Jon Hamilton

The letters O-C-D have become a punch line to describe people who make lists or wash their hands a lot. But for some people with obsessive-compulsive disorder, the intrusive thoughts and rituals are severely disabling and don't respond to drugs or behavioral therapies.

So doctors have been trying a new treatment for OCD: deep brain stimulation.

Deep brain stimulation is best known as a way to reduce the tremors of Parkinson's disease. A surgeon places wires deep in the brain that carry electrical impulses from an implanted device a bit like a pacemaker.

A experimental device that delivers electrical pulses to the forehead can help control epileptic seizures, say scientists at the University of California, Los Angeles.

The device works by stimulating the trigeminal nerve, which runs just beneath the skin covering the eyebrows. Electrical signals follow that nerve to areas in the brain where seizures often begin, researchers say.

The group that advises the U.S. government on vaccination thinks some new vaccines may not be worth the cost.

In 2009, the Advisory Committee on Immunization Practices, or ACIP, decided it's not cost effective to routinely vaccinate boys for human papillomavirus, though they do recommend the vaccine for girls. Now the group is struggling to decide whether infants and toddlers should get costly new vaccines to prevent a form of meningitis caused by bacteria.

Scientists have finally demonstrated that sex is useful.

A team from Indiana University found that worms that have sex were better able than asexual worms to stay one evolutionary step ahead of dangerous parasites.

The finding, published in the journal Science, provides the first direct evidence that sexual reproduction improves a species' ability to survive in a fast-changing environment. And it suggests that parasites, including bacteria and viruses, are one reason species developed sexual reproduction in the first place.

The next time you're delayed by rain or snow at an airport, consider this: it's possible that an airplane actually caused the bad weather.

When aircraft fly though certain clouds, they can trigger a chain of events that causes precipitation for miles around, according to a study in the journal Science.

The idea for the study came in 2007, when a plane full of weather scientists flew through a very odd snowstorm near Denver International Airport.