112 résultats pour "specific"
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Electronics.
electronic circuits. The resistors are made from carbon mixtures, metal films, or resistance wire and have two connecting wires attached. Variable resistors, with anadjustable sliding contact arm, are often used to control volume on radios and television sets. E Capacitors Capacitors consist of two metal plates that are separated by an insulating material ( see Capacitor). If a battery is connected to both plates, an electric charge will flow for a short time and accumulate on each plate. If th...
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Extrasolar Planets - astronomy.
When a planet passes in a front of the star it orbits—an event called a transit—it causes a small dip in the brightness of the star. Measuring the slight change in thebrightness can be used not only to directly detect a planet, but to determine its size and orbit. However, the planet needs to orbit in a plane that lies in a telescope’sline of sight on the star. Despite long odds, Earth-based telescopes have detected and studied a few exoplanets using this method. The first space telescope design...
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Observatory - astronomy.
Ultraviolet radiation, X rays, and gamma rays have shorter wavelengths than visible light has. These types of radiation tell astronomers about the hottest and mostviolent phenomena in the universe. Earth’s atmosphere blocks most of this radiation, so astronomers must send their observatories above the atmosphere aboardballoons, rockets, or satellites. Ultraviolet telescopes are much like visible light telescopes, but X-ray telescopes must have special nested cylindrical mirrors to prevent Xrays...
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Aztec Empire.
tribute to the empire in agricultural products, which were used to finance public projects. All able-bodied men owed military service to the empire. Citizens could also bedrafted to work on public lands or build temples, dikes, aqueducts, and roads. Although Aztec society had strict classes, a person’s status could change based on his or her contribution to society. Commoners could improve their rank, especially byperforming well in battle, and become prosperous landowners. Young people of some...
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Aztec Empire - USA History.
tribute to the empire in agricultural products, which were used to finance public projects. All able-bodied men owed military service to the empire. Citizens could also bedrafted to work on public lands or build temples, dikes, aqueducts, and roads. Although Aztec society had strict classes, a person’s status could change based on his or her contribution to society. Commoners could improve their rank, especially byperforming well in battle, and become prosperous landowners. Young people of some...
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Apollo Program - astronomy.
Moon’s orbit; rendezvousing and docking with the CSM; and finally, setting a course home to Earth. On return to Earth, the spacecraft was slowed by drag from Earth’satmosphere and by parachutes (just before splashdown), before landing in the ocean. The transit time to and from the Moon was approximately three days each way.Depending on the specific mission, the time in lunar orbit ranged from less than one day for Apollo 8 to over six days for the final three missions, and the time on thelunar s...
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Apollo Program - U.
Moon’s orbit; rendezvousing and docking with the CSM; and finally, setting a course home to Earth. On return to Earth, the spacecraft was slowed by drag from Earth’satmosphere and by parachutes (just before splashdown), before landing in the ocean. The transit time to and from the Moon was approximately three days each way.Depending on the specific mission, the time in lunar orbit ranged from less than one day for Apollo 8 to over six days for the final three missions, and the time on thelunar s...
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Theater
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INTRODUCTION
The Art of Theater
BBC Worldwide Americas, Inc.
Theater at EpidaurusAncient Greek dramas were performed in open-air theaters like this one in Epidaurus, Greece, which was designed byPolyclitus the Younger in 350 bc. A festival of ancient Greek drama is still held in the summer in this 14,000-seat theater.Roger Wood/Corbis Fundamental to the theater experience is the act of seeing and being seen; in fact, the word theater comes from the Greek word theatron , meaning 'seeing place.' Throughout the history of world cultures, actors have used...
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Alcoholism.
Although a consensus is growing among health professionals that alcohol dependence is a disease, society’s attitudes toward individuals with drinking problems remainambivalent and confused. Until the mid-20th century, the typical picture of the alcoholic was of someone without steady employment, unable to sustain familyrelationships and most likely in desperate financial straits. But this stereotype was largely dispelled when highly respected people publicly admitted their alcoholdependence and...
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Horse Racing.
interested parties claim the same horse at the same price, lots are drawn to determine the winning offer. Knowledgeable owners and trainers may use claiming races toobtain, at bargain prices, horses whose former owners underestimated the potential of their animals. Two other types of contests are match races and walkovers. A match race pits only two horses, almost always that season’s most successful racers, in a head-to-headduel. A walkover occurs when only one horse has not been scratched (w...
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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...
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Taxation.
Thus, corporate income faces a higher tax burden than income earned by individuals or by other types of businesses. Tax legislation passed in 2003 in the United Statesattempted to address this issue by lowering the tax rate on dividends. Some economists have proposed abolishing the corporate income tax and instead taxing the owners of corporations (shareholders) through the personal income tax.Other students of the tax system see the corporate income tax as the price corporations pay in return f...
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Welfare.
industrializing societies. Governments typically financed social insurance programs with tax funds and direct levies on the wages of potential recipients. Social insurancereplaced part of incomes lost when workers became disabled, were laid off, or had reached an age that forced them out of the labor market. Later, governments of Germany, France, Belgium, Sweden, and other countries developed forms of social insurance that provided population-wide, or universal,coverage. Such forms included chil...
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September 11 Attacks - U.
around and flew it back toward Washington, D.C. Flying low and fast, the airplane hit the Pentagon at 9:37 AM. In a bit of good fortune, the plane crashed into the west side of the building, which had recently been reinforced with stronger construction and blast-resistant windows in order to withstand a terrorist attack. Even so, theplane penetrated three of the Pentagon’s five concentric rings, taking a chunk out of the building and incinerating dozens of offices and the people who worked in t...
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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...
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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...
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Cell (biology) - biology.
proteins, or other proteins required by the cell. While relatively simple in construction, prokaryotic cells display extremely complex activity. They have a greater range of biochemical reactions than those found in theirlarger relatives, the eukaryotic cells. The extraordinary biochemical diversity of prokaryotic cells is manifested in the wide-ranging lifestyles of the archaebacteria andthe bacteria, whose habitats include polar ice, deserts, and hydrothermal vents—deep regions of the ocean un...
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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...
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Western Music
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INTRODUCTION
Bizet's Carmen
Georges Bizet's Carmen, first performed in Paris in 1875, was a milestone in the history of French opera.
church ceremonies during the period from the 5th to the 7th century. Roman chant became known as Gregorian chant after Pope Gregory I, the Great, who may havecomposed some of the melodies and who actively encouraged an orderly, ritualized use of music by the church. Because Gregory and later popes preferred Gregorianchant to the varieties that had developed elsewhere in Europe, Gregorian chant eventually superseded most of the others. Gregorian and other chant styles arepreserved in many manuscr...
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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...
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Indian Treaties in Canada - Canadian History.
Pontiac led an attack on British forts in the Great Lakes area to end British domination and to reinforce Indian autonomy. In response, British king George III issued theRoyal Proclamation of 1763 to try to appease the Indians of the interior. The proclamation set aside land for the Indians west of the Appalachian Mountains anddescribed this land as “lands reserved to [Indians] … as their Hunting Grounds.” The proclamation not only recognized Indian land ownership, but also required thattreaties...
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Film Noir
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INTRODUCTION
Lynch's Blue Velvet
The motion picture Blue Velvet (1986) brought wide acclaim to American director David Lynch.
Double IndemnityBarbara Stanwyck and Fred MacMurray are featured in Double Indemnity (1944), a story of lust and greed in the film noirtradition, directed by Billy Wilder. The film’s events are related in flashbacks by protagonist Walter Neff (MacMurray), whomakes a dying confession about a plot to kill a man for his insurance money.Bettmann/Corbis Another common aspect of film noir is the femme fatale, a seductive woman who lures the protagonist into actions that ultimately lead to his downfall...
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Civil Law.
Beginning in the 15th century, many European countries extensively colonized North and South America, Africa, and parts of Asia ( see Colonialism and Colonies). Colonial expansion spread the civil law system as colonizers imposed their system of law on their colonies. After achieving independence, some former colonies retainedthe legal system established by the colonizer. For example, the African nation of Senegal has retained the civil law system established by France. Other former colonieschos...
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Communism
access to, resources, but the underlying principle is quite similar. Rather than freeing some or even all people in a society to devote themselves to a higher cause, secular communism is designed to allow everyone to pursue personal fulfilment. It may best be characterized by a slogan adopted by Marx that appears to have been first published on the title page of Cabet's Voyage en Icarie (1840): ‘From each according to his ability, to each according to his need' . In other words, each pers...
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Genetics - biology.
construct identical buildings. Just as each contractor would require a full copy of the blueprint to construct a complete building, each new cell needs a complete copy ofan organism’s genetic information to function properly. Organisms use two types of cell division to ensure that DNA is passed down from cell to cell during reproduction. Simple one-celled organisms and other organisms thatreproduce asexually—that is, without the joining of cells from two different organisms—reproduce by a proces...
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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...
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Rembrandt.
myth that the painting was rejected by those who commissioned it, and led to a decline in Rembrandt's reputation and fortune, it was actually well received. Many of Rembrandt's landscapes in this middle period are romantic and based on his imagination rather than recording specific places. The inclusion of ancient ruins androlling hills, not a part of the flat Dutch countryside, as in River Valley with Ruins (Staatliche Gemäldegalerie, Kassel), suggests a classical influence derived from Italy...
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Personality Disorders.
People with histrionic personality disorder constantly strive to be the center of attention. They may act overly flirtatious or dress in ways that draw attention. They may also talk in a dramatic or theatrical style and display exaggerated emotional reactions. F Narcissistic Personality Disorder People with narcissistic personality disorder have a grandiose sense of self-importance. They seek excessive admiration from others and fantasize about unlimited success or power. They believe they...
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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...
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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...
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Development (biology) - biology.
Understanding the molecular machinery within cells gives biologists a direct basis for understanding growth, because growth is the synthesis of new protoplasm, andbiologists know the basic mechanism of this synthesis. One key gap, however, exists in this knowledge. Biologists want to know not only how substances aresynthesized but also how growth is controlled so that the proportions of an animal or plant remain consistent from generation to generation. The direction and amountof growth, which a...
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Popular and Social Dance
I
INTRODUCTION
The Cakewalk
The cakewalk, a dance of African American origin, was intended to lampoon high-strutting whites at fancy dress balls.
master. The dance manuals published between 1550 and 1630, written by Thoinot Arbeau of France, Cesare Negri of Italy, and other dancing masters, describe dances such asthe pavane, galliard, allemande, courante, saltarello, and volta, as well as circular branles and progressive longways dances (for a line of couples, in which each couplerepeats the pattern with one new couple after another; see Country Dance). The sense of order and harmony so important during the Renaissance gave rise to forma...
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Dogsledding.
Mushers are caretakers, but also coaches. Top mushers have large kennels, and their preparation for competition begins by buying and breeding race-specific dogs.They train their dogs, decide which to run on certain days, and make adjustments during races by switching and dropping dogs. Serious competitors run their dogsyear-round, using carts and all-terrain vehicles when there is not enough snow on the ground. During races they decide their strategy, choosing when to rest and whento push ahead....
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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...
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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...
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Confucius
official to several of the highest positions in the land. Nor does the story end there. By the time of the Han dynasty (206 BC-AD 220), Confucius was celebrated as the ‘uncrowned king' of the state of Lu, and by the fourth century AD, any prefecture wanting to define itself as a political entity was required by imperial decree to erect a temple to Confucius. Gods in China are local cultural heroes who are remembered by history as having contributed meaning and value to the tradition, and of...
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Electron
I
INTRODUCTION
Models of the Atom
Once scientists discovered the electron, they set out to explain how electrons behave in atoms.
Electron Density and Orbital ShapesAtomic orbitals are mathematical descriptions of where the electrons in an atom (or molecule) are most likely to be found.These descriptions are obtained by solving an equation known as the Schrödinger equation, which expresses ourknowledge of the atomic world. As the angular momentum and energy of an electron increases, it tends to reside indifferently shaped orbitals. The orbitals corresponding to the three lowest energy states are s, p, and d, respectively....
- The way in which companies frame themselves, their products and their clients
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Genetic Engineering.
Pseudomonas fluorescens bacterium. The genetically altered Pseudomonas fluorescens bacterium produces light in proportion to the amount of its activity in breaking down the naphthalene, thus providing a way to monitor the efficiency of the process ( see Bioremediation). A3 Medicine In 1982 the United States Food and Drug Administration (FDA) approved for the first time the medical use of a recombinant DNA protein, the hormone insulin, whichhad been cloned in large quantities by inserting th...
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Blood.
substances. For example, a person who is blood type A positive will not make antibodies against the A or Rh markers, but will make antibodies against the B marker,which is not on that person’s own red blood cells. If blood containing the B marker (from types B positive, B negative, AB positive, or AB negative) is transfused into thisperson, then the transfused red blood cells will be rapidly destroyed by the patient’s anti-B antibodies. In this case, the transfusion will do the patient no good a...
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Influenza.
days and disappear in seven to ten days. However, coughing and fatigue may persist for two or more weeks. Death from influenza itself is rare. But influenza can aggravate underlying medical conditions, such as heart or lung disease. Invading influenza viruses produceinflammation in the lining of the respiratory tract, damage that increases the risk that secondary infections will develop. Common complications include bronchitis,sinusitis, and bacterial pneumonia, occurring most frequently in olde...
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Heredity - biology.
allele from the mother and a mutated allele from the father. In both of these cases, the child will be a carrier. The child develops the disease only if he or she receives amutated allele from each parent. When both parents are carriers, there is a 25 percent chance that a child will be disease-free, a 25 percent chance that it will have thedisease, and a 50 percent chance that it will be a carrier. Examples of genetic diseases that follow the dominant-recessive pattern include sickle-cell anemi...
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Jazz
I
INTRODUCTION
Joshua Redman
Saxophonist Joshua Redman, a graduate of Harvard University, became a fast-rising star in jazz in the 1990s.
performed a highly produced, jazz-inspired form of blues that was popular in traveling minstrel shows and vaudeville. Thisexample is from the song “St. Louis Blues,” written by American composer and trumpet player W. C. Handy in 1914 andrecorded by Smith in 1925."St. Louis Blues" performed by Bessie Smith, from The Riverside History of Classic Jazz (Cat.# Riverside RB-005) Riverside Records under master license to Fantasy, Inc. All rightsreserved./Frank DriggsCollection/Archive Photos Jazz is ro...
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Moon - astronomy.
B Volcanic Features Maria, domes, rilles, and a few craters display indisputable characteristics of volcanic origin. Maria are plains of dark-colored rock that cover approximately 40 percent ofthe Moon's visible hemisphere. The maria formed when molten rock erupted onto the surface and solidified between 3.16 billion and 3.96 billion years ago. This rockresembles terrestrial basalt, a volcanic rock type widely distributed on Earth, but the rock that formed the maria has a higher iron content an...
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Cloning - biology.
found that such embryo cells are totipotent (able to give rise to all the different cell types in the body). Exploiting this characteristic, scientists developed three techniques to clone embryo cells: blastomere separation, blastocyst division, and somatic cell nuclear transfer. A Blastomere Separation In blastomere separation, scientists fertilize an egg cell with a sperm cell in a laboratory dish. The resulting embryo is allowed to divide until it forms a mass of aboutfour cells. Scientist...
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Tennis.
and interpret rules. The head official on the court, called the chair umpire, sits on a tall chair at one end of the net. A varying number of line judges sit around the courtbeyond the path of the players. Line judges determine whether serves and shots are good or out. A net-cord judge may be employed to determine when a ball touchesthe top of the net, and a foot-fault judge may watch for that specific infraction. In the 1980s electronic devices began to be used in some professional tournaments...
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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...
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Light - astronomy.
Each different frequency or wavelength of visible light causes our eye to see a slightly different color. The longest wavelength we can see is deep red at about 700 nm.The shortest wavelength humans can detect is deep blue or violet at about 400 nm. Most light sources do not radiate monochromatic light. What we call white light,such as light from the Sun, is a mixture of all the colors in the visible spectrum, with some represented more strongly than others. Human eyes respond best to greenlight...
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Geology.
terminology. Today the geologic time scale is generally agreed upon and used by scientists around the world, dividing time into eons, eras, periods, and epochs. Everyfew years, the numerical time scale is refined based on new evidence, and geologists publish an update. Geologists use several methods to determine geologic time. These methods include physical stratigraphy, or the placement of events in the order of their occurrence,and biostratigraphy, which uses fossils to determine geologic time...
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Kenya - country.
threatens fish and other water life in the lake by depriving them of oxygen. Kenya is well known for its game parks—including Masai Mara Game Park and Tsavo National Park in the south, and Marsabit National Reserve in the north—whichattract large numbers of tourists and much revenue. Conservation of wildlife within reserves has thus received high priority. About 13 percent (2007) of Kenya’s totalland is protected. There are 229 (2004) threatened species in Kenya. Threatened habitats include the...