Get a grip The article “Pruney fingers get better grip” (SN: 2/9/13, p. 11) indicated that skin wrinkling in response to extended exposure to water was the result of constricting blood vessels. I was waiting to read about the possibility that this was the body’s response to prevent heat loss. Water has a high heat capacity, and therefore I might expect that blood vessel constriction is to minimize heat transfer from the body to the water. Perhaps the wrinkling is a secondary, albeit advantageous, effect. Jim Marrone, Pinole, Calif. Cat controversy As a conservation biologist, I... (p. 31)

A new printing invention, electrostatic printing, is expected to have a major impact on the nation’s second largest industry because good quality and inexpensive impressions can be made on virtually any material, from building bricks to fresh fruits and vegetables. In the new process dry ink particles instead of wet ink are screened onto the material to be printed. The particles are attracted to the object or surface by an electrically charged backing plate. The design or image to be printed forms the other electrode plate in the system. The ink particles are then fused permanently on the su... (p. 4)

April 8–27 Join ornithologist Paul Sweet on birdwatching walks through New York City’s Central Park during spring migration. See bit.ly/SFAMNHsweet April 29 The National Academy of Sciences hosts a public symposium in Washington, D.C., to honor the society’s 150th anniversary. See bit.ly/SFnas150 (p. 4)

ATOM & COSMOS Curiosity finds minerals consistent with habitability. See “Life-friendly environment confirmed on Mars.” BODY & BRAIN Scientists meld rat minds in “Rats do tasks while connected brain-to-brain.” CULTURE BEAKER See Rachel Ehrenberg’s column on website comments, “Trolls bad news for scientific discourse.” ON THE SCENE BLOG Kids build plasma guns and more in “Intel Science Talent Search finalists show off their work.” (p. 4)

SN Prime | March 18, 2013 | Vol. 3, No. 11 Time after time, physicists have tried to explain time. Many claim to have succeeded. But they haven’t. Otherwise everybody would quit trying to explain it all over again. One of the most recent such efforts comes from the mathematician/cosmologist George F.R. Ellis. He thinks solving the time mystery involves figuring out the difference between the past and the future. That’s not as obvious as it sounds. Physical laws governing motion make no distinction between future and past. Equations describing the scattering of billiard balls on a pool...