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Pacifico_Yokohama | Pacifico Yokohama , officially known as , is a convention and exhibition center in Nishi-ku , Yokohama , Kanagawa , Japan . The center located in the western tip of waterfront Minato Mirai 21 district is one of the largest MICE venues in the nation . The Conference Center and Yokohama Grand InterContinental Hotel were completed first on July 29 , 1991 with the Exhibition Hall subsequently completed on October 12 . On April 25 , 1994 , National Convention Hall of Yokohama was completed . In 2001 it was designated the main press centre for the 2002 FIFA World Cup and the Exhibition Hall was expanded . The word `` Pacifico '' which stands for `` Pacific '' is derived from the Latin `` pacificus '' ( `` peace '' in English ) , primarily meaning `` peaceful '' or `` quiet '' . Pacifico Yokohama is also used as a music venue . |
Parti_Québécois | The Parti Québécois ( French , and sometimes English : Parti québécois , PQ ; -LSB- paʁ.ti ke.be.kwa -RSB- ) is a sovereignist provincial political party in Quebec in Canada . The PQ advocates national sovereignty for Quebec involving independence of the province of Quebec from Canada and establishing a sovereign state . The PQ has promoted the possibility of maintaining a loose political and economic sovereignty-association between Quebec and Canada . The party traditionally has support from the labour movement , but unlike most other social-democratic parties , its ties with the labour movement are informal . Members and supporters of the PQ are called `` péquistes '' ( Quebec French pronunciation : -LSB- pekɪst -RSB- ;) , a French word derived from the pronunciation of the party 's initials . The party is an associate member of COPPPAL . The party has strong informal ties to the Bloc Québécois ( BQ , whose members are known as `` Bloquistes '' ) , the federal party that advocates for the secession of Quebec from Canada and its independence , but the two are not linked organizationally . As with its federal counterpart , the Parti Québécois has been supported by a wide range of voters in Quebec , from large sections of organized labour to more conservative rural voters . |
Paleoarchean | The Paleoarchean ( -LSB- pronˌpeɪlɪ.oʊ.ɑrˈkiːən -RSB- also spelled Palaeoarchaean ( formerly known as early Archean ) ) is a geologic era within the Archaean Eon . It spans the period of time -- the era is defined chronometrically and not is referenced to a specific level in a rock section on Earth . The name derives from Greek `` Palaios '' ancient . The oldest ascertained life form of fossilized bacteria in microbial mats , old , found in Western Australia , is from this era . The first supercontinent Vaalbara formed during this period . During this era , a large asteroid , about 37 to wide , collided with the Earth in the area of South Africa about 3.26 billion years ago , creating the features known as the Barberton greenstone belt . |
Past_sea_level | Global or eustatic sea level has fluctuated significantly over the Earth 's history . The main factors affecting sea level are the amount and volume of available water and the shape and volume of the ocean basins . The primary influences on water volume are the temperature of the seawater , which affects density , and the amounts of water retained in other reservoirs like rivers , aquifers , lakes , glaciers , polar ice caps and sea ice . Over geological timescales , changes in the shape of the oceanic basins and in land/sea distribution affect sea level . In addition to eustatic changes , local changes in sea level are caused by tectonic uplift and subsidence . Over geologic time sea level has fluctuated by hundreds of meters . Today 's interglacial level is near historic highs and is 130 meters above the low level reached during the Last Glacial Maximum 19,000 -- 20,000 years ago . Observational and modeling studies of mass loss from glaciers and ice caps indicate a contribution to sea-level rise of 0.2 to 0.4 mm/yr averaged over the 20th century . Over this last million years , whereas it was higher most of the time before then , sea level was lower than today . |
Panda_Bear_(musician) | Noah Benjamin Lennox ( born July 17 , 1978 ) , also known by his moniker Panda Bear , is an American musician , songwriter , and co-founding member of the experimental pop band Animal Collective . In addition to his work with that group , Lennox has released five solo LPs since 1999 . His third , Person Pitch ( 2007 ) , is noted for influencing a wide range of subsequent indie music in addition to inspiring the chillwave genre and numerous soundalike acts . Lennox was primarily raised in Baltimore , Maryland , where he sang tenor in his high school chamber choir , and studied piano and cello . The name `` Panda Bear '' derived from his habit of drawing pandas on his early mixtapes as a teenager . He is currently based in Lisbon , Portugal . |
Pacific_Century | The Pacific Century ( and the associated term Asia-Pacific Century ) is a term that has been used to describe the 21st century through analogy with the term American Century . The implicit assumption underlying the usage of the term is that the 21st century will be dominated , especially economically , by the states in the Asia-Pacific region , in particular China , Japan , India , South Korea , Taiwan , the ASEAN members ( particularly Indonesia , Vietnam , Philippines , Thailand , Malaysia and Singapore ) , Australia , Russia , Canada , Mexico , and the United States . This idea can be compared to the historical Eurocentric/Atlantic viewpoint , which has dominated for the past two centuries . The term Asian Century is a more popularized term , shifting greater emphasis towards Asia , especially on the potential superpowers of China and India . Cities in those countries , such as Tokyo , Mumbai , Beijing , Kuala Lumpur , Jakarta , Manila , Singapore , Seoul , Hong Kong , Shanghai , Delhi , Pyongyang and Bangkok are increasingly gaining power as financial centres , displacing cities in Europe . However , critics of this associated term believe it incorrectly describes the 21st century and overstates the importance of the states around the Indian Ocean . Up until 2011 , this was proving to be true , as India had shown very promising growth , despite nagging infrastructure concerns . But with the continual unrest in Palestine and associated ultra critical Suez Canal , the Euro crisis , along with India 's and Brazil 's growth concerns , and Russia 's new look East policy , the Pacific Century is in fact a more accurate term than the Asian Century . Note the United States , Canada , and Mexico in particular are dual powers , both Pacific and Atlantic , however the West Coast of North America stands to benefit the most from the Pacific Century vis-à-vis the East Coast of North America . A 10-hour documentary entitled The Pacific Century was aired on PBS in 1992 , which covered the history of modern Asia and the West , as well as the future of the region . In a November 2011 article for Foreign Policy , the term was recast as America 's Pacific Century by US Secretary of State Hillary Clinton to succinctly describe the leading US foreign-policy goal of the 21st century . Acknowledging discussion of the rising threat to American power in the region from rapidly developing Pacific nations , most obviously China , Clinton said : `` One of the most important tasks of American statecraft over the next decade will therefore be to lock in a substantially increased investment -- diplomatic , economic , strategic , and otherwise -- in the Asia-Pacific region . '' President Barack Obama also toured various countries that month to bolster security alliances and work on a new trade bloc called the Trans-Pacific Partnership , from which China is excluded . The US was ASEAN 's largest trading partner in 2004 ; by 2012 China was the biggest trading partner of ASEAN by far , as well as the biggest of Japan , Korea , India and Australia . Clinton 's remarks were translated into official policy at the start of 2012 , as the Obama administration outlined a new China-centric military strategy . The preceding year , Clinton had already `` grabbed Beijing 's lapels '' by declaring the South China Sea as a vital American interest . The policy shift was denounced by Chinese state media , which declared that the Americans should not `` recklessly practice militarism '' , nor engage in `` war mongering '' . Unease from SE Asian countries at the militaristic rhetoric from the US led to a trip by Clinton in July 2012 , which aimed to extend economic ties to South East Asian countries that are becoming increasingly bound by trade with China , being spun as an adjustment to focusing more on economic issues . One indication of the comprehensiveness of the new American effort was Clinton 's visit to Laos , the first by a US Secretary of State since John Foster Dulles in 1955 . The end of summer 2013 saw US Defense Secretary Chuck Hagel forcefully lobbying the Philippines , a nation of major strategic importance , to permit a rotating American troop force to return to the country , an arrangement that would provide a fillip to the US military presence in the region . The rotating troop discussion was part of a broader framework agreement being negotiated by Washington and Manila that , if agreed , would permit American forces to operate out of Filipino military bases . The US response to the destruction visited on the Philippines by Typhoon Haiyan in November 2013 evidenced the rapidly expanding military alliance between the two countries . |
Palmdale,_California | Palmdale is a city in the center of northern Los Angeles County in the U.S. state of California . The San Gabriel Mountains separate Palmdale from the City of Los Angeles . On August 24 , 1962 , Palmdale became the first community in the Antelope Valley to incorporate . 47 years later , in November 2009 , voters approved making it a charter city . Its population was 152,750 at the 2010 census , up from 116,670 at the 2000 census . Palmdale is the 33rd most populous city in California . In 2013 , the Palmdale / Lancaster urban area had an estimated population of 513,547 . |
Patagonia | Patagonia ( -LSB- pa.ta.ˈɣo.ni̯a -RSB- ) is a sparsely populated region located at the southern end of South America , shared by Argentina and Chile . The region comprises the southern section of the Andes mountains as well as the deserts , pampas and grasslands east of this southern portion of the Andes . Patagonia has two coasts : western facing the Pacific Ocean and eastern facing the Atlantic Ocean . The Colorado and Barrancas rivers , which run from the Andes to the Atlantic , are commonly considered the northern limit of Argentine Patagonia . The archipelago of Tierra del Fuego is sometimes included as part of Patagonia . Most geographers and historians locate the northern limit of Chilean Patagonia at Reloncaví Estuary . |
Paleoatmosphere | A paleoatmosphere ( or palaeoatmosphere ) is an atmosphere , particularly that of Earth , at some unspecified time in the geological past . The composition of Earth 's paleoatmosphere can be inferred today from the study of the abundance of proxy materials such as iron oxides , charcoal and the stomatal density of fossil leaves in geological deposits . Although today 's atmosphere is dominated by nitrogen ( about 78 % ) , oxygen ( about 21 % ) , and argon ( about 1 % ) , the pre-biological atmosphere is thought to have been a highly reducing atmosphere , having virtually no free oxygen , virtually no argon , which is generated by the radioactive decay of 40K , and to have been dominated by nitrogen , carbon dioxide and methane . Appreciable concentrations of free oxygen were probably not present until about 2,500 million years ago ( Ma ) . After the Great Oxygenation Event , quantities of oxygen produced as a by-product of photosynthesis by cyanobacteria or blue-green algae began to exceed the quantities of chemically reducing materials , notably dissolved iron . By the beginning of the Cambrian period 541 Ma , free oxygen concentrations had increased sufficiently to enable the evolution of multicellular organisms . Following the subsequent appearance , rapid evolution and radiation of land plants , which covered much of the Earth 's land surface , beginning about 450 Ma , oxygen concentrations reached and later exceeded current values during the early Carboniferous , when atmospheric carbon dioxide was drawn down below current concentrations . This may have contributed to the Carboniferous Rainforest Collapse during the Moscovian and Kasimovian ages of the Pennsylvanian subperiod . |
Overproduction | In economics , overproduction , oversupply , excess of supply or glut refers to excess of supply over demand of products being offered to the market . This leads to lower prices and/or unsold goods along with the possibility of unemployment . The demand side equivalent is underconsumption ; some consider supply and demand two sides to the same coin -- excess supply is only relative to a given demand , and insufficient demand is only relative to a given supply -- and thus consider overproduction and underconsumption equivalent . Overproduction is often attributed as due to previous overinvestment -- creation of excess productive capacity , which must then either lie idle ( or under capacity ) , which is unprofitable , or produce an excess supply . |
Padrão | A padrão ( -LSB- pɐˈðɾɐ̃w̃ -RSB- , standard ; plural : padrões ) was a large stone cross inscribed with the coat of arms of Portugal that was placed as part of a land claim by numerous Portuguese explorers during the Portuguese Age of Discovery . Notable explorers known to have erected padrões were Diogo Cão , Bartolomeu Dias , Vasco da Gama , and Jorge Álvares . The Lisbon Geographic Society managed to restore in the 20th century three padrões erected by Diogo Cão and one by Bartolomeu Dias . At the Dias Cross Memorial on the coast of South Africa 's Eastern Cape province , there is a padrão replica on a spectacular outcrop ( False Island -- Kwaaihoek in Afrikaans , meaning `` Nasty corner '' ) ; it marks the site of Dias ' most easterly landfall , after becoming the first European navigator to round the Cape of Good Hope . The original padrão was discovered by Arthur Axelson in the 1930s -- it had fallen , or was pushed , off the top of Kwaaihoek , and was in pieces in the gullies below . Axelson recovered these pieces and was able to reconstruct the padrão the reconstructed original now stands in the William Cullen Library of the University of the Witwatersrand in Johannesburg . Indonesia National Museum hosts the Luso Sundanese padrão erected by Henrique Leme in 1522 in Sunda Kalapa port ( present day Tugu , sub-district of Jakarta , Indonesia ) . |
Paço_de_Arcos | Paço de Arcos ( -LSB- ˈpasu ˈdaɾkus -RSB- ) is a locality of Oeiras . In 2013 , the parish of Paço de Arcos merged into the new parish Oeiras e São Julião da Barra , Paço de Arcos e Caxias . The population in 2011 was 15,315 , in an area of 3.39 km ² . It was elevated to town by a decree at December 7 , 1926 . Its name comes from the Palácio dos Arcos located at the entrance to the village , where king D. Manuel I of Portugal watched Vasco da Gama 's caravels leave for India . Nowadays , the Portuguese maritime academy - Escola Náutica Infante D. Henrique - is based there . It 's also the base of the private business jet company NetJets Europe . Paço de Arcos is where Quinta da Fonte is located , one of the biggest office parks in Europe , being the home of companies such as General Electric , Hewlett Packard , among others . The town is featured in Robert Wilson 's 1999 novel A Small Death in Lisbon , as both the residence of the main character , Inspector José `` Zé '' Coelho , and where a body is found . |
Outcome_(probability) | In probability theory , an outcome is a possible result of an experiment . Each possible outcome of a particular experiment is unique , and different outcomes are mutually exclusive ( only one outcome will occur on each trial of the experiment ) . All of the possible outcomes of an experiment form the elements of a sample space . For the experiment where we flip a coin twice , the four possible outcomes that make up our sample space are ( H , T ) , ( T , H ) , ( T , T ) and ( H , H ) , where `` H '' represents a `` heads '' , and `` T '' represents a `` tails '' . Outcomes should not be confused with events , which are sets ( or informally , `` groups '' ) of outcomes . For comparison , we could define an event to occur when `` at least one ` heads ' '' is flipped in the experiment - that is , when the outcome contains at least one ` heads ' . This event would contains all outcomes in the sample space except the element ( T , T ) . |
Pacific_Northwest_windstorm | Pacific Northwest windstorms , sometimes colloquially known as Big Blows , are extratropical cyclones which form in the Pacific basin , and affect land areas in the Pacific Northwest of the United States and British Columbia , Canada . They form as cyclonic windstorms associated with areas of low atmospheric pressure that track across the North Pacific Ocean towards western North America . Deep low pressure areas are relatively common over the North Pacific . They are most common in the winter months . On average , the month when most windstorms form is December . The closest analogue to these storms are European windstorms , which also develop over the eastern portion of a major ocean . |
Pastaza_Province | Pastaza ( -LSB- pasˈtasa -RSB- ) is a province in the Oriente of Ecuador located in the eastern jungle . The capital is Puyo , founded on May 12 , 1899 and which boasts 36,700 inhabitants . The city is now accessible by paved roads , a recent development ; the main road from Baños follows the Pastaza river into the province . The Pastaza River surges into the province from the west and as the landscape flattens , meanders on to the Napo , a tributary of the Amazon . Natural resources of Pastaza are bananas , grapefruit , tobacco , cocoa and coffee . Tea has successfully been cultivated by a few British companies , and in the mid eighties one of the companies was honored by a visit from Princess Margaret from the royal family of Britain . The landscape is mostly mountainous in the western part of the province and becomes relatively flat toward the east as it nears the Peruvian border with rivers and plains characterizing most of the province . The highest elevation is 1,820 meters ( 5,970 ft ) . The climate is warm and humid due to the almost 7 meters of annual rainfall ( 22 feet ) in the parts closest to the western mountains , but with significant amounts of rainfall throughout the province . The median temperature is 18 to 24 Celsius . It is rumored that there is a lot of gold in the rivers of Pastaza ; however , to date no significant discoveries of gold have been reported . Snakes and other venomous creatures , such as tarantulas and scorpions , are common in the province . Travellers are advised to be cautious in any trekking through the jungles , parks and trails . Some of the snakes blend extremely well even in trees , so walking sticks and/or machetes are a good precaution for hiking . The flora of the region is spectacular . A few local parks have been developed with myriad natural orchids from the area and admittance to these parks is relatively inexpensive . Rainy day gear is advised since the rains are present almost year-round , many times in the late afternoon , but occasional all day as well . The rain is quite warm compared to those in North America . Pastaza is the largest province in Ecuador and the richest in biodiversity . To the north of Pastaza are the provinces Napo and Orellana , to the south is Morona Santiago , to the east is the country of Peru , and to the west are the provinces Tungurahua and Moronga Santiago . The total population is about 83,930 inhabitants . |
Paleocene–Eocene_Thermal_Maximum | The Paleocene -- Eocene Thermal Maximum ( PETM ) , alternatively ( ETM1 ) , and formerly known as the `` Initial Eocene '' or '' '' was a time period with more than 8 ° C warmer global average temperature than today . This climate event began at the time boundary between the Paleocene and Eocene geological epochs . The exact age and duration of the event is uncertain but it is estimated to have occurred around 55.5 million years ago . The associated period of massive carbon injection into the atmosphere has been estimated to have lasted no longer than 20,000 years . The entire warm period lasted for about 200,000 years . Global temperatures increased by 5 -- 8 ° C . The carbon dioxide was likely released in two pulses , the first lasting less than 2,000 years . Such a repeated carbon release is in line with current global warming . A main difference is that during the Paleocene -- Eocene Thermal Maximum , the planet was essentially ice-free . The onset of the Paleocene -- Eocene Thermal Maximum has been linked to an initial 5 ° C temperature rise and to extreme changes in Earth 's carbon cycle . The period is marked by a prominent negative excursion in carbon stable isotope records from around the globe ; more specifically , there was a large decrease in 13C/12C ratio of marine and terrestrial carbonates and organic carbon . Stratigraphic sections of rock from this period reveal numerous other changes . Fossil records for many organisms show major turnovers . For example , in the marine realm , a mass extinction of benthic foraminifera , a global expansion of subtropical dinoflagellates , and an appearance of excursion , planktic foraminifera and calcareous nanofossils all occurred during the beginning stages of PETM . On land , modern mammal orders ( including primates ) suddenly appear in Europe and in North America . Sediment deposition changed significantly at many outcrops and in many drill cores spanning this time interval . At least since 1997 , the Paleocene -- Eocene Thermal Maximum has become a focal point of considerable geoscience research because it probably provides the best past analog by which to understand impacts of global climate warming and of massive carbon input to the ocean and atmosphere , including ocean acidification . Although it is now widely accepted that the PETM represents a `` case study '' for global warming and massive carbon input to Earth 's surface , the cause , details and overall significance of the event remain perplexing . |
Oxygen_cycle | The oxygen cycle is the biogeochemical cycle of oxygen within its three main reservoirs : the atmosphere ( air ) , the total content of biological matter within the biosphere ( the global sum of all ecosystems ) , and the Earth 's crust . Failures in the oxygen cycle within the hydrosphere ( the combined mass of water found on , under , and over the surface of planet Earth ) can result in the development of hypoxic zones . The main driving factor of the oxygen cycle is photosynthesis , which is responsible for the modern Earth 's atmosphere and life on earth ( see the Great Oxygenation Event ) . |
Particulates | Atmospheric particulate matter -- also known as particulate matter ( PM ) or particulates -- are microscopic solid or liquid matter suspended in the Earth 's atmosphere . The term aerosol commonly refers to the particulate/air mixture , as opposed to the particulate matter alone . Sources of particulate matter can be man-made or natural . They have impacts on climate and precipitation that adversely affect human health . Subtypes of atmospheric particulate matter include suspended particulate matter ( SPM ) , thoracic and respirable particles , inhalable coarse particles , which are -LSB- coarse -RSB- particles with a diameter between 2.5 and 10 micrometers ( μm ) ( PM10 ) , fine particles with a diameter of 2.5 μm or less ( PM2 .5 ) , ultrafine particles , and soot The IARC and WHO designate airborne particulates a Group 1 carcinogen . Particulates are the deadliest form of air pollution due to their ability to penetrate deep into the lungs and blood streams unfiltered , causing permanent DNA mutations , heart attacks , and premature death . In 2013 , a study involving 312,944 people in nine European countries revealed that there was no safe level of particulates and that for every increase of 10 μg / m3 in PM10 , the lung cancer rate rose 22 % . The smaller PM2 .5 were particularly deadly , with a 36 % increase in lung cancer per 10 μg / m3 as it can penetrate deeper into the lungs . |
Palm_Beach_County,_Florida | Palm Beach County is a county located in the state of Florida , directly north of Broward County . As of the 2010 census , the population was 1,320,134 , making it the third-most populous county in Florida . The largest city and county seat is West Palm Beach . Named after one of its oldest settlements , Palm Beach , the county was established in 1909 , after being split from Dade County . The county 's modern-day boundaries were established in 1963 . Palm Beach County is one of the three counties in South Florida which make up the Miami metropolitan area , which was home to an estimated 6,012,331 people at the 2015 census . The area had been increasing in population since the late 19th century , with the incorporation of West Palm Beach in 1894 and after Henry Flagler extended the Florida East Coast Railway and built the Royal Poinciana Hotel , The Breakers , and Whitehall . In 1928 , the Okeechobee hurricane struck West Palm Beach and caused thousands of deaths . Since then , a number of other tropical cyclones have impacted the area . More recently , the county acquired national attention during the 2000 presidential election , when a controversial recount occurred . As of 2004 , Palm Beach County is Florida 's wealthiest county , with a per capita personal income of $ 44,518 . It leads the state in agricultural productivity , agriculture is Palm Beach County 's 2nd largest industry . |
Patos_Island | Patos Island is a small island in the San Juan Islands of the U.S. state of Washington . Since 1893 , it has been home to the Patos Island Lighthouse , guiding vessels through Boundary Pass between Canada and the United States . The name comes from the Spanish pato , meaning `` duck , '' which was given to the island in 1792 by Commander Dionisio Alcalá Galiano of the Sutil and Captain Cayetano Valdés y Flores of the Mexicana . The island and adjacent islets comprise Patos Island State Park , a 207 acre marine park with 20000 ft of saltwater shoreline . The entire island is owned by the federal government and is administered by the Bureau of Land Management 's Wenatchee Office . The Washington State Parks and Recreation Commission operates a small campground facility at Active Cove near the west side of the island , maintains a 1.5 mi loop trail , and has two offshore mooring buoys . The entire island , including the lighthouse , is part of the San Juan Islands National Monument , created in 2013 . |
Paleo-Indians | Paleo-Indians , Paleoindians or Paleoamericans is a classification term given to the first peoples who entered , and subsequently inhabited , the Americas during the final glacial episodes of the late Pleistocene period . The prefix `` paleo - '' comes from the Greek adjective palaios , meaning `` old '' or `` ancient '' . The term `` Paleo-Indians '' applies specifically to the lithic period in the Western Hemisphere and is distinct from the term `` Paleolithic '' . Evidence suggests big-animal hunters crossed the Bering Strait from Eurasia into North America over a land and ice bridge ( Beringia ) , that existed between 45,000 -- 12,000 BCE ( 47,000 -- 14,000 BP ) . Small isolated groups of hunter-gatherers migrated alongside herds of large herbivores far into Alaska . From BCE ( BP ) , ice-free corridors developed along the Pacific coast and valleys of North America . This allowed animals , followed by humans , to migrate south into the interior . The people went on foot or used primitive boats along the coastline . The precise dates and routes of the peopling of the New World are subject to ongoing debate . Stone tools , particularly projectile points and scrapers , are the primary evidence of the earliest human activity in the Americas . Crafted lithic flaked tools are used by archaeologists and anthropologists to classify cultural periods . Scientific evidence links Indigenous Americans to Asian peoples , specifically eastern Siberian populations . Indigenous peoples of the Americas have been linked to Siberian populations by linguistic factors , the distribution of blood types , and in genetic composition as reflected by molecular data , such as DNA . There is evidence for at least two separate migrations . Between 8000 -- 7000 BCE ( 10,000 -- 9,000 BP ) the climate stabilized , leading to a rise in population and lithic technology advances , resulting in more sedentary lifestyle . |
Palearctic_realm | The Palearctic or Palaearctic is the largest of the eight biogeographic realms constituting the Earth 's surface . It consists of Europe , Asia north of the foothills of the Himalayas , North Africa , and the northern and central parts of the Arabian Peninsula . The Palearctic realm comprises the smaller terrestrial ecoregions of the Euro-Siberian region ; the Mediterranean Basin ; the Sahara and Arabian Deserts ; and Western , Central and East Asia . The Palaearctic realm also has numerous rivers and lakes , forming several freshwater ecoregions . Some of the rivers were the source of water for the earliest recorded civilizations that used irrigation methods . |
Parabolic_antenna | A parabolic antenna is an antenna that uses a parabolic reflector , a curved surface with the cross-sectional shape of a parabola , to direct the radio waves . The most common form is shaped like a dish and is popularly called a dish antenna or parabolic dish . The main advantage of a parabolic antenna is that it has high directivity . It functions similarly to a searchlight or flashlight reflector to direct the radio waves in a narrow beam , or receive radio waves from one particular direction only . Parabolic antennas have some of the highest gains , meaning that they can produce the narrowest beamwidths , of any antenna type . In order to achieve narrow beamwidths , the parabolic reflector must be much larger than the wavelength of the radio waves used , so parabolic antennas are used in the high frequency part of the radio spectrum , at UHF and microwave ( SHF ) frequencies , at which the wavelengths are small enough that conveniently-sized reflectors can be used . Parabolic antennas are used as high-gain antennas for point-to-point communications , in applications such as microwave relay links that carry telephone and television signals between nearby cities , wireless WAN/LAN links for data communications , satellite communications and spacecraft communication antennas . They are also used in radio telescopes . The other large use of parabolic antennas is for radar antennas , in which there is a need to transmit a narrow beam of radio waves to locate objects like ships , airplanes , and guided missiles . With the advent of home satellite television receivers , parabolic antennas have become a common feature of the landscapes of modern countries . The parabolic antenna was invented by German physicist Heinrich Hertz during his discovery of radio waves in 1887 . He used cylindrical parabolic reflectors with spark-excited dipole antennas at their focus for both transmitting and receiving during his historic experiments . |
Patient_safety | Patient safety is a discipline that emphasizes safety in health care through the prevention , reduction , reporting , and analysis of medical error that often leads to adverse effects . The frequency and magnitude of avoidable adverse events experienced by patients was not well known until the 1990s , when multiple countries reported staggering numbers of patients harmed and killed by medical errors . Recognizing that healthcare errors impact 1 in every 10 patients around the world , the World Health Organization calls patient safety an endemic concern . Indeed , patient safety has emerged as a distinct healthcare discipline supported by an immature yet developing scientific framework . There is a significant transdisciplinary body of theoretical and research literature that informs the science of patient safety . The resulting patient safety knowledge continually informs improvement efforts such as : applying lessons learned from business and industry , adopting innovative technologies , educating providers and consumers , enhancing error reporting systems , and developing new economic incentives . |
Paleontology_in_Alaska | Paleontology in Alaska refers to paleontological research occurring within or conducted by people from the U.S. state of Alaska . During the Late Precambrian , Alaska was covered by a shallow sea that was home to stromatolite-forming bacteria . Alaska remained submerged into the Paleozoic era and the sea came to be home to creatures including ammonites , brachiopods , and reef-forming corals . An island chain formed in the eastern part of the state . Alaska remained covered in seawater during the Triassic and Jurassic . Local wildlife included ammonites , belemnites , bony fish and ichthyosaurs . Alaska was a more terrestrial environment during the Cretaceous , with a rich flora and dinosaur fauna . During the early Cenozoic , Alaska had a subtropical environment . The local seas continued to drop until a land bridge connected the state with Asia . Early humans crossed this bridge and remains of contemporary local wildlife such as woolly mammoths often show signs of having been butchered . More recent Native Americans interpreted local fossils through a mythological lens . The local fossils had attracted the attention of formally trained scientists by the 1830s . Major local finds include the Kikak-Tegoseak Pachyrhinosaurus bonebed . The Pleistocene-aged wooly mammoth , Mammuthus primigenius is the Alaska state fossil . |
Overcast | Overcast or overcast weather , as defined by the World Meteorological Organization , is the meteorological condition of clouds obscuring all of the sky by at least 95 percent . However , the total sky cover must not be entirely due to surface-based obscuring phenomena such as fog . Overcast , written as `` OVC '' in the METAR observation , is reported when the cloud cover is observed to equal eight oktas ( eighths ) . An overcast sky may be explicitly identified as thin ( predominantly transparent ) but otherwise is considered opaque which always constitutes a ceiling in aviation meteorology . Sometimes clouds can be different colors such as black or white , but overcast usually refers to darker skies . In some cases , it can be impossible to see distinct borders of clouds or the sky may be covered by a single type of cloud , such as stratus and the whole sky will be a dull white . Periods of overcast weather can range from a few hours to several days . Overcast weather can also affect people suffering from seasonal affective disorder . The same weather , when observed from above , might be referred to as ( an ) undercast . |
Outcome_bias | The outcome bias is an error made in evaluating the quality of a decision when the outcome of that decision is already known . Specifically , the outcome effect occurs when the same `` behavior produce -LSB- s -RSB- more ethical condemnation when it happen -LSB- s -RSB- to produce bad rather than good outcome , even if the outcome is determined by chance . '' While similar to the hindsight bias , the two phenomena are markedly different . The hindsight bias focuses on memory distortion to favor the actor , while the outcome bias focuses exclusively on weighting the past outcome heavier than other pieces of information in deciding if a past decision was correct . |
Paleo-Tethys_Ocean | The Paleo-Tethys or Palaeo-Tethys Ocean was an ocean located along the northern margin of the paleocontinent Gondwana that started to open during the Middle Cambrian , grew throughout the Paleozoic , and finally closed during the Late Triassic ; existing for about 400 million years . Paleo-Tethys was a precursor to the Tethys Ocean ( also called the Neo-Tethys ) which was located between Gondwana and the Hunic terranes ( continental fragments that broke-off Gondwana and moved north ) . It opened as the Proto-Tethys Ocean subducted under these terranes and closed as the Cimmerian terranes ( that also broke-off Gondwana and moved north ) gave way to the Tethys Ocean . Confusingly , the Neo-Tethys is sometimes defined as the ocean south of a hypothesised mid-ocean ridge separating Greater Indian from Asia , in which case the ocean between Cimmeria and this hypothesised ridge is called the Meso-Tethys , i.e. the `` Middle-Tethys '' . The so-called Hunic terranes are divided into the European Hunic ( today the crust under parts of Europe -- called Armorica -- and Iberia ) and Asiatic Hunic ( today the crust of parts of southern Asia ) . A large transform fault separated the two terranes . The role the Paleo-Tethys played in the supercontinent cycle , and especially the break-up of Pangaea , is unresolved . Some geologists argue that the opening of the North Atlantic was triggered by the subduction of Panthalassa under the western margins of the Americas while other argue that the closure of the Paleo-Tethys and Tethys resulted in the break-up . In the first scenario , mantle plumes caused the opening of the Atlantic and the break-up of Pangaea and the closure of the Tethyan domain was one of the consequences of this process ; in the other scenario , the longitudinal forces that closed the Tethyan domain were transmitted latitudinally in what is today the Mediterranean region , resulting in the initial opening of the Atlantic . |
Palos_Verdes_Peninsula | The Palos Verdes Peninsula is a landform and a geographic sub-region of the Los Angeles metropolitan area , within southwestern Los Angeles County in the U.S. state of California . Located in the South Bay region , the peninsula contains a group of affluent cities in the Palos Verdes Hills , including Palos Verdes Estates , Rancho Palos Verdes , Rolling Hills and Rolling Hills Estates . The South Bay city of Torrance borders the peninsula on the north , the Pacific Ocean is on the west and south , and the Port of Los Angeles is east . The hill cities on the peninsula are known for dramatic ocean and city views , distinguished schools , extensive horse trails , and expensive homes . |
Petroleum_in_the_United_States | Petroleum in the United States has been a major industry since shortly after the oil discovery in the Oil Creek area of Titusville , Pennsylvania in 1859 . The petroleum industry includes exploration for , production , processing ( refining ) , transportation , and marketing of natural gas and petroleum products . As of 2008 , the U.S. was the world 's third-largest oil producer ( after Saudi Arabia and Russia ) , producing 8.5 million barrels of oil and natural gas liquids per day . The leading oil-producing area in the United States in 2014 was Texas ( 3.17 Moilbbl per day ) , followed by the federal zone of the Gulf of Mexico ( 1.40 Moilbbl per day ) , followed by North Dakota ( 1.09 Moilbbl per day ) and California ( 0.50 Moilbbl per day ) . In 2015 , US production of crude oil rose to 9.48 million barrels per day , the highest annual rate since 1972 , and an increase of 90 % from the 2008 production of 5.00 million barrels per day . On a monthly basis , however , US production peaked in April 2015 at 9.63 million barrels per day , then declined due to lower oil prices to 8.74 million barrels per day in August 2016 . US Natural gas production achieved new record highs for each year from 2011 through 2014 . Marketed natural gas production in 2014 was 74.7 billion cubic feet per day , a 44 % increase over the rate of 51.9 billion cubic feet per day in 2005 . Over the same time period , production of natural gas liquids increased 70 % , from 1.74 million barrels per day in 2005 to 2.96 million barrels per day in 2014 . In April 2015 , natural gas was produced at the rate of 79.4 billion cubic feet per day . In 2014 , petroleum and natural gas were the two largest sources of energy in the U.S. , together providing 63 percent of the energy consumed ( oil provided 35 percent and gas 28 percent ) . In 2008 the United States consumed 19.5 Moilbbl per day of petroleum products , of which 46 percent was gasoline , 20 percent diesel fuel and heating oil , and 10 percent liquefied petroleum gas . In 2015 , the U.S. imported 24 % of the petroleum it used , the lowest since 1970 . The largest sources of U.S. imported oil were : Canada ( 40 % ) , Saudi Arabia ( 11 % ) , Venezuela ( 9 % ) , Mexico ( 8 % ) , and Colombia ( 4 % ) . According to the American Petroleum Institute , the oil and natural gas industry supports nine million U.S. jobs and makes up seven percent of the nation 's gross domestic product . |
Policy_uncertainty | Policy uncertainty ( also called regime uncertainty ) is a class of economic risk where the future path of government policy is uncertain , raising risk premia and leading businesses and individuals to delay spending and investment until this uncertainty has been resolved . Policy uncertainty may refer to uncertainty about monetary or fiscal policy , the tax or regulatory regime , or uncertainty over electoral outcomes that will influence political leadership . |
Peter_Sinclair_(environmental_activist) | Peter Sinclair from Midland , Michigan ( born 1953 ) , is an environmental activist whose focus is on climate change . He is a YouTube blogger , explorer and founder of the ClimateCrocks.com website . Together with climate researchers he 's traveled to hot spots of climate change , for instance to Greenland as part of the Dark Snow Project . Sinclair is perhaps best known for producing the Climate Denial Crock of the Week series on his YouTube channel . Videos have received praise from climate scientists such as Gavin Schmidt , Michael E. Mann , and the late Stephen Schneider . In 2012 , he launched another YouTube series , entitled This is not Cool , for the Yale Project on Climate Change Communication . |
Petroleum | Petroleum ( from petra #Greek : `` rock '' + oleum #Latin : `` oil '' . ) is a naturally occurring , yellow-to-black liquid found in geological formations beneath the Earth 's surface , which is commonly refined into various types of fuels . Components of petroleum are separated using a technique called fractional distillation . It consists of hydrocarbons of various molecular weights and other organic compounds . The name petroleum covers both naturally occurring unprocessed crude oil and petroleum products that are made up of refined crude oil . A fossil fuel , petroleum is formed when large quantities of dead organisms , usually zooplankton and algae , are buried underneath sedimentary rock and subjected to both intense heat and pressure . Petroleum has mostly been recovered by oil drilling ( natural petroleum springs are rare ) . Drilling is carried out after studies of structural geology ( at the reservoir scale ) , sedimentary basin analysis , and reservoir characterization ( mainly in terms of the porosity and permeability of geologic reservoir structures ) have been completed . It is refined and separated , most easily by distillation , into a large number of consumer products , from gasoline ( petrol ) and kerosene to asphalt and chemical reagents used to make plastics and pharmaceuticals . Petroleum is used in manufacturing a wide variety of materials , and it is estimated that the world consumes about 95 million barrels each day . Concern over the depletion of the earth 's finite reserves of oil , and the effect this would have on a society dependent on it , is a concept known as peak oil . The use of fossil fuels , such as petroleum , will have a negative impact on Earth 's biosphere , damaging ecosystems through events such as oil spills and releasing a range of pollutants into the air including ground-level ozone and sulfur dioxide from sulfur impurities in fossil fuels . The burning of fossil fuels plays the major role in the current episode of global warming . |
Pesticide_regulation_in_the_United_States | Pesticide regulation in the United States is primarily a responsibility of the Environmental Protection Agency . |
Planning_fallacy | The planning fallacy , first proposed by Daniel Kahneman and Amos Tversky in 1979 , is a phenomenon in which predictions about how much time will be needed to complete a future task display an optimism bias and underestimate the time needed . This phenomenon occurs regardless of the individual 's knowledge that past tasks of a similar nature have taken longer to complete than generally planned . The bias only affects predictions about one 's own tasks ; when outside observers predict task completion times , they show a pessimistic bias , overestimating the time needed . The planning fallacy requires that predictions of current tasks ' completion times are more optimistic than the beliefs about past completion times for similar projects and that predictions of the current tasks ' completion times are more optimistic than the actual time needed to complete the tasks . In 2003 , Lovallo and Kahneman proposed an expanded definition as the tendency to underestimate the time , costs , and risks of future actions and at the same time overestimate the benefits of the same actions . According to this definition , the planning fallacy results in not only time overruns , but also cost overruns and benefit shortfalls . |
Polar_seas | Polar seas is a collective term for the Arctic Ocean ( about 4-5 percent of Earth 's oceans ) and the southern part of the Southern Ocean ( south of Antarctic Convergence , about 10 percent of Earth 's oceans ) . In the coldest years , sea ice can cover around 13 percent of the Earth 's total surface at its maximum , but out of phase in the two hemispheres . The polar seas contain a huge biome with many organisms . Among the species that inhabit various polar seas and surrounding land areas are polar bear , penguin , reindeer ( caribou ) , muskox , wolverine , ermine , lemming , Arctic hare , Arctic ground squirrel , whale , harp seal , and walrus . These species have unique adaptations to the extreme conditions . Many might be endangered if they can not adapt to changing conditions . Contrary to popular opinion , the World Wildlife Fund studies for polar bears show that this species has prospered since 1950 , attaining five times the numbers found in 1950 . In general , Arctic ecosystems are relatively fragile and slow to recover from serious damage . |
Polar_forests_of_the_Cretaceous | Cretaceous polar forests were temperate forests that grew at polar latitudes during the final period of the Mesozoic Era , known as the Cretaceous Period 145 -- 66 Ma . During this period , global average temperature was about 10 C-change higher and carbon dioxide ( CO2 ) levels were approximately 1000 parts per million ( ppm ) , 2.5 times the current concentration in Earth 's atmosphere . The abundance of atmospheric carbon dioxide had a very significant impact on global climate and Earth 's natural systems as its concentration is considered one of the main factors in the development of a pronounced greenhouse Earth during the Cretaceous with a very low average global temperature gradient . As a consequence , high paleolatitudes in both hemispheres were much warmer than at present . This temperature gradient was partly responsible for the lack of continental ice sheets in polar regions . As a response to elevated global temperatures , the Earth 's hydrologic cycle was significantly enhanced due to greater volume of moisture evaporation from the surface of the ocean . In turn , the absolute sea level during this time period stood at elevations much higher than the present level . Continental encroachment of seawater formed widespread shallow seas , including expanses of epeiric seas . An increase in surface area between shallow , warm epeiric seawater and the atmosphere permits higher evaporation rates and more precipitation at various latitudes , producing a more temperate global climate . A widespread temperate climate also had significant effects on high latitude ecosystems . |
Phosphorus | Phosphorus is a chemical element with symbol P and atomic number 15 . As an element , phosphorus exists in two major forms -- white phosphorus and red phosphorus -- but because it is highly reactive , phosphorus is never found as a free element on Earth . At 0.099 % , phosphorus is the most abundant pnictogen in the Earth 's crust . With few exceptions , minerals containing phosphorus are in the maximally oxidized state as inorganic phosphate rocks . The first form of elemental phosphorus to be produced ( white phosphorus , in 1669 ) emits a faint glow when exposed to oxygen -- hence the name , taken from Greek mythology , Φωσφόρος meaning `` light-bearer '' ( Latin Lucifer ) , referring to the `` Morning Star '' , the planet Venus ( or Mercury ) . The term `` phosphorescence '' , meaning glow after illumination , originally derives from this property of phosphorus , although this word has since been used for a different physical process that produces a glow . The glow of phosphorus itself originates from oxidation of the white ( but not red ) phosphorus -- a process now termed chemiluminescence . Together with nitrogen , arsenic , antimony , and bismuth , phosphorus is classified as a pnictogen . Phosphorus is essential for life . Phosphates ( compounds containing the phosphate ion , PO43 − ) are a component of DNA , RNA , ATP , and the phospholipids , which form all cell membranes . Demonstrating the link between phosphorus and life , elemental phosphorus was first isolated from human urine , and bone ash was an important early phosphate source . Phosphate mines contain fossils , especially marine fossils , because phosphate is present in the fossilized deposits of animal remains and excreta . Low phosphate levels are an important limit to growth in some aquatic systems . The vast majority of phosphorus compounds produced are consumed as fertilisers . Phosphate is needed to replace the phosphorus that plants remove from the soil , and its annual demand is rising nearly twice as fast as the growth of the human population . Other applications include the role of organophosphorus compounds in detergents , pesticides , and nerve agents . |
Polarity_chron | A polarity chron , or chron , is the time interval between polarity reversals of Earth 's magnetic field . It is a term used in stratigraphy ( a branch of geology ) to name the time interval represented by a magnetostratigraphic polarity unit . It represents a certain time period in geologic history where the Earth 's magnetic field was in a `` normal '' and `` reversed '' position . Chrons are numbered in order starting from today and increasing in number into the past . As well as a number , each chron is divided into two parts , labelled `` n '' and `` r '' , thereby showing the position of the field 's polarity . A chron is the time equivalent to a chronozone or a polarity zone . It is called a `` polarity subchron '' when the interval is less than 200,000 years long . |
Polar_desert | Polar deserts are areas with annual precipitation less than 250 mm and a mean temperature of less than 10 C during the warmest months . Polar deserts on Earth cover nearly 5,000,000 km2 and consist primarily of hard bedrock or gravel plains . Polar deserts are one of two polar biomes : polar deserts and Arctic tundra . These biomes are located at the poles of the earth , specifically , the Arctic , northernmost North America , Europe , and Asia , and Antarctica . Polar deserts are located in the Arctic and Antarctic . Unlike the tundra that can support plant and animal life in the summer , polar deserts are barren with permanent layers of ice . However , there is evidence of life in this seemingly inhospitable environment.The thick ice contains sediments of organic and inorganic substances which create a habitable environment for microbial organisms . These organisms are closely related to cyanobacteria which have a variety of functions , particularly , fixing carbon dioxide from the melting water . Temperature changes in polar deserts frequently cross the freezing point of water . This `` freeze-thaw '' alternation forms patterned textures on the ground , as much as 5 m in diameter ( as seen in the picture on the right ) . Most of the interior of Antarctica is polar desert , despite the thick ice cover . Conversely , the McMurdo Dry Valleys of Antarctica , although they have had no ice for thousands of years due to katabatic wind , are not necessarily polar desert . Polar deserts are relatively common during ice ages , as ice ages tend to be dry . Climate scientists have voiced concerns about the effects of global warming to the ice poles in these polar biomes . |
Photosynthesis | Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that can later be released to fuel the organisms ' activities ( energy transformation ) . This chemical energy is stored in carbohydrate molecules , such as sugars , which are synthesized from carbon dioxide and water -- hence the name photosynthesis , from the Greek φῶς , phōs , `` light '' , and σύνθεσις , synthesis , `` putting together '' . In most cases , oxygen is also released as a waste product . Most plants , most algae , and cyanobacteria perform photosynthesis ; such organisms are called photoautotrophs . Photosynthesis is largely responsible for producing and maintaining the oxygen content of the Earth 's atmosphere , and supplies all of the organic compounds and most of the energy necessary for life on Earth . Although photosynthesis is performed differently by different species , the process always begins when energy from light is absorbed by proteins called reaction centres that contain green chlorophyll pigments . In plants , these proteins are held inside organelles called chloroplasts , which are most abundant in leaf cells , while in bacteria they are embedded in the plasma membrane . In these light-dependent reactions , some energy is used to strip electrons from suitable substances , such as water , producing oxygen gas . The hydrogen freed by the splitting of water is used in the creation of two further compounds that act as an immediate energy storage means : reduced nicotinamide adenine dinucleotide phosphate ( NADPH ) and adenosine triphosphate ( ATP ) , the `` energy currency '' of cells . In plants , algae and cyanobacteria , long-term energy storage in the form of sugars is produced by a subsequent sequence of reactions called the Calvin cycle ; some bacteria use different mechanisms , such as the reverse Krebs cycle , to achieve the same end . In the Calvin cycle , atmospheric carbon dioxide is incorporated into already existing organic carbon compounds , such as ribulose bisphosphate ( RuBP ) . Using the ATP and NADPH produced by the light-dependent reactions , the resulting compounds are then reduced and removed to form further carbohydrates , such as glucose . The first photosynthetic organisms probably evolved early in the evolutionary history of life and most likely used reducing agents such as hydrogen or hydrogen sulfide , rather than water , as sources of electrons . Cyanobacteria appeared later ; the excess oxygen they produced contributed directly to the oxygenation of the Earth , which rendered the evolution of complex life possible . Today , the average rate of energy capture by photosynthesis globally is approximately 130 terawatts , which is about three times the current power consumption of human civilization . Photosynthetic organisms also convert around 100 -- 115 thousand million metric tonnes of carbon into biomass per year . |
Pie_chart | A pie chart ( or a circle chart ) is a circular statistical graphic which is divided into slices to illustrate numerical proportion . In a pie chart , the arc length of each slice ( and consequently its central angle and area ) , is proportional to the quantity it represents . While it is named for its resemblance to a pie which has been sliced , there are variations on the way it can be presented . The earliest known pie chart is generally credited to William Playfair 's Statistical Breviary of 1801 . Pie charts are very widely used in the business world and the mass media . However , they have been criticized , and many experts recommend avoiding them , pointing out that research has shown it is difficult to compare different sections of a given pie chart , or to compare data across different pie charts . Pie charts can be replaced in most cases by other plots such as the bar chart , box plot or dot plots . |
Plague_(disease) | Plague is an infectious disease that is caused by the bacterium Yersinia pestis . Depending on lung infection , or sanitary conditions , plague can be spread in the air , by direct contact , or very rarely by contaminated undercooked food . The symptoms of plague depend on the concentrated areas of infection in each person : bubonic plague in lymph nodes , septicemic plague in blood vessels , pneumonic plague in lungs . It is treatable if detected early . Plague is still relatively common in some remote parts of the world . Until June 2007 , plague was one of the three epidemic diseases specifically reportable to the World Health Organization ( cholera and yellow fever the other two ) . The bacterium is named after the French-Swiss bacteriologist Alexandre Yersin . Historically , what are thought to have been massive pandemics of plague swept through Eurasia with very high death rates and causing major cultural changes . The largest of these were the Plague of Justinian of 541 -- 542 , The Black Death of the 1340s , continuing in the Second plague pandemic to break out at intervals , and the Third plague pandemic beginning in 1855 and considered inactive from 1959 . The epidemiological use of the term plague is currently applied to any severe bubo inflammation resulting from an infection with Y. pestis . Historically , the medical use of the term plague has been applied to pandemic infections in general . Plague is often synonymous with bubonic plague , but this describes just one of its manifestations . Other names have been used to describe this disease , such as Black Plague and the Black Death ; the latter is now used primarily by scholars to describe the second , and most devastating , pandemic of the disease . The etymology of the word plague is believed to come from the Latin word plāga ( `` blow , wound '' ) and plangere ( `` to strike , or to strike down '' ) , cf. German Plage ( `` infestation '' ) . |
Plate_tectonics | Plate tectonics ( from the Late Latin tectonicus , from the τεκτονικός `` pertaining to building '' ) is a scientific theory describing the large-scale motion of 7 large plates and the movements of a larger number of smaller plates of the Earth 's lithosphere , over the last hundreds of millions of years . The theoretical model builds on the concept of continental drift , an idea developed during the first few decades of the 20th century . The geoscientific community accepted plate-tectonic theory after seafloor spreading was validated in the late 1950s and early 1960s . The lithosphere , which is the rigid outermost shell of a planet ( the crust and upper mantle ) , is broken up into tectonic plates . The Earth 's lithosphere is composed of seven or eight major plates ( depending on how they are defined ) and many minor plates . Where the plates meet , their relative motion determines the type of boundary : convergent , divergent , or transform . Earthquakes , volcanic activity , mountain-building , and oceanic trench formation occur along these plate boundaries . The relative movement of the plates typically ranges from zero to 100 mm annually . Tectonic plates are composed of oceanic lithosphere and thicker continental lithosphere , each topped by its own kind of crust . Along convergent boundaries , subduction carries plates into the mantle ; the material lost is roughly balanced by the formation of new ( oceanic ) crust along divergent margins by seafloor spreading . In this way , the total surface of the lithosphere remains the same . This prediction of plate tectonics is also referred to as the conveyor belt principle . Earlier theories , since disproven , proposed gradual shrinking ( contraction ) or gradual expansion of the globe . Tectonic plates are able to move because the Earth 's lithosphere has greater mechanical strength than the underlying asthenosphere . Lateral density variations in the mantle result in convection . Plate movement is thought to be driven by a combination of the motion of the seafloor away from the spreading ridge ( due to variations in topography and density of the crust , which result in differences in gravitational forces ) and drag , with downward suction , at the subduction zones . Another explanation lies in the different forces generated by tidal forces of the Sun and Moon . The relative importance of each of these factors and their relationship to each other is unclear , and still the subject of much debate . |
Permo-Carboniferous | The Permo-Carboniferous refers to the time period including the latter parts of the Carboniferous and early part of the Permian period . Permo-Carboniferous rocks are in places not differentiated because of the presence of transitional fossils , and also where no conspicuous stratigraphic break is present . Permo-Carboniferous time , about 300 million years ago , was a period of significant glaciation . The widespread distribution of Permo-Carboniferous glacial sediments in South America , Africa , Madagascar , Arabia , India , Antarctica and Australia was one of the major pieces of evidence for the theory of continental drift , and led ultimately to the concept of a super-continent , Pangaea . Glacial activity spanned virtually the whole of Carboniferous and Early Permian time . Toward the end of the Carboniferous , around 290 million years ago , Gondwana , the southern part of Pangaea , was located near the south pole . Glacial centres expanded across the continents , producing glacial tillites and striations in pre-existing rocks . A complex centre of glaciation migrated across South America , Antarctica and South Africa between about 350 and 240 Ma . Chronological difficulties complicate the task of charting the evolution of the ice sheet over this interval . The Permo-Carboniferous ice sheet was so extensive that it would occupy a circle spanning 50 degrees of latitude centered on the pole . |
Politicization_of_science | The politicization of science is the manipulation of science for political gain . It occurs when government , business , or advocacy groups use legal or economic pressure to influence the findings of scientific research or the way it is disseminated , reported or interpreted . The politicization of science may also negatively affect academic and scientific freedom . Historically , groups have conducted various campaigns to promote their interests in defiance of scientific consensus , and in an effort to manipulate public policy . |
Pliocene | The Pliocene ( -LSB- pronˈplaɪəˌsiːn -RSB- also Pleiocene ) Epoch is the epoch in the geologic timescale that extends from 5.333 million to 2.58 million years BP . It is the second and youngest epoch of the Neogene Period in the Cenozoic Era . The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch . Prior to the 2009 revision of the geologic time scale , which placed the four most recent major glaciations entirely within the Pleistocene , the Pliocene also included the Gelasian stage , which lasted from 2.588 to 1.806 million years ago , and is now included in the Pleistocene . As with other older geologic periods , the geological strata that define the start and end are well identified but the exact dates of the start and end of the epoch are slightly uncertain . The boundaries defining the Pliocene are not set at an easily identified worldwide event but rather at regional boundaries between the warmer Miocene and the relatively cooler Pliocene . The upper boundary was set at the start of the Pleistocene glaciations . |
Phoenicia | Phoenicia ( -LSB- fᵻˈnɪʃə -RSB- or -LSB- fəˈniːʃə -RSB- from the Φοινίκη , meaning either `` land of palm trees '' or `` purple country '' ; فينيقية , ) was a thalassocratic ancient Semitic civilization , that originated in the Eastern Mediterranean and in the west of the Fertile Crescent . It included the coastline of what is now Lebanon , Israel , Gaza , Syria , and south-west Turkey , though some of its colonies later reached the Western Mediterranean ( most notably Carthage ) and even the Atlantic Ocean . The civilization spread across the Mediterranean between 1500 BC and 300 BC . Phoenicia is a Classical Greek term used to refer to the major export of the region , cloth dyed Tyrian purple from the Murex mollusc , and referred to the major Canaanite port towns , and it does not correspond exactly to a cultural identity that would have been recognised by the Phoenicians themselves . Their civilization was organized in city-states , similar to those of Ancient Greece , perhaps the most notable of which were Tyre , Sidon , Arvad , Berytus and Carthage . Each city-state was a politically independent unit , and it is uncertain to what extent the Phoenicians viewed themselves as a single nationality . In terms of archaeology , language , lifestyle , and religion there was little to set the Phoenicians apart as markedly different from other Semitic Canaanites . Around 1050 BC , a Phoenician alphabet was used for the writing of Phoenician . It became one of the most widely used writing systems , spread by Phoenician merchants across the Mediterranean world , where it evolved and was assimilated by many other cultures . |
Piezophile | A piezophile , also sometimes called a barophile , is an organism which thrives at high pressures , such as deep sea bacteria or archaea . They are generally found on ocean floors , where pressure often exceeds 380 atm ( 38 MPa ) . Some have been found at the bottom of the Pacific Ocean where the maximum pressure is roughly 117 MPa . The high pressures experienced by these organisms can cause the normally fluid cell membrane to become waxy and relatively impermeable to nutrients . These organisms have adapted in novel ways to become tolerant of these pressures in order to colonize deep sea habitats . One example , xenophyophores , have been found in the deepest ocean trench , 6.6 miles ( 10,541 meters ) below the surface . Barotolerant bacteria are able to survive at high pressures , but can exist in less extreme environments as well . Obligate barophiles can not survive outside such environments . For example , the Halomonas species Halomonas salaria requires a pressure of 1000 atm ( 100 MPa ) . Most piezophiles grow in darkness and are usually very UV-sensitive ; they lack many mechanisms of DNA repair . |
Planetary_equilibrium_temperature | The planetary equilibrium temperature is a theoretical temperature that a planet would be at when considered simply as if it were a black body being heated only by its parent star . In this model , the presence or absence of an atmosphere ( and therefore any greenhouse effect ) is not considered , and one treats the theoretical black body temperature as if it came from an idealized surface of the planet . Other authors use different names for this concept , such as equivalent blackbody temperature of a planet , or the effective radiation emission temperature of the planet . Similar concepts include the global mean temperature , global radiative equilibrium , and global-mean surface air temperature , which includes the effects of global warming . |
Photovoltaic_system | A photovoltaic system , also PV system or solar power system , is a power system designed to supply usable solar power by means of photovoltaics . It consists of an arrangement of several components , including solar panels to absorb and convert sunlight into electricity , a solar inverter to change the electric current from DC to AC , as well as mounting , cabling and other electrical accessories to set up a working system . It may also use a solar tracking system to improve the system 's overall performance and include an integrated battery solution , as prices for storage devices are expected to decline . Strictly speaking , a solar array only encompasses the ensemble of solar panels , the visible part of the PV system , and does not include all the other hardware , often summarized as balance of system ( BOS ) . Moreover , PV systems convert light directly into electricity and should n't be confused with other technologies , such as concentrated solar power or solar thermal , used for heating and cooling . PV systems range from small , rooftop-mounted or building-integrated systems with capacities from a few to several tens of kilowatts , to large utility-scale power stations of hundreds of megawatts . Nowadays , most PV systems are grid-connected , while off-grid or stand-alone systems only account for a small portion of the market . Operating silently and without any moving parts or environmental emissions , PV systems have developed from being niche market applications into a mature technology used for mainstream electricity generation . A rooftop system recoups the invested energy for its manufacturing and installation within 0.7 to 2 years and produces about 95 percent of net clean renewable energy over a 30-year service lifetime . Due to the exponential growth of photovoltaics , prices for PV systems have rapidly declined in recent years . However , they vary by market and the size of the system . In 2014 , prices for residential 5-kilowatt systems in the United States were around $ 3.29 per watt , while in the highly penetrated German market , prices for rooftop systems of up to 100 kW declined to $ 1.24 per watt . Nowadays , solar PV modules account for less than half of the system 's overall cost , leaving the rest to the remaining BOS-components and to soft costs , which include customer acquisition , permitting , inspection and interconnection , installation labor and financing costs . |
Policy_advocacy | Policy advocacy is defined as active , covert , or inadvertent support of a particular policy or class of policies . Whether it is proper for scientists and other technical experts to act as advocates for their personal policy preferences is contentious . In the scientific community , much of the controversy around policy advocacy involves precisely defining the proper role of science and scientists in the political process . Some scientists choose to act as policy advocates , while others regard such a dichotomous role as inappropriate . Providing technical and scientific information to inform policy deliberations in an objective and relevant way is recognized as a difficult problem in many scientific and technical professions . The challenge and conflicts have been studied for those working as stock analysts in brokerage firms , for medical experts testifying in malpractice trials , for funding officers at international development agencies , and for intelligence analysts within governmental national security agencies . The job of providing accurate , relevant , and policy neutral information is especially challenging if highly controversial policy issues ( such as climate change ) that have a significant scientific component . The use of normative science by scientists is a common method used to subtly advocate for preferred policy choices . |
Phillips_curve | The Phillips curve is a single-equation empirical model , named after William Phillips , describing a historical inverse relationship between rates of unemployment and corresponding rates of inflation that result within an economy . Stated simply , decreased unemployment , ( i.e. , increased levels of employment ) in an economy will correlate with higher rates of inflation . While there is a short run tradeoff between unemployment and inflation , it has not been observed in the long run . In 1968 , Milton Friedman asserted that the Phillips curve was only applicable in the short-run and that in the long-run , inflationary policies will not decrease unemployment . Friedman then correctly predicted that in the 1973 -- 75 recession , both inflation and unemployment would increase . The long-run Phillips curve is now seen as a vertical line at the natural rate of unemployment , where the rate of inflation has no effect on unemployment . Accordingly , the Phillips curve is now seen as too simplistic , with the unemployment rate supplanted by more accurate predictors of inflation based on velocity of money supply measures such as the MZM ( `` money zero maturity '' ) velocity , which is affected by unemployment in the short but not the long term . |
Plant_ecology | Plant ecology is a subdiscipline of ecology which studies the distribution and abundance of plants , the effects of environmental factors upon the abundance of plants , and the interactions among and between plants and other organisms . Examples of these are the distribution of temperate deciduous forests in North America , the effects of drought or flooding upon plant survival , and competition among desert plants for water , or effects of herds of grazing animals upon the composition of grasslands . A global overview of the Earth 's major vegetation types is provided by O.W. Archibold . He recognizes 11 major vegetation types : tropical forests , tropical savannas , arid regions ( deserts ) , Mediterranean ecosystems , temperate forest ecosystems , temperate grasslands , coniferous forests , tundra ( both polar and high mountain ) , terrestrial wetlands , freshwater ecosystems and coastal/marine systems . This breadth of topics shows the complexity of plant ecology , since it includes plants from floating single-celled algae up to large canopy forming trees . One feature that defines plants is photosynthesis . One of the most important aspects of plant ecology is the role plants have played in creating the oxygenated atmosphere of earth , an event that occurred some 2 billion years ago . It can be dated by the deposition of banded iron formations , distinctive sedimentary rocks with large amounts of iron oxide . At the same time , plants began removing carbon dioxide from the atmosphere , thereby initiating the process of controlling Earth 's climate . A long term trend of the Earth has been toward increasing oxygen and decreasing carbon dioxide , and many other events in the Earths history , like the first movement of life onto land , are likely tied to this sequence of events . One of the early classic books on plant ecology was written by J.E. Weaver and F.E. Clements . It talks broadly about plant communities , and particularly the importance of forces like competition and processes like succession . Although some of the terminology is dated , this important book can still often be obtained in used book stores . Plant ecology can also be divided by levels of organization including plant ecophysiology , plant population ecology , community ecology , ecosystem ecology , landscape ecology and biosphere ecology . The study of plants and vegetation is complicated by their form . First , most plants are rooted in the soil , which makes it difficult to observe and measure nutrient uptake and species interactions . Second , plants often reproduce vegetatively , that is asexually , in a way that makes it difficult to distinguish individual plants . Indeed , the very concept of an individual is doubtful , since even a tree may be regarded as a large collection of linked meristems . Hence , plant ecology and animal ecology have different styles of approach to problems that involve processes like reproduction , dispersal and mutualism . Some plant ecologists have placed considerable emphasis upon trying to treat plant populations as if they were animal populations , focusing on population ecology . Many other ecologists believe that while it is useful to draw upon population ecology to solve certain scientific problems , plants demand that ecologists work with multiple perspectives , appropriate to the problem , the scale and the situation . |
Pisa_(river) | The Pisa ( -LSB- ˈpisa -RSB- ; Pissek ) is a river in north-eastern Poland with a length of 80.4 km . It belongs to the Masurian Lake District of the Warmian-Masurian Voivodeship . The Pisa river flows from Lake Roś near the town of Pisz , and is a tributary of the Narew , connecting the Lakeland region with the Vistula . The Pisz Forest borders the river on its west bank . The name Pisa comes from the ancient Prussian language word `` pisa '' , meaning `` swamp . '' The name dates back to the Galindae tribe who lived in the area before the arrival of the Teutonic Knights , who referred to the Pisa as the Galinde . In November 1982 the Polish Centre for Research and Control of the Environment ( Ośrodek Badań i Kontroli Środowiska ) in Łomża included Pisa in the first class category for purity of its water . Pisa is a picturesque lowland river with its most scenic stretches around its upper and lower reaches . In the middle part , the river flows through boggy meadows . Along its entire length Pisa is navigable . Considerably deep ( 1 -- 1.8 m ) , it has the shallowest depth at its mouth , at the Narew river . Pisa is strongly meandering with the average descent of 32 cm per kilometer . Canoeing down the river from Pisz to Nowogród takes about 4 -- 5 days . |
Pollution_in_the_Arctic_Ocean | Pollution in the Arctic Ocean is primarily the result of economic activities carried out on land -- such as industrial development in the Arctic region , northern rivers , and the effects of military activities , particularly nuclear activity -- as well as the influx of pollutants from other regions of the world . However , the Arctic Ocean remains relatively clean compared to other marine regions of the world . Economic activity in the Arctic seas is not the only source of pollution . The growing presence of military weapons systems in the region raises concerns of increased pollution . Management of specific risks of marine pollution in the Arctic is governed primarily by national legislation in coastal states , although these take existing international standards into account . Bilateral agreements exist between Arctic states on cooperation in the prevention of marine pollution in the Arctic seas and immediate responses in case of oil spills . Nevertheless , there is no legal framework relating to weapons and other military presence . The first steps in this direction have already been made . After signing the 2010 Treaty on Maritime Delimitation of the continental shelf in the Barents Sea and the Arctic Ocean , Russia and Norway began bilateral consultations on the harmonization of national environmental standards used for the exploration and development of the mineral resources of the shelf . The parties came to an agreement to make a comparative analysis of national legislation and to identify differences concerning measures for preventing the pollution of the environment . A recent report published by the International Council on Clean Transportation ( ICCT ) suggested that the reduction of the polar ice caps and the projected increase in shipping activity in the region could have a severe impact on the levels of pollution experienced across the entire Arctic region but notes that a shift to cleaner sulphur-based fuel could resolve the issue . |
Pinniped | Pinnipeds ( -LSB- ˈpɪnᵻˌpɛdz -RSB- ) ( from Latin pinna `` fin '' and pes , pedis `` foot '' ) , commonly known as seals , are a widely distributed and diverse clade of carnivorous , fin-footed , semiaquatic marine mammals . They comprise the extant families Odobenidae ( whose only living member is the walrus ) , Otariidae ( the eared seals : sea lions and fur seals ) , and Phocidae ( the earless seals , or true seals ) . There are 33 extant species of pinnipeds , and more than 50 extinct species have been described from fossils . While seals were historically thought to have descended from two ancestral lines , molecular evidence supports them as a monophyletic lineage ( descended from one ancestral line ) . Pinnipeds belong to the order Carnivora and their closest living relatives are bears and musteloids ( weasels , raccoons , skunks , and red pandas ) , having diverged about 50 million years ago . Seals range in size from the 1 m and 45 kg Baikal seal to the 5 m and 3200 kg southern elephant seal , which is also the largest carnivoran . Several species exhibit sexual dimorphism . They have streamlined bodies and four limbs that are modified into flippers . Though not as fast in the water as dolphins , seals are more flexible and agile . Otariids use their front limbs primarily to propel themselves through the water , while phocids and walruses use their hind limbs . Otariids and walruses have hind limbs that can be pulled under the body and used as legs on land . By comparison , terrestrial locomotion by phocids is more cumbersome . Otariids have visible external ears , while phocids and walruses lack these . Pinnipeds have well-developed senses -- their eyesight and hearing are adapted for both air and water , and they have an advanced tactile system in their whiskers or vibrissae . Some species are well adapted for diving to great depths . They have a layer of fat , or blubber , under the skin to keep warm in the cold water , and , other than the walrus , all species are covered in fur . Although pinnipeds are widespread , most species prefer the colder waters of the Northern and Southern Hemispheres . They spend most of their lives in the water , but come ashore to mate , give birth , molt or escape from predators , like sharks and killer whales . They feed largely on fish and marine invertebrates ; but a few , like the leopard seal , feed on large vertebrates , such as penguins and other seals . Walruses are specialized for feeding on bottom-dwelling mollusks . Male pinnipeds typically mate with more than one female ( polygyny ) , although the degree of polygyny varies with the species . The males of land-breeding species tend to mate with a greater number of females than those of ice - or water-breeding species . Male pinniped strategies for reproductive success vary between defending females , defending territories that attract females and performing ritual displays or lek mating . Pups are typically born in the spring and summer months and females bear almost all the responsibility for raising them . Mothers of some species fast and nurse their young for a relatively short period of time while others take foraging trips at sea between nursing bouts . Walruses are known to nurse their young while at sea . Seals produce a number of vocalizations , notably the barks of California sea lions , the gong-like calls of walruses and the complex songs of Weddell seals . The meat , blubber and fur coats of pinnipeds have traditionally been used by indigenous peoples of the Arctic . Seals have been depicted in various cultures worldwide . They are commonly kept in captivity and are even sometimes trained to perform tricks and tasks . Once relentlessly hunted by commercial industries for their products , seals and walruses are now protected by international law . The Japanese sea lion and the Caribbean monk seal have become extinct in the past century , while the Mediterranean monk seal and Hawaiian monk seal are ranked endangered by the International Union for Conservation of Nature . Besides hunting , pinnipeds also face threats from accidental trapping , marine pollution , and conflicts with local people . |
Philosophical_skepticism | For a general discussion of skepticism , see Skepticism . Philosophical skepticism ( UK spelling scepticism ; from Greek σκέψις skepsis '' , `` inquiry '' ) is both a philosophical school of thought and a method that questions the possibility of certainty in knowledge . It is generally agreed that knowledge requires justification . It is not enough to have a true belief : one must also have good reasons for that belief . Skeptics claim that it is not possible to have an adequate justification . Skepticism is not a single position but covers a range of different positions . In the ancient world there were two main skeptical traditions . Academic skepticism took the dogmatic position that knowledge was not possible ; Pyrrhonian skeptics refused to take a dogmatic position on any issue -- including skepticism . Radical skepticism ends in the paradoxical claim that one can not know anything -- including that one can not know about knowing anything . Skepticism can be classified according to its scope . Local skepticism involves being skeptical about particular areas of knowledge , e.g. moral skepticism , skepticism about the external world , or skepticism about other minds , whereas global skepticism is skeptical about the possibility of any knowledge at all . Skepticism can also be classified according to its method . In the Western tradition there are two basic approaches to skepticism . Cartesian skepticism -- named somewhat misleadingly after René Descartes , who was not a skeptic but used some traditional skeptical arguments in his Meditations to help establish his rationalist approach to knowledge -- attempts to show that any proposed knowledge claim can be doubted . Agrippan skepticism focuses on the process of justification rather than the possibility of doubt . According to this view there are three ways in which one might attempt to justify a claim but none of them are adequate : one can keep on providing further justification but this leads to an infinite regress ; one can stop at a dogmatic assertion ; or one can argue in circular reasoning , never reaching a viable conclusion . Philosophical skepticism is distinguished from methodological skepticism in that philosophical skepticism is an approach that questions the possibility of certainty in knowledge , whereas methodological skepticism is an approach that subjects all knowledge claims to scrutiny with the goal of sorting out true from false claims . |
Policy_Review | Policy Review was a conservative journal from 1977 to 2013 . |
Philosophy_of_statistics | The philosophy of statistics involves the meaning , justification , utility , use and abuse of statistics and its methodology , and ethical and epistemological issues involved in the consideration of choice and interpretation of data and methods of statistics . Foundations of statistics involves issues in theoretical statistics , its goals and optimization methods to meet these goals , parametric assumptions or lack thereof considered in nonparametric statistics , model selection for the underlying probability distribution , and interpretation of the meaning of inferences made using statistics , related to the philosophy of probability and the philosophy of science . Discussion of the selection of the goals and the meaning of optimization , in foundations of statistics , are the subject of the philosophy of statistics . Selection of distribution models , and of the means of selection , is the subject of the philosophy of statistics , whereas the mathematics of optimization is the subject of nonparametric statistics . David Cox makes the point that any kind of interpretation of evidence is in fact a statistical model , although it is known through Ian Hacking 's work that many are ignorant of this subtlety . Issues arise involving sample size , such as cost and efficiency , are common , such as in polling and pharmaceutical research . Extra-mathematical considerations in the design of experiments and accommodating these issues arise in most actual experiments . The motivation and justification of data analysis and experimental design , as part of the scientific method are considered . Distinctions between induction and logical deduction relevant to inferences from data and evidence arise , such as when frequentist interpretations are compared with degrees of certainty derived from Bayesian inference . However , the difference between induction and ordinary reasoning is not generally appreciated . Leo Breiman exposed the diversity of thinking in his article on ` The Two Cultures ' , making the point that statistics has several kinds of inference to make , modelling and prediction amongst them . Issues in the philosophy of statistics arise throughout the history of statistics . Causality considerations arise with interpretations of , and definitions of , correlation , and in the theory of measurement . Objectivity in statistics is often confused with truth whereas it is better understood as replicability , which then needs to be defined in the particular case . Theodore Porter develops this as being the path pursued when trust has evaporated , being replaced with criteria . Ethics associated with epistemology and medical applications arise from potential abuse of statistics , such as selection of method or transformations of the data to arrive at different probability conclusions for the same data set . For example , the meaning of applications of a statistical inference to a single person , such as one single cancer patient , when there is no frequentist interpretation for that patient to adopt . Campaigns for statistical literacy must wrestle with the problem that most interesting questions around individual risk are very difficult to determine or interpret , even with the computer power currently available . |
Permafrost | In geology , permafrost is ground , including rock or ( cryotic ) soil , at or below the freezing point of water 0 C for two or more years . Most permafrost is located in high latitudes ( in and around the Arctic and Antarctic regions ) , but alpine permafrost may exist at high altitudes in much lower latitudes . Ground ice is not always present , as may be in the case of nonporous bedrock , but it frequently occurs and it may be in amounts exceeding the potential hydraulic saturation of the ground material . Permafrost accounts for 0.022 % of total water on earth and exists in 24 % of exposed land in the Northern Hemisphere . It also occurs subsea on the continental shelves of the continents surrounding the Arctic Ocean , portions of which were exposed during the last glacial period , with global weather implications . A global temperature rise of 1.5 C-change above current levels would be enough to start the thawing of permafrost in Siberia , according to one group of scientists . |
Platinum | Platinum is a chemical element with symbol Pt and atomic number 78 . It is a dense , malleable , ductile , highly unreactive , precious , gray-white transition metal . Its name is derived from the Spanish term platina , translated into `` little silver '' . Platinum is the most precious and rarest metal on the earth ; it is 30 times more rare than gold . Platinum is a member of the platinum group of elements and group 10 of the periodic table of elements . It has six naturally occurring isotopes . It is one of the rarer elements in Earth 's crust with an average abundance of approximately 5 μg / kg . It occurs in some nickel and copper ores along with some native deposits , mostly in South Africa , which accounts for 80 % of the world production . Because of its scarcity in Earth 's crust , only a few hundred tonnes are produced annually , and given its important uses , it is highly valuable and is a major precious metal commodity . Platinum is one of the least reactive metals . It has remarkable resistance to corrosion , even at high temperatures , and is therefore considered a noble metal . Consequently , platinum is often found chemically uncombined as native platinum . Because it occurs naturally in the alluvial sands of various rivers , it was first used by pre-Columbian South American natives to produce artifacts . It was referenced in European writings as early as 16th century , but it was not until Antonio de Ulloa published a report on a new metal of Colombian origin in 1748 that it began to be investigated by scientists . Platinum is used in catalytic converters , laboratory equipment , electrical contacts and electrodes , platinum resistance thermometers , dentistry equipment , and jewelry . Being a heavy metal , it leads to health issues upon exposure to its salts ; but due to its corrosion resistance , metallic platinum has not been linked to adverse health effects . Compounds containing platinum , such as cisplatin , oxaliplatin and carboplatin , are applied in chemotherapy against certain types of cancer . |
Planetary_boundaries | Planetary boundaries is the central concept in an Earth system framework proposed by a group of Earth system and environmental scientists led by Johan Rockström from the Stockholm Resilience Centre and Will Steffen from the Australian National University . In 2009 , the group proposed a framework of `` planetary boundaries '' designed to define a `` safe operating space for humanity '' for the international community , including governments at all levels , international organizations , civil society , the scientific community and the private sector , as a precondition for sustainable development . This framework is based on scientific research that indicates that since the Industrial Revolution , human actions have gradually become the main driver of global environmental change . The scientists assert that once human activity has passed certain thresholds or tipping points , defined as `` planetary boundaries '' , there is a risk of `` irreversible and abrupt environmental change '' . The group identified nine Earth system processes which have boundaries that , to the extent that they are not crossed , mark the safe zone for the planet . However , because of human activities some of these dangerous boundaries have already been crossed , while others are in imminent danger of being crossed . Rockström and Steffen collaborated with 26 leading academics , including Nobel laureate Paul Crutzen , Goddard Institute for Space Studies climate scientist James Hansen and the German Chancellor 's chief climate adviser Hans Joachim Schellnhuber . The group identified nine `` planetary life support systems '' essential for human survival , and attempted to quantify just how far seven of these systems have been pushed already . They then estimated how much further we can go before our own survival is threatened ; beyond these boundaries there is a risk of `` irreversible and abrupt environmental change '' which could make Earth less habitable . Estimates indicate that three of these boundaries -- climate change , biodiversity loss , and the biogeochemical flow boundary -- appear to have been crossed . The boundaries are `` rough , first estimates only , surrounded by large uncertainties and knowledge gaps '' that interact in ways that are complex and not well understood . Boundaries can help identify where there is room and define a `` safe space for human development '' , which is an improvement on approaches which aim at just minimizing human impacts on the planet . The 2009 report was presented to the General Assembly of the Club of Rome in Amsterdam . An edited summary of the report was subsequently published as the featured article in a special edition of Nature . Nature also published critical commentary from leading academics they invited to comment on each of the seven planetary boundaries which had been quantified , including comments from Nobel laureate Mario J. Molina and biologist Cristián Samper . In 2015 , a second paper was published in Science updating the Planetary Boundaries concept . The findings were presented at the World Economic Forum in Davos , January 2015 . |
Physical_model | Physical model ( most commonly referred to simply as a model but in this context distinguished from a conceptual model ) is a smaller or larger physical copy of an object . The object being modelled may be small ( for example , an atom ) or large ( for example , the Solar System ) . The geometry of the model and the object it represents are often similar in the sense that one is a rescaling of the other ; in such cases the scale is an important characteristic . However , in many cases the similarity is only approximate or even intentionally distorted . Sometimes the distortion is systematic with e.g. a fixed scale horizontally and a larger fixed scale vertically when modelling topography of a large area ( as opposed to a model of a smaller mountain region , which may well use the same scale horizontally and vertically , and show the true slopes ) . Physical models allow visualization , from examining the model , of information about the thing the model represents . A model can be a physical object such as an architectural model of a building . Uses of an architectural model include visualization of internal relationships within the structure or external relationships of the structure to the environment . Other uses of models in this sense are as toys . Instrumented physical models are the most effective way of investigating fluid flows such as around hydraulic structures . These models are scaled in terms of both geometry and important forces , for example using Froude number or Reynolds number scaling ( see Similitude ( model ) ) . A physical model of something large is usually smaller , and of something very small is larger . A physical model of something that can move , like a vehicle or machine , may be completely static , or have parts that can be moved manually , or be powered . A physical model may show inner parts that are normally not visible . The purpose of a physical model on a smaller scale may be to have a better overview , for testing purposes , as hobby or toy . The purpose of a physical model on a larger scale may be to see the structure of things that are normally too small to see properly or to see at all , for example a model of an insect or of a molecule . A physical model of an animal shows the animals physical composition without it walking or flying away , and without danger , and if the real animal is not available . A soft model of an animal is popular among children and some adults as cuddly toy.some models can be used in different ways as of like prototypes for cars . A model of a person may e.g. be a doll , a statue , and in fiction a robotic humanoid , e.g. the mechas in the movie A.I. . A model is a 3D alternative for a 2D representation such as a drawing or photograph , or in the case of a globe , a 3D , undistorted alternative for a flat world map . |
Pneumonia_front | The term Pneumonia front , first coined by Milwaukee Weather Bureau Office in the 1960s , is used to describe a rare meteorological phenomenon observed on the western Lake Michigan , USA , shoreline during the warm season . These fronts are defined as lake-modified synoptic scale cold fronts that result in one-hour temperature drops of 16 ° F ( 8.9 ° C ) or greater . They do not necessarily have to be synoptic , or large scale , cold fronts . Very often in the Spring to early summer the temperature difference between the cold lake waters and the warmer air over land can be as much as 35-40 ° F. Under weak prevailing winds , a density current can often develop in the form of a lake breeze that moves from that water to the adjacent shoreline and several miles inland . This `` lake-breeze cold front '' can drop temperature in places like Chicago , Milwaukee and Green Bay significantly as they cross the area . There has been many a Spring day at Wrigley Field that surprises people who may have travelled from an inland location toward the shore to take in an afternoon game , only to feel the effects of the `` pneumonia front '' as that cold blast of air comes through . The following are eighteen occurrences of a lake modified synoptic scale cold front or `` pneumonia front '' . |
Permian | The Permian is a geologic period and system which spans 46.7 million years from the end of the Carboniferous Period million years ago ( Mya ) , to the beginning of the Triassic Period 252.2 Mya . It is the last period of the Paleozoic Era ; the following Triassic Period belongs to the Mesozoic Era . The concept of the Permian was introduced in 1841 by geologist Sir Roderick Murchison , who named it after the city of Perm . The Permian witnessed the diversification of the early amniotes into the ancestral groups of the mammals , turtles , lepidosaurs , and archosaurs . The world at the time was dominated by two continents known as Pangaea and Siberia , surrounded by a global ocean called Panthalassa . The Carboniferous rainforest collapse left behind vast regions of desert within the continental interior . Amniotes , who could better cope with these drier conditions , rose to dominance in place of their amphibian ancestors . The Permian ( along with the Paleozoic ) ended with the Permian -- Triassic extinction event , the largest mass extinction in Earth 's history , in which nearly 90 % of marine species and 70 % of terrestrial species died out . It would take well into the Triassic for life to recover from this catastrophe . Recovery from the Permian-Triassic extinction event was protracted ; on land , ecosystems took 30 million years to recover . |
Plug-in_hybrids_in_California | California has been a leader in the promotion of plug-in hybrids ( PHEVs ) , and plug-in electric vehicles ( PEVs ) in general , including all-electric vehicles ( BEVs ) and other zero-emission vehicles . California is the largest U.S. car market and also the leading plug-in electric vehicle market in the country with over 200,000 plug-in electric vehicles registered by March 2016 , representing 47 % of all plug-in cars sold in the American market since 2008 , while the state represents about 10 % of all new car sales in the country . The Governor of California , Jerry Brown , issued an executive order in March 2012 that established the goal of getting 1.5 million zero-emission vehicles ( ZEVs ) on California roads by 2025 . In September 2014 , the Charge Ahead California Initiative set the additional goal to have at least 1 million zero-emission vehicles and near-zero-emission vehicles in California by January 1 , 2023 . As part of the state 's government incentives , in addition to the existing federal tax credit , plug-in hybrids are eligible for a purchase rebate . Also applicants that purchase or lease a PHEV meeting California 's Enhanced Advanced Technology Partial Zero Emission Vehicle ( Enhanced AT PZEV ) are entitled to a green clean air sticker that allows the vehicle to be operated by a single occupant in California 's carpool or high-occupancy vehicle lanes ( HOV ) . The limit to the number of green stickers was raised several times , and in September 2016 , the cap to the number of Green Clean Air Vehicle Decals was removed . The expiration date for the green stickers is January 1 , 2019 . , a total of 118,028 plug-in hybrids have been registered in California since 2010 . The market share of PHEVs in the state climbed from 0.1 % of new car sales in 2011 to 0.9 % in 2012 to 1.2 % in 2013 , and reached 1.6 % during 2014 . During 2015 the plug-in hybrid segment share fell to 1.4 % , and then increased to 1.5 % during the first nine months of 2016 . As of early June 2015 , a total of 45,829 plug-in hybrid owners have benefited with the state 's Clean Vehicle Rebate Project ( CVRP ) , representing 42.5 % of all clean vehicle rebates issued since January 2011 . By early March 2014 , and based on CVRP 's databse , the counties with the highest adoption of plug-in hybrids in the state are Los Angeles ( 8,015 ) , Orange ( 3,622 ) and Santa Clara ( 3,080 ) . , California leads the country with 5,749 public charging points , representing 26.7 % of the U.S total . |
Policy_Uncertainty | Policy Uncertainty is a broad class of economic risk where the future path of government policy is uncertain , raising risk premia and leading businesses and individuals to delay spending and investment until this uncertainty has been resolved . Policy uncertainty may refer to uncertainty about monetary or fiscal policy , the tax or regulatory regime , or uncertainty over electoral outcomes that will influence political leadership . |
Polar_High | The polar highs are areas of high atmospheric pressure around the north and south poles ; the north polar high being the stronger one because land gains and loses heat more effectively than sea . The cold temperatures in the polar regions cause air to descend to create the high pressure ( a process called subsidence ) , just as the warm temperatures around the equator cause air to rise to create the low pressure intertropical convergence zone . Rising air also occurs along bands of low pressure situated just below the polar highs around the 50th parallels of latitude . These extratropical convergence zones are occupied by the polar fronts where air masses of polar origin meet and clash with those of tropical or subtropical origin . This convergence of rising air completes the vertical cycle around the polar cell in each latitudinal hemisphere . Closely related to this concept is the polar vortex . Surface temperatures under the polar highs are the coldest on Earth , with no month having an average temperature above freezing . Regions under the polar high also experience very low levels of precipitation , which leads them to be known as `` polar deserts '' . Air flows outwards from the poles to create the polar easterlies in the arctic and antarctic areas . |
Polar_see-saw | The polar see-saw ( also : Bipolar seesaw ) is the phenomenon that temperature changes in the northern and southern hemispheres may be out of phase . The theory ( or hypothesis ) states that large changes , f.e. when the glaciers are intensely growing or depleting , in the formation of ocean bottom water in both poles take a long time to exert their effect in the other hemisphere . Estimates of the period of delay vary , one typical estimate is 1500 years . This is usually studied in the context of ice-cores taken from Antarctica and Greenland . |
Polar_vortex | A polar vortex is an upper level low-pressure area lying near the Earth 's pole . There are two polar vortices in the Earth 's atmosphere , which overlie the North , and South Poles . Each polar vortex is a persistent , large-scale , low pressure zone that rotates counter-clockwise at the North Pole ( called a cyclone ) , and clockwise at the South Pole . The bases of the two polar vortices are located in the middle and upper troposphere and extend into the stratosphere . Beneath that lies a large mass of cold , dense arctic air . The vortices weaken and strengthen from year to year . When the vortex of the arctic is strong it is well defined , there is a single vortex and the arctic air is well contained ; when weaker , which it generally is , it will break into two or more vortices ; when very weak , the flow of arctic air becomes more disorganized and masses of cold arctic air can push equatorward , bringing with it a rapid and sharp temperature drop . The interface between the cold dry air mass of the pole and the warm moist air mass further south defines the location of the polar front . The polar front is centered , roughly at 60 ° latitude . A polar vortex strengthens in the winter and weakens in the summer due to its dependence on the temperature difference between the equator and the poles . The vortices span less than 1,000 kilometers ( 620 miles ) in diameter within which they rotate counter-clockwise in the Northern Hemisphere , and in a clockwise fashion in the Southern Hemisphere . As with other cyclones , their rotation is driven by the Coriolis effect . When the polar vortex is strong , there is a single vortex with a jet stream that is `` well constrained '' near the polar front . When the northern vortex weakens , it separates into two or more vortices , the strongest of which are near Baffin Island , Canada and the other over northeast Siberia . The Antarctic vortex of the Southern Hemisphere is a single low pressure zone that is found near the edge of the Ross ice shelf near 160 west longitude . When the polar vortex is strong , the mid-latitude Westerlies ( winds at the surface level between 30 ° and 60 ° latitude from the west ) increase in strength and are persistent . When the polar vortex is weak , high pressure zones of the mid latitudes may push poleward , moving the polar vortex , jet stream , and polar front equatorward . The jet stream is seen to `` buckle '' and deviate south . This rapidly brings cold dry air into contact with the warm , moist air of the mid latitudes , resulting in a rapid and dramatic change of weather known as a `` cold snap '' . Ozone depletion occurs within the polar vortices -- particularly over the Southern Hemisphere -- reaching a maximum depletion in the spring . |
Polar_drift | Polar drift is a geological phenomenon caused by variations in the flow of molten iron in Earth 's outer core , resulting in changes in the orientation of Earth 's magnetic field , and hence the position of the magnetic north and south poles . The North Magnetic Pole is approximately 965 kilometers from the geographic north pole . The pole drifts considerably each day , and since 2007 it moves about 55 to 60 km per year as a result of this phenomenon . The South Magnetic Pole is constantly shifting due to changes in the Earth 's magnetic field . As of 2005 it was calculated to lie at , placing it off the coast of Antarctica , between Adelie Land and Wilkes Land . In 2015 it lay at ( est ) . That point lies outside the Antarctic Circle and it is moving northwest by about 10 to 15 kilometers per year . Its current distance from the actual Geographic South Pole is approximately 2860 km . The nearest permanent science station is Dumont d'Urville Station . Wilkes Land contains a large gravitational mass concentration . -RCB- | | ( 2004 est ) | | ( 2007 ) | | ( 2015 ) | - | South Magnetic Pole | | ( 1998 ) | | ( 2004 est ) | | ( 2007 ) | | ( 2015 ) | -RCB- |
Piscivore | A piscivore -LSB- ˈpɪsᵻvɔər -RSB- is a carnivorous animal which eats primarily fish . Piscivorous is equivalent to the Greek-derived word ichthyophagous . Fish were the diet of early tetrapods ( amphibians ) ; insectivory came next , then in time , reptiles added herbivory . Some animals , such as the sea lion and alligator , are not completely piscivorous , often preying on aquatic invertebrates or land animals in addition to fish , while others , such as the bulldog bat and gharial , are strictly dependent on fish for food . Humans can live on fish-based diets as can their carnivorous domesticated pets , such as dogs and cats . The name `` piscivore '' is derived from the Latin word for fish , piscis #Latin . Some creatures , including cnidarians , octopuses , squid , spiders , sharks , cetaceans , grizzly bears , jaguars , wolves , snakes , turtles , and sea gulls , may have fish as significant if not dominant portions of their diets . The ecological effects of piscivores can extend to other food chains . In a study of cutthroat trout stocking , researchers found that the addition of this piscivore can have noticeable effects on non-aquatic organisms , in this case bats feeding on insects emerging from the water with the trout . There exists classifications of primary and secondary piscivores . Primary piscivores , also known as `` specialists '' , shift to this habit in the first few months of their lives . Secondary piscivores will move to eating primarily fish later in their lifetime . It is hypothesized that the secondary piscivores ' diet change is due to an adaptation to maintain efficiency in their use of energy while growing . |
Planck_(spacecraft) | Planck was a space observatory operated by the European Space Agency ( ESA ) from 2009 to 2013 , which mapped the anisotropies of the cosmic microwave background ( CMB ) at microwave and infra-red frequencies , with high sensitivity and small angular resolution . The mission substantially improved upon observations made by the NASA Wilkinson Microwave Anisotropy Probe ( WMAP ) . Planck provided a major source of information relevant to several cosmological and astrophysical issues , such as testing theories of the early Universe and the origin of cosmic structure ; as of 2013 it has provided the most accurate measurements of several key cosmological parameters , including the average density of ordinary matter and dark matter in the Universe . The project was started around 1996 and was initially called COBRAS/SAMBA : the Cosmic Background Radiation Anisotropy Satellite/Satellite for Measurement of Background Anisotropies . It was later renamed in honour of the German physicist Max Planck ( 1858 -- 1947 ) , who derived the formula for black-body radiation . Built at the Cannes Mandelieu Space Center by Thales Alenia Space , and created as a medium-sized mission for ESA 's Horizon 2000 long-term scientific programme , Planck was launched in May 2009 , reaching the Earth/Sun by July , and by February 2010 had successfully started a second all-sky survey . On 21 March 2013 , the mission 's first all-sky map of the cosmic microwave background was released , with an expanded release including polarization data in February 2015 . At the end of its mission Planck was put into a heliocentric orbit and passivated to prevent it from endangering any future missions . The final deactivation command was sent to Planck in October 2013 . |
Polar_front | In meteorology , the polar front is the boundary between the polar cell and the Ferrel cell in each hemisphere . At this boundary a sharp gradient in temperature occurs between these two air masses , each at very different temperatures . The polar front arises as a result of cold polar air meeting warm tropical air . It is a stationary front as the air masses are not moving against each other . Off the coast of eastern North America , especially in winter , there is a sharp temperature gradient between the snow-covered land and the warm offshore currents . The polar front theory says that mid-latitude cyclones form on boundaries between warm and cold air . In winter , the polar front shifts towards the Equator , whereas high pressure systems dominate more in the summer . |
Phenology | Phenology is the study of periodic plant and animal life cycle events and how these are influenced by seasonal and interannual variations in climate , as well as habitat factors ( such as elevation ) . The word , coined by the Belgian botanist Charles Morren around 1849 , is derived from the Greek φαίνω ( phainō ) , `` to show , to bring to light , make to appear '' + λόγος ( logos ) , amongst others `` study , discourse , reasoning '' and indicates that phenology has been principally concerned with the dates of first occurrence of biological events in their annual cycle . Examples include the date of emergence of leaves and flowers , the first flight of butterflies and the first appearance of migratory birds , the date of leaf colouring and fall in deciduous trees , the dates of egg-laying of birds and amphibia , or the timing of the developmental cycles of temperate-zone honey bee colonies . In the scientific literature on ecology , the term is used more generally to indicate the time frame for any seasonal biological phenomena , including the dates of last appearance ( e.g. , the seasonal phenology of a species may be from April through September ) . Because many such phenomena are very sensitive to small variations in climate , especially to temperature , phenological records can be a useful proxy for temperature in historical climatology , especially in the study of climate change and global warming . For example , viticultural records of grape harvests in Europe have been used to reconstruct a record of summer growing season temperatures going back more than 500 years . In addition to providing a longer historical baseline than instrumental measurements , phenological observations provide high temporal resolution of ongoing changes related to global warming . |
Petroleum_seep | A petroleum seep is a place where natural liquid or gaseous hydrocarbons escape to the earth 's atmosphere and surface , normally under low pressure or flow . Seeps generally occur above either terrestrial or offshore petroleum accumulation structures . The hydrocarbons may escape along geological layers , or across them through fractures and fissures in the rock , or directly from an outcrop of oil-bearing rock . Petroleum seeps are quite common in many areas of the world , and have been exploited by mankind since paleolithic times . Natural products associated with these seeps include bitumen , pitch , asphalt and tar . In locations where seeps of natural gas are sufficiently large , natural `` eternal flames '' often persist . The occurrence of surface petroleum was often included in location names that developed ; these locations are also associated with early oil and gas exploitation as well as scientific and technological developments , which have grown into the petroleum industry . |
Pingo | A pingo , also called a hydrolaccolith , is a mound of earth-covered ice found in the Arctic and subarctic that can reach up to 70 m in height and up to 600 m in diameter . The term originated as the Inuvialuktun word for a small hill . The plural form is `` pingos '' . A pingo is a periglacial landform , which is defined as a nonglacial landform or process linked to colder climates . `` Periglacial '' suggests an environment located on the margin of past glaciers . However , freeze and thaw cycles influence landscapes outside areas of past glaciation . Therefore , periglacial environments are anywhere that freezing and thawing modify the landscape in a significant manner . They are essentially formed by ground ice which develops during the winter months as temperatures fall . |
Phreatic_eruption | A phreatic eruption , also called a phreatic explosion , ultravulcanian eruption or steam-blast eruption , occurs when magma heats ground or surface water . The extreme temperature of the magma ( anywhere from 500 to ) causes near-instantaneous evaporation to steam , resulting in an explosion of steam , water , ash , rock , and volcanic bombs . At Mount St. Helens , hundreds of steam explosions preceded a 1980 plinian eruption of the volcano . A less intense geothermal event may result in a mud volcano . Phreatic eruptions typically include steam and rock fragments ; the inclusion of lava is unusual . The temperature of the fragments can range from cold to incandescent . If molten magma is included , it is classified as a phreatomagmatic eruption . These eruptions occasionally create broad , low-relief craters called maars . Phreatic explosions can be accompanied by carbon dioxide or hydrogen sulfide gas emissions . The former can asphyxiate at sufficient concentration ; the latter is a broad spectrum poison . A 1979 phreatic eruption on the island of Java killed 140 people , most of whom were overcome by poisonous gases . Phreatic eruptions are classed as volcanic eruptions because a phreatic eruption could bring juvenile material to the surface . It is believed that the 1883 eruption of Krakatoa , which obliterated most of the volcanic island and created the loudest sound in recorded history , was a phreatic event . Kilauea , in Hawaii , has a long record of phreatic explosions ; a 1924 phreatic eruption hurled rocks estimated at eight tons up to a distance of one kilometer . Additional examples are the 1963 -- 65 eruption of Surtsey , the 1965 eruption of Taal Volcano , the 1982 Mount Tarumae eruption , the 2014 eruption of Mount Ontake and on May 7 , 2013 , at 8 a.m. ( PST ) Mayon Volcano produced a surprise phreatic eruption lasting 73 seconds . |
Plantation_economy | A plantation economy is an economy based on agricultural mass production , usually of a few commodity crops grown on large farms called plantations . Plantation economies rely on the export of cash crops as a source of income . Prominent plantation crops included cotton , rubber , sugar cane , tobacco , figs , rice , kapok , sisal , and species in the genus Indigofera , used to produce indigo dye . The longer a crop 's harvest period , the more efficient plantations become . Economies of scale are also achieved when the distance to market is long . Plantation crops usually need processing immediately after harvesting . Sugarcane , tea , sisal , and palm oil are most suited to plantations , while coconuts , rubber , and cotton are suitable to a lesser extent . |
Polar_ice_cap | A polar ice cap or polar cap is a high-latitude region of a planet , dwarf planet , or natural satellite that is covered in ice . There are no requirements with respect to size or composition for a body of ice to be termed a polar ice cap , nor any geological requirement for it to be over land ; only that it must be a body of solid phase matter in the polar region . This causes the term `` polar ice cap '' to be something of a misnomer , as the term ice cap itself is applied more narrowly to bodies that are over land , and cover less than 50,000 km ² : larger bodies are referred to as ice sheets . The composition of the ice will vary . For example , Earth 's polar caps are mainly water ice , whereas Mars 's polar ice caps are a mixture of solid carbon dioxide and water ice . Polar ice caps form because high-latitude regions receive less energy in the form of solar radiation from the Sun than equatorial regions , resulting in lower surface temperatures . Earth 's polar caps have changed dramatically over the last 12,000 years . Seasonal variations of the ice caps takes place due to varied solar energy absorption as the planet or moon revolves around the Sun . Additionally , in geologic time scales , the ice caps may grow or shrink due to climate variation . |
Petroleum_industry | The petroleum industry includes the global processes of exploration , extraction , refining , transporting ( often by oil tankers and pipelines ) , and marketing of petroleum products . The largest volume products of the industry are fuel oil and gasoline ( petrol ) . Petroleum ( oil ) is also the raw material for many chemical products , including pharmaceuticals , solvents , fertilizers , pesticides , synthetic fragrances , and plastics . The industry is usually divided into three major components : upstream , midstream and downstream . Midstream operations are usually included in the downstream category . Petroleum is vital to many industries , and is of importance to the maintenance of industrial civilization in its current configuration , and thus is a critical concern for many nations . Oil accounts for a large percentage of the world 's energy consumption , ranging from a low of 32 % for Europe and Asia , to a high of 53 % for the Middle East . Other geographic regions ' consumption patterns are as follows : South and Central America ( 44 % ) , Africa ( 41 % ) , and North America ( 40 % ) . The world consumes 30 billion barrels ( 4.8 km ³ ) of oil per year , with developed nations being the largest consumers . The United States consumed 25 % of the oil produced in 2007 . The production , distribution , refining , and retailing of petroleum taken as a whole represents the world 's largest industry in terms of dollar value . Governments such as the United States government provide a heavy public subsidy to petroleum companies , with major tax breaks at virtually every stage of oil exploration and extraction , including the costs of oil field leases and drilling equipment . |
Petroleum_industry_in_China | The impact of the petroleum industry in China has been increasing globally as China is the fourth-greatest oil producer in the world . China imported a record 6.7 m barrels a day ( b/d ) of oil in 2015 and forecasted `` to overtake the U.S. as the world 's biggest crude importer in 2016 '' According to the Energy Information Administration ( EIA ) China first became the `` world 's largest net importer of petroleum and other liquids '' by the end of 2013 . |
Plain | In geography , a plain is a flat , sweeping landmass that generally does not change much in elevation . Plains occur as lowlands along the bottoms of valleys or on the doorsteps of mountains , as coastal plains , and as plateaus or uplands . In a valley , a plain is enclosed on two sides but in other cases a plain may be delineated by a complete or partial ring of hills , by mountains or cliffs . Where a geological region contains more than one plain , they may be connected by a pass ( sometimes termed a gap ) . Coastal plains would mostly rise from sea level until they run into elevated features such as mountains or plateaus . Plains are one of the major landforms on earth , where they are present on all continents , and would cover more than one-third of the world 's land area . Plains may have been formed from flowing lava , deposited by water , ice , wind , or formed by erosion by these agents from hills and mountains . Plains would generally be under the grassland ( temperate or subtropical ) , steppe ( semi-arid ) , savannah ( tropical ) or tundra ( polar ) biomes . In a few instances , deserts and rainforests can also be plains . Plains in many areas are important for agriculture because where the soils were deposited as sediments they may be deep and fertile , and the flatness facilitates mechanization of crop production ; or because they support grasslands which provide good grazing for livestock . |
Peoples_of_Palawan | Palawan , the largest province in the Philippines , is home to several indigenous ethnolinguistic groups namely , the Kagayanen > , Tagbanwa , Palawano , Taaw ' t Bato , Molbog and the Batak tribes . They live in remote villages in the mountains and coastal areas . It is believed that their ancestors occupied the province long before Malay settlers from the Majapahit Empire of Indonesia arrived in these islands in the later 12th or 13th centuries . In 1962 , a team of anthropologists from the National Museum led by Dr. Robert Fox unearthed fossils at Lipuun Point ( now known as the Tabon Cave Complex ) in Quezon town that were classified as those of Homo sapiens and believed to be 22,000 to 24,000 years old . The recovery of the Tabon Man and other significant findings in the area earned for Palawan the title , `` the Cradle of Philippine Civilization . '' Research has shown that the Tagbanwa and Palawano are possible descendants of the Tabon Caves ' inhabitants . Their language and alphabet , farming methods , and common belief in soul relatives are some of their cultural similarities . After the death of Ferdinand Magellan , the remnant of his fleet landed in Palawan . Magellan 's chronicler , Antonio Pigafetta , in his writings , described the cultivated fields of the native people populating the Palawan Islands . He also mentioned that these people use weapons consisting of blowpipes , spears and bronze ombard . During his stay in the area , he witnessed for the first time cockfighting and fistfighting . He also discovered that the natives had their own system of writing consisting of 13 consonants and 3 vowels , and they had a dialect of 18 syllables . He further wrote that in Palawan , the local King had 10 scribes who wrote down the King 's dictation on leaves of plants . |
Perfect_storm | A `` perfect storm '' is an expression that describes an event where a rare combination of circumstances will aggravate a situation drastically . The term is also used to describe an actual phenomenon that happens to occur in such a confluence , resulting in an event of unusual magnitude . |
Permanent_Service_for_Mean_Sea_Level | The Permanent Service for Mean Sea Level is a repository for tide gauge data used in the measurement of long-term sea level change . The PSMSL is based at the National Oceanography Centre in Liverpool , England . It was founded in 1933 as the IUGG Mean Sea Level Committee , and adopted as a Permanent Service of the International Council for Science in 1958 . The tide gauge data are freely accessible by all , and consist predominantly of monthly-mean and annual-mean sea levels . The primary , `` Revised Local Reference '' data set has a continuous history of benchmark surveys for each gauge , ensuring that sea level is measured relative to a known land-based datum . There is also a `` Metric '' data set without such datum control , and a set of hourly and daily ocean bottom pressure data from the open ocean . The latter has no datum control , and the instruments are prone to calibration drift , so the bottom pressure data are useful only for oscillations with periods significantly shorter than the length of an individual instrument deployment ( typically 1 year ) . The PSMSL is financially supported by the UK Natural Environment Research Council , the International Council for Science World Data System , and the Intergovernmental Oceanographic Commission . |
Plesiochronous_digital_hierarchy | The plesiochronous digital hierarchy ( PDH ) is a technology used in telecommunications networks to transport large quantities of data over digital transport equipment such as fibre optic and microwave radio systems . The term plesiochronous is derived from Greek plēsios , meaning near , and chronos , time , and refers to the fact that PDH networks run in a state where different parts of the network are nearly , but not quite perfectly , synchronized . Backbone transport networks replaced PDH networks with synchronous digital hierarchy ( SDH ) or synchronous optical networking ( SONET ) equipment over the ten years ending around the turn of the millennium ( 2000 ) , whose floating payloads relaxed the more stringent timing requirements of PDH network technology . The cost in North America was $ 4.5 billion in 1998 alone , p. 171 . PDH allows transmission of data streams that are nominally running at the same rate , but allowing some variation on the speed around a nominal rate . By analogy , any two watches are nominally running at the same rate , clocking up 60 seconds every minute . However , there is no link between watches to guarantee that they run at exactly the same rate , and it is highly likely that one is running slightly faster than the other . |
Physical_impacts_of_climate_change | This article is about the physical impacts of climate change . For some of these physical impacts , their effect on social and economic systems are also described . This article refers to reports produced by the IPCC . In their usage , `` climate change '' refers to a change in the state of the climate that can be identified by changes in the mean and/or variability of its properties , and that persists for extended periods , typically decades or longer ( IPCC , 2007d :30 ) . The climate change referred to may be due to natural causes and/or the result of human activity . |
Pen_y_Cymoedd | Pen y Cymoedd ( `` Head of the Valleys '' ) is a # 365m wind farm development currently under construction , located between Neath and Aberdare in south Wales . The company has signed a lease agreement with Vattenfall of Sweden , and its UK subsidiary Vattenfall United Kingdom ( formerly Nuon Renewables ) , to develop what would be the United Kingdom 's highest altitude wind farm , on a site owned by the Forestry Commission Wales , . The project would see the installation of 76 turbines that are planned to operate for 25 years , and to generate up to 256 MW , an amount enough to power up to 206,000 homes . The turbine manufacturer is Siemens Wind Power . During the planning process , Nuon agreed to contribute about # 1.85 m annually to a community fund and to invest # 3m in a habitat restoration scheme , and the following parties contributed to the debate : Glyncorrwg Action Group : the wind farm will look down on the village of Glyncorrwg in the Afan Valley . Residents of the village campaigned against the development , which they claim would destroy the character of the landscape . Campaign for the Protection of Rural Wales : objected on the grounds of its potential impact on a sensitive peat habitat . Neath Port Talbot Council : the planning committee decided not to object to the scheme in January 2012 , after councillors carried out a site visit , although they set a number of conditions . The project gained final planning permission in May 2012 , The final turbine ( 76th turbine ) of Pen y Cymoedd was installed on March 2 , 2017 . The wind farm is now fully operational as of May 2017 . . The first 3.0 MW Siemens 101m turbine was fully completed on April 8 , 2016 . |
Peninsular_Spain | Peninsular Spain refers to that part of Spanish territory located within the Iberian peninsula , thus excluding other parts of Spain : the Canary Islands , the Balearic Islands , Ceuta , Melilla , and a number of islets and crags off the coast of Morocco known collectively as plazas de soberanía ( places of sovereignty ) . In Spain it is mostly known simply as `` the Peninsula '' . It has land frontiers with France and Andorra to the north ; Portugal to the west ; and the British territory of Gibraltar to the south . Many inhabitants of peninsular Spain tend to conflate that region with Spain as a whole , disregarding the other territories mentioned above . |
Piacenzian | The Piacenzian is in the international geologic time scale the upper stage or latest age of the Pliocene . It spans the time between 3.6 ± 0.005 Ma and 2.588 ± 0.005 Ma ( million years ago ) . The Piacenzian is after the Zanclean and is followed by the Gelasian ( part of the Pleistocene ) . The Piacenzian is roughly coeval with the European land mammal age MN 16 , overlaps the late Chapadmalalan and early Uquian South American land mammal age and falls inside the more extensive Blancan North American land mammal age . It also correlates with the Astian , Redonian , Reuverian and Romanian regional stages of Europe . Some authorities describe the British Red Crag Formation and Waltonian stage as late Piacenzian , while others regard them as early Pleistocene . |
Plausible_deniability | Plausible deniability is the ability for persons ( typically senior officials in a formal or informal chain of command ) to deny knowledge of or responsibility for any damnable actions committed by others ( usually subordinates in an organizational hierarchy ) because of a lack of evidence that can confirm their participation , even if they were personally involved in or at least willfully ignorant of the actions . In the case that illegal or otherwise disreputable and unpopular activities become public , high-ranking officials may deny any awareness of such acts in order to insulate themselves and shift blame onto the agents who carried out the acts , as they are confident that their doubters will be unable to prove otherwise . The lack of evidence to the contrary ostensibly makes the denial plausible , that is , credible , although sometimes it merely makes it unactionable . The term typically implies forethought , such as intentionally setting up the conditions to plausibly avoid responsibility for one 's ( future ) actions or knowledge . In some organizations , legal doctrines such as command responsibility exist to hold major parties responsible for the actions of subordinates involved in heinous acts and nullify any legal protection that their denial of involvement would carry . Notably , plausible deniability is primarily a more typically Western cultural construct , as high-ranking officials in more typically Eastern cultures , such as Japan or Korea , are expected to be responsible for their subordinates . As an example , many Japanese CEOs commit suicide when their companies go bankrupt or was dishonored in some way . In politics and espionage , deniability refers to the ability of a powerful player or intelligence agency to pass the buck and avoid blowback by secretly arranging for an action to be taken on their behalf by a third party ostensibly unconnected with the major player . In political campaigns , plausible deniability enables candidates to stay clean and denounce third-party advertisements that use unethical approaches or potentially libellous innuendo . In the US , plausible deniability is also a legal concept . It refers to lack of evidence proving an allegation . Standards of proof vary in civil and criminal cases . In civil cases , the standard of proof is `` preponderance of the evidence '' whereas in a criminal matter , the standard is `` beyond a reasonable doubt '' . If an opponent can not provide evidence for his allegation , one can plausibly deny the allegation even though it may be true . Although plausible deniability has existed throughout history , that name for it was coined by the CIA in the early 1960s to describe the withholding of information from senior officials in order to protect them from repercussions in the event that illegal or unpopular activities by the CIA became public knowledge . The roots of the name go back to Harry Truman 's national security council paper 10/2 of June 18 , 1948 , which defined `` covert operations '' as '' ... all activities ( except as noted herein ) which are conducted or sponsored by this Government against hostile foreign states or groups or in support of friendly foreign states or groups but which are so planned and executed that any US Government responsibility for them is not evident to unauthorized persons and that if uncovered the US Government can plausibly disclaim any responsibility for them . '' During Eisenhower 's administration , NSC 10/2 was incorporated into more specific NSC 5412/2 `` Covert Operations . '' NSC 5412 was de-classified in 1977 , and is located at the National Archives . |
Phanerozoic | The Phanerozoic Eon ( British English Phanærozoic ) is the current geologic eon in the geologic time scale , and the one during which abundant animal and plant life has existed . It covers million years to the present , and began with the Cambrian Period when diverse hard-shelled animals first appeared . Its name was derived from the Ancient Greek words φανερός ( phanerós ) and ζωή ( zōḗ ) , meaning visible life , since it was once believed that life began in the Cambrian , the first period of this eon . The time before the Phanerozoic , called the Precambrian supereon , is now divided into the Hadean , Archaean and Proterozoic eons . The time span of the Phanerozoic starts with the rapid emergence of a number of animal phyla ; the evolution of those phyla into diverse forms ; the emergence and development of complex plants ; the evolution of fish ; the emergence of insects and tetrapods ; and the development of modern fauna . Land plant life appeared in the early Phanerozoic eon . During this time span , tectonic forces caused the continents to move and eventually collect into a single landmass known as Pangaea , which then separated into the current continental landmasses . |
Pegasus_(satellite) | The Pegasus satellite program was a series of three American satellites launched in 1965 to study the frequency of micrometeorite impacts on spacecraft . All three Pegasus satellites were launched by Saturn I rockets , and remained connected with their upper stages . The Pegasus satellite was named for the winged horse of Greek mythology and was first lofted into space by a NASA Saturn I rocket on February 16 , 1965 . Like its namesake , the Pegasus satellite was notable for its `` wings '' , a pair of 96 ft-long , 14 ft-wide arrays of 104 panels fitted with sensors to detect punctures by micrometeoroids at high altitudes , in support of the Apollo Program to send manned lunar landing missions starting by 1970 . Micrometeoroids were believed to be potentially hazardous to the Apollo crew if they could puncture the spacecraft skin . The sensors successfully measured the frequency , size , direction and penetration of scores of micrometeoroid impacts . The satellite also carried sample protective shields mounted on the arrays . The NASA Marshall Space Flight Center was responsible for the design , production and operation of the three Pegasus satellites which were launched by Saturn I rocket test flights in 1965 . At launch , a boilerplate Apollo Command/Service Module and launch escape system tower were atop the Saturn I , with the Pegasus experiment folded inside the Service Module . After first stage separation and second-stage ignition , the launch escape system was jettisoned . When the second stage attained orbit , the 10,000-pound Apollo boilerplate Command and Service modules were jettisoned into a separate orbit . Then a motor driven device extended the winglike panels on the Pegasus to a span of 96 ft. The Pegasus wings remained attached to the Saturn I 's second stage as planned . A television camera , mounted on the interior of the Service Module adapter , provided pictures of the satellite deploying in space and as one historian has written , `` captured a vision of the eerie silent wings of Pegasus I as they haltingly deployed . '' The satellite exposed more than 2300 sqft of instrumented surface , with thickness varying up to 0.016 in . Ernst Stuhlinger , then director of the MSFC Research Projects Laboratory , noted that all three Pegasus missions provided more than data on micrometeoroid penetration . Scientists also were able to gather data regarding gyroscopic motion and orbital characteristics of rigid bodies in space , lifetimes of electronic components in the space environment , and thermal control systems and the degrading effects of space on thermal control coatings . Space historian Roger Bilstein reported that for physicists the Pegasus missions provided additional knowledge about the radiation environments of space , the Van Allen radiation belts and other phenomena . |
Pliocene_climate | During the Pliocene epoch ( 5.3 Ma to 2.6 Ma ) climate became cooler and drier , and seasonal , similar to modern climates . The global average temperature in the mid-Pliocene ( 3.3 Ma -- 3 Ma ) was 2 -- 3 ° C higher than today , global sea level 25m higher and the northern hemisphere ice sheet was ephemeral before the onset of extensive glaciation over Greenland that occurred in the late Pliocene around 3 Ma . The formation of an Arctic ice cap is signaled by an abrupt shift in oxygen isotope ratios and ice-rafted cobbles in the North Atlantic and North Pacific ocean beds . Mid-latitude glaciation was probably underway before the end of the epoch . The global cooling that occurred during the Pliocene may have spurred on the disappearance of forests and the spread of grasslands and savannas . During the Pliocene the earth climate system response shifted from a period of high frequency-low amplitude oscillation dominated by the 41,000-year period of Earth 's obliquity to one of low-frequency , high-amplitude oscillation dominated by the 100,000-year period of the orbital eccentricity characteristic of the Pleistocene glacial-interglacial cycles . The equatorial pacific ocean sea surface temperature gradient was considerably lower than it is today , mean sea surface temperature in the east were substantially warmer than today but similar in the west , this condition has been described as a permanent El Niño state or El Padre |
Polar_amplification | Polar amplification is the phenomenon that any change in the net radiation balance ( for example greenhouse intensification ) tends to produce a larger change in temperature near the poles than the planetary average . On a planet with an atmosphere that can restrict longwave radiation to space ( a greenhouse effect ) , surface temperatures will be warmer than a simple planetary equilibrium temperature calculation would predict . Where the atmosphere or an extensive ocean is able to convect heat polewards , the poles will be warmer and equatorial regions cooler than their local net radiation balances would predict . In the extreme , the planet Venus is thought to have experienced a very large increase in greenhouse effect over its lifetime , so much so that its poles have warmed sufficiently to render its surface temperature effectively isothermal ( no difference between poles and equator ) . On Earth , water vapor and trace gasses provide a lesser greenhouse effect , and the atmosphere and extensive oceans provide efficient poleward heat transport . Both palaeoclimate changes and recent global warming changes have exhibited strong polar amplification , as described below . |
Petroleum_product | Petroleum products are materials derived from crude oil ( petroleum ) as it is processed in oil refineries . Unlike petrochemicals , which are a collection of well-defined usually pure chemical compounds , petroleum products are complex mixtures . The majority of petroleum is converted to petroleum products , which includes several classes of fuels . According to the composition of the crude oil and depending on the demands of the market , refineries can produce different shares of petroleum products . The largest share of oil products is used as `` energy carriers '' , i.e. various grades of fuel oil and gasoline . These fuels include or can be blended to give gasoline , jet fuel , diesel fuel , heating oil , and heavier fuel oils . Heavier ( less volatile ) fractions can also be used to produce asphalt , tar , paraffin wax , lubricating and other heavy oils . Refineries also produce other chemicals , some of which are used in chemical processes to produce plastics and other useful materials . Since petroleum often contains a few percent sulfur-containing molecules , elemental sulfur is also often produced as a petroleum product . Carbon , in the form of petroleum coke , and hydrogen may also be produced as petroleum products . The hydrogen produced is often used as an intermediate product for other oil refinery processes such as hydrocracking and hydrodesulfurization . |
Pennsylvania | Pennsylvania -LSB- pɛnsᵻlˈveɪnjə -RSB- ( Pennsylvania German : Pennsylvaani or Pennsilfaani ) , officially the Commonwealth of Pennsylvania , is a state located in the northeastern and Mid-Atlantic regions of the United States . The Appalachian Mountains run through its middle . The commonwealth borders Delaware to the southeast , Maryland to the south , West Virginia to the southwest , Ohio to the west , Lake Erie and the Canadian province of Ontario to the northwest , New York to the north , and New Jersey to the east . Pennsylvania is the 33rd largest , the 5th most populous , and the 9th most densely populated of the 50 United States . The state 's five most populous cities are Philadelphia ( 1,560,297 ) , Pittsburgh ( 305,801 ) , Allentown ( 118,577 ) , Erie ( 100,671 ) , and Reading ( 89,893 ) . The state capital , and its ninth-largest city , is Harrisburg . Pennsylvania has 140 mi of shoreline along Lake Erie and the Delaware Estuary . The state is one of the 13 original founding states of the United States ; it came into being in 1681 as a result of a royal land grant to William Penn , the son of the state 's namesake . Part of Pennsylvania ( along the Delaware River ) , together with the present State of Delaware , had earlier been organized as the Colony of New Sweden . It was the second state to ratify the United States Constitution , on December 12 , 1787 . Independence Hall , where the United States Declaration of Independence and United States Constitution were drafted , is located in the state 's largest city of Philadelphia . During the American Civil War , the Battle of Gettysburg , was fought in the south central region of the state . Valley Forge near Philadelphia was General Washington 's headquarters during the bitter winter of 1777 -- 78 . |
Physical_oceanography | Physical oceanography is the study of physical conditions and physical processes within the ocean , especially the motions and physical properties of ocean waters . Physical oceanography is one of several sub-domains into which oceanography is divided . Others include biological , chemical and geological oceanography . Physical oceanography may be subdivided into descriptive and dynamical physical oceanography . Descriptive physical oceanography seeks to research the ocean through observations and complex numerical models , which describe the fluid motions as precise as possible . Dynamical physical oceanography focuses primarily upon the processes that govern the motion of fluids with emphasis upon theoretical research and numerical models . These are part of the large field of Geophysical Fluid Dynamics ( GFD ) that is shared together with meteorology . |