Three genetic variations picked out by powerful whole-genome scans help explain why some people develop AIDS quickly while others keep it at bay. (p. 35)

Hundreds of thousands of years ago, the spillover from an immense glacial lake carved a chasm that in a matter of weeks separated what is now Britain from continental Europe. (p. 35)

Prions, deformed proteins that cause brain-destroying diseases such as chronic wasting disease or mad cow disease, are more infectious when bound to soil particles. (p. 36)

Thanks to an immense calculation that worked out every possible game position, computers can now play a flawless game of checkers and force a draw every time. (p. 36)

As Arctic ice has dwindled, pregnant polar bears in northern Alaska have become more likely to dig their birthing dens on land or nearshore ice than on floating masses of sea ice. (p. 37)

A compound in the curry spice turmeric restores the ability of immune system cells to destroy plaques linked to Alzheimer's disease. (p. 37)

Red blood cells can send a chemical signal that makes platelets less sticky, easing blood flow through narrow vessels. (p. 38)

A new technology based on classical electromagnetic theory uses oscillating magnetic fields to transfer electric power wirelessly across a room. (p. 40)

Mathematical models that capture the essence of biological growth mechanisms are beginning to reveal how plants develop structures with intriguingly elegant geometries. (p. 42)

Transplants of human-brain stem cells triggered signs of improvement in monkeys with a Parkinson's disease–like disorder. (p. 45)

Nearly one in three recently surveyed U.S. adults reports having had serious alcohol problems at some time in their lives. (p. 45)

New observations by the Cassini spacecraft indicate the presence of ice and solid carbon dioxide on Saturn's moon Hyperion, and suggest an explanation for the orb's spongelike appearance. (p. 46)

A two-layer, polymer-based solar cell has good efficiency and could be cheap to mass-produce. (p. 46)

Nonperiodic structures called quasicrystals can act as interfaces between different crystal structures that would ordinarily not stick to each other. (p. 46)

A jogger wearing an iPod music player suffered second-degree ear and neck burns, burst eardrums, and jaw fractures after lightning struck a nearby tree. (p. 46)

(p. 47)