806 résultats pour "much"

• Cambio climático - ciencias de la naturaleza.

  relevante que influye en la dinámica del clima en la Tierra. El hielo presente en las regiones polares proporciona datos sobre la composición de la antigua atmósfera de la Tierra. Los núcleos de hielo analizados por los científicos,procedentes de las placas de hielo de Groenlandia y de la Antártida, ofrecen información sobre la temperatura y los gases de efecto invernadero presentes en la atmósferade hace cientos de miles de años. Las capas de estos núcleos de hielo formadas por las nevadas esta...

• Stem Cell.

  The medical profession used adult stem cells to treat diseases long before anyone isolated one. In 1968 scientists performed the first successful bone marrowtransplant, a procedure in which a patient receives an infusion of healthy bone marrow cells. The purpose of such transplants is to restore the blood-making capabilitiesof the patient’s diseased bone marrow after extremely strong chemotherapy has destroyed that bone marrow. From the beginning investigators suspected that stemcells in the inf...

• Exercise.

  broad, and most studies suggest a positive relationship between physical fitness and mental achievement. The relationship between regular aerobic exercise and cardiovascular health and longevity is well established. Regular exercise leads to a reduction in the risk ofcoronary heart disease, in which fatty deposits (plaque) form in blood vessels supplying the muscular wall of the heart, compromising oxygen delivery to the heartmuscle. In addition, with regular exercise the efficiency of the heart...

• Automation.

  Not all industries require the same degree of automation. Agriculture, sales, and some service industries are difficult to automate. The agriculture industry may becomemore mechanized, especially in the processing and packaging of foods; however, in many service industries such as supermarkets, for example, a checkout countermay be automated and the shelves or supply bins must still be stocked by hand. Similarly, doctors may consult a computer to assist in diagnosis, but they must makethe final...

• Ludwig van Beethoven I INTRODUCTION Ludwig van Beethoven Ludwig van Beethoven is considered possibly the greatest Western composer of all time.

  the other hand, breaks up the opening theme into contrasting segments in different tempi, whereas customary practice called for stating the theme in its entirety at thebeginning of a movement. In the first movement of the Eroica Symphony, one of the major works from Beethoven’s middle period, he again sought ways to expand upon the prevailing musical forms. At that time, composers usually organized movements in three major parts. First, the exposition introduces the musical themes of the pie...

• From "The Metamorphosis" - anthology.

  As all this was running through his mind at top speed without his being able to decide to leave his bed—the alarm clock had just struck a quarter to seven—therecame a cautious tap at the door behind the head of his bed. 'Gregor,' said a voice—it was his mother's—'it's a quarter to seven. Hadn't you a train to catch?' Thatgentle voice! Gregor had a shock as he heard his own voice answering hers, unmistakably his own voice, it was true, but with a persistent horrible twittering squeakbehind it lik...

• Spanish Empire.

  Spain’s royal government quickly imposed its own officials, first to collect taxes and then to administer the colony. Its goal was to assert royal control over both settlersand indigenous peoples. In Spain the government established a House of Trade to supervise colonial affairs and to oversee, license, and tax all trade and commerce. Asthe royal government asserted more authority over colonial activities, Columbus lost effective power, and was eventually replaced by other colonial governors. Wi...

• Spanish Empire .

  Spain’s royal government quickly imposed its own officials, first to collect taxes and then to administer the colony. Its goal was to assert royal control over both settlersand indigenous peoples. In Spain the government established a House of Trade to supervise colonial affairs and to oversee, license, and tax all trade and commerce. Asthe royal government asserted more authority over colonial activities, Columbus lost effective power, and was eventually replaced by other colonial governors. Wi...

• Pez - ciencias de la naturaleza.

  Anatomía externa de un pezEsta ilustración muestra las principales características anatómicas externas de los peces. Algunas especies no tienen todas las aletasque aparecen en la ilustración y otras carecen de escamas u opérculo.© Microsoft Corporation. Reservados todos los derechos. En general, los peces tienen forma ahusada, con el cuerpo moderadamente aplanado en los lados y más afilado en la zona de la cola que en la de la cabeza. Sus principalesrasgos son el juego de vértebras repetido en s...

• Maryland - geography.

  Maryland has no large natural lakes. The largest body of water is a reservoir, Deep Creek Lake, which has a surface area of only 18 sq km (7 sq mi). It lies on theAllegheny Plateau, behind a dam on a tributary of the Youghiogheny River. C Coastline The deeply indented shoreline has a length of 5,134 km (3,190 mi), of which only 50 km (31 miles) fronts on the Atlantic Ocean. The most significant coastal feature isChesapeake Bay. In the bay are many islands and Kent Island is the largest. The sta...

• Maryland - USA History.

  Maryland has no large natural lakes. The largest body of water is a reservoir, Deep Creek Lake, which has a surface area of only 18 sq km (7 sq mi). It lies on theAllegheny Plateau, behind a dam on a tributary of the Youghiogheny River. C Coastline The deeply indented shoreline has a length of 5,134 km (3,190 mi), of which only 50 km (31 miles) fronts on the Atlantic Ocean. The most significant coastal feature isChesapeake Bay. In the bay are many islands and Kent Island is the largest. The sta...

• Nebraska - geography.

  by natural resource districts to limit the rate of pumping for irrigation. C Climate Nebraska has a typical continental climate with wide seasonal variations in temperature. C1 Temperature Winter temperatures below -20°C (0° F) and summer temperatures in the upper 30°s C (lower 100°s F) are common. The average January temperature varies from about -7° C (about 20° F) in the northeast to about -2° C (about 29° F) in the southwest. The average for July, thehottest month, ranges from about 26° C...

• Nebraska - USA History.

  by natural resource districts to limit the rate of pumping for irrigation. C Climate Nebraska has a typical continental climate with wide seasonal variations in temperature. C1 Temperature Winter temperatures below -20°C (0° F) and summer temperatures in the upper 30°s C (lower 100°s F) are common. The average January temperature varies from about -7° C (about 20° F) in the northeast to about -2° C (about 29° F) in the southwest. The average for July, thehottest month, ranges from about 26° C...

• Frank Lloyd Wright I INTRODUCTION Robie House The Frederick C.

  Hills/DeCaro HouseAmerican architect Frank Lloyd Wright, a pioneer of modern architecture, lived and worked in the Chicago area during thelate 19th and early 20th centuries. He designed many single-family houses, known as prairie houses. The Hills/DeCarohouse in Oak Park, west of Chicago, is one of more than 20 houses Wright designed while living in the town between 1890and 1910.© 2007 Frank Lloyd Wright Foundation / Artists Rights Society (ARS), New York / Photo: Mary Ann Hemphill/Photo Researc...

• Corazón - ciencias de la naturaleza.

  Implantación quirúrgica de una válvula cardiacaLos cirujanos realizan intervenciones a corazón abierto para abrir las arterias obstruidas y reparar las lesiones físicas del corazónoriginadas por algún proceso lesivo, como un infarto. Este tipo de cirugía también se puede utilizar para corregir cardiopatíascongénitas, incluyendo la reposición de válvulas cardiacas defectuosas.David Leah/Science Source/Photo Researchers, Inc. Los trastornos del corazón son responsables de mayor número de muertes q...

• mention," I stirred my coffee.

  GOOGOLPLEX   As for the bracelet Momworetothe funeral, whatIdid was Iconverted Dad'slastvoice message intoMorse code,andI used sky-blue beadsforsilence, maroon beadsforbreaks between letters,violetbeads forbreaks between words,and long andshort pieces ofstring between thebeads forlong andshort beeps, whichareactually calledblips,Ithink, or something. Dadwould haveknown. Ittook menine hours tomake, andIhad thought aboutgivingitto Sonny, the homeless personwhoIsometimes seestanding outsidetheAllia...

• Black Death.

  disappeared in the West. V DISAPPEARANCE OF PLAGUE Plague became less common in Europe after the 1530s. The last plague in England was in 1665, the last in Western Europe in 1722. Numerous theories have beenoffered to explain the disappearance of plague. It has been argued that black rats, the primary carriers of plague, may have been replaced by larger brown rats that donot carry the infection. A second theory suggests that increased immunity among the rodents that carried the disease or chang...

• Black Death .

  disappeared in the West. V DISAPPEARANCE OF PLAGUE Plague became less common in Europe after the 1530s. The last plague in England was in 1665, the last in Western Europe in 1722. Numerous theories have beenoffered to explain the disappearance of plague. It has been argued that black rats, the primary carriers of plague, may have been replaced by larger brown rats that donot carry the infection. A second theory suggests that increased immunity among the rodents that carried the disease or chang...

• 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...

• Midnighters

• Himalayas - geography.

  result of deforestation the habitat of most of the wildlife has been destroyed. They are now restricted to special protected areas such as the Jaldapara and Kazirangasanctuaries in India ( see Kaziranga National Park) and the Chitawan preserve in Nepal. There are few animals in the Middle Himalayas because of extensive deforestation. In the Great Himalayas musk deer, wild goats, sheep, wolves, and snow leopards are found. The existence of the Abominable Snowman or Yeti has beenreported by highla...

• Lima (Peru) - geography.

  home to a wide range of museums, many focusing on Peru’s indigenous heritage. These include the National Museum of Anthropology and Archaeology, the GoldMuseum of Peru, the Museum of the Central Reserve Bank, and the Rafael Larco Herrera Museum, which specializes in pre-Hispanic ceramics. Art and history museumsare also found in metropolitan Lima, including the National Museum of the Republic, the Museum of Peruvian Culture, and the Museum of the Inquisition, in the buildingwhere colonial Cathol...

• Thailand - country.

  E Natural Resources Thailand possesses a range of mineral resources. Tin is mined in the peninsula. Important gemstones, such as sapphires, are found in the southeast, and coal reserves,particularly lignite, are in the north. Fish are abundant in rivers and coastal waters. In addition to being consumed domestically, fish are also exported. F Climate Thailand experiences a typical monsoon climate. Winds blow from the northeast during the winter months of October to March or April (known as the...

• Artificial Intelligence.

  Work in AI has primarily focused on two broad areas: developing logic-based systems that perform common-sense and expert reasoning, and using cognitive andbiological models to simulate and explain the information-processing capabilities of the human brain. In general, work in AI can be categorized within three research anddevelopment types: symbolic, connectionist, and evolutionary. Each has characteristic strengths and weaknesses. A Symbolic AI Symbolic AI is based in logic. It uses sequences...

• Thomas Jefferson I INTRODUCTION Thomas Jefferson (1743-1826), third president of the United States (1801-1809) and author of the Declaration of Independence.

  Jefferson was a poor speaker, but his literary talents made him a highly valued member of committees when resolutions and other public papers were drafted. Heemerged as the recognized author of the patriot cause in Virginia and indeed in the whole of the colonies. Jefferson's first public paper, however, was considered toostiff and formal, and it was rewritten. The paper was a response to the greeting of the new governor, Lord Botetourt, to the General Assembly. Jefferson, who nevertook criticis...

• Thomas Jefferson.

  Jefferson was a poor speaker, but his literary talents made him a highly valued member of committees when resolutions and other public papers were drafted. Heemerged as the recognized author of the patriot cause in Virginia and indeed in the whole of the colonies. Jefferson's first public paper, however, was considered toostiff and formal, and it was rewritten. The paper was a response to the greeting of the new governor, Lord Botetourt, to the General Assembly. Jefferson, who nevertook criticis...

• Thomas Jefferson

  Jefferson was a poor speaker, but his literary talents made him a highly valued member of committees when resolutions and other public papers were drafted. Heemerged as the recognized author of the patriot cause in Virginia and indeed in the whole of the colonies. Jefferson's first public paper, however, was considered toostiff and formal, and it was rewritten. The paper was a response to the greeting of the new governor, Lord Botetourt, to the General Assembly. Jefferson, who nevertook criticis...

• Thomas Jefferson - USA History.

  Jefferson was a poor speaker, but his literary talents made him a highly valued member of committees when resolutions and other public papers were drafted. Heemerged as the recognized author of the patriot cause in Virginia and indeed in the whole of the colonies. Jefferson's first public paper, however, was considered toostiff and formal, and it was rewritten. The paper was a response to the greeting of the new governor, Lord Botetourt, to the General Assembly. Jefferson, who nevertook criticis...

• Cameroon - country.

  seminomadic herders of the north. Cattle, goats, and fowl are the most commonly raised animals. B Forestry and Fishing Timber is traditionally one of Cameroon’s most valuable exports, consisting mainly of mahogany, ebony, and teak. The timber cut in 2006 amounted to 11.4 million cu m(401 million cu ft). Most of the fish caught in Cameroon come from the country’s rivers and lakes and are consumed locally. However, deep-sea fishing activity isincreasing, especially from the port of Douala. Some 1...

• Leukemia.

  leukemia, and normal or mildly decreased in chronic lymphocytic leukemia. Nearly all chronic leukemia patients have increased white cell counts. In chronic myelocyticleukemia, some of these leukemic white cells are capable of functioning as normal cells do by fighting infectious microbes. Hence, infection is no more common than in ahealthy individual. In chronic lymphocytic leukemia the blood contains large numbers of malignant lymphocytes that do not function normally. Normal lymphocytescoexist...

• Impressionism (art) I INTRODUCTION Vegetable Garden at the Hermitage, Pontoise Vegetable Garden at the Hermitage, Pontoise (1879) was painted by the French artist Camille Pissarro.

  the Grass; 1863, Musée d’Orsay, Paris), which depicts a nude woman at a woodland picnic. To emphasize the woman’snakedness, Manet not only shows that she has recently disrobed (by painting her clothes in a heap nearby) but alsodepicts her male companions fully clothed. In addition, the woman stares directly and unabashedly at the viewer, makingus feel almost like voyeurs as we gaze back. Manet’s painting style–the flat figures, which look almost like cutouts, andloose brushwork–also bewildered a...

• Comoros - country.

  Since 1981 the currency has been the Comorian franc. The Comorian franc had a fixed exchange rate with the French franc of 50 to 1 until 1994, when the rate was changed to 75 Comorian francs to 1 French franc. In 2006, the Comorian franc exchanged at an average of 392 to U.S.$1. Transport between the islands is mostly by air, and there is an international airport at Hahaia on Njazidja where jets can land. Road networks have been built betweenmost of the main island settlements, but the mountai...

• India - country.

  delta in the north, are intensely farmed. B Rivers and Lakes The rivers of India can be divided into three groups: the great Himalayan rivers of the north, the westward-flowing rivers of central India, and the eastward-flowingrivers of the Deccan Plateau and the rest of peninsular India. Only small portions of India’s rivers are navigable because of silting and the wide seasonal variation inwater flow (due to the monsoon climate). Water transport is thus of little importance in India. Barrages,...

• The Alchimist

• American Civil War.

  free state to keep the balance in the Senate. It also provided that slavery would be excluded from the still unorganized part of the Louisiana Territory. A line was drawnfrom Missouri’s southern boundary, at the latitude of 36°30’, and slavery would not be allowed in the territory north of that line,with the exception of Missouri. B Compromise of 1850 Agitation against slavery continued in the North. The South reacted by defending it ever more strongly. The Mexican War, by which the United Stat...

• American Civil War - U.

  free state to keep the balance in the Senate. It also provided that slavery would be excluded from the still unorganized part of the Louisiana Territory. A line was drawnfrom Missouri’s southern boundary, at the latitude of 36°30’, and slavery would not be allowed in the territory north of that line,with the exception of Missouri. B Compromise of 1850 Agitation against slavery continued in the North. The South reacted by defending it ever more strongly. The Mexican War, by which the United Stat...

• Antibiotics.

  In some species of bacteria the cell wall consists primarily of a thick layer of peptidoglycan. Other species have a much thinner layer of peptidoglycan and an outer aswell as an inner membrane. When bacteria are subjected to Gram's stain, these differences in structure affect the differential staining of the bacteria with a dye calledgentian violet. The differences in staining coloration (gram-positive bacteria appear purple and gram-negative bacteria appear colorless or reddish, depending on t...

• Uranus (planet) - astronomy.

  V COMPOSITION AND STRUCTURE A Interior of Uranus Uranus contains mostly rock and water, with hydrogen and helium (and trace amounts of methane) in its dense atmosphere. Astronomers believe that Uranus, likeNeptune, formed from the same material—principally frozen water and rock—that composes most of the planet’s moons. As the planet grew, pressures andtemperatures in the planet’s interior increased, heating the planet’s frozen water into a hot liquid. Uranus probably has a relatively small roc...

• Immune System.

  The humoral immune response involves a complex series of events after antigens enter the body. First, macrophages take up some of the antigen and attach it to classII MHC molecules, which then present the antigen to T helper cells. The T helper cells bind the presented antigen, which stimulates the T helper cells to divide andsecrete stimulatory molecules called interleukins. The interleukins in turn activate any B lymphocytes that have also bound the antigen. The activated B cells then divide...

• 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...

• Statistics I INTRODUCTION Statistics, branch of mathematics that deals with the collection, organization, and analysis of numerical data and with such problems as experiment design and decision making.

  Professional pollsters typically conduct their surveys among sample populations of 1,000 people. Statistical measurementsshow that reductions in the margin of error flatten out considerably after the sample size reaches 1,000.© Microsoft Corporation. All Rights Reserved. The raw materials of statistics are sets of numbers obtained from enumerations or measurements. In collecting statistical data, adequate precautions must be taken tosecure complete and accurate information. The first problem of...

• Burkina Faso - country.

  powers to promote the welfare of the people. The Lobi live in the southwest as farmers and hunters. Defiant of newcomers, they live in small terraced fortifications. The Bobo are chiefly farmers, artisans, and metalworkers living in large villages in the west-central part of the country. The Gourounsi are mainly artisans and farmers in the south-central areas. Their society is lesshighly structured than that of the other Voltaic groups. Christianity has made substantial inroads among them. The M...

• Coral - biology.

  Soft corals lack a distinct skeleton. Although they live in colonies, the individual polyps are fused into a complex body, usually strengthened by small lumps or spikesknown as sclerites, which are made of protein and calcite. Soft corals come in a variety of shapes, including undulating sheets, upright mushroomlike shapes, andbeautiful shapes that form branches. A number of other octocorals have skeletons made from a hard or horny protein, sometimes strengthened with more brittle calcareous dep...

• 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...

• Biodiversity.

  a common molecule, ribonucleic acid (RNA), and most also have deoxyribonucleic acid (DNA). These molecules direct the production of proteins—molecules responsiblefor the structure and function of virtually all living cells. This is the evolutionary chain of life. All species are descended from a single common ancestor. From that ancient single-celled microbe, all inherited RNA. As time goesby, species diverge and develop their own peculiar attributes, thus making their own contribution to biodiv...

• Biodiversity - biology.

  a common molecule, ribonucleic acid (RNA), and most also have deoxyribonucleic acid (DNA). These molecules direct the production of proteins—molecules responsiblefor the structure and function of virtually all living cells. This is the evolutionary chain of life. All species are descended from a single common ancestor. From that ancient single-celled microbe, all inherited RNA. As time goesby, species diverge and develop their own peculiar attributes, thus making their own contribution to biodiv...

• Circulatory System.

  C Additional Functions In addition to oxygen, the circulatory system also transports nutrients derived from digested food to the body. These nutrients enter the bloodstream by passingthrough the walls of the intestine. The nutrients are absorbed through a network of capillaries and veins that drain the intestines, called the hepatic portal circulation.The hepatic portal circulation carries the nutrients to the liver for further metabolic processing. The liver stores a variety of substances, suc...

• Thomas Edison.

  While Edison was working on the electric light, he made a scientific discovery that would become important to future generations. Edison noticed that particles of carbonfrom the filament blackened the insides of his light bulbs. This effect was caused by the emission of electrons from the filament, although Edison made the discoverybefore he and other scientists knew the electron existed. Not until 1897 did British physicist J. J. Thomson prove that the blackening observed by Edison was caused b...

• Thomas Edison - USA History.

  While Edison was working on the electric light, he made a scientific discovery that would become important to future generations. Edison noticed that particles of carbonfrom the filament blackened the insides of his light bulbs. This effect was caused by the emission of electrons from the filament, although Edison made the discoverybefore he and other scientists knew the electron existed. Not until 1897 did British physicist J. J. Thomson prove that the blackening observed by Edison was caused b...

• Extinction (biology) - biology.

  III ROLE OF MASS EXTINCTION IN EVOLUTION Historically biologists—most famous among them British naturalist Charles Darwin—assumed that extinction is the natural outcome of competition between newlyevolved, adaptively superior species and their older, more primitive ancestors. These scientists believed that newer, more highly evolved species simply drove less well-adapted species to extinction. That is, historically, extinction was thought to result from evolution. It was also thought that this...