Magazine

Red-Handed Terrorists


Scientists in Israel have made it much easier to detect whether a suspected terrorist has had contact with urea nitrate, an easy-to-concoct explosive. The compound was used in the 1993 World Trade Center bombing in New York and is a growing threat in Israel and possibly Iraq. Joseph Almog and his team at the Hebrew University of Jerusalem devised a spray that turns red when it contacts even minute traces of urea nitrate??s little as 5 millionths of a gram. Investigators could swab a suspect's hands with cotton wool, apply the spray to the swab, and get definitive results in seconds.

Such tools won't stop most terrorists before they strike, Almog admits. But they can also be used after an explosion to reveal what materials were used and perhaps by whom. Almog's team, which has patented its spray, is now working on advanced chemical tests that are up to 1,000 times more sensitive than the spray, for use in post-blast analysis. This new work will appear in the November issue of the Journal of Forensic Sciences.

Compact-Disc players aren't just for playing music anymore. Scientists at the Universidad Polit??cnica de Valencia in Spain say the discs and players can also help diagnose medical conditions or spot environmental toxins.

The Spanish team uses pregnancy testing to demonstrate the idea. They submerge a specially prepared CD in a mixture of a urine sample and some chemicals. Then they dry the disc and place it in an ordinary CD player. The same laser that reads the disc and converts data to music interacts with the chemical mix, altering the laser beam's intensity. A computer analyzes the changes in the light to reveal whether or not the donor of the sample is pregnant.

Future applications could include pesticide detection, tests for illnesses such as flu and hepatitis, and on-site monitoring of animal infections on farms.

Cockroaches are helping scientists understand the relationship between circadian rhythms and learning. Playing to the cockroach's food fixation, a team at Vanderbilt University taught each insect in a study to link the smell of peppermint, which they hate, with sugar water, which they crave. Roaches trained in the evening??hen they're generally most active rifling through people's kitchens??emembered the association for several days and returned when they smelled the mint. Those taught in the morning did not.

The roach study may be the first proven case of an insect whose learning ability is affected by its internal clock. But studies suggest timing counts for a lot in how other species??ncluding humans??earn.

?Economists studying behavior have a tool called the "ultimatum game," in which players decide how to divvy up pots of money. The rule is, if one player makes an offer that a second rejects, neither participant receives any money. It turns out biology sways economic choices. MIT research shows identical twins display more similarities in how they play the game than nonidentical twins do, even considering common upbringing. Genetics may account for up to 40% of the differences in how people play.

— While watching chimps play "ultimatum," scientists at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, concluded that these animals lack the human urge to make fair offers. Using raisins as incentives, they found the chimpanzee on the receiving side of a transaction was content as long as he got at least one raisin. And the chimp on the giving end quickly learned there would be no recriminations for being greedy, and thus never made a fair offer. The research appears in the Oct. 5 issue of Science.


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