Data Points

By Scott Turner / November / December 2000
October 24th, 2007

BUDWEISER HAD IT ALL WRONG. If three male bullfrogs sit next to one another on a log, each will probably ignore the other two, says Seth Horowitz, a postdoctoral researcher in neuroscience and psychology. According to a recent study he coauthored, the closer bullfrogs are grouped, the less likely they are to respond to one another’s calls. Male bullfrogs call for two reasons, Horowitz says: to attract mates and to warn intruders away from their defined territory. He speculates that proximity inhibits calling because bullfrogs don’t want to have to defend their territory too often. “It looks ridiculous to us,” he says, “but they take their fights very seriously. They’re vicious—they try to swallow each other.” — Chad Galts


ALLERGIES AND ASTHMA. In a twenty-three-year study of Brown freshmen, Clinical Professor of Medicine Guy Settipane has found that the likelihood of developing asthma increases with age, especially if you have allergies. The class of 1967 had an asthma frequency rate of 5.3 percent when it arrived on campus, but in a 1990 follow-up with roughly half the original group, the rate had climbed to 11.4 percent. Alums with allergies, meanwhile, were three times more likely to have developed asthma. The study, which was described in the May 2000 Annals of Allergy, Asthma & Immunology, contained better news for hay-fever sufferers: close to 55 percent of those surveyed said their symptoms had improved, while nearly 23 percent were entirely free of them. — Scott Turner


MAKING WAVES. Drag is the enemy of every engineer: overcoming it would make a submarine move faster through water and oil slip more quickly through a pipeline. Researchers have typically attacked this problem by designing ever smoother surfaces. Now Professor of Applied Math George Karniadakis has a better idea. The key to eliminating the twisted, turbulent eddies that develop along the surfaces of any moving object, he says, is to give them a second skin to create waves at right angles to whatever is flowing past them. By creating tiny waves on a surface, he explains, “you cut off the main mechanism of producing turbulence.” Developed on a hunch by the professor and one of his graduate students , the idea of creating waves to combat waves is, Karniadakis admits, counterintuitive. “That’s why people have never tried it before,” he says. — Chad Galts

HOW THE WEST WAS LOST. The Great Plains weren’t so plain 17 million years ago: the region, which was dominated by wooded grasslands, contained a rich collection of ancient plants and animals. In fact, says Professor of Ecology and Evolutionary Biology Christine Janis, the region contained a greater diversity of species than any ecosystem today. But by 10 million years ago the number of browsing species, which feed on shrubby plants, was reduced by half. In a new study, Janis and her colleagues suggest this change was consistent with a decline in atmo-spheric carbon dioxide. Because higher concentrations of ambient carbon dioxide result in greater plant growth, especially of shrubs, Janis says its slow drop resulted in lower plant productivity and might have led to the disappearance of such shrub-dependent animals as the North American camel.

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November / December 2000