On the horizon

Ant navigation: stride matters

Putting ants on stilts may sound like a circus trick, but researchers are using them to determine how Saharan desert ants find their way home.

When a desert ant heads out in search of food, it activates an internal pedometer that allows the tiny scavenger to find its way home without landmarks or scents, says a group of scientists, headed by Matthias Wittlinger at the University of Ulm, Germany.

The team let 25 ants wander 10 meters from their nest before capturing them. Researchers then glued tiny bristles to the feet of some ants, clipped a few millimeters off the legs of others, and released the rest tinker-free as a control. When let loose in the lab test, the tall ants marched about five extra meters before realizing they were lost. The shorter ants underestimated the distant home by about five meters.

The conclusion: Instead of measuring distance, desert ants must count steps. This evolution must reset itself after each trip, the team says, because altered ants that later returned home could once again travel to and fro accurately despite the modifications.

The dangers of driving and talking

Multitasking drivers beware: Gabbing on your cellphone while behind the wheel may be as dangerous as driving drunk. Researchers at the University of Utah in Salt Lake City found that talking in traffic – whether holding a cellphone or with a hands-free device – affects driving behavior as severely as cruising with a 0.08 percent blood-alcohol level, which is beyond the legal limit in many states. The report was published in the latest issue of Human Factors: The Journal of the Human Factors and Ergonomics Society.

In the study, 40 drivers used a driving simulator to follow a pace car along a virtual 24-mile highway. Each person first navigated the course undistracted, then did so using a hands-free headset, hand-held cellphone, and finally with a 0.08 percent blood-alcohol level. Drunken drivers maneuvered more aggressively and hit the brakes more forcefully than those chatting on a cellphone.

But those distracted by the phone had slower response times than undistracted drivers, resulting in all three of the virtual accidents recorded during the study. The report confirms past findings that hands-free headsets are only barely safer than hand-held versions.

Measuring earthquakes quickly

New NASA software could cut the time needed to accurately measure a large earthquake to mere minutes, possibly giving coastal towns more time to prepare in the event of an oceanwide disaster like the Sumatra quake of December 2004.

When that quake first roared beneath the Indian Ocean, unleashing immense tsunami waves that killed hundreds of thousands in Asia and Africa, initial estimates seriously underestimated the quake's power. Rapid analysis first gauged its magnitude at 8.0 – too weak to cause an oceanwide tsunami. Scientists took hours to reclassify the quake as a 9.0, which is 30 times more powerful in terms of the amount of energy released. Days later, its strength was upgraded to a 9.2.

But by reexamining 2004 GPS satellite data, a team led by Geoffrey Blewitt of the University of Nevada, Reno, found that immediately after the Sumatra quake, ground stations throughout the Indian Ocean shifted. For example, the massive quake permanently pushed posts in India (1,200 miles from the quake's epicenter) approximately 0.4 inches. The new NASA software can track this displacement quickly, providing an accurate measure of significant quakes within 15 minutes. The system, however, will only work on large quakes with magnitudes between of 8.7 and 9.3.

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