Category Archives: GeekScience

Salt, We Misjudged You

The first time I questioned the conventional wisdom on the nature of a healthy diet, I was in my salad days, almost 40 years ago, and the subject was salt. Researchers were claiming that salt supplementation was unnecessary after strenuous exercise, and this advice was being passed on by health reporters. All I knew was that I had played high school football in suburban Maryland, sweating profusely through double sessions in the swamplike 90-degree days of August. Without salt pills, I couldn’t make it through a two-hour practice; I couldn’t walk across the parking lot afterward without cramping.

While sports nutritionists have since come around to recommend that we should indeed replenish salt when we sweat it out in physical activity, the message that we should avoid salt at all other times remains strong. Salt consumption is said to raise blood pressure, cause hypertension and increase the risk of premature death. This is why the Department of Agriculture’s dietary guidelines still consider salt Public Enemy No. 1, coming before fats, sugars and alcohol. It’s why the director of the Centers for Disease Control and Prevention has suggested that reducing salt consumption is as critical to long-term health as quitting cigarettes.

And yet, this eat-less-salt argument has been surprisingly controversial — and difficult to defend. Not because the food industry opposes it, but because the actual evidence to support it has always been so weak.

When I spent the better part of a year researching the state of the salt science back in 1998 — already a quarter century into the eat-less-salt recommendations — journal editors and public health administrators were still remarkably candid in their assessment of how flimsy the evidence was implicating salt as the cause of hypertension.

“You can say without any shadow of a doubt,” as I was told then by Drummond Rennie, an editor for The Journal of the American Medical Association, that the authorities pushing the eat-less-salt message had “made a commitment to salt education that goes way beyond the scientific facts.”

While, back then, the evidence merely failed to demonstrate that salt was harmful, the evidence from studies published over the past two years actually suggests that restricting how much salt we eat can increase our likelihood of dying prematurely. Put simply, the possibility has been raised that if we were to eat as little salt as the U.S.D.A. and the C.D.C. recommend, we’d be harming rather than helping ourselves.

Your body’s internal clock is at war with society

Just because you sleep later than your early rising friends doesn’t mean you sleep longer than they do; nor does it make you lazier. And yet, the association between the time of day that a person wakes up and how proactive or driven they are is just one example of the many preconceptions that society upholds regarding sleep and productivity.

But here’s the problem: these expectations might actually be working against us.

In his recently published book, Internal time: Chronotypes, Social Jet Lag and Why You’re So Tired, German chronobiologist Till Roenneberg provides numerous examples of how social expectations surrounding time may be having a detrimental effect on large sections of the human population. Over on Brain Pickings, Maria Popova walks us through one of Roenneberg’s examples, wherein he examines the clash between adolescents’ sleep cycles and the starting times of typical school days:

Roenneberg points out that in our culture, there is a great disconnect between teenagers’ biological abilities and our social expectations of them, encapsulated in what is known as the disco hypothesis – the notion that if only teens would go to bed earlier, meaning not party until late, they’d be better able to wake up clear-headed and ready for school at the expected time. The data, however, indicate otherwise – adolescents’ internal time is shifted so they don’t find sleep before the small hours of the night.

Here, we brush up against a painfully obtrusive cultural obstacle: School starts early – as early as 7 A.M. in some European countries – and teens are expected to perform well on a schedule not designed with their internal time in mind. As a result, studies have shown that many students show the signs of narcolepsy – a severe sleeping disorder that makes one fall asleep at once when given the chance, immediately entering REM sleep.

Teen sleepingIn other words: our culture’s tendency to associate early rising with an ideal sleep pattern may be clashing with the biological needs of teenagers. On one hand, studies like this are troubling, because they suggest that we’re standing in the way of our students’ success. At they same time, however, they seem to point to a straightforward solution: simply tailor start-times to better fit the teenagers’ biological clocks:

Plasma Rocket Could Travel to Mars in 39 Days

In 2009, the Ad Astra Rocket Company tested what is currently the most powerful plasma rocket in the world. As the Webster, Texas, company announced, the VASIMR VX-200 engine ran at 201 kilowatts in a vacuum chamber, passing the 200-kilowatt mark for the first time. The test also marks the first time that a small-scale prototype of the company’s VASIMR (Variable Specific Impulse Magnetoplasma Rocket) rocket engine has been demonstrated at full power.

VX-200

A photograph of Ad Astra scientists in front of the AARC 150 m3 vacuum chamber. Credit: Ad Astra Rocket Company

“It’s the most powerful plasma rocket in the world right now,” says Franklin Chang-Diaz, former NASA astronaut and CEO of Ad Astra. The company has signed an agreement with NASA to test a 200-kilowatt VASIMR engine on the International Space Station (ISS) in 2013. The engine could provide periodic boosts to the ISS, which gradually drops in altitude due to atmospheric drag. ISS boosts are currently provided by spacecraft with conventional thrusters, which consume about 7.5 tonnes of propellant per year. By cutting this amount down to 0.3 tonnes, Chang-Diaz estimates that VASIMR could save NASA millions of dollars per year.

This video shows what it’s like to fire the VASIMR plasma rocket, the highest power steady-state electric propulsion device in the world, located in Houston TX.

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