137 résultats pour "environment"

• 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...

• Cat Family - biology.

  cats have coats that are mainly brown, yellow, or gray, often with white underbellies. The cubs of many species of cats have spotted coats, which helps hide them ingrass and underbrush from predators. Adult cats that have mainly spotted patterns in their fur include cheetahs, leopards, clouded leopards, jaguars, ocelots, margays, Geoffroy’s cat, and servals. Singlecolor coats are found in lions, pumas, and jaguarundis. Some individuals among leopards and jaguars, and more rarely in other species...

• Maine - geography.

  temperatures range from 17° to 21°C (62° to 70°F) with the southern interior being the warmest and the east coast and north the coolest. However, daytime summertemperatures may reach the lower 30°s C (lower 90°s F), and temperatures in winter have fallen as low as -44°C (-48°F) in the interior. D2 Precipitation Precipitation (rainfall and snowfall) in Maine is evenly distributed throughout the year. Most areas receive from 860 to 1,020 mm (34 to 40 in) yearly, although parts ofthe coast are som...

• Maine - USA History.

  temperatures range from 17° to 21°C (62° to 70°F) with the southern interior being the warmest and the east coast and north the coolest. However, daytime summertemperatures may reach the lower 30°s C (lower 90°s F), and temperatures in winter have fallen as low as -44°C (-48°F) in the interior. D2 Precipitation Precipitation (rainfall and snowfall) in Maine is evenly distributed throughout the year. Most areas receive from 860 to 1,020 mm (34 to 40 in) yearly, although parts ofthe coast are som...

• Costa Rica - country.

  protection from future deforestation is not guaranteed. Deforestation places Costa Rica’s rich biodiversity in danger. The country’s location on the cusp between Northand South America and its abundance of tropical forests make it home to a great variety of species, many of them rare and threatened. Deforestation also contributesto the country’s problematic rate of soil erosion. Costa Rica is party to international treaties concerning biodiversity, climate change ( see Global Warming), endangere...

• Concepts

  suggested that concept possession need not consist in knowing a definition, but in appreciating the role of a concept in thought and practice. Moreover, he claimed, a concept need not apply to things by virtue of some closed set of features captured by a definition, but rather by virtue of ‘family resemblances' among the things, a suggestion that has given rise in psychology to ‘prototype' theories of concepts. Most traditional approaches to possession conditions have been concerned with t...

• Technology.

  loose soil in this region, known as the Fertile Crescent, was easily scratched for planting, and an abundance of trees was available for firewood. By 5000 BC, farming communities were established in areas known today as Syria, Turkey, Lebanon, Israel, Jordan, Greece, and the islands of Crete and Cyprus. Agricultural societies in these places constructed stone buildings, used the sickle to harvest grain, developed a primitive plowstick, and advanced their skills inmetalworking. Trade in flint al...

• Telephone.

  digits is dialed. The development of inexpensive and reliable amplification provided by the introduction of the transistor in the 1960s made practical the design of adialing system based on the transmission of relatively low power tones instead of the higher-power dial pulses. Today most telephones have push buttons instead of a rotary dial. Touch-Tone is an optional service, and telephone companies still maintain the ability to receive pulsedialing. Push-button telephones usually have a switch...

• Zoology - biology.

  is still in its infancy and is quite controversial, chiefly because it has raised anew the old dispute about whether behavior is genetically determined. See Animal Behavior; Sociobiology. Embryology, the study of the development of individual animals, has investigated the way in which developing parts interact—for example, the interactions between theeyestalk and the epidermis during development of the lens of the eye. The emerging field of molecular development applies the techniques of molecu...

• Rock (mineral).

  pressure mineral assemblage. In a sense, the rock is stuck in a state that is characteristic of its earlier high-temperature and high-pressure environment. Thus,metamorphic rocks carry with them information about the history of temperatures and pressures to which they were subjected. The size, shape, and distribution of mineral grains in a rock are called the texture of the rock. Many metamorphic rocks are named for their main texture. Textures giveimportant clues as to how the rock formed. As t...

• Arthropod - biology.

  through a series of distinct phases to become adults. Larvae may also inhabit different environments and eat different foods than their parents. The life spans ofarthropods range from a few weeks to several decades. V ARTHROPOD EVOLUTION The evolutionary origins of modern arthropods are unclear and complex. It is generally accepted that the phylum is polyphyletic—that is, derived from several separateancestral lines. The ancestors of arthropods were ancient aquatic segmented worms, similar to p...

• Prokaryote - biology.

  earliest organisms to evolve, an estimated 3.4 billion to 3.5 billion years ago. The environment of the early Earth lacked oxygen, and cyanobacteria probably usedfermentation (a chemical process performed without the presence of oxygen) to produce the energy molecule adenosine triphosphate (ATP). Cyanobacteria introduced oxygen into the atmosphere through the process of photosynthesis. As the oxygen content in the atmosphere increased over the centuries, bacteria evolved that usedthis oxygen in...

• Frank Lloyd Wright.

  C Usonian Houses Wright achieved his goal of low-cost, democratic American architecture with his Usonian houses of the 1930s. Usonia was Wright’s term for the United States of North America, with an i added for a pleasing sound. The Usonian house had a simple design, usually with an L-shaped floor plan. This plan separated the noisier living space on one leg of the L from the quieter bedroom space on the other leg. The floor was made of concrete slabs, typically in a square grid of 4 by 4...

• Wetland.

  Other plants and animals have special adaptations suited for living in a wet environment. Most emergent plants have air spaces in their stems that enable oxygen to betransported to roots that grow in sediments with no oxygen. Some of the trees that grow in swamps form a set of roots above the soil surface or above the water thatallows them to get oxygen to the lower roots. In saltwater wetlands, specialized cells can limit the amount of salt that enters a plant, or specialized organs can excrete...

• 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...

• Camel - biology.

  of water in the stomach or hump as was once commonly believed. Unlike other mammals, however, the camel can survive as long as three weeks without drinking,depending on the water content of its food. It can survive a water loss of about 40 percent of its normal body weight. In comparison, a loss of 15 percent is usually fatalfor humans. Camels can go without water due to several unique adaptations to their environment. The camel conserves more water in its body than any other mammal. It excretes...

• Frank Lloyd Wright I INTRODUCTION Robie House The Frederick C.

  Hills/DeCaro HouseAmerican architect Frank Lloyd Wright, a pioneer of modern architecture, lived and worked in the Chicago area during thelate 19th and early 20th centuries. He designed many single-family houses, known as prairie houses. The Hills/DeCarohouse in Oak Park, west of Chicago, is one of more than 20 houses Wright designed while living in the town between 1890and 1910.© 2007 Frank Lloyd Wright Foundation / Artists Rights Society (ARS), New York / Photo: Mary Ann Hemphill/Photo Researc...

• Depression (psychology).

  IV CAUSES Some depressions seem to come out of the blue, even when things are going well. Others seem to have an obvious cause: a marital conflict, financial difficulty, or somepersonal failure. Yet many people with these problems do not become deeply depressed. Most psychologists believe depression results from an interaction betweenstressful life events and a person’s biological and psychological vulnerabilities. A Biological Factors Depression runs in families. By studying twins, researche...

• 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...

• 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...

• Bat - biology.

  tomb bat has rather small ears. The shapes of bat ears are extremely varied. The wide ears of the Australian false vampire bat meet above the head and are fused.Many bats are able to turn their ears in the direction of faint noises. Bat hearing and its use in echolocation are highly developed. Some bats have large, conspicuous eyes, while others may have small beady eyes. This variation suggests that vision plays different roles in the lives of various species.Despite the familiar expression, 'b...

• Fungus - biology.

  Many fungi can reproduce by the fragmentation of their hyphae. Each fragment develops into a new individual. Yeast, a small, single-celled fungus, reproduces bybudding, in which a bump forms on the yeast cell, eventually partitioning from the cell and growing into a new yeast cell. V CLASSIFICATION OF FUNGI Scientists have long disagreed about how to classify fungi, and the classification systems are still developing. The first description of fungi was published in 1729 byItalian botanist Pier...

• Vermont - geography.

  Forests cover 78 percent of Vermont. Most of the trees are deciduous, principally the maple, elm, birch, beech, oak, hickory, ash, cherry, and butternut. The state treeis the sugar maple, which provides Vermont’s famous maple syrup. Conifers are common in some mountain areas and include mainly the white pine, red spruce,hemlock, and cedar. A great variety of ferns have been found within the state. Among the more common wildflowers that grow in Vermont are anemones, arbutuses,violets, lilacs, dai...

• Vermont - USA History.

  Forests cover 78 percent of Vermont. Most of the trees are deciduous, principally the maple, elm, birch, beech, oak, hickory, ash, cherry, and butternut. The state treeis the sugar maple, which provides Vermont’s famous maple syrup. Conifers are common in some mountain areas and include mainly the white pine, red spruce,hemlock, and cedar. A great variety of ferns have been found within the state. Among the more common wildflowers that grow in Vermont are anemones, arbutuses,violets, lilacs, dai...

• Mountain Climbing.

  teeth on one side, and a straight, flat, metal blade called an adze on the other. Ice axes have many uses. One of the most common is to help the climber stay balanced on steep slopes. The climber swings the axe with a short, quick movement to lodge the pick in snow or ice, creating a secure anchor. If a climber should slip and beginsliding down a snowfield, a self-arrest can be performed by turning face down on the snow and burying the pick in the snow surface. The climber’s weight over the...

• Skin. I INTRODUCTION Skin, outer body covering of an animal. The term skin

  III SKIN APPENDAGES In humans, the skin appendages, or structures embedded in the skin, include hair, nails, and several types of glands. Glands are groups of cells that produce andsecrete substances needed by other parts of the body. In other vertebrates, the skin appendages include scales (in fish and reptiles) and feathers (in birds). Together,the skin and the skin appendages are known as the integumentary system of the body. A Hair Hair is a distinguishing characteristic of mammals, a gro...

• Pablo Picasso.

  Color juxtapositions—between blue and orange, for instance—are intentionally strident and unharmonious. The representation of space is fragmented and discontinuous. While the left side of the canvas is largely Iberian-influenced, the right side is inspired by African masks, especially in its striped patterns and oval forms. Suchborrowings, which led to great simplification, distortion, and visual incongruities, were considered extremely daring in 1907. The head of the figure at the bottom right,...

• Saskatchewan (province) - Geography.

  The length of the frost-free season varies within the province. In the southwest, particularly in the valley lands along the South Saskatchewan River, the frost-freeperiod ranges from 150 to 160 days. Regina enjoys about 123 frost-free days, and Saskatoon has about 111. The far north has only from 85 to 95 frost-free days. One important characteristic of Saskatchewan’s climate is the great variability in temperature and precipitation from year to year, which is often critical for agriculture.The...

• Saskatchewan (province) - Canadian History.

  The length of the frost-free season varies within the province. In the southwest, particularly in the valley lands along the South Saskatchewan River, the frost-freeperiod ranges from 150 to 160 days. Regina enjoys about 123 frost-free days, and Saskatoon has about 111. The far north has only from 85 to 95 frost-free days. One important characteristic of Saskatchewan’s climate is the great variability in temperature and precipitation from year to year, which is often critical for agriculture.The...

• Arctic - Geography.

  The Arctic is not a frozen desert devoid of life on land or sea, even during the cold, dark winter months. Spring brings a phenomenal resurgence of plant and animal life.Low temperatures are not always the critical element—moisture, the type of soil, and available solar energy are also extremely important. Some animals adapt well toArctic conditions; for instance, a number of species of mammals and birds carry additional insulation, such as fat, in cold months. Arctic summers with extended dayli...

• Saudi Arabia - country.

  C Natural Resources Some of the world’s largest oil and natural gas fields lie beneath Saudi Arabia and its offshore waters, representing the country’s most economically important naturalresource. In 2007 Saudi Arabia’s oil reserves were estimated at 264 billion barrels. Before the discovery and exploitation of these reserves in the mid-20th century,Saudi Arabia was one of the poorest countries in the world. Its relatively small population subsisted in a harsh environment with little agricultur...

• Spider (arthropod) - biology.

  The spider’s abdomen is soft and saclike. On the underside of the tip of the abdomen are three pairs of spinnerets. Each spinneret is studded with many fine, hairliketubes called spigots, which produce a variety of silk threads. The spigots lead to several large silk glands inside the abdomen. Silk is formed as a liquid inside theseabdominal glands. As the silk is drawn out through the spigots, protein molecules within the silk line up parallel to one another, causing the silk to harden and form...

• History of United States Business.

  their lives. But the rewards were worth it; a few lucrative voyages and a merchant could buy a townhouse, a carriage, perhaps a summer retreat. The merchant couldclimb the social ladder and circulate among the powerful in this highly materialistic society. This prospect of riches and the honor that accompanied them made Americancolonists willing to engage in highly speculative enterprises, such as shipping flour to the West Indies or importing goods from England by the thousands without beingcer...

• Québec - Geography.

  facilities. Tributaries south of the St. Lawrence include the Richelieu, the Saint-François, and the Chaudière rivers, which are only a few hundred kilometers long. TheRimouski and Matane rivers, also south of the St. Lawrence, are popular areas for recreation and salmon fishing. In the Canadian Shield, the longest rivers are theRupert, Eastmain, Grande Baleine, and La Grand-Rivière, which is the site of a huge hydroelectric complex. C Coastlines Québec has two systems of saltwater coastline. O...

• Québec - Canadian History.

  facilities. Tributaries south of the St. Lawrence include the Richelieu, the Saint-François, and the Chaudière rivers, which are only a few hundred kilometers long. TheRimouski and Matane rivers, also south of the St. Lawrence, are popular areas for recreation and salmon fishing. In the Canadian Shield, the longest rivers are theRupert, Eastmain, Grande Baleine, and La Grand-Rivière, which is the site of a huge hydroelectric complex. C Coastlines Québec has two systems of saltwater coastline. O...

• Insect - biology.

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

• British Columbia - Geography.

  hemlock, Douglas fir, Sitka spruce, and various cedars, grows rapidly in the mild, wet climate and produces the largest trees in Canada. In the dry lowlands of thesouthern and central interior, ponderosa and lodgepole pines, aspen, and bunchgrass are characteristic. Spruce dominates the Prince George region. Prairie grasses andstands of aspen are found in the northeastern corner of the province. At elevations higher than about 1,800 m (about 6,000 ft), an alpine vegetation of shrubs, mosses,and...

• British Columbia - Canadian History.

  hemlock, Douglas fir, Sitka spruce, and various cedars, grows rapidly in the mild, wet climate and produces the largest trees in Canada. In the dry lowlands of thesouthern and central interior, ponderosa and lodgepole pines, aspen, and bunchgrass are characteristic. Spruce dominates the Prince George region. Prairie grasses andstands of aspen are found in the northeastern corner of the province. At elevations higher than about 1,800 m (about 6,000 ft), an alpine vegetation of shrubs, mosses,and...

• Terrorism.

  exploitation, ethnic discrimination, and religious persecution. Perceived inequities in the distribution of wealth and political power have led some terrorists to attempt tooverthrow democratically elected governments. To achieve a fairer society, they would replace these governments with socialist or communist regimes. Left-wingterrorist groups of the 1960s and 1970s with such aims included Germany’s Baader-Meinhof Gang, Italy’s Red Brigades, and the Weather Underground ( see Weathermen) in the...

• European Union .

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

• 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...

• New Mexico - geography.

  New Mexico’s major river is the Río Grande, originating in southern Colorado, and flowing southward for 760 km (470 mi) through the state. Between the San LuisValley and Española Valley the river flows in a deep canyon known as the Río Grande Gorge; then, below White Rock Canyon, it flows through several valleys containingagricultural land. Most of the water of the Río Grande is used to irrigate these valleys. The Río Grande’s waterflow in New Mexico is extremely low. One of the major tributarie...

• New Mexico - USA History.

  New Mexico’s major river is the Río Grande, originating in southern Colorado, and flowing southward for 760 km (470 mi) through the state. Between the San LuisValley and Española Valley the river flows in a deep canyon known as the Río Grande Gorge; then, below White Rock Canyon, it flows through several valleys containingagricultural land. Most of the water of the Río Grande is used to irrigate these valleys. The Río Grande’s waterflow in New Mexico is extremely low. One of the major tributarie...

• 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...

• green activist

  In recent weeks, the Brazilian Government took measures to protect small farmers and environmentalists threatened   with death in the Amazon. In may, a couple of activists was murdered in an ambush in the State of Pará.               The work of census conducted this year by the NGO Global Witness,   two people are killed every week because of their commitment to the environment.                              Activists,   representatives of indigenous peoples, they are threatened and persecuted b...

• Exki implementation in UK

• Bird. I INTRODUCTION Bird, animal with feathers and wings. Birds are the only

  B Physical Adaptations for Flight The internal body parts of all birds, including flightless ones, reflect the evolution of birds as flying creatures. Birds have lightweight skeletons in which many of themajor bones are hollow. A unique feature of birds is the furculum, or wishbone, which is comparable to the collarbones of humans, although in birds the left and rightportions are fused together. The furculum absorbs the shock of wing motion and acts as a spring to help birds breathe while they...

• Bird - biology.

  B Physical Adaptations for Flight The internal body parts of all birds, including flightless ones, reflect the evolution of birds as flying creatures. Birds have lightweight skeletons in which many of themajor bones are hollow. A unique feature of birds is the furculum, or wishbone, which is comparable to the collarbones of humans, although in birds the left and rightportions are fused together. The furculum absorbs the shock of wing motion and acts as a spring to help birds breathe while they...