940 résultats pour "known"

• 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...

• Alphabet I INTRODUCTION Bengali Script India developed a number of different writing systems over the course of its history.

  A Pictographic and Ideographic Systems Early systems of writing used pictures to represent things and then to represent the sounds of those things. Pictographic writing, in which a simplified picture of the sunstood for the word sun, was probably the first step toward a written language. Chinese began as a pictographic language. To represent abstract ideas, the Chinese writing system combined pictographs. For example, the pictographs for sun and tree were combined to represent the concept of...

• Asteroid - astronomy.

  Asteroids of the S type, related to the stony iron meteorites, make up about 15 percent of the total population of asteroids that can be seen from Earth. Much rarer arethe M-type objects, corresponding in composition to the meteorites known as “irons.” These objects are made up of an iron-nickel alloy and may represent the cores ofbodies that were large enough to differentiate into layers and to melt deep inside. Their rocky outer layers may have been removed by impacts with other asteroids . A...

• Comedy I INTRODUCTION Laurel and Hardy Stan Laurel, in overalls, and Oliver Hardy, left, formed one of the most popular comedy teams in motion-picture history.

  The elements and techniques of comedy are diverse and differ from culture to culture. More than tragedy or serious drama, comic entertainment is controlled by socialconventions that define the boundaries of acceptable humor and topics that are taboo or off-limits for humor. What is considered funny in one place and time may beforbidden culturally or viewed as infantile or in poor taste in another. Virtually every component of human behavior is subject to comic treatment. This includes bodilyfunc...

• Aksum.

  doctrine that Christ was both divine and human. The Council of Chalcedon condemned Monophysitism in 451, and since that time the Coptic Church has beenindependent of other Christian churches. After the Council of Chalcedon, priests who continued to teach Monophysitism were persecuted in the eastern Roman Empire, and many migrated to Aksum. The influxof priests, along with the support of the royal family, strengthened missionary efforts in Aksum. Many churches and monasteries were founded after 4...

• Beetle - biology.

  cut, or crush prey. Beetles that consume nectar from flowers use tubelike mouthparts to suck up nectar like a primitive straw. C Thorax The thorax, the body region behind the head, consists of three segments that provide attachments for the legs and wings. Each segment of the thorax carries a pair oflegs. The middle segment also bears the stiff wing sheaths called elytra, and the hind segment holds the membranous hind wings. D Legs Beetles have six jointed legs, each leg with five parts. The f...

• Animation I INTRODUCTION Finding Nemo A clown fish named Marlin, left, and his friend Dory search for Marlin's son in the computer-animated feature film Finding Nemo (2003).

  Animator at WorkAnimators use computers for every part of the animation process, from creating a storyboard (a scene-by-sceneillustration of the plot) to imitating camera movement. This animator is creating a scene for the motion picture Antz(1998).C. Lepetit/Liaison Agency If an animator is basing the animation project on drawings, one of the most common animation techniques, he or she will first create a series of rough sketches thatoften will be filmed in a pencil test (simple line drawings...

• Earth (planet).

  Milky Way to complete one revolution around the Galaxy’s center. Earth’s axis of rotation is inclined (tilted) 23.5° relative to its plane of revolution around the Sun. This inclination of the axis creates the seasons and causes the height of the Sun in the sky at noon to increase and decrease as the seasons change. The Northern Hemisphere receives the most energy from the Sun when it is tiltedtoward the Sun. This orientation corresponds to summer in the Northern Hemisphere and winter in the S...

• Earth (planet) - astronomy.

  Milky Way to complete one revolution around the Galaxy’s center. Earth’s axis of rotation is inclined (tilted) 23.5° relative to its plane of revolution around the Sun. This inclination of the axis creates the seasons and causes the height of the Sun in the sky at noon to increase and decrease as the seasons change. The Northern Hemisphere receives the most energy from the Sun when it is tiltedtoward the Sun. This orientation corresponds to summer in the Northern Hemisphere and winter in the S...

• 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...

• 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...

• Spider (arthropod) - biology.

  The spider’s abdomen is soft and saclike. On the underside of the tip of the abdomen are three pairs of spinnerets. Each spinneret is studded with many fine, hairliketubes called spigots, which produce a variety of silk threads. The spigots lead to several large silk glands inside the abdomen. Silk is formed as a liquid inside theseabdominal glands. As the silk is drawn out through the spigots, protein molecules within the silk line up parallel to one another, causing the silk to harden and form...

• Canadian Literature I INTRODUCTION Canadian Literature, literature of the peoples of Canada.

  William Henry DrummondPoet William Henry Drummond described the lives of French Canadian farmers, loggers, and rural workers in verse thatreflected their mix of French and English speech. He gained recognition in the late 19th and early 20th centuries.Library of Congress In the early 19th century, most Canadian poetry imitated earlier British poetry. Poets Oliver Goldsmith (grandnephew of the Anglo-Irish writer of the same name),Charles Sangster, Charles Mair, and Levi Adams exemplified literary...

• Sumer - history.

  By the 23rd century BC the power of the Sumerians had declined to such an extent that they could no longer defend themselves against foreign invasion. The Semitic ruler Sargon I (reigned about 2335-2279 BC), called The Great, succeeded in conquering the entire country. Sargon founded a new capital, called Agade, in the far north of Sumer and made it the richest and most powerful city in the world. The people of northern Sumer and the conquering invaders, fusing gradually, became known ethnical...

• Holy Roman Empire I INTRODUCTION Holy Roman Empire, political entity of lands in western and central Europe, founded by Charlemagne in AD 800 and dissolved by Emperor Francis II in 1806.

  acquired the imperial title and an area running from the North Sea through Lotharingia (Lorraine) and Burgundy to northern Italy; Louis II received East Francia (theGerman duchies of Saxony, Swabia, and Bavaria). In 870 Lothair’s middle kingdom was divided by the Treaty of Mersen, which gave Lotharingia to East Francia and therest to West Francia. This division created the foundation for today’s states of Germany and France, respectively; however, in the 9th century these were highly fractured d...

• Holy Roman Empire .

  acquired the imperial title and an area running from the North Sea through Lotharingia (Lorraine) and Burgundy to northern Italy; Louis II received East Francia (theGerman duchies of Saxony, Swabia, and Bavaria). In 870 Lothair’s middle kingdom was divided by the Treaty of Mersen, which gave Lotharingia to East Francia and therest to West Francia. This division created the foundation for today’s states of Germany and France, respectively; however, in the 9th century these were highly fractured d...

• American Music I INTRODUCTION American Music, the folk, popular, and classical music of the United States--created by American-born or American-trained composers, or originating in American culture, or written primarily for American audiences.

  The country's first permanent orchestra was the New York Philharmonic Society, founded in 1842. Among the first symphonic and operatic composers the mostprominent was William Henry Fry, who composed the first opera by an American ( Leonora, 1845). Fry is best remembered, however, for four symphonies written in the 1850s and 1860s. George F. Bristow wrote the first opera on an American theme; his Rip Van Winkle was performed in New York City in 1855. Town bands, a popular form of community mu...

• Antelope - biology.

  antelopes still display complex patterns of behavior, although much of it is instinctive rather than learned. In open habitats, antelopes run a high risk of predation (being preyed upon). To survive they use several kinds of defensive strategy, including living in herds. Herd living ensures that many pairs of eyes and ears are on the alert for danger. Herd living also gives individuals a better chance of avoiding attack, because predators canchoose from many potential targets. When danger thre...

• London (England) - geography.

  In the northern part of the West End is Bloomsbury, the city’s traditional intellectual center, with its concentration of bookshops and homes of writers and academics. Inthe early 20th century a number of famous writers, critics, and artists who lived here became known as the Bloomsbury Group. Here, too, is the British Museum, one ofLondon’s chief tourist attractions. Nearby is the giant complex of the University of London, whose various colleges and departments have taken over much ofBloomsbury...

• Paris (city, France) - geography.

  Théâtre Musical de Paris and the Théâtre de la Ville. Just north of the Hôtel de Ville is the Pompidou Center, also known as Beaubourg, an arts complex devoted to modern and contemporary art and design. The structure,in steel and glass and featuring brightly colored, exposed pipes and ducts, is the work of Italian architect Renzo Piano and British architect Richard Rogers. Itscontroversial pop-art design contrasts sharply with the overall gray hue of the city, and was criticized by many followin...

• Star (astronomy) - astronomy.

  absorbing the missing colors of light. For example, the set of dark lines made by hydrogen includes a dark red line, the set of dark lines made by sodium includes a pairof dark yellow lines, and the set of dark lines made by iron includes lines of nearly every color. Each element in the gaseous outer layer of a star produces its ownparticular pattern of dark spectrum lines, depending on the temperature and pressure of the gas. Astronomers have observed spectrum lines, or spectra, for hundredsof...

• Animal Behavior - biology.

  The first motor program analyzed in much detail was the egg-rolling response of geese. When a goose sees an egg outside its nest, it stares at the egg, stretches itsneck until its bill is just on the other side of the egg, and then gently rolls the egg back into the nest. At first glance this seems a thoughtful and intelligent piece ofbehavior, but it is a mechanical motor program; almost any smooth, rounded object (the sign stimulus) will release the response. Furthermore, removal of the egg on...

• 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...

• Uruguay (country) - country.

  Freedom of religion is guaranteed by the constitution of Uruguay. Three-quarters of the people belong to the Roman Catholic Church. There are also sizable Protestantand Jewish congregations. The official language is Spanish, which in Uruguay has been influenced by Italian vocabulary and pronunciation. C Education Uruguay has one of the highest rates of literacy in Latin America, at 98.2 percent of the adult population. Six years of primary education is compulsory, and Uruguay isone of the few n...

• Paris (city, France) - geography.

  and its vibrant public square, frequented by street performers, soon became among the most popular landmarks in the city. West of the Pompidou Center is Les Halles, the site of the central market of Paris from the 12th century until 1969. The market was subsequently replaced by the Forum LesHalles, a multilevel underground complex featuring a shopping mall, museums, the Paris film library ( vidéothèque ), and a sports center. The street level of Les Halles features a garden, the Jardin des Halle...

• Rap I INTRODUCTION Jay-Z Rapper Jay-Z rose to popularity with such albums as Vol.

  Run-DMCTypically in rap music, vocalists recite rhyming lyrics in time to a beat that may be sampled from prerecorded music byother groups. Black youths developed rap music on the streets of inner cities in the United States during the 1970s, butthe style has expanded to include a wider variety of performers and audiences. The rap group Run-DMC, shown here, wasa powerful early influence in the genre. The group helped bring rap music into the mainstream when it released “WalkThis Way” (1986), a s...

• Babylonia - USA History.

  Pharmacology, too, doubtless had made considerable progress, although the only major direct evidence of this comes from a Sumerian tablet written several centuriesbefore Hammurabi. C Legal System and Writing Law and justice were key concepts in the Babylonian way of life. Justice was administered by the courts, each of which consisted of from one to four judges. Often theelders of a town constituted a tribunal. The judges could not reverse their decisions for any reason, but appeals from their...

• African Literature I INTRODUCTION African Literature, oral and written literature produced on the African continent.

  that few scholars of African culture know any African languages, and few Africans know an African language other than their own. The best-known literatures in Africanlanguages include those in Yoruba and Hausa in West Africa; Sotho, Xhosa, and Zulu in southern Africa; and Amharic, Somali, and Swahili in East Africa. In West Africa, Yoruba writing emerged after Bishop Ajayi Crowther, a former slave, developed a script for the language and in 1900 published the first Yorubatranslation of the Bible...

• William Shakespeare I INTRODUCTION William Shakespeare (1564-1616), English playwright and poet, recognized in much of the world as the greatest of all dramatists.

  Shakespeare’s reputation today is, however, based primarily on the 38 plays that he wrote, modified, or collaborated on. Records of Shakespeare’s plays begin toappear in 1594, when the theaters reopened with the passing of the plague that had closed them for 21 months. In December of 1594 his play The Comedy of Errors was performed in London during the Christmas revels at Gray’s Inn, one of the London law schools. In March of the following year he received payment for two playsthat had been per...

• William Shakespeare.

  Shakespeare’s reputation today is, however, based primarily on the 38 plays that he wrote, modified, or collaborated on. Records of Shakespeare’s plays begin toappear in 1594, when the theaters reopened with the passing of the plague that had closed them for 21 months. In December of 1594 his play The Comedy of Errors was performed in London during the Christmas revels at Gray’s Inn, one of the London law schools. In March of the following year he received payment for two playsthat had been per...

• Portraiture I INTRODUCTION Portraiture, visual representation of individual people, distinguished by references to the subject's character, social position, wealth, or profession.

  CaracallaCaracalla is a Roman portrait bust in marble of the emperor Marcus Aurelius Antoninus, probably done circa ad 215. Theson of Septimius Severus, Caracalla (as he was known) was a brutal man whose qualities come through in this piece withits dramatic realism. The bust, which is now in the Louvre, Paris, evidently served as the inspiration for Michelangelo’sbust of Brutus more than one thousand years later.Bridgeman Art Library, London/New York The first representations of identifiable ind...

• Fungus - biology.

  Many fungi can reproduce by the fragmentation of their hyphae. Each fragment develops into a new individual. Yeast, a small, single-celled fungus, reproduces bybudding, in which a bump forms on the yeast cell, eventually partitioning from the cell and growing into a new yeast cell. V CLASSIFICATION OF FUNGI Scientists have long disagreed about how to classify fungi, and the classification systems are still developing. The first description of fungi was published in 1729 byItalian botanist Pier...

• Baseball.

  pitcher or argue a call with an umpire. Two or more coaches, positioned closer to the field, assist the manager by communicating with the players. For example,managers may decide what pitches should be thrown, when batters should swing at a pitch, and how runners should move around the bases. The manager relays thesedecisions through special hand signals that the coaches repeat to communicate to the players. Umpires are responsible for interpreting and enforcing the rules of play. They rule on...

• USA - Iraq War - History.

  B Making the Case for War B1 “Neoconservatives” and the Bush Doctrine Long before President George W. Bush took office in 2001, elements in or close to the Republican Party had called repeatedly for firmer U.S. steps against Iraq,including a war if necessary to force a regime change. One such group authored a white paper in 1996 called A Clean Break: A New Strategy for Securing the Realm , which was later sent to Prime Minister Benjamin Netanyahu, leader of Israel’s Likud Party. It advocated...

• U.S.-Iraq War - U.S. History. I INTRODUCTION U.S.-Iraq War, military action begun in

  B Making the Case for War B1 “Neoconservatives” and the Bush Doctrine Long before President George W. Bush took office in 2001, elements in or close to the Republican Party had called repeatedly for firmer U.S. steps against Iraq,including a war if necessary to force a regime change. One such group authored a white paper in 1996 called A Clean Break: A New Strategy for Securing the Realm , which was later sent to Prime Minister Benjamin Netanyahu, leader of Israel’s Likud Party. It advocated...

• Drug. I INTRODUCTION Drug, substance that affects the function of living cells, used

  normalizing chemical activity in the emotional centers of the brain. Antianxiety drugs, also referred to as tranquilizers, treat anxiety by decreasing the activity in theanxiety centers of the brain. Sedative-hypnotic drugs are used both as sedatives to reduce anxiety and as hypnotics to induce sleep. Sedative-hypnotic drugs act by reducing brain-cell activity.Stimulant drugs, on the other hand, increase neuronal (nerve cell) activity and reduce fatigue and appetite. Analgesic drugs reduce pain...

• 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...

• 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...

• Orthodox Church.

  formally defined by an ecumenical council, as it was in Catholicism, some Orthodox theologians have taught that the act of becoming a monk or the service of burial canalso be sacraments. The sacramental practice of the Orthodox differs in many details from Western customs. Baptism is administered by immersing the child or adult three times under thewater, each time in the name of one of the persons of the Trinity. It is followed immediately by anointment with chrism, a sacred perfumed oil that r...

• Roman Mythology.

  Her temple on the Aventine Hill in Rome was a center for organizations of skilled craftspeople. According to tradition, in 509 BC the dynasty of Etruscan kings ended and the Roman Republic was founded. The republic was ruled by two chief magistrates, called consuls, who were elected by the people to one-year terms. During the time of the republic, the Capitoline temple became the most important public shrine of theRoman people and the focus of public worship. Each January, the new consuls offer...

• New Orleans - geography.

  D Metropolitan Region The New Orleans metropolitan region covers 8,800 sq km (3,400 sq mi) and includes the counties—known in Louisiana as parishes— of Orleans, Jefferson, Saint Bernard, Saint Charles, Saint John the Baptist, Saint Tammany, Saint James, and Plaquemines. At the center is the city of New Orleans, which is coextensive withOrleans Parish. It has a land area of 468 sq km (181 sq mi). Extending from this base are numerous suburban towns in the surrounding parishes. Metairie, Harahan...

• Tragedy I INTRODUCTION Euripides Unlike other 5th-century BC Greek playwrights, tragic poet Euripides addressed the plight of the common people, rather than that of mythic heroes.

  SenecaSeneca was a Roman philosopher, dramatist, and statesman. His tragedies later influenced Renaissance dramatists,including William Shakespeare. The bust of Seneca shown here is a Roman copy of a Greek original.Art Resource, NY Aeschylus is one of the best known of the ancient Greek tragic playwrights. The author of some 90 plays, he established many of the conventions of the tragic dramaticform, which he perfected throughout his career. Aeschylus's skillful use of poetic language and brilli...

• Dog Family - biology.

  muzzles, long and bushy tails, and large ears. Many foxes hunt by stalking prey and then leaping on it with a distinctive, stiff-legged pounce. Once thought to besolitary animals, foxes are now known to live in groups of up to six individuals. The remaining canids are each highly distinctive. Raccoon dogs and bush dogs are the least doglike canids in appearance. Raccoon dogs, found in eastern Asia, havestubby legs, a stout body, short ears, shaggy fur, and a black face mask that resembles a racc...

• Folk Art I INTRODUCTION Carved Native American Figure This figure of a Native American trapper was carved from a single pine log (about 1850-1890).

  that young Native American women were taught to weave by Ursuline nuns. The overall spirit of French-Canadian folk art is colorful, happy, and, at the same time,devout. B Anglo-Canadian Folk Art The English tradition in the Maritime provinces is strong in the decoration of utilitarian objects, in graining, marbling, and incising, and in ship carvings (both figureheadsand stern-board decorations). The emigration to Canada of many New Englanders during and after the American Revolution led to int...

• Birding - biology.

  swallows, and rock doves nest on buildings in cities, towns, and farms. The chimney swift has abandoned hollow trees for chimneys as a nest site in urban areas.Mallards and Canada geese—once exclusively wild, migratory species—now live year-round in the open spaces found in city parks and golf courses. Nearly all purplemartins, a songbird species that once used the abandoned nests of woodpeckers or the natural cavities of cliffs or dead trees, now live primarily in structures specificallyconstru...

• Electric Motors and Generators.

  the armature. It is often desirable to generate as high a voltage as possible, and rotating armatures are not practical in such applications because of the possibility of sparkingbetween brushes and slip rings and the danger of mechanical failures that might cause short circuits. Alternators are therefore constructed with a stationary armaturewithin which revolves a rotor composed of a number of field magnets. The principle of operation is exactly the same as that of the AC generator described,...

• 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...

• Native American Languages.

  From Nahuatl, spoken in Middle America, come avocado, cacao, cocoa, chile/chili, chocolate, coyote, tamale , tomato , and many others. Contributions from South American languages include jaguar, cashew, tapioca, and toucan from Tupinambá; alpaca, condor, jerky, llama, puma, and quinine from Quechua; and barbecue, canoe, guava, hammock, hurricane, iguana, maize, papaya, and potato from Maipurean (Arawakan). Native American languages, in turn, have borrowed words from European language...