380 résultats pour "development"

• Sleep - biology.

  V FUNCTIONS OF SLEEP Although no one knows for sure why we sleep, there are a number of theories. Sleep may have evolved to protect animals from their predators by reducing theiractivity during the times when they are most vulnerable. Research has shown that REM and NREM sleep may serve specific biological functions. Sleep deprivation studies reveal that humans and other animals respond to sleeploss in the same way. When study subjects are deprived of REM sleep, they tend to spend longer period...

• Wetland.

  Other plants and animals have special adaptations suited for living in a wet environment. Most emergent plants have air spaces in their stems that enable oxygen to betransported to roots that grow in sediments with no oxygen. Some of the trees that grow in swamps form a set of roots above the soil surface or above the water thatallows them to get oxygen to the lower roots. In saltwater wetlands, specialized cells can limit the amount of salt that enters a plant, or specialized organs can excrete...

• Unemployment.

  set up to monitor the economy and provide advice to the president and Congress. Between 1945 and 1990 nine cyclical swings in unemployment occurred; all weresmaller than the 1930s depression. During this period the unemployment rate was as low as 2.9 percent (1953) and as high as 9.7 percent (1982). Because of cutbacksin the unemployment insurance program and changes in the nature of employment during the 1980s, however, only 37 percent of jobless workers received benefits in1990. Fears that the...

• Magnetism I INTRODUCTION Magnetism, an aspect of electromagnetism, one of the fundamental forces of nature.

  the French physicist Paul Langevin produced a theory regarding the temperature dependence of the magnetic properties of paramagnets (discussed below), which wasbased on the atomic structure of matter. This theory is an early example of the description of large-scale properties in terms of the properties of electrons and atoms.Langevin's theory was subsequently expanded by the French physicist Pierre Ernst Weiss, who postulated the existence of an internal, “molecular” magnetic field inmaterials...

• Human Evolution.

  Strepsirhines are the most primitive types of living primates. The last common ancestors of strepsirhines and other mammals—creatures similar to tree shrews andclassified as Plesiadapiformes—evolved at least 65 million years ago. The earliest primates evolved by about 55 million years ago, and fossil species similar to lemursevolved during the Eocene Epoch (about 55 million to 38 million years ago). Strepsirhines share all of the basic characteristics of primates, although their brains are notpa...

• Human Evolution - biology.

  classified as Plesiadapiformes—evolved at least 65 million years ago. The earliest primates evolved by about 55 million years ago, and fossil species similar to lemursevolved during the Eocene Epoch (about 55 million to 38 million years ago). Strepsirhines share all of the basic characteristics of primates, although their brains are notparticularly large or complex and they have a more elaborate and sensitive olfactory system (sense of smell) than do other primates. B Haplorhines B1 Tarsiers T...

• Denver - geography.

  Denver is the center of professional sports in the Rocky Mountain region. Major league teams are the Denver Broncos (football), Colorado Rockies (baseball), DenverNuggets (basketball), and Colorado Avalanche (ice hockey). Coors Field (opened in 1995) is the home of the Colorado Rockies. The Broncos began play at the newlyconstructed Invesco Field at Mile High in 2001, and the Nuggets and Avalanche play at the Pepsi Center. The National Western Stock Show and Rodeo, one of thelargest such shows i...

• Iran - country.

  Zagros mountains. In the more arid central part of the country, wild pistachio and other drought-resistant trees grow in areas that have not been disturbed by humanactivity. Tamarisk and other salt-tolerant bushes grow along the margins of the Dasht-e Kavir. A wide variety of native mammals, reptiles, birds, and insects inhabit Iran. Many species of mammals—including wolves, foxes, bears, mountain goats, red mountainsheep, rabbits, and gerbils—continue to thrive. Others—including Caspian tigers,...

• Modern Dance I INTRODUCTION Modern Dance, tradition of theatrical dance unique to the 20th century.

  Though both had their own interests and styles, their collaboration helped establish modern dance as a 20th-century artform. Shawn helped overcome prejudices against men in the new field of modern dance.E.O. Hoppé/Corbis Because a dance language involves elements such as posture, use of the body’s weight, and the character of movements (sinuous, angular, and so forth)—as well asspecific movements of the head, torso, hands, arms, legs, and feet—most creators of modern dance have considered it ess...

• Miami (Florida) - geography.

  VI EDUCATIONAL AND CULTURAL INSTITUTIONS Colleges and universities in the area include the University of Miami, Florida International University, Barry University, St. Thomas University, and Florida MemorialCollege. Miami-Dade Community College, one of the nation’s largest two-year colleges, has six campuses in the region. Leading museums include the Historical Museumof Southern Florida, the Miami Museum of Science, the Miami Art Museum, the Lowe Art Museum on the campus of the University of M...

• Canada.

  Six general landform regions are distinguishable in Canada: the Appalachian Region, the Great Lakes and St. Lawrence Lowlands, the Canadian Shield, the Great Plains,the Canadian Cordillera, and the Canadian Arctic Archipelago. B1 Appalachian Region and Great Lakes and St. Lawrence Lowlands Eastern Canada consists of the Appalachian Region and the Great Lakes and St. Lawrence Lowlands. The Appalachian Region embraces Newfoundland Island, NovaScotia, New Brunswick, Prince Edward Island, and the G...

• Canada - country.

  Six general landform regions are distinguishable in Canada: the Appalachian Region, the Great Lakes and St. Lawrence Lowlands, the Canadian Shield, the Great Plains,the Canadian Cordillera, and the Canadian Arctic Archipelago. B1 Appalachian Region and Great Lakes and St. Lawrence Lowlands Eastern Canada consists of the Appalachian Region and the Great Lakes and St. Lawrence Lowlands. The Appalachian Region embraces Newfoundland Island, NovaScotia, New Brunswick, Prince Edward Island, and the G...

• Canada - Canadian History.

  Six general landform regions are distinguishable in Canada: the Appalachian Region, the Great Lakes and St. Lawrence Lowlands, the Canadian Shield, the Great Plains,the Canadian Cordillera, and the Canadian Arctic Archipelago. B1 Appalachian Region and Great Lakes and St. Lawrence Lowlands Eastern Canada consists of the Appalachian Region and the Great Lakes and St. Lawrence Lowlands. The Appalachian Region embraces Newfoundland Island, NovaScotia, New Brunswick, Prince Edward Island, and the G...

• Liechtenstein - country.

  principal crops are corn, potatoes, barley, wheat, and vegetables. Grapes are grown for wine production. Cattle and sheep are raised for meat and dairy products. B Manufacturing Liechtenstein has few raw materials and must import more than 90 percent of its energy sources. Consequently, Liechtenstein has no heavy industry. Instead, theprincipality has developed a number of efficient, small-scale industries that manufacture specialized goods such as false teeth and dental supplies, pharmaceutica...

• Australia - country.

  itself forms most of the border between New South Wales and Victoria. Considerable lengths of the Murray, Darling, and Murrumbidgee rivers are navigable during thewet seasons. The central plains region, also known as the Channel Country, is interlaced by a network of rivers. During the rainy season these rivers flood the low-lying countryside,but in dry months they become merely a series of water holes. The Victoria, Daly, and Roper rivers drain a section of the Northern Territory. In Queensland...

• Australia - Geography.

  itself forms most of the border between New South Wales and Victoria. Considerable lengths of the Murray, Darling, and Murrumbidgee rivers are navigable during thewet seasons. The central plains region, also known as the Channel Country, is interlaced by a network of rivers. During the rainy season these rivers flood the low-lying countryside,but in dry months they become merely a series of water holes. The Victoria, Daly, and Roper rivers drain a section of the Northern Territory. In Queensland...

• Tuberculosis.

  TB has existed for thousands of years. Scars on a skull found in Turkey indicate the presence of the disease 500,000 years ago. Scientists also have found tubercles inmummified bodies from ancient Egypt. References to TB can be found in the writings of ancient Babylonia, Egypt, and China. The term tuberculosis was first used in 1839; it was derived from the Latin word tubercula, meaning small lump, referring to the small scars seen in tissues of infected individuals. TB reappeared in Europe...

• Stroke.

  IV DIAGNOSIS The symptoms typical of a stroke can also be caused by other conditions, including brain tumors, various infections, and overdoses of certain drugs. A patient that hasstrokelike symptoms may undergo a battery of imaging techniques to rule out other medical problems and confirm that a stroke has occurred. The key imagingtechnique used in diagnosing strokes is computed tomography (also known as CT or CAT scanning), which employs X rays to obtain images of the internal structures oft...

• Puzzle.

  Visual puzzles involve searching a picture to find hidden or disguised figures or answering a question about some part of a visual illusion. For instance, the popular 19th- century prints of American lithographic company Currier & Ives featured hidden people, animals, and other objects. A 16th-century painting from Bukhara, Uzbekistan,of a camel includes hidden figures of 17 people, 10 rabbits, a monkey, and a dragon (Metropolitan Museum of Art, New York City). B Mathematical Puzzles and Logic...

• Senegal - country.

  Although most of the population works in agriculture, Senegal has a growing industrial sector, one of the largest in West Africa. Nevertheless, two cash crops remain atthe foundation of the economy—peanuts and cotton. Important technical and economic assistance has been provided by France and other countries of the EuropeanUnion and the International Bank for Reconstruction and Development (World Bank). In 2006 the gross domestic product (GDP) was $9.2 billion, or $760.90 a person. A Agriculture...

• Saudi Arabia - country.

  C Natural Resources Some of the world’s largest oil and natural gas fields lie beneath Saudi Arabia and its offshore waters, representing the country’s most economically important naturalresource. In 2007 Saudi Arabia’s oil reserves were estimated at 264 billion barrels. Before the discovery and exploitation of these reserves in the mid-20th century,Saudi Arabia was one of the poorest countries in the world. Its relatively small population subsisted in a harsh environment with little agricultur...

• Army. I INTRODUCTION Army, military land forces of a nation, assembled, drilled, disciplined,

  disappearance for several centuries of large standing armies in Europe. A Middle Ages Feudalism was based on a concept of local defense, each baron or landowner governing land that had been given him by the king, and each lord having his ownpersonal protective forces recruited from among men who worked for him. In return, each lord and his men were pledged to annual service to the monarch and couldbe called on in special instances, as in the defense of Christendom during the Crusades. National...

• Sambia - geographie.

  Alphabetisierungsgrad beträgt 82,2 Prozent. An der Universität von Sambia in Lusaka (gegründet 1965) studieren etwa 4 600 Studenten. Das Livingstone Museum in Maramba enthält eine Sammlung von Ausstellungsstücken zur Archäologie und Naturgeschichte Südafrikas. Das Institut für AfrikanischeStudien, das der Universität von Sambia angegliedert ist, veröffentlicht Studien über Zentralafrika. 5 VERWALTUNG UND POLITIK Sambia ist seit 1964 eine Präsidialrepublik. Gültig ist die Verfassung von 1991. 5....

• Yukon Territory - Geography.

  Tourism is the second most important private sector industry in the Yukon. Visitors come to fish, hunt, enjoy the rugged scenery, and see the historic buildings andcreeks associated with the gold rush. Some marten, lynx, muskrat, wolverine, and other fur-bearing animals are still trapped, but the Yukon plays a minor role in Canadian fur production. The Yukon’s manufacturing industries consist almost exclusively of some mineral refining, printing, and sawmilling. Several hydroelectric plants gene...

• Yukon Territory - Canadian History.

  Tourism is the second most important private sector industry in the Yukon. Visitors come to fish, hunt, enjoy the rugged scenery, and see the historic buildings andcreeks associated with the gold rush. Some marten, lynx, muskrat, wolverine, and other fur-bearing animals are still trapped, but the Yukon plays a minor role in Canadian fur production. The Yukon’s manufacturing industries consist almost exclusively of some mineral refining, printing, and sawmilling. Several hydroelectric plants gene...

• South America - Geography.

  South America is dominated by relatively warm climatic regimes. Spanning nearly the entire continent along the equator is a belt of humid tropical climate that grades tothe north and south into broad zones where the length of the rainy season and the amount of rainfall diminish. These zones have wet summers and dry winters and aresubject to prolonged droughts. Droughts are a particularly serious problem in northeastern Brazil and along the northern coast of Venezuela and Colombia. The areas ofra...

• Israel (country) - country.

  harbor in the northern part of the country, and Ashdod, an artificial deepwater port to the south, serve as the main seaports on the Mediterranean. The port of Elat onthe Gulf of Aqaba provides Israel’s only access to the Red Sea, making it extremely important to the country’s shipping interests. D Natural Resources Although much of Israel’s desert regions contain poor soils, the northern Negev, the coastal plains, and the interior valleys provide patches of productive soils. Anestimated 18 per...

• Europe .

  D Vegetation Although much of Europe, particularly the west, was originally covered by forest, the vegetation has been transformed by human habitation and the clearing of land.Only in the most northerly mountains and in parts of north central European Russia has the forest cover been relatively unaffected by human activity. On the otherhand, a considerable amount of Europe is covered by woodland that has been planted or has reoccupied cleared lands. The largest vegetation zone in Europe, cuttin...

• Europe - Geography.

  D Vegetation Although much of Europe, particularly the west, was originally covered by forest, the vegetation has been transformed by human habitation and the clearing of land.Only in the most northerly mountains and in parts of north central European Russia has the forest cover been relatively unaffected by human activity. On the otherhand, a considerable amount of Europe is covered by woodland that has been planted or has reoccupied cleared lands. The largest vegetation zone in Europe, cuttin...

• Classification - biology.

  species based on the fewest number of shared changes that have occurred from generation to generation. IV HISTORY OF CLASSIFICATION SYSTEMS Classification is one of the oldest sciences, but despite its age it is still a vigorous field full of new discoveries and methods. Much like other fields of science, greatthinkers have shaped the course of classification. One of the earliest classification schemes was established by Greek philosopher Aristotle, who lived in the 300s BC. Aristotle believe...

• Barbados - country.

  Barbados is served by a public library system centered in Bridgetown. B Culture The culture of Barbados combines English institutions, which evolved through more than three centuries of English rule, with a folk culture of African origin. Because ofits English traditions, Barbados is sometimes called “Little England.” Cricket has traditionally been the national game, and the island has produced some of the sport’sgreatest players. Water sports including surfing, swimming, snorkeling, and sailin...

• Warsaw - geography.

  VI ECONOMY In addition to serving as Poland's leading administrative center, Warsaw is also a center for science, research, and higher education. Since World War II the city'sindustrial base has been developed, with diverse plants producing steel, cars, tractors, and consumer electronics. Warsaw is the second most important industrial regionin Poland (after Katowice in the south). Warsaw, more than anywhere else in the country, has benefited from the boom in construction and commerce that foll...

• Geography - Geography.

  Geographers have developed a standard pattern of map symbols for identifying such cultural features as homes, factories, and churches; dams, bridges, and tunnels;railways, highways, and travel routes; and mines, farms, and grazing lands. C Analyzing Geographic Information Techniques that use mathematics or statistics to analyze data are known as quantitative methods. The use of quantitative methods enables geographers to treat a largeamount of data and a large number of variables in an objectiv...

• Cleveland (Ohio) - geography.

  Cleveland Children’s Museum. Also located in University Circle is Severance Hall, the home of the world-acclaimed Cleveland Orchestra. Nearby is the Cleveland PlayHouse, with three large, restored theaters and one of the largest non-profit professional theaters in the country. Downtown is Playhouse Square Center, with fourrecently restored theaters, home to the Cleveland Opera and the Great Lakes Theater Festival. On the waterfront is the Rock and Roll Hall of Fame and Museum,opened in 1995 and...

• Computer Memory.

  been created, information can be retrieved but not changed. Newer technologies allow ROMs to be semi-permanent—that is, the information can be changed, but ittakes several seconds to make the change. For example, a FLASH memory acts like a ROM because values remain stored in memory, but the values can be changed. C External Memory External memory can generally be classified as either magnetic or optical, or a combination called magneto-optical. A magnetic storage device, such as a computer'shar...

• Moscow (city, Russia) - geography.

  V RECREATION About 30 percent of Moscow’s territory is occupied by parks and public gardens, which were important elements of Soviet city planning. Gorky Park, which providesactivities such as amusement rides and boating, sits on the right bank of the Moscow River; the park’s display of a retired Soviet space shuttle dominates the riverside.The Moscow Zoo is located just west of the city center. The Botanical Gardens, administered by the Russian Academy of Sciences, offers a diverse display of...

• Koala - biology.

  V REPRODUCTION Female koalas become sexually mature around 18 to 24 months of age. They can produce one offspring a year until they reach about 13 years of age. Males begin toproduce sperm around age 2 and, in the absence of older, stronger males, they may breed at that young age. More often, however, a male must grow big enough tocompete with other males for females, and mating generally begins for males at about 4 years of age. The breeding season for koalas is from October to May, during the...

• Elizabeth I I INTRODUCTION Elizabeth I (1533-1603), queen of England and Ireland (1558-1603), daughter of Henry VIII and his second wife, Anne Boleyn.

  Catholic challenges and plots persisted through much of Elizabeth’s reign, and Elizabeth reacted to them strongly. In 1569 a group of powerful Catholic nobles innorthern England rose in rebellion but were savagely repressed. The northern earls were executed, their property and those of their followers was confiscated, and theirheirs were deprived of their inheritance. In 1570 the pope excommunicated Elizabeth, sanctioning Catholic efforts to dethrone her. In 1571 an international conspiracywas u...

• Elizabeth I.

  Catholic challenges and plots persisted through much of Elizabeth’s reign, and Elizabeth reacted to them strongly. In 1569 a group of powerful Catholic nobles innorthern England rose in rebellion but were savagely repressed. The northern earls were executed, their property and those of their followers was confiscated, and theirheirs were deprived of their inheritance. In 1570 the pope excommunicated Elizabeth, sanctioning Catholic efforts to dethrone her. In 1571 an international conspiracywas u...

• Elizabeth I .

  Catholic challenges and plots persisted through much of Elizabeth’s reign, and Elizabeth reacted to them strongly. In 1569 a group of powerful Catholic nobles innorthern England rose in rebellion but were savagely repressed. The northern earls were executed, their property and those of their followers was confiscated, and theirheirs were deprived of their inheritance. In 1570 the pope excommunicated Elizabeth, sanctioning Catholic efforts to dethrone her. In 1571 an international conspiracywas u...

• 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...

• Fossil Fuels.

  water molecules. This crystalline solid is known as gas hydrate. Because technology for the commercial extraction of gas hydrates has not yet been developed, this typeof fossil fuel is not included in most world energy resource estimates. However, in February 2007 the U.S. Department of Energy completed the drilling of a well toretrieve core samples of gas hydrates found in the Prudhoe Bay region of Alaska’s North Slope. By identifying the nature of these gas hydrates, the Energy Departmenthoped...

• Vietnam - country.

  E Natural Resources Vietnam’s most valuable natural resource is its land, particularly the fertile, alluvial soils in the Red and Mekong deltas. Some 29 percent of the land is currently beingcultivated. Vietnam has some valuable mineral resources, including gold, iron, tin, zinc, phosphate, chromite, apatite, and anthracite coal. Most deposits are located in the northernpart of the country. Few attempts were made to extract these minerals until the French takeover of Vietnam at the end of the 1...

• Cold War.

  With this, all the countries of Eastern Europe were under Communist control, and the creation of the Soviet bloc was complete. The events of 1948 contributed to agrowing conviction among political leaders in both the United States and the USSR that the opposing power posed a broad and fundamental threat to their nation’sinterests. The Berlin blockade and the spread of Communism in Europe led to negotiations between Western Europe, Canada, and the United States that resulted in the NorthAtlantic...

• Cold War .

  With this, all the countries of Eastern Europe were under Communist control, and the creation of the Soviet bloc was complete. The events of 1948 contributed to agrowing conviction among political leaders in both the United States and the USSR that the opposing power posed a broad and fundamental threat to their nation’sinterests. The Berlin blockade and the spread of Communism in Europe led to negotiations between Western Europe, Canada, and the United States that resulted in the NorthAtlantic...

• Cold War - U.

  With this, all the countries of Eastern Europe were under Communist control, and the creation of the Soviet bloc was complete. The events of 1948 contributed to agrowing conviction among political leaders in both the United States and the USSR that the opposing power posed a broad and fundamental threat to their nation’sinterests. The Berlin blockade and the spread of Communism in Europe led to negotiations between Western Europe, Canada, and the United States that resulted in the NorthAtlantic...

• Texas - geography.

  D Climate Eastern Texas has a humid subtropical climate, while a semiarid low latitude climate prevails in central areas, and an arid low latitude climate in the extreme west. Alongthe coast the climate is much milder, with fewer extremes in temperatures. Hurricanes sometimes hit the coastal areas of Texas from late July through September, andtornadoes are common in north-central Texas in April and May. D1 Temperature Summers are hot throughout the state, and temperatures exceeding 35°C (95°F)...

• Texas - USA History.

  D Climate Eastern Texas has a humid subtropical climate, while a semiarid low latitude climate prevails in central areas, and an arid low latitude climate in the extreme west. Alongthe coast the climate is much milder, with fewer extremes in temperatures. Hurricanes sometimes hit the coastal areas of Texas from late July through September, andtornadoes are common in north-central Texas in April and May. D1 Temperature Summers are hot throughout the state, and temperatures exceeding 35°C (95°F)...

• Northwest Territories - Geography.

  million years ago by the severe bending (folding) and faulting (breaking) of sedimentary rock that was once part of the Interior Plains. During the Wisconsin Ice Age,alpine glaciers covered the Cordillera, and the movement of the glaciers created razor-sharp peaks and ridges in these mountains. The moving glaciers also createdbroad U-shaped valleys. To the east of the Interior Plains, the ancient rocks of the Canadian Shield are exposed at the Earth’s surface, resulting in a rough, rolling terra...