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How Does an Anti-Gravity Treadmill Work?

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alterg.com

The "anti-gravity treadmill" was originally invented by Robert Whalen, a biomechanics researcher at NASA Ames Research Center, in the 1990s.

Whalen knew that astronauts on the International Space Station have to exercise for hours each day to combat the loss of bone mass and muscle in microgravity. But the treadmill on the ISS has always left a lot to be desired. In lieu of gravity, it uses straps around the shoulders and hips to anchor the astronaut to the treadmill. The bungee system doesn't do a good job of replicating the magnitude or types of force that runners experience here on Earth. And to make matters worse, it's pretty uncomfortable to run in. Astronaut Sunita Williams, who was the first person to run the Boston Marathon in space, described her experience in a NASA press release: "During the marathon my foot sometimes went numb and tingly from the straps' pressure on my hip. Also, I had to use moleskin where the harness rubbed my neck raw."

NASA

Whalen designed a treadmill that would let astronauts run in a more natural way. The design, patented in 1992, encloses a treadmill and the astronaut's lower body in an airtight chamber. Lowering the air pressure inside the chamber pushes the astronaut down, simulating gravity. Whereas the ISS's old treadmill allowed Williams to run on about 60 percent of her Earth weight, Whalen's treadmill would have allowed her to exercise at her normal Earth weight. That's important for keeping the muscles and bones healthy for when astronauts get home.

But Whalen's idea never made it off the ground. In 2005, the technology was licensed to a company called AlterG, which appears to have coined the term "anti-gravity treadmill." Instead of adding weight to astronauts in space, AlterG uses the technology to take the weight off of rehab patients recovering from leg and foot injuries.

NASA

AlterG's product looks like a bounce house for your lower body. To use it, you put on a pair of tight neoprene shorts. The shorts have a sort of skirt attached, and the skirt is lined with zipper teeth. You step onto the treadmill, inside a hole in its plastic casing, and zipper yourself in so that, from the waist down, you're encased in an airtight plastic bag. As you stand there, the treadmill measures your weight, and you tell it how intense you want your workout to be. The the machine uses "unweighting technology" to make you feel up to 80 percent lighter—so if you weigh 100 pounds, you could feel as light as 20 pounds on the treadmill. The terms "anti-gravity" and "unweighting technology" are enthusiastic descriptions for what the machine actually does, which is inflate the plastic bag around your lower body to lift you off the surface of the treadmill.

Despite its perhaps overhyped name, the anti-gravity treadmill seems to be doing good things in physical rehab clinics, because it allows patients to exercise without exacerbating an injury. Here's NASA's glowing review of the anti-gravity treadmill:

Professional and college sports teams across the United States feature the AlterG treadmill in their training facilities. Injured soldiers walk and run with the technology’s assistance at military hospitals and rehabilitation centers. Seniors get essential exercise using the support the machine provides, as do people with bariatric weight issues who cannot normally support their own weight. The treadmill has been a proven option for neurological uses as well, including helping patients re-learn proper balance and gait and transition to independent movement after traumatic brain injury.

A variety of peer-reviewed studies also suggest it helps people get back on their feet again.

A true anti-gravity machine—one that is not acted on by gravity—would of course have even more exciting applications, particularly in spaceflight. Unfortunately, for now at least, those machines only work in science fiction.

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Big Questions
Can You Really Go Blind Staring at a Solar Eclipse?
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A total solar eclipse will cut a path of totality across the United States on August 21, and eclipse mania is gripping the country. Should the wide-eyed and unprotected hazard a peek at this rare phenomenon?

NASA doesn't advise it. The truth is, a quick glance at a solar eclipse won't leave you blind. But you're not doing your peepers any favors. As NASA explains, even when 99 percent of the sun's surface is covered, the 1 percent that sneaks out around the edges is enough to damage the rod and cone cells in your retinas. As this light and radiation flood into the eye, the retina becomes trapped in a sort of solar cooker that scorches its tissue. And because your retinas don't have any pain receptors, your eyes have no way of warning you to stop.

The good news for astronomy enthusiasts is that there are ways to safely view a solar eclipse. A pair of NASA-approved eclipse glasses will block the retina-frying rays, but sunglasses or any other kind of smoked lenses cannot. (The editors at MrEclipse.com, an eclipse watchers' fan site, put shades in the "eye suicide" category.) NASA also suggests watching the eclipse indirectly through a pinhole projector, or through binoculars or a telescope fitted with special solar filters.

While it's safe to take a quick, unfiltered peek at the sun in the brief totality of a total solar eclipse, doing so during the partial phases—when the Moon is not completely covering the Sun—is much riskier.

WOULDN'T IT BE EASIER TO JUST TELL YOUR KIDS THEY WILL GO BLIND?

NASA's website tackled this question. Their short answer: that could ruin their lives.

"A student who heeds warnings from teachers and other authorities not to view the eclipse because of the danger to vision, and learns later that other students did see it safely, may feel cheated out of the experience. Having now learned that the authority figure was wrong on one occasion, how is this student going to react when other health-related advice about drugs, alcohol, AIDS, or smoking is given[?]"

This story was originally published in 2012.

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Big Questions
If Beer and Bread Use Almost the Exact Same Ingredients, Why Isn't Bread Alcoholic?
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If beer and bread use almost the exact same ingredients (minus hops) why isn't bread alcoholic?

Josh Velson:

All yeast breads contain some amount of alcohol. Have you ever smelled a rising loaf of bread or, better yet, smelled the air underneath dough that has been covered while rising? It smells really boozy. And that sweet smell that fresh-baked bread has under the yeast and nutty Maillard reaction notes? Alcohol.

However, during the baking process, most of the alcohol in the dough evaporates into the atmosphere. This is basically the same thing that happens to much of the water in the dough as well. And it’s long been known that bread contains residual alcohol—up to 1.9 percent of it. In the 1920s, the American Chemical Society even had a set of experimenters report on it.

Anecdotally, I’ve also accidentally made really boozy bread by letting a white bread dough rise for too long. The end result was that not enough of the alcohol boiled off, and the darned thing tasted like alcohol. You can also taste alcohol in the doughy bits of underbaked white bread, which I categorically do not recommend you try making.

Putting on my industrial biochemistry hat here, many [people] claim that alcohol is only the product of a “starvation process” on yeast once they run out of oxygen. That’s wrong.

The most common brewers and bread yeasts, of the Saccharomyces genus (and some of the Brettanomyces genus, also used to produce beer), will produce alcohol in both a beer wort
and in bread dough immediately, regardless of aeration. This is actually a surprising result, as it runs counter to what is most efficient for the cell (and, incidentally, the simplistic version of yeast biology that is often taught to home brewers). The expectation would be that the cell would perform aerobic respiration (full conversion of sugar and oxygen to carbon dioxide and water) until oxygen runs out, and only then revert to alcoholic fermentation, which runs without oxygen but produces less energy.

Instead, if a Saccharomyces yeast finds itself in a high-sugar environment, regardless of the presence of air it will start producing ethanol, shunting sugar into the anaerobic respiration pathway while still running the aerobic process in parallel. This phenomenon is known as the Crabtree effect, and is speculated to be an adaptation to suppress competing organisms
in the high-sugar environment because ethanol has antiseptic properties that yeasts are tolerant to but competitors are not. It’s a quirk of Saccharomyces biology that you basically only learn about if you spent a long time doing way too much yeast cell culture … like me.

This post originally appeared on Quora. Click here to view.

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