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5 December 2013 11:26 am ,
Vol. 342 ,
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
Since arriving on the island of Guam in the 1940s, the brown tree snake ( Boiga irregularis ) has extirpated native...
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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New Backpack Powers Up
8 September 2005 (All day)
Something old is new again: Ancient Chinese once used springy bamboo shoulder poles to transport heavy loads. Now, a researcher has designed a springy backpack that generates electrical energy through walking, eliminating the need to carry heavy batteries. Such a portable, efficient power source could be especially helpful to soldiers, scientists, or relief workers operating in remote areas.
Walking involves a lot of mechanical energy. From one step to the next, each hip, for example, rises and falls about 4 to 7 centimeters. Strap on a heavy pack, and even more energy is involved--a lot of it wasted. With a rigid pack, there's no way to access it, says muscle physiologist Lawrence Rome of the University of Pennsylvania in Philadelphia. So Rome created a suspended-load backpack that taps into this vertical movement.
Rome's pack uses springs to suspend the load from a fixed frame, allowing it to ride up and down freely during walking. As the pack bounces, it periodically runs a toothed rack across a gear attached to small generator on the fixed frame (see picture), thus converting the mechanical energy of walking into electrical energy.
A 38-kilogram pack can generate a maximum of about 7 watts, if the walker hustles, Rome says. At the more moderate pace of 5.5 kilometers per hour, a 29-kilogram load can generate about 4 watts, more than enough to operate a number of small portable devices at once, such as a cell phone, handheld GPS, PDA, and even night vision goggles, Rome and colleagues report 9 September in Science.
"It's a clever way to have power on the fly," says integrative physiologist Rodger Kram of the University of Colorado at Boulder. An added feature of the suspended-load backpack is that it doesn't just generate power--it also appears to more than double the metabolic efficiency of carrying any load, Kram notes. "So it may just be a better backpack."