383 résultats pour "additive"

• Periodic Law - chemistry.

  VI QUANTUM THEORY With the development of the quantum theory and its application to atomic structure by the Danish physicist Niels Bohr and other scientists, most of the detailedfeatures of the periodic table have found a ready explanation. Every electron is characterized by four quantum numbers that designate its orbital motion in space. Bymeans of the selection rules governing these quantum numbers and the exclusion principle of Wolfgang Pauli, which states that two electrons in the same ato...

• Comenius, John Amos

  enlightenment, peace, international co-operation and prosperity. This should be helped by the spread of education into all layers of society, and to each individual. The outbreak of the Civil War curtailed Comenius' activities in England. He left for Sweden to reform its educational system, hoping at the same time that Sweden's policy and participation in the Thirty Years' War might result in the liberation of the Kingdom of Bohemia from the rule of the Habsburgs and facilitate the repat...

• Egyptian Mythology I INTRODUCTION Egyptian Mythology, specifically, the religion of ancient Egypt.

  PtahThe Egyptian god Ptah was, among other things, patron of the arts and of artisans. He was worshipped at Memphis, theancient capital of Egypt. This statue of the deity dates from the 18th dynasty and is in the Egyptian Museum of Turin,Italy.Gianni Dagli Orti/Corbis In addition to those already named, the important divinities included the gods Amon, Thoth, Ptah, Khnemu, and Hapi, and the goddesses Hathor, Mut, Neit, andSekhmet. Their importance increased with the political ascendancy of the lo...

• NASA - astronomy.

  Challenger shuttle after launch in 1986 and the Columbia shuttle during reentry in 2003, killing both crews. Investigations traced the accidents to design flaws and tomanagement problems. Both accidents led to design and procedure changes, and to a temporary stoppage of shuttle flights. Following the Columbia disaster, NASA alsoannounced plans to retire the shuttle in 2010, after completion of the International Space Station (ISS), a human orbital research facility. The Constellation program is...

• Jacksonville (Florida) - geography.

  and southern sections and avoiding the downtown bottleneck where Interstate 95 crosses the Saint Johns River at the Fuller Warren Bridge. In addition to being a regional highway crossroads, the city is a railway hub, with Amtrak passenger service and several freight routes. The city’s expanding airport,located in northern Jacksonville, was the nation’s fastest growing in passenger volume in the mid-1990s. V GOVERNMENT Jacksonville has a mayor-council form of municipal government. The mayor and...

• Rembrandt I INTRODUCTION Rembrandt (1606-1669), Dutch baroque artist, who ranks as one of the greatest painters in the history of Western art.

  of his collection of art and antiquities, taken before an auction to pay his debts, showed the breadth of Rembrandt's interests: ancient sculpture, Flemish and ItalianRenaissance paintings, Far Eastern art, contemporary Dutch works, weapons, and armor. Unfortunately, the results of the auction—including the sale of hishouse—were disappointing. These problems in no way affected Rembrandt's work; if anything, his artistry increased. Some of the great paintings from this period are The Jewish Brid...

• LE PETIT LEXIQUE DE LITTERATURE

  Le Burlesque sera particulièrement à la mode entre 1640 et 1660. Il s'en prendra tour à tour à l'épopée, à latragédie, au portrait, au roman. Voir : Scarron : Virgile travesti ; Cyrano ; Boileau : Le Lutrin. CARTÉSIANISME. — Prend son origine dans le Discours de là Méthode de Descartes et surtout dans la première règle: « ne recevoir jamais aucune chose pour vraie que je ne la connusse évidemment être telle ». C'est la négation dela méthode d'autorité qui, depuis la scolastique, au Moye...

• Atlanta - geography.

  Prominent cultural and historical institutions in the city include the High Museum of Art (1983), designed by the noted postmodern American architect Richard Meier; theAtlanta Symphony; the Atlanta History Center, which maintains a history museum, historic houses and gardens, and extensive library and archives; NexusContemporary Art Center; the Robert W. Woodruff Arts Center; the Apex Museum; the Michael C. Carlos Museum at Emory University; the Clark Atlanta University ArtGallery; Fernbank Scie...

• Cincinnati - geography.

  and managed the Reds. The University of Cincinnati men’s basketball team enjoyed considerable success in the 1990s. IV ECONOMY Cincinnati, from its earliest beginnings, has functioned as a major port on the Ohio River. Distribution of raw materials as well as manufactured goods is one of the city’schief economic activities. Although Cincinnati remains one of the world’s leading centers for the distribution of bituminous (soft) coal, this trade is gradually declining. Coal from Kentucky and W...

• L'arithmétique : LA SCIENCE DES NOMBRES

  Un nombre n est divisible par un autre nombre m lorsqu'i l est le produit de ce dernier avec un troisième nombre : n =m.p . Autrement dit, le reste de la division euclidienne de n par m est égal à O. Exemple : 8 = 4 x 2 + o. Le nombre m est alors un diviseur den, et n est un multiple de m . Critères de divisibilité o Un nombre est divisible par 2 s'il se termine par un chiffre pair (0, 2, 4, 6, 8). o Un nombre est divisible par 3 lorsque la somme de s...

• 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...

• Woman Suffrage - U.

  form the National American Woman Suffrage Association. For many years thereafter the association worked to advance women’s rights on both the state and federallevels. Besides Stone, Anthony, and Stanton, leaders and supporters of the association included the noted American feminists Harriet Beecher Stowe, Julia Ward Howe,Clara Barton, Jane Addams, and Carrie Chapman Catt. Largely as a result of agitation by the association, suffrage was granted in the states of Colorado (1893), Utahand Idaho (18...

• Camel - biology.

  of water in the stomach or hump as was once commonly believed. Unlike other mammals, however, the camel can survive as long as three weeks without drinking,depending on the water content of its food. It can survive a water loss of about 40 percent of its normal body weight. In comparison, a loss of 15 percent is usually fatalfor humans. Camels can go without water due to several unique adaptations to their environment. The camel conserves more water in its body than any other mammal. It excretes...

• Ancient Egypt - history.

  The Nile River runs through the ancient city of Thebes in eastern Egypt. For a time, beginning in 2040 bc, Thebes was the capital ofEgypt.Farrell Grehan/Photo Researchers, Inc. According to inscriptions and documents found by archaeologists, the Egyptians called their country Kemet, meaning “the Black Land,” a reference to the dark, fertile soil that remained after the Nile floodwaters had receded. They also used another term, Deshret, or “the Red Land,” a designation for the desert sands th...

• California - geography.

  The Basin and Range province is an arid area of mountain ranges, basins, and deserts. In California it is represented primarily by parts of the Great Basin and SonoranDesert sections. Within the Great Basin lies Death Valley, whose lowest elevation, 86 m (282 ft) below sea level, is the lowest point in the Western Hemisphere. TheSonoran Desert section is characterized by numerous flat plains separated by low but rugged ranges. It includes the extensive Mojave, or Mohave, Desert. Also in thisprov...

• California - USA History.

  The Basin and Range province is an arid area of mountain ranges, basins, and deserts. In California it is represented primarily by parts of the Great Basin and SonoranDesert sections. Within the Great Basin lies Death Valley, whose lowest elevation, 86 m (282 ft) below sea level, is the lowest point in the Western Hemisphere. TheSonoran Desert section is characterized by numerous flat plains separated by low but rugged ranges. It includes the extensive Mojave, or Mohave, Desert. Also in thisprov...

• Cubism I INTRODUCTION Cubism, movement in modern art, especially in painting, invented by Spanish artist Pablo Picasso and French artist Georges Braque in 1907 and 1908.

  Mont Sainte-Victoire by CézanneFrench artist Paul Cézanne painted Mont Sainte-Victoire, a mountain near his home in Provence in southern France, onmany occasions. Over time, the images he produced became flatter, less realistic, and more abstract. In this late version,painted from 1902 to 1904, patches of color barely indicate the mountain, sky, and foreground, while creating a rhythmicpattern across the painting’s surface. The mountain and sky, both intensely blue, appear almost to merge.Philad...

• Stroke.

  IV DIAGNOSIS The symptoms typical of a stroke can also be caused by other conditions, including brain tumors, various infections, and overdoses of certain drugs. A patient that hasstrokelike symptoms may undergo a battery of imaging techniques to rule out other medical problems and confirm that a stroke has occurred. The key imagingtechnique used in diagnosing strokes is computed tomography (also known as CT or CAT scanning), which employs X rays to obtain images of the internal structures oft...

• Endocrine System.

  thermostat. When the heat in a house falls, the thermostat responds by switching the furnace on, and when the temperature is too warm, the thermostat switches thefurnace off. Usually, the change that a hormone produces also serves to regulate that hormone's secretion. For example, parathyroid hormone causes the body toincrease the level of calcium in the blood. As calcium levels rise, the secretion of parathyroid hormone then decreases. This feedback mechanism allows for tight controlover hormon...

• Endangered Species - biology.

  Red List database assesses the status of, and threats to, animal species worldwide. To add to this and other biodiversity databases, nongovernmental organizationssuch as Conservation International and World Wildlife Fund conduct periodic rapid assessments (focused, intensive evaluations) of biodiversity in varioushotspots— regions like Madagascar that are both rich in endemic species and environmentally threatened. This information is used in the administration of international agreements such...

• Ancient Egypt.

  around 4500 BC. The style and decoration of the pottery found at these sites differ from those of pottery found in Upper Egypt. The northern type eventually fell out of use. Other differences between the peoples in Upper Egypt and Lower Egypt include the nature of their architecture and the arrangements for burial of the dead, thelatter perhaps signifying differing religious beliefs. B Unification and Early Dynastic Period By 3500 BC, the settlement of Hierakonpolis, located on the west bank...

• Hormone.

  women is called a follicle-stimulating hormone. When a follicle-stimulating hormone binds to an ovary cell, it stimulates the enzymes needed for the synthesis ofestradiol, a female sex hormone. Another gonadotropin called luteinizing hormone regulates the production of eggs in women and the production of the male sexhormone testosterone. Produced in the male gonads, or testes, testosterone regulates changes to the male body during puberty, influences sexual behavior, and playsa role in growth. T...

• Indiana - geography.

  Michigan in Michigan. There are about 1,000 small natural lakes in Indiana, chiefly in the northern part of the state. The largest is Lake Wawasee, which covers almost 13 sq km (5 sq mi). Inthe central part of the state there are several lakes that were created behind dams on a number of smaller streams. They include Monroe Lake, near Bloomington; Geistand Eagle Creek reservoirs, northeast and northwest of Indianapolis; and Mississinewa and Huntington reservoirs, north of Marion. C Climate Most...

• Indiana - USA History.

  Michigan in Michigan. There are about 1,000 small natural lakes in Indiana, chiefly in the northern part of the state. The largest is Lake Wawasee, which covers almost 13 sq km (5 sq mi). Inthe central part of the state there are several lakes that were created behind dams on a number of smaller streams. They include Monroe Lake, near Bloomington; Geistand Eagle Creek reservoirs, northeast and northwest of Indianapolis; and Mississinewa and Huntington reservoirs, north of Marion. C Climate Most...

• Gemstones.

  In the late 1960s a method was developed for “growing” diamonds by heating a diamond particle to a high temperature and subjecting it to methane gas. The gasdecomposes into carbon atoms, which adhere to the diamond crystal. The crystal structure of the enlarged diamond is identical to that of a natural diamond. Diamondsof about 1 carat (200 mg or 0.007 oz) have been produced by this method, but their cost is still considerably higher than that of naturally occurring diamonds. Sapphires are made...

• Calvin Coolidge.

  By 1923 President Harding was faced with a number of difficulties. A business depression, which had begun in 1922, continued. In addition, the Republican majorities inboth houses of Congress were reduced in the election of 1922, and a discontented farm bloc of Western Republican senators threatened to destroy the Senate majorityby allying with the Democrats. Finally, it was rumored that major scandals involving Harding's friends were about to break. The rumors were soon proved accurate. The dire...

• Calvin Coolidge

  By 1923 President Harding was faced with a number of difficulties. A business depression, which had begun in 1922, continued. In addition, the Republican majorities inboth houses of Congress were reduced in the election of 1922, and a discontented farm bloc of Western Republican senators threatened to destroy the Senate majorityby allying with the Democrats. Finally, it was rumored that major scandals involving Harding's friends were about to break. The rumors were soon proved accurate. The dire...

• Human Evolution.

  Strepsirhines are the most primitive types of living primates. The last common ancestors of strepsirhines and other mammals—creatures similar to tree shrews andclassified as Plesiadapiformes—evolved at least 65 million years ago. The earliest primates evolved by about 55 million years ago, and fossil species similar to lemursevolved during the Eocene Epoch (about 55 million to 38 million years ago). Strepsirhines share all of the basic characteristics of primates, although their brains are notpa...

• Human Evolution - biology.

  classified as Plesiadapiformes—evolved at least 65 million years ago. The earliest primates evolved by about 55 million years ago, and fossil species similar to lemursevolved during the Eocene Epoch (about 55 million to 38 million years ago). Strepsirhines share all of the basic characteristics of primates, although their brains are notparticularly large or complex and they have a more elaborate and sensitive olfactory system (sense of smell) than do other primates. B Haplorhines B1 Tarsiers T...

• 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...

• Franklin Pierce.

  At the end of the war, Pierce returned home to his wife and six-year-old son. His law partnership had been dissolved, and he took a new partner. The new firm, like theold one, was highly successful. D Elder Statesman Pierce was by nature a politician. Although still in his early forties, as a retired U.S. senator he became New Hampshire's elder statesman and head of a group of lawyer-politicians called the Concord Clique, or the Regency. The group controlled the state's Democratic Party. Pierce...

• Franklin Pierce

  At the end of the war, Pierce returned home to his wife and six-year-old son. His law partnership had been dissolved, and he took a new partner. The new firm, like theold one, was highly successful. D Elder Statesman Pierce was by nature a politician. Although still in his early forties, as a retired U.S. senator he became New Hampshire's elder statesman and head of a group of lawyer-politicians called the Concord Clique, or the Regency. The group controlled the state's Democratic Party. Pierce...

• Cheetah - biology.

  animals such as zebras. Unlike most cats, cheetahs hunt during the day, when lions and hyenas that compete with them for prey are less likely to be active. Still,scientists in Tanzania have observed that cheetahs lose 10 to 13 percent of their kills to lions and hyenas. Alerted by the panic of a gazelle herd or by the circling ofvultures, lions and hyenas close in and easily drive the more timid cheetah away from a fresh kill. A cheetah usually stalks prey to within about 10 m (about 33 ft) and...

• Lester Pearson.

  a vacant seat. The by-election followed a major Liberal victory in September, and as a Liberal Party candidate, Pearson won by a comfortable margin in Algoma East,Ontario. He was reelected to the House of Commons in elections between 1949 and 1965. He was immediately made secretary of state for external affairs in the cabinetof Prime Minister Louis St. Laurent. In this post, Pearson set a new standard of frank exchange and cooperation that brought him respect and esteem. However, manyCanadians w...

• Lester Pearson - Canadian History.

  a vacant seat. The by-election followed a major Liberal victory in September, and as a Liberal Party candidate, Pearson won by a comfortable margin in Algoma East,Ontario. He was reelected to the House of Commons in elections between 1949 and 1965. He was immediately made secretary of state for external affairs in the cabinetof Prime Minister Louis St. Laurent. In this post, Pearson set a new standard of frank exchange and cooperation that brought him respect and esteem. However, manyCanadians w...

• Astronaut - astronomy.

  Every operation during a flight is important and interesting, but many might be boring to an observer. Much of an astronaut’s job is entering computer instructions,preparing samples, making measurements, recording data, fixing what breaks, and adjusting the checklist when something unexpected happens. Sometimes astronautsretrieve or repair satellites, rendezvous or dock with other spacecraft, and do important emergency repairs. The adaptability of the human crew is crucial to the successof missi...

• French and Indian War.

  Virginia as well as the French governor-general of Canada had attempted to seize their lands. After receiving large presents of supplies and arms, the Iroquoisgrudgingly renewed their alliances with the British colonies. Delegates then moved on to plan other defensive measures. An important topic was a plan of union developed by Benjamin Franklin. The Albany Plan, as it became known, proposed a single institution to govern all of the Britishcolonies in America. Under the plan, each colony would...

• French and Indian War - Canadian History.

  Virginia as well as the French governor-general of Canada had attempted to seize their lands. After receiving large presents of supplies and arms, the Iroquoisgrudgingly renewed their alliances with the British colonies. Delegates then moved on to plan other defensive measures. An important topic was a plan of union developed by Benjamin Franklin. The Albany Plan, as it became known, proposed a single institution to govern all of the Britishcolonies in America. Under the plan, each colony would...

• Slavery in Africa.

  The spread of Islam from Arabia into Africa after the religion’s founding in the 7th century AD affected the practice of slavery and slave trading in West, Central, and East Africa. Arabs had practiced slave raiding and trading in Arabia for centuries prior to the founding of Islam, and slavery became a component of Islamic traditions.Both the Qur'an (Koran) (the sacred scripture of Islam) and Islamic religious law served to codify and justify the existence of slavery. As Muslim Arabs conquered...

• Gardening - biology.

  of synthetic and organic fertilizers, see Organic Farming.) Fertilizers usually are sold in packages, on which the percentage by weight of the macronutrients nitrogen (N), phosphorus (P), and potassium (K) are listed on thelabel—always in the order N-P-K. For example, a fertilizer that is labeled 10-5-3 is 10 percent nitrogen, 5 percent phosphorus, and 3 percent potassium. V PLANTING AND TRANSPLANTING Before planting seeds, gardeners prepare, or till, the soil using a variety of methods. Some...

• 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...

• Iranian Art and Architecture I INTRODUCTION Iranian Art and Architecture, the visual arts of Iran.

  The first great development of ancient Persian architecture took place under the Achaemenid dynasty during the Persian Empire, from about 550 to 330 BC. Remains of Achaemenian architecture are numerous, the earliest being ruins at Pasargadae, the capital city of Cyrus the Great. These ruins include two palaces, a sacred precinct, acitadel, a tower, and the tomb of Cyrus. The palaces were set in walled gardens and contained central columnar halls, the largest of which was 37 m (111 ft) in length...

• Central America - Geography.

  F Animal Life Most of the animal life of Central America is similar to that of South America, but some animals have ties with North America. The marley and opossum have links withSouth America, as do the jaguar, ocelot, jaguarundi, and margay, which are members of the cat family. In contrast, the puma, gray fox, and coyote are of NorthAmerican origin. The armadillo, anteater, and sloth have ties to the south, deer to the north. The large manatee, an aquatic plant eater, survives in the isolated...

• Spain - country.

  B Natural Resources Spain has a number of mineral resources. The largest known deposits are of iron ore, zinc, and lead. Spain also produces significant quantities of copper and mercury.These deposits are mined mainly in Huelva province in southwestern Spain, around Cartagena on the Mediterranean, and at various points along the Bay of Biscay inthe north. Additionally, uranium is mined in the region of Extremadura, near the Portuguese frontier, where pyrites, fluorspar, gypsum, tungsten, and po...

• Bill of Rights.

  accused has the right to “confront”—that is, to cross-examine witnesses who testify against him or her at trial. Those accused also have a right to subpoena (compel)supporting witnesses to testify in court and to have a lawyer assist in their legal defense. G Seventh Amendment In Suits at common law, where the value in controversy shall exceed twenty dollars, the right of trial by jury shall be preserved, and no fact tried by a jury, shall beotherwise re-examined in any Court of the United Stat...

• Bill of Rights - U.

  accused has the right to “confront”—that is, to cross-examine witnesses who testify against him or her at trial. Those accused also have a right to subpoena (compel)supporting witnesses to testify in court and to have a lawyer assist in their legal defense. G Seventh Amendment In Suits at common law, where the value in controversy shall exceed twenty dollars, the right of trial by jury shall be preserved, and no fact tried by a jury, shall beotherwise re-examined in any Court of the United Stat...

• 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...

• 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...

• Asteroid - astronomy.

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

• Detroit - geography.

  of German and Irish immigrants. In the first half of the 20th century, the percentage of foreign-born residents declined, even though many immigrants arrived fromeastern Europe. During World War II (1939-1945), both whites and blacks were attracted from the South to work in the city’s defense industries. In 1950 foreign-bornand black residents each made up about 16 percent of the total population. In the five decades after 1950, the city lost almost half of its population, as many white resident...