262 résultats pour "growth"

• Population.

  year AD 1, and it took more than 1,500 years to reach the 500 million mark. Growth was not steady but was marked by oscillations dictated by climate, food supply, disease, and war. Starting in the 17th century, great advances in scientific knowledge, agriculture, industry, medicine, and social organization made possible rapid acceleration inpopulation growth. Machines gradually replaced human and animal labor. People slowly acquired the knowledge and means to control disease. By 1900 the worldp...

• Hormone.

  women is called a follicle-stimulating hormone. When a follicle-stimulating hormone binds to an ovary cell, it stimulates the enzymes needed for the synthesis ofestradiol, a female sex hormone. Another gonadotropin called luteinizing hormone regulates the production of eggs in women and the production of the male sexhormone testosterone. Produced in the male gonads, or testes, testosterone regulates changes to the male body during puberty, influences sexual behavior, and playsa role in growth. T...

• Ecology.

  an input of nutrients exceeding the capability of the ecosystem to process them. Nutrients eroded and leached from agricultural lands, along with sewage and industrialwastes accumulated from urban areas, all drain into streams, rivers, lakes, and estuaries. These pollutants destroy plants and animals that cannot tolerate theirpresence or the changed environmental conditions caused by them; at the same time they favor a few organisms more tolerant to changed conditions. Thus,precipitation filled...

• Ecology - biology.

  an input of nutrients exceeding the capability of the ecosystem to process them. Nutrients eroded and leached from agricultural lands, along with sewage and industrialwastes accumulated from urban areas, all drain into streams, rivers, lakes, and estuaries. These pollutants destroy plants and animals that cannot tolerate theirpresence or the changed environmental conditions caused by them; at the same time they favor a few organisms more tolerant to changed conditions. Thus,precipitation filled...

• Child Development.

  developmental scientists have studied how cultural values guide the skills and attitudes that children acquire as they mature, and how brain maturation influences thedevelopment of thinking and feeling. For a more detailed discussion of child development theories, see the Theories of Child Development section of this article. III BASIC QUESTIONS A Nature and Nurture Scholars have long debated the relative importance of nature (hereditary influences) and nurture (environmental influences) i...

• Sydney (Australia) - geography.

  blocks in the eastern suburbs and around railway stations elsewhere; and homes on large lots in the outer suburbs, especially those to the northwest. For publichousing, the state government built a number of high-rise apartment blocks in run-down inner suburbs after World War II (1939-1945). These housing projects weresoon deemed unsuccessful and were discontinued because they fostered crime and other social problems. More recently, public housing has taken the form of separateor semidetached ho...

• 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...

• Indianapolis - geography.

  Amateur athletic competitions are frequent in Indianapolis. Each summer it is the site for the finals of the Hoosier State Games, with athletes of all ages and skill levelscompeting in 21 sports. In 1987 Indianapolis hosted the Tenth Pan American Games, and is often the site for numerous Olympic trials and collegiate sportschampionships. Among the many sports facilities are those for tennis, bicycle racing, skating, and track and field. The city’s professional football team, the Indianapolis Col...

• Egypt - country.

  Egypt has a wide variety of mineral deposits, some of which, such as gold and red granite, have been exploited since ancient times. The chief mineral resource ofcontemporary value is petroleum, found mainly in the Red Sea coastal region, at Al ‘Alamayn (El ‘Alamein) on the Mediterranean, and on the Sinai Peninsula. Otherminerals include phosphates, manganese, iron ore, and uranium. Natural gas is also extracted. D Plants and Animals The vegetation of Egypt is confined largely to the Nile Delta,...

• Development (biology) - biology.

  Understanding the molecular machinery within cells gives biologists a direct basis for understanding growth, because growth is the synthesis of new protoplasm, andbiologists know the basic mechanism of this synthesis. One key gap, however, exists in this knowledge. Biologists want to know not only how substances aresynthesized but also how growth is controlled so that the proportions of an animal or plant remain consistent from generation to generation. The direction and amountof growth, which a...

• 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...

• 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...

• Endocrine System.

  thermostat. When the heat in a house falls, the thermostat responds by switching the furnace on, and when the temperature is too warm, the thermostat switches thefurnace off. Usually, the change that a hormone produces also serves to regulate that hormone's secretion. For example, parathyroid hormone causes the body toincrease the level of calcium in the blood. As calcium levels rise, the secretion of parathyroid hormone then decreases. This feedback mechanism allows for tight controlover hormon...

• Mexico City - geography.

  The park houses some of Mexico's most important public buildings, including Chapultepec Castle. Construction of the castle began in 1783. Positioned on the park’shighest elevation, the castle functioned as a fortress during colonial times. It once served as the presidential residence and now houses the National Museum of History,which includes murals by 20th-century Mexican painter Juan O'Gorman. Los Pinos, the official residence and working offices of the president, is also on the grounds, buti...

• Dallas (Texas) - geography.

  VI RECREATION Dallas contains more than 400 parks that cover a total of about 20,000 hectares (about 50,000 acres). Notable parks include Marsalis Park, which contains the DallasZoo, and the parks surrounding White Rock Lake, Bachman Lake, and Lake Cliff. City-owned greenbelts parallel White Rock Creek, Turtle Creek, and the Trinity River.Fair Park contains a number of museums, the city aquarium, and the Cotton Bowl stadium (the site of the annual Cotton Bowl college football game), as well as...

• Himalayas - geography.

  result of deforestation the habitat of most of the wildlife has been destroyed. They are now restricted to special protected areas such as the Jaldapara and Kazirangasanctuaries in India ( see Kaziranga National Park) and the Chitawan preserve in Nepal. There are few animals in the Middle Himalayas because of extensive deforestation. In the Great Himalayas musk deer, wild goats, sheep, wolves, and snow leopards are found. The existence of the Abominable Snowman or Yeti has beenreported by highla...

• Pollution.

  One of the greatest challenges caused by air pollution is global warming, an increase in Earth’s temperature due to the buildup of certain atmospheric gases such ascarbon dioxide. With the heavy use of fossil fuels in the 20th century, atmospheric concentrations of carbon dioxide have risen dramatically. Carbon dioxide and othergases, known as greenhouse gases, reduce the escape of heat from the planet without blocking radiation coming from the Sun. Because of this greenhouse effect,average glob...

• Industrial Revolution I INTRODUCTION Industrial Revolution, widespread replacement of manual labor by machines that began in Britain in the 18th century and is still continuing in some parts of the world.

  The most important advance in iron production occurred in 1784 when Englishman Henry Cort invented new techniques for rolling raw iron, a finishing process thatshapes iron into the desired size and form. These advances in metalworking were an important part of industrialization. They enabled iron, which was relativelyinexpensive and abundant, to be used in many new ways, such as building heavy machinery. Iron was well suited for heavy machinery because of its strength anddurability. Because of t...

• Industrial Revolution .

  The most important advance in iron production occurred in 1784 when Englishman Henry Cort invented new techniques for rolling raw iron, a finishing process thatshapes iron into the desired size and form. These advances in metalworking were an important part of industrialization. They enabled iron, which was relativelyinexpensive and abundant, to be used in many new ways, such as building heavy machinery. Iron was well suited for heavy machinery because of its strength anddurability. Because of t...

• Ireland - country.

  F Plants and Animals Ireland’s animal life does not differ markedly from that of England or France. Over many centuries of human settlement almost all of Ireland’s natural woodlands werecleared, and indigenous animals such as bear, wolf, wildcat, beaver, wild cattle, and the giant Irish deer (a type of fallow deer) gradually disappeared. However, thehardy and versatile Connemara pony, Ireland’s only native pony breed, has been used by Irish farmers since prehistoric times. The great auk, or gar...

• Labor Unions in the United States - U.

  National Guard troops were used against the strikers, with the result that the strike was lost and the union that conducted it virtually destroyed. In 1894 a strike by theAmerican Railway Union against the Pullman Palace Car Company was defeated by an injunction issued under the Sherman Antitrust Act of 1890, which made acombination or contract in restraint of trade illegal. Thereafter employers used injunctions with increasing frequency and effectiveness as an antistrike weapon. See also Hours...

• Republic of Singapore - country.

  Singaporeans of Chinese and Indian ancestry live in small, nuclear families. Housing favors smaller families, as most units consist of small apartments in high-risebuildings. Western clothing is common, and foods reflect the Chinese, Malay, and Indian origins of the people. D Social Issues Since Singapore became an independent state in 1965, government policies have brought orderliness and efficiency to the country. Examples are supplanting slum andsquatter areas with high-rise public housing p...

• Los Angeles - geography.

  (2006 population, 472,494), located east of the Port of Los Angeles. The city of Compton (95,701) is located north of Long Beach, on the east side of the AlamedaCorridor. On the other side of the corridor are the cities of Torrance (142,350) and Inglewood (114,914). Northwest of Inglewood and west of downtown Los Angeles are the wealthy and fashionable Santa Monica (88,050) and Beverly Hills (34,979). Both cities are enclaves:Santa Monica is surrounded by the City of Los Angeles to the north, ea...

• Los Angeles - geography.

  (2006 population, 472,494), located east of the Port of Los Angeles. The city of Compton (95,701) is located north of Long Beach, on the east side of the AlamedaCorridor. On the other side of the corridor are the cities of Torrance (142,350) and Inglewood (114,914). Northwest of Inglewood and west of downtown Los Angeles are the wealthy and fashionable Santa Monica (88,050) and Beverly Hills (34,979). Both cities are enclaves:Santa Monica is surrounded by the City of Los Angeles to the north, ea...

• South Carolina - geography.

  (20° F) or lower, occur each winter. July temperatures average 27° C (80° F) in most of the state, with temperatures in the lower 20°s C (lower 70°s F) in themountains. Except in the mountains, summer daytime highs throughout South Carolina often enter the lower 30°s C (lower 90°s F). The temperature in July in Columbiaranges from 21° to 33° C (70° to 92° F). D2 Precipitation Central South Carolina has an average annual precipitation (both rainfall and snowfall) of 1,140 mm (45 in). Greater amo...

• South Carolina - USA History.

  (20° F) or lower, occur each winter. July temperatures average 27° C (80° F) in most of the state, with temperatures in the lower 20°s C (lower 70°s F) in themountains. Except in the mountains, summer daytime highs throughout South Carolina often enter the lower 30°s C (lower 90°s F). The temperature in July in Columbiaranges from 21° to 33° C (70° to 92° F). D2 Precipitation Central South Carolina has an average annual precipitation (both rainfall and snowfall) of 1,140 mm (45 in). Greater amo...

• Soil. I INTRODUCTION Soil, the loose material that covers the land surfaces of

  an exchange between plants and the atmosphere, as oxygen diffuses into the soil and is used by roots for respiration. In turn, the resulting carbon dioxide diffusesthrough pore spaces and returns to the atmosphere. This exchange is most efficient in soils with a high degree of porosity. For farmers, gardeners, landscapers, andothers with a professional interest in soil health, the process of aeration—making holes in the soil surface to permit the exchange of air—is a crucial activity. Theburrowi...

• Slavery in the United States - U.

  tripled, from about 1.2 million to almost 4 million in 1860. The natural growth of the slave population meant that slavery could survive without new slave imports. Natural population growth also hastened the transition from an African to an African American slave population. By the 1770s, only about 20 percent of slaves in thecolonies were African-born, although the concentration of Africans remained higher in South Carolina and Georgia. After 1808 the proportion of African-born slavesbecame tin...

• Iowa - geography.

  Okoboji, Lost Island, Silver, and West Swan lakes. In addition, reservoirs have been created by damming several smaller Iowa rivers. There are a number of largereservoirs behind dams on the Mississippi River along the Iowa state line. C Climate Iowa’s climate is characterized by warm, generally moist summers and cold winters. Temperatures vary considerably from season to season and, at times, from day today. However, monthly averages are relatively uniform throughout the state and usually vary...

• Iowa - USA History.

  Okoboji, Lost Island, Silver, and West Swan lakes. In addition, reservoirs have been created by damming several smaller Iowa rivers. There are a number of largereservoirs behind dams on the Mississippi River along the Iowa state line. C Climate Iowa’s climate is characterized by warm, generally moist summers and cold winters. Temperatures vary considerably from season to season and, at times, from day today. However, monthly averages are relatively uniform throughout the state and usually vary...

• Las Vegas (Nevada) - geography.

  way for the Paiute people. In the late 1820s early Spanish explorers searching for water discovered an oasis in the region that now contains the city. They named theoasis “Las Vegas,” Spanish for “the meadows.” These expanses of wetlands, once irrigated by artesian waters carried under pressure from the nearby mountain ranges,were a main draw to southern Nevada until the 1940s. Las Vegas was an important stop along the Old Spanish Trail between Santa Fe, New Mexico, and southern California for m...

• Statistics I INTRODUCTION Statistics, branch of mathematics that deals with the collection, organization, and analysis of numerical data and with such problems as experiment design and decision making.

  Professional pollsters typically conduct their surveys among sample populations of 1,000 people. Statistical measurementsshow that reductions in the margin of error flatten out considerably after the sample size reaches 1,000.© Microsoft Corporation. All Rights Reserved. The raw materials of statistics are sets of numbers obtained from enumerations or measurements. In collecting statistical data, adequate precautions must be taken tosecure complete and accurate information. The first problem of...

• Human Sexuality.

  About six weeks after conception, if a Y chromosome is present in the embryo's cells (as it is in normal males), a gene on the chromosome directs the undifferentiatedgonads to become testes. If the Y chromosome is not present (as in normal females), the undifferentiated gonads will become ovaries. If the gonads become testes, they begin to produce androgens (male hormones, primarily testosterone) by about eight weeks after conception. These androgens stimulate development of the one set of the...

• Sweden - country.

  mi) and is Sweden’s second largest lake, after Vänern. The two lakes, together with several smaller lakes, rivers, and canals, form an internal water route called theGöta Canal. Built in the early 19th century, the Göta Canal extends for about 386 km (about 240 mi) and provides a scenic transportation link between the Baltic Sea,at Stockholm, and the Kattegat. Sweden’s other large lakes in the district include Mälaren, Hjälmaren, and the famously picturesque Siljan. D Climate Although one-seven...

• Portland - geography.

  Garden arena, which opened in 1995. In 2000 the Portland Fire, an expansion Women's National Basketball Association team, began play in the Rose Garden as well. VI ECONOMY Portland enjoys a diversified economy. Major manufactured products include paper, transportation equipment, metal products, sportswear, and electronic componentsand equipment. Major corporations headquartered in the metropolitan region include Nike, a leader in the manufacture of sports footwear, in Beaverton; Louisiana-Paci...

• Houston - geography.

  Prominent historical and cultural institutions include the Civic Center Complex, located in the central business district. The complex is composed of the George R. BrownConvention Center; the Wortham Center, which is the home of the Houston Grand Opera and the Houston Ballet; and the Jesse H. Jones Hall for Performing Arts, whichis the home of the Houston Symphony. The nearby Alley Theatre houses a professional repertory acting company. Among other local professional performance groupsare the Ma...

• Zimbabwe - country.

  contamination—especially from the dieldrin and DDT used in tsetse fly control—has significantly affected wildlife and human health. III PEOPLE AND SOCIETY OF ZIMBABWE In 2008 Zimbabwe’s population was estimated to be 12,382,920, giving the country a population density of 32 persons per sq km (83 per sq mi). With a birth rate of27 per 1,000 and a death rate of 22 per 1,000, Zimbabwe’s population growth rate is 0.6 percent. Life expectancy at birth was estimated at 40 years in 2008, downfrom 59...

• 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...

• Iran - country.

  Zagros mountains. In the more arid central part of the country, wild pistachio and other drought-resistant trees grow in areas that have not been disturbed by humanactivity. Tamarisk and other salt-tolerant bushes grow along the margins of the Dasht-e Kavir. A wide variety of native mammals, reptiles, birds, and insects inhabit Iran. Many species of mammals—including wolves, foxes, bears, mountain goats, red mountainsheep, rabbits, and gerbils—continue to thrive. Others—including Caspian tigers,...

• 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...

• 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...

• Louisiana - geography.

  lakes are on the Red River and its tributaries. In addition, small oxbow lakes are numerous in the Mississippi Alluvial Plain. Oxbow lakes are formed when a river cutsthrough the neck of one of its loops, or meanders, thus establishing a shorter course and leaving the former loop as a lake separate from the river. Louisiana also hassome artificially created reservoirs. C Coastline Louisiana’s long and irregular coastline extends along the Gulf of Mexico from the Pearl River on the east to the S...

• Louisiana - USA History.

  lakes are on the Red River and its tributaries. In addition, small oxbow lakes are numerous in the Mississippi Alluvial Plain. Oxbow lakes are formed when a river cutsthrough the neck of one of its loops, or meanders, thus establishing a shorter course and leaving the former loop as a lake separate from the river. Louisiana also hassome artificially created reservoirs. C Coastline Louisiana’s long and irregular coastline extends along the Gulf of Mexico from the Pearl River on the east to the S...

• Italy - country.

  C Natural Resources Italy is poor in natural resources. Much of the land is unsuitable for agriculture because of mountainous terrain or unfavorable climate. Italy, moreover, lacks substantialdeposits of basic natural resources such as coal, iron, and petroleum. Natural gas is the country’s most important mineral resource. Other deposits include feldspar andpumice. Many of Italy’s mineral deposits on the islands of Sicily and Sardinia had been heavily depleted by the early 1990s. Italy is rich...

• Bill Clinton.

  When Arkansas governor David Pryor ran for the U.S. Senate in 1978, Clinton ran for governor. He promised to improve the state’s schools and highways and toimprove economic conditions so that more jobs would be created. At that time, the average income of people in Arkansas ranked 49th among the 50 states. Clinton woneasily, receiving 60 percent of the vote against four opponents in the Democratic primary election and 63 percent against the Republican candidate, Lynn Lowe, in thegeneral election...

• Bill Clinton - USA History.

  When Arkansas governor David Pryor ran for the U.S. Senate in 1978, Clinton ran for governor. He promised to improve the state’s schools and highways and toimprove economic conditions so that more jobs would be created. At that time, the average income of people in Arkansas ranked 49th among the 50 states. Clinton woneasily, receiving 60 percent of the vote against four opponents in the Democratic primary election and 63 percent against the Republican candidate, Lynn Lowe, in thegeneral election...

• Jakarta - geography.

  voluntary movement of families to Indonesia's less populated islands). Jakarta is a magnet for migrants from other areas of Indonesia; during the late 1980s an estimated 250 migrants arrived daily. Most were between the ages of 15 and39 years, many with six years of education or less. There is also a significant number of commuters and seasonal migrants who work in government, manufacturing,and services. In addition, many of these temporary residents are engaged in informal employment as drivers...

• Botswana - country.

  at birth was 50.2 years, also a significant improvement. The urban population of Botswana has increased rapidly, from 18 percent of the total in 1981 to 51 percent in 2003. Gaborone, the capital, is the largest city and mainbusiness center. Other business centers are Francistown, Selebi-Pikwe, Molepolole, Kanye, and Serowe. Botswana received its name from the country’s principal ethnic group, the Tswana. Other ethnic groups include the Kgalagadi, Kalanga, and Basarwa. There are also asmall numbe...