【Phat Yeti出品】60-SECOND SCIENCE 官方听力文稿 + 讨论帖 （更新至：2008.03.07）

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60-Second Science_ July 7, 2008

Vaccinate Networks, Not Everyone

By vaccinating those individuals with the largest social networks, whole populations could be protected from disease outbreaks more efficiently. Karen Hopkin reports

You’ve probably heard of the whole six degrees of separation thing. It predicts that, on average, you’re no more than six links away from any other person on the planet. Like your roommate runs into a woman whose brother is a writer for Desperate Housewives. Which means you’re only six invites away from having lunch with Marcia Cross’s nannies.

The concept stems from the fact that people have social networks, and those networks tend to intersect. But the importance of this “small world” phenomenon extends beyond whose email address you have on your Blackberry. Now scientists think they can take advantage of these networks to design more efficient vaccination programs.

According to an international team of physicists, the most effective way to protect a population from disease is to immunize people who have the largest networks. If you can keep the most highly connected people from infecting their friends, neighbors, co-workers, you can halt an epidemic. And you may only have to vaccinate half the number of people you would normally. The findings will appear in an upcoming issue of Physical Review Letters. The biggest problem with such a program—people are bound to feel left out when they’re told that they don’t need a shot.

—Karen Hopkin



[ 本帖最后由 sxcz 于 2008-7-14 21:31 编辑 ]

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60-Second Science_ July 8, 2008
Bumpy Whale Fins Outperform Smooth Turbines

Whale and dolphin fins, flippers and tails are bumpy, which produce disturbed wakes that increase lift and decrease drag. Engineers are taking note. Cynthia Graber reports.

Whales and dolphins were molded by evolution to glide through water. We’ve been trying to create streamlined designs ourselves for structures such as wind turbine blades. Now researchers are examining the flippers, fins and tails of our water-dwelling cousins to learn how to improve engineering designs. Dr. Frank Fish—yes, that’s really his name—from West Chester University in Pennsylvania presented this research July 8 at the Society for Experimental Biology’s annual meeting in Marseille.
Here’s one example of the way Dr. Fish’s research is being applied. Whale flippers have a bumpy edge. This makes little sense to engineers. They’ve designed structures like wings and blades that ensure a steady air flow. But it turns out the unsteady flow over this more complex shape increased lift and reduces drag much better than any previous manmade design. It has to do with something called vortices. These are small tornado-shaped water formations in an animal’s wake. The bumps on a whale’s flipper help form vortices that generate more lift, more smoothly. Engineers are using this insight to design an entirely new wind turbine blade—so that we can generate power from wind as efficiently as whales and dolphins fly through the water.
—Cynthia Graber

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60-Second Science_ July 9, 2008
Ritalin Dose Changes Effect

Research with rats finds that Ritalin at low doses encourages neurons to fire together, but at high doses it's just another stimulant. Christopher Intagliata reports

Doctors prescribe Ritalin to hyperactive kids to calm them down and increase their attention span. And college kids have taken to using Ritalin to concentrate when they hit the books. But it hasn’t been clear how the drug boosts focus. Now a paper in the journal Biological Psychiatry suggests how it might work.
Neuroscientists dosed rats with Ritalin and had them perform the kind of working memory task ADHD patients have trouble with. At the same time they measured neural activity with tiny electrodes implanted in the rats’ brains. At low doses, Ritalin primarily affected the prefrontal cortex, jacking up its sensitivity to signals coming in from the hippocampus. And here’s how the drug seemed to help with attention—it strengthened choruses of neurons firing together and put a damper on scattered, uncoordinated activity.

But at high doses, the prefrontal cortex tuned out, and Ritalin’s effects were similar to those of other stimulants. The rats lost their cognitive edge and they became hyperactive, sniffing and licking repetitively. So Ritalin shows you can indeed have too much of a good thing—to the point of distraction.
—Christopher Intagliata

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