241 résultats pour "lights"

• Easter.

  Many Easter traditions originated long before the beginning of the Christian era. Like Christmas, which is related to pre-Christian winter festivals, Easter is connected inmany ways with early pagan rituals that accompanied the arrival of spring. Easter is also associated with the Jewish festival of Passover. A Easter Eggs The Easter egg is associated with beliefs of particularly ancient origin. The egg was an important symbol in the mythologies of many early civilizations, including those ofIn...

• Electricity I INTRODUCTION Electricity, one of the basic forms of energy.

  electrons in the neutral object are attracted to the positive object. Some of these electrons flow to the side of the neutral object that is nearest to the positive object.This side of the neutral object accumulates electrons and becomes negatively charged. Because electrons leave the far side of the neutral object while its protonsremain stationary, that side becomes positively charged. Since the negatively charged side of the neutral object is closest to the positive object, the attraction bet...

• From The Hunchback of Notre Dame - anthology.

  If then we were to attempt to penetrate through this thick and obdurate bark to the soul of Quasimodo; if we could sound the depths of this bungling piece oforganization; if we were enabled to hold a torch behind these untransparent organs, to explore the gloomy interior of this opaque being, to illumine its obscure cornersand its unmeaning cul-de-sacs, and to throw all at once a brilliant light upon the spirit enchained at the bottom of this den; we should doubtless find the wretch in some mi...

• Pittsburgh - geography.

  College of Allegheny County (1966), with branches in the city and suburbs. Pittsburgh has many outstanding cultural institutions. The Oakland district is where Carnegie Mellon University and the University of Pittsburgh are located. The CarnegieMuseums of Pittsburgh include The Carnegie Museum of Art (including the Scaife Galleries), which holds a distinguished motion-picture and video collection and a uniquestudy of architecture; the Carnegie Museum of Natural History, which displays an extensi...

• Venus (planet) - astronomy.

  level winds circle the planet at 360 km/h (225 mph), making a complete rotation in only four days. These winds are said to super-rotate because they travel muchfaster than the rotation of the planet itself. These high-speed winds cover the planet completely, blowing toward the west at virtually every latitude from equator topole. The motions of descending probes, however, have shown that the bulk of Venus’s tremendously dense atmosphere, closer to the planet’s surface, is almoststagnant. From th...

• Diving (underwater).

  compensator (or control) device (BCD or BC), which the diver wears as a vest. By adding air to the BCD, the diver becomes more buoyant and rises. By releasing air,the diver becomes less buoyant and sinks. With minor adjustments of air, the diver can achieve neutral buoyancy. A third hose attaches to pressure gauges that diversuse to monitor how much air remains in the tank. A fourth hose attaches to a backup breathing device called an alternate air source, or octopus. Divers also wear a belt w...

• Christmas.

  The new custom of Christmas gift giving allowed the marketplace to exert an unprecedented influence on holiday celebrations. Commercial innovations such asdepartment stores and mass advertising further expanded the custom of exchanging Christmas gifts. Seasonal retail sales helped fuel the economy, causing merchantsand advertisers to become some of the season’s most ardent promoters. Many holiday celebrants regretted these changes, however, and began voicing the nowcommon lament that Christmas h...

• Solar System - astronomy.

  dwarf planets according to the IAU because they have rounded shapes from their own gravity but have not cleared their neighborhoods in space of other objects—bothorbit through the Kuiper Belt, a region beyond Neptune containing thousands of small icy bodies. Pluto and Eris are composed of layers of ice around a rocky core.Ceres qualifies as a dwarf planet because it is spherical but is found in the asteroid belt, a zone between the orbits of Mars and Jupiter that contains thousands of smallrocky...

• Coral Reef.

  sensitive to particles of mud or sediment settling on them, which means that corals rarely grow close to rivers or other sources of sediment. In the sea, light is filteredout by depth, so reef-building corals can only grow in relatively shallow water. Even in the clearest oceans few reef-building corals grow below a depth of 80 to 100 m(260 to 328 ft). Although corals need nutrients, they cannot thrive in areas where there are large amounts of nutrients. Typically, microscopic organisms in the p...

• Tree - biology.

  The major parts of a tree are its roots, trunk, leaves, flowers, and seeds. These components play vital roles in a tree’s growth, development, and reproduction. A Roots Trees are held in place by anchoring organs called roots. In addition to anchoring the tree, roots also absorb water and minerals through tiny structures called roothairs. From the roots the water and mineral nutrients are carried upward through the wood cells to the leaves. Although the internal structure of most kinds of roots...

• 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...

• Tiger - biology.

  have a simple digestive system designed to process meat so that the nutrients can be readily absorbed into the bloodstream. With the exception of white tigers, which have blue eyes, all tigers have yellow eyes. Tigers mainly use vision to find prey. Although tigers see about as well as humansduring the day, their large eye openings gather more light than do human eyes, making tiger night vision far superior to that of humans. In addition, a special structurein the tiger’s eye, called the tapetu...

• Bear - biology.

  programs sponsored by zoos or other breeding centers have attempted to breed giant pandas in captivity, although most of these programs have proved unsuccessful.Among the difficulties faced by captive breeders has been the problem of encouraging a female giant panda to mate with a selected male during the two to three daysof the year when she is most fertile, a period known as estrus. B Spectacled Bear Creamy-white rings surrounding the eyes give the spectacled bear its name. Its shaggy coat of...

• Beetle - biology.

  cut, or crush prey. Beetles that consume nectar from flowers use tubelike mouthparts to suck up nectar like a primitive straw. C Thorax The thorax, the body region behind the head, consists of three segments that provide attachments for the legs and wings. Each segment of the thorax carries a pair oflegs. The middle segment also bears the stiff wing sheaths called elytra, and the hind segment holds the membranous hind wings. D Legs Beetles have six jointed legs, each leg with five parts. The f...

• North Carolina - geography.

  The drainage divide in North Carolina follows the Blue Ridge range on the eastern margin of the mountain region. This is called the “Eastern Continental Divide.” West ofthis divide, rivers drain into the Mississippi River through the Tennessee River and other tributaries of the Ohio River. The French Broad, the largest, and the LittleTennessee flow into the Tennessee River. The New River flows into the Kanawha River of West Virginia which in turn flows into the Ohio River. Most of the state’s ri...

• North Carolina - USA History.

  The drainage divide in North Carolina follows the Blue Ridge range on the eastern margin of the mountain region. This is called the “Eastern Continental Divide.” West ofthis divide, rivers drain into the Mississippi River through the Tennessee River and other tributaries of the Ohio River. The French Broad, the largest, and the LittleTennessee flow into the Tennessee River. The New River flows into the Kanawha River of West Virginia which in turn flows into the Ohio River. Most of the state’s ri...

• Illinois - geography.

  the state before joining the Mississippi River at Grafton. The Illinois has been deepened and straightened and forms part of the Illinois Waterway. The watershed between rivers that flow into the Mississippi river system and rivers that flow into the Great Lakes is low and in many places is not easily discernible. Inwhat is now the Chicago area, explorers had little difficulty portaging, or carrying, their canoes over the low watershed between the Des Plaines River, which flows intothe Illinois,...

• Illinois - USA History.

  the state before joining the Mississippi River at Grafton. The Illinois has been deepened and straightened and forms part of the Illinois Waterway. The watershed between rivers that flow into the Mississippi river system and rivers that flow into the Great Lakes is low and in many places is not easily discernible. Inwhat is now the Chicago area, explorers had little difficulty portaging, or carrying, their canoes over the low watershed between the Des Plaines River, which flows intothe Illinois,...

• Baroque Art and ArchitectureIINTRODUCTIONGerman Baroque ArchitectureThe baroque style of architecture flourished in Germany in the 18th century.

  C Early baroque styles Conversion of Saint PaulItalian baroque painter Caravaggio painted scenes of realism and drama, often selecting lofty, religious themes anddepicting them with lower-class characters and settings with dramatic spotlighting. With its unidealized characters andfocus on the horse’s body, his Conversion of Saint Paul seems to record a stable accident, not a miraculous conversion byGod. This work was painted in 1601 and is in the Cerasi Chapel, Santa Maria del Popolo, Rome, It...

• Race - biology.

  distributed as a cline, generally varying along a north-south line. Skin color is lightest in northern Europeans, especially in those who live around the Baltic Sea, andbecomes gradually darker as one moves toward southern Europe, the Mediterranean, the Middle East, and into northern Africa and northern subtropical Africa. Skin isdarkest in people who live in the tropical regions of Africa. The lack of clear-cut discontinuities makes any racial boundary based on skin color totally arbitrary. Sim...

• Hydrogen - chemistry.

  Hydrogen gas does not usually react with other chemicals at room temperature. That is, it does not split into two hydrogen atoms to combine with other chemicals. Thebond between the hydrogen atoms is very strong and can only be broken with a large amount of energy. However, when heated with a flame or a spark, hydrogen gaswill react violently with oxygen in the air to produce water in the following reaction: 2H2 + O 2 → 2H 2O This chemical equation shows that two hydrogen molecules (H 2) and o...

• Eclipse - astronomy.

  bending of light rays passing close to the sun because of the sun’s gravitational field ( see Relativity). The great brilliance of the solar disk and the sun-induced brightening of the earth’s atmosphere make observations of the corona and nearby stars impossible except during a solar eclipse. The coronagraph, a photographictelescope, permits direct observation of the edge of the solar disk at all times. Today, scientific solar eclipse observations are extremely valuable, particularly when thepa...

• X-Ray Astronomy - astronomy.

  Some neutron stars have weaker magnetic fields that allow incoming material to settle onto the entire surface of the neutron star. Eventually, so much material buildsup that the surface layer becomes dense enough to set off a vast thermonuclear explosion, called an outburst. The explosion heats gas to produce X rays. Such aneutron star—called an X-ray burster—can increase its X-ray production by a million times during an outburst. The X-ray glow fades over time, and the binary systementers a lon...

• Plant - biology.

  B1 Vacuoles Vacuoles are membrane-bound cavities filled with cell sap, which is made up mostly of water containing various dissolved sugars, salts, and other chemicals. B2 Plastids Plastids are types of organelles, structures that carry out specialized functions in the cell. Three kinds of plastids are important here. Chloroplasts contain chlorophyllsand carotenoid pigments; they are the site of photosynthesis, the process in which light energy from the sun is fixed as chemical energy in the b...

• Radio.

  signal, such as a musical note. This form of modulation, AM, is used in many radiotelephony services including standard radiobroadcasts. AM is also employed for carriercurrent telephony, in which the modulated carrier is transmitted by wire, and in the transmission of still pictures by wire or radio. See Broadcasting, Radio and Television. In FM the frequency of the carrier wave is varied within a fixed range at a rate corresponding to the frequency of a sound signal. This form of modulation, p...

• Gemstones.

  In the late 1960s a method was developed for “growing” diamonds by heating a diamond particle to a high temperature and subjecting it to methane gas. The gasdecomposes into carbon atoms, which adhere to the diamond crystal. The crystal structure of the enlarged diamond is identical to that of a natural diamond. Diamondsof about 1 carat (200 mg or 0.007 oz) have been produced by this method, but their cost is still considerably higher than that of naturally occurring diamonds. Sapphires are made...

• Greenhouse Effect.

  addition, humans cut down huge tracts of trees for lumber or to clear land for farming or building. This process, known as deforestation, can both release the carbonstored in trees and significantly reduce the number of trees available to absorb carbon dioxide. As a result of these human activities, carbon dioxide in the atmosphere is accumulating faster than Earth’s natural processes can absorb the gas. By analyzing airbubbles trapped in glacier ice that is many centuries old, scientists have d...

• Manhattan Project - U.

  other possible uses of nuclear energy, such as using uranium to operate large power plants or, perhaps, as power sources for ships or submarines. Then Nazi Germanyinvaded Poland on September 1, 1939, and Europe plunged into war. The scientists realized that any plans to build large-scale nuclear power plants would have to waituntil the war was over. Two weeks after the invasion of Poland, Hitler made a radio speech in which he threatened Britain with “a weapon against which there is no defense.”...

• Mars (planet) - astronomy.

  The Martian core is probably much like Earth’s, consisting mostly of iron, with a small amount of nickel. If other light elements, particularly sulfur, exist there as well, thecore may be larger than presently thought. From studying Earth’s magnetic field and core, scientists theorize that the motions of the liquid rock in Earth’s core generateits magnetic field. Mars does not have a significant magnetic field, so scientists believe that Mars’s core is probably solid. However, spacecraft data in...

• Claude Monet.

  Gardens were a recurrent theme for Monet in the 1870s, and paintings of his own garden dominate his later work. In 1890 he purchased a house in Giverny that hehad been renting for seven years. He began to develop its gardens, introducing an ornamental lily pond and a Japanese-style bridge. These and other features of hisidyllic estate were the subject of a steady output of large decorative paintings. He generally began by painting outdoors, but would then return to his studio to work andrework h...

• Rembrandt I INTRODUCTION Rembrandt (1606-1669), Dutch baroque artist, who ranks as one of the greatest painters in the history of Western art.

  of his collection of art and antiquities, taken before an auction to pay his debts, showed the breadth of Rembrandt's interests: ancient sculpture, Flemish and ItalianRenaissance paintings, Far Eastern art, contemporary Dutch works, weapons, and armor. Unfortunately, the results of the auction—including the sale of hishouse—were disappointing. These problems in no way affected Rembrandt's work; if anything, his artistry increased. Some of the great paintings from this period are The Jewish Brid...

• Igneous Rock.

  As a magma cools, the first crystals to form will be of minerals that become solid at relatively high temperatures (usually olivine and a type of feldspar known asanorthite). The composition of these early-formed mineral crystals will be different from the initial composition of the magma. Consequently, as these growing crystalstake certain elements out of the magma in certain proportions, the composition of the remaining liquid changes. This process is known as magmatic differentiation.Sometime...

• Butterflies and Moths - biology.

  The smallest butterflies are certain blues that have wingspans of a mere 0.7 cm (0.25 in). The largest are the female giant birdwings of Papua New Guinea, whichmeasure up to 30 cm (12 in) across. Moths range in size from tiny Microlepidoptera, several groups of small moths with wings no more than 0.16 cm (0.06 in) across, togiant silk moths, such as the atlas moth, which may exceed 30 cm (12 in) in wingspan. IV REPRODUCTION AND LIFE CYCLE Butterflies locate potential mates by sight, identifyin...

• Native American Architecture.

  B Relationship to the Universe and Nature A more profound difference between European American and Native American perceptions lay in how human beings saw themselves in relationship to the universe andin what they believed their responsibilities were to the natural world and to each other. Most European Americans saw themselves as separate from creation andadversaries of nature, ever struggling to conquer and subdue nature and force it to yield to their will. Native Americans saw themselves as...

• Boxing: Olympic Gold Medalists.

  (Since 1952 up to 57 kg/126 lb)1904 Oliver Kirk United States 1908 Richard Gunn United Kingdom 1920 Paul Fritsch France 1924 John Fields United States 1928 Lambertus van Klaveren The Netherlands 1932 Carmelo Robledo Argentina 1936 Oscar Casanovas Argentina 1948 Ernesto Formenti Italy 1952 Ján Zachara Czechoslovakia 1956 Vladimir Safronov USSR 1960 Francesco Musso Italy 1964 Stanislav Stepashkin USSR 1968 Antonio Roldan Mexico 1972 Boris Kuznetsov USSR 1976 Angel Herrera Cuba 1980 Rudi Fink East...

• Boxing: Olympic Gold Medalists.

  (Since 1952 up to 57 kg/126 lb)1904 Oliver Kirk United States 1908 Richard Gunn United Kingdom 1920 Paul Fritsch France 1924 John Fields United States 1928 Lambertus van Klaveren The Netherlands 1932 Carmelo Robledo Argentina 1936 Oscar Casanovas Argentina 1948 Ernesto Formenti Italy 1952 Ján Zachara Czechoslovakia 1956 Vladimir Safronov USSR 1960 Francesco Musso Italy 1964 Stanislav Stepashkin USSR 1968 Antonio Roldan Mexico 1972 Boris Kuznetsov USSR 1976 Angel Herrera Cuba 1980 Rudi Fink East...

• Helium - chemistry.

  the bends. This synthetic atmosphere is also used in medicine to relieve sufferers of respiratory difficulties because helium moves more easily than nitrogen throughconstricted respiratory passages. In surgery, beams of ionized helium from synchrocyclotron sources are proving useful in treating eye tumors, by stabilizing or evenshrinking the tumors. Such beams are also used to shrink blood-vessel malformations in the brains of patients. Helium is used in inert-gas arc welding for light metals, s...

• Édouard Manet I INTRODUCTION Manet: Tradition and Innovation French impressionist painter Édouard Manet shocked art audiences in Paris with Le déjeuner sur l'herbe (The Luncheon on the Grass; 1863, Musée d'Orsay, Paris), which depicts a nude woman at a woodland picnic.

  Le Déjeuner sur l’herbeLe Déjeuner sur l’herbe (Luncheon on the Grass) by Édouard Manet was painted in 1863. When it was first displayed, therough brushwork and undefined areas of color were as distressing to the public as the nude woman who was neither aclassical goddess nor a symbol in an allegory. Manet claimed that the real subject of the painting was light, and it was thatphilosophy that gave birth to impressionism.Bridgeman Art Library, London/New York After his father died in 1862, Manet...

• From Bulfinch's Mythology: Proserpine - anthology.

  the furrow, the seed failed to come up; there was too much sun, there was too much rain; the birds stole the seeds—thistles and brambles were the only growth.Seeing this, the fountain Arethusa interceded for the land. 'Goddess,' said she, 'blame not the land; it opened unwillingly to yield a passage to your daughter. I can tellyou of her fate, for I have seen her. This is not my native country; I came hither from Elis. I was a woodland nymph, and delighted in the chase. They praised mybeauty, bu...

• Flower - biology.

  insects. The sepals unfurl as the flower opens and often resemble small green leaves at the flower’s base. In some flowers, the sepals are colorful and work with thepetals to attract pollinators. E Variations in Structure Like virtually all forms in nature, flowers display many variations in their structure. Most flowers have all four whorls—pistil, stamens, petals, and sepals. Botanists callthese complete flowers. But some flowers are incomplete, meaning they lack one or more whorls. Incomplet...

• Gothic Art and Architecture I INTRODUCTION Notre Dame Cathedral, Paris Notre Dame Cathedral, in Paris, was begun in 1163 and completed for the most part in 1250.

  and by external arches, called flying buttresses. Consequently, the thick walls of Romanesque architecture could be largely replaced by thinner walls with glass windows,and the interiors could reach unprecedented heights. A revolution in building techniques thus occurred. With the Gothic vault, a ground plan could take on a variety of shapes. The general plan of the cathedrals, however, consisting of a long three-aisled nave interceptedby a transept and followed by a shorter choir and sanctuary,...

• Excerpt from A Christmas Carol - anthology.

  External heat and cold had little influence on Scrooge. No warmth could warm, no wintry weather chill him. No wind that blew was bitterer than he, no falling snowwas more intent upon its purpose, no pelting rain less open to entreaty. Foul weather didn’t know where to have him. The heaviest rain, and snow, and hail, and sleet,could boast of the advantage over him in only one respect. They often “came down” handsomely and Scrooge never did. Nobody ever stopped him in the street to say, with g...

• 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...

• Maryland - geography.

  Maryland has no large natural lakes. The largest body of water is a reservoir, Deep Creek Lake, which has a surface area of only 18 sq km (7 sq mi). It lies on theAllegheny Plateau, behind a dam on a tributary of the Youghiogheny River. C Coastline The deeply indented shoreline has a length of 5,134 km (3,190 mi), of which only 50 km (31 miles) fronts on the Atlantic Ocean. The most significant coastal feature isChesapeake Bay. In the bay are many islands and Kent Island is the largest. The sta...

• Maryland - USA History.

  Maryland has no large natural lakes. The largest body of water is a reservoir, Deep Creek Lake, which has a surface area of only 18 sq km (7 sq mi). It lies on theAllegheny Plateau, behind a dam on a tributary of the Youghiogheny River. C Coastline The deeply indented shoreline has a length of 5,134 km (3,190 mi), of which only 50 km (31 miles) fronts on the Atlantic Ocean. The most significant coastal feature isChesapeake Bay. In the bay are many islands and Kent Island is the largest. The sta...

• Bible.

  collection of many different books. The Old Testament is by no means a unified book in terms of authorship, date of composition, or literary type; it is instead a veritablelibrary. Generally speaking, the books of the Old Testament and their component parts may be identified as narratives, poetic works, prophetic works, law, or apocalypses.Most of these are broad categories that include various distinct types or genres of literature and oral tradition. None of these categories is limited to the...

• Peter Paul Rubens I INTRODUCTION Thetis Dipping Achilles in the Styx The sea nymph Thetis is seen dipping her son Achilles in the River Styx to make him immortal.

  Rubens, Equestrian Portrait of the Duke of LermaIn 1603 Flemish painter Peter Paul Rubens traveled to Spain as part of a diplomatic mission. While there, he received acommission for this portrait of the Duke of Lerma, the powerful prime minister of Spanish king Philip III. The painting nowhangs in the Prado Museum in Madrid, Spain.The Prado Museum, Madrid/Archivo Fotografico Oronoz Shortly thereafter, following the example of many northern European artists of the period, Rubens traveled to Italy...

• Biblical Archaeology.

  religion, among them the storm deity Baal (title of Hadad) mentioned frequently in the Old Testament. Moreover, the poetry of Ugarit has strong affinities with that ofthe Bible. They share much in the way of vocabulary, structure, and the use of figures of speech and other literary devices. In 1945, at ancient Naj‘Ḩamm ād ī in Upper Egypt, some 50 Gnostic writings in Coptic were discovered. They could be dated to the 4th century AD, but investigation of their character and content showed that t...

• THAT LONE.

  MY FEELINGS   They areannouncing flightsoverthespeakers. Wearenot listening. Theydonot matter tous, because weare not going anywhere. I miss youalready, Oskar.Imissed youeven when Iwas with you.That's beenmyproblem. Imiss what Ialready have, and Isurround myselfwiththings thataremissing. Every timeIput inanew page, Ilook atyour grandfather. Iam sorelieved tosee hisface. Itmakes mefeel safe. His shoulders arepinched. Hisspine iscurved. InDresden hewas agiant. I'mglad thathishands arestill rough....

• Paul Cézanne I INTRODUCTION Peaches and Pears Peaches and Pears (1888) by Paul Cézanne displays a sense of unity and continuity typical of the artist's many still-life paintings.

  the most transient natural effects as well as their own passing emotional states as the artists stood before nature. Under Pissarro's tutelage, and within a very shorttime during 1872-1873, Cézanne shifted from dark tones to bright hues and began to concentrate on scenes of farmland and rural villages. IV RETURN TO AIX-EN-PROVENCE Mont Sainte-Victoire by CézanneFrench artist Paul Cézanne painted Mont Sainte-Victoire, a mountain near his home in Provence in southern France, onmany occasions. Ov...