806 résultats pour "mucha"

• Air Pollution.

  Several pollutants attack the ozone layer. Chief among them is the class of chemicals known as chlorofluorocarbons (CFCs), formerly used as refrigerants (notably in airconditioners), as agents in several manufacturing processes, and as propellants in spray cans. CFC molecules are virtually indestructible until they reach thestratosphere. Here, intense ultraviolet radiation breaks the CFC molecules apart, releasing the chlorine atoms they contain. These chlorine atoms begin reacting withozone, br...

• Crusades.

  modern Lebanon; the Principality of Antioch, in modern Syria; and the County of Edessa, in modern northern Syria and southern Turkey. IV CRUSADES OF THE 12TH CENTURY The Crusades of the 12th century, through the end of the Third Crusade in 1192, illustrate the tensions and problems that plagued the enterprise as a whole. For thelords of Outremer a compromise with the residents and Muslim powers made sense; they could not live in constant warfare. And yet as European transplants theydepended on...

• Crusades .

  modern Lebanon; the Principality of Antioch, in modern Syria; and the County of Edessa, in modern northern Syria and southern Turkey. IV CRUSADES OF THE 12TH CENTURY The Crusades of the 12th century, through the end of the Third Crusade in 1192, illustrate the tensions and problems that plagued the enterprise as a whole. For thelords of Outremer a compromise with the residents and Muslim powers made sense; they could not live in constant warfare. And yet as European transplants theydepended on...

• Conservación - ciencias de la naturaleza.

  pequeños que no pueden serrarse en tablones, y los llamados árboles inferiores. Véase Bosque; Incendios forestales; Silvicultura. 5 CONSERVACIÓN DE LOS PASTIZALES Uno de los principios de la conservación de las tierras de pastos es usar sólo parte (más o menos la mitad) de la producción anual de plantas forrajeras para favorecer elcrecimiento y reproducción de plantas sanas. Además, a cada prado se le asigna el número de animales que pueden sustentarse adecuadamente en él y a éstos sólo se l...

• Gato - ciencias de la naturaleza.

  2.2 Sentidos La vista del gato está excepcionalmente adaptada a la caza, especialmente de noche. Tiene una excelente visión nocturna, visión periférica muy amplia y una visiónbinocular que le permite calcular distancias con exactitud. La visión diurna del gato no es tan buena como la de los humanos; los gatos ven el movimiento con mucha másfacilidad que el detalle y se cree que sólo pueden ver una gama limitada de colores. El gato tiene un oído extremadamente sensible. Puede oír una amplia esca...

• Hippopotamus - biology.

  hippo backs up to its droppings and uses its tail as a paddle, flicking the dung through the air. This creates a pile that can become several meters wide over time. Male river hippos start to establish territories when they are in their early 20s, and they may eventually control more than 250 m (820 ft) of the water's edge.Subordinate males come and go freely, but a rival male will spark a confrontation if it tries to intrude. The territory owner and intruder face each other open-mouthedand, if...

• The Summer Games of 1992 - sport.

  In the most ambitious undertaking of all, a stretch of rundown warehouses and abandoned factories beside the long-neglected Mediterranean waterfront wastransformed into a sparkling new district of apartments, shopping areas, and palmetto-lined promenades. During the games, the area served as the Olympic athletes'village, where, for the first time at any games, organizers offered accommodations to competitors and their coaches free of charge. After the games the apartmentswere to be sold to help...

• 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...

• Poverty.

  economic and demographic trends, and (7) welfare incentives. A Overpopulation Overpopulation, the situation of having large numbers of people with too few resources and too little space, is closely associated with poverty. It can result from highpopulation density (the ratio of people to land area, usually expressed as numbers of persons per square kilometer or square mile) or from low amounts of resources, or from both. Excessively high population densities put stress on available resources....

• American Westward Movement - U.

  British expansion. However, Native Americans of the Great Lakes and Ohio Valley lashed out against the English in an attempt to preserve their independence, theirland, and their way of life. With the Ottawa chief Pontiac as their most visible leader, the tribes waged a bloody and costly war. As a result, the British governmentdecided to keep the white settlers apart from the Native Americans. It issued the Royal Proclamation of 1763, banning all white settlement beyond the Appalachians andstatin...

• Europe .

  D Vegetation Although much of Europe, particularly the west, was originally covered by forest, the vegetation has been transformed by human habitation and the clearing of land.Only in the most northerly mountains and in parts of north central European Russia has the forest cover been relatively unaffected by human activity. On the otherhand, a considerable amount of Europe is covered by woodland that has been planted or has reoccupied cleared lands. The largest vegetation zone in Europe, cuttin...

• Europe - Geography.

  D Vegetation Although much of Europe, particularly the west, was originally covered by forest, the vegetation has been transformed by human habitation and the clearing of land.Only in the most northerly mountains and in parts of north central European Russia has the forest cover been relatively unaffected by human activity. On the otherhand, a considerable amount of Europe is covered by woodland that has been planted or has reoccupied cleared lands. The largest vegetation zone in Europe, cuttin...

• Nova - astronomy.

  When first discovered, the spectrum of a nova shows that the expanding layers of gas that cause the brightening have temperatures of 40,000° to 50,000° C (70,000°to 90,000° F)—about eight times as hot as the surface of the Sun. By the time a nova reaches maximum brightness, the temperature of the material has fallen to about10,000° C (about 20,000° F), or lower. Just after maximum brightness, the escaping cloud of gas cools and expands enough to become transparent. This transparency allows astro...

• Spain - country.

  B Natural Resources Spain has a number of mineral resources. The largest known deposits are of iron ore, zinc, and lead. Spain also produces significant quantities of copper and mercury.These deposits are mined mainly in Huelva province in southwestern Spain, around Cartagena on the Mediterranean, and at various points along the Bay of Biscay inthe north. Additionally, uranium is mined in the region of Extremadura, near the Portuguese frontier, where pyrites, fluorspar, gypsum, tungsten, and po...

• France - country.

  In both the Paris and Aquitaine basins, fertile soils derived from limestone and wind-deposited dust, called loess, have supported prosperous agriculture since ancienttimes. Other lowlands in France are scattered and relatively small. They include the Alsace Plain in the east, bordering Germany, the valley of the Rhône River in thesoutheast, and the Languedoc Plain along the Mediterranean coast. A2 Uplands France contains several regions of uplands, the worn down remains of ancient mountain sys...

• Alaska - geography.

  depression surrounded by highlands and have the coldest winter and hottest summer temperatures in Alaska. Once the Kuskokwim River passes through theKuskokwim Mountains, it forms the southern edge of a vast lake-studded alluvial plain bounded on the north by the Yukon River. This water-logged lowland is a majorsummer nesting area for birds. Fairbanks is the major city in this region, while Fort Yukon is the major community in the Yukon Flats and Bethel the largest settlementon the Lower Kuskokwi...

• Alaska - USA History.

  depression surrounded by highlands and have the coldest winter and hottest summer temperatures in Alaska. Once the Kuskokwim River passes through theKuskokwim Mountains, it forms the southern edge of a vast lake-studded alluvial plain bounded on the north by the Yukon River. This water-logged lowland is a majorsummer nesting area for birds. Fairbanks is the major city in this region, while Fort Yukon is the major community in the Yukon Flats and Bethel the largest settlementon the Lower Kuskokwi...

• Asia - Geography.

  Borneo, the world’s third largest island after Greenland and New Guinea. To the southeast is the Timor Sea separating the Asian island of Timor from the Australiancontinent. The Indian subcontinent is flanked by the Bay of Bengal on the east and the Arabian Sea on the west. The island of Sri Lanka and the much smaller Maldives andNicobar Islands trail away to the south. The Arabian Sea’s Gulf of Aden, the Red Sea, the Mediterranean Sea, and the Black Sea form an arc along the western rim of Asia...

• Asia - History.

  Borneo, the world’s third largest island after Greenland and New Guinea. To the southeast is the Timor Sea separating the Asian island of Timor from the Australiancontinent. The Indian subcontinent is flanked by the Bay of Bengal on the east and the Arabian Sea on the west. The island of Sri Lanka and the much smaller Maldives andNicobar Islands trail away to the south. The Arabian Sea’s Gulf of Aden, the Red Sea, the Mediterranean Sea, and the Black Sea form an arc along the western rim of Asia...

• 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...

• Guatemala - country.

  C Climate The climate of Guatemala varies according to elevation, from hot coastal plains to cold mountain heights. Most of the population lives between 900 and 2,400 m (3,000and 8,000 ft) above sea level, where there are warm days and cool nights with average annual temperatures of 20°C (68°F). The coastal regions are hot and humid,with average annual temperatures of 28°C (83°F). A rainy season, from May through October, is sometimes called “winter” because it brings cloudy afternoons andlower...

• Idaho - geography.

  Idaho-Montana state line in the southern part of the Bitterroot Mountains. Consequently, nearly all the rivers in the state drain toward the Pacific. Most of Idaho lieswithin the drainage basin of the Columbia River system. The Snake River, which is the chief river in southern and central Idaho, follows a crescent-shaped course forabout 790 km (about 490 mi) across southern Idaho. It then swings northward along the Idaho state line and joins the Columbia River in Washington. Major tributariesof...

• Idaho - USA History.

  Idaho-Montana state line in the southern part of the Bitterroot Mountains. Consequently, nearly all the rivers in the state drain toward the Pacific. Most of Idaho lieswithin the drainage basin of the Columbia River system. The Snake River, which is the chief river in southern and central Idaho, follows a crescent-shaped course forabout 790 km (about 490 mi) across southern Idaho. It then swings northward along the Idaho state line and joins the Columbia River in Washington. Major tributariesof...

• Ontario - Geography.

  governed Ontario’s initial settlement and development. The province’s most important river is the St. Lawrence. Its route was much improved and enlarged by dredgingand canal building in the mid-20th century. This enabled large ocean-going vessels to reach Great Lake ports ( see St. Lawrence Seaway). The Ottawa River was an important early route to the interior for fur traders and timber merchants. The Niagara River, because of its falls, is a great center of hydroelectric power as well as aninte...

• Ontario - Canadian History.

  governed Ontario’s initial settlement and development. The province’s most important river is the St. Lawrence. Its route was much improved and enlarged by dredgingand canal building in the mid-20th century. This enabled large ocean-going vessels to reach Great Lake ports ( see St. Lawrence Seaway). The Ottawa River was an important early route to the interior for fur traders and timber merchants. The Niagara River, because of its falls, is a great center of hydroelectric power as well as aninte...

• Federal Republic of Germany - country.

  B Rivers and Lakes Rivers have played a major role in Germany’s economic development. The Rhine River flows in a northwesterly direction from Switzerland through much of westernGermany and The Netherlands into the North Sea. It is a major European waterway and a pillar of commerce and trade. Its primary German tributaries include theMain, Mosel, Neckar, and Ruhr rivers. The Oder (Odra) River, along the border between Poland and Germany, runs northward and empties into the Baltic; it provides an...

• Nevada - geography.

  The Truckee, Carson, and Walker rivers flow out of the Sierra Nevada, thread their way around several of the desert ranges, and also end in closed basins. The Walkerflows into Walker Lake, the Carson into Lahontan Reservoir. The major part of the Truckee’s flow is now diverted to Lahontan Reservoir, although as required by lawsome of it empties into Pyramid Lake. Because these three streams flow constantly, the lakes into which they empty never dry up. Winnemucca Lake formerly receivedoverflow w...

• Nevada - USA History.

  The Truckee, Carson, and Walker rivers flow out of the Sierra Nevada, thread their way around several of the desert ranges, and also end in closed basins. The Walkerflows into Walker Lake, the Carson into Lahontan Reservoir. The major part of the Truckee’s flow is now diverted to Lahontan Reservoir, although as required by lawsome of it empties into Pyramid Lake. Because these three streams flow constantly, the lakes into which they empty never dry up. Winnemucca Lake formerly receivedoverflow w...

• 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...

• United Kingdom - country.

  B Natural Regions and Topography The island of Great Britain can be divided into two major natural regions—the highland zone and the lowland zone. The highland zone is an area of high hills andmountains in the north and west. The lowland zone in the south and east consists mostly of rolling plains. The zones are divided by an imaginary line running throughEngland from the River Exe on the southwest coast to the mouth of the River Tees on the northeast coast. The lowland zone has a milder climat...

• New Brunswick - Geography.

  Grand Lake, the largest lake in New Brunswick, is in the lowlands, east of Fredericton. Most other lakes are located in the northern and southwestern parts of NewBrunswick. D Climate New Brunswick has a continental climate that is moderated by maritime influences in the coastal areas. As a result, coastal regions are slightly warmer in the winter andslightly cooler in the summer than are interior regions. Annual temperature variations are large, with the January mean usually at least 25 to 28°C...

• New Brunswick - Canadian History.

  Grand Lake, the largest lake in New Brunswick, is in the lowlands, east of Fredericton. Most other lakes are located in the northern and southwestern parts of NewBrunswick. D Climate New Brunswick has a continental climate that is moderated by maritime influences in the coastal areas. As a result, coastal regions are slightly warmer in the winter andslightly cooler in the summer than are interior regions. Annual temperature variations are large, with the January mean usually at least 25 to 28°C...

• Rhode Island - geography.

  C (73° F). Along the northern state line, the January mean temperature is about 1° C (about 2° F) colder than in Warwick in January. Along the ocean coast, theJanuary mean temperature is -1° C (30° F). Warm season temperatures are also influenced by the ocean and bay, so temperatures are usually cooler along the coastthan in the interior. The difference tends to be greatest in spring and early summer. Winter temperatures in Rhode Island are usually above -7° C (20° F), buttemperatures colder by...

• Rhode Island - USA History.

  C (73° F). Along the northern state line, the January mean temperature is about 1° C (about 2° F) colder than in Warwick in January. Along the ocean coast, theJanuary mean temperature is -1° C (30° F). Warm season temperatures are also influenced by the ocean and bay, so temperatures are usually cooler along the coastthan in the interior. The difference tends to be greatest in spring and early summer. Winter temperatures in Rhode Island are usually above -7° C (20° F), buttemperatures colder by...

• Ancient Greece.

  The first culture of Aegean civilization on the Greek mainland is named Mycenaean for the palace at Mycenae on the Pelopónnisos. Scholars call the Mycenaeans the“earliest Greeks” because they are the first people known to have spoken Greek. Mycenaean culture developed later than Minoan. The ancestors of the Mycenaean people wandered onto the mainland from the north and the east from about 4000 to2000 BC, mixing with the people already there, and by about 1400 BC the Mycenaeans had become very...

• Ancient Greece .

  The first culture of Aegean civilization on the Greek mainland is named Mycenaean for the palace at Mycenae on the Pelopónnisos. Scholars call the Mycenaeans the“earliest Greeks” because they are the first people known to have spoken Greek. Mycenaean culture developed later than Minoan. The ancestors of the Mycenaean people wandered onto the mainland from the north and the east from about 4000 to2000 BC, mixing with the people already there, and by about 1400 BC the Mycenaeans had become very...

• Ancient Greece - USA History.

  The first culture of Aegean civilization on the Greek mainland is named Mycenaean for the palace at Mycenae on the Pelopónnisos. Scholars call the Mycenaeans the“earliest Greeks” because they are the first people known to have spoken Greek. Mycenaean culture developed later than Minoan. The ancestors of the Mycenaean people wandered onto the mainland from the north and the east from about 4000 to2000 BC, mixing with the people already there, and by about 1400 BC the Mycenaeans had become very...

• Afghanistan - country.

  D Climate Most of Afghanistan has a subarctic mountain climate with dry and cold winters, except for the lowlands, which have arid and semiarid climates. In the mountains and afew of the valleys bordering Pakistan, a fringe effect of the Indian monsoon, coming usually from the southeast, brings moist maritime tropical air in summer.Afghanistan has clearly defined seasons: Summers are hot and winters can be bitterly cold. Summer temperatures as high as 49°C (120°F) have been recorded in thenorth...

• 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...

• Excerpt from Northanger Abbey - anthology.

  “I will read you their names directly; here they are in my pocket-book. Castle of Wolfenbach, Clermont, Mysterious Warnings, Necromancer of the Black Forest, Midnight Bell, Orphan of the Rhine, and Horrid Mysteries. Those will last us some time.” “Yes; pretty well; but are they all horrid? Are you sure they are all horrid?” “Yes, quite sure; for a particular friend of mine, a Miss Andrews, a sweet girl, one of the sweetest creatures in the world, has read every one of them. I wis...

• Oregon - geography.

  B Rivers and Lakes The Columbia River forms most of the Oregon-Washington boundary, and with its tributaries this great river drains a large portion of Oregon. From the point where theColumbia first touches the state, at Wallula Gap, the river runs in a shallow gorge, deepening as it approaches the Cascades. This part of the river once had manyrapids and falls, but is now navigable by large vessels because of dams and locks that have been built along much of its length. An important tributary o...

• Oregon - USA History.

  B Rivers and Lakes The Columbia River forms most of the Oregon-Washington boundary, and with its tributaries this great river drains a large portion of Oregon. From the point where theColumbia first touches the state, at Wallula Gap, the river runs in a shallow gorge, deepening as it approaches the Cascades. This part of the river once had manyrapids and falls, but is now navigable by large vessels because of dams and locks that have been built along much of its length. An important tributary o...

• Turkey - country.

  has a general elevation of 900 to 1,500 m (3,000 to 5,000 ft) above sea level. The eastern highlands region is the most mountainous and rugged portion of Turkey; Mount Ararat (Ağrı Da ğı) is the highest peak in the country at 5,165 m (16,945ft). Many Christians and Jews believe it to be the same Mount Ararat mentioned in the Bible as the place where Noah’s ark came to rest. The eastern highlands are thesource for both the Tigris (Dicle) and Euphrates (Fir āt)—two of southwestern Asia’s principal...

• Hundred Years' War.

  knowledge of English tactics. Du Guesclin became Constable of France (head of the army) in 1370, and when he died in 1380, Clisson succeeded him. Charles also reorganized the French military, developing a full-time, professional army for the first time, and established a regular system of taxation to pay for it. Inaddition, France gained an important ally on the throne of the Spanish kingdom of Castile, Henry II, who had pledged support for Charles V. When the Caroline war began in 1369, the Eng...

• Hundred Years' War .

  knowledge of English tactics. Du Guesclin became Constable of France (head of the army) in 1370, and when he died in 1380, Clisson succeeded him. Charles also reorganized the French military, developing a full-time, professional army for the first time, and established a regular system of taxation to pay for it. Inaddition, France gained an important ally on the throne of the Spanish kingdom of Castile, Henry II, who had pledged support for Charles V. When the Caroline war began in 1369, the Eng...

• 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...

• Interstellar Matter - astronomy.

  silhouette of a cloud of dust. At other times, it blocks only a percentage of the light from behind it, a process known by astronomers as extinction . The long, narrow dark lanes in the Milky Way as seen from Earth are examples of extinction. The amount of extinction is different for different wavelengths of light. A2 Reddening Starlight that does not get completely absorbed by interstellar dust can still be changed by the dust’s effects. As light passes through less dense patches of interstel...

• 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...

• Hardware (computer).

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