24 résultats pour "clean"

• 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...

• Water Pollution.

  Cryptosporidium in the water supply of Milwaukee, Wisconsin, sickened more than 400,000 people and killed more than 100. H Thermal Pollution Water is often drawn from rivers, lakes, or the ocean for use as a coolant in factories and power plants. The water is usually returned to the source warmer than when itwas taken. Even small temperature changes in a body of water can drive away the fish and other species that were originally present, and attract other species in placeof them. Thermal pol...

• Acid Rain.

  the Adirondack Mountains of New York State, a quarter of the lakes and ponds are acidic, and many have lost their brook trout and other fish. In the middleAppalachian Mountains, over 1,300 streams are afflicted. All of Norway’s major rivers have been damaged by acid rain, severely reducing salmon and trout populations. E Plants and Animals The effects of acid rain on wildlife can be far-reaching. If a population of one plant or animal is adversely affected by acid rain, animals that feed on tha...

• Conservation.

  cancers, Hodgkin’s disease and leukemia. Unfortunately, human activities have greatly reduced biodiversity around the world. The 20th century encompasses one of the greatest waves of extinction, orelimination of species, to occur on the planet. The greatest threat to biodiversity is loss of habitat as humans develop land for agriculture, grazing livestock, industry,and habitation. The most drastic damage has occurred in the tropical rain forests, which cover less than seven percent of the Earth’...

• VIOLENCE : La violence Offences : les délits To have a clean

  D elinquency : la délinquance A vandal : un vandale A n outbreak o f violence : une explosion de violenceRivalries between : des rivalités entre A gang : un gang Juvenile delinquancy : la délinquance juvénile I n the su burbs : dans les banlieues High une mploymen t : un chômage élevé Sociological factors : des facteurs sociologiques Social inequalities : les inégalités sociales Poverty : la pauvreté To have no m oral values : ne pas avoir de v...

• Hazardous Wastes.

  A Source Reduction The best way to eliminate hazardous wastes is not to generate them in the first place. For example, improvements have been made in the production of integratedcircuits: The toxic chlorinated hydrocarbons commonly used in the 1970s were replaced in the 1980s by less toxic glycol ethers and in the 1990s by low-toxicity estersand alcohols. B Recycling Recycling is the recovery or reuse of usable materials from waste. About 5 percent of hazardous waste in the United States is re...

• First Aid.

  IV SEVERE BLEEDING The presence of blood over a considerable area of a person’s body does not always indicate severe bleeding. The blood may ooze from multiple small wounds or besmeared, giving the appearance of more blood than is actually present. The rate at which blood is lost from a wound depends on the size and kind of blood vesselruptured. Bright red, spurting blood indicates injury to an artery while welling or steadily flowing, dark red blood indicates injury to a vein. Welling or spur...

• Bacteria - biology.

  A2 b Bacterial Killers Some dramatic infectious diseases result from exposure to bacteria that are not part of our normal bacterial community. Cholera, one of the world’s deadliest diseasestoday, is caused by the bacterium Vibrio cholerae . Cholera is spread in water and food contaminated with the bacteria, and by people who have the disease. After entering the body, the cholera bacteria grow in the intestines, often along the surface of the intestinal wall, where they secrete a toxin (poiso...

• de l'agence a été un peu... hum... abrupt.

  moi que çan’a faitque déplacer ausud delafrontière lapartie production duproblème. Etc’est là-bas qu’ilsont besoin deblouses blanches. Pasici.Nos amis mexicains dirigentauMexique dessuperlaboratoires capables de fournir chacun centcinquante àdeux cents kilosdemeth parjour. Par jour . C’est beaucoup etça demande du savoir-faire. Alors,quand ilsmettent lamain suruncrack enchimie quipeut rationaliser leurproduction et obtenir unproduit demeilleure qualitésansfaireexploser leurslabos, ilsne lelaisse...

• Robot.

  V IMPACT OF ROBOTS Robotic manipulators create manufactured products that are of higher quality and lower cost. But robots can cause the loss of unskilled jobs, particularly on assemblylines in factories. New jobs are created in software and sensor development, in robot installation and maintenance, and in the conversion of old factories and the designof new ones. These new jobs, however, require higher levels of skill and training. Technologically oriented societies must face the task of retra...

• Dentistry.

  Together with dentists, dental hygienists and dental assistants make up the team that provides dental care to patients. Hygienists record patient medical histories, suchas blood pressure and pulse. They clean teeth, apply sealants and fluoride treatments, teach patients sound oral hygiene practices, and often assist with X rays. Manyhygienists receive a two-year associate degree, while others may choose to enroll in a four-year program at a university or in a master’s degree program. There are25...

• Learning.

  B1 Acquisition The acquisition phase is the initial learning of the conditioned response—for example, the dog learning to salivate at the sound of the bell. Several factors can affect the speed of conditioning during the acquisition phase. The most important factors are the order and timing of the stimuli. Conditioning occurs most quickly when theconditioned stimulus (the bell) precedes the unconditioned stimulus (the food) by about half a second. Conditioning takes longer and the response is...

• George Herbert Walker Bush.

  Lebanon. More troubling was the disclosure that agents operating under direct White House supervision used profits from the arms sales to buy weapons for thecontras, a group of anti-government Nicaraguan rebels, despite an explicit congressional ban on such aid. Bush later claimed that he opposed the arms-for-hostagesdeal, but offered little evidence to back his claims ( see Iran-Contra Affair). C 1988 Presidential Election While the Reagan-Bush program helped produce prosperity for the wealth...

• George Herbert Walker Bush - USA History.

  Lebanon. More troubling was the disclosure that agents operating under direct White House supervision used profits from the arms sales to buy weapons for thecontras, a group of anti-government Nicaraguan rebels, despite an explicit congressional ban on such aid. Bush later claimed that he opposed the arms-for-hostagesdeal, but offered little evidence to back his claims ( see Iran-Contra Affair). C 1988 Presidential Election While the Reagan-Bush program helped produce prosperity for the wealth...

• World Energy Supply.

  In the 1990s, oil production by non-OPEC countries remained strong and production by OPEC countries rebounded. The result at the end of the 20th century was aworld oil surplus and prices (when adjusted for inflation) that were lower than in 1972. Experts are uncertain about future oil supplies and prices. Low prices have spurred greater oil consumption, and experts question how long world petroleum reservescan keep pace with increased demand. Many of the world’s leading petroleum geologists beli...

• Art Deco I INTRODUCTION Art Deco Historic District The Art Deco Historic District is located at the southern end of Miami Beach, Florida.

  At the 1925 exposition several French masters unveiled work that created an international stir. Elegant inlaid wood furniture by Jacques Émile Ruhlmann, functionallacquerwork by Jean Dunand, silver jewelry by Jean Puiforcat, and glass vases by Lalique were hailed for their modernity and original lines. Ruhlmann designed a seriesof rooms for the exposition that had a far-reaching effect on American and European taste. Lalique later created a similarly streamlined decorative scheme for theluxuriou...

• Microprocessor.

  thin layer of oxide about 75 angstroms deep (an angstrom is one ten-billionth of a meter). Nearly every layer that is deposited on the wafer must be patterned accurately into the shape of the transistors and other electronic elements. Usually this is done in aprocess known as photolithography, which is analogous to transforming the wafer into a piece of photographic film and projecting a picture of the circuit on it. A coatingon the surface of the wafer, called the photoresist or resist, changes...

• Lifehack

• 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...

• Dog - biology.

  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...

• Fossil Fuels.

  water molecules. This crystalline solid is known as gas hydrate. Because technology for the commercial extraction of gas hydrates has not yet been developed, this typeof fossil fuel is not included in most world energy resource estimates. However, in February 2007 the U.S. Department of Energy completed the drilling of a well toretrieve core samples of gas hydrates found in the Prudhoe Bay region of Alaska’s North Slope. By identifying the nature of these gas hydrates, the Energy Departmenthoped...

• Cat. I INTRODUCTION Cat, small, mainly carnivorous animal, Felis silvestris catus, member of

  D Coat Colors The domestic cat's original coat color was probably grayish-brown with darker tabby stripes, a color that provides excellent camouflage in a variety of environments. Allother coat colors and patterns are the result of genetic mutations; for example, solid coat colors such as black and blue are the result of a gene that suppresses tabbystripes; an orange coat is the result of a gene that transforms black pigment to orange; and a solid white coat is the result of a gene that complet...

• Cat - biology.

  D Coat Colors The domestic cat's original coat color was probably grayish-brown with darker tabby stripes, a color that provides excellent camouflage in a variety of environments. Allother coat colors and patterns are the result of genetic mutations; for example, solid coat colors such as black and blue are the result of a gene that suppresses tabbystripes; an orange coat is the result of a gene that transforms black pigment to orange; and a solid white coat is the result of a gene that complet...

• Prints and Printmaking I INTRODUCTION Prints and Printmaking, pictorial images that can be inked onto paper, and the art of creating and reproducing them.

  Bewick’s The SkylarkBritish engraver Thomas Bewick’s The Skylark is part of his History of British Birds (2 vols., 1797 and 1804). Bewick wasthe first artist to demonstrate the full potential of wood engraving and is renowned for his fine natural history illustrations.Each illustration shows some of the bird’s natural habitat.Folio Society, London/Bridgeman Art Library, London/New York Historically, the wood engraving was chiefly used for illustrations in magazines and books. It is similar to th...