.... called Principles of chemistry (1868-1870), which later became a classic. These books included an improved version of the periodic table. Sir Joseph Thomson, another important person in the development of the atomic theory, was born in 1906. Thomson won the Nobel Prize in physics (1906) for his work in the conduction of electricty through gases. He discovered the electron by using cathode rays. An electron is the smallest particle of an atom, the charge on an electron is negative. Ernest Rutherford, who was born in 1871 identified the three main com .....

.... Although primarily an agricultural pest, this insect on occasion may invade the home for cereals. In the United States, the Texas leaf-cutting ant, Atta texana , occurs in Texas and Louisiana. This ant is believed to cause a total yearly loss of $5 million in the United States (unison services. 1998). There are about 9,500 named species of ants. These ants are divided into 16 sub families and 300 genera, all which belong to the family called Formicidae, the family of ants (Hoyt. 1996). The leaf cutting ant belongs to the genus called Atta. There are fifteen di .....

.... the government, and even parents and children have something to do with this vast new form of medicine. continues to grow every year, which makes it a very important issue in our society, in fact 40% of American use some form of herbal or other in the world today (Jonas). This fact just shows how widely used this method is. According to a survey of 1,539 adults in 1990 and 2,055 in 1997, use of at least one type of alternative therapy during the previous year jumped from 33.8 percent in 1990 to 42.1 percent in 1997 (Mann). These facts show just how fas .....

.... clone. 4. a population of identical cells arising from the culture of a single cell of a certain type, such as a human fibroblast or a rodent-human hybrid cell containing a full set of rodent chromosomes and a single human chromosome. Human embryo cloning starts with a standard in vitro fertilization procedure. Sperm and an egg cell are mixed together on a glass dish. After conception, the zygote (fertilized egg) is allowed to develop into a blastula (a hollow mass of cells). The zygote divides first into two cells, then four, then eight... A chemical is added .....

.... Some of these minerals are changed in to gases and others become tiny specks of ash. As these chemicals drift, they may change again. They may react with other chemicals in the air. When sulfur dioxide combines with water, the result is sulfuric acid. When nitrogen oxide gas combines with water, the result is also another acid. When the clouds releases rain or other precipitation, the acid goes with it. This is called acid rain. The level of acid is measured in pH levels. The pH scale begins at 0 and ends with 14. A reading lower than 7 is called .....

.... it’s first official flight on February 2, 1974. A level speed of Mach 2 at 40,000 ft was attained on March 11, 1974. The production F-16A differed from the YF-16 in having a 13-inch fuselage extension to hold more fuel and the Westinghouse APG-66 radar. The wing area was increased by 20 square feet and an additional underwing hardpoint was fitted. The first YF-16 was brought out on December 13, 1973 to make its first test flight at Fort Worth and was air freighted by C-5A to Edwards AFB on January 8, 1974. It was an unintended short hop around t .....

.... trees in danger and now they are starting to die off. The effects of acid rain on a tree is shown if it has less foliage, yellow spots and produces many cones (Baines, 22). Secondly, acid rain damages the trees through the soil by releasing metals that harm them even further (Lucas, 72). Acid rain makes the trees lose their leaves, so when the trees try to regrow their leaves, buds come instead, this process is called a panic shoot (M. 15). Large land areas which used to be covered with forests are now gone, dead or dying (Baines, 21). Aroun .....

.... tiredness, fever, loss of weight, diarrhea, and night sweats. AIDS is caused by two viruses that belong to a group called retroviruses. The virus became known as HIV-1. In 1985, scientists in France identified another closely related virus that produces AIDS. This such virus became known as HIV-2 and occurs mainly just in Africa. The virus,HIV-1 is spread throughout the world . HIV infects certain white blood cells, including T-helper cells and macrophages, that play key roles in the functioning of the human immune system. The virus attaches to .....