Male and female brains operate differently at a molecular level, according to a new study of a brain region involved in learning and memory and responses to stress and epilepsy.

Many brain disorders vary between the sexes, but how biology and culture contribute to these differences has been unclear. The neuroscientists found an intrinsic biological difference between males and females in the molecular regulation of synapses in the hippocampus. This provides a scientific reason to believe that female and male brains may respond differently to drugs targeting certain synaptic pathways.

The crucial genetic mashup that spawned the yeast that brews the vast majority of beer occurred at least twice -- and both times without human help -- according to a new study.

 More than 2.7 million people in the United States are infected with the hepatitis C virus, according to estimates from the Centers for Disease Control and Prevention, and people infected with the hepatitis C virus are at risk for liver damage, but the results of a new Johns Hopkins study now show the infection may also bring heart trouble.

Gang slayings move in a systematic pattern over time, spreading from one vulnerable area to the next like a disease, according to a paper by Michigan State University criminologists and public health researchers. That means there is a threshold where herd immunity takes effect, just like vaccines, but letting too many people opt out risks the whole community.

There were 2,363 gang-related killings in the United States in 2012, the highest number in at least six years, according to the latest available estimates from the Department of Justice. Gang membership also increased, to 850,000 in 2012 from 788,000 in 2007.

If you care about the environment, you should eat the steak and throw out the salad, according to University of Missouri researchers who say that the type of food wasted has a significant impact on the environment. 

Approximately 31 percent of food produced in the U.S., or 133 billion pounds of food worth $162 billion, was wasted in 2011 according to the United States Department of Agriculture (USDA).

It's an old joke: Practical nuclear fusion power plants are just 30 years away -- and always will be.

Maybe sooner, this time. Advances in magnet technology have led researchers at MIT to propose a new design for a practical compact tokamak fusion reactor that might be realized in as little as a decade, they say. Practical fusion power, should it ever happen, could offer a nearly inexhaustible energy resource.

The key is new commercially available superconductors, rare-earth barium copper oxide (REBCO) superconducting tapes, to produce high-magnetic field coils "just ripples through the whole design," says Dennis Whyte, a professor of Nuclear Science and Engineering and director of MIT's Plasma Science and Fusion Center. "It changes the whole thing."