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Scopes Monkey Trial: Guilty

Scientific American News - Mon, 07/21/2014 - 14:46
July 21 is verdict day in the infamous Scopes "Monkey" Trial of 1925. The verdict came in from a jury in Dayton, Tenn., that John Thomas Scopes had committed the crime of teaching evolution to...

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Ask Anything: Can Humans Smell Fear?

Popular Science News - Mon, 07/21/2014 - 12:41

Illustrations by Jason Schneider

If humans can indeed smell fear they wouldn’t be unusual in the animal kingdom. Sea anemones, earthworms, minnows, fruit flies, rats, mice, and deer, among others, have all been shown to signal unease through odor. Some responses are even more overt. For example, the offspring of one bird species vomits up a pungent, orange liquid when frightened by a predator; if a parent catches a whiff, it becomes warier in the nest. 

From an evolutionary perspective, a silent signal makes sense. “If you find yourself in a fearful situation, you might want your cohorts to know about it, but without calling attention to yourself by screaming or jumping around,” says Charles J. Wysocki, of the Monell Chemical Senses Center in Philadelphia. The same could hold true for humans. “Primates have become much more visual creatures [over time],” he says, “and I suspect that smell in general, including the perception of the fearful notes, have taken second place. But they’re still there.”

There’s only modest evidence for a smell of fear in people, though. No one has yet found a molecule in human sweat that corresponds to our level of anxiety. Several labs have tried to measure the effects of sniffing someone else’s fear-inspired body odor. First the scientists show people scary movies, and then they collect the subjects’ sweat from cotton pads placed in their armpits. When other people smell the cotton, they respond in subtle and unconscious ways. In one experiment, the smellers became more likely to judge ambiguous facial expressions in photographs as portraying fear. In another, they made fearful expressions of their own. A third found that fear-sniffing subjects blinked more forcefully and seemed more prone to being defensive.

These studies have some big problems. Sweat born from emotion does seem to have a different smell than sweat from exercise. But that doesn’t tell us whether fear-related sweat works differently from, say, happiness-related sweat or the sweat that comes from sexual arousal. “We’re using very crude techniques to study this,” says Denise Chen, a pioneer in this field at the Baylor College of Medicine. Among the limitations of the work is the fact that emotions can be hard to regulate in the lab. “It’s very easy to scare people,” she says, “but it’s not so easy to make them happy.”

Hygiene products pose another problem. The researchers must find subjects who are willing to forgo deodorant for several days before each study. “That’s hard to do in this country because people are so hygiene-conscious,” Chen says. It also raises the question of whether any of this research would even matter in a real-world setting. Given all the fragrances we dab onto our bodies, any signals that sweat might contain would be undetectable.

Or maybe not. Wysocki says there’s evidence that certain people can detect body odor even when masked. He tested about 40 common compounds used to cover smells and arrived at a surprising result. “It’s fairly easy to block the body odor of women in the noses of men,” he says. “But when it came to women, only two of the [masking] compounds were effective.”

This article originally appeared in the August 2014 issue of Popular Science.

HIV Cleared in 2 Patients via Cancer Treatment

Scientific American News - Mon, 07/21/2014 - 12:00
Patients' virus levels became undetectable after a bone-marrow therapy with stem cells

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Tiny Traps Capture Individual Blood Cells

Popular Science News - Mon, 07/21/2014 - 11:51

Trapped! An illustration and two microscope images showing the pyramidal self-folding traps and round cells. From Kate Malachowski et al., "Self-Folding Single Cell Grippers," Nano Letters 2014

Gotcha! These little pyramids are actually microscopic traps designed to gently enclose single cells without killing them. The idea is that in the future, such traps could be a part of a system for capturing and analyzing individual cells, perhaps as a part of cancer monitoring.

The traps, which are made out of silicon oxides, start out as flat, star-like shapes. When they're dipped into a saline solution, the arms automatically begin to fold inward along their hinges, capturing any cells that might be nearby at the time. In a new study, the traps' creators have shown the little nano-stars are able to grip two different kinds of mouse cells without killing them: red blood cells and fibroblasts, which are a type of connective tissue cell.

The traps' lead engineer, David Gracias of Johns Hopkins University, has long worked on making microscopic structures that start out flat, but then fold up by themselves. In addition to minute pyramids, he and his lab members have made all kinds of polyhedrons. They've made self-folding structures that fold in response to heat, instead of a dip in saline solution. They've even made microscopic, self-folding shapes with a kind of glue along the edges so they'll seal themselves once they're folded. You can see some of these shapes in a video they published last year. In their latest study, published in the journal Nano Letters, they worked with engineers from the U.S. Army Research Laboratory to make pyramidal grippers that are small enough to capture single cells and have vents so the cells can continue to exchange nutrients and waste with the liquid around them even while they're trapped.

There's a lot of work that the cell-grippers' designers would still need to do to put the grippers into a working product. They might want to be able to target certain cells, for example, instead of just capturing whatever happens by. If these traps are something they want to be able to inject in the human body—and that's what Gracias meant when he talked with about using this in vivo—then they'll also have to do a lot of safety testing.

Recall Your Favorite “Aha!” Moment—and Share It with Us

Scientific American News - Mon, 07/21/2014 - 11:20
Flashes of insight often come to a prepared mind. What led to yours?

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Modern Birds Evolved before the Dinosaurs Died

Scientific American News - Mon, 07/21/2014 - 11:00
Modern birds, long thought to have arisen only after the dinosaurs perished, turn out to have lived alongside them

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Squid Protein Could Help Brains 'Talk' to Computers

Popular Science News - Mon, 07/21/2014 - 10:57

The Caribbean reef squid, in the pencil squid family. Public Domain via Wikipedia

In the most advanced prosthetics--such as this crazy mind-controlled robotic arm--electronic hardware interfaces directly with nerves and muscles in the human body. But getting living tissue to play nice with a circuit board is anything but easy, for a number of reasons. One fundamental obstacle you may not have considered: electronics send signals via negatively charged electrons, whereas many of the communications carried out in living tissues take place through the movement of positively-charged particles, such as calcium and potassium ions. 

Now, though, scientists have discovered a new feature of a protein called reflectin, found in a group of animals called pencil squid. It turns out reflectin conducts protons and may be able to bridge the communication divide between cells and biomedical implants. Genetic Engineering and Biotechnology News explains:

[The team] began studying reflectin to discern how it enables the squid to change color and reflect light. They produced the squid protein in common bacteria and used it to make thin films on a silicon substrate. Via metal electrodes that contacted the film, the researchers observed the relationship between current and voltage under various conditions. Reflectin transported protons, they found, nearly as effectively as many of the best artificial materials.

It's ability to move around these positive charges and it's "tunability," or versatile nature, could be used to build implants and prosthetics that can more easily communicate with the human body. The fact that it is biological and flexible means that it may be better than existing materials for integrating into the human body, and with a lower chance of being rejected, the researchers (from the University of California, Irvine) said. And since it is a protein, it could be modified in other desirable ways, such as possibly being able to biodegrade after it is done serving a useful purpose, which could help patients avoid additional surgeries. 

The squid protein reflectin is also being investigated to make better camouflage, thanks to its interesting optical qualities.

[Genetic Engineering and Biotechnology News / Nature Chemistry]

Cystic Fibrosis Might Be 2 Diseases

Scientific American News - Mon, 07/21/2014 - 10:15
The sister disease affects the pancreas and other organs, while leaving the lungs alone

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Education Level Linked to Nearsightedness

Scientific American News - Mon, 07/21/2014 - 09:26
In a German study, half of those with a university degree were myopic compared to less than a quarter of folks who quit after high school or secondary school. Karen Hopkin reports.    

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Sandstone Arches Form under Their Own Stress

Scientific American News - Mon, 07/21/2014 - 09:25
Downward pressure and erosion combine to create the celebrated rock formations

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The Science of Lightning

Popular Science News - Mon, 07/21/2014 - 09:00

Shocking! Photograph by Travis Rathbone

When it comes to thunderheads, lightning is the great equalizer. Essentially a giant spark, lightning relieves the charge differentials that build up in storm systems. But it’s also one of the greatest mysteries in atmospheric science. Recently, scientists have started to explore lightning’s lesser-known siblings, which appear in ash plumes, labs, and even on other planets.

Odds of Survival

A typical lightning bolt carries 100 million volts—compare that to the 110 volts in an average electrical outlet. Yet more than a century’s worth of data shows that only 30 percent of lightning strikes are fatal. A charge can spark across skin like electricity across a resistor, causing severe burns but sparing internal organs.  

Types of Lightning Dark

Some lightning can’t be seen. Gamma rays burst from thunderheads without giving off heat or light, but their radiation is 100 times more energetic than a medical x-ray. Scientists were perplexed by these invisible flashes until researchers recently found that they, too, diffuse imbalanced charges in clouds.


Extraterrestrial lightning is always tricky to observe. But during Saturn’s 2009 equinox, conditions dampened the rings’ glow enough for the Cassini spacecraft to capture flashes on the gaseous planet. Lightning has also been detected on Jupiter, and radio data suggests it exists on Uranus and Neptune.


Named for the bizarre orbs that have been spotted during storms, ball lightning was finally caught on camera by scientists in 2012. “We don’t know what it is,” says lightning researcher Don MacGorman. Spectral analysis suggests the balls form when lightning strikes and vaporizes elements in the soil.


So-called dirty thunderstorms are thought to occur when dust particles from a volcanic ash plume collide with ice crystals in the atmosphere. This event is hard to study, so researchers in Germany created a plume in the lab using real volcanic ash. The smaller the particles, the more prolific the lightning.

Lightning By Numbers

50,000°F: Temperature of a lightning bolt. That’s five times hotter than the surface of the sun.

Half an inch: Approximate diameter of a lightning-bolt channel

8 million: Average number of lightning flashes that strike Earth every day

This article originally appeared in the August 2014 issue of Popular Science. 

California Halts Injection of Fracking Waste into Ground

Scientific American News - Mon, 07/21/2014 - 09:00
The state warns that fracking for natural gas might be contaminating aquifers used as a source for drinking water

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Ants Could Help Warming Cry Uncle

Scientific American News - Mon, 07/21/2014 - 08:36
At test sites, the exposure of rock by ants accelerated the absorption of atmospheric CO2 by the rock by as much as 335 times compared with ant-free areas. David Biello reports  

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Kidney Stone Risk Creeps North as Climate Changes

Scientific American News - Mon, 07/21/2014 - 08:30
A link between heat and the painful stones means increased chances under global warming

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Giant Pterosaurs Serve as Aircraft Inspiration

Scientific American News - Mon, 07/21/2014 - 08:20
Even the U.S. Department of Defense has shown interest in these long-extinct reptiles

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Molecular Computer Detects Ebola and Marburg Viruses

Scientific American News - Mon, 07/21/2014 - 08:10
Material from deadly pathogens triggers alerts directly, and could speed detection

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Ask Anything: Could Scientists Put Sunscreen In A Pill?

Popular Science News - Mon, 07/21/2014 - 08:00

Illustrations by Jason Schneider

Turns out, a few oral sunscreens already exist, based on the theory that antioxidants offer sun protection. Laboratory studies provide some evidence in support of this idea. When scientists feed vitamin E to hairless mice, the animals show less skin damage upon exposure to ultraviolet light. Dermatologist Salvador González Rodríguez has studied an extract made from a fern called Polypodium leucotomos. The substance, which is high in antioxidants, may decrease sun-related DNA damage in humans, he says. But as a consultant for a Spanish company that makes an oral sunscreen, Rodríguez has skin in the game, so to speak. And he admits that oral sunscreens don’t work that well when measured in the standard ways: “If we evaluate protection in terms of how conventional sunscreens are evaluated, then antioxidant-based oral sunscreens provide very low SPF.”

That doesn’t mean we’ll be stuck slathering our bodies with goopy lotion as we lurch into a globally warmed future. Many marine creatures that live in shallow water produce chemicals called mycosporine-like amino acids, which function as a natural sunscreen by absorbing UV light. These compounds have been found in bacteria, algae, and fungi. Some scientists think it may be possible to pass the compounds on to humans too, though so far, no one has had much success.  

This article originally appeared in the August 2014 issue of Popular Science.

Proton Spin Mystery Gains a New Clue

Scientific American News - Mon, 07/21/2014 - 08:00
Physicists long assumed a proton’s spin came from its three constituent quarks. New measurements suggest particles called gluons make a significant contribution

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Tapping Your Inner Rain Man

Scientific American News - Mon, 07/21/2014 - 06:30
A blow to the head can sometimes unmask hidden artistic or intellectual gifts

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Spider Gene Study Reveals Tangled Evolution

Scientific American News - Mon, 07/21/2014 - 02:05
A new arachnid family tree suggests that many spider species evolved away from web-weaving

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