48 résultats pour "completely"

• Comparative Anatomy.

  In comparing two species, anatomists have to be careful to differentiate between homologous structures, which are ones that have evolved from a shared ancestor, andanalogous structures, which have developed from different origins. Homologous structures are built on the same underlying plan. A human arm, a bat’s wing, and awhale’s flipper look quite different from the outside, but the bones inside reveal that these limbs all have the same basic structure. Analogous structures, by contrast,often l...

• Space Shuttle - astronomy.

  The two SRBs, with their combined thrust of some 26 million newtons (about 5.8 million lb), provide most of the power for the first two minutes of flight. The SRBs takethe space shuttle to an altitude of 45 km (28 mi) and a speed of 4,973 km/h (3,094 mph) before they separate and fall back into the ocean to be retrieved,refurbished, and prepared for another flight. After the boosters fall away, the three main engines continue to provide thrust. These engines are clustered at the rear end of the...

• A Communist regime since 1945 and completely cut off from the outside world for thirty years, Albania opened its frontiers in 1990.

• Ice Hockey.

  Each period begins with a face-off at the blue dot at center ice. During the face-off one player from each team lines up at the dot with the stick blade on the ice. After the referee drops the puck, the two players attempt to gain possession of it. Quick hands and strength are essential qualities for players participating in the face-off. Once the puck is dropped, it is in play until an official’s whistle stops it, a goal is scored, or time expires. The team on offense tries to move the puck f...

• Global Warming.

  some of the warming influence of increasing greenhouse gases. A1 Carbon Dioxide Carbon dioxide is the second most abundant greenhouse gas, after water vapor. Carbon dioxide constantly circulates in the environment through a variety of naturalprocesses known as the carbon cycle. It is released into the atmosphere from natural processes such as eruptions of volcanoes; the respiration of animals, whichbreathe in oxygen and exhale carbon dioxide; and the burning or decay of plants and other organic...

• Insects.

  parents. It does not have wings. It may not even have legs. As the insect grows, it starts to changeshape. This change is called metamorphosis. There are two kinds of metamorphosis, called incompleteand complete. Dragonflies, grasshoppers, and crickets are some insects that go through incomplete metamorphosis asthey grow up. The young insects are called nymphs or naiads. The young insect molts, or crawls out ofits exoskeleton, as it grows bigger. It grows a new, larger exoskeleton. Its body chan...

• Sexually Transmitted Infections.

  D Genital Herpes Genital herpes is caused by infection with the herpes simplex virus (HSV). Most cases of genital herpes are due to HSV type 2. Some cases, however, result from genitalinfections with HSV type 1, a common cause of cold sores. Genital herpes causes recurrent outbreaks of painful sores on the genitals, although the disease oftenremains dormant with no symptoms for long periods. In the United States, one in five individuals over the age of 12 is infected with HSV type 2, and the va...

• Los Angeles - geography.

  size and population) among all the cities in Los Angeles County. It is irregular in shape because it has grown over the years through the annexation of surrounding territoryand cities. The city proper is shaped like a lighted torch, its narrow handle extending north from the Port of Los Angeles to downtown Los Angeles, and its flames flickeringirregularly to the north, west, and northwest. Several separate cities—such as Beverly Hills, Santa Monica, and Culver City—are partly or completely surro...

• Greenhouse Effect.

  addition, humans cut down huge tracts of trees for lumber or to clear land for farming or building. This process, known as deforestation, can both release the carbonstored in trees and significantly reduce the number of trees available to absorb carbon dioxide. As a result of these human activities, carbon dioxide in the atmosphere is accumulating faster than Earth’s natural processes can absorb the gas. By analyzing airbubbles trapped in glacier ice that is many centuries old, scientists have d...

• Helicopter.

  naturally flaps down so as to increase lift. Flapping allows the differences in lift caused by uneven rotor tip speed to cancel out, producing a stable ride. Many helicoptersuse mechanical hinges with lubricated bearings, but some use flexible straps made of a composite material in order to reduce the required maintenance. Helicopters require different amounts of lift and thrust at different times during flight, because the aerodynamic forces acting on them change during hovering andacceleration...

• Air Pollution.

  Several pollutants attack the ozone layer. Chief among them is the class of chemicals known as chlorofluorocarbons (CFCs), formerly used as refrigerants (notably in airconditioners), as agents in several manufacturing processes, and as propellants in spray cans. CFC molecules are virtually indestructible until they reach thestratosphere. Here, intense ultraviolet radiation breaks the CFC molecules apart, releasing the chlorine atoms they contain. These chlorine atoms begin reacting withozone, br...

• Environment.

  escape into space of the infrared energy radiated back out by Earth. This process is referred to as the greenhouse effect. These gases, primarily carbon dioxide,methane, nitrous oxide, and water vapor, insulate Earth’s surface, helping to maintain warm temperatures. Without these gases, Earth would be a frozen planet with anaverage temperature of about -18°C (about 0°F) instead of a comfortable 15°C (59°F). If the concentration of these gases rises, they trap more heat within theatmosphere, caus...

• Christianity.

  history of architecture. See Basilica; Church; Early Christian Art and Architecture;Prayer. C Christian Life The instruction and exhortation of Christian preaching and teaching concern all the themes of doctrine and morals: the love of God and the love of neighbor, the twochief commandments in the ethical message of Jesus (see Matthew 22: 34-40). Application of these commandments to the concrete situations of human life, bothpersonal and social, does not produce a uniformity of moral or polit...

• Manhattan Project - U.

  other possible uses of nuclear energy, such as using uranium to operate large power plants or, perhaps, as power sources for ships or submarines. Then Nazi Germanyinvaded Poland on September 1, 1939, and Europe plunged into war. The scientists realized that any plans to build large-scale nuclear power plants would have to waituntil the war was over. Two weeks after the invasion of Poland, Hitler made a radio speech in which he threatened Britain with “a weapon against which there is no defense.”...

• Austria - country.

  Wildlife is generally scarce in Austria. Chamois, deer, and marmot are still present; bear, which were once abundant, are now almost completely absent. Hunting isstrictly regulated to protect the remaining species. F Environmental Issues Industrial emissions, a high volume of tourist traffic, and significant air pollution from other countries—principally the former East Germany, Slovakia, and the CzechRepublic—combine to make acid rain the major environmental problem in Austria. One-quarter of...

• Franklin D.

  Roosevelt entrusted his campaign management to the journalist Louis McHenry Howe. Howe, a genius at politics, performed brilliantly. Henceforth, Roosevelt and Howewere to be almost inseparable, and Howe, a wizened and colorful little man, guided the political fortunes of the Hyde Park aristocrat. B Assistant Secretary of the Navy Even before his reelection to the New York legislature, Roosevelt had entered the national political arena by taking part in the campaign of Governor Woodrow Wilson of...

• Franklin D.

  Roosevelt entrusted his campaign management to the journalist Louis McHenry Howe. Howe, a genius at politics, performed brilliantly. Henceforth, Roosevelt and Howewere to be almost inseparable, and Howe, a wizened and colorful little man, guided the political fortunes of the Hyde Park aristocrat. B Assistant Secretary of the Navy Even before his reelection to the New York legislature, Roosevelt had entered the national political arena by taking part in the campaign of Governor Woodrow Wilson of...

• Greek Art and Architecture - USA History.

  The struggle between these two city-states and their allies ultimately led to the Peloponnesian War (431-404 BC), which Sparta won. Despite this conflict, the 5th century, often called the Classical period, is usually considered the culmination of Greek art, architecture, and drama, with its highest achievements being the Temple ofZeus at Olympia, the Parthenon in Athens, and the plays of Athenian dramatists Aeschylus, Sophocles, Euripides, and Aristophanes. The 4th century, or Late Classical p...

• Reproduction - biology.

  E Gestation After fertilization of the egg, the resulting zygote undergoes cell division and differentiation to form the embryo. In most higher plants, the embryo is enclosed in a layerof nutritive material surrounded by a hard outer covering, forming the seed. In most lower animals the embryo, surrounded by the nutritive material of the formerovum, is enveloped by a leathery or calcareous shell and is extruded from the body of the female. Animals, such as birds, that lay their eggs before the...

• what did you do?

  ceilings, theplates, thewindows, thelampshades! Wasitan act ofrebellion! Anact ofexpression! Werethepaintings good, orwas that beside thepoint! Ineeded tosee itfor myself, andIneeded totell the world about it!Iused tolive for reporting likethat! Stalin found outabout thecommunity andsent histhugs in,just afew days before Igot there, to break alloftheir arms! Thatwasworse thankilling them! Itwas ahorrible sight,Oskar: theirarms incrude splints, straight infront ofthem likezombies! Theycouldn't fe...

• Crafts.

  VI POTTERY Ceramic objects can be molded completely by hand or thrown (shaped) on a potter's wheel, a device with a rotating horizontal disk. When the clay hardens, it is fired ina high-temperature oven, or kiln, to strengthen it. To make the object waterproof, glazes may then be applied and the piece fired again. Although hand construction iseasy to master, throwing on the potter's wheel requires practice. Several simple tools are used by potters, including sponges, trimming tools, wooden sha...

• 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...

• Military Religious Orders .

  Hospitalers’ charitable functions were playing a secondary role to their military duties. Successes in war defending the Holy Land enriched the order with vast gifts ofproperty in Europe and Palestine. In the 12th century the Hospitalers acquired three impressive fortresses in Palestine at Krak des Chevaliers, Belvoir, and Margat. Atthe height of their power in the 13th century, the Hospitalers regularly supplied 500 knights to defend the Latin Kingdom of Jerusalem against the Empire. The Crusad...

• Neptune (planet) - astronomy.

  The gaseous atmosphere of Neptune contains hydrogen, helium, and about 3 percent methane. It extends about 5,000 km (about 3,000 mi) above the planet’s ocean.Light reflected from Neptune’s deep atmosphere is blue, because the atmospheric methane absorbs red and orange light but scatters blue light. In 1998 astronomersalso identified molecules of methyl in Neptune’s atmosphere. Methyl molecules each contain one carbon atom and three hydrogen atoms. Methyl molecules are knownas hydrocarbon radical...

• Diving (sport).

  water that creates a larger, more noticeable splash after the diver’s body displaces water under the surface. To minimize this upjet, top-level divers make a quickswimming motion by releasing their hands and collapsing their arms as they submerge. Instead of a large splash, the surface of the water appears to boil as the airbubbles rise from the diver’s entry. For feetfirst entries, which are rare in top-level competitions, divers place their legs and feet together while pointing their toes down...

• National Socialism .

  VII THE PARTY IN THE REICHSTAG The movement grew rapidly, recruiting thousands of discharged civil servants, ruined shopkeepers and small-business owners, impoverished farmers, workersdisillusioned with the Socialist and Communist parties, and a host of frustrated and embittered young people of all classes, brought up in the postwar years and withouthope of personal economic security. In the Reichstag elections of 1930 the National Socialists polled almost 6.5 million votes (more than 18 perce...

• Gothic Art and Architecture I INTRODUCTION Notre Dame Cathedral, Paris Notre Dame Cathedral, in Paris, was begun in 1163 and completed for the most part in 1250.

  and by external arches, called flying buttresses. Consequently, the thick walls of Romanesque architecture could be largely replaced by thinner walls with glass windows,and the interiors could reach unprecedented heights. A revolution in building techniques thus occurred. With the Gothic vault, a ground plan could take on a variety of shapes. The general plan of the cathedrals, however, consisting of a long three-aisled nave interceptedby a transept and followed by a shorter choir and sanctuary,...

• Coral Reef.

  sensitive to particles of mud or sediment settling on them, which means that corals rarely grow close to rivers or other sources of sediment. In the sea, light is filteredout by depth, so reef-building corals can only grow in relatively shallow water. Even in the clearest oceans few reef-building corals grow below a depth of 80 to 100 m(260 to 328 ft). Although corals need nutrients, they cannot thrive in areas where there are large amounts of nutrients. Typically, microscopic organisms in the p...

• 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...

• Reformation .

  Saxony, he made war against the Schmalkaldic League, a defensive association of Protestant princes. The Roman Catholic forces were successful at first. Later,however, Duke Maurice went over to the Protestant side, and Charles V was obliged to make peace. The religious civil war ended with the religious Peace of Augsburg in1555. Its terms provided that each of the rulers of the German states, which numbered about 300, choose between Roman Catholicism and Lutheranism and enforcethe chosen faith up...

• Pottery I INTRODUCTION Pottery, clay that is chemically altered and permanently hardened by firing in a kiln.

  basket, or a clay or plaster form. Liquid clay can be poured into plaster molds. A pot can be coil built: Clay is rolled between the palms of the hands and extended intolong coils, a coil is formed into a ring, and the pot is built up by superimposing rings. Also, a ball of clay can be pinched into the desired shape. The most sophisticatedpottery-making technique is wheel throwing. The potter's wheel, invented in the 4th millennium BC, is a flat disk that revolves horizontally on a pivot. Both...

• Cat Family - biology.

  cats have coats that are mainly brown, yellow, or gray, often with white underbellies. The cubs of many species of cats have spotted coats, which helps hide them ingrass and underbrush from predators. Adult cats that have mainly spotted patterns in their fur include cheetahs, leopards, clouded leopards, jaguars, ocelots, margays, Geoffroy’s cat, and servals. Singlecolor coats are found in lions, pumas, and jaguarundis. Some individuals among leopards and jaguars, and more rarely in other species...

• Native American Art.

  folding, braiding or weaving, could also be sewn onto the hide. The production of decorated clothing and bags increased after contact with Europeans as a greater variety of textiles and other materials became available throughtrade. Imported glass beads inspired native women, who quickly adapted quillwork techniques for the creation of beaded apparel. European curvilinear and floraldesigns of the 19th century proved as meaningful for the native women who worked with them as they were for the non...

• Bicycle.

  narrow as possible to minimize weight and interference with pedaling. F Specialty Bicycles Many other types of bicycles are designed for special purposes. Although not as common as standard single-rider racing, touring, mountain, or recreational bicycles,they nonetheless have significant niches. Recumbent bicycles are bicycles on which the rider sits upright as if in a chair, with legs and feet stretched out in front. Because they support the rider’s lower back,recumbents allow the rider far mo...

• Hungary - country.

  Northern Hungary lacks sufficient water, especially between July and October, when precipitation levels are typically low. Canals irrigate the Great Hungarian Plain,which is subject to drought. Because of the country’s mainly flat terrain, only limited water resources can be harnessed for hydroelectric power. F Environmental Issues Rapid industrialization in Hungary following World War II contributed significantly to a number of major environmental problems, including air, water, and soil pollu...

• Newfoundland and Labrador - Geography.

  Precipitation averages about 1,120 mm (about 44 in) yearly in Newfoundland. In Labrador precipitation varies from about 1,020 mm (about 40 in) in the southeast toabout 510 mm (about 20 in) in the extreme north. Heavy winter snowfalls are common, especially in Newfoundland. D Plant Life About one-third of Newfoundland is forested, and most of the rest of the island is made up of barren areas of reindeer moss and lichens. The forests consist almostentirely of conifers. The most important species...

• Newfoundland and Labrador - Canadian History.

  Precipitation averages about 1,120 mm (about 44 in) yearly in Newfoundland. In Labrador precipitation varies from about 1,020 mm (about 40 in) in the southeast toabout 510 mm (about 20 in) in the extreme north. Heavy winter snowfalls are common, especially in Newfoundland. D Plant Life About one-third of Newfoundland is forested, and most of the rest of the island is made up of barren areas of reindeer moss and lichens. The forests consist almostentirely of conifers. The most important species...

• Woodrow Wilson.

  daughters. In 1885 Wilson also accepted a position with the newly opened Bryn Mawr College, a school for women near Philadelphia. Wilson was not particularly patient with womenas intellectual associates and did not enjoy his teaching duties. He was, however, able to pursue his writing. A University Professor In 1888 Wilson left Bryn Mawr for a professorship in history and political economy at Wesleyan University in Connecticut. There, in 1889, he published The State, a lengthy textbook analyz...

• Woodrow Wilson

  daughters. In 1885 Wilson also accepted a position with the newly opened Bryn Mawr College, a school for women near Philadelphia. Wilson was not particularly patient with womenas intellectual associates and did not enjoy his teaching duties. He was, however, able to pursue his writing. A University Professor In 1888 Wilson left Bryn Mawr for a professorship in history and political economy at Wesleyan University in Connecticut. There, in 1889, he published The State, a lengthy textbook analyz...

• Los Angeles - geography.

  (2006 population, 472,494), located east of the Port of Los Angeles. The city of Compton (95,701) is located north of Long Beach, on the east side of the AlamedaCorridor. On the other side of the corridor are the cities of Torrance (142,350) and Inglewood (114,914). Northwest of Inglewood and west of downtown Los Angeles are the wealthy and fashionable Santa Monica (88,050) and Beverly Hills (34,979). Both cities are enclaves:Santa Monica is surrounded by the City of Los Angeles to the north, ea...

• Los Angeles - geography.

  (2006 population, 472,494), located east of the Port of Los Angeles. The city of Compton (95,701) is located north of Long Beach, on the east side of the AlamedaCorridor. On the other side of the corridor are the cities of Torrance (142,350) and Inglewood (114,914). Northwest of Inglewood and west of downtown Los Angeles are the wealthy and fashionable Santa Monica (88,050) and Beverly Hills (34,979). Both cities are enclaves:Santa Monica is surrounded by the City of Los Angeles to the north, ea...

• Medicine.

  C Other Health Professionals Medicine is not restricted to physicians. A wide variety of health care practitioners work in this exciting field. By far the largest professional group is nurses. Registerednurses help physicians during examinations, treatment, and surgery. They observe, evaluate, and record patients’ symptoms, administer medications, and provideother care ( see Nursing). Nurse practitioners perform basic duties once reserved for physicians, such as diagnosing and treating common i...

• Race - biology.

  distributed as a cline, generally varying along a north-south line. Skin color is lightest in northern Europeans, especially in those who live around the Baltic Sea, andbecomes gradually darker as one moves toward southern Europe, the Mediterranean, the Middle East, and into northern Africa and northern subtropical Africa. Skin isdarkest in people who live in the tropical regions of Africa. The lack of clear-cut discontinuities makes any racial boundary based on skin color totally arbitrary. Sim...

• Georgia (state) - geography.

  B Rivers and Lakes Most of the rivers of Georgia drain eastward to the Atlantic Ocean proper or southward to the Gulf of Mexico. Only a few flow northward to the Tennessee River, which isa major tributary of the Mississippi River. Most of the rivers flowing to the coasts are navigable by barges and small craft as far upstream as the Fall Line. The major river flowing to the Atlantic is the Savannah River, which, with the Tugaloo River, one of its headwaters, forms most of the state’s eastern bo...

• Georgia (state) - USA History.

  B Rivers and Lakes Most of the rivers of Georgia drain eastward to the Atlantic Ocean proper or southward to the Gulf of Mexico. Only a few flow northward to the Tennessee River, which isa major tributary of the Mississippi River. Most of the rivers flowing to the coasts are navigable by barges and small craft as far upstream as the Fall Line. The major river flowing to the Atlantic is the Savannah River, which, with the Tugaloo River, one of its headwaters, forms most of the state’s eastern bo...

• Native Americans of North America.

  addition to smallpox and measles, explorers and colonists brought a host of other diseases: bubonic plague, cholera, typhoid fever, scarlet fever, pleurisy, mumps,diphtheria, pneumonia, whooping cough, malaria, yellow fever, and various sexually transmitted infections. Despite the undisputed devastation wreaked on Indian populations after European contact, native populations showed enormous regional variability in their response todisease exposure. Some peoples survived and, in some cases, even...

• Native Americans of North America - Canadian History.

  addition to smallpox and measles, explorers and colonists brought a host of other diseases: bubonic plague, cholera, typhoid fever, scarlet fever, pleurisy, mumps,diphtheria, pneumonia, whooping cough, malaria, yellow fever, and various sexually transmitted infections. Despite the undisputed devastation wreaked on Indian populations after European contact, native populations showed enormous regional variability in their response todisease exposure. Some peoples survived and, in some cases, even...

• On the road