1327 résultats pour "than"

• 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...

• United States History - U.

  and improved upon the designs of Arab sailing ships and learned to mount cannons on those ships. In the 15th century they began exploring the west coast ofAfrica—bypassing Arab merchants to trade directly for African gold and slaves. They also colonized the Madeira Islands, the Azores, and the Cape Verde Islands andturned them into the first European slave plantations. The European explorers were all looking for an ocean route to Asia. Christopher Columbus sailed for the monarchs of Spain in 149...

• United States History - U.

  and improved upon the designs of Arab sailing ships and learned to mount cannons on those ships. In the 15th century they began exploring the west coast ofAfrica—bypassing Arab merchants to trade directly for African gold and slaves. They also colonized the Madeira Islands, the Azores, and the Cape Verde Islands andturned them into the first European slave plantations. The European explorers were all looking for an ocean route to Asia. Christopher Columbus sailed for the monarchs of Spain in 149...

• 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...

• Wyoming (state) - geography.

  The basins, which lie in the rain shadow of mountains, are very dry, with an average annual precipitation of about 250 mm (about 10 in) or less; the Great Plains regionhas an annual average of about 380 mm (about 15 in), and the Black Hills region receives slightly more. Thunderstorms and hailstorms are relatively frequent insummer. The annual snowfall ranges from about 500 mm (about 20 in) in the Bighorn Basin to well over 5,100 mm (over 200 in) in the higher mountains, where annualprecipitatio...

• Wyoming (state) - USA History.

  The basins, which lie in the rain shadow of mountains, are very dry, with an average annual precipitation of about 250 mm (about 10 in) or less; the Great Plains regionhas an annual average of about 380 mm (about 15 in), and the Black Hills region receives slightly more. Thunderstorms and hailstorms are relatively frequent insummer. The annual snowfall ranges from about 500 mm (about 20 in) in the Bighorn Basin to well over 5,100 mm (over 200 in) in the higher mountains, where annualprecipitatio...

• 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...

• 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...

• Middle East - Geography.

  though overall they have improved considerably since the 1970s. This variation reflects the different levels of wealth and development in countries of the Middle East. Inthe highly developed country of Israel the infant mortality rate was 8 deaths per 1000 live births in 1997. By comparison, the rate per 1000 live births was 71 in less-developed Egypt and 75 in Yemen. A Ethnic Groups and Languages Arabs make up the majority of the people of the Middle East, accounting for almost the entire popu...

• Boston - geography.

  The neighborhoods of Allston and Brighton occupy the northwest corner of the city to the west of Fenway. The Allston-Brighton area is bordered to the east, north, andwest by the Charles River and to the south by the Massachusetts Turnpike and the town of Brookline. It is an industrial and residential neighborhood that is also thelocation of Boston College and Harvard University Business School. Boston has been unsuccessful in annexing Brookline, the birthplace of U.S. president John F.Kennedy an...

• 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...

• 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...

• Carbon - chemistry.

  Graphite is black and slippery and conducts electricity. In graphite, the atoms form planar, or flat, layers. Each layer is made up of rings containing six carbon atoms.The rings are linked to each other in a structure that resembles the hexagonal mesh of chicken wire. Each atom has three sigma bonds (with 120° between any two ofthe bonds) and belongs to three neighboring rings. The fourth electron of each atom becomes part of an extensive pi bond system. Graphite conducts electricity,because th...

• Ancient Greece - history.

  Palace of KnossosThe ancient city of Knossos was a center of the Minoan civilization, an advanced society on Crete named after Minos, a legendaryCretan king. Skilled in such fields as engineering and architecture, the Minoans constructed the palace at Knossos in 1700 bc. Aserious fire at least three centuries later caused the collapse of the palace and foreshadowed the subsequent decline of the city.Wolfgang Kaehler Settlers had begun sailing from Asia Minor to Crete about 6000 BC because the i...

• Skiing.

  Safety is very important to all skiers, and all Alpine resorts have a ski patrol. The ski patrol’s responsibility is to take care of injured skiers, to mark hazardous spots ontrails, to make sure that trails are in good condition before opening them, and, at times, to act as traffic police in congested areas. Skiers are also responsible for takingtheir own safety into consideration, as well as that of others. Anyone who participates in the sport should be aware of the Skier’s Responsibility Code...

• Water Pollution.

  Cryptosporidium in the water supply of Milwaukee, Wisconsin, sickened more than 400,000 people and killed more than 100. H Thermal Pollution Water is often drawn from rivers, lakes, or the ocean for use as a coolant in factories and power plants. The water is usually returned to the source warmer than when itwas taken. Even small temperature changes in a body of water can drive away the fish and other species that were originally present, and attract other species in placeof them. Thermal pol...

• Health Care System in Canada.

  With a few exceptions, provincial health plans cover all medically necessary services, so that patients need not pay directly for anything except so-called incidental costs.These incidental costs include items such as a patient’s private hospital room, unless it is specified by a physician, and transportation to the hospital. Provincial healthplans also do not cover some nonessential procedures, such as laser surgery for the eye, cosmetic surgery, procedures to reverse sterilization, and, in mos...

• Democratic Party.

  At the beginning of the 20th century the Democrats’ minority position among voters remained central to their existence. The Progressive split in Republican rankshelped elect Woodrow Wilson twice, but the entry of the United States into World War I ended that. The war, popular at first, backfired against the Wilsonadministration when large numbers of German Americans and Irish Americans protested with their votes against U.S. involvement on England’s side. The result wasanother Republican landsli...

• 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...

• Valley.

  Except in mountainous terrain, rivers are almost always flanked by floodplains. Floodplains are flat wide deposits of alluvium, river-deposited sediment, on either side of the river channel. During floods, a river overflows its banks and spreads out the sediment near the river to form a floodplain. Floodplains of large rivers, such as thoseof the Mississippi River, can be flat areas tens of kilometers across. River channels migrate back and forth across their floodplains as alluvium is repeate...

• Valley - Geography.

  Except in mountainous terrain, rivers are almost always flanked by floodplains. Floodplains are flat wide deposits of alluvium, river-deposited sediment, on either side of the river channel. During floods, a river overflows its banks and spreads out the sediment near the river to form a floodplain. Floodplains of large rivers, such as thoseof the Mississippi River, can be flat areas tens of kilometers across. River channels migrate back and forth across their floodplains as alluvium is repeate...

• Church of Jesus Christ of Latter-day Saints.

  yearly visited a book written in a hieroglyphic script on golden plates buried in a nearby hill; the book’s location, he said, had been disclosed to him by an angel. In 1830he completed the translation of these plates, “by the gift and power of God,” and published the Book of Mormon, which he believed to be a religious record of theancient inhabitants of North America. On April 6, 1830, he organized the Church of Christ, soon known by its present title, the Church of Jesus Christ of Latter-daySa...

• Confucianism.

  IV NEO-CONFUCIANISM After centuries of intellectual and cultural dominance by Buddhism, China began to experience a revival of Confucian thought during the Tang dynasty ( AD 618-907). It was led by poet and essayist Han Yu (Han Yü). Han Yu attacked Buddhism and Daoism, which he believed had kept government officials from seeing how they couldhelp the people. To further public welfare, he urged them to study the way of the ancient sages through the Five Classics . Han Yu almost lost his life f...

• From The Hunchback of Notre Dame - anthology.

  If then we were to attempt to penetrate through this thick and obdurate bark to the soul of Quasimodo; if we could sound the depths of this bungling piece oforganization; if we were enabled to hold a torch behind these untransparent organs, to explore the gloomy interior of this opaque being, to illumine its obscure cornersand its unmeaning cul-de-sacs, and to throw all at once a brilliant light upon the spirit enchained at the bottom of this den; we should doubtless find the wretch in some mi...

• Reconstruction (U.

  Instead, Congress began a lengthy debate over Reconstruction policy. The program eventually enacted resulted from a series of compromises among Republicanfactions; the Radicals were never powerful enough to gain everything they sought. Still, fueled by anger at the president's refusal to compromise and at the appearanceof former Confederates returning to power throughout the South, members of Congress moved increasingly toward the Radicals. The key Reconstruction measuresenacted aimed to produce...

• Redshift - astronomy.

  Astronomers can also use redshift to identify the oldest and most distant objects in the observable universe. Astronomers believe that quasars are the most distantobjects in the universe, because they have some of the largest redshifts. Quasars are objects in space that strongly emit radio waves. Astronomers originally namedthese objects quasars, which stands for quas i-stell ar (or starlike) radio source, because they appear as points of light, like stars, in photographs of the sky. When astro...

• Comedy

  Socrates suffered in the comedy of Aristophanes. Throughout history, opposition to comedy and laughter has been strongest in societies which emphasize physical restraint, decorum and conformity. Many medieval monastic orders had statutes forbidding laughter. The Puritan and Victorian eras saw many condemnations of comedy and laughter. The more authoritarian the regime, the greater its suppression of comedy. Hitler even set up ‘joke courts' to punish those who made fun of his regime - one Berl...

• Obesity.

  of a day, contributing to the development of obesity. V TREATMENTS FOR OBESITY Obesity can become a chronic lifelong condition caused by overeating, physical inactivity, and even genetic makeup. No matter what the cause, however, obesity can beprevented or managed with a combination of diet, exercise, behavior modification, and in severe cases, weight-loss medications and surgery. A Diets The most common and conservative treatment for obesity utilizes a nutritionally balanced, low calorie diet...

• From As You Like It - anthology.

  ROSALIND : Ay, and twenty such. ORLANDO : What sayst thou? ROSALIND : Are you not good? ORLANDO : I hope so. ROSALIND : Why then, can one desire too much of a good thing? [ To CELIA ] Come, sister, you shall be the priest and marry us.—Give me your hand, Orlando.—What do you say, sister?ORLANDO : [to CELIA ] Pray thee, marry us. CELIA : I cannot say the words. ROSALIND : You must begin, 'Will you, Orlando'— CELIA : Go to. Will you, Orlando, have to wife this Rosalind? ORLANDO : I will. ROSALIND...

• Bowling.

  In each of the first nine frames the bowler rolls one or two balls. If the bowler knocks down all ten pins with the first ball, he or she has rolled a strike, the best roll possible. An X is recorded on the scoresheet or screen, and the bowler receives ten points (the number of pins knocked down) plus a bonus of the number of pins thebowler knocks down in his or her next two bowls. The maximum possible score in a strike frame, therefore, is 30: the strike followed by two more strikes on subseq...

• Laser.

  their atoms into laser light. Consequently, they are the most powerful continuous wave (CW) lasers—that is, lasers that emit light continuously rather than in pulses. C Liquid Lasers The most common liquid laser media are inorganic dyes contained in glass vessels. They are pumped by intense flash lamps in a pulse mode or by a separate gas laserin the continuous wave mode. Some dye lasers are tunable, meaning that the color of the laser light they emit can be adjusted with the help of a prism lo...

• Birds.

  Birds need much less sleep than people do. One seabird, called the sooty tern, can fly for years bytaking “naps” that last only a few seconds. Most birds that live on land are active during the day and sleep at night. Owls are just the opposite.They sleep during the day and hunt at night. Birds usually sleep in shrubs, on tree branches, in holes in trees, or on the ground. Most ducks sleep onthe water. Many birds sleep while they are standing. MATING AND BREEDING Many kinds of birds have only on...

• 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...

• 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...

• Tiger - biology.

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

• Social Psychology.

  During the 1960s, American psychologist Stanley Milgram studied a form of social influence stronger than conformity: obedience to authority. In a famous series ofexperiments that attracted controversy about human research ethics, Milgram put each of 1,000 subjects into a situation in which they were ordered by anexperimenter to administer painful electric shocks to a confederate (who did not actually receive any shocks). The subjects in these studies were led to believe that theywere acting as '...

• Elementary Particles I INTRODUCTION Structure of Matter Modern physics has revealed successively deeper layers of structure in ordinary matter.

  The most fundamental particles that make up matter fall into the fermion category. These fermions cannot be split into anything smaller. The particles that carry theforces acting on matter and antimatter are bosons called force carriers. Force carriers are also fundamental particles, so they cannot be split into anything smaller.These bosons carry the four basic forces in the universe: the electromagnetic, the gravitational, the strong (force that holds the nuclei of atoms together), and the wea...

• United States Senate.

  providing for military forces, and declaring war. Article I, Section 8, also gives Congress implied powers—to “make all laws which shall be necessary and proper” forcarrying out the enumerated powers, and to investigate and oversee the executive branch. The Senate also has the power to conduct impeachment trials against thepresident, federal judges, and other officials. The Senate can only impeach someone after the House brings charges, however. A two-thirds majority vote of thesenators in the c...

• Meteorology.

  to find the corresponding relative humidity and dew-point temperature. III SPECIAL METEOROLOGICAL INSTRUMENTS Meteorologists have developed several sophisticated instruments that measure multiple physical characteristics of the air simultaneously and at more than one location.The most important of these special instruments are radiosondes, Doppler radar, and weather satellites. A Radiosonde A radiosonde measures air temperature, air pressure, and humidity from the earth’s surface up to an alt...

• Rocket.

  the vacuum of space, however, demonstrated that this belief was not true. In fact, rockets produce more thrust in the vacuum of space than on Earth. Air pressure andfriction with the air reduce a rocket’s thrust by about 10 percent on Earth as compared to the rocket’s performance in space. B Thrust and Efficiency Thrust is a measurement of the force of a rocket, or the amount of “push” exerted backward to move a rocket forward. Thrusts vary greatly from rocket to rocket.Engineers measure thrust...

• Rocket - astronomy.

  the vacuum of space, however, demonstrated that this belief was not true. In fact, rockets produce more thrust in the vacuum of space than on Earth. Air pressure andfriction with the air reduce a rocket’s thrust by about 10 percent on Earth as compared to the rocket’s performance in space. B Thrust and Efficiency Thrust is a measurement of the force of a rocket, or the amount of “push” exerted backward to move a rocket forward. Thrusts vary greatly from rocket to rocket.Engineers measure thrust...

• Psychotherapy.

  Other managed-care companies pay therapists a set fee to meet with a client for up to a specified maximum number of sessions depending on the nature of theproblem, free of interference from case reviewers. For example, a managed-care firm may pay a therapist $200 to hold up to eight sessions with a person. If the clientuses all eight sessions, the therapist normally loses money. But if treatment stops after two or three sessions, the therapist makes a profit. This relatively new system iscontrov...

• Earthquake.

  III CAUSES Most earthquakes are caused by the sudden slip along geologic faults. The faults slip because of movement of the Earth’s tectonic plates. This concept is called theelastic rebound theory. The rocky tectonic plates move very slowly, floating on top of a weaker rocky layer. As the plates collide with each other or slide past eachother, pressure builds up within the rocky crust. Earthquakes occur when pressure within the crust increases slowly over hundreds of years and finally exceeds...

• Health Insurance.

  needs services. Essentially, individuals make regular payments to the plan rather than having to pay especially large sums at any one time in the event of sudden illnessor injury. In this way, the group as a whole funds expensive treatments for those few who need them. Many people believe that in addition to providing financial stability, health insurance can promote good health. Supporters of this idea claim that by lowering thepersonal cost of services, insurance induces individuals to seek he...

• Electricity I INTRODUCTION Electricity, one of the basic forms of energy.

  electrons in the neutral object are attracted to the positive object. Some of these electrons flow to the side of the neutral object that is nearest to the positive object.This side of the neutral object accumulates electrons and becomes negatively charged. Because electrons leave the far side of the neutral object while its protonsremain stationary, that side becomes positively charged. Since the negatively charged side of the neutral object is closest to the positive object, the attraction bet...

• Golf. I INTRODUCTION Golf, outdoor game in which individual players use specially designed

  caddie or caddy. (Caddies, once an integral feature of the game, have now been replaced on many courses by motorized carts and pull carts.) In England the game was made popular by the attention given it by James VI of Scotland, later James I of England, and his son Charles I. In the 18th century the first golf associations were established. They included the Honourable Company of Edinburgh Golfers (founded 1744) in Edinburgh, Scotland;the Saint Andrews Society of Golfers (1754) in Saint Andrew...

• 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...

• Finland - country.

  Productive forestland is the most valuable natural resource of Finland. Spruce, pine, and silver birch are the principal trees used to manufacture wood and pulp andpaper products. Finland lacks coal and petroleum resources and is a net importer of energy resources. However, Finland does have significant deposits of peat, which is cut from thenumerous peat bogs that cover much of the north. Peat is an important heat source for homes, and it provides about 7 percent of Finland’s electricity needs....

• 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...