Last April, a volcanic eruption in Iceland sent a cloud of ash billowing towards Europe. That ash was potentially hazardous for aircraft, and authorities decided to ground all flights — inconveniencing tens of thousands of travelers — rather than risk an accident.
Although images of dead birds and blackened marshes in the Gulf of Mexico are gone, many scientists say it's too early to declare a recovery. They suspect there could be hidden damage to the Gulf's marine life and marshes.
More than 70 percent of Americans now own cellphones, and many of those users have wondered, at some point, whether regularly holding a phone to the head might lead to brain cancer.But Siddhartha Mukherjee, an assistant professor of medicine at Columbia University, found thatdespite years