While trying to develop a vaccine for AIDS, researchers have uncovered a biological catch-22 that's been hindering their chances of success. They say that while the immune system can produce cells with the potential to manufacture HIV-blocking antibodies, it also works equally hard to eliminate those cells before they have a chance to mature.

Over the years, scientists have assumed that B cells – one of the first lines of defense against infection – are simply not able to "see" the HIV virus. HIV has the ability to hide its most vulnerable parts from immune system surveillance, and researchers generally assumed that
helped explain why B cells often took weeks and even months to arise following infection.

Many studies have shown, and common sense dictates, that good looks greatly benefit those who have them. Prettier people tend to have more social relationships, and reap the psychological benefits as a result. What may not be so widely known, however, is that the relevance of physical appearance varies based on geography.

According to a study published in Personal Relationships, The importance of attractiveness depends on the social environment where we live. Attractiveness does matter in more socially mobile, urban areas (and from a woman's point of view actually indicates psychological well-being), but it is far less relevant in rural areas.

Analysis of microfossils found in ocean sediment cores is illuminating the environmental conditions that prevailed at high latitudes during a critical period of Earth history.

Around 55 million years ago at the beginning of the Eocene epoch, the Earth's poles are believed to have been free of ice. But by the early Oligocene around 25 million years later, ice sheets covered Antarctica and continental ice had developed on Greenland.

In a pilot project that could help better manage the planet's strained natural resources, NASA satellites and sensors are providing a local Washington community the information needed to make more accurate river flow predictions on a daily basis, helping them manage their water availability .

"World leaders are struggling to protect natural resources for future generations," said Jeff Ward, a senior research scientist at the Department of Energy's Pacific Northwest National Laboratory. "These tools help us sustainably use natural resources while balancing environmental, cultural and economic concerns."