.... May (1994) and Antia et al. (1993) predict the modulation of virulence in parasite-host systems by integrating evolutionary and transmissibility factors. INTRODUCTION Why do certain parasites exhibit high levels of virulence within their host populations while others exhibit low virulence? The two prime factors most frequently cited (Esch and Fernandez 1993, Toft et al. 1991) are evolutionary history and mode of transmission. Incongruently evolved parasite-host associations are characterized by high virulence, while congruent evolution may result in reduced virulence (Toft et al. 1991). Parasites transmitted vertically (f .....

.... Many people were misdiagnosed due to the similarities between these diseases, and the fact that they can occur in milder or more sever forms leading to an overlap of the most obvious symptoms. (7) Chickenpox mostly occurs in children classifying it as a childhood disease although it can occur in adults who are not yet immune to it. This could lead to the belief of chickenpox being one of the oldest diseases. Since the chickenpox infection has two phases, one most common during childhood then a latent form that can become active again later in the persons life, doctors believe that this reactivation would start the cycle all over again. If eve .....

.... the energy that leaves, botteling heat like the glass panels of a greenhouse. Without this natural "greenhouse effect," temperatures would be alot lower than they are now, and life like today would not work. Instead, thanks to greenhouse gases, the earth's average temperature is better, 60°F. But, problems may happen when the amount of greenhouse gases increases. Since the beginning of the industrial revolution, great amounts of carbon dioxide have increased nearly 30%, methane concentrations have almost doubled, and nitrous oxide concentrations have risen about 15%. These increases have made the heat-trapping worse in the eart .....

.... for applied genetics. In 1929 practically no hybrid corn was grown among the 100 million acres of corn in the United States. But by 1970 the vast majority of 67 million acres was planted with the hybrid variety, yielding twice as much corn. Plant breeders have a definite advantage over animal breeders, because they can often produce fertile varieties - indeed, new species - by crossbreeding between species. This is because hybrids are often polypoid. Polyploidy, as we know, can occur naturally in the wild. Some species of cotton that we grow are polypodies that probably arose originally by accidental crosses between different species of co .....

.... percent of the common diseases killing Americans can be prevented by a responsible lifestyle and diet. Drug testing on animals is not accurate and has no advantage to animals or people. Animals including dogs, cats, mice, pigs, monkeys, horses, deer, and cattle are commonly used for these senseless experimentations. The other remaining misfortunate animals come from places a little closer to you and me. Some of them come from animal shelters, some from the “free to a good home” ads in the newspaper, or, even worse, some have been stolen directly from their own yard. Imagine your pet being crammed into a cage with ten other animals .....

.... his tentacle to take a mass of spermatophore from within his mantle cavity, he then inserts it into the oviduct, in the mantle cavity of the female. This process occurs at depths from 20-100m and, lasts hours. With female octopuses receiving spermatophore up to 1m long. Female octopus seem to prefer larger males as mates and male octopus may mate with more than one female in their life span, however the male octopus only lives a few months after breeding, and the female will die shortly after the eggs hatch. Incubation can take from 150 days to seven or more months. The female may produce any where from 20,000 to 100,000 eggs over a p .....

.... large numbers of children were being diagnosed with juvenile rheumatoid arthritis in Lyme and two neighboring towns. The investigators discovered that most of the affected children lived near wooded areas likely to harbor ticks. They also found that the children's first symptoms typically started in the summer months coinciding with the height of the tick season. Several of the patients interviewed reported having a skin rash just before developing their arthritis, and many also recalled being bitten by a tick at the rash site. Further investigations resulted in the discovery that tiny deer ticks infected with a spiral-shaped bacterium or spir .....

.... had been cloned in this way ("Clone"). The scientist who started cloning is Ian Wilmut (who led the group) (Recer). He cloned Dolly using the nucleus from the cell of its mother, and it had an exact genetic replica of its mother. This spurred arguments about cloning humans (Recer). After Wilmut hinted he may be repeating his experiment to silence the critics (Recer). Wilmut does not have the courage to repeat his experiment, also that the government will never allow him to repeate it. Another reason for cloning is that before it was done and even now scientists think cloning could help produce genetic models of human diseases. With this researche .....

.... American College of Cardiology that one drink a day can help lower the risk of heart disease. But when consumption surpasses two drinks a day, risks increase for some kinds of cancer. Doctors at UT Southwestern Medical Center at Dallas say before you start drinking for your health, talk to your doctor. For some people, the risks of alcohol outweigh the benefits. And remember that while one drink a day can be helpful, more can be harmful. Could a drink a day keep the doctor away? One study says alcohol can have beneficial effects. Doctors recently determined that people who drank moderately, about one or two drinks per day, had a lower chance of deve .....

.... and into Great Britain. Soviet statements indicated that 31 people died because of the accident, but the number of radiation-caused deaths is still unknown. The same deadly radiation that was present in this explosion is also present in spent fuels. This presents special problems in the handling, storage, and disposal of the depleted uranium. When nuclear fuel is first loaded into a reactor, 238U and 235U are present. When in the reactor, the 235U is gradually depleted and gives rise to fission products, generally, cesium (137Cs) and strontium (90Sr). These waste materials are very unstable and have to undergo radioactive disintegration be .....