.... e Hidrógeno (comúnmente presentes en el aire). Por mucho tiempo se les usó como pesticida, pero ya dejaron de ser efectivas pues algunas clases de insectos, lograron transformarse para que las dioxinas no surgieran un efecto mortífero en ellos y por tanto dejaron de ser efectivas. Esto llevó a que por algún tiempo (y en la actualidad en pocos lugares en donde todavía se usa este tipo de pesticida), las dioxinas llegaron hasta nosotros no solo por el aire sino que directamente por los alimentos. Son lipofílicos, es decir solubles en las grasas y sus moléculas están unidas por enlaces fuertes que les dan una vida media entre los 7 y los .....

.... 1943 through 1946 several studies concluded that available rockets would be unable to place a satellite into orbit. Work on rockets for missiles and upper atmosphere research was so great after World War II that by 1954 the possibility of launching a satellite was no longer in serious doubt. In October 1954 the Committee for the International Geophysical Year (IGY), announced to other countries that they were considering launching small satellite vehicles for space exploration. In April and again in July 1955 the USSR and the U.S. announced plans to launch for the IGY. The USSR launched SPUTNIK 1 on Oct. 4, 1957, and the United States launched .....

.... have enabled suffers to survive into adulthood. Research into the cause of reads like a detective story. One clue is that patients have excess amounts of sodium and chloride in their sweat making it vey salty . At the University of North Carolina researchers found that salt imbalance caues thick mucus to accumulate in the patients lungd. High level of salt in lung cells draw water out of the mucus causing it to thicken.The level of salt in a cell is determained by the movement of ions across the cell membrane.Ions are carried across call memebranes by protein channels embedded in the cell membrane. Since the stucture and functions of proteins ar .....

.... even cancers" (D4). In 1948, in the industrial town of Donora, Pennsylvania, which sits in a valley, had twenty deaths, and nearly 6,000 residents, or 40% of the population, suffered respiratory problems (Edelson 25, 26). New York experienced several killer smogs, which in a later analysis attributed, from the usually severe pollution, 58 deaths (Edelson 26). Not only in the United States are health problems caused by air pollution showing up, but they are also showing up in other parts of the world, like Europe. In 1930, in Belgium's Meuse River valley, a major industrial region, where the primary fuel was coal reported sixty deaths, and about .....

.... the prohibition, marijuana was widely used because of the scarcity of alcohol. Prohibition was repealed after just thirteen years while the prohibition against marijuana lasted for more than seventy five years. This double standard may have resulted from the wishes of those in power. Alcohol prohibition struck directly at tens of millions of Americans of all ages, including many of societies most powerful members. Marijuana prohibition threatened far fewer Americans, and they had relatively little influence in the districts of power. Only the prohibition of marijuana, which some sixty million Americans have violated since 1965 has come close to app .....

.... whole nation found out, nobody is immortal. By examining this further, we will look at the lives of the seven who died in this dumbfounding calamity, take a look at exactly what went wrong during this fateful mission, and the outcome from this sorrowful occurrence. First, who exactly were those astronauts that died on the Challenger? Sharon Christa Corrigan McAuliffe, born in 1948, was the famous winner of the teacher-in-space program, was a high school teacher at Concord, N. H., a wife, and a mother of two children. She touched the lives of all those she knew and taught. As a school official in Concord said after her death, "To us, she seemed av .....

.... of carbon dioxide by replacing old-growth forests with faster-growing young trees". A new study of young and old forests says how this is in fact not true. Loggers have said that new trees pull the carbon dioxide better than old trees, and this may seem true, but it is not. There is one point being overlooked from all of this. The older, larger trees can store much, much more carbon dioxide than a new tree could. By cutting and burning these magnificent seasoned trees, the CO2 is being released back into the atmosphere. These releases of carbon dioxide add up in our surroundings, only to intensify Global Warming. Although this shows what happe .....

.... hit land they begin to lose speed and die off due to friction. In the Northern Hemisphere usually travel first in a northwestern direction and in the higher latitudes turn toward the northeast. In the Southern Hemisphere the usual path of a hurricane is first to the southwest and then turning toward the southeast. are characterized by strong winds and pouring rain. Thunderstorms and waterspouts appear in the storm's cloud system. All contain an eye. The eye of a hurricane is a low pressure, calm area in the middle of the storm. The air in the eye is sinking and this causes there to be no rain in this area and little wind. This gives the im .....

.... As pathogen numbers increase, so does the risk of human health. Biochemical Oxygen Demand: Organic wastes that decay in a body of water. decrease the amount of oxygen found in it. The living things in the lake need oxygen to survive. If the oxygen level is depressed to zero, all fish in the lake die. Any decomposition that does not contain oxygen starts to generate noxious gases such as Hydrogen Sulfide. Pulp and paper mills, and municipal sewage causes BOD. Nutrients: Nutrients, particularly nitrogen and phosphorus, enrich waters and accelerate the aging of lakes and streams. Also, the result of this is rich plant life which prohibits recreat .....

.... video and data transmission in digital form, to be sent and received by a customer. Unlike stand alone services such as telephone, telex, fax and data communications, ISDN is a network which can offer all these services as a package in which a user can talk, exchange data, faxes and other documents at the same time, instead of having to use different networks for these services. 3. What is Satellite Communications? This is the use of orbiting satellites to relay microwave transmissions from earth stations to the satellite an to re-transmit those signals back down to another earth station by means of microwave transmission. Cellular Radio At .....