【推荐2】A new study has found no evidence that sunscreen, commonly used to reduce the risk of skin cancer, actually increases the risk.

Researchers from the University of Iowa based their findings on a review of 18 earlier studies that looked at the association between sunscreen use and melanomas(黑素瘤). They said that they found flaws in studies that had reported associations between sunscreen use and higher risk of melanoma.

Most health experts believe that by protecting the skin from the harmful effects of the sun, sunscreen helps prevent skin cancer, which is increasing in incidence (发生率) faster than any other cancer in the United States.

But questions have been raised about sunscreen and whether it may have the opposite effect, perhaps by allowing people to remain exposed to the sun longer without burning.

The researchers said that among the problems with some earlier studies is that they often failed to take into account that those people most at risk for skin cancer—people with fair skin and freckles(雀斑), for example—are more likely to use sunscreen. As a result, it may appear that sunscreen users get cancer more often.

The studies, which generally relied on volunteers to recall their sunscreen use, were also unable to prove how well the products had been applied, said the new study.

【推荐2】Bacteria are an annoying problem for astronauts. The microorganisms (微生物) from our bodies grow uncontrollably on surfaces of the International Space Station, so astronauts spend hours cleaning them up each week. How is NASA overcoming this very tiny big problem? It’s turning to a bunch of high school kids. But not just any kids. It is depending on NASA HUNCH high school classrooms, like the one science teachers Gene Gordon and Donna Himmelberg lead at Fairport High School in Fairport, New York.

HUNCH is designed to connect high school classrooms with NASA engineers. For the past two years, Gordon’s students have been studying ways to kill bacteria in zero gravity, and they think they’re close to a solution (解决方案). “We don’t give the students any breaks. They have to do it just like NASA engineers,” says Florence Gold, a project manager.

“There are no tests,” Gordon says. “There is no graded homework. There almost are no grades, other than ‘Are you working towards your goal?’ Basically, it’s ‘I’ve got to produce this product and then, at the end of year, present it to NASA.’ Engineers come and really do an in-person review, and...it’s not a very nice thing at times. It’s a hard business review of your product.”

Gordon says the HUNCH program has an impact (影响) on college admissions and practical life skills. “These kids are so absorbed in their studies that I just sit back. I don’t teach.” And that annoying bacteria? Gordon says his students are emailing daily with NASA engineers about the problem, readying a workable solution to test in space.