611 résultats pour "résultante"

• Radar.

  gathers the weak returning radar signals and converts them into an electric current. Because a radar antenna may both transmit and receive signals, the duplexerdetermines whether the antenna is connected to the receiver or the transmitter. The receiver determines whether the signal should be reported and often does furtheranalysis before sending the results to the display. The display conveys the results to the human operator through a visual display or an audible signal. B1 The Antenna The rec...

• Dark Matter - astronomy.

  observed, and the measured frequency of such events has placed limits on how much dark matter can take the form of MACHOs. From the observations that have beenmade by astronomers, it is now known that MACHOs cannot be the dominant constituent of dark matter. There are simply not enough such gravitational lenses. Physicists suspect that a more exotic form of cold dark matter must exist. This form is not baryonic. Like neutrinos, this form barely interacts with ordinary matter, butis some type of...

• Metabolism (chemistry) - biology.

  nearly perfect balance. Although much remains to be revealed about metabolic processes, biochemists now agree that regulatory, or rate-limiting, enzymes figure largely in the reactionsinvolved ( see Enzyme). Affecting metabolic pathways at the earliest steps, each enzyme molecule has a specific, or active, site that matches, or “fits,” its particular substrate—the compound with which the enzyme forms a product. The precision with which rate-limiting enzymes and substrates join to set off a parti...

• Alzheimer's Disease.

  compared residents of Ibadan, Nigeria, who eat a mostly low-fat vegetarian diet, with African Americans living in Indianapolis, Indiana, whose diet included a variety ofhigh-fat foods. The Nigerians were less likely to develop Alzheimer’s disease compared to their U.S. counterparts. Some researchers suspect that health problems suchas high blood pressure, atherosclerosis (arteries clogged by fatty deposits), high cholesterol levels, or other cardiovascular problems may play a role in the devel...

• érosion.

  En même temps que le lit s'approfondit, il s'élargit parfois. Les berges inscrites dans des matériaux meubles s'éboulent quand elles sont imbibées d'eau, lors des crues ; lescourants les frappent, en particulier dans les courbes, les faisant reculer tandis que les sinuosités s'exagèrent. Ainsi se forment et évoluent les méandres. Cet élargissementdu lit relève de l'érosion latérale. L'eau opère un tri en fonction de sa compétence, ou capacité de transport (taille maximale des alluvions que le co...

• érosion - géologie et géophysique.

  En même temps que le lit s'approfondit, il s'élargit parfois. Les berges inscrites dans des matériaux meubles s'éboulent quand elles sont imbibées d'eau, lors des crues ; lescourants les frappent, en particulier dans les courbes, les faisant reculer tandis que les sinuosités s'exagèrent. Ainsi se forment et évoluent les méandres. Cet élargissementdu lit relève de l'érosion latérale. L'eau opère un tri en fonction de sa compétence, ou capacité de transport (taille maximale des alluvions que le co...

• Water - chemistry.

  flourides in drinking water has been found to reduce tooth decay. See Fluorine. Seawater contains, in addition to concentrated amounts of sodium chloride, or salt, many other soluble compounds, as the impure waters of rivers and streams areconstantly feeding the oceans. At the same time, pure water is continually lost by the process of evaporation, and as a result the proportion of the impurities that givethe oceans their saline character is increased. See Ocean and Oceanography. VII WATER...

• Virus (computer).

  how closely it resembles a virus. It relies on experience with previous viruses to predict the likelihood that a suspicious file is an as-yet unidentified or unclassified newvirus. Other types of antiviral software include monitoring software and integrity-shell software. Monitoring software is different from scanning software. It detects illegal orpotentially damaging viral activities such as overwriting computer files or reformatting the computer's hard drive. Integrity-shell software establis...

• Turbine.

  steam turbine has supplanted the reciprocating engine as a prime mover in large electricity-generating plants and is also used as a means of jet propulsion. Steam turbines are used in the generation of nuclear power and in nuclear ship propulsion. They operate with fuel-fired boilers for power generation. In cogenerationapplications requiring both process heat (heat used in an industrial process) and electricity, steam is raised at high pressure in the boiler and extracted from the turbineat th...

• Radio Astronomy - astronomy.

  equivalent to the apparent angular dimensions of a basketball at the distance of the moon. In 1984, the U.S. government appropriated funds for the construction of aninstallation called the very long baseline array (VLBA), a network of 10 radio antennas spread from the U.S.-Canadian border to Puerto Rico and from Hawaii to the U.S.Atlantic coast. The VLBA is expected to provide angular resolutions in the range of 200-millionths of an arc second. Canada and Australia are both planning similarprogr...

• 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...

• Plate Tectonics.

  ridges. The Mid-Atlantic Ridge is an underwater mountain range created at a divergent plate boundary in the middle of the Atlantic Ocean. It is part of a worldwidesystem of ridges made by seafloor spreading. The Mid-Atlantic Ridge is currently spreading at a rate of 2.5 cm per year (1 in per year). The mid-ocean ridges today are60,000 km (about 40,000 mi) long, forming the largest continuous mountain chain on earth. Earthquakes, faults, underwater volcanic eruptions, and vents, oropenings, along...

• Pollution.

  One of the greatest challenges caused by air pollution is global warming, an increase in Earth’s temperature due to the buildup of certain atmospheric gases such ascarbon dioxide. With the heavy use of fossil fuels in the 20th century, atmospheric concentrations of carbon dioxide have risen dramatically. Carbon dioxide and othergases, known as greenhouse gases, reduce the escape of heat from the planet without blocking radiation coming from the Sun. Because of this greenhouse effect,average glob...

• Jupiter (planet) - astronomy.

  Beneath the supercritical fluid zone, the pressure reaches 3 million Earth atmospheres. At this depth, the atoms collide so frequently and violently that the hydrogenatoms are ionized—that is, the negatively charged electrons are stripped away from the positively charged protons of the hydrogen nuclei. This ionization results in asea of electrically charged particles that resembles a liquid metal and gives rise to Jupiter’s magnetic field. This liquid metallic hydrogen zone is 30,000 to 40,000 k...

• Labor Unions in the United States - U.

  National Guard troops were used against the strikers, with the result that the strike was lost and the union that conducted it virtually destroyed. In 1894 a strike by theAmerican Railway Union against the Pullman Palace Car Company was defeated by an injunction issued under the Sherman Antitrust Act of 1890, which made acombination or contract in restraint of trade illegal. Thereafter employers used injunctions with increasing frequency and effectiveness as an antistrike weapon. See also Hours...

• Television.

  A charge-coupled device (CCD) can be much smaller than a camera tube and is much more durable. As a result, cameras with CCDs are more compact and portablethan those using a camera tube. The image they create is less vulnerable to distortion and is therefore clearer. In a CCD, the light from a scene strikes an array ofphotodiodes arranged on a silicon chip. Photodiodes are devices that conduct electricity when they are struck by light; they send this electricity to tiny capacitors. Thecapacitors...

• Wars of Yugoslav Succession.

  of Yugoslav succession was over. In January 1992 members of the European Community (EC; after 1993 the European Union, EU) recognized Slovenia’s independencealong with that of Croatia. The United States and other countries did so shortly thereafter. IV THE WAR IN CROATIA As the Yugoslav army withdrew from Slovenia in July 1991, a second and far more serious conflict erupted in Croatia. But the road to war in Croatia began more than ayear earlier. In April and May 1990 the Croatian Democratic U...

• Wars of Yugoslav Succession .

  of Yugoslav succession was over. In January 1992 members of the European Community (EC; after 1993 the European Union, EU) recognized Slovenia’s independencealong with that of Croatia. The United States and other countries did so shortly thereafter. IV THE WAR IN CROATIA As the Yugoslav army withdrew from Slovenia in July 1991, a second and far more serious conflict erupted in Croatia. But the road to war in Croatia began more than ayear earlier. In April and May 1990 the Croatian Democratic U...

• Baseball.

  pitcher or argue a call with an umpire. Two or more coaches, positioned closer to the field, assist the manager by communicating with the players. For example,managers may decide what pitches should be thrown, when batters should swing at a pitch, and how runners should move around the bases. The manager relays thesedecisions through special hand signals that the coaches repeat to communicate to the players. Umpires are responsible for interpreting and enforcing the rules of play. They rule on...

• Le beau s'impose-t-il à notre jugement ou en résulte-t-il ?

• Droit Administratif, Commentaire du 18 Juin 2008 : La responsabilité administrative, les principes généraux

  II. La responsabilité de la puissance publique engagée pour faute lourde par violation d’un droit communautaire à M.Gestas. M.Gestas ne peux entacher la responsabilité de la puissance publique par une erreur dans l’exercice de la fonction juridictionnelle (A). Mais cependant il pourranéanmoins engager la responsabilité de l’état par la violation du droit communautaire qui lui est conféré à savoir le droit au respect d’un procès au délai raisonnable(B.) A- La faute lourde invoquée par M.Gestas da...

• Il en a résulté une imageréductrice et une interprétation fallacieuse de cet événement capital.

• La zone intertropicale forme un milieu climatique avec une chaleur constante et, en dehors d'une bande équatoriale toujours pluvieuse, avec un rythme annuel de précipitations qui diminue au fur et à mesure que l'on se rapproche des tropiques, sauf dans l'Asie des moussons.

  température - La température terrestre Une forte humidité. Si le climat tropical est caractérisé par la chaleur, il l'est également par l'humidité. Celle-ci résulte des températures élevées, puisque seul l'air chaud est physiquement capable de contenir beaucoup de vapeur d'eau, avant que celle-ci ne se condense. Il pleut en effet d'autant plus que l'air est chargé de vapeur d'eau et que des mouvements d'ascendance de cet air humide se développent, provoquant la condensation et la formation des...

• chirurgie - Mécedine.

  occasionnées par des armes blanches ou des armes à feu, elle sert aujourd’hui à corriger des malformations congénitales ou les obstructions au niveau des valves résultantde fièvres rhumatismales. La ligature des artères permettant de contrôler les hémorragies a eu une grande importance dans ces pratiques chirurgicales. De nombreuses affections coronariennes qui autrefois entraînaient la mort ou laissaient de lourdes séquelles peuvent aujourd’hui être guéries grâce à la chirurgie. Il estdésormais...

• Anxiety.

  A Genetics and Neurobiology Studies suggest that anxiety disorders run in families. That is, children and close relatives of people with disorders are more likely than most to develop anxietydisorders. Some people may inherit genes that make them particularly vulnerable to anxiety. These genes do not necessarily cause people to be anxious, but the genesmay increase the risk of anxiety disorders when certain psychological and social factors are also present. Anxiety also appears to be related to...

• From Bush v.

  legal requirements. This case has shown that punch card balloting machines can produce an unfortunate number of ballots which are not punched in a clean, complete way by the voter.After the current counting, it is likely legislative bodies nationwide will examine ways to improve the mechanisms and machinery for voting. B The individual citizen has no federal constitutional right to vote for electors for the President of the United States unless and until the state legislature chooses astatewide...

• Advertising.

  Advertising agencies make money in a variety of ways. When the agency uses the client’s advertising budget to buy time for an ad on the radio or on television or whenit buys space for an ad in a newspaper or magazine, the media outlet allows the agency to keep 15 percent of the cost of the space or the time as a commission. The15 percent commission has become an advertising industry standard and usually accounts for the largest portion of the agency’s income. Agencies also charge clientsfor the...

• Depression (psychology).

  IV CAUSES Some depressions seem to come out of the blue, even when things are going well. Others seem to have an obvious cause: a marital conflict, financial difficulty, or somepersonal failure. Yet many people with these problems do not become deeply depressed. Most psychologists believe depression results from an interaction betweenstressful life events and a person’s biological and psychological vulnerabilities. A Biological Factors Depression runs in families. By studying twins, researche...

• Poverty.

  economic and demographic trends, and (7) welfare incentives. A Overpopulation Overpopulation, the situation of having large numbers of people with too few resources and too little space, is closely associated with poverty. It can result from highpopulation density (the ratio of people to land area, usually expressed as numbers of persons per square kilometer or square mile) or from low amounts of resources, or from both. Excessively high population densities put stress on available resources....

• Acquired Immunodeficiency Syndrome.

  child transmission is particularly prevalent in Africa. D Misperceptions About HIV Transmission The routes of HIV transmission are well documented by scientists, but health officials continually grapple with people’s unfounded fears concerning the potential for HIVtransmission by other means. HIV differs from other infectious viruses in that it dies quickly if exposed to the environment. No evidence has linked HIV transmission tocasual contact with an infected person, such as a handshake, huggi...

• Evolution - biology.

  genetic diversity to extinction. Sexual reproduction ensures that the genes in a population are rearranged in each generation, a process termed recombination. Although the combinations of genes inindividuals change with each new generation, the gene frequency, or ratio of different alleles in the entire population, remains relatively constant if no evolutionaryforces act on the population. One such force is the introduction of new genes into the genetic material of the population, or gene pool...

• Intelligence.

  education. Teachers had no way of knowing which of the “slow” students had true learning problems and which simply had behavioral problems or poor prior education.In 1904 the French Ministry of Public Instruction asked Binet and others to develop a method to objectively identify children who would have difficulty with formaleducation. Objectivity was important so that conclusions about a child’s potential for learning would not be influenced by any biases of the examiner. The governmenthoped tha...

• Roman Mythology.

  Her temple on the Aventine Hill in Rome was a center for organizations of skilled craftspeople. According to tradition, in 509 BC the dynasty of Etruscan kings ended and the Roman Republic was founded. The republic was ruled by two chief magistrates, called consuls, who were elected by the people to one-year terms. During the time of the republic, the Capitoline temple became the most important public shrine of theRoman people and the focus of public worship. Each January, the new consuls offer...

• Electoral College.

  III HISTORY OF THE ELECTORAL COLLEGE A Origins One thing is clear about the political theory underpinning the electoral college: The framers of the Constitution could not agree on one. From the outset, the framerswere uncertain about how the president should be chosen. Meeting in the Constitutional Convention in Philadelphia, Pennsylvania, in 1787, the framers originally decidedto have Congress choose the president, and that there should be no popular vote to elect the president. Then the Con...

• oeuf. n.m., cellule vivante résultant de la fusion de l'ovule

• Cuba - country.

  Only two land mammals, the hutia, or cane rat, and the solenodon, a rare insectivore that resembles a rat, are known to be indigenous. The island has numerous batsand nearly 300 kinds of birds, including vultures, wild turkeys, quail, finches, gulls, macaws, parakeets, and hummingbirds. The bee hummingbird of Cuba is thesmallest bird in the world. Among the few reptiles are tortoises, caimans, the Cuban crocodile, and a species of boa that can attain a length of 3.7 m (12 ft). More than700 speci...

• 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...

• British Empire .

  B1 The Seven Years’ War During the Seven Years’ War in Europe (1756-1763), Britain made large imperial gains at the expense of France. The North American segment of the Seven Years’ Warwas known as the French and Indian War. It was launched by the British against French possessions in North America in 1754, and in 1758 the British captured theFrench fortress of Louisbourg, which gave them access to French territory in the St. Lawrence Valley. In the following year Québec was captured, marking t...

• Human Nutrition.

  is one of the most preventable types of cancer. Nutritionists caution that most Americans need to eat more complex carbohydrates. In the typical American diet, only 40 to 50 percent of total calories come fromcarbohydrates—a lower percentage than found in most of the world. To make matters worse, half of the carbohydrate calories consumed by the typical American comefrom processed foods filled with simple sugars. Experts recommend that these foods make up no more that 10 percent of our diet, bec...

• French Revolution.

  B2 Assembly of Notables and Estates-General To pressure the parlements into accepting the plan, Calonne decided to gain prior approval of it from an Assembly of Notables—a group of hand-picked dignitaries hethought would sympathize with his views. But Calonne had badly miscalculated. Meeting in January 1787, the assembly refused to believe that a financial crisis reallyexisted. They had been influenced by Necker’s argument that state finances were sound and suspected that the monarchy was only...

• French Revolution .

  B2 Assembly of Notables and Estates-General To pressure the parlements into accepting the plan, Calonne decided to gain prior approval of it from an Assembly of Notables—a group of hand-picked dignitaries hethought would sympathize with his views. But Calonne had badly miscalculated. Meeting in January 1787, the assembly refused to believe that a financial crisis reallyexisted. They had been influenced by Necker’s argument that state finances were sound and suspected that the monarchy was only...

• Algebra I INTRODUCTION Algebra, branch of mathematics in which symbols (usually letters) represent unknown numbers in mathematical equations.

  B Order of Operations and Grouping Algebra relies on an established sequence for performing arithmetic operations. This ensures that everyone who executes a string of operations arrives at the sameanswer. Multiplication is performed first, then division, followed by addition, then subtraction. For example: 1 + 2 · 3 equals 7 because 2 and 3 are multiplied first and then added to 1. Exponents and roots have even higher priority than multiplication: 3 · 2 2 = 3 · 4 = 12 Grouping symbols override...

• Religion.

  By the end of the 19th century, scholars were making religion an object of systematic inquiry. Müller’s comparative approach was adopted in many European andJapanese universities, and as a result the common features of world religions (such as gods, prayer, priesthood, and creation myths) were the subjects of sustainedscholarly investigation. In addition, field anthropologists had begun to compile firsthand accounts of the religions of peoples who previously had been dismissed assavages. The stu...

• 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...

• African American History - U.

  In their day-to-day lives, slaves and servants shared similar grievances and frequently formed alliances. Advertisements seeking the return of slaves and servants whohad run away together filled colonial newspapers. When a slave named Charles escaped in 1740, the Pennsylvania Gazette reported that two white servants, a 'Scotch man' and an Englishman, escaped with him. Sometimes interracial alliances involved violence. During Bacon's Rebellion in 1676, slaves and servants took up armsagainst Na...

• Relativity - astronomy.

  beta, for example, might be as large as 0.5, and the mass of the electron doubled. The mass of a rapidly moving electron could be easily determined by measuring thecurvature produced in its path by a magnetic field; the heavier the electron, the greater its inertia and the less the curvature produced by a given strength of field ( see Magnetism). Experimentation dramatically confirmed Einstein's prediction; the electron increased in mass by exactly the amount he predicted. Thus, the kinetic ener...

• Soil. I INTRODUCTION Soil, the loose material that covers the land surfaces of

  an exchange between plants and the atmosphere, as oxygen diffuses into the soil and is used by roots for respiration. In turn, the resulting carbon dioxide diffusesthrough pore spaces and returns to the atmosphere. This exchange is most efficient in soils with a high degree of porosity. For farmers, gardeners, landscapers, andothers with a professional interest in soil health, the process of aeration—making holes in the soil surface to permit the exchange of air—is a crucial activity. Theburrowi...

• Marketing.

  Where advertising reaches a mass audience, personal or direct selling focuses on one customer at a time. That kind of individual attention makes direct sellingexpensive, but it also makes it effective. As the costs of personal selling have risen, the utilization of salespeople has changed. Simple transactions are completed byclerks. Salespeople are now used primarily where the products are complex and require detailed explanation, customized application, or careful negotiation over priceand paym...

• Accounting and Bookkeeping.

  The proliferation of mandated notes that accompany financial statements is a particularly visible example. Such notes disclose information that is not already included inthe body of the financial statement. One of the very first notes identifies the accounting methods adopted when acceptable alternative methods also exist, or when theunique nature of the company's business justifies an otherwise unconventional approach. The notes also disclose information about lease commitments, contingent liab...