230 résultats pour "single"

• Débat Single Sex School

  ways to learn, independence, participation during class, ability to succeed in school, attitude in school, behavior in school and grades. Highlights of the survey results included: · Roughly three-quarters of the students who participated in the survey believed that single-gender classes were contributing factors to their improvements in each category. · Although both boys and girls gave positive reviews to the single-gender experience, the strongest endorsements came from girls. Four ou...

• Folk Art I INTRODUCTION Carved Native American Figure This figure of a Native American trapper was carved from a single pine log (about 1850-1890).

  that young Native American women were taught to weave by Ursuline nuns. The overall spirit of French-Canadian folk art is colorful, happy, and, at the same time,devout. B Anglo-Canadian Folk Art The English tradition in the Maritime provinces is strong in the decoration of utilitarian objects, in graining, marbling, and incising, and in ship carvings (both figureheadsand stern-board decorations). The emigration to Canada of many New Englanders during and after the American Revolution led to int...

• Badminton.

  Once play has started, players tend to hit straight, low-flying shots called drives. When the shuttle remains close to the center of the court, net shots can be a goodoption. Net shots can be hard-hit or delicate. They are aimed at the front area of the opponent’s court, forcing the opponent to play the shot close to the net. If the opponent manages to return a net shot, the return must be hit high to clear the net. This gives the player a chance for a smash—the deadliest attacking stroke inbadm...

• European Union .

  safeguard the interests of the member states, a common assembly with advisory authority only, and a court of justice to settle disputes. D European Economic Community (EEC) In 1957 the participants in the ECSC signed two more treaties, known as the Treaties of Rome. These treaties created the European Atomic Energy Community(Euratom) for the development of peaceful uses of atomic energy and, most important, the European Economic Community (EEC, often referred to as the CommonMarket). The EEC tr...

• 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...

• Electric Motors and Generators.

  the armature. It is often desirable to generate as high a voltage as possible, and rotating armatures are not practical in such applications because of the possibility of sparkingbetween brushes and slip rings and the danger of mechanical failures that might cause short circuits. Alternators are therefore constructed with a stationary armaturewithin which revolves a rotor composed of a number of field magnets. The principle of operation is exactly the same as that of the AC generator described,...

• Horse - biology.

  Horses reach sexual maturity at about one and a half years. The estrous cycle in the mare—a mature female horse—typically lasts 21 days. During the first five days ofthe cycle, the mare is usually receptive to mating. The estrous cycle stops during winter and resumes in the spring, which is the start of the breeding season. Astallion—a mature male horse—approaching a mare in estrus engages in various courtship rituals. These include uttering nickering sounds and sniffing and licking themare’s ge...

• Steam Engine.

  wear caused by this pressure, steam-engine valves are frequently made in a cylindrical form entirely enclosing the piston, so that the pressure is equal all around thevalve and friction is minimized. The development of this type of valve is attributed to the American inventor and manufacturer George Henry Corliss. In other types ofslide valves, the moving portion of the valve is designed so that steam does not press directly on the back of the valve. The linkage between the piston of the engine...

• Inorganic Chemistry - chemistry.

  two electrically charged plates (positively charged top plate and negatively charged bottom plate). By measuring the difference in how fast these electron-laden oildrops fell when the metal plates were charged and uncharged, Millikan was able to calculate the total charge on each oil drop. Because each measurement was a wholenumber multiple of -1.60 × 10 -19 coulombs, Millikan concluded this was the charge carried by a single electron. Using Thomson’s electron charge-to-mass ratio, Millikan then...

• Internet.

  usually pays a fixed monthly fee for a dedicated connection. In exchange, the company providing the connection agrees to relay data between the user’s computer andthe Internet. Dial-up is the least expensive access technology, but it is also the least convenient. To use dial-up access, a subscriber must have a telephone modem, a device thatconnects a computer to the telephone system and is capable of converting data into sounds and sounds back into data. The user’s ISP provides software that con...

• New York - geography.

  The Adirondack province consists of a large highland area occupying 26,000 sq km (10,000 sq mi) in the northeastern quarter of the state. The region is domelike inshape, with the higher elevations toward the east. The western Adirondack province is more a rugged hill region and not truly mountainous. Geologically, this area isrelated to the Laurentian Upland, or Canadian Shield, which lies north of the St. Lawrence River, for it is composed of the same very old igneous rocks, principallygranite...

• New York - USA History.

  The Adirondack province consists of a large highland area occupying 26,000 sq km (10,000 sq mi) in the northeastern quarter of the state. The region is domelike inshape, with the higher elevations toward the east. The western Adirondack province is more a rugged hill region and not truly mountainous. Geologically, this area isrelated to the Laurentian Upland, or Canadian Shield, which lies north of the St. Lawrence River, for it is composed of the same very old igneous rocks, principallygranite...

• 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...

• Computer Memory.

  been created, information can be retrieved but not changed. Newer technologies allow ROMs to be semi-permanent—that is, the information can be changed, but ittakes several seconds to make the change. For example, a FLASH memory acts like a ROM because values remain stored in memory, but the values can be changed. C External Memory External memory can generally be classified as either magnetic or optical, or a combination called magneto-optical. A magnetic storage device, such as a computer'shar...

• Fruit - biology.

  from a flower with several pistils. The ovary may have a single compartment, or carpel, which houses the ovule or ovules. Or the ovary may consist of two or morecarpels, each of which may contain one or more ovules. A drupe develops from an ovary with a single carpel and is characterized by an edible exocarp and mesocarp and an inedible, hard endocarp, or pit that encloses asingle seed. Cherries, peaches, apricots, and plums are examples of drupes. Almonds also are classified as drupes, but in a...

• Boston - geography.

  The neighborhoods of Allston and Brighton occupy the northwest corner of the city to the west of Fenway. The Allston-Brighton area is bordered to the east, north, andwest by the Charles River and to the south by the Massachusetts Turnpike and the town of Brookline. It is an industrial and residential neighborhood that is also thelocation of Boston College and Harvard University Business School. Boston has been unsuccessful in annexing Brookline, the birthplace of U.S. president John F.Kennedy an...

• 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...

• 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...

• Child Abuse.

  C Social Isolation and Low Community Involvement Parents and caretakers who abuse children tend to be socially isolated. Few violent parents belong to any community organizations, and most have little contact withfriends or relatives. This lack of social involvement deprives abusive parents of support systems that would help them deal better with social or family stress. Moreover,the lack of community contacts makes these parents less likely to change their behavior to conform with community va...

• NHL Top Scorers in a Single Season.

• Confucian philosophy, Korean

  neglected by more traditional Confucianism. Read with new eyes, an entirely new level of meaning was uncovered in the ancient texts: they discovered a Confucian foundation for the meditative cultivation of consciousness that had been a particular strength of the Buddhists, and to frame it and provide an account of sagehood equal to Buddhist talk of enlightenment, they found a complete metaphysical system, a Confucian version of the kind of thinking that had been elaborated mainly under Daoist au...

• Biodiversity.

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

• Biodiversity - biology.

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

• Dolphin (aquatic mammal) - biology.

  Scientists have observed dolphins displaying three types of caregiving behaviors: standing by, excitement, and supporting. In standing-by behavior, dolphins remain inthe vicinity of an injured or ill companion without offering aid. In excitement behavior, dolphins swim swiftly in circles around an injured dolphin, responding aggressivelytoward threats to the injured animal. For instance, they may bite harpoon lines or charge boats that come too close to the animal. In supporting behavior, one or...

• Ship. I INTRODUCTION Ship, vessel that is buoyant in the water and used

  B1 Biremes Experience soon proved that longer ships posed a new set of problems: They were weaker structurally, more difficult to maneuver, and presented a larger target to anyenemy ship with a ram. In the 8th century BC Mediterranean shipbuilders eliminated these problems with the bireme , a war galley built to accommodate two levels, or banks , of oarsmen. Oarsmen on the lower level rowed oars from ports cut into the side of the vessel, while those above rowed from the deck. This arrangemen...

• 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...

• Bicycle.

  narrow as possible to minimize weight and interference with pedaling. F Specialty Bicycles Many other types of bicycles are designed for special purposes. Although not as common as standard single-rider racing, touring, mountain, or recreational bicycles,they nonetheless have significant niches. Recumbent bicycles are bicycles on which the rider sits upright as if in a chair, with legs and feet stretched out in front. Because they support the rider’s lower back,recumbents allow the rider far mo...

• Constitution of the United States.

  chief executive should have the power to veto legislation, should be elected by Congress or the people, should be eligible to run for reelection, and should command thearmed forces. Some delegates even hoped for a limited monarchy. Not until September 8, more than three months after the convention started, did the final shape ofthe presidency emerge: a single leader, elected to a four-year term and eligible for reelection, with authority to veto bills enacted by Congress. The president was alsog...

• Constitution of the United States - U.

  chief executive should have the power to veto legislation, should be elected by Congress or the people, should be eligible to run for reelection, and should command thearmed forces. Some delegates even hoped for a limited monarchy. Not until September 8, more than three months after the convention started, did the final shape ofthe presidency emerge: a single leader, elected to a four-year term and eligible for reelection, with authority to veto bills enacted by Congress. The president was alsog...

• 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...

• Alphabet I INTRODUCTION Bengali Script India developed a number of different writing systems over the course of its history.

  A Pictographic and Ideographic Systems Early systems of writing used pictures to represent things and then to represent the sounds of those things. Pictographic writing, in which a simplified picture of the sunstood for the word sun, was probably the first step toward a written language. Chinese began as a pictographic language. To represent abstract ideas, the Chinese writing system combined pictographs. For example, the pictographs for sun and tree were combined to represent the concept of...

• Automobile Racing.

  beginning in 1906 at Le Mans it came to refer to the principal F1 auto race in a given nation, except in the United States, where the term continues to be used lessdiscriminately. After the end of World War I in 1918, when automobile racing blossomed internationally, a series of GP races in several nations became reserved for F1competition, and an annual GP calendar was developed consisting of national races, such as the French Grand Prix and the British Grand Prix. An annual award calledthe Wor...

• Fascism.

  values as coming before a radical political transformation. Others argue that a radical political transformation will then be followed by a change in values. Fascists claimthat the nation has entered a dangerous age of mediocrity, weakness, and decline. They are convinced that through their timely action they can save the nation fromitself. Fascists may assert the need to take drastic action against a nation's 'inner' enemies. Fascists promise that with their help the national crisis will end an...

• Latin American Music I INTRODUCTION Tito Puente Playing the Drums Since the 1950s American drummer Tito Puente has popularized Latin American music, especially the mambo, in the United States.

  Panpipe Music of BoliviaWell before the Spanish conquest, native peoples such as the Quechua and Aymara living in the Andes Mountains inBolivia, Peru, and Ecuador, developed a rich musical tradition. Panpipes (set of tuned pipes), made of ceramic, sugarcane,or bone were paired with shell trumpets, cane flutes, and drums, which accompanied dancers during religious and secularceremonies. Large ensembles of 4 to 20 panpipe players are still the norm, and Spanish influences have since beenintegrated...

• Rhinoceros - biology.

  Male and female rhinos have a similar physical appearance, although male rhinos are usually larger than females, with the size difference varying between species. Inthe wild, some rhinos probably live into their late 40s, and they have survived into their 30s in captivity. IV TYPES OF RHINOCEROSES Until recently, mammalogists divided the rhinoceros family into three subfamilies, each with different characteristics. Scientists now believe that living rhinos belong to asingle subfamily, although...

• Ice Skating.

  cold climate. Competitors for these events are chosen from the best skaters in each participating country, usually through preliminary national competitions. Speedskaters also compete on a World Cup circuit, which pits the world’s best skaters against one another during the year. A Figure Skating The major types of competitive figure skating are individual men’s and women’s competitions, pairs skating, ice dancing, and precision skating. In individualcompetitions a single skater performs requir...

• Nanotechnology.

  ever-finer method of reducing material to the nanoscale size. Instead, nanostructures would be assembled atom by atom and molecule by molecule, from the atomiclevel up, just as occurs in nature. However, assembly at this scale has its own challenges. In school, children learn about some of these challenges when they study the random Brownian motion seen in particles suspended in liquids such as water. Theparticles themselves are not moving. Rather, the water molecules that surround the particles...

• Insect - biology.

  they almost always have six legs. In some insects, such as beetles, the legs are practically identical, but in other insects each pair is a slightly different shape. Still otherinsects have specialized leg structures. Examples are praying mantises, which have grasping and stabbing forelegs armed with lethal spines, and grasshoppers andfleas, which have large, muscular hind legs that catapult them into the air. Mole crickets’ front legs are modified for digging, and backswimmers have hind legs de...

• Airplane.

  For example, the Anglo-French Concorde, a commercial supersonic aircraft, was generally limited to over-water routes, or to those over sparsely populated regions ofthe world. This limitation impacted the commercial viability of the Concorde, which ended its regular passenger service in October 2003. Designers today believe theycan help lessen the impact of sonic booms created by supersonic airliners but probably cannot eliminate them. One of the most difficult practical barriers to supersonic fl...

• La Legende des Siecles Ce livre, c'est le reste effrayant de

  Que rien puisse, en criant: Quoi, j'étais inutile! Dans le gouffre à jamais retomber éperdu; Et le lien sacré du service rendu, A travers l'ombre affreuse et la céleste sphère, Joint l'échelon de nuit aux marches de lumière. Hope is indeed the keynote of Hugo's poetry. In the darkest days of 1871, when France was tearing out her own vitals and Paris was destroying itself, he could write thus: Les récits montrent l'un après l'autre leurs têtes, Car les évènements ont leur cap des Temp...

• Indianapolis - geography.

  Amateur athletic competitions are frequent in Indianapolis. Each summer it is the site for the finals of the Hoosier State Games, with athletes of all ages and skill levelscompeting in 21 sports. In 1987 Indianapolis hosted the Tenth Pan American Games, and is often the site for numerous Olympic trials and collegiate sportschampionships. Among the many sports facilities are those for tennis, bicycle racing, skating, and track and field. The city’s professional football team, the Indianapolis Col...

• Classification - biology.

  species based on the fewest number of shared changes that have occurred from generation to generation. IV HISTORY OF CLASSIFICATION SYSTEMS Classification is one of the oldest sciences, but despite its age it is still a vigorous field full of new discoveries and methods. Much like other fields of science, greatthinkers have shaped the course of classification. One of the earliest classification schemes was established by Greek philosopher Aristotle, who lived in the 300s BC. Aristotle believe...

• Sailing.

  the sails sweep across the decks of the vessel from one side to the other, and also because of the danger of breaking spars. In wild jibing, control can be lostmomentarily and, if the seas are high, a small boat can broach —that is, veer on its side with danger of swamping or capsizing. An unintentional jibe in a heavy wind frequently has enough force to break the masts of a vessel. When jibing intentionally, careful sailors always haul in on the boom while turning, so that the boom willtravel...

• Buenos Aires (city) - geography.

  The city has produced or nurtured many of the most prominent Spanish-language writers of the 20th century, including Jorge Luis Borges, Julio Cortázar, and ManuelPuig. Buenos Aires has long been one of the primary centers of Spanish-language publishing and printing, and it is home to major publishing companies. It supports theoldest English-language daily newspaper in Latin America, the Buenos Aires Herald, published since 1876. The arts have a long, rich history in Buenos Aires. This is mani...

• Primate - biology.

  The primate order includes a handful of species that live entirely on meat (carnivores) and also a few that are strict vegetarians (herbivores), but it is composed chieflyof animals that have varied diets (omnivores). The carnivorous primates are the four species of tarsiers, which live in Southeast Asia. Using their long back legs, thesepocket-sized nocturnal hunters leap on their prey, pinning it down with their hands and then killing it with their needle-sharp teeth. Tarsiers primarily eat in...

• Antelope - biology.

  antelopes still display complex patterns of behavior, although much of it is instinctive rather than learned. In open habitats, antelopes run a high risk of predation (being preyed upon). To survive they use several kinds of defensive strategy, including living in herds. Herd living ensures that many pairs of eyes and ears are on the alert for danger. Herd living also gives individuals a better chance of avoiding attack, because predators canchoose from many potential targets. When danger thre...

• Slovakia - country.

  The country is divided informally into the three regions of Western Slovakia, Central Slovakia, and Eastern Slovakia, corresponding to administrative divisions that wereabolished in 1989. Most of Slovakia’s 600,000 Hungarians live in the southern parts of Western and Central Slovakia, which served as the cultural center of Hungary forseveral centuries after Hungary proper was invaded by the Ottomans in the 16th century. The Ruthenian and Ukrainian minorities are concentrated in the northernregio...

• NHL Top Scorers in a Single Season The following are the top scorers in the National Hockey League ranked by the largest number of goals scored in a season.

• Tuberculosis.

  TB has existed for thousands of years. Scars on a skull found in Turkey indicate the presence of the disease 500,000 years ago. Scientists also have found tubercles inmummified bodies from ancient Egypt. References to TB can be found in the writings of ancient Babylonia, Egypt, and China. The term tuberculosis was first used in 1839; it was derived from the Latin word tubercula, meaning small lump, referring to the small scars seen in tissues of infected individuals. TB reappeared in Europe...

• Zebra - biology.

  C Life Span Captive zebras have lived into their late 30s. Life expectancy in the wild, where predators abound, is probably not much more than 12 years. IV SOCIAL BEHAVIOR Like horses, zebras have large brains and a wide variety of social behaviors. Although they cannot match the overall intelligence of mammals that hunt, zebras interactwith each other in complex ways. Zebras usually live in groups known as herds, but the social structure of these groups depends on the species. The plains zeb...