2432 résultats pour "frome"

• Neandertals.

  Neandertals made stone tools by striking flakes from rock “cores.” The cores were carefully selected and prepared so that only a single blow was normally required todetach a flake. A number of relatively standardized flakes were sometimes produced from a single core. These sharp flakes served as “blanks” that were further workedand shaped into the desired tools. Suitable stone was sometimes rare, and often tools were sharpened and resharpened to make new tools, yielding a whole variety ofshapes...

• 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...

• Comoros - country.

  Since 1981 the currency has been the Comorian franc. The Comorian franc had a fixed exchange rate with the French franc of 50 to 1 until 1994, when the rate was changed to 75 Comorian francs to 1 French franc. In 2006, the Comorian franc exchanged at an average of 392 to U.S.$1. Transport between the islands is mostly by air, and there is an international airport at Hahaia on Njazidja where jets can land. Road networks have been built betweenmost of the main island settlements, but the mountai...

• Comte, Isidore-Auguste-Marie-François-Xavier

  1 Life Auguste Comte was born in Montpellier, France. He attended the École Polytechnique, from which he was expelled in 1816, for political reasons. Comte's main concern throughout his life was resolving the political, social and moral problems caused by the French Revolution. To that end, he embarked upon an encyclopedic work, which he first conceived under the inspiration of Henri de Saint-Simon , for whom he worked as secretary from 1817 to 1824. At that time, he proposed several pla...

• Arab-Israeli Conflict.

  the Suez Canal and in 1951 blockaded the Strait of Tiran (Israel’s access to the Red Sea), which Israel regarded as an act of war. In June 1956 Egypt nationalized theSuez Canal, which had been jointly owned by Britain and France. In late October, Israel invaded the Gaza Strip and Sinai Peninsula, defeating Egyptian forces there.Britain and France attacked Egypt a few days later. Although the fighting was brief and Israel eventually withdrew from the Sinai and Gaza, the conflict furtherexacerbate...

• Arab-Israeli Conflict - History.

  the Suez Canal and in 1951 blockaded the Strait of Tiran (Israel’s access to the Red Sea), which Israel regarded as an act of war. In June 1956 Egypt nationalized theSuez Canal, which had been jointly owned by Britain and France. In late October, Israel invaded the Gaza Strip and Sinai Peninsula, defeating Egyptian forces there.Britain and France attacked Egypt a few days later. Although the fighting was brief and Israel eventually withdrew from the Sinai and Gaza, the conflict furtherexacerbate...

• Stem Cell.

  The medical profession used adult stem cells to treat diseases long before anyone isolated one. In 1968 scientists performed the first successful bone marrowtransplant, a procedure in which a patient receives an infusion of healthy bone marrow cells. The purpose of such transplants is to restore the blood-making capabilitiesof the patient’s diseased bone marrow after extremely strong chemotherapy has destroyed that bone marrow. From the beginning investigators suspected that stemcells in the inf...

• Artificial Satellite - astronomy.

  The first stage of a multistage rocket consists of rocket engines that provide a huge amount of force, or thrust. The first stage lifts the entire launch vehicle—with itsload of fuel, the rocket body, and the satellite—off the launch pad and into the first part of the flight. After its engines use all their fuel, the first stage portion of therocket separates from the rest of the launch vehicle and falls to Earth. The second stage then ignites, providing the energy necessary to lift the satellit...

• Human Evolution.

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

• Bac L anglais

  12AN1LME1 Page : 2/4 Joseph Netmaker brought the letter out to me. Winter had just started to settle itself into the country. Joseph walked on snowshoes from the town. ‘This is for you, Niska,’ he said. ‘It is from the Canadian boss, their hookimaw.’ As soon as I saw the brown letter, the English words written upon it, I knew what it contained. I sat down beside the fire and stirred at it with a stick while Joseph read, first out 5 loud and in his stumbling English, then for me in our l...

• Human Evolution - biology.

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

• 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...

• Aegean Civilization .

  warlike. The styles are also more formal and geometric than those of earlier examples, anticipating the art of classical Greece. A typical Mycenaean city had, at its center, the fortress palace of the king. The cities were fortified with massive structures of unevenly cut stones, known as Cyclopeanwalls. The Linear B tablets from this time include names of Greek gods, such as Zeus, and contain detailed records of royal possessions. The gold masks, weapons, andjewelry found by Schliemann at the r...

• Supernova - astronomy.

  The term hypernova has been proposed for an extremely massive core-collapse supernova—possibly more than 100 times the mass of the Sun. A hypernova is thought to form a black hole. Just before it explodes, a hypernova may release a huge burst of gamma rays in a jet from the rotating black hole at its center. These jets mayexplain the so-called long gamma-ray bursts detected by astronomers. According to some researchers, massive stars with over 40 solar masses may sometimescollapse directly int...

• Aegean Civilization - USA History.

  warlike. The styles are also more formal and geometric than those of earlier examples, anticipating the art of classical Greece. A typical Mycenaean city had, at its center, the fortress palace of the king. The cities were fortified with massive structures of unevenly cut stones, known as Cyclopeanwalls. The Linear B tablets from this time include names of Greek gods, such as Zeus, and contain detailed records of royal possessions. The gold masks, weapons, andjewelry found by Schliemann at the r...

• Natural Satellite - astronomy.

  Titan, Saturn’s largest moon, also has few impact craters. Although icy volcanism from water and ammonia may occur along with some tectonic activity, Titan’s youngsurface is most likely the result of weather processes. Titan’s dense, cold atmosphere precipitates particles of complex organic molecules that accumulate as dunes andmountains. Methane rain erodes the surface and creates lakes at the moon’s poles. Triton’s young surface also may result from processes in its atmosphere, as well aserupt...

• Nicaraguan Revolution.

  Directorate. Within a year Robelo and Violeta Chamorro left the junta, and the Council of State was reorganized to guarantee an overwhelming Sandinista majority.Elections were postponed, restrictions were placed on the media, and relations with the Roman Catholic Church became increasingly tense. Two non-Sandinistasreplaced Robelo and Chamorro on the junta, but they had little power, and the government’s relations with opposition political parties and the private business sectordeteriorated. A D...

• Eukaryote - biology.

  The waste is then expelled through a hole in the fused membrane. In complex animals, cells generate wastes such as urea when nutrients are broken down within cells.These wastes are transported by blood to the kidneys. The kidneys process the waste and produce urine, which is removed from the body through the bladder.Undigested food travels through the tubelike intestines and is eliminated through the digestive system. V EVOLUTIONARY ORIGINS Eukaryotes evolved much later than prokaryotes, whose...

• Planetary Science - astronomy.

  III ORIGINS AND COMPOSITIONS OF PLANETS Astronomers believe that planetary systems are formed of elemental materials that were created in the interiors of giant stars. Some of this material comes from giantstars that shed material into space as they age. Most of the matter to form planets, however, comes from stars that explode as supernovas and spread debris enrichedwith the heavier chemical elements into space. According to the currently accepted views, the most likely first stage in the evo...

• Earth (planet).

  Milky Way to complete one revolution around the Galaxy’s center. Earth’s axis of rotation is inclined (tilted) 23.5° relative to its plane of revolution around the Sun. This inclination of the axis creates the seasons and causes the height of the Sun in the sky at noon to increase and decrease as the seasons change. The Northern Hemisphere receives the most energy from the Sun when it is tiltedtoward the Sun. This orientation corresponds to summer in the Northern Hemisphere and winter in the S...

• Earth (planet) - astronomy.

  Milky Way to complete one revolution around the Galaxy’s center. Earth’s axis of rotation is inclined (tilted) 23.5° relative to its plane of revolution around the Sun. This inclination of the axis creates the seasons and causes the height of the Sun in the sky at noon to increase and decrease as the seasons change. The Northern Hemisphere receives the most energy from the Sun when it is tiltedtoward the Sun. This orientation corresponds to summer in the Northern Hemisphere and winter in the S...

• 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...

• Atlantic Slave Trade.

  members of the planters’ society. Through most of the years of the Atlantic trade, prices for Africans remained favorable in relation to the price of the crops theyproduced. They were, thus, the best economic solution for plantation owners seeking inexpensive labor. The Atlantic slave trade began as a trickle in the 1440s and grew slowly through the 17th century. By 1700, 25,000 slaves, on average, were crossing the Atlantic everyyear. After 1700 the trade grew much more rapidly to a peak in the...

• Frog (animal).

  which means that their body temperature depends on the temperature of the surrounding environment. Few species can tolerate temperatures below 4°C (40°F) orabove 40°C (104°F), and many species can survive only within a narrower range of temperatures. In addition, frogs’ thin, moist skin offers little protection againstwater loss, and when on land the animals must guard against drying out. Many frogs are active at night because temperatures are cooler and humidity is higher thanduring the day. In...

• Frog (animal) - biology.

  which means that their body temperature depends on the temperature of the surrounding environment. Few species can tolerate temperatures below 4°C (40°F) orabove 40°C (104°F), and many species can survive only within a narrower range of temperatures. In addition, frogs’ thin, moist skin offers little protection againstwater loss, and when on land the animals must guard against drying out. Many frogs are active at night because temperatures are cooler and humidity is higher thanduring the day. In...

• Comparative Anatomy.

  In comparing two species, anatomists have to be careful to differentiate between homologous structures, which are ones that have evolved from a shared ancestor, andanalogous structures, which have developed from different origins. Homologous structures are built on the same underlying plan. A human arm, a bat’s wing, and awhale’s flipper look quite different from the outside, but the bones inside reveal that these limbs all have the same basic structure. Analogous structures, by contrast,often l...

• Madrid - geography.

  Madrid’s Plaza MayorBuilt in the early 17th century, the Plaza Mayor was used for a variety of activities, including bullfights, executions during theInquisition, and festivals. Today it is one of Madrid’s main tourist attractions.Cesar Lucas/The Image Bank The traditional heart of Madrid is an area 3.9 sq km (1.5 sq mi). In 1656 King Philip IV had a city wall built around the area. Over the next 200 years the city grew throughconstruction of taller buildings and the use of open land within the...

• 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...

• Drug. I INTRODUCTION Drug, substance that affects the function of living cells, used

  normalizing chemical activity in the emotional centers of the brain. Antianxiety drugs, also referred to as tranquilizers, treat anxiety by decreasing the activity in theanxiety centers of the brain. Sedative-hypnotic drugs are used both as sedatives to reduce anxiety and as hypnotics to induce sleep. Sedative-hypnotic drugs act by reducing brain-cell activity.Stimulant drugs, on the other hand, increase neuronal (nerve cell) activity and reduce fatigue and appetite. Analgesic drugs reduce pain...

• Telescope - astronomy.

  Observatory). In some telescopes designed in the 1990s, the mirror’s weight has been dramatically reduced by sandwiching a honeycomb pattern of glass ribs between a thin, butrigid, concave mirror and a flat back plate. Engineers have even developed meniscus mirrors—mirrors that are too thin to support their own weight. An adjustableframework supports the meniscus mirror, and servomechanical actuators, controlled by computer, continually adjust the shape of the mirror as it tracks celestial tar...

• Weather.

  hours, and the snow can be much deeper in places where the wind piles it up in drifts. Extraordinarily deep snows sometimes accumulate on the upwind side ofmountain slopes during severe winter storms or on the downwind shores of large lakes during outbreaks of polar air. VI WIND Wind is the horizontal movement of air. It is named for the direction from which it comes—for example, a north wind comes from the north. In most places near theground, the wind speed averages from 8 to 24 km/h (from 5...

• Arab-Israeli Conflict - history.

  Arab-Israeli War of 1948-1949As early as April 1948 the newly independent nation of Israel put into effect Plan Dalet, which called for the expulsion of PalestinianArabs from areas allotted to the Palestinians under the United Nations (UN) partition plan. The combined forces of several Arabnations and Palestinian guerrillas attacked the Israelis. Israel defeated the Arab forces between 1948 and 1949, taking much of theland that had been granted to the Palestinians by the UN in 1947. Unresolved t...

• Greek Mythology.

  world in search of her; as a result, fertility left the earth. Zeus commanded Hades to release Persephone, but Hades had cunningly given her a pomegranate seed toeat. Having consumed food from the underworld, Persephone was obliged to return below the earth for part of each year. Her return from the underworld each yearmeant the revival of nature and the beginning of spring. This myth was told especially in connection with the Eleusinian Mysteries, sacred rituals observed in the Greektown of Ele...

• United States (Overview) - country.

  parts. IV UNITED STATES PEOPLE When Europeans first reached North America in the 1520s, they encountered other people—Native Americans—and they also encountered a new geography. Someimagined they were entering “a howling wilderness”—an environment filled with exotic flora and fauna but sparsely populated. In reality, they found their way to alandmass that was widely settled. But soon after the Europeans’ arrival, the population of the Americas plummeted, largely because Native Americans lacked...

• 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...

• Basketball.

  rebound. Play continues as the teams score and possession changes. A time-out, when the game is stopped for a certain amount of time, allows coaches to instructplayers or to develop a new game strategy. A Offense Playing offense is perhaps the most prominent part of playing basketball, as it allows players to demonstrate and improve upon individual skills necessary to beingsuccessful. Many of basketball's best players have exceptional talents on offense. Basic offensive skills are passing, ball...

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

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

• Heart.

  situation. A Cardiac Cycle Although the right and left halves of the heart are separate, they both contract in unison, producing a single heartbeat. The sequence of events from the beginning ofone heartbeat to the beginning of the next is called the cardiac cycle. The cardiac cycle has two phases: diastole, when the heart’s chambers are relaxed, and systole,when the chambers contract to move blood. During the systolic phase, the atria contract first, followed by contraction of the ventricles. T...

• Ocean and Oceanography - geography.

  gravity, so the level of the ocean will be lower over valleys. Using this method, a complete survey of the ocean floor was accomplished in less than two years. Maps madefrom data on the level of the ocean surface have been compared with maps made with direct depth measurements and the two types have corresponded well. Using sonar, depth measurements are made by measuring the time for a sound wave to travel from the surface of the ocean to the ocean floor, and to return ( see Sounding). Often sev...

• Psychoanalysis.

  A cornerstone of modern psychoanalytic theory and practice is the concept of anxiety, which institutes appropriate mechanisms of defense against certain dangersituations. These danger situations, as described by Freud, are the fear of abandonment by or the loss of the loved one (the object), the risk of losing the object's love,the danger of retaliation and punishment, and, finally, the hazard of reproach by the superego. Thus, symptom formation, character and impulse disorders, andperversions,...

• Hurricane.

  V HOW HURRICANES ARE DETECTED AND MONITORED Since 1943 U.S. military and civilian aircraft have been flying into hurricanes to measure wind velocities and directions, the location and size of the eye, air pressures,and temperatures in different parts of the storm. A coordinated system of tracking hurricanes was developed in the mid-1950s, and steady improvements have beenmade over the years. In addition to reports from aircraft, geosynchronous weather satellites (since 1966) and ocean buoys tha...

• Volcano.

  before eruption. Very violent explosive eruptions are called Plinian eruptions, after Roman naturalist Pliny the Elder. These eruptions can last for several hours to daysand eject a large amount of pyroclastic material. Some volcanoes can produce much more energetic eruptions that eject materials farther from the vents because oftheir andesitic and dacitic composition. Andesitic and dacitic lava is generally thicker than basaltic lava. Stiff lava generally produces more-explosive eruptions. B No...

• Mount Everest - geography.

  endangered or killed when their tents collapsed or were ripped to shreds by the gales. Hypothermia, the dramatic loss of body heat, is also a major and debilitatingproblem in this region of high winds and low temperatures. Another hazard facing Everest climbers is the famous Khumbu icefall, which is located not far above Base Camp and is caused by the rapid movement of the Khumbuglacier over the steep rock underneath. The movement breaks the ice into sérac (large, pointed masses of ice) cliffs...

• Han Dynasty - History.

  However, these reforms faced serious opposition. The feudal barons formed an alliance and rebelled against Wang Mang. They were joined by members of the Liufamily, who were descended from Jingdi (Ching-ti), a former Han emperor, and a civil war followed. As the empire fell into disorder, militant secret societies formedarmed bands and attacked villages and towns. Wang Mang had believed that proper institutions would eventually bring peace to China, but in AD 23, an army led by the Liu clan brea...

• Aristotelianism, medieval

  are introduced by the interaction of Aristotle with Jewish, Christian and Islamic religious thinking. The Christianambiguities are perhaps the most familiar. Almost all of the Christian Aristotelians in the Latin West were members ofthe clergy. Most spent their professional lives teaching and writing, not the liberal arts or philosophy, but Christiantheology. It remains controversial whether or to what extent we can find an autonomous or even a textuallydistinguishable Aristotelian p...

• Ocean and Oceanography.

  of sediment. When studied in sedimentary core samples, which can represent many millions of years of deposits, they provide a detailed and continuous history of theearth’s environmental changes. The record is particularly informative for the most recent 2 million to 5 million years, during which major fluctuations in global climatehave occurred. Successive ice ages can be traced by the relative scarcity or abundance of the shells of warm-water and cold-water diatoms in various layers of asedimen...

• Ocean and Oceanography - Geography.

  of sediment. When studied in sedimentary core samples, which can represent many millions of years of deposits, they provide a detailed and continuous history of theearth’s environmental changes. The record is particularly informative for the most recent 2 million to 5 million years, during which major fluctuations in global climatehave occurred. Successive ice ages can be traced by the relative scarcity or abundance of the shells of warm-water and cold-water diatoms in various layers of asedimen...

• Asia - geography.

  the Himalayas, the world’s highest mountain system. The Pacific Ocean plate drifted westward, scraping along the Eurasian plate and slipping under its coastal edge. This created the islands of Japan, Taiwan, the Kurils, theRyūky ūs, and the Philippines. Southeast Asia lies at the intersection of the Eurasian, Pacific Ocean, and Indian Ocean plates. Over time the contact between these platescreated the mountain ranges of mainland Southeast Asia. The continued slow movement of the plates causes fr...

• Asia - history.

  the Himalayas, the world’s highest mountain system. The Pacific Ocean plate drifted westward, scraping along the Eurasian plate and slipping under its coastal edge. This created the islands of Japan, Taiwan, the Kurils, theRyūky ūs, and the Philippines. Southeast Asia lies at the intersection of the Eurasian, Pacific Ocean, and Indian Ocean plates. Over time the contact between these platescreated the mountain ranges of mainland Southeast Asia. The continued slow movement of the plates causes fr...

• Respiratory System.

  rapidly, or laughs while swallowing, the swallowing reflex may not work, and food or fluid can enter the larynx. Food, fluid, or other substances in the larynx initiate acough reflex as the body attempts to clear the larynx of the obstruction. If the cough reflex does not work, a person can choke, a life-threatening situation. TheHeimlich maneuver is a technique used to clear a blocked larynx ( see First Aid). A surgical procedure called a tracheotomy is used to bypass the larynx and get air to...