Despite the overwhelming abundance of water on the planet and in our lives, the molecular structure of water has remained a mystery.

In all, water exhibits 66 known anomalies, including a strangely varying density, large heat capacity and high surface tension. Contrary to other "normal" liquids, which become denser as they get colder, water reaches its maximum density at about 4° Celsius. Above and below this temperature, water is less dense; this is why, for example, lakes freeze from the surface down.

Water also has an unusually large capacity to store heat, which stabilizes the temperature of the oceans, and a high surface tension, which allows insects to walk on water, droplets to form and trees to transport water to great heights.

There are many hypotheses about the early days of black holes.  Researchers writing in The Astrophysical Journal Letters have undertaken simulations using data taken from observations of the cosmic background radiation—the earliest view of the structure of the universe - and then applied the basic laws that govern the interaction of matter. In doing so, they say they have allowed the early universe in their simulation to evolve as they believe it did in reality.

Acupuncture has been used in East-Asian medicine for thousands of years to treat pain and some people swear by it, but if and how it works at the cellular level is largely unknown.

Using brain imaging, a University of Michigan study says they have evidence that traditional Chinese acupuncture affects the brain's long-term ability to regulate pain by activating the body's natural painkillers. 

Acupuncture needs a boost due to recent controversy over large studies showing that sham acupuncture is as effective as real acupuncture in reducing chronic pain. 

If you're the family member of a critical care patient, you prefer doctors to keep their opinions on life support decisions to themselves, according to new research that challenges a long-held belief in the critical care community that caregivers want advice on the matter . 

The research found that surrogates are virtually split when it comes to how much guidance they want to receive from physicians in making end-of-life medical choices on behalf of critically ill patients, according to lead author of the paper, Douglas B. White, of the University of Pittsburgh Medical Center.

A group of University of Utah scientists say they developed a "molecular condom" that could help protect women against AIDS in Africa and other impoverished areas.

It's a vaginal gel that turns semisolid in the presence of semen, trapping AIDS virus particles in a microscopic mesh so they can't infect vaginal cells.

A study testing the behavior of the new gel and showing how it traps AIDS-causing HIV particles will be published online later this week in the journal Advanced Functional Materials.

The sex hormone estrogen tempers the killing activity of immune cells called cytotoxic T cells (CTLs), which are known to attack tumor cells and cells infected by viruses.

Estrogen plays a critical role in the regulation of growth and the development of cells and is also crucial for cell-type-specific gene expression in various tissues. Deregulation of this system results in breast and ovarian cancer.  The key player in this process is a cytotoxic T cell molecule known as EBAG9.

Breast and ovarian tumors are treated with drugs such as tamoxifen. Researchers suggest that this drug inhibits tumor growth by blocking the estrogen receptors of the tumor cells. However, up to now it has been unclear what effect this inhibition has on the immune system.