118 résultats pour "function"

• 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...

• Hardware (computer).

  Magnetic tape drives use magnetic tape similar to the tape used in VCR cassettes. Tape drives have a very slow read/write time, but have a very high capacity; in fact,their capacity is second only to hard disk drives. Tape drives are mainly used to back up data. Compact disc drives store information on pits burned into the surface of a disc of reflective material ( see CD-ROM). CD-ROMs can store up to 737 megabytes (MB) of data. A Compact Disc-Recordable (CD-R) or Compact Disc-ReWritable (CD-RW)...

• Greek Art and Architecture - USA History.

  The struggle between these two city-states and their allies ultimately led to the Peloponnesian War (431-404 BC), which Sparta won. Despite this conflict, the 5th century, often called the Classical period, is usually considered the culmination of Greek art, architecture, and drama, with its highest achievements being the Temple ofZeus at Olympia, the Parthenon in Athens, and the plays of Athenian dramatists Aeschylus, Sophocles, Euripides, and Aristophanes. The 4th century, or Late Classical p...

• Central Processing Unit.

  Development of the computer chip started in 1958 when Jack Kilby of Texas Instruments demonstrated that it was possible to integrate the various components of aCPU onto a single piece of silicon. These computer chips were called integrated circuits (ICs) because they combined multiple electronic circuits on the same chip.Subsequent design and manufacturing advances allowed transistor densities on integrated circuits to increase tremendously. The first ICs had only tens of transistorsper chip com...

• Teeth.

  treatments to reduce the risk of tooth decay; clear plastic coatings painted on the teeth, called dental sealants, and applications of the mineral fluoride, which fortifiestooth enamel, are two such treatments. Fluoride is also added to public water supplies in a process called fluoridation, which benefits more than 150 million Americans. Gum disease, or periodontal disease, is a progressive condition that worsens with age. Gum disease occurs when bacteria eat away at gum tissue, causing it to p...

• Honey Bee - biology.

  B Reproduction and Development The queen controls the sex of her offspring. When an egg passes from her ovary to her oviduct, the queen determines whether the egg is fertilized with sperm from thespermatheca. A fertilized egg develops into a female honey bee, either worker or queen, and an unfertilized egg becomes a male honey bee, or drone. The queen lays the eggs that will develop into more queens in specially constructed downward-pointing, peanut-shaped cells, in which the egg adheres to the...

• Washington, D.

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

• Mental Illness.

  note that under this definition, political dissidents could be considered mentally ill for refusing to accept the dictates of their government. VI PREVALENCE Mental illness affects people of all ages, races, cultures, and socioeconomic classes. The prevalence of mental illness refers to how many people experience a mentalillness during a specified time period. A United States and Worldwide In the United States, researchers estimate that about 24 percent of people 18 or older, or about 44 mill...

• Prison.

  Furthermore, experts disagree about whether imprisoning criminals actually prevents further crime. Some critics charge that American prisons simply warehouseviolence—meaning that U.S. prison inmates are confined and incapacitated in large numbers, with little or no effort made to rehabilitate them. Critics have labeled theresult of this process turnstile justice, referring to the fact that most inmates are chronic and persistent offenders and return to prison following conviction for new crime...

• West Virginia - geography.

  Forests, mostly of hardwood varieties, cover 79 percent of West Virginia. The principal commercial species are the oak, yellow poplar, maple, birch, beech, black walnut,hickory, and gum. Softwoods include pines and hemlock firs. Flowering trees include the wild crab apple, dogwood, hawthorn, and redbud. Among the many floweringbushes and plants are the rhododendron, which is the state flower, the laurel, blueberry, hepatica, wild geranium, and black-eyed Susan. Insects and disease, mostly introd...

• West Virginia - USA History.

  Forests, mostly of hardwood varieties, cover 79 percent of West Virginia. The principal commercial species are the oak, yellow poplar, maple, birch, beech, black walnut,hickory, and gum. Softwoods include pines and hemlock firs. Flowering trees include the wild crab apple, dogwood, hawthorn, and redbud. Among the many floweringbushes and plants are the rhododendron, which is the state flower, the laurel, blueberry, hepatica, wild geranium, and black-eyed Susan. Insects and disease, mostly introd...

• arc en ciel

  · "Adults are always asking little kids what they want to be when they grow up because   they're looking for ideas.” What we can or cannot do, what we consider possible or impossible, is rarely a function of our true   capability. It is more likely a function of our beliefs about who we are. Tony Robbins “ Nobody can go back and start a new beginning, but anyone can start today and make a new ending. ” The difference between school and life? In school, you're taught a lesson and then...

• Multiple Sclerosis.

  slow the progress of the disease. It has become increasingly clear that early treatment is crucial to prevent or delay further damage to the nervous system. There are also treatments for specific symptoms, including corticosteroids (often taken intravenously), that can shorten the duration of an MS attack. Several drugs canrelieve spasticity, fatigue, and bladder problems. People with MS often find that nondrug treatments, such as regular exercise and adequate rest, can help them tomaintain more...

• 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...

• 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...

• Drug Dependence.

  these drugs develops rapidly, no withdrawal syndrome is apparent when they are discontinued. Phencyclidine, or PCP, known popularly by such names as “angel dust” and “rocket fuel,” has no medical purpose for humans but is occasionally used by veterinarians asan anesthetic and sedative for animals. It became a common drug of abuse in the late 1970s, and is considered a menace because it can easily be synthesized. Itseffects differ from those of other hallucinogens. LSD, for example, produces deta...

• Aristotle I INTRODUCTION Aristotle (384-322 BC), Greek philosopher and scientist, who shares with Plato and Socrates the distinction of being the most famous of ancient philosophers.

  succession of individuals. These processes are therefore intermediate between the changeless circles of the heavens and the simple linear movements of the terrestrialelements. The species form a scale from simple (worms and flies at the bottom) to complex (human beings at the top), but evolution is not possible. C Aristotelian Psychology For Aristotle, psychology was a study of the soul. Insisting that form (the essence, or unchanging characteristic element in an object) and matter (the commonu...

• Aristotle.

  succession of individuals. These processes are therefore intermediate between the changeless circles of the heavens and the simple linear movements of the terrestrialelements. The species form a scale from simple (worms and flies at the bottom) to complex (human beings at the top), but evolution is not possible. C Aristotelian Psychology For Aristotle, psychology was a study of the soul. Insisting that form (the essence, or unchanging characteristic element in an object) and matter (the commonu...

• 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...

• Eye. I INTRODUCTION Eye, light-sensitive organ of vision in animals. The eyes of

  Several structures, not parts of the eyeball, contribute to the protection of the eye. The most important of these are the eyelids, two folds of skin and tissue, upper andlower, that can be closed by means of muscles to form a protective covering over the eyeball against excessive light and mechanical injury. The eyelashes, a fringe ofshort hairs growing on the edge of either eyelid, act as a screen to keep dust particles and insects out of the eyes when the eyelids are partly closed. Inside the...

• Police.

  body. In larger agencies, executive officers may be selected through a civil service or merit system, after moving through the ranks from patrol officer to sergeant,lieutenant, captain, and (in still larger agencies) deputy or assistant chief. At the county level, the head of the agency usually holds the title sheriff. The sheriff is almost always elected and has the power to appoint deputies. Sheriffs'departments often provide law enforcement services for unincorporated areas of counties and ar...

• International Criminal Court.

  only exercise its jurisdiction when a national court is unwilling or unable to carry out the investigation or prosecution. For example, the ICC might intervene when agovernment’s judicial system has collapsed or is actively shielding a person from criminal responsibility. The court may hold accountable any person aged 18 or older at the time of the crime without regard to the individual’s official duties or functions. Therefore, heads ofstate, legislators, and other high-ranking government offic...

• Stress (psychology).

  blood flow is diverted from the internal organs and skin to the brain and muscles. Breathing speeds up, the pupils dilate, and perspiration increases. This reaction issometimes called the fight-or-flight response because it energizes the body to either confront or flee from a threat. Another part of the stress response involves the hypothalamus and the pituitary gland, parts of the brain that are important in regulating hormones and many otherbodily functions. In times of stress, the hypothal...

• Mesoamerica.

  for cooking. In other regions, the earliest ceramics are more sophisticated technically and aesthetically. At around 1800 BC in the Pacific coastal region of Soconusco (in what is now southeastern Chiapas State, Mexico), the earliest pottery was very complex both in forms and decoration. It seems to have had a social function and beenused primarily for ritual feasting. III MAJOR CIVILIZATIONS Over a period of 3000 years, beginning in about 1500 BC, a number of important cultures emerged in M...

• 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...

• Telecommunications.

  commonly referred to as wireless communications, use technologies such as cordless telephones, cellular radio telephones, pagers, and satellites. Wirelesscommunications offer increased mobility and flexibility. In the future some experts believe that wireless devices will also offer high-speed Internet access. C Wires and Cables Wires and cables were the original medium for telecommunications and are still the primary means for telephone connections. Wireline transmission evolved fromtelegraph...

• Orthodox Church.

  formally defined by an ecumenical council, as it was in Catholicism, some Orthodox theologians have taught that the act of becoming a monk or the service of burial canalso be sacraments. The sacramental practice of the Orthodox differs in many details from Western customs. Baptism is administered by immersing the child or adult three times under thewater, each time in the name of one of the persons of the Trinity. It is followed immediately by anointment with chrism, a sacred perfumed oil that r...

• Georgia (country) - country.

  1917. During the subsequent Soviet period, religious practice was strongly discouraged because the Soviet state was officially atheistic; however, the GeorgianOrthodox Church was allowed to function openly. Orthodox Christianity is the religion of about 58 percent of the Georgian population. Muslims represent about 19 percent of the country’s population, with ethnicAzerbaijanis, Kurds, and Ajars comprising the principal Muslim groups. Ajars are ethnic Georgians who converted to Islam in the 17th...

• Haiti - country.

  Haitian Creole and French are the official languages of Haiti. Haitian Creole, a French-based Creole with influences from West African languages, was made an officiallanguage under the 1987 constitution. It is the mother tongue for nearly the entire population of Haiti and the language of instruction in schools. French is spokenmainly as a second language by a small section of the population. B Religion About 80 percent of Haiti’s people are nominal Roman Catholics, many of them combining an Af...

• Railroads.

  III GAUGES The gauge of track is the distance between the inner edges of the rails at points 1.59 cm (0.626 in) below the top of the heads. In the United States, Canada, theUnited Kingdom, Mexico, Norway, Sweden, and much of continental Europe, the standard gauge is 143.51 cm (56.5 in). Why this measurement became the standard isa matter of speculation. Probably the tradition is inherited from early tramroads built to accommodate wagons with axles 1.5 m (5 ft) long; some of the early edge rail...

• Church, Alonzo

  principal expression of this language is an abstraction operator which is used to construct an expression for a function from an expression for an arbitrary value. For example, ' ¸x:x 2 ' denotes the function which takes any number to its square. The rules of transformation (conversion) of the calculus provide a guide for derivations among expressions of the above type. The ¸-calculus has had a significant effect on the development of logic. It was shown that the original formulation of the...

• VAR

  Accordingly, continuous distributions are described with probability density functions as illustrated in Exhibit 2 below: In Exhibit 2, the curve shows how densely probability is distributed across the sample space. Area under the curve corresponds to probability. For example, in Exhibit 3, the area of the yellow region corresponds to the probability that the random variable will be between 0 and 2perhaps a total probability of 31%. The normal and lognormal distributions are examples of conti...

• Quantum Theory I INTRODUCTION Quantum Theory, in physics, description of the particles that make up matter and how they interact with each other and with energy.

  electron in the same way a particle with momentum would: It bumps the electron and changes the electron’s path. The light is also affected by the collision as though itwere a particle, in that its energy and momentum changes. Momentum is a quantity that can be defined for all particles. For light particles, or photons, momentum depends on the frequency, or color, of the photon, which in turndepends on the photon’s energy. The energy of a photon is equal to a constant number, called Planck’s cons...

• Confucian philosophy, Chinese

  occupies a pre-eminent place in the history of Chinese philosophy. The core of Confucian thought lies in the teachings of Confucius (551-479 BC) contained in the Analects ( Lunyu ), along with the brilliant and divergent contributions of Mencius (372?-289 BC) and Xunzi ( fl. 298-238 BC), as well as the Daxue (Great Learning) and the Zhongyong (Doctrine of the Mean), originally chapters in the Liji (Book of Rites). Significant and original developments, particularly along a quasi-metaphysica...

• Color I INTRODUCTION Color © Microsoft Corporation.

  The colors that absorb light of the additive primary colors are called subtractive primary colors. They are magenta (purplish-pink), which absorbs green; yellow, whichabsorbs blue; and cyan (light greenish-blue), which absorbs red. Thus, if a green light is thrown on a magenta pigment, the eye will perceive black. These subtractiveprimary colors are also called the pigment primaries. They can be mixed together in varying amounts to match almost any hue. If all three are mixed in about equalamoun...

• common law v equity

  were named sheriffs. The Lords performed judicial functions and perceived the tax. They were itinerant judges and watched on the occasion of their judicial tour that royal decrees were observed but also that the peace of the kingdom was maintained. On returning to the Big Council(Advise), these Lords were involved in the legislative decisions which belonged to king. The first specialized court was the Court of Exchequer who already...

• Vertebrate - biology.

  E Reptiles Compared to amphibians, reptiles are much more fully adapted to life on land. They have scaly, waterproof skin, and they either give birth to live young or lay eggs withwaterproof shells. There are about 7,000 species alive today, including snakes, alligators, and turtles. During the age of the dinosaurs, about 230 million to 65 millionyears ago, reptiles outnumbered all other land vertebrates put together. F Birds Birds evolved from flightless reptiles but underwent some major chan...

• Checks and Balances.

  no political interest has enough power to prevail over the others. In 1997 and early 1998, for example, the Senate refused to take action on many of President BillClinton’s appointments of new federal court judges. Although the Senate’s power to approve or reject federal court nominees is one of the key checks on presidentialauthority, the dispute between Clinton and the Senate meant that there were not enough federal judges to handle the court’s workload. But the system of checks andbalance was...

• Mental Retardation.

  For example, measles, chicken pox, and whooping cough may lead to encephalitis and meningitis, which can damage the brain. Physical trauma to the brain can also cause mental retardation. Brain damage may result from accidental blows to the head, near drowning, severe child abuse, andchildhood exposure to such toxins as lead and mercury. Experts believe that poverty and a lack of stimulation during infancy and early childhood can be factors inmental retardation. Children raised in poor environmen...

• instruction c_51

• Aerospace Medicine - astronomy.

  medically as aeroembolism and popularly as the bends, leads to confusion, paralysis, or neurocirculatory collapse. The most characteristic symptoms of the bends arepain in the large joints resulting from pressure of the gas on tendons and nerves, together with spasm of the blood vessels. Preflight inhalation of pure oxygen toeliminate nitrogen from the system has proved valuable as a preventive measure. Rapid decompression, resulting from accidental failure at high altitudes of thepressure withi...

• 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...

• Political Parties.

  In both Britain and the United States, competition between political parties undermined traditional conceptions of politics rooted in classical and Christian notions ofvirtue and public service. According to this tradition, political leaders should act according to a model of virtue that involved placing the common good above theinterests of a fraction of the society. Leaders acting to benefit only themselves or a narrow portion of the society were considered corrupt. However, party competitionr...

• Roman Mythology I INTRODUCTION Roman Mythology, the religious beliefs and practices of the people of ancient Rome.

  Aeneas and AnchisesAccording to mythology, Aeneas was a Trojan prince. After Troy fell to the Greeks during the Trojan War, Aeneas traveledto Italy and met and married a woman in the kingdom that occupied the region that would one day become Rome.Through this marriage, Aeneas was the direct ancestor of Romulus and Remus, the legendary founders of Rome. In thispainting he is carrying his father, Anchises, on his back while fleeing from Troy. This painting by Lionello Spada is in theLouvre Museum...

• Physical Chemistry - chemistry.

  by the system in the form of the flow of electrical currents, formation of surfaces and changes in surface tension, changes in volume or pressure, and formation ordisappearance of chemical species. B Chemical Kinetics This field studies the rates of chemical processes as a function of the concentration of the reacting species, of the products of the reaction, of catalysts and inhibitors, ofvarious solvent media, of temperature, and of all other variables that can affect the reaction rate. It is...

• Army. I INTRODUCTION Army, military land forces of a nation, assembled, drilled, disciplined,

  disappearance for several centuries of large standing armies in Europe. A Middle Ages Feudalism was based on a concept of local defense, each baron or landowner governing land that had been given him by the king, and each lord having his ownpersonal protective forces recruited from among men who worked for him. In return, each lord and his men were pledged to annual service to the monarch and couldbe called on in special instances, as in the defense of Christendom during the Crusades. National...

• Wireless Communications.

  were large, heavy units. After the invention of the transistor in 1948, radios shrank in size to small handheld radio transceivers. Public two-way radios with severalfrequency options are widely available as well. Usually limited in range to a few miles, these units are great aids for such mobile professionals as construction workers,film crews, event planners, and security personnel. Simpler two-way radios, called walkie-talkies, have been popular children’s toys for years. Most walkie-talkiesb...

• 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...

• Helicopter.

  naturally flaps down so as to increase lift. Flapping allows the differences in lift caused by uneven rotor tip speed to cancel out, producing a stable ride. Many helicoptersuse mechanical hinges with lubricated bearings, but some use flexible straps made of a composite material in order to reduce the required maintenance. Helicopters require different amounts of lift and thrust at different times during flight, because the aerodynamic forces acting on them change during hovering andacceleration...