787 résultats pour "percent"

• Bat - biology.

  tomb bat has rather small ears. The shapes of bat ears are extremely varied. The wide ears of the Australian false vampire bat meet above the head and are fused.Many bats are able to turn their ears in the direction of faint noises. Bat hearing and its use in echolocation are highly developed. Some bats have large, conspicuous eyes, while others may have small beady eyes. This variation suggests that vision plays different roles in the lives of various species.Despite the familiar expression, 'b...

• Soil. I INTRODUCTION Soil, the loose material that covers the land surfaces of

  an exchange between plants and the atmosphere, as oxygen diffuses into the soil and is used by roots for respiration. In turn, the resulting carbon dioxide diffusesthrough pore spaces and returns to the atmosphere. This exchange is most efficient in soils with a high degree of porosity. For farmers, gardeners, landscapers, andothers with a professional interest in soil health, the process of aeration—making holes in the soil surface to permit the exchange of air—is a crucial activity. Theburrowi...

• Tiger - biology.

  have a simple digestive system designed to process meat so that the nutrients can be readily absorbed into the bloodstream. With the exception of white tigers, which have blue eyes, all tigers have yellow eyes. Tigers mainly use vision to find prey. Although tigers see about as well as humansduring the day, their large eye openings gather more light than do human eyes, making tiger night vision far superior to that of humans. In addition, a special structurein the tiger’s eye, called the tapetu...

• Capital Punishment.

  deterrent effect. Capital punishment advocates note that because the death penalty is reserved for the most aggravated murders, the deterrent effect of capitalpunishment on such crimes may not be apparent in data on homicide rates in general. Supporters also urge that the conflicting results of various studies indicate thatthe deterrent effect of the death penalty cannot not be proven or disproven with any certainty. They maintain that in the absence of conclusive proof that the threat ofexecuti...

• Tampa - geography.

  tennis. V ECONOMY Since 1980 metropolitan Tampa has become the foremost banking, commercial, and services center in the western part of the Florida Peninsula. The city is home to manyhigh-technology companies including biomedical and information technology firms and manufacturers of medical products. Large new office complexes have been built nearBrandon along interstates 75 and 4 in the eastern suburbs and most importantly at Westshore adjacent to Tampa International Airport in the west; downt...

• Lightning.

  In the U.S. about 100 persons are killed and many injured by lightning each year, more than by tornadoes or hurricanes. Forty percent of all farm fires and 75,000forest fires a year are started by lightning. Lightning is not all bad, however. The soil is enriched with nitrogen that is released from the atmosphere by lightning andcarried to the ground by raindrops. Some scientists believe that lightning may have been a key element in the origin of life on earth, creating from simple elementscompl...

• Arthropod - biology.

  through a series of distinct phases to become adults. Larvae may also inhabit different environments and eat different foods than their parents. The life spans ofarthropods range from a few weeks to several decades. V ARTHROPOD EVOLUTION The evolutionary origins of modern arthropods are unclear and complex. It is generally accepted that the phylum is polyphyletic—that is, derived from several separateancestral lines. The ancestors of arthropods were ancient aquatic segmented worms, similar to p...

• Electric Lighting.

  successful arc lamp in 1878. Tungsten filaments were substituted for carbon filaments in incandescent lamps in 1907, and gas-filled incandescent lamps were developedin 1913. The fluorescent lamp was introduced in 1938. See also Lamp. For most of the 20th century the incandescent light bulb was widely used for lighting in homes. More energy-efficient and longer-lasting fluorescent lamps were adoptedfor industrial and office use. In 1979 a compact fluorescent bulb that screwed into ordinary lig...

• Liver.

  by bacterial infections. But hepatitis is most often caused by one of several viruses. The hepatitis A virus (HAV) can produce flulike symptoms and jaundice, but manypeople who contract it have no symptoms. The disease tends to resolve on its own. Because HAV lives in feces in the intestinal tract, hepatitis A is prevalent in areaswhere drinking water is contaminated with raw sewage. Good hygiene practices and a hepatitis A vaccination are effective measures of prevention. Hepatitis B is a more...

• Malaria.

  last long and is unlikely to be fatal. Infants and children are especially vulnerable to malaria because they have not yet built up immunity to the parasite. Some peoplehave genetic traits that help them resist malaria. Sickle-cell anemia and thalassemia, for example, are inherited blood disorders linked to malaria resistance. Travelers who lack immunity to malaria should take precautionary measures when visiting areas where the disease is prevalent. Such measures include using insectrepellents,...

• Salmon (fish) - biology.

  alarm and become one of the most important conservation issues in the Pacific Northwest. Less than 2 percent of the wild salmon population of the Columbia River Basin(including parts of Washington, Oregon, Idaho, Montana, Wyoming, and British Columbia) remains and only one individual sockeye salmon returned to the Snake Riverin Idaho in 1994. Coho salmon in the Snake River have been declared extinct by the U.S. Fish and Wildlife Service, as have 106 other salmon populations on the WestCoast. Man...

• Penguin - biology.

  B Parents and Offspring Once female penguins lay their eggs, both the parents incubate the eggs. The incubation period varies according to species, ranging from 33 days for the little penguinto about 63 days for the emperor penguin. In most medium-sized penguins incubation takes 35 to 38 days. The incubation routine is highly variable among penguinspecies, although in general both sexes participate in incubation and feeding of young. Male and female Adélie penguins take turns incubating their e...

• Leukemia.

  leukemia, and normal or mildly decreased in chronic lymphocytic leukemia. Nearly all chronic leukemia patients have increased white cell counts. In chronic myelocyticleukemia, some of these leukemic white cells are capable of functioning as normal cells do by fighting infectious microbes. Hence, infection is no more common than in ahealthy individual. In chronic lymphocytic leukemia the blood contains large numbers of malignant lymphocytes that do not function normally. Normal lymphocytescoexist...

• Giant Panda - biology.

  In 2007 conservationists announced that a parasitic roundworm was responsible for a significant number of the panda deaths reported in the wild since 1990. Theparasite Baylisascaris schroederi causes the disease visceral larval migrans, which results in bleeding in the lungs, the liver, and the intestines, and can also affect the brain. It is not known if other recent pandas deaths were caused by the same parasite or by a different contagious disease. Loss of habitat from deforestation is forc...

• John Diefenbaker.

  only Conservative elected from Saskatchewan, which had gone solidly to the Co-operative Commonwealth Federation (CCF), a coalition party dedicated to social andwelfare reforms. In 1952 the Liberals in Saskatchewan abolished Diefenbaker's Lake Centre seat altogether by merging it with the neighboring legislative district of Moose Jaw, where theCCF had a vast majority. In 1953 Diefenbaker decided to run for election in Prince Albert. Again he was the only Conservative returned to Parliament fromSa...

• John Diefenbaker - Canadian History.

  only Conservative elected from Saskatchewan, which had gone solidly to the Co-operative Commonwealth Federation (CCF), a coalition party dedicated to social andwelfare reforms. In 1952 the Liberals in Saskatchewan abolished Diefenbaker's Lake Centre seat altogether by merging it with the neighboring legislative district of Moose Jaw, where theCCF had a vast majority. In 1953 Diefenbaker decided to run for election in Prince Albert. Again he was the only Conservative returned to Parliament fromSa...

• Turbine.

  steam turbine has supplanted the reciprocating engine as a prime mover in large electricity-generating plants and is also used as a means of jet propulsion. Steam turbines are used in the generation of nuclear power and in nuclear ship propulsion. They operate with fuel-fired boilers for power generation. In cogenerationapplications requiring both process heat (heat used in an industrial process) and electricity, steam is raised at high pressure in the boiler and extracted from the turbineat th...

• Courts in the United States.

  The term circuit derives from the original structure of these courts. Under the Judiciary Act of 1789, trials of certain cases were required to be held before three-judge circuit courts consisting of two Supreme Court justices and the federal trial judge in the district court. In addition to their regular duties, Supreme Court justices were required to ride circuit, traveling from district to district within their assigned circuit, often covering great distances. In 1891 Congress establishe...

• Dentistry.

  Together with dentists, dental hygienists and dental assistants make up the team that provides dental care to patients. Hygienists record patient medical histories, suchas blood pressure and pulse. They clean teeth, apply sealants and fluoride treatments, teach patients sound oral hygiene practices, and often assist with X rays. Manyhygienists receive a two-year associate degree, while others may choose to enroll in a four-year program at a university or in a master’s degree program. There are25...

• Brian Mulroney.

  At the party convention Mulroney was one of the candidates who ran against Clark. This time Mulroney did not have to contend with a rival candidate from Québec. Healso had the support of the remnants of the Diefenbaker faction—who disliked Clark even more than they disliked Mulroney. Mulroney was also endorsed by asubstantial group of members of Parliament; this endorsement helped allay concerns about whether he could provide effective leadership in Parliament. Mulroney waselected leader of the...

• Brian Mulroney - Canadian History.

  At the party convention Mulroney was one of the candidates who ran against Clark. This time Mulroney did not have to contend with a rival candidate from Québec. Healso had the support of the remnants of the Diefenbaker faction—who disliked Clark even more than they disliked Mulroney. Mulroney was also endorsed by asubstantial group of members of Parliament; this endorsement helped allay concerns about whether he could provide effective leadership in Parliament. Mulroney waselected leader of the...

• Paul Martin.

  VI CONFLICT WITH THE PRIME MINISTER Martin’s success could not have been achieved without the support he received from Jean Chrétien. Yet relations between the two men continued to deteriorate. In partthis was because of their continuing disagreement about how best to deal with the separatist challenge in Québec. In the 1993 election, a majority of Québec seats hadgone to the Bloc Québécois, and in 1994 the provincial separatist party, the Parti Québécois, won election on a platform promising...

• Paul Martin - Canadian History.

  VI CONFLICT WITH THE PRIME MINISTER Martin’s success could not have been achieved without the support he received from Jean Chrétien. Yet relations between the two men continued to deteriorate. In partthis was because of their continuing disagreement about how best to deal with the separatist challenge in Québec. In the 1993 election, a majority of Québec seats hadgone to the Bloc Québécois, and in 1994 the provincial separatist party, the Parti Québécois, won election on a platform promising...

• Herbert Hoover.

  E Postwar Work Even after the armistice, the Allies continued their blockade around Germany. Hoover, in Europe again, worked to have it relaxed. He was appointed chairman of theAmerican Relief Administration to assist in the economic restoration of Europe, receiving from the U.S. Congress $100 million to fight famine and plague. In this officialrole, and afterward as a private citizen, Hoover oversaw the distribution of 46 million tons of food to people in 30 countries. He controlled shipping,...

• Herbert Hoover

  E Postwar Work Even after the armistice, the Allies continued their blockade around Germany. Hoover, in Europe again, worked to have it relaxed. He was appointed chairman of theAmerican Relief Administration to assist in the economic restoration of Europe, receiving from the U.S. Congress $100 million to fight famine and plague. In this officialrole, and afterward as a private citizen, Hoover oversaw the distribution of 46 million tons of food to people in 30 countries. He controlled shipping,...

• Relativity - astronomy.

  beta, for example, might be as large as 0.5, and the mass of the electron doubled. The mass of a rapidly moving electron could be easily determined by measuring thecurvature produced in its path by a magnetic field; the heavier the electron, the greater its inertia and the less the curvature produced by a given strength of field ( see Magnetism). Experimentation dramatically confirmed Einstein's prediction; the electron increased in mass by exactly the amount he predicted. Thus, the kinetic ener...

• United States House of Representatives.

  Because of the high cost of elections and the short two-year term of office, members of the House campaign almost constantly. They spend much of their time raisingcampaign funds, and they frequently return to their districts to keep in touch with voters. Because the elections are so frequent, House members tend to pay closeattention to how their votes in Congress will be seen in the short term. House members tend to come from wealthier family backgrounds than average Americans. Few working class...

• Astrobiology - astronomy.

  water to help reactions along. American chemists Stanley Miller and Harold Urey tested part of Oparin and Haldane’s hypothesis in the early 1950s by simulating conditions of the early Earth. In whathas become known as the Miller-Urey experiment, the two scientists connected two flasks with a loop of glass tubing that allowed the gases to pass between the flasks.They filled the upper flask with methane, ammonia, and hydrogen—components thought to have been in the early atmosphere. They filled the...

• Supreme Court of Canada.

  whether the leave to appeal will be granted and the case heard by the Court. The Court has no specified criteria by which it determines whether to grant leave, and the Court does not give reasons for its decision. The key factor appears to be acase’s degree of national importance. Other factors might include the impact of uncertainty in the challenged law, the case’s appropriateness for developing the law torespond to changing social needs, and the presence of a split decision at the court of ap...

• Insect - biology.

  they almost always have six legs. In some insects, such as beetles, the legs are practically identical, but in other insects each pair is a slightly different shape. Still otherinsects have specialized leg structures. Examples are praying mantises, which have grasping and stabbing forelegs armed with lethal spines, and grasshoppers andfleas, which have large, muscular hind legs that catapult them into the air. Mole crickets’ front legs are modified for digging, and backswimmers have hind legs de...

• Comet - astronomy.

  may exceed the planet Jupiter in size, however. Observations from telescopes on Earth and in space indicate that most of the gases in the coma and tail of a comet are fragmentary molecules, or radicals, of the mostcommon elements in space: hydrogen, carbon, nitrogen, and oxygen. The radicals, for example, of CH, NH, and OH may be broken away from the stable molecules CH 4 (methane), NH 3 (ammonia), and H 2O (water), which may exist as ices or more complex, very cold compounds in the nucleus. Al...

• Bear - biology.

  programs sponsored by zoos or other breeding centers have attempted to breed giant pandas in captivity, although most of these programs have proved unsuccessful.Among the difficulties faced by captive breeders has been the problem of encouraging a female giant panda to mate with a selected male during the two to three daysof the year when she is most fertile, a period known as estrus. B Spectacled Bear Creamy-white rings surrounding the eyes give the spectacled bear its name. Its shaggy coat of...

• Sydney (Australia) - geography.

  blocks in the eastern suburbs and around railway stations elsewhere; and homes on large lots in the outer suburbs, especially those to the northwest. For publichousing, the state government built a number of high-rise apartment blocks in run-down inner suburbs after World War II (1939-1945). These housing projects weresoon deemed unsuccessful and were discontinued because they fostered crime and other social problems. More recently, public housing has taken the form of separateor semidetached ho...

• Austin - geography.

  Mexico, and Canada. IV POINTS OF INTEREST Among Austin’s points of interest are the State Capitol Building, constructed of Texas pink granite between 1882 and 1888, and the Governor’s Mansion (1856). Severalbuildings reflect Austin’s early architecture, including the French Legation (1841), the residence of the French ambassador to the Republic of Texas, which existed from 1836until 1845; and the Driskill Hotel. Austin is home to the largest colony of urban bats in North America. Between April...

• Nauru Facts and Figures.

  Population per physician Not available Population per hospital bed Not available Literacy rateTotal Not available Female Not available Male Not available Education expenditure as a share of gross national product (GNP) Not available Number of years of compulsory schooling 11 years (2001-2002) Number of students per teacher, primary school 23 students per teacher (1998-1999) GOVERNMENTForm of government Republic Voting qualifications Universal and compulsory at age 20 Constitution 3...

• Monaco Facts and Figures.

  Male 76.1 years (2008 estimate) Infant mortality rate 5 deaths per 1,000 live births (2008 estimate) Population per physician 171 people (2004) Population per hospital bed 51 people (1995) Literacy rateTotal Not available Female Not available Male Not available Education expenditure as a share of gross national product (GNP) Not available Number of years of compulsory schooling 10 years (2002-2003) Number of students per teacher, primary school 22 students per teacher (2000-2001)...

• Andorra Facts and Figures.

  Population per physician 275 people (2006) Population per hospital bed 303 people (2003) Literacy rateTotal Not available Female Not available Male Not available Education expenditure as a share of gross national product (GNP) Not available Number of years of compulsory schooling 10 years (2002-2003) Number of students per teacher, primary school 12 students per teacher (2002-2003) GOVERNMENTForm of government Parliamentary coprincipality Voting qualifications Universal at age 18 C...

• Phoenix (city, Arizona) - geography.

  alfalfa, durum wheat, vegetables, citrus and other fruits, and beef and dairy cattle. The health service industry is a large and growing part of the city’s economy. United States State Capitals© Microsoft Corporation. All Rights Reserved. Phoenix is served by interstate highways 10 and 17, the Southern Pacific and the Burlington Northern Santa Fe railroads, and Sky Harbor International Airport. In its early years, Phoenix became popular as a haven for winter visitors from North America’s colder...

• Tuvalu Facts and Figures.

  Literacy rateTotal Not available Female Not available Male Not available Education expenditure as a share of gross national product (GNP) Not available Number of years of compulsory schooling 8 years (2001-2002) Number of students per teacher, primary school 25 students per teacher (2001-2002) GOVERNMENTForm of government Constitutional monarchy Voting qualifications Universal at age 18 Constitution1 October 1978; revised 1986 Armed forcesTotal number of military personnel Not avail...

• Aluminum - chemistry.

• Air Quality.

• Toronto - geography.

  to arrive in the Toronto CMA, most conspicuously from Hong Kong. People of Chinese origin accounted for over 9 percent of the city’s population at the 2001 census.Foreign-born residents constitute 44 percent of the population, the highest metropolitan percentage on the North American continent. The ethnic breakdown of metropolitanToronto in the 2001 census included Canadian, 18.5 percent; English, 16.9 percent; Scottish, 11.1 percent; Irish, 10.5 percent; Chinese, 9.4 percent; Italian, 9.2 perce...

• Rice - biology.

  V HISTORY According to the most widely accepted theory, rice cultivation originated as early as 10,000 BC in Asia. Archaeological evidence shows that rice was grown in Thailand as early as 4000 BC, and over the centuries spread to China, Japan, and Indonesia. By 400 BC rice was cultivated in the Middle East and Africa. The invading armies of Alexander the Great probably introduced rice to Greece and nearby Mediterranean countries around 330 BC. Rice was brought to the American colonies in t...

• Nashville - geography.

  The metropolitan area has 10,549.3 sq km (4,073.1 sq mi). The important cities and towns in the metropolitan region include Franklin, site of a major battle of theAmerican Civil War (1861-1865), Murfreesboro, Gallatin, Lebanon, and Springfield. Nashville’s suburbs also have spread into adjacent counties in recent years, particularlyWilliamson County to the south. Nashville’s downtown is located on high, limestone bluffs overlooking the Cumberland River, with four bridges connecting the east and...

• Chicago (city, Illinois) - geography.

  The Chicago River divides the city into three broad sections, known traditionally as the North, West, and South sides. The North Side is largely residential, interspersed withindustry. The West Side generally is a lower-income residential area and contains numerous industrial, railroad, and wholesale-produce facilities. The South Side occupiesalmost half the city and contains diverse residential neighborhoods, ranging from decayed tenement districts to areas of modest detached houses. The South...

• St. John's (city, Newfoundland and Labrador) - Geography. I INTRODUCTION St. John's (city,

  coast of Newfoundland and Labrador have brought some hope of potential economic upturn for the port. St. John’s has an international airport, which connects the city to mainland Canada and points outside the country. The city is also the eastern terminus of the Trans-Canada Highway. Although traffic through the city’s harbor has diminished considerably, the port of St. John’s continues to serve as an important Canadian Coast Guarddepot and port of call for container ships. Passenger service on t...

• Toronto - geography.

  now a museum. In the far northeast side of the City is the Toronto Zoo, a modern zoo covering many acres and with well-designed animal displays. Originally known as the SkyDome, the Rogers Centre is a state-of-the-art stadium complex that opened in 1989. The stadium features a retractable roof that can openin 20 minutes to expose the playing field and most of the 50,000 seats to the open air. It is the home of the Toronto Argonauts of the Canadian Football League and theToronto Blue Jays of Majo...

• Toronto - Geography.

  now a museum. In the far northeast side of the City is the Toronto Zoo, a modern zoo covering many acres and with well-designed animal displays. Originally known as the SkyDome, the Rogers Centre is a state-of-the-art stadium complex that opened in 1989. The stadium features a retractable roof that can openin 20 minutes to expose the playing field and most of the 50,000 seats to the open air. It is the home of the Toronto Argonauts of the Canadian Football League and theToronto Blue Jays of Majo...

• Welfare.

  industrializing societies. Governments typically financed social insurance programs with tax funds and direct levies on the wages of potential recipients. Social insurancereplaced part of incomes lost when workers became disabled, were laid off, or had reached an age that forced them out of the labor market. Later, governments of Germany, France, Belgium, Sweden, and other countries developed forms of social insurance that provided population-wide, or universal,coverage. Such forms included chil...

• Swaziland - country.

  convention of 1894 placed Swaziland under the administration of the Union of South Africa (now the Republic of South Africa). Administration passed to the Britishgovernor of Transvaal in 1903 and to the British high commissioner for South Africa in 1907. In 1967 Swaziland became internally self-governing. The nation attainedfull independence on September 6, 1968, with King Sobhuza II as head of state. The king suspended the constitution in 1973 and banned all political activity; under anew const...