Discover的January - February 2015目录

Euphoria overtook the science world on March 17, when members of the BICEP2 team announced the discovery of gravitational waves that represented the “first tremors of the Big Bang.” A couple of months later, two independent analyses claimed the BICEP2 researchers had underestimated the effects of dust in our galaxy, as it could produce the pattern they had attributed to gravitational waves. On Sept. 22, data from the Planck space telescope showed that the portion of the sky BICEP2 studied contained more galactic dust than previously assumed. The two teams have joined forces to determine whether the signal BICEP2 detected originated, at least in part, from gravitational waves, or if it’s entirely explained by dust. The results should appear in late 2014. Meanwhile, astronomers are continuing the kinds of observations…

Suicide ravages freely, claiming old and young, rich and poor, famous and unknown. But some people face increased risk, and current tests don’t spot them early enough to intervene effectively. In July, molecular biologist Zachary Kaminsky of Johns Hopkins University and his team reported a simple way to detect people with suicidal tendencies — with a blood test. They examined DNA from brain tissue of people who died by suicide and those who died of other causes and measured its methylation — levels of chemicals called methyl groups on DNA that alter gene expression. They found that a stress-mitigating gene called SKA2 was less active in those who died by suicide and was more likely to be methylated. Experts believe that when SKA2 is too sluggish, some people can’t stop…

The drill-and-fill approach to fixing cavities may eventually have new competition, thanks to Harvard University biomedical engineer David Mooney and National Institutes of Health assistant clinical investigator Praveen Arany. The pair, along with colleagues, reported in May that they had developed a new technique that stimulates the growth of dentin, the hardened tissue below tooth enamel, through the use of a simple, low-powered laser. Arany drilled holes in the teeth of rats, shined a light similar to a laser pointer into the false cavities for five minutes, then capped them. Twelve weeks later, the dentin inside had grown back. By studying the same process in cultured cells, the scientists found that the light stimulated a molecular chain reaction that activated a normally dormant protein called TGF-beta 1. That protein, in…