478 résultats pour "livi"

• Ant - biology.

  The workers of many ant species carry a stinger within the hind end of the gaster. These ants use the stinger to defend against their enemies. In some species, workerants lack a stinger but use the tip of their gaster to squirt or dab poison at other small animals and when fighting battles with other ants, fending off predators, or killinginsects or other animals that they use as food. III PHYSIOLOGY Ants have a rigid, external skeleton called an exoskeleton that gives the soft, inner body its...

• Kenya - country.

  threatens fish and other water life in the lake by depriving them of oxygen. Kenya is well known for its game parks—including Masai Mara Game Park and Tsavo National Park in the south, and Marsabit National Reserve in the north—whichattract large numbers of tourists and much revenue. Conservation of wildlife within reserves has thus received high priority. About 13 percent (2007) of Kenya’s totalland is protected. There are 229 (2004) threatened species in Kenya. Threatened habitats include the...

• Mammal - biology.

  On land, mammals live in many different habitats, and at a wide range of altitudes. Many mammals dig burrows as refuges or as places to raise their young, but somehave developed a largely subterranean lifestyle, feeding on small animals or plant roots beneath the soil's surface. These animals, including moles and mole-rats, digthrough the ground either with spadelike front paws or with their teeth, and they detect danger by being highly sensitive to vibrations transmitted through the soil.Most m...

• Mental Retardation.

  For example, measles, chicken pox, and whooping cough may lead to encephalitis and meningitis, which can damage the brain. Physical trauma to the brain can also cause mental retardation. Brain damage may result from accidental blows to the head, near drowning, severe child abuse, andchildhood exposure to such toxins as lead and mercury. Experts believe that poverty and a lack of stimulation during infancy and early childhood can be factors inmental retardation. Children raised in poor environmen...

• Democratic Republic of the Congo - country.

  Except in the high elevations, the country’s climate is very hot and humid. The average annual temperature in the low central area is about 27°C (about 80°F).Temperatures are considerably higher in February, the hottest month. At altitudes above about 1,500 m (about 5,000 ft) the average annual temperature is about 19°C(about 66°F). Average annual rainfall is about 1,500 mm (about 60 in) in the north and about 1,300 mm (about 50 in) in the south. Frequent heavy rains occur fromApril to November...

• 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...

• 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...

• Burkina Faso - country.

  powers to promote the welfare of the people. The Lobi live in the southwest as farmers and hunters. Defiant of newcomers, they live in small terraced fortifications. The Bobo are chiefly farmers, artisans, and metalworkers living in large villages in the west-central part of the country. The Gourounsi are mainly artisans and farmers in the south-central areas. Their society is lesshighly structured than that of the other Voltaic groups. Christianity has made substantial inroads among them. The M...

• Coral - biology.

  Soft corals lack a distinct skeleton. Although they live in colonies, the individual polyps are fused into a complex body, usually strengthened by small lumps or spikesknown as sclerites, which are made of protein and calcite. Soft corals come in a variety of shapes, including undulating sheets, upright mushroomlike shapes, andbeautiful shapes that form branches. A number of other octocorals have skeletons made from a hard or horny protein, sometimes strengthened with more brittle calcareous dep...

• Animal - biology.

  Vertebrates are customarily divided into cold-blooded and warm-blooded animals, but these labels are not very precise. Biologists normally use the terms ectoderm and endoderm to describe temperature regulation more accurately. An ectoderm is an animal whose temperature is dictated by its surroundings, while an endoderm is one that keeps its body at a constant warm temperature by generating internal heat. Reptiles, amphibians, and fish are ectoderms. Although they do not maintain a constant wa...

• Bears.

  American black bears live in Canada, the United States, and northern Mexico. Scientists think there maybe as many as 700,000 black bears in the United States. American black bears eat grasses, berries,acorns, and walnuts. BROWN BEAR Brown bears have fur that is light or dark brown. They also have a big hump on their shoulders. Theirsnout is turned upward. Brown bears live in Asia, Europe, and North America. Grizzly bears are a kind ofbrown bear. Brown bears are among the largest bears. Large mal...

• Rain Forest.

  dropped into the heart of the forest by helicopters. Suspended from the crane’s long, movable arm is a large gondola that functions as a mobile treetop laboratory.Moving from tree to tree, forest researchers collect specimens, conduct experiments, and observe life in the canopy frontier. The highest stratum of the rain forest is made up of the emergent trees, those individuals that stick up above the forest canopy. Emergents, which do not form acontinuous layer, are usually the giants of the for...

• Being Brown

  eurocentriques du monde, une joie qui vient du fait d'être parfaitement centré culturellement… »   D. Writing :    Priya dislikes living in America, she thinks it is a land of inequalities. She praises Indian values that seem better according to her. Her father disagrees with her, he praises American values, and seems to be happy with all the comfort he could get in the United States.    Both sides have positive and negative aspects. First, about Priya's point of view. She is right when she says...

• Vitamin.

  Vitamin B 1, or thiamine, promotes the metabolism of carbohydrates, enabling these nutrients to release their energy. Thiamine also plays a role in the functioning of the nervous system, muscles, and heart. The body does not store thiamine and people who are malnourished may develop thiamine deficiency. Mild thiamine deficiency cancause fatigue, muscle weakness, and loss of appetite. Severe thiamine deficiency causes beriberi, a disease characterized by muscle weakness, swelling of the heart,and...

• 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...

• Venezuela - country.

  Venezuela has six navigable rivers. Of the thousand or more streams in the country, the majority flow into the Orinoco. The Orinoco flows east across central Venezuelaand drains approximately four-fifths of the total area of the country. With the tributaries—the Apure, Meta, and Negro rivers—it forms the outlet into the Atlantic Oceanfor the waters of much of the interior of Colombia, as well as of inland Venezuela. F Climate The climate of Venezuela is tropical on the Llanos and along the coas...

• Chile - country.

  D Plant and Animal Life The indigenous plant life of Chile varies according to climatic zone. Plant life in the northern region includes brambles and cactus and has little variety. Here, theAtacama provides one of the best examples on Earth of an absolute desert. The more humid Central Valley supports several species of cacti, espino (a thorny shrub),grasses, and the Chilean pine, which bears edible nuts. Dense rain forests are located south of Valdivia with laurel, magnolia, false beech, and v...

• From Walden - anthology.

  instant? We should live in all the ages of the world in an hour; ay, in all the worlds of the ages. History, Poetry, Mythology!—I know of no reading of another'sexperience so startling and informing as this would be. The greater part of what my neighbors call good I believe in my soul to be bad, and if I repent of any thing, it is very likely to be my good behavior. What demonpossessed me that I behaved so well? You may say the wisest thing you can old man,—you who have lived seventy years,...

• Giant Panda - biology.

  In 2007 conservationists announced that a parasitic roundworm was responsible for a significant number of the panda deaths reported in the wild since 1990. Theparasite Baylisascaris schroederi causes the disease visceral larval migrans, which results in bleeding in the lungs, the liver, and the intestines, and can also affect the brain. It is not known if other recent pandas deaths were caused by the same parasite or by a different contagious disease. Loss of habitat from deforestation is forc...

• Whale - biology.

  III BEHAVIOR OF WHALES Studies of whales in captivity have taught scientists much about the complex social behavior of whales. Since the late 1980s, advances in the use of satellite trackingsystems have also broadened opportunities for scientists to observe how whales behave in the wild. A Swimming and Diving Whales swim by making powerful up-and-down movements of the tail flukes, which provide thrust. The power comes from body muscles that flex the lower spine upand down in a wavelike motion...

• 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...

• 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...

• Middle East - Geography.

  though overall they have improved considerably since the 1970s. This variation reflects the different levels of wealth and development in countries of the Middle East. Inthe highly developed country of Israel the infant mortality rate was 8 deaths per 1000 live births in 1997. By comparison, the rate per 1000 live births was 71 in less-developed Egypt and 75 in Yemen. A Ethnic Groups and Languages Arabs make up the majority of the people of the Middle East, accounting for almost the entire popu...

• Israel (country) - country.

  harbor in the northern part of the country, and Ashdod, an artificial deepwater port to the south, serve as the main seaports on the Mediterranean. The port of Elat onthe Gulf of Aqaba provides Israel’s only access to the Red Sea, making it extremely important to the country’s shipping interests. D Natural Resources Although much of Israel’s desert regions contain poor soils, the northern Negev, the coastal plains, and the interior valleys provide patches of productive soils. Anestimated 18 per...

• Texas - geography.

  D Climate Eastern Texas has a humid subtropical climate, while a semiarid low latitude climate prevails in central areas, and an arid low latitude climate in the extreme west. Alongthe coast the climate is much milder, with fewer extremes in temperatures. Hurricanes sometimes hit the coastal areas of Texas from late July through September, andtornadoes are common in north-central Texas in April and May. D1 Temperature Summers are hot throughout the state, and temperatures exceeding 35°C (95°F)...

• Texas - USA History.

  D Climate Eastern Texas has a humid subtropical climate, while a semiarid low latitude climate prevails in central areas, and an arid low latitude climate in the extreme west. Alongthe coast the climate is much milder, with fewer extremes in temperatures. Hurricanes sometimes hit the coastal areas of Texas from late July through September, andtornadoes are common in north-central Texas in April and May. D1 Temperature Summers are hot throughout the state, and temperatures exceeding 35°C (95°F)...

• Diseases of Animals.

  infected animal. It may also spread in milk or in garbage that contains contaminated meat. Typical symptoms include blisters that appear on the mouth and feet;animals may become lame when their hooves degenerate. Canine distemper is a highly contagious disease caused by the paramyxovirus, which is transmitted in discharges from the nose and eyes. Symptoms begin with fever,malaise, and nasal and ocular discharges and may progress to convulsions and other nervous system disorders. Parvoviruses aff...

• Fishing.

  directly to the spool and turns the spool one rotation at a time. C Fishing Lines Fishing lines serve as the link between the angler’s reel and the lure or bait. The most popular line used for sportfishing is monofilament nylon line, which is strong anddurable and has a certain amount of stretch, which helps when an angler sets the hook. The line comes in a variety of strengths, from 2-pound test to more than 100-pound test. (Pound test is the amount of pressure that can be put on a line before...

• Epinay, dame de La Live d'F175D Fontenelle, Bernard le Bovier deF175A Prades,

• Birding - biology.

  swallows, and rock doves nest on buildings in cities, towns, and farms. The chimney swift has abandoned hollow trees for chimneys as a nest site in urban areas.Mallards and Canada geese—once exclusively wild, migratory species—now live year-round in the open spaces found in city parks and golf courses. Nearly all purplemartins, a songbird species that once used the abandoned nests of woodpeckers or the natural cavities of cliffs or dead trees, now live primarily in structures specificallyconstru...

• Algeria - country.

  areas to fishing. National parks, including the giant Tassili N’Ajjer National Park in the eastern corner of the country, comprise a large proportion of the protected area. The effects of Algeria’s human population on the fragile landscape have been severe. The greatest ecological threats are deforestation and burning of scrub vegetation,conversion of steppe habitat to arable land, and soil erosion due to overgrazing and poor farming practices. Pollution of Mediterranean coastal waters is pervas...

• Vietnam - country.

  E Natural Resources Vietnam’s most valuable natural resource is its land, particularly the fertile, alluvial soils in the Red and Mekong deltas. Some 29 percent of the land is currently beingcultivated. Vietnam has some valuable mineral resources, including gold, iron, tin, zinc, phosphate, chromite, apatite, and anthracite coal. Most deposits are located in the northernpart of the country. Few attempts were made to extract these minerals until the French takeover of Vietnam at the end of the 1...

• Houdetot (Élisabeth de La Live de Bellegarde.

• Aging - biology.

  Different theories have been proposed to explain how SF works. One theory is based on the assumption that aging, and diseases that occur more frequently withadvancing age, are caused by structural damage to cells. This damage accumulates in tiny amounts each time the cell divides, eventually preventing the cell fromcarrying out normal functions. One cause of this damage may be free radicals, which are chemical compounds found in the environment and also generated by normal chemical reactions in...

• 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...

• Animation I INTRODUCTION Finding Nemo A clown fish named Marlin, left, and his friend Dory search for Marlin's son in the computer-animated feature film Finding Nemo (2003).

  Animator at WorkAnimators use computers for every part of the animation process, from creating a storyboard (a scene-by-sceneillustration of the plot) to imitating camera movement. This animator is creating a scene for the motion picture Antz(1998).C. Lepetit/Liaison Agency If an animator is basing the animation project on drawings, one of the most common animation techniques, he or she will first create a series of rough sketches thatoften will be filmed in a pencil test (simple line drawings...

• Blood.

  substances. For example, a person who is blood type A positive will not make antibodies against the A or Rh markers, but will make antibodies against the B marker,which is not on that person’s own red blood cells. If blood containing the B marker (from types B positive, B negative, AB positive, or AB negative) is transfused into thisperson, then the transfused red blood cells will be rapidly destroyed by the patient’s anti-B antibodies. In this case, the transfusion will do the patient no good a...

• Ecuador - country.

  F Natural Resources Ecuador’s main mineral wealth is in petroleum. Other mineral resources of the country include gold, silver, copper, lead, and zinc. Forests cover 38.3 percent of thecountry. G Plants and Animals Along the northern part of the Ecuador coast, and within the inner portion of the southern coast, tropical jungles abound. In some places the jungles extend up theslopes of the Andes as wet, mossy forests. Dense forests cover both flanks of the Cordilleras, as well as the Oriente, u...

• Cheetah - biology.

  animals such as zebras. Unlike most cats, cheetahs hunt during the day, when lions and hyenas that compete with them for prey are less likely to be active. Still,scientists in Tanzania have observed that cheetahs lose 10 to 13 percent of their kills to lions and hyenas. Alerted by the panic of a gazelle herd or by the circling ofvultures, lions and hyenas close in and easily drive the more timid cheetah away from a fresh kill. A cheetah usually stalks prey to within about 10 m (about 33 ft) and...

• Republic of Indonesia - country.

  Mahakam in East Kalimantan and the Martapura and Barito in South Kalimantan. Most of these rivers originate in the island’s central massif (mountain mass) and meander through extensive swamps as they approach the coast. Settlements such as Samarinda and Banjarmasin cluster along the rivers, which serve ascommunication routes into the interior. The largest rivers on Sumatra drain from west to east into the Strait of Malacca. In the north, the Asahan River once linked trade between the Batak peo...

• Native American Architecture I INTRODUCTION Native American Architecture, traditional architecture of the peoples of who lived in North America before Europeans arrived.

  Mound Builders who resided in the area.John Elk III/Bruce Coleman, Inc. Another mound building culture, named Hopewell, also appears to have originated in Ohio but expanded west to Iowa, Kansas, and Oklahoma, south to Louisiana,Mississippi, and Alabama, east to Georgia and the Appalachian Mountains, and north to Wisconsin, Michigan, and lower Ontario in Canada. The Hopewell culture lastedfrom about 200 BC to 400 AD. Hopewell people built large, linear mounds to create enclosures in geometrical...

• 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...

• Human Nutrition.

  is one of the most preventable types of cancer. Nutritionists caution that most Americans need to eat more complex carbohydrates. In the typical American diet, only 40 to 50 percent of total calories come fromcarbohydrates—a lower percentage than found in most of the world. To make matters worse, half of the carbohydrate calories consumed by the typical American comefrom processed foods filled with simple sugars. Experts recommend that these foods make up no more that 10 percent of our diet, bec...

• Dog Family - biology.

  muzzles, long and bushy tails, and large ears. Many foxes hunt by stalking prey and then leaping on it with a distinctive, stiff-legged pounce. Once thought to besolitary animals, foxes are now known to live in groups of up to six individuals. The remaining canids are each highly distinctive. Raccoon dogs and bush dogs are the least doglike canids in appearance. Raccoon dogs, found in eastern Asia, havestubby legs, a stout body, short ears, shaggy fur, and a black face mask that resembles a racc...

• Whales.

  whales travel to cool waters near the Arctic or Antarctica every summer. They feed on krill , small animals that look like shrimp. In the winter, baleen whales head for warmer waters near the equator tobreed. Other whales do not migrate. Narwhals, for instance, live year-round in the cool waters of the Arctic andNorth Atlantic oceans. HAVING BABY WHALES After male and female whales mate, it takes from 10 to 16 months for a baby whale to form. The lengthof time depends on the whale species. A wh...

• Religion.

  By the end of the 19th century, scholars were making religion an object of systematic inquiry. Müller’s comparative approach was adopted in many European andJapanese universities, and as a result the common features of world religions (such as gods, prayer, priesthood, and creation myths) were the subjects of sustainedscholarly investigation. In addition, field anthropologists had begun to compile firsthand accounts of the religions of peoples who previously had been dismissed assavages. The stu...

• Circulatory System.

  C Additional Functions In addition to oxygen, the circulatory system also transports nutrients derived from digested food to the body. These nutrients enter the bloodstream by passingthrough the walls of the intestine. The nutrients are absorbed through a network of capillaries and veins that drain the intestines, called the hepatic portal circulation.The hepatic portal circulation carries the nutrients to the liver for further metabolic processing. The liver stores a variety of substances, suc...

• Dog. I INTRODUCTION Dog, mammal generally considered to be the first domesticated animal.

  French word for butterfly because it has ears that resemble butterfly wings, is a happy, friendly dog, suitable for small living spaces. The final dog group, nonsporting ,includes a wide variety of purebreds that differ in size, coat, overall appearance, and personality, from the shorthaired spotted dalmatian to the curly-haired poodle. V DOG BEHAVIOR Instinctive behaviors of the domestic dog are comparable to those of its wild relatives, the wolf, coyote, fox, and jackal. Unlike trained behavi...