A video featuring the “Luke Arm,” named after the Star Wars prosthetic, being developed by Dean Kamen for a DARPA contract.

http://spectrum.ieee.org/video?id=221

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Caffeine is thought to block the receptor for adenosine, a critical chemical messenger involved in the homeostatic drive for sleep. If that were true, then caffeine would be most effective if it were administered in parallel with growing pressure from the sleep homeostatic system, and also with accumulating adenosine.

To test their hypothesis, the scientists studied 16 male subjects in private suites, free of time cues, for 29 days. Instead of keeping to a 24-hour day, researchers scheduled the subjects to live on a 42.85–hour day (28.57-hour wake episodes), simulating the duration of extended wakefulness commonly encountered by doctors, and military and emergency services personnel. The extended day was also designed to disrupt the subjects’ circadian system while maximizing the effects of the homeostatic push for sleep.

Following a randomized, double-blind protocol, subjects received either one caffeine pill, containing 0.3 mg per kilogram of body weight, roughly the equivalent of two ounces of coffee, or an identical-looking placebo. They took the pills upon waking and then once every hour. The goal of the steady dosing was to progressively build up caffeine levels in a way that would coincide with—and ultimately, counteract—the progressive push of the homeostatic system, which grows stronger the longer a subject stays awake.

The strategy worked. Subjects who took the low-dose caffeine performed better on cognitive tests. They also exhibited fewer accidental sleep onsets, or microsleeps. EEG tests showed that placebo subjects were unintentionally asleep 1.57 percent of the time during the scheduled wake episodes, compared with 0.32 percent for those receiving caffeine. Despite their enhanced wakefulness, the caffeine-taking subjects reported feeling sleepier than their placebo counterparts, suggesting that the wake-promoting effects of caffeine do not replace the restorative effects gained through sleep.

Coffee, tea, and other caffeine-containing beverages are tools. Don’t drink more than you need to and slow the rate of your drinking to spread it out. Keep in mind that once you reach the point where you don’t need to maintain a high feeling of wakefulness that you should immediately stop drinking it.

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The researchers continued collecting information from the parents and interviewed the teens again at age 16, and again at ages 22 and 33.

At age 14, most of the children watched between one and three hours of television each day, while 13% watched more than four hours, and 10% watched less than one hour. Their viewing habits remained nearly identical at ages 16 and 22.

Johnson’s team found that 30% of students who watched more than three hours of television at age 14 had attention problems in subsequent years. By comparison, only 15% of those who watched less than one hour of TV at age 14 showed the same attention deficits later on.

Nearly one-third of those who watched many hours of television fell behind or failed to graduate by age 22. By comparison, only 10% of the teens who watched less than an hour of TV a day went on to perform poorly in school or drop out.

Those who watched three hours or more hours of TV had an 82% greater chance of not graduating or falling behind compared with teens who watched less than an hour – even after controlling for other factors, such as the learning difficulties the teens had at age 14 and their socio-economical status.

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“NO MAN is an island,” wrote John Donne. He was thinking of the wider society of which every human being is a member, but it is also true that human bodies themselves are societies. Besides the 10 trillion human cells in a body, there are another 100 trillion bacterial cells. These bacteria are symbiotic with their human hosts—drawing sustenance from them, but also giving something in return by performing chemical transformations that human cells cannot manage and safely occupying ecological niches that might otherwise be colonised by pathogens. Together, the numerous species that make up this luxuriant community are estimated to contain about 100 times as many genes as the human genome proper. The exact details of this “supplementary” human genome are, however, unknown.

This should soon change. At a meeting held last week in Bethesda, Maryland, a team of researchers organised by Jane Peterson and Lu Wang of America’s National Human Genome Research Institute unveiled their plan for a Human Microbiome Project…One question the project would address is the degree to which the human microbiome is, indeed, uniquely human, and how the various host-microbe relationships have come about. Another is whether a set of bacteria is essential for basic human physiology—in other words whether humans really are symbiotic creatures who would die without their collaborators.

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As recently as 1993, when Dr. Sherwin Nuland wrote the best seller “How We Die,” the conventional answer was that it was his cells that had died. The patient couldn’t be revived because the tissues of his brain and heart had suffered irreversible damage from lack of oxygen. This process was understood to begin after just four or five minutes. If the patient doesn’t receive cardiopulmonary resuscitation within that time, and if his heart can’t be restarted soon thereafter, he is unlikely to recover. That dogma went unquestioned until researchers actually looked at oxygen-starved heart cells under a microscope. What they saw amazed them, according to Dr. Lance Becker, an authority on emergency medicine at the University of Pennsylvania. “After one hour,” he says, “we couldn’t see evidence the cells had died. We thought we’d done something wrong.” In fact, cells cut off from their blood supply died only hours later.

But if the cells are still alive, why can’t doctors revive someone who has been dead for an hour? Because once the cells have been without oxygen for more than five minutes, they die when their oxygen supply is resumed. It was that “astounding” discovery, Becker says, that led him to his post as the director of Penn’s Center for Resuscitation Science, a newly created research institute operating on one of medicine’s newest frontiers: treating the dead.

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