Archive for March, 2012

Natural Gender Selection: Starving Women Seem to Give Birth to More Daughters

By Sarah Zhang | March 30, 2012 9:06 am

The disastrous economic policies of Mao’s Great Leap Forward caused the single deadliest famine in the history of the world. Between 1958 and 1961, an estimated 15 to 45 million people died of malnutrition in China. And during this period, according to a new study, a strangely high proportion of babies born were female.

China has had a long cultural tradition of favoring sons over daughters, and boys outnumber girls every year in this data from 1940 to 1980. But from one year after the famine’s beginning to two years after its end, the proportion of males drops sharply, as you can see in the graph above.

This study may bolster the Trivers-Willard hypothesis, which suggests that poor maternal condition, such as famine, would favor giving birth to more girls. Since the reproductive success of males tend to be more variable—a reproductively successful male can father many children, whereas a unfit one fathers none—girls are a “safer” evolutionary investment in risky times. The birth sex ratios of mammals such as ground squirrels and red deer follow this pattern. Lab experiments where the male blastocytes of cows survive better in glucose-rich environments identified a possible mechanism.

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CATEGORIZED UNDER: Health & Medicine

Yes, Insecticides Kill Bees. Studies ID Chemical That May Contribute to Colony Collapse

By Sarah Zhang | March 29, 2012 2:54 pm

spacing is important
Honey bees tagged with RFID chips

The mysterious drop in honey bee populations—often called colony collapse disorder for lack of a more specific name—has generated a long list of suspects that includes mites, viruses, malnutrition, and even cell phone radiation. Two new studies published in Science suggest that neonicotinoids, a class of widely used insecticides, may belong at the top of the list.

That an insecticide kills insects like bees is not particularly surprising. Neonicotoinoids have already been partially banned in Italy, Germany, and France for their possible role in colony collapse disorder. Still, it remains one of the most common pesticides: one neonicotoinid alone, imidacloprid, is authorized for use on over 140 crops in 120 countries. Results from the two new studies suggest that even doses that do not kill the bee immediately can have enough ill effect to eventually cause colony collapse.

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CATEGORIZED UNDER: Environment, Living World

New Algorithm Captures What Pleases the Human Ear—and May Replace Human Instrument Tuners

By Sarah Zhang | March 29, 2012 10:16 am

As computer hardware and software becomes ever more powerful, they find ways to match and then exceed many human abilities. One point of superiority that humans have stubbornly refused to yield is tuning musical instruments. Pythagoras identified the precise, mathematical relationships between musical tones over 2,000 years ago, and modern machines can beat out any human when it comes to precise math. So why aren’t computers better than people? The professional tuner does have one incontrovertible advantage: a trained human ear.

Imprecision, it turns out, is embedded in our scales, instruments, and tuning system, so pros have to adjust each instrument by ear to make it sound its best. Electronic tuners can’t do this well because there has been no known way to calculate it. Basically, it’s an art, not a science. But now, a new algorithm published in arXiv claims to be just as good as a professional tuner. To understand how this new algorithm works, it’s worth understanding how today’s electronic tuners don’t work.

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CATEGORIZED UNDER: Physics & Math, Top Posts

Watch This: Earth's Oceans Wriggling With Durable, Beautiful Currents

By Sarah Zhang | March 28, 2012 9:10 am

 

For a strangely hypnotic minute and a half, check out this visualization of the Earth’s ocean currents. It flies you across the globe–past small blue swirls and over the bright lines of the Gulf Stream. More ocean current photos and videos, all based on data from NASA’s ECCO2 project, are available to watch and download at the Scientific Visualization Studio.

[via PopSci]

CATEGORIZED UNDER: Environment

"Death Star" of Medical Technology: Proton-Beam Therapy Shows "All the Problems" in US Healthcare

By Sarah Zhang | March 27, 2012 12:20 pm

spacing is important

Proton-beam therapy is massively expensive—$100+ million facilities, each treatment twice as much as radiation—and not proven to be any safer or more effective than other cancer treatments. So why are U.S. hospitals racing to build new proton-beam facilities?

Financial incentives, and the wrong ones, according to a skeptical piece at Bloomberg. To house the 200-ton cyclotron that accelerates protons to 93,000 miles per second, the facilities have to be as big as football fields, with 16-feet-thick concrete walls. Hospitals can afford to build them because proton-beam therapy is “extremely favorably reimbursed” by Medicare and many private insurance companies, says Sean Tunis, CEO of the Center for Medical Technology Policy. To foot the construction bill, hospitals will have to push the treatment aggressively to cancer patients.

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CATEGORIZED UNDER: Health & Medicine, Technology

Old Bones Tell the Tales and Reveal the Diets of 18th-Century Sailors

By Sarah Zhang | March 27, 2012 8:39 am


You are what you eat—that’s true even after your bones have spent 200 years buried in the dirt. A new study using old bones from 18th century British sailors confirmed the naval diet: lots of biscuits, more protein than the average landlubber, and the same damn things sailors ate for the previous 200 years.

The Victualing Board actually kept meticulous records of a sailor’s official rations: 1 lb of bread and 1 gallon of beer per day (!), plus 1 lb of pork twice a week, 2 lbs of beef twice a week, or butter and cheese the other three days. But when the going got tough out in the middle of watery nowhere, did sailors actually get their rations? Yes, it seems, based on an analysis of nitrogen isotopes extracted from the bones of 80 sailors. The elevated levels of nitrogen suggested that sailors did get as much beef and pork as the Victualing Board recorded. And despite being at sea, they didn’t seem to eat much fish.

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CATEGORIZED UNDER: Health & Medicine

Let Them Eat Dirt: How Clean Environments May Set Kids Up for Immune Problems

By Sarah Zhang | March 26, 2012 1:38 pm

dirty baby

With modern plumbing and hygiene, the number of nasty microbes we humans are exposed to has plummeted, while the rate of autoimmune diseases and allergies has shot up. Are those related? Proponents of the hygiene hypothesis think so: our immune system is supposed to develop by encountering microbes, so being too clean throws it out of whack as the immune system overreacts to minor insults.

A new study found that mice raised germ-free had especially high numbers of invariant natural killer T cells (iNKT) in their colons and lungs—the mouse versions of inflammatory bowel disease and asthma, respectively. Most evidence supporting the hygiene hypothesis has just been in observed correlations, so this research that identifies a plausible molecular mechanism is good evidence for how over-cleanliness might cause immune dysfunction.

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CATEGORIZED UNDER: Health & Medicine

The Bionic Limb Revolution? Not So Fast

By Sarah Zhang | March 26, 2012 9:52 am

A monkey controls his robotic arm with a brain-machine interface. 

If this monkey can eat marshmallows with his robotic arm, mind-controlled prosthetics for humans can’t be far off, right? Well, that’s true if all you ever wanted to do with your prosthetic was sit strapped in a chair reaching for marshmallows. But as Michael Chorost explains in a recent feature for Wired, challenges abound when building an arm that works in everyday life.

Over the course of a day, you might use your arm to pick up a chair, unzip your jacket, or scratch your neck—each one of these actions are unique. But statistical algorithms used now can translate the firing of neurons into only a few stereotyped motions. And it’s not just about writing better algorithms; it’s an input problem too. Getting electrodes to pick up signals from the same neurons over time is a continuous battle against the body’s natural defenses:
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Messenger Results: Mercury is a Giant Ball of Iron

By Veronique Greenwood | March 24, 2012 8:28 am

mercury

Mercury is an odd little planet, tiny but incredibly dense, relatively close by but hard to study via telescope. The MESSENGER probe‘s latest findings, 57 papers presented two days ago at conference, bring new weirdness to our understanding of the planet closest to the Sun.

Take, for instance, the new revelations about Mercury’s core. We always knew that Mercury had a proportionally larger core than Earth does; geologists thought that it might make up a whopping 42% of the planet’s volume, in comparison to Earth’s 17%. The newest estimate, though, blows that out of the water: We now think the number is 85%. To boot, there appears to be an extremely dense layer more than a hundred miles thick encasing the core, perhaps a shell of iron sulfide. That makes the mantle and crust—to use the memorable analogy of a planetary scientist interviewed by Wired—like a mere orange peel on a giant orange of metal.

Another memorable finding: the largest crater on Mercury, Caloris Basin, isn’t actually much of a basin. It seems that the crater’s center gradually rose at some point in the not-too-distant past until it was higher than its edges. This has geologists revising their impressions that Mercury stopped being geologically active 4.5 billion years ago to something more like 2 billion years ago.

[via Wired]

Image courtesy of Case Western Reserve University

CATEGORIZED UNDER: Space

Here's Lookin' at You, Io

By Veronique Greenwood | March 22, 2012 2:37 pm

io

Pulling together decades of data from the Voyager, Galileo, Cassini, and New Horizon probes, as well as the Hubble Space Telescope, scientists at the US Geological Survey have put together a complete geological map of Io, the beautiful, mysterious Jovian moon. Io is the most volcanically active object in the solar system, and its surface reflects that: unlike everything else around, it has no craters, a sign that its surface is constantly being remade. That’s thanks to volcanoes that shoot out more than 100 times more lava per year than Earth’s.

The map is a lovely thing, and you can play around with it yourself here.

CATEGORIZED UNDER: Space
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