News Scan Briefs; June 2005; Scientific American Magazine; by JR Minkel, Charles Q. Choi; 2 Page(s)

When its fuel runs out, an old star expands into a red giant and then collapses to become a white dwarf. Some dwarfs can go through a second period of gianthood because the collapse squeezes and heats leftover fuel, but astrophysicists expected the second red giant phase to last perhaps a few centuries. Now a white dwarf that reignited in 1996 has shown signs of heating up again, indicating that it has already passed through the cooler red giant stage. Radio telescope measurements of the star, known as Sakurai's object or V4334 Sgr, picked up a crackle characteristic of gases ionizing around it, which would require its temperature to have risen quite a bit since the late 1990s. The rapid evolution may be the result of the dwarf's innards mixing poorly, leading the star to burn only the fuel close to its surface, which would quickly run out, hypothesize University of Manchester researchers in the April 8 Science.

If you want to shoo away a fly without waving your hands, try a laser. Just be sure to bathe its nerves in a light-activated chemical before zapping away at it, as Susana Lima and Gero Misesenb¿eck of Yale University have done. They engineered specific fly neurons to produce a rat protein that transmits an electrical signal when activated by the molecule ATP. Next they designed a chemical "cage" for ATP that dissolves when hit with ultraviolet laser light. Finally, they took advantage of a fly's emergency "fly away!" reflex, triggered by the insect's central nerve even when its head is gone. The two could send most zapped flies jumping and flying, even when the flies were blinded or beheaded. They also made slow-moving flies buzz around more excitedly by targeting different neurons. The technique, the investigators say in the April 8 Cell, may permit more precise studies of behavior and brain circuitry than electrodes do.