New scientific findings suggest that a large comet may have exploded over North America 12,900 years ago, explaining riddles that scientists have wrestled with for decades, including an abrupt cooling of much of the planet and the extinction of large mammals.

The discovery was made by scientists from the University of California at Santa Barbara and their colleagues. James Kennett, a paleoceanographer at the university, said that the discovery may explain some of the highly debated geologic controversies of recent decades.

The period in question is called the Younger Dryas, an interval of abrupt cooling that lasted for about 1,000 years and occurred at the beginning of an inter-glacial warm period.

NASA's Galaxy Evolution Explorer has spotted an amazingly long comet-like tail behind a star streaking through space at supersonic speeds. The star, named Mira after the Latin word for "wonderful," has been a favorite of astronomers for about 400 years. It is a fast-moving, older star called a red giant that sheds massive amounts of surface material.

The space-based Galaxy Evolution Explorer scanned the popular star during its ongoing survey of the entire sky in ultraviolet light. Astronomers then noticed what looked like a comet with a gargantuan tail. In fact, material blowing off Mira is forming a wake 13 light-years long, or about 20,000 times the average distance of Pluto from the sun.

For the first time, findings by scientists at the Genome Institute of Singapore (GIS) may be paving the way for more efficient analyses and tests related to the replication of cells, and ultimately, to the better understanding of human biology, such as in stem cell research.

Faithful duplication of the genome (the hereditary information that is encoded in genetic materials known as DNA) ensures that daughter cells inherit a complete set of genetic materials identical to parent cells. This duplication occurs in the section of the cell cycle known as the S-phase. Extensive research on the budding yeast, an organism often used in modern cell biology research, had revealed that the replication process is initiated at hundreds of origins in the S-phase.

Nerve cells must perform millions of neuronal processes and form connections between them during embryonic development to ensure that the nervous system will function properly. Dr. Marta Rosário and Prof. Walter Birchmeier from the Max Delbrück Center for Molecular Medicine (MDC) Berlin-Buch (Germany), a member of the Helmholtz-Association of National Research Centres, have discovered a novel regulator which is crucial for this process and which they named NOMA-GAP (Neurite-Outgrowth MultiAdaptor RhoGAP).

They show that NOMA-GAP is essential for the function of the nerve growth factor (NGF), itself a crucial factor for the functioning of the nervous system and for nerve cell survival.

Mayo Clinic researchers have identified the first immune molecule that appears to play a role in prostate cancer development and in predicting cancer recurrence and progression after surgery. The report on the B7-H3 molecule by Mayo Clinic Cancer Center appears today in Cancer Research.

“This discovery will allow physicians to individualize treatment and observation plans for prostate cancer patients,” says Timothy Roth, M.D., a Mayo Clinic urology resident and lead author of the study. “Being able to tell a patient his specific risk after surgery, and perhaps even prior to surgery, will be a huge step forward.”

A prominent problem in AIDS is a form of dementia that robs one’s ability to concentrate and perform normal movements. Scientists at the Burnham Institute for Medical Research (Burnham) have discovered how HIV/AIDS disrupts the normal replication of stem cells in the adult brain, preventing new nerve cells from forming.

Drs. Stuart Lipton, Marcus Kaul, Shu-ichi Okamoto and their colleagues uncovered a novel molecular mechanism that inhibits stem cell proliferation and that could possibly be triggered in other neurodegenerative diseases as well.

A normally functioning adult human brain has the ability to partially replenish or repair itself through neurogenesis, the proliferation and development of adult neural progenitor/stem cells (aNPCs) into new nerve cells.

Movies such as Spiderman 2 and Speed generate excitement among audiences with their cool special effects. But they also defy the laws of physics, contributing to students’ ignorance about science.

Two University of Central Florida professors show just how poorly Hollywood writers and directors understand science in an article published in the German journal “Praxis der Naturwissenschaften Physik.” Common sense may indicate that people should know the stunts in movies are just make believe, but the professors say that’s not necessarily true.

Some people really do believe a bus traveling 70 mph can clear a 50-foot gap in a freeway, as depicted in the movie Speed.

Antibacterial soaps show no health benefits over plain soaps and, in fact, may render some common antibiotics less effective, says a University of Michigan public health professor.

In the first known comprehensive analysis of whether antibacterial soaps work better than plain soaps, Allison Aiello of the U-M School of Public Health and her team found that washing hands with an antibacterial soap was no more effective in preventing infectious illness than plain soap. Moreover, antibacterial soaps at formulations sold to the public do not remove any more bacteria from the hands during washing than plain soaps.

While studying the mechanisms of development in shark embryos, University of Florida scientists identified genetic activity that is required for digit development in limbed animals.

Previous work suggested that the transition from fins to limbs involved the addition of a late phase of gene activity during embryonic development, something thought to be absent during the development of fish fins.

The finding shows what was thought to be a relatively recent evolutionary innovation existed eons earlier than previously believed, shedding light on how life on Earth developed and potentially providing insight for scientists seeking ways to cure human birth defects, which affect about 150,000 infants annually in the United States.