Chips Nearing Smallness Limit

Everything has limits, including how small computer chips can get. The question has been just how small could they get, and when would we reach that limit. Now, David A. Muller and colleagues at Bell Laboratories, Lucent Technologies in Murray Hill, N.J., say they've determined just how small silicon chips can get using current technologies.

The researchers measured the chemical composition and electronic structure, at the atomic level, across "gate oxides," which are the narrowest part of chips at the heart of today's computers.

The minimum thickness needed for the silicon dioxide film to function is four atoms, the researchers report in the June 24 issue of Nature. If manufacturers continue to shrink chips at the current rate, they'll reach that limit by about 2012, the researchers estimate.

"For the next 12 years, microelectronic circuits based on silicon technology will remain the basis for further 'electronization' of our world," writes Max Schulz of the University of Erlangen-Nurnberg in Germany in an accompanying article. "Eventually, science and industry will have to find new ways to build faster and larger computers."

Women's Cycle of Attraction

A woman's preference in men apparently varies depending on where she is in her menstrual cycle. When women are in the middle of their cycle--when they're ovulating and most likely to get pregnant--they seem to prefer more masculine-appearing men. Otherwise, their tastes run to men with more feminine, nurturing looks.

That's according to new research by a team of British and Japanese researchers.

Ian Penton-Voak of the University of St. Andrews in Scotland and colleagues asked 39 Japanese women to look at a series of pictures of male faces and pick the ones they found most attractive. When the researchers examined where the women were in their menstrual cycle, they found that the women who were ovulating preferred more masculine-looking men.

In a second experiment, the researchers asked 65 British women to alter composite pictures of male faces to make them more masculine- or feminine-looking and choose the most attractive face for a "long-term relationship" or a "short-term sexual relationship." For the most part, women who were ovulating chose masculine men for short-term flings and feminine men for long-term relationships.

"A female might choose a primary partner whose low masculine appearance suggests cooperation in parental care but occasionally copulate with a male with a more masculine appearance," they write in the June 24 issue of Nature.

Chimps' Familial Recognition

Chimpanzees appear to be able to identify other chimps that are related to each other, even if they have never met them, just by looking at pictures of their faces.

Lisa Parr and Frans de Waal of the Yerkes Regional Primate Research Center in Atlanta demonstrated this ability in man's closest living relative by testing three male and two female chimps. The researchers showed the chimps pictures of the faces of other chimps they had never seen before and rewarded them if they could determine which of two other pictures of chimps was of a relative of the first.

"This is the first demonstration of any non-human primate of kin recognition that is visual and independent of familiarity," said Parr, who reports the results in the June 17 issue of Nature.

Curiously, the chimps could only match females to their sons and not to their daughters. The researchers speculated that this may be because in the male-centered chimp social system this ability is more important. Females, for example, move into neighboring chimp groups as soon as they reach puberty to avoid mating with their relatives. So the ability to recognize facial similarities may help a female avoid moving into a group in which the males resemble her mother.

Depression May Alter Brain

Depression may cause permanent changes in the brain, according to new research.

Yvette I. Sheline of Washington University School of Medicine in St. Louis and her colleagues performed brain scans on 48 women aged 23 to 86, half of whom had a history of clinical depression. A part of the brain called the hippocampus was about 10 percent smaller in the women who had a history of depression, the researchers report in the June 15 issue of the Journal of Neuroscience.

The hippocampus is involved in learning and forming memories. The women with a history of depression also performed more poorly on memory tests.

"The finding that depression can result in volume loss and that more depression can result in even greater volume loss underscores the importance of treating and preventing depression," Sheline says. "Treatment not only can prevent suffering and restore quality of life. It also appears that treating depression may limit long-term damage."

The 'Ouch!' Precursor

Anyone who has ever sat in a dentist's chair knows that the anticipation of pain is part of what makes pain so unpleasant.

To learn more about how the brain handles pain and its precursor, Alexander Ploghaus of the University of Oxford in England and colleagues used brain scans to study 12 healthy volunteers while they experienced painful sensations on their left hands that were signaled in advance by a colored light. Different parts of the brain were activated to anticipate pain and experience the pain itself.

"Anticipation of pain can in its own right cause mood changes and behavioral adaptations that exacerbate the suffering experienced by chronic pain patients," the researchers write in the June 17 issue of Science. "Selective manipulations of activity at these sites may offer therapeutic possibilities for treating chronic pain."