Chance events may profoundly shape history. What if Franz Ferdinand's driver had not taken a wrong turn, bringing the Duke face to face with his assassin? Would World War I still have been fought? Would Hitler have risen to power decades later?

UCLA researchers led by Dr. Brigitte Gomperts have discovered the inner workings of the process thought to be the first stage in the development of lung cancer. Their study explains how factors that regulate the growth of adult stem cells that repair tissue in the lungs can lead to the formation of precancerous lesions.

HIV-1, the virus responsible for most cases of AIDS, is a very selective virus. It does not readily infect species other than its usual hosts – humans and chimpanzees. While this would qualify as good news for most mammals, for humans this fact has made the search for effective treatments and vaccines for AIDS that much more difficult; without an accurate animal model of the disease, researchers have had few options for clinical studies of the virus.