.... the history and the process of growth and change. It aids in learning about human evolution. Tetrapods are creatures with four limbs, hips, shoulders, fingers, and toes, which developed sometime after lobe-finned fish, and before the first fully terrestrial vertebrates. The earliest tetrapod known is Acanthostega. It is also considered the most primitive tetrapod. It is very close to its fish ancestry, but still anatomically far from its terrestrial relatives. These creatures still lived in water, but they had a lot of the terrestrial tetrapod anatomical characteristics. Introduction: Before tetrapods existed, all vertebrates were confined to living in aquatic habitats. ....

.... and astronomers have made up over the past 6,000 years (and probably even more!). The real purpose for the is to help us tell which stars are which, nothing more. On a really dark night, you can see about 1000 to 1500 stars. Trying to tell which is which is hard. The help by breaking up the sky into more manageable bits. They are used as mnemonics, or memory aids. For example, if you spot three bright stars in a row in the winter evening, you might realise, "Oh! That's part of Orion!" Suddenly, the rest of the constellation falls into place and you can declare: "There's Betelgeuse in Orion's left shoulder and Rigel is his foot." And once you recognise Orion, you can remembe ....

.... hole was created by man made substances. These substances are chlorofluorocarbons (CFC's). CFC's are found to be emitted into the atmosphere by solvents, refrigerators, and spray can propellants mainly in the Northern Hemisphere. CFC's disperse throughout the stratosphere and breakdown to release chlorine. Chlorine by itself is a very stable compound, but when in the stratosphere it binds to and destroys ozone. This is a cyclic process and therefor means that one chlorine can destroy many ozone molecules (Figure 1.2) During the winter in the Antarctic the circumpolar vortex, which is a strong westerly circulation around the continent, builds in the stratosphere. This ph ....

.... ones produced around 1900. In the later twentieth century people developed a increasing "need" for pure gold and silver. European and American scientists developed a new advanced way for this- amalgams. Amalgams are alloys of mercury usually used to extract elements from there various ores. Then, once the common metal is extracted mercury is then separated through distillation. Without mercury our world would be much different. We would have different, if any, ways of determining temperature. Mercury is also used in cleaning modern day swimming pools as "Mercury Vapor lamps" for sterilization. Mercury can be used in both reconstructing and destroying life in water ways de ....

.... for the existence of insurance companies is a single word, profit. More specifically, premiums less costs provide the all important profit margin, the life blood of the insurance industry. By not providing coverage for the billion dollar industry of alternative treatments, insurance companies are keeping the cost of the premiums down but at the same time not allowing their customers to use complementary treatments such as chiropractic to prevent or cure illness. The more rigid and restrictive the policy provisos, the more assurance for the companies that they will maximize their bottom lines. Therefore, patients of alternative therapies as well as doctors must sho ....

.... interest can be traced to the truly strange nature of quantum mechanical ideas. Quantum physics amounts to much more than a theory of atomic and subatomic processes, it represents nothing less than a complete transformation of our world view. "Its [quantum physics] implications for the nature of reality and the relationship between observer and observed are both subtle and profound. (Barenco)" A description of the world in which an object can apparently be in more than one place at the same time, in which a particle can penetrate a barrier without breaking it, in which something can be both a wave and a particle, and in which widely separated particles can cooperate in an ....

.... in a daily brisk walk of 30 to 60 minutes (Cufman, 1993). Moderate regular exercise, lasting say 15 to 30 minutes, five times a week also has been found to improve health. In fact, high levels of exercise increase the risk of injuries (Edlin p.130 ). If you exercise regularly, your overall risk of a heart attack is about 50 percent less than if you are inactive and out of shape. With routine exercise you can reach a level of physical fitness comparable to an active person ten to twenty years younger. Regular exercise may also lower your cholesterol and blood pressure, and reduce the risk of diabetes. Exercise increases the size of coronary arteries and reduce clogging due ....

.... object's motion. In the case of a falling object, air resistance pushes up as pulls down, which causes the object to slow down. When Galileo's experiment was repeated on the moon, the hammer and the feather hit the ground at the exact same time. This is due to the fact that the moon has no atmosphere. Therefore, air resistance doesn't exist on the moon. Also, the amount of air resistance on an object depends on the speed, size, shape, and density of the object. The larger the surface area of the object, the greater the amount of air resistance on it. This is why feathers, leaves, and sheets of paper fall more slowly than pennies, acorns, and crumpled balls of paper. The ....