461 résultats pour "few"

• Acid Rain.

  the Adirondack Mountains of New York State, a quarter of the lakes and ponds are acidic, and many have lost their brook trout and other fish. In the middleAppalachian Mountains, over 1,300 streams are afflicted. All of Norway’s major rivers have been damaged by acid rain, severely reducing salmon and trout populations. E Plants and Animals The effects of acid rain on wildlife can be far-reaching. If a population of one plant or animal is adversely affected by acid rain, animals that feed on tha...

• Coronary Heart Disease.

  when a patient is at rest may indicate that the blood supply of the heart is not normal, and the ECG can often detect damage from a previous heart attack. In anexercise stress test, an ECG is recorded while a patient is performing physical activity such as walking on a treadmill or riding a stationary bicycle. As the intensity ofexercise increases, the doctor looks for specific changes in the ECG that indicate the heart is not getting enough oxygen. In cardiac catheterization, a long, thin, flex...

• Chemical Reaction - chemistry.

  Many groups of elements occur so often as ions that they are given names: nitrate, NO 3-; sulfate, SO 42-; and phosphate, PO 43-. The suffix -ate usually indicates the presence of oxygen. The positive ion, NH 4+, is called ammonium, as in NH 4Cl, ammonium chloride, or (NH 4)3PO4, ammonium phosphate. Rules for naming more complicated compounds exist, but many compounds have been given trivial names—for example, Na 2B4O7·10 H 2O, borax—or proprietary names—F(CF 2)nF, Teflon. These nonsystemat...

• Declaration of Independence.

  communication networks to publicize British actions and encourage demonstrations of defiance. Soon these committees and some colonial legislatures issued a call for anall-colony congress to discuss other appropriate responses to Britain’s actions. The Continental Congress first met in Philadelphia from September to the end of October1774. This body did not plan for war; instead, it debated the extent to which the colonies should carry their resistance to Great Britain. The First Continental Cong...

• Declaration of Independence - U.

  communication networks to publicize British actions and encourage demonstrations of defiance. Soon these committees and some colonial legislatures issued a call for anall-colony congress to discuss other appropriate responses to Britain’s actions. The Continental Congress first met in Philadelphia from September to the end of October1774. This body did not plan for war; instead, it debated the extent to which the colonies should carry their resistance to Great Britain. The First Continental Cong...

• The Souls of Black Folk by W.

  in amused contempt and pity. One ever feels his two-ness,—an American, a Negro; two souls, two thoughts, two unreconciled strivings; two warring ideals in onedark body, whose dogged strength alone keeps it from being torn asunder. The history of the American Negro is the history of this strife—this longing to attain self-conscious manhood, to merge his double self into a better and truer self. Inthis merging he wishes neither of the older selves to be lost. He would not Africanize America, f...

• 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...

• Solar System - astronomy.

  dwarf planets according to the IAU because they have rounded shapes from their own gravity but have not cleared their neighborhoods in space of other objects—bothorbit through the Kuiper Belt, a region beyond Neptune containing thousands of small icy bodies. Pluto and Eris are composed of layers of ice around a rocky core.Ceres qualifies as a dwarf planet because it is spherical but is found in the asteroid belt, a zone between the orbits of Mars and Jupiter that contains thousands of smallrocky...

• Artificial Satellite - astronomy.

  The first stage of a multistage rocket consists of rocket engines that provide a huge amount of force, or thrust. The first stage lifts the entire launch vehicle—with itsload of fuel, the rocket body, and the satellite—off the launch pad and into the first part of the flight. After its engines use all their fuel, the first stage portion of therocket separates from the rest of the launch vehicle and falls to Earth. The second stage then ignites, providing the energy necessary to lift the satellit...

• Extrasolar Planets - astronomy.

  When a planet passes in a front of the star it orbits—an event called a transit—it causes a small dip in the brightness of the star. Measuring the slight change in thebrightness can be used not only to directly detect a planet, but to determine its size and orbit. However, the planet needs to orbit in a plane that lies in a telescope’sline of sight on the star. Despite long odds, Earth-based telescopes have detected and studied a few exoplanets using this method. The first space telescope design...

• Ice Skating.

  cold climate. Competitors for these events are chosen from the best skaters in each participating country, usually through preliminary national competitions. Speedskaters also compete on a World Cup circuit, which pits the world’s best skaters against one another during the year. A Figure Skating The major types of competitive figure skating are individual men’s and women’s competitions, pairs skating, ice dancing, and precision skating. In individualcompetitions a single skater performs requir...

• Heredity - biology.

  allele from the mother and a mutated allele from the father. In both of these cases, the child will be a carrier. The child develops the disease only if he or she receives amutated allele from each parent. When both parents are carriers, there is a 25 percent chance that a child will be disease-free, a 25 percent chance that it will have thedisease, and a 50 percent chance that it will be a carrier. Examples of genetic diseases that follow the dominant-recessive pattern include sickle-cell anemi...

• Anatomy.

  The body defends itself against foreign proteins and infectious microorganisms by means of a complex dual system that depends on recognizing a portion of the surfacepattern of the invader. The two parts of the system are termed cellular immunity, in which lymphocytes are the effective agent, and humoral immunity, based on theaction of antibody molecules. When particular lymphocytes recognize a foreign molecular pattern (termed an antigen), they release antibodies in great numbers; other lymphocy...

• Skin. I INTRODUCTION Skin, outer body covering of an animal. The term skin

  III SKIN APPENDAGES In humans, the skin appendages, or structures embedded in the skin, include hair, nails, and several types of glands. Glands are groups of cells that produce andsecrete substances needed by other parts of the body. In other vertebrates, the skin appendages include scales (in fish and reptiles) and feathers (in birds). Together,the skin and the skin appendages are known as the integumentary system of the body. A Hair Hair is a distinguishing characteristic of mammals, a gro...

• Economics.

  Malthus, nature's check was “positive”: “The power of population is so superior to the power of the earth to produce subsistence for man, that premature death must insome shape or other visit the human race.” The shapes it took included war, epidemics, pestilence and plague, human vices, and famine, all combining to level theworld's population with the world's food supply. The only escape from population pressure and the horrors of the positive check was in voluntary limitation of population, no...

• From "Resistance to Civil Government" - anthology.

  intending it, as God. A very few—as heroes, patriots, martyrs, reformers in the great sense, and men—serve the state with their consciences also, and so necessarily resist it for the most part; and they are commonly treated as enemies by it. A wise man will only be useful as a man, and will not submit to be “clay,” and “stop a holeto keep the wind away,” but leave that office to his dust at least: “I am too high born to be propertied,To be a second at control,Or useful serving-man and instr...

• Soccer's Big Show Comes to the United States.

  There were many doubters, both overseas and within the United States. Some U.S. sportswriters derided the idea of holding the World Cup in the United States asakin to staging the World Series in India—how could there be any local interest? Foreign critics felt that money was the sole reason for FIFA's decision and that thesport was about to be cheapened to make it acceptable to Americans. The rumors flew: FIFA was going to enlarge the goals, it would allow timeouts (unheard of inthe sport) to ac...

• Excerpt from Barnaby Rudge - anthology.

  Mr. Dennis rolled lazily over upon his breast, and resting his chin upon his hand in imitation of the attitude in which Hugh lay, said, as he too looked towards thedoor: “ Ay, ay, you knew him, brother, you knew him. But who'd suppose to look at that chap now, that he could be the man he is! Isn't it a thousand cruel pities, brother,that instead of taking his nat'ral rest and qualifying himself for further exertions in this here honourable cause, he should be playing at soldiers like a boy?...

• 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...

• Washington, D.

  structures built according to L’Enfant’s plan. During the War of 1812, British troops set fire to the White House, destroying its interior. President James Madison and hisfamily lived in the Octagon while the White House was being rebuilt. South of the Federal Triangle is the Mall, a narrow park stretching roughly 1.6 km (1 mi) from the Capitol to the Washington Monument. Although the Mall officially endsat 14th Street, landscaped greenery extends to the Potomac. The Washington Monument, whose m...

• Spread of Islam - History.

  Muhammad died in 632 and was succeeded by Abu Bakr, the father of Muhammad’s favorite wife, Aisha. Abu Bakr was the first caliph ( khalifah, Arabic for “successor”) of Islam. Like Muhammad, Abu Bakr was a member of the Quraysh clan. While neither Abu Bakr nor any subsequent caliph claimed the role of prophet, they wereleaders of this new religious enterprise that was quickly becoming a political entity as well. The first four caliphs, all of whom were selected by some form of council ofMuslims,...

• 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...

• Great Depression in the United States - U.

  prices would continue to rise and they could soon sell their stocks at a profit. The widespread belief that anyone could get rich led many less affluent Americans into the market as well. Investors bought millions of shares of stock “on margin,” arisky practice similar to buying products on credit. They paid only a small part of the price and borrowed the rest, gambling that they could sell the stock at a highenough price to repay the loan and make a profit. For a time this was true: In 1928 the...

• Rain Forest.

  dropped into the heart of the forest by helicopters. Suspended from the crane’s long, movable arm is a large gondola that functions as a mobile treetop laboratory.Moving from tree to tree, forest researchers collect specimens, conduct experiments, and observe life in the canopy frontier. The highest stratum of the rain forest is made up of the emergent trees, those individuals that stick up above the forest canopy. Emergents, which do not form acontinuous layer, are usually the giants of the for...

• History of United States Business.

  their lives. But the rewards were worth it; a few lucrative voyages and a merchant could buy a townhouse, a carriage, perhaps a summer retreat. The merchant couldclimb the social ladder and circulate among the powerful in this highly materialistic society. This prospect of riches and the honor that accompanied them made Americancolonists willing to engage in highly speculative enterprises, such as shipping flour to the West Indies or importing goods from England by the thousands without beingcer...

• Cosmology - astronomy.

  In 1917 American scientist Harlow Shapley measured the distance to several groups of stars known as globular clusters. He measured these distances by using amethod developed in 1912 by American astronomer Henrietta Leavitt. Leavitt’s method relates distance to variations in brightness of Cepheid variables, a class of starsthat vary periodically in brightness. Shapley’s distance measurements showed that the clusters were centered around a point far from the Sun. The arrangement of theclusters was...

• 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...

• War of 1812 - History.

  the thorough training they received in handling guns was far ahead of contemporary British standards. As hostilities loomed, Congress authorized a regular army of 35,000 men, but when the United States officially declared war in June 1812, the actual land force was lessthan 10,000 and nearly half of these soldiers were raw recruits. The existing troops were also widely scattered in small garrisons. The government planned tosupplement this regular force with 50,000 volunteers and 100,000 militiam...

• War of 1812 - U.

  the thorough training they received in handling guns was far ahead of contemporary British standards. As hostilities loomed, Congress authorized a regular army of 35,000 men, but when the United States officially declared war in June 1812, the actual land force was lessthan 10,000 and nearly half of these soldiers were raw recruits. The existing troops were also widely scattered in small garrisons. The government planned tosupplement this regular force with 50,000 volunteers and 100,000 militiam...

• Qing Dynasty - History.

  The Manchus also dealt with the problem of Russian expansion into northeastern Asia. In 1689 the Treaty of Nerchinsk was signed by an envoy from the Manchu courtand a Russian representing Peter the Great. The treaty, the first between China and a Western country, established territorial boundaries and defined rules ofcommerce for the two powers. Through the mid-18th century, the Manchus continued to consolidate their power. In 1720 the Qing ruler sent forces to fight the Mongols in Tibet and the...

• Marriage.

  In many traditional societies, marriage typically involved transfers of property from the parents to their marrying children or from one set of parents to the other. Thesecustoms persist in some places today and are part of the tradition of arranged marriages. For example, in some cultures the bride’s parents may give property (knownas a dowry) to the new couple. The practice of giving dowries has been common in countries such as Greece, Egypt, India, and China from ancient times until thepresen...

• Planetary Science - astronomy.

  III ORIGINS AND COMPOSITIONS OF PLANETS Astronomers believe that planetary systems are formed of elemental materials that were created in the interiors of giant stars. Some of this material comes from giantstars that shed material into space as they age. Most of the matter to form planets, however, comes from stars that explode as supernovas and spread debris enrichedwith the heavier chemical elements into space. According to the currently accepted views, the most likely first stage in the evo...

• Geology.

  terminology. Today the geologic time scale is generally agreed upon and used by scientists around the world, dividing time into eons, eras, periods, and epochs. Everyfew years, the numerical time scale is refined based on new evidence, and geologists publish an update. Geologists use several methods to determine geologic time. These methods include physical stratigraphy, or the placement of events in the order of their occurrence,and biostratigraphy, which uses fossils to determine geologic time...

• North America - Geography.

  D Climate Although North America has considerable climatic variety, five principal climatic regions can be identified. The northern two-thirds of Canada and Alaska, as well as all ofGreenland, have subarctic and arctic climates, in which long, dark, bitterly cold winters alternate with brief, mild summers. Most of the region, which receives relativelylittle precipitation, is covered with snow and ice during much of the year. A second climatic region is made up of the eastern two-thirds of the U...

• Johann Sebastian Bach.

  from his duties, and even tossed him into jail for “too obstinately requesting his dismissal.” But after several weeks the duke saw it was of no use and let him go. E Köthen: 1717-1723 Bach’s new employer, Leopold, loved and understood music and could play the violin, viola da gamba, and harpsichord as well as sing bass. The prince held Bach in highregard and stood as godfather for his seventh child. Bach, in turn, named the child Leopold August in his employer’s honor. Bach later said that the...

• Olympic Games.

  the next decade nearly all the ISFs abolished the distinction between amateurs and professionals, accepting so-called open Games. One of the most visible examples of the policy change came in 1992, when professional players from the National Basketball Association (NBA) were permitted to play inthe Summer Games in Barcelona, Spain. Professionals from the National Hockey League (NHL) became eligible to participate beginning with the 1998 Winter Olympics inNagano, Japan. V CEREMONIES The Olymp...

• Chile - country.

  D Plant and Animal Life The indigenous plant life of Chile varies according to climatic zone. Plant life in the northern region includes brambles and cactus and has little variety. Here, theAtacama provides one of the best examples on Earth of an absolute desert. The more humid Central Valley supports several species of cacti, espino (a thorny shrub),grasses, and the Chilean pine, which bears edible nuts. Dense rain forests are located south of Valdivia with laurel, magnolia, false beech, and v...

• Sweden - country.

  mi) and is Sweden’s second largest lake, after Vänern. The two lakes, together with several smaller lakes, rivers, and canals, form an internal water route called theGöta Canal. Built in the early 19th century, the Göta Canal extends for about 386 km (about 240 mi) and provides a scenic transportation link between the Baltic Sea,at Stockholm, and the Kattegat. Sweden’s other large lakes in the district include Mälaren, Hjälmaren, and the famously picturesque Siljan. D Climate Although one-seven...

• George Washington I INTRODUCTION George Washington (1732-1799), first president of the United States (1789-1797) and one of the most important leaders in United States history.

  A2 Promotion This was Washington’s first experience with the difficulties of raising troops while lacking equipment, clothing, and funds. Apparently he thought his efforts worthy ofsome recognition and successfully applied to Dinwiddie for a lieutenant colonel’s commission. He left Alexandria, Virginia, early in April with about 150 poorly equippedand half-trained troops. A3 First Battles Before he had advanced very far, Washington received news that the French had driven Trent’s men back from...

• George Washington.

  A2 Promotion This was Washington’s first experience with the difficulties of raising troops while lacking equipment, clothing, and funds. Apparently he thought his efforts worthy ofsome recognition and successfully applied to Dinwiddie for a lieutenant colonel’s commission. He left Alexandria, Virginia, early in April with about 150 poorly equippedand half-trained troops. A3 First Battles Before he had advanced very far, Washington received news that the French had driven Trent’s men back from...

• George Washington

  A2 Promotion This was Washington’s first experience with the difficulties of raising troops while lacking equipment, clothing, and funds. Apparently he thought his efforts worthy ofsome recognition and successfully applied to Dinwiddie for a lieutenant colonel’s commission. He left Alexandria, Virginia, early in April with about 150 poorly equippedand half-trained troops. A3 First Battles Before he had advanced very far, Washington received news that the French had driven Trent’s men back from...

• John Elway Leads "The Drive".

  touchdown against a strong defense. Bedlam reigned inside the stadium. In their two previous possessions the Broncos mustered a total of 15 yards. When Elway entered the huddle, however, he cracked a smile. “I couldn't believe it,”Denver receiver Steve Watson told Sports Illustrated. ”He said, ‘If you work hard, good things are going to happen.’ And then he smiled again.” Elway hit running back Sammy Winder for a short gain. After two more short-yardage plays, Elway shifted into high gear....

• Montréal - geography.

  Place Jacques-Cartier, MontréalPlace Jacques-Cartier is named for the French explorer who was one of the first Europeans to venture into Canada in the 16thcentury. It is a popular spot in the city of Montréal, Québec’s largest city.R.E. Murowchick/Photo Researchers, Inc. French influence lasted for a time after the British conquest of 1760, as shown by some late 18th-century houses. British influence came to prevail, however, and most ofOld Montréal is in fact a Victorian Style city, probably th...

• Ape - biology.

  previous infant has been weaned. This process—like all aspects of ape development—takes a remarkable length of time. A gibbon is weaned by the age of about 2years, while chimps take more than 4 years. Like young monkeys, young apes are carried by their mothers. They either cling to the mother's belly or, in the case ofolder chimps, ride on her back. In great apes, infant care is largely the job of the females, while in some gibbons the mother hands over responsibility to the fatherwhen the infan...

• The Four-Minute Mile.

  The nervous runners false-started once before setting off cleanly. As planned, Chris Brasher led Bannister through the first half-mile. After a half lap (200 meters),Bannister called out to his teammate: “Faster! Faster!” Accelerating, the runners sped through the first quarter-mile in 57.5 seconds-ahead of pace. At 600 meters,Stampfl shouted from the infield: “Relax! Relax!” Running smoothly behind Brasher, Bannister reached the half-mile mark in 1 min 58.2 sec. Chataway sprinted into the l...

• Argentina Wins World Cup.

  Dutch team responded with two unanswered goals to earn the victory. In the consolation match Brazil squeaked past Italy, 2-1, in what was the final high-profileappearance of Brazilian star Roberto Rivelino, a three-time World Cup participant. The championship match was held at Río de la Plata stadium in Buenos Aires on Sunday, June 25. In a classic match-up, a methodical, disciplined European teamplayed against a spontaneous, mercurial South American squad. According to Argentina's coach, Ce...

• Kuiper Belt - astronomy.

  III RESEARCH The Kuiper Belt is an exciting area of research in astronomy. The discovery and astronomical exploration of the Kuiper Belt over the past decade have fueled arevolution in scientists’ views of the solar system. Today astronomers recognize the Kuiper Belt as the third major region of the solar system (the other two regions arethe inner solar system, with its small rocky planets, and the outer solar system, with its gas-giant planets). They believe that the belt helps explain Pluto’...

• Austin Wins the US Open.

  from Friday to Saturday. Austin's coach, Robert Landsdorp, sensed she was slightly off her game and urged Austin to spend the extra day on the practice court. Staring across the net at the two-time Wimbledon champion, Austin opened the match against Navratilova with a double fault. Austin dropped the first game and fellbehind in the second game before coming alive. She won three straight games, twice breaking Navratilova's serve to pull ahead 3-1. Playing with a veteran's savvy,Austin made a...

• Bullfighting.

  V THE GREAT MATADORS Ranking the great matadors is highly subjective. Most aficionados would agree, however, that the following names must be included in any list of the modern greats:Rodolfo Gaona, Armillita (Fermín Espinosa), and Arruza, of Mexico; and Belmonte, Manolete, and Antonio Ordoñez, of Spain. Few South Americans have made an impacton the international bullfighting world. Although several North Americans have attempted careers as matadors, only Sidney Franklin and John Fulton Short m...

• Prokaryote - biology.

  earliest organisms to evolve, an estimated 3.4 billion to 3.5 billion years ago. The environment of the early Earth lacked oxygen, and cyanobacteria probably usedfermentation (a chemical process performed without the presence of oxygen) to produce the energy molecule adenosine triphosphate (ATP). Cyanobacteria introduced oxygen into the atmosphere through the process of photosynthesis. As the oxygen content in the atmosphere increased over the centuries, bacteria evolved that usedthis oxygen in...