6H), 2.58-2.51 (m, 1H), 3.24-3.03 (m, 6H), 3.38-3.29 (m, 1H), 3.52-3.48 (m, 2H), 3.67 (s, 4H), 3.82 (s, 8H), 3.91-3.87 (m, 1H), 4.00 (t, J=4.8 Hz, 2H), 4.69 (d, J=3.0 Hz, 2H), 5.27 (d, J=12.0 Hz, 2H), 5.30 (d, J=16.5 Hz, 1H), 5.74 (d, J=16.2 Hz, 1H), 6.86 (s, 2H), 7.04 (s, 1H), 7.15-7.11 (m, 4H), 7.40-7.36 (m, 2H), 7.71-7.55 (m, 12H), 7.83 (d, J=2.1 Hz, 1H), 8.23 (d, J=9.3 Hz, 1H), 8.49 (d, J=4.8 Hz, 4H). Mass: (EM+2H + )/2. found 641.26. Compound 13: 1 H NMR (300 MHz, CDCl 3 ) δ 1.06-0.88 (m, 6H), 1.40 (t, J=7.5 Hz, 3H), 1.83-1.65 (m, 4H), 1.97-1.85 (m, 2H), 2.26 (t, J=7.5 Hz, 1H), 2.41 (t, J=7.2 Hz, 1H), 3.16 (m, 2H), 3.35 (m, 1H), 3.49 (m, 1H), 3.65 (s, 2H), 3.67 (s, 2H), 3.80 (s, 8H), 3.96 (m, 2H), 4.68 (s, 1H), 4.72 (s, 1H), 5.27 (s, 2H), 5.31 (d, J=14.1 Hz, 1H), 5.75 (d, J=16.2 Hz, 1H), 6.84 (s, 2H), 7.15-7.07 (m, 5H), 7.41-7.34 (m, 2H), 7.69-7.56 (m, 10H), 7.96-7.94 (m, 1H), 8.18 (d, J=8.4 Hz, 1H), 8.31-8.24 (m, 2H), 8.50 (d, J=4.5 Hz, 4H). Mass: (EM+2H + )/2. found 583.27. Compound 14: 1 H NMR (300 MHz, CDCl 3 ) δ 1.04 (t, J=7.5 Hz, 3H), 1.40 (t, J=8.1 Hz, 3H), 1.97-1.81 (m, 6H), 3.21-3.13 (m, 2H), 3.60 (t, J=7.2 Hz, 2H), 3.67 (s, 4H), 3.82 (s, 8H), 3.97 (m, 2H), 4.92 (s, 2H), 5.28 (d, J=3.9 Hz, 2H), 5.32 (d, J=13.2 Hz, 1H), 5.76 (d, J=16.2 Hz, 1H), 6.85 (s, 2H), 6.95-6.92 (m, 1H), 7.15-7.10 (m, 5H), 7.41 (d, J=4.8 Hz, 1H), 7.48 (d, J=7.8 Hz, 2H), 7.69-7.56 (m, 11H), 7.96 (m, 1H), 8.31-8.24 (m, 3H), 8.50 (d, J=4.5 Hz, 4H). Mass: (EM+2H + )/2. found 603.74. Compound 15: 1 H NMR (300 MHz, CDCl 3 ): δ=8.51 (d, J=4.2 Hz, 4H), 8.31-8.16 (m, 3H), 7.98-7.95 (m, 1H), 7.72-7.53 (m, 10H), 7.37 (d, J=8.1 Hz, 2H), 7.18-7.11 (m, 4H), 7.08 (s, 1H), 6.84 (s, 2H), 5.57 (dd, J=133, 16.5 Hz, 2H), 5.28 (s, 2H), 4.69 (d, J=4.8 Hz, 2H), 3.97 (d, J=5.4 Hz, 2H), 3.86-3.72 (m, 10H), 3.70-3.56 (m, 4H), 3.52-3.29 (m, 2H), 3.22-3.13 (m, 2H), 1.96-1.84 (m, 2H), 1.82-1.54 (m, 12H), 1.41 (t, J=7.2 Hz, 3H), 1.30-1.14 (m, 3H), 1.05 (t, J=7.2 Hz, 3H). Mass: (EM+2H + )/2. found 603.78. Compound 16: 1 H NMR (400 MHz, CDCl 3 ) δ 1.05 (t, J=7.2 Hz, 3H), 1.41 (t, J=7.6 Hz, 3H), 1.96-1.85 (m, 4H), 3.17 (q, J=8.0 Hz, 2H), 3.29 (s, 1H), 3.57 (s, 1H), 3.69 (s, 4H), 3.83 (s, 9H), 4.00 (s, 1H), 4.64 (s, 1H), 4.87 (s, 1H), 5.29 (d, J=5.6 Hz, 2H), 5.32 (d, J=17.2 Hz, 1H), 5.76 (d, J=16 Hz, 1H), 6.81 (s, 1H), 6.86 (s, 1H), 7.15-7.12 (m, 5H), 7.31-7.29 (m, 2H), 7.49 (m, 3H), 7.63-7.57 (m, 9H), 7.69-7.66 (m, 2H), 7.96 (d, J=2.8 Hz, 1H), 8.25 (d, J=8.4 Hz, 2H), 8.30 (d, J=9.2 Hz, 1H), 8.50 (d, J=4.8 Hz, 4H). Mass: (EM+2H + )/2. found 639.72. Compound 17: 1 H NMR (400 MHz, CDCl 3 ) δ 1.00 (t, J=7.2 Hz, 3H), 1.38 (t, J=7.6 Hz, 3H), 1.63 (m, 1H), 1.81-1.94 (m, 5H), 3.13 (q, J=7.2 Hz, 2H), 3.37 (m, 1H), 3.61 (m, 5H), 3.78 (m, 9H), 4.00 (m, 1H), 4.71 (s, 1H), 4.90 (s, 1H), 5.24 (d, J=8 Hz, 2H), 5.27 (d, J=16 Hz, 1H), 5.70 (d, J=16.4 Hz, 1H), 6.77 (s, 1H), 6.84 (s, 1H), 7.07-7.11 (m, 5H), 7.32-7.38 (m, 4H), 7.50-7.56 (m, 15H), 7.65 (d, J=9.2 Hz, 1H), 7.68 (s, 1H), 7.93 (d, J=2.4 Hz, 1H), 8.23 (d, J=8.4 Hz, 2H), 8.27 (d, J=9.2 Hz, 1H), 8.47 (d, J=4.4 Hz, 4H). Mass: (EM+2H + )/2. found 638.83. Compound 18: 1 H NMR (300 MHz, CDCl 3 ) δ 1.04 (t, J=7.5 Hz, 3H), 1.37 (t, J=7.8 Hz, 3H), 1.50-1.46 (m, 2H), 1.77 (m, 2H), 1.93-1.83 (m, 2H), 3.16 (q, J=7.5 Hz, 2H), 3.66 (s, 4H), 3.74-3.72 (m, 2H), 3.81 (s, 8H), 4.09-3.96 (m, 4H), 4.82 (d, J=9.3 Hz, 2H), 5.28 (d, J=4.2 Hz, 2H), 5.31 (d, J=14.7 Hz, 1H), 5.75 (d, J=16.2 Hz, 1H), 6.75 (s, 1H), 6.85 (s, 1H), 7.26-7.10 (m, 15H), 7.50 (d, J=7.8 Hz, 2H), 7.68-7.55 (m, 10H), 7.95 (d, J=1.8 Hz, 1H), 8.21-8.17 (m, 2H), 8.29 (d, J=9.0 Hz, 1H), 8.49 (d, J=4.5 Hz, 4H). Mass: (EM+2H + )/2. found 645.79. Compound 19: 1 H NMR (300 MHz, CDCl 3 ) δ 1.01 (t, J=7.2 Hz, 3H), 1.38 (t, J=7.5 Hz, 3H), 1.74 (m, 2H), 1.93-1.84 (m, 6H), 3.18-3.10 (m, 2H), 3.39-3.44 (m, 2H), 3.64 (s, 4H), 3.78 (s, 8H), 3.94 (t, J=5.7 Hz, 2H), 4.62 (s, 2H), 5.31-5.25 (m, 3H), 5.71 (d, J=16.5 Hz, 1H), 6.81 (s, 2H), 7.13-7.08 (m, 6H), 7.43 (d, J=8.7 Hz, 2H), 7.62-7.54 (m, 8H), 7.65 (d, J=2.4 Hz, 1H), 7.67 (s, 1H), 7.92 (d, J=2.4 Hz, 1H), 8.15 (d, J=2.7 Hz, 1H), 8.20 (d, J=8.1 Hz, 2H), 8.27 (d, J=9.6 Hz, 1H), 8.48 (d, J=4.8 Hz, 4H), 8.64 (d, J=2.7 Hz, 1H). Mass: (EM+2H + /2. found 632. Compound 20: 1 H NMR (300 MHz, CDCl 3 ) δ 1.04 (t, J=7.8 Hz, 3H), 1.40 (t, J=7.2 Hz, 3H), 1.77 (m, 2H), 1.95-1.85 (m, 4H), 3.17-3.12 (m, 2H), 3.56 (m, 2H), 3.69 (s, 4H), 3.82 (s, 8H), 3.96 (m, 2H), 4.92 (s, 2H), 5.28 (s, 2H), 5.30 (d, J=16.5 Hz, 1H), 5.74 (d, J=16.5 Hz, 1H), 6.82 (s, 2H), 7.08 (s, 1H), 7.16-7.12 (m, 4H), 7.42 (d, J=7.8 Hz, 2H), 7.67-7.56 (m, 10H), 7.95 (s, 1H), 8.23 (d, J=7.5 Hz, 2H), 8.28 (d, J=9 Hz, 1H), 8.52 (m, 4H), 8.68 (s, 1H). Mass: (EM+2H + )/2. found 627. Compound 21: 1 H NMR (300 MHz, CDCl 3 ) δ 1.03 (t, J=7.2 Hz, 3H), 1.39 (t, J=7.5 Hz, 3H), 1.96-1.85 (m, 4H), 2.09 (m, 2H), 3.16-3.11 (m, 2H), 3.64 (m, 2H), 3.67 (s, 4H), 3.80 (s, 8H), 4.06 (t, J=6 Hz, 2H), 4.13 (m, 2H), 5.33-5.27 (m, 3H), 5.74 (d, J=16.8 Hz, 1H), 6.17 (d, J=8.4 Hz, 1H), 6.84 (s, 2H), 7.15-7.10 (m, 5H), 7.39 (d, J=8.1 Hz, 2H), 7.66-7.54 (m, 10H), 7.94 (s, 1H), 8.28-8.23 (m, 3H), 8.35 (d, J=9.3 Hz, 1H), 8.48 (d, J=5.1 Hz, 4H). Mass: (EM+2H + )/2. found 630. Compound 22: 1 H NMR (400 MHz, CDCl 3 ): δ=8.51 (s, 4H), 8.31-8.18 (m, 3H), 7.97-7.94 (m, 1H), 7.72-7.60 (m, 10H), 7.44-7.30 (m, 2H), 7.19-7.07 (m, 5H), 6.86 (s, 2H), 5.54 (dd, J=172, 16.4 Hz, 2H), 5.28 (s, 2H), 4.73 (d, J=16.4 Hz, 2H), 3.99 (s, 2H), 3.83-3.74 (m, 10H), 3.70-3.67 (m, 4H), 3.50 (s, 1H), 3.38 (s, 1H), 3.18 (s, 2H), 2.50-2.42 (m, 2H), 1.97-1.86 (m, 2H), 1.81 (s, 4H), 1.73-1.67 (m, 2H), 1.45-1.39 (m, 3H), 1.32-1.30 (m, 6H), 1.08-1.02 (m, 3H), 0.89-0.87 (m, 314). Mass: (EM+2H + )/2. found 604.79. Compound 23: 1 H NMR (400 MHz, CDCl 3 ) δ 1.04 (t, J=7.2 Hz, 3H), 1.41 (t, J=7.6 Hz, 3H), 1.59 (m, 1H), 1.76 (m, 1H), 1.96-1.83 (m, 4H), 3.20-3.14 (m, 2H), 3.30 (m, 1H), 3.59 (m, 1H), 3.67 (s, 4H), 3.81 (s, 8H), 3.89-4.02 (m, 2H), 4.66 (s, 1H), 4.90 (s, 1H), 5.28 (d, J=5.6 Hz, 2H), 5.31 (d, J=17.2 Hz, 1H), 5.75 (d, J=16.4 Hz, 1H), 6.78 (s, 1H), 6.86 (s, 1H), 7.14-7.10 (m, 5H), 7.42-7.35 (m, 5H), 7.63-7.57 (m, 10H), 7.69-7.66 (m, 2H), 7.96 (d, J=2.8 Hz, 1H), 8.24 (d, J=8 Hz, 2H), 8.29 (d, J=9.2 Hz, 1H), 8.50 (d, J=4.8 Hz, 4H). Mass: (EM+2H + /2. found 600.76. Compound 24: 1 H NMR (300 MHz, CDCl 3 ) δ 1.04 (t, J=7.5 Hz, 3H), 1.44-1.37 (m, 4H), 1.70-1.65 (m, 1H), 1.99-1.86 (m, 4H), 3.19-3.15 (m, 2H), 3.68-3.65 (m, 6H), 3.82-3.80 (m, 10H), 4.09-3.94 (m, 2H), 5.29 (s, 2H), 5.31 (d, J=16.2 Hz, 1H), 5.75 (d, J=16.2 Hz, 1H), 6.68 (s, 1H), 6.90 (s, 1H), 7.14-7.12 (m, 5H), 7.28 (d, J=5.1 Hz, 2H), 7.64-7.39 (m, 12H), 7.72-7.67 (m, 2H), 7.99-7.80 (m, 4H), 8.17 (d, J=8.1 Hz, 1H), 8.32-8.27 (m, 2H), 8.50 (d, J=4.5 Hz, 4H). Mass: (EM+2H + )/2. found 625.77. Compound 25: 1 H NMR (300 MHz, CDCl 3 ) δ 1.00 (t, J=7.2 Hz, 3H), 1.38 (t, J=7.5 Hz, 3H), 1.60-1.49 (m, 4H), 1.93-1.81 (m, 2H), 2.46 (s, 1H), 2.54 (s, 2H), 3.03 (m, 1H), 3.17-3.10 (m, 2H), 3.44 (m, 1H), 3.64 (s, 4H), 3.78 (s, 8H), 3.86 (m, 2H), 4.50 (s, 1H), 4.72 (s, 1H), 5.25 (d, J=4.2 Hz, 2H), 5.27 (d, J=16.8 Hz, 1H), 5.70 (d, J=16.5 Hz, 1H), 6.80-6.77 (m, 2H), 7.12-7.08 (m, 5H), 7.19-7.17 (m, 1H), 7.35-7.33 (m, 1H), 7.50-7.42 (m, 3H), 7.65-7.54 (m, 11H), 7.68 (s, 1H), 7.92 (d, J=2.4 Hz, 1H), 8.12-8.06 (m, 2H), 8.28 (d, J=9.0 Hz, 1H), 8.47 (d, J=4.8 Hz, 4H). Mass: (EM+2H + )/2. found 658.26. Compound 26: 1 H NMR (300 MHz, CDCl 3 ) δ 1.04 (t, J=7.2 Hz, 3H), 1.29 (m, 2H), 1.40 (t, J=7.5 Hz, 3H), 1.68 (m, 8H), 1.95-1.86 (m, 4H), 2.28 (m, 2H), 2.95 (m, 1H), 3.16 (q, J=7.5 Hz, 2H), 3.30 (m, 1H), 3.67 (s, 4H), 3.81 (s, 8H), 3.91 (m, 2H), 4.22 (s, 1H), 4.65 (s, 1H), 5.28 (d, J=3.6 Hz, 2H), 5.31 (d, J=15.3 Hz, 1H), 5.76 (d, J=16.5 Hz, 1H), 6.81 (s, 2H), 7.15-7.10 (m, 5H), 7.38-7.20 (m, 6H), 7.61-7.56 (m, 8H), 7.69-7.64 (m, 2H), 7.95 (d, J=1.8 Hz, 1H), 8.17 (d, J=7.8 Hz, 2H), 8.29 (d, J=9.3 Hz, 1H), 8.50 (d, J=4.2 Hz, 4H). Mass: (EM+2H + )/2. found 658.28. Compound 27: 1 H NMR (300 MHz, CDCl 3 ) δ 1.04 (t, J=7.2 Hz, 3H), 1.41 (t, J=7.5 Hz, 3H), 1.77-1.60 (m, 2H), 1.93-1.84 (m, 4H), 3.17 (q, J=7.2 Hz, 2H), 3.27 (m, 1H), 3.61 (m, 1H), 3.66 (s, 4H), 3.81 (s, 8H), 4.01-3.94 (m, 2H), 4.61 (s, 1H), 4.90 (s, 1H), 5.28 (s, 2H), 5.31 (d, J=15.3 Hz, 1H), 5.75 (d, J=16.2 Hz, 1H), 6.79 (s, 1H), 6.85 (s, 1H), 7.14-7.10 (m, 5H), 7.69-7.55 (m, 16H), 7.96 (s, 1H), 8.25 (d, J=7.5 Hz, 2H), 8.30 (d, J=9.0 Hz, 1H), 8.50 (d, J=4.8 Hz, 4H). Mass: (EM+2H + )/2. found 634.76. Compound 28: 1 H NMR (300 MHz, CDCl 3 ): δ=8.49 (dd, J=4.5, 0.9 Hz, 4H), 8.16 (d, J=9.3 Hz, 1H), 7.78 (d, J=2.1 Hz, 1H), 7.63-7.50 (m, 10H), 7.13-7.09 (m, 4H), 7.06 (s, 1H), 6.85 (s, 2H), 5.85 (t, J=6.0 Hz, 1H), 5.72 (d, J=16.2 Hz, 1H), 5.28 (d, J=16.2 Hz, 1H), 5.17 (s, 2H), 4.01 (t, J=5.4 Hz, 2H), 3.80 (s, 8H), 3.65 (s, 4H), 3.40 (q, J=6.0 Hz, 2H), 3.07 (q, J=7.5 Hz, 2H), 1.95-1.82 (m, 6H), 1.34 (t, J=7.5 Hz, 3H), 1.01 (t, J=7.2 Hz, 3H). Mass: (EM+2H + )/2. found 504. Compound 29: 1 H NMR (300 MHz, CDCl 3 ): δ=8.48 (d, J=4.8 Hz, 4H), 8.19 (d, J=9.0 Hz, 1H), 7.85-7.55 (m, 12H), 7.12-7.08 (m, 5H), 6.79 (s, 2H), 5.71 (dd, J=16.5, 7.2 Hz, 1H), 5.29 (d, J=16.5 Hz, 1H), 5.21 (d, J=7.8 Hz, 2H), 3.92 (m, 1H), 3.78-3.74 (m, 11H), 3.63-3.59 (m, 5H), 3.36-3.34 (m, 2H), 3.11-3.08 (m, 2H), 2.40-1.72 (m, 10H), 1.37-1.32 (m, 3H), 1.04 (t, J=7.2 Hz, 3H). Mass: (EM+2H + )/2. found 552. Compound 31: 1 H NMR (400 MHz, CDCl 3 ): δ=8.49 (d, J=4.4 Hz, 4H), 8.23 (dd, J=9.2, 5.2 Hz, 1H), 7.88-7.56 (m, 15H), 7.45-7.41 (m, 4H), 7.35 (t, J=6.4 Hz, 1H), 7.11-7.08 (m, 5H), 6.84 (s, 1H), 6.79 (s, 1H), 5.73 (d, J=16.0 Hz, 1H), 5.30 (d, J=16.0 Hz, 1H), 5.24 (s, 2H), 4.79 (s, 1H), 4.68 (s, 1H), 3.99 (t, J=5.6 Hz, 2H), 3.80-3.77 (m, 8H), 3.64-3.61 (m, 4H), 3.58-3.54 (m, 2H), 3.12-3.10 (m, 2H), 1.89-1.88 (m, 6H), 1.38-1.33 (m, 3H), 1.04-1.01 (m, 3H). Mass: (EM+2H + )/2. found 586.77. Compound 32: 1 H NMR (400 MHz, CDCl 3 ): δ=8.48 (d, J=4.8 Hz, 4H), 8.15 (t, J=8.0 Hz, 1H), 7.77 (s, 1H), 7.62-7.54 (m, 10H), 7.11 (t, J=6.0 Hz, 4H), 7.05 (s, 1H), 6.82 (s, 2H), 6.13-6.09 (m, 1H), 5.69 (d, J=16.4 Hz, 1H), 5.26 (d, J=16.4 Hz, 1H), 5.20 (s, 2H), 4.36 (d, J=12.8 Hz, 1H), 4.25 (d, J=12.0 Hz, 1H), 3.96 (t, J=5.6 Hz, 2H), 3.78 (s, 8H), 3.63 (s, 4H), 3.34 (q, J=6.4 Hz, 2H), 3.13-3.04 (m, 3H), 2.87 (t, J=11.2 Hz, 1H), 2.33-2.28 (m, 1H), 1.93-1.79 (m, 8H), 1.71 (q, J=7.6 Hz, 2H), 1.37 (t, J=7.6 Hz, 3H), 0.99 (t, J=7.2 Hz, 3H). Mass: (EM+2H + )/2. found 559.26. Compound 33: 1 H NMR (300 MHz, CDCl 3 ): δ=8.47 (d, J=4.8 Hz, 4H), 8.20 (d, J=9.0 Hz, 1H), 7.80-7.78 (m, 1H), 7.64-7.49 (m, 10H), 7.47-7.41 (m, 1H), 7.10 (t, J=6.0 Hz, 4H), 7.04 (s, 1H), 6.78 (s, 2H), 5.69 (d, J=16.5 Hz, 1H), 5.27 (d, J=16.5 Hz, 1H), 5.22 (s, 2H), 3.91 (m, 2H), 3.82 (m, 2H), 3.76 (s, 8H), 3.72-3.68 (m, 4H), 3.61 (s, 6H), 3.31-3.27 (m, 2H), 3.11 (q, J=7.2 Hz, 2H), 2.47-2.44 (m, 2H), 2.35-2.33 (m, 2H), 2.05-1.95 (m, 2H), 1.92-1.83 (m, 2H), 1.81-1.76 (m, 2H), 1.66 (m, 2H), 1.36 (t, J=7.5 Hz, 3H), 1.12-1.09 (m, 6H), 0.99 (t, J=7.5 Hz, 3H). Mass: (EM+2H + )/2. found 615.80. Compound 34: 1 H NMR (400 MHz, CDCl 3 ): δ=8.38 (d, J=4.0 Hz, 4H), 7.74-7.71 (m, 4H), 7.62-7.58 (m, 7H), 7.35 (dd, J=7.2, 2.4 Hz, 1H), 7.24-7.21 (m, 4H), 6.89 (s, 1H), 6.58 (s, 2H), 5.35 (m, 1H), 4.97 (m, 1H), 4.73 (s, 2H), 4.25-4.24 (m, 1H), 4.13-4.10 (m, 1H), 3.91 (s, 3H), 3.76 (t, J=5.6 Hz, 2H), 3.68 (s, 8H), 3.61 (m, 1H), 3.49 (s, 4H), 3.20-3.17 (m, 1H), 3.08-3.03 (m, 1H), 2.94 (d, J=18.4 Hz, 1H), 2.80 (d, J=18.4 Hz, 1H), 2.49-2.30 (m, 6H), 2.10-1.93 (m, 2H), 1.71-1.53 (m, 4H), 1.25 (d, J=6.8 Hz, 3H). Mass: (EM+2H + )/2. found 605. Compound 35: 1 H NMR (400 MHz, CDCl 3 ): δ=8.49 (d, J=4 Hz, 4H), 8.18 (d, J=9.2 Hz, 1H), 7.79 (s, 1H), 7.68-7.41 (m, 11H), 7.15-7.06 (m, 6H), 5.52 (dd, J=175.6, 16.4 Hz, 2H), 5.22 (s, 2H), 4.14 (s, 2H), 3.96 (s, 4H), 3.83-3.73 (m, 8H), 3.48 (s, 2H), 3.09-3.07 (m, 2H), 1.94-1.86 (m, 2H), 1.34 (t, J=7.6 Hz, 3H), 1.019 (t, J=7.6 Hz, 3H). Mass: (EM+2H + )/2. found 510. Compound 36: 1 H NMR (400 MHz, CDCl 3 ): δ=8.68 (s, 1H), 8.49 (d, J=4.4 Hz, 4H), 8.24 (t, J=8 Hz, 2H), 8.09 (d, J=8 Hz, 1H), 7.87 (d, J=2 Hz, 1H), 7.67 (s, 1H), 7.58-7.43 (m, 10H), 7.11-7.04 (m, 6H), 5.54 (dd, J=178.6, 16 Hz, 2H), 5.27 (s, 2H), 3.83-3.76 (m, 11H), 3.49 (s, 3H), 3.15 (q, J=7.6 Hz, 2H), 2.90 (t, J=6.4 Hz, 2H), 1.95-1.84 (m, 2H), 1.38 (t, J=7.6 Hz, 3H), 1.06 (t, J=7.6 Hz, 3H). Mass: (EM+2H + )/2. found 542. Compound 37: 1 H NMR (300 MHz, CDCl 3 ): δ=8.50-8.48 (m, 4H), 8.31-8.24 (m, 3H), 7.97 (s, 1H), 7.70-7.52 (m, 12H), 7.16-7.10 (m, 6H), 7.06 (s, 1H), 7.04 (s, 1H), 6.78 (s, 2H), 6.05 (s, 1H), 5.76 (d, J=16.5 Hz, 1H), 5.34-5.28 (m, 3H), 4.74 (s, 2H), 4.04 (m, 2H), 3.77 (s, 8H), 3.59 (s, 4H), 3.55 (m, 2H), 3.17 (q, J=7.5 Hz, 2H), 2.54 (q, J=7.5 Hz, 4H), 1.97-1.84 (m, 6H), 1.41 (t, J=7.8 Hz, 3H), 1.12 (t, J=7.5 Hz, 6H), 1.04 (t, J=7.2 Hz, 3H). Mass: (EM+2H + )/2. found 636. Compound 38: 1 H NMR (300 MHz, CDCl 3 ) δ 1.04 (t, J=7.5 Hz, 3H), 1.32-1.25 (m, 2H), 1.40 (t, J=7.5 Hz, 3H), 1.63 (m, 6H), 1.93-1.85 (m, 6H), 2.22-2.17 (m, 2H), 2.90 (m, 1H), 3.20-3.15 (m, 3H), 3.88-3.67 (m, 26H), 4.09 (s, 1H), 4.54 (s, 1H), 5.28 (d, J=10.5 Hz, 2H), 5.31 (d, J=12.0 Hz, 1H), 5.75 (d, J=16.2 Hz, 1H), 6.77 (s, 2H), 6.97 (m, 1H), 7.26-7.11 (m, 10H), 7.72-7.55 (m, 12H), 7.99-7.96 (m, 3H), 8.29-8.26 (m, 3H), 8.49 (d, J=4.8 Hz, 4H). Mass: (EM+2H + )/2. found 798. Compound 39: 1 H NMR (400 MHz, CDCl 3 ): δ=1.03 (t, J=7.2 Hz, 3H), 1.25 (m, 1H), 1.39 (t, J=7.6 Hz, 31-1), 1.65-1.96 (m, 11H), 2.01 (m, 2H), 2.24 (m, 2H), 3.13-3.19 (m, 3H), 3.44-3.54 (m, 5H), 3.59-3.64 (m, 12H), 3.77 (s, 8H), 3.97 (t, J=5.6 Hz, 2H), 4.30 (s, 1H), 4.67 (s, 1H), 5.27 (d, J=12.4 Hz, 2H), 5.30 (d, J=16.0 Hz, 1H), 5.74 (d, J=16.0 Hz, 1H), 6.80 (s, 2H), 7.05 (s, 1H), 7.09-7.12 (m, 5H), 7.20-7.30 (m, 5H), 7.54-7.62 (m, 8H), 7.65-7.68 (m, 2H), 7.76 (m, 4H), 7.94 (d, J=2.4 Hz, 1H), 8.13 (d, J=6.8 Hz, 2H), 8.28 (d, J=9.2 Hz, 1H), 8.48 (d, J=4.8 Hz, 4H). Mass: (EM+2H + )/2. found 798. Compound 40: 1 H NMR (300 MHz, CDCl 3 ): δ=1.04 (t, J=7.2 Hz, 3H), 1.25-1.29 (m, 1H), 1.39 (t, J=7.2 Hz, 3H), 1.66-1.97 (m, 9H), 2.17-2.26 (m, 3H), 2.75 (m, 1H), 3.12-3.20 (m, 3H), 3.39 (m, 1H), 3.74-3.86 (m, 12H), 4.10 (s, 1H), 4.72 (s, 1H), 5.27-5.34 (m, 3H), 5.75 (d, J=16.5 Hz, 1H), 6.99 (s, 2H), 7.12-7.14 (m, 4H), 7.20-7.31 (m, 6H), 7.44-7.46 (m, 4H), 7.55-7.60 (m, 4H), 7.64-7.67 (m, 3H), 7.93 (s, 1H), 8.10-8.18 (m, 2H), 8.28 (d, J=9.3 Hz, 1H), 8.51 (m, 4H). Mass: (EM+2H + )/2. found 645. Compound 41: 1 H NMR (CDCl 3 , 400 MHz): δ=1.12 (s, 3H), 1.21 (s, 3H), 1.68 (s, 3H), 1.91 (s, 3H), 1.63-2.33 (m, 4H), 2.26 (s, 3H), 2.41 (s, 3H), 2.38-2.58 (m, 8H), 2.72 (t, J=6.8 Hz, 2H), 3.18-3.27 (m, 2H), 3.64 (s, 4H), 3.78 (s, 8H), 3.94 (t, J=6.0 Hz, 2H), 4.19 (d, J=8.4 Hz, 1H), 4.30 (d, J=8.4 Hz, 1H), 4.43 (dd, J=10.8, 6.8 Hz, 1H), 4.96 (d, J=9.2 Hz, 1H), 5.67 (d, J=7.2 Hz, 1H), 5.88-5.93 (m, 2H), 6.20 (t, J=9.2 Hz, 1H), 6.29 (s, 1H), 6.81 (s, 2H), 7.06 (s, 1H), 7.06-7.12 (m, 4H), 7.27-7.63 (m, 24H), 7.79 (d, J=5.6 Hz, 2H), 8.13 (d, J=5.6 Hz, 2H), 8.48 (d, J=4.8 Hz, 4H). Mass: (EM+2H + )/2. found 762. Compound 42: 1 H NMR (CDCl 3 , 400 MHz): δ=0.98 (t, J=7.2 Hz, 3H), 1.22 (m, 8H), 1.38 (t, J=7.6 Hz, 3H), 1.88 (m, 2H), 2.01 (s, 5H), 2.10-2.41 (m, 8H), 2.85 (s, 1H), 2.92 (s, 1H), 3.15 (m, 3H), 3.44 (s, 2H), 3.50-3.71 (m, 13H), 3.76 (s, 8H), 3.86 (s, 2H), 4.10 (dd, J=7.2 Hz, 4H), 4.32 (s, 2H), 4.53 (s, 1H), 5.24 (s, 2H), 5.30 (d, J=16 Hz, 1H), 5.73 (d, J=16 Hz, 1H), 6.75 (s, 3H), 6.95 (br, 2H), 7.1-7.25 (m, 13H), 7.29 (d, J=8.4 Hz, 2H), 7.52-7.64 (m, 8H), 7.64-7.72 (m, 3H), 7.93 (d, J=2.4 Hz, 1H), 8.14 (d, J=7.2 Hz, 2H), 8.27 (d, J=9.2 Hz, 1H), 8.47 (d, J=8.8 Hz, 4H). Mass: (EM+2H + )/2. found 901.6. Compound 43: 1 H NMR (CDCl 3 , 400 MHz): δ=1.12 (s, 3H), 1.20 (s, 3H), 1.67 (s, 3H), 1.93 (s, 3H), 2.16 (s, 3H), 2.37 (s, 3H), 2.21-2.76 (m, 8H), 2.97 (d, J=6.8 Hz, 1H), 3.36-3.41 (m, 1H), 3.54-3.62 (m, 1H), 3.71 (t, J=4.4 Hz, 4H), 3.78 (s, 4H), 3.84 (s, 8H), 4.16-4.20 (m, 3H), 4.41-4.57 (m, 3H), 4.70 (s, 1H), 4.94 (d, J=9.2 Hz, 1H), 5.66 (dd, J=6.8, 3.6 Hz, 1H), 5.86-5.90 (m, 1H), 6.17 (q, J=9.2 Hz, 1H), 6.31 (d, J=4.4 Hz, 1H), 6.95 (s, 1H), 7.00 (s, 1H), 7.03-7.09 (m, 4H), 7.19-7.63 (m, 34H), 7.80 (dd, J=17.6, 7.2 Hz, 2H), 8.12 (m, 2H), 8.47 (d, J=4.8 Hz, 4H). Mass: (EM+2H + )/2. found 831. Compound 44: 1 H NMR (400 MHz, CDCl 3 ): δ=1.05 (t, J=7.2 Hz, 3H), 1.40 (t, J=7.6 Hz, 3H), 1.85-1.96 (m, 6H), 3.14-3.54 (m, 2H), 3.52-3.57 (m, 2H), 3.65 (s, 4H), 3.80 (s, 8H), 4.057-4.10 (m, 2H), 5.27 (s, 2H), 5.29 (d, J=16.0 Hz, 1H), 5.73 (d, J=16.0 Hz, 1H), 6.88 (s, 2H), 6.99 (d, J=8.4 Hz, 2H), 7.07-7.12 (m, 6H), 7.28-7.66 (m, 18H), 7.93 (d, J=2.8 Hz, 1H), 8.07 (d, J=8.4 Hz, 2H), 8.26 (d, J=9.2 Hz, 1H), 8.48 (d, J=4.8 Hz, 4H). Mass: (EM+2H + )/2. found 661.4. Compound 45: 1 H NMR (CDCl 3 , 300 MHz): δ=1.11 (s, 3H), 1.18 (s, 3H), 1.66 (s, 3H), 1.89 (s, 3H), 2.18 (s, 3H), 2.27 (s, 3H), 2.02-2.57 (m, 7H), 2.68 (t, J=6.6 Hz, 2H), 2.79 (t, J=5.7 Hz, 2H), 3.25 (q, J=4.8 Hz, 2H), 3.40 (t, J=5.1 Hz, 2H), 3.54-3.63 (m, 10H), 3.70 (t, J=4.5 Hz, 4H), 3.77 (s, 4H), 3.81 (s, 8H), 4.18 (d, J=8.8 Hz, 1H), 4.28 (d, J=8.8 Hz, 1H), 4.39-4.47 (m, 3H), 4.94 (d, J=9.0 Hz, 1H), 5.43 (d, J=3.6 Hz, 1H), 5.66 (d, J=6.6 Hz, 1H), 5.90 (dd, J=8.4, 3.6 Hz, 1H), 6.16 (t, J=9.0 Hz, 1H), 6.28 (s, 1H), 7.06-7.09 (m, 8H), 7.22-7.61 (m, 33H), 7.79 (dd, J=7.5 Hz, 2H), 8.11 (dd, J=7.5 Hz, 2H), 8.46 (d, J=4.5 Hz, 4H). Mass: (EM+2H + )/2. found 978. Compound 46: 1 H NMR (400 MHz, CDCl 3 ): δ=1.12 (s, 3H), 1.19 (s, 3H), 1.68 (s, 3H), 1.87-1.88 (m, 1H), 1.90 (s, 3H), 2.07-2.13 (m, 1H), 2.20 (s, 3H), 2.28-2.35 (m, 1H), 2.42 (s, 3H), 2.56 (t, J=6.8 Hz, 2H), 2.66-2.67 (m, 1H), 2.80 (t, J=6.8 Hz, 2H), 3.25-3.31 (m, 2H), 3.79-3.96 (m, 18H), 4.11 (s, 2H), 4.20 (d, J=8.8 Hz, 1H), 4.22-4.28 (m, 2H), 4.31 (d, J=8 Hz, 1H), 4.40-4.45 (m, 1H), 4.95 (d, J=8.4 Hz, 1H), 5.48 (d, J=3.6 Hz, 1H), 5.68 (d, J=6.8 Hz, 1H), 5.94 (dd, J=8.4, 3.6 Hz, 1H), 6.22 (t, J=8.8 Hz, 1H), 6.27 (s, 1H), 6.89 (d, J=8.4 Hz, 2H), 7.08-7.13 (m, 4H), 7.20 (d, J=7.6 Hz, 2H), 7.27-7.66 (m, 21H), 7.77 (d, J=7.2 Hz, 2H), 8.14 (d, J=7.2 Hz, 2H), 8.41 (d, J=4.8 Hz, 2H), 8.49 (d, J=4.8 Hz, 2H). Mass: (EM+2H + )/2. found 857.8. Compound 47: 1 H NMR (400 MHz, CDCl 3 ): δ=1.04 (t, J=7.2 Hz, 3H), 1.30 (s, 9H), 1.44 (t, J=7.6 Hz, 3H), 1.86-1.97 (m, 4H), 2.03-2.08 (m, 2H), 3.18-3.24 (m, 2H), 3.36-3.40 (m, 2H), 3.85 (s, 4H), 3.95 (s, 6H), 4.26 (s, 2H), 5.30-5.34 (m, 3H), 5.78 (d, 1.04, J=3.6 Hz, 3H), 7.09-7.13 (m, 2H), 7.17-7.21 (m, 2H), 7.5 (d, J=8 Hz, 2H), 7.60-7.76 (m, 9H), 7.84 (d, J=8.8 Hz, 2H), 8.0 (d, J=2.4 Hz, 1H), 8.28-8.32 (m, 4H), 8.48 (d J=7.6 Hz, 2H), 8.55 (d, J=6.8 Hz, 2H). Mass: (EM+2H + )/2. found 626.8. Compound 48: 1 H NMR (CDCl 3 , 400 MHz): δ=0.88 (m, 6H), 1.03 (t, J=6.8 Hz, 3H), 1.39 (t, J=7.2 Hz, 3H), 1.90 (m, 2H), 2.23 (br, 5H), 2.93 (br, 2H), 3.13 (m, 3H), 3.25 (s, 2H), 3.41-3.78 (m, 21H), 3.91 (m, 2H), 4.11 (s, 2H), 4.33 (s, 2H), 4.56 (s, 2H), 5.25 (s, 2H), 5.32 (d, J=18.4 Hz, 1H), 5.76 (d, J=16.4 Hz, 1H), 6.74 (s, 2H), 6.98 (s, 2H), 7.04-7.51 (m, 30H), 7.69 (m, 4H), 7.95 (s, 2H), 8.17 (d, J=6 Hz, 2H), 8.30 (d, J=8.8 Hz, 1H). Compound 49: 1 H NMR (300 MHz, CDCl 3 ): δ=1.05 (t, J=7.2 Hz, 3H), 1.25 (m, 3H), 1.41 (t, J=7.5 Hz, 3H), 1.69 (m, 11H), 1.83-2.02 (m, 4H), 2.27 (m, 2H), 2.84 (m, 1H), 3.00 (d, J=5.7 Hz, 2H), 3.14-3.21 (m, 3H), 3.64 (s, 3H), 3.76 (s, 4H), 3.84 (s, 8H), 4.15 (s, 1H), 4.57 (s, 1H), 4.74-4.80 (m, 1H), 5.29 (d, J=4.8 Hz, 2H), 5.32 (d, J=14.7 Hz, 1H), 5.76 (d, J=16.5 Hz, 1H), 6.95 (s, 2H), 7.10-7.14 (m, 4H), 7.18-7.33 (m, 6H), 7.43-7.46 (m, 4H), 7.57-7.62 (m, 4H), 7.67-7.70 (m, 2H), 7.96 (d, J=2.1 Hz, 1H), 8.17 (d, J=8.1 Hz, 2H), 8.29 (d, J=9.0 Hz, 1H), 8.52 (d, J=5.1 Hz, 4H). Mass: (EM+2H + )/2. found 730. Compound 50: 1 H NMR (CDCl 3 , 400 MHz): δ=0.88 (m, 2H), 1.13 (s, 3H), 1.21 (s, 3H), 1.22-1.30 (m, 4H), 1.68 (s, 3H), 1.69-1.91 (m, 6H), 1.91 (s, 3H), 2.05-2.32 (m, 2H), 2.21 (s, 3H), 2.42 (s, 3H), 2.55-2.97 (m, 6H), 2.76 (t, J=6.8 Hz, 2H), 3.14-3.54 (m, 8H), 3.64 (s, 4H), 3.67 (s, 8H), 3.86 (t, J=5.6 Hz, 2H), 3.95 (t, J=6.0 Hz, 2H), 4.10-4.12 (m, 2H), 4.09 (d, J=4.4 Hz, 1H), 4.19 (d, J=4.4 Hz, 1H), 4.29-4.45 (m, 3H), 4.95-4.97 (m, 2H), 5.45 (d, J=4.0 Hz, 1H), 5.67 (d, J=7.2 Hz, 1H), 5.92 (dd, J=8.4, 4.0 Hz, 1H), 6.19 (t, J=9.2 Hz, 1H), 6.29 (s, 1H), 6.43-6.45 (m, 1H), 6.82 (s, 2H), 6.82-7.14 (m, 5H), 7.27-7.63 (m, 26H), 7.80 (d, J=7.2 Hz, 2H), 8.13 (d, J=7.2 Hz, 2H), 8.50 (d, J=4.8 Hz, 4H). Mass: (EM+2H + )/2. found 937. Compound 51: 1 H NMR (300 MHz, CDCl 3 ): δ=1.05 (t, J=7.2 Hz, 3H), 1.25-1.40 (m, 12H), 1.83-1.91 (m, 6H), 3.16-3.23 (m, 2H), 3.47-4.05 (m, 28H), 4.55 (s, 2H), 4.77 (s, 2H), 5.28-5.34 (m, 3H), 5.76 (d, J=16.2 Hz, 1H), 6.86 (s, 2H), 7.01-7.13 (m, 5H), 7.60-7.66 (m, 16H), 7.96 (d, J=2.4 Hz, 1H), 8.08 (d, J=8.7 Hz, 2H), 8.28 (d, J=9.3 Hz, 1H), 8.48 (d, J=4.2 Hz, 4H). Mass: (EM+2H + )/2. found 760.4. Zn-DPA conjugates of each of the compounds described above, denoted as Zn-DPA-(Compound number), were prepared following the procedure described below. More specifically, each of Compounds 1-51 was mixed with 2 molar equivalents of zinc nitrate in a solution containing a solvent mixture of dichloromethane and methanol (1:1) at room temperature and stirred for one hour. Removal of the solvent under vacuum yielded the corresponding Zn-DPA conjugate. The analytical data of several Zn-DPA conjugates are shown below as representative examples: Zn-DPA-(8): 1 H NMR (700 MHz, DMSO-d 6 ): δ=0.86 (t, J=7.0 Hz, 3H), 1.25 (t, J=7.7 Hz, 3H), 1.66 (p, J=7.7 Hz, 2H), 1.79-1.89 (m, 4H), 3.16 (q, J=7.7 Hz, 2H), 3.20 (q, J=7.7 Hz, 2H), 3.75 (d, J=16.1 Hz, 4H), 3.84 (s, 4H), 4.11 (br, 2H), 4.33 (d, J=16.1 Hz, 4H), 5.31 (s, 2H), 5.41 (s, 2H), 6.48 (br, 1H), 6.51 (s, 1H), 6.86 (s, 1H), 6.99 (s, 2H), 7.02 (s, 1H), 7.44 (t, J=7.7 Hz, 1H), 7.54 (d, J=7.7 Hz, 4H), 7.60 (t, J=7.0 Hz, 4H), 7.65 (d, J=7.7 Hz, 1H), 7.71 (d, J=7.7 Hz, 1H), 7.65 (dd, J=9.1, 2.1 Hz, 2H), 8.05 (t, J=7.7 Hz, 4H), 8.14 (s, 1H), 8.21 (d, J=9.1 Hz, 1H), 8.37 (s, 1H), 8.63 (d, J=5.6 Hz, 3H), 8.95 (s, 1H). Mass: (EM+Zn+2H + )/2. found 595, (EM+2Zn+2H + )/2. found 627. Zn-DPA-(11): 1 H NMR (700 MHz, DMSO-d 6 ): δ=0.86 (t, J=7.0 Hz, 3H), 1.25 (t, J=7.7 Hz, 3H), 1.79-1.88 (m, 6H), 3.16 (q, J=7.7 Hz, 2H), 3.48 (s, 2H), 3.73 (d, J=16.1 Hz, 4H), 3.81 (br, 4H), 4.10 (br, 1H), 4.32 (d, J=16.1 Hz, 4H), 4.73 (s, 2H), 5.32 (s, 2H), 5.41 (s, 2H), 6.52 (s, 1H), 6.86 (s, 1H), 6.98 (s, 2H), 7.29-7.31 (m, 1H), 7.37 (d, J=7.7 Hz, 2H), 7.40 (t, J=7.7 Hz, 4H), 7.47 (t, J=7.7 Hz, 2H), 7.52 (d, J=7.7 Hz, 4H), 7.58-7.62 (m, 6H), 7.61 (d, J=7.7 Hz, 2H), 7.76 (t, J=7.7 Hz, 2H), 7.93 (d, J=9.1 Hz, 1H), 8.03 (t, J=7.7 Hz, 4H), 8.20 (d, J=5.6 Hz, 1H), 8.42 (s, 1H), 8.63 (d, J=5.6 Hz, 4H), 8.84 (br, 1H). Mass: (EM+Zn+2H + )/2. found 678, (EM+2Zn+2H + )/2. found 710. Zn-DPA-(17): 1 H NMR (700 MHz, DMSO-d 6 ): δ=0.85 (t, J=7.0 Hz, 3H), 1.25 (t, J=7.7 Hz, 3H), 1.74-1.88 (m, 6H), 3.15 (q, J=7.7 Hz, 3H), 3.53 (s, 1H), 3.69-3.83 (m, 8H), 3.94 (br, 1H), 4.16 (br, 1H), 4.30-4.38 (m, 4H), 4.73 (s, 1H), 4.88 (s, 1H), 5.30 (s, 2H), 5.40 (s, 2H), 6.51 (s, 1H), 6.54-6.88 (m, 2H), 6.93 (s, 1H), 7.02 (s, 1H), 7.30-7.64 (m, 17H), 7.68 (d, J=7.7 Hz, 2H), 7.75 (d, J=9.1 Hz, 1H), 8.05 (t, J=7.7 Hz, 4H), 8.15 (s, 1H), 8.18-8.21 (m, 3H), 8.64 (d, J=5.6 Hz, 4H). Mass: (EM+Zn+2H + )/2. found 670, (EM+2Zn+2H + )/2. found 702. Zn-DPA-(31): 1 H NMR (700 MHz, DMSO-d 6 ): δ=0.85 (t, J=7.0 Hz, 3H), 1.19 (t, J=7.0 Hz, 2H), 1.24 (t, J=7.7 Hz, 1H), 1.82-1.84 (m, 6H), 3.07-3.15 (m, 2H), 3.50 (br, 1H), 3.60 (br, 1H), 3.71 (t, J=17.5 Hz, 4H), 3.81 (s, 4H), 4.12-4.14 (m, 2H), 4.31 (t, J=14.7 Hz, 4H), 4.65 (s, 1H), 4.82 (s, 1H), 5.29 (s, 2H), 5.41 (s, 2H), 6.51 (s, 1H), 6.86 (s, 1H), 6.99 (s, 2H), 7.26-7.72 (m, 20H), 7.72 (d, J=7.7 Hz, 1H), 8.03 (t, J=7.7 Hz, 3H), 8.13 (t, J=7.7 Hz, 1H), 8.63 (d, J=4.9 Hz, 4H). Mass: (EM+Zn+2H + )/2. found 618, (EM+2Zn+2H + /2. found 650. Plasma Stability of Zn-DPA Conjugates Zn-DPA conjugates, Zn-DPA-(8), Zn-DPA-(12), Zn-DPA-(25), Zn-DPA-(26), and Zn-DPA-(42) prepared from the corresponding compounds 8, 12, 25, 26, and 42, respectively, were incubated in mouse plasma at 37° C. for up to 24 hours to assess the stability of these conjugates. A sample was analyzed with a High Performance Liquid Chromatography system to determine the concentration of a test conjugate at one of four time points (i.e., 0, 3 hours, 6 hours, and 24 hours). The percentages of the test conjugate remaining at 3, 6, and 24 hours after incubation in the plasma were determined. The results are shown in Table 1 below. A higher percentage indicates greater stability. Among the five test conjugates, Zn-DPA-(26) and Zn-DPA-(42) prepared from Compounds 26 and 42, respectively, were the most stable. After 24 hours of incubation, it was found that 95% or higher of these conjugates remained in the plasma. TABLE 1 Stability (percentage remaining) of Zn-DPA conjugates, Zn-DPA- (8), Zn-DPA-(12), Zn-DPA-(25), Zn-DPA-(26), and Zn-DPA-(42) Zn conjugates time = 0 time = 3 hr time = 6 hr time = 24 hr Zn-DPA-(8) 100 90 82 — Zn-DPA-(12) 100 84 76 — Zn-DPA-(25) 100 90 85 — Zn-DPA-(26) 100 99 97 95 Zn-DPA-(42) 100 99 98 97 Growth Inhibition of Cancer Cells Cell Culture SCM-1, MiaPaca2 and Colo205 cells were grown in RPMI 1640 (Roswell Park Memorial Institute) medium (RPMI; Gibco), supplemented with 10% fetal bovine serum (FBS; Gibco). Detroit551 cells were grown in Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% FBS 50 U/mL of penicillin and streptomycin, and 1% Nonessential amino acids (NEAA; Gibco). Zn-DPA conjugates, Zn-DPA-(8), Zn-DPA-(12), Zn-DPA-(25), Zn-DPA-(26), and Zn-DPA-(42) prepared from the corresponding compounds 8, 12, 25, 26, and 42, respectively, were used to inhibit the growth of human cancer cells (SCM-1, Colo205, MiaPaca2) and human embryonic skin fibroblast cells Detroit551 following the procedures described below. Cell Viability Assay Cell viability was examined by the MTS assay (Promega, Madison, Wis., USA). More specifically, cells were grown (2500˜3000 cells/well) in a flat bottomed 96-well plate for 24 hours. A medium was added along with a test compound at a pre-determined concentration. The cells were further incubated for 72 hours. At the end of the incubation, the medium was removed and diluted with 100 μl of a 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium/phenazine methosulfate mixture. The cells were again incubated for 1.5 hours at 37° C. in a humidified incubator with 5% CO 2 to allow viable cells to convert the tetrazolium salt into formazan. The conversion was determined by measuring the absorbance at 490 nm using a BioTek PowerWave-X Absorbance Microplate Reader. The data obtained were normalized using a vehicle (dimethyl sulfoxide, DMSO)-treated control (100% viability) and a background control (0% viability) to verify growth inhibition. The IC 50 value is defined as the concentration of a compound that induces a 50% reduction in cell viability in comparison with a vehicle-treated control. These values were calculated using GraphPad Prism version 4 software (San Diego, Calif., USA). The IC 50 values for five Zn-DPA conjugates, i.e., Zn-DPA-(8), Zn-DPA-(12), Zn-DPA-(25), Zn-DPA-(26), and Zn-DPA-(42), were shown in Table 2 below. Also shown in this table are IC 50 values for two anticancer compounds, i.e., SN-38 and CPT-11, for comparison. See below for the structures of these two compounds. Note that Zn-DPA-(8), Zn-DPA-(12), Zn-DPA-(25), Zn-DPA-(26), and Zn-DPA-(42), and CPT-11 are prodrugs of the anti-cancer compound SN-38. Zn-DPA-(26), Zn-DPA-(42), and CPT-11 contained SN-38 at about 24%, 18%, and 58%, respectively. TABLE 2 IC 50 values of Zn-DPA conjugates, Zn-DPA-(8), Zn-DPA-(12), Zn-DPA- (25), Zn-DPA-(26), Zn-DPA-(42), and two anticancer compounds (SN- 38 and CPT-11) against human cancer cells (Colo205, SCM-1, MiaPaca2) and human embryonic skin fibroblast Detroit 551. Conjugates or Compounds Colo205 SCM-1 MiaPaca2 Detroit 551 Zn-DPA-(8) 0.42 0.64 — 9.3 Zn-DPA-(12) 0.12 0.94 — 2.9 Zn-DPA-(25) 0.58 1 — 7.2 Zn-DPA-(26) 1.1 2.6 0.12 >10 Zn-DPA-(42) 3.7 — 0.55 >10 SN-38 0.14 0.64 0.02 4 CPT-11 >10 >10 3.6 >10 *unit in (μM) In Vivo Antitumor Assay Two Zn-DPA conjugates, Zn-DPA-(26) and Zn-DPA-(42) were subjected to an in vivo antitumor assay against Colo205 or MiaPaca2 tumors growing in nude mice following the procedure described below. More specifically, Colo205 or MiaPaca2 cells were cultured and maintained in a flask with a RPMI-1640 medium, which was supplemented with 10% FBS. The cells were harvested and innoculated (1×10 6 cells) subcutaneously into the left flank of a adult male nude mouse. Tumor-bearing mice were grouped at the mean tumor volume of approximately 200 mm 3 . Tumor dimensions were measured with a digital caliper, and the tumor volume in mm 3 was calculated by the formula: Volume=(length×width^ 2 )/2. The mice were housed in sterilized cages equipped with an air filter and sterile bedding materials at the Laboratory Animal Center of National Health Research Institutes. All mice were fed with sterilized water and chow at libitum under 12-hour light/12-hour dark cycle throughout the study. Several dosages of Zn-DPA-(26) and Zn-DPA-(42), were used in this assay, i.e., 40 mg/kg, 20 mg/kg, and 10 mg/kg, p<0.05 vs. vehicle control by one-way ANOVA analysis and the Newman-Keuls multiple comparison test. Both Zn-DPA-(26) and Zn-DPA-(42) in the mixture of 10% DMSO/20% Cremophor EL/70% dextrose were intravenously administered in a regimen of once daily for five consecutive days when dosed at 20 mg/kg or 10 mg/kg, or of twice per week, for two weeks when dosed at 40 mg/kg; CPT-11 (40 mg/kg) was intravenously administered twice a week for two weeks; and SN-38 (10 mg/kg) in the mixture of 10% DMSO/20% Cremophor EL/10% Na 2 CO 3 /60% dextrose was intravenously administered at once daily for five consecutive days for two weeks. Although the amounts of SN-38 contained in Zn-DPA-(26) and Zn-DPA-(42) were only 24% and 18%, respectively (as compared to 58% contained in CPT-11), these two Zn-DPA conjugates were found to unexpectedly show much greater antitumor activities than those of SN-38 and CPT-11 tested in the Colo205 tumor xenograft mouse model. More specifically, it was found that Zn-DPA-(26) unexpectedly showed much higher antitumor activities at dosages of 10 mg/kg and 40 mg/kg, compared to those of SN-38 at 10 mg/kg and CPT-11 at 40 mg/kg; and Zn-DPA-(42), also unexpectedly, showed antitumor activities in a dose-dependent manner and much higher antitumor activities at all three dosages, compared to those of SN-38 at 10 mg/kg and CPT-11 at 40 mg/kg. Moreover, in the MiaPaca2 tumor xenograft mouse model, Zn-DPA-(42) unexpectedly showed antitumor activities in a dose-dependent manner and much higher antitumor activities at dosages of 40 mg/kg, 20 mg/kg, and 10 mg/kg, compared to those of SN-38 at 10 mg/kg and CPT-11 at 40 mg/kg. Other Embodiments All of the features disclosed in this specification may be combined in any combination. Each feature disclosed in this specification may be replaced by an alternative feature serving the same, equivalent, or similar purpose. Thus, unless expressly stated otherwise, each feature disclosed is only an example of a generic series of equivalent or similar features. From the above description, one skilled in the art can easily ascertain the essential characteristics of the present invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions. For example, compounds structurally analogous to the compounds of this invention also can be made, screened for their efficacy in treating a condition that relates to cells containing inside-out phosphatidylserine. Thus, other embodiments are also within the claims.

Dipicolylamine compounds of Formula (I) set forth herein. Also disclosed are pharmaceutical compositions containing metal ions and these compounds. Further disclosed is a method for treating a condition associated with cells containing inside-out phosphatidylserine, with these compounds.

RELATED CASES This is a Continuation application of application Ser. No. 08/527,094, filed Sep. 12, 1995 now U.S. Pat. No. 5,844,717, entitled “Method And System For Producing Micropolarization Panels For Use In Micropolarizing Spatially Multiplexed Images Of 3-D Objects During Stereoscopic Display Processes (As Amended)”; which is a continuation of application Ser. No. 07/536,419, filed Jun. 11, 1990, entitled “METHODS FOR MANUFACTURING POLARIZERS”, now U.S. Pat. No. 5,327,285, issued on Jul. 5, 1994. BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to the field of polarizers and the high throughput mass manufacturing of a new class of polarizars called micropolarizers. Micropolarizers have been developed for use in spatial multiplexing and demultiplexing image elements in a 3-D stereo imaging and display system. 2. Description of Related Art This invention is related to my co-pending application Ser. No. 07/536,190 entitled “A System For Producing 3-D Stereo Images” filed on even date herewith incorporated herein by reference in its entirety, which introduces a fundamentally new optical element called a micropolarizer. The function of the micropolarizer is to spatially multiplex and spatially demultiplex image elements in the 3-D stereo imaging and displaying system of the aforementioned co-pending application. As shown in FIG. 1, the micropolarizer (μPol) 1 , 2 is a regular array of cells 3 each of which comprises a set of microscopic polarizers with polarization states P 1 and P 2 . The array has a period p which is the cell size and is also the pixel size of the imaging or displaying devices. It is possible to turn unpolarized light into linearly polarized light by one of three well known means: 1) Nicol prisms; 2) Brewster Angle (condition of total internal reflection in dielectric materials); and 3) Polaroid film. These are called linear polarizers. The Polaroids are special plastic films which are inexpensive and come in very large sheets. They are made of polyvinyl alcohol (PVA) sheets stretched between 3 to 5 times their original length and treated with iodine/potassium iodide mixture to produce the dichroic effect. This effect is responsible for heavily attenuating (absorbing) the electric field components along the stretching direction while transmitting the perpendicular electric field components. Therefore, if P 1 is along the stretching direction of the PVA sheets, it is not transmitted, where as only P 2 is transmitted, producing polarized light. By simply rotating the PVA sheet 90 degrees, P 1 state will now be transmitted and P 2 will be absorbed. The aforementioned three known means for producing polarized light have always been used in situations where the polarizer elements have large areas, in excess of 1 cm 2 . However, for 3-D imaging with μPols using 35 mm film, to preserve the high resolution, the μPol array period p may be as small as 10 micron. Therefore, there is no prior art anticipating the use of or teaching how to mass produce μPols having such small dimensions. SUMMARY OF THE INVENTION The present invention provides a means for high through put mass manufacturing of micropolarizer arrays. To use the μPols in consumer 3-D photography, and printing applications, the economics dictate that the cost of μPols be in the range of 1 to 5 cents per square inch. For this reason, the low cost PVA is the basis for the manufacturing process. The present invention also provides a flexible μPols manufacturing process which can be adapted to low and high resolution situations as well as alternative manufacturing methods, each of which may be advantageous in certain applications and adaptable to processing different polarizer materials. The present invention further provides an electronically controllable μPol. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an illustration of a micropolarizer array according to the present invention. FIGS. 2 and 3 illustrate fabrication processes of linear micropolarizers using, respectively, bleaching and selective application of iodine. FIG. 4 shows final alignment and lamination processes for making linear micropolarizers. FIG. 5 illustrates a process for fabricating linear micropolarizers by means of etching. FIG. 6 illustrates a method for patterning micropolarizer by mechanical means. FIG. 7 shows final alignment and lamination processes for making linear micropolarizers by the etching method. FIG. 8 shows final alignment and lam ion processes for making circular micropolarizers by the etching method. FIGS. 9 and 10 illustrate processes for making linear and circular polarizers eliminating an alignment step. FIGS. 11 and 12 illustrate photo-lithographic patterning steps. FIG. 13 illustrates an automated high through-put process for continuous production of micropolarizer sheets by photo-lithographic means. FIG. 14 illustrates an automated high through-put process for continuous production of micropolarizer sheets by direct application of bleaching ink or iodine-based ink. FIG. 15 illustrates an active electronically controllable micropolarizer based on electro-optical effect of liquid crystals. DETAILED DESCRIPTION Since its invention by E. Land in the 1930's, polyvinyl alcohol (PVA) has been the polarizer material of choice. It is available from several manufacturers including the Polaroid Corporation. It comes as rolls 19 inches wide and thousands of feet long. The PVA, which is 10 to 20 micron thick, is stretched 2 to 5 times original length and treated with iodine to give it its dichroic (polarizing) property. The PVA treated in this manner crystallizes and becomes brittle. The processes below employ certain chemical properties of the PVA. These are: i) resistance to organic solvents and oils; ii) water solubility, 30% water and 70% ethyl alcohol; iii) bleaching of the dichroic effect in hot humid atmosphere and by means of caustic solutions; iv) manifestation of dichroic effect by painting the PVA in iodine/potassium iodide solution; and v) the stabilization of the dichroic effect in boric acid solution. The starting PVA material comes laminated to a clear plastic substrate which protects the brittle PVA and facilitates handling and processing. The substrate is made either of cellulose aceto bytyrate (CAB) or cellulose triacetate (CTA), and is typically 50 to 125 micron thick. CAB and CTA are ultra-clear plastics and at the same time they are good barriers against humidity. For some applications, large glass plates are also used as substrates. Although other polymers, when stretched and treated by dichroic dyes, exhibit similar optical activity to that of PVA and may be fabricated into micropolarizers following the methods taught here, only PVA is considered in the manufacturing processes described in the present invention. The physical principles on which the polarization of light and other electromagnetic waves, and the optical activity which produces phase retardation (quarter wave and half wave retarders) are described in books on optics, such as: M. Born and E. Wolf, Principles of Optics, Pergamon Press, London, fourth edition, 1970; F. S. Crawford, Jr., Waves, McGraw-Hill, New York, 1968; and M. V. Klein, Optics, Wiley, N. Y., 1970. There are several important facts used in this invention: 1. Two linear polarizers with their optical axis 90 degrees from each other extinguish light. 2. A linear polarization which is 45 degrees from the optical axis of a quarter wave retarder is converted into a circular polarization. 3. A linear polarization which is 45 degrees from the optical axis of a half wave retarder is converted into a linear polarization rotated 90 degrees. 4. Two linear polarization states, P 1 and P 2 , 90 degrees from each other, are converted into clockwise and counter-clockwise circular polarization states by means of a quarter waver retarder. 5. A circular polarization is converted into a linear polarization by means of a linear polarizer. 6. A clockwise circular polarization is converted into a counter-clockwise polarization by means of a half-wave retarder. The process for producing the micropolarizers, μPols, 1 , 2 in FIG. 1 is described in FIG. 2 which starts with a sheet of linear polarizer 5 laminated onto a clear substrate 4 . The laminate is coated with photosensitive material 6 called photoresist. This can be one of several well known liquid photoresists marketed by Eastman Kodak and Shipley, or in the form of a dry photoresist sheet called Riston from the Du Pont Company. The latter is preferred because complete laminated rolls of the three materials 3 , 5 , 6 can be produced and used to start the μPols process. The photoresist is subsequently exposed and developed using a mask having the desired pattern of the μPols cell 3 producing a pattern with polarization parts protected with the photoresist 6 and unprotected parts 7 exposed for further treatment. These exposed parts 7 are treated for several seconds with a caustic solution e.g., a solution of potassium hydroxide. This bleaching solution removes the dichroic effect from the PVA so that the exposed parts 8 are no longer able to polarize light. The photoresist is removed by known strippers, which have no bleaching effect, thus the first part 9 of the μPols fabrication is produced. Alternatively, FIG. 3 shows a method for making linear μPols by starting with a laminate of PVA 10 which is stretched but does not yet have the dichroic effect, i.e., it has not yet been treated with iodine, and the substrate 4 . Following identical steps as above, windows 7 are opened in the photoresist revealing part of the PVA. The next step is to treat the exposed parts with a solution of iodine/potassium iodide and subsequently with a boric acid stabilizing solution. The exposed parts 11 of the PVA become polarizers while those protected with the photoresist remain unpolarizers. Stripping the photoresist completes the first part of the process. As illustrated in FIG. 4, a complete μPol is made using two parts 13 , 14 produced by either the process of FIG. 2 or FIG. 3 except that part 13 has polarization axis oriented 90 degrees from that of part 14 . The two parts are aligned 15 so that the patterned polarizer areas do not over lap, and then laminated together to from the final product 16 . The μPol 16 is laminated with the PVA surfaces facing and in contact with each other. The μPol 17 is laminated with the PVA of part 13 is in contact with the substrate of part 14 . The μPol 18 is laminated with the substrates of both parts are in contact with each other. Finally, it is possible to produce the μPol 19 with only one substrate onto which two PVA films are laminated and patterned according to the process described above. The above process leaves the patterned PVA film in place and achieves the desired result by either bleaching it or treating it with iodine solution. The processes described in FIGS. 5 and 6 achieve the desired result by the complete removal of parts of the PVA. In FIG. 5, the starting material is any PVA film 20 (linear polarizer, quarter wave retarder, or half wave retarder) or any non-PVA optically active material laminated to a substrate. As described above, windows 7 in the photoresist are opened. The exposed PVA 7 is removed 21 by means of chemical etching (30% water/70% ethyl alcohol solution), photochemical etching, eximer laser etching or reactive ion etching. Stripping the photoresist, the first part 22 of the μPols process is completed. The removal of PVA can also be accomplished by mechanical cutting or milling means. FIG. 6 illustrates the process which uses a diamond cutter 66 mounted on a motor driven shaft 74 . In one embodiment, the PVA 68 is sandwiched between two polymers, such as poly-methyl methacrylate, PMMA, film 67 , and the sandwich is laminated onto a substrate 69 . The diamond saw is used to cut channels. The channel width and the distance between the channels are identical. The PMMA serves to protect the top PVA surface from abrasion and protects the substrate from being cut by the saw. Next the PMMA on top of the PVA and in the channel is dissolved away, leaving the part 71 with clean substrate surface 70 . This part can be used as is to complete the μPol fabrication or the original substrate 69 is removed by dissolving away the rest of the PMMA, after having attached a second substrate 72 . This part which consists of the patterned PVA 68 laminated to the substrate 72 is used in a subsequent step to complete the μPol. Even though this process is mechanical in nature, it has been shown in Electronic Business, May 14, 1990, page 125, that channels and spacings as small as 5 micron can be made using diamond discs manufactured by Disco HI-TEC America Inc., of Santa Clara, Calif. Realizing that using only one disc makes the process slow and costly, the arrangement in FIG. 6 is used where many discs 73 in parallel 75 is preferred. Each disc has its center punched out in the shape of a hexagonal so that it can be mounted on a shaft 74 with a hexagonal cross section. Hundreds of such discs are mounted on the same shaft and are spaced apart by means of spacers 76 whose diameters are smaller than those of the discs. The diameter difference is used to control the cutting depth. The spacers also have hexagonal centers. The cutting discs and the spacers have the same thickness in order to obtain identical channel width and channel spacing. The discs and spacers are mounted on the shaft tightly to prevent lateral motion, while the hexagonal shaft prevents slipping. The discs are made to rotate between 20,000 and 50,000 RPM and the laminate is cut in continuous fashion, thus achieving high through put. To complete making a whole μPol the parts 22 , 71 , 72 prepared by the PVA removal methods are used as in FIG. 7 . If the PVA is a linear polarizer, then, parts 23 , 24 have patterned polarizers which are oriented 90 degrees from each other, and when aligned 25 , and laminated together, complete linear μPols 26 , 27 , 28 , 29 result. If the PVA is quarter wave retarder, then the parts 30 , 31 of FIG. 8 have patterned retarders with optical axes oriented 90 degrees from each other, and when aligned 32 and laminated to a sheet of linear polarizer 33 , complete circular μPols 34 , 35 , 36 result. Up until now all μPols have been made using two patterned parts aligned to each other and then laminated as in FIGS. 4, 7 , and 8 . It possible make μPols with a single patterned part 38 or 40 in FIGS. 9 and 10, and without the alignment step. In FIG. 9, the single patterned part 38 consists of a patterned half-wave retarder on a substrate 4 . It is mounted simply on a sheet of polarizer 39 with no alignment necessary and a complete μPols results. If a linear polarizer sheet 39 is used, the result is a linear μPols. If a circular polarizer sheet 39 is used, the result is a circular μPols. In FIG. 10 the single patterned part 40 has a linear polarizer which is simply mounted on a circular polarizer sheet 41 to produce a complete μPols. FIG. 11 shows the apparatus 42 used for contact printing of the laminate 46 made of photoresist, PVA, and its substrate. The apparatus consists of a vacuum box 47 , and a vacuum pump 48 attached thereto. The top of box is flat surface with vacuum holes which hold the laminate flat during exposure. The mask 45 with its emulsion facing down, makes direct contact with the photoresist surface with the aid of the top glass cover 44 . The very high intensity UV lamp 43 is then turned on for 30 to 60 seconds to expose the photoresist. The laminate is subsequently removed for development and the rest of the μPols fabrications processes as described in FIGS. 2, 3 , and 5 . This printing process using apparatus 46 is automated for large area μPols production as shown in FIG. 12 . The laminate 46 is furnished in a large roll, is fed to apparatus 42 when the vacuum pump 48 is off and the mask and cover 44 are open. By means of an electronic controller, the following automatic sequences are carried out: (1) the vacuum is turned on; (2) the cover and mask are lowered; (3) the lamp is turned on for certain period of time; (4) the lamp is turned off; (5) the mask and cover are, lifted; (6) the vacuum is turned off; and (7) the laminate is advanced. These steps are repeated until the whole roll is finished. The exposed roll 49 is then processed further. This exposure apparatus is simple and has no critical alignment requirements. The fully automated embodiment in FIG. 13 is used for continuous mass production. The raw roll of laminate 46 enters from the right and the finished roll 56 of μPols exists from the left. As one laminate segment is exposed, it is advanced to the left, developed and rinsed in station 50 . Said segment is then further advanced to the left to be dried in station 51 , and advanced further to section 52 . This station carries out the most critical μPols process by one of three methods discussed above in connection with FIGS. 2, 3 , and 5 . These are: 1. Bleaching by means of potassium hydroxide then rinsing. 2. Polarizing by means of iodine/potassium iodide solution, boric acid stabilizing solution, then water/methyl alcohol rinse. 3. Dry or wet etching of the PVA. After the rinsing step in station 52 , the segment is advanced to station 53 for drying and heat treatment. The photoresist stripping and rinsing is done in 54 and the final drying step in 55 . The finished roll 56 is laminated with a polarizer sheet according to FIGS. 9 and 10 complete the μPols. The photolithographic printing used above involves several steps: 1. Application of the photoresist 2. Baking 3. Making contact with the mask 4. Exposure 5. Development 6. Rinsing 7. Drying 8. Post baking 9. Stripping 10. Rinsing 11. Drying These steps have been eliminated by using the mechanical method described in FIG. 6 . They are also completely eliminated by using the embodiment illustrated in FIG. 14 . This apparatus 57 promises to be the least expensive high volume manufacturing process for μPols. It consists of a plate drum 58 to which a plate a fixed, a blanket drum 59 which has a rubber surface, and an impression drum 60 . The inks from ink fountains 62 , 65 , are transferred to the plate by means of rollers 63 , 64 . The pattern is transferred from the plate to the blanket drum which in turn it transfers to the PVA laminate 61 . The rotation of the blanket drum and the impression drums draws in the laminate, and blanket rubber surface pressing on the laminate causes proper printing. Although the hardware is similar to that used in offset printing press, the process is different from offset printing. The principal difference is in the ink formulation. In offset printing slightly acidic water is used in fountain 65 , and an oil-based paint (linseed oil, pigments, binder, and other additives) is used in fountain 62 . These are not intended to interact w the paper. The pigments in the oil based solution will remain bonded to the paper, and the water evaporates. In the μPols printing process, on the other hand, the oil based solution is clear and is not intended to remain, while the water based solution is intended to interact with the PVA and permanently modify it, by bleaching it or by endowing it with the dichroic property. Another difference is the use of the negative image on the plate to print a positive image of the pattern on the PVA laminate, whereas in the offset printing, the opposite occurs. The plates are made by means which are well known in the offset printing industry. The μPols process using apparatus 57 has three embodiments which depend on the content of the water based solutions in fountain 65 , while fountain 62 contains a fast drying clear oil solution: 1. Selective Bleaching: The water based solution contains a bleaching agent such as potassium hydroxide or sodium hydroxide which applied selectively as pattern on the polarized PVA. Where applied, the solution removes the iodine and its polarizing effect. Rinsing and drying steps follow this bleaching step. 2. Selective Dichroism: The water based solution contains a iodine/potassium iodide which is applied selectively as a pattern on the unpolarized PVA. Where applied, the solution turns the PVA into a polarizer. This step is followed by a stabilizing step using a boric acid solution and subsequently rinsing using a methyl alcohol solution and drying steps. 3. Selective Etching: The water based solution contains a clear polymer which is applied selectively as a pattern on the polarized or unpolarized PVA. Where applied, the solution leaves a protective polymer layer. This step is followed by an etching step to remove the unprotected PVA, by rinsing and drying steps. Electrically Controllable Micropolarizers There are applications in which a variable μPols are needed, and in particular, μPols which are electronically alterable. This can be accomplished by using electro-optical materials such as liquid crystals or organic nonlinear optical polymers, see C. C. Teng and H. T. Man, Applied Physics Letters, 30, 1734 (1990), or magneto-optical materials which have large Faraday rotation. All these materials rotate the polarization of incident radiations by applying voltages or magnetic fields. The preferred embodiment 77 in FIG. 15 uses a twisted nematic liquid crystal 78 which rotates the polarization 90 degrees by applying a voltage alternating at 10 to 20 KHz and having an RMS value of about 10 volts. This voltage is applied between the checker-board patterned transparent electrode made of indium-tin oxide ITO 82 on a glass substrate 80 and an unpatterned ground ITO layer 81 deposited on a second glass substrate 79 . The patterned ITO 82 are connected to a common voltage bus 85 . Each connection 86 is made of aluminum film whose area is a small percentage of the ITO area, in the order of 10%. Thus we created two types of cells: One type which has liquid crystal and ITO 81 , 82 on both sides, will be affected by the applied electric field; and the other type which has liquid crystal but has ITO 81 on one side only and hence will not be affected by the applied electric field. The polarizer sheet 83 with polarization state P 1 is laminated to the glass substrate 80 completes the electronic μPols. The operating principles of electronically switchable μPols is as follows: When the voltage 84 is zero, the polarization P 1 of the incident light will not change. When a voltage is applied, the cells with ITO on both sides will rotate the polarization to a state P 2 , while the cells with ITO on one side only leave the polarization P 1 unchanged. The end result is a regular periodic array of cells with two polarization states P 1 and P 2 . This is a μPol that can be turned off and on.

A method of mass producing a micropolarizer including the steps exposing films of predetermined polarization states to electromagnetic radiation through masks of predetermined patterns, etching away exposed parts of each film and aligning and laminating the films to one another to provide a micropolarizer comprising alternating sets of microscopic polarizers with different polarization states.

REFERENCE TO RELATED APPLICATION This application is a continuation of U.S. patent application Ser. No. 10/462,044, filed Jun. 16, 2003, now U.S. Pat. No. 7,425,968, the entire file wrapper contents of which are hereby incorporated by reference as though fully set out at length. COPYRIGHT NOTICE AND PERMISSION This document contains some material which is subject to copyright protection. The copyright owner has no objection to the reproduction with proper attribution of authorship and ownership and without alteration by anyone of this material as it appears in the files or records of the United States Patent and Trademark Office, but otherwise reserves all rights whatsoever. FIELD OF THE INVENTION The present invention relates to a computer-implemented method and apparatus for automatically labeling maps or graph layouts in accordance with predefined label criteria. BACKGROUND OF THE INVENTION Maps include geographic drawings showing countries, cities, rivers, bodies of water, mountains, and other features of interest. Labeling cartographic features is a fundamental part of map-making. Placing each label optimally with respect to its corresponding feature invariably produces labels overlapping each other or too close to each other. As this results in confusion and unacceptable maps, methods to reposition labels or not draw them at all must be used to create a map that conveys as much information as possible. Tagging graphical objects with text labels is a fundamental task in the design of many types of informational graphics. This problem is seen in its most essential form in cartography, but it also arises frequently in the production of other informational graphics such as scatter plots. The quality of a labeling is determined essentially by the degree to which labels obscure other labels or features of the underlying graphic. The goal is to choose positions for the labels that do not give rise to label overlaps and that minimize obscuration of features. Construction of a good labeling is thus a combinatorial optimization problem, which has been shown to be NP-hard (Marks and Shieber, 1991). As a hypothetical baseline algorithm, randomly choosing positions for each label generates a poor labeling, both aesthetically, and as quantified using a metric that counts the number of conflicted labels, i.e., those that obscure point features or other labels. In addition to geographical and technical maps, there are many labeling applications relating to graph layouts and drawings. These applications include, but are not limited to, areas such as database design (e.g. entity relationship diagrams), software engineering including CASE, software debugging, complex web pages, CAD drafting, complex electrical diagrams, and telecommunications and communications networking. In fact, the labeling of the graphical features of any drawing is generally necessary because it conveys information essential to understanding the drawing. For complex and information rich drawings, computer aided labeling is increasingly employed. As used in the present specification, the term “map” is used to include both geographical and technical maps as well as graph layouts and drawings. The term “label” is used to refer to text or other indicia to be placed on a map. A system and method for labeling objects on maps while avoiding collisions with other labels has been sought after. Some apparently powerful algorithms for automatic label placement on maps use heuristics that capture considerable cartographic expertise but are hampered by provably inefficient methods of search and optimization. This patent discloses a system and method for label placement that achieves the twin goals of practical efficiency and high labeling quality by employing cartographic heuristics. SUMMARY OF THE INVENTION The present invention provides a computer-implemented system and method of automatically labeling a map in accordance with predefined label location, placement, and priority criteria. Here, each label is represented as a convex polygon with any orientation on the map. Labels have various parameters associated with them such as location, size, shape, number and location of vertices, target feature, priority, movement constraints, and clearance. After finding the best position of a label for every feature without regard to other labels or features, higher priority label positions are compared to lower priority label positions two at a time. If the labels interfere, the lower priority label is moved within its movement constraint. Several candidate locations for the lower priority label position are found by moving it the shortest distance to avoid the higher priority label position. A new location is acceptable if the location does not collide with a label of higher priority. It can collide with a label of lower priority. If no candidate positions are acceptable, the label is not moved. This process continues until all labels are inspected, after which a deviation from the desired result function is calculated. This function is zero if the label interference for all labels is zero and greater than zero otherwise. The whole process is repeated until the evaluation function equals zero or the change in the evaluation function is less than a given percent (e.g., two percent) for a small number (e.g., four) of iterations or if it oscillates for a number (e.g., six) of iterations or if the number of iterations is greater than a set number (e.g., twenty). If any interference remains, then interfering labels with lower priorities are not drawn. The details of the present invention, both as to its structure and operation, can best be understood in reference to the accompanying drawings, in which like reference to the accompanying drawings, in which like reference numerals refer to like parts, and in which: BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram of a computer hardware architecture compatible with the present system and method. FIG. 2 is a schematic diagram showing an exemplary computer program product. FIG. 3 is a flow chart showing the overall logic of the present system and method. FIGS. 4 a , 4 b , and 4 c is a flow chart showing the initialization of the anti-collision system and method. FIG. 5 is a flow chart of the sorting labels by priority. FIG. 6 is a flow chart showing the initialization of halting criteria variables. FIGS. 7 a and 7 b is a flow chart showing the test of whether each label has been tested. FIG. 8 is a flow chart showing the overlap test FIGS. 9 a , 9 b , and 9 c is a flow chart showing the movement procedure. FIG. 10 is a flow chart showing the initiation of collision scores and priority ranges. FIG. 11 is a flow chart showing the calculation of the evaluation function. FIG. 12 is a flow chart showing the halt routine. FIG. 13 is a flow chart showing the routine to adjust label properties. FIG. 14 is a flow chart showing the return to caller. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring initially to FIG. 1 , a system is shown which includes a digital processing apparatus. This system is a general-purpose computer 1000 . The computer may include a graphics display, print hardware, and print software, or may be as simple as a generic personal computer. The example computer in FIG. 1 includes central processor 1010 , system memory 1015 , disk storage 1020 (e.g., hard drive, floppy drive, CD-ROM drive, and DVD drive), controller 1005 , network adapter 1050 , video adapter 1030 , and monitor 1055 . Data input may be through one or more of the following agencies: keyboard 1035 , pointing device 1040 , disk storage 1020 , local area network 1060 , point to point communications 1065 , and wide area network 1070 (e.g., internet). One or more features of the computer as shown may be omitted while still permitting the practice of the invention. For example, printer 1045 is not necessary for maps intended to be displayed only on monitor 1055 . Likewise, network adapter 1050 , local area network 1060 , point to point communications 1065 , and wide area network 1070 are not necessary when the primary method of data input is via removable disk storage. The flow charts herein illustrate the structure of the logic of the present invention as embodied in computer program software. Those skilled in the art will appreciate that the flow charts illustrate the structures of logic elements, such as computer program code elements or electronic logic circuits, that function according to this invention. Manifestly, the invention is practiced in its essential embodiment by a machine component that renders the logic elements in a form that instructs a digital processing apparatus (that is, a computer) to perform a sequence of function steps corresponding to those shown. FIG. 2 shows a computer program product which includes a disk 1080 having a computer usable medium 1085 thereon for storing program modules a, b, c, and d. While 4 modules are shown in FIG. 2 , it is to be understood that the number of modules into which the program is divided is arbitrary and may be in any particular embodiment a different number. Modules a, b, c, d may be a computer program that is executed by processor 1010 within the computer 1000 as a series of computer-executable instructions. In addition to the above-mentioned disk storage 1020 , these instructions may reside, for example in RAM or ROM of the computer 1000 or the instructions may be stored on a DASD array, magnetic tape, electronic read-only memory, or other appropriate data storage device. In an illustrative embodiment of the invention, the computer-executable instructions may be lines of compiled C++ code. FIG. 3 is an overview and summary of the label anti-collision procedure for maps. The caller of the procedure performs the first stage, routine 5 , and the second stage, routine 8 . Routine 5 involves locating each label on a map in the optimal position with respect to its target feature without regard to other labels or features. Routine 8 assigns properties to the map and the labels. To begin, the user must specify how to initially place labels on a map. That is, commencing at routine 5 , it is assumed that the user will assign positions that give the best label location with respect to its associated feature. For this procedure to work, the user places the labels in the best spots according to their criteria regardless of other labels and map features. For example, in the initial positions, labels may overlap each other and/or extend over the map boundary. Labels are assumed to be convex polygons while the map boundary is assumed to be a rectangle. Next, at routine 8 , the user must assign properties to the map and the labels. Map properties include its height and width. A label's properties include the associated map feature(s), initial location, size, shape, angular orientation, priority, movement constraints, and clearance. In addition, each label has an associated property that indicates the fraction of the label area that can extend outside the map boundary before it is not drawn. The procedure takes all of these properties into account to move labels to acceptable positions or to not draw the label. The following discussion concerns only those geometric objects in the plane of the map, of which the labels are a part. All labels are restricted to convex planar polygons in this plane. A planar polygon is convex if it contains all the line segments connecting any pair of its points. If two convex planar polygons overlap, this means that: 1) at least one vertex of one polygon is inside the other polygon, or 2) at least one edge of one polygon crosses or touches (i.e., intersects) an edge of the other polygon. To begin the anti-collision procedure, three initialization steps occur. First, labels lying partially inside the map boundary must either be moved completely inside the portrait or be excluded from being compared to other labels and excluded from being drawn. Each label has movement types and constraints that determine whether or not the label qualifies for movement completely onto the map. These movement types and constraints are explained below. Labels qualifying for movement to the inside of the map are moved regardless of the collision status with any other label. Second, the labels must be ordered in a list with respect to priority from highest priority to lowest priority. In general, many labels will have the same priority. Within any group of labels with the same priority, any particular label is randomly placed within that block. Third and last, variables that monitor the state of the procedure must be initialized. The purpose of routine 10 is to move labels within the map boundary. If too much of a label is outside the boundary, it will not be included in the map. Each label is tested to determine what fraction of its area is within the map boundary. At routine 20 , labels are sorted in order of descending priority. Halting criteria parameters are initialized at routine 30 . Every combination of two labels is tested for overlap in routine 40 . When comparing labels to determine if they overlap, it is important to choose the order of comparison properly to avoid excessive calculation and moving labels more times than necessary. The highest priority labels should be tested for overlap before labels of lower priority. The overlap test at routine 45 has three parts. First, it must be determined if any vertex of a first label is inside the second label. Second, it must be determined if any vertex of a second label is inside the first label. Third, it must determine if any edge of the first label intersects any edge of the second label. If at any point either label is determined to overlap the other label, then any remaining parts are bypassed. Labels are moved about the map at routine 50 to clear existing label collisions. After it is determined that two labels overlap, the routine finds several new locations for the lower priority of the two labels that eradicate the existing overlap. These locations are ranked by how far the label must be moved, shortest to longest. Then if appropriate, the lower priority is moved to a new location, and its location parameters are adjusted. The evaluation function, routine 60 , quantifies the extent of label collisions. Routines 40 , 45 , 50 , and 60 iterate until halt routine criteria 70 are satisfied. Labels may move several times before the iterations stop. After the iterations stop, all labels are examined for any overlap and label properties are adjusted at routine 80 . Finally, control is returned at routine 90 to the user to draw or view the map. FIGS. 4 a , 4 b , and 4 c display the logic of routine 10 in detail. The purpose of routine 10 is to make sure all of a label is within the map boundary. If too much of a label is outside the boundary, it will not be included in the map. Each label is tested to determine what fraction of its area is within the map boundary. A particular label is divided into a grid; 32 by 32 cells is a typical division that works well in practice. If the centroid of a cell is within the map boundary, the entire cell contributes to the fraction of the label within the boundary. The areas of each cell within the map are added to together. If this sum of cell areas, divided by the total label area, is greater than a predetermined value, then the label is moved entirely onto the map according to the movement procedure and the movement constraints described below. The only change to the procedure is that there is no test for overlap with other labels. The qualifying labels are moved onto the map at this time and tested later. Step 100 obtains a list of labels from data storage. Each label is tested for whether the entire label is inside the map boundary. First, step 108 initializes flags that will be used in routine 10 . Step 112 tests whether vertices of each label are outside the map boundary. If the vertices of a label are all inside the map boundary, then the next label is tested. If any vertices of a label are outside the map boundary, then, at step 116 , a circumscribing rectangle is placed around the label. Then the circumscribing rectangle is divided into a plurality of cells at step 120 . For example, the rectangle may be divided into 64 cells by 64 cells forming a total of 4096 cells. Each cell is tested, step 124 . The test includes finding the center point of each cell to find the number of cells inside the label, step 128 . Then, at step 132 , the center point of each cell used to find the number of cells both inside the label and inside the map. The fraction of the label inside the map boundary is determined at step 136 . The high and the low values of the x and y coordinates for the vertices of the label are found in step 140 . Then the label is tested, step 144 , to determine if the fraction of the label inside the map boundary is high enough to qualify for attempted movement inside the map. There is one of two possible ways the label might move depending on its movement constraints which is determined in step 148 . One movement, in both the x-axis and y-axis direction, is performed in steps 152 , 156 , 160 , 164 , and 168 . In step 152 , the x-axis and y-axis movement of the label in the plane of the map (2D type movement) is initialized to (0,0). In step 156 , the minimum 2D type movement to move the entire label within the map is determined (see the following pseudo-code for Routine 10 which shows how to determine the minimum 2D type movement). In step 160 , the maximum allowed 2D movement parameter for the label from its original position is compared to the minimum 2D type movement. In step 164 , it is determined if the label fits within the map boundary after the label has been moved by the minimum 2D movement. This is really a test to see if the label is too big to fit in the map. In step 168 , if the label can fit in the map, a label flag and a label parameter are set. The other movement, restricted to a vector, is performed in steps 172 , 176 , 180 , 184 , and 188 . In step 172 , the vector type label movement candidates(s) to move the label within the map is determined (see the following pseudo-code for Routine 10 which shows how to determine the minimum vector movement). In step 176 , a loop cycles through candidate(s) for the label which are determined in step 172 . In step 180 , if the maximum allowed vector movement parameter for the label from its original position is less than the magnitude of the current candidate for the label, go to step 176 . Otherwise, go to step 184 . In step 184 , if the label does not fit within the map boundary after the label has been moved by the current candidate, go to step 176 . This is really a test to see if the label is too big to fit in the map. Otherwise, go to step 188 . In step 188 , if the label can fit in the map, a label flag and a label parameter are set. If the label is partially or totally outside the map, and cannot be properly moved within the map, which is checked in step 192 , then a parameter for that label is set in step 196 . Once all labels have been tested, step 104 exits routine 10 and proceeds to routine 20 . Referring to FIG. 5 , labels are sorted by priority at step 200 from the highest priority label to the lowest priority label and placed into a data structure map. Step 210 exits routine 20 and proceeds to routine 30 , an initialization of halting criteria variables. In FIG. 6 , step 300 initializes halting criteria variables. Step 310 exits routine 30 and proceeds to routine 40 , a test of every combination of two labels for overlap. The above-described logic is further shown in the following pseudo-code with comments: PULL IN THE LABELS FROM THE EDGES OF THE MAP ROUTINE //Pseudo-code for the Initialization of the Anti-collision Procedure for Maps //List of pseudo-code variables previous_collision_score - the collision score from the previous iteration previous_previous_collision_score - the collision score from two iterations ago iteration_count - number of times the anti-collision procedure has looped slow_change_count - number of iterations of continuous slow change of collision score oscillation_count - number of iterations of continuous oscillation of collision score priority_of_most_important_label - numerical priority value of the most important label priority_range - the difference between the priority of the least and the most important labels. This number is non-negative. frac_inside - fraction of label inside the map boundaries map_x_size - the number of x units in the map - map boundary is a rectangle map_y_size - the number of y units in the map - map boundary is a rectangle (xMove2D, yMove2D) - the label movement if the label qualifies for movement completely inside the map boundary and the label parameters specify 2D type movement (xMoveVec[ ], yMoveVec[ ]) - an array of label movements if the label qualifies for movement completely inside the map boundary and the label parameters specify vector type movement (xc, yc) - center point of a cell formed from a grid within the circumscribing rectangle around the label (x_IP, y_IP) - a point satisfying various conditions used to properly move a label completely inside the map boundary LABEL_TOO_MUCH_OUTSIDE_PORTRAIT - indicates if the procedure has determined that the label has much area outside the map boundary or can not be properly moved to a new position completely inside the map boundary. This is a flag of every label set by the procedure. LABEL_OUTSIDE_PORTRAIT - Not used. This is a flag of every label set by the procedure. LABEL_MOVED_INTO_PORTRAIT - indicates if the procedure has moved a label that was originally partially outside the map boundary to a new position completely inside the map boundary. This is a flag of every label set by the procedure. LABEL_MIN_FRACTION_INSIDE - minimum fraction of the label that must be inside the map boundary to attempt relocation completely inside the map boundary. This is a parameter of every label set by caller. LABEL_NEW_LOCATION - A vector (x, y) which is added to all vertices of a label if the procedure moves the label. This vector has an initial value of (0, 0). This is a parameter of every label determined by the procedure. // pseudo-code also has: // a list of possible label movement candidates to pull the label inside the map boundary // a data structure map of labels and their properties sorted by priority from the most // important label to the least important label ------------------------------------------------------------ // THIS IS THE START OF ROUTINE 10 // The labels are not in any particular order at this point. // They are only in the order in which they are received from the caller. for i = first unordered label to last unordered label  set label i flag LABEL_OUTSIDE_PORTRAIT = FALSE  set label i flag LABEL_TOO_MUCH_OUTSIDE_PORTRAIT = FALSE  set label i flag LABEL_MOVED_INTO_PORTRAIT = FALSE  set label i parameter LABEL_NEW_LOCATION = (0, 0)  // Determine if the label is inside or outside the map boundary.  // If all vertices are inside, then the entire label is inside.  // Here, a vertex on the map boundary is inside the boundary.  label_inside_map = TRUE  for j = first vertex of label i to last vertex of label i  if ( vertex j outside map boundary ) {   label_inside_map = FALSE  }  next j  if ( label_inside_map = FALSE ) {  // Below, find the approximate fraction of the label inside the map boundary.  // The circumscribing rectangle has edges parallel to the map edges.  // Note that both the rectangle and the label are convex polygons.  Put a circumscribing rectangle around label i  Divide the circumscribing rectangle into 64 units by 64 units forming 4096 cells  in_label = 0  in_label_and_map = 0  for k = first cell to last cell   Find center point of cell k called (xc, yc)   // Here, a point on a label edge or map boundary is inside the label or map.   // Use the “point inside convex polygon” procedure described in the   // labels overlap section.   if( (xc, yc) inside label ) {   in_label = in_label + 1   if( (xc, yc) inside map boundary ) {    in_label_and_map = in_label_and_map + 1   }   }  next k  frac_inside = ( in_label_and_map )/( in_label )  // Move the label inside the map boundary if enough of the label is inside.  // Some of the vertices below may be the same vertex.  (x_low, yL) = coordinates of vertex with lowest x coordinate  (x_high, yH) = coordinates of vertex with highest x coordinate  (xL, y_low) = coordinates of vertex with lowest y coordinate  (xH, y_high) = coordinates of vertex with highest y coordinate  // find the new location for the label  if ( frac_inside > LABEL_MIN_FRACTION_INSIDE parameter of label i ) {   if ( 2D type movement for label i ) {   (xMove2D, yMove2D) = (0, 0)   // If both conditions are true, the label will not fit into the map.   if ( x_low < 0 ) {    xMove2D = 0 − x_low   }   else if ( x_high > map_x_size − 1 ) {    xMove2D = map_x_size − 1 − x_high   }   // If both conditions are true, the label will not fit into the map.   if ( y_low < 0 ) {    yMove2D = 0 − y_low   }   else if ( y_high > map_y_size − 1 ) {    yMove2D = map_y_size − 1 − y_high   }   // Determine if the label is still within its movement parameters.   // This means has the label moved too far from its original position.   // The original location parameter is never changed. It does not change   // because it is always used for comparison to the new position.   if ( (xMove2D, yMove2D) within label i 2D type movement parameters ) {    // Determine if the label is still inside the map boundary after movement.    // This is really a test to see if the label is too big to fit in the map.    // Here, a vertex on the map boundary is not outside the map.    // This test works because both label and map are convex polygons.    for j = first vertex of label i to last vertex of label i    label_moved_outside_map = FALSE    if ( ( vertex j + (xMove2D, yMove2D) ) of label i is outside map boundary ) {     label_moved_outside_map = TRUE    }    next j    if ( label_moved_outside_map = FALSE ) {    set label i flag LABEL_MOVED_INTO_PORTRAIT = TRUE    set label i parameter LABEL_NEW_LOCATION = (xMove2D, yMove2D)    }   }   }   else { // vector type movement   count = 0   // If both conditions are true, the label will not fit into the map.   if ( x_low < 0 ) {    find a point (x_IP, y_IP) which meets the following requirements    contained by a line parallel to the vector type movement    contained by a the line x = 0    contained by a line also containing (x_low, yL)   if ( (x_IP, y_IP) exists ) {    xMoveVec[count] = x_IP − x_low    yMoveVec[count] = y_IP − yL    place in list of possible label movement candidates    count = count + 1   }   }   else if ( x_high > map_x_size − 1 ) {   find a point (x_IP, y_IP) which meets the following requirements    contained by a line parallel to the vector type movement    contained by a the line x = map_x_size − 1    contained by a line also containing (x_high, yH)   if ( (x_IP, y_IP) exists ) {    xMoveVec[count] = x_IP − x_high    yMoveVec[count] = y_IP − yH    place in list of possible label movement candidates    count = count + 1   }   }  // If both conditions are true, the label will not fit into the map.   if ( y_low < 0 ) {   find a point (x_IP, y_IP) which meets the following requirements    contained by a line parallel to the vector type movement    contained by a the line y = 0    contained by a line also containing (XL, y_low)   if ( (x_IP, y_IP) exists ) {    xMoveVec[count] = x_IP − xL    yMoveVec[count] = y_IP − y_low    place in list of possible label movement candidates    count = count + 1   }   }   else if ( y_high > map_y_size − 1 ) {   find a point (x_IP, y_IP) which meets the following requirements    contained by a line parallel to the vector type movement    contained by a the line y = map_y_size − 1    contained by a line also containing (xH, y_high)   if ( (x_IP, y_IP) exists ) {    xMoveVec[count] = x_IP − xH    yMoveVec[count] = y_IP − y_high    place in list of possible label movement candidates    count = count + 1   }   }   // Can have zero, one, or two possible label movement candidates   for k = 0 to (count − 1)   // Determine if the label is still within its movement parameters.   // This means has the label moved too far from its original position.   // The original location parameter is never changed. It does not change   // because it is always used for comparison to the new position.   move_distance = magnitude of (xMoveVec[k], yMoveVec[k])   if ( move_distance within label i vector type movement parameters ) {    // Determine if the label is still inside the map boundary after movement.    // This is really a test to see if the label is too big to fit in the map.    // Here, a vertex on the map boundary is not outside the map.    // This test works because both label and map are convex polygons.    for j = first vertex of label i to last vertex of label i     label_moved_outside_map = FALSE     if(( vertex j + (xMoveVec[k], yMoveVec[k])) of label i is outside map boundary) {     label_moved_outside_map = TRUE     }    next j    if ( label_moved_outside_map = FALSE ) {     set label i flag LABEL_MOVED_INTO_PORTRAIT = TRUE     set label i parameter LABEL_NEW_LOCATION = (xMoveVec[k], yMoveVec[k])     break out of loop // go past next k    }    }   next k   } // end of vector type movement  }  if ( label i flag LABEL_MOVED_INTO_PORTRAIT = FALSE ) {   set label i flag LABEL_TOO_MUCH_OUTSIDE_PORTRAIT = TRUE  }  } // end if label_inside_map = FALSE next i // THIS IS THE START OF ROUTINE 20 // Sort the labels by priority. // The labels with the highest priorities have the lowest numbers. // Priorities may be negative numbers. // Labels may have the same priority. // After this loop, assume all labels are ordered properly. Sort labels by priority from the most important label to the least important label  and place into a data structure map // THIS IS THE START OF ROUTINE 30 // Initialize halting criteria variables priority_range = priority_of_least_important_label − priority_of_most_important_label // initialize these two variables to large numbers previous_collision_score = Very Large Number previous_previous_collision_score = Very Large Number iteration_count = 0 slow_change_count = 0 oscillation_count = 0 Referring to FIGS. 7 a and 7 b , labels are compared to determine if they overlap (routine 40 ). The number of labels and the maximum numerical difference between the highest and lowest priority labels is determined in step 400 . All labels are grouped according to priority. In step 403 , a loop cycles through all the priorities from the highest priority (i.e. priority 0) to the lowest priority of the labels (i.e. priority last_Pri), for every integer from 0 to last_Pri. In step 406 , it is determined if there are any labels corresponding to the current priority in the loop. If there are no labels with the current priority of the loop, then in step 409 , set the value of array first_label[current priority of loop] to −1 and set the value of the array last label [current priority of loop] to −1. If there are labels with the current priority of the loop, then in step 412 , set the value of array first_label [current priority of loop] to the index of the most important label with priority p and set the value of the array last_label [current priority of loop] to the index of the least important label with priority p. It is important to choose the order of comparison properly to avoid excessive calculation and moving labels more times than necessary. This part compares two labels using loops. In step 415 , the loop for the first label starts at priority 0 and goes to priority last_Pri. In step 421 , if the value of the variable: first_label [current priority of first loop] is equal to −1, then go back to the beginning of loop for the first label. Otherwise, go to step 424 . In step 424 , the loop for the second label starts at the current priority of the first loop and goes to priority ‘last_Pri.’ In step 427 , if the value of the variable: first_label [current priority of second loop] is equal to −1, then go back to the beginning of loop for the second label. Otherwise, go to step 430 . In step 430 , a third loop starts at the index in the list of labels of the first label with a priority equal to the current priority of the first loop and goes to the index in the list of labels of the last label with a priority equal to the current priority of the first loop. In step 433 , if the label with the current index in the list of labels from the loop in step 430 is completely outside of the map or too much of the label is outside of the map, then go back to step 430 . Otherwise, go to step 436 . In step 436 , a fourth loop starts at the index in the list of labels of the first label with a priority equal to the current priority of the second loop and goes to the index in the list of labels of the last label with a priority equal to the current priority of the second loop. When step 436 has finished examining the relevant labels, then step 436 returns to step 430 . As discussed above, when step 430 has finished examining the relevant labels, then step 430 returns to step 424 . If step 426 has not finished examining the relevant labels, then proceed to step 439 . In step 439 , if the label with the current index in the list of labels from the loop in step 436 is completely outside of the map or too much of the label is outside of the map, then go back to step 436 . Otherwise, go to step 442 . In step 442 , if the current label index of the loop in step 430 is less than or equal to the current label index of the loop in step 436 , then go to step 436 . Otherwise, go to step 445 . Step 445 , which corresponds to routine 45 , tests for overlap between the members of the pair. Step 448 , which corresponds to routine 50 , performs the movement procedure on one of the labels if they overlap. Step 418 exits routine 40 and proceeds to routine 60 , an evaluation function procedure. The above-described logic is further shown in the following pseudo-code with comments: Order of Comparison for the Label Overlap Test Routine // The n labels have already been sorted in priority order, // from the most important, label 0, consecutively, // to the least important, label (n − 1). LABEL_TOO_MUCH_OUTSIDE_PORTRAIT - indicates if the procedure has determined that the label has much area outside the map boundary or can not be properly moved to a new position completely inside the map boundary. This is a flag of every label set by the procedure. LABEL_OUTSIDE_PORTRAIT - Not used. This is a flag of every label set by the procedure. LABEL_MOVED_INTO_PORTRAIT - indicates if the procedure has moved a label that was originally partially outside the map boundary to a new position completely inside the map boundary. This is a flag of every label set by the procedure. last_Label_Index = number_of_labels − 1; // zero based // Zero based. // The highest priority is zero and the lowest priority is a number greater than zero. // Note that there may be priorities which have no labels. last_Pri = lowest priority − highest priority; // which equal the lowest priority // Below, if there are no labels with priority p, // first_Pri[p] = −1 and last_Pri[p] = −1 // first_label[p] = first label index with priority p // last_label[p] = last label index with priority p for p = 0 to last_Pri; // highest priority to lowest priority  if labels with priority p exist  first_label[p] = most important label with priority p;  last_label[p] = least important label with priority p;  else  first_label[p] = −1;  last_label[p] = −1; next p; for i_pri = 0 to last_Pri; // highest priority to lowest priority  if first_label[i_pri] = −1, continue to next i_pri;  for j_pri = i_pri to last_Pri; // highest priority to lowest priority  if first_label[j_pri] = −1, continue to next j_pri;  for i_idx = first_label[i_pri] to last_label[i_pri];  if i_idx flag  LABEL_TOO_MUCH_OUTSIDE_PORTRAIT = TRUE OR         LABEL_OUTSIDE_PORTRAIT = TRUE, continue to next i_idx   for j_idx = first_label[j_pri] to last_label[j_pri];   // Do not compare a label to itself or   // compare labels which have been previously compared,   // for this particular iteration of the entire algorithm.   if i_idx <= j_idx, continue to next j_idx;   if j_idx flag  LABEL_TOO_MUCH_OUTSIDE_PORTRAIT = TRUE OR         LABEL_OUTSIDE_PORTRAIT = TRUE, continue to next j_idx   if label i_idx overlaps label j_idx,      then perform the label movement procedure on label j_idx;   next j_idx;  next i_idx;  next j_pri; next i_pri; All labels are restricted to convex planar polygons in the plane of the map. A planar polygon is convex if it contains all the line segments connecting any pair of its points. If two convex planar polygons overlap, this means that: 1) at least one vertex of one polygon is inside the other polygon, or 2) at least one edge of one polygon intersects an edge of the other polygon. Routine 45 , shown in FIG. 8 , is a label overlap test procedure. The overlap test has three parts. First, it determines if any vertex of the first polygon is inside the second polygon, step 462 . Second, it determines if any vertex of the second polygon is inside the first polygon, step 466 . Third, it determines if any edge of the first polygon intersects any edge of the second polygon step 470 . Once any vertex is found to be inside the other polygon, there is no need to test remaining vertices and edges. Once any edge is found to intersect any edge of the other polygon, there is no need to test remaining edges and vertices. Prior to the overlap test, routine 45 begins by receiving two labels from caller in step 450 . In step 454 , the maximum and minimum x and y values for each label are determined. These x and y values form circumscribing rectangles, whose edges are parallel to the map's x axis and y axis, for each label. In step 458 , the circumscribing rectangles for each label are compared. If these circumscribing rectangles do not overlap, then routine 45 returns “no overlap” to the caller in step 478 . FIG. 8 shows the test for whether a vertex of a polygon is inside another polygon. The method is shown in “Determining if a Point Lies on the Interior of a Polygon,” Paul Bourke (available on the world wide web). Consider the standard right-handed two-dimensional Cartesian coordinate system with the positive y direction up and the positive x direction to the right. A first polygon's edges are chosen such that the perimeter is traversed in the counterclockwise (CCW) direction (the perimeter may be traversed in a clockwise direction so long as it is done consistently). At step 462 , if any vertex of a second polygon is to the left of all edges of the first polygon, then that vertex is inside the first polygon. Likewise, at step 466 , if any vertex of the first polygon is to the left of all edges of the second polygon then that vertex is inside the second polygon. If any vertex of a polygon is inside another polygon, then the polygons overlap. This is the test for a point being inside a convex planar polygon. Lines containing the edges that make up a polygon may be written, ( y−Y 1)( X 2 −X 1)−( x−X 1)( Y 2 −Y 1)=0 where (x,y) is any point on the line, and (X1,Y1) and (X2,Y2) are the endpoints of an edge of the polygon under test. Points lying on the polygon edges satisfy the line equations, while points not on the polygon edges do not satisfy those equations. If (x, y) is any point in the plane, the equation for a line containing an edge is: ( y−Y 1)( X 2 −X 1)−( x−X 1)( Y 2 −Y 1)= K where K is a real number constant. Then, for all points to the left of any edge, K>0, and for all points to the right of any edge, K<0. Note that point 2 in the above equation is at the head of the vector representing the edge and point 1 is at the tail of the vector representing edge. This is true because, for all edges pointing to the right, (X2−X1)>0. For any point above the line containing the edge, (x_above, y_above), there exists a point, (x,y), on the line, such that: x _above= x and y _above> y Therefore: ( y−Y 1)( X 2 −X 1)−( x−X 1)( Y 2 −Y 1)=( y−Y 1)( X 2 −X 1)−( x−X 1)( Y 2 −Y 1) ( y _above− Y 1)( X 2 −X 1)−( x−X 1)( Y 2 −Y 1)>( y−Y 1)( X 2 −X 1)−( x−X 1)( Y 2 −Y 1) ( y _above− Y 1)( X 2 −X 1)−( x _above− X 1)( Y 2 −Y 1)>( y−Y 1)( X 2 −X 1)−( x−X 1)( Y 2 −Y 1) A point that is above a line pointing to the right is a point that lies to the left of the line. Similar arguments show that any point on the left of lines pointing up, pointing down, or pointing left yields a positive value with substituted into the line equation. Step 470 tests whether the edges of one polygon intersect another polygon. Consider the equations of the lines that contain the edges of the first polygon and the equations of the lines that contain the edges of the second polygon. Determine the intersection point for every two-line combination, where one line is a line that contains an edge of the first polygon and the other line is a line that contains an edge of the second polygon. If the intersection point lies on or between the endpoints of the polygon edges, then the edge of one polygon intersects the edge of the other polygon and the polygons overlap. In cases where the lines are parallel, and not coincident, no intersection point exists for that pair of lines. If the lines are coincident, then the edges may or may not touch, but if the edges touch then the polygons overlap. If the three above overlap tests, at step 462 , step 466 , step 470 , find an overlap between the two labels, then routine 45 returns “labels overlap” to the caller in step 482 , step 486 , and step 490 , respectively. If after performing the three tests, there is no overlap between the two labels, then routine 45 returns “no overlap” to the caller in step 474 . The above-described logic is further shown in the following pseudo-code with comments: Pseudo-code for the Overlap Test Of Convex Planar Polygons List of pseudo-code variables (x_2_i, y_2_i) - vertex i of polygon 2 (X1_j, Y1_j) - vertex 1 of edge j of polygon 1 (X2_j, Y2_j) - vertex 2 of edge j of polygon 1 (x_IP, y_IP) - intersection point of lines containing edges x_max_i - max x of edge i y_min_j - min y on edge j find max x, max y, min x, min y on polygon 1 - each will be on a vertex find max x, max y, min x, min y on polygon 2 - each will be on a vertex // if any expression is true, the polygons do not overlap, so return false if (min x of polygon 1 >= max x of polygon 2) RETURN NO_OVERLAP if (min x of polygon 2 >= max x of polygon 1) RETURN NO_OVERLAP if (min y of polygon 1 >= max y of polygon 2) RETURN NO_OVERLAP if (min y of polygon 2 >= max y of polygon 1) RETURN NO_OVERLAP // if any vertex of polygon 2 is inside polygon 1, the result is greater than zero. // proceed around polygon 1 in the CCW direction for each vertex of polygon 2 for i = first vertex of polygon 2 to last vertex of polygon 2  inside = TRUE  for j = first edge of polygon 1 to last edge of polygon 1 in CCW direction  if((y_2_i − Y1_j) (X2_j − X1_j) − (x_2_i − X1_j) (Y2_j −  Y1_j) <= 0) inside = FALSE  next j  if (inside = TRUE), RETURN OVERLAP next i Repeat the above, except test polygon 1 vertices with polygon 2 edges Return OVERLAP if appropriate // perform the edge intersection test for i = first edge of polygon 1 to last edge of polygon 1  of the two endpoints of edge i, get x_max_i, y_max_i, x_min_i,  y_min_i  for j = first edge of polygon 2 to last edge of polygon 2  of the two endpoints of edge j, get x_max_j, y_max_j, x_min_j, y_min_j  solve for intersection point, (x_IP, y_IP), of lines containing edge i and edge j  if intersection point exists   // An intersection at an endpoint is an overlap.   // These tests also take care vertical and horizontal edges.   if (x_IP <= x_max_i and x_IP >= x_min_i) and    (y_IP <= y_max_i and y_IP >= y_min_i) and    (x_IP <= x_max_j and x_IP >= x_min_j) and    (y_IP <= y_max_j and y_IP >= y_min_j), RETURN    OVERLAP  next j next i RETURN NO_OVERLAP Labels must be moved about the map to clear existing label collisions. After it is determined that two labels overlap, routine 50 ( FIGS. 9 a , 9 b , and 9 c ) finds several new locations for the lower priority of the two labels that eradicate the existing overlap. The higher priority label is a first label while a lower priority label is a second label. These locations are ranked by how far the second label must be moved, shortest to longest. The actual location finally selected must meet the following criteria: 1) the second label moves a shorter distance than other qualifying locations; 2) the second label movement does not result in overlap with another label (or labels) of equal or higher priority than the first label; 3) the second label movement does not exceed the maximum movement parameters for that particular label; and 4) no part of the second label is moved outside the map boundary. If no candidate locations meet these criteria, the second label is not moved. During the process of fixing existing collisions, other collisions may be created. New collisions are only allowed if it reduces collisions among labels with priorities equal to or higher than the first label. As the procedure iterates, new collisions are handled like the original collisions. The procedure will minimize collisions. Each label may be moved in one of two ways. A caller selects the type of movement of a label to the exclusion of the other type of movement. First, a label may move in any direction on the map, up to a maximum distance from the original location. This is referred to as 2D type movement. Second, a label may move parallel to a vector up to a maximum distance from the original location in the positive vector direction or the negative vector direction. This is referred to as vector type movement may be used for linear features such as highways and rivers. Both the vector and the maximum distances are in the label's parameter list. Labels on a map may consist of any mixture of 2D movement and vector movement types. However, higher priority labels must be examined before lower priority labels regardless of movement type. Prior to the attempted label movement, routine 50 begins by receiving two labels from caller in step 500 . Routine 50 cycles through the edges of first label in step 503 and cycles through the vertices of second label in step 509 . A counter is set in step 506 . The first label's edges are traversed in a CCW direction. Remembering that these operations take place on a two dimensional map, step 512 tests whether each vertex of the second label is left of a line containing an edge of the first label when the first label is traversed in a CCW direction. A vertex of the second label is said to be on a label side of the line containing the edge of the first label if the vertex of the second label and area of the first label are on the same side of the line containing the edge of the first label. Note that these labels are restricted to convex polygons so all of one label will be on one side of the line containing the label's edge and no part of the label will be on the other side of the line. Likewise, a vertex of a second convex polygon is said to be on a convex polygon side of a line containing an edge of a first convex polygon if the vertex of the second convex polygon and area of the first convex polygon are on the same side of the line containing the edge of the first convex polygon. If step 515 specifies a 2D type movement, then step 518 finds an intersection of two lines. A first line is the line that contains one edge of the first label. A second line is perpendicular the first line and contains the vertex. If, instead, step 515 specifies a vector type movement, then step 521 finds an intersection of a line containing an edge and a line parallel to the vector type movement also containing the vertex. If in either the 2D type movement case or the vector type movement case, an intersection exists step 524 , and the vertex is on the label side as defined above, step 527 calculates a first vector from the vertex to the intersection. If the first vector is too small, step 530 , then the routine 50 calculates, in steps 533 , 536 , and 539 , a second vector with desirable properties listed in steps 536 and 539 . In the case that the first vector is too small, the first vector is replaced by the second vector. Whichever vector remains, it is hereafter referred to as the vector. Step 542 tests whether the vector is within movement bounds from the original label location. If at step 545 , it is within bounds, the vector is placed on an end of a list of qualified vectors and a length of the vector is placed on an end of a length list. Once all vertices of the second label are tested, if there any qualified vectors (step 548 ), then, at step 551 : 1) Find the maximum length in the length list and a corresponding qualified vector from the vector list; 2) Insert the length and the qualified vector into a data structure map that is sorted by distance; and 3) Empty the length list and vector list. After all the edges of the first label are checked, at step 554 the steps starting at step 512 are repeated using the edges of the second label and the vertices of the first label. For any qualifying vectors, a negative of the vector is taken and that vector and its length are inserted into the data structure map. Next, tests are performed to determine if proposed locations for the second label are acceptable. At step 560 , starting with a shortest vector in the data structure map, the second label is moved in both a direction and a length of the shortest vector to obtain a new location for the second label. Then, at step 563 , a test is performed to determine if part of the new location for the second label is outside the map boundary. If, the new location for the second label places part of the second label outside the map boundary, repeat steps 557 , 560 , and 563 , using a next vector from the data structure map. Step 566 retrieves labels with priorities greater than or equal to the first label. In step 569 , if any retrieved label is the first label or the second label, then retrieve the next label in step 566 . At step 572 , the overlap test is performed on the current candidate location for the second label against labels that fail tests at step 563 and step 569 . If there is an overlap, steps 557 through 572 are repeated. Otherwise, the second label is moved to the candidate location in step 575 . After a new location is found for the second label among the proposed locations, or after all proposed locations are determined to be unacceptable, then data structure map is cleared in step 578 , and a next pair of labels is supplied in step 581 . The above-described logic is further shown in the following pseudo-code with comments: Movement Procedure of Convex Planar Polygons // List of pseudo-code variables (x_2_j, y_2_j) - vertex j of polygon 2 (X1_i, Y1_i) - vertex 1 of edge i of polygon 1 (X2_i, Y2_i) - vertex 2 of edge i of polygon 1 (x_IP, y_IP) - intersection point of lines containing edge and vertex (X,Y) - vector from vertex to edge pseudo-code also has:  a list of distances  a list of vectors  a data structure map of distances and vectors sorted by distance, short to long // Polygon 1 is the more important polygon and polygon 2 will move if possible // Here, the vertices in a polygon are on the left side of the edge // of the other polygon when traversing it in the CCW direction, // but the vertices are not necessarily inside the other polygon. // That is why all possibilities are caught in the algorithm below - // even where no vertex from either polygon is inside the other. // Do not have to check specifically for the above case. // If a vertex of polygon 2 is on left side a polygon 1 edge, the result is greater than zero. // proceed around polygon 1 in the CCW direction for each vertex of polygon 2 // Note the the vertex in question does not have to be inside polygon 1 for i = first edge of polygon 1 to last edge of polygon 1 in CCW direction  count_of_possible_vertices = 0  for j = first vertex of polygon 2 to last vertex of polygon 2  if((y_2_j − Y1_i)(X2_i − X1_i) − (x_2_j − X1_i)(Y2_i −  Y1_i) > 0)   if (2D type movement for polygon 2)   // a solution will always exist for this case   solve for intersection point, (x_IP, y_IP), of a line containing edge i   and a line perpendicular to edge i containing (x_2_j, y_2_j)   if (vector type movement for polygon 2)   // a solution might not exist for this case   solve for intersection point, (x_IP, y_IP), of a line containing edge i   and a line parallel to the vector type movement containing (x_2_j, y_2_j)   if ( solution exits for (x_IP, y_IP) )   // get vector from vertex to intersection point   (X,Y) = (x_IP − x_2_j, y_IP − y_2_j)   if ( (X,Y) length minute )    if ( 2D type movement for polygon 2 )     find a point (X,Y) which meets the following requirements    on right side of edge i (CCW)    contained by a line perpendicular to edge i    contained by a line also containing (x_IP, y_IP)    a minute distance from (x_IP, y_IP)    else // vector type movement for polygon 2     find a point (X,Y) which meets the following requirements    on right side of edge i (CCW)    contained by a line parallel to the vector type movement    contained by a line also containing (x_IP, y_IP)    a minute distance from (x_IP, y_IP)   // because polygon may move several times, keep the original location of the label   if ( movement of (X,Y) leaves polygon with movement limit )    // Make vector just a bit larger that the distance to the edge    // so when polygon 2 is moved, it moves just outside the polygon 1    length_of_XY = length of (X, Y) * (1.0 + 1.0e−09)    X = X * (1.0 + 10e−09)    Y = Y * (1.0 + 10e−09)    append length_of_XY to end of distance list    append (X,Y) to end of vector list    count_of_possible_vertices = count_of_possible_vertices + 1  next j  if (count_of_possible_vertices > 0)   find the maximum distance in the distance list   get the corresponding vector to this distance from the vector list   insert the distance and the vector into the data structure map sorted  by distance,   from the shortest distance to the longest distance   empty distance list and vector list  next i  Repeat the above, except use polygon 1 vertices and with polygon 2  edges  The vector for possible movement, (X,Y), is reversed  Insert the results into the same distance/vector data structure map  // the outer loop is just going thought the sorted data structure map  for i = first location candidate to last location candidate   get new location for polygon by adding vector (X,Y) to each vertex   if ( any part of label outside map boundary ) next i   for j = first label to last label whose priority >= polygon 1    if ( polygon 1 is label j or polygon 2 is label j) next j    if ( polygon 2 in location candidate i overlaps label j ) next i    update polygon 2 location in its parameter list    break out of both for loops   next j  next i  clear the data structure map  get the next pair of labels to be tested for overlap The Evaluation Function, the Halting Criteria, and the Adjustment of Label Properties The following pseudo-code contains a reminder to initialize collision scores and priority ranges at the top of the procedure. This is shown in FIG. 10 , assignment 590 . It is probable that the process of label movement will iterate indefinitely, therefore halting criteria are needed. An evaluation function provides input to a halting procedure to stop the process at an acceptable point. The calculation of the evaluation function is represented by routine 60 as shown in FIG. 11 . All labels that overlap are known at this point. The procedure used to reduce label collisions is an iterative process. A collision score is a variable that measures the severity of collisions of labels in the map. It is initialized to zero in step 600 . Step 605 performs cycling through label pairs. In step 610 , each label of the current pair of labels is tested to see if it has too much of its area outside the map or if it is completely outside the map. This avoids unnecessary calculation for labels that will not be used. The overlap test (routine 45 ) is performed in step 615 . If no overlap occurs between the two labels being tested, then another unique pair of labels is fetched in step 605 . If overlap occurs, then the collision score is added to the previous collision score in step 620 . The final value of the collision score is attained after all the unique label pairs have been tested. In this anti-collision procedure for maps, the evaluation function at step 620 is: Collision ⁢ ⁢ Score = ∑ ij ⁢ ( ( label ⁢ ⁢ i ⁢ ⁢ adjusted ⁢ ⁢ priority ) 2 + ( label ⁢ ⁢ j ⁢ ⁢ adjusted ⁢ ⁢ priority ) 2 ) where the score is the summation over every pair of overlapping labels. The result of this function is defined as zero if no collisions remain and greater than zero if any collisions remain. The function penalizes disproportionately for collisions involving high priority labels. For instance, a collision involving a high priority label and a low priority label gets a higher score (worse) than a collision involving two medium priority labels. Routine 70 as shown in FIG. 12 evaluates halting criteria to determine if the labels are in optimal locations. The iterative process must halt at some point. A slow change halting criteria is evaluated in step 700 . If the slow change per iteration in the collision score occurs, the slow change count is incremented by one in step 705 . If the slow change per iteration does not occur, the slow change variable is reset to zero in step 710 . A short-term oscillation halting criteria is evaluated in step 715 . If the short-term oscillation in the collision score occurs, the short-term oscillation count is incremented by one in step 720 . If the short-term oscillation does not occur, the short-term oscillation count is reset to zero in step 725 . The previous values of the collision score are stored in step 730 . Step 730 also increments the iteration count by one. Here, an iteration is one cycle of the anti-collision algorithm that includes routines 40 , 45 , 50 , and 60 . Example rules tested at step 735 to halt the procedure follow: 1) the evaluation function is below a minimum value; 2) the number of iterations is greater than a maximum value; 3) the evaluation function changes less than a minimum percentage of the previous iteration for more than a set number of iterations; and 4) the evaluation function oscillates for more than a set number of consecutive iterations. If none of these conditions is met, the anti-collision algorithm is repeated in step 740 , noting that labels may move several times before the iterations stop. A label's new position is stored in its parameter list at the time a label is moved. The original position is always available in the label's parameter list. Routine 80 , as shown in FIG. 13 , adjusts label properties. At this point, labels will not be moved because the halting criteria have been satisfied. However, some labels may still overlap. Routine 80 begins in step 800 by setting the DRAW flag to TRUE for every label. Step 805 performs cycling through label pairs. In step 810 , each label of the current pair is tested to see if it has too much of its area outside the map or if it is completely outside the map. This avoids unnecessary calculation for labels that are not used. Labels that have some or all of their area outside the map have their DRAW flag set to FALSE in step 815 . The overlap test (routine 45 ) is performed in step 820 on those label pairs for which neither have any area outside the map. If no overlap occurs between the two labels being tested, then another unique pair of labels is fetched in step 805 . Otherwise, go to step 825 . In step 825 , if both labels have MUST DRAW=TRUE, then go to step 840 . Otherwise, go to step 830 . In step 830 , if the first label has MUST DRAW=TRUE, then go to step 840 . Otherwise, go to step 835 . In step 835 , if the second label has MUST DRAW=TRUE, then go to step 845 . Otherwise, go to step 840 . In step 840 , the second label has its draw flag set to DRAW=FALSE. In step 845 , the first label has its draw flag set to DRAW=FALSE. Here, the first label is higher on the list of labels than the second label. These flags are in the label's parameter list. The MUST DRAW flag is set by the caller. If the DRAW flag is true, this procedure will draw the label. If the DRAW is false, this procedure will not draw the label. For any pair of overlapping labels, the following somewhat arbitrary rules determine the final state of a label's DRAW flag: 1) If one label has MUST DRAW=TRUE, that label sets DRAW=TRUE, and the second label sets DRAW=FALSE. 3) If both labels have MUST DRAW=TRUE, the label higher on the list of label priority sets DRAW=TRUE, and the other label sets DRAW=FALSE. Note that this will hold for labels of equal priority. 4) If neither label has MUST DRAW=TRUE, the label higher on the list of label priority sets DRAW=TRUE, and the other label sets DRAW=FALSE. Note that this will hold for labels of equal priority. The label priority list and the overlap test are described in preceding sections of the description of the entire anti-collision procedure. After label properties are adjusted, control is returned to the caller, in step 900 of FIG. 14 . The above-described logic is further shown in the following pseudo-code with comments. Pseudo-Code for the Evaluation Function, the Halting Criteria, and the Adjustment of Label Properties List of pseudo-code variables collision_score - the sum of the evaluation function after each Iteration previous_collision_score - the collision score from the previous iteration previous_previous_collision_score - the collision score from two iterations ago iteration_count - number of times the anti-collision procedure has Looped slow_change_count - number of iterations of continuous slow change of collision score oscillation_count - number of iterations of continuous oscillation of collision score priority_of_most_important_label - numerical priority value of the most important label priority_range - the difference between the priority of the least and the most important labels. This number is non-negative. adjusted_priority_1 - the label 1 priority modified to make it work in the evaluation function // Initialize halting criteria variables priority_range = priority_of_least_important_label - priority_of_most_important_label // initialize these two variables to large numbers previous_collision_score = Very Large Number previous_previous_collision_score = Very Large Number iteration_count = 0 slow_change_count = 0 oscillation_count = 0 //------ The above must be done at the top of the procedure --------// // Evaluation Function ----------------------------------------------------- collision_score = 0 // these loops go thought label priority list for i = first label to last label  if( label i flag LABEL_TOO_MUCH_OUTSIDE_PORTRAIT =  TRUE OR   label i flag LABEL_OUTSIDE_PORTRAIT = TRUE ) next i  for j = label i+1 to last label  if( label j flag LABEL_TOO_MUCH_OUTSIDE_PORTRAIT =  TRUE OR   label j flag LABEL_OUTSIDE_PORTRAIT = TRUE ) next j  if( label i and label j overlap )  {   // Adjust the label priorities to make the evaluation function work properly.   // Note that the highest priority labels are assigned the lowest numbers and   // priorities may be positive or negative.   adjusted_priority_1 = 1 + priority_range -          ( label_1_priority - priority_of_most_important_label )   adjusted_priority_2 = 1 + priority_range -          ( label_2_priority - priority_of_most_important_label )   collision_score = collision_score +         (adjusted_priority_1) * (adjusted_priority_1) +         (adjusted_priority_2) * (adjusted_priority_2)   }  next j next i // Halting Algorithm ------------------------------------------------------ // is there slow change ? if(collision_score <= previous_collision_score AND  collision_score > 0.98*previous_collision_score) {  slow_change_count = slow_change_count + 1 } else {  slow_change_count = 0 } // is there oscillation ? if( (collision_score > previous_collision_score AND   previous_collision_score < previous_previous_collision_score ) OR   (collision_score < previous_collision_score AND   previous_collision_score > previous_previous_collision_score ) ) {  oscillation_count = oscillation_count + 1 { else }  oscillation_count = 0 } iteration_count = iteration_count + 1 previous_previous_collision_score = previous_collision_score previous_collision_score = collision_score if(collision_score = 0) goto ADJUST_LABEL_PARAMETERS if(iteration_count > 20) goto ADJUST_LABEL_PARAMETERS if(slow change_count > 4) goto ADJUST_LABEL_PARAMETERS if(oscillation_count > 6) goto ADJUST_LABEL_PARAMETERS goto Start of Next Iteration ADJUST_LABEL_PARAMETERS: //---------------------------------- // set label flag DRAW = TRUE for all labels for i = first label to last label  label_i_DRAW = TRUE next i // these loops go thought label priority list and set the draw flag for i = first label to last label  if( label i flag LABEL_TOO_MUCH_OUTSIDE_PORTRAIT =  TRUE OR   label i flag LABEL_OUTSIDE_PORTRAIT = TRUE )  {   label_i_DRAW = FALSE   next i  }  for j = label i+1 to last label   if( label j flag LABEL_TOO_MUCH_OUTSIDE_PORTRAIT =   TRUE OR    label j flag LABEL_OUTSIDE_PORTRAIT = TRUE )   {    label_j_DRAW = FALSE    next j   }   if( label i and label j overlap )   {    if ( label_i_MUST_DRAW = TRUE AND label_j_MUST_    DRAW = TRUE )    {     label_j_DRAW = FALSE   }    else if ( label_i_MUST_DRAW = TRUE )    {     label_j_DRAW = FALSE    }    else if ( label_j_MUST_DRAW = TRUE )    {     label_j_DRAW = FALSE    }    else    {     label_j_DRAW = FALSE    }   }  next j next return to caller While the particular SYSTEM AND METHOD FOR LABELING MAPS as herein shown and described in detail is fully capable of attaining the above-described objects of the invention, it is to be understood that it is the presently preferred embodiment of the present invention and is thus representative of the subject matter which is broadly contemplated by the present invention, that the scope of the present invention fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the present invention is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular means “at least one”. All structural and functional equivalents to the elements of the above-described preferred embodiment that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims. Moreover, it is not necessary for a device or method to address each and every problem sought to be solved by the present invention, for it to be encompassed by the present claims. Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims.

A system and method for label placement is disclosed that achieves the twin goals of practical efficiency and high labeling quality by employing cartographic heuristics. A caller defines map and label properties. Then labels are pulled within a map boundary. Labels are next ordered by priority in descending importance. The order of testing labels is determined. Attempts are made to move overlapping labels. This is an iterative process; therefore there must be criteria that halt the procedure. Upon reaching an acceptable solution, the label properties are adjusted to reflect the new label placements.

Technical Field This application relates to a time division multiplexing (TDM) repeater method for supporting wide area networking of trunked radio systems. BACKGROUND OF THE INVENTION Time division multiplexing/time division multiple access (TDM/TDMA) repeater systems are known. Such systems are characterized by an inbound channel, utilized by a multiplicity of users, each of which being permitted the use of one or more non-overlapping time periods (slots) in which to transmit information. A continuous outbound channel exists, also time slotted to facilitate segregation of information directed to the various users, wherein at least some of the outbound transmitted information is derived from the received inbound information. The use of the aforementioned TDM/TDMA approach to provide widearea coverage trunking radio systems is also known. The requirements for these systems are great. On the one hand, it is desired to provide the variety of system configurations potentially necessary to provide wide area networked coverage, including satellite receivers, simulcast, etc. This may involve compensating for considerable delay in the system infrastructure. On the other hand, it is desired to maintain all the features of TDM including multi-radio capabilities such as full duplex, voice plus data, conferencing, priority monitor, emergency preemption, etc. Furthermore, system capacity and performance should not be compromised. A key problem is that of minimizing the bulk audio delay through the entire system. Excess delay introduces a confusion factor and reduces communications efficiency and user acceptance. The use of TDM already may introduce a substantial fixed amount of delay due to a relatively large RF channel framing such as, for example, 250 msec one-way. Thus, it is particularly important to minimize any additional delay introduced by any scheme for networking sites. The basic goals of a repeater in any wide area networked radio trunking system are as follows: For any transmitter node, it is desired to repeat a user's information that is somehow obtained from one or more signals either received at that node or received via alternate communications paths from potentially numerous other remote nodes throughout the network. The added audio delay should be as small as possible. In a multiple user TDM/TDMA system, there should also be no impact on the features or capabilities of the basic single-site TDM system. A key advantage of certain TDM/TDMA systems, however, is that a subscriber can transmit during one time slot and have all the other time slots available for reception to provide features such as receiving simultaneous data, monitoring the control channel (slot) for various purposes, conferencing, full duplex, and so forth. This requirement precludes the approach of shifting the outbound repeater timing relative to the inbound timing, since an overlap zone is formed that prevents subscriber reception of all the other outbound slots while transmitting, thereby limiting some of the TDM system features. Thus, it is desirable that the transmitter output TDM framing from all the nodes should be such that one user's information is repeated essentially coincident with when that same user is being received. Means for combining multiple signals from satellite receivers for retransmission is well known in the art. Likewise, introduction of infrastructure delay to align the timing of signals for simulcast retransmission is also well known. In the past, several schemes have been used to achieve this desired synchronization. One scheme has introduced additional guard time at the end of each inbound slot. The outbound slots are synchronized to the inbound frame and the received information is repeated slightly delayed in time within the same frame time slot. The impact of having to repeat this frame at a remote node is that the guard time must be increased to allow for the maximum backbone delay incurred from any receiver site to any transmitter in the network. The obvious disadvantage of this approach is that it would require such a substantial increase in propagation allowance that the channel capacity would be greatly diminished. A second approach likewise provides coincident inbound and outbound frames. Information received during a first slot is delayed for retransmission during a later slot. The main problem with this approach is that the additional incurred delay, over and above the basic TDM/speech coding delay, can be quite large. At least one full time slot's information, representing a frames worth of speech, is required to be received even if the next adjacent slot is used to repeat the inbound slot. As a result, there is a need for an improved method for repeating TDM/TDMA frames in a trunked wide area network environment. SUMMARY OF THE INVENTION It is an object of the invention to provide an improved method for repeating TDM/TDMA frames in a trunked wide area coverage radio network environment. Accordingly, an improved method for repeating TDM/TDMA frames is disclosed that repeats inbound information generally coincident or synchronized with the time that information is being received, yet minimizes the added bulk delay. In essence, the last part of the inbound information received in a previously received time slot is combined with all but the end of the currently received slot for repeating during the time of the currently received time slot. The information received at the end of the current time slot is "held over" for repeating or retransmission during the next assigned inbound time slot period. This method provides a timing technique that allows for wide area networking of TDM radio systems and maintaining all the features of TDM, yet without incurring excess added bulk delay. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a timing diagram that shows a first embodiment of a method for repeating TDM/TDMA frames, according to the invention. FIG. 2 shows a typical flow diagram for the first embodiment. FIG. 3 shows a typical repeater for practising the first embodiment. DETAILED DESCRIPTION OF THE INVENTION FIG. 1 is a timing diagram that shows a first embodiment of a method for repeating TDM/TDMA frames, according to the invention. There is shown on the top three consecutive inbound frames, designated for convenience inbound frame (k-1), inbound frame k, and inbound frame (k+1). Also is shown the corresponding three consecutive outbound frames, designated for convenience outbound frame (k-1), outbound frame k, and outbound frame (k+1). Note that each frame contains a plurality of slots, herein the initial or first slot designated slot A. Also note that each slot contains a plurality of message segments, herein six. For purposes of demonstrating the first embodiment, it is assumed that inbound frame (k-1) slot A contains the following message segments: 1', 2', 3', 4', 5', and 6'. Also, it is assumed that inbound frame k slot A contains the following message segments: 1, 2, 3, 4, 5, and 6. Finally, it is assumed that inbound frame (k+1) contains the following message segments: 1', 2', 3', 4', 5', and 6'. In FIG. 1, it is assumed that conventional approaches for handling TDM/TDMA radio trunking system synchronization and control are provided and, therefore, they are not shown. For example, the use of synchronization patterns may be provided within the inbound slot to facilitate the base repeater's synchronizing to the received inbound slot. There may also be inbound control and/or date information. The repeater may locally generate synchronization patterns, control and/or data to combine with the user information to comprise the complete transmitted outbound slot. For the purposes of describing this invention, it is only necessary to consider the actual repeated information format. For a typical speech example, each TDM frame might be 240 msec long with 4 slots per frame. With this arrangement, each inbound and outbound slot may contain 6 message segments, each representing 40 msec of speech, for a total of 240 msec. While this example uses message segments of uniform length for speech, other configurations are also possible. In fact, it will be appreciated that the message segments may be of non-uniform length and may transport a variety of information types using various coding schemes. It will also be appreciated that each frame may contain as few as two slots, and each slot may contain as few as two message segments. As shown by FIG. 1, each outbound slot includes all the message segments of the corresponding inbound slot except for the final message segment, which is saved. The saved message segment is then sent as the initial message segment of the succeeding outbound frame slot. Thus, only the last slot is delayed (saved) for subsequent repeating (retransmission). It will be appreciated, however, that instead of saving the last (individual) message segment, the last two (or some other number of) message segments could be saved or delayed. Consider frame (k-1) in FIG. 1. Inbound frame (k-1) slot A contains message segments 1' through 6'. Note the corresponding outbound frame (k-1) slot A contains message segments 1' through 5' only. Therefore, the message segment 6' is not sent during frame (k-1), and is saved for the succeeding frame k. Now consider frame k. Inbound frame k slot A contains message segments 1 through 6. Message segment 6', however, has been saved from the previous frame (k-1) and now must be sent as the first segment of outbound frame k slot A. The current inbound message segments 1 through 5 are now repeated as outbound segments. As a result, the current slot A message segment 6 is not sent during frame k, and is saved for the succeeding frame (k+1). Now consider frame (k+1), wherein slot A contains inbound message segments 1' through 6'. As before, however, the saved message segment 6 from the previous frame is the first outbound message segment to be sent in slot A in this frame. Inbound message segments 1' through 5' are then sent as outbound segments, leaving the current slot A message segment 6' to be saved for the next frame. The advantage of the disclosed technique is that it can be used to compensate for infrastructure delay between the receive and transmit paths. For the particular example and numbers given above, up to 10 msec of infrastructure delay is accommodated with the incurring of only 40 msec of actual additional audio delay. Greater infrastructure delay can be accommodated by using multiple message segments, longer message segments (e.g. by repartitioning or combining), etc. FIG. 2 shows a typical flow diagram for the first embodiment. It is assumed the current frame is numerically the kth frame, and that each slot has n message segments, and that the ith message segment is currently being received. The process starts at step 11, and then proceeds to step 13, wherein the ith inbound message segment is received. The process next goes to step 15, where the received segment is transferred to an inbound buffer as the ith stored segment. The process next decides whether this is the first message segment of the current slot to be received or, numerically, whether i=1, step 17. If the answer to this determination is negative, then the process recalls, or fetches, the (i-1)th stored segment from the inbound buffer, step 19, and transfers it to an outbound buffer, step 21. The process now transmits the current outbound segment from the outbound buffer, step 23, and returns, step 25. Now assume that the current received message segment is the first to be received for the current slot. In this case, at step 17, the process will affirm that i=1, and will go to step 27. Here the process retrieves, or fetches, the nth stored segment for the corresponding slot of the previous frame (k-1) from the inbound buffer, and transfers it to the outbound buffer step 21. The process now continues as above. As mentioned above, the result of this process is that, at the end of the current slot, the nth received segment is left over, or saved, to be transmitted as the initial outbound message segment of the corresponding slot of the next (successive) frame. Similar to above, it will be appreciated that while FIG. 2 depicts saving only the last individual nth segment, the last few final segments (such as two or more) could be saved. FIG. 3 shows a typical implementation of a repeater for practising the first embodiment. Referring now to FIG. 3, there is shown a repeater 101 with an input 103 and an output 105. The input 103 is connected to a common input 107 of a first two-position switch 109. The switch 109 has a first output 111 and a second output 113, and is controlled by a suitable timing and control circuit 115 such as a digital signal processor (DSP) or a suitably-programmed microprocessor. The output 105 is connected to a common output 117 of a second two-position switch 119 with a first input 121 and a second input 123. The switch 119 is likewise controlled by the timing and control circuit 115. The repeater 101 also includes a first information buffer 125 whose input 127 is connected to the first output 111 of the first switch 109 and whose output 129 is connected to the first input 121 of the second switch 119. The information buffer acts like a fixed length, clocked shift register. It has a length precisely equal to that of the message segment. The repeater 101 also includes a similar second information buffer 131 whose input 133 is connected to the second output 113 of the first switch 109 and whose output 135 is connected to the second input 123 of the second switch 119. It should be evident that the first two-position switch 109, when made to connect the common input 107 to the first output 111, may be used to steer the repeater input 103 to the input 127 of the first information buffer 125. Likewise, it should be obvious that the switch 109, when made to connect the common input 107 to the second output 113, may be used to route the repeater input 103 to the input 133 of the second information buffer 131. Thus, by controlling the position of the switch 109, a message segment 137 of an inbound TDM/TDMA frame may be clocked (or written) into either the first information buffer 125 or the second buffer 131. It should further be evident that the second two-position switch 119, when made to connect the common output 117 to the first input 121, may be used to connect the output 129 of the first information buffer 125 to the repeater output 105. Likewise, it should be clear that the switch 119, when made to connect the common output 117 to the second input 123, may be used to connect the output 135 of the second information buffer 131 to the repeater output 105. Thus, by controlling the position of the switch 119, a message segment 139 of an outbound TDM/TDMA frame may be clocked (or read) from either the first information buffer 125 or the second buffer 131. Assume now that switch 109 is initially set to connect the repeater input 103 to the input 127 of the first information buffer 125 and that switch 119 is initially set to connect the repeater output 105 to the output 129 of the first information buffer 125. With the foregoing in mind, it should be obvious that the repeater 101 may be made to function so that a first inbound segment is initially clocked into the first information buffer 125. Thereafter, the switch 109 changes position so the second inbound segment is clocked into the second information buffer 131 whilst the contents of the first information buffer 125 are clocked out as the second outbound segment. Thereafter, the switch 109 and the switch 119 both change position so the third inbound segment is clocked into the first information buffer 125 whilst the contents of the second information buffer 131 are clocked out as the third outbound segment. Thereafter, both switches change position together synchronized with the inbound segments so that, in general, each inbound segment is received and stored (or delayed) for retransmission as the next (or subsequent) outbound segment. At the end of any time slot, the last (most recent) inbound message segment will be saved (or stored) to be sent as the initial outbound message segment for the corresponding time slot for the next (succeeding) frame. As described herein, this invention provides a timing technique that allows for wide area networking of TDM trunking systems yet without incurring excess added bulk audio delay and maintaining all the inherent features of TDM. While various embodiments of a method for repeating TDM/TDMA frames, according to the present invention, have been described hereinabove, the scope of the invention is defined by the following claims.

An improved method for repeating TDM/TDMA frames in a trunked wide area network environment is disclosed that repeats a user's inbound information during the same time slot the user is assigned for transmit, yet minimizes the added bulk audio delay. According to the invention, the last portion of the inbound information received in a previously-received time slot is combined with all but the end of the currently-received slot for repeating during the currently-received time slot. The information received at the end of the current time slot is stored for repeating during the next assigned inbound time slot period. This method provides a timing technique that allows for wide area networking of TDM trunking systems, yet without incurring excess added bulk audio delay and maintaining all the features of TDM. A typical repeater embodying this method is also described.

CROSS REFERENCE TO RELATED APPLICATIONS This application claims priority to and benefit of U.S. Provisional Patent Application Ser. No. 61/398,632, filed on Jun. 29, 2010, which is incorporated herein by reference. FIELD OF THE INVENTION The present invention relates to semiconductor storage arrays, and more particularly to resistor arrays having two or three dimensions. REFERENCE TO A SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISK APPENDIX Not Applicable. REFERENCE REGARDING FEDERAL SPONSORSHIP Not Applicable. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT Not Applicable. SUMMARY OF THE INVENTION The present invention is a means and method for constructing and operating a 3-D array and, more particularly, a 3-D memory array. This array is intended to be manufacturable at low cost by virtue of the limited number of steps per layer of memory elements. The low number of steps results by having the storage elements separated by a resistive component as opposed to an active component. These storage elements are stacked vertically above a memory cell switch in the substrate. This switch is selected by x and y decoding of the row and column bits in the memory address. The present invention lends itself to single bit accesses as well as simultaneous multiple bit accesses. In a 3-D array such as a memory array, rows extend in the x direction, columns extend in the y directions, and the layers are stacked in the z direction. Conductive elements (i.e., wires) extending in the z direction are referred to as posts. Columns exist only in the foundation for the purpose of identifying a line of posts. Columns are not found in the layers of the array. Posts extend upwards from their respective column and through the layers of the array. To select a post, one must choose a column which will in turn select all of the posts extending upwardly from that column (i.e., choosing a column selects all of the posts upon that chosen column) or that column could enable a switch at the base of every post. A column choice is identified by a value on the x-axis. Rows, on the other hand, are found within the layers of the array (and not in the foundation). The rows are orthogonal to both the columns and the posts. Any set of rows that are all positioned vertically one above each other form a two-dimensional plane and are called a row-plane and a row-plane includes one row from every layer in making such a vertical collection of rows. A row-plane choice is identified by a value on the y-axis. FIG. 4 depicts a schematic for a row-plane in which layers are labeled A through D (the z-axis) and posts are labeled 1 through 16. By choosing a column and a row-plane, a single post will be selected at the intersection of that column and row-plane. By choosing a particular layer in addition to a post (i.e., a row-plane and a column), a single bit will be selected at the point of intersection of the chosen row on the chosen level with a post on the chosen column. A layer choice is identified by a value on the z-axis. The present invention is a 3-D array (or greater, multi-dimensional array) in which a switching element can exist at the end of the column or more likely exists at the bottom of each post (e.g., proximate to the connection of a post to a column). In this way, any one row-plane can be isolated from the rest and be accessed independently from all of the other row-planes in the 3-D array. This makes it possible to operate and analyze a single row-plane as a mostly stand-alone circuit. This makes it possible to operate and analyze a single two-dimensional plane (a row-plane) out of multi-dimensional (2-D, 3-D or greater) array as a mostly stand-alone circuit. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 depicts a 4 layer by 4 row by 16 column 3-D array. FIG. 2 depicts a partial schematic showing one row and 16 posts. FIG. 3 depicts a partial schematic showing two rows and 16 posts. FIG. 4 depicts a schematic for a row-plane showing four rows and 16 posts with post drivers driven from a reference row. FIG. 5 shows a table of voltage calculations having a correct guess for the selected memory element. FIG. 6 shows a table of voltage calculations having an incorrect guess for the selected memory element. FIG. 7 is a graph depicting voltages on the columns and on a selected Row while reading when the selected column in farther from the row driver. FIG. 8 is a graph depicting voltages on the columns and on a selected Row while reading when the selected column is closer to the row driver. FIG. 9 is a graph depicting voltages on the columns and on a selected Row while erasing. FIG. 10 is a graph depicting voltages on the columns and on a selected Row while programming in a three-dimensional array. DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention is a 3-D array in which a switching element exists at the bottom of each post (e.g., proximate to the connection of a post to a column). In this way, any one vertical row-plane can be isolated from the rest and be accessed independently from all of the other row-planes in the 3-D array. This makes it possible to operate and analyze a single row-plane as a mostly stand-alone circuit. A variety of switching elements are contemplated by the present teaching and include rectification devices of many types (including diodes, SCR's, OTS devices, four-layer diodes, and the like), switches of many types (including MOS, bipolar, unijunction and other types of transistors, organic switches, and the like), and other current controlling devices. It is not intended to limit the present teaching to any one type of current controlling device. Because of the economics of semiconductor manufacturing and processing, the layers will typically be far fewer in number than the row-planes and columns. As a result, analysis of a single row-plane will typically consist of the analysis of a resistive array that is large in one dimension (the posts along the x-axis) and small in the other (the layers in the z-axis). In other words, the post length typically will be small relative to the row length which will be long. FIG. 1 depicts a 3-D memory array. Typically, an actual array will have many more rows and columns, but for the sake of the present discussion, a small array is depicted. Generally speaking, the three dimensional memory or information storage array is made up of a plurality of vertically oriented two-dimensional arrays (row-planes) that are generally parallel to each other. These two-dimensional arrays consist of multiple, parallel conductive lines (herein called posts) that are connected to current controlling, switch devices in the substrate (such as bipolar or MOS transistors, SCR's, or the like). The posts pass through the layers of memory. Each layer within a row-plane has a conductive line and the memory bits (information storage elements) are positioned roughly where the posts intersect the conductive line of each layer. FIG. 2 depicts a partial schematic showing one row (A) and 16 posts. A resistive change memory element, 200 , is present at each node or point of crossing between a row and a post. At the end of the row (A), a current measuring circuit, 201 , is provided (shown as a simple op-amp sensor with negative feedback as is well understood by those skilled in the art). With the positive input to the op-amp set to a voltage, V, the right hand end of row (A) will also be maintained at this voltage potential, V. With no voltage applied to any post, row (A) will have no loading and no current will be flowing so all points along row (A) will also be at voltage potential, V. If a voltage is applied to any one post, a small current will flow and the output of the op-amp will fluctuate in proportion to that current (as a function of the feedback resistor of the op-amp and the resistance of the memory element at the node). The resistance of the row line and the selected post will also contribute to the output value. Since the post is short and its resistance will be small relative to the resistance of the memory element, 200 , the post resistance is being ignored for this initial analysis. If ground potential is applied to post 16 (with all the other posts floating), the resulting current, I, will be equal to V/(R+r) where R is the resistance of the memory element and r is the resistance of row (A) from approximately that point where row (A) crosses post 16 to the input of the op-amp. The resistance of any segment of row (A) from one post to the next post will be (r/16) and the voltage drop across any such segment will therefore be (I×r/16). With these equations in mind, the voltage along row (A) at every post can be calculated. One could let the voltage on each of the unselected posts continue to float, but in the alternative, one could apply these computed voltages along row (A) proximate to each post (bias voltages) to each unselected post (such that there should be no voltage potential across any of the unselected memory elements) and the output should be unchanged and no additional current will flow. In determining the calculated voltage values, one would (a) decide upon the voltage to be asserted on the selected post (here, 0V is to be applied to post 16); (b) knowing the desired current to flow through the selected memory element (here, 50 μA) given a particular resistance for that memory element (here, 10 KΩ) and, based on that desired current for that resistance, calculate the required voltage across memory element A-16 (here, 0.5V) to yield that current for that resistance; (c) having determined the voltage on the post (0.0V) and the voltage across the memory element (0.5V), calculate the voltage on row (A) at the selected post (here, 0.0V+0.5V=0.5V); (d) compute the resistance of the row (A) from the op-amp to the point on row (A) at the selected post (if each segment has a resistance of 0.2Ω, then the row (A) resistance is 0.2Ω×16 segments=3.2χ); (d) assuming that no current flows into any of the unselected elements on that row (i.e., all of the current that flows through the voltage element must therefore flow from the point on row (A) at the selected post to the op-amp), determine the voltage drop from the point on row (A) at the selected post to the op-amp (here, the drop is 50 μA×3.2Ω=0.160 mV); and finally, (e) determine the voltage necessary at the op-amp by adding the voltage drop along the length of the row (A) to the voltage on the row (A) at the selected post (here, 0.160 mV+0.5V=500.16 mV); and finally (f) continuing with the assumption that no current flows into any of the unselected elements on that row, determine the voltage on row (A) at each post using Ohm's Law for voltage dividers: if row (A) has a resistance of 0.2Ω per segment (between two posts or between post 1 and the op-amp) and a current of 50 μA, the voltage across any segment will be 10 μV and the voltage on row (A) at each post (1 through 16, respectively) will be 500.16 mV at the op-amp, 500.15 mV at post 1, 500.14 mV at post 2, and so forth until post 16 at which point the voltage will be 500.00 mV. Having calculated the voltages on row (A) at each post, these same voltages can be externally applied to the posts 1 through 15, respectfully, and no voltage potential will appear across any of the memory elements A-1 through A-15 and no current will flow from row (A) into any of the unselected posts (consistent with the assumption at (d)). The op-amp output value when all the unselected posts are floating is the same for when these calculated voltages are applied to each post. In FIG. 5 , the calculations for this example have been summarized in a table. The above example presumes that the resistance of (i.e., the value stored in) the targeted memory element (A-16) is element known to begin with. Since the resistance of the storage element (A-16) would not be known at the start of a read operation, the exact voltages to apply to the posts would not be known either to eliminate current flowing into any of the unselected posts (this will also be true when the correct resistance is assumed, but to a lesser extent, due to process variations, natural variations in the resistance of the memory element, device aging effects, and the like). However, if one assumed the state that the memory element was in (of its two possible states as would be the case with a single level cell (SLC) type of memory element), one could then calculate (as done above) the post voltages based on this assumption and predict the output value from the op-amp. If one assumed the correct memory element state, the output should be as predicted; if the prediction is incorrect, then the other memory element state could be concluded. During a write or erase operation, the additional complexity of voltage threshold and snapback on the memory element as described below, can occur, depending on the memory element characteristics. Note that when a post other than the left most (i.e., farther away from the op-amp than the selected post) is selected, all posts to the left of that selected post should be biased to that voltage computed to be on row (A) at the selected post point (in order to ensure that no currents are flowing in row (A) to the left of the selected post). To simplify the biasing of unselected posts to the left of the selected post, the voltage, V, at the + terminal of the op-amp could be adjusted downward such that the voltage on row (A) at the selected post will always be the same (however, this voltage adjustment is not required as other compensating calculations and adjustments could be made); this voltage adjustment simplifies the voltage calculations and settings (then the voltage to apply to all the posts to the left of the selected post will always be the same voltage as well). This downward adjustment should equal the voltage drop across the posts to the left of the selected post that would have occurred had the left most post been selected. In our example, if post 11 were now the selected post and grounded, there will be five unselected posts to the left of post 11, across each of which a voltage of 10 μV would have fallen if post 16 had been selected, so V should be adjusted down by 5×10 μV or a 50 μV downward adjustment. This will result in an adjusted V of 110 μV and the voltage on row (A) at post 11 will be 500.00 mV (the same voltage on row (A) at the selected post as was calculated when the selected post was post 16) and posts 12 through 16 would also be biased to 500.00 mV. With the voltage on row (A) at post 11 being 500.00 mV and all the unselected posts to the left of post 11 biased at 500.00 mV, it is clear that there will be no current flowing to the left of selected post 11. If, as was described for the voltage calculations for FIG. 2 , there is no current flowing from a given row to any of the unselected posts (i.e., the voltage on the row at each post was matched by the voltage applied to each respective post), there will be no current leaking into any of the unselected posts. On the other hand, if in calculating the voltages for FIG. 2 , the assumption of the resistance for the selected memory element were incorrect (i.e., one assumed the wrong resistance value), then the voltage on the row (A) at any given post would differ slightly from the voltage computed and applied to each unselected post and a small amount of current will leak from the row (A) into those unselected posts. This small leaking current, in total, could result in a current flow that approaches the current expected to be flowing through the selected memory element for the assumed resistance; if this occurs, this leaking current could cause a misread at the op-amp output. For example, if one assumed the lowest possible resistance value for the selected memory element and that assumption turned out to be wrong (e.g., the resistance value was actually the highest possible resistance value, and as a result, the voltage on the row (A) at the selected post would be loaded down much less than assumed), then the voltage on the row (A) at the selected post would be higher than assumed and the voltage on the row (A) at every unselected post would also be higher than assumed. Ideally, the voltage across an unselected memory element would be zero and no current will flow through the unselected element; in the next best case, the unselected elements would be in their highest resistance state such that, while not at zero current, the smallest current will flow through the unselected elements. In a worst case scenario, all of the unselected memory elements would be in their lowest resistance state resulting in the greatest current flowing into each unselected post (due to those slightly higher voltages at each unselected post). In FIG. 6 , the calculations for this example, in which the assumed resistance value for the selected memory element is incorrect, have been summarized in a table. As the number of posts in the circuit increases, the total of these leaking currents will also increase and as this total converges on the current expected to be flowing through the selected memory element for the assumed resistance, the margin for reading will be reduced. Several techniques can be considered for determining if the resistance assumed for the selected memory element was the correct assumption. The current flowing through the selected post could be measured to determine if that current is consistent with the resistance assumption. Alternatively, the current flowing through one or more (or the total through all) of the unselected posts could be measured to determine if current is or is not flowing to confirm whether or not the resistance assumption was correct. Alternatively, the opposite resistance value for the selected memory element could be assumed, (which would presumably be the correct resistance value causing the leaking currents to be greatly reduced or eliminated), and new voltages for the unselected posts could be computed and applied. In this latter case, the unselected post voltages could be stepped such that first the voltages corresponding to a low selected memory element resistance are applied and then the voltages corresponding to a high selected memory element resistance are applied. It should be noted that the leaking currents to the unselected posts can cause a shift in the voltage applied to those unselected posts if the impedance of the source of those voltages is large; this can become an issue with sneak paths when there is more than one layer in the array (e.g., a 3-D array) as will be discussed, below. Put another way, since the row has a finite resistance, there will be a voltage drop along the row from the op-amp row driver at the end of the row to the point along the row where it crosses the selected post that is sinking to ground and a graph of these voltages is shown in FIG. 7 . In this graph, the op-amp is on the right where V X is applied and the drop in that voltage is shown as the line extending from right to left having a downward slope to the selected post (shown by an upward pointing arrow below the x-axis). To the left of the selected post, this line is flat because there is no additional loading beyond the selected post. At the point of the selected post, the voltage across the information storage element is shown and is represented by the lighter gray bar where the height of the bar corresponds to the voltage across the element. [Note, the graph is representative of the voltages for the purpose of the present discussion but it does not represent actual scale.] The darker gray bar below the lighter gray bar represents the voltage on the post. The small dark bar represents the voltage slightly above ground corresponding to the selected post. Therefore, for all the unselected posts, the darker gray bar in the graph represents a voltage corresponding to the value experienced on the row at each post's respective crossing point and the small gray bar on top represents a voltage across the information storage element of approximately zero. It should be again noted that with a zero potential across the information storage element of each of the unselected posts, the resistance value of those information storage elements is inconsequential. To read the information storage element at the targeted location, V X is set as a function of the distance away from the end of the row to the selected post such that the read voltage (V R ) occurs on the row at the point of intersection of the row with the selected post (as well as at every point from that selected post to the end of the row away from the op-amp). If the selected post is closer to the op-amp (i.e., closer to the right end of the row) as shown in FIG. 8 , the applied voltage V X is correspondingly lowered such that V R remains at the same level. V X is determined using an assumption of the resistance value of the information storage element at the targeted memory cell. The slope of the line is a function of the resistance of the row and the current through that row and this current is a function of the resistance of the selected information storage element, among other things, and the information storage element has a range of resistance values—for a single level cell (SLC) this resistance value will be either high (about 100 KΩ to 1 MΩ) or low (about 10 KΩ). Since in the ideal case, the voltage across all of the unselected information storage elements is zero when the assumed resistance of the targeted information storage element is exactly right, those unselected elements could in theory have any resistance value from zero (a short circuit) to infinity (an opened circuit) because no current flows through them. But, if the actual resistance value for the targeted element is greater than the assumed resistance value, the actual voltage V R will be greater than the computed voltage V R (by how much greater is a function of the loading by the unselected elements, but V R will never be lower than the computed value). If actual voltage V R is much greater than the calculated voltage V R , then both the selected element must be higher than its assumed resistance value and the loading by the unselected elements must be low (i.e., the data bit state is known). However, if the actual voltage V R is about equal to the calculated voltage V R (leakage currents will typically keep the voltage from being exact), then either the selected information storage element is in the assumed resistance state or the selected element is in the opposite state but the unselected elements are heavily loading the row line (i.e., the data bit state is ambiguous). Since the unselected information storage elements are all biased by posts that are set to voltages that are equal to or greater than V R , then there must be significant loading and the current flowing through the unselected elements must be greater than when the current is only flowing through the selected element (when its resistance is as was assumed in which case no current would be flowing through the unselected elements—the data bit state, with the inclusion of a current measurement, is not ambiguous). Finally, when V X is close to V R (i.e., when the selected column is close to the op-amp end of the row), there can be little loading by the unselected elements and presence the current flowing would indicate that the selected element is in the assumed low resistance state as assumed. Within the 3-D array is a plurality of 2-D resistive arrays (a row-plane is a 2-D resistive array comprising rows on one dimension and posts on the other). One of the limiting mechanisms in a resistive array is sneak paths. In the present invention, sneak paths are addressed by controlling the voltage on the posts. FIG. 3 depicts a partial schematic showing a second row (B) and 16 posts. In this case, the same procedure is performed for reading both rows simultaneously. The post voltages are applied assuming both of the memory elements on any given post (one to row (A) and one to row (B)) are in a particular state and the op-amp outputs (as a function of the current flowing from each op-amp into its respective row and the feedback resistor as is well understood by those skilled in the art) would each be compared to the predicted voltage. A sneak path is a conductive path from one row (e.g., the row depicted in FIG. 2 ) to an adjacent row (e.g., this additional row added in FIG. 3 ) that would distort the voltage and/or current on that adjacent row. But, the only way one row can provide a sneak path to another row is via one or more of the posts. Sneak paths occur when nodes are allowed to float or are only weakly driven. If, on the other hand, the post is driven from a low impedance source (i.e., strongly driven relative to the potential loading from any of the rows), the ability for any given row to influence any other row by way of a sneak path through one or more posts is greatly limited. If a given memory element assumption is incorrect, leaking current will flow as described above to or from the unselected posts and this will cause the voltages on those posts to be shifted (i.e., increased or decreased, respectively). The extent of this voltage shift is a function of the impedance of the voltage sourced to the post. If the post (along with any voltage driving circuitry) has low impedance, the impact of the leaking current will be smaller than if the post has a high impedance. By minimizing the impact of the leaking currents by making the posts lower impedance, one will necessarily be minimizing the impact of the sneak paths. In other words, by driving/clamping every unselected post to its calculated voltage, the sneak path is substantially limited. This can be achieved by placing a current driving device at each post or by ensuring that the impedance of the post (and any circuitry to assert that voltage on that post) is much small than the impedance of the memory elements connected to that post (when they are at their worst case—lowest resistance—state). When there is no driving element, the number of layers will be reduced as dictated by this difference between the memory elements' impedance and the post's impedance. It should be noted that, since the posts are common to all of the layers (i.e., all of the rows), the voltage applied to the posts will be the same for all of the layers/rows. Since the voltage calculated for each unselected post is a function of the resistance value assumed for the selected memory element on the row, the same resistance must be assumed for the selected memory element between a selected post and each level (i.e., to each row) for a given set of computed unselected post voltages. With some resistance memory elements such as phase-change memory elements (comprising a Chalcogenide alloy material such as GST), once a threshold voltage across the memory element is exceeded, the element exhibits a snapback action and its resistance drops (in some cases to only 1000 to 2000 ohms or less). With a 3-5-5 GST material, this snapback occurs at approximately 1V. To program or erase such a memory element, the calculation outlined above would be repeated to determine the voltages along row (A) while assuming that the voltage across the selected memory element is to be the threshold voltage (e.g., 1.0V, or slightly greater, as opposed to the 0.5V in the above example) and that the resistance of the memory element is to be at its lowest resistance value prior to exhibiting snapback (in the example above, this resistance was 10 KΩ). If the assumption of the element's resistance is incorrect (i.e., the element's resistance is greater), the voltage across that element will be higher, but still less than the voltage calculated to be on the end of row (A) at the op-amp. When the voltage is applied and the element exhibits snapback, the resistance will drop and the voltage across the element will collapse while the current will increase. With the above example, the post 16 memory element of 10 KΩ at the threshold voltage of 1V (the current through the element would be 100 μA while the op-amp voltage would be have to be approximately 1.00032V) will snap to an approximate range of 2 KΩ (at 0.499 mA) to 1 KΩ (at 0.997 mA) and all of the voltages along row (A) would correspondingly drop. With an op-amp voltage of 1.00032V and a resistance per segment of 0.2Ω, the voltage on the row at post 1 and post 15 would be roughly 1.00022V and 0.99882V respectively, with each post point in between being determined according to Ohm's law. If the posts were biased to these after-snapback voltages, then each unselected memory element would have zero volts across it following snapback. In practice, the op-amp circuit could be designed to adjust these voltages automatically when snapback occurs while incorporating a current limiting and shaping circuit to provide the desired programming or erasing waveform, as is well understood by those skilled in the art of analog design. A reference voltage for each post can be generated from a resistive line (the reference line) having one end asserted at the op-amp voltage and a second point asserted at the selected post voltage at a point along its length proportional to the point along the length of the row to where the selected post is located. Voltage taps can then be drawn off this resistive line at points corresponding to each post. This resistive line would typically have a conductivity that is the same as one of the row lines or that is proportional to a row line (in this latter case, the tap points will be proportionally adjusted along this resistive line). A voltage follower can be utilized at each tap point having a high impedance input from the tap point, to minimize loading the tap on the reference line and distorting the voltages generated therein, and having a low impedance output to drive the voltage to the post, as depicted in FIG. 4 (with the reference line grounded by post 16 for when post 16 is selected). This will give the correct slope for the voltages across the line as well as an approximately close absolute reference voltage for each unselected post (noting that the absolute voltages must also allow for the voltage drop across the selected memory element and the selected post, but these voltage drops can be compensated for in the voltage follower design and it, along with its variations, will be clear to those skilled in the art). For the highest memory bit packing density, a vertically constructed switch or transistor (as are known in the prior art) in the base of each post is desired, where the circuit for generating the intermediate voltages from a reference line can be positioned at the edge of the 3-D array at the ends of the columns. When reading and erasing, all of the memory bits connected to the selected post are equals; that is to say, all the elements will be read or all the elements will be erased and all the elements can be treated equally. This also means that all of the reference voltages adjacent to the unselected posts will be the same on each layer. As a result, erasing can be performed similarly to reading in that one selected post will be pulled to ground and all of the rows will be raised to a voltage such that, when allowing for the voltage drop along the row as described above, the voltage across the selected memory element (bit) will be the desired erase voltage; the unselected posts will be biased accordingly so that the voltage across the unselected bits is at or near zero volts (0 v). When applying an erase pulse that is shaped (e.g., a pulse that ramps down over time), the input to the reference voltage generator must be likewise shaped so that the bias voltage on each unselected post will track the waveform on the row at each unselected post. However, during programming, this is not the case. When programming a memory cell, operation proceeds in the same manner, except that the voltage V R is increased to a programming voltage level, V P (see FIG. 9 as compared to FIG. 7 ). As is depicted in this graph, the voltage across the memory elements at the unselected columns remains small because the bias voltages on these unselected columns are correspondingly raised along with V P . (Note that FIG. 7 and FIG. 9 are not necessarily to scale, but they do reflect the greater programming voltage, V P .) During programming, some bits may need to be programmed while others may need to be left unchanged. When an erased bit is being programmed, the voltage V X applied to that row will be selected such that the voltage at the selected post will result in the programming voltage V P being applied across the memory element to be programmed. The unselected posts could be biased to those reference voltages that would put 0 v across each unselected memory element. However, if all of the unselected posts are biased such that there is 0 v across the unselected memory elements for a layer that is being programmed, since the post bias voltages are the same layer-to-layer, a different layer that is not being programmed and for which the row voltage, V P (or V P-bar ), is lower (e.g., a row voltage closer to the level used during reading—a voltage that will not cause the snapback threshold to be exceeded across the memory element at the selected post) would see a large reverse voltage across those memory elements. Alternatively, the post bias voltages could be set to those voltages used for reading and any row on which the memory element is not being programmed could be set to the voltage used when reading, then the voltage on the rows on which the memory elements are being programmed would be set higher (such that the programming voltage V P will be applied across the memory elements to be programmed), but this will put a high forward voltage across those unselected memory elements on the layers to be programmed. Both of these cases are acceptable as long as the voltages across the unselected memory elements in either case do not exceed the snapback threshold voltage (a write disturb will occur if the snapback voltage across an unselected memory element is exceeded). If a memory element material is used that requires a very large programming voltage V P or which has a very low snapback threshold voltage such that the application of the required programming voltage would cause the snapback threshold to be exceeded on any of the unselected memory elements, a different memory element material would have to be substituted. However, if between these two approaches (namely to bias the unselected posts for zero volts across the unselected memory elements connected to the layer being programmed or to bias the unselected posts for zero volts across the unselected memory elements connected the layer not being programmed, as just described above) the threshold voltage is not exceeded, on average, across the unselected memory elements, the unselected posts can be biased to voltages that fall between the voltage that would result in zero volts across the unselected memory elements on a layer being programmed and the voltage that would result in zero volts across the unselected memory elements on a layer not being programmed. Either of these voltages or any ones in between can be generated as described above with regard to FIG. 4 and the generation of the post biasing references voltages. The present invention is well suited for use as a three-dimensional resistive array. With a three-dimensional structured resistive array, each information storage element could be formed in series with a voltage threshold device such as an Ovonic Threshold Switch (OTS) to improve the noise margin. An alternative approach for reading is to apply the calculated post voltage to every post (including the post to be selected) and measure the output from the op-amp. Once this output value is sampled, the selected post is pulled to ground and the output (the result voltage) is compared to the sampled voltage. If this technique is combined with a resistance selection for the memory element assumption that is roughly the average of the possible high and low resistance values for that memory element, the result voltage will be greater than the sampled voltage for one bit state and lower for the other bit state. If more than two states are possible, such as with a multi level cell (MLC) type memory element, multiple assumptions could be tested during a read operation or this could be accomplished by ramping the assumed voltage for the selected post. At the start of an erase operation having a shaped erase pulse, the op-amps could continue to hold the rows to V potential and all posts could be brought to and held at V potential. Then a post could be lowered to a voltage that will cause the memory elements to erase which could include pulsing this voltage low and ramping it high as would be done with a GST type memory element. With this approach, all of the memory elements on that post will be erased simultaneously. Also, the reference voltages will be constant while the selected post would change according to the desired pulse shape. The impedance of the row lines with their respective op-amp drivers will determine how many posts can be operated simultaneously during an erase cycle and, as long as the rows and the unselected posts can be held high (or high enough to prevent the voltage across a memory element not being erased from exceeding the threshold voltage), more posts can be added to the erase operation. It should also be noted that if the impedance of the posts is too high, the current entering the post from a first row upon which an erase cycle is being performed can raise the voltage on that post and could impact the ability to place the necessary threshold voltage across the memory element connecting that post with a second row; as a result, to activate an additional row during an erase cycle, the voltage on that additional row may have to be shifted in order to ensure the necessary voltage potential is achieved across the additional memory element. Programming and erasing often utilizes higher currents and with some materials (such as GST) must exceed the material threshold. When the material threshold is exceeded (snapback), the resistance drops and the voltage across the material will collapse. This will result in higher currents in the circuit and lower voltages along the row line. Programming multiple bits at once can be difficult if one bit exhibits snapback (thereby causing the voltage across that bit to collapse and the voltages along the row to drop) ahead of other bits intended to be programmed at the same time. It is worthy to note that during a read operation the assumed resistance for a selected memory element can vary by a few orders of magnitude (e.g., with 3-3-5 GST, the high resistance can be on the order of mega-ohms whereas the low resistance can be as low as several kilo-ohms or a variability factor of as much as 1000×), during a write or erase operation this error is potentially much smaller (e.g., following snapback, the memory element will be in a single state—post-snapback—where the resistance is approximately one to two kilo-ohms or a variability factor of about 2×); in other words, during write and erase operations, the memory element is generally known whereas during read operations, a high or low resistance state must be assumed and this assumption, necessarily, will often be the wrong state. Also, Chalcogenide alloys such as 3-3-5 GST can be programmed by a narrow pulse (as short as roughly 10 nSec long) and erased by a long pulse (e.g., a few 100 nSec), but the amplitude of the long pulse can have as much as a 20% lower voltage. This is because the narrow pulse functions to melt the GST and, once melted, is terminated as quickly as possible so as to leave that memory element in a high resistance, amorphous state. The long pulse, however, is used to restore the crystalline state of the memory element and functions to anneal the material; as such, the voltage need not be so high as to melt the material, but rather just high enough to provide the energy necessary for the atoms in the material to move back to a crystalline state. Because of this difference in voltage amplitude of the two pulses, it will be desirable to reverse the purpose of these two pulses. Instead of using the long pulse with the lower voltage to erase the memory element and the short pulse with the higher voltage to program the memory element, one could relax the voltages required to individually program the bits of a resistive array by reversing the meaning of the pulses (i.e., using the short pulse with the higher voltage to erase the memory element and the long pulse with the lower voltage to program the memory element). While this will result in slower programming because of the use of the longer pulse, the voltages in the resistive array while programming will be lower thereby providing less chance that a memory bit connected to that post that is not being programmed (i.e., that should remain in the reset state) or that any other memory bit in the resistive array will suffer a write disturb (i.e., have its state be inadvertently changed). Erasing is then performed with the short, higher voltage pulse. But during an erase function, since all bits on a selected post are erased simultaneously, this higher voltage is less likely to cause any bit to be disturbed. The foregoing description of an example of the preferred embodiment of the invention and the variations thereon have been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be limited not by this detailed description.

The present invention is a means and method for constructing and operating a 3-D array and, more particularly, a 3-D memory array. This array can be manufactured as a monolithic integrated circuit at low cost by virtue of the limited number of steps per layer of memory elements. The low number of steps results by having the storage elements separated by a resistive component as opposed to an active component. The 3-D array is in essence, an array of 2-D resistive arrays (row-planes) having a long dimension (typically along the rows) and a short dimension (typically in the direction of the stacked layers). Any one row-plane can be isolated from the rest and be accessed independently from all of the other row-planes in the 3-D array. This makes it possible to operate and analyze a single row-plane as a mostly stand-alone circuit. The present invention lends itself to single bit accesses as well as simultaneous multiple bit accesses.

BACKGROUND OF THE INVENTION [0001] A. Field of the Invention [0002] The field of the present invention relates generally to structural building materials and systems for utilizing the same, specifically such building materials that are made out of concrete but are manufactured to resemble wood boards or stone and systems for installation of the same. More specifically, this invention relates to building materials that are made out of concrete boards that have an appearance similar to standard wood or stone products which are joined together with connectors. [0003] B. Background [0004] Although the apparatus of the present invention is suitable for use with a number of different structures, the discussion in this disclosure will focus on the use of the present invention as a structural material for decking. It is well known that wood and stone are commonly used as building materials to construct a large variety of structures, including backyard decking. Many people prefer wood or stone due to its natural appearance and feel. As a decking material, however, wood does have a number of disadvantages. These disadvantages include the need for preservatives and coatings to protect the wood from exposure to sun, rain and other weather elements. Failure to place these materials on the wood decking when constructed will substantially shorten the structure's life and result in a decking of unsatisfactory appearance after a relatively short time period. In addition to the initial coating of the preservatives, the owner of the decking must ensure that it is properly treated over varying intervals of the life of the decking. Failure to properly maintain the decking will also result in a much shorter life for the decking and decking that is of undesirable appearance. The care of the wood decking requires both an investment in money and time. Stone materials also have a number of disadvantages when used as a decking material. The primary disadvantage has to do with limitations on the size and placement of the stone materials [0005] In addition to the care requirements for wood materials set forth above, many people are turning away from wood where acceptable substitutes are available for environmental reasons. The most common wood material used for decking and the like is redwood and cedar. Both these materials are becoming generally less available and, as a result, more expensive to be used as structural materials in relatively large structures (such as decking). In addition, the primary system available for placing these materials in their proper positions are the use of nails, screws and/or bolts of various types. These connectors generally result in the heads or tops of the connectors being visible and, often, protrusions above the surface of the deck or other structure. [0006] A number of different materials have been developed to be used as a structural material in place of wood or stone. These materials include various plastics, metals and concrete. In general, these materials are not utilized as much as standard wood or stone products. The lack of use is primarily due to the less attractive appearance and feel of these materials. In addition, the systems available for installation of these materials are typically less than satisfactory. Recent developments in the use of plastic composites have added a new material that can be used for decking and other structures. The plastic composites are generally manufactured out of a concrete resin, such as recycled polyethylene, and waste wood fibers. The plastic and wood fibers are mixed together and then formed into board-shaped or stone-shaped structural materials that are used for decking and other structural needs as a replacement for wood boards or stone. The use of plastics for building materials has a number of disadvantages, such as the petroleum products from which it is made, the expense and difficulty in making the product and the susceptibility of plastic to damage from the weather elements. [0007] What is needed is a structural material that can serve as a replacement for wood and stone and be used in place of wood and stone for constructing various structures, such as decking. To successfully replace the wood and stone products, the structural material must have the ability to be shaped as a wood member (i.e., a board) or a stone slab, be able to have a color added to it and be durable and weather resistant. A more preferable connector for installing these materials is also needed so as to provide a more secure and attractive system. SUMMARY OF THE INVENTION [0008] The above-grade concrete decking system of the present invention provides the benefits and solves the problems identified above. That is to say, the present invention discloses a building system that can be used in place of wood and stone building materials, is easy to manufacture, durable and relatively maintenance free. The system used to install the subject building material provides a stable structure, such as a decking, that is easy to install and provides a long life structure. [0009] In its broadest form, the primary embodiment of the present invention comprises a plurality of adjoining deck members overlying a plurality of spaced apart joists that are connected together with a clip member shaped and configured to hold the deck members to the joists. The plurality of deck members comprises at least a first deck member and a second deck member on top of the plurality of spaced apart joists. Each of the deck members has a first side and an opposing second side, a top surface and a bottom surface. At least one of the opposing sides of each deck member has a slot therein. The slot can either be a single slot that runs the length of the deck member or it can be a series of slots that are spaced apart an amount equal to the spacing of the joists. The clip member has at least a base portion, a vertical portion and an insert portion. The various components of the clip member are sized and configured such that the insert portion is disposed in the slot when the base portion is disposed between the bottom surface of the deck member and the joist and the vertical member is disposed between the adjoining deck members. The deck members can be a concrete composite material shaped and configured into a board member that simulates a natural wood finish or shaped and configured into a stone member that simulates a natural stone material. [0010] In one specific configuration, the deck system utilizes a adjoining deck members that have slotted sides that face each other and are intended to abut each other in the finished form. The insert portion of the clip member has extensions that extend away from the vertical portion of the clip member in opposite directions such that the insert portions are disposed in the slots in the opposing sides of the adjoining deck members. To further improve the stability of the decking system, an adhesive can be used between the deck members and the joist. In addition, the base portion of the clip member should have at least one opening therein that is configured to receive a connector, such as a nail, screw, bolt or other connector, to secure the clip member base portion to the joist. [0011] Instead of utilizing slots in the deck members, one embodiment of the present invention utilizes deck members that are shaped and configured to fit together with the clip member (and if desired adhesive material) between the deck members or between the deck members and the joist. In another embodiment, the deck members fit together and include a slot in at least one of the deck members so as to receive the insert portion of the clip member. [0012] Accordingly, the primary objective of the present invention is to provide an above-grade decking system that securely connects the surface deck members to the underlying joists without the need for connectors going through the top of the deck members. [0013] It is also an important objective of the present invention to provide an above-grade decking system that utilizes shaped clip members that are used to secure deck members to underlying joists. [0014] It is also an important objective of the present invention to provide an above-grade decking system that is suitable for securing deck members made out of concrete composite materials, which are shaped into looking like wood or stone products, to joists. [0015] It is also an important objective of the present invention to provide an above-grade decking system that utilizes decking members shaped and configured to fit together with a clip member therebetween. [0016] The above and other objectives of the present invention will be explained in greater detail by reference to the figures and the description of the preferred embodiment which follows. As set forth herein, the present invention resides in the novel features of form, construction, mode of operation and combination of parts presently described and understood by the claims. BRIEF DESCRIPTION OF THE DRAWINGS [0017] In the drawings which illustrate the best modes presently contemplated for carrying out the present invention: [0018] [0018]FIG. 1 is a perspective view of a deck utilizing board members made out of the concrete material and utilizing the system described herein; [0019] [0019]FIG. 2 is a side view of the connector shown in FIG. 1; [0020] [0020]FIG. 3 is a top view of the connector in FIG. 2; [0021] [0021]FIG. 4 is a side view of an alternate embodiment of the connector shown in FIGS. 2 and 3; [0022] [0022]FIG. 5 is a perspective view of the use of a deck portion utilizing stone slabs and a connector of the present invention; [0023] [0023]FIG. 6 is a perspective view of the connector illustrated in FIG. 5; [0024] [0024]FIG. 7 is a side view of an alternative embodiment of the present invention; and [0025] [0025]FIG. 8 is a side view of an alternative embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0026] With reference to the figures where like elements have been given like numerical designations to facilitate the reader's understanding of the present invention, the preferred embodiments of the present invention are set forth below. The enclosed figures and drawings are merely illustrative of the preferred embodiments and represent several different ways of configuring the present invention. Although specific components, materials, configurations and uses are illustrated, it should be understood that a number of variations to the components and to the configuration of those components described herein and in the accompanying figures can be made without changing the scope and function of the invention set forth herein. [0027] An above-grade concrete decking system manufactured out of the materials and pursuant to the system of the present invention is shown generally as 10 in FIGS. 1, 5, 7 and 8 . As shown in FIG. 1, a typical decking system 10 has a plurality of adjoining deck members 12 , comprising at least a first deck member 12 a and a second deck member 12 b in the shape of board members (i.e., wood boards) or stone material (i.e., stone slabs), positioned above and attached to a plurality of spaced apart joists 14 (one of which is shown) that support deck members 12 to form deck 10 . Deck members 12 , having first side 13 a, opposing second side 13 b, top 13 c and bottom 13 d, are typically made out of wood. As discussed above, deck members 12 can be made out of a concrete composite material, such as concrete mixed with plastic, sawdust or other materials that is then formed into a board shape (i.e., a two-by-four) member 12 . Generally, the outer surfaces of the composite deck members 12 are contoured and configured to resemble natural wood or stone products. The builder of deck 10 obtains sufficient quantity of deck members 12 to cover the area where the deck 10 is to be placed. Typically, a deck 10 made out of wooden deck members 12 utilizes nails, screws or bolts to connect deck members 12 to joist 14 by driving or placing the connectors through the individual deck members 12 into joist 14 . With composite board-shaped members 12 , however, this is typically not possible or practical. Instead, a layer of adhesive (shown as 16 in FIG. 1) is placed on top of joist 14 or the bottom 13 d of deck member 12 so as to be between the deck members 12 and the joist 14 . The adhesives for use with the present invention are well known in the industry and commonly known. The deck members 12 are then placed on the adhesive 16 and are left to dry or cure. The integrity of the decking system for concrete composite members utilizing the system of installation of the prior art relies on the ability of the adhesive 16 to sufficiently bond deck members 12 to joist 14 . Unfortunately, this bond often weakens as the wood framing expands and contacts over time, resulting in deck members 12 becoming loose. The loosening of deck members 12 requires repair or replacement of deck 10 . [0028] To improve the integrity of a deck 10 utilizing deck members 12 made out of composite materials, the present invention utilizes a plurality of clip members 18 to mechanically attach deck members 12 to joist 14 . As shown in FIG. 1, clip members 18 are utilized between adjoining deck members 12 and between deck members 12 and joist 14 . As shown in FIGS. 2 and 3, one configuration for clip member 18 is the use of an elongated base portion 20 , vertical portion 22 and one or more insert portions 24 (FIG. 2 shows the use of two opposite facing insert portions 24 a and 24 b ). Base portion 20 can include a hole 26 , sized for a nail, screw, bolt or other connector 30 , for use in attaching clip member 18 to joist 14 . Alternatively, base portion 20 of clip member 18 can include an integral attachment or connector portion (shown in FIG. 4 as 27 ) protruding downward from base portion 20 that is suitable for attachment to joist 14 . If a flush surface is desired for base portion 20 , hole 26 can be contoured such that the top of the connector 30 (i.e., the head of a nail) will be flush with base portion 20 after it is driven or placed through joist 14 . [0029] In use, insert portion 24 ab of clip member 18 is inserted into a slot 28 located on side 13 b of first deck member 12 a already in place on joist 14 such that vertical portion 22 abuts against side 13 b of deck member 12 a. Slot 28 can extend the entire length of the deck members 12 or be spaced a distance apart approximately equal to the spacing of the joists 14 . A nail or other connector 30 is inserted through hole 26 and into joist 14 . An adjoining second deck member 12 b is placed along side the first deck member 12 a such that insert portion 24 b extends into slot 28 and the bottom 13 d of the second deck member 12 is over base portion 20 . First side 13 a of second deck member 12 b can either abut vertical portion 22 of clip member 18 and second side 13 b of the first deck member 12 a or a gap can be provided between the two deck members 12 a and 12 b so that grout material can be placed therebetween. The deck member 12 on the outer edge of deck 10 placed on joist 14 can either use a modified clip member 18 having only a single facing insert member 24 b (i.e., a C-shaped clip member) or a clip member 18 with one portion of the insert member 24 a broken off. The deck system 10 of the present invention using clip member 18 can also be utilized with adhesive layer 16 to provide a deck system which has deck members 12 even more securely attached to joist 14 . The use of adhesive 16 also provides a cushioning effect for clip members 18 , even after the adhesive 16 loosens over time from the natural expansion and contraction of the wood joist 14 . Clip members 18 are placed between each deck member 12 at every joist 14 that make up the complete deck 10 . [0030] Clip member 18 can be made from a variety of materials having a variety of sizes and configurations. One material found suitable for this purpose by the inventor is 0.060 ({fraction (1/16)}″) gauge galvanized metal. For ease in manufacturing, clip member 18 can be made from a generally rectangular piece of metal that is cut to form the separate insert portions 24 a and 24 b and then bent at the appropriate places to form base portion 20 , vertical portion 22 and insert portions 24 . In one configuration, the inventor has found that an insert portion 24 a and 24 b of one-fourth to one-half inch width is sufficient to provide the needed support to anchor deck members 12 to joist 14 . Alternatively, clip member 18 can be configured to different sizes and/or shapes. One such alternative, shown in FIG. 4., uses an oval-shaped insert portion 32 . Alternatively, insert portion 32 can be rectangular or otherwise shaped to fit into slot 28 of deck members. If a different configuration for clip member 18 is to be used, the configuration of slot 28 could be modified to best match clip member 18 to ensure clip member 18 provides the mechanical support desired. [0031] Another embodiment of the above-grade decking system of the present invention is shown in FIG. 5. In this embodiment, deck 10 has a plurality of adjoining deck members 12 , comprising at least a first deck member 12 a and a second deck member 12 b in the shape of wood or stone materials, that are attached to joist 14 with an adhesive layer 16 and a clip member 36 . The use of adhesive 16 alone with the deck members 12 has the same problems described above (i.e., they loosen over time). Clip member 36 is made out of the same materials as clip member 18 and comprises a base portion 38 , vertical portion 40 and insert portion 42 . Located on base portion 38 can be a hole 44 , which can be contoured as discussed above, for allowing connector 30 (i.e., a nail) to be attached to joist 14 . The use of an adhesive layer 16 with clip member 36 provides integrity support and a the cushioning effect described above. One configuration for clip member 36 is a 1″ base portion 38 , ⅝″ vertical portion 40 and ½″ insert portion 42 . [0032] In use, clip member 36 is placed between adjacent deck members 12 a and 12 b, which are placed on a layer of adhesive material 16 , such that insert portion 42 b is on top of lower extension 46 of second deck member 12 b. A nail 30 or other connector is driven through hole 44 in base portion 38 and into joist 14 to mechanically connect deck member 12 b to joist 14 . The first deck member 12 a is placed adjacent to the second deck member 12 b such that the bottom of first deck member 12 a is placed on top of base portion 38 and its side abuts vertical portion 40 . Insert portion 42 a extends into slot 28 on deck member 12 a and the upper extension 48 of deck member 12 a is placed on top of insert portion 42 b. In some installations, it is preferable that upper extension 48 does not abut the adjacent deck member 12 b so that gap 50 is created for placement of grout between the deck members. Alternatively, deck members 12 a and 12 b can abut each other. The above procedure is repeated throughout the joists 14 and deck members 12 used to form deck 10 . [0033] Another alternative configuration for the present invention, shown in FIG. 7, a plywood member 52 , or other types of wood material, disposed between deck members 12 and joist 14 to reduce the overall weight of the deck 10 (by utilizing thinner deck members 12 ). A connector 36 , held in place with nail 30 that goes through plywood member 52 into joist 14 , provides mechanical support to deck members 12 . As with the embodiments described above, an adhesive (not shown) can be used between deck members 12 and plywood 52 and/or between plywood 52 and joist 14 . [0034] Another embodiment of the present invention is illustrated in FIG. 8. In this embodiment, the adjoining deck members 12 a and 12 b are shaped and configured to fit together with a clip member 54 that is shaped to take advantage of the deck members 12 fitting together. Each deck member 12 has a protruding segment 56 on one side (i.e., first side 13 a ) and a recessed segment 58 on the opposite side (i.e., second side 13 b ), as shown in FIG. 8. The protruding segment 56 is shaped and configured to be received into the recessed segment 58 when the two adjoining deck members 12 a and 12 b are placed side by side. The clip member 54 has an insert portion 60 that comprises a single portion that extends the opposite side of vertical member 62 as the base portion 64 (forming a s-like shape) that is configured to be inserted between the protruding segment 56 of one deck member 12 a and the recessed segment 58 of the adjoining deck member 12 b. [0035] Although the deck system 10 of the present invention works best for composite concrete materials shaped and configured to resemble wood or stone products, due to the weight of the material bearing down on the joists, it can also be utilized with wood members. For instance, deck members 12 made out of wood can be cut on the sides to form the slots 28 shown in FIG. 1 so the clip member 18 can be utilized with the deck 10 . The advantage of utilizing the present system 10 over traditional mechanisms for connecting deck members 12 to joists 14 is the elimination of the nail head, or equivalent top of connector 30 , from being visible from and extending above top surface 13 c of deck 10 . [0036] While there are shown and described herein certain specific alternative forms of the invention, it will be readily apparent to those skilled in the art that the invention is not so limited, but is susceptible to various modifications and rearrangements in design and materials without departing from the spirit and scope of the invention. In particular, it should be noted that the present invention is subject to modification with regard to the dimensional relationships set forth herein and modifications in assembly, materials, size, shape, and use. For instance, there are numerous components described herein that can be replaced with equivalent functioning components to accomplish the objectives of the present invention. One such modification is the use of different materials than those set forth herein. Another modification would be a change in the dimensional characteristics of the various components.

An above-grade decking system having a plurality of deck members overlying a plurality of joists with clip member connectors connecting the deck members to the joists. The present decking system is particularly adapted for use with concrete composite materials that are shaped into construction materials and testured to resemble wood or stone products. The clip members are shaped to hold the deck memebers onto the joists. The clip members fit into slots in the deck memebers and are attached to the joists using commonly available connectors. The deck memebers can be shaped and configured to fit together with the clip memebers therebetween.

BACKGROUND [0001] This invention relates to a method of preparing a composite article and to an adhesive composition useful for forming such composite articles. In particular, the method of this invention includes applying a layer of an adhesive composition to a substrate, drying that layer or allowing it to dry, and contacting that layer with at least one other substrate. Composite articles are prepared by bonding two or more substrates together with an interposed adhesive composition. Substrates may be the same or different. The composite articles desirably have good adhesive strength; that is, the polymeric adhesive composition must adhere well to the substrates and be resistant to forces that lead to separation. [0002] In some cases, the applied adhesive composition contains a solvent or other fluid, which, after application of the adhesive composition to a substrate, is allowed to evaporate; sometimes, evaporation is enhanced or speeded by the application of heat and/or forced gas flow. Often, curing (i.e., desirable chemical reactions that are thought to increase the strength of the adhesive and/or its ability to bond to substrates) takes place during or after the drying and/or heating process. In some cases, these chemical reactions form crosslinks between polymers. [0003] One approach to providing adhesive compositions is found in U.S. Pat. No. 5,578,683, which discloses pressure-sensitive adhesives containing graft copolymers that have crosslinkable macromonomers as polymerized units. Crosslinkable macromonomers are specialty materials that are potentially difficult to purchase and/or manufacture. An object of the present invention is to provide curable adhesive compositions that do not require such specialty materials. STATEMENT OF THE INVENTION [0004] In a first aspect of the present invention, there is provided an adhesive composition comprising: (a) 10% to 90% fluid medium, by weight based on the weight of said adhesive composition, and (b) 10% to 90% at least one acrylic polymer composition, by solid weight based on the weight of said adhesive composition, wherein said acrylic polymer composition comprises as polymerized units: (i) at least one monomer with carboxyl functionality, and (ii) at least one carboxyl-reactive monomer, wherein said carboxyl-reactive monomer has molecular weight less than 800. [0009] In a second aspect of the present invention, there is provided a method for bonding substrates comprising: applying a layer of an adhesive composition to a substrate; drying or allowing to dry said layer of said adhesive composition; and contacting at least one subsequent substrate to said layer of said adhesive composition, wherein said adhesive composition comprises: (a) 10% to 90% fluid medium, by weight based on the weight of said adhesive composition, and (b) 10% to 90% at least one acrylic polymer composition, by solid weight based on the weight of said adhesive composition, wherein said acrylic polymer composition comprises as polymerized units: (i) at least one monomer with carboxyl functionality, and (ii) at least one carboxyl-reactive monomer, wherein said carboxyl-reactive monomer has molecular weight less than 800. DETAILED DESCRIPTION [0014] The practice of the present invention involves the use of compositions that contain an acrylic polymer composition and a fluid medium. As used herein, “fluid medium” means a fluid that forms a continuous phase and that bears the acrylic polymer composition in a distributed form such as a solution, dispersion, or combination thereof. By “fluid” is meant a liquid with viscosity of 20 Pa·s (20,000 cps) or less at 25° C., as measured by standard methods, for example using Brookfield viscometer model DVI with a #25 spindle. In some embodiments, the fluid medium will be aqueous, which means herein that the fluid medium contains water in the amount of 50% or more by weight, based on the weight of the fluid medium; among aqueous media, preferred is water in the amount of 80% or more. [0015] As used herein, “solid weight” of a material refers to compositions in which a material that is a polymer and/or that is a solid at 25° C. is dissolved and/or suspended in a fluid; the “solid weight” of such a material is the weight that material would have if it were isolated from the composition; the solids weight of that material in a composition is independent of the amount of fluid present in the composition. [0016] As used herein, “acrylic polymer composition” means a composition that contains one or more acrylic polymers. If two or more acrylic polymers are used, they may be the same or different. As used herein, “acrylic polymer” means a polymer that contains 25% or more by weight, based on the weight of the polymer, (meth)acrylic monomers as polymerized units. “(Meth)acrylic monomers” herein mean monomers with at least one functional group that is either acrylic or methacrylic. Similarly, “(meth)acrylate” herein means either acrylate or methacrylate. (Meth)acrylic monomers include acrylic acid, methacrylic acid, their esters, their amides, and derivatives thereof. [0017] In preferred embodiments of the present invention, the acrylic polymer is not polymerized in the presence of resins or polymers that are not acrylic polymers. For example, preferred acrylic polymers of the present invention are not polymerized in the presence of tackifier resin or in the presence of epoxy resin. [0018] As used herein, “polymerized units” refers to monomers that are polymerized to form a polymer. That is, when certain monomers are used to form a copolymer, those monomers are said to be included as polymerized units in that polymer. If that polymer is then mixed with a different polymer to form a polymer composition, the polymer composition is said to include those same certain monomers as polymerized units. [0019] Some acrylic monomers suitable for inclusion as polymerized units in the acrylic polymer composition of the present invention are, for example, (meth)acrylic acid and alkyl (meth)acrylate esters wherein the ester group consists of a linear, branched or cyclic alkyl group with 1 to 70 carbon atoms. Some preferred alkyl (meth)acrylate esters are those with alkyl groups of 1 to 8 carbon atoms; more preferred are those with 1 to 4 carbon atoms. [0020] Other suitable (meth)acrylic monomers are, for example, aryl (meth)acrylate esters, halogenated alkyl or aryl (meth)acrylate esters, other (meth)acrylate esters, substituted and unsubstituted (meth)acrylamides, (meth)acrylonitriles, derivatives thereof, or mixtures thereof. Also suitable are multiethylenically unsaturated monomers, such as, for example, di-, tri-, and tetra-(meth)acrylates. Also suitable are (meth)acrylate monomers with attached functional groups such as, for example, ethylenic unsaturation, epoxide or glycidyl groups, isocyanate groups, other reactive groups, combinations thereof, and mixtures thereof. [0021] Some suitable (meth)acrylic monomers include, for example, methyl acrylate, ethyl acrylate (EA), propyl acrylate, isopropyl acrylate, n-butyl acrylate (BA), isobutyl acrylate, secondary butyl acrylate, t-butyl acrylate, pentyl acrylate, neopentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate (EHA), decyl acrylate, isodecyl acrylate, lauryl acrylate, bornyl acrylate, isobornyl acrylate, myristyl acrylate, pentadecyl acrylate, stearyl acrylate and the like; methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, hexyl methacrylate, octyl methacrylate, isooctyl methacrylate, decyl methacrylate, isodecyl methacrylate, lauryl methacrylate, bornyl methacrylate, isobornyl methacrylate, myristyl methacrylate, pentadecyl methacrylate, stearyl methacrylate, phosphoethyl methacrylate and the like; and itaconic acid, fumaric acid, and the like. [0022] Acrylic polymer compositions of the present invention may include as polymerized units, in addition to (meth)acrylic monomers, other monomers such as, for example, styrene, substituted styrene, vinyl acetate, olefins including ethylene, dienes including butadiene, vinyl chloride, sodium styrene sulfonates, sodium vinyl sulfonates, maleic acid, maleic anhydride, derivatives thereof, or mixtures thereof. [0023] In some embodiments of the present invention, one or more of the acrylic polymers in the acrylic polymer composition will be dissolved in the fluid medium. In some embodiments, one or more of the acrylic polymers in the acrylic polymer composition will be dispersed in the fluid medium as a dispersion. “Dispersion” herein includes, latex, emulsion, suspension, other dispersed forms, or combinations thereof. In some embodiments, some acrylic polymer molecules will be dissolved while others will be dispersed, and in some embodiments some acrylic polymer molecules will be partly dissolved and partly dispersed. All combinations of solution and dispersion, and all forms of dispersion, are contemplated for use in the present invention. Preferred are solutions, latices, and combinations thereof. Latex polymers (also known as “emulsion polymers”) are polymers made by the process of emulsion polymerization. [0024] The acrylic polymer composition of some embodiments of the present invention will contain one or more macromonomers as polymerized units. Macromonomers are low molecular weight polymers having at least one functional group at the end of the polymer chain that is capable of further polymerization, when exposed to polymerization conditions, with itself or with other monomers (i.e., is capable of forming a polymer of itself and/or capable of forming a copolymer of itself with other monomers). By “low molecular weight” is meant that the macromonomer has a degree of polymerization from about 10 to about 1,000, preferably from 20 to 200. By “degree of polymerization” is meant the number of polymerized monomer units present in the macromonomer. Typical macromonomers will have molecular weights of 800 to 200,000. In some embodiments, the polymerizable group at the end of the macromonomer is ethylenic unsaturation, the other monomers also contain ethylenic unsaturation, and the copolymerization is a free radical copolymerization. Some suitable methods of making macromonomers and of copolymerizing them with other monomers are disclosed in WO0222689. The monomers suitable for use in making acrylic polymers are also suitable for making macromonomers. [0025] In some embodiments of the present invention, macromonomers are not included as polymerized units in the acrylic polymer composition. In embodiments where macromonomers are included, a preferred amount of macromonomer is 0.1% or more by weight based on the solid weight of the acrylic polymer composition; more preferred is 1% or more; still more preferred is 4% or more. Also, in embodiments where macromonomers are included, a preferred amount of macromonomer is 20% or less by weight based on the solid weight of the acrylic polymer composition; more preferred is 10% or less; still more preferred is 7% or less. [0026] The acrylic polymer composition of the present invention contains, as polymerized units, monomers with carboxyl functionality. Suitable monomers will have one or more carboxyl groups, or they will have groups such as anhydrides that readily form carboxyl groups. Suitable monomers with carboxyl functionality include, for example, (meth)acrylic acid, (meth)acryloxypropionic acid, itaconic acid, aconitic acid, maleic acid or anhydride, fumaric acid, crotonic acid, monoalkyl maleate, monoalkyl fumarate, monoalkyl itaconate, similar acid monomers, and mixtures thereof. The alkyl groups suitable for use in the monoalkyl esters listed above are C 1 -C 8 linear, branched, or cyclic alkyl groups, including, for example, ethyl, methyl, and butyl groups. Also suitable for use as monomers with carboxyl functionality are macromonomers that contain, as polymerized units, suitable monomers with carboxyl functionality. Preferred monomers with carboxyl functionality are acrylic acid; methacrylic acid; macromonomers containing acrylic acid and/or methacrylic acid as polymerized units; and mixtures thereof. [0027] The amount of monomer with carboxyl functionality, in some embodiments, will be 0.1% or more by weight based on the solid weight of the acrylic polymer composition; preferred is 0.2% or more; more preferred is 0.5% or more; even more preferred is 1% or more; and most preferred is 1.4% or more. The amount of monomer with carboxyl functionality, in some embodiments, will be 20% or less by weight based on the solid weight of the acrylic polymer composition; preferred is 15% or less; more preferred is 10% or less, and most preferred is 5% or less. [0028] Also included in the acrylic polymer composition of the present invention are polymerized units of at least one carboxyl-reactive monomer. As used herein, “carboxyl-reactive monomer” means a monomer that contains at least one carboxyl-reactive group, which is a reactive group capable of reacting with carboxyl functionality. Without limiting the invention to any specific mechanism, it is contemplated that while the acrylic polymer composition is dissolved and/or dispersed in the fluid medium, the carboxyl functionality and the carboxyl-reactive groups will not react to any substantial extent. It is further contemplated that when the fluid medium is removed by drying, heating, and/or other means, the carboxyl-reactive groups will react with the carboxyl functionality to provide crosslinking, which is thought to improve the strength and/or adhesion of the adhesive. [0029] Any carboxyl-reactive group that is capable of reacting with carboxyl functionality and that can be attached to a monomer capable of use as a polymerized unit in an acrylic polymer is suitable for use in the present invention. Suitable carboxyl-reactive groups include, for example, isocyanate groups, glycidyl groups, acetoacetate groups, acetoacetamide groups, and mixtures thereof. In some embodiments, the carboxyl reactive monomer will have one carboxyl-reactive group. In other embodiments, the carboxyl reactive monomer will have more than one carboxyl-reactive group. Some suitable monomers that are capable of inclusion as polymerized units in acrylic polymers and that have suitable carboxyl-reactive groups include, for example, urethane (meth)acrylates with available isocyanate groups, other (meth)acrylates with available isocyanate groups, glycidyl (meth)acrylate, vinyl acetoacetate, acetoacetoxyalkyl (meth)acrylates, allyl acetoacetate, 2,3-di(acetoacetoxy)alkyl (meth)acrylates, vinyl acetoacetamide, acetoacetoxyalkyl (meth)acrylamide, substituted versions thereof, and mixtures thereof. The alkyl groups suitable for use in the carboxyl-reactive monomers listed above are C 1 -C 8 linear, branched, or cyclic alkyl groups, including, for example, ethyl, methyl, and butyl groups. Preferred carboxyl-reactive monomers are acetoacetoxyethyl (meth)acrylate, glycidyl (meth)acrylate, and mixtures thereof; more preferred is glycidyl methacrylate. [0030] The carboxyl-reactive monomer is a macromonomer in some embodiments of the present invention. Preferred are embodiments in which the carboxyl-reactive monomer is not a macromonomer. The carboxyl-reactive monomers of the present invention preferably have molecular weight of 800 or less; more preferably 500 or less; and even more preferably 250 or less. [0031] The amount of carboxyl-reactive monomer, in some embodiments, will be 0.05% or more by weight based on the solid weight of the acrylic polymer composition; preferred is 0.1% or more; more preferred is 0.2% or more; even more preferred is 0.4% or more; and most preferred is 0.5% or more. The amount of carboxyl-reactive monomer, in some embodiments, will be 10% or less by weight based on the solid weight of the acrylic polymer composition; preferred is 5% or less; more preferred is 2% or less; and most preferred is 1% or less. [0032] The acrylic polymer composition of this invention will typically have one or more glass transition temperatures (Tg's) as measured via differential scanning calorimetry. Preferably, all Tg's are in the range from −100° C. to +50° C. If the intended use of the adhesive composition is as a pressure-sensitive adhesive, at least one Tg is preferably in the range from −70° C. to −10° C., more preferably, −70° C. to −35° C. If the intended use is wet/dry bond laminating adhesive, at least one Tg is preferably in the range from −50° C. to +50° C., more preferably, −30° C. to +25° C., still more preferably, −10° C. to +10° C. If the intended use is a heat seal adhesive, at least one Tg is preferably in the range from −20° C. to +50° C., more preferably, +10° C. to +30° C.; additionally, the modulus for heat seal adhesives is preferably approximately 3×10 dyne/cm 2 at temperatures in the range from 25° C. to 100° C. If the intended use is as a cold seal adhesive, at least one Tg is preferably in the range from −100° C. to +10° C., more preferably −80° C. to 0° C. [0033] In some embodiments, the acrylic polymer composition used in the adhesive composition of the present invention contains one or more polymers prepared by emulsion polymerization techniques well known in the art. The emulsion polymer or polymers may be formed from any monomer or mixture of monomers which yields a water-insoluble latex, film-forming polymer. It is contemplated that in some embodiments, the adhesive composition will be heated during drying and/or during the process of bonding substrates together. The polymer is considered herein to be “film forming” if it is capable of forming a film at 20° C. or at the highest temperature to which it will be exposed during drying and/or during the process of bonding substrates together. [0034] The molecular weight of the emulsion polymer may be adjusted through the addition of a chain transfer agent, such as n-dodecyl mercaptan, during emulsion polymerization to give a suitable balance of adhesive and cohesive strength. [0035] The adhesive composition can contain conventional adhesive adjuvants such as, for example, tackifiers, emulsifiers and wetting agents, crosslinkers, monomers, oligomers, polymers, solvents or plasticizers, buffers, neutralizers, thickeners or rheology modifiers, biocides, antifoaming or defoaming agents. Preferred are compositions without any substantial amount of crosslinker. By “crosslinker” is meant herein a compound that is not one of the acrylic polymers of the present invention and that is capable of reacting with certain polymers to form crosslinks. In particular, preferred embodiments of the present invention do not contain amine compounds, other than small amounts (1% or less by weight, based on the solid weight of the adhesive composition) that may be used in the polymerization process; more preferred is 0.5% or less; most preferred is 0.1% or less. [0036] Some adhesive compositions are one-pack systems and some are multi-pack systems. One-pack systems are compositions for which all the ingredients are added to a single container, which can then be stored for a relatively long time without losing any desirable properties; after storage it can be removed from that container and applied to a substrate without addition of further ingredients. Multi-pack systems are compositions which, in order to retain their useful properties, must be stored in two or more separate containers; the contents of the containers are mixed together a relatively short time before the mixture is applied to a substrate. Multi-pack systems are typically employed when the ingredients are designed to undergo a chemical reaction immediately after the packs are mixed. Adhesive compositions that are either one-pack or multi-pack systems may be used in the practice of the present invention; one-pack systems are preferred. [0037] In one-pack embodiments of the present invention, the polymers, monomers, and reactive groups would preferably be chosen so that the carboxyl-reactive groups and the carboxyl functionality would not react to any significant extent during storage of the container that contains the adhesive composition. [0038] The acrylic polymer composition of the present invention contains one or more acrylic polymers. In some embodiments, the acrylic polymer composition will contain at least two different acrylic polymers: a first acrylic polymer will contain, as polymerized units, at least one monomer with carboxyl functionality and will not contain, as polymerized units, any carboxyl-reactive monomers; while a second acrylic polymer will not contain, as polymerized units, any monomers with carboxyl functionality and will contain, as polymerized units, at least one carboxyl-reactive monomer. It is contemplated that such embodiments could be practiced as multi-pack systems, typically with the first acrylic polymer in one container and the second acrylic polymer in a different container. It is also contemplated that some of these embodiments could be practiced as one-pack systems. [0039] Preferred are embodiments of the present invention that contain at least one acrylic polymer that contains, as polymerized units, monomers with carboxyl functionality and carboxyl-reactive monomers. Acrylic polymers that contain, as polymerized units, monomers with carboxyl functionality and carboxyl-reactive monomers are known herein as “bifunctional acrylic polymers.” [0040] A wide variety of bifunctional acrylic polymers are suitable for use in the present invention. For example, one suitable bifunctional acrylic polymer would be a copolymer that included as polymerized units at least one monomer with carboxyl functionality and at least one suitable carboxl-reactive-monomer but that did not include any macromonomers as polymerized units. Other suitable bifunctional acrylic polymers include at least one macromonomer as polymerized units; among such polymers, some suitable polymers include as polymerized units monomers with carboxyl functionality that are not macromonomers. Other suitable bifunctional acrylic polymers include as polymerized units macromonomers with carboxyl functionality. Still other suitable bifunctional acrylic polymers include as polymerized units both macromonomers with carboxyl functionality and monomers with carboxyl functionality that are not macromonomers. Yet other suitable bifunctional acrylic polymers include as polymerized units at least one macromonomer that has no carboxyl functionality. Also suitable are mixtures and copolymers of the above suitable bifunctional acrylic polymers. [0041] Embodiments that employ bifunctional acrylic polymers generally could be practiced as either one-pack or multi-pack systems. Generally, when using embodiments that may be practiced as either one-pack or multi-pack systems, the simplicity and convenience of the one-pack system will make the one-pack preferable over the multi-pack. In particular, embodiments with bifunctional polymers are advantageous because of simplicity of manufacture of the polymer and because the convenience of the one-pack system is available. A preferred embodiment of the present invention employs at least one bifunctional polymer in a one-pack system. [0042] The layer of adhesive composition that is applied to a substrate may be continuous or discontinuous; it may have uniform thickness or it may be thicker in some places than others. After application to the substrate, the aqueous composition is typically dried, or allowed to dry, at a temperature from 20° C. to 95° C. [0043] In some embodiments of the present invention, after the adhesive composition is applied to a first substrate, it is contacted with a subsequent substrate to form an assembly, which is optionally subjected to applied pressure such as by passing it between rollers to effect increased contact of the substrates with the adhesive composition. In another embodiment the adhesive composition may be simultaneously or sequentially applied to two surfaces of a first substrate, which coated surfaces are then simultaneously or sequentially bonded to two subsequent substrates, which may be the same or different relative to the first substrate and each other. It is further contemplated that the composite article may subsequently be bonded to one or more other substrates using the same or a different adhesive before or after the process described herein. Also, it is contemplated that a wide variety of arrangements of substrates and polymeric adhesive layers may be used to form the composite article. For example, multiple substrates may be alternated with multiple layers of adhesive, such as for example in multilayered laminates. For another example, in some embodiments, layers of adhesive composition, each applied to its own substrate, may be brought together. [0044] In some embodiments of the present invention, a layer of the adhesive composition will be applied to a substrate and dried before being contacted with a subsequent substrate. Alternatively, in other embodiments, using a process known as “wet bonding,” a layer of the adhesive composition will be applied to a substrant; a subsequent substrate will be contacted with the layer of adhesive composition; and the assembly thus formed will then be dried or allowed to dry. It is contemplated that when multiple substrates and/or multiple subsequent substrates and/or multiple layers of adhesives are used, any combination of wet bonding and/or other methods may be used. When wet bonding is used to bond thin, flat substrates, the process is called “wet bond lamination.” The present invention is contemplated to be particularly useful in wet bond lamination. [0045] Typical substrates include, for example, paper, fabric, metals, metal foils, metalized polymers, and various polymers, including, for example, polymers with low surface energies. Substrates may be used with or without a prior treatment such as an acid etch or corona discharge or primer. The adhesive composition may be applied using conventional application methods such as, for example, roll coating, doctor-blade application, and printing methods. [0046] Some composite articles are made of relatively thin, flat layers; such composite articles are generally known as laminates. In many cases, one or more of the substrates in a laminate is a polymeric film, including, for example, untreated, metalized, and treated polymeric films. The method of this invention is useful for preparing various types of composite articles, including laminates, especially flexible laminates. Laminates are used to provide packaging which is light-weight and flexible. It is desirable to use the adhesive composition at a low application weight to minimize the weight of the laminate, to maintain flexibility, and to minimize cost. [0047] Crosslinking can be observed in some embodiments of the present invention. Typically, the occurrence of crosslinking in polymers can be observed using any of a variety of methods known in the art, as described for example by L. H. Sperling in Introduction to Physical Polymer Science , second edition, Wiley-Interscience, 1992. For example, crosslinked polymers generally cannot be dissolved in any solvent. Also, crosslinked polymers generally give a distinctive response in Dynamic Mechanical Analysis (DMA) testing: in the “plateau” temperature range (i.e., temperatures ranging from 50° C. above the glass transition temperature (Tg) up to 200° C., or up to the temperature of degradation, if that is less than 200° C.), a crosslinked polymer will generally have a relatively flat elastic modulus, as measured by the shear elastic modulus (G′) or the tensile elastic modulus (E′). For example, an adhesive composition could be tested by DMA by drying or allowing the composition to dry under conditions (e.g., temperature, time, etc.) resembling the expected drying conditions during application to a substrate; the dried composition could then be measured by DMA at 6.28 cycles/sec from 50° C. above Tg up to 200° C. (or up to the temperature of degradation, if that is less than 200° C.); normally if the dried composition is crosslinked, the G′ values over the entire temperature range will be between 1 kPa (10 4 dyne/cm 2 ) and 1 MPa (10 7 dyne/cm 2 ). The glass transition temperature, for the purpose of defining the plateau temperature range, is measured herein as the temperature of the peak in the curve of tan(delta) vs. temperature in the DMA test. If more than one Tg is present in the dried adhesive composition, the DMA assessment of crosslinking is made by examining the modulus from 50° C. above the highest Tg up to 200° C. (or the degradation temperature, if that is lower than 200° C.). [0048] It is to be understood that for purposes of the present specification and claims that the range and ratio limits recited herein can be combined. For example, if ranges of 60 to 120 and 80 to 110 are recited for a particular parameter, it is understood that the ranges of 60 to 110 and 80 to 120 are also contemplated. Additionally, if minimum range values of 1 and 2 are recited, and if maximum range values of 3, 4, and 5 are recited, then the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. [0000] Abbreviations: [0000] AA=acrylic acid MAA=methacrylic acid MMA=methyl methacrylate BA=n-butyl acrylate EA=ethyl acrylate GMA=glycidyl methacrylate HSLDPE=high slip low density polyethylene mPET=metalized polyethylene terephthalate Robond™ 2000=Aqueous acrylic latex polymer adhesive, from Rohm and Haas Co., Philadelphia, Pa. Primal™ Resin 18=Aqueous solution polymer, EA/MAA, from Rohm and Haas Co., Philadelphia, Pa. Disponil™ FES-32=fatty alkyl ether sulfate, sodim salt from Henkel Corp., Ambler Pa. Pluracol™ P410=polyether polyol from BASF Corp. Test Procedures: [0061] Laminates were prepared by coating one substrate with the adhesive composition and then drying the coating in an oven at 70° C. for 2 minutes. The coatweight was in the range of 1.0-1.4 pounds per ream. The second substrate was applied onto coated substrate and pressed through cylinders at 65.5° C. Laminates were cut into strips 25.4 mm (1 inch) wide. A portion of the end of the strip is not coated, so that the substrates can be peeled apart and placed in the opposite jaws of a vertical tensile tester. The other end of the strip is supported to keep the sample in the shape of a letter “T” while the jaws are separated at 254 mm/minute (10 inches/minute). The average force to separate the jaws is reported as the “T-peel” value, in grams of force per 25.4 mm (I inch) of sample width). Tests are performed at room temperature (18° C. to 25° C.). “Initial” results are reported on tests performed immediately after laminating; “7 day” results are reported on tests performed on samples stored for 7 days at room temperature; and “2 day boiling” results are reported on tests performed on samples immersed in boiling water for 2 days. [0062] Dynamic Mechanical Analysis was performed by preparing the samples of the adhesive composition by casting dispersion onto Teflon petri dish with 1 mm thickness. The film is dried for 2-5 days at room temperature ant then dried in vacuum oven at 50° C. for 24 hours, flipped over the film and the other side of film is dried in vacuum oven at 50° C. for another 24 hours. The samples were tested in Rheometrics Mechanical Spectrometer (RMS-800) from Rheometrics company at 6.28 cycles/sec at strain of 5% from −50° C. to 200° C. EXAMPLES Example 1 Macromoner [0063] Monomer emulsion was prepared by adding MAA macromonomer solution (12 g in 80 g H 2 O) into the emulsifying solution of 344 g deionized water, 15.5 g surfactant Fes-32, 744 g BA, and 4 g GMA. 20% solution of monomer emulsion was added into the kettle containing 216 g deionized water and 99.5 g macromonomer (92MMA/8EA). After 20 minutes stirring, the glass reactor was heated to 90° C. while buffer solution of 0.6 g Na 2 CO 3 and 10 g deionized water was fed into the reactor. At 80° C., sodium persulfate was added as a shot and monomer emulsion feed was started for 60 minutes feeding time. Reaction was maintained at 90° C. for length of feeds and for an hour hold. After hold, the reaction was cooled to 60° C., and 6.2 g of Fe 2 SO 4 solution (0.15%) was added and followed by two sets of redox initiator solution: tert-butyl peroxide (1.9 g in 10 g H 2 O) and SSF (0.9 g in 10 g H 2 O) in feeding of 20 minutes. Then the reaction was held for 15 minutes and cooled to 40° C., and 2.0 g of biocide Kathon (Rohm and Haas Co., Philadelphia, Pa.) was added. The product was filtered. Example 2 Adhesive Composition [0064] An adhesive composition was made by mixing the following ingredients. “Parts by Weight” herein means 100× (weight of the ingredient, including solids and fluid medium)/(total weight of the adhesive composition). Ingredient Parts by Weight Macromonomer emulsion of Example 29.85 1 (50.6% solids) Robond ™ PS2000 (54.5% solids) 39.80 Primal ™ Resin 18 (22.0% solids) 29.85 Pluracol ™ P410 (100% solids) 0.50 [0065] This adhesive composition was coated onto HSLDPE at room temperature and dried at 70° C. and laminated with mPET under weight pressure of cylinder. The T-peel results were as follows: Initial: 377 g/25.4 mm 7 day: 367 g/25.4 mm 2-day boil: 490 g/25.4 mm [0066] In DMA testing, the Tg (peak of tan(delta) vs. temperature) occurred at around −15° C. From 35° C. to 200° C., G′ values were all between 10 kPa (10 5 dyne/cm 2 ) and 1 MPa (10 7 dyne/cm 2 ). Example 3 Adhesive Composition [0067] Using the methods of Example 1, a macromonomer emulsion ME2 was prepared of composition 97 BA/1.5 MAA/0.6 GMA. Also, a macromonomer emulsion ME3 was prepared by polymerizing ME2 with the macromonomer of Example 1, in the ratio 95 ME2/5 Example 1. Ingredient Parts by Weight ME 3 (50.2% solids) 46.43 Robond ™ PS2000 (54.5% solids) 26.53 Primal ™ Resin 18 (22.0% solids) 29.53 Pluracol P410 (100% solids) 0.50 [0068] This adhesive composition was coated onto HSLDPE at room temperature and dried at 70° C. and laminated with mPET under weight pressure of cylinder. The T-peel results were as follows: Initial: 376 g/25.4 mm 7 day: 349 g/25.4 mm 2-day boil: 490 g/25.4 mm [0069] In DMA testing, the Tg (peak of tan(delta) vs. temperature) occurred at around −32° C. From 22° C. to 200° C., G′ values were all between 10 kPa (10 5 dyne/cm 2 ) and 1 MPa (10 7 dyne/cm 2 ). Example 4 Adhesive Composition [0070] A repeat of the preparation of ME3 from Example 3 produced ME3b. ME3 and ME3b were each used as the sole ingredient in an adhesive composition. Samples were prepared and tested as in Example 2. T-peel results were as follows: Test ME3 ME3b Initial: 254 g/25.4 mm 134 g/25.4 mm 7 day: 269 g/25.4 mm 288 g/25.4 mm 2-day boil: 493 g/25.4 mm 510 g/25.4 mm [0071] Composition ME3b was tested in DMA. Tg was around −30° C. G′ values from 20° C. to 200° C. were all between 10 kPa (10 5 dyne/cm 2 ) and 1 MPa (10 7 dyne/cm 2 ). Example 5 Adhesive Composition using Random Copolymer without Presence of Macromonomer [0072] Using the methods of Example 1, 2 polymer latices, PL1 and PL2 were prepared with these compositions: PL1: 85.48 EA/9.94 MMA/3.98 AA/0.60 GMA (51.2% solids) PL2: 93 BA/1.43 MAA/0.57 GMA/4.6 MMA/0.40 EA (49.9% solids) [0075] Each latex was used as the sole ingredient in an adhesive composition, which was applied and tested as in Example 2. T-peel results were as follows: Test PL1 PL2 Initial: 275 g/25.4 mm  96 g/25.4 mm 7 day: 401 g/25.4 mm 423 g/25.4 mm 2-day boil: 527 g/25.4 mm 404 g/25.4 mm [0076] Composition PL1 was tested in DMA. Tg was around 10° C. G′ values from 60° C. to 200° C. were all between 10 kPa (10 5 dyne/cm 2 ) and 1 MPa (10 7 dyne/cm 2 ). Example 6 Storage Stability [0077] The aqueous latices of the adhesive compositions of Example 2, Example 3, Example 4 (both ME3 and ME3b), and Example 5 (both PL1 and PL2) were stored at 40° C. for one month. All of them showed no change in viscosity or appearance.

An adhesive composition is provided, along with a method for bonding substrates with the provided compositions. The adhesive composition is curable and suitable for bonding laminates, but it does not require macromonomers with carboxyl-reactive groups.

BACKGROUND OF THE INVENTION This invention relates to a carrier to transport items. Manufacturers have devised cases for carrying items. Examples of cases include luggage, briefcases and computer carriers. In particular, for computer carriers that hold a portable computer, the typical carrier resembles a briefcase. The cases have the same (i.e., rectangular) shape as the computer. The cases are made of either a hard material or soft material. The cases afford some protection to their contents. SUMMARY OF THE INVENTION In general, the invention features a pouch having two opposing, curved sidewalls. Each curved sidewall has a padding layer and a casing on an exterior portion of the padding layer. In one embodiment, the casing and padding are arranged such that the casing is in tension with respect to the padding layer. The tension causes the opposing sidewalls to curve. The pouch has a closing piece, such as a flap extending from one opposing sidewall and attaching to the other opposing sidewall. The padding layer can be a corrugated material or a closed cell foam material. The padding layer can also have a series of folds and ridges that run in parallel with the curvature of the sidewall of the pouch. The pouch is configured to deform so that it absorbs and distributes any impact energy imparted to the pouch. The pouch can be substantially fitted for a rectangular object so that such an object inside the pouch forms protective pockets between the object and sidewalls of the pouch. BRIEF DESCRIPTION OF THE DRAWINGS The foregoing features and other aspects of the invention will become more apparent from the drawings, taken together with the accompanying description, in which: FIG. 1 is a perspective view illustrating a protective pouch; FIG. 2A is a perspective view illustrating the pouch of FIG. 1 in an open position with a portable computer being inserted; FIG. 2B is a cross-sectional view taken along line 2B--2B of FIG. 2A; FIG. 3A is a cross-sectional perspective view illustrating a padding layer for the pouch of FIG. 1; FIG. 3B is a cross-sectional perspective view illustrating an alternate embodiment of the padding layer for the pouch of FIG. 1; FIG. 3C is a cross-sectional perspective view illustrating a still further alternate embodiment of the padding layer for the pouch of FIG. 1; FIG. 3D is a perspective view illustrating a padding layer having a hard plastic coating useful in the pouch of FIG. 1; FIG. 4A is a perspective view of an alternate embodiment of a pouch; FIG. 4B is a view of a side padding for the pouch of FIG. 4A; FIG. 4C is a cross-sectional view showing side padding; and FIG. 5 is a top view of FIG. 2A illustrating protective pockets surrounding the contents inside a pouch. DETAILED DESCRIPTION Referring now to FIG. 1, a protective pouch 10 having an outer protective covering 12 and a closure flap 14 is shown in a closed position. In one embodiment, outer protective covering 12 and flap 14 are comprised of a suitable fabric-type material that is stitched at seam 16a and seam 16b. The pouch is sized to hold a fragile device such as a portable computer. The configuration of the pouch 10 and the materials of the components of the pouch 10 are provided to impart shock absorbing properties to the pouch as will be described. The pouch 10 protects its contents by a number of mechanisms in the event of impact from an outside force, such as by dropping the pouch and its contents on the ground. Referring now to FIGS. 2A and 2B, the pouch 10 is shown in an open position with flap 14 open revealing a pair of Velcro®, Velcro Industries, strips 15a, 15b. One Velcro® strip 15a is attached to the inside of flap 14 and the mating Velcro® strip 15b is attached to a front sidewall 18a of the pouch 10. A back sidewall 18b is also provided. Both sidewalls 18a, 18b are joined along seams 16a, 16b and are configured to have an outwardly curved surface. In particular, as shown in FIG. 2B, the pouch includes the outer protective covering 12 of fabric or other outer protective covering arranged about a padding layer 20. The outer protective covering 12 is configured to be placed in tension between seams 16a, 16b with respect to padding layer 20 so as to cause the sidewalls of the pouch 10 to curve outward. This curvature provides the pouch 10 with shock absorbing and cushioning properties when the pouch 10 is used to protect an object. The shock absorbing property results from a spring-like force. The spring-like force must be overcome by an external force to cause the sidewalls to collapse before the external force can act on an object in the pouch 10. The shock absorbing properties of the sidewalls are in addition to the intrinsic protective properties afforded by the characteristics of the materials used to make the pouch. A suitable fabric material for the outer protective covering 12 includes a rip-stop Nylon®. The pouch 10 optionally includes an inner liner 19 disposed to cover the padding layer 20. The inner liner 19 need not be the same material as the outer protective covering 12. Referring now to FIG. 3A, one embodiment of the padding layer 20 is shown. The padding layer 20 is comprised of a foam material and is arranged as a plurality of here evenly spaced alternating ridges 20a and folds 20b, or corrugations resembling waves that extend over the surface of the padding layer 20. The corrugations are provided to stiffen the foam in an in-plane, lateral direction orthogonal to the corrugations. When this foam layer 20 is used within the pouch, the corrugations are preferably disposed parallel with the curved surface of the sidewalls. The combination of the curved surface of the sidewalls and the corrugations cause the pouch to have substantial rigidity and enables the pouch to have the curved sidewalls and conform to a generally oval type shape as shown in FIG. 2B. In one embodiment of the padding layer 20, the foam layer 22 is comprised of a closed cell foam that provides a degree of cushioning to the padding. Alternatively, an open cell foam material could be used but an open cell foam is less preferred because of its typical water absorbent properties. Referring now to FIG. 3B, an alternative embodiment 20' of the padding layer is shown. Foam material 22' (either open or closed cell) is configured as crossed layers that deform upon impact. Referring now to FIG. 3C, another alternative embodiment 20" of the padding layer 20 is shown. Padding layer 20" includes the closed cell foam layer and the corrugated portions of the embodiment of FIG. 3A, as well as, spacers 24 disposed between ridges to provide the foam layer 22" with additional resistance to deforming in the lateral direction. One type of foam that has this configuration is Ridge-Rest® closed cell foam material (available from Cascade Designs) and is disclosed in U.S. Pat. No. 4,980,936 incorporated herein by reference. Referring now to FIG. 3D, padding layer 20 is shown having a thin hard covering surface 26 over a padding layer. As shown the surface 26 is disposed over the corrugated portions of either the padding layer 20 or 20". The hard covering surface 26 is a plastic or other type of material or film such as Kevlar® from Dupont and can act as the outer protective covering of the pouch or an additional protective layer between the padding layer 20 and outer layer 12. The hard covering 26 is characterized as having a hardness that is substantially greater than the hardness of the underlying padding layer. The hard covering surface 26 can be molded into a curve shape to dissipate energy across the outer case. The hard covering surface 26 can also be curved ribs that form a rib cage. Referring now to FIG. 4A, the inner lining 19 and outer protective covering 12 can be arranged to form a sleeve 28 within which the padding layer 20 is inserted. The dimensions of the sleeve 28 and hence the surface area of the inner layer 20 and the surface area of the outer protective covering 12 are selected so that when the inner layer 20 is inserted into the sleeve, the outer surface area curves outwardly imparting the illustrated curved surface to the front sidewall 18a and the back sidewall 18b. By configuring the outer protective layer 12 and the padding layer 20, in this manner, the combination provides a spring-like property to the sidewalls 18a, 18b of the pouch to increase the ability of the pouch to protect its contents. Referring now to FIG. 4B, the padding layer 20 can have a sidewall padding layer 30 disposed along the edges of the pouch while the sidewalls 18a, 18b of the pouch 10 are still maintained in curvature. The sidewall padding layer 30 is inserted adjacent the pair of seams 16a, 16b and along the bottom of the pouch 10. Alternatively, as shown in FIG. 4C, the sidewall padding can be placed between a pair of seams along each of the edges of the pouch. Each sidewall 18a, 18b of the pouch would be coupled between a corresponding pair of seams 19a, 19a' and 19b, 19b' so that the outer layer of each sidewall 18a, 18b is disposed in tension between the pair of corresponding seams with respect to the padding layer 12. The sidewall padding layer 30 is inserted to provide additional shock absorbent properties and protection along the sidewalls 18a, 18b to an object contained in the pouch 10. Referring now to FIG. 5, the pouch 10 is shown housing an object 38, such as a portable computer. Because the object 38 is rectangular and the configuration of the pouch is oval-like, protective pockets or spaces 32 are formed between sidewall surfaces of the object 38 and opposing portions of the interior of the pouch 10. During impact against the outside of the pouch, the presence of the protective pockets 32 diminish the impact force imparted to the object 32 because the sidewalls of the pouch 10 flex or compress to fill the pockets and thus dissipate a portion of the force imparted to the object as a result of the impact. Besides producing protective zones 32 around object 38, tensional forces increase the structural integrity of padding layer 20. The protective covering 12 and padding resist distortion from their relaxed shape by resisting an externally applied force 34 with a "restoring force" 36. The restoring force is related to the amount of pre-stressing of the pouch provided by the curved surfaces of the pouch 10. This prestressing can be modeled as a spring in partial compression. Therefore, prestressing the curved sidewalls increases the amount of energy that the pouch 10 will absorb before its contents are affected. A strap can also be attached to the inside of the pouch for additional security. The strap can be fastened around the object 38 to prevent the object 38 from shifting inside the pouch. The pouch can be used to protect nonrectangular objects. In addition, a rectangular form can be placed within the pouch and the form can house objects having different shapes. Having described preferred embodiments of the invention, other embodiments incorporating its concept may be used. It is felt, therefore, that this invention should not be limited to the disclosed embodiment, but rather should be limited only by the spirit and scope of the appended claims.

A protective pouch has a closed cell foam padding and a casing enclosed around the closed cell foam padding. The configuration forms two opposing curved sidewalls. The protective pouch has a closing mechanism, which can be a flap extending from one sidewall and attached to the other sidewall. The pouch can be substantially fitted for a rectangular object so that when the object is inside said pouch, the object forms protective pockets between the sidewalls of the object and opposing sidewalls of the pouch.

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation of U.S. application Ser. No. 13/499,756, filed Apr. 2, 2012, which is the U.S. national phase entry of PCT/US2011/020124 with an international filing date of Jan. 4, 2011, which claims priority to U.S. Provisional Application No. 61/292,280, filed Jan. 5, 2010, the entire disclosures of which are hereby incorporated by reference. BACKGROUND [0002] Appliances such as clothes washers and driers, dish washers, etc., must be packaged before they leave a manufacturing facility in a manner that protects them from the hazards of transport until they reach their ultimate destination, which is typically a consumer's home. Along the way, an appliance may be loaded and unloaded from several locations and must be packaged for protection against inadvertent damage. Appliances such as vertical suspension clothes washers include an outer cabinet or housing containing a tub that is suspended in the cabinet and moved relative to the cabinet by a tub drive motor. Washers of this type are well known in the art and it is not unusual for such appliances to occasionally experience damage during shipping. It is also not unusual for such appliances to generate varying levels of sound or noise during operation in the consumer's home. SUMMARY [0003] Apparatuses and methods relating to appliances are provided. In one embodiment, an appliance having a housing, a moveable tub member inside the housing, and a dampening portion is provided. The housing includes, for example, at least one side wall and the dampening portion disposed at least partially between the moveable tub member and the at least one side wall. The dampening portion includes, for example, a resilient material having at least one surface extending at least partially along the side wall or tub member. BRIEF DESCRIPTION OF THE DRAWINGS [0004] The accompanying drawings incorporated herein and forming a part of the specification, illustrate several embodiments of the present invention and together with the description serve to explain certain principles of the invention. In the drawings: [0005] FIG. 1 is a perspective view of one embodiment of a plug that can be used for packaging (shipping), operation damping, or both; [0006] FIGS. 2 a -2 c are front plan views of embodiments of a horizontal energy damping element that can be used for packaging (shipping), operation damping, or both. [0007] FIG. 3 is a perspective view of the embodiment of FIG. 2 b formed into one embodiment of a sleeve of the type that is stretched around the tub of the washer in order to form an embodiment of the horizontal energy damping element; [0008] FIG. 4 is a schematical cross sectional view illustrating one embodiment of a combined shipping and operation damping system for protecting the tub of the washer during shipping; [0009] FIG. 5 a is a view similar to FIG. 4 but showing the plug removed and the horizontal energy damping element in position around the tub to provide vibration damping and acoustic insulation during washing operation; [0010] FIG. 5 b is another cross sectional view illustrating the horizontal energy damping element positioned around the tub so as to be present in the space between the tub and the sidewalls of the cabinet; [0011] FIG. 6 is a schematical cross sectional view illustrating an alternative embodiment for the horizontal energy damping element; [0012] FIG. 7 a is a front elevational view of yet another alternative embodiment of the horizontal energy damping element in the form of a T-shaped pad; [0013] FIG. 7 b is a detailed partial sectional view illustrating how the T-shaped pad of FIG. 7 a is mounted to a sidewall of the washer cabinet; and [0014] FIG. 8 is a partial cross sectional view of another alternative embodiment of the horizontal energy damping element. DETAILED DESCRIPTION [0015] Prior to discussing the various embodiments, a review of the definitions of some exemplary terms used throughout the disclosure is appropriate. Both singular and plural forms of all terms fall within each meaning: [0016] “Physical communication” as used herein, includes but is not limited to connecting, affixing, joining, attaching, fixing, fastening, and placing in contact two or more components, elements, assemblies, portions, or parts. Physical communication between two or more components, etc., can be direct or indirect such as through the use of one or more intermediary components and may be intermittent or continuous. [0017] In accordance with one general embodiment, a combined shipping and operation damping system is provided for a washer including a tub suspended in a cabinet having a top wall, sidewalls, a tub access opening in the top wall, and a lid covering that access opening. The system comprises a removable plug having a first portion contoured to fit snugly in the tub and a second portion contoured to fit snugly in the access opening in the cabinet. In addition the system includes a horizontal energy damping element positioned between the tub and the sidewalls of the cabinet. The removable plug and horizontal energy damping element function together to secure the tub in place in the cabinet during shipping. The removable plug is then removed following shipping and the horizontal energy damping element remains in place to provide vibration damping and acoustic insulation during washer operation. [0018] In accordance with one general embodiment, a method is provided for both shipping and operation damping of a washer including a tub suspended in a cabinet having a top wall, sidewalls, a tub access opening in the top wall, and a lid covering the access opening. The method comprises the steps of (a) positioning a removable plug in the access opening in the tub, the plug being contoured to snugly engage the cabinet and the tub; and (b) positioning a horizontal energy damping element between the tub and the sidewalls of the cabinet. The removable plug and horizontal energy damping element secure the tub in place in the cabinet during shipping. The removable plug is then removed following shipping and the horizontal energy damping element remains in place around the tub to provide vibration damping and acoustic insulation during washer operation. [0019] In accordance with yet another general embodiment, a clothes washer comprises a cabinet including sidewalls, a top wall having an access opening, and a lid covering that access opening. The clothes washer further includes a tub suspended in the cabinet as well as a pump and motor system contained in the cabinet. Further, the clothes washer includes a sleeve of resilient material secured around the tub that provides vibration damping and acoustic insulation. [0020] In accordance with still another general embodiment, a clothes washer is provided comprising (a) a cabinet including sidewalls, a top wall having an access opening, and a lid covering that access opening; (b) a tub suspended in the cabinet; and (c) a pump and motor system contained in the cabinet. The clothes washer further includes a block of resilient material secured to the cabinet. The block of resilient material includes a tub opening. The tub extends through that tub opening. [0021] In accordance with yet another general embodiment, a clothes washer comprises (a) a cabinet including sidewalls, a top wall having an access opening, and a lid covering that access opening; (b) a tub suspended in the cabinet; and (c) a pump and motor system contained in the cabinet. Further, the clothes washer includes a substantially T-shaped pad mounted to each sidewall that provides vibration dampening and acoustic insulation. [0022] Reference is now made to FIGS. 1, 2 a - 2 c , 3 , 4 , and 5 a - 5 b illustrating an embodiment of the combined shipping and operation damping system of the present invention. The shipping and operation damping system includes a removable plug 12 and means for dampening. In one embodiment, the means for dampening is a horizontal energy damping element 14 . As will become apparent from the following description, the removable plug 12 and horizontal energy damping element 14 function together to secure a tub means or tub T in place in a means for housing or cabinet C of a washer W during shipping. The removable plug 12 is removed following shipping and the horizontal energy damping element 14 remains in place around the tub T to provide vibration damping and acoustic insulation during washer operation. [0023] As best illustrated in FIG. 1 , the removable plug 12 includes a first or lower portion 16 that is sized, shaped, and contoured to fit snugly in the tub of washer W. The plug 12 also includes a second or lower portion 20 sized, shaped and contoured to fit snugly in the opening O provided in the top wall of the cabinet C of washer W (see also FIG. 4 ). In the illustrated embodiment the second portion 20 includes a flat sidewall segment 18 matching the shape of the opening O that functions to lock the removable plug 12 in position. [0024] Since the plug 12 fits snugly in both the opening O of the cabinet C and the tub T of the washer W, it should be appreciated that the plug functions to substantially prevent horizontal movement of the tub T relative to the cabinet C during shipping or other transport of the washer. [0025] The plug 12 may be made from substantially any appropriate material including but not limited to expanded polystyrene, molded plastic, cardboard, and mixtures thereof. [0026] As best illustrated in FIGS. 3 and 4 , the horizontal energy damping element 14 comprises a sleeve 22 of resilient material that is, in one embodiment, stretched over and secured around the tub T. The sleeve 22 may be secured in any appropriate manner including by means of mechanical fasteners, an appropriate adhesive, or friction. As best illustrated in FIGS. 2 a -2 c , the sleeve 22 may be formed from a solid sheet of resilient material 24 , a lattice sheet of resilient material 26 , or a combination sheet 28 of solid and lattice sections 30 , 32 , respectively, of resilient material. Any of the sheets 24 , 26 , 28 may be formed into a sleeve 22 by abutting and securing the ends of the sheet together by hot welding, adhesive, or other appropriate means. Thus, as illustrated in FIGS. 2 b and 3 , the ends 34 of the sheet 26 may be connected together to form the sleeve 22 of lattice material. [0027] The horizontal energy damping element 14 or sleeve 22 may be made from substantially any appropriate material including, but not limited to, material selected from a group consisting of a polyester, a polyester olefin blend, polyethylene terephthalate, polybutylene terephthalate, a polyethylene terephthalate and polypropylene blend, a polybutylene terephthalate and polypropylene blend, and combinations thereof. As an alternative, the horizontal energy damping element 14 or sleeve 22 may be made from a laminated material including a core layer of fiberglass reinforced polymer material sandwiched between two wear layers of polyester material. [0028] Polyester materials are particularly useful as construction material for the sleeve 22 as they exhibit excellent resiliency and wear resistance to provide a long service life. At the same time, the acoustic properties of the material may be tuned to better control noise and vibration. This may be done by adjusting the density as well as the diameter and length of the fibers utilized in the material. [0029] In addition, it should be appreciated that the horizontal energy damping element 14 or sleeve 22 may be further tuned to provide the desired spring rate for the most effective damping of horizontal energy or motion of the tub T within the cabinet C. Typically, the horizontal energy damping element 14 /sleeve 22 provides a spring rate of between about 6.5 and about 102.0 pounds of force per 100 square inches of contact area. However, this is not critical as long as the sleeve provides the appropriate protections during shipping and/or operation. In this regard, a sleeve 22 made from the lattice sheet 26 provides the greatest versatility. [0030] The spring rate range desired for optimum energy dampening is dependent upon the weight of the tub T, the cabinet-to-tub wall gap G (which may be an air gap), and the weight of wet clothes contained in the tub. A gap G is provided between the damping element 14 /sleeve 22 and the cabinet sidewalls S so as to not impair the torque movement of the tub T during start and stop movements. In other embodiments, gap G may extend partially or completely along tub T and may or may not be in contact with tub T or the cabinet sidewalls S. [0031] The loft of the material determines how soon the tub T starts meeting resistance to slow the horizontal energy or momentum of the tub as it moves toward contact with the sidewall S of the cabinet C. The more the material of the damping element 14 /sleeve 22 is compressed between the tub T and sidewall S during horizontal movements, the higher the spring rate of the material and the stronger the damping of the horizontal energy. Thus, it should be appreciated that the damping element 14 /sleeve 22 made from the lattice material 26 may be effectively “tuned” for a number of different applications. By increasing the amount of solid material in the lattice 26 the spring rate may be increased. Conversely, by reducing the amount of solid material in the lattice 26 , the spring rate of the material may be reduced. Thus, by selecting a proper lattice and adjusting the loft or thickness of the lattice to between about 20.0 and about 50.0 mm it is possible to tune the spring rate to a desired level for the most efficient and effective damping of horizontal energy. Typically the lattice will include between about 10 and about 90 percent solid material and between about 90 and about 10 percent open space. [0032] As illustrated in FIGS. 4 and 5 b , damping element 14 /sleeve 22 need not extend to the top and bottom of the tub T, but can occupy portions in between. In alternative embodiments, damping element 14 /sleeve 22 can extend to the upper and lower extremities of the tub T. Hence, more or less of the tub T can be covered by damping element 14 /sleeve 22 . Furthermore, damping element 14 /sleeve 22 can be made of a plurality of damping elements or sleeves around tub T, which may or may not be adjacent to each other. In this manner, the damping element 14 /sleeve 22 can be formed by an assembly of components. Still further, damping element 14 /sleeve 22 may extend partially or completely along tub T and may be continuous or discontinuous. [0033] As noted above, the plug 12 and damping element 14 are positioned during packaging as illustrated in FIG. 4 to prevent horizontal shifting of the tub T in the cabinet C during shipping. Once the washer W is positioned in a laundry room or otherwise situated for use, the plug 12 is removed while the damping element 14 remains positioned around the tub T for the life of the washer W (see FIGS. 5 a and 5 b ). In this manner, the damping element 14 is dual use: shipping and operation. As such, it is not disposed of after shipping has been completed. [0034] During operation, the damping element 14 reduces and controls horizontal motion of the tub T toward the sidewalls S of the cabinet C. This reduces noise and vibration so as to provide smoother and more silent operation. The polyester material of the damping element 14 is very resilient and scuff resistant so as to provide a long service life without any significant degradation of desired damping properties. Other materials may be used which have similar properties. [0035] An alternative embodiment of the means for dampening is a horizontal energy damping element 14 as illustrated in FIG. 6 . In this embodiment the horizontal energy damping element 14 comprises a block 40 of resilient material that is secured to the sidewalls S of the cabinet C. The block 40 of resilient material includes a tub opening 42 . As should be appreciated the tub T extends through the opening 42 . A small space or clearance air gap G is provided between the tub T and the tub opening 42 so that the torque movement of the tub T during start and stop movements is not impaired in any way. In other embodiments, gap G may extend partially or completely along tub T and may or may not be in contact with tub T. [0036] It should be appreciated, however, as the tub T moves horizontally under load from, for example, uneven weight distribution of clothes in the tub T during a spin cycle, the tub T engages and compresses the block 40 . The spring rate of the material then dampens that horizontal movement. As described earlier, the block 40 need not extend to the upper and bottom extremities of tub T, but may be positioned at portions in between. In one embodiment, block 40 is secured to the sidewalls S at the same approximate tub location as damping element 14 /sleeve 22 in FIGS. 4 and 5 b. [0037] Still another alternative embodiment of the means for dampening is a horizontal energy damping element 14 as illustrated in FIGS. 7 a and 7 b . As illustrated in FIG. 7 a , this embodiment of the horizontal energy damping element 14 comprises a substantially T-shaped pad 50 . As illustrated in FIG. 7 b such a T-shaped pad 50 is mounted to each sidewall S of the washer W. A small space or clearance gap is provided between each of the T-shaped pads 50 and the tub T when the tub T is in its steady state position. However, whenever the tub T moves horizontally under loading during operation of the washer W, the tub T engages one or more of the pads 50 , compressing the pad. The spring rate of the material used to construct the pad 50 provides damping of that horizontal energy as the material compresses thereby controlling and limiting horizontal movement and vibration. [0038] The block 40 and T-shaped pads 50 of the two alternative embodiments are made from the same material of the sleeve 22 . Thus, each embodiment of the damping element 14 provides the desired resiliency and spring rate for effective damping of horizontal energy and the necessary strength and abrasive resistance to function as desired for a long service life. In other embodiments, pad 50 can be made from different shapes such as, for example an I-shape, only an upper horizontal portion of a T-shape, etc. [0039] In summary, numerous benefits result from employing the concepts of the present invention. The plug and horizontal vibration damping element function together to greatly reduce or otherwise limit horizontal movement of the tub T within the cabinet C of the washer W during shipping. Thus, potential damage to the tub T is prevented as it is transported from one location to another. [0040] Following shipping, plug 12 is removed and the horizontal energy damping element can remain to provide vibration damping during operation. Significantly, by controlling and eliminating undesired horizontal movement of the tub T it is possible to provide a larger capacity tub T within a given size cabinet C. In addition, the material from which the horizontal energy damping element 14 is constructed provides acoustic benefits reducing noise during operation of the washer W. [0041] Still further, the horizontal energy damping element 14 provides improved water management by catching and absorbing water that might be inadvertently spilled from the tub T during operation of the washer W and preventing that water from reaching the floor underneath the appliance. Further, it should be appreciated that the horizontal energy damping element 14 is typically made from a polyester material which is resistant to the growth of bacteria, mildew and mold. Further, the material is hydrophobic by nature and, therefore, dries quickly. In addition, such polyester material provides excellent wear resistance and will provide a long service life. [0042] The foregoing description of the preferred embodiments of the present invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Modifications or variations are possible in light of the above teachings. For example, each embodiment of the horizontal energy damping element 14 described above is made from a single layer of material. FIG. 8 illustrates an alternative embodiment wherein the horizontal energy damping element 14 is made from a laminate comprising a cure layer 60 of fiberglass reinforced polymer material sandwiched between two wear layers 70 of polyester based material such as the materials used to make the sleeve 22 described above. [0043] The embodiments were chosen and described to illustrate the principles of the invention and its practical application. It is clear that modifications and variations are within the scope of the invention as determined by the appended claims. The drawings and preferred embodiments do not and are not intended to limit the ordinary meaning of the claims in their fair and broad interpretation in any way.

Systems for shipping and operation dampening an appliance having a housing, a moveable tub member inside the housing, and a dampening portion are provided. The housing includes at least one sidewall, with the dampening portion disposed at least partially between the moveable tub member and the at least one side wall. The dampening portion includes a resilient material having at least one surface extending at least partially along the sidewall or tub member.

RELATED APPLICATIONS This application claims priority to, and incorporates by reference, U.S. provisional patent application No. 60/466,995, filed May 1, 2003, and U.S. provisional patent application No. 60/476,535, filed Jun. 6, 2003. TECHNICAL FIELD This application relates to electronic lighting systems. More specifically, the present invention relates to an electronic controller for striking, restriking and/or dimming a power-driven device such as a lamp, bulb or other lighting fixture. BACKGROUND Electronic controllers such as ballasts are commonly used for starting and restarting large lighting fixtures, such as those found in street lights, warehouse stores and the like. To start and/or restart such a lighting fixture, a ballast that delivers a very high current, and thus a very high power, has been required. This requirement significantly increases operating costs, especially when additional power is required to turn on a light. It also reduces the life of the bulb since a high current spike can stress and degrade the filament and/or gas contained within the bulb. Further, the conventional ballast is heavy and must be located near the bulb unless a very substantial wiring system is installed throughout the building or other location in which the bulbs are installed. Thus, it is desirable to develop an improved electronic lamp driver system that delivers a low start up current that is still capable of striking and restriking hot a bulb in a large lighting fixture such as lighting fixtures having bulbs in the range of 100 watts to 2000 watts. BRIEF SUMMARY A preferred embodiment of the invention provides an electronic device for starting and/or re-starting a power-driven device such as a lamp, bulb or lighting fixture. In an embodiment, the device includes an input stage, a rectifier stage, a power factor correction stage, and a coil device comprising a wound coil having a primary winding of multistranded wire. The circuit may automatically adjust to a range of wattages and/or loads. In an embodiment, the input stage accepts an AC input signal, the rectifier stage converts the AC input signal to a DC voltage level, and the coil device converts the DC signal to an AC output signal. The power factor correction stage may include a single-stage or a two-stage power factor correction controller. The device may also include a feedback stage, a filter stage, an output stage including a ballast controller and one or more MOSFETs, and/or a frequency adjustment circuit that adjusts the frequency of the AC output signal. In an embodiment, at least one of the stages includes a thermal cutout component. The power factor correction stage may also include a coil device having a primary winding of multistranded wire. The output coil device may be a choke or transformer when the device is used to control the delivery of power to one or more non-fluorescent bulbs. Alternatively, the coil device may include a secondary winding and serve as a transformer for the delivery of power to one or more fluorescent lamps. In an embodiment, the circuit may include an input stage, a rectifier stage, and a power factor correction stage, and it may provide an auto-ranging line voltage for the operation of a variety of loads. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates an embodiment of the present inventive lamp driver, in this illustration showing the driver being used to drive a non-fluorescent lamp, with an optional alternate output for two sets of fluorescent lamps, also shown. FIG. 2 illustrates an alternate embodiment of the lamp driver, in this case driving one non-fluorescent lamp and two fluorescent lamps. FIG. 3 illustrates input and filter stages of the embodiment of FIG. 1 . FIG. 4 illustrates elements of the DC rectifier stage of FIG. 1 . FIG. 5 illustrates exemplary elements of the power factor correction stage of FIG. 1 and the high voltage power filter stage of FIG. 1 . FIG. 6 illustrates exemplary elements of the output stage of FIG. 1 . FIG. 7 illustrates a prior art dimming circuit. FIG. 8 illustrates an embodiment of the feedback stage of FIG. 1 FIG. 9 illustrates an embodiment where the lamp driver drives a non-fluorescent lamp. FIG. 10 illustrates an embodiment where the lamp driver drives multiple fluorescent lamps. FIG. 11 is a block diagram of a prior art power factor correction circuit. DETAILED DESCRIPTION An embodiment of the present inventive lamp driver system is illustrated in FIG. 1 . As indicated in FIG. 1 , the exemplary system 100 may include as many as seven stages or more, each of which may provide additional features for the system. Referring to FIG. 1 , in the illustrated embodiment the first stage of the device 10 receives an input voltage and operates as an AC power supply. The input stage 10 may accept an input voltage that is at least between the range of 80 and 300 volts, with signal frequencies at approximately 50 to 60 kHz, although other voltages and frequencies are possible depending on the application. The second stage 20 functions as electromagnetic interference (EMI) filter. The third stage 30 functions as a DC rectifier, converting the AC input voltage to a DC voltage, with a connection to a feedback circuit. The fourth stage 40 operates as a power factor correction stage. The fifth stage 50 operates as a high-voltage power filter. The sixth stage 60 operates as the output stage to deliver power to one or more lamps or other devices. The seventh stage 70 is a general feedback stage. Although FIG. 1 as illustrated defines a boundary for the feedback stage 70 , the boundary is only intended to illustrate a portion of the feedback stage 70 . In fact, feedback is typically provided to each of stages 30 , 40 , 50 and 60 . As illustrated in FIG. 2 , in an alternate embodiment an external power source 110 that is not generally considered to be a stage of the device 100 may be provided. In the embodiment of FIG. 2 , power source 110 provides a low-voltage power source for the electronic devices in device 100 . FIG. 2 illustrates stages in a manner using a numbering system showing their correspondence to FIG. 1 . FIG. 3 through FIG. 10 provide additional detail of embodiments of the individual stages described above and illustrated in FIG. 1 . The values listed below for individual elements are exemplary values only and should not be interpreted as limiting. Persons skilled in the art will recognize that other values are possible without departing from the spirit and scope of the invention. Exemplary elements of input stage 10 and second stage 20 are illustrated in FIG. 3 . Referring to FIG. 3 , input stage 10 includes a power source, optionally between 80 and 300 volts and at signal frequencies between about 50 and about 60 kHz, or plug 16 at AC inputs 11 A and 11 B, a line fuse 12 , and two varistors 13 and 14 . In the illustrated embodiment, the power source may be a 120V, 50/60 kHz voltage source, and the line fuse 12 may be a 1.5 A fuse for a driver for a 150 watt lamp. When the circuit is used to light higher intensity lamps, larger fuses may be needed, such as a 5 amp fuse for a 400 watt bulb. Varistors or zener diodes 13 and 14 may function as surge protection devices connected between each of the AC inputs and ground 17 . When a power surge or voltage spike is exhibited on the AC inputs, the resistance of varistors or zener diodes 13 and 14 may quickly decrease, creating a shunt path for the over-voltage. In this way, other components in the device may be protected from power surges. The EMI filter stage 20 of the device may function as a noise filter. In the filter stage, an LC filter may be replicated between each AC input 11 A and 11 B and ground. The LC filters operate as noise filters to remove unwanted frequencies from the AC voltage input source. The LC filters may be composed of optional inductors 21 and 22 (not shown in FIG. 3 , but shown in the embodiment of FIG. 2 ), and capacitors 23 and 24 . In an embodiment, the inductors 21 and 22 may have an inductance of approximately 600 nH, and capacitors 23 and 24 may have a capacitance of approximately 2.2 nF. Capacitor 25 may have a capacitance of 0.15 μF. Other values are possible without departing from the spirit and scope of the invention. The DC rectifier stage 30 may convert the AC input signal into a DC voltage. Exemplary elements of the DC rectifier stage 30 are illustrated in FIG. 4 . Diode bridge 31 functions as a full wave bridge and converts the AC input voltage into a DC output voltage. Diode bridge 31 may be made of a full wave rectifier, or it may be four separate diodes, such as 4-amp diodes. The use of separate diodes instead of a rectifier is preferred for higher wattage drivers. Diode bridge 31 may be connected to the feedback stage 70 via the ground plane. The connection between diode bridge 31 and ground may stabilize the voltage differential across the bridge. Optional thermal cutout component 32 may operate as a temperature-sensitive, protective device to shut down the operation of diode bridge 31 in certain thermal conditions. For example, thermal component 32 may trigger a shut down when it senses an external temperature of 105° C., which may indicate a fire. Exemplary elements of the power factor correction stage 40 are illustrated in FIG. 5 . A coil device 41 operates to boost the output voltage based on the lamp or lamps (or other device or devices) attached to the output of device 100 . A coil device 41 using multistranded wire is described in co-pending U.S. patent application Ser. No. 10/834,778, entitled “Coil Device”, filed Apr. 29, 2004, which is incorporated herein by reference in its entirety. Other coil devices are possible without departing from the spirit and scope of the invention. The coil device preferably includes a secondary winding when it is used as a power circuit for the ballast. The power factor correction circuit may be used to make a nonlinear load operate like a resistive load by putting it into phase. This correction may also help to reduce total harmonic distortion. In one embodiment, the power factor correction controller 42 may be a Fairchild Semiconductor FAN7527 or similar device. The power factor correction controller 42 may be used along with one or more resistors 44 - 48 ; one or more capacitors 49 , 141 and 144 ; one or more diodes 142 and 143 ; a coil device 41 ; and MOSFET 147 to create a power factor correction circuit. In one embodiment corresponding to FIG. 2 , resistors 43 , 44 , 45 , 46 , 47 and 48 may have resistances of approximately 150 kΩ, 47Ω, 22 kΩ, 2.1 MΩ, 14.7 kΩ and 1Ω, respectively, and capacitors 49 , 141 and 144 may have capacitances of approximately 0.01 μF, 100 MF and 0.22 μF, respectively with capacitor 145 and its corresponding wiring not being present. In an alternate embodiment corresponding to FIG. 1 , resistors 43 , 44 , 45 , 46 , 47 and 48 may have values of approximately 180Ω, 10Ω, 22 kΩ, 2.2 MΩ, 27 kΩ, and 0.25Ω, respectively, while capacitors 49 , 141 , 144 and 145 may have values of approximately 1 nf, 0.47 μF, 1 μF and 1 MF, respectively. The embodiment shown in FIGS. 1 and 5 may also include a diode 151 . In the embodiment illustrated in FIG. 5 , the power factor correction device 42 includes a two-stage power factor correction microchip. An example of such a microchip is the FAN7527B supplied by Fairchild Semiconductor. Unlike the prior art, which used three-stage or other microchips, the two-stage microchip provides several advantages in that it uses substantially the same frequency for pre-startup heating and actual startup, thus providing a power saving advantage. The pre-startup heating and actual startup frequency may each be, for example, approximately three times normal operating frequency. The operation of a prior power factor correction circuit is described in Fairchild Application Note AN4107, published May 2000, and is illustrated in FIG. 11 . Exemplary elements of a high voltage power filter stage 50 are also illustrated in FIG. 5 . For a 150 watt unit, stage 50 may incorporate resistor 51 and variable resistor 52 . In an embodiment, resistor 51 may have a resistance of about 1.1 MΩ, and variable resistor 52 may have a peak resistance of about 10 kΩ. The optional variable resistor 52 may be used to adjust the frequency of the output signal by changing its voltage, since a higher voltage will result in a higher frequency. A higher frequency may also change the wavelength of the output signal. Optional resistor 148 , such as a 6 kΩ resistor, may also be used. In an embodiment, the frequency of the output signal may be varied so that the lamp or lamps connected to the output of the ballast device may create light emissions of varying wavelengths, selected based on the attributes of the bulb or load to be driven. For example, a high pressure sodium bulb may handle a lower frequency, such as 20-40 kHz, while a xenon bulb may require a higher frequency, such as 150 kHz or more. In an alternate embodiment, the variable resistor may be set to a constant value to achieve a known frequency and create light emissions of a known wavelength. Capacitor 53 illustrated in FIG. 5 may have a resistance of between 47 MF and 100 MF. Other values are possible. Preferred elements of an output stage 60 are illustrated in FIG. 6 . Referring to FIG. 6 , a controller 61 may be implemented by a ballast controller such as a Fairchild Semiconductor KA7540 or KA7541 or a similar device. The controller 61 is used to produce the high output voltage required to drive the output MOSFETs 62 and 63 in conjunction with a standard gate driver 64 . The MOSFETs 62 and 63 blend the injected frequency component output from stage 50 and the high voltage driven from the standard gate driver 64 to produce the proper signal to the lamps and/or bulbs. The drain port of MOSFET 62 is driven by stage 50 at a high voltage (such as 400 volts) and receives a pulse input at a frequency determined by the variable resistor 52 . The resulting output of MOSFETs 62 and 63 may be a switching DC square wave or substantially square wave. Preferred, although not required, values for various elements in FIG. 6 are that resistors 263 , 65 , 66 , 67 , 68 and 69 may be approximately 51Ω, 51Ω, 150 KΩ, 22 KΩ, 51Ω and 51Ω, respectively. Variable resistors 261 and 262 may each have values of up to 1 KΩ. Capacitors 162 , 163 , 164 , and 165 may be approximately 100 pF, 0.22 μF, 47 MF, and 0.27 μF, respectively. Varistor 167 may be a 15 volt Zener diode. Diodes 265 , 266 , 267 and 268 may be, for example, 300 volt diodes. In each case, other values are possible. The use of a Fairchild Semiconductor KA7540 as controller 60 may allow for enhanced restriking capability when the circuit is used for non-fluorescent bulbs. However, in an alternate embodiment, a different controller 61 such as a Fairchild Semiconductor KA7541 may be used. In such a case, one skilled in the art will recognize that the dimming circuit inside the KA7540 is not present in the KA7541, and that such dimming capability may need to be replicated or otherwise added to the lamp driver in order to restrike a non-fluorescent bulb. An illustration of the prior art dimming circuit of the KA7450, as presented in the Fairchild Semiconductor product specification, is presented in FIG. 7 . Another option may be to include a capacitor which will allow a high starting current with gradual dimming. Referring to FIG. 8 , feedback stage 70 is a general feedback stage in which the output voltage level is transmitted to other stages to permit for corrections in the total voltage differential in the circuit. Referring to FIG. 8 , exemplary values for resistors 71 , 72 , 73 , 74 , 75 , 76 , 77 and 78 are maybe 10 KΩ, 100 KΩ, 442 KΩ, 220 KΩ, 180 KΩ, 10 KΩ, 200 KΩ and 442 KΩ, respectively, while exemplary values of capacitors 171 , 172 , and 173 may be 1 nF, 1 mF and 1 nF, respectively. Other values are possible. Optional indicator light 177 may provide an indication of when the bulb is restriking. The feedback stage 70 may also serve as a circuit to turn off MOSFETs 62 and 63 when a bulb is not installed in the system. Although FIG. 8 illustrates a boundary for the feedback stage 70 , the boundary is only intended to illustrate a portion of the feedback stage 70 . In fact, feedback is typically provided to each of stages 30 , 40 , 50 and 60 . The output waveform of the device may drive one or more lamps, one or more bulbs, or any combination of the two or other devices. Referring to FIG. 9 , if one or more non-fluorescent bulbs 91 are driven, a coil device 82 similar to the one illustrated in stage 40 may be used to convert the DC square wave output from stage 60 of the ballast device into an AC sine wave. An exemplary coil device 82 is the multistranded wire device with a secondary winding as illustrated in pending U.S. patent application Ser. No. 10/834,778, filed Apr. 29, 2004, entitled “Coil Device”, which is incorporated herein by reference in its entirety. Such a device may include a primary winding of multistranded wire, such as that commonly known as litz wire. The coil device includes a conductive core positioned inside the primary winding and outside the primary winding. The core that is positioned inside the primary winding may include an air gap. The primary winding is preferably covered by an insulating layer. In this case, a secondary winding may not be required and the device may be used as a choke. Referring again to FIG. 9 , exemplary values for capacitors 95 and 96 are 0.68 μF (for a 400 volt line) and 0.012 μF, respectively. Referring to FIG. 10 , if one or more fluorescent lamps 90 A- 90 D are driven, the coil device 81 illustrated in co-pending U.S. patent application Ser. No. 10/834,778, entitled “Coil Device”, filed Apr. 29, 2004, may also be used. An optional secondary winding may also be provided around the primary winding to allow the device to operate as a transformer. Optionally, the secondary winding may also be made of multistranded wire. If two or more fluorescent lamps are connected, they may be connected in series as illustrated in FIG. 10 . Each combination of two fluorescent lamps preferably has a single associated coil device. If two or more non-fluorescent bulbs are used (such as metal halide bulbs), each non-fluorescent bulb preferably has its own coil device as illustrated in FIG. 9 . Additional configurations with additional lamps are possible. The present inventive ballasts may be used to light a variety of bulbs, and in an embodiment the ballasts automatically adjust to the value of the load. Thus, one ballast can be used to operate lamps of varying wattages, such as those ranging from 150 watts to 400 watts in an embodiment. Optionally, it may also be lighter in weight than many conventional ballasts. In examples, in one embodiment the lamp driver was used in connection with a ballast controller to light a metal halide lamp, and it was found that the device automatically adjusted to a 1-amp current flow for a 150-watt lamp and a 3.4-amp current flow for a 400-watt lamp. Certain embodiments of the lamp driver may be separated from the lamp by a wire distance of as much as 200 feet or more without any significant loss of output. It is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in this description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Hence, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods, and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.

An electronic device for starting and/or re-starting a power-driven device such as a lamp, bulb or lighting fixture includes an input stage, a rectifier stage, a power factor correction stage with total harmonic distortion correction, and a coil device comprising a wound coil having a primary winding of multistranded wire. The circuit may automatically adjust to a range of loads, and/or it may provide an auto-ranging line voltage. In an embodiment, the input stage accepts an AC input signal, the rectifier stage converts the AC input signal to a DC signal, and the coil device converts the DC signal to an AC output signal. The device may also include a frequency adjustment circuit that adjusts the frequency of the AC output signal to assistance in the performance of a restart function.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to charge pumps and, more particularly, to a cross-coupled, dual-chain charge pump, that is referred here as a bootstrapped charge pump. 2. Description of the Related Art Historically, semiconductor devices that required voltages that were greater than the power supply voltage utilized dedicated pins to input the required voltages from an off-chip supply. Current-generation non-volatile memory devices, however, commonly use a charge pump, which utilizes the power supply voltage and ground, to generate the required voltages on the chip. Thus, by utilizing a charge pump, dedicated pins are no longer required to input voltages from an off-chip supply that are greater than the power supply voltage. As a result, the total pin count of a device can be reduced accordingly. This is a significant advantage to current-generation chips that often have a limited number of pins available. Although charge pumps can provide the needed voltages from the power supply voltage and ground, charge pumps typically suffer from a low current drive (can source only a limited amount of current). FIG. 1 shows a schematic diagram that illustrates a conventional charge pump 100 . As shown in FIG. 1, charge pump 100 includes a number of stages SG 1 -SGn that are serially connected together to form a chain. Each stage SG in the chain progressively “pumps” or increases the voltage input to the stage to achieve the needed voltage. Stages SG 1 -SGn include a corresponding number of input nodes NI 1 -NIn, output nodes NO 1 -NOn, and diode-connected n-channel transistors DN 1 -DNn. Each transistor DN has a gate and drain connected to an input node NI and a source connected to an output node NO. In addition, stages SG 1 -SGn also include a corresponding number of capacitors CAP 1 -CAPn, switching nodes NS 1 -NSn, and switches SW 1 -SWn. Each capacitor CAP is connected between an output node NO and a switching node NS. Each switch SW, in turn, is connected to a switching node NS, and either a power supply voltage VCC or ground, depending on the logic state of a clock signal. As further shown in FIG. 1, first stage SG 1 receives an input voltage VI such as the power supply voltage VCC, while last stage SGn outputs a pumped voltage VPM on output node NOn. The output node NO of each remaining stage is connected to the input node NI of the next stage SG in the chain. In operation, the switch SW in each odd-numbered stage SG is controlled by a first clock signal PH 1 , while the switch SW in each even-numbered stage SG is controlled by a second clock signal PH 2 that is 180° out-of-phase with the first clock signal PH 1 . For both clock signals PH 1 and PH 2 , when the clock signal is asserted, the switch SW is connected to ground. On the other hand, when the clock signal is de-asserted, the switch is connected to the power supply voltage VCC. Thus, when the first clock signal PH 1 is asserted, first switch SW 1 is connected to ground. In this condition, the gate-to-source voltage VGS of transistor DN 1 is greater than the threshold voltage VTH 1 of transistor DN 1 . As a result, transistor DN 1 turns on and a current flows from the input node NI 1 to the output node NO 1 until the voltage VO on output node NO 1 rises to a value that is a threshold voltage drop less than the power supply voltage VCC. When the voltage VO on output node NO 1 is a threshold voltage drop less than the power supply voltage VCC (VO=VCC−VTH 1 ), transistor DN 1 turns off as transistor DN 1 conducts only as long as the gate-to-source voltage VGS is greater than the threshold voltage VTH 1 . As a result, the voltage across capacitor CAP 1 is also equal to VCC−VTH 1 . When the first clock signal PH 1 is de-asserted, switch SW 1 of the first stage SG 1 is connected to the power supply voltage VCC. Since transistor DN 1 is turned off, thereby isolating output node NO 1 from the input node NI 1 , the power supply voltage VCC on switching node SW 1 also appears on output node NO 1 due to the principle of charge neutrality. As a result, the voltage VO 1 on the output node NO 1 is defined in equation EQ. 1 as: VO 1 =VCC−VTH 1 + VCC= 2 VCC−VTH 1 .  EQ. 1 Thus, the voltage VO 1 on output node NO 1 is greater by the power supply voltage VCC when the first clock signal PH 1 is de-asserted. At the same time that the first clock signal PH 1 is de-asserted, the second clock signal PH 2 is asserted which, in turn, causes switch SW 2 to be connected to ground. As with transistor DN 1 , transistor DN 2 turns on until the voltage VO 2 on output node NO 2 is a threshold voltage drop less than the voltage on input node NI 2 /output node NO 1 . The voltage VO 2 on output node NO 2 takes several clock cycles to reach 2VCC−VTH 1 −VTH 2 . This is because, unlike transistor DN 1 where the current is delivered from the power supply voltage VCC, the current flowing into the output node NO 2 from input node NI 2 /output node NO 1 reduces the voltage on input node NI 2 /output node NO 1 , and thus, additional cycles are needed for the nodes to reach their full potentials. When the second clock signal PH 2 is de-asserted, switch SW 2 is connected to the power supply voltage VCC which, in turn, causes the voltage VO 2 on output node NO 2 to be increased by the power supply voltage VCC. This process continues as described above. Thus, charge pump 100 shifts electrons from the output node NO to the input node NI of each stage SG until the pumped voltage VPM on output node NOn is equal to: VPM=n ( VCC )−( VTH 1 +VTH 2 + . . . +VTHn ).  EQ. 2 (The pumped voltage VPM is actually slightly less due to the body effect of the transistors DN in each stage SG.) One disadvantage of charge pump 100 is that the pump voltage VPM is reduced by the combined threshold voltage drops (VTH 1 +VTH 2 + . . . +VTHn). The transistors in the charge pump, being configured as diodes, do not act as ideal switches, as in the case of an ideal charge pump. Further, the drive strength of the pump is greatly reduced when current is drawn from the pump. In some cases, an additional stage SG may need to be added to compensate for this loss, thereby increasing the size and cost of the charge pump. Thus, there is a need for a charge pump that outputs a pumped voltage VPM that is not reduced by the accumulated threshold voltage drops. SUMMARY OF THE INVENTION The charge pump of the present invention outputs a pumped voltage that is not reduced by the accumulated threshold voltage drops by utilizing a dual-chain charge pump where the pumped voltages from each charge pump chain drive the gates of the other charge pump chain. As a result, the voltages on the gates of the transistors are pumped up to be at least one diode drop greater than the voltages on the drains of the n-channel transistors, and one diode drop less than the voltages on the sources of the p-channel transistors. In the charge pump of the present invention, the diode drops associated with the transistors are eliminated as a result of the pumped voltages on the drains/sources of the transistors of each pump that gets coupled to the gates of the transistors of the other pump. This makes the transistors act as ideal switches, and thus, enables the voltages on the sources/drains of the transistors to reach their full potentials, without being limited by their threshold voltages. Thus, this cross-coupled charge pump exhibits a bootstrapping phenomena, as the sources/drains are bootstrapped to reach their full potentials. Hence, the charge pump of the present invention is referred to as a bootstrapped charge pump. A charge pump stage in accordance with the present invention includes a bottom transistor and a top transistor. The bottom transistor has a first node, a gate, and a second node. The top transistor has a third node, a gate connected to the second node of the bottom transistor, and a second node connected to the gate of the bottom transistor. The charge pump stage also includes a bottom capacitor that is connected between the second node of the bottom transistor and a first clock signal, and a top capacitor that is connected between the second node of the top transistor and a second clock signal. The second clock signal is out-of-phase and non-overlapping with the first clock signal. A charge pump in accordance with the present invention includes a plurality of stages that are connected together in series. Each stage has a bottom transistor and a top transistor. The bottom transistor has a first node, a gate, and a second node, while the top transistor has a first node, a gate connected to the second node of the bottom transistor, and a second node connected to the gate of the bottom transistor. Each stage also has a bottom capacitor that is connected between the second node of the bottom transistor and either a first clock signal or a second clock signal. The first clock signal is connected when a stage is an odd-numbered stage, while the second clock signal is connected when a stage is an even-numbered stage. Each stage further has a top capacitor that is connected between the second node of the top transistor and either the first clock signal or the second clock signal. The first clock signal is connected when a stage is an even-numbered stage, while the second clock signal is connected when a stage is an odd-numbered stage. The second clock signal is out-of-phase and non-overlapping with the first clock signal. The plurality of stages are connected together so that, excluding a last stage, the second nodes of the bottom and top transistors in each stage are connected to the first nodes of the bottom and top transistors, respectively, in an adjacent stage, and so that, excluding a first stage, the first nodes of the bottom and top transistors in each stage are connected to the second nodes of the bottom and top transistors, respectively, in an adjacent stage. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description and accompanying drawings which set forth an illustrative embodiment in which the principles of the invention are utilized. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram illustrating a conventional charge pump 100 . FIG. 2 is a schematic diagram illustrating a charge pump 200 in accordance with the present invention. FIG. 3 is a schematic diagram illustrating a charge pump 300 in accordance with the present invention. FIG. 4 is a schematic diagram illustrating a charge pump 400 in accordance with the present invention. FIG. 5 is a schematic diagram illustrating a charge pump 500 in accordance with the present invention. FIG. 6 is a schematic diagram illustrating a charge pump 600 in accordance with the present invention. FIG. 7 is a schematic diagram illustrating a charge pump 700 in accordance with the present invention. FIG. 8 is a schematic diagram illustrating a charge pump 800 in accordance with the present invention. FIG. 9 is a schematic diagram illustrating a charge pump 900 in accordance with the present invention. DETAILED DESCRIPTION FIG. 2 shows a schematic diagram that illustrates a charge pump 200 in accordance with the present invention. As shown in FIG. 2, charge pump 200 includes a number of stages SG 1 -SGn that are serially connected together to form a chain. The stages SG 1 -SGn have a number of bottom transistors BT 1 -BTn and a corresponding number of top transistors TT 1 -TTn. Each bottom transistor BT in a stage SG has a drain, a gate, and a source. Each top transistor TT in the stage SG has a drain, a gate connected to the source of the bottom transistor BT, and a source connected to the gate of the bottom transistor BT. The stages SG 1 -SGn also have a number of bottom capacitors BC 1 -BCn and a corresponding number of top capacitors TC 1 -TCn. Each bottom capacitor BC in a stage SG is connected between the source of a bottom transistor BT and either a first clock signal PH 1 or a second clock signal PH 2 . The first clock signal PH 1 is utilized when the stage SG is an odd-numbered stage, while the second clock signal PH 2 is utilized when the stage SG is an even-numbered stage. In addition, each top capacitor TC in a stage SG is connected between the source of the top transistor TT and either the first clock signal PH 1 or the second clock signal PH 2 . The first clock signal PH 1 is utilized when the stage SG is an even-numbered stage, while the second clock signal PH 2 is utilized when the stage SG is an odd-numbered stage. The second clock signal PH 2 is out-of-phase and non-overlapping with the first clock signal PH 1 . In addition, both clock signals PH 1 and PH 2 alternate between a logic high voltage level such as the power supply voltage VCC, and a logic low voltage level such as ground (the logic low level can also be negative). Stages SG 1 -SGn are connected together so that, with the exception of the last stage SGn, the sources of the bottom and top transistors BT and TT in each stage SG are connected to the drains of the bottom and top transistors BT and TT, respectively, in an adjacent stage SG. In addition, the drains of both the bottom and top transistors BT 1 and TT 1 in the first stage SG 1 are connected to receive the input voltage VIN (such as the power supply voltage VCC). Further, the sources of the bottom and top transistors BTn and TTn in the last stage SGn output a pumped bottom voltage PBV, and a pumped top voltage PTV, respectively. The operation of charge pump 200 is illustrated with a two-stage charge pump. When the clock signal PH 1 falls to the logic low voltage level, a logic low potential approximately equal to the logic low voltage level is capacitively coupled to the source of bottom transistor BT 1 . Due to the cross coupling, the logic low potential is also coupled to the gate of top transistor TT 1 . When the clock signal PH 2 rises to the logic high voltage level, a logic high potential approximately equal to the logic high voltage level is capacitively coupled to the source of top transistor TT 1 , and to the gate of bottom transistor BT 1 . In this condition, the gate-to-source voltage of bottom transistor BT 1 is greater than its threshold voltage. As a result, bottom transistor BT 1 turns on and the voltage on the source of bottom transistor BT 1 rises to a value that is equal to the logic high potential less the threshold voltage of bottom transistor BT 1 . The gate-to-source voltage of top transistor TT 1 , on the other hand, is less than its threshold voltage. As a result, top transistor TT 1 is turned off. When the clock signal PH 2 switches back to the logic low voltage level from the logic high voltage level, the logic low potential is capacitively coupled to the source of top transistor TT 1 . Due to the cross coupling, the logic low potential is also coupled to the gate of bottom transistor BT 1 . When the clock signal PH 1 rises to the logic high voltage level, the logic high potential is capacitively coupled to the source of bottom transistor BT 1 . However, since a voltage equal to the logic high potential less the threshold voltage of bottom transistor BT 1 is already on the source of bottom transistor BT 1 , the capacitively coupled logic high potential raises the potential on the source of bottom transistor BT 1 . The potential is raised by the difference between the logic low potential and the logic high potential to a potential equal to twice the logic high potential less the threshold voltage of bottom transistor BT 1 . Due to the cross coupling, this same potential, which is more than one threshold voltage drop greater than the voltage on the drain of top transistor TT 1 , also sits on the gate of top transistor TT 1 . Thus, the voltage on the source of top transistor TT 1 rises to the input voltage VIN. When the clock signal PH 1 switches back to the logic low voltage level from the logic high level, the logic low potential is capacitively coupled to the source of bottom transistor BT 1 . This reduces the potential on the source from twice the logic high potential less the threshold voltage of the bottom transistor to a single logic high potential less the threshold voltage of the bottom transistor. Due to the cross coupling, the same potential also sits on the gate of top transistor TT 1 . When the clock signal PH 2 again rises to the logic high voltage level, the logic high potential is capacitively coupled to the source of top transistor TT 1 . However, since a voltage equal to the input voltage VIN is already on the source of top transistor TT 1 , the capacitively coupled logic high potential raises the potential on the source of top transistor TT 1 . The potential is raised by the value of the logic high potential so that a potential equal to the input voltage plus the logic high potential is on the source of top transistor TT 1 . Due to the cross coupling, this same potential, which is more than one threshold voltage drop greater than the voltage on the drain of bottom transistor BT 1 , also sits on the gate of bottom transistor BT 1 . Thus, the voltage on the source of bottom transistor BT 1 rises to the input voltage VIN. Thus, as the first clock signal PH 1 switches between the logic low voltage level and the logic high voltage level, the potential on the source of bottom transistor BT 1 switches between the input voltage VIN and the input voltage VIN plus the logic high potential. Similarly, as the second clock signal PH 2 switches between the logic low voltage level and the logic high voltage level, the potential on the source of top transistor TT 1 switches between the input voltage VIN and the input voltage VIN plus the logic high potential. Since the logic high potential is approximately equal to the input voltage VIN, the potentials on the sources of the bottom and top transistors of stage SG 1 roughly swing between VIN and 2 VIN. Thus, in accordance with the present invention, charge pump 200 provides pumped voltages that are not reduced by the threshold voltages of the pumping transistors. When stage SG 2 is added, the adjoining bottom transistors are switched on and off out-of-phase so that when one transistor is on, the adjoining transistors are off. This allows the highest potential from stage SG 1 to become the lowest potential of stage SG 2 . Thus, the final predischarge potential on the source of bottom transistor BT 2 in stage SG 2 switches between the highest potential that is on the source of bottom transistor BT 1 , and this potential plus the logic high potential. Similarly, the adjoining top transistors are switched on and off out-of-phase so that when one transistor is on, the adjoining transistors are off. This allows the highest potential from stage SG 1 to become the lowest potential of stage SG 2 . Thus, the final predischarge potential on the source of top transistor TT 2 in stage SG 2 switches between the highest potential that is on the source of top transistor TT 1 , and this potential plus the logic high potential. Since the logic high potential is approximately equal to the input voltage VIN, the potentials on the sources of the bottom and top transistors of stage SG 2 roughly swing between 2VIN and 3VIN. Thus, for n stages, the final potential on the source of the bottom transistor of the nth stage switches between the input voltage VIN plus n−1 times the logic high potential; and the input voltage VIN plus n times the logic high potential. Similarly, the final potential on the source of the top transistor of the nth stage switches between the input voltage VIN plus n−1 times the logic high potential; and the input voltage VIN plus n times the logic high potential. When additional stages are utilized, it takes a number of clock cycles before the sources of the bottom and top transistors BTn and TTn in the last stage SGn reach their final predischarge potentials. With the bottom and top transistors BT 1 and TT 1 in the first stage SG 1 , the currents to the sources are delivered by the power supply voltages VCC on the drains. However, the drains of the top and bottom transistors of an additional stage SG, which are otherwise electrically isolated, are able to conduct a part of the currents to the sources of the additional stage as long as the increasing source potential does not turn off the transistor. Thus, it takes a number of clock cycles to shift or pump the charge to the sources of the transistors in the last stage SGn from the input voltage VIN connected to the drains on the transistors in the first stage SG 1 . The larger the difference between the logic low voltage level and the logic high voltage level, the greater the amount of charge that can be pumped each cycle. FIG. 3 shows a schematic diagram that illustrates a charge pump 300 in accordance with the present invention. Charge pump 300 is similar to charge pump 200 and, as a result, utilizes the same reference numerals to designate the structures that are common to both pumps. As shown in FIG. 3, pump 300 differs from pump 200 in that pump 300 includes a first diode-connected transistor DT 1 and a second diode-connected transistor DT 2 . Transistor DT 1 has a drain and a gate connected to the source of the top transistor TTn in the last stage SGn, and a source connected to an output node NOUT. Transistor DT 2 has a drain and a gate connected to the source of the bottom transistor BTn in the last stage SGn, and a source connected to the output node NOUT. In operation, the voltage on the source of transistor DT 1 has an approximately square waveform that switches between first and second voltages. The first voltage is equal to the input voltage VIN plus n−1 times the logic high potential less the threshold voltage of transistor DT 1 . The second voltage is equal to the input voltage VIN plus n times the logic high potential less the threshold voltage of transistor DT 1 . Similarly, the voltage on the source of transistor DT 2 has an approximately square waveform that switches between first and second voltages. The first voltage being equal to the input voltage VIN plus n−1 times the logic high potential less the threshold voltage of transistor DT 2 . The second voltage being equal to the input voltage VIN plus n times the logic high potential less the threshold voltage of transistor DT 2 . The voltages on the sources of transistors DT 1 and DT 2 are 180° out-of-phase such that the first voltage on the source of transistor DT 1 and the second voltage on the source of transistor DT 2 are present at the same time. As a result, an approximately constant voltage equal to the input voltage VIN plus n times the logic high potential less the threshold voltage of transistor DT 1 (the threshold voltages of transistors DT 1 and DT 2 are assumed to be the same) is present on the output node NOUT. FIG. 4 shows a schematic diagram that illustrates a charge pump 400 in accordance with the present invention. Charge pump 400 is similar to charge pump 200 and, as a result, utilizes the same reference numerals to designate the structures that are common to both pumps. As shown in FIG. 4, pump 400 differs from pump 200 in that pump 400 includes an n-channel first transistor Q 1 and an n-channel second transistor Q 2 . First transistor Q 1 has a drain connected to the source of the bottom transistor BTn in the last stage SGn, a gate, and a source connected to an output node NOUT. Second transistor Q 2 has a drain connected to the source of the top transistor TTn in the last stage SGn, a gate, and a source connected to the output node NOUT. Pump 400 also includes an n-channel third transistor Q 3 and an n-channel fourth transistor Q 4 . Third transistor Q 3 has a drain connected to the source of transistor Q 1 and the output node NOUT, a gate connected to the gate of transistor Q 1 , and a source. Fourth transistor Q 4 has a drain connected to the source of transistor Q 2 and the output node NOUT, a gate connected to the gate of transistor Q 2 and the source of transistor Q 3 , and a source connected to the gate of transistor Q 3 . Pump 400 additionally includes a bottom capacitor CAP 1 and a top capacitor CAP 2 . Bottom capacitor CAP 1 is connected between the source of transistor Q 3 and the clock signal that is the same as the clock signal that is connected to the top capacitor TCn in the last stage SGn. Top capacitor CAP 2 is connected between the source of transistor Q 4 and the clock signal that is the same as the clock signal that is connected to the bottom capacitor BCn in the last stage SGn. Bottom and top capacitors CAP 1 and CAP 2 can be, for example, about one-tenth as large as the bottom and top capacitors BC and TC. In operation, the voltages on the sources of transistors Q 3 and Q 4 are pumped up in the same way as if transistors Q 3 and Q 4 were the bottom and top transistors BT and TT of another stage SG. As noted above, for n stages, the final potential on the source of the bottom transistor BTn of the nth stage switches between the input voltage VIN plus n−1 times the logic high potential; and the input voltage VIN plus n times the logic high potential. Similarly, the final potential on the source of the top transistor TTn of the nth stage switches between the input voltage VIN plus n−1 times the logic high potential; and the input voltage VIN plus n times the logic high potential. Thus, the final potentials on the sources of transistors Q 3 and Q 4 switch between the input voltage VIN plus n times the logic high potential; and the input voltage VIN plus n+1 times the logic high potential. As a result, the highest final potentials on the sources of transistors Q 3 and Q 4 are both one logic high potential greater than the highest final potentials on the sources of the bottom and top transistors BTn and TTn of the last stage SGn. Due to the cross coupling, when the potential on the source of the bottom transistor BTn of the last stage SGn switches to its highest potential, the voltage on the gates of transistors Q 1 and Q 3 also switches to its highest potential. This, in turn, causes the potential on the output node NOUT to rise to the highest potential that is on the source of the bottom transistor BTn of the last stage SGn. Similarly, when the potential on the source of the top transistor TTn of the last stage SGn switches to its highest potential, the voltage on the gates of transistors Q 2 and Q 4 also switches to its highest potential. This, in turn, causes the potential on the output node NOUT to rise to the highest potential that is on the source of the top transistor TTn of the last stage SGn. The voltage on the source of transistor Q 1 has an approximately square waveform that switches between first and second voltages. The first voltage is equal to the input voltage VIN plus n−1 times the logic high potential. The second voltage is equal to the input voltage VIN plus n times the logic high potential. Similarly, the voltage on the source of transistor Q 2 has an approximately square waveform that switches between first and second voltages. The first voltage being equal to the input voltage VIN plus n−1 times the logic high potential. The second voltage being equal to the input voltage VIN plus n times the logic high potential. The voltages on the sources of transistors Q 1 and Q 2 are 180° out-of-phase such that the first voltage on the source of transistor Q 1 and the second voltage on the source of transistor Q 2 are present at the same time. As a result, an approximately constant voltage equal to the input voltage VIN plus n times the logic high potential is present on the output node NOUT. Thus, charge pump 400 eliminates the threshold voltage drop associated with the voltage output from charge pump 300 . FIG. 5 shows a schematic diagram that illustrates a charge pump 500 in accordance with the present invention. Charge pump 500 is similar to charge pump 400 and, as a result, utilizes the same reference numerals to designate the structures that are common to both pumps. As shown in FIG. 5, pump 500 differs from pump 400 in that pump 500 includes a pair of n-channel transistors N 1 and N 2 that are used to enable or disable pump 500 . Transistor N 1 has a drain connected to the gate of transistor Q 2 , a gate connected to receive a control signal CNT, and a source connected to ground. Transistor N 2 has a drain connected to the gate of transistor Q 1 , a gate connected to receive the control signal CNT, and a source connected to ground. In operation, when the control signal CNT is low, the gates of the transistors Q 1 -Q 4 are unaffected by transistors N 1 and N 2 , and thus enabling the pump to operate normally. However, when the control signal CNT is high, the gates of transistors Q 1 -Q 4 are pulled to ground, thereby turning transistors Q 1 -Q 4 , and as a result, the whole pump off. The present invention can also be utilized to pump negative voltages from a supply voltage by exchanging p-channel transistors for the n-channel transistors. FIG. 6 shows a schematic diagram that illustrates a charge pump stage 600 in accordance with the present invention. As shown in FIG. 6, charge pump 600 includes a number of stages NSG 1 -NSGn that are serially connected together to form a chain. The stages NSG 1 -NSGn have a number of bottom transistors NBT 1 -NBTn and a corresponding number of top transistors NTT 1 -NTTn. Each bottom transistor NBT in a stage NSG has a drain, a gate, and a source. Each top transistor NTT in the stage NSG has a source, a gate connected to the drain of the bottom transistor NBT, and a drain connected to the gate of the bottom transistor NBT. The stages NSG 1 -NSGn also have a number of bottom capacitors NBC 1 -NBCn and a corresponding number of top capacitors NTC 1 -NTCn. Each bottom capacitor NBC in a stage NSG is connected between the drain of a bottom transistor NBT and either the first clock signal PH 1 or the second clock signal PH 2 . The first clock signal PH 1 is utilized when the stage NSG is an odd-numbered stage, while the second clock signal PH 2 is utilized when the stage NSG is an even-numbered stage. In addition, each top capacitor NTC in a stage NSG is connected between the source of the top transistor NTT and either the first clock signal PH 1 or the second clock signal PH 2 . The first clock signal PH 1 is utilized when the stage NSG is an even-numbered stage, while the second clock signal PH 2 is utilized when the stage NSG is an odd-numbered stage. The second clock signal PH 2 is out-of-phase and non-overlapping with the first clock signal PH 1 . In addition, both clock signals PH 1 and PH 2 alternate between a logic high voltage level such as the power supply voltage VCC, and a logic low voltage level such as ground (the logic low level can also be negative). Stages NSG 1 -NSGn are connected together so that, with the exception of the last stage NSGn, the drains of the bottom and top transistors NBT and NTT in each stage NSG are connected to the sources of the bottom and top transistors NBT and NTT, respectively, in an adjacent stage NSG. In addition, the sources of both the bottom and top transistors NBT 1 and NTT 1 in the first stage NSG 1 are connected to receive the input voltage VIN (such as the power supply voltage VCC). Further, the drains of the bottom and top transistors NBTn and NTTn in the last stage NSGn output a pumped bottom voltage NPBV, and a pumped top voltage NPTV, respectively. The operation of charge pump 600 is illustrated with a two-stage charge pump. When the clock signal PH 1 rises to the logic high voltage level, a logic high potential approximately equal to the logic high voltage level is capacitively coupled to the drain of bottom transistor NBT 1 . Due to the cross coupling, the logic high potential is also coupled to the gate of top transistor NTT 1 . When the clock signal PH 2 falls to the logic low voltage level, a logic low potential approximately equal to the logic low voltage level is capacitively coupled to the drain of top transistor NTT 1 , and to the gate of bottom transistor NBT 1 . In this condition, the gate-to-source voltage of bottom transistor NBT 1 is less (more negative) than the threshold voltage (which is negative) of bottom transistor NBT 1 . As a result, bottom transistor NBT 1 turns on and the voltage on the drain of bottom transistor NBT 1 rises to that of input voltage VIN. The gate-to-source voltage of top transistor NTT 1 , on the other hand, is greater than the threshold voltage of top transistor NTT 1 . As a result, top transistor NTT 1 is turned off and the voltage on its drain resides at the logic low voltage level. When the clock signal PH 2 switches back to the logic high voltage level from the logic low voltage level, the logic high potential is capacitively coupled to the drain of top transistor NTT 1 . Due to the cross coupling, the logic high potential is also coupled to the gate of bottom transistor NBT 1 . When the clock signal PH 1 falls to the logic low voltage level, the logic low potential is capacitively coupled to the drain of bottom transistor NBT 1 . However, since a voltage equal to the value of input voltage VIN is already on the drain of bottom transistor NBT 1 , the capacitively coupled logic low potential reduces the potential on the drain of bottom transistor NBT 1 . The potential is reduced by the difference between the logic low potential and the logic high potential. However, since in most cases, the logic high potential and the input voltage VIN equal the supply voltage VCC, the drain voltage is reduced to zero. Due to the cross coupling, this same zero potential also sits on the gate of top transistor NTT 1 , and thus, passes the input voltage VIN onto the drain of top transistor NTT 1 . Therefore, voltages on the drains of the bottom and top transistors NBT 1 and NTT 1 in stage NSG 1 oscillate between VIN and ground. In stage NSG 2 , when the clock signal PH 1 switches to the logic low voltage level from the logic high level, the logic low potential is capacitively coupled to the drain of top transistor NTT 2 . This decreases the potential on the drain by an amount equal to the difference between the logic high and the logic low voltages. Due to cross coupling, this voltage is coupled to the gate of bottom transistor NBT 2 and, thus, makes the bottom transistor NBT 2 conduct because the gate-to-drain voltage is lower than the threshold voltage of the p-channel transistor NBT 2 . (The source and drain of a MOS transistor are reversible and, in this instance, the drain of bottom transistor NBT 2 functions as a source.) The clock signal PH 2 , meanwhile, is at a logic high level. This gets coupled onto the drain of bottom transistor NBT 2 . As a result, the voltage on this node rises but because of the capacitively coupled low voltage on the gate of transistor NBT 2 , the transistor conducts, and thus, limits the voltage on the drain of transistor NBT 2 . The voltage on the drain of the transistor NBT 2 can reach a maximum value that equals the absolute value of the threshold voltage of the PMOS transistor. This voltage is reached when the capacitively coupled low voltage on the gate of the transistor is assumed to be zero, in which case, the PMOS transistor NBT 2 acts like a diode because of zero voltages on both the drain (acting as a source) and gate. However, when the clock signal PH 2 switches to a logic low level in the next cycle, the logic low potential gets capacitively coupled to the drain of the bottom transistor NBT 2 . This drops the potential on the drain of bottom transistor NBT 2 by an amount equal to the difference between the logic high and the logic low voltages, and makes the voltage reach a negative value as this difference is usually greater than the absolute value of the threshold voltage of the p-channel transistor. Due to cross coupling, the negative voltage on the drain of bottom transistor NBT 2 sits on the gate of top transistor NTT 2 . When the clock signal PH 2 is at a logic low state, the voltage on the drain of top transistor NTT 2 equals zero and this value gets passed on to its drain because of the sufficiently low negative voltage on the gate of top transistor NTT 2 . Meanwhile, the clock signal PH 1 is at a logic high state and when this gets down to logic low state, it pulls down the zero voltage on the drain of top transistor NTT 2 to a value that equals the difference between the logic low and the logic high voltages. By a similar process, the negative voltage on the drain of top transistor NTT 2 causes a zero voltage to be passed to the drain of bottom transistor NBT 2 which, in the next cycle, gets reduced to a negative value that equals the difference between the logic low and the logic high voltages. In most cases, the logic low voltage is the same as the ground voltage and the logic high voltage equals the same value as the input voltage VIN. Thus, as the first clock signal PH 1 switches between the logic high voltage level and the logic low voltage level, the final predischarge potential on the drain of top transistor NTT 2 switches between zero voltage and the negative voltage −VIN. Similarly, as the second clock signal PH 2 switches between the logic high voltage level and the logic low voltage level, the final potential on the drain of bottom transistor NBT 2 switches between zero voltage and the negative voltage −VIN. Thus, in accordance with the present invention, charge pump 600 provides pumped negative voltages that are not affected by the threshold voltages of the pumping transistors. When a stage is added, the adjoining bottom transistors are switched on and off out-of-phase so that when one transistor is on, the adjoining transistors are off. This allows the lowest potential from one stage to become the highest potential of the next stage in the series. Thus, the final predischarge potential on the drain of the bottom transistor NBT in a next stage switches between the lowest potential that is on the drain of the bottom transistor NBT in the previous stage, and this potential minus the difference between the logic high and the logic low potentials. Similarly, the adjoining top transistors are switched on and off out-of-phase so that when one transistor is on, the adjoining transistors are off. This allows the lowest potential from one stage to become the highest potential of the next stage in the series. Thus, the final predischarge potential on the top transistor NTT in a next stage switches between the lowest potential that is on the top transistor NTT in the previous stage, and this potential minus the difference between the logic high and the logic low potentials. For n stages, the final potential on the drain of the bottom transistor of the nth stage switches between the input voltage VIN minus n−1 times the difference between the logic high and the logic low potential; and the input voltage minus n times the difference between the logic high and the logic low potentials. Similarly, the final potential on the drain of the top transistor of the nth stage switches between the input voltage VIN minus n−1 times the difference between the logic high and the logic low potentials, and the input voltage minus n times the difference between the logic high and the logic low potentials. FIG. 7 shows a schematic diagram that illustrates a charge pump 700 in accordance with the present invention. Charge pump 700 is similar to charge pump 600 and, as a result, utilizes the same reference numerals to designate the structures that are common to both pumps. As shown in FIG. 7, pump 700 differs from pump 600 in that pump 700 includes a first p-channel diode-connected transistor PT 1 and a second p-channel diode-connected transistor PT 2 that are connected as transistors DT 1 and DT 2 . In operation, the voltage on the source of transistor PT 1 has an approximately square waveform that switches between first and second voltages. The first voltage is equal to the input voltage VIN minus n−1 times the difference between the logic high and the logic low potentials plus the absolute value of the threshold voltage of transistor PT 1 . The second voltage is equal to the input voltage minus n times the difference between the logic high and the logic low potentials plus the absolute value of the threshold voltage of transistor PT 1 . Similarly, the voltage on the source of transistor PT 2 has an approximately square waveform that switches between first and second voltages. The first voltage is equal to the input voltage VIN minus n−1 times the difference between the logic high and the logic low potentials plus the absolute value of the threshold voltage of transistor PT 2 . The second voltage is equal to the input voltage minus n times the difference between the logic high and the logic low potentials plus the absolute value of the threshold voltage of transistor PT 2 . The voltages on the sources of transistors PT 1 and PT 2 are 180° out-of-phase such that the first voltage on the source of transistor PT 1 and the second voltage on the source of transistor PT 2 are present at the same time. As a result, an approximately constant negative voltage equal to the negative voltage −VIN minus n times the logic low potential plus the absolute value of the threshold voltage of transistor PT 1 (the threshold voltages of transistors PT 1 and PT 2 are assumed to be the same) is present on the output node NOUT. FIG. 8 shows a schematic diagram that illustrates a charge pump 800 in accordance with the present invention. Charge pump 800 is similar to charge pump 600 , as a result, utilizes the same reference numerals to designate the structures that are common to both pumps. As shown in FIG. 8, pump 800 differs from pump 600 in that pump 800 includes a p-channel first transistor Q 1 and a p-channel second transistor Q 2 . First transistor Q 1 has a source connected to the drain of the bottom transistor NBTn in the last stage NSGn, a gate, and a drain connected to an output node NOUT. Second transistor Q 2 has a source connected to the drain of the top transistor NTTn in the last stage NSGn, a gate, and a drain connected to the output node NOUT. Pump 800 also includes a third n-channel transistor Q 3 and a fourth n-channel transistor Q 4 . Third transistor Q 3 has a source connected to the drain of transistor Q 1 and the output node NOUT, a gate connected to the gate of transistor Q 1 , and a drain. Fourth transistor Q 4 has a source connected to the drain of transistor Q 2 and the output node NOUT, a gate connected to the gate of transistor Q 2 and the drain of transistor Q 3 , and a drain connected to the gate of transistor Q 3 . Pump 800 additionally includes a bottom capacitor CAP 1 and a top capacitor CAP 2 . Bottom capacitor CAP 1 is connected between the drain of transistor Q 3 and the clock signal that is the same as the clock signal that is connected to the top capacitor NTCn in the last stage NSGn. Top capacitor CAP 2 is connected between the drain of transistor Q 4 and the clock signal that is the same as the clock signal that is connected to the bottom capacitor NBCn in the last stage NSGn. Bottom and top capacitors CAP 1 and CAP 2 can be, for example, about one-tenth as large as the bottom and top capacitors NBC and NTC. In operation, the voltages on the drains of transistors Q 3 and Q 4 are pumped down in the same way as if transistors Q 3 and Q 4 were the bottom and top transistors NBT and NTT of another stage NSG. Thus, the final potentials on the drains of transistors Q 3 and Q 4 switch between the input voltage VIN minus n−1 times the difference between the logic high and the logic low potentials; and the input voltage VIN minus n times the difference between the logic high and the logic low potentials. As a result, the lowest final potentials on the drains of transistors Q 3 and Q 4 are both lower than the lowest final potentials on the drains of the bottom and top transistors NBT and NTT of the last stage NSGn by the difference between the logic high and the logic low potentials. Due to the cross coupling, when the potential on the drain of the bottom transistor of the last stage NSGn switches to its lowest potential, the voltage on the gates of transistors Q 1 and Q 3 also switches to its lowest potential. This, in turn, causes the potential on the output node NOUT to fall to the lowest potential that is on the drain of the bottom transistor NBTn of the last stage NSGn. Similarly, when the potential on the drain of the top transistor of the last stage NSGn switches to its lowest potential, the voltage on the gates of transistors Q 2 and Q 4 also switches to its lowest potential. This, in turn, causes the potential on the output node NOUT to fall to the lowest potential that is on the drain of the bottom transistor NBTn of the last stage NSGn. The voltage on the drain of transistor Q 1 has an approximately square waveform that switches between first and second voltages. The first voltage is equal to the input voltage VIN minus n−1 times the difference between the logic high and the logic low potentials. The second voltage is equal to the input voltage minus n times the difference between the logic high and the logic low potentials. Similarly, the voltage on the drain of transistor Q 2 has an approximately square waveform that switches between first and second voltages. The first voltage is equal to the input voltage VIN minus n−1 times the difference between the logic high and the logic low potentials. The second voltage is equal to the input voltage minus n times the difference between the logic high and the logic low potentials. The voltages on the drains of transistors Q 1 and Q 2 are 180° out-of-phase such that the first voltage on the drain of transistor Q 1 and the second voltage on the drain of transistor Q 2 are present at the same time. As a result, an approximately constant voltage equal to the input voltage VIN minus n times the difference between the logic high and the logic low potentials is present on the output node NOUT. FIG. 9 shows a schematic diagram that illustrates a charge pump 900 in accordance with the present invention. Charge pump 900 is similar to charge pump 800 and, as a result, utilizes the same reference numerals to designate the structures that are common to both pumps. As shown in FIG. 9, pump 900 differs from pump 800 in that pump 900 includes a pair of p-channel transistors P 1 and P 2 that are used to enable or disable pump 900 . Transistor P 1 has a drain connected to the gate of transistor Q 2 , a gate connected to receive a control signal CNT, and a source connected to a supply voltage VCC. Transistor P 2 has a drain connected to the gate of transistor Q 1 , a gate connected to receive the control signal CNT, and a source connected to the supply voltage VCC. In operation, when the control signal is at a logic high potential, equal to that of the supply voltage VCC, the gates of the transistors Q 1 -Q 4 are unaffected by transistors N 1 and N 2 , and thus, enable the pump to operate normally. However, when the control signal CNT is low, the gates of transistors Q 1 -Q 4 are pulled to the supply voltage VCC, thereby turning transistors Q 1 -Q 4 , and as a result, the whole pump off. It should be understood that various alternatives to the embodiment of the invention described herein may be employed in practicing the invention. Thus, it is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.

The diode drops associated with the output voltage from a conventional charge pump are eliminated in the present invention with a dual-chain charge pump that utilizes the pumped voltages from each charge pump chain to drive the gates of the other charge pump chain. As a result, the voltages on the gates of the transistors are pumped up to a level such that there is no threshold voltage drop across the transistor, and thus, making it behave like an ideal switch.

BACKGROUND OF THE INVENTION 1. Field of the Invention The process of the present invention constitutes a means for the reactive separation of hydrolyzable polymers such as polyethylene terephthalate resins ("PET"), polyamides, polycarbonates, polyethers, poly-acrylonitriles in mixtures with polyolefins such as polypropylene ("PP") and polyethylene ("PE") by selectively converting the hydrolyzable polymers to their starting materials, e.g., PET to terephthalic acid ("TPA") and ethylene glycol ("EG"). Selective conversion is carried out by heating the starting mixture of neutral liquid water, hydrolyzable polymers, preferably PET, polyamides, polycarbonates, polyethers and polyacrylonitriles, and other non-hydrolyzable polyolefins such as PP and PE at from about 200° C. up to the critical temperature of water, which is about 374° C. at autogenous pressure. 2. Discussion of Related Art The hydrolysis of high molecular weight condensation polymers such as PET in the absence of added acids or bases, is well known in the art. When, for example the condensation polymer is PET, the primary hydrolysis products are TPA and EG, see, e.g., U.S. Pat. No. 4,578,510, U.S. Pat. No. 4,605,762, U.S. Pat. No. 4,620,032 and U.S. Pat. No. 3,120,561. However, the art does not teach nor suggest a process for the reactive separation of condensation polymers such as PET, polyamides, polycarbonates, polyethers, polyvinylchlorides, and polyacrylonitriles from mixtures containing other polymer resins by hydrolyzing the condensation polymer into its water-soluble components in the presence of neutral liquid water as a starting material in the absence of any externally supplied acids or bases and at autogenous pressure. SUMMARY OF THE INVENTION This invention relates to a process for the reactive separation of hydrolyzable polymers, such as PET, polyamides, polycarbonates, polyethers, polyvinylchlorides, and polyacrylonitriles in mixtures with polyolefins such as PP and PE by selectively converting PET to TPA and EG by contacting the mixture with neutral liquid water as a starting material (pH equals 7.0) at a temperature preferably from about 200° C. to about 310° C., more preferably from about 250° C. to about 300° C. at the pressure generated by the mixed components of the system at the corresponding temperature ("autogenous pressure"). The products resulting from the conversion of the products remain in the hot liquid water phase and may be separated. DETAILED DESCRIPTION OF THE INVENTION All materials used herein may be obtained from commercial sources. The hydrolyzable polymers are preferably PET, polyamides, polycarbonates, polyethers, and polyacrylonitriles polymers in mixtures with non-hydrolyzable polymers, preferably polyolefins such as PP, PE alone or in mixtures thereof. As used herein, "hydrolyzable" refers to decomposition of the C--0 bonds in the backbone of a polymer by hydrolysis under the conditions of the present invention. In the starting mixture, the hydrolyzable and nonhydrolyzable polymers may be present in any form that can be accommodate by the reaction vessel, thus powders crystals, small chips are acceptable. The selective reactive separation of the PET, polyamides, polycarbonates, polyethers, and poly acrylonitriles (collectively referred to herein as "hydrolyzable polymers") in a mixture of the hydrolyzable polymers and non-hydrolyzable polymers, specifically polyolefins such as PP and PE and selective reactive polyolefins e.g., is carried out by contacting the starting materials of the non-hydrolyzable and hydrolyzable polymers and neutral liquid water at a temperature of preferably from about 200° C. up to the critical temperature of water, which is about 374° C., preferably from about 200° C. to about 350° C., more preferably from about 225° C. to about 325° C. for a time sufficient to convert the hydrolyzable polymer(s) to corresponding water soluble components. The identity of such components are well known to one ordinarily skilled in the art. Polyolefins in the mixture are not hydrolyzable polymers at the reaction conditions of the process of the present invention. The amount by weight of water to polymer should be from about 1:1-20:1, preferably from about 2:1-10:1. The reaction is carried out at autogenous pressure (i.e., vapor) the pressure generated by the mixed components system at the given reaction temperature which typically, for liquid water alone will be from about 225.45 psi at 200° C. to about 2397.79 psi at 350° C. It is within the skill of one ordinarily skilled in the art to determine such pressures, and the pressure of liquid water in the above temperature range may be determined by reference to standard tests. See, e.g., CRC Handbook of Chemistry and Physics, 61st Edition, p. D-197 (1980-1981). In the process of the present invention, liquid water, the hydrolyzable polymers, and the non-hydrolyzable polymers are the only starting materials. The products resulting from contacting the starting materials of the polymers and neutral liquid water under the reaction conditions of the present invention are such that the hydrolyzable polymers produce products that are soluble in hot water and, thus, remain in the hot liquid water phase, while the non-hydrolyzable polymers (polyolefins) form a separate, solid phase. The two phases may be separated by any means known to one skilled in the art, for example, by filtration, by such contact and thus are present as a separate, solid phase. For example, when the starting mixture contains PET, PE and PP, and neutral liquid water the contacting reactively separates the PET by producing TPA and EG that remain in the aqueous layer; the PP and PE are not hydrolyzed by such contacting. The products of PET hydrolysis, TPA and EG, are recoverable from the hot liquid water phase layer. The process has utility in plastics recycling by providing a simple method for differentiating by reactive separation hydrolyzable polymers from which starting materials can be recovered from other non-hydrolyzable polymers (polyolefins) which then can be used in conversion processes, and has utility as a method for reactive purification of non-hydrolyzable polymers (polyolefins) so that they can be used in other conversion processes. The process of the present invention may be understood by reference to the following examples. EXAMPLE 1 A mixture of PET (plastic soda containers), polyamides (nylon), and polycarbonates was cut into small pieces and placed in a minibomb with an approximately five-fold excess by weight of water to the total amount by weight of polymer. The temperature was raised to approximately 315° C. for 2 hours. At the end of the 2-hour period, the hot liquid phase containing the hydrolysis products, terephthalic acid and ethylene glycol, was separated from the solid phase which contained the polyolefins. EXAMPLE 2 The procedures of Example 1 were repeated, except that the temperature was raised to 350° C. As in Example 1, the temperature was raised to approximately 350° C. for 2 hours. At the end of the 2-hour period, the hot liquid water phase containing the hydrolysis products, terephthalic acid and ethylene glycol, was separated from the solid phase which contained the polyolefins.

The present invention relates to a process for reactively separating hydrolyzable polymers, such as PET, in mixtures of the polymer and certain non-hydrolyzable polymers, specifically polyolefins by converting the hydrolyzable polymers to their corresponding water soluble components (e.g., PET to ethylene glycol and terephthalic acid) in the presence of liquid water at temperatures from about 200° C. up to the critical temperature of water and autogenous pressure. The process has utility in recycling and waste material separation processes.

BACKGROUND [0001] 1. Technical Field [0002] The present invention relates to ink-jet printers capable of forming predetermined letters and images on print media by, for example, discharging minuscule ink droplets of a plurality of colors from a plurality of nozzles so as to form minute particles (ink dots) on the print media. [0003] 2. Related Art [0004] Such ink-jet printers have been in widespread use by general users in addition to users in offices along with the popularization of personal computers, digital cameras, and the like since such ink-jet printers can easily produce high-quality color prints at low cost. Typical ink-jet printers of this type include printing heads (also referred to as ink-jet heads), and produce desired prints on which predetermined letters and images are formed by discharging (ejecting) ink droplets from nozzles of the ink-jet heads while the ink-jet heads are moved with respect to print media so as to form minute ink dots on the print media. In general, ink-jet printers including movable bodies referred to as carriages that include ink-jet heads attached thereto and are moved in a direction intersecting with a direction along which print media are transported (print-medium transporting direction) are referred to as “ink-jet printers of the multi-pass type”. In contrast, ink-jet printers including long ink-jet heads (not necessarily single units) extending in the direction intersecting with the print-medium transporting direction and capable of printing in a so-called one pass are referred to as “ink-jet printers of the line-head type”. [0005] In these ink-jet printers, the inclination of print media needs to be corrected so as to be a predetermined angle. For example, when print media that are being transported are inclined with respect to the print-medium transporting direction, letters and images are not printed on the print media at proper positions. To solve this problem, for example, gate rollers described in JP-A-2004-51340 capable of correcting the inclination of print media and adjusting the timing of transporting the print media can be used. In this known technology, each print medium in a paper-feeding unit is fed by feed rollers, and brought into contact with a nip (contact portion) formed between the gate rollers. Next, the print medium is warped by further driving the feed rollers. Subsequently, the gate rollers are driven so that the warpage of the print medium is removed. With this, the inclination of the print medium is corrected and the timing of transporting the print medium is adjusted. Moreover, in this ink-jet printer, a fact that the stiffness of a print medium is changed depending on temperature and humidity is noted, and the amount of warpage of the print medium formed when the print medium is pressed toward the nip formed between the gate rollers is adjusted in accordance with temperature and humidity such that the print medium is prevented from buckling. [0006] However, in the ink-jet printer described in JP-A-2004-51340, the amount of warpage of the print medium is adjusted simply in accordance with temperature and humidity, and, for example, the effect of ink droplets discharged to a first side of the print medium in a case where printing on a second side of the print medium is performed subsequent to printing on the first side of the print medium is not considered. In particular, when water-based ink is used, the stiffness of the print medium is significantly changed before and after printing. Similarly, the stiffness of the print medium after printing is changed in accordance with its printing state. When printing on the second side of the print medium is performed subsequent to printing on the first side, the print medium can be buckled if the print medium is not pressed toward the gate rollers with a force in accordance with the stiffness of the print medium. SUMMARY [0007] An advantage of some aspects of the invention is that an ink-jet printer is provided such that a print medium whose first side is printed and whose second side is to be printed is not buckled when the print medium is pressed toward gate rollers. [0008] According to an aspect of the invention, an ink-jet printer that prints on a second side of a print medium subsequent to printing on a first side of the print medium includes gate rollers, the inclination of the print medium with respect to a direction along which the print medium is transported being adjusted by bringing a leading portion of the print medium in the direction along which the print medium is transported into contact with a nip formed between the gate rollers such that the print medium is warped; a feed roller that feeds the print medium to the gate rollers such that the print medium comes into contact with the gate rollers and is warped; and a warpage controller that controls the amount of warpage of the print medium formed by the feed roller in accordance with a printing state of the first side of the print medium. [0009] The warpage controller can set the amount of warpage of the print medium formed by the feed roller so as to be less than a reference value in accordance with the amount of ink droplets discharged to the first side of the print medium. [0010] The warpage controller can set the amount of warpage of the print medium formed by the feed roller so as to be less than a reference value when the first side of the print medium is printed in color. Moreover, the warpage controller can set the amount of warpage of the print medium formed by the feed roller so as to be less than a reference value in accordance with the amount of a margin left on the first side of the print medium. [0011] The warpage controller can set the amount of warpage of the print medium formed by the feed roller so as to be less than a reference value when the amount of ink droplets discharged to the leading portion of the first side of the print medium in the direction along which the print medium is transported is larger than that discharged to a trailing portion of the print medium in the direction along which the print medium is transported. [0012] According to an aspect of the invention, the print medium is prevented from buckling when the print medium is pressed toward the gate rollers by setting the amount of warpage of the print medium formed by the feed roller to a value smaller than a reference value when, for example, the amount of ink droplets discharged to the first side of the print medium is large, the first side of the print medium is printed in color, the amount of the margin left on the first side of the print medium is small, and the amount of ink droplets discharged to the leading portion of the first side of the print medium in the direction along which the print medium is transported is larger than that discharged to the trailing portion of the print medium in the direction along which the print medium is transported. BRIEF DESCRIPTION OF THE DRAWINGS [0013] The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. [0014] FIG. 1 is a front view schematically illustrating an ink-jet printer according to a first embodiment of the invention. [0015] FIGS. 2A and 2B illustrate a part adjacent to gate rollers in the ink-jet printer shown in FIG. 1 in detail. [0016] FIGS. 3A to 3E illustrate how to control amounts of warpage of one-side-printed media in the ink-jet printer shown in FIG. 1 . [0017] FIG. 4 is a flow chart illustrating an arithmetic processing for calculating an amount of warpage of a one-side-printed medium in the ink-jet printer shown in FIG. 1 . DESCRIPTION OF EXEMPLARY EMBODIMENTS [0018] Next, an ink-jet printer according to a first embodiment of the invention will be described with reference to the drawings. FIG. 1 is a front view schematically illustrating the ink-jet printer of the line-head type according to this embodiment. In FIG. 1 , each print medium 1 is transported from left to right, and letters and images are printed on the print media 1 in printing areas on the transporting path of the print media 1 . The ink-jet printer according to this embodiment includes ink-jet heads disposed at two different positions in a direction along which the print media 1 are transported (hereinafter referred to as a print-medium transporting direction). In addition, the ink-jet printer includes a reversing unit at an upper position in the printer so as to reverse the print media and supply the reversed print media to the printing areas. With this, the ink-jet printer is capable of so-called duplex printing. [0019] As shown in FIG. 1 , the ink-jet printer includes first ink-jet heads 2 disposed upstream in the print-medium transporting direction, second ink-jet heads 3 disposed downstream in the print-medium transporting direction, a first transporting unit 4 disposed below the first ink-jet heads 2 so as to transport the print media 1 , and a second transporting unit 5 disposed below the second ink-jet heads 3 . The first transporting unit 4 includes a plurality of first transporting belts 6 disposed at predetermined intervals in a direction intersecting with the print-medium transporting direction (hereinafter referred to as a nozzle-array direction). Similarly, the second transporting unit 5 includes a plurality of second transporting belts 7 disposed at predetermined intervals in the nozzle-array direction. [0020] The transporting belts 6 and 7 are alternately disposed. A driving roller 8 is disposed at a position where the transporting belts 6 and 7 overlap each other. A first driven roller 9 is disposed upstream of the driving roller 8 , and a second driven roller 10 is disposed downstream of the driving roller 8 . A tension roller 11 is disposed at a lower intermediate position between the driving roller 8 and the first driven roller 9 , and another tension roller 11 is disposed at a lower intermediate position between the driving roller 8 and the second driven roller 10 . The first transporting belts 6 are wound around the driving roller 8 , the first driven roller 9 , and one of the tension rollers 11 ; and the second transporting belts 7 are wound around the driving roller 8 , the second driven roller 10 , and the other tension roller 11 . A motor (not shown) is connected to the driving roller 8 . When the driving roller 8 is rotated by the motor, the first transporting unit 4 constituted by the first transporting belts 6 and the second transporting unit 5 constituted by the second transporting belts 7 are synchronously driven at the same speed. In addition, a paper-pressing roller 13 is disposed above the first driven roller 9 such that the print media 1 electrostatically adhere to the first transporting belts 6 . [0021] The ink-jet heads 2 and 3 for, for example, four colors of yellow (Y), magenta (M), cyan (C), and black (K) are disposed at different positions in the print-medium transporting direction. Ink is supplied from ink tanks (not shown) for those colors to the ink-jet heads 2 and 3 via ink-supplying tubes. A plurality of nozzles are formed in the ink-jet heads 2 and 3 in the nozzle-array direction, and minute ink dots are formed on the print media 1 when required amounts of ink droplets are discharged from the nozzles to desired positions on the print media 1 at the same time. Letters and images can be printed on first sides of the print media 1 in a so-called one pass when the above-described operation is performed for each color while the print media 1 pass under the ink-jet heads 2 and 3 using the transporting units 4 and 5 only one time. That is, the areas in which the ink-jet heads 2 and 3 are arranged correspond to the printing areas. [0022] Ink can be discharged from the nozzles of the ink-jet heads using, for example, the electrostatic effect, the piezoelectric effect, or film boiling. In the method using the electrostatic effect, driving signals are supplied to electrostatic gaps serving as actuators such that the positions of vibrating plates inside cavities are changed. With this, the pressure inside the cavities is changed, and ink droplets are discharged from nozzles in response to the pressure change. In the method using the piezoelectric effect, driving signals are supplied to piezoelectric elements serving as actuators such that the positions of vibrating plates inside cavities are changed. With this, the pressure inside the cavities is changed, and ink droplets are discharged from nozzles in response to the pressure change. In the method using film boiling, minute heaters disposed inside cavities instantaneously heat ink to 300° C. or more such that film boiling occurs and bubbles are generated. With this, the pressure inside the cavities is changed, and ink droplets are discharged from nozzles in response to the pressure change. Any of these ink-discharging methods is applicable to the invention. However, the method using the piezoelectric effect is preferably used since the amounts of ink droplets to be discharged can be adjusted by changing peak values of the driving signals or changing the degree of increments or decrements of voltage. [0023] The ink-discharging nozzles of the first ink-jet heads 2 are disposed only between two adjacent first transporting belts 6 in the first transporting unit 4 , and the ink-discharging nozzles of the second ink-jet heads 3 are disposed only between two adjacent second transporting belts 7 in the second transporting unit 5 . With this, the ink-jet heads 2 and 3 can be cleaned by cleaning units that are disposed inside the transporting belts 6 and 7 and are vertically movable to the ink-jet heads 2 and 3 . With this arrangement, a whole page cannot be printed in one pass using only either of the ink-jet heads 2 and 3 . Therefore, the ink-jet heads 2 and 3 are disposed at different positions in the print-medium transporting direction so that the printing areas compensate for each other. [0024] A pair of gate rollers 14 is disposed upstream of the first driven roller 9 . The gate rollers 14 adjust the timing of feeding the print media 1 supplied from paper-feeding units 15 , and correct the inclination of the print media 1 with respect to the print-medium transporting direction. In this embodiment, the paper-feeding units 15 are disposed at three positions in the printer so as to support the print media 1 of different sizes. Moreover, a pickup roller 16 is disposed over each of the paper-feeding units 15 so as to supply the print media 1 . A separation roller 17 is disposed at each connecting point of the paper-feeding units 15 and the transporting paths of the print media 1 , and a separation pad 18 is disposed under each of the separation rollers 17 . [0025] The ink-jet printer according to this embodiment further includes a controller 19 for controlling the printer and a power source 20 at a lower right position in FIG. 1 . The controller 19 includes a computer system including, for example, a central processing unit (CPU). The power source 20 controls its electric power and generates a high voltage to be supplied to a belt-charging unit (not shown). In this embodiment, the transporting belts 6 and 7 are charged by the belt-charging unit so that the print media 1 adhere to the charged transporting belts 6 and 7 by electrostatic force while being transported. [0026] In this ink-jet printer, the surfaces of the transporting belts 6 and 7 are charged by the belt-charging unit. While the transporting belts 6 and 7 are charged, the print media 1 are fed via the gate rollers 14 onto the first transporting belts 6 one by one. When the print media 1 are pressed to the first transporting belts 6 by the paper-pressing roller 13 , the print media 1 adhere to the surfaces of the first transporting belts 6 by dielectric polarization effect caused in the print media 1 by the charged first transporting belts 6 . In this state, the driving roller 8 is rotated by the motor, and the driving force is transmitted to the first driven roller 9 via the first transporting belts 6 . [0027] The print media 1 are moved downstream in the print-medium transporting direction to a position below the first ink-jet heads 2 while adhering to the first transporting belts 6 . Subsequently, ink droplets are discharged from the nozzles formed in the first ink-jet heads 2 . After printing using the first ink-jet heads 2 , the print media 1 are moved downstream in the print-medium transporting direction, and transferred to the second transporting belts 7 in the second transporting unit 5 . Since the surfaces of the second transporting belts 7 are also charged by the belt-charging unit as described above, the print media 1 adhere to the surfaces of the second transporting belts 7 by the dielectric polarization effect in the same manner as the print media 1 adhere to the first transporting belts 6 . [0028] In this state, the print media 1 are moved downstream in the print-medium transporting direction by the second transporting belts 7 to a position below the second ink-jet heads 3 . Subsequently, ink droplets are discharged from the nozzles formed in the second ink-jet heads 3 . After printing using the second ink-jet heads 3 , the print media 1 are further moved downstream in the print-medium transporting direction, and discharged to a paper-discharging section 23 while the print media 1 are separated from the surfaces of the second transporting belts 7 by a separating unit (not shown). Herein, guide rollers 24 shown in FIG. 1 feed the print media 1 from the paper-feeding units 15 to the first transporting unit 4 , and guiding paths (not shown) for substantially guiding the print media 1 are formed adjacent to the guide rollers 24 . [0029] As described above, the reversing unit for reversing the print media 1 is disposed above the printing areas formed over the transporting units 4 and 5 . The reversing unit includes a plurality of feed rollers 21 , belt conveyors 22 that transport the print media 1 while vertically supporting the print media 1 , a transporting section 27 that transports the print media 1 from a position adjacent to the paper-discharging section 23 to a position adjacent to the paper-feeding units 15 via a guiding path (not shown), and a reversing section 28 that takes the print media 1 out of the transporting section 27 at a predetermined position of the transporting section 27 and reveres the print media 1 . A first flapper 25 for sending the print media 1 whose first sides are printed to the transporting section 27 is disposed upstream of the paper-discharging section 23 in the print-medium transporting direction, and a second flapper 26 for sending the print media 1 from the transporting section 27 to the reversing section 28 is disposed below the reversing section 28 . [0030] For duplex printing, the print media 1 whose first sides are printed in the printing areas are sent to the transporting section 27 by the first flapper 25 , and transported to the reversing section 28 by the feed rollers 21 in the transporting section 27 and the belt conveyors 22 . When the print media 1 are transported to a position before the reversing section 28 , the second flapper 26 is actuated, and sends the print media 1 to the reversing section 28 . The reversing section 28 guides the print media 1 using the feed rollers 21 such that the print media 1 are turned upside down, and sends the print media 1 back using the feed rollers 21 while the print media 1 are in the inverted position. The print media 1 pass through the second flapper 26 , and are sent to the gate rollers 14 through the feed rollers 21 adjacent to the paper-feeding units 15 . The gate rollers 14 adjust the inclination of the print media 1 whose first sides are printed in the same manner as the gate rollers 14 adjust the inclination of the print media 1 whose first sides are unprinted, and feed the print media 1 to the printing areas. [0031] FIGS. 2A and 2B illustrate a print medium 1 fed from the transporting section 27 to the gate rollers 14 in detail. A guide plate 29 shown in FIGS. 2A and 2B forms the guiding path of the transporting section 27 , and guides the print medium 1 when the print medium 1 is pressed toward the gate rollers 14 by the feed rollers 21 and warped. In addition, detection sensors 30 shown in FIGS. 2A and 2B detect the passage of the print medium 1 . When the stiffness of the print medium 1 is high to some extent, the print medium 1 pressed toward the gate rollers 14 is warped flexibly as shown in FIG. 2A , and the inclination of the print medium 1 can be adjusted when the warpage of the print media 1 is removed. In contrast, when the stiffness of the print medium 1 is low, the print medium 1 pressed toward the gate rollers 14 can be buckled and form, for example, a Z shape as shown in FIG. 2B . In particular, when the first side of the print medium 1 is printed using water-based ink, the stiffness of the print medium 1 is further reduced due to the penetration of the water-based ink. [0032] In this embodiment, print media 1 , whose first sides are printed and whose second sides are to be printed (hereinafter also referred to as one-side-printed media 1 ) are warped when being pressed toward the gate rollers 14 , and the amounts of warpage are controlled by the controller 19 . The amounts of warpage of the print media 1 can be controlled using amounts of feed, that is, amounts of rotation of the feed rollers 21 that are closest to the detection sensors 30 after the detection sensors 30 detect the one-side-printed media 1 . Since the stiffnesses of the print media 1 are not significantly high, the amounts of warpage of the print media 1 can be adjusted by controlling the amounts of feed, i.e., the amounts of rotation of the feed rollers 21 without controlling the pushing force with which the print media 1 are pressed toward the gate rollers 14 . Reductions in the amounts of warpage can easily prevent the buckling of the print media 1 . However, the warpage is required to some extent so that the inclination of the print media 1 can be adjusted. Therefore, the controller 19 performs control such that the amounts of warpage become small when the stiffnesses of the one-side-printed media 1 are low in particular. [0033] In this embodiment, the stiffnesses of the one-side-printed media 1 and the amounts of warpage of the one-side-printed media 1 are determined as follows. Herein, one-side-printed media 1 shown in FIGS. 3A to 3E are transported from left to right in FIG. 3A to 3E . For example, as shown in FIG. 3A , when the amounts (total amounts) of ink droplets discharged to the first sides of the print media 1 are determined as large, the stiffnesses of the print media 1 are determined as low, and warpage correction factors for the print media 1 are set to small values. Moreover, as shown in FIG. 3B , the amounts of ink droplets discharged to the first sides of the print media 1 are determined as large in the case of color printing, and the stiffnesses of the print media 1 are determined as low. Thus, the warpage correction factors are set to small values. Furthermore, as shown in FIG. 3C , the amounts of ink droplets discharged to the first sides of the print media 1 are determined as large when margins are small, and the stiffnesses of the print media 1 are determined as low. Thus, the warpage correction factors are set to small values. In the case of color printing, the amounts of ink droplets are increased compared with the case of black-and-white printing since ink droplets of different colors are discharged to the same positions. [0034] In this embodiment, the stiffnesses of one-side-printed media 1 are determined also using patterns printed on the first sides of the print media 1 for determining the amounts of warpage. As shown in FIG. 3D , for example, even when the amounts of ink droplets discharged to the one-side-printed media 1 are the same, the stiffnesses of the print media 1 are determined as low when large amounts of ink droplets are discharged to the leading portions of the print media 1 in the print-medium transporting direction, which correspond to areas to be buckled, compared with the case where large amount of ink droplets are discharged to the trailing portions of the print media 1 in the print-medium transporting direction, which correspond to areas uninvolved in buckling. Thus, the warpage correction factors are set to small value. Moreover, when no continuous blank spaces are formed in the print-medium transporting direction, the stiffnesses of the print media 1 are determined to be low compared with the case where continuous blank spaces are formed in the print-medium transporting direction, and the warpage correction factors are set to small values. Aside from these, the warpage correction factors are also determined with consideration of the types of the print media 1 . The amounts of warpage of the one-side-printed media 1 are calculated by multiplying a reference value of the amounts of warpage by the above-described warpage correction factors. [0035] FIG. 4 illustrates an arithmetic processing for calculating an amount of warpage of a one-side-printed medium 1 . In Step S 1 , a warpage correction factor α depending on the type of the one-side-printed medium 1 described above is retrieved from a memory containing warpage correction factors. In Step S 2 , a warpage correction factor β depending on the amount (total amount) of ink droplets described above is retrieved from the memory. In Step S 3 , a warpage correction factor γ depending on the printed pattern described above is retrieved from the memory. In Step S 4 , an amount of warpage Y is calculated by multiplying a reference value X of the amount of warpage by the warpage correction factors α to γ retrieved in Steps S 1 to S 3 . Subsequently, the process returns to the main program. [0036] In accordance with the ink-jet printer according to this embodiment, one-side-printed media 1 , whose first sides are printed and whose second sides are to be printed, are warped when being pressed toward the gate rollers 14 by the feed rollers 21 , and the amounts of warpage are controlled in accordance with the amounts of ink droplets discharged to the first sides of the one-side-printed media 1 , the printing states such as the patterns printed on the one-side-printed media 1 , and the like. Therefore, the one-side-printed media 1 can be prevented from buckling when the one-side-printed media 1 are pressed toward the gate rollers 14 . [0037] Moreover, the amounts of warpage of the one-side-printed media 1 are set so as to be less than the reference value in accordance with the amounts of ink droplets discharged to the first sides of the one-side-printed media 1 . Therefore, the one-side-printed media 1 can be prevented from buckling when the one-side-printed media 1 are pressed toward the gate rollers 14 by the feed rollers 21 . Furthermore, the amounts of warpage of the one-side-printed media 1 are set so as to be less than the reference value in the case of color printing. Therefore, the one-side-printed media 1 can be reliably prevented from buckling when the one-side-printed media 1 are pressed toward the gate rollers 14 by the feed rollers 21 . [0038] Moreover, the amounts of warpage of the one-side-printed media 1 are set so as to be less than the reference value in accordance with the amounts of blank spaces formed on the first sides of the one-side-printed media 1 . Therefore, the one-side-printed media 1 can be reliably prevented from buckling when the one-side-printed media 1 are pressed toward the gate rollers 14 by the feed rollers 21 . Furthermore, the amounts of warpage of the one-side-printed media 1 are set so as to be less than the reference value when the amounts of ink droplets discharged to the leading portions of the one-side-printed media 1 in the print-medium transporting direction are larger than those discharged to the trailing portions of the one-side-printed media 1 . Therefore, the one-side-printed media 1 can be reliably prevented from buckling when the one-side-printed media 1 are pressed toward the gate rollers 14 by the feed rollers 21 . In addition, the amounts of warpage of the one-side-printed media 1 are set so as to be less than the reference value when the areas of continuous blank spaces formed on the first sides of the one-side-printed media 1 in the print-medium transporting direction are small. Therefore, the one-side-printed media 1 can be reliably prevented from buckling when the one-side-printed media 1 are pressed toward the gate rollers 14 by the feed rollers 21 .

An ink-jet printer that prints on a second side of a print medium subsequent to printing on a first side of the print medium includes gate rollers, the inclination of the print medium with respect to a direction along which the print medium is transported being adjusted by bringing a leading portion of the print medium in the direction along which the print medium is transported into contact with a nip formed between the gate rollers such that the print medium is warped; a feed roller that feeds the print medium to the gate rollers such that the print medium comes into contact with the gate rollers and is warped; and a warpage controller that controls the amount of warpage of the print medium formed by the feed roller in accordance with a printing state of the first side of the print medium.

CROSS-REFERENCE TO RELATED APPLICATIONS This application claim priority to U.S. application Ser. No. 12/827,487, filed on Jun. 30, 2010, the entire contents of which are hereby incorporated by reference. TECHNICAL FIELD This document relates to removing noise from audio. BACKGROUND Teleconferences and video conferences are becoming ever more popular mechanisms for communicating. Many portable computer devices, such as laptops, netbooks, and smartphones, today have built-in microphones. In addition, many portable computer devices have built-in cameras (or can easily have an inexpensive external camera, such as a web cam, added). This allows for very low cost participation in teleconferences and video conferences. It is common for participants in a conference to be typing during the conference. For example, a participant may be taking notes about the conference or multi-tasking while talking or while listening to others talk. With the physical proximity of the keyboard on the portable computer device to a microphone that may also be on the portable computer device, the microphone can easily pick up noise from the keystrokes and transmit the noise to the conference, annoying the other participants. In headphones, it is common to remove unwanted ambient noise by building a model of the noise, and inserting the “inverse” of that noise in the audio signal to cancel the noise. The trick is to build a model that accurately matches the noise so that it can be removed without removing meaningful parts of the audio signal. For example, noise canceling headphones have small microphones outside the headphones themselves. Any sounds the headphones detect as coming from “outside” are potentially noise that should be canceled. SUMMARY In general, this document describes systems and methods for removing noise from audio. In certain examples, the actuation of keys on a computer device can be sensed separately by electrical contact being made within the key mechanisms and by sounds (e.g., clicking) of the keys received on a microphone that is electronically connected to the computer device. Such received data may be correlated, such as by aligning the two sets of data in time so as to identify the portion of the sounds received by the microphone that is attributable to the actuation of the keys, so that such portion may be selectively and partially or substantially removed from the sound. Previous actuation of the keys and associated sounds of such actuation may also be acquired under previous controlled conditions so that a model can more readily identify the part of a sound signal that can be attributed to the action of the keys, once the timing of the keys has been determined in the audio signal. The subsequent filtered signal can then be broadcast to other electronic devices such as to users of telephones or other computer devices that are on a conference call with a user of the computer device. In one aspect, a computer-implemented method for removing noise from audio includes building a sound model that represents noises which result from activations of input controls of a computer device. The method further includes receiving an audio signal produced from a microphone substantially near the computer device. The method further includes identifying, without using the microphone, an activation of at least one input control from among the input controls. The method further includes associating a portion of the audio signal as corresponding to the identified activation. The method further includes applying, from the audio model, a representation of a noise for the identified activation to the associated portion of the audio signal so as to cancel at least part of the noise from the audio signal. Implementations can include any, all, or none of the following features. The microphone is mounted to the computer device. The input controls include keys on a keyboard, the activations include physical actuations of the keys on the keyboard, and identifying the activation includes receiving a software event for the activation. The noises include audible sounds that result from the physical actuations of the keys. The model defines the audible sounds of the physical actuations of the keys by frequency and duration. Building the model includes obtaining, through the microphone, the audible sounds of the physical actuations of the keys. Obtaining the audible sounds of the physical actuations of the keys occurs as a background operation for training the computer device while one or more other operations are performed that use the keys. Building the model includes receiving the obtained audible sounds of the physical actuations of the keys at a server system that is remote from the computer device. The method includes receiving the audio signal and data representing timing of the activation of the key on the computer device at the server system. The noise includes electrical noise. The method includes sending the audio signal with the part of the noise removed over a network for receipt by participants in a teleconference. Associating the portion of the audio signal as corresponding to the identified activation includes correlating timing of receiving the portion and of receiving the activation. The method includes automatically calibrating the computer device to determine an amount of time between receiving the portion and receiving the activation. In one aspect, a computer program product, encoded on a computer-readable medium, operable to cause one or more processors to perform operations for removing noise from audio includes building a sound model that represents noises which result from activations of input controls of a computer device. The operations further include receiving an audio signal produced from a microphone substantially near the computer device. The operations further include identifying, without using the microphone, an activation of at least one input control from among the input controls. The operations further include associating a portion of the audio signal as corresponding to the identified activation. The operations further include applying, from the audio model, a representation of a noise for the identified activation to the associated portion of the audio signal so as to cancel at least part of the noise from the audio signal. Implementations can include any, all, or none of the following features. The microphone is mounted to the computer device. The input controls include keys on a keyboard, the activations include physical actuations of the keys on the keyboard, and identifying the activation includes receiving a software event for the activation. The noises include audible sounds that result from the physical actuations of the keys. The model defines the audible sounds of the physical actuations of the keys by frequency and duration. Building the model includes obtaining, through the microphone, the audible sounds of the physical actuations of the keys. Obtaining the audible sounds of the physical actuations of the keys occurs as a background operation for training the computer device while one or more other operations are performed that use the keys. Building the model includes receiving the obtained audible sounds of the physical actuations of the keys at a server system that is remote from the computer device. The operations include receiving the audio signal and data representing timing of the activation of the key on the computer device at the server system. The noise includes electrical noise. The operations include sending the audio signal with the part of the noise removed over a network for receipt by participants in a teleconference. Associating the portion of the audio signal as corresponding to the identified activation includes correlating timing of receiving the portion and of receiving the activation. The operations include automatically calibrating the computer device to determine an amount of time between receiving the portion and receiving the activation. In one aspect, a computer-implemented system for removing noise during a teleconference includes a sound model generated to define noises which result from input controls being activated on a computer device. The system further includes an interface to receive first data that reflects electrical activation of the input controls and second data that reflects an audio signal received by a microphone in communication with the computer device. At least a portion of the audio signal includes one or more of the noises which result from activation of the input controls on the computer device. The system further includes a noise cancellation module programmed to correlate the first data with the second data and to use representations of the one or more noises from the sound model to cancel the one or more noises from the portion of the audio signal received from the microphone. Implementations can include any, all, or none of the following features. The microphone is mounted to the computer device. The input controls include keys on a keyboard of the computer device and activation of the input controls includes physical actuation of the keys on the keyboard. The systems and techniques described here may provide one or more of the following advantages. First, a system can allow a user to interact with one or more input controls, such as a keyboard or button, while speaking into a microphone without distracting an audience that listens to the recording with the sounds of those input controls. Second, a system can provide a software solution for reducing noise from input controls, such as a keyboard or button, during a recording on a computer device. Third, a system can reduce noise from input controls during a recording on a computer device without the addition of further hardware to the computer device, such as additional microphones. Fourth, a system can provide for canceling noise at a central server system and distributing the noise canceled audio to multiple computer devices. The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims. DESCRIPTION OF DRAWINGS FIG. 1 is a schematic diagram that shows an example of a system for removing noise from audio. FIG. 2 is a block diagram that shows an example of a portable computing device for removing noise from audio. FIG. 3 is a flow chart that shows an example of a process for removing noise from audio. FIG. 4 shows an example of a computing device and a mobile computing device that can be used in connection with computer-implemented methods and systems described in this document. DETAILED DESCRIPTION This document describes systems and techniques for removing noise from audio. In general, audio input to a computing device may be modified, such as to filter or cancel noise that results from one or more other input devices being used. For example, the noise may be the sounds of key presses, button clicks, or mouse pad taps and the sounds can be removed from the audio that has been captured. In another example, the noise may be electromagnetic noise, such as electromagnetic interference with the audio input caused by another input device. With the noise from the input devices removed, the audio can then be recorded and/or transmitted. This removal may occur, for example, prior to the audio being sent from the computing device to another computing device that is participating in a teleconference or videoconference. In another example, the raw audio can be provided to an intermediate system where the noise is filtered or canceled and then provided to another computing device. FIG. 1 is a schematic diagram that shows an example of a system 100 for removing noise from audio. The system 100 generally includes a computing device 102 equipped with a microphone 104 . The system 100 can access software for correlating activation events from one or more input devices on the computing device 102 with noise that results from the activation events. Activation events and input devices can include, for example, key presses on a keyboard, clicks on a button, scrolling of a trackball or mouse wheel, or taps on a touch pad. The noise, in the case of audible noise, is included in or, in the case of electromagnetic noise, interferes with an audio signal received via the microphone 104 . The system 100 can identify the relationship between such received data in order to better filter out the noise of the activation events from audio captured via the microphone 104 . As noted, the computing device 102 receives audio input via the microphone 104 . The audio input includes both intended audio, such as a speech input 108 from a user 106 , and unintended audio or interference, such as one or more noises 112 that result from activating one or more input controls 110 . The input controls can include, for example, keys in a keyboard 110 a , a touchpad 110 b , and other keys in the form of one or more buttons 110 c . In some implementations, the input controls 110 can include a touchscreen, scroll wheel, or a trackball. The computing device 102 uses active noise control processes to filter the audio input to isolate the speech input 108 of the user 106 , or other audio, from the noises 112 produced by the input controls 110 . In using the computing device 102 , the user 106 may speak while making one or more inputs with the input controls 110 . Activating the input controls 110 produces the noises 112 . The noises 112 combine with the speech input 108 , and the combined sounds are received by the microphone 104 and/or the computing device 102 as audio input. The computing device 102 modifies the audio input to cancel or filter the noises 112 , leaving only, or substantially only, the speech input 108 from the user 106 , or at least the non-noise content of the audio. Substantially can include, for example, a significant or noticeable reduction in the magnitude of the noises 112 as compared to the speech input 108 . The modified audio input can be sent, for example, to one or more remote computing devices that are participating in a teleconference. The remote computing devices can then play back the modified audio to their respective users. The computing device 102 , which in this example is a laptop computer, executes one or more applications that receive audio input from the microphone 104 and concurrently receive another input, such as electronic signals indicating the actuation of a key press on the keyboard 110 a , a selection of the buttons 110 c , or a tap on the touchpad 110 b . The computing device 102 also stores representations of the sound produced by the key press, button click, and other input events. For example, the representations may be stored as waveforms. When the computing device 102 receives a particular input event, such as by recognizing that the contacts on a particular key or button have been connected or a key press event being raised by an operating system of the computing device 102 , the computing device 102 retrieves the associated representation and applies the representation to the recorded audio from the microphone 104 to cancel the sound produced by the input event. In some implementations, the applications that receive the audio input can include a teleconferencing or remote education application. The teleconferencing or remote education application may provide the modified recorded audio to one or more remote computing devices that are participating in the teleconference or remote education session. The recorded audio may be stored for a definite period of time in certain applications, and may also be streamed, transmitted, and not subsequently stored. Alternatively, the teleconferencing or remote education application may provide audio data to an intermediate system, such as a teleconferencing server system. For example, the computing device 102 can provide the modified audio to the teleconferencing server system. In another example, the computing device 102 can provide the unmodified audio data and data describing the input control activation events (e.g., key contacts being registered by the computing device 102 , apart from what sound is heard by the microphone 104 ), such as an identification of the specific events and times that the specific events occurred relative to the audio data. The teleconferencing server system can then perform the noise cancellation operations on the audio data. For example, the teleconferencing server system may have previously stored, or may otherwise have access to, the representations of the sounds produced by activating the input controls 110 (or input controls on a similar form of device, such as a particular brand and model of laptop computer). The teleconferencing server system uses the event identifications and the timing information to select corresponding ones of the representations and to apply those representations at the correct time to cancel the noise from the audio data. The teleconferencing server system can then provide the modified audio to the remote computing devices. In some implementations, the microphone is substantially near the computing device 102 . Substantially near can include the microphone 104 being mounted to the computing device 102 or placed a short distance from the computing device 102 . For example, as shown in FIG. 1 , the microphone 104 is integrated within a housing for a laptop type of computing device. In another example, a microphone that is external to the computing device 102 can be used for receiving the audio input, such as a freestanding microphone on the same desk or surface as the computing device 102 or a headset/earpiece on a person operating the computing device 102 . In another example, the microphone 104 can be placed on the computing device 102 , such as a microphone that rests on, is clipped to, or is adhered to a housing of the computing device 102 . In yet another example, the microphone 104 can be located a short distance from the computing device 102 , such as several inches or a few feet. In another example, the microphone 104 can be at a distance and/or a type of contact with the computing device 102 which allows vibration resulting from activation of input controls to conduct through a solid or semi-solid material to the computing device 102 . In some implementations, the computing device 102 can be a type of computing device other than a laptop computer. For example, the computing device 102 can be another type of portable computing device, such as a netbook, a smartphone, or a tablet computing device. In another example, the computing device 102 can be a desktop type computing device. In yet another example, the computing device 102 can be integrated with another device or system, such as within a vehicle navigation or entertainment system. In certain implementations more or less of the operations described here can be performed on the computing device 102 versus on a remote server system. At one end, the training of a sound model to recognize the sounds of key presses, and the canceling or other filtering of the sounds of key presses may all be performed on the computing device 102 . At the other end of the spectrum, the processing and filtering may occur on the server system, with the computing device 102 simply sending audio data captured by the microphone 104 along with corresponding data that is not from the microphone 104 but directly represents actual actuation of keys on the computing device 102 . The server system in such an implementation may then handle the building of a sound model that represents the sounds made by key presses, and may also subsequently apply that model to sounds passed by the computing device 102 , so as to remove in substantial part sounds that are attributable to key presses. FIG. 2 is a block diagram that shows an example of a portable computing device 200 for removing noise from audio. The portable computing device 200 may be used, for example, by a presenter of a teleconference. The presenter's speech can be broadcast to other client computing devices while the presenter uses a keyboard or other input control during the teleconference. The portable computing device 200 cancels or reduces the sound of key presses and other background noises that result from activating the input controls, in order to isolate the speech or other audio that is intended to be included in the audio signal, from the noises that result from activation of the input controls. The portable computing device 200 includes a microphone 206 for capturing a sound input 202 . The microphone 206 can be integrated into the portable computing device 200 , as shown here, or can be a peripheral device such as a podium microphone or a headset microphone. The portable computing device 200 includes at least one input control 208 , such as a keyboard, a mouse, a touch screen, or remote control, which receives an activation 204 , such as a key press, button click, or touch screen tap. An activation of a key is identified by data received from the key itself (e.g., electrical signal from contact being made in the key and/or a subsequent corresponding key press event being issued by hardware, software, and/or firmware that processes the electrical signal from the contact) rather than from sounds received from the microphone 206 , through which activation can only be inferred. The input control 208 generates an activation event 212 that is processed by one or more applications that execute on the portable computing device 200 . For example, a key press activation event may result in the generation of a text character on a display screen by a word processor application, or a button click (another form of key press) activation event may be processed as a selection in a menu of an application. In addition to creating the activation event 212 , the activation 204 of the input control 208 also results, substantially simultaneously as perceived by a typical user, in the generation of an audible sound or noise. In some instances, the audible sound is an unintended consequence of activating mechanical parts of the input control 208 and/or from the user contacting the input control 208 , such as a click, a vibration, or a tapping sound. In the example of a microphone integrated within the portable computing device 200 , this unintended noise can appear magnified when registered by the microphone 206 . This may be a result of the key actuation vibrating the housing of the portable computing device 200 and the housing transferring that vibration to the microphone 206 . The microphone 206 creates an audio signal 210 from the sound input 202 and passes the audio signal 210 to a noise cancellation module 214 . The input control 208 causes the generation of the activation event 212 as a result of the activation 204 of the input control 208 and passes data that indicates the occurrence of the activation event 212 to the noise cancellation module 214 . In some implementations, the noise cancellation module 214 is a software module or program that executes in the foreground or background in the portable computing device 200 . In some implementations, the audio signal 210 and/or data for the activation event 212 are routed by an operating system and/or device drivers of the portable computing device 200 from the microphone 206 and the input control 208 to the noise cancellation module 214 . The noise cancellation module 214 determines that the audio signal 210 contains the sound that results from the activation 204 of the input control 208 based upon the activation event 212 . Such a determination may be made by correlating the occurrence of the activation event 212 with a particular sound signature in the audio signal 210 , and then canceling the sound signature using stored information. For example, the noise cancellation module 214 can retrieve a representation of the sound, such as a waveform, from an input control waveform storage 216 . The input control waveform storage 216 stores waveforms that represent the sounds produced by activation of the input controls in the portable computing device 200 . The noise cancellation module 214 applies the waveform associated with the activation event 212 to the audio signal 210 to destructively interfere with the sound of the activation 204 to create a modified audio signal 218 . An input control waveform can be an audio signal substantially in phase, substantially in antiphase (e.g., 180 degrees out of phase), or substantially in phase and with an inverse polarity, with the sound input 202 . In some implementations, such a waveform may also be constructed in real-time. In the case of a substantially in phase input control waveform, the inverse of the input control waveform can be added to the audio signal 210 to destructively interfere with the sound of the activation 204 and thus filter out such noise. In the case of an input control waveform substantially in antiphase or substantially in phase and with an inverse polarity with the sound input 202 , the input control waveform can be added to the audio signal 210 . In some implementations, the input control waveforms can be created by the noise cancellation module 214 and stored in the input control waveform storage 216 . For example, during a training session, the noise cancellation module 214 can use the microphone 206 to record one or more instances of the sound that results from the activation 204 of the input control 208 . In the case of multiple instances, the noise cancellation module 214 may calculate an aggregate or an average of the recorded sounds made by activation of the input control 208 . In some implementations, the manufacturer of the portable computing device 200 can generate the input control waveforms and distribute the input control waveforms for the particular model of device (but generally not the particular device) preloaded with the portable computing device 200 in the input control waveform storage 216 . As the sound of the input control 208 changes over time, for example as a spring in the input control 208 loses elasticity or parts in the input control 208 become worn, the noise cancellation module 214 can periodically or at predetermined times re-record and recalculate the input control waveforms. In some implementations, the noise cancellation module 214 can record the input control waveforms in the background while the portable computing device 200 performs another task. For example, the noise cancellation module 214 can record input control waveforms and associate the waveforms with corresponding activation events while the user types a document into a word processor application. In some implementations, one or more of the noise cancellation module 214 and the input control waveform storage 216 can be included in a server system. For example, where processor power and/or storage capacity may be limited in the portable computing device 200 , the server system can perform the noise cancellation operations of the noise cancellation module 214 and/or the storage of the input control waveform storage 216 . In another example, the server system can perform the noise cancellation and storage functions if the server system is already being used as a proxy for the teleconference between the computing devices. In another example, the server system can perform the noise cancellation and storage functions if the modified audio is not needed for playback at the portable computing device 200 where it was first recorded and is only or primarily being sent to other computing devices. Where a server system performs alteration of an audio signal, the sound model for providing cancellation may be specific to a particular user's device (and the model may be accessed in association with an account for the user) or may be more general and aimed at a particular make, class, or model of device. A user's account may store information that reflects such a device identifier, or data that identifies the type of device may be sent with the audio data and other data that is provided from the device to the server. The server may then use the identifying information to select the appropriate sound model for that device type from among multiple such sound models that the server system may store. Returning to the particular components themselves, the noise cancellation module 214 passes the modified audio signal 218 to another application, device, or system, such as a teleconference application 220 , the operating system of the portable computing device 200 , or to another computing system or audio recording system. For example, the portable computing device 200 may be a portable or handheld video game device. The video game device receives the sound input 202 and cancels the sounds of one or more input controls. The video game device can execute a video game which communicates with other video game consoles. Users can interact with the video game devices using input controls and speak to the users of the other video game devices with microphones. The video game or video game device can include the noise cancellation module 214 to modify user speech input by minimizing the sounds of activating the input controls that are picked up by the microphone 206 . In some implementations, the noise cancellation module 214 and/or the input control waveform storage 216 are included in a video game server system. The video game server system can store input control waveforms that are averaged over multiple ones of the video game devices and/or waveforms that are specific to individual video game devices. The video game devices can send unmodified speech inputs and information describing activation events occurring at the respective video game devices to the video game server system. The video game server system performs the noise cancellation on the speech inputs and forwards the modified speech inputs to the video game devices. In some implementations, the video game server system can add multiple speech inputs together to make a single modified audio signal that is then forwarded to the video game devices. In some implementations, the video game server system creates a single modified audio signal for each of the video game devices, such that the single modified audio signal sent to a particular video game device does not include the speech input that originated from that particular video game device. In another example, the portable computing device 200 may be a mixing board that can receive an audio input, including a performer singing, and cancel noises from input controls on an instrument, such as from keys on an electronic keyboard or buttons on an electronic drum set. The mixing board receives the sound input 202 from the microphone 206 , which includes the singing from the performer as well as the noise of mechanical manipulation of the electronic instrument (e.g., the noise of a pressed keyboard key or the noise of an electronic drumhead or button being struck or pressed). The mixing board includes the noise cancellation module 214 that detects activation events from the electronic instrument and filters the sound input 202 to remove or minimize the noise of the instrument in the audio input. FIG. 3 is a flow chart that shows an example of a process 300 for removing noise from audio. The process 300 may be performed, for example, by a system such as the system 100 or the portable computing device 200 . For clarity of presentation, the description that follows uses the system 100 and the portable computing device 200 as examples for describing the process 300 . However, another system, or combination of systems, may be used to perform the process 300 . Prior to an audio recording session, the process 300 begins with the building ( 302 ) of a model of input control audio signals that represent sound that is produced by activating one or more input controls. Such a phase may serve to help train the device. In addition, the input control audio signals are associated with corresponding input control activation events that result from activating the input controls. For example, the user 106 may initiate a calibration routine on the computing device 102 . The computing device 102 can prompt the user to activate each of the input controls 110 . The computing device 102 can then record and store the noises 112 associated with the activation of the input controls 110 . Alternatively, the training process may place a paragraph or other block of text on a screen, and may ask the user to type the text in a quiet room, while correlating particular key presses (as sensed by activation of the keys) with observed sounds. Such observed sounds may, individually, be used as the basis for canceling signals that are applied later when their particular corresponding key is activated by a user. During the audio recording session, the process 300 receives ( 304 ) a recording session audio signal recorded from a microphone in the computing device. For example, a user may speak into the microphone 206 , and the microphone 206 can generate the audio signal 210 . Also during the audio recording session, the process 300 receives ( 306 ) an input control activation event that results from activation of a corresponding one of the input controls. The received input control activation event is included among the input control activation events associated with the input control audio signals. For example, the user may also activate the input controls 208 , which can generate the activation event 212 . The process 300 retrieves ( 308 ) an input control audio signal that is associated with the received input control activation event from among the input control audio signals in the model. For example, the noise cancellation module 214 can retrieve the input control audio signal from the input control waveform storage 216 that is associated with the activation event 212 . The process 300 applies ( 310 ) the input control audio signal to the received recording session audio signal to remove the input control audio signal from the received recording session audio signal. For example, the noise cancellation module 214 can receive the activation event 212 and look up an input control audio signal from the input control waveform storage 216 . The noise cancellation module 214 , after delaying for a time difference associated with the input control audio signal and the activation event 212 , applies the input control audio signal to the audio signal 210 to generate the modified audio signal 218 . The process 300 outputs ( 312 ) the modified audio signal through an audio interface of the computing device or through a network interface to another computing device or a server system. For example, the noise cancellation module 214 can send the modified audio signal 218 to the teleconference application 220 . FIG. 4 shows an example of a computing device 400 and a mobile computing device that can be used to implement the techniques described here. The computing device 400 is intended to represent various forms of digital computers, such as laptops, desktops, workstations, personal digital assistants, servers, blade servers, mainframes, and other appropriate computers. The mobile computing device is intended to represent various forms of mobile devices, such as personal digital assistants, cellular telephones, smart-phones, and other similar computing devices. The components shown here, their connections and relationships, and their functions, are meant to be exemplary only, and are not meant to limit implementations of the inventions described and/or claimed in this document. The computing device 400 includes a processor 402 , a memory 404 , a storage device 406 , a high-speed interface 408 connecting to the memory 404 and multiple high-speed expansion ports 410 , and a low-speed interface 412 connecting to a low-speed expansion port 414 and the storage device 406 . Each of the processor 402 , the memory 404 , the storage device 406 , the high-speed interface 408 , the high-speed expansion ports 410 , and the low-speed interface 412 , are interconnected using various busses, and may be mounted on a common motherboard or in other manners as appropriate. The processor 402 can process instructions for execution within the computing device 400 , including instructions stored in the memory 404 or on the storage device 406 to display graphical information for a GUI on an external input/output device, such as a display 416 coupled to the high-speed interface 408 . In other implementations, multiple processors and/or multiple buses may be used, as appropriate, along with multiple memories and types of memory. Also, multiple computing devices may be connected, with each device providing portions of the necessary operations (e.g., as a server bank, a group of blade servers, or a multi-processor system). The memory 404 stores information within the computing device 400 . In some implementations, the memory 404 is a volatile memory unit or units. In some implementations, the memory 404 is a non-volatile memory unit or units. The memory 404 may also be another form of computer-readable medium, such as a magnetic or optical disk. The storage device 406 is capable of providing mass storage for the computing device 400 . In some implementations, the storage device 406 may be or contain a computer-readable medium, such as a floppy disk device, a hard disk device, an optical disk device, or a tape device, a flash memory or other similar solid state memory device, or an array of devices, including devices in a storage area network or other configurations. A computer program product can be tangibly embodied in an information carrier. The computer program product may also contain instructions that, when executed, perform one or more methods, such as those described above. The computer program product can also be tangibly embodied in a computer- or machine-readable medium, such as the memory 404 , the storage device 406 , or memory on the processor 402 . The high-speed interface 408 manages bandwidth-intensive operations for the computing device 400 , while the low-speed interface 412 manages lower bandwidth-intensive operations. Such allocation of functions is exemplary only. In some implementations, the high-speed interface 408 is coupled to the memory 404 , the display 416 (e.g., through a graphics processor or accelerator), and to the high-speed expansion ports 410 , which may accept various expansion cards (not shown). In the implementation, the low-speed interface 412 is coupled to the storage device 406 and the low-speed expansion port 414 . The low-speed expansion port 414 , which may include various communication ports (e.g., USB, Bluetooth, Ethernet, wireless Ethernet) may be coupled to one or more input/output devices, such as a keyboard, a pointing device, a scanner, or a networking device such as a switch or router, e.g., through a network adapter. The computing device 400 may be implemented in a number of different forms, as shown in the figure. For example, it may be implemented as a standard server 420 , or multiple times in a group of such servers. In addition, it may be implemented in a personal computer such as a laptop computer 422 . It may also be implemented as part of a rack server system 424 . Alternatively, components from the computing device 400 may be combined with other components in a mobile device (not shown), such as a mobile computing device 450 . Each of such devices may contain one or more of the computing device 400 and the mobile computing device 450 , and an entire system may be made up of multiple computing devices communicating with each other. The mobile computing device 450 includes a processor 452 , a memory 464 , an input/output device such as a display 454 , a communication interface 466 , and a transceiver 468 , among other components. The mobile computing device 450 may also be provided with a storage device, such as a micro-drive or other device, to provide additional storage. Each of the processor 452 , the memory 464 , the display 454 , the communication interface 466 , and the transceiver 468 , are interconnected using various buses, and several of the components may be mounted on a common motherboard or in other manners as appropriate. The processor 452 can execute instructions within the mobile computing device 450 , including instructions stored in the memory 464 . The processor 452 may be implemented as a chipset of chips that include separate and multiple analog and digital processors. The processor 452 may provide, for example, for coordination of the other components of the mobile computing device 450 , such as control of user interfaces, applications run by the mobile computing device 450 , and wireless communication by the mobile computing device 450 . The processor 452 may communicate with a user through a control interface 458 and a display interface 456 coupled to the display 454 . The display 454 may be, for example, a TFT (Thin-Film-Transistor Liquid Crystal Display) display or an OLED (Organic Light Emitting Diode) display, or other appropriate display technology. The display interface 456 may comprise appropriate circuitry for driving the display 454 to present graphical and other information to a user. The control interface 458 may receive commands from a user and convert them for submission to the processor 452 . In addition, an external interface 462 may provide communication with the processor 452 , so as to enable near area communication of the mobile computing device 450 with other devices. The external interface 462 may provide, for example, for wired communication in some implementations, or for wireless communication in other implementations, and multiple interfaces may also be used. The memory 464 stores information within the mobile computing device 450 . The memory 464 can be implemented as one or more of a computer-readable medium or media, a volatile memory unit or units, or a non-volatile memory unit or units. An expansion memory 474 may also be provided and connected to the mobile computing device 450 through an expansion interface 472 , which may include, for example, a SIMM (Single In Line Memory Module) card interface. The expansion memory 474 may provide extra storage space for the mobile computing device 450 , or may also store applications or other information for the mobile computing device 450 . Specifically, the expansion memory 474 may include instructions to carry out or supplement the processes described above, and may include secure information also. Thus, for example, the expansion memory 474 may be provide as a security module for the mobile computing device 450 , and may be programmed with instructions that permit secure use of the mobile computing device 450 . In addition, secure applications may be provided via the SIMM cards, along with additional information, such as placing identifying information on the SIMM card in a non-hackable manner. The memory may include, for example, flash memory and/or NVRAM memory (non-volatile random access memory), as discussed below. In some implementations, a computer program product is tangibly embodied in an information carrier. The computer program product contains instructions that, when executed, perform one or more methods, such as those described above. The computer program product can be a computer- or machine-readable medium, such as the memory 464 , the expansion memory 474 , or memory on the processor 452 . In some implementations, the computer program product can be received in a propagated signal, for example, over the transceiver 468 or the external interface 462 . The mobile computing device 450 may communicate wirelessly through the communication interface 466 , which may include digital signal processing circuitry where necessary. The communication interface 466 may provide for communications under various modes or protocols, such as GSM voice calls (Global System for Mobile communications), SMS (Short Message Service), EMS (Enhanced Messaging Service), or MMS messaging (Multimedia Messaging Service), CDMA (code division multiple access), TDMA (time division multiple access), PDC (Personal Digital Cellular), WCDMA (Wideband Code Division Multiple Access), CDMA2000, or GPRS (General Packet Radio Service), among others. Such communication may occur, for example, through the transceiver 468 using a radio-frequency. In addition, short-range communication may occur, such as using a Bluetooth, WiFi, or other such transceiver (not shown). In addition, a GPS (Global Positioning System) receiver module 470 may provide additional navigation- and location-related wireless data to the mobile computing device 450 , which may be used as appropriate by applications running on the mobile computing device 450 . The mobile computing device 450 may also communicate audibly using an audio codec 460 , which may receive spoken information from a user and convert it to usable digital information. The audio codec 460 may likewise generate audible sound for a user, such as through a speaker, e.g., in a handset of the mobile computing device 450 . Such sound may include sound from voice telephone calls, may include recorded sound (e.g., voice messages, music files, etc.) and may also include sound generated by applications operating on the mobile computing device 450 . The mobile computing device 450 may be implemented in a number of different forms, as shown in the figure. For example, it may be implemented as a cellular telephone 480 . It may also be implemented as part of a smart-phone 482 , personal digital assistant, or other similar mobile device. Various implementations of the systems and techniques described here can be realized in digital electronic circuitry, integrated circuitry, specially designed ASICs (application specific integrated circuits), computer hardware, firmware, software, and/or combinations thereof. These various implementations can include implementation in one or more computer programs that are executable and/or interpretable on a programmable system including at least one programmable processor, which may be special or general purpose, coupled to receive data and instructions from, and to transmit data and instructions to, a storage system, at least one input device, and at least one output device. These computer programs (also known as programs, software, software applications or code) include machine instructions for a programmable processor, and can be implemented in a high-level procedural and/or object-oriented programming language, and/or in assembly/machine language. As used herein, the terms machine-readable medium and computer-readable medium refer to any computer program product, apparatus and/or device (e.g., magnetic discs, optical disks, memory, Programmable Logic Devices (PLDs)) used to provide machine instructions and/or data to a programmable processor, including a machine-readable medium that receives machine instructions as a machine-readable signal. The term machine-readable signal refers to any signal used to provide machine instructions and/or data to a programmable processor. To provide for interaction with a user, the systems and techniques described here can be implemented on a computer having a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user and a keyboard and a pointing device (e.g., a mouse or a trackball) by which the user can provide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form, including acoustic, speech, or tactile input. The systems and techniques described here can be implemented in a computing system that includes a back end component (e.g., as a data server), or that includes a middleware component (e.g., an application server), or that includes a front end component (e.g., a client computer having a graphical user interface or a Web browser through which a user can interact with an implementation of the systems and techniques described here), or any combination of such back end, middleware, or front end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include a local area network (LAN), a wide area network (WAN), and the Internet. The computing system can include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other. Although a few implementations have been described in detail above, other modifications are possible. For example, the logic flows depicted in the figures do not require the particular order shown, or sequential order, to achieve desirable results. In addition, other steps may be provided, or steps may be eliminated, from the described flows, and other components may be added to, or removed from, the described systems. Accordingly, other implementations are within the scope of the following claims.

The subject matter of this specification can be embodied in, among other things, a computer-implemented method for removing noise from audio that includes building a sound model that represents noises which result from activations of input controls of a computer device. The method further includes receiving an audio signal produced from a microphone substantially near the computer device. The method further includes identifying, without using the microphone, an activation of at least one input control from among the input controls. The method further includes associating a portion of the audio signal as corresponding to the identified activation. The method further includes applying, from the audio model, a representation of a noise for the identified activation to the associated portion of the audio signal so as to cancel at least part of the noise from the audio signal.

BACKGROUND OF THE INVENTION The present invention is directed to light fixtures and particularly to a florescent light fixture capable of replacing an incandescent light in a ceiling down-light. Incandescent lamps have long been employed as down-lights in ceilings. In modern building construction, these lights are often mounting in fixtures above a suspended ceiling such that the depending bulb has a front glass near the plane of the suspended ceiling. These bulbs are normally screwed into the fixture by means of a standardized light socket for incandescent bulbs. Incandescent bulbs have recently come into some disfavor because of the heat generated by the bulbs and because of the energy consumption and lack of lighting efficiency when compared with florescent lighting. National standards are ever increasing with respect to the amount of heat which can be conducted to a junction box, a ceiling and other near-by components. The incandescent light generates a significant amount of heat energy which can make such standards difficult to meet, particularly in ceiling mounted light fixture applications. On the other hand, florescent lighting generates far less heat which might be conveyed to such a junction box, ceiling or the like. However, florescent fixtures normally require substantially different mounting and socket systems than are required by incandescent bulbs; and replacement of incandescent lighting by florescent lighting has generally required major revisions to the building. The level of efficiency of incandescent bulbs, as measured by the amount of light generated per unit of input power, is much lower than that for florescent lighting. Consequently, to obtain the same lighting effect, greater amounts of energy are required for any given situation. With the increase in the cost of power, incandescent lighting has become relatively costly. Again, switching to florescent lighting can also be very expensive because of the great differences in mounting and electrical hook-ups. The cost of switching to florescent lighting has often out-weighed any benefit achieved from the more efficient system. SUMMARY OF THE INVENTION The present invention is directed to a lighting fixture which adapts to mountings for incandescent bulbs. However, the fixture of the present invention is for florescent lights. Thus, low cost replacement of incandescent lighting without disruptive modifications to the building or building interior can be achieved using the present invention. At the same time, the heating problems associated with incandescent lighting and the power drain associated with incandescent lighting are to a large extent obviated. Because down-lights for ceiling mounted incandescent bulbs are not standardized as to the location of the light socket relative to the ceiling and because of the restriction of space adjacent the socket, a standardized replacement fixture for such incandescent bulbs in down-light installations has required custom modifications normally resulting in the entire replacement of the incandescent light fixture. By the present invention, an extensible member is employed which is able to accommodate a wide variety of light socket positions. At the same time, the extensible member provides advantageous placement of the light plug and permits threading of the plug into the existing socket and adjustment of the lighting fixture such that the backing plate for the florescent light will be flush with the ceiling. Accordingly, it is an objective of the present invention to provide a florescent light fixture easily installed in a mounting for incandescent bulbs. Other and further objects and advantages will appear hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view, as seen from below, of the present invention. FIG. 2 is a side view of the present invention with portions of the body thereof broken away for clarity. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Turning in detail to the figures, a florescent light fixture is disclosed with a toroidal florescent tube 10 positioned on the fixture. A diffuser in any number of esthetic configurations may be positioned around the florescent tube 10. However, as the diffuser has no bearing on the present invention, it has been excluded. The tube 10 is mounted to a backing plate 12 by means of brackets 14. Three such brackets are illustrated. The backing plate 12 is subtantially of sheet metal construction and normally has a white or reflective under-surface to ensure diffusion of a maximum amount of light. A hole extends through the backing plate 12 for receipt of a starter 16. In this way, the starter may be replaced without disassembly of the unit when it becomes defective. The coupling 18 also extends from the backing plate 12 for providing electrical power to the tube 10 at the contacts provided in the tube electrode assembly 20. Mounted to the back side of the backing plate 12 is a transformer box 22. The transformer box 22 is conveniently attached to the backing plate 12 by fasteners 24. Located within the terminal box 22 are the electrical leads, the transformer and starter necessary for the operation of a florescent light. In the present embodiment, the transformer box 22 is substantially cylindrical with the backing plate 12 at one end and a formed top 26 at the other. This compact configuration for the transformer box 22 allows it to be positioned in a location originally occupied by an incandescent light bulb. Rigidly fixed to the top 26 of the transformer box 22 by means of fasteners 28 is a shaft 30. The shaft 30 is constructed of a tube having a hollow, square cross-section. The shaft 30 extends from the backing plate 12 a distance which is less than the anticipated distance between the ceiling and the socket in the incandescent fixture with which the present fixture is to be associated. Cooperating with the shaft 30 is another shaft 22 which is also of tubing having a hollow, square cross-section. The shaft 32 is smaller than the shaft 30 in order that the shaft 32 may be telescoped within the shaft 30. Some clearance is considered advantageous for ease of assembly and to prevent binding. However, the shaft 32 is preferably large enough so that it is unable to rotate to any substantial extent within the shaft 30. In this way, torque may be transmitted from the shaft 30 to the shaft 32. The combined shafts 30 and 32 thus form an extensible member which allows relative movement between the shafts in an axial direction but which rigidly constrains each shaft from rotating relative to the other shaft. To provide resistance to the relative axial movement between shafts 30 and 32, a spring 34 is disposed within shaft 30, between the walls of shaft 30 and shaft 32. The spring 34 is in compression between the two shafts to create the resistance to axial movement. The spring 34 is held in place by a fastener 36, as can be seen in FIG. 2. The spring 34 provides another function in that it cooperates with a stop 38 formed in one wall of the shaft 32 to limit axial movement between the shafts 30 and 32. The shafts 30 and 32 are shown in maximum extension with the stop 38 encountering the spring 34 in FIG. 2. FIG. 2 also shows, in phantom the extensible member in its contracted state. A plug 40 is employed with the present fixture. This plug is capable of mating with a standardized light socket which is normally employed with incandescent bulbs. The plug 40 is secured to the opposite end of the extensible member from the transformer box 22 at one end of shaft 32. Conventional fasteners 42 may be employed. The employment of the present florescent light fixture of the present invention in mountings for incandescent bulbs is relatively simple. The incandescent bulb is removed from a ceiling down-light leaving the fixture itself. The extensible member is extended to ensure that the plug 40 will reach the socket of the incandescent bulb mounting. The entire florescent light fixture is then threaded into the socket for electrical contact. The configuration of the shafts 30 and 32 allows transmission of the torque from the backing plate 12 and transformer box 22 to the plug 40. Once the plug 40 is positioned, the backing plate 12 and transformer 22 is simply forced upwardly until the backing plate 12 is flush with the ceiling. This is made possible by the extensible member extending between the plug 40 and the transformer box 22. Once the backing plate 12 is in position against the ceiling, the florescent tube 10 may be positioned and a diffuser also mounted on the backing plate 12. Naturally, the tube and defuser may be preassembled with the lamp prior to installation. For removal, the backing plate 12 is simply lowered and the entire fixture is rotated out of the socket. Thus, an easily installed florescent light fixture is disclosed by the present invention which does not require substantial modification to an existing incandescent bulb down-light fixture. Thus, modification of a lighting system for florescent lights may be accomplished for savings in money and electrical power and for reduction in generated heat. While embodiments and applications of this invention have been shown and described, it would be apparent to those skilled in the art that many more modifications are possible without departing from the inventive concepts herein described. The invention, therefore, is not to be restricted except by the spirit of the appended claims.

A light fixture for florescent tubes designed to be mounted in incandescent light bulb sockets. This fixture is particularly adapted for replacing incandescent down-lights mounted in ceilings. A standard plug is positioned at one end of an extensible member while a transformer box and backing plate are attached at the other end of the extensible member. The extensible member includes telescoping tubes of square cross-section.

BACKGROUND OF THE INVENTION This invention relates to a lighting device for an observation unit, an image pickup unit or the like which is used for observing or picking up an image of a surface of a specimen sample, and more particularly to an improvement in a lighting device which is adapted to light or illuminate a surface of a section to be observed (hereinafter referred to as "observed section") of a specimen sample while providing a light field due to vertical projection and/or a dark field due to lateral projection as required. There are conventionally known an observation unit for observing an image or magnified image of a surface of an observed section of a specimen sample which is an object subject to observation and an image pickup unit for displaying the image on a picture plane of a monitor TV to indirectly observe it. Each of the observation unit and the image pickup unit is adapted to locate a lighting head or an image pickup head each having a projecting means incorporated therein in a manner to face the surface of the observed section of the specimen sample to light the observed section, to thereby permit the observation to be carried out. In each of the observation unit and image pickup unit thus constructed, lighting is generally carried out by a vertical projection method mainly using vertically projected light wherein parallel light beams are vertically irradiated to a longitudinal surface portion of the surface of the observed section of the specimen sample in a direction perpendicular thereto or by a lateral projection method mainly using laterally projected light wherein light beams are obliquely irradiated to the longitudinal surface portion of the surface of the observed section a direction oblique with respect to the surface portion. However, when the surface of the specimen sample which is an object subject to observation has relatively fine unevenness, individual execution of the vertical projection method or lateral projection method fails to permit the fine unevenness on the surface to be precisely observed. In order to avoid the problem, concurrent execution of both projection methods would be considered. Unfortunately, this causes the observation device or image pickup device to be highly complicated in structure. SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing disadvantage of the prior art. Accordingly, it is an object of the present invention to provide a lighting device which is capable of being suitable for use for an observation unit, an image pickup unit or the like while solving the above-described problems of the prior art. It is another object of the present invention to provide a lighting device which is capable of carrying out satisfactory lighting or illumination irrespective of conditions of a surface of an observed section of a specimen sample. It is a further object of the present invention to provide a lighting device which is capable of selectively accomplishing at least one of light field lighting and dark field lighting depending on a purpose of observation carried out on a surface of an observed section of a specimen sample. In accordance with the present invention, a lighting device is provided. The lighting device includes a tube body constituted by a cylindrical barrel. The cylindrical barrel has a central optical axis defined therein and is formed at a lower end portion thereof with an objective opening in a manner to face a surface of an observed section of a specimen sample. The lighting device also includes a light guide cylinder arranged in a lower portion of the cylindrical barrel so that a central axis thereof is aligned with the optical axis. The objective opening is divided into a central region in which a light field area is defined and a peripheral region which is defined outside the central region and in which a dark field area is defined. The cylindrical barrel is formed at an upper portion thereof with a light field light inlet opening through which light field light of which the quantity is adjusted is introduced into the cylindrical barrel. The lighting device further includes a semitransparent reflection mirror provided in the cylindrical barrel so as to positionally correspond to the light field light inlet opening and be aligned with the optical axis. The semitransparent reflection mirror reflects the introduced light field light to form vertically projected light irradiated on the light field area, to thereby illuminate light toward a longitudinal surface portion of the surface of the observed section of the specimen sample in a direction perpendicular thereto. The cylindrical barrel is formed at a lower portion thereof with a dark field light inlet opening through which dark field light of which the quantity is adjusted is introduced into the cylindrical barrel. Moreover, the lighting device includes a first reflection mirror arranged on an outer periphery of the light guide cylinder in the cylindrical barrel so as to positionally correspond to the dark field light inlet opening and reflecting the introduced dark field light to form vertically projected light directed through a space between the light guide cylinder and the cylindrical barrel to the dark field area, as well as a second reflection mirror arranged on an inner periphery of a lower end of the cylindrical barrel and reflecting the vertically projected dark field light to form laterally projected light directed to the light field area, to thereby light a lateral surface portion of the surface of the observed section of the specimen sample in a direction lateral with respect to the surface portion; whereby any one of illumination by both light field light and dark field light of each of which the quantity is adjusted as required, illumination by only the light field light, and illumination by only the dark field light is selected as desired. In a preferred embodiment of the present invention, the lighting device may further comprise a light field luminous source for emitting the light field light and a dark field luminous source for emitting the dark field light, which are provided independent from each other; and a light field light adjusting slit member for adjusting the quantity of the light field light emitted by the light field luminous source and a dark field light adjusting slit member for adjusting the quantity of the dark field light emitted by the dark field luminous source. In another preferred embodiment of the present, the lighting device may further comprise a common luminous source for the light field light and dark field light, whereby light emitted from the common luminous source is divided into the light field light and dark field light; and a light field light adjusting slit member for adjusting the quantity of the light field light and a dark field light adjusting slit member for adjusting the quantity of the dark field light. In a further embodiment of the present invention, the lighting device may further comprise a light field luminous source for emitting the light field light and a dark field luminous source for emitting the dark field light, which are provided independent from each other, wherein the light field luminous source and dark field luminous source each are applied thereto a voltage, to thereby permit the quantity of each of the light field light and dark field light emitted by the luminous sources to be adjusted. In the lighting device of the present invention constructed as described above, the luminous sources for the light field light and dark field light are turned on while keeping the objective opening of the tube body positioned right opposite to the surface of the observed section of the specimen sample. Then, light field light of which the quantity is adjusted is introduced through the light field light inlet opening into the cylindrical barrel and downwardly reflected by the semitransparent reflection mirror to form vertically projected light, which straight travels to the light field area to illuminate the longitudinal surface portion of the surface of the specimen sample in a direction perpendicular to the surface portion. Whereas, dark field light of which the quantity is adjusted is introduced through the dark field light inlet opening into the cylindrical barrel and then downwardly reflected by the first reflection mirror to form vertically projected light, which then travels through the space between the cylindrical barrel and the light guide cylinder toward the dark field area. Thereafter, the dark field light is laterally reflected by the second reflection mirror to form laterally projected light, which then travels to the light field area to illuminate the lateral surface portion of the surface of the specimen sample in a direction lateral with respect to the surface portion. Thus, the present invention permits any one of illumination by both light field light and dark field light of each of which the quantity is adjusted as required, illumination by only the light field light, and illumination by only the dark field light to be selected as desired, resulting in selectively providing a lighted two-dimensional image of the surface and its lighted three-dimensional image as desired. BRIEF DESCRIPTION OF THE DRAWINGS These and other objects and many of the attendant advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings; wherein: FIG. 1 is a schematic sectional view showing a first manner of lighting operation of an embodiment of a lighting device according to the present invention which is applied to an observation unit, an image pickup unit or the like; FIG. 2 is a schematic sectional view showing a second manner of lighting operation of the lighting device shown in FIG. 1; FIG. 3 is a schematic sectional view showing a third manner of lighting operation of the lighting device shown in FIG. 1; FIG. 4 is a schematic sectional view showing a first manner of lighting operation of a second embodiment of a lighting device according to the present invention which is applied to an observation unit, an image pickup unit or the like; and FIG. 5 is a schematic sectional view showing a first manner of lighting operation of a third embodiment of a lighting unit according to the present invention which is applied to an observation unit, an image pickup unit or the like. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Now, a lighting device according to the present invention will be described hereinafter with reference to the accompanying drawings. Referring first to FIGS. 1 to 3, a first embodiment of a lighting device according to the present invention which is effectively applied to an observation unit, an image pickup unit or the like is illustrated. A lighting device of the illustrated embodiment includes a tube body 11, which includes a cylindrical barrel 12. The cylindrical barrel 12 is formed at a lower portion thereof with an objective opening 13 in such a manner that a longitudinal central axis of the opening 13 is aligned with a central optical axis A defined in the cylindrical barrel 12. The objective opening 13 is arranged so as to face a surface of an observed section of a specimen sample B. Also, the cylindrical barrel 12 is formed at an upper portion thereof with a light guide opening 14 for guiding, toward an observation section (not shown), reflected light Lc obtained by irradiating the surface of the observed section of the specimen sample B with illuminating light for a light field (hereinafter referred to as "light field light") designated at reference character La and/or illuminating light for a dark field (hereinafter referred to as "dark field light") designated at reference character Lb. Further, in the opening 13 of the cylindrical barrel 12, a light field area a is defined in a manner to be positioned in a central region about the optical axis A and a dark field area b is defined in a manner to be positioned in a peripheral region outside the central region. The cylindrical barrel 12 is also formed on one side of the upper portion thereof with a light field light inlet opening 21 of a relatively small area for light field illumination and at a portion thereof below the opening 21 on the same side with a dark field light inlet opening 31 of a relatively large area. In addition, the cylindrical barrel 12 is provided on an inside thereof positionally corresponding to the dark field light inlet opening 31 with a light guide cylinder 41 which is so arranged that a longitudinal central axis thereof is aligned with the optical axis A. The light guide cylinder 41 acts to partition the light field area a in the central region and the dark field area b in the peripheral region from each other, so that the inside of the cylinder 41 permits the light field light La to be guided to the light field area a in the central region and the outside of the cylinder 41 permits the dark field light Lb to be guided to the dark field area b in the peripheral region. The lighting device of the illustrated embodiment also includes a luminous source for a light field (hereinafter referred to as "light field luminous source") designated at reference numeral 51 which is adapted to carry out light field illumination and a slit member for adjusting the quantity of light for a light field (hereinafter referred to as "light field light adjusting slit member") designated at reference numeral 52. The luminous source 51 and slit member 52 are arranged outside the cylindrical barrel 12 so as to be opposite to each other and positionally correspond to the light field light inlet opening 21 with the slit member 52 being interposed between the opening 21 and the luminous source 51. The luminous source 51 may comprise a halogen lamp, an ultraviolet (UV) lamp or the like. The slit member 52 functions to adjust the quantity of light emitted from the luminous source 51 upon turning-on of the source within a range of between, for example, 0% of the total light quantity and 100% thereof and, as required, adjust a direction of the light so as to permit it to be directed toward the light field light inlet opening 21. Also, the lighting device may include a lens (not shown) for suitably forming the light into parallel light beams. The cylindrical barrel 12 is provided therein with a half mirror or semitransparent reflection mirror 22, which is arranged so as to permit the light field light La introduced through the light field light inlet opening 21 into the barrel 12 to be guided as vertically projected light along the central optical axis A toward the light field area a in the central region of the objective opening 13 and permit the reflected light Lc to be taken out from the surface of the observed section of the specimen sample B. The light guide cylinder 41 is provided at a lower portion of an inside thereof with a fixed or variable constriction 23 for restricting a range of irradiation or vertical projection of the light field light La reflected by the reflection mirror 22, to thereby improve resolution. In addition, the lighting device of the illustrated embodiment further includes a luminous source for a dark field (hereinafter referred to as "dark field luminous source") designated at reference numeral 61 which is adapted to carry out light field illumination and a slit member for adjusting the quantity of light for a dark field (hereinafter referred to as "dark field light adjusting slit member") designated at reference numeral 62. The dark field luminous source 61 and slit member 62 are arranged outside the cylindrical barrel 12 so as to be opposite to each other and positionally correspond to the dark field light inlet opening 31 with the slit member 62 being interposed between the opening 31 and the luminous source 61. The luminous source 61 may comprise a halogen lamp, an ultraviolet (UV) lamp or the like. The slit member 62 functions to adjust the quantity of light emitted from the luminous source 61 upon turning-on of the source 61 within a range between, for example, 0% of the total light quantity and 100% thereof and, as required, adjust a direction of the light so as to permit it to be directed toward the dark field light inlet opening 31. Also, the lighting device may include a diffusion filter (not shown) for suitably eliminating unevenness of concentration of the light. The cylindrical barrel 12 is provided therein with a first reflection mirror 32, which is arranged so as to permit the dark field light Lb introduced through the dark field light inlet opening 31 into the barrel 12 to be guided, as vertically projected light, in parallel to the central optical axis A toward the dark field area b in the peripheral region of the objective opening 13. Further, the cylindrical barrel 12 is provided at a portion thereof below the first reflection mirror 32 with a second reflection mirror 33 so as to be positioned in the objective opening 13. The second reflection mirror 33 is arranged so as to permit the dark field light Lb reflected by the first reflection mirror 32 and then vertically projected to be re-reflected by the second reflection mirror, to thereby be directed in the form of laterally projected light from the dark field area b to the light field area a. Now, the manner of operation of the lighting device of the illustrated embodiment will be described hereinafter with reference to FIG. 1 showing a first lighting manner wherein the specimen sample B is observed utilizing both light field lighting and dark field lighting. First, the quantity of light field light La and that of dark field light Lb are selectively adjusted through the light field light adjusting slit member 52 and dark field light adjusting slit member 62 as required, respectively, while keeping the objective opening 13 of the tube body 11 right opposite to the surface of the observed section of the specimen sample B which is an object subject to observation and keeping the light field luminous source 51 and dark field luminous source 61 turned-on to emit light therefrom. Then, the light field light La is introduced through the light field light inlet opening 21 into the tube body 11 while being kept perpendicular to central optical axis A and then reflected by the semitransparent reflection mirror 22. This results in the light field light La forming vertically projected light which downwardly travels parallel to the central optical axis A toward the light field area a of the central region in the light guide cylinder 41. Then, the light field light La is constricted through the constriction 23, to thereby light the whole surface of the observed section of the specimen sample B in a direction perpendicular to a longitudinal surface portion of the surface, resulting in a lighted image of the surface of the observed section being longitudinally two-dimensionally observed. More particularly, this mainly results in a lighted image of the longitudinal surface portion of the surface being two-dimensionally observed. Then, light forming the image upwardly travels as reflected light in the light guide cylinder 41 and passes through the semitransparent reflection mirror 22, resulting in being picked up through the light guide opening 14 by the observation section (not shown). Thus, the two-dimensional image of the longitudinal surface portion of the surface of the specimen sample B can be observed while being lighted, as desired. The quantity of the light field light La to be irradiated may be adjusted through the slit member 52, to thereby permit the observation to be more satisfactorily carried out. The dark field light Lb is introduced through the dark field light inlet opening 31 into the tube body 11 so as to be perpendicular to the central optical axis A and then reflected by the first reflection mirror 32. This causes the dark field light Lb to form vertically projected light which downwardly straight travels parallel to the central optical axis A through a space between the cylindrical barrel 12 and the light guide cylinder 41 toward the dark field area b of the peripheral region. Subsequently, the dark field light Lb is reflected by the second reflection mirror 33 in the dark field area b, to thereby form laterally projected light, which straight travels toward the light field area a of the central region. This results in the dark field light Lb or laterally projected light illuminating the surface of the observed section of the specimen sample B in a direction parallel to the surface, to thereby permit the surface to be laterally two-dimensionally observed. A lighted image or observed image of the surface thus obtained travels upwardly as reflected light in the light guide cylinder 41 and passes through the semitransparent reflection mirror 22, resulting in being picked up through the light inlet opening 14 by the observation section. Thus, the lighted lateral image of the surface of the specimen sample B can be observed as desired. More particularly, this mainly permits a lighted image of a lateral surface portion of the surface of the specimen sample B to be two-dimensionally obtained. The quantity of irradiation of the dark field light Lb may be adjusted through the slit member 62, to thereby permit the observation to be more satisfactorily carried out. Thus, in the lighting device of the illustrated embodiment, the light field light La forms vertically projected light which independently lights or illuminates the surface of the observed section of the specimen sample B in a direction right opposite or perpendicular to the surface of the observed section or along the optical axis A, to thereby mainly provide a lighted longitudinal two-dimensional image of the surface. Concurrently, the dark field light Lb forms laterally projected light directed from the dark field area b to the light field area a, which independently lights the surface of the specimen sample in a direction substantially parallel to the surface of the observed section or in a direction substantially perpendicular or oblique to the optical axis, to thereby provide lighted lateral two-dimensional image of the surface. Thus, the lighting device of the illustrated embodiment permits lighting carried out mainly by the vertically projected light and that mainly by the laterally projected light to cooperate with each other to form lighted three-dimensional image of the surface which can be readily observed. Further, the quantities of light field light La and dark field light Lb may be adjusted during observation of the lighted image, to thereby permit a dark shadow portion of the image to be eliminated, to thereby facilitate the observation. Further, the manner of operation of the lighting device of the illustrated embodiment will be described hereinafter with reference to FIG. 2 showing a second lighting manner wherein the specimen sample B is observed utilizing only light field lighting. Similar to the first lighting manner described above with reference to FIG. 1, the objective opening 13 of the tube body 11 is kept right opposite to the longitudinal surface portion of the surface of the observed section of the specimen sample B which is an object subject to observation and the light field luminous source 51 and dark field luminous source 61 are kept turned-on to emit light field light La and dark field light Lb therefrom, respectively. Then, the quantity of the dark field light Lb emitted is restricted to a level of 0% through the dark field light adjusting slit member 62, resulting in a situation as if the dark field luminous source 61 were kept turned off. Alternatively, the dark field luminous source 61 is turned off and only the light field luminous source 51 is kept turned on, and the quantity of the light field light La emitted is selectively adjusted through the light field light adjusting slit member 52 as required, resulting in forming only the light field light La into vertically projected light. The vertically projected light thus obtained lights or illuminates the whole surface of the observed section of the specimen sample B in a direction perpendicular to the longitudinal surface portion of the surface of the observed section or in a direction parallel to the optical axis A, to thereby permit the surface to be longitudinally two-dimensionally observed. Adjustment of the quantity of irradiation of the light field light La permits the observation to be more satisfactorily carried out. Moreover, the manner of operation of the lighting device of the illustrated embodiment will be described hereinafter with reference to FIG. 3 showing a third lighting manner wherein the specimen sample B is observed utilizing only dark field lighting. The objective opening 13 of the tube body 11 is kept right opposite to the longitudinal surface portion of the surface of the observed section of the specimen sample B and the light field luminous source 51 and dark field luminous source 61 are kept turned-on to emit light field light La and dark field light Lb light therefrom, respectively. Then, the quantity of the light field light La emitted is restricted to a level of 0% through the light field light adjusting slit member 52, resulting in a situation as if the light field luminous source were kept turned off. Alternatively, the light field luminous source 51 is turned off and only the dark field luminous source 61 is kept turned on, and the quantity of the dark field light Lb emitted is selectively adjusted through the dark field light adjusting slit member 62 as required, to thereby form only the dark field light Lb into laterally projected light. The laterally projected light thus obtained illuminates the whole surface of the observed section of the specimen sample B in a direction substantially parallel to the longitudinal surface portion of the observed section, to thereby permit the surface to be laterally two-dimensionally observed. Adjustment of the quantity of irradiation of the dark field light Lb permits the observation to be more satisfactorily carried out. Referring now to FIG. 4, a second embodiment of a lighting device according to the present invention is illustrated, wherein a lighting device of the second embodiment is practived in the same manner as the first lighting manner of the first embodiment described above with reference to FIG. 1. In a lighting device of the illustrated embodiment, a single luminous source 71 which may likewise comprise a halogen lamp, an ultraviolet (UV) lamp or the like is commonly used to produce light field light La and dark field light Lb. More particularly, light Ld for illumination emitted commonly from the common luminous source 71 is guided to both a light field side and a dark field side through a suitable means such as optical fibers or the like. Light guided to the light field side passes through a light field light adjusting slit member 52, so that light field light La of which the quantity is adjusted is output; whereas light guided to the dark field side likewise passes through a dark field light adjusting slit member 62, so that dark field light La of which the quantity is adjusted is output. Thus, the second embodiment may be operated in substantially the same manner as the first lighting manner of the first embodiment described above with reference to FIG. 1. The remaining part of the second embodiment may be constructed in substantially the same manner as the first embodiment. Also, the lighting device of the second embodiment may carry out operation in the same lighting manner as the second lighting manner of the first embodiment described above with reference to FIG. 2 by outputting light field light La of which the quantity is adjusted through the slit member 52 on the light field side and fully closing, on the dark field side, the dark field light adjusting slit member 62 to interrupt dark field light Lb. Also, operation of the lighting device of the second embodiment in the same lighting manner as the third lighting manner of the first embodiment may be carried out by fully closing the light field light adjusting slit member 52 to interrupt light field light La, resulting in only dark field light Lb of which the quantity is adjusted through the dark field light adjusting slit member 62 being output. Referring now to FIG. 5, a third embodiment of a lighting device according to the present invention is illustrated, wherein a lighting device of the third embodiment is operated in the same manner as the first lighting manner of the first embodiment described above with reference to FIG. 1. In the lighting device of the illustrated embodiment, the light field light adjusting slit member 52 and dark field light adjusting slit member 62 used in the first embodiment shown in FIGS. 1 to 3 are omitted. Substitutely, adjustment of the quantity of each of light field light La and dark field light Lb is carried out by adjusting a voltage applied to each of luminous sources 51 and 61. The remaining part of the third embodiment may be constructed in substantially the same manner as the first embodiment. Thus, it will be noted that the third embodiment simplifies the structure of the lighting device. Also, the third embodiment constructed as described above may carry out operation in the same lighting manner as the second lighting manner of the first embodiment described above with reference to FIG. 2 by controlling a voltage applied to the light field luminous source 51 to adjust the quantity of light field light La which is then output and by interrupting application of a voltage to the dark field luminous source 61 to prevent emission of the light from the luminous source 61. Further, the lighting device of the third embodiment may be operated in the same lighting manner as the third lighting manner of the first embodiment shown in FIG. 1 by interrupting feeding of electric power to the light field luminous source 51 to prevent emitting of light field light La and controlling a voltage applied to the dark field luminous source 61 to output dark field light Lb of which the quantity is adjusted. As can be seen foregoing, the lighting device of the present invention is so constructed in the manner that the light field luminous source and dark field luminous source are turned on to emit light therefrom while keeping the objective opening of the tube body right opposite to the surface of the observed section of the specimen sample and light field light and dark field light of each of which the quantity is adjusted are output. Then, the light field light is irradiated as vertically projected light on the whole surface of the observed section of the specimen sample in a direction perpendicular to the longitudinal surface portion of the surface in the light field area of the central region of the objective opening to mainly obtain a lighted image of the longitudinal surface portion and the dark field is irradiated as laterally projected light on the whole surface of the observed section from the dark field area of the peripheral section to the light field area or in a direction parallel to the longitudinal surface portion of the surface of the objected section to mainly obtain a lighted image of the lateral surface portion of the surface of the observed section. The lighted images thus obtained can be selectively observed while being changed over as desired. Alternatively, the light field illumination and dark field illumination can be synthesized to provide a lighted three-dimensional image of the surface which can be readily observed. Thus, the present invention permits the surface of the observed section of the specimen sample to be readily observed in a desired manner depending on an object of the observation. While preferred embodiments of the invention have been described with a certain degree of particularity with reference to the drawings, obvious modifications and variations are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

A lighting device capable of lighting a surface of an observed section of a specimen sample so as to permit an object of observation of the surface to be satisfied even when the surface has relatively fine unevenness. Any one of light field illumination mainly using vertically projected light, dark field illumination mainly using laterally projected light and a combination thereof is selectively carried out with respect to the surface of the specimen sample as desired, to thereby selectively provide a lighted two-dimensional image of the surface and its lighted three-dimensional image as desired.

FIELD AND BACKGROUND OF THE INVENTION The present invention relates to a refrigerating apparatus. To facilitate understanding of the present invention it will be helpful that a conventional refrigerating apparatus including an air cooling type condenser adapted to cooperate with a water cooling type condenser will be briefly described below with reference to FIG. 1 which is a system diagram schematically illustrating the conventional refrigerating apparatus. First, description will be made as to the case when the refrigerating apparatus is operated with the aid of air cooling. Refrigerant gas discharged from a compressor 1 at high temperature and pressure enters an air cooling type condensor 2 with a blower 6 disposed in the proximity thereof for the purpose of cooling so that heat included in refrigerant gas is emitted from the air cooling type condenser 2 whereby it is liquidized therein. Refrigerant is then delivered to a water cooling type condenser 3. In this case, however, no cooling water flows through the water cooling type condenser 3 and therefore the latter serves merely as a liquid receiver or storage, because no heat radiation is effected therefrom. After leaving the water cooling type condenser 3, refrigerant reaches an expansion valve 4 in which it is subjected to pressure reduction and then it enters an evaporator 5 in which it is evaporated by extracting heat from the surroundings. After completion of evaporation refrigerant comes back to the compressure 1 and thereby a single cycle of refrigeration is finished. Next, description will be made as to the case when the refrigerating apparatus is operated with the aid of water cooling. Refrigerant gas discharged from the compressor 1 at high temperature and pressure enters the air cooling type condenser 2 with the blower 6 disposed in the proximity thereof for the purpose of cooling. When the blower 6 is rotated, a part of heat included in refrigerant is emitted into the environmental air by way of forcible convection, whereas when the blower 6 is not rotated, the air cooling type condenser 2 is heated up to a considerably high temperature but a part of heat included in refrigerant is also emitted into the environmental air by way of natural convection. Thus, a part of heat is emitted from the air cooling type condenser 2 in that way and thereafter refrigerant is delivered to the water cooling type condenser 3 through which cooling water 7 flows circulatively at all time. Heat removal is effected further from the water cooling type condenser 3 with the aid of the cooling water 7 until refrigerant gas is liquidified therein. Then, refrigerant liquid reaches the expansion valve 4 in which it is subjected to pressure reduction. Next, it enters the evaporator 5 in which it is evaporated by extracting heat from the surroundings. After completion of evaporation it comes back to the compressor 1 and thereby a single cycle of refrigeration is finished. In the above-described conventional refrigerating system it is required that the water cooling type condenser 3 serves not only as a liquid receiver during operation of the refrigerating apparatus with the aid of air cooling but also as an ordinary water cooling type condenser during operation of the same with the aid of water cooling. Accordingly, the water cooling type condenser 3 is required to hold a sufficient volume of refrigerant therein, resulting in considerably increased space required for mounting it. Further, there is necessity for storing a surplus volume of refrigerant in the water cooling type condenser in order to assure that the latter serves as a liquid storage satisfactorily. As a result an ample volume of refrigerant is required for operating the conventional refrigerating apparatus. SUMMARY OF THE INVENTION Thus, the present invention has been proposed with the foregoing background in mind. It is an object of the present invention to provide an improved refrigerating apparatus which requires reduced space for mounting it. To accomplish the above object there is proposed in accordance with the present invention a refrigerating apparatus of the type including a compressor, air cooling type condensers, an expansion valve and an evaporator which are connected in series one after another in the refrigerating system, wherein the air cooling type condensers comprise an upstream air cooling type condenser and a downstream air cooling type condenser which are separately arranged in the refrigerating system and a water cooling type condenser is disposed between both the upstream and downstream air cooling type condensers. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings will be briefly described below. FIG. 1 is a system diagram which schematically illustrates a conventional refrigerating apparatus including an air cooling type condenser adapted to cooperate with a water cooling type condenser. FIG. 2 is a system diagram which schematically illustrates a refrigerating apparatus in accordance with the first embodiment of the invention, and FIG. 3 is a system diagram which schematically illustrates a refrigerating apparatus in accordance with the second embodiment of the invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS Now, the present invention will be described in greater detail hereunder with reference to FIGS. 2 and 3. First, description will be made as to a refrigerating apparatus in accordance with the first embodiment of the invention which is schematically illustrated in FIG. 2. In this connection it should be noted that the same or similar apparatus components as those in FIG. 1 are identified with the same reference numerals. In the drawing reference numeral 12 designates a first air cooling type condenser, reference numeral 13 designates a water cooling type condenser, reference numeral 14 designates a second air cooling type condenser, reference numeral 17 designates a blower, reference numeral 18 designates cooling water and reference numeral 19 designates another blower. Now, operation of the refrigerating apparatus in accordance with the first embodiment of the invention will be first described in case when it is operated with air for air cooling. Refrigerant gas enters the first air cooling type condenser 12 at high temperature and pressure after it is discharged from a compressor 1. Since the blower 17 is rotating for the first air cooling type condenser 12, refrigerant gas is caused to cool in the latter while it is emitting a part of the energy included therein. A part of the cooled refrigerant gas is liquidized and thereafter refrigerant flows into the water cooling type condenser 13. It should be noted that in case of operation of the refrigerating apparatus with the aid of air cooling no cooling water flows in the water cooling type condenser 13 and therefore the latter has no capability of condensing refrigerant gas. For this reason it serves merely as a piping. Refrigerant enters the second air cooling type condenser 14 after it leaves the water cooling type condenser 13. Since the blower 19 is rotating for the second air cooling type condenser 14, refrigerant emits heat further until condensation is completed therein. Next, liquid refrigerant reaches an expansion valve 4 in which it is in turn subjected to pressure reduction. It is then delivered to an evaporator 5 in which it is evaporated by extracting heat from the surroundings. After completion of evaporation refrigerant comes back to the compressor 1 and thereby a single cycle of refrigeration is finished. Next, operation of the refrigerating apparatus will be described as to the case when it is operated with the aid of water cooling. Refrigerant gas enters the first air cooling type condenser 12 at high temperature and pressure after it is discharged from the compressor 1. When the blower 17 is rotated, a part of heat is emitted from refrigerant gas by way of forcible convection around the first air cooling type condenser 12, whereas when the blower is not rotated, the first air cooling type condenser 12 is heated up to a considerably high temperature, a part the of heat is emitted into the environmental air by way of natural convection. After a part of the heat included in refrigerant is emitted in the first air cooling type condenser 12, it flows into the water cooling type condenser 13 through which cooling water 18 flows circulatively at all time. Owing to the fact that cooling water flows therethrough for the purpose of cooling a substantial part of refrigerant gas is liquidized and thereafter liquid refrigerant flows into the second air cooling type condenser 14. If the blower 19 is rotated residual refrigerant gas is liquidized by way of forcible convection, whereas when the blower is not rotated it is liquidized by way of natural convection which facilitates heat radiation from the second air cooling type condenser 14. Thus, liquidization of refrigerant is completed. If refrigerant gas is already liquidized when it leaves the water cooling type condenser 13, the second air cooling type condenser 14 serves merely as a piping. After completion of liquidization of refrigerant in the second air cooling type condenser 14 in that way refrigerant liquid is delivered to the expansion valve 4 in which it is subjected to pressure reduction and then it flows into the evaporator 5 in which it is evaporated by extracting heat from the surroundings. After completion of evaporation refrigerant comes back to the compressor 1 and thereby a single cycle of refrigeration is finished. As will be readily apparent from the above description, the water cooling type condenser 13 serves merely as a piping in case of operation of the refrigerating apparatus with the aid of air cooling, whereas the second air cooling type condenser 14 serves merely as a refrigerant liquid receiver in case of operation of the apparatus with the aid of water cooling. Thus, it results that the water cooling type condenser 13 requires a very small volume of inside space through which refrigerant flows and therefore there is necessity for a small area of space where the water cooling type condenser 13 is to be mounted and that no extra volume of refrigerant is required because the water cooling type condenser 13 does not serve as a refrigerant liquid storage and thus it becomes possible to reduce a required volume of refrigerant. In the above-described embodiment of the invention both the first air cooling type condenser 12 and the second air cooling type condensor 14 are arranged separately one from another. Alternatively, they may be made integral with one another as a single air cooling condenser in which the water cooling type condenser 13 is disposed at the position located midway of the refrigerant passages. Further, both the blowers 17 and 19 may be replaced with a single one or more than two blowers may be arranged for the same purpose. Next, description will be made as to a refrigerating apparatus in accordance with the second embodiment of the invention which is schematically illustrated in FIG. 3. The same apparatus components as those in FIG. 2 are identified with the same reference numerals but their repeated description will not be required. In the drawing reference numeral 21 designates an upper communication pipe, reference numeral 22 designates a lower communication pipe and reference numeral 23 designates a junction therebetween. In case of the illustrated refrigerating apparatus operation of the latter is the same as in case of the foregoing first embodiment until refrigerant leaves the water cooling type condenser 13 for both the types of air cooling and water cooling. When the apparatus is operated with the aid of air cooling, a large part of refrigerant flowing into a gas-liquid separator 20 after leaving the water cooling type condenser 13 is gaseous while a small part of the same is in the form of liquid. Refrigerant gas flows into the second gas cooling type condenser 14 via the upper communication pipe 21. Since a large volume of refrigerant flows through the second air cooling type condenser 14 in this case, a high level of refrigerant pressure loss is caused whereby the liquid surface in the gas-liquid separator 20 assumes a considerably lower position. Thus, when the lowermost end position of the gas-liquid separator 20 is lowered sufficiently, it results that all refrigerant gas flows into the second air cooling type condenser 14. While the blower 19 is rotating, heat included in refrigerant gas is emitted into the environmental air until it is liquidized. Then, liquidized refrigerant reaches the junction 23 in which it is united with another liquidized refrigerant coming from the gas-liquid separator 20 via the lower communication pipe 22 and the combined refrigerant is delivered to the expansion valve 4 in which it is subjected to pressure reduction. Next, it enters the evaporator 5 in which it is evaporated by extracting heat from the surroundings. After completion of evaporation refrigerant comes back to the compressor 1 and thereby a single cycle of refrigeration is finished. Next, when the apparatus is operated with the aid of water cooling, a large part of refrigerant flowing into the gas-liquid separator 20 after leaving the water cooling type condenser 13 is in the form of liquid while a small part of the same is gaseous. Refrigerant liquid is separated from refrigerant gas in the gas-liquid separator 20 and it is then delivered to the junction 23 via the lower communication pipe 22, whereas refrigerant gas flows into the second air cooling type condenser 14 via the upper communication pipe 21 in which it is liquidized in the same manner as in the foregoing first embodiment and after completion of liquidization refrigerant liquid reaches the junction 23. If liquidization is completed until refrigerant leaves the water cooling type condensor 13, no refrigerant flows into the second air cooling type condenser 14 and thus the gas-liquid separator 20 serves merely as a liquid receiver. Refrigerant liquid united at the junction 23 reaches the expansion valve 4 in which it is subjected to pressure reduction. Then, it is delivered to the evaporator 5 in which it is evaporated by extracting heat from the surroundings. After completion of evaporation refrigerant comes back to the compressor 1 and thereby a single cycle of refrigeration is finished. As will be readily understood from the above description, in addition to the functional effects obtained from the refrigerating apparatus in accordance with the first embodiment in which a large part of refrigerant flows through the second air cooling type condenser 14 in the form of liquidized refrigerant during operation of the apparatus with the aid of water cooling the refrigerating apparatus in accordance with the second embodiment has such a functional effect that refrigerant liquid is discharged from the gas-liquid separator 20 without any entrance into the second air cooling type condenser 14. As a result it is assured that a volume of refrigerant liquid to be held in the second air cooling type condenser 14 can be substantially reduced and thereby a volume of refrigerant required for the refrigerating apparatus can be reduced correspondingly. It should be noted that the lowermost end position of the gas-liquid separator 20 may be determined in such a manner that differential pressure is developed at the junction 23 corresponding to the maximum pressure loss of refrigerant in the second air cooling type condenser 14. While the present invention has been described above with respect to two preferred embodiments, it should be of course be understood that it should not be limited only to them but many changes or modifications may be made without any departure from the spirit and scope of the invention. Since the refrigerating apparatus of the invention as constructed in the above-described manner consists in that an upstream air cooling type condenser and a downstream air cooling type condenser are separately arranged in a refrigerating system including a compressor, air cooling type condensers, an expansion valve and an evaporator and a water cooling type condenser is disposed between both the upstream and downstream air cooling type condensers, it is assured that a space required for mounting the refrigerating apparatus is substantially reduced, resulting in excellent industrial advantages being obtained therefrom.

An improved refrigerating apparatus including a compressor, air cooling type condensers, an expansion valve and an evaporator which are connected in series one after another in the refrigerating system, is disclosed, wherein the improvement consists in that the air cooling type condensers comprise an upstream air cooling type condenser and a downstream air cooling type condenser which are separately arranged in the refrigerating system and a water cooling type which condenser is disposed between both the upstream and downstream air cooling type condensers. Owing to the arrangement of the refrigerating apparatus in accordance with the invention, reduced space required for mounting the refrigerating apparatus, and decreased volume of refrigerant required for operating the refrigerating apparatus are assured.

FIELD OF THE INVENTION [0001] The invention relates to novel organic fluorides and methods for their production. BACKGROUND OF THE INVENTION [0002] Fluorine substitution is a powerful tool to improve the bioavailability of pharmaceuticals and agrochemicals. Thus, an expansive set of nucleophilic and electrophilic reagents have been developed to replace various C—X functional groups with C—F. [0003] [ CheMBioChem Special Issue: Fluorine In the Life Sciences 2004, 5, 557726]. Simplest among the nucleophilic fluorinating reagents are “anhydrous” or “naked” organic fluoride salts, represented by tetramethylammonium fluoride (TMAF) [Christe, K. O, et al, J. Am. Chem. Soc. 1990, 112, 7619-25, 1-methylhexamethylenetetramine fluoride (MHAF) [Gnann, R. Z., et al, J. Am. Chem. Soc. 1997, 119, 112-115] and tetramethylphosphonium fluoride (TMPF) [Kornath, A, et al, Inorg. Chem. 2003, 42, 2894-2901]. Highly soluble anhydrous fluoride salts possessing a wide variety of alkyl groups are desirable for synthetic purposes, but these compounds cannot be prepared according to current methodologies. [0004] Typical of prior art methods for preparing such salts are those described in U.S. Pat. No. 5,369,212 and Canadian patent no. 2035561. [0005] The preparation of absolutely anhydrous fluoride salts whose cations are substituted with alkyl groups possessing beta-hydrogen atoms has proved to be a significant challenge. Approximately 20 years ago, the first claims for “anhydrous” tetrabutylammonium fluoride appeared. The compounds were prepared by physical drying of the hydrated salt, i.e., dynamic high vacuum (<0.1 mmHg) to remove water for at least 48 hours from TBAF.3H 2 O at 40˜45° C. (JOC, 1984, 49, 3216-3219). However, there was still 0.1 to 0.3 equiv of water in this “anhydrous” TBAF and copius quantities of the elimination products (tributylamine, bifluoride ion, and butane) as a result of this process. The side reactions and the presence of water and tributylamine significantly decrease the reactivity of the fluoride ion and lead to significant side reactions, such as hydrolysis of the starting substrates. An example of water's deleterious effects upon the reactivity of TBAF can be seen in simple model reactions. For example, if TBAF that is dried using physical methods is combined with benzyl chloride or benzyl bromide at room temperature to 40° C., formation of benzyl fluoride required 8 to 12 hours. In comparison, if truly anhydrous TBAF were employed, the same reaction would only take a few minutes or less at low temperatures and give quantitative yields. [0006] Later, individual syntheses of tetramethylammonium fluoride (TMAF) (JACS, 1990, 112, 7619-7625), cobaltocenium fluoride (Cp 2 CoF), (JACS, 1994, 116, 11165-11166), 1-Methylhexamethylenetetramine fluoride (MHAF) (JACS, 1997, 119, 112-115), tetramethylphosphonium fluoride (TMPF) (Inorg. Chem., 2003, 42, 2894-2901) as well as several others were synthesized and characterized as “naked” or “anhydrous” fluoride salts. However, each of these salts has specific drawbacks in terms of solubility or reactivity, and the preparative methods for synthesizing these individual salts are not applicable for the preparation of a wide variety of fluoride salts. Anhydrous fluoride salts with alkyl groups capable of beta-elimination (ethyl, propyl, butyl, isopropyl, pentyl, isobutyl, etc.) in particular are not accessible by current methods. [0007] Generally, then, these compounds are commonly prepared in a hydrated state and are subsequently dried by heating under dynamic vacuum or by azeotropic distillation. However, the conditions used to dry these salts are often incompatible with a variety of desirable cations. For example, dried tetrabutylammonium fluoride, (TBAF) [Cox, D. P., et al, J. Org. Chem. 1984, 49, 3216-19] is reported to decompose by Hofmann elimination at room temperature. The salt isolated after dehydration is contaminated with copious amounts of bifluoride ion (HF 2 ) and tributylamine [Shannn, R. K., et al, J. Org. Chem. 1983, 48, 2112-14]. These considerations and findings have led to the belief among those skilled in the art that “it is very unlikely that pure, anhydrous tetraalkylammonium fluoride salts have ever, in fact, been produced in the case of ammonium ions susceptible to E2 eliminations” [Sharma et al, supra]. [0008] It is an object of the present invention to provide a novel method of producing truly anhydrous organic fluoride salts and reagents. [0009] It is a further object of the invention to provide novel anhydrous organic fluoride salts and reagents. SUMMARY OF THE INVENTION [0010] The above and other objects are realized by the present invention one embodiment of which relates to a method of synthesizing an anhydrous fluoride salt having the formula: [Q n M] x+ F x − comprising the nucleophilic substitution of a fluorinated aromatic or fluorinated unsaturated organic compound with a salt having the formula: [Q n M] x+ A x − in an inert polar, aprotic solvent; wherein M is an atom capable of supporting a formal positive charge, the n groups Q are independently varied organic moieties, n is an integer such that the [Q n M] carries at least one formal positive charge, x is an integer defining the number of formal positive charge(s), +, carried by the [Q n M], A − is an anionic nucleophile capable of substituting for F in the fluorinated compound and F represents fluorine or a radioisotope thereof. [0011] Another embodiment of the invention concerns anhydrous organic fluoride salts and reagents of the above formula, preferably produced by the above-described invention. [0012] Still other embodiments of the invention relate to the use of the anhydrous organic fluoride salts and reagents of the invention in methods, processes and syntheses wherein the non-anhydrous salts and reagents are employed. BRIEF DESCRIPTION OF THE DRAWINGS [0013] FIGS. 1-10 depict 19 F NMR and 1 H NMR spectra for various reaction products produced by the reactions described herein (vide infra). DETAILED DESCRIPTION OF THE INVENTION [0014] The present invention is predicated on the discovery that a wide variety of truly anhydrous organic fluoride salts and reagents may be synthesized in one step by the nucleophilic substitution of various fluorinated organic compounds with organic salts of diffusely charged anionic nucleophiles capable of forming strong bonds to carbon in a nucleophilic substitution reaction. Thus, employing the methods of the invention a wide range of novel anhydrous salts can be prepared using one simple procedure. Moreover, as the examples set forth below demonstrate, the method of the invention allows many sensitive or unstable fluoride salts to be prepared easily. Such compounds would decompose rapidly under the conditions employed in typical literature preparations of similar compounds. [0015] Although the invention is principally exemplified and illustrated herein for preparing tetrabutylammonium fluoride, it will be understood by those skilled in the art that the inventive method may be utilized to prepare many and varied anhydrous fluoride salts. It will also be understood by those skilled in the art that the method of the invention may also be utilized to prepare radioisotopic fluoride salts (e.g., 18 F). [0016] The reaction may be carried out at low temperatures [−35° C. to RT] in polar aprotic solvents such as tetrahydrofuran, dimethyl sulfoxide, diethyl ether, dioxane, dimethoxyethane, methyl tert-butyl ether, acetonitrile, acetone, methylethylketone, tetrahydrofuran, dimethylformamide, dimethylacetamide, N-methylpyrolidinone, butyronitrile, or in aromatic solvents such as toluene, pyridine, benzonitrile, or diphenyl ether. Other suitable solvents include carbonates such as diethyl carbonate and hexamethylphosphoric triamide. In preferred embodiments tetrahydrofuran, dimethylsulfoxide, and acetonitrile are the solvents employed. Halogenated solvents such as methylene chloride or dichloroethane are decomposed rapidly by anhydrous fluoride salts, and are thus generally not useful for this synthetic procedure. [0017] In the above-described formulae, Q is an organic moiety capable of undergoing E2 elimination and may be, e.g., alkyl, alkenyl, alkynyl, or form the backbone or sidechain of a polymer. M may be N, P or any element capable of supporting a formal positive charge. The anion A may any diffusely charged anionic nucleophile capable of forming strong bonds to carbon in a nucleophilic substitution reaction, such as, e.g., cyanide, isothiocyanate, thiocyanate, alkyl- and arylthiolates, or azide. In preferred embodiments cyanide is the nucleophile employed. [0018] [Q n M] x+ A x − is preferably a tetraalkylammonium cyanide, a trialkylarylammonium cyanide, a dialkyldiarylammonium cyanide, an alkyltriarylammonium cyanide, or a tetraarylammonium cyanide; Q being an organic moiety capable of undergoing E2 elimination. [0019] The fluorinated compound nucleophically substituted in the method of the invention is preferably a fluorinated benzene, alkene or alkyne with a large number of fluorine atoms per unit weight e.g., hexafluorobenzene, octafluoronaphthalene, octafluorotoluene, pentafluorobenzonitrile, pentafluoropyridine, decafluorobiphenyl, etc. For the generation of isotopically labeled anhydrous fluoride salts (i.e., TBA 18 F) a singly fluorinated arene is sufficient, e.g., 4-fluorobenzonitrile. [0020] The reaction scheme for the method of the invention is: [0021] Nucleophile substitution reactions are generally well known in the art as exemplified in U.S. Pat. Nos. 6,794,401; 6,451,921; 6,156,812 and 5,854,084, inter alia. [0022] Thus tetrabutylammonium fluoride (TBAF) is easily prepared in one step at low temperatures by the nucleophilic substitution of the hexafluorobenzene with tetrabutylammonium cyanide. Adventitious water is readily scavenged by the hexacyanobenzene by-product of the reaction. [0023] The constraints on a fluoride-generating synthesis grounded in nucleophile substitution reactions are quite severe and dictate a careful choice of the nucleophile. Because the enthalpic driving force for fluoride liberating reaction derives almost exclusively from ion-pairing and ΔBDE terms, and because the C sp2 -F bond in aromatics (as well as unsaturated compounds) is exceptionally strong (126 kcal/mol), only diffusely charged anionic nucleophiles capable of forming strong bonds to carbon are capable of acting in nucleophile substitution reactions reactions at low temperature in polar aprotic solvents. Cyanide ion, a potent, weakly basic nucleophile that forms strong bonds to sp2-hybridized carbon (BDE=133 kcal/mol) is an excellent candidate. It will be understood by those skilled in the art, however, that any similar diffusely charged anionic nucleophile may also be employed in the method of the invention, such as, e.g., isothiocyanate, isocyanate, cyanate, thiocyanate, alkyl- and arylthiolates, or azide. [0024] As illustrated in the examples below, treatment of hexafluorobenzene with tetrabutylammonium cyanide (TBACN) (in 1:1 to 1:6 molar ratios) in the polar aprotic solvents THF, acetonitrile, or DMSO at or below room temperature gives excellent yields of anhydrous TBAF. 19 F NMR spectroscopy indicates that the overall yield of TBAF in solution in all cases is >95%. Cyano substitution dramatically increases the fluorinated benzene ring's susceptibility to further nucleophilic attack, as is evidenced by the observation of pentacyanofluorobenzene and hexafluorobenzene as the principal fluorinated aromatic species in the reaction solution, even if 1:1 TBACN:C 6 F 6 stoichiometry is employed. [0025] In THF, colorless to light yellow anhydrous TBAF precipitated from cooled (−35° C.) solutions and yields of the isolated salt ranged from 40% to 70%. Freshly isolated TBAF displayed one singlet 19 F NMR signal at −86 ppm in THF and four 1 H NMR signals for the TBA cation. The characteristic doublet of HF 2 — at δ=−147 ppm (J H-F =128 Hz) was observed in freshly prepared solution samples, and in samples precipitated from THF and redissolved. The concentration of TBA HF 2 — was generally less than 2% that of TBAF. Solid anhydrous TBAF is stable under nitrogen at −35° C. for weeks. TBAF decomposes slowly in THF or in the solid state by E2 elimination if warmed above 0° C. [0026] TBAF can be prepared conveniently in situ in polar aprotic solvents at room temperature and used without isolation or purification. Treatment of (CD) 3 SO or CD 3 CN solutions of TBACN with C 6 F 6 (at 25° C.) gave highly colored, concentrated (up to 2 M) solutions of TBAF exhibiting the characteristic 19 F NMR signals for ion-paired fluoride (Table 1). Small amounts (generally <4%) of HF 2 — are also generated in these solvents. TBAF is stable for hours in CD 3 CN and for more than 24 h in DMSO at 25° C. TABLE 1 19 F NMR data of anhydrous fluoride salts Compd Solvent Chemical Shift TBAF THF −86 ppm CD 3 CN −72 ppm (CD 3 ) 2 SO −75 ppm TMAF (CD 3 ) 2 SO  −75 ppm a CD 3 CN −74 ppm TMPF CD 3 CN −70 ppm a generated in situ with TMACN. [0027] The origins of the unexpected stability of TBAF in THF, CH 3 CN, and DMSO lie in the relatively low temperatures used for generation of the salt, and in the dehydrating properties of the main reaction byproduct, hexacyanobenzene. Hexacyanobenzene has been shown to add water to form the strong acid pentacyanophenol (pKa=2.9). Thus, adventitious water is removed from solution during the course of the initial fluoride-generating nucleophilic reaction, forming two equivalents of bifluoride ion per equivalent of water and the innocuous byproduct TBA pentacyanophenoxide. Added water (0.08 eq.) is scavenged from TBAF solutions prepared in this manner, as is evidenced by time-dependent changes in the linewidth and chemical shift of the fluoride ion 19 F NMR resonance, and by the generation of 0.16 eq. of HF 2 —. [0028] It has been shown that the addition of alkoxide nucleophiles to hexacyanobenzene is rapid under basic conditions, and that the resultant pentacyanophenyl alkyl ethers are subject to S N 2 displacement. This pathway is amply demonstrated by the direct fluorination of simple alcohols. For example, if excess TBAF (12 eq.) is generated in situ in (CD 3 ) 2 S0 and used directly, benzyl alcohol is converted quantitatively to benzyl fluoride, presumably via the intermediacy of benzyl pentacyanophenyl ether. Thus, generation of TBAF in the presence of hexacyanobenzene can provide DAST-like deoxofluorination of alcohols. [0029] Given that fluoride, the smallest anion (ionic radius=1.33 Å) forms extremely strong bonds to protons (H—F BDE=136 kcal/mol, HF 2 — BDE=46 kcal/mol) F − is expected to be an aggressive Brønsted base. It has been shown that TMAF deprotonates CD 3 CN over the course of several hours consuming F − to form DF 2 −2 . A similar process is observed with TBAF in CD 3 CN; nevertheless, no decomposition of the TBA cation is observed over the course of 24 hours. In contrast, no deuterium exchange is observed in solutions of TBAF in (CD 3 ) 2 SO over the same time period. These results do not, however, allow a good estimate of the ion-pair basicity of fluoride ion in polar aprotic solvents, since slow rates of proton transfer and side reactions may preclude generation of a true equilibrium mixture. An additional complication is that any proton transfer to fluoride ion is followed by a rapid conversion to HF 2 — under these conditions. [0030] The kinetic barriers inherent in the proton transfer from C—H bonds to F − are apparent in the following example. While (CD 3 ) 2 SO does not undergo proton exchange with residual HF 2 in TBAF solutions, if a (CD 3 ) 2 SO solution of purified TBAF (precipitated from THF) is spiked with water (0.08 eq.), a slow (2 h) conversion of HF 2 − to DF 2 − is observed. Deuterium exchange occurs without a detectable increase in the bifluoride ion concentration, indicating that deprotonation of water by TBAF is strongly disfavored under these conditions (see FIG. 1 ). Upon standing, hydrated DMSO solutions of purified TBAF evolve butene and tributylamine by E2 elimination, demonstrating the sensitivity of TBAF to hydroxylic impurities in polar aprotic solvents. [0031] The anhydrous organic fluoride salts of the invention find utility in a wide variety of methods, processes, reactions and syntheses employing the corresponding non-anhydrous fluoride salts. The substitution of the anhydrous fluoride salts of the invention in these methods gives rise to more efficient reactions leading to higher yields of the desired product and the production of undesired reaction conditions and by-products. Exemplary of such reactions are a) nucleophilic substitution reactions of alkyl halides, tosylates, and triflates; b) nucleophilic substitution reactions of nitroaromatics, chloroaromatics, and aromatic triflates, and c) for the deprotection of silylated species. Again, however, it will be understood by those skilled in the art that the anhydrous salts of the invention may be utilized to good effect in any reaction or method where the use of the corresponding non-anhydrous salt is applicable. It will also be understood by those skilled in the art that the anhydrous salts of the invention may be employed in the form of the reaction mixture produced by the method of the invention or may be separated therefrom before use according to any conventional method for separating organic salts from their reaction products, such as, e.g., use of ion exchange resins, chiral chemistry and the like. [0032] Reactions employing TBAF generated in situ in accordance with the method of the invention are summarized in Table 2. For nucleophilic fluorination, anhydrous TBAF is comparable to, or exceeds the reactivity of other nucleophilic fluorinating agents. In head-to-head comparisons, TBAF exhibits dramatically enhanced rates of fluorination compared to dynamic vacuum dried “anhydrous” TBAF, CoCp 2 F, or TBAT. Neither heating nor a gross excess of TBAF is generally required to effect substitution (Table 2). TABLE 2 Fluorination of various substrates using anhydrous TBAF Yield* Run Substrate Reagent Solvent Conditions Product (%) Comments Ref. 1 PhCH 2 Br 1.3˜1.5 eq. CD 3 CN −35° C., <5 PhCH 3 F 100 This TBAF min work 2 PhCH 2 Br 2 eq. TBAF THF RT, 8 h PhCH 3 F >90 PhCH 2 ClH “anhydrous” (5%) 3 CH 3 I 1.5 eq. TBAF CD 3 CN −40° C., <5 CH 3 F 100 This min work 4 CH 3 I CoCp 2 F THF RT, 6 h CH 3 F 100 5 CH 3 (CH 2 ) 2 Br TBAF THF RT, <5 min CH 3 (CH 2 ) 3 F 40-50 (remainder This alkene) work 6 CH 3 (CH 2 ) 2 Br 6 eq. TBAT CD 3 CN Reflux, 24 h CH 3 (CH 2 ) 3 F 85 7 CH 3 (CH 2 ) 2 Br 2 eq. TBAF THF RT, 1 h CH 3 (CH 2 ) 3 F 48 40% octanol “anhydrous” 8 TBAF THF RT, <5 min CH 3 (CH 2 ) 13 F 100 This work 9 4 eq. TBAF THF, or CD 3 CN RT, <5 min >90 This work 10 1.3 eq. TBAF CD 3 CN RT, <2 min >95 This work 11 PhCOCl 1 eq. TBAF THF RT, <2 min PhCOF 100 This work 12 Tosyl-Cl 1 eq. TBAF THF RT, <2 min Tosyl-F 100 This work *yields were calculated by integration of starting material and product signals in the 1 H and/or 13 F NMR spectra. [0033] Taken together, the results presented here show that exceptionally nucleophilic, highly soluble fluoride ion sources featuring ammonium cations can be prepared readily even if the cations are thought susceptible to E2 elimination. The self dehydrating nature of the nucleophilic aromatic substitution method makes it an exceptionally forgiving synthetic route to anhydrous fluoride salts. [0034] Generally, the method of the invention produces anhydrous organic fluoride salts and reagents containing less than 0.01% H 2 O in one efficient step, in high yields and low temperatures without deleterious effects on the product or reaction mechanism. Moreover, the reactivity of the anhydrous fluoride salts of the invention in solution or liquid approaches that of conventional fluoride salts in the gas phase, e.g., a reaction between nitrobenzene and conventionally produced organic fluoride salt in solution will not proceed but will in gas phase. The anhydrous fluoride salts of the invention will react with nitrobenzene in solution. EXAMPLES [0035] All reagents were handled under N 2 . Hexafluorobenzene (C 6 F 6 ) (99%, SynQuest) was passed through a column of activated (130° C. for 5 h) silica gel and distilled from CaH 2 . Acetonitrile (HPLC grade, Aldrich) was distilled from P 2 O 5 and redistilled under reduced pressure from CaH 2 . THF (anhydrous, Aldrich) was distilled from LiAlH 4 . Purified solvents were stored under N 2 in Schlenk-style flasks under N 2 . Tetra-n-butylammonium cyanide (TBACN) (97%) was obtained from Fluka Chemical Co. TBACN was dried under vacuum at 40° C. overnight prior to use. For initial work, TBACN was recrystallized from THF/Hexane by layering, subsequent studies showed that this purification step was unnecessary. Tetramethylammonium hexafluorophosphate (TMAPF 6 ) was obtained from Fluka and dried under vacuum. All other reagents were of analytical grade, from Aldrich. All chemical handling was performed under N 2 in a glove box. [0036] 1 H, 13 C and 19 F NMR spectra were determined in the Instrumentation Center at the University of Nebraska-Lincoln. 400 MHz (QNP probe for 1 H, 13 C and 19 F NMR spectra), 500 MHz (QNP probe for 1 H, 13 C and 19 F NMR spectra) and 600 MHz (HF probe for 1 H and 19 F NMR spectra) NMR spectrometers were used in this study. 19 F NMR chemical shifts were referenced to an internal standard, hexafluorobenzene [0037] Syntheses of TBAF [0038] Anhydrous tetrabutylammonium fluoride (TBAF): 0.67 g TBACN was dissolved in 2.5 ml THF and the resulting solution was cooled to −65° C. A chilled solution (−65° C.) of 0.3 ml hexafluorobenzene (C 6 F 6 ) in 0.5 ml THF was added, and the mixture was allowed to warm gradually (over 4 hours) to −15° C. During this time the solution changed from colorless to yellow-green, and a white solid precipitated. The mixture was again cooled to −65° C., the solid was filtered and washed two times with cold THF. All isolation procedures were kept below −36° C. The white or light yellow TBAF solid was collected and put into a −36° C. freezer for short term storage. Total TBAF yield was over 95% (based upon TBACN, confirmed by quenching experiments with benzyl chloride) if the mixture was used directly. Isolated yields of the solid material varied from 40% to 70% depending on the rapidity of the wash and filtration steps. 1 H NMR ((CD 3 ) 2 SO) 3.23 (8H, m), 1.56 (8H, m), 1.28 (8H, sext, J=7.31 Hz), 0.86 (12H, t, J=7.31 Hz); 19 F NMR ((CD 3 ) 2 SO) −72.6 ppm (s); 13 C NMR ((CD 3 ) 2 SO): 57.5, 23.1, 19.2, 13.5 ppm. [0039] Generation of TBAF in CH 3 CN: TBACN (0.134 g, 0.5 mmol) was dissolved in anhydrous acetonitrile (0.5 ml). At 25° C., 9.6 μl (0.083 mmol) C 6 F 6 was added, and the initially colorless solution changed to dark-red immediately. The reaction was monitored by 19 F NMR spectroscopy. Fluoride generation was complete within 1 h. A representative 19 F NMR spectrum is shown in FIG. 1 . [0040] Generation of TBAF in DMSO: A very similar procedure was used to generate TBAF in DMSO. TBACN (0.134 g, 0.5 mmol) was dissolved in anhydrous acetonitrile (0.5 ml). At 25° C., 9.6 μl (0.083 mmol) C 6 F 6 was added, and the mixture was allowed to stand for one h. The solubility of TBAF in both CH 3 CN and DMSO was excellent (up to 2 M). The solution was directly used in the fluorination reaction. [0041] TMACN—TMACN was prepared by metathetical ion-exchange of TBACN with TMAPF 6 in acetonitrile/THF. 110 mg (0.5 mmol) TMAPF 6 was dissolved in a minimum amount of acetonitrile, and a saturated acetonitrile solution of TBACN (134 mg, 0.5 mmol) was added. The precipitated TMACN was filtered, washed with a small amount of acetonitrile, and the residual solvents were evaporated. 1 H NMR (CD 3 CN) 3.11 ppm (s), 13 C NMR (CD 3 CN) 54.27, 167.20. [0042] TMAF—TMAF was synthesized from TMACN and C 6 F 6 in acetonitrile by a method similar to that described for TBAF. 4.6 mg TMACN dissolve in 0.6 ml of (CD 3 ) 2 SO at room temperature. 1.0 μl hexafluorobenzene (C 6 F 6 ) was and the mixture was allowed to stand at room temperature for 12 h. [0000] General Procedure for Fluorination Reactions [0043] The general procedure given below was used for all fluorination reactions employing in situ generated TBAF. Yields were calculated by integration of the relevant peaks in the 1 H and 19 F NMR spectra. [0044] In an NMR tube equipped with a PTFE resealable closure, TBACN (0.134 g, 0.5 mmol) was dissolved in anhydrous CD 3 CN (or (CD 3 ) 2 SO) (0.5 ml). At 25° C., 9.6 μl (0.083 mmol) C 6 F 6 was added, and the mixture was held at room temperature for 1 h. The mixture was cooled to −40° C. and the substrate (0.25-0.5 mmol) was added. The solution was mixed vigorously and the tube was transferred to a precooled (−35° C.) NMR probe and spectra were gathered. The time elapsed from the sample mixing until completion of the first NMR spectrum was approximately 3 min. The reaction was monitored by 19 F NMR spectra every 2 minutes until no further change was observed. [0045] Table 3 shows results of fluorination of various substrates under different conditions. For comparison, the literature results by other fluorination regents are listed in table 3. TABLE 3 Temp and Yield Run Substrate Reagent Solvent Time Product (%) Comments Ref. 1 PhCH 2 Br 1.3˜1.5 eq. acetonitrile −35° C., <5 PhCH 2 F 100 No This TBAF min PhCH 2 OH work 2 PhCH 2 Br DMSO RT, <2 PhCH 2 F 100 This min work 3 PhCH 2 Br THF RT, <2 PhCH 2 F 100 This min work 4 PhCH 2 Br 2 eq. TBAF THF RT, 8 PhCH 2 F >90 PhCH 2 OH 1 “anhydrous” hours (5%) 5 PhCH 2 Cl 1.5 eq. THF RT, <2 PhCH 2 F 100 This TBAF min work 6 PhCH 2 Cl 2 eq. TBAF THF 40° C., 12 PhCH 2 F 1 “anhydrous” hours 7 PhCH 2 Cl CoCp 2 F THF RT, 90 PhCH 2 F 95 2 min 8 CH 3 I 1.5 eq. TBAF acetonitrile −40° C., <5 CH 3 F 100 This min work 9 CH 3 I CoCp 2 F THF RT, 6 CH 3 F 100 2 hours 10 CH 3 (CH 2 ) 7 Br TBAF THF RT, <5 CH 3 (CH 2 ) 7 F 40˜50 No octanol This min work 11 CH 3 (CH 2 ) 7 Br 6 eq. TBAT acetonitrile Reflux, 24 h CH 3 (CH 2 ) 7 F 85 3 12 CH 3 (CH 2 ) 7 Br 2 eq. TBAF THF RT, 1 hour CH 3 (CH 2 ) 7 F 48 40% octanol 1 “anhydrous” 13 CH 3 (CH 2 ) 17 (p-Cl- TBAF THF RT, <5 CH 3 (CH 2 ) 7 F 100 This benzenesulfonate) min work 14 CH 3 (CH 2 ) 7 OTs 2 eq. TBAF none RT, 1 hour CH 3 (CH 2 ) 7 F 98 2% alkene 1 “anhydrous” 15 CH 3 (CH 2 ) 7 OTs 4 eq. TBAT acetonitrile Reflux, 24 h CH 3 (CH 2 ) 7 F 99 Trace alkene 3 16 2 eq. TBAF THF, or acetonitrile RT, <5 min 100 This work 17 1.3 eq TBAF DMSO, or acetonitrile RT, <8 hours >90 This work 18 1.3 eq TBAF acetonitrile RT, <2 min ˜95 This work 19 PhCOCl 1 eq. TBAF THF RT or PhCOF 100 This below RT, work <2 min 20 PhCOCl 2 eq. TBAF RT, 1 hour PhCOF 81* 1 “anhydrous” 21 Tosyl-Cl 1 eq. TBAF THF RT, <2 Tosyl-F 100 This min work 22 2.5 eq. TBAF, 3 h; followed by add H 2 O DMSO or acetonitrile RT, ˜3 hours This work 23 TBABF—KHF 2 none 120° C., 2 hours 86 Contains 10% PhCHFCH 2 OH 4 NMR Spectra: [0046] Generation of TBAF— FIG. 1 : 19 F NMR spectra recorded over the course of 40 minutes following the mixing of 134 mg TBACN and 9.6 μl C 6 F 6 in CD 3 CN. The peak at =−72 ppm is due to fluoride ion; the peak at □=−164 ppm peak is the C 6 F 6 ; the small peak at =−147 ppm (d, J HF =148 Hz) is due to HF 2 − (The signal marked with * at −151 ppm is an artifact). [0047] Debromofluorination of an aromatic compound— FIG. 2 : Conversion of 3,5-bis(trifluoromethyl)bromobenzene to 3,5-bis(trifluoromethyl)fluorobenzene by TBAF in (CD 3 ) 2 SO. a: 19 F NMR spectrum before the addition of 3,5-bis(trifluoromethyl)bromobenzene; b-e: 19 F NMR spectrum after the addition of 3,5-bis(trifluoromethyl)bromobenzene. The total elapsed time was 8 h. Chemical shift assignments: =−74 ppm (F − ), =−64 ppm (CF 3 ), =−108 ppm (Ar—F). [0048] Removal of protic solvent by hexacyanobenzene— FIG. 3 : 19 F NMR spectra showing the effect of adding 0.08 eq. benzyl alcohol to a solution of in-situ generated TBAF (CD 3 ) 2 SO. a: Spectrum recorded before the addition of benzyl alcohol; b: 5 min after addition of benzyl alcohol; c: 1 h after addition; d: 4 h after addition; e: 20 h after addition. For spectra b and c the bottom spectrum is presented with the normal Y-scale, the top spectrum has the Y-scale multiplied by 8. [0049] Impact of protic solvent in the absence of hexacyanobenzene— FIG. 4 : 19 F NMR spectra showing the effect of adding 0.08 eq. benzyl alcohol to a solution of purified TBAF (CD 3 ) 2 SO. a: Spectrum recorded before the addition of benzyl alcohol; b: 10 min after addition of benzyl alcohol; c: 1 h after addition; d: 7 h after addition; e: 20 h after addition. For spectra b and c the bottom spectrum is presented with the normal Y-scale, the top spectrum has the Y-scale multiplied by 64. [0050] Reaction of in-situ generated TBAF with water— FIG. 5 : 19 F NMR spectra of the reaction of in situ generated TBAF with 0.083 eq. water in (CD 3 ) 2 SO. a, before addition of water; b˜h, after addition of water. [0051] Detail of FIG. 5 — FIG. 6 : 19 F NMR spectra (expanded area from FIG. S- 5 ) of the reaction of in-situ generated TBAF with 0.083 eq water in DMSO-d6. a, before addition of water; b˜h, after addition of water. [0052] Reaction of in-situ generated TBAF with water— FIG. 7 : 1 H NMR spectra of the reaction of in-situ generated TBAF with 0.083 eq water in (CD 3 ) 2 SO. a, before addition of water; b˜f, after addition of water. The signal at 5.6 ppm is assigned to H 2 O. [0053] Reaction of isolated TBAF with water— FIG. 8 : 19 F NMR spectra of the reaction of isolated TBAF with 0.083 eq water in (CD 3 ) 2 SO. a, before addition of water; b˜g, after addition of water. [0054] Detail of FIG. 8 — FIG. 9 : 19 F NMR spectra of the reaction of isolated TBAF with 0.083 eq water in (CD 3 ) 2 SO. (Detail from FIG. S- 8 .) [0055] Reaction of isolated TBAF with water— FIG. 10 : 19 F NMR spectra of the reaction of isolated TBAF with 0.083 eq water in (CD 3 ) 2 SO. a, before addition of water; b˜e, after addition of water. The signal at 5.6 ppm is assigned to H 2 O; the signal at 5.8 ppm is assigned to HOD.

Anhydrous organic fluoride salts and reagents prepared by a method comprising the nucleophilic substitution of a fluorinated aromatic or fluorinated unsaturated organic compound with a salt having the formula: [Q n M] x+ A x − in an inert polar, aprotic solvent; wherein M is an atom capable of supporting a formal positive charge, the n groups Q are independently varied organic moieties, n is an integer such that the [Q n M] carries at least one formal positive charge, x is an integer defining the number of formal positive charge(s), +, carried by the [Q n M], A − is an anionic nucleophile capable of substituting for F in the fluorinated compound and F represents fluorine or a radioisotope thereof.

FIELD OF THE INVENTION This invention generally relates to electronic commerce software applications and, more particularly, to a method and system relating to commodities purchasing over a network of distributed computing devices. BACKGROUND OF THE INVENTION Commodity items such as lumber, agricultural products, metals, and livestock/meat are usually traded in the open market between a number of buyers and sellers. The sales transactions of most commodity items involve a number of parameters. For instance, in the trade of commodity lumber, a buyer usually orders materials by specifying parameters such as lumber species, grade, size (i.e. 2×4, 2×10, etc.) and length, as well as the “tally” or mix of units of various lengths within shipment, method of transportation (i.e., rail or truck), shipping terms (i.e., FOB or delivered), and desired date of receipt, with each parameter influencing the value of the commodity purchase. Given the multiple possible combinations of factors, a commodity buyer often finds it difficult to objectively compare similar but unequal offerings among competing vendors. For example, in a case where a lumber buyer desires to order a railcar load of spruce (SPF) 2×4's of #2 & Better grade, the buyer would query vendors offering matching species and grade carloads seeking the best match for the buyer's need or tally preference at the lowest market price. Lumber carloads are quoted at a price per thousand board feet for all material on the railcar. In a market where the shipping parameters are not identical, it is very difficult for buyers to determine the comparative value of unequal offerings. Typically a lumber buyer will find multiple vendors each having different offerings available. For example, a railcar of SPF 2×4's may be quoted at rate of $300/MBF (thousand board feet) by multiple vendors. Even though MBF price is equal, one vendor's carload may represent significantly greater marketplace value because it contains the more desirable lengths of 2×4's, such as builder preferred sixteen foot 2×4's. When the offering price varies in addition to the mix of lengths, it becomes increasingly difficult to compare quotes from various vendors. Further, because construction projects often require long lead times, the lumber product may need to be priced now, but not delivered until a time in the future. Alternately, another species of lumber (i.e., southern pine) may represent an acceptable substitute. Therefore, from the foregoing, there is a need for a method and system that allows buyers to evaluate the price of commodity offerings possessing varying shipping parameters. SUMMARY OF THE INVENTION The present invention provides a system and method for managing and evaluating commodities purchasing over a network of distributed computing devices. In one embodiment, buyers generate a request for quote and, in response to the request for quote, receive a quote from a plurality of sellers. A price normalization routine allows buyers to evaluate and compare a normalized price for commodity products having different evaluation parameters. In one example, a plurality of computers are connected to a network, including at least one server, at least one buyer client computer, and a plurality of seller client computers. A method for evaluating commodities pricing first provides a browsable display describing at least one commodities exchange service. At least one request for quote (RFQ) is received from a buyer. Responsive to the RFQ, the system then receives at least one quote from different sellers, where each quote may have a different price and quantity listed. The system normalizes the prices received from the different quotes by applying a metric factor to the quote and at least one comparison value is generated. A comparison value allows the buyer to readily compare the prices of a number of commodities having inherently different values to an objective measure. In addition, the system tracks all transactional activity and provides a cross compilation tool for evaluation and analysis. In regard to the latter, a method for evaluating commodities pricing comprises maintaining a database of commodities transactions. The database includes price data sets exchanged between buyer and seller agents. One or more price data sets exchanged between a particular buyer agent and a particular seller agent in a specified time period are retrieved from the database. In one embodiment, the specified time period may be a day, for example. The retrieved price data sets are summed to determine a summed price total. Additionally, metric data indicative of market prices for commodities indicated by the retrieved price data sets are received. The market prices for the commodities in the price data sets are summed to determine a summed market price total. The summed price total is then compared to the summed market price total to generate a comparison value. The method may further comprise generating the comparison value by calculating a ratio of the summed price total and the summed market price total. In that regard, the ratio may be calculated by dividing the summed price total by the summed market price total. If desired, the price data sets that are retrieved may be limited to price data sets exchanged in response to pricing inquiries that are sent at the same time. Moreover, multiple buyer agents and/or seller agents may be grouped such that the retrieved price data sets include price data sets of the group, which price data sets are summed to determine the summed price total. An output may be generated which reports the comparison value. In yet another embodiment, a database of commodities transactions includes price data sets exchanged between a plurality of buyer and seller agents for pricing commodities. A method for evaluating commodities pricing comprises retrieving from the database one or more price data sets in a specified time period. Commodities indicated by the retrieved price data sets meet a specified criterion. The retrieved price data sets are summed to determine a summed price total. Additionally, metric data indicative of market prices for the commodities indicated in the retrieved price data sets are received. The market prices for the commodities are summed to determine a summed market price total. The summed price total is then compared to the summed market price total to generate at least one comparison value. Again, the specified time period may be a day, for example. The comparison value may be generated by calculating a ratio of the summed price total and the summed market price total. In that regard, the ratio may be calculated by dividing the summed price total by the summed market price total. If desired, the retrieved price data sets may be limited to price data sets that resulted in a purchase of the commodities indicated by the price data sets. As noted above, price data sets are retrieved such that commodities indicated by the price data sets meet a specified criterion. For example, without limitation, the specified criterion may be a size of commodity in the price data sets, a species of commodity in the price data sets, and/or a grade of commodity in the price data sets. In some embodiments, commodities indicated by the retrieved price data sets meet two or more specified criteria. Again, the method may further comprise generating an output that reports the comparison value. BRIEF DESCRIPTION OF THE DRAWINGS The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: FIG. 1 is a block diagram of a prior art representative portion of the Internet. FIG. 2 is a pictorial diagram of a system of devices connected to the Internet, which depict the travel route of data in accordance with the present invention. FIG. 3 is a block diagram of the several components of the buyer's computer shown in FIG. 2 that is used to request information on a particular route in accordance with the present invention. FIG. 4 is a block diagram of the several components of an information server shown in FIG. 2 that is used to supply information on a particular route in accordance with the present invention. FIG. 5 is a flow diagram illustrating the logic of a routine used by the information server to receive and process the buyer's actions. FIGS. 6A-6B are flow diagrams illustrating another embodiment of the logic used by the information server to receive and process the quotes and quote requests of both buyers and vendors. FIG. 7 is a flow diagram illustrating another embodiment of the logic used by the information server to execute the process of a catalog purchase. FIGS. 8A-8D are images of windows produced by a Web browser application installed on a client computer accessing a server illustrating one embodiment of the present invention. FIG. 9 is a flow diagram illustrating one embodiment of the normalization process in accordance with the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The term “Internet” refers to the collection of networks and routers that use the Internet Protocol (IP) to communicate with one another. A representative section of the Internet 100 as known in the prior art is shown in FIG. 1 in which a plurality of local area networks (LANs) 120 and a wide area network (WAN) 110 are interconnected by routers 125 . The routers 125 are generally special purpose computers used to interface one LAN or WAN to another. Communication links within the LANs may be twisted wire pair, or coaxial cable, while communication links between networks may utilize 56 Kbps analog telephone lines, or 1 Mbps digital T-1 lines and/or 45 Mbps T-3 lines. Further computers and other related electronic devices can be remotely connected to either the LANs 120 or the WAN 110 via a modem and temporary telephone link. Such computers and electronic devices 130 are shown in FIG. 1 as connected to one of the LANs 120 via dotted lines. It will be appreciated that the Internet comprises a vast number of such interconnected networks, computers, and routers and that only a small, representative section of the Internet 100 is shown in FIG. 1 . The World Wide Web (WWW), on the other hand, is vast collection of interconnected, electronically stored information located on servers connected throughout the Internet 100 . Many companies are now providing services and access to their content over the Internet 100 using the WWW. In accordance with the present invention and as shown in FIG. 2 , there may be a plurality of buyers operating a plurality of client computing devices 235 . FIG. 2 generally shows a system 200 of computers and devices to which an information server 230 is connected and to which the buyers' computers 235 are also connected. Also connected to the Internet 100 , is a plurality of computing devices 250 associated with a plurality of sellers. The system 200 also includes a communications program, referred to as CEA, which is used on seller's computing devices 250 to create a communication means between the seller's backend office software and the server application. The buyers of a market commodity may, through their computers 235 , request information about a plurality of items or order over the Internet 100 via a Web browser installed on the buyers' computers. Responsive to such requests, the information server 230 , also referred to as a server 230 , may combine the first buyer's information with information from other buyers on other computing devices 235 . The server 230 then transmits the combined buyer data to the respective computing devices 250 associated with the plurality of buyers. Details of this process are described in more detail below in association with FIGS. 5-7 . Those of ordinary skill in the art will appreciate that in other embodiments of the present invention, the capabilities of the server 230 and/or the client computing devices 235 and 250 may all be embodied in the other configurations. Consequently, it would be appreciated that in these embodiments, the server 230 could be located on any computing device associated with the buyer or seller's computing devices. Additionally, those of ordinary skill in the art will recognize that while only four buyer computing devices 235 , four seller computing devices 250 , and one server 230 are depicted in FIG. 2 , numerous configurations involving a vast number of buyer and seller computing devices and a plurality of servers 230 , equipped with the hardware and software components described below, may be connected to the Internet 100 . FIG. 3 depicts several of the key components of the buyer's client computing device 235 . As known in the art, client computing devices 235 are also referred to as “clients” or “devices,” and client computing devices 235 also include other devices such as palm computing devices, cellular telephones, or other like forms of electronics. A client computing device can also be the same computing device as the server 230 . An “agent” can be a person, server, or a client computing device 235 having software configured to assist the buyer in making purchasing decisions based on one or more buyer determined parameters. Those of ordinary skill in the art will appreciate that the buyers' computer 235 in actual practice will include many more components than those shown in FIG. 3 . However, it is not necessary that all of these generally conventional components be shown in order to disclose an illustrative embodiment for practicing the present invention. As shown in FIG. 3 , the buyer's computer includes a network interface 315 for connecting to the Internet 100 . Those of ordinary skill in the art will appreciate that the network interface 315 includes the necessary circuitry for such a connection, and is also constructed for use with the TCP/IP protocol. The buyers' computer 235 also includes a processing unit 305 , a display 310 , and a memory 300 all interconnected along with the network interface 315 via a bus 360 . The memory 300 generally comprises a random access memory (RAM), a read-only memory (ROM) and a permanent mass storage device, such as a disk drive. The memory 300 stores the program code necessary for requesting and/or depicting a desired route over the Internet 100 in accordance with the present invention. More specifically, the memory 300 stores a Web browser 330 , such as Netscape's NAVIGATOR or Microsoft's INTERNET EXPLORER browsers, used in accordance with the present invention for depicting a desired route over the Internet 100 . In addition, memory 300 also stores an operating system 320 and a communications application 325 . It will be appreciated that these software components may be stored on a computer-readable medium and loaded into memory 300 of the buyers' computer 235 using a drive mechanism associated with the computer-readable medium, such as a floppy, tape or CD-ROM drive. As will be described in more detail below, the user interface which allows products to be ordered by the buyers are supplied by a remote server, i.e., the information server 230 located elsewhere on the Internet as illustrated in FIG. 2 . FIG. 4 depicts several of the key components of the information server 230 . Those of ordinary skill in the art will appreciate that the information server 230 includes many more components than shown in FIG. 4 . However, it is not necessary that all of these generally conventional components be shown in order to disclose an illustrative embodiment for practicing the present invention. As shown in FIG. 4 , the information server 230 is connected to the Internet 100 via a network interface 410 . Those of ordinary skill in the art will appreciate that the network interface 410 includes the necessary circuitry for connecting the information server 230 to the Internet 100 , and is constructed for use with the TCP/IP protocol. The information server 230 also includes a processing unit 415 , a display 440 , and a mass memory 450 all interconnected along with the network interface 410 via a bus 460 . The mass memory 450 generally comprises a random access memory (RAM), read-only memory (ROM), and a permanent mass storage device, such as a hard disk drive, tape drive, optical drive, floppy disk drive, or combination thereof. The mass memory 450 stores the program code and data necessary for incident and route analysis as well as supplying the results of that analysis to consumers in accordance with the present invention. More specifically, the mass memory 450 stores a metrics application 425 formed in accordance with the present invention for managing the purchase forums of commodities products. In addition, mass memory 450 stores a database 445 of buyer information continuously logged by the information server 230 for statistical market analysis. It will be appreciated by those of ordinary skill in the art that the database 445 of product and buyer information may also be stored on other servers or storage devices connected to the either the information server 230 or the Internet 100 . Finally, mass memory 450 stores Web server software 430 for handling requests for stored information received via the Internet 100 and the WWW, and an operating system 420 . It will be appreciated that the aforementioned software components may be stored on a computer-readable medium and loaded into mass memory 450 of the information server 230 using a drive mechanism associated with the computer-readable medium, such as floppy, tape or CD-ROM drive. In addition, the data stored in the mass memory 450 and other memory can be “exposed” to other computers or persons for purposes of communicating data. Thus, “exposing” data from a computing device could mean transmitting data to another device or person, transferring XML data packets, transferring data within the same computer, or other like forms of data communications. In accordance with one embodiment of the present invention, FIG. 5 is a flow chart illustrating the logic implemented for the creation of a Request for Quote (RFQ) by a singular buyer or a pool of buyers. In process of FIG. 5 , also referred to as the pooling process 500 , a buyer or a pool of buyers generate an RFQ which is displayed or transmitted to a plurality of sellers. Responsive to receiving the RFQ, the sellers then send quotes to the buyers. In summary, the creation of the RFQ consists of at least one buyer initially entering general user identification information to initiate the process. The buyer would then define a Line Item on a Web page displaying an RFQ form. The Line Item is defined per industry specification and units of product are grouped as a “tally” per industry practice. The pooling process 500 allows buyers to combine RFQ Line Items with other buyers with like needs. In one embodiment, the pool buy feature is created by a graphical user interface where the RFQ Line Items from a plurality of buyers is displayed on a Web page to one of the pool buyers, referred to as the pool administrator. The server 230 also provides a Web-based feature allowing the pool administrator to selectively add each RFQ Line Item to one combined RFQ. The combined RFQ is then sent to at least one vendor or seller. This feature provides a forum for pooling the orders of many buyers, which allows individual entities or divisions of larger companies to advantageously bid for larger orders, thus providing them with more bidding power and the possibility of gaining a lower price. The pooling process 500 begins in a step 501 where a buyer initiates the process by providing buyer purchase data. In step 501 , the buyer accesses a Web page transmitted from the server 230 configured to receive the buyer purchase data, also referred to as the product specification data set or the Line Item data. One exemplary Web page for the logic of step 501 is depicted in FIG. 8A . As shown in FIG. 8A , the buyer enters the Line Item data specifications in the fields of the Web page. The Line Item data consists of lumber species and grade 803 , number of pieces per unit 804 , quantities of the various units comprising the preferred assortment in the tally 805 A-E, delivery method 806 , delivery date 807 , delivery location 808 , and the overall quantity 809 . In one embodiment, the buyer must define the delivery date as either contemporaneous “on-or-before” delivery date, or specify a delivery date in the future for a “Forward Price” RFQ. In addition, the buyer selects a metric or multiple metrics in a field 810 per RFQ Line Item (tally). As described in more detail below, the metric provides pricing data that is used as a reference point for the buyer to compare the various quotes returned from the sellers. The buyer RFQ Line Item data is then stored in the memory of the server 230 . Returning to FIG. 5 , at a next step 503 , the server 230 determines if the buyer is going to participate in a pool buy. In the process of decision block 503 , the server 230 provides an option in a Web page that allows the buyer to post their Line Item data to a vendor or post their Line Item data to a buyer pool. The window illustrated in FIG. 8A is one exemplary Web page illustrating these options for a buyer. As shown in FIG. 8A , the links “Post Buyer Pool” 812 and “Post to Vendors” 814 are provided on the RFQ Web page. At a step 503 , if the buyer does not elect to participate in a pool buy, the process continues to a step 513 where the server 230 generates a request for a quote (RFQ) from the buyer's Line Item data. A detailed description of how the server 230 generates a request for a quote (RFQ) is summarized below and referred to as the purchase order process 600 A depicted in FIG. 6A . Alternatively at the decision block 503 , if the buyer elects to participate in a pool buy, the process continues to a step 505 where the system notifies other buyers logged into the server 230 that an RFQ is available in a pool, allowing other buyers to add additional Line Items (tallies) to the RFQ. In this part of the process, the Line Items from each buyer are received by and stored in the server memory. The Line Items provided by each buyer in the pool are received by the server 230 using the same process as described above with reference to block 501 and the Web page of FIG. 8A . All of the Line Items stored on the server 230 are then displayed to a pool administrator via a Web page or an email message. In one embodiment, the pool administrator is one of the buyers in a pool, where the pool administrator has the capability to select all of the Line Item data to generate a combined RFQ. The server 230 provides the pool administrator with this capability by the use of any Web-based communicative device, such as email or HTML forms. As part of the process, as shown in steps 507 and 509 , the pool may be left open for a predetermined period of time to allow additional buyers to add purchase data to the current RFQ. At a decision block 509 , the server 230 determines if the pool administrator has closed the pool. The logic of this step 509 is executed when the server 230 receives the combined RFQ data from the pool administrator. The pool administrator can send the combined RFQ data to the server 230 via an HTML form or by other electronic messaging means such as email or URL strings. Once the server 230 has determined that the pool is closed, the process continues to block 510 where the Line Items from each buyer (the combined RFQ) is sent to all of the buyers in the pool. The process then continues to the step 513 where the server 230 sends the combined RFQ to the vendors or sellers. Referring now to FIG. 6A , one embodiment of the purchase-negotiation process 600 is disclosed. The purchase-negotiation process 600 is also referred to as an solicited offer process or the market purchase process. In summary, the purchase-negotiation process 600 allows at least one buyer to submit an RFQ and then view quotes from a plurality of vendors and purchase items from selected vendor(s). The logic of FIG. 6A provides buyers with a forum that automatically manages, collects and normalizes the price of desired commodity items. The purchase-negotiation process 600 calculates a normalized price data set that is based on a predefined metric(s). The calculation of the normalized price data set in combination with the format of the Web pages described herein create an integrated forum where quotes for a plurality of inherently dissimilar products can be easily obtained and compared. The purchase-negotiation process 600 begins at a step 601 where the RFQ, as generated by one buyer or a pool of buyers in the process depicted in FIG. 5 , is sent to a plurality of computing devices 250 associated with a plurality of sellers or vendors. The vendors receive the RFQ via a web page transmitted by the server 230 . In one embodiment, the vendors receive an email message having a hypertext link to the RFQ Web page to provide notice the vendor. Responsive to the information in the buyers' RFQ, the process then continues to a step 603 where at least one vendor sends their quote information to the server 230 . In the process of step 603 , the vendors respond to the RFQ by sending their price quote to the server 230 for display via a Web page to the buyer or buyer pool. Generally described, the vendors send an HTML form or an email message with a price and description of the order. The description of the order in the quote message contains the same order information as the RFQ. FIG. 8B illustrates one exemplary Web page of a vendor quote that is displayed to the buyer. As shown in FIG. 8B , the vendor quote includes the vendor's price 813 , the lumber species and grade 803 , number of pieces per unit 804 , quantities of the various units comprising the preferred assortment in the tally 805 A-E, delivery method 806 , delivery date 807 , and delivery location 808 . In the quote response message, the vendor has the capability to modify any of the information that was submitted in the RFQ. For example, the vendor may edit the quantity values for the various units comprising the preferred assortment in the tally 805 A-E. This allows the vendor to adjust the buyer's request according to the vendor's inventory, best means of transportation, etc. All of the vendor's quote information is referred to as price data set or the RFQ Line Item (tally) quote. Returning to FIG. 6A , the process continues to a step 605 , where the server 230 normalizes the price of each RFQ Line Item (tally) quote from each vendor. The normalization of the vendor's price is a computation that adjusts the vendor's price utilizing data from a metric. The normalization process is carried out because each vendor may respond to the Line Items of an RFQ by quoting products that are different from buyer's RFQ and/or have a different tally configuration. The normalization of the pricing allows the buyers to objectively compare the relative value of the different products offered by the plurality of vendors. For example, one vendor may produce a quote for an RFQ of: one unit of 2×4×12, two units of 2×4×12, and three units of 2×4×16. At the same time, another vendor may submit a quote for three units of 2×4×12, one unit of 2×4×12, and two units of 2×4×16. Even though there is some difference between these two offerings, the price normalization process provides a means for the buyer to effectively compare and evaluate the different quotes even though there are variations in the products. The price normalization process 900 is described in more detail below in conjunction with the flow diagram of FIG. 9 . Returning again to FIG. 6A , at a step 607 the vendor's quote information is communicated to the buyer's computer for display. As shown in FIG. 8B and described in detail above, the vendor's quote is displayed via a Web page that communicates the vendor's quote price 813 and other purchase information. In addition, the vendor's quote page contains a metric price 815 and a quote price vs. metric price ratio 816 . The metric price 815 and the quote price vs. metric price ratio 816 are also referred to as a normalized price data value. Next, at a step 609 , the buyer or the administrator of the buyer pool, compares the various products and prices quoted by the vendors along with the normalized price for each Line Item on the RFQ. In this part of the process, the buyer may decide to purchase one of the products from a particular vendor and sends a notification to the selected vendor indicating the same. The buyer notifies the selected vendor by the use of an electronic means via the server 230 , such as an HTML form, a chat window, email, etc. For example, the quote Web page depicted in FIG. 8B shows two different quotes with two different tallies, the first quote price 813 of $360, and the second quote price 813 A of $320. If the buyer determines that they prefer to purchase the materials listed in the first quote, the buyer selects the “Buy!” hyperlink 820 or 820 A associated with the desired tally. If the buyer is not satisfied with any of the listed vendor quotes, the server 230 allows the buyer to further negotiate with one or more of the vendors to obtain a new quote. This step is shown in decision block 611 , where the buyer makes the determination to either accept a quoted price or proceed to a step 613 where they negotiate with the vendor to obtain another quote or present a counter offer. Here, the server 230 provides a graphical user interface configured to allow the buyer and one vendor to electronically communicate, such as a chat window, streaming voice communications or other standard methods of communication. There are many forms of electronic communications known in the art that can be used to allow the buyer and vendors to communicate. The buyer and seller negotiate various quotes and iterate through several steps 603 - 613 directed by the server 230 , where each quote is normalized, compared and further negotiated until quote is accepted by the buyer or negotiations cease. While the buyer and seller negotiate the various quotes, the server 230 stores each quote until the two parties agree on a price. At any step during the negotiation process, the system always presents the buyer with an option to terminate the negotiation if dissatisfied with the quote(s). At decision block 611 , when a buyer agrees on a quoted price, the process then continues to a step 615 where the buyer sends a notification message to the vendor indicating they have accepted a quote. As described above with reference to steps 603 - 613 , the buyer notification message of step 615 may be in the form of a message on a chat window, email, by an HTML form, or the like. However, the buyer notification must be transmitted in a format that allows the system to record the transaction. The buyer notification may include all of the information regarding the specifications by RFQ Line Item, such as, but not limited to, the buy price, date and method of shipment, and payment terms. The purchase-negotiation process 600 is then finalized when the system, as shown in a step 617 , sends a confirmation message to a tracking system. The confirmation message includes all of the information related to the agreed sales transaction. Optionally, the process includes a step 619 , where the server 230 stores all of the information related to RFQ, offers, and the final sales transaction in a historical database. This would allow the server 230 to use all of the transaction information in an analysis process for providing an improved method of obtaining a lower market price in future transactions and in identifying optimum purchasing strategy. The analysis process is described in further detail below. Although the illustrated embodiment is configured to store the data related to the sales transactions, the system can also be configured to store all of the iterative quote information exchanged between the buyer and vendor. Referring now to FIG. 6B , an embodiment of the unsolicited offer process 650 is disclosed. In summary, the unsolicited offer process 650 , also referred to as the unsolicited market purchase process, allows at least one buyer to view unsolicited offers from a plurality of vendors and purchase items from a plurality of vendors from the offers. The logic of FIG. 6B provides buyers with a forum that automatically manages, collects and normalizes price quotes based on metric data. By the price normalization method of FIG. 6B , the server 230 creates an integrated forum where offers from a plurality of inherently dissimilar products can be obtained and normalized for determination of purchase. The unsolicited offer process 650 begins at a step 651 where the plurality of vendors are able to submit offers to the server 230 . This part of the process is executed in manner similar to step 603 of FIG. 6A , where the vendor submits a quote to the server 230 . However, in the Web page of step 651 , the server 230 generates a Web page containing several tallies from many different vendors. In addition, at step 651 , the server 230 stores all of the unsolicited offer data provided by the vendors. Next, at a step 653 , a buyer views the offers stored on the server 230 . This part of the process is carried out in a manner similar to the process of step 603 or 607 where the server 230 displays a plurality of offers similar to the tallies depicted in FIG. 8A . Next, at a step 655 , the buyer selects a metric for the calculation of the normalized price associated with the selected offer. As described in more detail below, metrics may come from publicly available information, i.e., price of futures contracts traded on the Chicago Mercantile Exchange, subscription services such as Crowes™ or Random Lengths™ accessed via the metric server adapter 435 (shown in FIG. 4 ), or internally generated metrics derived from the data stored in the server 230 . The normalization calculation, otherwise referred to as the normalization process, occurs each time the buyer views a different offer, and the normalization calculation uses the most current metric data for each calculation. The normalization process is carried out because each vendor will most likely offer products that may vary from products of other vendors, and have a different tally configuration from those supplied by other vendors. The normalization of the pricing allows the buyers to compare the relative value of the different products offered by the number of vendors. The metric price for each selected offer is displayed in a similar manner as the metric price 815 and 816 shown in the Web page of FIG. 8B . Next, at decision block 657 , the buyer selects at least one offer for purchase. This is similar to the process of FIG. 6A in that the buyer selects the “Buy!” hyperlink 820 associated with the desired tally to purchase an order. The process then continues to steps 659 - 663 , where at step 659 the process transmits a buy notice to the vendor, then at step 661 sends a purchase confirmation to the tracking system, and then at step 663 saves the transaction data in the server database. The steps 659 - 663 are carried out in the same manner as the steps 615 - 619 of FIG. 6A . In the above-described process, the buyer notification may include all of the information regarding the specifications by RFQ Line Item, and data such as, but not limited to, the buy price, date and method of shipment, and the payment terms. Referring now to FIG. 7 , a flow diagram illustrating yet another embodiment of the present invention is shown. FIG. 7 illustrates the catalog purchase process 700 . This embodiment allows buyers to search for a catalog price of desired commerce items; enter their purchase data based on the pre-negotiated catalog prices, and to compare those catalog prices with a selected metric price and the current market price, wherein the current market price is determined by the purchase-negotiation process 600 . The process starts at a step 701 where the buyer selects a program buy catalog 443 . The program buy catalog 443 provides buyers with the published or pre-negotiated price of the desired products. Next, at a step 703 , based on the catalog information, the buyer then enters their purchase data. Similar to the step 501 of FIG. 5 and the tally shown in FIG. 8A , the buyer sends purchase data to the server 230 , such as the desired quantity of each item and the lumber species, grade, etc. The process then proceeds to decision block 707 where the buyer makes a determination of whether to purchase the items using the catalog price, or purchase the desired product in the open market. Here, the server 230 allows the user to make this determination by displaying the metric price of each catalog price. This format is similar to the metric price 815 and 816 displayed in FIG. 8B . At decision block 707 , if the buyer determines that the catalog price is better than a selected metric price, the process then proceeds to steps 709 , 711 , and 713 , where a program buy from the catalog is executed, and the buyer's purchase information is stored on the server 230 and sent to the vendor's system to confirm the sale. These steps 711 - 713 are carried out in the same manner as the confirmation and save steps 617 and 619 as shown in FIG. 6A . At decision block 707 , if the buyer determines that the metric price is better than the catalog price, the process continues to a step 717 where the buyers purchase data is entered into an RFQ. At this step, the process carries out the first five steps 601 - 609 of the method of FIG. 6A to provide buyers with the price data from the open market, as well as provide the normalized prices for each open market quote. At a step 719 , the server 230 then displays a web page that allows the user to select from a purchase option of a catalog or spot (market) purchase. At decision block 721 , based on the displayed information, the buyer will then have an opportunity to make a determination of whether they will proceed with a catalog purchase or an open market purchase. At decision block 721 , if the buyer proceeds with the catalog purchase, the process continues to step 709 where the catalog purchase is executed. The steps 709 - 713 used to carry out the catalog purchase are the same as if the buyer had selected the catalog purchase in step 707 . However, if at decision block 721 the buyer selects the option to proceed with the market purchase, the process continues to a step 723 where the RFQ generated in step 717 is sent to the vendor. Here, the process carries out the steps of FIG. 6 to complete the open market purchase. More specifically, the process continues to step 609 where the buyer compares the normalized prices from each vendor. Once a vendor is selected, the negotiation process of steps 603 - 613 is carried out until the buyer decides to execute the purchase. Next, the transaction steps 615 - 619 are carried out to confirm the purchase, notify the tracking system, and save the transactional data on the historical database. Optionally, the process can include a step where the server 230 stores all of the information related to program buy and metric comparisons, and the final sales transaction in a historical database. This would allow the server 230 to use all of the transaction information in an analysis process for providing an improved method of obtaining the value of the program. Although the illustrated embodiment is configured to store the data related to the sales transactions, the system can also be configured to store all of the iterative quote information exchanged between the buyer and vendor. The analysis process allows the server 230 to utilize the sales history records stored in steps 619 and 711 to generate price reports for various third parties as well as provide a means of calculating current market prices for products sold in the above-described methods. The sales history records are also used as the source for a metric such as those used in the process of FIGS. 6A , 6 B, and 7 . As shown in steps 619 , 663 , and 711 , the server 230 continually updates the historical database for each sales transaction. The analysis reporting process allows a buyer or manager of buyers to conduct analysis on the historical information. This analysis would include multi-value cross compilation, for purposes of determining purchasing strategies, buyer effectiveness, program performance, vendor performance, and measuring effectiveness of forward pricing as a risk management strategy. Referring now to FIG. 9 , a flow diagram illustrating the logic of the normalization process 900 is shown. The logic of the normalization process 900 resides on the server 230 and processes the quotes received from commodity sellers. The logic begins in at a step 905 where quote data is obtained from the seller in response to the buyer's RFQ as described above. Next, at a step 910 , routine 900 iteratively calculates the board footage (BF) of each type of lumber. Once all the totals are calculated for each type, routine 900 continues to a step 915 where the server 230 calculates the total type price. At step 915 , routine 900 iteratively calculates the total type price for the amount of each type of lumber specified in the quote. The is accomplished by taking the total board footage (BF), calculated in block 910 and multiplying the total BF by the price per MBF specified in the quote. Once all the prices are calculated for each type, routine 900 continues to a step 920 where the server 230 calculates total quoted price. At step 920 the routine 900 calculates the total price for the quote by summing all the total type prices calculated at step 915 . At a step 925 , routine 900 iteratively retrieves the most current price for each type of lumber specified in the quote from a predefined metric source(s). Metrics may come from publicly available information, i.e. price of futures contracts traded on the Chicago Mercantile Exchange, subscription service publications such as Crowes™ or Random Lengths™, or internally generated metrics derived from the server database. Once all the prices are retrieved for each type, at a step 930 the routine 900 then iteratively calculates the market price for the quantity of each type of lumber in quote. Once the totals for all types are calculated, routine 900 continues to a step 935 where the routine 900 calculates the total market price for the quote by summing all the most current prices calculated in step 930 . Although this example illustrates that steps 910 - 920 are executed before steps 925 - 935 , these two groups of steps can be executed in any order, or in parallel, so long as they are both executed before a comparison step 940 . At step 940 , routine 900 compares the total quoted to the metric price to arrive at a comparative value. In one exemplary embodiment of the current invention the comparative value is a “percent of metric” value. A value higher than one (1) percent indicates a price that is above the metric rate, and a lower percent indicates a price that is below the metric rate. The operation of the routine 900 can be further illustrated through an example utilizing specific exemplary data. In the example, a buyer sends out a request for quote (RFQ) requesting a lot of 2×4 S&B lumber consisting of five units of 2″×4″×8′, two units of 2″×4″×14′, and five units of 2″×4″×16′. The buyer then receives quotes from three sellers. Seller A responds with a tally of six units of 2″×4″×8′, four units of 2″×4″×14′, and three units of 2″×4″×16′ for $287 per thousand board feet. Seller B responds with a lot of five units of 2″×4″×8′, one unit of 2″×4″×14′, and six units of 2″×4″×16′ for $283 per thousand board feet. Seller C responds with a lot of one unit of 2″×4″×8′, five units of 2″×4″×14′, and five units of 2″×4″×16′ for $282 per thousand board feet. Suppose also that the typical unit size is 294 pieces/unit, and the metric or reported market price for 2″×4″×8′s is $287.50, for 2″×4″×14′s it is $278.50, and for 2″×4″×16′s it is $288. Viewing the MBF prices for the respective quotes is not particularly informative, given that certain lengths of lumber are more desirable and priced accordingly in the marketplace. By processing the quote from Seller A using routine 900 , we arrive at a total MBF of 29.792, giving a total quoted price of $8,550.30. The selected metric price for the same types and quantities of lumber would be $8,471.12; therefore the quoted price would have a percent of market value of 100.93%. Processing the quote from Seller B using routine 900 , we arrive at a total MBF of 29.400, giving a total quoted price of $8,320.20. The selected metric price for the same types and quantities of lumber, however, would be $8,437.21; therefore the quoted price would have a percent of market value of 98.61%. Finally, processing the quote from Seller C using routine 900 , we arrive at a total MBF of 30.968, giving a total quoted price of $8,732.98. The selected metric price for the same types and quantities of lumber, however, would be $8,767.66; therefore the quoted price would have a percent of market value of 99.38%. By looking at the percent of selected metric value, it is apparent that the price from Seller B is a better value. As shown in the methods of FIGS. 5-7 , this price normalization process allows users to compare inherently different offers having different quality and quantity values. In yet another example of an application of the normalization process, additional exemplary data is used to demonstrate the analysis of a transaction having one RFQ from a buyer and two different quotes from a seller, normalized to comparable product of another species. In this example, the buyer produces an RFQ listing the following items: one carload of Eastern SPF (ESPF) lumber having four units of 2″×4″×8′, four units of 2″×4″×10′, six units of 2″×4″×12′, two units of 2″×4″×14′, and six units of 2″×4″×16′. The vendor then responds with two different quotes with two different unit tallies and two different prices. The first response lists a quote price of $320 per thousand board feet and a slight modification of the tally provides four units of 2″×4″×8′, four units of 2″×4″×10′, six units of 2″×4″×12′, three units of 2″×4″×14′, and five units of 2″×4″×16′. The second response quotes per the requested tally at a price of $322 per thousand board feet. Both quotes list the delivery location as “Chicago.” To display the quotes, the server 230 produces a Web page similar to that displayed in FIG. 8C , where the vendor's modified tally is displayed in highlighted text. The buyer can then view summary metric comparison or select the hypertext link “View Calculation Detail,” which then invokes the server 230 to produce a Web page as shown in FIG. 8D . Referring now to the Web page illustrated in FIG. 8D , the data produced by the server 230 compares the response to a selected metric of a different species, Western SPF (WSPF), for items of same size, grade, and tally. The market price for the same 2×4 tally of ESPF and WSPF are thus simultaneously compared. In an example Eastern quoted at $322 per thousand board feet, Western metric (Random Lengths 6/26/2000 print price plus freight of $80 as defined in Metric Manager) for the same tally being $331.791. This metric comparison is also represented as Quote/Metric Value or Eastern price representing 0.970490 or 97% of comparable Western product. In review of the normalization process, the buyer must select a metric source for price information for a defined item given a set of attributes, i.e., grade, species, and size. The metric may then -be mapped to the RFQ item for comparison and does not have to be equivalent of item. For instance, as explained in the above-described example, it may be desirable to map the market relationship of one commodity item to another. The most current pricing data for the metric is electronically moved from the selected source to the server 230 . As mentioned above, metrics may come from publicly available information, (i.e., price of Futures contracts traded on the Chicago Mercantile Exchange), or subscription services, (i.e., Crowes™ or Random Lengths™ Publications), or be an internal metric generated by the server 230 . This metric data is used in the normalization process for all calculations, as described with reference to the above-described methods. While the preferred embodiment of the invention has been illustrated and described, it will be appreciated that within the scope of the appended claims, various changes can be made therein without departing from the spirit of the invention. For example, in an agricultural commodity, an order for Wheat U.S. #2 HRW could be compared to a selected metric of Wheat U.S. #2 Soft White, similar to how different species are analyzed in the above-described example. The above system and method can be used to purchase other commodity items such as in the trade of livestock. In such a variation, order information such as a lumber tally would be substituted for a meat type, grade, and cut. Other examples of commodity items include agricultural products, metals, or any other items of commerce having several order parameters.

Managing and evaluating commodities pricing, in one embodiment, includes retrieving and summing one or more price data sets exchanged between a buyer and seller agent in a specified time period. Additionally, metric data indicative of market prices for commodities indicated by the retrieved price data sets are summed. The summed totals are then compared to generate a comparison value. In another embodiment, one or more price data sets in a specified time period are retrieved, wherein commodities indicated by the price data sets meet a specified criterion. The retrieved price data sets and metric data indicative of market prices for the indicated commodities are summed and compared. In another embodiment, price data in one or more requests for quote are compared with metric data to normalize quoted prices. Accordingly, multi-value cross compilation of sales transactions and metric data for evaluation of commodities pricing is achieved.

CROSS-REFERENCES TO RELATED APPLICATIONS [0001] This application claims the benefit of U.S. Provisional Application No. 62/89,329, filed Dec. 9, 2014, and U.S. Provisional Application 62/101,096, filed Jan. 8, 2015, which are incorporated by reference herein in their entirety. BACKGROUND INFORMATION Field of the Disclosure [0002] This invention relates to the polymerization of HFO-1234ze (CF 3 CH═CHF, 1,3,3,3-tetraffluoropropene) with other copolymerizable fluorinated monomers and the obtained HFO-1234ze copolymers. Description of the Related Art [0003] U.S. Patent Publication 2012/0208007 addresses the need for a barrier coating on a reflective layer applied to the back of a glass substrate to protect the reflective property of the reflective layer. The barrier coating provided in this reference is a thermosetting polymer that contains a substantial amount of a polymer having the polymeric segment of the formula —[CR 1 CF 3 —CR 2 R 3 ]—, wherein R 1 , R 2 , and R 3 are independently selected from H and F [0010]. A variety of hydrofluoroolefins (HFOs) may be used to form the polymer, HFO-1234yf (2,3,3,3-tetrafluoropropene, CF 3 CF═CH 2 ) is disclosed as a compound that is suitable [0025]. Other suitable compounds are HFO-1234zf (CF 3 CH═CH 2 ), HFO-1234ze, and HFO-1225 (pentafluoropropene) [0026]. These compounds may be copolymerized with additional monomers, mentioning about twenty five of such monomers [0027]. The sole Example uses a solution of 1234yf as the coating composition. [0004] U.S. Pat. No. 8,163,858 addresses the need for a moisture barrier and an oxygen barrier and provides a film containing vinylidene fluoride copolymerized with a fluorinated comonomer as the barrier, the film containing 50 wt % to 99 wt % of the vinylidene fluoride for the oxygen barrier and 0.1 to 50 wt % vinylidene fluoride for the moisture barrier, the fluorinated comonomer amount being 0.1 wt % to 50 wt %, and 50 wt % to 99.9 wt %, respectively (col. 2, I. 18-36). The preferred fluorinated comonomers are 2,3,3,3-tetrafluoropropene, 1,1,3,3,3-pentafluorpropene, 2-chloro-pentafluoropropene, hexafluoropropylene, trifluoroethylene, chlorotrifluoroethylene, 3,3,3-trifluoro-2-trifluoromethylpropene, and a mixture thereof (col. 3, I. 33-37). Other fluorinated comonomers are disclosed to be useful in modest amounts, mentioning greater than 40 of such comonomers, including the cis and trans isomers of 1234ze. HFO-1234yf is the only HFO used in the vinylidene fluoride copolymers of the Examples. [0005] U.S. Patent Publication 2014/008987 discloses the copolymerization of 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene, or 1-chloro-2,3,3-tetrafluoropropene with ethylenically unsaturated monomers [0007]. A number of hydrocarbon ethylenically unsaturated monomers are disclosed along with HFP, the ethylenically unsaturated monomer constituting 30 to 95 mol percent of the copolymer [0009], [0100]. The Examples are all directed to the copolymerization of 2,3,3,3-tetrafluoropropene (1234yf) with ethylene. [0006] It is apparent that any reason for interest in fluoropolymers containing HFO-1234ze as a comonomer is missing from '007 and '858. SUMMARY [0007] It has been discovered that HFO-1234ze has copolymerization capability not possessed by HFO-1234yf. It has also been discovered that HFO-1234ze copolymerizes at a faster rate than hexafluoropropylene that is present in many fluoropolymers, i.e. fluoroplastics and fluoroelastomers. It has further been discovered that once incorporated into the fluoropolymer in place of hexafluoropropylene, the thermal stability of the fluoropolymer improves. [0008] These discoveries and other advantages are embodied in the HFO-1234ze copolymers of the present invention, which can be described as copolymer comprising 1,3,3,3-tetrafluoropropene (1234ze) and one or more comonomers selected from the group consisting of vinyl fluoride (VF), vinylidene fluoride (VF 2 ), tetrafluoroethylene (TFE), chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), and perfluoro(alkyl vinyl ether) (PAVE), wherein said alkyl contains 1 to 5 carbon atoms. [0009] The copolymer can be a fluoroplastic or a fluoroelastomer, depending upon its monomer content. [0010] When the copolymer is a fluoroelastomer, the 1234ze is a cure site for the fluoroelastomer. The function of the 1234ze monomer as a cure site in the copolymer can be described as the process comprising forming by copolymerization the copolymer comprising 1,3,3,3-tetrafluoropropene (1234ze) and one or more comonomers selected from the group consisting of vinyl fluoride (VF), vinylidene fluoride (VF 2 ), tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and perfluoro(alkyl vinyl ether) (PAVE), wherein said alkyl contains 1 to 5 carbon atoms and curing said copolymer. [0011] In one embodiment, the 1234ze can be present in the copolymer in place of some or all of the HFP. When HFP is present in the copolymer along with the 1234ze, then preferably at least one other comonomer that is copolymerizable with the 1234ze and HFP is present, preferably a fluoroolefin, more preferably VF 2 and/or TFE. [0012] In another embodiment, the copolymer comprises the 1234ze and VF. Preferably, the amount of 1234ze in the copolymer is at least 18 mol %. [0013] In another embodiment, the copolymer comprises the 1234ze, VF and TFE. [0014] In another embodiment, the copolymer comprises the 1234ze, the TFE, and the VF 2 and optionally the HFP. [0015] In another embodiment, the copolymer comprises the 1234ze, the TFE and optionally, the HFP. [0016] In another embodiment, the copolymer comprises the 1234ze, the TFE, and ethylene and optionally the HFP. [0017] In another embodiment, the copolymer comprises the 1234ze, CTFE and ethylene or 1234ze, CTFE, TFE, and ethylene, either copolymer optionally comprising modifying monomer described hereinafter. [0018] In another embodiment, the copolymer comprises the 1234ze, the TFE, the VF 2 , and optionally the HFP. [0019] In another embodiment, the copolymer is a fluoroelastomer, comprising the 1234ze and either the VF 2 or the perfluoro(alkyl vinyl ether), preferably perfluoro(methyl vinyl ether) (PMVE). In a preferred aspect of this embodiment, the copolymer (fluoroelastomer) comprises the 1234ze, the VF 2 , the TFE, and optionally, the HFP. Preferably, this copolymer (fluoroelastomer) additionally comprises the HFP. In another preferred aspect of this embodiment, the 1234ze/VF 2 /TFE copolymer (fluoroelastomer) additionally comprises the perfluoro(alkyl vinyl ether), preferably PMVE. In another embodiment, the copolymer (fluoroelastomer) comprises the 1234ze, the TFE and the perfluoro(alkyl vinyl ether), preferably PMVE. [0020] Examples of copolymers of the present invention include the following: [0021] Fluoroplastics: 1234ze/VF 1234ze/VF/TFE 1234ze/TFE 1234ze/TFE/HFP 1234ze/TFE/ethylene 1234ze/TFE/HFP/ethylene 1234ze/CTFE/ethylene 1234ze/CTFE/TFE/ethylene 1234ze/TFE/VF 2 1234ze/TFE/VF 2 /HFP 1234ze/VF 2 [0033] Fluoroelastomers: 1234ze/VF 2 1234ze/VF 2 /HFP 1234ze/VF 2 /TFE 1234ze/VF 2 /TFE/HFP 1234ze/VF 2 /TFE/PMVE 1234ze/TFE/PMVE [0040] The monomers present in these fluoroplastics and fluoroelastomers are present in an effective amount to obtain the plastic or elastomer nature indicated. DETAILED DESCRIPTION [0041] The HFO-1234ze used in the present invention can be the cis or trans isomer configuration or can be a mixture of these isomers. [0042] For simplicity, the copolymers of the present invention are described in terms of the monomers from which they are obtained by copolymerization. These monomers are present in the copolymer as repeat units, e.g. —CF 2 —CF 2 — for TFE, —CH 2 —CHF— for VF, —CH 2 —CF 2 — for VF 2 , —CCF 3 —CF 2 — for HFP, —CF 2 —CFOCF 3 — for PMVE, —ClFC—CF 2 — for CTFE, and —CHCF 3 —CHF— for 1234ze. [0043] The term copolymer(s) used herein includes polymers comprising two or more comonomers. Thus, the 1234ze copolymers of the present invention include copolymers of 1234ze with at least one additional comonomer. The term copolymer(s) includes dipolymers, terpolymers, quatrapolymers, and even copolymers containing a greater number of comonomers. [0044] With reference to the copolymers of the present invention: The transitional terms “comprises”, “comprising”, “includes”, “including”, “has”, “having” or any other variation thereof cover the presence of comonomers in addition to those specifically identified in copolymers. The transitional phrase “consisting of” excludes the presence of such additional comonomers in the copolymer. The transitional phrase “consisting essentially of” includes comonomers in addition to those literally disclosed provided that these additional included comonomers do not materially affect the basic and novel characteristic(s) of the claimed invention. The term “consisting essentially of” occupies a middle ground between “comprising” and “consisting of.” While the preferred transitional term for the copolymers of the present invention is “comprising” or the like as described above, it is also contemplated that the transitional terms “consist of” and the like or “consisting essentially of” can apply to one or more or all of these copolymers. [0045] The term elastomer in fluoroelastomer refers to the copolymer exhibiting rubbery character, i.e. being capable of recovering its original shape after being stretched to high elongation, e.g. at least 50%. The copolymer is considered a fluoroelastomer whether exhibiting its elastomer character as-polymerized or only after curing. In contrast, fluoroplastics are not rubbery, but instead are rigid and in thin sections, flexible. With Respect to Fluoroplastics: [0046] Preferred fluoroplastic copolymers of 1234ze with VF include dipolymers and copolymers of 1234ze and VF with at least one additional comonomer that is copolymerizable with 1234ze and VF. Preferably, the additional comonomer(s) is fluoroolefin, preferably containing at least two carbon atoms substituted onto carbon atoms that become part of the main chain of the copolymer. The preferred dipolymer is 1234ze/VF. Preferably, the composition of the dipolymer is 2 to 40 mol % of the 1234ze and 98 to 60 mol % VF to total 100 mol % of the combination of these comonomers. When 1234yf is used in place of 1234ze in the copolymerization with VF, the amount of 1234yf that will copolymerize with the VF is limited, such that the resultant copolymer contains no more than 14 mol % of the 1234yf. Even when an excess amount of 1234yf is present in the copolymerization medium, and measures are taken to facilitate the copolymerization of the 1234yf, the maximum amount that copolymerizes with the VF is 14 mol %. Thus, a preferred 1234ze/VF composition is wherein the 1234ze comprises 15 to 40 mol % and the VF comprises 5 to 60 mol %, to total 100 mol % of the combination of these conomomers. [0047] Another preferred fluoroplastic copolymer of 1234ze with VF is the copolymer comprising 1234ze/VF/TFE. Preferably, the composition of this copolymer is 1 to 25 mol % 1234ze, 20 to 85 mol % VF, and 10 to 80 mol % TFE, to total 100 mol % of the combination of these monomers. Still another preferred copolymer is the copolymer comprising 1234ze/VF/TFE/VF 2 , wherein the composition is 1 to 25 mol % 1234ze, 20 to 85 mol % VF, and 10 to 80 mol % of the combination of the TFE and VF 2 , to total 100 mol % of the combination of these monomers. The combination of TFE and VF 2 monomers in the copolymer is preferably 10 to 90 mol % of each monomer to total 100 mol % of this combination of these monomers. [0048] Many of these 1234ze/VF copolymers, including terpolymers and quatrapolymers) are soluble in DMF(dimethyl formamide) or DMAC (dimethylacetamide) when heated to 75 to 100° C. The resultant solutions can be cast onto a surface and dried to form either a film that is separable from the surface or a coating on the surface. The film or coating exhibits high resistance to weathering in outdoor exposure. The resultant solution are solvent borne coatings that are useful in the semiconductor industry, the electronic industry, top coats for photoresists, anti-reflective coatings, wire coatings, protective coatings for oil and gas, and photovoltaics. [0049] The copolymers with high TFE content can be melt fabricated by such processes as extrusion and injection molding into films and other shapes that can be used in outdoor environments. [0050] Preferred fluoroplastic copolymers of 1234ze/TFE include dipolymers and copolymers with at least one additional comonomer that is copolymerizable with 1234ze and TFE. Preferably, the additional comonomer(s) is fluoroolefin, preferably containing at least two carbon atoms substituted onto carbon atoms that become part of the main chain of the copolymer. Alternatively, the additional comonomer can be ethylene. The dipolymer resembles the well-known fluoroplastic FEP, which comprises a copolymer of TFE and HFP, except that the 1234ze replaces all of the HFP, and imparts to the resultant 1234ze/TFE copolymer both a faster copolymerization rate and improved thermal stability. The repeat unit —CHCF 3 —CHF— derived from 1234ze by copolymerization does not give the thermally unstable —CF 3 CF—CF 3 CF— diad that arises from head-to-tail coupling of HFP repeat units. U.S. Pat. No. 4,626,587 discloses the thermal instability of this diad. Preferably the composition of the copolymer comprises 1 to 20 mol % 1234ze and 99 to 80 mol % TFE, to total 100 mol % of the combination of these monomers, more preferably 2 to 10 mol % 1234ze and 98 to 90 mol % TFE, to total 100 mol % of the combination of these monomers. In another embodiment, the 1234ze is present in the copolymer in place of only a portion of the HFP, whereby the resultant copolymer comprises 1234ze/TFE/HFP. Both embodiments can be described as the copolymer comprising 1234ze, TFE and optionally, HFP, the combined amount of the 1234ze and the HFP, when present, being from 1 to 20 mol %, and each of the 1234ze and HFP, when present, being in at least the amount of 0.1 mol %, the TFE being present in the amount of 80 to 99 mol %, to total 100 mol % based on the combined mol % of the 1234ze, the TFE and the HFP, when present. More preferably, the copolymer comprises 1234ze, TFE and optionally, HFP, the combined amount of the 1234ze and the HFP, when present, being from 1 to 10 mol %, and each of the 1234ze and HFP, when present, being in at least the amount of 0.1 mol %, the TFE being present in the amount of 90 to 99 mol %, to total 100 mol % based on the combined mol % of the 1234ze, the TFE and the HFP, when present. In a preferred embodiment, the HFP is present in at least the 0.1 mol % amount, preferably at 0.5 mol % amount, up to the maximum amounts of 20 mol % and 10 mol % mentioned above, and more preferably no more than 5 mol %, the 12134ze making up the difference to total the 20 ml % or 10 mol % maximums mentioned above. [0051] The 1234ze/TFE copolymer and the 12324ze/TFE/HFP copolymer can also comprise a small amount of additional fluoromonomer, such as perfluoro(ethyl vinyl ether) or perfluoro(propyl vinyl ether) to improve MIT flex life of the copolymer. Such small amount of fluoroolefin is from 0.2 to 3 wt % of the total weight of the copolymer. [0052] Another embodiment of 1234ze/TFE copolymer is the copolymer comprising 1234ze/TFE/ethylene and optionally HFP or PFBE (perfluorobutyl ethylene, CF 3 (CF 2 ) 2 CH═CH 2 ). This embodiment has two aspects. A composition applicable to both of these aspects is 0.1 to 10 mol % 1234ze, 1 to 95 mol % TFE, and 2 to 60 mol % ethylene. [0053] According to one aspect, the 1234ze replaces some or all of the PFBE modifier for ETFE (ethylene/tetrafluoroethylene) copolymer. The modifier is present in a small amount in the ETFE copolymer to improve stress crack resistance. The preferred composition for this aspect is 0.1 to 10 mol % 1234ze, 40 to 60 mol % TFE, and 40 to 60 mol % of the ethylene, based on the combined mol % of the 1234ze, TFE and ethylene totaling 100 mol %. This aspect also contemplates that not all of the PFBE is replaced by the 1234ze , whereby the copolymer is 1234ze/PFBE/TFE/ethylene having the same preferred composition as set forth above, except that the 1234ze and PFBE comprises the 0.1 to 10 mol % portion of the copolymer. Preferably the 1234ze comprises at least 20% of the mols making up this portion and comprises at least 0.1 mol % of the overall copolymer. These copolymers have the same utilities as ETFE copolymer modified with PFBE, such as electrical wire insulation. [0054] According to the other aspect of this embodiment, the 1234ze is present in the copolymer in place of some or all of the HFP in the copolymer TFE/HFP/ethylene. A preferred composition of this copolymer is 2 to 60 mol % 1234ze, 1 to 95 mol % TFE and 2 to 60 mol % ethylene, to total 100 mol % of the combination of these monomers. When HFP is also present in the copolymer, the combination of the 1234ze and HFP totals the 2 to 60 mol %, the amounts of TFE and ethylene being the same as set forth above. The 1234ze and HFP preferably each comprise at least 1% of the 2 to 60 mol %, and more preferably at least 2% of the total mol % of the 1234ze and HFP combined, with the proviso that the copolymer comprises at least 12 mol % of the 1234ze, preferably at least 3 mol % of the 1234ze, based on the combined mol % of the 1234ze, the TFE, the HFP, and the ethylene totaling 100 mol %. Another preferred composition of the copolymer is 2 to 25 mol % 1234ze, 60 to 95 mol % TFE, and 2 to 25 mol % ethylene, to total 100 mol % of the combination of these monomers. When HFP is also present in the copolymer, the combination of the 1234ze and HFP totals the 2 to 25 mol %, the amounts of TFE and ethylene being the same as set forth above for this preferred composition. The 1234ze and HFP preferably each comprise at least 1% of the 2 to 25 mol %, and more preferably at least 2% of the total mol % of the 1234ze and HFP combined, with the proviso that the copolymer comprises at least 2 mol % of the 1234ze, preferably at least 3 mol % of the 1234ze, based on the combined mol % of the 1234ze, the TFE, the HFP, and the ethylene totaling 100 mol %. The 1234ze/TFE/ethylene and 1234ze/TFE/HFP/ethylene copolymers of the present invention are preferably amorphous, i.e. have no to low crystallinity such that they can be melt fabricated into transparent films. They also have low dielectric constant, making the films useful as insulation in the electronics applications. [0055] The 1234ze/TFE copolymers are insoluble in hydrocarbon solvents, even at elevated temperature, but are melt fabricable by such molding techniques as extrusion and injection molding into such shapes as film and tubes for utility in the same way as FEP. [0056] Another embodiment of preferred fluoroplastic copolymers is the copolymer wherein 1234ze replaces some or all of the HFIB (hexafluoroisobutylene) stress crack modifier of the ECTFE (ethylene/chlorotrifluoroethylene) copolymer. A preferred composition of this copolymer.comprises 40 to 60 mol % ethylene, 40 to 60 mol % of either CTFE or CTFE and TFE, and 0.1 to 10 mol % of 1234ze, based on the combined mol % totaling 100 mol %. The CTFE component may constitute the entire 40 to 60 mol % or up to 80% of the mols of CTFE and TFE making up this 40 to 60 mol % component of the copolymer. Thus, this copolymer can be 1234ze/CTFE/ethylene or 1234ze/CTFE/TFE/ethylene. Any of these copolymers can also comprise HFIB in place of part of the 0.1 to 10 mol % 1234ze component. For example, the HFIB can replace at least 20% of the mols of 1234ze component, with the proviso that the minimum content of the 1234ze in the copolymer is at least 0.1 mol %, preferably at least 0.5 mol %. Thus, the copolymer of this embodiment in which the presence of TFE and HFIB in the copolymer are both optional independent of one another contemplates 1234ze/CTFE/ethylene/HFIB and 1234ze/CTFE/TFE/ethylene/HFIB copolymers as well as these copolymers without either the TFE or the HFIB. The copolymers of this embodiment of the present invention are useful as a corrosion-resistant coating on corrosion susceptible substrates. [0057] Preferred fluoroplastic copolymers of 1234ze/VF 2 include dipolymers and copolymers with at least one additional comonomer that is copolymerizable with 1234ze and VF 2 . Preferably, the additional comonomer(s) is fluoroolefin, preferably containing at least two carbon atoms substituted onto carbon atoms that become part of the main chain of the copolymer. Preferably, the composition of the dipolymer is 2 to 35 mol % of the 1234ze and 98 to 65 mol % VF 2 to total 100 mol % of the combination of these comonomers. Preferably the copolymer comprises 1234ze, TFE, VF 2 and optionally HFP. The 1234ze can be present in the copolymer in place of part or all of the HFP found in TFE/VF 2 /HFP copolymer. The preferred composition of the copolymer 1234ze/VF 2 /TFE is 2 to 20 mol % 1234ze, 15 to 50 mol % VF 2 , and 20 to 80 mol % TFE, to total 100 mol % of the combination of these monomers. The preferred composition of the copolymer 1234ze/VF 2 /TFE/HFP is the same as for the 1234ze/VF 2 /TFE copolymer, except that the 2 to 20 mol % of the 1234ze is applicable to the combination of the 1234ze and the HFP. With respect to this 1234ze/HFP combination, the amount of 1234ze present is 10 to 90 mol %, and the amount of HFP present is 90 to 10 mol %, total 100 mol % of the combination of monomers. These copolymers are melt fabricable by such molding techniques as extrusion and injection molding into such shapes as film for coating or and tubes for conveying fluids. With Respect to Fluoroelastomers: [0058] Preferred fluoroelastomers are copolymers comprising 1234ze/VF 2 and exhibiting a Tg of no greater than 5° C. and preferably no greater than 0° C. The 1234ze comonomer represents a site for curing of the fluoro-elastomer. The dipolymer 1234ze/VF 2 preferably has the composition of 5 to 35 mol % 1234ze and 95 to 65 mol % VF 2 , to total 100 mol % of the combination of these monomers. Preferred copolymers of 1234ze/VF 2 comprise at least one additional monomer that is copolymerizable with 1234ze and VF 2 . Preferably, the additional comonomer(s) is fluoroolefin, preferably containing at least two carbon atoms substituted onto carbon atoms that become part of the main chain of the copolymer. Preferred additional monomers are one or more of HFP, TFE, and PMVE. [0059] A preferred fluoroelastomer comprises 1234ze/VF 2 /HFP having the following composition: (1234ze+HFP)/VF 2 =(30 to 15)/70 to 85 mol % to total 100 mol % (same meaning as to total 100 mol % of the combination of these monomers). Preferably, the 1234ze comprises 5 to 95% and the HFP comprises 95 to 5% to total 100% of the 30 to 15 mol %, more preferably 10 to 90% of the 1234ze and 90 to 10% of the HFP to total 100% of the 30 to 15 mol %. [0060] Another preferred fluoroelastomer comprises 1234ze/VF 2 /TFE having the following composition: 1234ze/VF 2 /TFE=15 to 25/50 to 80/7 to 30 mol % to total 100 mol %. [0061] Another preferred fluoroelastomer comprises 1234ze/VF 2 /TFE/HFP having the following composition: (1234ze+HFP)/VF 2 /TFE=(15 to 25)/50 to 80/7 to 30 mol % to total 100 ml %. Preferably, the 1234ze comprises 5 to 95% and the HFP comprises 95 to 5% to total 100% of the 15 to 25 mol %, more preferably 10 to 90% of the 1234ze and 90 to 10% of the HFP to total 100% of the 15 to 25 mol %. [0062] Another preferred fluoroelastomer comprises 1234ze/VF 2 /TFE/PMVE having the following composition: 1 to 40 mol % 1234ze, 15 to 60 mol % VF 2, 5 to 25 mol % TFE, and 15 to 40 mol % PMVE, to total 100 mol % of the combination of these monomers. [0063] Another preferred elastomer also having a Tg of no greater than 5° C., preferably no greater than 0° C. comprises 1234ze/TFE/PMVE preferably having the composition 0.1 to 5/55 to 65/35 to 45 mol % to total 100 mol % [0064] The as-copolymerized fluoroelastomer is typically a gum that can be incorporated such as by compounding with additional ingredients as desired and then cured to exhibit the rubbery character. The curing is carried out by incorporating curing agent, preferably that which is nucleophilic for crosslinking reaction with the 1234ze monomer present in the copolymer, into the copolymer and heating the resultant copolymer/curing agent mixture. Prior to heating, the compounded copolymer is formed into the desired shape of the article to be cured. [0065] Such additional ingredients for compounding into the copolymer include particulate filler such as barium sulfate or titanium dioxide, acid acceptor such as metal oxide, such as magnesium oxide or calcium hydroxide, curing agent such as ethylenediamine carbamate, hexamethylene diamine carbamate, triethylenetetramine/benzoyl peroxide, and N,N′-m-phenylene dimaleimide. Additional curing agent is disclosed in Example 23 below. The compounded copolymer can then be formed by conventional hot processing into such shapes as seals, gaskets, o-rings, and hoses, followed by post-curing at elevated temperatures such as 450° F. (232° C.). [0066] The copolymerization process to prepare 1234ze copolymers of the present invention is preferably conducted, as in the Examples below, to produce random copolymers, i.e. without programming the monomer feed into the polymerization reaction to produce block copolymer. [0067] A typical large scale process for the copolymerization to form 1234ze copolymers of the present invention is aqueous dispersion polymerization of the monomers in a stirred heated reactor containing a fluorosurfactant, free radical initiator, and deionized water. As the polymerization proceeds, additional monomers are added to maintain the pressure, along with additional feeds of surfactant and initiator. A chain transfer agent may be employed in the copolymerization of some polymers to control molecular weight. To terminate the copolymerization, all the feeds are stopped, the reactor is vented and purged with nitrogen, and the raw copolymer dispersion in the reactor is transferred to a cooling vessel. For use in coatings for metals, glass and fabric, the polymer dispersion is typically transferred to a dispersion concentration operation which produces stabilized dispersions used as coatings. Alternatively, the copolymer dispersion is coagulated, and the coagulated copolymer is separated from the aqueous medium and is dried to obtain copolymer powder, which can then be used to fabricate articles such as by melt-processing in the case of fluoroplastics or press fabrication, followed by post-curing in the case of fluoroelastomers EXAMPLES [0068] Thermal Stability Test—In this Test, the thermal stability of the copolymer is determined by heating up a sample of the copolymer, during which time, the %wt loss is measured. The higher the temperature before the %wt loss reaches 5 wt %, the greater the thermal stability of the copolymer. The Thermal Stability Test is conducted using a Q50 TGA (thermo gravimetric analyzer) instrument by TA Instruments. The test is run under air from room temperature to 500° C. by heating a copolymer sample (10 to 15 milligrams) at the rate of 10° C./minute. The weight loss of the sample is monitored and recorded. From this recording, the temperature at which the weight loss reaches 5 wt % can be calculated. Examples 1 to 8 VF/TFE/1234ze Copolymer [0069] A 400 mL Hastelloy® C shaker tube is charged with distilled water (200 mL), Capstone® FS-10 (5.30 g), disodium hydrogen phosphate (1.3 g) and ammonium persulfate (0.16 g), cooled, evacuated and nitrogen flushed. Vinyl fluoride (3.125 g), tetrafluoroethylene (50 g) and 1, 3,3,3-tetrafluoropropene (9.4 g) is then charged to the shaker tube. Vigorous shaking of the shaker tube is started and continued throughout the run. The shaker tube is heated to 70° C. causing the pressure in the autoclave to increase from 260 to 645 psi (1.8 to 4.5 MPa). Shaking and heating were stopped 18 minutes later after pressure had decreased 21% to 513 psi (3.5 MPa). This gives a polymer emulsion that is coagulated by adding 100 ml of saturated aqueous MgSO4 with vigorous stirring. The precipitated polymer is collected by filtration and washed several times with warm water (70° C.). After drying in vacuum oven (100 mmHg) at 80° C. for 24 hours, 28 g of white polymer are obtained. Polymer Analysis: [0070] DSC, 10° C./min, N2, second heat: Tm at 199° C. and Tm at 288° C. Composition 19 F NMR (mol %): VF/TFE/1,3,3,3-tetrafluoropropene terpolymer (15.74/78.4/5.86). Copolymerization in a reactor to which the monomers are fed to the reactor during copolymerization yields a copolymer having a single melting temperature (Tm). [0071] The same experimental procedure is applied to Example 2 to 8, and the results are listed in Table 1. [0000] TABLE 1 VF-TFE-1,3,3,3-tetrafluoropropene Terpolymer Example # 1 2 3 4 5 6 7 8 Material charge DI water g 200 200 200 220 180 180 180 180 APS g 0.16 0.16 0.16 0.16 0.16 0.16 0.16 0.16 Na 2 HPO4.7H 2 O g 1.30 1.30 1.30 1.30 1.3 1.3 1.3 1.3 FS-10 g 5.30 5.30 5.30 5.30 5.3 5.3 5.3 5.3 VF g 3.13 8.30 15 20 9 20 34 60 TFE g 50 50 40 20 50 40 30 20 CF 3 CH═CHF g 9.4 17 45 60 3.125 6.7 11.25 20 Reaction condition Temp ° C. 70 71.9 71.9 70 68 68.4 70 71.4 Init Pressure MPa 4.5 4.8 4.7 4.1 4.8 4.9 5.4 6.1 Final Pressure MPa 3.5 3.8 3.8 3.3 3.9 3.9 4.3 4.7 time for P drop min 18 17 13 21 5 11 9 22 Product Polymer g 28 16.2 28.7 26 19.5 24 27 30 Thermal data Tg ° C. (−13.3), (−13.9), 37.13 45.6 41.7 (39.3)   (37.8)   Tm ° C. (199) 173.35 134.7 N/A 197 180.7 168.3 151.1 (288), 5 wt % loss of ° C. 348.75 321.87 328.52 354.46 304 325.69 302 297 Polymer in air Polymer composition by 19 F NMR VF mol % 20.77 40.66 48.05 52.96 46.87 60.69 77.72 82.41 TFE mol % 76.82 55.04 44.29 28.56 52.24 36.56 19.22 12.02 CF 3 CH═CHF mol % 2.4 4.3 7.65 18.48 0.89 2.75 3.06 5.56 [0072] The copolymer of Example 4 exhibits the highest thermal stability, arising from this copolymer containing the highest amount of 1234ze, notwithstanding that this copolymer contains a substantial amount of VF and relatively small amount of TFE. The copolymer of Example 4 has no melting temperature, indicating the absence of crystallinity. The reaction time (time for pressure drop) for all of the copolymers of Examples 1 to 8 is short, indicating the high reactivity of 1234ze in copolymerization. The copolymers are insoluble in hydrocarbon solvents at ambient temperature (about 20° C.) temperature, but are soluble in DMF and DMAC heated to temperatures of 75 to ° C. Examples 9 to 12 HFP-TFE-1234ze Copolymer [0073] A 400 mL Hastelloy® C shaker tube is charged with distilled water (200 mL), Capstone® FS-10 (5.30 g), disodium hydrogen phosphate (1.3 g) and ammonium persulfate (0.16 g), cooled, evacuated and nitrogen flushed. Hexafluoropropylene (3.5 g), tetrafluoroethylene (50 g) and 1,3,3,3-tetrafluoropropene (17 g) are then charged to the shaker tube. Vigorous shaking of the shaker tube is started and continued throughout the run. The shaker tube is heated to 70° C. causing the pressure in the autoclave to increase from 192 to 572 psi (1.3 to 3.9 MPa). Shaking and heating are stopped 33 minutes later after pressure has decreased 21% to 458 psi (3.2 MPa). This gives a polymer emulsion that is coagulated by adding 100 ml of saturated aqueous MgSO4 with vigorous stirring. The precipitated polymer is collected by filtration and washed several times with warm water (70° C.). After drying in vacuum oven (100 mmHg) at 80° C. for 24 hours, 24.1 g of white polymer are obtained. [0074] Polymer Analysis: DSC, 10° C./min, N2, second heat: Tm at 289° C. Composition 19 F NMR (mol %): HFP/TFE/1,3,3,3-tetrafluoropropene terpolymer (0.5/95.66/3.84) [0077] The same experimental procedure is applied to Example 10 to12 and the results are listed in Table 2. [0000] TABLE 2 HFP-TFE-1,3,3,3-tetrafluoropropene Terpolymer Example # 9 10 11 12 Material charge DI water g 180 200 200 200 APS g 0.16 0.16 0.16 0.16 Na 2 HPO4.7H 2 O g 1.30 1.30 1.30 1.30 FS-10 g 5.30 5.30 5.30 5.30 HFP g 3.50 17.00 40 60 TFE g 50 50 45 30 CF 3 CH═CHF g 17 17 15 10 Reaction condition temp ° C. 70 72 71 71 Init Pressure MPa 3.9 4.1 4.0 4.0 Final Pressure MPa 3.2 3.3 3.2 2.7 time for Pressure drop min 33 43 73 163 Product polymer g 24.1 26 34 24 Thermal data Tm ° C. 289 284 280 276 5 wt % loss of Polymer ° C. 463 432 424 412 Polymer composition by 19 F NMR HFP mol % 0.5 1.11 2.29 4.54 TFE mol % 95.66 95.4 94.35 92.36 CF 3 CH═CHF mol % 3.84 3.49 3.36 3.1 [0078] HFP-TFE-1,3,3,3-tetrafluoropropene terpolymer (Table 2) data demonstrates 1,3,3,3-tetrafluoropropene reacts faster with TFE than does HFP. This is indicated by the increase in time for pressure drop (reaction time) as the HFP content increases, with relatively small change in 1234ze content. The 5% polymer weight loss in air indicates that the terpolymer is more thermally stable as 1,3,3,3-tetrafluoropropene content increases. The polymer composition of Example 9, having the highest 1234ze content, exhibits the highest temperature reached before weight loss reaches 5 wt %. The copolymers of Examples 9 to 12 are all insoluble in hydrocarbon solvents, including DMF and DMAC heated to temperatures of 75 to 100° C. Examples 13 to 18 VF-1234ze Copolymer [0079] A 400 mL Hastelloy C shaker tube was charged with distilled water (200 mL), Pluronic® 31R1 (0.1 g) and Vazo-50 (0.05 g), cooled, evacuated and nitrogen flushed. Vinyl fluoride (90 g) and 1,3,3,3-tetrafluoropropene (10 g) are then charged to the shaker tube. Vigorous shaking of the shaker tube is started and continued throughout the run. The shaker tube is heated to 80° C. causing the pressure in the autoclave to increase from 168 to 1240 psi (1.2 to 8.6 MPa). Shaking and heating are stopped 33 minutes later after pressure has decreased 20% to 981 psi (6.9 MPa). This gives a polymer emulsion that is coagulated by adding 100 ml of saturated aqueous MgSO4 with vigorous stirring. The precipitated polymer is collected by filtration and washed several times with warm water (70° C.). After drying in vacuum oven (100 mmHg) at 80° C. for 24 hours, 47 g of white polymer are obtained. [0080] Polymer Analysis: DSC, 10° C./min, N2, second heat: Tg at 44° C. and Tm at 179° C. Composition 19 F NMR (mol %): VF/1,3,3,3-tetrafluoropropene copolymer (97.9/2.1). [0083] The same experimental procedure is applied to Example 14 to18, and the results are listed in Table 3. [0000] TABLE 3 VF-1,3,3,3-tetrafluoropropene Copolymer Example # 13 14 15 16 17 18 Material charge DI water g 200 200 200 200 200 200 V-50 g 0.05 0.05 0.05 0.05 0.05 0.05 VF g 90 75 50 25 70 65 CF 3 CH═CHF g 10 25 50 75 30 35 31R1 g 0.1 0.1 0.1 0.1 0.1 0.1 Reaction condition Temp ° C. 80 80 80.2 80.5 80.8 81.3 Init. Pressure MPa 8.3 8.1 5.5 3.9 7.1 6.4 Final Pressure MPa 6.8 6.5 4.4 3.7 5.5 5.1 time for min 32 50 100 420 51 52 Pressure drop Product Polymer g 47 39 40 10 46 48 Thermal data Tg ° C. 44 38 38 46 36 36 Tm ° C. 179 154 N/A N/A 139 N/A 5 wt % loss of Polymer ° C. 300 303 313 327 316 298 Polymer composition by 19 F NMR CH 2 ═CHF mol % 97.9 93.59 81.01 69.96 91.76 89.37 CF 3 CH═CHF mol % 2.1 6.41 18.99 30.04 8.24 10.63 [0084] The copolymers are all insoluble in hydrocarbon solvents at ambient temperature, but are soluble in DMF and DMAC heated to 75 to 100° C. [0085] The same series of experiments are run with VF-2,3,3,3-tetrafluoropropene (HFO-1234yf) under the same conditions. The 2,3,3,3-tetrafluoropropene incorporation levels off at 13 to 16 mol %. Greater amounts of 1234yf added to the reactor does not result in an increase in 1234yf incorporation greater than 16 mol % in the copolymer. This maximum incorporation of 1234yf into the copolymer does not increase with changes made to the copolymerization process in attempts to increase this maximum incorporation amount, including extending the reaction time and increasing the 1234yf monomer feed. Examples 19 to 22 TFE-1234ze Copolymer [0086] A 400 mL Hastelloy C shaker tube is charged with distilled water (180 mL), Capstone® FS-10 (5.30 g), disodium hydrogen phosphate (1.3 g) and ammonium persulfate (0.16 g), cooled, evacuated and nitrogen flushed. Tetrafluoroethylene (45 g) and 1,3,3,3-tetrafluoropropene (5 g) are then charged to the shaker tube. Vigorous shaking of the shaker tube is started and continued throughout the run. The shaker tube is heated to 70° C. causing the pressure in the autoclave to increase from 156 to 543 psi (1.1 to 3.7 MPa). Shaking and heating are stopped 33 minutes later after pressure has decreased 20% to 434 psi (3.0 MPa). This gives a polymer emulsion that is coagulated by adding 100 ml of saturated aqueous MgSO4 with vigorous stirring. The precipitated polymer is collected by filtration and washed several times with warm water (70° C.). After drying in vacuum oven (100 mmHg) at 80° C. for 24 hours, 18 g of white polymer are obtained. [0087] Polymer Analysis: DSC, 10° C./min, N2, second heat: Tm at 306.5° C. Composition 19 F NMR (mol %): TFE/1,3,3,3-tetrafluoropropene copolymer (98/2) [0090] The same experimental procedure was applied to Example 20 to 22, and the results are listed in Table 4. [0000] TABLE 4 TFE-1,3,3,3-tetrafluoropropene Copolymer Example # 19 20 21 22 Material charge DI water g 180 180 180 180 APS g 0.16 0.16 0.16 0.16 Na 2 HPO4.7H 2 O g 1.30 1.30 1.30 1.30 FS-10 g 5.30 5.30 5.30 5.30 TFE g 45 50 50 25 CF 3 CH═CHF g 5 17 50 75 Reaction condition Temp ° C. 69.8 70.5 70.4 70.7 Init Pressure MPa 3.7 4.2 3.8 2.8 Final Pressure MPa 3.0 3.4 3.1 2.4 time for Pressure drop min 14 31 140 442 Product Polymer g 18 25 19 9 Thermal data Tm ° C. 306.5 289.7 260.4 207.47 5 wt % loss of Polymer ° C. 434.34 437.15 402.01 370.6 Polymer composition by 19 F NMR TFE mol % 98 96.3 92.17 86.6 CF 3 CH=CHF mol % 2 3.7 7.83 13.4 [0091] The polymerizations Examples 19 to 22 above are repeated, except that the 1234ze is replaced by HFP to demonstrate the faster copolymerization when 1234ze is used instead of HFP. The results are shown in Table 5. [0000] TABLE 5 TFE-HFP Copolymer Comparative Examples 1 2 3 4 Material charge DI water g 180 180 180 180 APS g 0.16 0.16 0.16 0.16 Na 2 HPO4.7H 2 O g 1.3 1.3 1.3 1.3 FS-10 g 5.3 5.3 5.3 5.3 TFE g 50 45 25 10 CF 3 CF═CF 2 g 17 45 75 90 Reaction condition Temp ° C. 60.3 70 70 72.5 Init Pressure MPa 3.9 3.7 3.0 2.6 Final Pressure MPa 3.2 3.0 2.4 2.4 time for Pressure drop min 15 21 88 104 Product Polymer g 25.36 24.19 25.01 11.55 Thermal data Tm ° C. 311.7 298.9 287.7 228.4 5 wt % loss of Polymer ° C. 422.99 426.81 396.46 379.8 Polymer composition by 19 F NMR TFE mol % 97.84 95.66 90.37 84.79 CF 3 CF═CF 2 mol % 2.16 4.34 9.63 15.21 [0092] The copolymers of Examples 19 to 22 are all insoluble in hydrocarbon solvents, including DMF and DMAC heated to 75 to 100° C. [0093] Comparing TFE-1,3,3,3-tetrafluoropropene copolymer (Table 4) with TFE-HFP copolymer (Table 5), TFE/1,3,3,3-tetrafluoropropene copolymer has better incorporation with TFE than HFP based on NMR data. The copolymerizations carried out using HFP require a much greater proportion of HFP feed into the reactor than when 1234ze is used. The copolymer of TFE-1,3,3,3-tetrafluoropropene is thermally more stable than TFE-HFP copolymer by the higher 5 wt % loss temperatures for the 1234ze-containing copolymer at least for compositions containing up to 8 or 10 mol % 1234ze. Example 23 fluoroelastomer of 1234zeNF2/TFE/PMVE Copolymer [0094] This fluoroelastomer is prepared by a semi-batch emulsion polymerization process, carried out at 80° C. in a well-stirred reaction vessel. A water solution is prepared by dissolving 1.75 g sodium phosphate dibasic heptahydrate and 0.42 g of sodium octyl sulfonate to 1350 g with deionized, deoxygenated water. From this solution, 1250 g is charged to a 2-liter reactor. The solution is heated to 80° C. After removal of trace oxygen, the reactor is pressurized to 320 psig (2.2 MPa) with a monomer mixture of 35.9 wt % vinylidine fluoride (VF 2 ), 8.3 wt % HFO-1234ze, 50.8 wt % perfluoro(methyl vinyl ether) (PMVE), and 5.0 wt % tetrafluoroethylene (TFE). A 40 ml sample of a 4.0 wt % ammonium persulfate and 9.6 wt.% sodium phosphate dibasic heptahydrate initiator aqueous solution is then added. As the reactor pressure drops, a monomer mixture of 49.3 wt % VF 2 , 3.1 wt % HFO1234ze, 39.4 wt % PMVE and 12.2 wt % TFE is supplied to the reactor to maintain a pressure of 320 psig (2.2 MPa) throughout the polymerization. Additional initiator solution is added to maintain polymerization rate. After a total of 417 g incremental monomer had been fed, monomer addition is discontinued and the reactor is purged of residual monomer. The total reaction time is 2.2 hours. The resulting fluoroelastomer latex has a solids content of 25.4 wt % and a pH of 6.0. The fluoroelastomer latex is coagulated with aluminum potassium sulfate solution, washed with deionized water, and dried. The copolymer has a Tg of −24.1 C and a composition (NMR 1 H and 19 F) in mol % of VF 2 /TFE/1234ze/PMVE=48.9/24.3/24.1/2.7. [0095] The copolymer is compounded, molded into O-rings press and post-cured, followed by compression set testing to demonstrate the function of the 1234ze comonomer in the copolymer as a cure site in the curing process. The cured O-rings exhibit elastomer behavior by being rubbery and by resistance to compression setting. [0096] The copolymer is compounded on a two-roll rubber mill in the proportions (parts by weights) shown in Table 6. Cure characteristics of the compounded compositions are shown in Table 7. [0097] O-rings are made by press curing at 177° C., followed by a post cure under nitrogen at 232° C. for 16 hours. [0000] TABLE 6 Compounded Compositions Batch No. A B Recipe in phr Amount of Copolymer 96.70 100.00 MT Black 30.00 30.00 RCR-6190 2.00 0.00 VC-50 1.30 2.00 bisphenol)-AF 0.00 0.40 Calcium Hydroxide HP-XL 6.00 6.00 magnesium oxide 3.00 3.00 Total 139.00 141.40 Batch Size 139.00 141.40 [0098] RCR 6190 is a mixture of benzyltriphenylphosphonium chloride (34.4 wt %) and bis(phenol)-AF (65.6 wt %). VC-50 is a mixture of 4,4′-[2,2,2-trifluoro-1-(trifluoromethyl-ethylidene]diphenol (about 62 wt %) and benzyltriphenylphosphonium-4,4-[trifluoro-1-trifluoromethyl)ethylidene] diphenol salt (1:1)(about 38 wt %) [0099] Cure characteristics are initially measured using a Monsanto MDR 2000 instrument under the following conditions: Moving die frequency: 1.66 Hz; Oscillation amplitude: ±0.5 degrees Temperature: 165 or 177° C. Duration of test: 30 minutes Tc90: time to 90% of maximum torque, minutes [0105] Compression set of O-ring samples was determined in accordance with ASTM D395-89, 25% deflection for 70 hours at 200° C., 168 hours at 200° C., and 70 hours at 225° C. Mean values are reported in Table 7. [0000] TABLE 7 Compression Set (C/S) Test Results Batch number (A) (B) Compression Set Test Hot Air-70 hr @ 200° C. Avg C/S [A] 56.86 39.71 Median C/S [A] 55.88 39.71 Hot Air-70 hr @ 225° C. Avg C/S [A] 85.71 80.88 Median C/S [A] 85.71 80.88 Hot Air-168 hr @ 200° C. Avg C/S [A] 74.51 66.18 Median C/S [A] 73.53 66.18 [0106] The above test results reveal fluoroelastomer exhibits good elastomer properties arising from the adequate crosslinking density of the cure. The foregoing described procedure for curing, including compounding and molding, is applicable to the fluoroelastomer copolymers of the present invention. Example 24 Fluoroelastomer of 1234zeNF2/PMVE/TFE Copolymer [0107] This fluoroelastomer is prepared by a semi-batch emulsion polymerization process, carried out at 80° C. in a well-stirred reaction vessel. A water solution is prepared by dissolving 1.75 sodium phosphate dibasic heptahydrate and 0.42 g of sodium octyl sulfonate to 1350 g with deionized, deoxygenated water. From this solution, 1250 is charged to a 2-liter reactor. The solution is heated to 80° C. After removal of trace oxygen, the reactor is pressurized to 320 psig (2.2 MPa) with a monomer mixture of 8.1 wt % vinylidine fluoride (VF 2 ), 44.4 wt % HFO1234ze, 44.7 wt % perfluoro methyl vinyl ether (PMVE), and 2.8 wt % tetrafluoroethylene (TFE). A 40 ml sample of a 4.0 wt % ammonium persulfate and 9.6 wt % sodium phosphate dibasic heptahydrate initiator aqueous solution is then added. As the reactor pressure drops, a monomer mixture of 18.9 wt % VF 2 , 34.2 wt % HFO-1234ze, 36.8 wt % PMVE and 10.1 wt % TFE is supplied to the reactor to maintain a pressure of 320 psig (2.2 MPa throughout the polymerization. Additional initiator solution is added to maintain polymerization rate. After a total of 417 g incremental monomer has been fed, monomer addition is discontinued and the reactor is purged of residual monomer. The total reaction time is 13 hours. The resulting fluoroelastomer latex has a solids content of 6.0 wt % and a pH of 3.3. The fluoroelastomer latex is coagulated with aluminum potassium sulfate solution, washed with deionized water, and dried. The copolymer has a Tg of less than 0° C. and a composition (NMR 1 H and 19 F) in mol % of VF 2 /TFE/1234ze/PMVE=33.2/12.9/37.9/16.0. Examples 25 to 28 1234ze/TFENF2 Copolymer [0108] A 400 mL Hastelloy C shaker tube is charged with distilled water (220 mL), Capstone® FS-10 (5.30 g), disodium hydrogen phosphate (1.3 g) and ammonium persulfate (0.16 g), cooled, evacuated and nitrogen flushed. Vinylidene fluoride (3.125 g), tetrafluoroethylene (50 g) and 1,3,3,3-tetrafluoropropene (9.4 g) are then charged to the shaker tube. Vigorous shaking of the shaker tube is started and continued throughout the run. The shaker tube is heated to 70° C. causing the pressure in the autoclave to increase from 260 to 600 psi (1.8 to 4.1 MPa). Shaking and heating are stopped 30 minutes later after pressure has decreased 20% to 480 psi (3.3 MPa). This gives a polymer emulsion that is coagulated by adding 100 ml of saturated aqueous MgSO4 with vigorous stirring. The precipitated polymer is collected by filtration and washed several times with warm water (70° C.). After drying in vacuum oven (100 mmHg) at 80° C. for 24 hours, 30 g of white polymer are obtained. [0109] Polymer Analysis: DSC, 10° C./min, N2, second heat: Tm at 180° C. Composition 19 F NMR (mol %): VF 2 /TFE/1,3,3,3-tetrafluoropropene terpolymer (18/80/2) [0112] The same experimental procedure is applied to Example 26 to 28 and the results are listed in Table 8. [0000] TABLE 8 TFE-1,3,3,3 tetrafluoropropene-VF 2 Terpolymer Example # 25 26 27 28 Material charge DI water g 220 220 220 220 APS g 0.16 0.16 0.16 0.16 Na 2 HPO4.7H 2 O g 1.30 1.30 1.30 1.30 FS-10 g 5.30 5.30 5.30 5.30 VF 2 g 3.13 8.30 15 20 TFE g 50 50 40 20 CF 3 CH═CHF g 9.4 17 45 60 Reaction condition Temp ° C. 70 70 70 70 Init Pressure MPa 4.1 3.9 3.5 2.8 Final Pressure MPa 3.3 3.1 2.8 2.2 time for P drop min 30 30 45 60 Product Polymer g 30 25 20 25 Thermal data Tm ° C. 262 210 144 73 5 wt % loss of ° C. 389 362 350 344 Polymer in air Polymer composition by 19 F NMR VF 2 mol % 18 38 48 50 TFE mol % 80 58 44 22 CF 3 CH═CHF mol % 2 4 8 18 [0113] The copolymers are insoluble in hydrocarbon solvents, including DMF and DMAC heated to 75 to 100° C. Examples 29 to 32 1234ze/TFE/ethylene Copolymer [0114] A 400 mL Hastelloy C shaker tube is charged with distilled water (220 mL), Capstone® FS-10 (5.30 g), disodium hydrogen phosphate (1.3 g) and ammonium persulfate (0.16 g), cooled, evacuated and nitrogen flushed. Ethylene (3.125 g), tetrafluoroethylene (50 g) and 1,3,3,3-tetrafluoropropene (9.4 g) are then charged to the shaker tube. Vigorous shaking of the shaker tube is started and continued throughout the run. The shaker tube is heated to 70° C. causing the pressure in the autoclave to increase from 260 to 764 psi (1.8 to 5.1 MPa). Shaking and heating are stopped 60 minutes later after pressure has decreased 20% to 321 psi (4.1 MPa). This gives a polymer emulsion that is coagulated by adding 100 ml of saturated aqueous MgSO4 with vigorous stirring. The precipitated polymer is collected by filtration and washed several times with warm water (70° C.). After drying in vacuum oven (100 mmHg) at 80° C. for 24 hours, 20 g of white polymer are obtained. [0115] Polymer Analysis: DSC, 10° C./min, N2, second heat: Tm at 200° C. Composition 19F NMR (mol %): TFE/1,3,3,3-tetrafluoropropene/ethylene terpolymer (3/94/3) [0118] The same experimental procedure is applied to Example 30 to 32 and the results are listed in Table 9. [0000] TABLE 9 TFE-1,3,3,3 tetrafluoropropene-Ethylene Terpolymer Example # 29 30 31 32 Material charge DI water g 220 220 220 220 APS g 0.16 0.16 0.16 0.16 Na 2 HPO4.7H 2 O g 1.30 1.30 1.30 1.30 FS-10 g 5.30 5.30 5.30 5.30 TFE g 50 50 40 20 CF 3 CH═CHF g 9.4 17 45 60 Ethylene g 3.13 8.3 15 20 Reaction condition Temp ° C. 70 70 70 70 Init pressure MPa 5.1 4.9 4.5 3.8 final pressure MPa 4.08 3.1 2.8 2.2 Time min 200 300 450 600 Product Polymer g 20 15 15 10 Thermal data Tg ° C. 130 90 Tm ° C. 200 180 5 wt % loss of ° C. 300 280 250 200 polymer in air Polymer composition by 19 F NMR TFE mol % 94 85 75 65 CF 3 CH═CHF mol % 3 9 15 20 Ethylene mol % 3 6 10 15 [0119] The copolymers 29 and 30 exhibit crystallinity (Tm, but no Tg), and the copolymers of Examples 31 and 32 are amorphous (no Tm, but have Tg) and can be melt formed into films that can be used for coating substrates. [0120] When the combination of 1234ze and ethylene increases from 15 mol % (Example 30) to 25 mol % (Example 31), the resultant copolymers change from exhibiting crystallinity to being amorphous. Most of this change is attributed to the presence of the 1234ze because of its greater molecular size than the ethylene. Preferably, the combination of 1234ze and ethylene in the1234ze/TFE/ethylene copolymer and the 1234ze/TFE/HFP/ethylene copolymer is at least 20 mol % to obtain the copolymer in the amorphous state. Example 33 CTFE/ethylene/1234ze Copolymer [0121] A 1 L autoclave is charged with distilled deoxygenated water (500 mL), Capstone® FS-10 (5.30 g), disodium hydrogen phosphate (1.3 g) and ammonium persulfate (0.16 g), cooled, evacuated and nitrogen flushed. Ethylene (40 g), CTFE (200 g) and 1,3,3,3 tetrafluoropropene (3 g) are then charged to the autoclave at 0° C. The autoclave is stirred and heated to 70° C. for 2 hours. This gives a polymer emulsion that is coagulated by adding 150 ml of saturated aqueous MgSO4 with vigorous stirring. The precipitated polymer is collected by filtration and washed several times with warm water (70° C.). After drying in vacuum oven (100 mmHg) at 80° C. for 24 hours, 25 g of white polymer are obtained. [0122] DSC, 10° C./min, N2, second heat: Tm at 241° C. [0123] Composition 19 F NMR (mol %): Ethylene/CTFE/1, 3,3,3 tetrafluoropropene terpolymer (47/51/2)

The present invention provides 1,3,3,3-tetrafluoropropene (HFO-1234 ze ) copolymers comprising 1,3,3,3-tetrafluoropropene and one or more comonomers selected from the group consisting of vinyl fluoride (VF), vinylidene fluoride (VF 2 ), tetrafluoroethylene (TFE), chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), and perfluoro(alkyl vinyl ether) (PAVE), wherein said alkyl contains 1 to 5 carbon atoms, the copolymers being a fluoroplastic or a fluoroelastomer, depending upon monomer content.

This application claims the benefit of provisional patent application No. 60/691,158 file date Jun. 17, 2005 TECHNICAL FIELD OF THE INVENTION This invention pertains directly to the field of interference lithography and nanotechnology. However, the invention can be applied to any situation where a large area needs to be seamlessly tiled with a smaller base pattern by any of a multitude of pattern exposure or impression mechanisms. BACKGROUND OF THE INVENTION Nano structured and micro structured surfaces have been investigated for many years in terms of the special functional properties that can be achieved. For example, surfaces made up of many small “protuberances”, such as closely and regularly spaced cones, at the micron or sub-micron scale, can exhibit self-cleaning as well as near omni-directional and polarization insensitive anti-reflective properties at optical wavelengths. When features are on the nanometer scale, such so-called “Motheye” nanotextured surface treatments can be ideal anti-glare treatments for display applications. The anti-glare properties can be superior to any other bulk or multi-layered material film approach. A number of examples of such nanometer scale structures or “nanotextures” are illustrated in FIG. 1 a . The linear 2-D relief grating is typically used for Bragg grating applications. This particular one was used to realize tight 90 degree bends in integrated optic wave guides 1 . The negative index structure has the potential for realizing flat lenses, and is currently a popular research topic 2 . The “Motheye” and SWS (“Subwavelength structures”) are both used for anti-reflective applications 3 , with Motheye being a much more broadband treatment 4 . The “black hole” structure is used for light trapping applications, but could also be used as a highly efficient field emitter array, such as for backlight or plasma display applications. Currently, such nanometer scale periodic structures are typically created by using optical beam interference lithography. The issue now is that useful coherent pattern sizes are typically limited to a few inches, creating a barrier to commercial application of these nanotechnologies. What is needed now is a readily scalable coherent nanotextured surface treatment technology. Such a technology could be immediately used in Motheye anti-glare and smudge resistant treatments for the plethora of display devices and windows available in the consumer and industrial markets. These include but are not limited to personal digital assistants, cell phones, portable game devices, laptop computer displays, television screens, and automobile and store-front windows. An approach to realizing larger form factor nanotextured surfaces at the exposure level can be considered. One series of inventions taught by Hobbes 5 and Kelsey, et al. 6 describe the use of optical fiber delivery of the exposure beams to increase the coherent interference pattern size and uniformity in the far field recording (exposure) plane. It can be surmised that due to the divergence of the optical beam from an optical fiber, larger pattern size could be achieved by simply increasing the distance between the optical fiber tip and the exposure region. However, this has practical limitations, as larger distances will incur more pointing and vibration sensitivity, as well as wave front phase randomization, all of which will tend to wash out the developed exposure pattern. The other issue is that the exposure intensity is reduced rapidly in a square law sense as the distance is increased, leading to increased exposure times. As an example, an increase in diameter coverage by a factor two incurs an exposure time increase of a factor four. Longer exposure times lead to more washing out of the interference pattern exposure due to vibrations, mechanical, and other drifts. Another approach to realizing large area micro and nano textured surfaces has been to mechanically stitch together the nanotextured surfaces, either at the master stamp level shown in FIG. 2 , or at the product level as shown in FIG. 3 . At the master level, many smaller sub-master stamps are bonded together to form a larger master stamp. At the product level, a single smaller master is used to “stamp and repeat” a product film or substrate to cover a larger area. Although there may be some exceptions for certain applications, the vast majority of display applications would require perfect (seamless) stitching, as the human eye is very capable of discerning stitch errors at the microscopic scale. This is due mostly to discontinuous phase boundaries and stitch related defects. Due to practical tolerance issues, such mechanical tiling inherently results in large stitching errors in all 3 dimensions (x, y, and z) when applied to micro and nanometer scale textures. At best, such errors would result in cosmetic and performance reduction in display anti-glare treatments. At worst, such errors make these mechanical approaches completely useless for large area coherent diffraction elements. A third approach to scaling up these nanotextures combines the optical and mechanical approaches. This approach stitches or otherwise blends together many smaller uniform patterns at the exposure phase to create a larger area coherent pattern. This has been achieved to some degree by researchers at MIT, using what they call “scanning beam interference lithography” 7 . In that patented work 8 , large area linear grating patterns were reportedly achieved by scanning the position of a photoresist coated substrate under the fluence of two interfering 1 to 2 mm diameter Gaussian beams. The smaller base interference pattern was thus a simple linear fringe pattern. Positioning of the substrate was reportedly kept on track by feedback from a highly sophisticated optical metrology apparatus. Reportedly, there was some success in fabricating linear gratings (arrays of 400 nm spaced lines) on 300 mm diameter wafers 9 . However, the apparatus was quite complex, as can be discerned from the lengthy 99 page patent document. This was likely because position control and grating coherence relied on feedback from a fixed reference “fiducial” grating as opposed to locking on to actual previous exposures. Any drift in the fiducial during the scanning process would result in stitch error. Also, note that the 1 mm exposure size would result in very slow process times for large area coverage. Finally, although the 400 nm spacing may be suitable for near infrared applications, it is not sufficient for the less than 200 nm feature sizes required for visible (e.g. display) applications. Also, as the method taught is a scanning approach, it is not amenable to larger area stamp and repeat coherent coverage of more complex 3-D nanotexture patterns, such as Motheye. McCoy teaches a stitching related invention in a 1995 patent that addresses the intensity profile needed in the tile overlap regions to ensure an overall uniform dosage 10 . This somewhat obvious method of achieving spatially uniform dosage has also been used by Schattenburg, et al. in their scanning beam interference lithography invention 8 . There is no reference in McCoy's invention as to how the fine structures of the base pattern would be stitched or mesh aligned. To date, there has been no report of a method by which to perform seamless stitch tiling of nanometer scale patterns to large areas. SUMMARY OF THE INVENTION This patent disclosure describes several approaches to implementation of optical feedback and positioning for stitch alignment of nanometer and micrometer scale patterns formed by methods such as interference lithography. Due to the regularity and periodicity of the step-and-repeat tiled patterns at their boundaries, adjacent exposures can be stitch aligned by observing the pattern optical transmissions, or other suitable signals, in the pattern overlap regions. In this fashion, each new exposure is locked onto a previous exposure. Such stitch tiling can be extended to cover arbitrarily large areas with a smaller base pattern. In an exemplary embodiment of the disclosed invention, the bleaching effect of photoresist or other photosensitive layer or layers is exploited to form a stitch alignment transmission mask for each new pattern exposure. In another embodiment, a special registration layer serves for alignment of each new exposure pattern to a previously exposed pattern. For interference lithography, in addition to a conventional piezo based, or other hi resolution mechanical positioning method, a high speed optical modulation method is taught which can be used for fine stitch alignment of the base pattern once it is roughly positioned by mechanical, or other means. BRIEF DESCRIPTION OF THE DRAWINGS For a more complete understanding of the present invention and its advantages, reference is now made to the following description taken in conjunction with the accompanying figures in which like reference numbers indicate like features and wherein: FIG. 1 is a collection of high resolution photos of example nanometer and micrometer scale periodic structures that may scale to large coherent areas through application of the present invention; FIG. 2 is an illustration of generating a larger master stamp by tile stitching of smaller stamps by mechanical means, with details of the inherent stitch errors; FIG. 3 is a pictorial representation of a mechanical stamp and repeat tiling scheme or stitching at the product fabrication level; FIG. 4 is an illustration of an exemplary embodiment of the present invention as applied to overlap tiling and stitching of circular, Gaussian profile exposure patterns that comprise fine periodic features on the nanometer scale; FIG. 5 illustrates the self masking mechanism in accordance with an exemplary embodiment of the present invention as applied to exposure level stitching of patterns in a medium to high contrast photosensitive layer or layers; FIG. 6 is a graphical representation of the response behavior of a typical photosensitive material (photoresist) to exposure dosage; FIG. 7 illustrates the use of contrast enhancing material layer or layers in the self masking mechanism in accordance with a modification of an exemplary embodiment of the present invention as applied to exposure level stitching of patterns in a low contrast photosensitive layer or layers; FIG. 8 is a flow diagram of the operation of a stitch alignment and exposure state machine in accordance with an exemplary embodiment of the present invention; FIG. 9 is a graphical representation of an example of the optical transmission behavior of a typical photoresist as it undergoes full fluence from an exposure source; FIG. 10 is a diagram of a complete tile and stitch alignment and exposure machine implemented for stitching patterns formed by two beam interference lithography in an exemplary embodiment of the present invention; FIG. 11 is a detailed diagram of an embodiment of an optical transmission signal sensor apparatus in accordance with the machine of FIG. 10 ; FIG. 12 is a detailed diagram of an exemplary embodiment of the transmission signal sensor apparatus in accordance with the machine of FIG. 10 , whereby a secondary image registration layer is implemented to confine the transmission signal to a well defined plane; FIG. 13 is a detailed diagram of the secondary image registration layer referred to in FIG. 12 ; FIG. 14 illustrates an example of the use of the transmitted alignment signal image map to achieve bipolar servo control for rapid or continuous stitch alignment before or during full exposure conditions; DETAILED DESCRIPTION OF THE INVENTION The current invention pertains to a novel, simple, and cost effective method to seamlessly tile and stitch regular surface textures, such as those with periodic nanometer scale features, at the exposure level of the fabrication process. An example of exposure level tile stitching of patterns in accordance with an exemplary embodiment of the present invention is shown in FIG. 4 . Exposure pattern 102 may be generated by any of a number of ways, such as through interference by a plurality of monochromatic beams. Post exposures 105 represent impression of base pattern 102 at a plurality of partially overlapping tiled positions. The impression is manifested in the form of a transmission mask, or some other permanent or semi-permanent effect in the surface being exposed that can be used to register the post exposure pattern fine position relative to the new exposure pattern 102 position. Corresponding zoom view details are shown for base pattern 103 and for post-exposures 104 , and for an overlap region 100 . Here, due to the fine feature regularity of the base pattern 103 , the pre-exposure pattern 102 can be seamlessly tiled by overlapping and meshing with post-exposure patterns 105 through some form of alignment error feedback signal. It is this alignment between base exposure pattern 102 and post-exposures 105 in the overlap regions such as 107 and 106 which represents the essence of the present invention. That is, that the new exposures are aligned directly with previous exposures. According to previous disclosures 10,8 , the overall exposure pattern intensity profile is modified at the boundaries where stitching overlap occurs so as to ensure a more spatially uniform exposure dosage. In the figure, a Gaussian profile 101 is used as an example. This is the default profile for a free space beam of radiation, and also results in a highly regular wave front both in phase and in intensity. Stitched pattern exposure separations are appropriately chosen to yield the most spatially uniform dosage profile. To mesh perfectly (no stitch error), some form of alignment feedback must be implemented for the overlapping region between pre and post exposures. Also, positioning of the pattern at the nanometer scale must be implemented. A number of embodiments for the feedback are emphasized in this disclosure. In the specific case where patterns are formed through interference lithography, an alignment positioning invention by exposure beam differential phase control is also described. 1. Alignment Feedback via Self-Generated Transmission Mask (Self Masking) For most photosensitive materials used in lithography, the absorption of the photo-resist undergoes a permanent change after exposure. In positive photo-resist, this is called “bleaching” and can result in a much higher photo-resist optical transmission after exposure. The exposed pattern itself can thus serve as a pattern overlap alignment mask for an adjacent exposure light pattern. When the new exposure pattern is aligned to the previous exposure (mask), it will show up as a strong transmitted light signal in the pattern overlap region. It then becomes simply a matter of positioning the substrate and/or pattern to maximize this transmitted light in order to seamlessly “stitch” align the adjacent pre-exposure pattern with the already post exposed pattern. Applying this to the illustration of FIG. 4 , one can see that the lighter features in the post exposure zoom view 104 represent windows of higher optical transmission. In the overlap alignment region such as in the zoom view 100 , one can see that maximum transmission of the exposure pattern 102 will occur when it is aligned with the exposed features of the post exposure pattern. FIG. 5 is an illustration detailing an exemplary embodiment of stitch alignment feedback in the present invention. In this embodiment, each full exposure 111 and 119 inherently creates a transmission alignment mask via the photo-bleaching properties of the photosensitive layer or layers. An appropriate photo-resist layer (or layers) 112 is applied to a suitably optically transparent substrate 113 . After exposure of the base tile pattern 111 to create transmission mask 114 in the photoresist 112 , adjacent tiled pre-exposure patterns 116 are roughly positioned to partially overlap the previous exposure in region 115 in such a way that the eventual total exposure dosage will be uniform across both exposure patterns. During this coarse positioning, the pre-exposure pattern 116 can be significantly reduced in dosage (E<<Eo) relative to the full exposure (E>>Eo) case, so as not to prematurely bleach, or otherwise expose the photoresist 112 until the alignment condition has been achieved. Adjusting this pre-exposure pattern 116 fine position and maximizing the transmitted signal 117 from the pattern overlap region 115 signifies the alignment condition, and a full exposure 119 is applied. Note that dosage, in the context of this invention disclosure, refers to any combination of average exposure energy, intensity, and time of the exposure pattern. Any pre-exposure effects can be further reduced by using high contrast photoresists or contrast enhancement layers. That is, there is a sharp non-linear increase in photoresist exposure after a certain threshold exposure dosage Eo is reached. Any integrated exposure or dosage below this value has negligible effect on the final developed pattern. Hereinafter, this, or other variations of this alignment feedback scheme, are referred to as “self-masking” stitch alignment. Once stitch alignments and exposures are completed, a plurality of seamlessly tiled patterns are thus impressed in a uniform dosage 120 in the photoresist 112 . This uniformity of dosage 141 stems from the use of graded intensity exposure patterns 130 and 139 . The exposed photoresist layer or layers 112 can then be further processed by development techniques to yield the textured surface 122 . In many cases, the follow-up process will involve using this developed pattern as an etch mask to transfer the pattern to the substrate 113 . Although the embodiments described thus far represent application of the invention to more two-dimensional nanometer scale surface textures, the self-masking described in the present invention may be applied to stitching of more general three dimensional patterns with periodic boundaries, such as those that could be formed by holography, without violating the spirit of the invention. Such exposure schemes can be used to create three-dimensional photonic band gap structures. For example, interference lithography could be used to create a three-dimensional nanometer scale periodic exposure pattern in a thick layer or volume of photosensitive material. In one embodiment of the stitch alignment invention, overlap region transmission of adjacent 3-D exposures would again be used as the alignment signal. X, Y, and Z (as needed) would be adjusted to maximize the transmitted signal and achieve stitch alignment. Although the embodiment described thus far specifies transmission of the overlap signal through a suitably transparent substrate, it will be obvious to those skilled in the art that, given a suitably reflecting substrate, the reflected light pattern will also correlate with the stitch alignment error magnitude. This modification, and others like it, does not violate the spirit of this invention. 2. Self-Masking Alignment Feedback with Commercial Photoresists A. Photosensitive Layer Selection Commercial photoresists typically undergo changes in absorption coefficient due to bleaching during and after exposure. This “contrast” in absorption before and after exposure shows up in the so called “Dill” parameters for the resist, so named after the researcher that defined them in a landmark 1975 paper 11 . The complete set of Dill parameters, along with typical units are: A = 1 d ⁢ Log ⁡ [ T ⁡ ( ∞ ) T ⁡ ( 0 ) ] ⁢ ⁢ ( μ ⁢ ⁢ m - 1 ) ( 1 ) B = - 1 d ⁢ Log ⁡ [ T ⁡ ( ∞ ) ] ⁢ ⁢ ( μm - 1 ) ( 2 ) C = A + B AI 0 ⁢ T ⁡ ( 0 ) ⁢ { 1 - T ⁡ ( 0 ) } ⁢ ⅆ T ⁡ ( 0 ) ⅆ t ⁢ ⁢ ( mJ ⁢ / ⁢ cm 2 ) - 1 ( 3 ) As can be seen, the “A” parameter is a direct measure of the contrast, or change in transmission before and after exposure, while “B” represents the transparency (bleaching amount) after full exposure. Multiplying A by the film thickness will give the Log ratio change in transmission after exposure. Values of A for high contrast resists are between 1 and 2, which means the transmission of 1 μm unexposed films can be from 1/10 to 1/100 that of exposed films. As an example, Clariant AZ® HiR™ series i-line photoresist publishes a “k” absorbing value of refractive index change from 0.031 before exposure to 0.0009 after exposure to 405 nm light. Using T = ⅇ - 2 ⁢ α · d = ⅇ - 4 ⁢ π λ ⁢ k · d ( 4 ) and λ=405 nm, d=film thickness=0.5 μm or 500 nm, then optical power transmission (T) will change from 62% before exposure, to 99% after exposure (not including Fresnel reflection loss of about 6% per air/resist interface for this particular resist). Such a change in transmission clearly can be used as an alignment signal. B. The Alignment Time Window High contrast photoresists are typified by the response shown in FIG. 6 . In this example of the popular Shipley™ 1800 series photoresist, there is a very clear threshold behavior of developed resist versus exposure dose (combination of exposure energy, intensity, and time). It is this threshold behavior signified by Eo and related contrast parameter for the resist that affords the time needed to perform the alignment step. During the stitch alignment steps, as long as net exposure dosage is kept well below the Eo threshold, there will be no significant photoresist removal during the development step. It is only after the stitch alignment is locked that the dosage is increased to achieve full exposure and subsequent development. C. Contrast Enhancement Films For some cases, the final developed photoresist pattern itself can serve as the actual nanostructured surface for replication. This is often the case for Motheye films, where interference lithography and a lower contrast resist will incur a more sinusoidal pattern to the developed features as shown in the Motheye structure of FIG. 1 . In these cases, the photo bleaching effect of the photoresist is smaller, and self masking in the photoresist may be problematic, or otherwise impractical. For such low contrast photoresist applications, a contrast enhancing material (CEM) film can be applied on top of the photoresist. Such materials are available commercially from Shin-Etsu MicroSi™ and are specifically designed for “aerial” image (i.e. non-contact) exposure applications such as interference and projection lithography 12,13 . FIG. 7 is an illustration representing an exemplary embodiment of the modified stitch alignment invention using a contrast enhancing film 134 deposited on top of the photoresist 133 which is in turn deposited on a suitably transparent substrate 132 . As shown in the figure, after the exposure stitching is complete, the CEM film is simply removed. The detailed explanation for FIG. 7 follows that for FIG. 5 , with the exception that the resist development results in a sinusoidal like profile nanostructured surface 142 , suitable for direct transfer to a master stamp. Typically, this transfer process entails deposition of a thin layer of metal, such as gold. Thick Nickel plating can then be used to build up a rigid over layer that can then be transferred to a rigid back plate. Photoresist stripping then yields the rugged Nickel “shim” negative of the original photoresist structure, which can then be used to mass replicate the nanotexture by any of various molding processes. Although targeted for stitching of exposure patterns in low contrast photoresists, such CEM films may be used to increase the self-masking alignment signal strength for any photoresist selection. 3. Processing of the Self Masking Alignment Feedback Signal The previous section detailed how the photosensitive layer becomes an optical alignment mask for an adjacent exposure. This section will detail how this mask is used to perform the actual stitch alignment. FIG. 8 features flow diagrams that illustrate processing of the optical alignment feedback signal in accordance with an exemplary embodiment of the present invention. In the figure, once the process is started, the relative coarse position of the substrate relative to the first exposure is set 150 . The exposure level is switched on at a pre-exposure (alignment) level 151 . The fine position of the pattern relative to the substrate is then dither scanned over distances suitable for ascertaining the position at peak feedback signal 152 . Typically, this scan distance will be 1.5 times the period of the fine structure features so as to ensure capture of a significant portion of the feedback signal peak in the feedback time domain waveform. Once the maximum feedback signal is located, the position is locked to this condition 153 . A full exposure process then takes place 154 , which actually consists of a subroutine that periodically checks and corrects the alignment against thermal and other drifts during the course of the full exposure step 154 . As shown in the figure, the full exposure starts with a full exposure energy and intensity level for a prescribed time “n” time in block 154 a . The first time passing through the decision block 154 b , the full exposure condition will typically not yet be met. The alignment is then checked and corrected as necessary in blocks 154 c , 154 d , and 154 e . The process then loops back to the full exposure level for another time period “n” in block 154 a . This looping will continue until the integrated dosage for full exposure has been met. Inputs to this block 154 include interval n as well as a loop count. The loop count is equal to the total dosage time for maximum exposure divided by the exposure time interval n. A. The Alignment “Search” Window At first look, the dose threshold behavior of FIG. 6 would seem to imply that there is a substantial window of time (dosage=intensity×time) to perform alignment. After all, typical photoresist exposure times for interference lithography are typically in the 30 to 60 second regime. By attenuating the UV source 10 dB during the alignment step, the window before threshold exposure occurs could be extended by 10 times to over 300 seconds (5 minutes). By using a lock-in amplifier to modulate and collect the alignment feedback signal, the duty cycle could also be used to directly reduce the average intensity of the beam during alignment. However, it is important to recognize that each overlap alignment area will undergo pre-exposure dithering at least twice: once before it is first fully exposed, and again for the adjacent exposure. Thus, the actual time window to perform alignment is half what is indicated by the photoresist contrast curve. B. Transmission “Leakage” and Position Search “Dithering” It is important to understand that under any exposure level, as long as the photon energy is sufficient, then there will be some bleaching of the resist. The rate of bleaching will be determined by the exposure wavelength and intensity. The bleaching depth profile at a specific intensity, photon energy, and time will depend on the specific resist being used. The net effect is that a typical photoresist film will continuously increase in transmission during any level of exposure. A sample of a common photoresist film (AZ1350) transmission increasing over time under full exposure conditions is given in FIG. 9 11 . The high slope region 160 of the curve 162 represents the approximate pre-exposure time window Δt whereby the dosage has not yet reached the Eo threshold value indicated in FIG. 6 . This slope and saturation of transmission over exposure time eventually results in the ΔT total change in transmission 161 . It is apparent that even a low average intensity pre-exposure transmission stitch alignment signal will change with time due to this steady “leakage” exposure within the dosage window 160 . The significance of this is that the optical alignment feedback loop will need to be capable of masking out this leakage and drift component. In an exemplary embodiment of the present invention, a simple way to mask the transmission leakage signal is implemented by “AC coupling” the transmission signal beyond the maximum transmission leakage ramp rate. Dithering of pattern position at a higher frequency is done to search for the aligned position. The AC coupling is configured to filter out just the dither frequency components in the transmission signal. Peaks in the transmission vs. position sweep represent alignment along the dithering position axis. If a 2-D pattern must be aligned, both x and y will be dithered sequentially and iteratively to get maximum alignment. If necessary, another alignment axis may be theta or rotation of the pattern. All axes need to be aligned sequentially and iteratively to achieve the optimal alignment for all overlap regions and thus seamless tiling of the patterns. C. Alignment Mechanism and Procedure Up to now, it has been taken for granted that position of the substrate relative to the exposure pattern (or vice versa) can be freely and smoothly controlled, and is stable during the full exposure step. In fact, when feature spacings are on order of 100 nm, and tolerances are in the 5 to 10 nm regime, this is not a trivial task. As illustrated in the preferred embodiment of feedback processing in FIG. 8 , a coarse positioning mechanical stage steps the substrate (recording plane) to the approximate step and repeat pattern stitch positions. Then, a fine high speed positioning control is dithered to locate and lock the pre-exposure pattern to the previous exposed pattern in the overlap region. The fine “nano” positioning travel only need be in the range of the feature period itself in order to be able lock an adjacent pre-exposure pattern to an exposed (self-mask) pattern. Dithering position over two or more feature periods will ensure that an entire transmission maximum will be captured during any sweep. FIG. 10 illustrates an exemplary embodiment of the present invention when applied to stitching of linear grating fringe patterns formed by two beam interference lithography. In the figure, the exposure source radiation from 170 is coupled into single mode polarization preserving optical fiber 175 by 174 after being processed by the beam chopping and attenuation unit 172 . The beam chopping is engaged during lock-in amplifier operation to reduce feedback signal noise stemming both from ambient light and from the transmission photo-detector and sensor electronics. The attenuation function controls the beam intensity for switching from pre-exposure to full exposure intensity conditions. Once the radiation is in the optical fiber 175 , it is inserted into a fiber optic splitter and differential phase controller 176 . This unit splits the light into two beams, and a phase control signal is applied to adjust and lock the relative optical phase between the two beams. This differential phase controls the spatial phase of the fine pattern features in interference pattern 184 . The two beams are then delivered over single mode optical fibers 178 and 179 to the collimating or focusing optics 180 and 181 . The single mode optical fibers 178 and 179 result in high quality single mode Gaussian beams being delivered to the recording (wafer) plane 185 via suitable high quality collimating optics 180 and 181 . Beam shaping optics may be integrated into 180 and 181 , provided the interference pattern 184 is still regular and periodic enough to allow seamless (or near seamless) overlap in the tile overlap regions. In a preferred embodiment of the present invention, collimating optics 180 and 181 are designed and positioned to achieve cylindrical beam waists at the interference pattern 184 in recording surface 185 . This will give a uniform and well defined wave front intensity and phase over a well defined elliptically shaped exposure interference pattern 184 for both beams. Both beams 182 and 183 can then completely overlap. This is important for achieving homogenous interference patterns 184 that can thus be stitch tiled by the present invention. As shown in FIG. 10 , one of two high speed fine position adjustment mechanisms are used during the stitch alignment positioning (dithering) step. The piezo translation control 187 is well known and serves as the conventional mechanical approach. The optical phase control 177 is unique to interference lithography in that the differential phase between the two beams can be controlled to adjust the fringe period positions. Differential phase sweep (dithering) over 180 degrees or more will ensure capture of the maximum alignment feedback signal during the fine position scanning sweep. Ability to control phase over at least 270 degrees will ensure that the alignment peak transmission can be set to the center of the 180 degree phase control sweep through DC bias offset control level. The operation of the exemplary embodiment of the present invention illustrated in FIG. 10 is based on the feedback signal processing embodiment described in FIG. 8 . The computer 192 represents the sequential state machine that enables automation of the tile stitch align and repeat process of FIG. 8 . Computer 192 processes the transmission stitch alignment feedback image signal 190 directly and analog sensor signal 191 via lock-in amplifier output 194 or via digital interface 196 such as by general purpose interface buss (GPIB). The detailed operation steps are as follows: 1. For the first exposure, since there is no other pattern to lock on to, the only requirement is that exposure pattern 184 must be relatively stable enough to generate a “seed” transmission alignment mask pattern. Even if the feature contrast is lower for this first exposure, adjacent stitched patterns will quickly improve, as they are phase locked on to previous exposures. 2. The beam 171 is then blocked or sufficiently attenuated by 192 via control 201 of attenuator 172 after each full exposure step before indexing to the next tile position. 3. The mechanical stages 185 and 187 are controlled by computer 192 stepper control 188 of x and y coarse position of recording plane 185 for the next exposure pattern to be tile stitched. 4. The pre-exposure intensity level is engaged via computer 192 control 201 of attenuator 172 . Computer 192 enables lock-in amplifier 193 via digital interface 196 to lock on to analog optical transmission signal 191 modulated by beam modulation in 172 and sensed by sensor 189 . 5. The fine nanometer scale position adjustment (piezo 187 or optical phase 177 ) is then dithered (scanned) by computer 192 control 197 of the gate of sweep generator 199 . 6. Computer 192 captures analog signal 191 over dither scan window time via analog output 194 or digital interface 196 from lock-in amplifier 193 . The captured waveform is used to locate and lock the pre-exposure pattern 184 fringe phase (by phase control 177 ) or table position (by piezo control 187 of mechanical stages 186 and 187 ) to the alignment position indicated by the feedback signal 191 peak level position. This bias level is set by the computer 192 via bias control 198 of sweep generator 199 . Note that fine position bias levels for x 186 , y 187 , and theta 202 (if applicable) axes are iteratively aligned until the absolute maximum feedback signal is achieved. In these cases, a plurality of bias 198 , sweep gate control 197 must be implemented to accommodate the plurality of alignment axes. In the two beam interference embodiment of FIG. 10 , since the interference pattern 184 is a linear grating pattern oriented in line with the y axis, the single x axis fine alignment is sufficient provided the yaw or linearity of the x and y stages over their translation ranges meets a prescribed tolerance. 7. The dither sweep is then switched off by computer 192 via gate control 197 of sweep generator 199 . The bias level control 198 level set in step 6 is maintained by computer 192 to maintain the current stitch aligned condition. 8. The computer 192 switches the attenuator 172 to full exposure condition via control 201 . 9. As full exposure proceeds, the fine alignment is periodically checked and corrected to guard against any thermal induced or other position drifts that could smear the stitched pattern. Steps 4 through 8 are repeated for each alignment check until full exposure dosage occurs. Note that alignment may also be checked under full exposure conditions if the alignment check process is rapid enough. 10. Go to step 2 and repeat until all patterns are stitched FIG. 11 illustrates a preferred embodiment of the alignment sensor feedback unit 189 for the present invention. Here, the sensor optics consists of an objective lens 225 aligned to image a small circular region 224 of the recording plane within the stitch alignment (overlap) region of post exposure pattern 222 and the current pre-exposure pattern 223 . An “f-stop” may be used to capture only light within a specific cone angle from this circular region. Note that the objective lens 225 need not be capable of resolving the fine structure of the interference pattern, only the overall intensity map and level. A beam splitting prism 227 or other beam splitting device is then used to split off a portion of the imaged intensity profile 226 for high sensitivity analog transmission feedback signal sensing using a photo-detector 228 . The remaining portion passes through prism 227 to fall on an imaging device 229 , such as a CCD camera. The imaging device 229 captures the relative intensity map while detector 228 more accurately captures the total transmitted optical power. In an exemplary embodiment of the present invention, this image information is used to determine the stitch position error sign so as to generate a true bipolar servo stitch alignment feedback signal. This embodiment is illustrated in FIG. 14 . In the figure, a plurality of monochromatic beams 270 is used to create the interference pattern 271 on the substrate recording plane 272 . Imaging the optical transmission of the pattern in the overlap region by an objective lens 273 will result in various intensity map profiles depending on the degree of stitch or mesh alignment along linear 186 and 187 and angular (yaw) 202 axes of FIG. 10 . The figure presents examples of image profiles for a misaligned case 276 and for a properly stitch aligned case 275 along all axes. Image processing 277 and pattern or substrate control 278 is implemented in the computer 192 of FIG. 10 . With such a more direct stitch alignment feedback, alignments can be completed more rapidly than with the analog dither approach described in previous embodiments. This alignment can also be checked and corrected under full exposure conditions. In such a case, an attenuator or other gain control of the imaging device may be implemented to avoid image saturation effects. It will be obvious to those skilled in the art that the transmitted image processing approach just described for determining stitch alignment error polarity can be readily extended to reflected image processing, given a suitably reflecting substrate. These, and other modifications like it, may be employed without violating the spirit of this invention. In a preferred embodiment in accordance with the present invention, a secondary image registration plane, such as consisting of a transparent slide with a frosted surface, or other image plane registration device may be used in place of direct imaging of the overlap regions in the substrate recording plane. Such a modification can alleviate interference and “speckle” effects in the transmitted optical intensity map, and can lead to a more consistent stitch alignment signal reading. FIG. 12 illustrates an exemplary embodiment of such a registration plane in accordance with the present invention. Here, all components common to the configuration of FIG. 11 serve the same functions. The difference is that the objective lens 247 in this case is chosen to image a region of the secondary image registration plane 246 spaced at some distance 245 from the primary recording plane containing impressed post exposure pattern 243 and pre-exposure pattern 242 . Item FIG. 13 is a more detailed illustration of this secondary recording plane in accordance with an exemplary embodiment of the present invention. Here, 265 of FIG. 13 represent detail of the secondary image registration plane 246 of FIG. 12 . In FIG. 13 , the image registration plane 265 has upon it a spatial optical filter or other f-stop device so as to limit the registered image to an aperture 262 that only contains interference pattern light 261 from interference volume 260 . Objective lens 264 is chosen and positioned so as to image a smaller aperture field 263 of this overall interference pattern contained within the spatial filter aperture 262 . It will be obvious to those skilled in the art that a general plurality of interfering beams may be employed to generate the interference patterns referred to in all the embodiments described thus far and to the invention illustrated by FIG. 10 . The description thus far is to serve as an exemplary example of overlap stitch alignment of interference patterns. For a plurality of beams beyond the two described here, a corresponding plurality of beam controls is implied without violating the spirit of this invention. It will also be obvious to those skilled in the art that although the embodiments described thus far apply directly to the field of interference lithography, other pattern impression mechanisms may also be employed without violating the spirit of this invention. These include, but are not limited to, electron beam, x-ray, radio, or any other radiation source that is used to generate a pattern that is to be tiled and stitch aligned. It will also be obvious to those skilled in the art that the transmission feedback signal described thus far for the present invention can be extended to include other stitch alignment signals, including, but not limited to, reflection or diffraction, without violating the spirit of the present invention. A fundamental aspect of the present invention is that each pattern impression, by itself, creates a stitch alignment fiducial or reference for subsequent pattern impressions. In this way, stitch errors are minimized relative to approaches that use a separate external reference. In this respect, there is no restriction on the overlap condition. In the embodiments described in the present disclosure, the overlap condition has been preferred so as to directly align a new pattern to a previously impressed one through transmission signal feedback. However, other schemes may be devised to reduce this overlap to zero, given suitable intensity profiles, while still referencing off of previous impressions to perform the alignment. In this respect, such zero, or even negative overlap configurations, may be implemented without violating the spirit of this invention. It is the intention of this disclosure to describe preferred and exemplary embodiments of the present invention. This does in no way exclude other modifications and embodiments to the present invention that that do not violate the spirit of this invention.

This invention addresses the scalability problem of periodic “nanostructured” surface treatments such as those formed by interference lithography. A novel but simple method is described that achieves seamless stitching of nanostructure surface textures at the pattern exposure level. The described tiling approach will enable scaling up of coherent nanostructured surfaces to arbitrary area sizes. Such a large form factor nanotechnology will be essential for fabricating large aperture, coherent diffractive elements. Other applications include high performance, antiglare/antireflection and smudge resistant Motheye treatments for display products such as PDA's, laptop computers, large screen TV's, cockpit canopies, instrument panels, missile and targeting domes, and, more recently, “negative-index” surfaces. Although ideal for seamless stitching of nanometer scale patterns, the technology is broadly applicable to any situation where an arbitrarily large area needs to be seamlessly tiled with a smaller base pattern that has periodic overlap able boundaries.

CROSS REFERENCES TO RELATED APPLICATIONS The present application claims priority to U.S. Provisional Patent Application No. 61/553,244, filed on Oct. 30, 2011, claims priority to U.S. Provisional Patent Application No. 61/553,253, filed on Oct. 31, 2011, claims priority to U.S. Provisional Patent Application No. 61/553,254, filed on Oct. 31, 2011, is a continuation-in-part application of U.S. patent application Ser. No. 12/697,258, filed on Jan. 31, 2010, which claims priority to U.S. Provisional Patent Application No. 61/149,692, filed on Feb. 2, 2009, and is a continuation-in-part application of U.S. patent application Ser. No. 12/697,264, filed on Jan. 31, 2010, which claims priority to U.S. Provisional Patent Application No. 61/149,692, filed on Feb. 2, 2009, all of which are hereby incorporated by reference in their entireties. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT Not Applicable BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is related to a wireless sub-surface sensor. 2. Description of the Related Art The prior art discusses other irrigation systems and methods. Closing an underground to above ground RF communication link is a challenging task. The challenge is typically due to difficult propagation conditions perpetrated by high water content as well as high conductivity in the soil. The moisture and conductivity vary over time depending on environmental stimulus. High water content increases the rate of absorption of RF energy. Salinity and moisture both change the die-electric constant of the soil, effectively detuning the antenna element as water content changes over time. In instances, it is possible to adaptively modify the antenna tuning elements, to attempt to tune the antenna to the current state of the soil. However, in some instances it may not be possible to overcome the adverse effects of moisture in the ground by direct tuning of the RF and antenna components on board the underground wireless sensor. In other instances, certain wireless sensing devices may not be able to adapt their tuning in close to real time to match the soil conditions. The Present Invention seeks to resolve the problems of the prior art. BRIEF SUMMARY OF THE INVENTION The present invention provides a solution to the problems of the prior art. One aspect of the present invention is related to adaptive packet transmission rate and transmission power based on conditions of the phenomena that are being measured. An adaptive sensor transmission with a sensor value based control of sensor data transmission rate. Another aspect of the present invention is a wireless sensor capable of sensing and measuring at least one ambient parameter. The same sensor is capable of transmission of measurement values at some periodic rate, where the transmission rate can be varied. The ambient parameters examples include soil or air temperature, soil moisture, soil nitrate value. Other parameters are also applicable. There is a local processor collocated with the sensor where decision logic may be stored. Environment sampling takes places at a predefined fixed rate. Transmission takes place only if the current values is significantly different than the previously sampled value or if at least a given period of time has elapsed from the previous transmission interval. Another aspect of the present invention is a predefined transmission schedule is presented. A plurality of sensor value ranges are defined. When the environment al measurements fall in the given range, a different sampling rate and transmission rate will be followed. Example: when the measured temperate value is below a given limit, sensor sampling will be done at a lower rate and sensor value reporting will be stopped. The same logic may be applied to an array of measurement parameter values and reporting rates. Another aspect of the present invention is when the sensors measure the soil moisture value to dry, i.e. the sensor is out of the soil, the sensor transmit power levels are adjusted (reduced) to accommodate a different propagation condition. RF impedances (complex resistances) are often characterized on a two dimensional SMITH® Chart. A discussion of SMITH® Charts is set forth in Designing Impedance Matching Networks With the HP 8751 A , Hewlett-Packard Company, 1990, which is hereby incorporated by reference in its entirety. Another discussion of SMITH® Charts is set forth in Stephen D Stearns, Mysteries of the Smith Chart , Pacificon 2001, 2001, which is hereby incorporated by reference in its entirety. The inventors noticed that if the antenna is tuned in a specific and novel manner, its impedance is shifted in an arc around the ideal match (about 50 ohms) as moisture levels in the soil changed. By characterizing the arc by a radius and angle, the inventors were able to tune the radius to remain nearly constant. Only the phase angle of the impedance changed. The inventors designed the physical antenna structure, board structure, housing (air space) and tuning elements to maintain a constant impedance magnitude. This became an automatic, adaptive RF tuning which improved antenna performance across a range of soil moisture levels. The present invention provides a solution to the problems of the prior art. The inventors of the present invention noticed the dielectric of soil, and how it changes with moisture and salinity, which led them to believe that a radiofrequency (“RF”) antenna of a wireless sub-surface soil sensor may be able to be tuned based on moisture and salinity measurements. The inventors measured soil moisture and salinity using novel sensors which also provided the electrical properties of the soil in which the wireless sub-surface soil sensor was placed. These electrical properties affect the efficient transmission and range of an antenna. The inventors realized that an antenna could be configured to optimize transmission efficiency and boost range. Components added to the antenna circuitry controlled by the processor allow for the antenna to be tuned based on the electrical properties of the soil. One aspect of the present invention improves a communication range and communication reliability of an antenna for a wireless soil sensor buried below the surface of a land area. The system includes a set of wireless sub-surface sensors, a receiver, and a control engine. The wireless sub-surface sensors include a configuration switchable antenna, a processor and a battery. The sensors monitor soil conductivity and soil dielectric constant values and transmit and receive the monitored data to and from above ground. The receiver monitors signal strength from each of the wireless sub-surface sensors based on a set of switchable antenna configurations, and also transmits and receives data. The control engine includes a processor configured to create a two-dimensional map of the signal property of the switchable antenna configurations, based on soil conductivity and soil dielectric constant values. The control engine receives data from the receiver. The sets of wireless sub-surface sensors are made up of a first group of sensors positioned within the upper soil and a second group of sensors positioned within the lower soil, and the sensors monitor the soil conductivity and the soil dielectric constant within their respective sections of soil. A wireless sensor is activated to measure soil electrical properties, which includes soil conductivity and a soil dielectric constant, for a land area. The land area is preferably a golf course. The measured data is transmitted from the sensor to at least one receiver above the surface at a set of switchable antenna configurations, and a signal property, preferably received signal strength, is monitored for the transmission of data. The measuring and monitoring is repeated at sixty sensor transmission cycle intervals. A map of the signal property for the set of switchable antennal configurations is created and provided to each set of sensor nodes. The most favorable antenna configuration for the position of the node is determined and then the node is configured to the favorable configuration and data is transmitted from the node. The map is preferably a two-dimensional map of soil conductivity and the soil dielectric constant. Another aspect of the present invention improves wireless soil communication when buried below ground. The system includes a set of wireless sub-surface sensors, a receiver and a control engine. The receiver receives and transmits data to the wireless sub-surface sensors. The control engine includes a processor and receives data from the receiver. Sensors can be paired with an irrigation controller. A sensor transmits a pairing signal, the pairing signal is received at an irrigation controller, and the irrigation controller is then paired with the wireless sensor. A wireless sensor transmits data to at least one receiver above the surface of the land and the communication link quality of the data transmission is monitored, and depending on the communication link quality and at least one soil condition, the power level of the sensor will vary. Algorithms are used to sweep potential antenna configurations and matching components, which are used within a node to extend a transmissions range, to optimize link budget. Yet another aspect of the present invention predicts sensor values from wireless sensors when wireless transmissions from the sensors are not received due to radio noise, environmental conditions, dropping battery levels, damaged sensors, etc. based on the time duration from the previous successfully received sensor value; the value of the last successfully received sensor value; observed correlations between the sensor that has not reported and those that are still successfully received; or data from other, non-wireless sensors as well as data from other installations that may be received wirelessly such as nearby weather stations. The missing sensor value is assumed to be the last successfully reported sensor value if the elapsed time interval is less than some specified length; or the missing sensor value is assumed to be an average, the minimum, maximum, or some other statistical measure of all other sensors in the same installation that have been successfully received; or the missing sensor value is assumed to be the same as another successfully received sensor value that historically has been most correlated with the missing sensor; or the missing sensor value will reflect other sensor data such as weather data and current irrigation run times for the sensor location to predict the missing value. The missing soil moisture sensor value is assumed to be wet as wet soils typically make wireless communication more difficult. One or more of the strategies of missing data can be applied simultaneously. Yet another aspect of the present invention is a wireless soil sensor. The sensor includes a sensing component, a transceiver, a microcontroller, a battery, and an energy saving circuit. The microcontroller generates a clock signal at a predetermined frequency for performing soil conductivity measurements. Yet another aspect of the present invention is an adaptive irrigation control. A set of real-time soil measurements is obtained, which is the basis for prorating irrigation, by an irrigation interrupter. The irrigation interrupter includes a housing and a processor configured to create a set of profiles of moisture levels and behaviors. Each profile has a minimum moisture level, a maximum moisture level, and a mechanism for mid-flow cutoff for a watering cycle of a predetermined length to control the irrigation. Yet another aspect of the present invention is a wireless soil sensing network. The network includes field swappable, tethered sensors on a node which allows for flexible sensor placement away from a soil disturbing node which can be placed near the surface to improve communication range. The network can also include an inductive coupling sensor link. Power and communications are achieved by the inductive link, which eliminates through cables and simplifies sensor installation, assembly, and waterproofing of nodes. Yet another aspect of the present invention is a system for controlling irrigation in a community. The system includes a water source, a set of wireless controllers, and a set of sub-surface sensors. The controllers control the flow of water through each set of valves, each set of wireless controllers at a home in the community. The valves are in flow communication with the water source and a sprinkler, each set of valves corresponding to a sub-area of a set of sub-areas of a soil area. The wireless controller is in wireless communication with the sub-surface wireless sensors. The sub-surface sensors include a processor, a transceiver, and a power source. The sensors correspond to a sub-area of a set of sub-areas of a soil area, each set of sub-surface sensors corresponding to a valve within a set of valves, each set of sub-surface sensors having a probe structure for measuring a moisture content of the corresponding sub-area of a set of sub-areas. Irrigation data from each home is sent from the wireless controller to a central location so that it can be aggregated into community wide reporting/management of irrigation. Yet another aspect of the present invention improves a communication range and communication reliability of a wireless soil sensor buried below the surface of a land area. When a communication link with a wireless sensor is determined to have been lost, a nearby reliably communicating sensor is assigned to act as a proxy for the sensor that lost communication. Alternatively, after determining that the wireless sensor's communication link is lost, irrigation decisions are made based on all other reporting sensors instead. It is an object of the present invention to provide a proprietary wireless root zone intelligence system that measures real time soil moisture, temperature and salinity. It is an object of the present invention to provide an advanced wireless sensor and analytical, intuitive, fully interactive software. It is an object of the present invention to optimizes turf health and playability, improve product quality, optimize resource utilization. It is an object of the present invention to provide a state-of-the-art wireless mesh network, coupled with comprehensive software monitoring, eliminates guesswork. It is an object of the present invention to provide real-time trending and predictive modeling accessible via software at your fingertips. It is an object of the present invention to provide world-class, web-enabled agronomy services. It is an object of the present invention to provide help users best manage greens, fairways and rough. It is an object of the present invention to provide sensor collection data on root zone moisture, salinity and temperature. It is an object of the present invention to provide monitor healthy thresholds. It is an object of the present invention to provide a cost saving benefits. It is an object of the present invention to provide efficiencies in water, energy and fertilizer usage. It is an object of the present invention to provide added salinity controls. It is an object of the present invention to provide decreased labor inputs. It is an object of the present invention to provide increased turf quality and crop yields. It is an object of the present invention to provide agronomic benefits. It is an object of the present invention to provide efficient salinity management and irrigation uniformity. It is an object of the present invention to provide deeper rooting for more oxygen. It is an object of the present invention to provide predictive disease control. It is an object of the present invention to provide environmental benefits. It is an object of the present invention to provide water conservation of 25% or more. It is an object of the present invention to provide reduced phosphates, nitrates and pesticides. It is an object of the present invention to provide a reduced carbon footprint. It is an object of the present invention to provide regulatory benefits. It is an object of the present invention to provide water-mandate friendly, measurable compliance. It is an object of the present invention to promote green activity. One aspect of the present invention is full control of irrigation without user intervention. Another aspect is an adaptive irrigation interrupter which learns the watering patterns established by an irrigation controller and takes action to intelligently limit watering based on knowledge of time, temperature and soil moisture. Ten sets, or profiles, of moisture levels and behaviors are defined for soils ranging from maximum moisture retention/need such as clay soils to minimal moisture retention such as sandy soils. Each profile has a minimum moisture level (where the device will not suppress any watering), a max moisture level (where the device will entirely suppress watering), and a mechanism for mid-flow cutoff so that for a watering cycle of a predetermined length the device controls how long to allow irrigation. The interrupter learns the watering pattern of the controller by monitoring behavior over a set period (two weeks), and mapping the start and duration of each zone's irrigation. A default profile is preferably set to enable users to ignore a setting and only adjust it after observing overall plant results. Web-site interaction preferably provides greater information. The interrupter also preferably monitors sensor soil temperatures and its own to enable cold weather control, which may be set to trigger at 40 F and 33 F, where reduced watering is set. The present invention provides a wireless soil sensor. The wireless sensor includes a microcontroller, an antenna and an amplifier in electrical communication with the antenna. The amplifier varies a power transmission to the antenna based on a real-time soil conductivity value of a soil area and a real-time soil dielectric constant value of a soil area to improve a communication range and communication reliability of the antenna. The antenna circuit preferably includes a set of resistors and inductors for tuning the antenna. The sensor's microcontroller is preferably configured to measure analog voltages and perform calculations to determine the real-time soil conductivity value and the real-time soil dielectric constant value. The soil sensor preferably includes a soil moisture circuit and a soil salinity circuit. One aspect of the present invention is a wireless soil sensor with additional aspects. The wireless sensor includes a microcontroller, an antenna and an amplifier, as well as a probe conducting structure, a soil moisture circuit, and a soil salinity circuit. The antenna preferably transmits at 2.4 Gigahertz. The amplifier varies a power transmission to the antenna based on a real-time soil conductivity value of a soil area and a real-time soil dielectric constant value of a soil area to improve a communication range and communication reliability of the antenna. The probe conducting structure is placed in the material forming a capacitor connected to a soil moisture circuit. The soil moisture circuit includes a high frequency oscillator for applying electrical stimulus to the probe structure, a known reference capacitor connected in series to the high frequency oscillator, and a first voltage meter located between the high frequency oscillator and the reference capacitor. The soil salinity circuit includes a low frequency oscillator for applying electrical stimulus to the probe structure, a known reference resistor connected in series to the low frequency oscillator, and a second voltage meter located between the low frequency oscillator and the reference resistor. Furthermore, the respective circuits connect between the reference capacitor and the reference resistor, at which point the circuits are connected to the probe structure and a third voltage meter. Another aspect of the present invention is a method for tuning an antenna of a wireless sub-surface sensor positioned in a soil area. The method comprises determining at least one real-time electrical property of a soil area, analyzing the real-time electrical property to determine an optimal antenna power for efficient transmission and range, amplifying power to the antenna from an amplifier, and transmitting data from the amplified antenna to a receiver above ground. The set of soil electrical properties includes soil conductivity and soil dielectric constant values. The present invention provides a wireless sensor capable of sensing and measuring at least one ambient parameter. The wireless sensor is capable of transmitting measurement values at a periodic rate, at a transmission rate that is varied or non-varied. The ambient parameters preferably comprise at least one of soil temperature, air temperature, soil moisture, soil nitrate value and other parameters. The sampling preferably takes places at a predefined fixed rate. The wireless sensor preferably houses a local processor that has a decision logic within. One aspect of the present invention is related to wireless sensor transmission. Transmission takes place only if the current value is significantly different than the previously sampled value or if at least a given period of time has elapsed from the previous transmission interval. Another aspect of the present invention is a predefined transmission schedule. A set of sensor value ranges is defined and when the environmental measurements fall within the given range, a different sampling rate and transmission rate will be followed. When the measured temperate value is below a given limit, sensor sampling will be done at a lower rate and sensor value reporting will be stopped. The same logic is applied to an array of measurement parameter values and reporting rates. Yet another aspect of the present invention is related to sensor adaptation. When the sensors measure the soil moisture value to dry, the sensor transmit power levels are adjusted to accommodate a different propagation condition. The sensor transmit power levels are reduced. Having briefly described the present invention, the above and further objects, features and advantages thereof will be recognized by those skilled in the pertinent art from the following detailed description of the invention when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS FIG. 1 is a top perspective view of a wireless soil sensor of the present invention with a sleeve attached over a portion of the wireless soil sensor. FIG. 2 is a first side view of the wireless soil sensor of FIG. 1 . FIG. 3 is an opposing side view of the wireless soil sensor of FIG. 1 . FIG. 4 is top plan view of the wireless soil sensor of FIG. 1 . FIG. 5 is a top perspective view of a wireless soil sensor of the present invention without a sleeve attached over a portion of the wireless soil sensor. FIG. 6 is a first side view of the wireless soil sensor of FIG. 5 . FIG. 7 is top plan view of the wireless soil sensor of FIG. 5 . FIG. 8 is a rear plan view of the wireless soil sensor of FIG. 5 . FIG. 9 is a schematic diagram of a preferred embodiment of a system of the present invention. FIG. 9A is a schematic diagram of a preferred embodiment of a system of the present invention illustrating a mesh network established by the transmitters of the system. FIG. 9B is a schematic diagram of an embodiment of a sensor node of the system. FIG. 9C is a schematic diagram of an embodiment of a sensor node of the system. FIG. 10 is a flow chart of a preferred method. FIG. 11 is an image of flushing information. FIG. 12 is an image of indicators for the optimal zone. FIG. 13 is an image of proactive irrigation practices. FIG. 14 is an image of comprehensive analysis for defining the zone. FIG. 14A is an image of current performance in relation to the zone. FIG. 14B is an image of indicators out of the zone. FIG. 14C is an image of salinity information. FIG. 15 is a schematic diagram of a prior art irrigation control system. FIG. 16 is a schematic diagram of an irrigation control system with an irrigation interrupt. FIG. 17 is a schematic diagram of an irrigation control system with a wireless irrigation controller. FIG. 18 is a schematic diagram of a prior art irrigation control system. FIG. 19 is a schematic diagram of an irrigation control system with a tethered sensor. FIG. 20 is a schematic diagram of an irrigation control system with a wireless interrupt. FIG. 21 is a schematic diagram of an irrigation control system with a wireless controller. FIG. 22 is a block diagram of an alternative embodiment of a sensor. FIG. 23 is a graph of a calibration curve showing variation in 1/RC with increasing sample conductivity. FIG. 24 is a schematic diagram of an embodiment of a sensor. FIG. 25 is a flow chart of a method. FIG. 26 is a flow chart of a method. FIG. 27 is a flow chart of a method. FIG. 28 is a flow chart of a method. FIG. 29 is a flow chart of a method. DETAILED DESCRIPTION OF THE INVENTION The present invention may be used with a system and method such as disclosed in Glancy et al., U.S. patent application Ser. No. 12/983,241, filed on Dec. 31, 2010 for an Apparatus And Method For Wireless Real Time Measurement And Control Of Soil And Turf Conditions, which is hereby incorporated by reference in its entirety. The present invention may be used with a system, sensor and method such as disclosed in Campbell, U.S. Pat. No. 7,482,820 for a Sensor For Measuring Moisture And Salinity, which is hereby incorporated by reference in its entirety. The present invention may use a chemical sensor probe such as disclose in U.S. Pat. No. 4,059,499 which is hereby incorporated by reference in its entirety. The present invention may use a chemical sensor probe such as disclose in U.S. Pat. No. 5,033,397 which is hereby incorporated by reference in its entirety. The present invention may utilize the systems and methods disclosed in Magro et al., U.S. patent application Ser. No. 12/697,226, filed on Jan. 30, 2010, for a Method And System For Monitoring Soil And Water Resources, which is hereby incorporated by reference in its entirety. The present invention may also utilize the systems and methods disclosed in Magro et al., U.S. patent application Ser. No. 12/911,720, filed on Oct. 25, 2010 for a Method For Soil Analysis, which is hereby incorporated by reference in its entirety. Magro et al., U.S. patent application Ser. No. 12/698,176, filed on Feb. 2, 2010 for a Method And System For Monitoring Soil And Water Resources is hereby incorporated by reference in its entirety. Campbell et al., U.S. patent application Ser. No. 12/698,138, filed on Feb. 1, 2010 for a Method, System And Sensor For Performing Soil Measurements is hereby incorporated by reference in its entirety. Campbell et al., U.S. Pat. No. 8,035,403 for a Wireless Soil Sensor Utilizing A RF Frequency For Performing Soil Moisture Measurements is hereby incorporated by reference in its entirety. Campbell et al., U.S. patent application Ser. No. 12/697,258, filed on Jan. 31, 2010 for a Method And System For Improving A Communication Range And Reliability Of A Soil Sensor Antenna is hereby incorporated by reference in its entirety. Campbell et al., U.S. patent application Ser. No. 12/697,264, filed on Jan. 31, 2010 for an Antenna Circuit Matching The Soil Conditions is hereby incorporated by reference in its entirety. Campbell et al., U.S. patent application Ser. No. 12/697,283, filed on Jan. 31, 2010 for an Adaptive Irrigation Control is hereby incorporated by reference in its entirety. Campbell et al., U.S. patent application Ser. No. 12/697,281, filed on Jan. 31, 2010 for an Irrigation Interrupter is hereby incorporated by reference in its entirety. Campbell et al., U.S. patent application Ser. No. 12/697,292, filed on Jan. 31, 2010 for a Wireless Soil Sensor Utilizing A RF Frequency For Performing Soil Moisture Measurements is hereby incorporated by reference in its entirety. Campbell et al., U.S. patent application Ser. No. 12/697,256, filed on Jan. 31, 2010 for a Method And System For Soil And Water Resources is hereby incorporated by reference in its entirety. Campbell et al., U.S. patent application Ser. No. 12/697,257, filed on Jan. 31, 2010 for a Method And System For Soil And Water Resources is hereby incorporated by reference in its entirety. Systems, methods, sensors, controllers and interrupters for optimizing irrigation are disclosed in Campbell et al., U.S. patent application Ser. No. 12/697,258, filed on Jan. 31, 2010, for a Method And System For Improving A Communication Range And Reliability Of A Soil Sensor Antenna, which is hereby incorporated by reference in its entirety. Likewise, systems, methods, sensors, controllers and interrupters for optimizing irrigation are disclosed in Campbell et al., U.S. patent application Ser. No. 12/697,254, filed on Jan. 31, 2010, for a Method And System For Soil And Water Resources, which is hereby incorporated by reference in its entirety. Magro et al., U.S. patent application Ser. No. 13/017,538, filed on Jan. 31, 2011 for an Automatic Efficient Irrigation Threshold Setting is hereby incorporated by reference in its entirety. Apruzzese et al., U.S. Provisional Patent Application No. 61/553,237, filed on Oct. 30, 2011, for an Irrigation Controller is hereby incorporated by reference in its entirety. A wireless sub-surface sensor 21 is shown in FIGS. 1-8 . The wireless sub-surface sensor is placed in the soil below the surface to monitor various parameters of the soil such as electrical properties. Other parameters include moisture, salinity and temperature. As shown in FIGS. 9 , 9 A and 9 B, a preferred embodiment of a system of the present invention is generally designated 20 . The system preferably includes a plurality of wireless sub-surface sensors 21 (upper soil 21 a and lower soil 21 b ), a plurality of above-ground receivers 22 , a control engine located at an operations center, and a plurality of above-ground sensors 24 . The above ground sensors 24 preferably measures air temperature, wind speed, and relative humidity. FIG. 9B illustrates a wireless sub-surface sensor 21 preferably utilized in the system 20 . The wireless sub-surface sensor 21 preferably has a housing 30 , a processor 31 , a configuration switchable antenna 32 , sensors 33 a , 33 b and 33 c , and a power supply 34 . The sensors 33 are preferably measure the electrical properties of the soil. FIG. 9C illustrates a wireless sub-surface sensor 21 alternatively utilized in the system 20 . The wireless sub-surface sensor 21 preferably has a housing 30 , a processor 31 with an integrated sensor 33 , a configuration switchable antenna 32 , and a power supply 34 . FIG. 10 is a flow chart of a preferred method 1000 for a wireless soil sensor power saving transmission protocol. At block 1001 , a wireless sensor is activated. At block 1002 , a plurality of soil properties for the land area are measured by the wireless sub-surface sensor. At block 1003 , data from the wireless sensor is attempted to be transmitted to at least one receiver above the surface of the land area. At block 1004 , the wireless sub-surface soil sensor fails to connect with a receiver a predetermined number of times. The predetermined number can vary from 10 to 100, and all ranges in between. At block 1005 , the wireless sub-surface soil sensor determines that a moisture level of the soil is at or above a threshold level. At block 1006 , the wireless sub-surface soil sensor deactivates transmissions to conserve power. The deactivation period preferably ranges from 30 minutes to 48 hours, and all time period in between. At block 1007 , the wireless sub-surface soil sensor measures the soil moisture level. At block 1008 , the wireless sub-surface soil sensor determines that the soil moisture level is below a threshold. At block 1009 , the wireless sub-surface soil sensor reactivates transmissions to the receiver. An example of a protocol that will implement an embodiment of this approach is provided below. It is provided in the context of a two way over the air link, but can easily be applied to a one way link. A wireless device (soil sensor 21 , interrupter 12 or controller 11 ) typically goes through a network entry process, in which it searches for and locks onto the signals of other members of the wireless network it is entering. After the signal lock, a handshake takes place, where the entering node transmits and expects to receive a sequence of well defined messages over the air. At the conclusion of this handshake, the entering node is considered a member of the network. It will be able to transmit and receive over the air messages using a well defined protocol. It will be considered a “Joined” member. A “joined” member may maintain a connection oriented or a connection less link with its radio neighbors. (Example of a connection oriented link is a time synchronized CDMA channel between a station and a cell tower. Example of a connection-less link is the Carrier Sense Medium Access (CSMA) link between a WiFi station and its Access Point). Typically, if the “joined” member is not able to communicate with the other end of the link within a predefined window, it loses its “joined” status, and has to go through a network entry process again. At the least, it may have to perform a less complex re-synchronization task to re-establish its time synch with the network (if is uses a connection oriented link). The link establishment, re-synch, or network entry process will continue (typically with less and less frequency, upon failed attempts) until a) the node rejoins the network, b) the time interval between reentry attempts becomes so large that the node effectively becomes dormant, or c) until the node runs out of battery. The wireless soil sensor 21 is required to transmit messages for all of the above transactions. If the cause of loss of “joined” status is dues to surrounding soil that is too moist or too saline then the rejoin attempts will also fail. If this condition is not detected, the wireless soil sensor 21 will continue wasting scarce battery reserves for transmissions. The adaptive transmission scheduling mechanism discussed here takes into account the moisture and conductivity of the soil that surrounds the wireless soil sensor 21 . It will stop transmissions until the moisture levels of the soil surrounding the node have dropped to manageable levels that will allow successful transmissions. An example of a preferred method of adaptive transmission is as follows. A preferred method for an adaptive transmission aspect of the present invention begins with determining if (x) number of consecutive connection attempts (or transmission) have failed. Next, the method includes determining if the measured moisture level (or a composite metric that includes moisture and conductivity levels) is at some threshold (y) or above. Next, the method includes assuming the surrounding soil is too wet. Next, the method includes suspending the timers that control the transmission activity of the node. Next, the method includes, continuing to sample the moisture levels, and as long as the moisture levels are above threshold (z), attempting to connect once every predetermined time period, T (T time units only, where T is larger than typical inter-transmission intervals). Next, the method includes determining when the moisture levels have dropped below a threshold (w), then un-suspending the timers and a state machine that controls transmissions. Next, the method includes, allowing the normal protocol to resume for the system. One can manage what one can measure. And, one can do it all on a real time basis. Soil intelligence equals savings and health. The present invention is preferably a complete package of advanced software, agronomic services and wireless sensor system that helps take the guesswork out of turf management. The present invention turns raw data into useful operating thresholds that help maintain and optimize plant health and performance. The present invention provides the necessary formula that automatically alerts when and where a facility might be experiencing stress and what the treatment options are. One aspect of the present invention has a data collection component of the software, which allows for monitoring in real time, from an office or from on-site or remote locations, the key variables of moisture, salinity and temperature from each sensor site. The graphic displays are user-friendly and the present invention helps set high-low threshold ranges for each sensor location so that one instantly knows whether the soil is in or out of the optimal range for growth conditions and playability. By continuously analyzing the recorded data and thresholds for each location, this component visually alerts one to conditions at each sensor location and suggests what actions are needed to be more efficient and effective. One aspect of the present invention optimizes turf and crop health and playability by measuring root zone moisture, salinity and temperature and applying best practices to your turf management. Once the wireless soil sensors 21 are in the ground sending raw data, an optimal zone is devised by analyzing accumulated sensor data, putting decades of agronomic experience to use and applying tested scientific principles. The Zone defines the upper and lower operating thresholds to ensure plant health. This helps with: course evaluation; soil and water analyses; review of existing practices including irrigation, nutritional inputs and maintenance; threshold determinations; sensor placement and more. On a real-time basis, one can manage greens, tees, fairways and rough to keep a facility in prime condition. The wireless soil sensor 21 provides wireless interface between the sensing elements and the Communication Control Nodes (CCNs) that preferably form a mesh network. The key features include the shape: 8×4 inches. Buried with a Standard Cup Cutter. Supports sensors: analog or digital. 3 “D” Cell batteries: 4+ years life, field replaceable. 1 Watt FHSS radio board supports approximately 400 ft. range 4 in. in ground. Sensor interface and antenna for over air programming for product upgrades. The key functionalities of the wireless soil sensor 21 are as follows: provide accurate, real-time data on soil moisture, temperature and salinity. Key Features: Pre calibrated for sand, silt and clay. Moisture measurement. Accuracy: +/−0.02WFV from 0 to saturation at <2.5 dS/m conductivity. +/−0.04WFV from 0 to saturation at 2.5-5 dS/m conductivity. Repeatability: +/−0.001WFV. WFV is the fraction of soil occupied by water, a soil at 10% soil moisture has a WFV of 0.10. Conductivity measurement: Accuracy: +/−2% or 0.02 dS/m, whichever is greater, 0-2.5 dS/m.+/−5%, 2.5-5 dS/m. Repeatability: +/−1% or 0.01 dS/m whichever is greater, 0-2.5 dS/m.+/−4%, 2.5-5 dS/m. Temperature measurement: Accuracy: +/−0.5° C. from −10 to +50° C., +/−1° F. from 14 to 122° F. Repeatability: 0.05° C., 0.1° F. Benefits: Dual sensors allow gradients of soil moisture, conductivity, and temperature to be monitored. High accuracy and repeatability. No individual sensor calibration required. Above-Ground Wireless Mesh Network: Communication Control Nodes. Key Functionality: CCNs are the interface to the Sensor Nodes. Each is a radio node that automatically joins and forms the mesh network on power up. Key Features: Range of ˜1 mile above ground unobstructed. Requires 1 Amp while transmitting. 12-24 Volt AC or DC power. Can be attached via 110/220 Volt power adapter. Weather proof enclosure. Benefits: Self forming, self healing, multihop mesh network; No special wiring required; Two way communications with link quality statistics; Control of buried nodes; The multihop mesh allows extension of the wireless coverage area far beyond the nominal range of the radios. Agronomy. Soil health impacts everything grown above. What is agronomy? It is the study of plant and soil sciences and how they impact crop and plant production, performance and yield. Every plant has specific tolerances to environmental variables like moisture, temperature and salinity which impact the ability to grow, flourish, proliferate and perform to expectations. Agronomists using the present invention help define those optimal threshold levels as well as their impacts on root, leaf and lateral growth, responses to man-made or natural environmental stress, and resistance to disease and insect pressure. As a result, in this case water usage was reduced by nearly 30% while playability was enhanced uniformly. The indicator of the present invention predicts the likelihood for disease outbreaks before they happen. The software package utilized feeds off data provided by the wireless soil sensors 21 and wireless communications system. It displays real time conditions and provides comprehensive intelligence and predictive actions. The system helps establish health- and performance-optimizing operating threshold ranges, evaluate your data and current practices, and refine existing programs. The results, optimal turf conditions and real savings, will generate a strong and lasting return on investment. The agronomic benefits include more efficient salinity management, uniform irrigation, deeper rooting, predictive disease control and healthier, more stable conditions. There are environmental benefits as well like water conservation, reduced use of phosphates, nitrates and pesticides, a reduced carbon/water footprint and regulatory compliance. Real time sensor measurements using the present invention also include soil oxygen, pH, concentrations of specific ion species—(Na+ has a very detrimental effect compared to the same concentration of Ca+2). Pollutant measurements include both hydrocarbons (oils, gasoline, etc.) and metals (chromium, lead, etc.). As to the wireless transmission network, an alternative process of an adaptive model may be utilized with the present invention. An antenna, designed for efficient RF communication in air is relatively straightforward because the key electrical properties of the transmission medium (air) are well known and essentially constant. In below ground RF transmission, the key properties of the soils vary greatly with moisture content and salinity hence it is a much more difficult problem to design an efficient antenna. In addition, the best antenna design is influenced by how deeply buried the antenna is. The present invention includes elements to the antenna circuit that, under control of microcontroller, allow for varying the properties of the antenna to more closely match the conditions and improve range and reliability of communication. The wireless sub-surface sensor 21 measures both the dielectric constant of the soil (moisture) and conductivity (salinity) directly. Hence, the sensor measures precisely the two most important factors affecting antenna efficiency. In a predictive model, the method includes activating a sensor and measuring soil electrical properties. The method also includes, based on the soil properties, activating antenna elements to give an effective transmission. The method also includes transmitting sensor data. In an adaptive model, the method includes activating a sensor and measuring soil electrical properties. The method also includes transmitting data repeatedly until all switchable antenna configurations have been attempted. The method also includes monitoring signal strength for each transmission. The method also includes repeat this process possibly every 60 sensor transmissions. As time progress, a receiver can put together a two dimensional map (soil dielectric constant on one axis, soil conductivity on the other) with received power for all antenna configurations. The map is downloaded on some regular schedule to the buried sensor node. When the wireless sub-surface sensor 21 makes a measurement, the sensor reviews the map for the antenna configuration that gives the highest received signal power at the receiver for the current conditions. A node configures an antenna and sends a packet of data. Even after the map is downloaded, every 60 sensor readings preferably have all of the different antenna configurations attempted which allows the map to evolve. The advantage of this adaptive process is that it can make an allowance for the actual depth of burial as well as the relative antenna locations and orientations. This is important because different antenna configurations have different radiation patterns. Hence, it is possible that a less than ideal antenna configuration works best in that it has the highest radiated power in the particular direction and polarization that the receiver antenna lies in. As shown in FIG. 15 , an irrigation system 10 ′ includes a 24 VAC power supply, a controller 11 , and a valve box 13 with valves 123 a and 13 b . These irrigation systems 10 ′ work by using a 24 volt alternating current source to open valves 13 a and 13 b . When no current flows (open switch 51 ), the valves 13 a and 13 b are closed and no water flows. A controller/timer 11 is used to turn on the current to the separate valves 13 a and 13 b . Usually there is a “common” wire 53 that returns the current from all valves 13 a and 13 b . Separate “hot” wires 52 a and 52 b are used for each of the valves 13 a and 13 b . As shown in FIG. 18 , the irrigation controller 11 controls the valve box 13 through wires 17 a and 17 b to provide water form source pipe 16 b to sprinkler pipe 16 a for dispersion on a soil 15 through sprinkler 14 . As shown in FIG. 19 , the prior art is improved upon by a system 10 with a tethered sensor 21 ′ in which is a sensor coupled to an interrupter 12 wired into the wirings 17 a , 17 b , 17 c and 17 d of the valve box 13 . The interrupter 12 acts to turn off a scheduled irrigation if the moisture exceeds a predetermined threshold established by a user. The interrupter 12 acts as an in-line switch that closes (allowing current to flow and the valve 13 to open) only if the controller 11 starts a scheduled irrigation and the soil moisture is below a predetermined threshold established by a user). In the system 10 of FIG. 19 , the interrupter 12 can only interrupt a scheduled irrigation, not initiate an irrigation. The system 10 has a sensor 21 which is cabled (no wireless communication). The system 10 of FIG. 19 has the advantage of being very simple, it is capable of being easily installed into virtually all existing irrigation systems, and it requires no independent power (the system 10 draws power off the 24VAC irrigation line). As shown in FIG. 20 , a wireless interrupt approach is similar to the “Tethered Sensor” system 10 of FIG. 19 , except that wireless communication is used between a wireless soil sensor 21 and an interrupter 12 . The wireless soil sensor 21 requires battery power and the interrupter 12 requires a battery to accommodate flexible wireless reporting. The principle advantage of the system 10 of FIG. 20 is that no cabling is needed, and installation is simpler than the tethered system 10 of FIG. 19 . As shown in FIG. 20 , the wireless soil sensor 21 transmits a wireless signal 18 a to the interrupter 12 pertaining to the moisture levels of the soil in a particular soil area. A wireless controller system 10 is shown in FIG. 21 . The wireless controller system 10 uses a wireless link back to a wireless irrigation controller 11 (there is no “interrupter”) The principle advantage of the wireless controller system 10 of FIG. 21 is that the wireless soil sensors 21 preferably initiate irrigation if needed (allowing for the user to set scheduled irrigation times as well if desired). A user also may allow the wireless controller 11 to look at more than one wireless soil sensor 21 for each irrigation zone (area irrigated by one valve 13 ) taking an average, use the lowest value, etc. One can also allow for simpler level adjusting, including such features as a “hot day” button nudging the target water levels up a notch and many others. The goal of one aspect of the present invention is to develop an inexpensive and easy to install system compatible with existing irrigation systems that can be quickly configured by homeowners/landscapers of limited technical sophistication. An objective of the present invention is an overall lower cost, a system that is easy to install in existing and new irrigation systems, setup that is as easy to use as a traditional irrigation controller, and careful design of setup features, default modes, user input device and display to give a superior customer interface. Irrigation interrupt of the system interfaces simply with existing irrigation control systems to over-ride scheduled irrigation when moisture levels hit user settable thresholds. When operating in this manner, the system is incapable of initiating an irrigation event and needs to be used with a conventional irrigation controller. An irrigation controller 11 of the system 10 can initiate and stop irrigation events and replaces existing installation irrigation controllers or is suitable for complete control of new installations through both timing of irrigation to certain times of the day as well as based on near real-time soil moisture data. As mentioned above, a typical irrigation controller system 10 ′ is shown in FIG. 15 . The system 10 ′ includes a 24VAC power supply connected to 120VAC and an irrigation controller 11 . Wiring 52 a and 52 b leads from the controller 11 to one or more valve boxes 13 . When the current loop is closed, the valves 13 a and 13 b open and a zone is watered. Typically, the controller 11 is set to turn on and off valves at predetermined times for a set time. In the irrigation interrupt system 10 , as shown in FIG. 16 , the interrupter 12 is positioned between the standard irrigation controller 11 and the valves 13 a and 13 b . A wireless soil sensor 21 is placed in each irrigation zone and the wireless soil sensor 21 is in periodic communication with the irrigation controller 12 . In this system, watering only occurs when both the standard irrigation controller 11 indicates that it is time to water and the irrigation interrupter 12 indicates that soil moisture is below a predetermined threshold. The interrupter 12 opens switch 54 a and 54 b to terminate the current flow through lines 52 a ′ and 52 b ′ and close the valves 13 a and 13 b . Line 55 provides power to the interrupter 12 , especially when the switch 51 of the controller 11 is open. In the wireless irrigation controller system 10 of FIG. 17 , the same interrupter hardware is used but the inputs to the irrigation interrupter 12 are always on, i.e. the irrigation interrupt 12 is now in control and irrigation will occur under the direct control of the wireless interrupter 12 based on soil moisture data. Different firmware is necessary, but the hardware is identical with only minimal changes in the wiring. In both systems, power for the irrigation interrupter 12 is drawn directly off the 24VAC eliminating the need for a separate power supply. The system 10 is capable of operating with soil moisture only wireless soil sensors 21 with integrated two-way wireless telemetry, sensor firmware, an irrigation interrupter/controller (Controller) and controller firmware. The wireless soil sensors consist of a soil moisture only sensor, wireless two-way telemetry, microcontroller, and at least some non-volatile memory, and are preferably battery powered. These components are integrated into one physical package (no cabling) and the wireless soil sensor 21 is buried in strategic locations to monitor soil moisture conditions. The sensor firmware manages making sensor measurements, transmitting them to the controller, receiving controller commands, and power-management (putting system to sleep). The controller 11 preferably consists of two-way wireless telemetry compatible with the wireless soil sensors 21 , a microcontroller, non-volatile memory, a user input (preferably a four or five way wheel), display (preferably 36 character two line LCD), and circuitry for opening or closing switches for irrigation zones (switch in an open position is over-riding irrigation). In existing irrigation systems and for use with an already installed controller, the wireless controller 11 is spliced into existing wiring close to an existing irrigation controller. In replacing an existing irrigation controller or in new installations, the wireless controller 11 is directly connected to irrigation zone wiring. The controller firmware allows collection of wireless telemetry of soil moisture data, “commissioning” of new wireless soil sensors 21 , i.e. associating a wireless soil sensor 21 with an irrigation zone and an installation, setting irrigation thresholds, etc. All of the components preferably operate over a temperature range of −20 to 70° C. (with the exception of the display which is operable over 0 to 50° C.) and are capable of storage over −20 to 70° C. All components preferably are Human Body Model ESD resistant but not lightning resistant. Wireless soil sensors 21 are preferably fully waterproof while the interrupters 12 preferably only have a low level of splash-proofing. For the purposes of determining battery shelf life in the wireless soil sensors 21 , a temperature under 40 C is assumed (temperature, depending on battery technology, can greatly impact self discharge rates). Wireless telemetry range of approximately 100-200 feet is preferred. The range is achieved at depths of up to 12 inches and in moderate clutter (vegetation, slight topography, through garage wall, etc.). A wireless soil sensor 21 is preferably installed at least as close as 3 inches from soil surface for monitoring soil moisture in shallow rooting turf. The package of the wireless soil sensor is preferably no larger than 2″×2″×8″ (ideally 1.5″×1.5″×6″). A bulky package is difficult to install (particularly at shallow depths), disrupt soil environment, and a turn-off to consumers. A non-volatile memory is preferred. Timekeeping is accurate to within +/−2% which allows the wireless soil sensors 21 to wakeup at on a regular schedule, timing for I2C commands, as well as scheduling sensor “listen” windows for wireless receive modes. The wireless soil sensor 21 is capable of receiving simple operational parameters wirelessly from a controller 11 or an interrupter 12 , which allows the controller 11 or the interrupter 12 to set reporting interval, selection of adaptive algorithms, etc. A procedure for re-programming the wireless soil sensors 21 after production is included in order to allow for changes encountered in debugging or upgrades. Alternatively, it can be through a programming header in the battery or by some other wireless programming option. The wireless soil sensor 21 is preferably able to detect imminent battery, to prevent the wireless soil sensors 21 from failing suddenly with no warning or begin to operate intermittently reflecting battery temperature and other variable as well as possibly giving corrupted data that may result in incorrect irrigation decisions. The sensor firmware is capable of executing and reading I2C commands. Analog sensor requires I2C commands to control oscillator and make A/D measurements. I2C commands need to be executed sequentially according to a sloppy timing of about +/−3 mS over 100 mS. I2C can operate anywhere from 20 to 200 KHz. The sensor firmware is able to perform simple calculations like conversion of raw A/D values into soil moisture which requires simple functions-addition, subtraction, division, polynomials but no log, trig, etc. functions. The sensor firmware is capable of going into a very low power mode between set measurement interval with routines to wake up at end of interval which may range from 1-100 min. which is set in a non-volatile configuration file which can be modified by interrupt controller. After measurement is complete, soil moisture data needs to be sent to interrupt controller 11 . The sensor firmware preferably has a static soil moisture mode. An operational mode that allows the wireless soil sensor 21 to wake up, measure soil moisture, and if a change in soil moisture from the last wirelessly reported measurement does not exceed a settable threshold, return to a sleep mode without sending data. This threshold value, as well as whether this feature is enabled, preferably resides in a non-volatile configuration file which can be modified by the interrupt controller 11 . The wireless soil sensor 21 preferably transmits a new reading once every six hours regardless of soil moisture changes to confirm operation. The wireless soil sensor 21 preferably has a default mode firmware upon power restart for the sensor firmware, which allows a wireless soil sensor 21 to be commissioned, i.e. assigned to a specific irrigation interrupter to allow for resolving sensors from a close neighbors residence. In addition, commissioning must be flexible to allow for a change in assigned interrupt controller 11 in the future or if commissioning is lost. A wireless soil sensor 21 is preferably capable of a listening mode in a power efficient manner for receiving changes to the configuration file wirelessly from the interrupt controller 11 with a maximum file size of 100 bytes at least once a month without degrading three year sensor battery life. The wireless soil sensor 21 preferably has the ability to download full operating firmware. On a regular schedule (about once every six hours) the wireless soil sensor 21 preferably provides in addition to the soil moisture value, diagnostics such as battery voltage, and raw measured values not to exceed an additional 25 bytes. This data is used to assess performance and for diagnosis of bugs or sensor failure. If the raw A/D values used to determine soil moisture data are out of normal ranges, the wireless soil sensor 21 preferably sends a “Bad Data” even if the computed soil moisture value appears reasonable. This helps detect failed wireless soil sensors 21 and prevent bad control actions. The irrigation interrupter 12 is capable of turning on and off AC current up to 700 mA continuously at 70 C for each irrigation zone from an AC voltage range of 16 to 34 volts with no more that 1V in drop across switching circuitry. Switching circuitry is not damaged by inductive transients generated by turn off of valve solenoids. Regardless of whether the interrupt controller 11 is allowing or blocking irrigation, the interrupt controller 11 can detect the presence of an AC voltage (generated by irrigation controller 11 to initiate an irrigation). This feature allows for calculations of savings such as % of scheduled irrigation events that were canceled by system. The hardware for the irrigation interrupter 12 is preferably resistant to moderate ESD and transients that may enter system through 24 VAC transformer in order to be reliable. The interrupt controller 11 draws power directly from nominal 24VAC transformer to avoid having to use a separate power supply with a maximum current draw of 100 mA. The interrupt controller 11 operates correctly with an AC input varying from 16 to 34 VAC to account for AC mains voltage of 84 to 130 VAC (typical specified level of AC power seen in a household) and variation in transformer output with load. The interrupt controller 11 is capable of operating in typical residential systems which have between four and eight zones. More sophisticated systems could be addressed by using multiple units. The interrupt controller 11 is preferably capable of a log for the last 30 days of soil moisture readings for eight zones at 10 minute interval as well as whether an irrigation event is occurring, and whether it has been interrupted at 1 minute intervals in non-volatile memory. The log is preferably structured so accurate date and time is available for data record. This feature is good for both debugging purposes but also in allowing the system to display to the user the amount of water saved thus justifying the product. Firmware responds as gracefully as possible to problems. For instance, if soil moisture data is out of range or uC lockup (possibly detected by watchdog circuit) irrigation proceeds according to the irrigation controller 11 (i.e. no interrupt). If an irrigation interrupter 12 is operating as a wireless irrigation controller (no standard irrigation controller), the system 10 should default to no irrigation. Failure modes give obvious indication of problems. Ample code space is preferably reserved to allow for extensive additional features in the future. All user settable configurations are preferably stored in non-volatile memory so as to allow for seamless recovery from lockup or loss of power. Preferably, a real time clock has the ability to keep time after power loss for up to 1 month. The interrupter firmware is capable of generating a user water savings report for the last day, week, and month (i.e. percent of scheduled irrigation that was interrupted) by zone and as a whole for all eight zones as well as total run time per zone. A process is developed to allow sensors upon installation or system expansion to be assigned to a particular irrigation zone for a particular irrigation interrupter. The process needs to be flexible enough to allow for replacement of failed wireless soil sensors 21 as well. This allows the system 10 to be used with neighboring installations without confusion as well as assigning the right sensor to the right zone. A user sets, for each zone, the maximum soil moisture level that will terminate an irrigation event. There is also a settable hysteresis, Y, i.e. if during a single scheduled irrigation event the soil moisture rises about the threshold X and irrigation is stopped, it would not begin again until level fell to X-Y. This prevents valves from turning on and off rapidly when approaching the threshold. When new irrigation event occurs, the threshold defaults back to X. A hold feature allows a user to hold current conditions going forward (i.e. take last soil moisture readings and apply as thresholds). A show current status mode for the interrupt controller 11 defaults to when no keypad entry has occurred for a minute or so and shows zone by zone-threshold, last soil moisture data, irrigation is being attempted, and if irrigation is being interrupted. The save configuration allows up to six configurations to be saved, named, and recalled (for all zones thresholds, hysteresis, adaptive algorithms on or off, etc.). This allows for summer and winter settings, etc. A disable setting is where all zones are enabled and the system is under control of the irrigation controller 11 solely, i.e. the interrupter 12 allows valves 13 a and 13 b to be on at all times when the standard irrigation controller 11 schedules irrigation regardless of the soil moisture data. This is a “safety mode” so that if there are critical problems, the user is not forced to reconfigure things to keep the grass from dying. A bump feature allows a user to “bump” up or down all thresholds equally at an approximately 0.5% water by volume increment (allows for quick adjustment for hot weather or other reasons), which revert to previous settings after 1 days unless user selects to apply them permanently. The firmware is preferably capable of detecting missing or out of range soil moisture and low battery conditions and display warning. A wireless irrigation controller mode allows the irrigation interrupter 12 to function as full soil moisture data driven irrigation controller 11 without the use of a standard irrigation controller 11 . Essentially all of the features of a standard irrigation controller 11 are implemented such as scheduling irrigation times, valve run-times, etc. These scheduled events are subjected to the same “interrupt” schemes as the irrigation interrupter 12 based on soil moisture data. When water is applied to the soil the wireless soil sensors 21 report the increase in moisture content but also look at the tail off in moisture levels when irrigation ceases. In cases of significant overwatering, there is a sharp spike in moisture levels followed by a sharp fall after irrigation ceases. This is due to the soil essentially being so wet it “free drains” below the root zone (thus wasting the water). The present invention implements algorithms to monitor this and adjust irrigation events to eliminate this wasteful practice allowing the system to essentially configure itself over time. The wireless soil sensor 21 is preferably directly integrated with a radio and microcontroller. It also preferably has a sleeve that fits over the sensor that the user removes to turn it on. It also preferably has an optional microcontroller generated clock signal to avoid having to use a separate oscillator for the conductivity measurement. It also preferably has the same RF frequency the radio uses to eliminate having to use a separate oscillator for the soil moisture measurement. It also preferably uses “spread spectrum oscillators” to achieve FCC compliance. It also preferably has sensor components that are currently PCB may be made out of conducting plastic formulations simplifying assembly, improving aesthetics, and reducing costs. As shown in FIG. 22 , the sensor apparatus 120 preferable includes a digital signal processor 135 connected to a moisture circuit 122 and a salinity circuit 123 , which are both connected to a probe structure 121 . The probe structure 121 is placed in the soil which is to be measured. The probe structure 121 forms an effective coaxial capacitor within the soil. Such probe structures are well known in the art, and typically include a base and elongated conductors extending from the base and disposed around a central elongated conductor. The digital signal processor 135 or microprocessor, facilitates the process, allowing for multiple conducting structures to be inserted into the soil (or other media of interest) as well as cabling to provide power and transfer measurement results to recording or control instrumentation. The probe structure 121 , which when placed in soil forms, electrically, the circuit elements C S and R s , and are referred to as forming a “capacitor.” The probe structure 121 can be arranged in a variety of different geometries many of which are shown in U.S. Pat. Nos. 2,870,404, 4,288,742, and 4,540,936, all of which are hereby incorporated by reference in their entireties. The conducting structures of the afore-mentioned '104 patent can also be included in the probe structure 121 . The probe structure 121 can be made of metal, printed circuit board, or other electrically conductive materials. Depending on the media of interest, the range of expected C S and R s to be measured and frequencies employed, many different geometries and sizes can be employed as the probe structure 121 in sensor. FIG. 23 illustrates a graph 302 showing a calibration curve of the variation in 1/RC (X axis) with increasing sample conductivity (Y axis). FIG. 24 is an embodiment of sensor 21 . The wireless sub-surface sensor 21 preferably has a housing 30 , a processor 31 , a configuration switchable antenna 32 , an antenna circuit 39 , sensors 33 a and 33 c , and a power supply 34 . At least one of the sensors 33 are preferably measures the electrical properties of the soil. The antenna circuit 39 tunes the antenna to optimize the transmission. The antenna circuit 39 preferably comprises a plurality of resistors and inductors for tuning the antenna to match an optimal impedance for transmission. FIG. 25 is a flow chart of a method 2000 for prescribing action to maintain a land area within a predetermined performance zone. At block 2001 , a plurality of parameters of the land area are monitored by a plurality of sensors. At block 2002 , a plurality of values for each of the plurality of parameters of the land area are generated by the sensors. At block 2003 , the plurality of values are transmitted to a processing location. At block 2004 , the plurality of values are processed to generate a plurality of indicator values of a current state in relation to the performance zone for the land area. At block 2005 , a desired state for the land area is determined at the processing location. At block 2006 , an action for the land area is prescribed. FIG. 26 is a flow chart of a method 3000 for adaptive irrigation control. At block 3001 , real-time soil moisture, soil temperature and soil salinity values are obtained by a plurality of sensors. At block 3002 , a real-time moisture percolation value is obtained. At block 3003 , watering schedules based on the values are determined without end-user intervention. At block 3004 , watering schedules to at least one of seasonal, weather, climate and soil conditions are adapted by the irrigation system. FIG. 27 is a flow chart of a method 4000 for predicting alerts to maintain a land area within a predetermined performance zone. At block 4001 , a plurality of parameters of the land area are monitored by a plurality of sensors. At block 4002 , a plurality of values for each of the plurality of parameters of the land area are generated by the sensors. At block 4003 , the plurality of values are transmitted to a processing location. At block 4004 , the plurality of values are processed to generate a plurality of indicator values of a current state in relation to the performance zone for the land area. At block 4005 , the processing engine determines if the current state exceeds an alert threshold. At block 4006 , an operator is alerted if the current state exceeds an alert threshold or will exceed an alert threshold. FIG. 28 is a flow chart of a method 5000 for an agronomic service for a land area. At block 5001 , a plurality of parameters of the land area are monitored by a plurality of sensors. At block 5002 , a plurality of values for each of the plurality of parameters of the land area are generated by the sensors. At block 5003 , the plurality of values are transmitted to a processing location. At block 5004 , the plurality of values are processed to generate a plurality of indicator values of a current state in relation to the performance zone for the land area. At block 5005 , the processing engine compares the current state to a performance zone for the land area. At block 5006 , an agronomic service is prescribed based on the current state. FIG. 29 is a flow chart of a method 6000 for an agronomic service for a land area. At block 6001 , a plurality of parameters of the land area are monitored by a plurality of sensors. At block 6002 , a plurality of values for each of the plurality of parameters of the land area are generated by the sensors. At block 6003 , the plurality of values are transmitted to a processing location. At block 6004 , the plurality of values are processed to generate a plurality of indicator values of a current state of the irrigation of the land area. At block 6005 , the processing engine determines if the current state is within at least one regulatory standard. At block 6006 , an agronomic service is prescribed based on the current state. From the foregoing it is believed that those skilled in the pertinent art will recognize the meritorious advancement of this invention and will readily understand that while the present invention has been described in association with a preferred embodiment thereof, and other embodiments illustrated in the accompanying drawings, numerous changes modification and substitutions of equivalents may be made therein without departing from the spirit and scope of this invention which is intended to be unlimited by the foregoing except as may appear in the following appended claim. Therefore, the embodiments of the invention in which an exclusive property or privilege is claimed are defined in the following appended claims.

A wireless sensor capable of sensing and measuring at least one ambient parameter is disclosed herein. The wireless sensor is capable of transmission of measurement values at a periodic rate, wherein the transmission rate is varied or non-varied. An amplifier varies a power transmission to the antenna based on a real-time soil conductivity value of a soil area and a real-time soil dielectric constant value of a soil area to improve a communication range and communication reliability of the antenna.

FIELD OF THE INVENTION [0001] The present invention relates to an oil recovery process, and more particularly to a method of recovering oil from subterranean hydrocarbon deposits using horizontal wells and in situ combustion. BACKGROUND OF THE INVENTION [0002] There are many oil recovery processes of the prior art employed for the production of oil from subterranean reservoirs. Some of these use vertical wells or combine vertical and horizontal wells. Examples of pattern processes are the inverted 7-spot well pattern that has been employed for steam, solvent and combustion-based processes using vertical wells, and the staggered horizontal well pattern of U.S. Pat. No. 5,273,111 which has been employed (but limited to) a process using steam injection. [0003] U.S. Pat. No. 5,626,191 to Toe-to-Heel Air Injection (THAI) discloses a repetitive method whereby the vertical segment of a vertical-horizontal producer well is subsequently converted to an air injection well, to assist in mobilizing oil for recovery by an adjacent horizontal well, which is subsequently likewise converted into an air injection well, and the process repeated. [0004] U.S. Pat. No. 6,167,966 employs a water-flooding process employing a combination of vertical and horizontal wells. [0005] U.S. Pat. No. 4,598,770 (Shu et al, 1986) discloses a steam-drive pattern process wherein alternating horizontal injection wells and horizontal production wells are all placed low in a reservoir. In situ combustion processes are not contemplated. [0006] Joshi in Joshi, S. D., “A Review of Thermal oil Recovery Using Horizontal wells”, In Situ, 11(2 &3), 211-259 (1987), discloses a steam-based oil recovery process using staggered and vertically-displaced horizontal injection and production wells pattern. A major concern is the high heat loss to the cap rock when steam is injected at the top of the reservoir. [0007] U.S. Pat. No. 5,273,111 (Brannan et al, 1993) teaches a steam-based pattern process for the recovery of mobile oil in a petroleum reservoir. A pattern of parallel offset horizontal wells are employed with steam injectors. The horizontal sections of the injection wells are placed in the reservoir above the horizontal sections of the production wells, with a horizontal production well drilled into the reservoir at a point below the injection wells, but intermediate said injection wells. Steam is injected on a continuous basis through the upper injection wells, while oil is produced through the lower production wells. Neither in situ combustion nor line drive processes are taught. [0008] U.S. Pat. No. 5,803,171 (McCaffery et al, 1998) teaches an improvement of the Brennan patent wherein cyclic steam stimulation is used to achieve communication between the injector and producer prior to the application of continuous steam injection. In situ combustion processes are not mentioned. [0009] U.S. Pat. No. 7,717,175 (Chung et al, 2010) discloses a solvent-based process utilizing horizontal well patterns where parallel wells are placed alternately higher and lower in a reservoir with the upper wells used for production of solvent-thinned oil and the lower wells for solvent injection. Gravity-induced oil-solvent mixing is induced by the counter-current flow of oil and solvent. The wells are provided with flow control devices to achieve uniform injection and production profiles along the wellbores. The devices compensate for pressure drop along the wellbores which can cause non-uniform distribution of fluids within the wellbore and reduce reservoir sweep efficiency. In situ combustion processes are not mentioned. [0010] WO/2009/090477 (Xai et al) discloses an in situ combustion pattern process wherein a series of vertical wells that are completed at the top are placed between horizontal producing wells that are specifically above an aquifer. This arrangement of wells is claimed to be utilizable for oil production in the presence of an aquifer. [0011] US Patent Application 2010/0326656 (Menard, 2010) discloses a steam pattern process entailing the use of alternating horizontal injection and production wells wherein isolated zones of fluid egress and ingress are created along the respective wellbores in order to achieve homogeneous reservoir sweep. The alternating wellbores may be in the same vertical plane or alternating between low and high in the reservoir, as in U.S. Pat. No. 5,803,171. Hot vapour is injected in the upper wells (e.g. steam). [0012] As seen from the above patents, steam-based oil recovery processes are commonly employed to recover heavy oil and bitumen from underground formations. For example, steam-assisted-gravity-drainage (SAGD) and cyclic steam injection are used for the recovery of heavy oil and cold bitumen. When the oil is mobile as native oil or is rendered mobile by some in situ pre-treatment, such as a steam drive process, the thus-mobilized oil can then drain downwardly by gravity and be collected by a horizontal collector well. [0013] A serious drawback of steam drive processes is the inefficiency of generating steam at the surface because a considerable amount of the heat generated by the fuel is lost without providing useful heat in the reservoir. Roger Butler, in his book “Thermal Recovery of oil and Bitumen', p. 415,416, estimates the thermal efficiency at each stage of the steam-injection process as follows: steam generator, 75-85%; transmission to the well, 75-95%” flow down the well to the reservoir, 80-95%; flow in the reservoir to the condensation front, 25-75%. It is necessary to keep the reservoir between the injector and the advancing condensation front at steam temperature so that the major energy transfer can occur from steam condensing at the oil face. In conclusion, 50% or more of the fuel energy can be lost before heat arrives at the oil face. The energy costs based on BTU in the reservoir are 2.6-4.4 times lower for air injection compared with steam injection. Several other drawbacks occur with steam-based oil recovery processes: natural gas may not be available to fire the steam boilers, fresh water may be scarce and clean-up of produced water for recycling to the boilers is expensive. In summary, steam-based oil recovery processes are thermally inefficient, expensive and environmentally unfriendly. [0014] Improved efficiency, shortened time on initial return on investment (i.e. quicker initial oil recovery rates to allow more immediate return on capital invested), and decreased initial capital cost, in various degrees, are each areas in the above methods which may be improved. SUMMARY OF THE INVENTION [0015] The present invention overcomes problems with the prior art steam-injection method of inter alfa U.S. Pat. No. 5,273,111 (Brannan) wherein reservoir heating is accomplished by the injection of large quantities of steam, typically under high pressure. Such prior art method has the drawbacks of needing to provide large and costly steam-generating equipment at surface, and as noted below is thermally inefficient in transferring heat to oil within the reservoir in order to achieve the necessary reduction in viscosity to be able to produce oil from a viscous oil reservoir. [0016] Thus substantial costs are further incurred in steam recovery methods which use steam to heat oil in heating the large quantities of steam needed, over and above the captical costs of acquiring, shipping, and assembling the necessary steam generating equipment in the form of boilers, burners, and associated piping. [0017] Moreover, although in situ combustion oil recovery techniques such as that disclosed in U.S. Pat. No. 5,626,191 are known, such typically involve a progression of a combustion front perpendicular to and along a horizontal collector well, which combustion front at any instant is travelling from a point along the horizontal production well. Accordingly, such prior art in situ combustion recovery method does not allow production of oil from within the underground formation simultaneously along an entire horizontal length of a production well. [0018] Advantageously, the applicant has created a method of recovering oil from within an underground formation, which is able to incorporate in a particular manner in situ combustion for generating heat (and thus unlike U.S. Pat. No. 5,273,111 does not require costly steam-generating equipment at surface and injection of steam), and which further, unlike prior art in situ recovery methods such as U.S. Pat. No. 5,626,191, is able to simultaneously utilize in situ heating and importantly attain production of oil from within a formation along an entire length of a horizontal collector well (or wells), and is able to have relatively high initial oil recovery rates. [0019] Specifically, the method of the present invention has been experimentally proven, in certain conditions as discussed later herein, to achieve a higher initial oil recovery rate than either the staggered well method of oil recovery using steam injection as taught in U.S. Pat. No. 5,273,111 [hereinafter the “staggered steam” method] and which disadvantageously need have costly steam generating equipment at surface], or a “crossed well” method of oil recovery which similarly uses in-situ combustion, the latter being a non-public method of oil recovery conceived by the inventor herein and in many respects itself an improvement, in certain respects and to varying degrees, over prior art methods and configurations. [0020] Specifically, for a comparable volumetric sweep area and identical total cumulative oil recovery in regard to a subterranean underground reservoir (formation), the staggered well (air injection) method of the present invention has been experimentally shown, under certain conditions as discussed herein, to provide a greater initial rate of recovery of oil than the “staggered steam” method or the “crossed well” method. Thus using the method of the present invention a greater and more rapid initial return on investment may be achieved. [0021] For oil companies incurring large expenditures in developing subterranean reservoirs, the ability to utilize a method which will generate revenue quickly and thereby permit quicker “pay-down” of initial expenses incurred with regard to search, locating, and acquiring, and initially drilling wells in a hydrocarbon-bearing formation is a significant advantage. The time in which a return on investment may be realized is frequently a very real and substantial consideration as to whether the investment in such a capital project is or can ever be made in the first place. [0022] Accordingly, in one broad embodiment of the oil recovery process of the present invention, such method comprises a continuous in situ combustion process using solely horizontal wells for injection of an oxidizing gas and for the simultaneous production of oil, using a symmetrical array of laterally and vertically offset (i.e. alternately ‘staggered’) parallel horizontal injection and production wells. [0023] More particularly, in one broad embodiment of the oil recovery method of the present invention such method comprises the steps of: [0024] (i) drilling a pair of parallel, spaced-apart, upper horizontal wells within said hydrocarbon-containing reservoir, substantially coplanar with each other; [0025] (ii) drilling, relatively low in said reservoir, a lower horizontal well situated below said upper horizontal wells and positioned substantially parallel to and intermediate said pair of upper horizontal wells; [0026] (iii) injecting an oxidizing gas into each of said upper horizontal wells and injecting said oxidizing gas into said reservoir via apertures in each of said pair of upper horizontal wells; [0027] (iv) igniting said oxidizing gas and hydrocarbons then contained within said formation and causing oil in said formation to become heated; [0028] (v) recovering oil which has become heated and which has migrated downwardly in said subterranean reservoir, in said lower horizontal well; and [0029] (vi) recovering said oil from said lower horizontal well to surface. [0030] Such method meets the commercial need of having relatively low energy costs (in that a separate supply of fuel for boilers to generate steam is not needed), and has lower initial capital start-up costs due to lack of need to acquire steam-generating equipment. Moreover, as set out below, such novel method for recovering hydrocarbons from a subterranean formation has a high initial oil recovery rate which is a significant advantage in allowing income generated from the produced oil to be more quickly applied against the significant expenses of locating, acquiring, and developing a suitable hydrocarbon containing deposit. [0031] In a further preferred method of the present invention, such method may comprise the further steps of: [0032] (a) drilling a further upper horizontal well within an upper region of said hydrocarbon-containing reservoir substantially parallel to and laterally spaced apart from said upper horizontal wells; [0033] (b) drilling a further lower horizontal well intermediate said further upper horizontal well and a nearest of said previously-drilled upper horizontal wells, said lower horizontal well positioned below said upper horizontal wells and positioned substantially parallel therewith; [0034] (c) injecting said oxidizing gas into said further upper horizontal well and into said nearest of said previously-drilled upper horizontal wells so as to thereby inject said oxidizing gas into said reservoir via a plurality of apertures in both said further upper horizontal well and said nearest of said upper horizontal wells; [0035] (d) collecting oil which has become heated as a result of heat being produced during combustion of said oxidizing gas and hydrocarbons in said reservoir and which oil has migrated downwardly in said subterranean reservoir, in said further lower horizontal well; [0036] (e) recovering said oil from said further lower horizontal well to surface. [0037] In a further preferred embodiment, such above method may be used to progressively recover oil from an underground formation in a “line drive” manner. Accordingly, in such “line drive” embodiment, above steps (a)-(e) are successively repeated to thereby progress in a linear direction with drilled horizontal wells so as to progressively recover oil in said linear direction from said underground hydrocarbon reservoir. [0038] The distance between the parallel lower horizontal wells, the upper horizontal wells, as well as the respective upper and lower well lengths, will all depend upon specific reservoir properties. Such distances can, however, be adequately optimized by a competent reservoir engineer. The lateral spacing between the horizontal wells can be 25-200 meters, preferably 50-150 meters and most preferably 75-125 meters. The length of the horizontal well segments can be 50-2000 meters, preferably 200-1000 meters and most preferably 400-800 meters. The vertical distance between the upper horizontal injection wells and the lower horizontal producer wells is typically dictated by the depth of the oil bearing seam within an underground formation, with such depths typically varying between 2 m to 50 m, but sometimes greater, with the upper horizontal injection wells being located in an upper region of the hydrocarbon-containing seam within the underground formation, and the lower horizontal production wells located along a lower base of the oil-containing seam within the underground formation. [0039] In each of the above methods it is further contemplated that hot combustion gases which are produced upon ignition of the hydrocarbons and oxidizing gas will travel from a high pressure area within the formation (i.e. typically proximate the upper horizontal injector wells) to a low pressure area (i.e. typically proximate the lower producer wells), and be further drawn into and recovered from said lower horizontal well along with said oil to surface. [0040] In a homogeneous reservoir using the method of the present invention it is beneficial for high reservoir sweep efficiency to deliver the injectant equally to perforations in a well liner within the upper horizontal wells, and to utilize as best as possible equal oil entry rates at each perforation along well liner(s) contained within the lower horizontal (production) well. Considering that all horizontal wells typically have a ‘toe’ at a distal end thereof, and a ‘heel’ at a proximal end thereof where the horizontal well joins the downwardly-drilled vertical segment of a horizontal-vertical well pair, in a refinement of the present invention the upper horizontal wells are drilled so that the respective “heels” of the parallel upper horizontal (injection) wells are all on a same side of the reservoir, such side being opposite a side of the reservoir at which the respective heel (proximal end) of the adjacent laterally spaced apart lower horizontal production wells is situated. In other words, the vertical wells which are connected to each of the respective upper horizontal wells are on opposite sides of the reservoir that the vertical wells for the corresponding lower horizontal wells (and their associated respective heel portions) are located. In such manner oxidizing gas which is injected in the upper horizontal well (the pressure thereof being highest at the “heel” [i.e. proximal] end of such upper horizontal wells) has less of a tendency to “short-circuit” directly to the low pressure portion of the lower horizontal well which is at the heel (proximal) end of such lower horizontal well, then located on the opposite side of the reservoir. [0041] Accordingly, in a further preferred embodiment of the present invention the step of injecting said oxidizing gas into said upper injection wells comprises the step of injecting said oxidizing gas into proximal ends of said upper horizontal wells, such proximal ends situated on a side of said underground formation, and said step of withdrawing oil from said lower horizontal well comprises withdrawing said oil from a proximal end of said lower horizontal well which is situated on another side of said reservoir opposite said side at which said proximal ends of said upper horizontal wells are situated. [0042] In an alternative embodiment which accomplishes the same purpose of reducing the tendency of “short circuiting” and advantageously allows both the injection and production wells to be drilled with their respective vertical portions (i.e. proximal ends) situated on the same side of the reservoir (i.e. a drilling pad for drilling each of the upper and lower wells can thereby remain on the same side of the reservoir and need not be moved back and forth to opposite sides of the reservoir when drilling lower wells and then upper wells), internal tubing may be used in the upper injection wells and/ or the lower production well(s). [0043] Specifically, in an alternative embodiment where tubing is employed in the upper horizontal wells, such tubing is provided with an open end proximate the distal end of the upper horizontal wells. Such allows transfer of the point of injection of the oxidizing gas (and thus the high pressure point in such upper horizontal well) to the distal end thereof. In such manner the high pressure source in the upper horizontal injection wells will be at an end of the reservoir opposite the low pressure toe of the producing wells, thereby forcing heated gas to travel a longer distance through the formation and thereby more effectively heat and free oil trapped in the formation, and further avoid “short-circuiting” of combustion gases. Heated gases are thus caused to travel through the formation and be collected by the low pressure area at the toe of the production well. Such configuration has the benefit of permitting drilling pads to all be located on the same side of the reservoir. [0044] Similarly, where tubing is employed in the lower horizontal wells, such tubing is provided with an open end proximate the distal end of the lower horizontal wells, with the proximal ends of each of the upper production wells, and the lower production well(s) situated on the same side of the reservoir. Such tubing allows transfer of the point of recovery of the produced oil (and thus transfer of the lowest pressure point in such lower horizontal well) to the distal end of the lower production well. In such manner the high pressure source in the upper horizontal injection wells will again be at a proximal end thereof, namely at an end of the reservoir opposite the low pressure distal (toe) portion of the producing wells, thereby forcing heated gas to travel a longer distance through the formation and thereby more effectively heat and thus free oil trapped in the formation, and avoid “short-circuiting” of heated gas. Such configuration, wherein each of the proximal ends of the upper injector wells and lower production wells are on the same side of the reservoir, again has the benefit of permitting all drilling pads to be located on the same side of the reservoir. [0045] As an alternative to the employment of configurations which transpose (reverse) the respective heel and toe portions of adjacent horizontal wells or alternatively use internal tubing in the injector well, the uniform delivery of gas along the length of the injection well and uniform collection in the production well may be obtained, or further enhanced, by varying the number and size of perforations along the well liner in an injector well, to balance the pressure drop along the well. A pressure-drop-correcting perforated tubing can be placed inside the primary liner. This has the advantage of utilizing gas flow in the annular space to further assist the homogeneous delivery of gas. [0046] Specifically, the number and size of perforations of the well liner in a injector producer well may progressively increase from the heel portion to the toe portion thereof, in order to more uniformly distribute such oxidizing gas to the reservoir along the entire length of the upper injector wells, and assist in preventing “fingering” of injectant gas directly into production wells. [0047] Accordingly, in one such embodiment each of said upper horizontal injector wells has a well liner in which said plurality of apertures are situated, and wherein a size of said apertures or a number of said apertures within said well liner progressively increases from a proximal end to a distal end of said upper horizontal wells, and said oxidizing gas is injected into said proximal end of each of said upper horizontal wells. [0048] Alternatively, or in addition, said lower horizontal well may be provided with a well liner in which a plurality of apertures are situated, and wherein a size of said apertures or a number of said apertures within said well liner progressively increases from a proximal end to a distal end of said lower horizontal well, in order to more uniformly collect mobile oil along substantially the entire length of the production well, and to assist in preventing “fingering” of injectant gas directly into production wells. [0049] Accordingly, in a further preferred refinement to better allow the upper production wells to more uniformly distribute the oxidizing gas to the formation to avoid “fingering” or “short circuiting” of high pressure oxidizing gas directly to production wells, and to further allow more uniform and efficient collection of oil from the formation by the lower production wells, each of said proximal ends of the upper horizontal injection wells are situated on the same side of the reservoir as the proximal ends of each of the lower horizontal producer wells, and [0050] (i) each of said upper horizontal injector wells has a well liner in which said plurality of apertures are situated, and wherein a size of said apertures or a number of said apertures within said well liner progressively increases from a proximal end to a distal end of said upper horizontal wells, and said oxidizing gas is injected into said proximal end of each of said upper horizontal wells; and [0051] (ii) said lower horizontal well(s) may be provided with a well liner in which a plurality of apertures are situated, and wherein a size of said apertures or a number of said apertures within said well liner progressively increases from a proximal end to a distal end of said lower horizontal well. [0052] The outside diameter of the horizontal well liner segments can be 4 inches to 12 inches, but preferably 5-10 inches and most preferably 7-9 inches. The perforations in the horizontal segments can be slots, wire-wrapped screens, Facsrite™ screen plugs or other technologies that provide the desired degree of sand retention. [0053] The injected gas may be any oxidizing gas, including but not limited to, air, oxygen or mixtures thereof. In a preferred embodiment the oxidizing gas is air but is further diluted with a varying quantity a non-oxidizing gas such as carbon dioxide or steam, to thereby reduce (per injected volume) the relative concentration of oxygen in such quantity of injected gas, thereby allowing control over the temperature produced during combustion by decreasing the amount of oxygen allowed to combust with hydrocarbon within the formation. [0054] Alternatively, or in addition, such oxidizing gas contains water vapour, or water droplets, or water which turns to steam, which condenses when moving downwardly in the formation and which releases heat in the latent heat of condensation thereby assisting in transferring heat to oil in the lower portion of the formation and allowing such oil to become mobile and drain downwardly into the lower horizontal collector well. [0055] The maximum oxidizing gas injection rate will be limited by the maximum gas injection pressure which must be kept below the rock fracture pressure, and will be affected by the length of the horizontal wells, the reservoir rock permeability, fluid saturations and other factors. [0056] The use of a numerical simulator such as that used in the examples below is beneficial for confirming the operability and viability of the design of the present invention for a specific reservoir, and can be readily conducted by reservoir engineers skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS [0057] In the accompanying drawings, which illustrate one or more exemplary embodiments and are not to be construed as limiting the invention to these depicted embodiments: [0058] FIG. 1 shows a perspective schematic view of a subterranean hydrocarbon-containing, showing the “staggered well” method of the present invention, having a plurality of upper horizontal injection wells and a plurality of alternatingly-spaced lower horizontal production wells situated low in the reservoir, which uses air injection and in-situ combustion to provide heat to mobilize oil in the formation ; [0059] FIG. 2 shows a cross-sectional view of FIG. 1 taken along plane “A-A” in the direction of arrows “A-A; [0060] FIG. 3 is a perspective view of the staggered well method of the present invention, after a “line drive” method is employed; [0061] FIG. 4( i )-( iii ) is a series of three cross-sectional view of FIG. 1 taken along plane “A-A” in the direction of arrows ‘A-A’, showing a progression of oil recovery steps during successive time intervals during the carrying out of the staggered well “line drive” embodiment of the present invention; [0062] FIG. 6 shows a perspective schematic view of an alternative “staggered well” method of the present invention, wherein the proximal ends of each of the upper and lower horizontal wells are located on the same side of the underground hydrocarbon reservoir; [0063] FIG. 6 is an enlarged perspective view of various upper and lower horizontal wells, showing a manner of employing tubing in each of the upper horizontal wells in accordance with an embodiment of the method of the present invention; [0064] FIG. 7 is an enlarged perspective view of various upper and lower horizontal wells, showing a manner of employing tubing in the lower horizontal well(s) in accordance with an embodiment of the method of the present invention; [0065] FIG. 8 is an enlarged perspective view of various upper and lower horizontal wells, showing a manner of employing progressively increasing number of apertures in each of the well liners of the upper and lower horizontal wells, in accordance with a further alternative embodiment of the method of the present invention; [0066] FIG. 9 is an enlarged perspective view of various upper and lower horizontal wells, showing a manner of employing progressively increasing sizes of apertures in each of the well liners of the upper and lower horizontal wells, in accordance with a further alternative embodiment of the method of the present invention; [0067] FIG. 10 is an alternative oil recovery method, not part of the present invention herein, and is the configuration of the alternative method used for comparison purposes in comparing relative oil recovery factor of such method to that of the present invention, as shown in FIG. 11 ; and [0068] FIG. 11 is a graph showing the percentage of oil recovered from a formation, using the method of the present invention (graph “X”); the method of FIG. 10 (graph “Y”); and a method using staggered wells not forming part of the invention which utilizes steam injection for heating instead of oxidizing gas injection and in situ combustion for heating (graph “Z”). DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS [0069] FIGS. 1-3 & 5 show a developed subterranean formation/reservoir 22 using an embodiment of the “staggered well” method of oil recovery of the present invention (hereinafter the “Staggered Well” method). In such “Staggered Well” method parallel upper horizontal injection wells 1 , 1 ′, & 1 ″ of each of length “b” are placed parallel to each other in mutually spaced relation, all situated high in a hydrocarbon-containing portion 20 of thickness “a” which forms part of subterranean formation/reservoir 22 situated below ground-level surface 24 . Parallel horizontal, spaced apart lower horizontal production wells 2 , 2 ′ & 2 ″ of similar length “b” are respectively placed low in the reservoir 22 , both below and approximately intermediate respective injection wells 1 , 1 ′, and 1 ″, to make a well pattern array of staggered and laterally separated parallel and alternating horizontal gas injection wells 1 , 1 ′, & 1 ″ and oil production wells 2 , 2 ′ & 2 ″ as shown in FIGS. 1-3 & 5 . [0070] The hydrocarbon-containing reservoir 22 shown in FIG. 1 possesses two and one-half injection wells 1 , 1 ′, & 1 ″ and two and one-half production wells 2 , 2 ′, & 2 ″ (edge injection well 1 and edge production well 2 ″ each respectively constituting one-half well) for a total of five horizontal wells in the pattern. Conducting three repetitions of the method of FIG. 1 requires fifteen horizontal wells, as shown in FIG. 3 . [0071] The lateral spacing “c” of the upper horizontal injection wells 1 , 1 ′, & 1 ″ and the lower horizontal injection wells 2 , 2 ′ & 2 ″ is preferably uniform. [0072] In the embodiment of the Staggered Well method shown in FIG. 1 , the vertical segments 8 of the horizontal injection wells 1 , 1 ′ & 1 ″ are at opposite sides of reservoir 22 compared with the vertical segments 9 of the horizontal production wells 2 , 2 ′ & 2 ″, each vertical segment 8 of associated respective horizontal well 1 , 1 ′ & 1 ″ extending upwardly to surface 24 and likewise each vertical segment 9 of associated respective horizontal production well 2 , 2 ′ & 2 ″ extending upwardly to surface 24 . (For purposes of clarity, only vertical segments portions 8 , 9 of the respective vertical wells extending to surface 24 are depicted in FIG. 1 ). Accordingly, the vertical segments 8 of the each of injection wells 1 , 1 ′, & 1 ″ in the embodiment of the method shown in FIG. 1 are thus longitudinally offset by the well length ‘b’ from the respective vertical segments 9 (and corresponding associated horizontal production wells 2 , 2 ′ & 2 ″. [0073] Vertical segments 9 and associated horizontal production wells 2 , 2 ′, & 2 ″ which are situated intermediate horizontal injection wells 1 , 1 ′ & 1 ″, are laterally offset from horizontal injection wells 1 , 1 ′ & 1 ″ and associated vertical segments 8 a distance “c”. The reason for such lateral offset “c” is to eliminate or at least minimize “short-circuiting” of injected oxidizing gas directly from injection wells 1 , 1 ′, & 1 ″ into production wells 2 , 2 ′ & 2 ″ as explained above. [0074] The pattern shown in FIG. 1 can be extended indefinitely away from the face 3 and/or the face 6 as desired to cover a specific volume of oil reservoir 22 . In further phases of the reservoir development, as shown in FIG. 3 , an additional array of injections wells 1 , 1 ′, & 1 ″ and production wells 2 , 2 ′ & 2 ″ are drilled adjacent to the first array of FIG. 1 , and such process repeated, eventually exploiting the entire reservoir 22 . [0075] Referring to FIG. 1 showing one embodiment of the invention, horizontal injector wells 1 & 1 ′ and production well 2 are drilled, in a preferred embodiment each being provided with well liner segments 30 situated in each of horizontal wells 1 , 1 ′, & 1 ″ and 2 , 2 ′ & 2 ″. Well liner segments 30 each contain apertures or slots 24 from which an oxidizing gas, which may further include carbon dioxide and/or steam, is injected into formation 22 via an injector wells 1 , 1 ′. [0076] Upon ignition of the so-formed oxidizing gas and hydrocarbon mixture in the reservoir 22 , and in particular in the oil-bearing seam 20 thereof, heated oil and combustion gas (not shown) contained with reservoir partition segments 50 a, 50 b flow and are drawn downwardly due to lower pressures toward production well 2 , and are drawn into and enter production well 2 via apertures 24 therein. Thereafter such collected oil and combustion gases (not shown) are drawn to surface 24 via gas lift or pump means. [0077] In the case of horizontal production wells 2 , 2 ′ & 2 ″, well liners 30 and the apertures 24 therein may take the form of slotted liners, wire-wrapped screens, FacsRite™ well liners having sand screen plugs, or combinations thereof, to reduce the flow of sand and other undesirable substances such as drill cuttings from within the formation 22 into production wells 2 , 2 ′ & 2 ″. [0078] The Staggered Well (Air Injection) method may utilize a “line drive” configuration, by drilling another injection well 1 ″ and a corresponding production well 2 ′, as shown in FIG. 1 . Such method is better illustrated in FIG. 4( i )-( iii ), in which three successive phases are implemented and depicted. In this regard, FIG. 4 shows views on section A-A of FIG. 1 , at successive respective time intervals (i), & (iii), showing a method of causing a “line drive” of oil recovery in the direction “Q”, and in particular the remaining portions of oil bearing seam 20 which continue to possess oil and thus illustrates the progressive recovery of oil from oil bearing seam 20 . Specifically, as seen from the first phase [ FIG. 4( i )], the injector wells 1 , 1 ′, and 1 ″, and producer well 2 and 2 ′ are first drilled, and after injection of oxidizing gas into formation 22 via injection wells 1 , 1 ′ & 1 ″ and ignition of the so-formed mixture of oxidizing gas and hydrocarbons in reservoir 22 , production of oil from well 2 and 2 ′ is commenced, causing depletion of oil from oil bearing seam 20 , as shown in FIG. 4( i ). Thereafter in a second phase [ FIG. 4( ii )], a further producer well 2 ″ is drilled, and injection and production commenced respectively in regard to injector wells 1 , 1 ′, and production well 2 ′. In a third phase [ FIG. 4( iii )], a fourth injector 1 ′″ and a fourth producer 2 ′″ are drilled, with production ceasing from production well 2 , and injection and production commenced in injection well 1 ′″ and production well 2 ′″ respectively. The process may be continued indefinitely as shown in FIG. 3 , until reaching an end of reservoir 22 . [0079] Alternatively, as mentioned above, such “Staggered Well (Air Injection)” method may simply consist of simultaneously drilling a set number of injector wells (e.g. such as three wells 1 , 1 ′, & 1 ″) and a corresponding number of producer wells (e.g. such as three wells 2 , 2 ′ & 2 ″), so as to produce the “pattern” of staggered wells of wells 1 , 1 ′, & 1 ″ and 2 , 2 ′ & 2 ″ shown in FIG. 1 , and produce oil from reservoir partition segments 50 a,b , 50 c,d, and 50 e. Such pattern may be repeated as necessary, as shown in FIG. 3 through well partition segments 50 f - 50 o , in order to exploit an entire reservoir 22 . [0080] FIG. 5 shows an alternate embodiment of the Staggered Well (Air Injection) method of unregistered trademark of Absolute Completion Technologies for well liners having sand screens therein the present invention, where each of vertical segments 8 , 9 of corresponding horizontal wells 1 , 1 ′, & 1 ″ and 2 , 2 ′, & 2 ″ respectively, are drilled on the same side 4 of reservoir 22 . Advantageously, as discussed above, such configuration allows a drilling pad for drilling wells 1 , 1 ′, & 1 ″ and 2 , 2 ′, & 2 ″ to remain on the same side 4 of reservoir 22 , thus increasing the speed and ease by which the wells 1 , 1 ′, & 1 ″ and 2 , 2 ′, & 2 ″ may be drilled. [0081] When vertical segments 8 , 9 of corresponding horizontal wells 1 , 1 ′, & 1 ″ and 2 , 2 ′, & 2 ″ respectively are drilled on the same side 4 of reservoir 22 as shown in FIG. 5 , to better and more uniformly inject oxidizing gas into formation 22 via horizontal wells 1 , 1 ′, & 1 ″, and/or to more uniformly collect oil in horizontal wells 2 , 2 ′, & 2 ″, it is preferred to use tubing 40 in the manner described below. [0082] Specifically, in a first embodiment employing tubing 40 , tubing 40 is inserted in upper horizontal injection wells 1 ′, 1 ″, 1 ′″ of FIG. 1 and in all injection wells, if desired. FIG. 6 shows an exemplification of such concept using tubing 40 in two adjacent injection wells 1 ′, 1 ″. Such tubing 40 preferentially extends from the heel 43 at the vertical portion 8 of each of wells 1 ′, 1 ″ to the toe portion 44 of each of such wells 1 ′, 1 ″. Gaseous air “G” is injected into tubing 40 , which air “G” thereafter flows into injection wells 1 ′, 1 ″ and thereafter into oil bearing seam 20 of formation 22 via apertures 24 in well liner segments 30 as shown in FIG. 6 . Heated oil “O” flows into apertures 24 in well liners 30 of producer well 2 ′, and is thereafter produced to surface 24 (see FIG. 1 ) [0083] Alternatively, in a second alternative embodiment employing tubing 40 , tubing 40 is inserted in lower production wells 2 , 2 ″, 2 ′″, and 2 ″″ of FIG. 1 and in all injection wells, if desired. FIG. 7 shows an exemplification of such concept using tubing 40 in one production well 2 ′. Such tubing 40 preferentially extends from the heel 43 at the vertical portion 9 of production 2 ′ to the toe portion 44 thereof, as shown in FIG. 7 . Oil “O” is withdrawn from toe 44 of production well 2 ′ via tubing 40 , such oil “O” entering apertures 24 in well liners 30 in production well 2 ′, and is thereafter produced to surface 24 (see FIG. 1 ). [0084] Alternatively, instead of using tubing 40 within the method of the present invention to more uniformly heat the oil in the formation, prevent short-circuiting between injector wells 1 , 1 ′, 1 ′″, and producer wells 2 , 2 ′, 2 ″, and 2 ″, and thereby better collect oil “O” in horizontal wells 2 , 2 ′, & 2 ″, it is contemplated that either the number or size of apertures 24 in well liners 30 in production wells 2 , 2 ′, 2 ″, be progressively increased from heel 42 to toe 44 . [0085] Specifically, FIG. 8 shows one such embodiment being utilized in respect of a single production well 2 ′, where the number of apertures 24 in well liners 30 in production wells 2 , 2 ′, 2 ″, is progressively increased from heel 42 to toe 44 . [0086] FIG. 9 shows another alternative embodiment of such concept being utilized in respect of a single production well 2 ′, where the size of apertures 24 in well liners 30 in production wells 2 , 2 ′, 2 ″, is progressively increased from heel 42 to toe 44 . EXAMPLES [0087] Extensive computer simulation of processes for the recovery of mobile oil were undertaken using the STARS™ Thermal Simulator 2010.12 provided by the Computer Modelling Group, Calgary, Alberta, Canada. [0088] The model dimensions used in comparative Examples 1-3 below in number of grid blocks were 20×50×20 and the grid block sizes were respectively 5.0 m, 5.0 m and 1.0 m, resulting in the same total reservoir volume in each case of 500,000 m 3 (i.e. 100 m×250 m×20 m). [0089] The modelling reservoir used in each of comparative Examples 1-3 below contained bitumen at elevated temperature (54.4°) with high rock permeability. [0090] In each of comparative Examples 1-3 below, the total number of wells used for comparative purposes was the same. [0091] Specifically, for the Staggered Well (Air Injection) method, namely a method of the present invention (Example 1 below), a total of five wells were employed, namely 2.5 injection wells 1 , 1 ′, and 1 ″, and 2.5 production wells 2 , 2 ′, and 2 ″, keeping in mind that injection well 1 and production well 2 ″ which appear at the end of grid block 50 a and 50 e, respectively, are counted as half-wells. [0092] For the Staggered Steam configuration and method (e.g. as per FIG. 1 , but not using air injection or in situ combustion-see Example 2 below), a total of five wells consisting of 2.5 injection wells 1 , 1 ′, and 1 ″, and 2.5 production wells 2 , 2 ′, and 2 ″, again keeping in mind that injection well 1 and production well 2 ″ which appear at the end of grid block 50 a and 50 e , respectively, are counted as half-wells. [0093] With regard to the “crossed-wells” configuration/method as shown in FIG. 10 (see Example 3, below), a similar total of five wells were used, namely two (2) injection wells 1 ′, 1 ″, and three (3) production wells 2 , 2 ′, 2 ″, and 2 ′″, again keeping in mind that production well 2 and production well 2 ″″ which each appear at the end of the grid block shown in FIG. 10 are counted as half-wells. [0094] With regard to each comparative model described in Examples 1-3 below, each model received an identical amount of gaseous injection, namely a total of 50,000 m 3 /day, with Examples 1 and 3 receiving air injection, and Example 2 receiving gaseous steam injection. [0095] For combustion simulations with air the reactions used: 1. 1.0 Oil→0.42 Upgrade (C 16 H 34 )+1.3375 CH 4 +29.6992 Coke 2. 1.0 Oil+13.24896 O 2 →5.949792 H 2 O+6.0 CH 4 +9.5 CO 2 +0.5 CO/N2+27.3423 Coke 3. 1.0 Coke+1.2575 O 2 →0.565 H 2 O+0.95 CO 2 +0.05 CO/N2 [0099] In order to improve sweep efficiency, the transmissibility of the oil production wells 2 , 2 ′, 2 ″, and 2 ′″ was varied monotonically from 1.0 at the toe to 0.943 at the heel. Practically speaking, as described herein, such diminished transmissibility of the oil along the length of a production well 2 , 2 ′, 2 ″, and/or 2 ″″ can be accomplished by progressively decreasing either the aperture 24 size, or number of apertures 24 of sequential slotted liner segments 30 from toe 44 to heel 42 of production wells 2 , 2 ′, 2 ″, or 2 ″″ (see for example FIG. 8 , FIG. 9 , respectively). [0100] Additional reservoir properties for each of the reservoirs 22 and comparative methods of oil extraction modelled in Examples 1-3 below were set out in TABLE 1, below: [0000] TABLE 1 Reservoir properties, oil properties and well control. Parameter Units Value Reservoir Properties Pay thickness m 20 Porosity % 30 Oil saturation % 80 Water saturation % 20 Gas mole fraction fraction 0.263 H. Permeability mD 5000 V. Permeability mD 3400 Reservoir temperature ° C. 54.4 Reservoir pressure kPa 3000 Rock compressibility /kPa  3.5E−5 Conductivity J/m.d.C  1.5E+5 Rock Heat capacity J/m 3 -C 2.35E+6 Oil Properties Density Kg/m 3 1009 Viscosity, dead oil @ 20 C. cP 77,000 Viscosity, in situ cP 1139 Average molecular weight oil AMU 598 Average molecular weight AMU 224 Upgrade Oil mole fraction Fraction 0.737 Compressibility /kPa 1.06E+3 The wells were controlled using the following parameters: Maximum air injection pressure kPa 7,000 Horizontal well length m 500 Producer BHP minimum kPa 2600 Total air or steam injection rate m 3 /d 50,000 Example 1 Staggered Well (Air Injection) Method [0101] FIGS. 1 and 4( i )-( iii ) depict a method of oil recovery (using air injection and in situ combustion heating) of the present invention, and in particular depict the method used in Example 1 [Staggered Well (Air Injection)], utilizing a total air injection volume of 50,000 m 3 /d. [0102] For the Staggered Well (Air Injection) Method as shown in FIGS. 1 , 2.5 injection wells 1 , 1 ′, and 1 ″, and 2.5 production wells 2 , 2 ′, and 2 ′ as part of grid blocks 50 a - 50 e , were all simultaneously drilled, for a total of five wells. The reservoir thickness ‘a’ was 20 m and the well offset ‘c’ was 50 m for each grid block 50 a - 50 o . Air injection rates were 10,000 m 3 /d for well 1 and 20,000 m 3 /d for each of injectors 1 ′ and 1 ″, for a total of 50,000 m 3 /d for the grid block pattern 50 a - 50 e. [0103] A summary of results, namely the Oil Recovery Factor over time (1,825 days=5 years) for Example 1, is shown in FIG. 11 as line ‘X’. Example 2 Crossed-Wells Method [0104] FIG. 10 shows an alternative method of oil recovery from a subterranean reservoir 22 , which is not the subject matter of this application but of another patent application of the within inventor and commonly assigned (hereinafter the “crossed wells” method). [0105] In the crossed-well method depicted in FIG. 10 , injector wells 1 , 1 ′ are perpendicularly disposed to the horizontal collection wells 2 , 2 ′, 2 ″, and 2 ′″. Specifically in this crossed-well method, parallel horizontal well injection wells 1 , 1 ′ are placed high in reservoir 22 , and parallel horizontal production wells 2 , 2 ′, 2 ″, & 2 ″ are placed low in reservoir 22 perpendicular to injection wells 1 , 1 ′. Horizontal Injection well 1 ′ is located distance ‘q’ (25 m) from the front edge of the model and injection well 1 is placed distance ‘q’ from the back side of reservoir 22 , namely with injectors 1 , 1 ′ separated by a distance ‘2 q’. The well length is “b”. The spacing of the horizontal production wells is “c”, for a total grid block volume of 500,000 m 3 . [0106] The air injection rate into the upper injection wells 1 , 1 ′ was 50,000 m31/d, divided equally between injector wells 1 , 1 ′. Air was injected continuously and oil, water and gas were produced continuously from the lower wells 2 , 2 ′, 2 ″ & 2 ″. [0107] A summary of results, namely the Oil Recovery Factor over time (1,825 days=5 years) for Example 2, is shown in FIG. 11 as line ‘Y’. Example 3 Staggered Steam Method [0108] Example 3 (method of FIG. 1 , but with hot steam injection instead of air injection and not employing in situ combustion) is not part of the present invention, and is only provided to illustrate the comparative efficiency with other oil recovery methods (e.g. Example 1 and Example 2). [0109] Saturated steam was injected continuously at the rate of 150, 300 and 300 m 3 /d (water equivalent—for a total of 50,000 m 3 /d gaseous equivalent) into injection wells 1 , 1 ′ and 1 ″ respectively, while production wells 2 , 2 ′ and 2 ″ were open to production. [0110] A summary of results of the Staggered Steam method, showing the Oil Recovery Factor over time (1,825 days=5 years) for Example 3, is shown in FIG. 11 as line ‘Y’. COMPARISON AND PROVEN ADVANTAGES [0111] Comparing lines ‘Y’ (Crossed-wells) and line “X” [the present invention, Staggered Wells (Air Injection) it is clear that at any selected time the oil recovery is higher with the present invention. [0112] Comparing line “Z” (Staggered Steam injection) with line “X” of the present invention [Staggered Wells (Air Injection) ] the benefit of higher early oil rate with the present invention is even greater. [0113] The higher Oil Recovery Factors at 2.4 years and 5.0 years of the present invention (Line “X”) show the significant financial advantage of the present invention considering the earlier return on investment in the form of earlier and greater oil recovery. Also, with a lower Air/Oil ratio than the steam injection method (Example 3), the present invention (Example 1) will carry lower air compression costs. Because of the thermal inefficiency of steam processes, the Staggered Steam process is not competitive. [0000] TABLE 2 Oil recovery Factors and energy requirements. Oil recovery Cumulative factor, % Oil Oil recovery Cumulative Relative Well 2.4-years 5-year, km 3 factor at Air/Oil energy Arrangement Line (874 days) (1827 days) 5-years, % Ratio cost Crossed Wells* “Y” 49.9 93.3 80.0 980 1.0 (Example 2 and FIG. 10)* Staggered Steam “Z” 40.7 98.2 82.7 N/A 2.2-4.4 Injection* (Example 3 and FIG. 1) Staggered Wells “X” 56.5 98.2 81.2 866 1.0 (Air Injection) (Example 1 and FIG. 1) *Does not form part of the invention claimed herein [0114] The scope of the claims should not be limited by the preferred embodiments set forth in the foregoing examples, but should be given the broadest interpretation consistent with the description as a whole, and the claims are not to be limited to the preferred or exemplified embodiments of the invention.

An in situ combustion process entailing the simultaneous production of oil and combustion gases that combines fluid drive, gravity phase segregation and gravity drainage to produce hydrocarbons from a subterranean oil-bearing formation, comprising initially injecting a gas through a pair of horizontal wells placed high in the formation and producing combustion gas and oil through parallel and laterally offset horizontal wells that are placed low in the formation intermediate the pair of horizontal wells placed high in the formation.

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit under 35 USC 119(a) of Korean Patent Application No. 10-2014-0107936 filed on Aug. 19, 2014 in the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference for all purposes. BACKGROUND [0002] 1. Field [0003] The following description relates to a photo sensor and to a photo sensor module configuring a UV sensor using poly silicon formed on a semiconductor substrate, which minimizes size of a chip by forming a passive device processing sensing signal in a vertical direction with a UV sensor. [0004] 2. Description of Related Art [0005] UV sensing has recently been incorporated in various portable products, such as, for example, smart phone and wearable devices, because of an increase in awareness of protecting people from UV exposure. Such products, which are equipped with a UV sensor, can signal alarm before an end-user harms his or her health during outdoor exercise by measuring accumulated UV exposure concentration. Moreover, a UV sensor in smart phones or wearable devices can operate functions such as, for example, proximity and motion control, and measure UV exposure concentration, heart rate, pulse frequency and blood oxygen level. [0006] Silicon photo diode is generally used as a UV sensor. U.S. Pat. No. 8,071,946 (Multi-function light sensor, registered on Dec. 6, 2011, hereinafter referred to as ‘prior document’) to Kita (“Kita”) is an example of a UV sensor which uses silicon photo diode. Kita is incorporated herein in its entirety by reference in the same manner as when each cited document is separately and specifically incorporated or incorporated in its entirety. [0007] Kita discloses a UV sensor manufactured based on a Silicon on Insulator (SOI) substrate structure. The UV sensor provides a SOI substrate 12 comprising a silicon oxide insulator film 16 and a silicon semiconductor layer 18 configured of single crystal silicon on a silicon substrate 14 . An ultraviolet ray sensing UV sensor is formed on the silicon semiconductor layer 18 configuring the SOI substrate 12 . A first photo diode and a second photo diode which sense other rays, are formed on a silicon substrate 14 to avoid overlap with a UV sensor. A silicon oxide insulator film separates a first photo diode, a second photo diode, and a UV sensor. [0008] A UV sensor with the above-mentioned structure has some problem. A UV sensor is manufactured formed on a silicon semiconductor layer of a SOI substrate. Moreover, any active device or passive device to process sensing signal is not formed on a lower UV sensor. [0009] This makes it difficult to reduce the size of an IC chip comprising a UV sensor and making it difficult to reduce the size of the smart phones or wearable devices smaller. [0010] Demand for a UV sensor, which can detect UV with high sensitivity while reducing manufacturing cost is increasing. The UV sensors known in the art are not capable of high sensitivity sensing function and being cheaper than a SOI substrate. SUMMARY [0011] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. [0012] The present disclosure provides a UV sensor which is based on poly silicon formed on a semiconductor substrate. [0013] The present disclosure minimizes size of an IC chip size by improving a structure forming a passive device perpendicular to a UV sensor. [0014] The present disclosure provides one sensor module to sense both UV and non-UV. [0015] In one general aspect there is provided a photo sensor module including a semiconductor substrate, a field oxide layer, formed on the semiconductor substrate, and a photo sensor including a photo diode formed on the field oxide layer. [0016] The photo sensor module may include a first WELL region and a second WELL region formed on the semiconductor substrate, a first source/drain region formed on the first WELL region and a second source/drain region formed on the second WELL region, an isolation layer formed between the first WELL region and the second WELL region, and a gate insulator film and a gate electrode formed on the first WELL region and another gate insulator film and another gate electrode formed on the second WELL region. [0017] The photo sensor module may include an insulator film formed on the field oxide layer and the gate electrodes, and a passivation layer formed on the insulator film. [0018] A part of the insulator film and the passivation layer may be removed, and a part of the photo diode is exposed to outside. [0019] The photo diode may include two or more doping region formed in a module form to sense UV. [0020] The photo diode may include a first doping region of high concentration, a second doping region of low concentration, doped in a different impurity from the first doping region, and a third doping region of high concentration, doped in an identical impurity as the second doping region. [0021] The photo diode may include a first doping region of high concentration, a second doping region of low concentration doped in an identical impurity as the first doping region, and a third doping region of high concentration doped in different impurity from the second doping region. [0022] The third doping region may be enlarged to contact the first source/drain region. [0023] In another general aspect there is provided a photo sensor module, including a semiconductor substrate, a field oxide layer, formed on the semiconductor substrate, a passive device, placed on the field oxide layer, at least one insulator film laminated on the field oxide layer, and a photo diode formed on the at least one insulator film above the passive device. [0024] The photo sensor module may include a WELL region, formed on the semiconductor substrate, and a doping region of high concentration, formed on the WELL region. [0025] The photo sensor module may include a metal wire formed on the insulator film, and a trench connecting the metal wire to the WELL region. [0026] The trench may be filled with one of tungsten (W), aluminum (Al), or copper (Cu). [0027] A doping region of the photo diode and a source/drain doping region of the WELL region may be connected with a trench. [0028] The metal wire may surround a portion of the photo diode and a barrier metal may be formed below the metal wire. [0029] The barrier metal may include one of titanium(Ti), titanium nitride layer(TiN), or a combination of titanium(Ti) and titanium nitride layer(TiN). [0030] The photo sensor may include a first insulator film laminated on the field oxide layer, a second insulator film laminated on the first insulator film, a third insulator film laminated on the second insulator film, and a fourth insulator film laminated on the third insulator film, at least one first metal wire formed in the second insulator film, at least one first trench formed in the first insulator film, and the at least one first trench connecting the at least one first metal wire to a source/drain doping region of a WELL region of the semiconductor substrate, at least one second metal wire is formed on the fourth insulator film insulator, and the photo diode and at least one second trench is formed in the fourth insulator film, and the at least one second trench connecting the at least second first metal wire to the photo diode. [0031] The third insulator film may be thinner than the other insulator films. [0032] In another general aspect there is provided a photo sensor module, including a semiconductor substrate, a sensor section formed in the semiconductor substrate, at least one insulator film laminated on the semiconductor substrate, a photo diode placed on an upper portion of the sensor section and formed on the insulator film, and a UV shield formed between the sensor section and the photo diode. [0033] The sensor section may be configured to sense non-UV, and the photo diode is configured to sense UV. [0034] In another general aspect there is provided a photo sensor module, including a semiconductor substrate, a doping region of high concentration formed on the semiconductor substrate, a first field oxide layer and a second field oxide layer formed on the semiconductor substrate, a first photo diode and a second photo diode formed on the first field oxide layer and the second field oxide layer, respectively, and a portion of the first photo diode and a portion of the second photo diode contacting with the doping region of high concentration. [0035] The photo sensor module of claim 20 , wherein the first photo diode and the second photo diode are back-to-back diode. [0036] A doping region of the first photo diode and a doping region of the second photo diode may be enlarged to reach a source/drain doping region of a WELL region of the semiconductor substrate. [0037] The following description discloses a UV sensor that senses UV and a logic section that processes the UV sensor sensed signal simultaneously, on a semiconductor substrate. For example, when forming a poly silicon layer by deposing poly silicon on a field oxide layer or when forming a photo diode by doping impurity on the poly silicon layer, devices can be comprised under the identical process as the identical process is also applied together on a logic section. Therefore, the following description discloses a UV sensor that not only reduces the manufacture cost but also simplifies the manufacture process. [0038] The photo sensor module of the following description discloses a photo diode, which has a predetermined doping region on a semiconductor substrate. Hence, thickness of a semiconductor substrate maybe reducible compared to a manufacture, using a traditional SOI substrate. [0039] Additionally, the following description discloses a UV sensor that can not only place an active device or a passive device on a lower UV sensor but can also improved a structure by placing a sensor section that can sense non-UV. Thus, a UV sensor can reduce an equipped IC chip size. [0040] Other features and aspects will be apparent from the following detailed description, the drawings, and the claims. BRIEF DESCRIPTION OF THE DRAWING [0041] FIG. 1 is a diagram illustrating an example of a photo sensor module. [0042] FIG. 2 is a diagram illustrating another example of a photo sensor module. [0043] FIG. 3 is a diagram illustrating another example of a photo sensor module. [0044] FIG. 4 is a diagram illustrating another example of a photo sensor module. [0045] FIG. 5 is a diagram illustrating another example of a photo sensor module. [0046] FIG. 6 is a diagram illustrating another example of a photo sensor module. [0047] FIG. 7 is a diagram illustrating another example of a photo sensor module. [0048] FIG. 8 is a diagram illustrating another example of a photo sensor module according to the eighth embodiment of the present invention. [0049] FIG. 9 is a diagram illustrating another example of a photo sensor module. [0050] FIG. 10 is a diagram illustrating another example of a photo sensor module. [0051] FIG. 11 is a diagram illustrating another example of a photo sensor module. [0052] FIG. 12 is a diagram illustrating another example of a photo sensor module. [0053] FIG. 13 is a diagram illustrating another example of a photo sensor module. [0054] Throughout the drawings and the detailed description, unless otherwise described or provided, the same drawing reference numerals will be understood to refer to the same elements, features, and structures. The drawings may not be to scale, and the relative size, proportions, and depiction of elements in the drawings may be exaggerated for clarity, illustration, and convenience. DETAILED DESCRIPTION [0055] The following detailed description is provided to assist the reader in gaining a comprehensive understanding of the methods, apparatuses, and/or systems described herein. However, various changes, modifications, and equivalents of the systems, apparatuses and/or methods described herein will be apparent to one of ordinary skill in the art. The progression of processing steps and/or operations described is an example; however, the sequence of operations is not limited to that set forth herein and may be changed as is known in the art, with the exception of steps and/or operations necessarily occurring in a certain order. Also, descriptions of functions and constructions that are well known to one of ordinary skill in the art may be omitted for increased clarity and conciseness. [0056] The features described herein may be embodied in different forms, and are not to be construed as being limited to the examples described herein. Rather, the examples described herein have been provided so that this disclosure will be thorough and complete, and will convey the full scope of the disclosure to one of ordinary skill in the art. [0057] The following description provides a photo sensor module, comprising a UV sensor which is a photo sensor, combatable with general silicon technology wherein, a ploy silicon layer, which is horizontally formed on a semiconductor substrate surface, a passive device formed on a lower UV sensor. Hence, the following description provides a photo sensor module at lower cost and having higher sensitivity sensing. [0058] Unless indicated otherwise, a statement that a first layer is “on” a second layer or a substrate is to be interpreted as covering both a case where the first layer directly contacts the second layer or the substrate, and a case where one or more other layers are disposed between the first layer and the second layer or the substrate. [0059] Words describing relative spatial relationships, such as “below”, “beneath”, “under”, “lower”, “bottom”, “above”, “over”, “upper”, “top”, “left”, and “right”, may be used to conveniently describe spatial relationships of one device or elements with other devices or elements. Such words are to be interpreted as encompassing a device oriented as illustrated in the drawings, and in other orientations in use or operation. For example, an example in which a device includes a second layer disposed above a first layer based on the orientation of the device illustrated in the drawings also encompasses the device when the device is flipped upside down in use or operation. [0060] Expressions such as “first conductivity type” and “second conductivity type” as used herein may refer to opposite conductivity types such as N and P conductivity types, and examples described herein using such expressions encompass complementary examples as well. For example, an example in which a first conductivity type is N and a second conductivity type is P encompasses an example in which the first conductivity type is P and the second conductivity type is N. [0061] FIG. 1 is a diagram illustrating an example of a photo sensor module. In FIG. 1 , a semiconductor substrate 100 is a P type substrate doped with a P type impurity of low concentration. Other P type substrate, such as, for example, a P type substrate formed with a P-epi region, and the like may be used without departing from the spirit and scope of the illustrative examples described. [0062] For separation among devices of a semiconductor substrate ( 100 ), Local Oxidation of Silicon (LOCOS), Shallow Trench Isolation (STI) and Deep Trench Isolation (DTI) or an isolation layer of a combination of, STI and DTI may be used. An isolation layer can be differentiated with a first isolation layer to a third isolation layer 110 , 112 , 114 and a first isolation layer to a third isolation layer 110 , 112 , 114 are formed of a field oxide layer. A photo diode is formed on the first field oxide layer 110 , which is explained below. [0063] A first WELL region (PWELL) 120 and a second WELL region (NWELL) 130 are formed on a semiconductor substrate 100 . A first WELL region 120 is formed between a first isolation layer 110 and a second isolation layer 112 , and a second WELL region 130 is formed between a second isolation layer 112 and a third isolation layer 114 . A junction isolation well 140 can be formed on a side of a second WELL region 130 for separation among devices. When forming the WELL regions 120 , 130 , and 140 a drive-in annealing method can be processed in a high temperature of approximately over 1000° C., for dopant diffusion. Source/drain regions 122 and 132 of high concentration are formed on a first WELL region 120 and a second WELL region 130 , respectively. Moreover, Lightly Doped Drain (LDD) regions 124 and 134 of low concentration are formed on source/drain regions 122 and 132 of high concentration, respectively. LDD regions 124 and 134 are formed by a blanket ion injection method. A blanket ion injection method is processed during or after a deposition of a gate electrode 154 . [0064] A gate insulator film 152 and a gate electrode 154 are formed on a first WELL region 120 and a second WELL region 130 . Thickness of a gate insulator film 152 formed on the first WELL region 120 and the second WELL region 130 can be identical or different. Spacers 156 are formed on both sides of a gate electrode 154 . [0065] A photo diode 160 is formed on a first isolation layer 110 as a UV sensor. Element 160 is referred to as a UV sensor or a photo diode in the following description. A UV sensor 160 is formed by deposing poly silicon on a field oxide layer, i.e., a first isolation layer 110 that is formed on a semiconductor substrate 100 . A poly silicon layer 160 senses UV when impurity is doped. In a non-exhaustive example, a UV sensor 160 includes, an N+ region 161 injected with N type impurity of high concentration, a P region (P−, P−− region) 162 injected with P type impurity of low concentration, and a P+ region 163 injected with P type impurity of high concentration. Moreover, an N+ region 161 is type N, a P region 162 and a P+ region 163 are type P, and a PN junction is formed between type N and type P. Thus, a depletion layer is formed on the P region 162 of low concentration impurity, between an N+ region and a P+ region. Electromotive force leading to a flow of electric current is generated by a light absorbed by the depletion layer. Accordingly, UV is sensed through the generation of electric current. Thickness of the N+ region 161 , the P region (P−, P−− region) 162 and the P+ region 163 can be identical or different. [0066] The UV sensor 160 in the example described above is formed in a form of a photo diode on a field oxide layer 110 , which is formed on a semiconductor substrate 100 and senses UV. The manufacture process can be simplified and thickness of the IC chip can be reduced as compared to applying UV sensor on a SOI substrate. [0067] In other examples described same reference numbers may be used in regards to identical structure but redundant explanation will be omitted. [0068] FIG. 2 is a diagram of another example of a photo sensor module. [0069] The photo sensor module shown in the example of FIG. 2 has a structure that is similar to the photo sensor module shown in FIG. 1 . The above description of FIG. 1 , is also applicable to FIG. 2 , and is incorporated herein by reference. Thus, the above description may not be repeated here. A doping region of a UV sensor formed on a field oxide layer in FIG. 2 is different than the doping region of a UV sensor formed on a field oxide layer in FIG. 1 . FIG. 2 comprises an N+ region 164 injected of N type impurity of high concentration, an N region (N−, N−− region) 165 injected of N type impurity of low concentration, and a P+ region 166 injected of P type impurity of high concentration. Thus, a depletion layer is formed in an N region 165 of low impurity concentration, between N+ region and P+ region and an electromotive force is generated by light absorbed by the depletion layer. [0070] Like FIGS. 1 2 , a UV sensor 160 photo diode can be applied in various ways, such as, for example, N+/P/P+ or N+/N/P+, although it is not limited to the doping region. A UV sensor can be formed with a photo diode of other doping regions, which are shown in the other examples. [0071] FIG. 3 is a diagram of another example of a photo sensor module. [0072] The photo sensor module shown in the example of FIG. 3 has an structure that is similar to the photo sensor modules shown in FIGS. 1 and 2 . The above description of FIGS. 1-2 , is also applicable to FIG. 3 , and is incorporated herein by reference. Thus, the above description may not be repeated here. In FIG. 3 , a semiconductor substrate 100 is provided, a first isolation layer to a third isolation layer 110 , 112 , 114 are formed on a semiconductor substrate 100 . A first WELL region (PWELL) to a third WELL region (NWELL) 120 , 130 , 140 are formed on a semiconductor substrate 100 . A source/drain region 122 and 132 of high concentration are formed on a first WELL region 120 and a second WELL region 130 . A gate insulator film 152 , a gate electrode 154 , and spacers 156 are formed on both sides of a gate electrode 154 . [0073] In the example shown in FIG. 3 , doping region of a photo diode which forms a UV sensor 170 , comprises a P+ region, a P/P−/P−− region, and a N+ region. Among a P+ region, a P/P−/P−− region, and an N+ region, the N+ doping region 171 adjoins a semiconductor substrate 100 . The N+ doping region 171 of a photo diode is extended and contacts with a source/drain region (N+) 122 of a first WELL region 120 . The N+ doping region 171 of a photo diode is formed together, generally in a deposition method, when other doping region P+ region and P/P−/P−− region are formed. Thickness of the doping regions can all be identical or different. Likewise, a photo diode formed in a deposition method is identically applied on other examples of the photo sensor module. [0074] Thus, electromotive power is generated between a P+ region and an N+ region, in a P region of low impurity concentration and in an extended region. [0075] FIG. 4 is a diagram of another example of a photo sensor module and FIG. 5 is a diagram of yet another example of a photo sensor module. [0076] In FIG. 4 , a first field oxide layer 210 and a second field oxide layer 220 are symmetrically formed on a semiconductor substrate 200 . A semiconductor substrate 200 is a P type substrate doped of P type impurity. [0077] An N+ region 250 doped of N type impurity of high concentration is formed adjacent to a central part where a first field oxide layer 210 and a second field oxide layer 220 adjoin. [0078] Photo diodes 230 , 240 are symmetrically formed on the first field oxide layer 210 and on the second field oxide layer 220 , respectively. A photo diode 230 formed on a first field oxide layer 210 forms an N+ doping region 231 by contacting with an N+ region 250 , doped of high concentration. A P (P−, P−−) doping region and a P+ doping region are formed in order, adjacent to the N+ doping region 231 . Moreover, a photo diode formed on a second field oxide layer 210 forms an N+ doping region 241 by contacting with an N+ region 250 , doped of high concentration. A P (P−, P−−) doping region and a P+ doping region are formed in order, adjacent to a N+ doping region 241 . In other words, N+ doping regions 231 , 241 are extended and contacts with an N+ region 250 . Photo diodes 230 , 240 are all formed in a deposition method on a first field oxide layer 210 and the field oxide layer 220 , and thickness of photo diodes 230 , 240 can be identical or different. [0079] In the example shown in FIG. 4 , a doping region of photo diodes 230 , 240 , which comprises a UV sensor is a structure that is in contact with a semiconductor substrate 200 . [0080] Meanwhile, an example of a doping region of a UV sensor, which is formed different but with an identical structure with FIG. 4 is shown in FIG. 5 . FIG. 5 shows that a first field oxide layer 210 and a second field oxide layer 220 are formed identically on a P type semiconductor substrate 200 . Photo diodes 230 , 240 , which is a UV sensor, are formed and on a first field oxide layer 210 and a second field oxide layer 220 . [0081] Photo diodes 230 , 240 of FIG. 5 comprise a different doping region from a doping region of FIG. 4 . A P+ doping region, an N− doping region and an N+ doping region are formed in order on a first field oxide layer 210 and a second field oxide layer 220 according to a P+ region 250 doped of high concentration on a P type semiconductor substrate 200 . P+ doping regions 231 , 241 is extended to contact with the P+ region 250 doped of high concentration. A P+ region 250 is a region, doped of high concentration compared to a P type semiconductor substrate 200 . [0082] FIG. 6 is a cross sectional diagram of another example of a photo sensor module. [0083] The photo sensor module of FIG. 6 is a structure of two photo diodes 330 , 340 formed symmetrically. In FIG. 6 , photo diodes 330 , 340 have a P+/N−/P+ doping region using a Back-to-Back diode. [0084] A P type semiconductor substrate 300 is provided. A first field oxide layer 310 and a second field oxide layer 320 are symmetrically formed on a semiconductor substrate 300 . In a central part adjacent a first field oxide layer 310 and a second field oxide layer 320 , a P+ region 350 doped of P type impurity of high concentration is formed. [0085] Doping region of photo diodes 330 , 340 , which is an UV sensor with P+/N−/P+ doping region is formed on the first field oxide layer 310 and the second field oxide layer 320 , respectively. A side of photo diodes 330 and 340 facing each other is extended and forms P+ doing regions 331 and 341 respectively. The P+ doing regions 331 and 341 contacts with a P+ region 350 . The doping regions 331 and 341 of photo diodes 330 and 340 comprise a UV sensor and contacts with a semiconductor substrate 300 . [0086] In another example, a photo diode of an N+/P/N+ doping region, different from the P+/N−/P+ doping region can be provided. In this example, an N+ doping region is formed on a P type semiconductor substrate. The extended section of photo diode contacts with an N+ doping region of a semiconductor substrate. [0087] FIG. 7 is a diagram illustrating another example of a photo sensor module. [0088] Referring to a photo sensor module of FIG. 7 , semiconductor substrate 400 doped in a first P type impurity is formed. [0089] On a semiconductor substrate 400 surface, isolation layers 410 , 412 , and 414 of a combination of LOCOS, STI and DTI are formed for separation of devices. In a non-exhaustive example, a first isolation layer to third isolation layer 410 , 412 , and 414 are field oxide layer. [0090] A first WELL region PWELL 420 and a second WELL region NWELL 430 are formed between the first isolation layer to the third isolation layers 410 , 412 , and 414 . A first WELL region 420 is formed between a first isolation layer 410 and a second isolation layer 412 , and a second WELL region 430 is formed between a second isolation layer 412 and a third isolation layer 414 . On a side of a second WELL region 430 , a junction isolation well 440 can be formed for separation of devices. When forming the WELL regions 420 , 430 , and 440 a drive-in annealing can be processed in a high temperature of approximately over 1000° C. for dopant diffusion. On the first WELL region 420 and the second WELL region 430 , source/drain regions 421 and 431 of high concentration are formed. On lower spacers 505 , LDD regions 422 and 432 , which are doping region of low concentration, are formed. LDD regions 422 and 432 can be formed in a blanket ion injection method. [0091] A first insulator film to a fourth insulator film 500 , 510 , 520 , and 530 are formed in order on a semiconductor substrate 400 . [0092] A first layer insulator film 500 is formed on a semiconductor substrate 400 . A resistor 502 , a gate insulator film 503 , and a gate electrode 504 are formed in a first layer insulator film 500 . A gate insulator film 503 and a gate electrode 504 are formed on a first WELL region 420 and a second WELL region 430 . Spacers 505 are formed on both sides of a gate electrode 504 . Multiple trenches 506 are formed on a first layer insulator film 500 . A trench 506 connects the source/drain region 421 with a metal wire 511 , which is formed on a second layer insulator film 510 . A conductor is filled in a trench 506 . Conductors, such as, for example, Tungsten (W), Aluminum (Al), and Copper (Cu) so on are used as a filling material. A trench 506 formed on the first layer insulator film 500 is called a ‘first trench.’ [0093] A second layer insulator film 510 is formed on a first layer insulator film 500 . A metal wire 511 is formed on a second layer insulator film 510 . A part of a metal wire 511 is connected with a first trench 506 . [0094] A third layer insulator film 520 is formed on a second layer insulator film 520 . Thickness of a third layer insulator film 520 is comparatively thinner than other layer insulator films 500 , 510 , and 530 . This is because no structure is formed on a third layer insulator film 520 but it only serves an insulation function. [0095] A fourth layer insulator film 530 is formed on a third layer insulator film 520 . A photo diode 531 , which is a UV sensor, is formed on a fourth layer insulator film 530 . A photo diode 531 has a P+ region, a P (or P−, P−−) region, and a N+ doping region. A P+ region and a N+ region, herein, should be connected with a source/drain region 421 , 431 . For this, a metal wire 550 is formed on a fourth layer insulator film 550 . A trench 532 a , which connects a photo diode 531 and a metal wire 550 is formed on a fourth layer insulator film 530 . A trench 532 b that connects a metal wire 550 and a metal wire 511 of a second layer insulator film 510 is also formed. Trench 532 b connects the metal wire 550 to the metal wire 511 via a third layer insulator film 520 and a fourth layer insulator film 530 . Trenches 532 a and 532 b formed on a fourth layer insulator film 530 is called a ‘second trench.’ Trenches 532 a and 532 b , unlike a form of a first trench, can be formed in a via form according to thickness of a layer insulator film. [0096] In this example shown in FIG. 7 , a photo diode 531 is absorbed in a P region of low concentration that is formed between a P+ region and an N+ region when the light is irradiated from above. Electromotive power is generated by absorbed light, and the photo diode 531 senses UV, using change of electromotive power. In this example, a photo diode 531 , which is a UV sensor is formed on a fourth layer insulator film 530 , separated from a semiconductor substrate 400 . A register 502 , which is a passive device, is formed on a first isolation layer 410 , thus, a passive device and a UV sensor are placed vertically. [0097] FIG. 8 is a cross sectional diagram of another example of a photo sensor module. The example of FIG. 8 is different from the example shown in FIG. 7 because a second layer insulator film and a third layer insulator film are not formed in the example shown in FIG. 8 . [0098] A photo diode 531 , which is a UV sensor, is a structure of source/drain regions 421 , 431 , metal wires 533 , 550 , and trenches 506 , 532 that are connected with each other. An N+ doping region of a photo diode 531 is directly connected with a source/drain region 421 of a first WELL region 420 via a trench 506 . [0099] In the case of the eighth embodiment, a UV sensor is placed on an upper passive device. [0100] FIG. 9 is a cross sectional diagram of another example of a photo sensor module. [0101] Referring to the photo sensor module of FIG. 9 , a first layer insulator film 500 and a second layer insulator film 530 are included on a semiconductor substrate 400 . [0102] A first WELL region 420 and a second WELL region 430 are formed on a semiconductor substrate 400 . A source/drain region 505 is formed on a first WELL region 420 and a second WELL region 430 . Moreover, with reference to FIG. 7 , a second isolation layer 412 is formed on a semiconductor substrate 400 , between a first isolation layer 410 , the first WELL region 420 , and a second WELL region 430 . [0103] On a first layer insulator film 500 , a register 502 , a gate electrode 504 , and a gate insulator film 503 are formed. A plurality of a first trench 506 are formed. This is identical to the other recited examples, the description of which are incorporated herein by reference. Thus, the above description may not be repeated here. [0104] A photo diode 531 , which is a UV sensor, is formed on a second layer insulator film 530 . A photo diode 531 comprises N+/P (P−, P−−) N+ doping region. In a second layer insulator film 530 , metal wires 533 a , 533 b , 533 c are provided, and a part of metal wires 533 b , 533 c are placed on an N+ region of a photo diode 531 . A metal wire 533 c is formed in a stair shape and surrounds an N+ doping region. On lower side of a metal wire 533 c , a barrier metal 534 is formed of titanium (Ti), titanium nitride layer (TiN) or a combination (TiN) of titanium (Ti) and titanium nitride layer (TiN). [0105] An N+ doping region of a UV sensor is directly connected with a source/drain region 505 of a first WELL region 420 . [0106] Since a second trench 532 is also formed on a second layer insulator film 530 , a second layer insulator film 530 is connected with a metal wire 550 , formed on upper portion of the second layer insulator film 530 , or with a first trench 506 . [0107] FIG. 10 is a cross sectional diagram of another example of a photo sensor module. [0108] The photo sensor module of FIG. 10 provides a semiconductor substrate 600 . WELL regions 602 , 604 , and 606 and isolation layers 610 , 612 , and 614 are formed on the semiconductor substrate 600 . A photo diode 630 , a UV sensor, which has a N+/P/P+ doping region is formed on a first insolation layer 610 . [0109] On a upper semiconductor substrate 600 , a layer insulator film 620 is formed. A layer insulator film 620 can be thicker than thickness of a semiconductor substrate 600 . A part of a layer insulator film 620 has a region 625 that is removed. A part of a P doping region of a photo diode 530 is exposed by the removed region 625 . [0110] A passivation layer 640 is formed on a layer insulator film 620 . [0111] FIG. 11 is a cross sectional diagram of another example of a photo sensor module. Compared to the example of FIG. 10 , a part of a layer insulator film 620 is not removed in FIG. 11 . [0112] Isolation layers 610 , 612 , 614 are formed on a semiconductor substrate 600 wherein WELL regions 602 , 604 , 606 are formed. A photo diode 630 is formed on an isolation layer 610 of a semiconductor substrate 600 . A gate electrode 632 and a gate insulator film 633 are formed on a semiconductor substrate 600 . A layer insulator film 620 is formed on the semiconductor substrate 600 , including a photo diode 630 , a gate electrode 632 and a gate insulator film 633 . A passivation layer 640 is laminated on a layer insulator film 620 . A passivation layer 640 maximizes UV transmissivity. [0113] FIG. 12 is a cross sectional diagram of another example of a photo sensor module. [0114] FIG. 12 also has a similar structure in some parts compared to the other examples, for example, FIG. 12 has similar structure as that of FIG. 7 . The above description of the similar structures of FIG. 7 is incorporated herein by reference in FIG. 12 . Thus, the above description may not be repeated here. [0115] Referring to FIG. 12 , a first layer insulator film to a fourth layer insulator film 710 , 720 , 730 , 740 are laminated in order on a semiconductor substrate 700 . [0116] On a semiconductor substrate 700 , a first insulator film to a third insulator film 701 , 702 , 703 are formed and WELL regions 704 , 705 , 706 are formed according to the insulator films 701 , 702 , 703 . A register 711 , a gate electrode 712 , and a first trench 713 are formed on a first layer insulator film 710 . Metal wires 721 are formed on a second layer insulator film 720 . A photo diode 732 and second trenches 731 are formed on a third layer insulator film 730 . Metal wires 741 connected with second trenches 731 are formed on a fourth layer insulator film 740 . A passivation layer 750 is formed on a fourth layer insulator film 740 . [0117] FIG. 12 provides a structure that exposes a sensing region of a photo diode 732 to the outside. This is because a part of region 760 of a third layer insulator film 730 , a fourth layer insulator film 740 , and a passivation layer 740 is removed by an etching process. A photo sensor module can also be manufactured in this structure. [0118] With reference to FIG. 13 , a photo sensor module can provide sensing function, which simultaneously senses UV and non-UV. [0119] FIG. 13 is a drawing of another example of a photo sensor module. A semiconductor substrate 800 is shown in FIG. 13 . [0120] To separate the devices, isolation layers of LOCS, STI DTI or a combination of LOCS, STI and DTI are formed on a semiconductor substrate 800 . An isolation layer can be differentiated with a first isolation layer to a fourth isolation layer 801 , 802 , 803 , 804 . A sensor section 810 , sensing non-UV, is formed between a first isolation layer 801 and a second isolation layer 802 ; a first WELL region (PWELL) 812 is formed between a second isolation layer 802 and a third isolation layer 803 ; a second WELL region (NWELL) 814 is formed between a third isolation layer 803 and a fourth isolation layer 804 . A source/drain region 812 a of high concentration and a LDD region 812 b of low concentration doping region, are formed on a first WELL region 812 and a second WELL region 814 . Further, a junction isolation well 816 is formed on a side of a second WELL region 814 . [0121] A first layer insulator layer (IMD: Inter metal dielectric) 820 is formed on a semiconductor substrate 800 . A gate insulator film 821 and a gate electrode 822 are formed on a first layer insulator film 820 in a corresponding region of a first WELL region 812 and a second WELL region 814 . Spacers 823 are formed on each side of a gate electrode 822 . First trenches 824 are formed corresponding with a source/drain region 812 a on a first layer insulator film 820 . Conductor such as, for example, tungsten (W), aluminum (Al), and copper (Cu) is filled in a first trench 824 . [0122] A second layer insulator film (ILD: Inter layer dielectric) 830 is formed on a first layer insulator film 820 . Metal wire 831 is formed corresponding with a first trench 824 on a second layer insulator film 830 . [0123] A third layer insulator film (ILD: Inter layer dielectric) 840 is formed on a second layer insulator film 830 . A photo diode 850 and a UV sensor is formed on a third layer insulator film 840 . A photo diode 850 comprises P+/P/N+ doping region and is placed on a section corresponding to the upper sensor section 810 formed on the semiconductor substrate 800 . Second trenches 841 are also formed on a third layer insulator film 840 . [0124] A UV Block layer 860 is formed between a second layer insulator film 830 and a third layer insulator film 840 . A UV Block layer 860 blocks UV and only transmits non-UV. A sensor section 810 , which is formed on a semiconductor substrate 800 , senses non-UV. [0125] A fourth layer insulator film 870 is formed on a third layer insulator film 840 and a metal wire 871 is formed on the fourth layer insulator film 870 . A metal wire 871 is connected with a photo diode 850 using second trenches 841 or is connected with a metal wire 831 of a second layer insulator film 830 . [0126] A passivation layer 880 is formed on a fourth layer insulator film 870 . In the example shown in FIG. 13 , a photo diode 850 senses UV and a sensor section 810 formed on lower photo diode 850 senses non-UV. [0127] The examples disclosed in the description above use poly silicon layer grown on a semiconductor substrate as a UV sensor and provides a photo sensor module of improved structure of other sensor section or a passive device that can sense non-UV, placed on a lower section of a UV sensor. [0128] While this disclosure includes specific examples, it will be apparent to one of ordinary skill in the art that various changes in form and details may be made in these examples without departing from the spirit and scope of the claims and their equivalents. The examples described herein are to be considered in a descriptive sense only, and not for purposes of limitation. Descriptions of features or aspects in each example are to be considered as being applicable to similar features or aspects in other examples. Suitable results may be achieved if the described techniques are performed in a different order, and/or if components in a described system, architecture, device, or circuit are combined in a different manner and/or replaced or supplemented by other components or their equivalents. Therefore, the scope of the disclosure is defined not by the detailed description, but by the claims and their equivalents, and all variations within the scope of the claims and their equivalents are to be construed as being included in the disclosure.

The present disclosure relates to a photo sensor module. The thickness and size of an IC chip may be reduced by manufacturing a photo sensor based on a semiconductor substrate and improving the structure to place a UV sensor on the upper section of an active device or a passive device. The photo sensor module includes a semiconductor substrate, a field oxide layer, formed on the semiconductor substrate, and a photo sensor comprising a photo diode formed on the field oxide layer.

CROSS-REFERENCE TO RELATED APPLICATION This application is a divisional of application Ser. No. 10/184,216, filed Jun. 28, 2002, the contents of which are hereby incorporated by reference in their entirety. TECHNICAL FIELD The present invention relates to information processing systems, and, more particularly, to runtime versioning in the context of such systems (e.g., dynamic modification of an information processing system without taking the overall system off-line). BACKGROUND Many information processing systems operate according to software configurations which migrate through a series of upgrades and/or patches to repair, extend or otherwise modify the capabilities of such systems. In order to effect such modifications, the information processing systems are typically taken off-line, with the consequential detrimental effect on system availability and overall performance. Also, these systems typically need to be backwards compatible with prior versions through successive version updates. Thus, there is a need for an information processing system with a facility for managing its configuration so that modifications made during runtime are propagated and take affect without restarting the system or a portion thereof. This would allow the potential for 100% uptime while upgrading such systems. There is also a need for a means of allowing an information processing system to be able to process multiple configuration versions, and to be able to process such versions even while such versions are changing during operation of the information processing systems. SUMMARY The present invention relates to information processing systems, and, more particularly, to runtime versioning in the context of such systems (e.g., dynamic modification and extension of an information processing system without taking the overall system offline). For example, a system such as a registry server capable of transactional configuration changes is provided which manages its configuration so that modifications made during runtime are propagated and take affect without restarting the server. In one embodiment, a service implementation comprises at least one persistent data store, a configuration manager and a request handling interface. The configuration manager is asynchronously updated in correspondence with changes to the at least one persistent data store. The request handling interface employs a factory to instantiate a handler instance for handling of a particular request. The handler instance is instantiated based on then current factory-specific configuration information of the configuration manager. In another embodiment, a method is provided including the steps of receiving a message at a message processing service, determining if the message is a create object message, and determining if message is a runtime configuration callback message. In a further embodiment, an object is created by a factory responsive to receiving the message if the message is a create object message. In a further embodiment, a factory-specific configuration cache is updated responsive to receiving the message if the message is a runtime configuration callback message. In a further embodiment, a configuration manager is updated if the message is a configuration storage update complete message. In a further embodiment, a persistent data storage is updated if the message is a configuration storage update message. In another embodiment, a method of implementing runtime versioning is provided. Information stored in a data storage device is changed. Factory-specific configuration information of a configuration manager is updated responsive to the changing of the information stored in the data storage device. A current version of factory-specific configuration information of the configuration manager is accessed by a factory responsive to receiving a message for processing by the factory. The foregoing provides a brief description, or summary, of certain embodiments discussed in greater detail in the detailed description below. Consequently, the foregoing contains, by necessity, simplifications, generalizations and omissions of detail. Consequently, those skilled in the art will appreciate that the foregoing summary is illustrative only and that it is not intended to be in any way limiting of the invention. Other aspects, inventive features, and advantages of the present invention, as defined solely by the claims, may be apparent from the detailed description set forth below. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of one embodiment of an information processing system/network configurable for runtime versioning in accordance with the invention. FIG. 2 is a flowchart showing an exemplary flow of operation for a configuration manager client within the system of FIG. 1 . FIG. 3 is a flowchart showing an exemplary operational flow of a logical persistent search process executing within the system of FIG. 1 . FIG. 4 is a flowchart showing an exemplary operational flow of a configuration management callback process executing within the system of FIG. 1 . DETAILED DESCRIPTION The following discussion is intended to provide a detailed description of at least one example of the invention and should not be taken to be limiting of the invention itself. Rather, any number of variations may fall within the scope of the invention which is properly defined in the claims following this description. FIG. 1 is a block diagram of one embodiment of an information processing system/network 100 . System 100 may be any appropriate type of information processing system. In the presently discussed example, system 100 provides a registry server such as a Sun ONE registry server. System 100 includes transport interface 110 , application 120 , configuration manager 180 and directory server 190 . Transport interface 110 is coupled to receive transport specific request messages via coupling 104 , and to provide corresponding messages via coupling 115 to a message processing service such as application 120 . Application 120 is coupled to interact with configuration manager 180 and directory server 190 to process the received requests. Application 120 provides a request handling service in the present embodiment. Configuration manager 180 is also coupled to interact with directory server 190 . Transport interface 110 is any type of appropriate interface configured to screen and transfer messages between other information processing systems and system 100 . For example, transport interface 110 may provide a Hypertext Transfer Protocol (HTTP) interface or a Java Messaging Service (JMS) interface. In one embodiment, transport interface 110 is configured to receive messages in a non-native format such as the Extensible Markup Language (XML). Application 120 is a network system application program interface which includes various configuration manager clients or listeners. One type of configuration manager client is a factory singleton for creating process instances to facilitate processing of messages. For example, application 120 includes the illustrated request factory 140 , handler factory 150 and a storage access object factory such as Data Access Object (DAO) factory 160 . Each factory includes a configuration cache to enable the factory to operate according to the latest and/or multiple configurations or versions. For example, the configuration cache for each of factories 140 , 150 and 160 is illustrated by request configuration (RC) 145 , handler configuration (HC) 155 and DAO configuration (DAOC). 165 , respectively. In the embodiment shown, request factory 140 uses RC 145 to create request object 147 , handler factory 150 uses HC 155 to create handler object 157 , and DAO factory 160 uses the DAOC 165 to create DAO 167 . As used herein, a client or factory configuration cache need not be, and in this embodiment is not, a dedicated hardware cache, and may take as simple a form as software partitioned areas of memory assigned to the respective factories. Configuration manager 180 is a software object which includes a configuration manager for each client in application 120 . Specifically, as shown, configuration manager 180 includes request configuration manager (RCM) 182 , handler configuration manager (HCM) 184 and DAO configuration manager (DAO CM) 186 . Configuration caches 145 , 155 , and 165 interact with configuration managers 182 , 184 , and 186 , respectively, to ensure proper runtime versioning. Configuration managers 182 , 184 and 186 are updated responsive to changes to directory server 190 . Directory server 190 is a file system on any appropriate form of persistent data storage. Directory server 190 may include a number of data storage devices coupled together. In a registry server embodiment, registry server information and configuration may be stored within directory server 190 . In one embodiment, directory server 190 is a Lightweight Directory Access Protocol (LDAP) directory server. In another embodiment, directory server 190 is a Sun ONE directory server. In still another embodiment, directory server 190 is a relational database management system (RDBMS). During operation, the various components of system 100 communicate via a variety of messages including update messages, object creation messages, callback messages and search messages. For example, request factory 140 receives non-native format messages from transport interface 110 and generates request objects such as request 147 . Request 147 may be a java object request such as an administrative request. Request 147 may be a Universal Description, Discovery and Integration (UDDI) request. Request 147 sends a native format request message to handler factory 150 . Handler factory 150 generates a handler object such as handler 157 responsive to request 147 . Handler 157 includes information from request 147 . Handler 157 uses DAO 167 to access directory server 190 . DAO 167 is created by DAO factory 167 responsive to handler 157 . In each case, the factory consults the respective configuration factory for the appropriately versioned configuration information for use in creating the respective object. If a configuration update message is received at a component of system 100 , an update to configuration information stored at directory server 190 is made. Configuration manager 180 detects the update via a persistent search message to directory server 190 . Responsive to detecting the update at directory server 190 , configuration manager 180 updates its own respective client-specific caches (e.g., CMs 182 , 184 and 186 ) as appropriate, and informs the appropriate clients (e.g., factories 140 , 150 and 160 ) via callback messages. FIG. 2 is a flowchart showing an exemplary flow of operation for a configuration manager client within the system of FIG. 1 . As discussed above, exemplary configuration manager clients include request factory 140 , handler factory 150 and DAO factory 160 . During registration operation 210 , each configuration manager client registers its interest in configuration information stored in configuration manager 180 . For example, request factory 140 registers interest in updated configuration information so that when the request configuration manager 182 is updated, request configuration cache 145 may be updated by a callback procedure. Other factories may make similar registrations for their respective configuration caches. After registration operation 210 , the configuration manager client waits for new messages. If a new message is received during new message decision 220 , control transitions to create object decision 230 . If the message requires creation of an object, such object is created during object creation flow 240 . If the message does not require creation of an object, the configuration manager client in question determines if the messages is a callback message during decision 250 . If the message is not a callback message, the configuration manager client again waits for new messages. If the message is a callback message, the callback is processed during configuration caching flow 260 . In the illustrated embodiment, if the message requires creation of an object, the configuration cache is queried during cache query operation 242 . The configuration cache of the configuration manager client is queried with the message name and version to get the appropriate class name. After the appropriate class name is obtained during query operation 242 , a new object of the appropriate class name type is created during create object operation 244 . After the new object is created during creation object operation 244 , the new object is returned during return operation 246 . The configuration manager client then waits for new messages again (e.g., at decision 220 ). For example, responsive to a message being received by request factory 140 , request factory 140 queries the request factory configuration cache 145 with the message name and version of the message. Configuration cache 145 provides the necessary information to create request 147 . The message may be compatible with one of several protocol versions understood by application 120 , and configuration cache 145 provides the appropriate information for the version of the message to create the appropriately versioned request object. For further example, responsive to receiving a native format request message from request object 147 , handler factory 140 queries the handler factory configuration cache 155 with the name and version of the request. Configuration cache 155 provides the necessary information to create handler 157 . The native format message may be compatible with one of several protocol versions understood by application 120 , and configuration cache 155 provides the appropriate information for that version to create the appropriately versioned handler object 157 . Similar operations may occur with regard to DAO factory 160 and DAO object 167 . If the message is determined to be a callback message during decision 250 shown in FIG. 2 , the configuration management client must take certain steps to update its configuration cache. This may be performed to obtain the latest version information, for example. In the illustrated embodiment, a new configuration cache is created during cache creation operation 262 . After a new cache is created during cache creation operation 262 , new configuration information is copied to the newly created configuration cache during cache copy operation 264 . After cache copy operation 264 , the current configuration cache is replaced atomically with the newly created configuration cache during cache replacement operation 266 . The configuration manager client then waits for new messages again (e.g., at decision 220 ). For example, responsive to a callback message being received by request factory 140 , request factory 140 creates a new request factory configuration cache. Request factory 140 then copies new configuration information from request configuration manager 182 to the newly created configuration cache. Next, request factory 140 replaces configuration cache 145 with the new configuration cache which contains the latest configuration information. Similarly, handler and DAO factory configuration caches 155 and 165 may be updated from handler and DAO configuration managers 184 and 186 , respectively. FIG. 3 is a flowchart showing an exemplary operational flow of a logical persistent search process executing within the system of FIG. 1 . The logical persistent search process is used to update directory server 190 with information intended to change the configuration information used to generate objects by configuration manager clients. In one embodiment, system 100 provides a registry server configuration class which uses an LDAP persistent search for asynchronous notification of configuration changes within the directory of directory server 190 . From a programming perspective, a persistent search works like a synchronous, LDAP search, but calls iterate over the search result block until there is a result available, hence a separate thread is used for this function. Referring to FIG. 3 , after a configuration update message is received at system 100 during update message decision 310 , a storage element of system 100 (e.g., a portion of directory server 190 ) is updated with new configuration information from the message during update operation 320 . After the persistent data storage is updated during operation 320 , an update message is sent from directory server 190 to configuration manager 180 if the update corresponds to a search result. A configuration manager callback process (e.g., process 400 of FIG. 4 ) is initiated responsive to receiving the update message/search result. The configuration manager call back process updates configuration manager 180 from directory server 190 in accordance with the changes indicated in the update message. Because configuration manager 180 is only interested in registry server configuration information, an LDAP search filter is used to restrict the search to the entries of an objectclass type matching the allowed configuration manager client types, some of which are shown in FIG. 1 . The search is set to wait for adds or modifies. Using this method, a result is returned to the search thread upon an add or modify operation to a configuration entry in directory server 190 . FIG. 4 shows one example of the configuration management callback process referenced above with regard to FIG. 3 . As shown in FIG. 4 , configuration manager 180 waits for an update message indicating that the configuration information stored in directory server 190 has been changed. If such an update message is received during change message decision 410 , the type of configuration information change is determined from the update message during get type operation 420 . For example, the type may be representative of one or more of the factories, but is at least indicative of which portions of configuration manager 180 should be updated. After the type of configuration information change is determined during operation 420 , the appropriate sub-configuration manager cache (e.g., one or more of CMs 182 , 184 and 186 ) within configuration manager 180 is updated during update operation 430 . After update operation 430 , the sub-configuration manager caches are queried to retrieve a list of callbacks during list query operation 440 . Each sub-configuration manager cache indicates a callback if registration was made during operation 210 ( FIG. 1 ). Next, if the callback list does not include any listener callbacks during list decision 450 , then operation continues with additional change messages at operation 410 . If the callback list length is not zero during list decision 450 , the listener configuration caching process is performed for each listener. For example, callback messages may be used for each configuration manager client to initiate the configuration caching flow 260 shown in FIG. 1 for each client. Using configuration manager 180 in this way allows other components in the system to receive notification of changes to one or more configuration components. For example, the handling component requests updates about changes to the handling configuration entry. When the configuration component receives a search result indicating that the handling configuration entry, it notifies the handling component by sending it, via a callback, the new configuration. To facilitate this notification, each configuration entry is self-describing. Each has an attribute that identifies it as a particular configuration entry, e.g., Handler or DAO. When the persistent search thread receives an entry that has changed, it evaluates this attribute and caches the entry contents in memory. Finally, it notifies registered components of the registry server about these changes via their callbacks. System 100 provides the capability for administrators to manipulate registry server functionality at runtime. The set of registry server protocol handlers together form what is known as the application/registry server. Through the configuration manager protocol, handlers and other functionality may be swapped, for example, with an alternate implementation and/or removed without requiring a server restart. This function allows the ability for system administrators to add new protocol functions in the future and deprecate old ones with zero application downtime. Each configuration runtime contains a single set of factories that manage the set of exported registry protocol function (e.g., UDDI and administrative API). Factories retrieve the list of support functions from the configuration manager on start-up. As discussed above, a callback between each factory and the configuration manager ensures subsequent updates to the list are propagated as needed. In one embodiment, redundant registry servers are deployed to enhance performance and/or reliability. Therefore, a configuration management runtime (e.g., configuration manager 180 ) may be embedded within each of the registry servers. Additional, replicated directory servers may also be added to further increase reliability. Each registry server is then coupled to one or more directory servers such as directory server 190 . When clustered, a single management runtime receives the modification request over HTTP/SOAP. For example, a system user or administrator may send a modification message to one of the registry servers. The runtime configuration manager at the registry server receiving the message then stores the change within a directory server, but does not typically communicate with its peer registry servers. Upon a successful update of the directory server, the directory server propagates the change to all active registry server instances. These instances are then responsible for updating their configuration caches. Thus, an update message arrives from a user where it is implemented at the receiving registry server, then the update is stored in a directory server coupled to the registry server, and then it is updated from the directory server to each registry server. The above description is intended to describe at least one embodiment of the invention. The above description is not intended to define the scope of the invention. Rather, the scope of the invention is defined in the claims below. Thus, other embodiments of the invention include other variations, modifications, additions, and/or improvements to the above description. For example, those skilled in the art will recognize that boundaries between the functionality of the above described operations are merely illustrative. The functionality of multiple operations may be combined into a single operation, and/or the functionality of a single operation may be distributed in additional operations. Moreover, alternative embodiments may include multiple instances of a particular operation, and the order of operations may be altered in various other embodiments. The operations discussed herein may consist of steps carried out by system users, hardware modules and/or software modules. In other embodiments, the operations of FIGS. 2-4 , for example, are directly or indirectly representative of software modules (e.g., factories, objects, routines, or other partitional software designations) resident on a computer readable medium and/or resident within a computer system and/or transmitted to the computer system as part of a computer program product. Thus, the operations referred to herein may correspond to modules or portions of modules (e.g., software, firmware or hardware modules, or combinations thereof). The functionality of operations referred to herein may correspond to the functionality of modules or portions of modules in various embodiments. Accordingly, the boundaries between modules are merely illustrative and alternative embodiments may merge modules or impose an alternative decomposition of functionality of modules. For example, the modules discussed herein may be decomposed into submodules to be executed as multiple computer processes. Moreover, alternative embodiments may combine multiple instances of a particular module or submodule. The above described method, the operations thereof and modules therefor may be executed on a computer system configured to execute the operations of the method and/or may be executed from computer-readable media. Computer systems may be found in many forms including but not limited to mainframes, minicomputers, servers, workstations, personal computers, notepads, personal digital assistants, various wireless devices and embedded systems, just to name a few. A typical computer system includes at least one processing unit, associated memory and a number of input/output (I/O) devices. A computer system processes information according to a program and produces resultant output information via I/O devices. A program is a list of instructions such as a particular application program and/or an operating system. A computer program is typically stored internally on computer readable storage media or transmitted to the computer system via a Computer readable transmission medium. A computer process typically includes an executing (running) program or portion of a program, current program values and state information, and the resources used by the operating system to manage the execution of the process. A parent computer process may spawn other, child processes to help perform the overall functionality of the parent process. Because the parent process specifically spawns the child processes to perform a portion of the overall functionality of the parent process, the functions performed by child processes (and grandchild processes, etc.) may sometimes be described as being performed by the parent process. The method(s) described above may be embodied in a computer-readable medium for configuring a computer system to execute the method. The computer readable media may be permanently, removably or remotely coupled to system 100 or another system. The computer readable media may include, for example and without limitation, any number of the following: magnetic storage media including disk and tape storage media; optical storage media such as compact disk media (e.g., CD-ROM, CD-R, etc.) and digital video disk storage media; holographic memory; nonvolatile memory storage media including semiconductor-based memory units such as FLASH memory, EEPROM, EPROM, ROM; ferromagnetic digital memories; spintronic memories, volatile storage media including registers, buffers or caches, main memory, RAM, etc.; and data transmission media including permanent and intermittent computer networks, point-to-point telecommunication equipment, carrier wave transmission media, the Internet, just to name a few. Other new and various types of computer-readable media may be used to store and/or transmit the software modules discussed herein. It is to be understood that the architecture(s) depicted herein (e.g., in FIG. 1 ) are merely exemplary, and that in fact many other architectures can be implemented which achieve the same functionality. In an abstract, but still definite sense, any arrangement of components to achieve the same functionality is effectively “associated” such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as “associated with” each other such that the desired functionality is achieved, irrespective of architectures or intermedial components Likewise, any two components so associated can also be viewed as being “operably connected”, or “operably coupled”, to each other to achieve the desired functionality. Because the above detailed description is exemplary, when “one embodiment” is described, it is an exemplary embodiment. Accordingly, the use of the word “one” in this context is not intended to indicate that one and only one embodiment may have a described feature. Rather, many other embodiments may, and often do, have the described feature of the exemplary “one embodiment.” Thus, as used above, when the invention is described in the context of one embodiment, that one embodiment is one of many possible embodiments of the invention. Notwithstanding the above caveat regarding the use of the words “one embodiment” in the detailed description, it will be understood by those within the art that if a specific number of an introduced claim element is intended in the below claims, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such limitation is present or intended. For example, in the claims below, when a claim element is described as having “one” feature, it is intended that the element be limited to one and only one of the feature described. Furthermore, when a claim element is described in the claims below as including or comprising “a” feature, it is not intended that the element be limited to one and only one of the feature described. Rather, for example, the claim including “a” feature reads upon an apparatus or method including one or more of the feature in question. That is, because the apparatus or method in question includes a feature, the claim reads on the apparatus or method regardless of whether the apparatus or method includes another such similar feature. This use of the word “'a” as a nonlimiting, introductory article to a feature of a claim is adopted herein by Applicants as being identical to the interpretation adopted by many courts in the past, notwithstanding any anomalous or precedential case law to the contrary that may be found. Similarly, when a claim element is described in the claims below as including or comprising an aforementioned feature (e.g., “the” feature), it is intended that the element not be limited to one and only one of the feature described merely by the incidental use of the definite article. Furthermore, the use of introductory phrases such as “at least one” and “one or more” in the claims should not be construed to imply that the introduction of another claim element by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim element to inventions containing only one such element, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an.” The same holds true for the use of definite articles. While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that, based upon the teachings herein, various modifications, alternative constructions, and equivalents may be used without departing from the invention claimed herein. Consequently, the appended claims encompass within their scope all such changes, modifications, etc. as are within the spirit and scope of the invention. Furthermore, it is to be understood that the invention is solely defined by the appended claims. The above description is not intended to present an exhaustive list of embodiments of the invention. Unless expressly stated otherwise, each example presented herein is a nonlimiting or nonexclusive example, whether or not the terms nonlimiting, nonexclusive or similar terms are contemporaneously expressed with each example. Although an attempt has been made to outline some exemplary embodiments and exemplary variations thereto, other embodiments and/or variations are within the scope of the invention as defined in the claims below.

An information processing system includes a runtime versioning facility which allows for managing its configuration so that modifications made during runtime are propagated and take affect without restarting the system or a portion thereof. This allows the potential for 100% uptime while upgrading such systems. This also provides a system capability to process multiple configuration versions, and to be able to process such versions even while such versions are changing during operation of the information processing systems. For example, a system such as a registry server capable of transactional configuration changes is provided which manages its configuration so that modifications made during runtime are propagated and take affect without restarting the server.

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application is based on and claims the benefit of U.S. Provisional Application No. 60/783,503, filed on Mar. 17, 2006 and entitled “Folding Carrier,” which is incorporated herein by reference in its entirety. BACKGROUND [0002] The ability to flat pack enclosures such as pet carriers is a problem both before and after purchase by a consumer. After purchase, the consumer is left with a large bulky item to store. Before purchase, during shipment and at the point of distribution and sale, there is a storage problem with large carriers, such as for pets, because such carriers require large shipping volume and consume valuable shelf space. [0003] In the past, many carriers, such as handbags, were simply crushed to store them flat. Crushing is not suitable for those carriers that need to be rigid and remain fully assembled so not to restrict the space within the enclosure. This is very important if the enclosure is used for pets, although it is important for other types of carriers and not limited in use for pets. SUMMARY [0004] The folding carrier has a body typically having multiple panels, such as two sides, two ends, a bottom and a top. The body is preferably composed of a pliable or flexible material such as fabric, vinyl, or leather. A cavity for holding a pet and for storing or carrying materials is defined by the body. To provide rigidity, the opposing sides, the opposing ends, or the top and bottom have a skeleton formed of a rigid material, such as metal or plastic, covered exteriorly by the pliable material. The skeleton helps define the shape of the body. [0005] Methods of transporting the carrier could include the use of handles, a carrying strap or wheels, either pulled along with a strap on four wheels or tipped on two wheels and pulled along with the use of a retractable rigid handle. [0006] To provide access to the interior or cavity of the body, one or more sides, ends, top or bottom are secured to the remainder of the body with reclosable access devices, such as zippers, hook and loop fasteners, snaps, buttons or the like. At least one edge of the sides, ends, top or bottom that are secured with reclosable access devices is integrally hinged to an adjoining panel of the body, so that when that panel is opened using the reclosable access device, the panel remains attached to the body. In addition, a door may be provided in a side or end which is also secured to the remainder of the body using a zipper, hook and loop fasteners, snaps, buttons or the like. A panel access opening may also be provided in a side, end, top or bottom, such as with overlapping panels of the pliable material. The door provides easy access for a pet owner, for example, to remove a pet, while the panel access opening permits the pet owner to insert his/her hand into the cavity to touch a pet while keeping the body substantially closed. BRIEF DESCRIPTION OF DRAWINGS [0007] While the appended claims set forth the features of the present patent with particularity, the patent, together with its objects and advantages, may be best understood from the following detailed description taken in conjunction with the accompanying drawings, of which: [0008] FIG. 1 is a front perspective view of a first embodiment, with a substantially rigid handle retracted and a substantially flexible handle extended. [0009] FIG. 2 is a rear perspective view of a first embodiment, with a substantially rigid handle extended, a substantially flexible handle flattened, and wheels at the bottom. [0010] FIG. 3 is a perspective view of a second embodiment, with a rigid skeleton and a zipper extending across the length of the carrier on both of its sides. [0011] FIG. 4 is a perspective view of a third embodiment, with a rigid skeleton and a zipper extending across the width of the carrier at both of its ends. [0012] FIG. 5 shows the embodiment of FIG. 3 with a side unzipped and the body partially folded. [0013] FIG. 6 shows the embodiment of FIG. 3 with both sides unzipped and spread opposite each other on either side of the top, bottom and two ends. [0014] FIG. 7 shows the embodiment of FIG. 3 with one side folded beneath the bottom and the other side folded between the top and bottom and one end folded over the top. [0015] FIG. 8 shows the embodiment of FIG. 4 with one end unzipped. [0016] FIG. 9 shows the embodiment of FIG. 4 with both ends unzipped and spread away from the rest of the body. [0017] FIG. 10 shows the embodiment of FIG. 4 with both ends unzipped and folded within the cavity formed by the two sides, top and bottom. [0018] FIG. 11 shows the embodiment of FIG. 4 with the body fully flattened with the two sides, two ends, top and bottom substantially parallel to each other. [0019] FIG. 12 shows the embodiment of FIG. 1 with one side unzipped. [0020] FIG. 13 shows the embodiment of FIG. 1 with both sides unzipped and one side folded into the cavity formed by the top, bottom, and two ends, and the other side spread away from the rest of the body. [0021] FIG. 14 shows the embodiment of FIG. 1 with the body fully flattened and the two ends both unzipped and within the cavity, and the top, bottom and sides substantially parallel to each other. [0022] FIG. 15 is a perspective view of the embodiment of FIG. 3 with a door at one end unzipped to provide access to the cavity. [0023] FIG. 16 is a perspective view of the embodiment of FIG. 3 showing a cavity access panel and opening in one end. [0024] FIG. 17 is a perspective view of the embodiment of FIG. 3 showing a cavity access panel and opening in one end and a side unzipped. DETAILED DESCRIPTION OF THE EMBODIMENTS [0025] While the appended claims set forth the features of the present patent with particularity, the patent, together with its objects and advantages, may be best understood from the following detailed description taken in conjunction with the accompanying drawings. [0026] Now referring to FIG. 1 , it illustrates a three-dimensional front perspective view of a first embodiment 10 of a folding carrier. The first embodiment 10 is illustrated to include side panels 12 and 14 , a front and top panel 16 that are visible in FIG. 1 . Moreover, the first embodiment 10 also includes a bottom panel 18 and a back panel 20 . A telescopic handle 22 and a loop handle 24 may be attached to the back panel 20 . The first embodiment 10 of FIG. 1 includes a pocket zipper 24 creating a pocket area on the side panel 12 , a front-bottom zipper 26 creating an opening for a pet, etc., in the front, a front-top zipper 28 creating another opening in the front of the carrier and opening-zippers 30 and 32 that may allows the front-top panel to be detachably attached to the side panels 12 and 14 and to the back panel 20 . [0027] FIG. 2 illustrates an alternate view of the first embodiment 10 . Especially, FIG. 2 illustrates the first embodiment 10 from the back so that the back panel 20 , the telescopic handle 22 is illustrated in its fully extended form. As it can be seen from FIG. 2 , the back panel 20 may also include a telescopic handle housing pocket 34 that may be used to store the telescopic handle 22 in its un-extended form. [0028] Now referring to FIG. 3 , it illustrates a second embodiment 40 of the folding carrier. The second embodiment 40 may include side panels 42 and 44 that may be attached to a bottom panel 46 and a top panel 48 . The top panel 48 may further be designed to cover front end 50 and back end 52 of the second embodiment 40 . A handle 54 may be attached to the top panel 48 while a strap 56 may be attached to the front end 50 and the back end 52 of the second embodiment 40 . The bottom panel 46 of the second embodiment 40 may also include a cushioning material located to its inside surface and a semi-rigid material attached to its outside surface. The cushioning material may provide a surface on which a pet can sleep or sit on, whereas the semi-rigid surface may provide support to the weight of the pet. [0029] FIG. 4 illustrates a third embodiment 60 of the folding carrier. The third embodiment 60 may include side panels 62 and 64 that may be attached to a bottom panel 66 and to a top panel 68 . Furthermore a front panel 70 and a back panel 72 may be attached to the side panels 62 and 64 and the top panel 68 by zipper or other similar tying mechanism. A handle 74 may be attached to the top panel 68 while a strap 76 may be attached to the front end 70 and the back end 72 of the third embodiment 60 . The side panels 62 and 64 may have zippered pockets such as the pocket 78 attached to them. [0030] FIG. 5 is a perspective view of the second embodiment 40 of the folding carrier with the side panel 42 unzipped and the body of the folding carrier partially folded. FIG. 6 shows the second embodiment 40 of the folding carrier with both side panels 42 and 44 folded down. The back panel 52 is shown to be folded down on the bottom panel of the folding carrier. Similarly, the top panel 48 is also shown to be folded down on the bottom panel and a front panel of the folding carrier. Such flexibility to fold various panels on top of each other allows the folding carrier to be easily stored in a compact fashion. [0031] FIG. 7 shows a different perspective of the second embodiment 40 of the folding carrier in a collapsed format. As shown in FIG. 7 , the front panel 50 and the top panel 48 are shown pulled on top of the bottom panel of the folding carrier. [0032] FIG. 8 illustrates a perspective of the third embodiment 60 of the folding carrier with the back panel 72 of the folding carrier zipped opened and collapsed down. Further in FIG. 9 , both the front panel 70 and the back panel 72 of the folding carrier 60 are illustrated zipped opened and collapsed down. Subsequently, a user may fold in the zipped open front panel 70 and the back panel 72 towards the bottom panel of the folding carrier. FIG. 10 illustrates such an embodiment of the folding carrier with the front panel 70 zipped open and folded in towards the inner cavity of the folding carrier. [0033] FIG. 11 illustrates the each of the various side panels of the third embodiment 60 of the folding carrier zipped open and collapsed on towards the bottom panel of the folding carrier. As illustrated in FIG. 11 , it is possible to fold the folding carrier to a very compact form, which allows a user to store the folding carrier easily and without taking too much extra space. When in the compact form, the folding carrier may be stored in another container, suitcase, etc., for easily transferring it from one place to another. Such compact form also allows a manufacturer to pack a large number of folded carriers in a shipping container and allows a store owner to shelf a large number of such units on shelves. [0034] Now referring to FIG. 13 , the first embodiment 10 of the folding carrier is illustrated with the side panel 72 zipped open. Subsequently, as shown in FIG. 13 , the zipped open side panel may be folded inside the cavity of the folding carrier. For example, in FIG. 13 , the side panel 12 is illustrated to be folded into the cavity of the folding carrier while the side panel 14 is illustrated to be zipped open and folded down. FIG. 13 also illustrates the bottom panel 18 folded down on the back panel of the folding carrier. [0035] FIG. 14 illustrates an alternate embodiment of the first embodiment 10 of the folding carrier from a different point of view. Herein both side panels 12 and 14 are tucked inside the cavity of the folding carrier. [0036] Now referring to FIG. 15 , an alternate illustration of the second embodiment 40 of the folding carrier is shown with the front panel 50 zipped and folded down. The other side panels and the back panels may also be similarly zipped down to allow the folding carrier to be folded down. [0037] FIG. 16 illustrates the second embodiment 40 of the folding carrier with a flap 102 attached to the top panel 48 . The flap 102 may be provided on one side of the top panel 48 so as to flap down on the front panel 50 or it may also be provided on the other side of the top panel 48 so as to flap down on the back panel 52 as well. The flap 102 may be fixedly attached to the front panel 50 with an attaching mechanism such as zipper, Velcro, buttons, etc. The flap 102 allows a user of the folding carrier to attend to the storage area or the cavity inside the folding carrier without having to open the entire side panel. [0038] Thus, for example, if the folding carrier is used to transport an animal, a user may input his hand through the flap 102 to touch the animal, to feed the animal, etc. Such capability is illustrated in further detail in FIG. 17 , wherein the side panel 42 of the folding carrier is shown to be zipped open and collapsed while a user is shown to be approaching the cavity of the folding carrier via the opening created by the flap opening 102 . [0039] As shown above, the folding carrier can be folded substantially flat for shipping, store display, or home storage when not in use by simply unzipping the opposing sides, ends, or top and bottom, folding the unzipped sides, ends, or top and bottom into the cavity or exteriorly to the remainder of the body, and pressing the remaining sides, ends, or top and bottom so that the all fold into a flat and substantially parallel position relative to each other. When the carrier is to be used, the procedure is simply reversed to fully assemble it.

A folding carrier described herein is composed of a plurality of panels made of pliable and flexible material such as fabric, vinyl or leather where each of the plurality of panels may be folded onto each other. The folding carrier also includes a cavity access opening in one of the panels that allows a user to access the cavity formed by the plurality of panels, wherein the cavity access opening is secured to the one of the panels with re-closable access device.

FIELD OF THE INVENTION AND RELATED ART [0001] The present invention relates to an image forming apparatus employing an intermediary transferring member. In particular, it relates to an image forming apparatus, and the operating method therefor, which enable the operator of the image forming apparatus to manually cause the image forming apparatus to operate in the mode for eliminating the cause(s) of the image defect(s), as the operator notices the presence of an image defect (defects) in an image formed by the image forming apparatus. [0002] As for the modes in which an image forming apparatus can be operated to eliminate a cause (or causes) of an image defect (image defects), there are an automatic mode which is automatically carried out based on the cumulative number of the prints yielded by an image forming apparatus, or the like factors, and a manual mode which is carried out as the switch for starting the manual mode is pressed by the operator of the image forming apparatus. [0003] An image forming apparatus, which can be manually instructed by its operator to operate in the mode for eliminating the cause (causes) of the formation of a defective image, makes it possible for the operator to deal with a situation in which the image forming apparatus has yielded an image suffering from an unexpected image defect. [0004] Japanese Laid-open Patent Application 2001-134109 discloses an image forming apparatus which can be controlled by its operator through its control panel to operate in a cleaning mode for clearing the intermediary transferring member of the external additives of the developer having adhered thereto. [0005] In the case of this image forming apparatus, as its operator notices, in a given image yielded by the apparatus, the presence of an image defect, more specifically, a so-called ghost, that is, the phenomenon that the pattern of the image formed during the preceding image formation cycles is faintly visible across the image formed thereafter, the image forming apparatus can be controlled by its operator to operate in the cleaning mode for cleaning the intermediary transferring member, in order to the eliminate the cause(s) of the image defect. [0006] However, the above described image forming apparatus is problematic in that there are situations in which even if an operator of an image forming apparatus such as the one described above identifies the cause(s) of the abovementioned image defect, and instructs the apparatus to operate in the mode for eliminating the cause of the image defect, the cause of the image defect persists. [0007] In other words, the causes for the formation of a defective image by an image forming apparatus employing an intermediary transferring member are not limited to the substances having adhered to the intermediary transferring member. If a cause of the image defect is one other than the residues having adhered to the intermediary transferring member, the cause of the image defect cannot be eliminated, even if the mode for cleaning the intermediary transferring member is carried out. Moreover, it is very difficult to correctly identify the cause(s) of an image defect. [0008] As the image defects which frequently occur due to the causes other than the above described ones, there are the image defects resulting from the changes in the condition under which a toner image is formed on an image bearing member. SUMMARY OF THE INVENTION [0009] The primary object of the present invention is to provide an image forming apparatus having a means which enables the user of the image forming apparatus to swiftly eliminate the causes of an image defect, even when it is difficult for the operator to identify the causes of the image defect. [0010] According to an aspect of the present invention, there is provided an image forming apparatus comprising an image bearing member; toner image formation means for forming a toner image on said image bearing member; removing means for removing deposited matter deposited on said image bearing member; detecting means for detecting a toner image to be detected, formed on said toner image formation means; control means for controlling a toner image forming condition of said toner image forming means in accordance with a result of detection of the toner image to be detected by said detecting means; said apparatus being operable in a mode in which said removing means operates to remove the deposition, and said detecting means operates to detect the toner image to be detected, executing means for executing an operation in said mode; and an operating portion for manually starting execution of the operation in said mode by said executing means. [0011] These and other objects, features, and advantages of the present invention will become more apparent upon consideration of the following description of the preferred embodiments of the present invention, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0012] FIG. 1 is a schematic drawing of the image forming apparatus in the first embodiment of the present invention, showing the general structure thereof. [0013] FIG. 2 is a block diagram of the sequence for controlling the image forming operation of the image forming apparatus in the first embodiment of the present invention. [0014] FIG. 3 is a block diagram of the sequence for controlling the tone gradation of the image forming apparatus in the first embodiment of the present invention. [0015] FIG. 4 is a drawing showing the toner image formation condition control pattern of the image forming apparatus in the first embodiment of the present invention. [0016] FIG. 5 is a graph showing the relationship between the density level of the image outputted in each of the primary colors and the corresponding output of the photosensitive element. [0017] FIG. 6 is a block diagram showing the process for creating a LUT correction table. [0018] FIG. 7 is a graph showing the relationship in density level between the theoretical toner image formation condition control pattern and the>the pattern used for controlling the toner image formation conditions, and the density level of the resultant image. [0019] FIG. 8 is a graph showing the relationship between the input level and output level. [0020] FIG. 9 is a drawing showing the toner image formation position control pattern of the image forming apparatus in the first embodiment of the present invention. [0021] FIG. 10 is drawing showing in detail the toner image formation position control pattern for the image forming apparatus in the first embodiment of the present invention. [0022] FIG. 11 is a drawing showing the video memory portion of the image forming apparatus in the first embodiment of the present invention. [0023] FIG. 12 is a drawing showing the external I/F processing portion of the image forming apparatus in the first embodiment of the present invention. [0024] FIG. 13 is a drawing of an example of the control panel of the image forming apparatus in the first embodiment of the present invention. [0025] FIG. 14 a is a flowchart of the recovery mode sequence. [0026] FIG. 14 b is a flowchart of another recovery mode sequence. [0027] FIG. 15 is a drawing showing the toner image formed on the intermediary transfer belt in the recovery mode. [0028] FIG. 16 is a drawing showing the recovery mode sequence. [0029] FIG. 17 is a drawing showing another recovery mode sequence. [0030] FIG. 18 is a drawing of the image forming apparatus in the third embodiment of the present invention, showing the general structure thereof. [0031] FIG. 19 is a drawing showing the recovery mode sequence in the second embodiment of the present invention. [0032] FIGS. 20 a , 20 b , and 20 c are drawings showing the examples of the windows shown across the display portion of the control panel of the image forming apparatus in the fourth embodiment of the present invention. [0033] FIG. 21 a is a flowchart of the recovery mode sequence in the fourth embodiment of the present invention, in which a selecting means can be used to clean the intermediary transferring member without carrying out the process of controlling the image forming apparatus in toner image position and toner image density. [0034] FIG. 21 b is a flowchart of another recovery mode sequence in the forth embodiment of the present invention, in which a selecting means can be used to clean the intermediary transferring member without carrying out the process of controlling the image forming apparatus in toner image position and toner image density. [0035] FIG. 22 is a drawing of the recovery mode window of the display portion in the fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0036] According to the present invention, an image forming apparatus is enabled to be operated in the mode in which the abovementioned adherent residues on the intermediary transferring member are removed by the abovementioned residue removing means, and in which the toner image is detected by the abovementioned detecting means, and also, it is provided with a means for carrying out this mode. [0037] Further, the image forming apparatus is provided with a control portion through which the operator of the image forming apparatus can cause the abovementioned means for carrying out the abovementioned recovery mode to start carrying out the recovery mode. [0038] Therefore, even when the cause of the image defect cannot be identified by an operator, the cause of the image defect can be quickly eliminated. [0039] Hereinafter, the preferred embodiments of the present invention will be described in detail. Embodiment 1 [0040] Next, the first embodiment of the present invention will described with reference to the appended drawings. [0041] FIG. 1 is a schematic sectional view of a full-color printer as an example of an image forming apparatus. It is provided with four image forming portions (image formation units): an image forming portion 1 Y for forming an image for the yellow color; an image forming portion 1 M for forming an image of the magenta color; an image forming portion 1 C for forming an image of the cyan color; and an image forming portion 1 Bk for forming an image of the black color. These four image forming portions 1 Y, 1 M, 1 C, and 1 Bk are arranged in a straight line at preset intervals. [0042] The image forming portions (toner image forming means) 1 Y, 1 M, 1 C, and 1 Bk are provided with electrophotographic photosensitive members 2 a , 2 b , 2 c , and 2 d (which hereinafter will be referred to as photosensitive drums), as image bearing members, which are in the form of a drum. They are also provided with primary charging devices 3 a , 3 b , 3 c , and 3 d , developing apparatuses 4 a , 4 b , 4 c , and 4 d , transfer rollers 5 a , 5 b , 5 c , and 5 d , as transferring means, and drum cleaning apparatuses 6 a , 6 b , 6 c , and 6 d , respectively, which are disposed in the adjacencies of the peripheral surfaces of the photosensitive drums 2 a , 2 b , 2 c , and 2 d in a manner of surrounding the photosensitive drums 2 a , 2 b , 2 c , and 2 d , respectively. The image forming apparatus is also provided with an exposing apparatus 7 based on a laser, which is disposed below the space in which the primary charging devices 3 a , 3 b , 3 c , and 3 d , and developing apparatuses 4 a , 4 b , 4 c , and 4 d are disposed. Further, the image forming apparatus is provided with an electric power switch 1070 as a means for turning on the image forming apparatus. [0043] In the developing apparatuses 4 a , 4 b , 4 c , and 4 d , yellow, magenta, cyan, and black toners are stored, respectively. [0044] As the image forming apparatus is turned on with the use of the switch 1070 , the image forming apparatus starts up. [0045] Each of the photosensitive drums 2 a , 2 b , 2 c , and 2 d is made up of an aluminum substrate in the form of a drum, and a photoconductive layer formed on the peripheral surface of the substrate, of a negative organic photoconductive substance. Each of the photosensitive drums 2 a , 2 b , 2 c , and 2 d is rotationally driven by a driving apparatus (unshown) at a preset process speed in the direction indicated by an arrow mark (clockwise direction of FIG. 1 ). [0046] The primary charging devices 3 a , 3 b , 3 c , and 3 d as primary charging means negatively and uniformly charge the peripheral surfaces of the photosensitive drums 2 a , 2 b , 2 c , and 2 d , respectively, to a preset potential level, with the use of the charge bias applied from a charge bias power source (unshown). [0047] The developing apparatuses 4 a , 4 b , 4 c , and 4 d contain toner, and develop the electrostatic latent images formed on the peripheral surfaces of the photosensitive drums 2 a , 2 b , 2 c , and 2 d , into visible images (images formed of toner) by adhering the toners of the corresponding colors, respectively. [0048] The transfer rollers 5 a , 5 b , 5 c , and 5 d as primary transferring means are disposed so that they can be pressed against the peripheral surfaces of the photosensitive drums 2 a , 2 b , 2 c , and 2 d , with an intermediary transfer belt 8 sandwiched between the peripheral surfaces of the transfer rollers 5 a , 5 b , 5 c , and 5 d and the peripheral surfaces of the photosensitive drums 2 a , 2 b , 2 c , and 2 d , in primary transfer portions 32 a , 32 b , 32 c , and 32 d , respectively. [0049] The drum cleaning apparatuses 6 a , 6 b , 6 c , and 6 d are provided with a cleaning blade, or the like, for removing the residual toner, that is, the toner remaining on the peripheral surface of the photosensitive drums 2 after the primary transfer. [0050] The intermediary transfer belt 8 is disposed on the top side of the space in which the photosensitive drums 2 a , 2 b , 2 c , and 2 d are disposed, and is stretched around a pair of rollers 10 and 11 . The roller 10 is the one which opposes the secondary transfer roller 12 , with the intermediary transfer belt 8 sandwiched between the two rollers, and the roller 11 is a tension roller. The roller 10 is disposed so that it can be pressed against the peripheral surface of the secondary transfer roller 12 , with the intermediary transfer belt 8 sandwiched between the rollers 10 and 12 . The intermediary transfer belt 8 is an endless piece of film formed of a dielectric resin such as polycarbonate, polyethylene terephthalate, polyfluorovinylidene, or the like. [0051] Further, the intermediary transfer belt 8 is extended at such an angle that the portions of the intermediary transfer belt 8 , which are in contact with the peripheral surfaces of the photosensitive drums 2 a , 2 b , 2 c , and 2 d , are positioned higher than the portion of the intermediary transfer belt 8 , which is in contact with the secondary transfer roller 12 . [0052] In other words, the intermediary transfer belt 8 is angled so that the downwardly facing portion 8 b of the outward surface (in terms of the loop which intermediary transfer belt 8 forms) of the intermediary transfer belt 8 , that is, the portion of the outward surface of the intermediary transfer belt 8 , with which each of the photosensitive drums 2 a , 2 b , 2 c , and 2 d comes into contact, by the top portion of its peripheral surface, as the intermediary transfer belt 8 is rotationally driven, is positioned higher than the portion of the outward surface of the intermediary transfer belt 8 , which is in the secondary transfer portion 34 . More specifically, the intermediary transfer belt 8 is stretched at roughly 15°. Further, the intermediary transfer belt 8 is kept stretched by two rollers: the aforementioned roller 10 , which opposes the secondary transfer roller 12 , and is disposed on the secondary transfer portion side to drive the intermediary transfer belt 8 ; and the tension roller 11 disposed on the opposite side of the intermediary transfer belt 8 from the roller 10 , with the primary transfer portions 32 a - 32 d positioned between the two rollers 10 and 12 in terms of the direction in which the intermediary transfer belt 8 is stretched. [0053] The roller 10 (secondary transferring means) is disposed so that it can be pressed against the secondary transfer roller 12 , with the intermediary transfer belt 8 sandwiched between the two rollers 10 and 12 . Disposed in the adjacencies of the tension roller 11 and outward side of the loop which the endless intermediary transfer belt 8 forms is a belt cleaning apparatus 13 for recovering the transfer residual toner remaining on the outwardly facing surface of the intermediary transfer belt 8 , by removing it from the intermediary transfer belt 8 . The belt cleaning apparatus 13 removes residues other than the transfer residual toner, which have adhered to the intermediary transfer belt 8 , as well as the transfer residual toner. Disposed on the downstream side of the secondary transfer portion 34 , in terms of the direction in which a transfer medium P is conveyed, is a fixing apparatus, which is made up of a fixation roller 16 a and a pressure roller 16 b , and through which the recording medium P is vertically conveyed. [0054] The exposing apparatus 7 is made up of: a light emitting means based on a laser, which emits beams of laser light, while modulating them with sequential electrical digital video signals in accordance with the image formation data; a polygon lens; a deflection mirror, etc. It forms electrostatic latent images different in the primary colors they correspond, on the peripheral surfaces of the photosensitive drums 2 a , 2 b , 2 c , and 2 d , which have been charged by the primary charging devices 3 a , 3 b , 3 c , and 3 d , according to the image formation data, by exposing the charged peripheral surfaces of the photosensitive drums 2 a , 2 b , 2 c , and 2 d , respectively. [0055] Next, the image forming operation of the above described image forming apparatus will be described. [0056] As an image formation start signal is issued, the photosensitive drums 2 a , 2 b , 2 c , and 2 d begin to be rotationally driven at a preset process speed. As they are rotationally driven, they are uniformly charged to the negative polarity, by the primary charging devices 3 a , 3 b , 3 c , and 3 d , in the image forming portions 1 Y, 1 M, 1 C, and 1 Bk, respectively. The exposing apparatus 7 emits beams of laser light while modulating them with the externally inputted video signals, which reflect the primary color components into which the image formation data have been converted. The emitted beams of laser light are transmitted by way of the polygon lens, deflection mirror, etc., illuminating thereby the peripheral surfaces of the photosensitive drums 2 a , 2 b , 2 c , and 2 d . As a result, electrostatic latent images, which correspond one for one to the primary colors, are formed on the peripheral surface of the photosensitive drums 2 a , 2 b , 2 c , and 2 d , one for one. [0057] Then, the toner of the yellow color is adhered to the electrostatic latent image on the photosensitive drum 2 a by applying to the developing apparatus 4 a a development bias, the polarity of which is the same (negative) as that to which the photosensitive drum 2 a has been charged; the electrostatic latent image on the peripheral surface of the photosensitive drum 2 a is developed into a visible image, that is, an image formed of toner. This image formed of the yellow toner (which hereinafter will be referred to simply as yellow toner image) is transferred (primary transfer) by the application of the primary transfer bias (opposite (positive) in polarity to toner) onto the intermediary transfer belt 8 , which is being circularly driven, in the primary transfer portion 32 a , which is between the photosensitive drum 2 a and transfer roller 5 a . The primary transfer bias is applied to the transfer roller 5 a from a primary transfer bias power source 1060 a. [0058] The portion of the intermediary transfer belt 8 , onto which the yellow toner image has just been transferred, is moved toward the image forming portion 1 M, in which the toner image of the magenta color having just formed on the photosensitive drum 2 b is layered onto the yellow toner image on the intermediary transfer belt 8 , in the primary transfer portion 32 b. [0059] The transfer residual toner, that is, the toner remaining on each of the photosensitive drums 2 a , 2 b , 2 c , and 2 d after the toner image transfer, is scraped down by the cleaning blade, or the like, with which each of the drum cleaning apparatus 6 a , 6 b , 6 c , and 6 d is provided, and then, is recovered. [0060] Similarly, the toner image of the cyan color, and the toner image of the magenta color, which have been formed on the photosensitive drums 2 c and 2 d in the image forming portions 1 C and 1 Bk, respectively, are sequentially transferred in layers, in the primary transfer portions 32 c - 32 d , respectively, onto the yellow and magenta toner images having been layered on the peripheral surface of the intermediary transfer belt 8 . As a result, a full-color image, that is, a visible image of full-color, is formed, on the intermediary transfer belt 8 . [0061] Meanwhile, a transfer medium P (sheet of paper) is fed into the main assembly of the image forming apparatus from a sheet feeder cassette 17 or a manual sheet feeder tray 20 , and then, is conveyed by a pair of registration rollers 19 through a recording medium conveyance passage 18 (sheet passage) to the second transfer portion 34 , with such timing that as the leading edge of the full-color toner image on the intermediary transfer belt 8 arrives at the secondary transfer portion 34 , that is, the interface between the aforementioned roller 10 and secondary transfer roller 12 , the recording medium P reaches the secondary transfer portion 34 at the same time. In the secondary transfer portion 34 , the full-color image, that is, the combination of the layered four toner images different in color, is transferred (secondary transfer) onto the transfer medium P, by the secondary transfer roller 12 , to which the secondary transfer bias (which is opposite (positive) in polarity to toner) is being applied, as the recording medium P is conveyed through the secondary transfer portion 34 . As the secondary transfer roller 12 , an electrically conductive rubber roller formed of sponged rubber or the like is employed. [0062] After the formation (transfer) of the full-color toner image onto the transfer medium P, the transfer medium P is conveyed to the fixing apparatus 16 , in which the full-color toner image is heated, while being compressed, in the fixation nip between the fixation roller 16 a and pressure roller 16 b . As a result, the full-color toner image is thermally fixed to the surface of the transfer medium P. Thereafter, the recording medium P is discharged by a pair of sheet discharge rollers 21 onto the delivery tray 22 , which constitutes a part of the top portion of the main assembly of the image forming apparatus, ending thereby the image formation sequence. As for the secondary transfer residual toner, that is, the toner remaining on the intermediary transfer belt 8 after the secondary transfer, is removed by a cleaning apparatus 13 as a toner removing means disposed in contact with the surface of the intermediary transfer belt 8 , in order to prepare the intermediary transfer belt 8 for the formation of the next image. The cleaning apparatus 13 in this embodiment employs the blade-based cleaning method; a blade 131 formed of urethane rubber is placed in contact with the intermediary transfer belt 8 with the application of a preset amount of pressure. [0063] The steps described above are the steps for forming an image on only one of the two surfaces of the recording medium P (one-sided image formation). [0064] FIG. 2 is a block diagram showing the basic image forming operation of the image forming apparatus. Designated by a referential symbol 171 is a CPU which controls the basic operation of the image forming apparatus, to which a ROM 174 , in which the control programs are stored, a work RAM 175 for data processing, and an input/output port 178 , are connected through an address bus and a data bus. To the input/output port 173 , a sensor (unshown) for detecting the recording sheet position, or the like means, are connected to input the signals therefrom for controlling motors, clutches, and the like (unshown), into the CPU 171 , which uses the signals (inputs) to control the operation of the image forming apparatus. [0065] More specifically, the CPU 171 sequentially controls the inputs thereto and outputs therefrom, in order to control the image forming operation, according to the contents of the ROM 174 , through the input/output port 173 . Also to the CPU 171 , a control portion 172 is connected, so that it is enabled to control the displaying means of the control portion 172 , and inputting means (key pad or the like). It is through the inputting means (key pad or the like) that an operator is to instruct the CPU 171 to switch the image formation mode, and/or display mode. The CPU 171 displays the condition of the image forming apparatus, and the operational mode set by the operator through the inputting means (key pad or the like). Also connected to the CPU 171 are: an external I/F processing portion 400 for exchanging (transmitting or receiving) the image formation data and/or the data to be processed, with external devices such as a personal computer; a video memory portion 300 used for image expansion, or temporarily storing image formation data; and an image forming portion 200 by which the sequential image formation data transferred from the video memory portion 300 are processed for exposing the photosensitive drums 2 with the use of the exposing apparatus 7 . [0066] The image forming apparatus in this embodiment is enabled to reproduce various levels of tone. The process carried out by this image forming apparatus in order to reproduce various level of tone will be described with reference to the block diagram, in FIG. 3 , of the toner reproduction process. [0067] The luminance signals of an intended image are obtained by a CCD 1019 , and the obtained luminance signals are converted into digital luminance signals by an A/D conversion circuit 1020 . Then, the digital luminance signals are sent through a shading circuit 1021 which rectifies the errors in the digital luminance signals resulting from the variation in the sensitivity of a CCD. Then, the rectified digital luminance signals are sent through a LOG conversion device 1022 to convert the rectified digital luminance signals into density signals. [0068] The density signals obtained through the LOG conversion device 1022 are rectified using an LUT 1023 in order to ensure that the y property of the printer, which is selected at the initialization of the printer, is such that the original and the image outputted by the image forming apparatus match in density. The LUT 1023 is designed to be corrected using an LUT correction table 1024 yielded as the results of a computation which will be described later. [0069] After being rectified with the use of the abovementioned LUT 1023 , the density signals are converted by a pulse width conversion circuit 1025 into signals, each of which matches the width of the corresponding dot, and then, are sent to a laser driver 1026 , which projects a beam of laser light, while modulating it with the thus obtained digital signals, to scan (expose) the photosensitive drums 2 ( 2 a , 2 b , 2 c , and 2 d ). As a result, a latent image is formed of a collection of dots different in size, on each of the photosensitive drums 2 , and each of the latent images is put through the developing process, transferring process, and fixing process. Consequently, an image, the tone gradation of which matches that of the original, is formed on the aforementioned recording medium P. [0070] In this embodiment, the level of the abovementioned density signal is expressed using 8 bits. In other words, the density is expressed in 256 levels. In order to realize a desired level of density, the image forming apparatus is controlled in terms of toner image density. [0071] The method for controlling the image forming apparatus in toner image density is as follows: [0072] Referring to FIG. 4 , a toner image condition control pattern (toner image to be detected) 1027 a made up of five sections different in density level (section with density level of OOH, section density level of 40H, section with density level of 80H, section with density level of COH, and section with density level of FFH) is formed on the photosensitive drum 2 , and then, is transferred onto the intermediary transfer belt 8 . [0073] Incidentally, this image forming apparatus is provided with an internal test pattern generator capable of generating on the photosensitive drums 2 ( 2 a , 2 b , 2 c , and 2 d ) one of multiple test patterns different in density signal level. [0074] The images of the toner image density control pattern 1027 a formed on the photosensitive drums 2 as described above are sequentially transferred onto the intermediary transfer belt 8 , and then, the optical density of each of the five sections of the image of the toner image density control pattern 1027 a is synchronously detected by the combination of a light emitting element 1028 and a photosensitive element 1029 , as a toner image detecting means, which outputs signals proportional to the detected level of the optical density. FIG. 5 is a graph showing the relationship between the density of each of the outputted images of the toner image density control pattern 1027 a , which are different in color, and the corresponding output of the photosensitive element 1029 , in this embodiment. [0075] Based on the results of the detection by the combination of the light emitting element 1028 and photosensitive element 1029 , as a detecting means, the toner image density controlling means 1050 controls the lookup table (which hereinafter will be referred to as LUT), controlling thereby the image forming apparatus in terms of toner image density. [0076] Next, the details of the control method carried out by the toner image density controlling means 1050 will be described. [0077] Referring to the block diagram in FIG. 6 , the method for creating the table 1024 for correcting the LUT, by processing the signals outputted by the abovementioned photosensitive element 1029 , which detects (reads) the optical density of a toner image, will be described. The signals outputted by the photosensitive element 1029 are converted by an A/D conversion device 1030 , into digital signals, which are converted by a density conversion circuit 1031 , into density signals. [0078] During the initial setting of the y property of the image forming apparatus (printer), the image forming apparatus is set according to the LUT so that the relationship between the density of the toner image density control pattern 1027 a and the density of the image of the toner image density control pattern becomes linear (curved line C in FIG. 7 ). However, the photosensitive drums 2 ( 2 a , 2 b , 2 c , and 2 d ) change in such properties as sensitivity, developability, etc., due to the changes in the manner in which the toner is supplied, changes in the ambience, and/or the like changes, which occur with the elapse of time, which in turn causes the abovementioned relationship between the density of the toner image density control pattern 1027 a and the density of the image thereof, to deviate from the relationship represented by the curved line C; it changes to that represented by a curved line A or that represented by a curved line B, for example. [0079] Thus, if the density levels detected by the photosensitive element 1029 are higher than the intended density levels, as indicated by the curved line A in FIG. 7 , a computation is made to lower the values, to which the density levels are set, as shown by the curved line A′ in FIG. 8 , so that the resultant output density levels will be lower by the amount by which the output density level was higher than the intended density level. Further, if the density levels detected by the photosensitive element 1029 are lower than the intended density levels, as indicated by the curved line B in FIG. 7 , a computation is made to raise the values, to which the density levels are set, as shown by the curved line B′ in FIG. 8 , so that the resultant output density levels will be higher by the amount by which the output density level was lower than the intended density level. [0080] For the above described purpose, the LUT correction table 1024 to be used for correcting the LUT table 1023 is created by a correction value computation circuit 1032 , which performs the above described computation for obtaining the correction value, based on the density levels calculated by the density conversion circuit 1031 shown in FIG. 6 . [0081] The table 1024 for correcting the LUT 1023 , which is created through the above described process, is used to correct the LUT 1023 , and the corrected LUT 1023 is used to compensate for the toner gradation which has been changed by the abovementioned factors, so that the printer remains constant in terms of the toner gradation. A toner image, the tone gradation of which matches the preset toner gradation, can be formed by carrying out the above described compensation process for each of the primary colors. The abovementioned values used for the compensation are stored in the unshown RAM of the control portion, and are continuously used until the above described correction process is repeated as it is determined that an outputted toner image is abnormal in density. [0082] Next, the process of controlling the image forming apparatus in toner image position will be described. [0083] Referring to FIG. 9 , a toner image position control pattern 1027 b (toner image to be detected) is formed across the portion of the intermediary transfer belt 8 , which opposes the combination of the light emitting element 1028 and photosensitive element 1029 , as a detecting means. The beam of light projected from the light emitting element 1028 onto the toner image position control pattern 1027 b is reflected by the pattern 1027 b , and is detected by the photosensitive element 1029 . [0084] The results of the detection by the photosensitive element 1029 are used by the toner image position controlling means 1051 to control the image forming apparatus in the position of the portion of each of the photosensitive drums 2 , across which each photosensitive drum 2 is exposed by the exposing means 7 , controlling thereby the apparatus in the position of the portion of the photosensitive drum 2 across which the toner image is to be formed. [0085] Shown in detail in FIG. 10 is the toner image formation position control pattern 1027 b . In FIG. 10 , the patterns Ya, Ma, Ca, and Bka are formed on the intermediary transfer belt 8 by the image forming portions 1 Y, 1 M, 1 C, and 1 Bk. The patterns Ya, Ma, Ca, and Bka are straight lines perpendicular to the direction indicated by an arrow mark A, that is, the direction in which the intermediary transfer belt 8 is moved. Further, the patterns Ya, Ma, Ca, and Bka have been formed with a preset timing. Also referring to FIG. 10 , designated by referential symbols la 1 , la 2 , and la 3 are the distances between the patterns Ya and Ma, between the patterns Ma and Ca, and between the patterns Ca and Bka, which are measured by the combination of the light emitting element 1028 and photosensitive element 1029 . The theoretical values of the distances la 1 , la 2 , and la 3 are known from the timing with which the patterns Ya, Ma, Ca, and Bka have been formed. [0086] The toner image formation position controlling means 1051 compares the values of the distances la 1 , la 2 , and la 3 with their theoretical values, and controls the image forming apparatus in the position of the portion of the intermediary transfer belt 8 , across which a toner image is to be formed, in terms of the direction which is parallel to the intermediary transfer belt advancement direction as well as the direction perpendicular thereto. That is, the toner image position controlling means 1051 controls the image forming apparatus in the position of the portion of each of the photosensitive drums 2 , across which the photosensitive drum 2 is exposed by the exposing means 7 of each of the image forming portions 1 Y, 1 M, 1 C, and 1 Bk, respectively. [0087] Also referring to FIG. 10 , the patterns Yb, Mb, Cb, and Bkb are also formed on the intermediary transfer belt 8 by the image forming portions 1 Y, 1 M, 1 C, and 1 Bk. Each of the patterns Yb, Mb, Cb, and Bkb is a pair of straight lines inclined at a preset angle relative to the direction perpendicular to the direction indicated by the arrow mark A, which is the direction in which the intermediary transfer belt 8 advances. The patterns Yb, Mb, Cb, and Bkb are formed with a preset timing. Designated by referential symbols lb 1 , lb 2 , lb 3 and lb 4 are the distances between the preset point of one of the pair of straight lines of each of the patterns Yb, Mb, Cb, and Bkb, and that of the other. These distances are measured by the combination of the light emitting element 1028 and photosensitive element 1029 . The theoretical values of the distances lb 1 , lb 2 , lb 3 , and lb 4 are known from the preset timing with which the patterns Yb, Mb, Cb, and Bkb have been formed. [0088] The toner image formation position controlling means 1051 compares the values of the distances la 1 , la 2 , and la 3 with their theoretical values, and controls the image forming apparatus in the position of the portion of the intermediary transfer belt 8 , across which a toner image is to be formed, in terms of the direction which is parallel to the intermediary transferring member advancement direction as well as the direction perpendicular thereto. That is, the toner image position controlling means 1050 controls the image forming apparatus in the position of the portion of each of the photosensitive drums 2 , across which the photosensitive drum 2 is exposed by the exposing means 7 of each of the image forming portions 1 Y, 1 M, 1 C, and 1 Bk, respectively. [0089] As described above, the detecting means detects the toner images on the intermediary transfer belt 8 . Based on the results of the detection, the toner image density controlling means 1050 and toner image position controlling means 1051 , as controlling means, variably control the toner image formation conditions (toner image density, toner image position) for the toner image forming means. [0090] Next, referring to FIG. 11 , the details of the video memory portion 300 will be described. The video memory portion 300 is accessed to write the image formation data received from the external I/F processing portion 400 through a memory controller 302 , into a page memory 301 , which is such a memory as DRAM, and also, to read the image formation date to provide the image forming portions 2 with the image formation data. [0091] The memory controller portion 302 determines whether or not the image formation data, which it receives from the external I/F processing portion 400 , is compressed data. If it determines that the data is compressed data, it expands the compressed data, with the use of a compressed data expanding portion 300 . Therefore, it writes the expanded data into the page memory 301 . [0092] The memory controller portion 302 also generates a signal for refreshing the page memory 301 in the form of a DRAM or the like. Further, it controls such a process as accessing the page memory 301 to write the data from the external I/F processing portion 400 , and to read the data in the page memory 301 to supply the image forming portions 200 with the image formation data. Further, it controls which addresses in the page memory 301 the data are to be written into, which addresses in the page memory 301 the data are to be read from, in which direction the data is to be read, or the like. [0093] Next, referring to FIG. 12 , the structure of the external I/F processing portion 400 will be described. [0094] The external I/F processing portion 400 is made up of: a USB I/F portion 401 , a centro I/F portion 402 , and a network I/F portion 403 , through one of which the image formation data and print command data sent from the external apparatus 500 are received by the video memory portion 300 , or the condition of the image forming apparatus determined by the CPU 171 , and the like, are transmitted to the external apparatus 500 , which here is a computer, a workstation, or the like. [0095] The print command data received from the external apparatus 500 through one of the USB I/F portion 401 , centro I/F portion 402 , and network I/F portion 403 , are processed by the CPU 171 to be used for setting the image forming portion 200 for carrying out a printing operation, and also, for setting the timing with which the printing operation is carried out, with the use of the image forming portion 200 , or through the I/O 173 . [0096] The image formation data received from the external apparatus 500 through one of the USB I/F portion 401 , centro I/F portion 402 , and network I/F portion 403 , are transmitted to the video memory portion 300 , with the timing set based on the print command data, and are processed by the image forming portion 200 to be used for image formation. [0097] Next, the recovery mode which is to be used by a user (operator) to eliminate the cause(s) of the formation of an abnormal image, if the user notices the formation of an abnormal image, will be described. The recovery mode is started by a user, by depressing the recovery mode starting means 601 , with which the control panel 600 (controlling portion), shown in FIG. 13 , of the image forming apparatus is provided, while the image forming apparatus is on, more specifically, while the image forming apparatus is kept on standby. As the recovery mode starting means 601 is depressed, the command data are processed by the CPU 171 (processing means) shown in FIG. 2 . The recovery mode is carried out by the image forming portion 200 , etc. The image forming apparatus is designed so that the recovery mode can be started at will by a user, by operating the recover mode starting means 601 . [0098] The recovery mode in this embodiment is carried out as follows. FIG. 14 a is a flowchart of the recovery mode sequence in this embodiment. [0099] In the recovery mode, Step S 1 related to the removal of the adherent residues on the intermediary transfer belt 8 , Step S 2 related to the positioning of a toner image, and Step S 3 related to toner density, are sequentially carried out in this order. As the recovery mode is started, the rotation of the intermediary transfer belt 8 is started, and then, as the recovery mode ends, the rotation of the intermediary transfer belt 8 is stopped. [0100] Next, the step (Step S 1 in FIG. 14 a ), which is related to the removal of the adherent residues on the intermediary transfer belt 8 , and is carried out first, will be described in detail. [0101] As the recovery mode starting means 601 is depressed by a user, the recovery mode begins. First, it is started to drive the intermediary transfer belt 8 in the direction indicated by an arrow mark A. As the intermediary transfer belt 8 is circularly driven, the intermediary transfer belt 8 rubs against the blade 131 (rubber blade) of the cleaning apparatus 13 , which is formed of urethane rubber. As a result, the adherent residues on the intermediary transfer belt 8 are removed by the blade 131 . It is desired that the intermediary transfer belt 8 is circularly driven no less than one full turn (which requires 2.4 seconds). The longer the length of time the intermediary transfer belt 8 rubs against the urethane rubber blade 131 , the more ensured it is that the adherent residues on the intermediary transfer belt 8 are satisfactorily removed. In this embodiment, the intermediary transfer belt 8 is circularly driven 75 times (180 seconds). Incidentally, while the recovery mode is carried out, the intermediary transfer belt 8 is continuously circularly moved. [0102] Further, the presence of the toner between the urethane rubber blade 131 and intermediary transfer belt 8 while the intermediary transfer belt 8 is rubbing against the urethane rubber blade 131 improves the urethane rubber blade 131 in terms of its performance in the removal of the residues on the intermediary transfer belt 8 , because the toner acts as an abradant. [0103] Referring to FIG. 15( a ), in this embodiment, therefore, a toner image 1033 for cleaning the intermediary transfer belt 8 is formed on the rotating intermediary transfer belt 8 , supplying the interface between the urethane rubber blade 131 and intermediary transfer belt 8 with toner. At this time, the method for supplying the interface between the urethane rubber blade 131 and intermediary transfer belt 8 with toner will be described. [0104] First, the toner image 1033 , which is in the form of a belt (extending perpendicular to intermediary transfer belt advancement direction), is formed on the rotating intermediary transfer belt 8 . Referring to FIG. 15 , the length of the this toner image 1033 , that is, its measurement in terms of the direction perpendicular to the intermediary transfer belt advancement direction, is equivalent to the length of the entirety of the range across which an image can be formed, whereas the width of the toner image 1033 , that is, the measurement of the toner image 1033 in terms of the direction parallel to the intermediary transfer belt advancement direction, is roughly 10 cm. The size of the toner image 1033 in the form of a belt, and the formation timing therefor, are stored in advance in the video memory portion 300 . [0105] While the intermediary transfer belt 8 is circularly driven to supply the interface between the urethane rubber blade 131 and intermediary transfer belt 8 with toner, the process of feeding the image forming apparatus with a sheet of recording medium, process of conveying a sheet of recording medium though the apparatus, and process of transferring a toner image onto a sheet of recording medium, are not carried out, which is different from the normal image forming operation. As the intermediary transfer belt 8 is circularly driven, the toner image 1033 thereon reaches the urethane rubber blade 131 , supplying the interface between the urethane rubber blade 131 and intermediary transfer belt 8 with toner. [0106] Next, the step (Steps S 21 and S 22 in FIG. 14 ), which is carried out second, will be described. [0107] Referring to FIG. 15( b ), the toner image position control pattern 1027 b is formed on the intermediary transfer belt 8 as shown in the drawing (S 21 ). The toner image formation position control pattern 1027 b is formed on the portion of the intermediary transfer belt 8 , which is within the image formation range. The toner image position control pattern 1027 b is formed on the intermediary transfer belt 8 after the circular driving of the intermediary transfer belt 8 no less than one turn after the formation of the toner image 1033 on the intermediary transfer belt 8 . In other words, the toner image formation position control pattern 1027 b is formed on the portion of the intermediary transfer belt 8 , from which the residues have been removed by the cleaning apparatus 13 . [0108] Then, the toner image position control pattern 1027 b is detected by the combination of the light emitting element 1028 and photosensitive element 1029 (S 22 ). [0109] Described next will be the step (Steps S 31 and S 32 ) related to the toner density, which is carried out third. [0110] Referring to FIG. 15( b ), the toner image density control pattern 1027 a is formed across the portion of the intermediary transfer belt 8 , which is on the upstream side of the toner image formation position control pattern 1027 b in terms of the advancement direction of the intermediary transfer belt 8 as shown in the drawing (Step S 31 in FIG. 14 a ). The toner image formation condition control pattern 1027 a is formed on the portion of the intermediary transfer belt 8 , which is within the image formation range. In other words, the toner image density control pattern 1027 a is formed on the portion of the intermediary transfer belt 8 , from which the residues have been removed by the cleaning apparatus 13 . [0111] Further, the toner image density control pattern 1027 a is detected by the combination of the light emitting element 1028 and photosensitive element 1029 , as a toner image detecting means (Step S 32 in FIG. 14 a ). [0112] As soon as the process for controlling the image forming apparatus in the toner image density is completed, the intermediary transfer belt 8 , which has been circularly driven, is stopped, ending thereby the recovery mode. [0113] Then, during the period between the completion of the recovery mode and the formation of the next image, the CPU 171 controls the image forming apparatus in the toner image formation position, and toner image density, based on the results of the detection of the toner image formation position control pattern 1027 a and toner image density control pattern 1027 a , respectively. [0114] As described above, with the provision of the recovery mode, in which the residues having adhered to the intermediary transfer belt 8 as an image bearing member are removed; the image forming apparatus can be corrected in the position of the area across which a toner image is formed; and the image forming apparatus is corrected in the density level at which a toner image is formed, a user is enabled to quickly eliminate the cause(s) of the formation of an defective image, even when it (they) cannot be identified by the user. [0115] Incidentally, in the case of the above described method shown in FIG. 14 a , the image forming apparatus is corrected in the toner image formation position and toner image density, after the completion of the recovery mode. The step (S 23 ) for correcting the image forming apparatus in terms of the toner image formation position may be carried out immediately after the step (S 22 ) in which the toner image formation position control pattern is detected by the combination of the light emitting element 1028 and photosensitive element 1029 , as shown in FIG. 14 b . Further, the step (S 32 ) in which the image forming apparatus is corrected in toner image density may be carried out immediately after the step (S 32 ) in which the toner image density control pattern 1027 a is detected by the combination of the light emitting element 1028 and photosensitive element 1029 , as shown in FIG. 14 b. [0116] Next, referring to FIG. 16 , the total length of time used, in this embodiment, for detecting the images of the toner image position control pattern 1027 b and toner image density control pattern 1027 a is 63.8 seconds, being shorter than the length of time necessary for satisfactorily removing the residues on the intermediary transfer belt 8 , which is 180 seconds. [0117] In this embodiment, the toner image position control pattern 1027 b and toner image density control pattern 1027 a are detected during the removal of the adherent residue on the intermediary transfer belt 8 . Therefore, the length of time the image forming apparatus in accordance with the present invention cannot be used for image formation is 180 seconds. In other words, it is roughly 55 seconds shorter than the length of the time for the recovery mode required by an image forming apparatus which does not carry out the process of detecting the toner image position control pattern 1027 b and toner image density control pattern 1027 a at the same time as it carries out the process of removing the adherent residue on the intermediary transfer belt 8 . Thus, the employment of this embodiment also reduces the time necessary for the recovery mode. Embodiment 2 [0118] In this embodiment, the image forming apparatus is provided with a door switch or the like which makes it possible to detect whether or not the door is open. Further, the image forming apparatus is designed so that as the door with a door switch is opened by an operator who inferred that the formation of a defective image was attributable to the presence of residues on the intermediary transfer belt, the recovery mode in the first embodiment is automatically carried out. Embodiment 3 [0119] FIG. 18 shows the image forming apparatus in this embodiment. The components of this image forming apparatus, which are similar in structure and function, are given the same referential symbols as those given to their counterparts of the image forming apparatus in the first embodiment, and will not be described. [0120] Referring to FIG. 18 , referential symbols 1061 a , 1061 b , 1061 c , and 1061 d designate transfer voltage detecting means for detecting the voltages which generate as biases which are proportional in amplitude to preset amount of electric current are applied to transfer rollers 5 a , 5 b , 5 c , and 5 d by transfer power sources 1060 a , 1060 b , 1060 c , and 1060 d , respectively. Designated by referential symbols 1062 a , 1062 b , 1062 c , and 1062 d are transfer voltage controlling means for controlling the voltages of the biases applied to the transfer rollers 5 a , 5 b , 5 c , and 5 d , according to the results of the detection by the transfer voltage detecting means 1061 a , 1061 b , 1061 c , and 1061 d , when transferring toner images from the image bearing members 2 a , 2 b , 2 c , and 2 d , respectively. [0121] In this embodiment, the recovery mode in the first embodiment is provided with an additional step which is carried out by the transfer voltage controlling means 1062 a , 1062 b , 1062 c , and 1062 d , at least before the detection of the image of the toner image density control pattern 1027 a , in order to control in voltage the biases applied to the transfer rollers 5 a , 5 b , 5 c , and 5 d , respectively. FIG. 19 shows the recovery mode sequence in this embodiment. Embodiment 4 [0122] In this embodiment, the image forming apparatus is provided with such a control portion as the one shown in FIG. 20( a ). As a user depresses the intermediary transfer belt residue removal starting means 701 of the control panel 700 of the image forming apparatus, the same process as the one carried out by the image forming apparatus in the first embodiment is carried out to remove the residues having adhered to the intermediary transfer belt 8 . Then, the user is to depress the mode setting button 702 of the control panel 700 to switch the display to the mode setting window, which enables the user to choose to, or not to choose to, carry out the process of controlling the toner formation position, and/or the process of controlling the toner image formation conditions. [0123] FIG. 21 a is a flowchart of the recovery mode sequence in the fourth embodiment of the present invention, in which a selecting means can be used to clean the intermediary transferring member without carrying out the process of controlling the image forming apparatus in toner image position and toner image density. [0124] This sequence will be described with reference to FIG. 21 a. [0125] FIG. 20 b shows the window 703 for instructing the image forming apparatus to carry out, or not to carry out, the image correction processes. A user can use this control selecting means 703 to choose, or not to choose, to cause the image forming apparatus to carry out the process of controlling the image forming apparatus in toner image formation position and toner image formation conditions at the same time as the process of removing the residues having adhered to the intermediary transfer belt 8 (Step S 1 in FIG. 21 a ). [0126] If the user chooses not to carry out the process of controlling the image forming apparatus in toner image formation position and toner image density at the same time as the residue removal, and depresses the residue removal starting means 701 to carry out the process of removing the residue, the display switches to the window shown in FIG. 20 c , informing thereby the user that the image forming apparatus is going to carry out only the residue removal operation, and then, the residue removal operation begins (Steps S 31 and S 32 in FIG. 21 a ). [0127] If the user chooses to carry out the process of controlling the toner image formation position and process of controlling the toner image density at the same time as the residue removal, and depresses the residue removal starting means 701 to cause the image forming apparatus to carry out the process of removing the residue, the toner image position control pattern 1027 b and toner image density control pattern 1027 a are formed immediately after the removal of the residues (Steps S 21 and S 22 in FIG. 21 a ). Then, the toner image position control pattern 1027 b and toner image density control pattern 1027 a are detected (Step S 23 in FIG. 21 a ). [0128] Then, the process of controlling the image forming apparatus in toner image formation position and toner image density are carried out during the period between the completion of the recovery mode, that is, the completion of the residue removal, and the starting of the formation of the next image. [0129] Incidentally, an image forming apparatus may be designed so that its CPU instructs the apparatus to begin to carry out the process of controlling the image forming apparatus in toner image formation position and toner image density after Step S 23 , and to complete the process before the completion of the residue removal process, as shown in FIG. 21 b (Step S 24 in FIG. 21 b ). Embodiment 5 [0130] FIG. 22 shows a residue removal mode starting means (window) 800 different from the one in the preceding embodiments. In the case of this residue removal mode starting means 800 , through which a user can instruct an image forming apparatus to carry out the process of clearing the intermediary transfer belt 8 of the residues thereon, is a part of a computer or a workstation. As a user depresses (touches) the residue removal starting means 801 of the control portion 800 , the above described process of clearing the intermediary transfer belt 8 of the residues thereon, and the process of controlling the image forming apparatus in toner image formation position and toner image formation conditions, begin. Also in the case of this embodiment, a user is allowed to choose, or not to choose, to cause the image forming apparatus to carry out the process of controlling the image forming apparatus in toner image formation position and toner image formation conditions at the same time as the process of removing the residues having adhered to the intermediary transfer belt 8 . [0131] While the invention has been described with reference to the structures disclosed herein, it is not confined to the details set forth, and this application is intended to cover such modifications or changes as may come within the purposes of the improvements or the scope of the following claims. [0132] This application claims priority from Japanese Patent Application No. 329235/2004 filed Nov. 12, 2004 which is hereby incorporated by reference.

An image forming apparatus includes an image bearing member; toner image formation means for forming a toner image on the image bearing member; removing means for removing deposited matter deposited on the image bearing member; detecting means for detecting a toner image to be detected, formed on the toner image formation means; control means for controlling a toner image forming condition of the toner image forming means in accordance with a result of detection of the toner image to be detected by the detecting means; the apparatus being operable in a mode in which the removing means operates to remove the deposition, and the detecting means operates to detect the toner image to be detected, executing means for executing an operation in the mode; and an operating portion for manually starting execution of the operation in the mode by the executing means.

This application is a continuation-in-part of application Ser. No. 08/237,337 filed May 3, 1994(abandoned), which is a continuation of application Ser. No. 07/956,770 filed Dec. 17, 1992, now abandoned. BACKGROUND OF THE INVENTION 1. Technical Field of the Invention This invention relates to a press machine having a frame which is C-shaped in side elevational view, a bolster which is mounted on a bed of a lower jaw portion of the frame, and a slide which is mounted on an upper jaw portion of the frame. More particularly, this invention relates to a press machine whose side frames are reinforced by reinforcing members. 2. Discussion of Related Art A prior art example of a press machine i to which the present invention relates is shown in FIG. 1. A frame 2 of the press machine 1 is C-shaped in side elevational view, and has a lower jaw portion with a bed 4 supported thereon, and an upper jaw portion with a slide 5 and a driving unit for driving the slide 5 supported thereon. The arrangement is made such that when the slide 5 is lowered by rotation of a main spindle, a workpiece (not shown) positioned on a lower die 7 mounted on a bolster 4a resting on the bed 4 is punched by an upper die (punch) 6 fixedly secured to the slide 5. In FIG. 1, reference numeral 3 denotes a front side plate of the frame, and reference numeral 8 denotes a side frame. In the above-mentioned prior art press machine 1, to suppress or reduce the vibration of the frame 2 or the level of noise generated by the press, for example, either (1) a vibration damping material is mounted on the surface of the frame, or (2) the whole press machine is surrounded by a box to isolate the noise. (Refer, for example, to "Examples of Measures for controlling Noise generated by Press Machines", collection of lectures and thesis on technique presentation conferences issued by Japanese Noise Control Engineering Society, P141, September 1989). Further, as shown in FIGS. 2 and 3, a third prior art alternative (3) for reducing or suppressing the vibration of the frame or the level of noise generated includes mounting an L-shaped reinforcing plate-shaped member 9 on the inner surface of each of the side frames 8. The problem with mounting a vibration damping material on the surface of the frame, as in the abovementioned case (1), is that it causes an increase in the weight and cost of the entire press machine. For effective vibration damping, the thickness of the vibration damping material must be at least equal to or more than that of the frame, so that if the thickness of the frame is 22 mm, for example, then the total thickness of the frame and the vibration damping material becomes about 50 mm, thus increasing the weight of the entire press machine, giving disadvantages in terms of cost and practicality. Further, where the whole press machine is surrounded by a box, as in the above-mentioned case (2), other problems exist relating to press operation, cost and the need for increased working space in factories. Still further, in the above-mentioned alternative (3), as shown in FIGS. 2 and 3, because the plate-shaped member 9 is fixedly secured to each of the side frames 8 as the reinforcing member thereof, the reinforcing effect for preventing the opening formed between the upper and lower jaws of the frame from flaring was limited. Further, the prior art reinforcing member 9 mounted on the side frames 8 so as to extend upwards from the upper jaw portion is inefficient as a reinforcing member since only a small loading is applied to this portion. A fourth alternative (4) for reducing or suppressing the vibration of the frame is described in Japanese Patent Publication 55-46399. This alternative uses a pair of tie rods 2 extending between opposite side frames 1, 1' of a press machine. The tie rods 2 are fixed to each side frame by means of a nut 3 and a load plate 4, 5. A preload is applied to the tie rods 2 to reduce or suppress at least certain kinds of vibrations occurring in the side frames during operation. The '399 device uses a vibration damping technique which relies on an increased stiffness of the structure to reduce the vibration amplitude. The vibration energy itself is not dispersed into another form of energy (e.g., heat)--it is just converted into a different amplitude. The '399 device has significant drawbacks. The arrangement of the tie rods 2 between the side frames substantially limits or interferes with the arrangement of a device or mechanisms disposed inside the press machine. Moreover, the preload strain applied to the press body of the device by the tie rods 2 is disadvantageous because it creates damaging stress in the side frames and tends to disorder the positioning accuracy of the mechanisms within the frame. Thus, the use of the tie rods requires readjustment of the mechanisms for proper performance after securing the tie rods, thereby creating an additional inconvenience. Further, the vibration damping effects of the tie rod arrangement of the '399 device is less than satisfactory because the arrangement is not effective against antisymmetric vibrations of the side frames (i.e., both side frames moving in the same direction in the same phase) during operation of the press machine. SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances in the prior art, and has for its principal object to provide a press machine which is effectively reinforced so as to improve the working accuracy of finished products without installing any special device on the outside of the press machine, without extremely increasing the weight of the entire press machine, and without obstructing the space between the side frames, and which is capable of reducing appreciably the level of noise generated by the machine in operation. To achieve the above-mentioned object, the inventors of the present invention analyzed the vibration and noise generating mechanism of the existing press machines. In a press machine 1, as shown in FIG. 1, when a slide 5 is lowered by rotation of a main spindle to allow an upper die (punch) 6 fixedly secured to the slide 5 to punch a workpiece (not shown) on a lower die 7 mounted on a bolster 4a resting on a bed 4, a frame 2 of the press machine 1 is subjected to a resistance to shearing of the workpiece so that a big magnitude of force is exerted on the frame 2. The big magnitude of force tends to flare the opening formed between the upper and lower jaws of the frame. The workpiece is then cracked and broken suddenly. This breaking of the workpiece causes release of the loading therefrom, thus generating shock, which is propagated to the entire press machine, thereby generating noise and vibration. Further, when the force is exerted on the frame 2, which tends to flare the opening formed between the jaws thereof, a misalignment occurs between the upper die 6 and the lower die 7, thereby tending to reduce the accuracy of finished products. FIG. 4 is a graph showing the relationship between punching load and noise (breakthrough noise). As shown by this graph, the lower the punching load, that is, the smaller the amount of deformation or flare of the opening of the frame 2 when the press machine is subjected to the resistance of shearing of the workpiece, the lower the level of noise becomes. In a press machine with a C-shaped frame, the amount of deformation of the notched portion of the upper jaw portion is the biggest. Consequently, if a reinforcing plate is fixedly secured to this upper jaw portion so as to eliminate the notched portion, then the above-named amount of deformation or flare of the opening of the frame 2 is reduced, thus reducing the breakthrough noise. Further, as another means for reducing the level of the breakthrough noise, noise generating portions of the press machine may be removed. As a result of experiments, it was found out that the noise generated by the rear, upper portion of the side frames is 20% of the noise generated by the entire press machine making this portion the principal noise generating source. Therefore, the breakthrough noise can be reduced by removing this portion. The foregoing reveals that if the amount of deformation or flare of the opening of the frame of the press machine is suppressed, the noise level can be reduced, and the accuracy of finished products can be improved. The present invention has been made on the basis of this finding. To achieve the above-mentioned object, according to a first aspect of the present invention, there is provided a press machine having a frame which is C-shaped in side elevational view, a bolster which is mounted on a lower jaw portion of the frame, and a slide and a drive system for driving the slide which are mounted on an upper jaw portion of the frame, characterized in that a means for suppressing vibrations in the side frames without obstructing a space between the side frames is provided including at least one reinforcing member fixedly secured to each of a pair of side frames forming both sides of the frame at at least one predetermined place so as to suppress the deformation or flare of the opening of the frame. Further, according to a second aspect of the present invention, there is provided a press machine as set forth in the above-mentioned first aspect, characterized in that the reinforcing member has substantially the same shape as a substantially inverted trapezoidal throughhole formed in the rear, upper portion of each of the side frames and has the same thickness as the latter, and is fixedly secured to the upper side surface of an upper jaw portion of each of the side frames. According to a third aspect of the present invention, there is provided a press machine as set forth in the above-mentioned first aspect, characterized in that the reinforcing member is an L-shaped plate member corresponding to the configuration of a zone which extends from the leading end of the lower jaw portion to the uppermost portion of the innermost upright wall of the recess, and at least two pieces of reinforcing members are superposed and fixedly secured to the zone on the inner surface of each of the side frames. Further, according to a fourth aspect of the present invention, there is provided a press machine as set forth in the above-mentioned first aspect, characterized in that the reinforcing member is a sheet of strip-shaped plate member, and is fixedly secured to a vertically intermediate portion of the inner surface of each of the side frames along the rear edge thereof. Yet further, according to a fifth aspect of the present invention, there is provided a press machine as set forth in the above-mentioned first aspect, characterized in that the reinforcing member is a substantially rectangular plate member, and is fixedly secured by means of bolts or by plug welding to the inner surface of each of the side frames at a plurality of places. According to the present invention incorporating the above-mentioned aspects, the following advantages are obtained. The press machine is effectively reinforced so as to improve the working accuracy of finished products without the need for installing any special device on the outside thereof, without increasing extremely the weight of the entire press machine, without obstructing the space between the side frames, and which is capable of reducing appreciably the level of noise generated by the machine in operation. The reinforcement is provided without creating a preload stress in the side frames so that an accuracy of the mechanisms within the press frame is maintained, and both asymmetric and symmetric vibrations are effectively suppressed. Stating in brief, since each of the side frames is reinforced by at least one plate member at at least one suitable place, the deformation of the frame or flare of the opening formed between the upper and lower jaws of the frame which tends to occur in operation is reduced, thereby reducing vibration, and hence, the noise caused thereby, and also improving working accuracy of finished products. The above-mentioned and other objects, aspects and advantages of the present invention will become apparent to those skilled in the art by making reference to the following description and the accompanying drawings in which preferred embodiments incorporating the principles of the present invention are shown by way of examples only. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic, overall perspective view showing a prior art press machine which is C-shaped in side sectional view. FIG. 2 is a schematic, side elevational view showing a prior art example of reinforcement of a side frame; FIG. 3 is a sectional view taken along line III--III in FIG. 2; FIG. 4 is a graph showing the relationship between the punching load and the noise; FIGS. 5, 6 and 7 are schematic interior side elevational views showing first, second and third embodiments of the present invention; FIG. 8 is a sectional view taken along line VIII--VIII in FIG. 7; FIGS. 9A and 9B are plan views showing reinforcing members used in the embodiment shown in FIG. 7; FIGS. 10 and 11 are schematic interior side elevational views showing a fourth embodiment of the present invention and its variant example; FIGS. 12 and 13 are fragmentary sectional views showing two examples of reinforcing members for use in the embodiments shown in FIGS. 10 and 11 which are fixedly secured to the side frames; and FIG. 14 is a graph showing the result of vibration damping experiments conducted in relation to the embodiments shown in FIGS. 10 and 11. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Several embodiments of the present invention will now be described in detail below with reference to FIGS. 5 to 14 of the accompanying drawings. A first embodiment of the present invention will be described with reference to FIG. 5. In this embodiment, the same component parts as those of the prior art example shown in FIG. 1 are denoted by the same reference numerals, and further description thereof is thus omitted. In FIG. 5, each of the left and right side frames 10 of a press machine 1 has a substantially inverted trapezoidal through-hole 11 formed in the rear, upper portion thereof. Further, each of the side frames 10 has a notched portion 12 formed above the upper jaw portion on the front side thereof. A piece of reinforcing plate 13 which is of a shape closing the side of the notched portion 12 is fixedly secured by welding to the notched portion 12. The member which is cut out from the side plate 10 to form the through-hole 11 is used as the reinforcing plate 13. Due to the above-mentioned construction, the area of the rear, upper portion of the side frame 10, which is a principal noise and vibration generating portion, is reduced, thereby reducing the noise and vibration generated in this portion. Further, the notched portion 12 formed above the upper jaw portion, which is subjected to a high loading, is reinforced by the reinforcing plate 13 so that the amount of flare of the opening formed between the upper and lower jaws of the side frames 10 is reduced by about 10% as compared with the prior art example, thereby reducing the breakthrough noise. The second embodiment of the present invention will be described with reference to FIG. 6. In FIG. 6, a vertically extending reinforcing plate 14 comprised of a strip-shaped plate member is fixedly secured to each of the left and right side frames 10 forming both side walls of the frame of a press machine along the rear edge of the inner surface thereof. When the length, height and thickness of the side frame 10 are denoted by L, H and T, the width W of the reinforcing plate 14 is preferably about 0.08 L (W=0.08 L), and the thickness t of the plate 14 (which is the dimension of the plate 14 in a direction at right angles to the side frame 10) is preferably about 1.5 T (t=1.5 T). Further, the height h 1 of the reinforcing plate 14 at the upper end thereof is preferably about 0.77 H (h 1 =0.77 H), and the length h 2 of the plate 14 in the direction of the height thereof is preferably about 0.48 H (h 2 =0.48 H). An example of the above-mentioned dimensions can be, L=1250 mm, T=55 mm, H=2210 mm, h 1 =1702 mm, and h 2 =1061 mm. Due to the above-mentioned construction, the deformation of the frame in the transverse direction is reduced by about 10% as compared with the prior art example of FIGS. 2 and 3. Next, the third embodiment of the present invention will be described with reference to FIGS. 7 to 9B. In FIG. 7, an L-shaped reinforcing member 15 is fixedly secured to the inner surface of each of the side frames 10 so as to extend from a leading end of a lower-jaw portion 10a of the C-shaped member to the top of a press operation zone 10b. The reinforcing member 15 has a height ι which corresponds to the height of the innermost upright wall of the recess. The reinforcing member 15 is comprised of a first reinforcing member 16a and a second reinforcing member 16b which are superposed and fixedly secured in two layers. These reinforcing members 16a and 16b are formed as shown in FIGS. 9A and 9B, respectively. When the height of the press operation zone of the side frame 10 is denoted by ι, the widths W 1 and W 2 of the reinforcing members 16a and 16b are as follows: W.sub.1 =1/2ι, W.sub.2 =1/3 ι The ratio of the thickness t 1 of the reinforcing member 16a to the thickness t 2 of the reinforcing member 16b is as follows: t.sub.1 :t2=1:2.2 One example of the actual dimensions of the reinforcing members 16a, 16b can be, ι=450 mm, W 1 =225 mm, W 2 =150 mm, t 1 =32 mm, and t 2 =70 mm. In the above-mentioned construction, the frame is reinforced by the first and second reinforcing members 16a and 16b to withstand the loading exerted thereon, which tends to flare the frame. Next, the fourth embodiment of the present invention and a variant example thereof will be described with reference to FIGS. 10 to 14. FIGS. 10 and 11 each show only one of the side frames 10 of the press machine. A substantially rectangular plate member 18 (or members 18) is (are) fixedly secured to the inner surface of the side frame 10 which is C-shaped in side view. There are two examples of the arrangement of the plate member 18 (or members 18). In one example, as shown in FIG. 10, a plurality of plate members 18 each having a small area are fixedly secured to the side frame at a plurality of places. In another example, as shown in FIG. 11, a single piece of plate member 18 having a large area is fixedly secured to the side frame 10 with the longer side thereof extending in the vertical direction. Further, a piece of plate member 18 whose thickness is about one-tenth of that of the side frame 10 or a plurality of separate plate members 18 are fixedly secured in a single layer to the side frame 10. Alternatively, a plurality of superposed plate members 18 each having the same thickness are fixedly secured in the form of one-piece or separate pieces to the side frame 10 as shown in FIGS. 12 and 13. Further, in respect of fixing means, the superposed plate members 18 are fixedly secured by means of bolts 19 to the side frame 10 at a plurality of places, as shown in FIG. 12, or they are fixedly secured by plug welding 20 to the side frame 10 at a plurality of places, as shown in FIG. 13. Preferably the total area of the bolts 20 or the plug welded joints is about 5 to 6% of the surface area of the plate member(s) 18. In the above-mentioned construction, when vibration is propagated to the side frame 10, the side frame 10 will vibrate together with the plate member 18 (or members 18) fixedly secured thereto. At that time, because both the side frame 10 and the plate member 18 (or members 18) have different natural frequencies and both the members 10 and 18 are fixedly secured to each other at a plurality of places, and held only in contact with each other in the remaining portions, the above-mentioned vibration causes the members 10 and 18 to strike or chafe against each other in the contact portions. Such striking or chafing energy will give a vibration damping effect so that the above-mentioned vibration energy is absorbed into the side frames as heat energy, thereby suppressing the vibration. Thus, the present invention relies on a vibration damping technique which converts vibrations into heat energy and disperses it into the structure itself. In contrast to the prior art (JP 55-46399) device which has tie rods extending between the side frames and relies on an increased stiffness in the structure to reduce vibration effects, the plate member(s) 18 of the present invention are effective against both symmetric vibrations (the side frames moving in opposing directions) and asymmetric vibrations (both side frames moving in the same direction in phase with each other). Moreover, as is clear from FIGS. 10 to 13 of the drawings, the superposed plate members 18 do not obstruct a space between the side frames 10, as do the tie rods 2 in the '399 device. The plate members 18 provide a means for suppressing vibrations in the side frames 10 while leaving the space between the side frames open for accommodating the most suitable arrangements and sizes of punching and pressing mechanisms (e.g., driving, lubricating, and controlling mechanisms, and the like). As used in this application, the phrase "without obstructing a space between the side frames" means without having a member extending between and connected to the two side frames, such as the tie rods 2 of the '399 device. Moreover, with the reinforcing plates 18 of the present invention it is not necessary to apply a preload to the side frames. This eliminates the inconveniences resulting from the repositioning of the mechanisms within the press machine of the '399 device after the preloading is applied by the tie rods 2. Experimental results on the degree of the abovementioned damping of vibration are shown in FIG. 14. In this drawing, reference characters "a" indicate the result obtained when side frames only 14 mm thick are provided, black dots indicate the result obtained when plate members are fixedly secured by plug welding to each of side frames, white dots indicate the result obtained when plate members are fixedly secured by means of bolts to each of the side frames, and X marks indicate the result obtained when prior art vibration damping materials were used. As is apparent from this graph, the construction according to the present invention could provide nearly the same vibration damping effect as that obtained by the construction using the prior art vibration damping material. The foregoing description is merely illustrative of preferred embodiments of the present invention, and the scope of the present invention is not to be limited thereto. It will readily occur to those skilled in the art many changes and modifications of the present invention without departing from the scope of the present invention.

A press machine having side frames which are effectively reinforced so as to appreciably reduce the noise generated during operation of the machine and improve the working accuracy of the machine without installing any special device on the outside thereof, significantly increasing the weight of the entire press machine, or obstructing a space between the side frames of the press machine. The side frames of the press machine are C-shaped in side view and are reinforced by at least one reinforcing member fixedly secured to each of the side frames at at least one predetermined place. The reinforcing members function to suppress the deformation of the opening of the C-shaped side frames to reduce noise and improve accuracy. The reinforcing members convert the vibrational energy of the side frames into heat energy which is then absorbed into the side frames.

FIELD OF THE INVENTION This invention relates to a gaming machine. More particularly, the invention relates to a gaming machine and to an improvement to a game played on such a gaming machine. BACKGROUND TO THE INVENTION Players who regularly play gaming machines quickly tire of particular games and therefore it is necessary for manufacturers of these machines to develop innovative game features which add interest to the games. In so doing, it is hoped to keep players amused and therefore willing to continue playing the game as well as to attract new players. Also, with the growth that has occurred in the gaming machine market, there is intense competition between manufacturers to supply various existing and new venues. When selecting a supplier of gaming machines, the operator of a venue will often pay close attention to the popularity of various games with their patrons. Therefore, gaming machine manufacturers are keen to devise games and/or game features which are popular with the players as a mechanism for improving sales, retaining customers and attracting new customers. Still further, these days it is becoming increasingly common to provide bonus features associated with games to enhance player enjoyment and to maintain player interest. These features are becoming increasingly complex to the extent that gaming machines these days often have “Help” screens to explain to players how the features operate and what they entail. A large percentage of players do not have the inclination to read such screens and would rather just play the game. Hence such screens could be a disincentive to a player to play that particular gaming machine. This could have adverse consequences for the revenue of an operator of the venue in which the gaming machine is installed. SUMMARY OF THE INVENTION According to a first aspect of the invention, there is provided a gaming machine having a display and a game controller arranged to control images of symbols displayed on the display, the game controller being arranged to play a game wherein at least one random event is caused to be displayed on the display and, if a predefined winning event occurs, the machine awards a prize, the gaming machine comprising a bonus feature that is triggered when a trigger condition occurs in a base game and an indicator incorporated in the bonus feature that indicates to the player that the chance of winning during the bonus feature is higher than in the base game that triggered the bonus feature. Preferably, the format of the bonus feature is the same as that of the base game apart from the indicator incorporated in the bonus feature. Thus, the base game may be a spinning reel game with the bonus feature being a series of free spinning reel games. The indicator may be a variable device that indicates to the player that, as the bonus feature, i.e. the series of free games, progresses, the potential return to player percentage increases. The indicator may be related to the occurrence of a special symbol on the display of the gaming machine during play of the bonus feature. More particularly, the indicator may be the quantity of a special symbol that occurs during the bonus feature, i.e. on at least one of the reels of the games of the series of free games. The occurrence of the special symbol may increase on the at least one reel as the bonus feature, being the series of free games, progresses. The controller may provide the variability of the indicator by causing a special symbol to be added in respect of each event of the bonus feature. Each event may be one of the free games and one special symbol may be added in respect of each free game, eg. prior to the free game. Instead, the special symbol may only be added after completion of a predetermined number of events in the bonus feature, i.e. after a predetermined number of free games of the series of free games. Still further, the special symbol may be added randomly or upon the occurrence of some outcome in the bonus feature. As indicated above, the base game may be a spinning reel game and the bonus feature may be a series of free spinning reel games and the special symbol may be added to at least one of a plurality of reel strips so that the at least one reel strip increases in length. Instead, the special symbol may be added in substitution for existing symbols on at least one of a plurality of reel strips so that the at least one reel strip retains the same length as the other reel strips. Thus, the special symbol may be added to a middle reel strip of a five reel game or, instead, the special symbol may be added to each of a plurality of the reel strips, eg. the second, third, fourth and fifth reel strips of the game. The special symbol may be a substitute symbol. The substitute symbol may, for example, occur on a middle reel such as the third reel of a five reel game. With the occurrence of an increasing number of substitute symbols during the series of free games, the chances of obtaining a prize winning combination with the substitute symbol substituting are increased. Preferably, any additional substitute symbol is positioned adjacent a prior occurrence of the substitute symbol on the reel strip so that it becomes, visually, readily apparent to the player that at least one further substitute symbol has been added. According to a second aspect of the invention, there is provided a method of operating a gaming machine, the gaming machine having a display and being controlled by a game controller arranged to control images displayed on the display, the method comprising triggering a bonus feature when a trigger condition occurs in a base game and incorporating an indicating means in the bonus feature to indicate to the player that a potential return to player percentage of the bonus feature is higher than that which is applicable in the base game that triggered the bonus feature. The gaming machine is to be understood to include a gaming apparatus that does not require the wagering of a stake in order to play the game and further includes apparatus which is connectable to a network. The format of the bonus feature may be the same as that of the base game apart from the indicator incorporated in the bonus feature. The method may include implementing the indicator as a variable device that indicates to the player that, as the bonus feature progresses, the potential return to player percentage increases. More particularly, the method may include relating the indicator to the occurrence of a special symbol on the display during play of the bonus feature. The indicator may be the quantity of a special symbol occurring during the bonus feature and the method may include increasing the occurrence of the special symbol as the bonus feature progresses. The method may include providing the variability of the indicator by causing a special symbol to be added in respect of each event of the bonus feature. Thus, the method may include adding the special symbol after completion of a predetermined number of events in the bonus feature. Instead, the method may include adding the special symbol randomly or upon the occurrence of some outcome in the bonus feature. The game includes a base game which is a spinning reel game and the bonus feature may be a series of free spinning reel games and the method may include adding a special symbol to at least one of a plurality of reel strips so that the at least one reel strip increases in length. Instead, the method may include adding the special symbol in substitution for existing symbols on at least one of a plurality of reel strips so that the at least one reel strip retains the same length as the other reel strips. The special symbol may be a substitute symbol. The method may include positioning any additional substitute symbol adjacent a prior occurrence of the substitute symbol on the reel strip so that it becomes, visually, readily apparent to the player that at least one further substitute symbol has been added. BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the invention is now described by way of example with reference to the accompanying diagrammatic drawings in which:— FIG. 1 shows a perspective view of a gaming machine, in accordance with the invention; FIG. 2 shows a block diagram of a control circuit of the gaming machine; FIG. 3 shows a screen display after a base game of a game played on the gaming machine of FIG. 1 ; FIG. 4 shows a screen display after a first game of a bonus feature of the game following the base game; and FIG. 5 shows a flow chart of the game, including the bonus feature. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1 , reference numeral 10 generally designates a gaming machine, including a game, in accordance with an embodiment of the invention. The machine 10 includes a console 12 having a display means in the form of a video display unit 14 on which a game 16 is played, in use. The video display unit 14 may be implemented as a cathode ray screen device, a liquid crystal display, a plasma screen, or the like. The game 16 is a spinning reel game which simulates the rotation of a number of spinning reels 18 . A midtrim 20 of the machine 10 houses a bank 22 of buttons for enabling a player to play the game 16 . The midtrim 20 also houses a credit input mechanism 24 including a coin input chute 24 . 1 and a bill collector 24 . 2 . The machine 10 includes a top box 26 on which artwork 28 is carried. The artwork 28 includes paytables, details of bonus awards, etc. A coin tray 30 is mounted beneath the console 12 for cash payouts from the machine 10 . Referring to FIG. 2 of the drawings, a control means or control circuit 32 is illustrated. A program which implements the game and user interface is run on a processor 34 of the control circuit 32 . The processor 34 forms part of a controller 36 that drives the screen of the video display unit 14 and that receives input signals from sensors 38 . The sensors 38 include sensors associated with the bank 22 of buttons and touch sensors mounted in the screen of the video display unit 14 . The controller 36 also receives input pulses from the mechanism 24 to determine whether or not a player has provided sufficient credit to commence playing. The mechanism 24 may, instead of the coin input chute 24 . 1 or the bill collector 24 . 2 , or in addition thereto, be a credit card reader (not shown) or any other type of validation device. Finally, the controller 36 drives a payout mechanism 40 which, for example, may be a coin hopper for feeding coins to the coin tray 30 to make a pay out to a player when the player wishes to redeem his or her credit. The game 16 played on the gaming machine 10 is a spinning reel game having five reels 18 . Further, the game 16 includes a bonus feature where, upon the occurrence of a predetermined trigger condition in a base game of the game 16 , a series of free games is awarded. The bonus feature includes an indicator, as will be described in greater detail below, which clearly indicates to a player that the potential return to player percentage in the bonus feature is higher than that which is applicable in respect of the base game of the game 16 . In the description which follows, it is assumed that wins, both in the base game and in the free games of the bonus feature, pay from left-to-right. For the game 16 described in this example, it is assumed that the set of symbols applicable to the reel strips is as follows: DIAMOND (substitute) SYM_A SYM_B SYM_C A K Q 10 9 S (scatter) The DIAMOND symbol 58 ( FIG. 4 ) is a substitute symbol which substitutes for all other symbols, apart from scatters in making up winning combinations. For each symbol, apart from the DIAMOND symbol 58 , there will be a paytable of prizes that applies for certain winning combinations. For example, 5 SYM_A on a payline pays 500 credits (multiplied by the bet per line), 4 SYM_A appearing in a left-to-right combination pays 100 credits (multiplied by the bet per line) and so on. Similarly, 5 scatter symbols S (the scatter symbol) appearing anywhere on the screen pays 20 credits (multiplied by the total bet), 4 scatter symbols S appearing anywhere on the screen pays 15 credits (multiplied by the total bet) and so on. The occurrence of at least 3 scatter symbols S also functions as a trigger condition to award the bonus feature, as will be described below. For each winning payline combination, one of the applicable symbols may be substituted by the DIAMOND symbol 58 to make up the winning combination. The simplified reel strips for the reels 18 for the base game of the game 16 are as follows: Position Reel 1 Reel 2 Reel 3 Reel 4 Reel 5  1 SYM_A SYM_B SYM_C 10 A  2 A K K SYM_A SYM_C  3 K  9  9 Q J  4 SYM_B SYM_C A A 10  5 Q Q 10 10  9  6 DIA- DIA- DIA- DIA- DIA- MOND MOND MOND MOND MOND  7 10 A  9 Q A  8 A  9 SYM_A SYM_C SYM_C  9  9 SYM_A K K Q 10 SYM_C SYM_A SYM_B A SYM_A 11 10 SYM_A Q SYM_B A 12 J SYM_A 10 Q K 13 A 10 K J SYM_C 14 10 J J A J 15 SCAT SCAT SCAT SCAT SCAT 16  9 10  9  9 A 17 10 A 10 Q SYM_B 18 A  9 K SYM_B J 19  9 10  9 K SYM_C 20 J A 10 A J Hence, the base game of the game 16 may have some occurrences of the same symbol positioned next to each other for visual effect such as, in the case of reel strip 2, four occurrences of the top award symbol, SYM_A, are arranged next to one another in positions 9-12. As indicated above, the occurrence of three scatter symbols S in the base game of the game 16 triggers the bonus feature being, as described above, a series of ten free games. FIG. 3 of the drawings shows a screen display 50 of the base game where it is assumed that the reels 18 have stopped at reel strip positions 15, 11, 14, 16 and 13, respectively, on the first payline. The occurrence of the three scatter symbols S results in a win of ten credits (multiplied by three credits being the total bet) for a total win of thirty credits. This is displayed on a win meter 52 of the gaming machine 10 . A message 54 is displayed on the screen display indicating that the bonus feature has been awarded and that ten free games are remaining. Prior to each free game of the series of free games, one DIAMOND symbol 58 ( FIG. 4 ) is added to the third reel strip. The additional DIAMOND symbol 58 is added adjacent another occurrence of the DIAMOND symbol 58 on the third reel strip. Accordingly, prior to the first free game, the reel strips will change to the following: Position Reel 1 Reel 2 Reel 3 Reel 4 Reel 5  1 SYM_A SYM_B SYM_C 10 A  2 A K K SYM_A SYM_C  3 K  9  9 Q J  4 SYM_B SYM_C A A 10  5 Q Q 10 10  9  6 DIA- DIA- DIA- DIA- DIA- MOND MOND MOND MOND MOND  7 10 A DIA- Q A MOND  8 A  9  9 SYM_C SYM_C  9  9 SYM_A SYM_A K Q 10 SYM_C SYM_A K A SYM_A 11 10 SYM_A SYM_B SYM_B A 12 J SYM_A Q Q K 13 A 10 10 J SYM_C 14 10 J K A J 15 SCAT SCAT J SCAT SCAT 16  9 10 SCAT  9 A 17 10 A  9 Q SYM_B 18 A  9 10 SYM_B J 19  9 10 K K SYM_C 20 J A  9 A J 21 10 That is, reel strip 3 has been extended by one position and a further DIAMOND symbol 58 has been inserted at position 7 adjacent to the other occurrence of the DIAMOND symbol 58 on the third reel strip. Assuming that in the first free game the reels 18 stop at reel strip positions 3, 2, 6, 2 and 2, the screen display is as shown in FIG. 4 of the drawings and is designated generally by the reference numeral 60 . For the winning combination of 3×K (with the DIAMOND symbol 58 substituting) on payline 1, a prize of 25 credits, the player playing one credit per line, is awarded and displayed on the win meter 52 . There are then nine free games remaining as indicated by the message 54 . After the tenth free game, ten additional DIAMOND symbols 58 have been added to the third reel strip so that the reel strips now appear as follows: Position Reel 1 Reel 2 Reel 3 Reel 4 Reel 5  1 SYM_A SYM_B SYM_C 10 A  2 A K K SYM_A SYM_C  3 K 9 9 Q J  4 SYM_B SYM_C A A 10  5 Q Q 10 10 9  6 DIA- DIA- DIA- DIA- DIA- MOND MOND MOND MOND MOND  7 10 A DIA- Q A MOND  8 A 9 DIA- SYM_C SYM_C MOND  9 9 SYM_A DIA- K Q MOND 10 SYM_C SYM_A DIA- A SYM_A MOND 11 10 SYM_A DIA- SYM_B A MOND 12 J SYM_A DIA- Q K MOND 13 A 10 DIA- J SYM_C MOND 14 10 J DIA- A J MOND 15 SCAT SCAT DIA- SCAT SCAT MOND 16 9 10 DIA- 9 A MOND 17 10 A 9 Q SYM_B 18 A 9 SYM_A SYM_B J 19 9 10 K K SYM_C 20 J A SYM_B A J 21 Q 22 10 23 K 24 J 25 SCAT 26 9 27 10 28 K 29 9 30 10 Accordingly, as the free games progress, the player's chances of winning are greatly increased because of the higher chance of getting a substitute symbol on the third reel strip. The DIAMOND symbol 58 is designed to stand out from the remaining symbols on the reels 18 so that, as the reels 18 spin, the player has a readily identifiable visual effect of seeing the DIAMOND symbols 58 spinning past. Hence, as extra DIAMOND symbols 58 are added to the third reel, the player has the visual confirmation that the potential return to player percentage is increasing due to the increased number of DIAMOND symbols 58 spinning past. It will be appreciated that, by the later games of the series of free games, there is a very high chance of one or more DIAMOND symbols 58 being displayed when the third reel 18 stops spinning. Instead of the reel strip associated with the third reel 18 being increased in length by the addition of further DIAMOND symbols 58 , the reel strip associated with the third reel 18 could remain the same length as the other reel strips by substituting the DIAMOND symbol 58 for other symbols presently on the reel strip of the third reel 18 . In another embodiment of the invention (not shown), additional DIAMOND symbol 58 are added to each of the second, third, fourth and fifth reels 18 as the free games of the series of free games progresses therefore increasing the likelihood of a winning outcome being obtained even further, particularly, in the later games of the series of free games. It is also not necessary that the positioning of the other symbol on the reel strips remain completely constant during all the free games of the series of free games. Their distribution may alter. It is a particular advantage of the invention that an indicator is provided which readily indicates to a player that the potential return to player percentage for the free game is higher and increases during the bonus feature. Hence, the player need not, if the player does not wish to do so, consult a “Help” screen of the gaming machine 10 to ascertain how the bonus feature works. The applicant believes that this will enhance player enjoyment of the game. It will also enhance revenue for operators of a venue in which the gaming machine 10 is installed as players will be less reticent about playing the game if they know, in a simplified manner, how the bonus feature works and that it is not necessary to consult a “Help” screen should they not wish to do so. Another major benefit of the invention is that, as the bonus feature progresses, the chances of winning increases. Hence, the last impression that is left in the mind of the player is likely to be a good one as the player is more likely to end the feature with one or more winning games and higher payouts than non-winning games and lower payouts. It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

A gaming machine 10 has a display 14 and a game controller arranged to control images of symbols displayed on the display 14 . The game controller is arranged to play a game 16 wherein at least one random event is caused to be displayed on the display and, if a predefined winning event occurs, the machine 10 awards a prize. The gaming machine 10 comprises a bonus feature that is triggered when a trigger condition occurs in a base game and an indicator incorporated in the bonus feature indicates to the player that the chance of winning during the bonus feature is higher than in the base game that triggered the bonus feature.

REFERENCE TO RELATED APPLICATIONS This application claims priority benefits to the U.S. provisional application Serial No. 60/161,275 filed on Oct. 25, 1999. This application incorporates by reference in its entirety the U.S. provisional application Serial No. 60/161,275, filed on Oct. 25, 1999. FIELD OF THE INVENTION The present invention relates to fast programmable Electrically Erasable Programmable Read-Only Memory devices and method for operating such devices. BACKGROUND OF THE INVENTION Nowadays, most Flash memories use Channel Hot Electron Injection (“CHEI”) at the drain side of the memory cell, or Fowler-Nordheim Tunnelling (“FNT”) for programming. The Channel Hot Electron Injection mechanism provides a relatively high programming speed (˜10 μs) at the expense of a high power consumption (˜400 μA/bit) which limits the number of cells that can be programmed simultaneously (so-called page-mode programming) to a maximum of 8 bytes (Y. Miyawaki et al., IEEE J. Solid-State Circuits, vol.27, p.583, 1992). Furthermore, in order to allow a further scaling of the transistor dimensions towards 0.18 μm and below, supply voltage scaling from 3.3V towards 1.8V also becomes mandatory. This supply voltage scaling is known to degrade the Channel Hot Electron Injection efficiency and, hence, the corresponding programming speed considerably. These memories already use a bitline charge pump to provide a 4-5V drain voltage to the cell during programming and erasing. The problem with this solution is two-fold: (1) since the internally generated programming voltages are not scaled down with respect to the technology generation, it becomes practically impossible to further scale the cell itself, in terms of both vertical (dielectric thicknesses) and lateral (gate length) dimensions; (2) due to the high power needed to trigger the Channel Hot Electron Injection, it becomes harder and harder to supply these voltages on-chip from a high voltage generator or charge pumping circuit. Also, the relative area of the charge pumps and the corresponding high-voltage switching circuitry increases with respect to the useful area of the memory chip. On the other hand, tunnelling provides slower programming times (˜100 μs) and a low power consumption which allows larger pages (˜4 kbit) in order to reduce the effective programming time to 1 μs/byte (T. Tanaka et al., IEEE J. Solid-State Circuits, vol.29, p.1366, 1994). However, a further improvement is limited by tunnel-oxide scaling limits and by the very high voltages (˜15V) needed on chip for Fowler-Nordheim Tunnelling, both compromising device reliability and process scalability. The recent success of Source-Side Injection (“SSI”) as a viable alternative over Fowler-Nordheim Tunnelling and Channel Hot Electron Injection for Flash programming is mainly due to its unique combination of moderate-to-low power consumption with very high programming speed at moderate voltages. A typical example of such a device relying on Source-Side Injection for programming is the High Injection Metal-Oxide-Semiconductor or HIMOS® memory cell (J. Van Houdt et al., 11th IEEE Nonvolatile Semiconductor Memory Workshop, February 1991; J. Van Houdt et al., IEEE Trans. Electron Devices, vol.ED-40, p.2255, 1993). As also described in the U.S. Pat. Nos. 5,583,810 and 5,583,811, a speed-optimized implementation of the HIMOS® cell in a 0.7-μm CMOS technology exhibits a 400 nanoseconds programming time while consuming only a moderate current (˜35 μA/cell) from a 5V supply. This result is obtained when biasing the device at the maximum gate current, i.e. at a control-gate voltage (V cg ) of 1.5V. The corresponding cell area is in the order of 15 μm 2 for a 0.7-μm embedded Flash memory technology when implemented in a contactless virtual ground array as described in pending application Ser. No. 08/426,685, incorporated herein by reference. In terms of the feature size F (i.e. the smallest dimension on chip for a given technology), this corresponds to ˜30F 2 for a 0.7-μm technology. This is fairly large as compared to the high density Flash memory concepts which are all in the ˜10F 2 range. However, due to the growing demand for higher densities, also in embedded memory applications like e.g. smart-cards and embedded microcontrollers, a continuous increase in array density and the scaling of the supply voltage become mandatory. This evolution calls for more aggressive cell-area scaling and for low-voltage and low-power operation. In the co-pending application Ser. No. 08/694,812, incorporated herein by reference, a programming scheme is described which reduces the power consumption during the write operation considerably. Also, the used write voltages are expected to scale with the supply voltage V supply since the Source-Side Injection mechanism only requires the floating-gate channel to stay in the linear regime for fast programming (see e.g. J. Van Houdt et al., IEEE Trans. Electron Devices, vol. ED-40, p.2255, 1993). Therefore, the necessary Program-Gate voltage V pg for fast programming is given by: V pg ≈( V supply +V th )/ p   (1) wherein V th is the intrinsic threshold voltage of the floating gate transistor (˜0.5V) and p is the coupling ratio from Program Gate to Floating Gate (typically ˜50%). According to Eq.(1), V pg is thus expected to scale twice as fast as the supply voltage in a first order calculation. It can be concluded that the high programming voltage is scaling very well with the supply voltage and offers enough margin in order for the high voltage circuitry to follow the minimum design rule. These and other features described in the related patents and patent applications indicate the high scalability of the HIMOS® concept in comparison with the traditional cells that use drain multiplication or tunnelling. However, there are some drawbacks in the HIMOS® cell concept. First, there is a drawback of the additional program gate, which increases the cell area considerably in the case of a double polysilicon technology. Furthermore, since both a control gate and a program gate are formed in the same polysilicon layer, the process requires special polysilicon etching recipes in order to remove the polysilicon stringers between the control gate and the program gate. Another drawback is related to the decoder design. Since the cell is erased with negative gate voltages on the control gate and program gate, as described in the pending application “Method of erasing a Flash EEPROM memory cell optimized for low power consumption”, U.S. Pat. No. 5,969,991 issued Oct. 19, 1999, a pMOS transfer gate is required in the row decoder. During read-out (a program gate voltage is set to zero) and during the write/read deselect operations (a control gate voltage is set to zero), a negative voltage is required to switch the ground potential onto the gates of the array. This in turn requires a small charge pump in the row decoder, which has a small but negative impact on the access time and power consumption. Further, there is a reliability problem associated with the program gate's disturb phenomenon. After a cell has been programmed, the high program gate's programming voltage (typically 9V in a 0.35 μm technology) can cause discharging of this cell while programming other cells on the same row. Alternatively, erased cells can be slowly programmed because of tunnelling through the tunnel oxide. Further, another problem is due to the appearance of Stress-Induced Leakage Current (“SILC”). When the cell has been written and erased for a large number of times, the tunnel oxide quality is deteriorated in such a way that the application of a small read-out voltage at the drain can cause slow discharging of programmed cells. Even though this is a very small leakage current, it has to be controlled for the entire lifetime of the device that is typically 10 years. There have been many attempts to obtain a smaller cell using 3 polysilicon layers, as described in a co-pending PCT patent application Ser. No. PCT/BE98/00134, WO 9913513, filed Sep. 9, 1998. Other references to such devices are: (1) U.S. Pat. No. 5,284,784, issued Feb. 8, 1994, to Martin H. Manley; (2) U.S. Pat. No. 5,091,882, issued Feb. 25, 1992, to K. Naruke; (3) U.S. Pat. No. 4,794,565, issued Dec. 27, 1988, to A. T. Wu et al. (4) U.S. Pat. No. 5,235,544, issued Aug. 10, 1993, to J. Caywood; (5) U.S. Pat. No. 5,338,952, issued Aug. 16, 1994, to Y. Yamauchi; (6) U.S. Pat. No. 5,280,446, issued Jan. 18, 1994, to Y. Y. Ma et al.; and (7) U.S. Pat. No. 5,394,360, issued Feb. 28, 1995, to T. Fukumoto. These references all suffer from a number of significant disadvantages that are discussed now in more detail. The first four referenced patents (Manley, Naruke, Wu and Caywood) all describe so-called “sidewall gate” devices (FIG. 1 ). In each of these devices, the floating gate is formed in the first polysilicon layer, while the select gate is formed by a polysilicon sidewall spacer. This spacer can be formed in the second polysilicon layer (Manley, FIG. 1 a ) or in the third one (Wu, Naruke, Caywood, FIG. 1 ). There are main disadvantages associated with these sidewall-gate devices. First of all, the sidewall select gate is formed by depositing a polysilicon layer on the chip which is then removed selectively by using anisotropic (dry) etching techniques. However, it is very difficult to control this selective etching operation. For example, the width of the spacer remaining after etching determines the effective channel length during programming and this parameter should be tightly controlled. Therefore, this technique is not to be considered as a standard process step for CMOS. Also, after this anisotropic etch, the remaining sidewall is not only present on the source side of the device, but it will be a ring around the first and eventually also the second polysilicon gate(s). To correct for this problem, an additional photo step is required. Further, since the select gate controls a short portion of the channel, it needs to switch off the transistor channel in some cases, e.g. when reading/writing a particular cell the select gates of the (erased) cells sharing the same bitline have to be able to reduce their channel current to zero in order to prevent leakage currents and/or unwanted programming in the array. Usually, the thickness of the polysilicon, which determines the width of the spacer, is smaller than the minimum feature size that compromises the hard-off situation which in turn is highly desired in a memory array. Further, the efficiency of the Source Side Injection mechanism is closely linked to the thickness of the oxide spacing in between the select and the floating gate (see e.g. J. Van Houdt et al., IEEE Transactions on Electron Devices, vol.39, no.5, May 1992). By putting the sidewall right next to the control gate (Wu, Naruke, Caywood), the oxide spacing has to remain fairly thick since it also has to isolate the high control gate voltage during programming from this sidewall gate. Therefore, the injection efficiency is compromized by isolation requirements. Also, since the part of the transistor channel which is controlled by the sidewall gate is much shorter than the part controlled by the floating gate, a larger portion of the external drain voltage will be lost for the channel hot-electron generation at the injection point. However, the main problem with these devices is the difficulty for contacting the cells in a large array of memory cells. The sidewall gate is also used for wiring, and this has a considerable negative impact on the parasitic resistance in a large memory array, as explained in U.S. Pat. No. 5,394,360, issued Feb. 28th, 1995, to T. Fukumoto (col.1, lines 37-41). The 5th reference (U.S. Pat. No. 5,338,952, issued Aug. 16th, 1994, to Y. Yamauchi) removes some of the problems mentioned above by forming the floating gate as a polysilicon sidewall spacer (FIG. 1 c ). However, some drawbacks of the sidewall-gate device are still present in this memory cell. First of all, the sidewall select gate is still formed by depositing a polysilicon layer on the chip that is then removed selectively by using anisotropic (dry) etching techniques. In this case, the width of the spacer remaining after etching determines the effective channel length during the read-out process, and this parameter should be tightly controlled. Further, if electrons are stored on the floating sidewall gate, the portion of the channel controlled by this sidewall has to be switched off efficiently, which is not evident. As already mentioned above, the thickness of the polysilicon that determines the width of the spacer is usually smaller than the minimum feature size, which compromises the hard-off situation that is highly desired in a memory array. Eventually, the cell may exhibit a soft-on and a hard-on state instead of hard-off/hard-on states as required for fast access. Furthermore, since erasing is now to be achieved from the sidewall towards a sufficiently underdiffused drain junction, the effective channel controlled by the spacer is even smaller. This makes the leakage problem during read-out even more critical. As in the previous cases, after the anisotropic etch, the remaining sidewall is not only present on the drain side of the device, but it will be a ring around the select gate. To correct for this, an additional photo step is required. Further, since the floating gate is a sidewall spacer, the coupling ratio between the control gate (3rd polysilicon) and this floating gate will be rather small. Indeed, referring to FIG. 1 in the Yamauchi application, it is clear that the couplings from the floating sidewall gate towards the control gate, substrate/drain and select gate are on the same order of magnitude. This implies that the high programming voltage is still 12V in a 0.5 μm CMOS technology (see the corresponding conference paper “A 5V-only virtual ground Flash cell with an auxiliary gate for high density and high speed applications”, by Y. Yamauchi et al., IEDM Tech. Dig., p.319, 1991). Consequently, the voltage difference between the control gate and the select (or auxiliary) gate exceeds 10V during programming which compromises the scaling of the 2nd interpoly layer (layer 12 in FIG. 1 of the discussed application). Thus, this dielectric layer will have to remain relatively thick (200 Å) according to the application (col.4, line 46). This will further decrease the coupling ratio between the control gate and the floating gate, since the oxide between the sidewall and the select gate has to scale because of its impact on the source-side injection efficiency (see above). The only solution is to increase the coupling ratio by adding coupling area (so-called wings) between the control gate and the floating gate. However, this solution compromises the major advantage of this cell, which is its high integration density. Additionally, the erase voltage is still very high (−11V according to the application), which makes the concept unsuited for embedded memory applications where these high negative voltages would introduce too high an additional processing cost. This high erase voltage is again a consequence of the fairly low coupling ratio towards the sidewall gate. Ma et al. (referenced patent 6) disclose an alternative memory cell with 3 polysilicon layers, which also uses the source-side injection mechanism (FIG. 1 d ). The major difference with the previously discussed prior art is the absence of a sidewall gate. Instead, first and second poly are etched in a stacked way and the select gate is added on top by a 3rd polysilicon layer. Some major disadvantages are given hereafter. First of all, it is well-known that such a processing scheme introduces considerable complexity which makes it impossible to use in an embedded memory application. On the other hand, the used erase voltage is still −12V provided that the bitline is biased at 5V. In future generations (when the supply voltage and hence also the bitline voltage go down), aggressive tunnel oxide scaling will be required in order not to have an increase of this negative voltage. Further, the oxide spacing between the select gate and the control gate has to be kept quite thick because this oxide also serves to isolate the high programming voltage from the select gate in order not to have a soft-erase effect or even oxide breakdown during programming. This restriction compromises scaling in general and, more in particularly, decreases the injection efficiency which is directly linked to the thickness of this spacing as explained extensively by J. Van Houdt et al. in IEEE Transactions on Electron Devices, vol.39, no.5, May 1992. U.S. Pat. No. 5,394,360, issued Feb. 28th, 1995, to T. Fukumoto, describes several embodiments of source-side injection cells. The embodiment disclosed in FIG. 2 of the above-mentioned patent suffers from the same disadvantages as the device described by Ma et al. (see above). The second embodiment (FIG. 4 in that patent and FIG. 2 in the present application) still suffers from problems. For example, the dielectric determining the injection efficiency that is used for the spacing between select gate and control gate also has to provide sufficient isolation between the high programming voltage (2nd polysilicon) and the (low) select gate voltage during programming (3rd polysilicon). When examining the numbers from this patent, the control gate will be pulsed to 14-15V and the select gate is biased at 1.5V during programming (col.2, lines 59-64). This implies that the second interpoly dielectric is subject to a stress of 12.5-13.5V. Obviously, this layer can not be made very thin and, hence, the injection efficiency will be compromised since the same layer is also serving as the spacing oxide between select gate and floating gate (see FIG. 2 ). A second problem with the Fukumoto cell is the following: the second polysilicon (control) gate should cover most of the floating gate in order to increase the coupling ratio and hence reduce the programming voltage. On the other hand, this overlap is limited due to design rules since the “offset region” (col.1, line 59) has to be covered uniquely by the third polysilicon gate for having a functional cell. In practice, this layout rule will be about ½ of the feature size due to misalignment considerations (see FIG. 2 ). Since the floating gate has to be scaled as much as possible to minimize capacitive coupling ratios towards all terminals other than the control gate, its length will be ˜F in an efficient cell design. This implies that only 50% of the floating gate area will actually contribute to the coupling ratio. The statement (col.3, lines 34-37) that “the second gate electrode is provided so as not to enter (overlap) the offset region and to be directly capacitively-coupled with the whole surface of the floating gate” is, therefore, a contradiction. Making sure that the second gate does not overlap the offset region implies that only part of the floating gate area contributes to the coupling ratio from control gate to floating gate and in turn explains why 14-15V is still typically used for programming the cell. In a pending application, “Non-volatile memory cell”, PCT patent application Ser. No. PCT/BE98/00134, WO 9913513, filed Sep. 9, 1998, a device architecture is claimed which circumvents the above-mentioned problems yielding a very compact though still CMOS-compatible geometry that paves the way to high-density and low-voltage memory applications. Although the above-mentioned application Ser. No. PCT/BE98/00134, WO 99/13513 solves the above-mentioned problems, it still requires 3 polysilicon layers which is much more complicated for the processing of the chip than a double polysilicon scheme. Other references to memory devices that are relevant with respect to the present invention are listed below: (1) U.S. Pat. No. 5,029,130, issued Jul. 2, 1991, listed inventor B. Yeh; (2) “An 18 Mb Serial Flash EEPROM for Solid-State Disk Applications”, by D. J. Lee et al., paper presented at the 1994 Symposium on VLSI Circuits, tech. digest p.59; (3) “A 5 Volt high density poly-poly erase Flash EPROM cell”. by R. Kazerounian, paper presented at the 1988 Intemational Electron Devices Meeting, tech. digest p.436; (4) U.S. Pat. No. 5,572,054, issued on Nov. 5, 1996, listed inventors Wang et al. These references all suffer from a variety of problems such as a high processing complexity and/or the need for high erase voltages. Yeh et al. show a split gate cell with a very complicated interpoly formation scheme which, again, makes this concept unsuited for embedded memory. The used erase voltage is still 15V although special processing features have been introduced specifically to enhance the interpoly conduction for efficient erasure. The papers by Lee and by Kazerounian show less details on processing issues, but it is clear from the disclosure that the erase voltages are in the order of 20V in order to tunnel through a polyoxide. Wang et al. (U.S. Pat. No. 5,572,054) describes an electrically programmable and erasable memory device which comprises at least one transistor. This transistor comprises a substrate which is provided with a source, a drain and a channel region extending between the source and the drain. The substrate has a split point situated between the source and the drain which forms a separation between a first region extending from the split point towards the drain and a second region extending from the split point towards the source. A first insulating layer is applied on the substrate and extends in the second region over a portion of the source and the channel region. A second insulating layer is applied on the substrate in the first region, where it separates the substrate from a control gate. The second insulating layer further extends in the second region where it contacts the control gate. A floating gate is sandwiched between the first and second insulating layers and extends over a portion of the source to be capacitively coupled to the source. This transistor structure is commonly known in the art as a “split gate” structure. There are n-channel and p-channel devices with split gate transistors. In the n-channel devices, the source and drain are doped with an n-type dopant and the substrate is doped with a p-type dopant. In p-channel devices, the source and drain are doped with a p-type dopant and the substrate is doped with an n-type dopant. The device described in U.S. Pat. No. 5,572,054 is an n-channel device. This implies that electrons flow through the channel region from the drain towards the source. In p-channel devices, the electrons flow from source to drain, which implies in p-channel split gate transistors the floating gate is located in the region extending from the split point towards the drain. The floating gate of the device described in U.S. Pat. No. 5,572,054 can be charged to obtain a programmed state and discharged to obtain a non-programmed or erased state of the memory cell. Programming the floating gate means that electrons are introduced onto the floating gate. Erasing means that electrons are removed from the floating gate. Assuming that the floating gate is in an erased state, i.e. positively charged, programming the transistor, i.e. charging the floating gate, is conducted as follows. A ground potential is applied to the drain, a low positive voltage (e.g. +1 V) is applied to the control gate and a high positive voltage (e.g. +12 V) is applied to the source. The high voltage difference between drain and source causes electrons to migrate through the channel from the drain towards the source, i.e. the channel region becomes conductive and is “turned on.” The positive voltage on the control gate serves to transfer the drain potential onto the split point. When the electrons reach the split point, they see a steep potential drop as the influence of the positive voltage on the control gate diminishes in this point. The steep potential drop is approximately equal to the source potential and causes them to be accelerated or “heated”. Due to the capacitive coupling with the source, the floating gate attracts the heated electrons, which causes some of them to be injected through the first insulating layer onto the floating gate. This process continues until the positive charges on the floating gate are neutralised by the electrons injected onto it and the floating gate is no longer positively charged, which results in the portion of the channel region beneath the floating gate being “turned off”, i.e. it is no longer conductive. This method of charging the floating gate is commonly known in the art as channel hot electron injection (CHEI). Assuming that the floating gate is in a programmed state, i.e. negatively charged, erasing the transistor, i.e. discharging the floating gate is conducted as follows. A ground potential is applied to the source and the drain, and a high positive voltage (e.g. +15 V) is applied to the control gate. The high potential of the control gate causes electrons on the floating gate to travel through the second insulating layer to the control gate by means of the Fowler-Nordheim tunneling mechanism, which is known to the person skilled in the art. The memory cell described in U.S. Pat. No. 5,572,054 however has the disadvantage that high voltages are needed for both programming and erasing the memory cell. Because of these high voltages, the first and second insulating layers need to have a substantial thickness in order to avoid breakdown. Furthermore, particular circuits, such as for example charge pumping circuits, are required to achieve the high programming and erasing voltages, since these voltages are above the supply voltage of the device, which is commonly about 5 volts. This can lead to an increase in the size of the memory device. AIMS OF THE INVENTION An aim of the invention is to develop a high density memory device having fast programming capabilities, using low voltages, being scalable and being easy to process. Another aim of the invention is to present an electrically programmable and erasable memory device in which the voltages used for programming and erasing are less than those used in the prior art. SUMMARY OF THE INVENTION The aim of the invention is achieved in that said first insulating layer and said overlap are dimensioned in such a way as to create a capacitive coupling between said floating gate and said drain enabling injection onto the floating gate of hot electrons generated by drain induced secondary impact ionisation. The mechanism used in the device of the invention for programming the transistor, drain induced secondary impact ionisation, can be explained as follows. A voltage difference is applied over the channel region in such a way that hot electrons flow from source to drain. As these hot electrons impact on the drain, they transfer a certain amount of their energy onto the drain. As a result, the drain is ionised, meaning that electrons come loose from the drain. These so-called “secondary electrons” are heated as they receive energy from the electrons impacting on the drain. Due to the capacitive coupling of the floating gate with the drain, by which part of the voltage on the drain is induced on the floating gate, the secondary electrons are attracted by the floating gate. Some of them have sufficient energy to diffuse through the first insulating layer and be injected onto the floating gate. The mechanism of drain induced secondary impact ionisation allows the programming and erasing of the transistor at more moderate voltages with respect to the prior art. In a preferred embodiment of the device of the invention, the substrate is negatively biased with respect to the source during programming of the transistor. Biasing the substrate negatively with respect to the source has the advantage that the electric field which is present over the first insulating layer and is caused by the voltage difference between the floating gate and the substrate, can be enhanced. An enhancement in this electric field causes the secondary electrons to be more attracted to the floating gate. As a result, biasing the substrate negatively with respect to the source can lead to an enhancement of the programming speed. In a further preferred embodiment of the device of the invention, a drain junction is provided between the drain and the substrate, which drain junction has a depth larger than the overlap between the floating gate and the drain. This deep drain junction is preferably provided with a halo extension. By providing such a drain junction, the mechanism of drain induced secondary impact ionisation can be enhanced, resulting in a further enhancement of the programming speed. The capacitive coupling between the floating gate and the drain is preferably constructed such that it enables tunnelling, preferably Fowler-Nordheim tunnelling, of electrons from said floating gate to said drain for erasing the transistor. In order to enable tunnelling of electrons from the floating gate and a target, a capacitive coupling between the floating gate and the target is required. This capacitive coupling is preferably between predetermined values. A capacitive coupling of too low value is undesirable for tunnelling, because this implies that there is either substantially no overlap between the floating gate and the target, or that the insulating layer between the floating gate and the target is too thick to enable tunnelling at a moderate voltage. A capacitive coupling of too high value is also undesirable for tunnelling, because a high capacitive coupling results in a large part of the voltage applied to the target being induced on the floating gate, so that at a moderate voltage, the voltage difference between the target and the floating gate remains too low to achieve tunnelling. Programming the transistor of the device in one embodiment of the invention comprises the steps of applying a source voltage to the source, applying a control gate voltage to the control gate and applying a drain voltage to the drain. The drain voltage has a higher voltage value than the control gate voltage, which in its turn has a higher voltage value than the source voltage. As the control gate voltage is below the drain voltage, the device of the invention allows the use of more moderate voltages for programming with respect to the prior art. Erasing the transistor of the device in one embodiment of the invention comprises the steps of applying a source voltage to the source, applying a control gate voltage to the control gate and applying a drain voltage to the drain. The drain voltage has a higher voltage value than the control gate voltage and the source voltage, which are preferably supplied with the ground potential. As a result of the suitable capacitive coupling between the floating gate and the drain as described above, the device of the invention allows the use of more moderate voltages for erasing with respect to the prior art. Reading the transistor of the device of the invention comprises the steps of applying a source voltage to the source, applying a control gate voltage to the control gate and applying a drain voltage to the drain. The control gate voltage has a higher voltage value than the source voltage, which in its turn has a higher voltage value than the drain voltage. This method of reading the transistor can be termed “reverse read-out,” because the third source voltage is higher than the drain voltage, which is preferably the ground potential. The reverse read-out has the advantage that a low voltage, preferably the ground potential, is applied to the drain during reading, which serves to avoid a leakage current from the floating gate to the drain. These and other advantages of the invention will be more apparent to one of the ordinary skill in the art after reading the detailed description section with references to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a cross-sectional view of prior art devices, with FIGS. 1 a and 1 b showing typical sidewall-gate structures, FIG. 1 c showing a prior art sidewall-gate structure where the sidewall serves as the floating gate and FIG. 1 d showing a prior art split-gate structure employing three polysilicon layer; FIG. 2 shows a cross-section of a prior art memory cell having conflicting requirement of the second interpoly dielectric layer; FIG. 3 shows a cross-sectional side view of a preferred embodiment of a transistor of a device according to an exemplary embodiment; FIG. 4 shows a graph representing the influence of negatively biasing the substrate on the floating gate current in the device according to an exemplary embodiment; FIG. 5 shows a flow chart illustrating a processing method for creating a device according to an exemplary embodiment; FIG. 6 shows a flow chart illustrating a method for programming a device according to an exemplary embodiment; FIG. 7 shows a flow chart illustrating a method for erasing a device according to an exemplary embodiment; FIG. 8 shows a flow chart illustrating a method for reading a device according to an exemplary embodiment of the present invention; and FIG. 9 shows a suitable array configuration for the device according to an exemplary embodiment. DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS Referring to the drawings, FIG. 3 is a block diagram illustrating a device arranged to employ exemplary embodiments of the present invention. As shown in FIG. 3, the device comprises a transistor 1 having a substrate 2 provided with a drain 3 , a source 4 , and a channel region 5 extending between the source 4 and the drain 3 . The substrate 2 has a split point 6 between the source 4 and the drain 3 . The split point 6 forms a separation between a first region 7 extending from the split point 6 in a first direction towards the source 4 and a second region 8 extending from the split point 6 in a second direction towards the drain 3 . A first insulating layer 9 is applied on the substrate 2 and extends in the second region 8 over at least a portion of the drain 3 and at least a portion of the channel region 5 . A second insulating layer 10 is applied on the substrate 2 in the first region 7 , where it separates the substrate 2 from a control gate 11 . The second insulating layer 10 extends further in the second region 8 , where it contacts the control gate 11 . Further, the device has a floating gate 12 positioned between the first insulating layer 9 and the second insulating layer 10 . The floating gate 12 extends in the second region 8 over the channel region 5 and over at least a portion of the drain 3 to establish an overlap 13 between the floating gate 12 and the drain 3 . The first insulating layer 9 and the overlap 13 are positioned in such a way that a capacitive coupling is created between the floating gate 12 and the drain 3 . This capacitive coupling enables the injection of hot electrons onto the floating gate 3 . According to the exemplary embodiment, the hot electrons are generated by a drain induced secondary impact ionization. In the device according to an exemplary embodiment, the first insulating layer 9 as well as the overlap 13 between the floating gate 12 and the drain 3 are arranged in such a way that a capacitive coupling is created between the floating gate 12 and the drain 3 . Thus, the injection of hot electrons onto the floating gate 3 is possible, where the hot electrons are generated by a drain induced secondary impact ionization. Primary electrons, i.e. hot electrons migrating through the channel region 5 from source 4 to drain 3 , require less energy for impact ionizing the drain 3 than they require for being injected onto the floating gate 12 . The reason is that the injection onto the floating gate 12 requires a lot of energy to be able to cross the first insulating layer 9 . As a result, a lower voltage difference between drain 3 and source 4 is required for heating the primary electrons when they are used for impact ionization of the drain 3 instead of injection onto the floating gate 12 . Therefore, only a moderate voltage needs to be supplied to the drain 3 for heating the primary electrons. Further, a thinner first insulating layer 9 is possible, as the voltage difference between the drain 3 and the floating gate 12 will never be as large as when the primary electrons are used for injection onto the floating gate 12 . Further, the first insulating layer 9 can be constructed thinner as there is a lower risk of breakdown. Since the first insulating layer 9 can be constructed thinner, the amount of energy required for injection of hot electrons onto the floating gate 12 is reduced. This in turn allows the use of secondary electrons for charging the floating gate 12 in the device according to the exemplary embodiment. Therefore, the device has an advantage that the voltage applied to the drain 3 for programming the transistor can be reduced, less than the voltage necessary for application to the source of prior art devices such as the device of U.S. Pat. No. 5,572,054. By providing the split point 6 , electrons migrating through the channel region 5 can become sufficiently heated by a steep potential drop and may ionize the drain 3 . This shows that a lower voltage with respect to the source 4 can be applied to the drain 3 . This has the advantage that the voltage difference over the channel region 2 can be reduced, less than is required in prior art devices such as the device of U.S. Pat. No. 5,572,054. Further, according to an exemplary embodiment, the capacitive coupling between the floating gate 12 and the drain 3 results in a part of the drain voltage being induced on the floating gate 12 , enabling the floating gate 12 to attract the secondary electrons. As a result, the control gate voltage is no longer used for attracting the secondary electrons towards the floating gate 12 . According to an exemplary embodiment, the control gate 11 is only used for biasing the channel region 5 in the first region 7 extending from the split point 6 towards the source 4 , in such a way that the source voltage is transferred onto the split point 6 . The control gate 11 in the first region 7 is only separated from the substrate 2 by the second insulating layer 10 , and not also by the first insulating layer 9 and the floating gate 12 as in the stacked gate transistor. Thus, the control gate 11 is nearer the substrate 2 in the first region 7 . Further, providing the capacitive coupling has the advantage that the control gate voltage required for programming the transistor 1 can be reduced as compared to prior art devices such as the device in U.S. Pat. No. 5,659,504. Furthermore, the voltage required on the control gate 11 for programming the transistor in the device according to the exemplary embodiment can be below the voltage applied to the drain 3 . The device according to the exemplary embodiment can be operated at low voltages than prior art devices and thus consumes less power. Moreover, the device of the current invention is smaller in size, is more scalable and requires less charge pumping circuitry. Furthermore, in the device of the current invention, the use of a program gate for triggering the floating gate is unnecessary, since the floating gate is capacitively coupled to the drain. Such a program gate is, for example, required in prior art devices using Source Side Injection at moderate voltages. The omission of the program gate enables the construction of a smaller memory device as compared to such Source Side Injection based devices. The transistor size in the device of the invention can be less than 1 μm 2 in a 0.25 μm CMOS technology. The capacitive coupling ratio of the floating gate 12 with respect to the drain 3 is preferably between 0.2 and 0.5. This means that preferably 20 to 50% of the voltage applied to the drain is induced on the floating gate. However, the coupling ratio between the floating gate and the drain can also be any other value deemed suitable by the person skilled in the art. The substrate 2 is preferably negatively biased with respect to the source 4 during programming of the transistor 1 . The effect of negatively biasing the substrate 2 is that the electric field which is created over the first insulating layer 9 , i.e. between the floating gate 12 and the substrate 2 , is enhanced. This results in the secondary electrons being more strongly attracted by the floating gate 12 , so that more secondary electrons are injected onto the floating gate 12 in a given period. Therefore, by negatively biasing the substrate 2 with respect to the source 4 , the programming speed of the device according to the invention can be enhanced. The enhancement in the programming speed is illustrated in FIG. 4, which represents the floating gate current I fg for charging the floating gate as a function of the floating gate voltage V fg (with the source being connected to the ground potential) for a zero substrate bias V b and a negative substrate bias V b of −2.5 V, and for a device produced in a 0.25 μm CMOS technology. When grounding the substrate 2 , only a very small floating gate current I fg is detected because of the poor injection efficiency of the conventional drain hot-electron injection mechanism. However, when a small negative voltage is applied to the substrate (e.g −2.5V), the floating gate current I fg is increased by several orders of magnitude due to secondary electron injection effects originating from a larger silicon electric field in the drain region. This experiment evidences the appearance of an injection mechanism in the memory device according to the exemplary embodiment of the present invention, and it can be used for fast programming at low voltages. As the memory device of the invention preferably comprises a plurality of transistors arranged in parallel columns and rows, the substrate 2 is preferably locally adapted for ensuring electrical isolation of each transistor for which the substrate is negatively biased with respect to the source 4 , from the rest of the substrate. In this way, it can be ensured that transistors which do not have to be programmed, i.e. for which the substrate is not to be negatively biased with respect to the source, are unintentionally programmed. The device shown in FIG. 3 is preferably provided with a drain junction 14 having a depth D which is optimised for having a highly efficient drain induced secondary impact ionisation. The optimised depth can be achieved by making the drain junction depth D larger than the overlap 13 between the floating gate 12 and the drain 3 . The drain junction depth D is preferably between one to four times the overlap 13 , or larger. The drain junction 14 is further preferably provided with a halo extension 16 that further increases the secondary electron injection efficiency. The large drain junction depth D is possible in the device since, according to an exemplary embodiment, the electric field between the drain and the source does not need to be very strong. The device according to an exemplary embodiment shows a programming efficiency which is at least as similar to prior art devices, but at much lower voltages. As previously mentioned, this is achieved by employing the drain induced secondary impact ionisation mechanism, requiring a drain voltage that is less than the supply voltage to the device (e.g., keeping the drain voltage less than a supply voltage of 5 Volts). The low drain voltage allows the use of a thin first insulating layer 9 under the floating gate 12 since drain disturb conditions are largely relaxed. This in turn enables the erase of the floating gate 12 towards the drain 3 by means of tunnelling of electrons through the first insulating layer 9 instead of erasing the floating gate towards the control gate by means of tunnelling of electrons through the second insulating layer 10 . As a result, only low voltages are to be applied to the control gate 11 , both during programming and erasing of the transistor 1 . Consequently, the second insulating layer 10 under the control gate 11 can be scaled in relation to the corresponding CMOS generation, i.e. can be constructed thinner with respect to existing devices, and there is is a lower risk of breakdown of the second insulating layer 10 resulting from a high voltage on the control gate 11 . A second reason why the second insulating layer 10 is very thick in prior art devices, for example split gate devices, is the need for a very large drain coupling to enable injection of primary hot electrons onto the floating gate. As the sum of the respective coupling ratios between the floating gate and the respective components of the transistor surrounding the floating gate equals 1 (by definition), this implies that the coupling ratio between the floating gate 12 and the control gate 11 should be minimized. According to an exemplary embodiment, the control gate coupling is allowed to be larger because a drain coupling on the order of 20% to 50% is sufficient to induce enough voltage on the floating gate to enable the injection of secondary electrons onto the floating gate, which allows a thinner second insulating layer 10 . According to an exemplary embodiment, the first insulating layer 9 preferably has a thickness of at most 50 angstroms (5 nm). The second insulating layer 10 in the first region 7 preferably has a thickness of at most 50 angstroms (5 nm), preferably 35 angstroms (3.5 nm). The second insulating layer 10 in the second region 8 preferably has a thickness of at most 150 angstroms (15 nm), preferably 130 angstroms (13 nm). However, the first and second insulating layers can also have any thickness deemed suitable by the person skilled in the art, and the first and second insulating layer can have the same or different dielectric constants. It should be noted that the device of the invention is a p-channel device, which means that the drain and the source are switched with respect to the device described in U.S. Pat. No. 5,572,054 (Wang et al.). The mechanism of drain induced secondary impact ionisation is known as such from U.S. Pat. No. 5,659,504. However, the transistor with which the mechanism of drain induced secondary impact ionisation is used in U.S. Pat. No. 5,659,504 has a different structure than the transistor in the device of the current invention. The transistor in the device described in U.S. Pat. No. 5,659,504 has a so-called “stacked gate” structure. This means that the floating gate and the control gate are stacked above each other, the floating gate being separated from the substrate by a first insulating layer and the control gate being separated from the floating gate by a second insulating layer. The floating gate and the control gate have substantially the same length and extend over the channel region between source and drain. A first main difference with the stacked gate structure is the absence of the split point. A second main difference is that the floating gate does not extend over a substantial portion of the drain, which means that the floating gate is substantially not capacitively coupled to the drain. In the device of U.S. Pat. No. 5,659,504, the electrons migrating through the channel region from source to drain are heated by means of the voltage difference between the drain and the source. This voltage difference has to be large enough to heat the electrons sufficiently and enable them to impact ionise on the drain. There is no indication in U.S. Pat. No. 5,659,504 that a steep potential drop as the result of a split point can be used for sufficiently heating the electrons. Furthermore, in the device of U.S. Pat. No. 5,659,504, the floating gate is substantially not capacitively coupled to the drain, so that substantially no part of the drain voltage is induced on the floating gate. This means that substantially no injection of secondary electrons onto the floating gate can be achieved as the result of a capacitive coupling of the floating gate with the drain. The injection of secondary electrons is achieved by applying a voltage to the control gate which is such that it established an electric field attracting the secondary electrons towards the floating gate. There is no teaching or suggestion in U.S. Pat. No. 5,659,504 that injection of secondary electrons onto the floating gate can be induced by capacitively coupling the floating gate to the drain. Hence, there is no indication in U.S. Pat. No. 5,659,504 that the mechanism of drain induced secondary impact ionisation can be applied for programming a split gate transistor. In the device of U.S. Pat. No. 5,572,054 the electrons which are injected onto the floating gate are electrons which migrate through the channel region and become heated when they see the steep potential drop as a result of the split point. These electrons could be termed “primary electrons,” as they are directly injected from the channel region onto the floating gate. These primary electrons are not generated on the source (or the drain) by means of impact ionisation, which means that they are not secondary electrons. There is no teaching or suggestion in U.S. Pat. No. 5,572,054 that secondary electrons generated by impact ionisation of the source (or the drain) could be injected onto the floating gate of a split gate transistor. Furthermore, there is no teaching or suggestion in U.S. Pat. No. 5,572,054 that primary electrons can be used to generate secondary electrons on the source (or the drain) by means of impact ionisation. Hence, there is no indication in U.S. Pat. No. 5,572,054 that a split gate transistor can be programmed by using the mechanism of drain induced secondary impact ionisation. It can be concluded that the device of the invention cannot be achieved by simply combining the split gate structure of U.S. Pat. No. 5,572,054 with the programming mechanism of U.S. Pat. No. 5,659,504. FIG. 5 is a flow chart illustrating an exemplary processing method 50 for creating the device shown in FIG. 3 . Referring to FIG. 5, at step 52 , a thin oxide is grown on substrate 2 in a second region (e.g. the second region 8 ) to form a first insulating layer (e.g. the first insulating layer 9 ). According to an exemplary embodiment, the first insulating layer is 70 Å for a 0.35 μm CMOS technology. Next, at step 54 , a first polysilicon layer is deposited and etched to form a floating gate such as the floating gates 12 of the transistors 1 as shown in FIG. 3 . At step 56 , a junction 14 is formed. In one embodiment, the junction 14 is self-aligned with the floating gate 12 on a drain side. Further, the junction 14 can be formed by a deep n + implantation (preferably combined Phosphorous/Arsenicum junction with a halo). Simultaneously, a source junction, such as source junction 4 , is formed in a non-self-aligned manner. Alternatively, it could be formed together with the CMOS junctions (after performing the 2nd polysilicon definition). At step 58 , a thin oxide (comparable to the CMOS gate oxide of the corresponding generation, i.e. 55 Å for 0.25 μm CMOS etc.) is grown on the complementary part of the substrate 2 , i.e. in the first region 7 . Simultaneously, a second insulating layer, such as second insulating layer 10 is formed. According to an exemplary embodiment, the second insulating layer is formed by placing a thin polyoxide on a top and a sidewall of the floating gate 12 . Depending on the oxidation conditions and the doping level of the floating gate 12 , this interpoly oxide can be very thin. At step 60 , a control gate such as the control gate 11 is formed. According to an exemplary embodiment, the control gate 11 is formed by depositing and etching a second polysilicon layer. At this point, the junctions of the CMOS process are formed, and, eventually, they may be combined with the source junctions of the transistors. The method 50 shows only an exemplary method for creating the device shown in FIG. 3, and the device could also be produced in any other way known to a person skilled in the art. FIG. 6 is a flow chart illustrating a method 70 for programming the device shown in FIG. 3, according to an exemplary embodiment. Referring to FIG. 6, at step 72 , a first source voltage V s1 is applied to the source 4 . At step 74 , a first control gate voltage V cg1 is applied to the control gate 11 . At step 76 , a first drain voltage V d1 is applied to the drain 3 . At step 78 , the substrate 2 is negatively biased. According to an exemplary embodiment, the first control gate voltage V cg1 is higher than the first source voltage V s1 . The first control gate voltage's value is chosen in such a way above the first source voltage V s1 so the first source voltage V s1 is transferred onto the split point 6 . For example, the first control gate voltage could be set to a voltage between 1.8 V and 2.5 V higher than the first source voltage V s1 . Moreover, the first drain voltage V d1 has a higher voltage than the first control gate V cg1 , which in turn has a higher voltage than the first source V s1 . The first source voltage V s1 is preferably the ground potential. The first drain voltage V d1 is preferably below the supply voltage to the device of for example 5 V. The voltage difference between the first drain voltage V d1 and the first source voltage Vs 1 is above the threshold voltage V t for turning on the channel region 5 . The first control gate voltage V cg1 is in such a way above the first source voltage V s1 that the first source voltage V s1 is transferred onto the split point 6 . The first drain voltage V d1 is further chosen such that a high enough voltage is induced on the floating gate 12 , as a result of the capacitive coupling with the drain 3 , that injection of secondary electrons, which are generated by impact ionisation on the drain, is enabled. Further, according to an exemplary embodiment, the substrate 2 is negatively biased by applying to the substrate a substrate voltage V b , which preferably is a negative voltage with respect to the first source voltage V s1 . The substrate voltage V b serves to increase the electric field over the first insulating layer 9 , so that the injection of secondary electrons onto the floating gate 12 can be enhanced. In a preferred embodiment, typical programming voltages for the device of the invention in a 0.18 μm technology are: a first source voltage V s1 of 0 V (the source is grounded), a first control gate voltage V cg1 of around 2V and a first drain voltage V d1 of 4-5V which can be supplied from a small charge pumping circuit. A small negative substrate voltage V b of about −2V or less is preferably applied to the substrate. This brings the floating gate 12 to a potential of about 3V which is sufficient to efficiently trigger the drain enhanced secondary impact ionisation mechanism. In the device of the invention, tunnelling of electrons from the floating gate to the drain is enabled, because of a suitable capacitive coupling between the floating gate and the drain (e.g. 20 to 50%). The suitable capacitive coupling results from the use of drain induced secondary impact ionisation as a mechanism for programming. Because of the lower drain voltage with respect to the prior art, the first insulating layer between the floating gate and the drain can be constructed thinner. Because of the thinner first insulating layer, a smaller part of the drain voltage has to be induced on the floating gate to enable injection of secondary electrons through the first insulating layer. This means that the capacitive coupling between the floating gate and the drain can have a lower value than in the device of U.S. Pat. No. 5,572,054. In the latter device, the floating gate has to be induced to a higher voltage value, due to use of channel hot (primary) electron injection as mechanism for programming the floating gate. This is because a high source voltage is required to sufficiently heat the primary electrons, which in turn results in the requirement of a thicker first insulating layer between the floating gate and the source in order to prevent breakdown, which in turn leads to the primary electrons needing a higher amount of energy to cross the first insulating layer, so that the floating gate is to be induced to a higher voltage value. The presence of a suitable capacitive coupling between the floating gate and the drain in the device of the invention also leads to a lower voltage (e.g. about 8 V) being required on the drain for erasing the floating gate, with respect to the voltages needed on the control gate in the prior art. FIG. 7 is a flow chart illustrating a method 80 for erasing the device shown in FIG. 3 . Referring to FIG. 7, at step 82 , a second source voltage V S2 is applied to the source 4 . At step 84 , a second control gate voltage V cg2 is applied to the control gate 11 . At step 86 , a second drain voltage V d2 is applied to the drain 3 . At step 88 , a small negative voltage is applied to the substrate 2 to further increase the tunnelling field at the floating-gate-to-drain overlap 13 . In a preferred embodiment, the second drain voltage V d2 has a higher voltage value than the second source voltage V s2 and the second control gate voltage V cg2 . The second drain voltage V d2 is preferably above the supply voltage and second source voltage V s2 and the second control gate voltage V cg2 are preferably below the supply voltage applied to the device. The second source and control gate voltages V s2 and V cg2 are preferably the ground potential. The second drain voltage V d2 is chosen in such a way above the second control gate voltage V cg2 that electrons on the floating gate 12 are transferred to the drain 3 by means of tunnelling, preferably Fowler-Nordheim tunnelling, through the first insulating layer 9 . During erase, the control gate 11 is preferably grounded while the second drain voltage V d2 is preferably about 8V. A small negative voltage could be applied to the substrate 2 to further increase the tunneling field at the floating-gate-to-drain overlap 13 . The apparatus and method for erasing is in contrast to what is taught in the prior art. In the prior art, erasing the floating gate is achieved by Fowler-Nordheim tunnelling from the floating gate to the control gate. In the device of U.S. Pat. No. 5,572,054, tunnelling from the floating gate to the source is not possible at a moderate voltage, because the capacitive coupling between the floating gate and the source is too high (80%). In the device of U.S. Pat. No. 5,659,504, tunnelling from the floating gate to the drain is not possible at a moderate voltage, because there is substantially no overlap between the floating gate and the drain. In both prior art devices, the capacitive coupling between the floating gate and the control gate is more desirable for tunnelling than the capacitive coupling between the floating gate and the source or the drain. As a result, in both prior art devices the floating gate is erased by means of tunnelling of electrons from the floating gate to the control gate. It should be noted that in both cases the voltage applied to the control gate for erasing the floating gate is still high (15 V in U.S. Pat. No. 5,572,054; 12 to 20 V in U.S. Pat. No. 5,659,504) with respect to the supply voltage (e.g. 5 V). FIG. 8 is a flow chart illustrating a method 90 for reading the device shown in FIG. 3 . Referring to FIG. 8, at step 92 , a third drain voltage V d3 is applied to the drain 3 . At step 94 , a third source voltage V s3 is applied to the source 4 . At step 96 , a third control gate voltage V cg3 is applied to the control gate 11 . According to an exemplary embodiment, the third control gate voltage V cg3 has a higher voltage value than the third source voltage V s3 , which in turn has a higher voltage value than the third drain voltage V d3 . The third control gate voltage V cg3 is preferably below the supply voltage to the device and the third drain voltage V d3 is preferably at the ground potential. As already mentioned above, this method of reading the transistor can be termed “reverse read-out”, as the voltage for reading is applied to the source 4 instead of to the drain 3 . The “reverse read-out” method has an advantage that the leakage current from floating gate 12 to drain 3 is suppressed, and the reliability of the device is enhanced. The “reverse read-out” is in contrast to the prior art, because for example in the device of U.S. Pat. No. 5,572,054, the higher voltage for reading is applied on the floating gate side of the transistor, i.e. also on the source, but as already mentioned, the drain and source are switched in the prior art device with respect to the device of the invention. Further, due to the possibility of using the thin insulating layers 9 , 10 under control gate 11 and floating gate 12 , the device has also a high read-out current. This further implies that the programmed state is a ‘hard-off’ state since the subthreshold slope of the transistor has a steepness comparable to the CMOS devices in the same technology. For read-out, a source voltage V s3 being 1 V higher than the (grounded) drain voltage V d3 can be used. A read-out control gate voltage V cg3 in between 1.8 and 2.5 higher than the (grounded) drain voltage V d3 can be exploited. The substrate 2 is preferably also grounded. The possible voltages for programming, erasing and reading a transistor in the device shown in FIG. 3 are summarized in a Table 1 shown below. TABLE 1 V s (V) V d (V) V cg (V) V b (V) Program 0 4-5 1.8-4 ˜−2 Read-out 1 0 1.8-2.5 0 Erase 0 8 0 0 FIG. 9 shows an efficient array organisation for the memory device of the invention when fabricating memory circuits. First, it is noted that the sources 4 of the transistors on a column are to be connected to the vertical bitline, while the drains 3 of the cells on a row are connected to a common horizontal erase line. Advantages of this configuration are that the cell is read-out in the reverse way, which suppresses the Stress-induced Leakage Current in the drain-to-floating gate overlap region. Additionally, the absence of drain coupling during read-out further reduces the amount of electrons to be transferred onto the floating gate 12 for a given external threshold voltage V t , and, thus also the electric field over the first insulating layer 9 under charge storage (or retention) conditions. Secondly, the high erase voltage is only applied to one particular row of cells (or, eventually to a number of adjacent rows) which are to be erased simultaneously as a sector. This ensures that the erase voltage V d2 does not disturb the other sectors of the memory (no erase disturb mechanism and thus no need for inhibit voltages). Thirdly, the moderate drain voltage V d1 applied during programming will not cause significant charge loss in unselected transistors since the disturb time is limited by the number of words on a row. Since the drain 3 is connected to a common erase line along a row of cells, the non-selected cells have to be inhibited during programming, i.e. prevented from being programmed unintentionally. This can easily be done as follows: (1) all bitlines are biased at the supply voltage or a slightly larger inhibit voltage (e.g. 2.5 V in a 0.18 μm technology); (2) a row of cells is selected by applying about 1.8V to its wordline and 4-5V to its erase line. Under these conditions, the transistor is not drawing any current since the control-gate channel, i.e. the channel region 2 in the first region 7 under the control gate 11 , is cut off; (3) the bitlines of the transistors to be programmed are discharged selectively to ground which causes a current to flow only through these cells. A consequence of this configuration is that the bitline cannot be shared between adjacent columns of transistors. However, it is possible to share the bitline contact between 2 adjacent transistors on the same column in order to reduce the transistor area. For the drain contact (contacting the transistor to the erase line), the situation is somewhat more complicated. If the drain contact is shared between adjacent transistors on the same column, the impact of the drain disturb mechanism during programming is more than doubled because of the absence of a wordline voltage on the adjacent row, which further enhances the tunnelling field across the first insulating layer 9 . In practice, this problem requires a compromise between sector size, first insulating layer thickness and drain voltage during programming. Sharing the drain contact between transistors on the same row, or, alternatively, using a diffusion region for erase line routing are other solutions that remove the disturb problem. In view of the wide variety of embodiments to which the principles of the invention can be applied, it should be understood that the illustrated embodiment is an exemplary embodiment, and should not be taken as limiting the scope of the invention. For example, one of ordinary skill in the art will readily appreciate that various elements of the present invention can be practiced with software, hardware, or a combination of thereof. The claims should thus not be read as limited to the described order or elements unless stated to that effect. Therefore, all embodiments that come within the scope and spirit of the following claims and equivalent thereto are claimed as the invention.

Apparatus for an electrically programmable and erasable memory device and methods for programming, erasing and reading the device. The device has a single transistor including a source, a drain, a control gate and a floating gate positioned between the control gate, the source and the drain, where the floating gate is capacitively coupled to the drain. At least one part of the floating gate is partly positioned between the control gate, the drain and the source, and the other part of the floating gate overlaps with the drain. Further, the single transistor of the device includes means for injecting hot electrons generated by the drain induced secondary impact ionization onto the floating gate. Additionally, the means are arranged to induce Fowler-Nordheim tunnelling of charges from the floating gate to the drain.