Thursday, January 27, 2011


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Gender stereotypes suggest that men are usually tough and women are usually tender. A new study published in Psychological Science, a journal of the Association for Psychological Science, finds these stereotypes have some real bodily truth for our brains; when people look at a gender-neutral face, they are more likely to judge it as male if they’re touching something hard and as female if they’re touching something soft.

Several studies have found recently that we understand many concepts through our bodies. For example, weight conveys importance; just giving someone a heavy clipboard to hold will make them judge something as more important than someone who holds a light clipboard. Michael Slepian, a graduate student at Tufts University, and his colleagues wanted to know if this was also true for how people think about gender.

For one experiment, people were given either a hard or a soft ball to hold, then told to squeeze it continuously while looking at pictures of faces on a computer. Each face had been made to look exactly gender-neutral, so it was neither male nor female. For each face, the volunteer had to categorize it as male or female. People who were squeezing the soft ball were more likely to judge faces as female, while people who handled the hard ball were more likely to categorize them as male.

The same effect was found in a second experiment in which people wrote their answers on a piece of paper with carbon paper underneath; some were told to press hard, to make two copies, and some were told to press lightly, so the carbon paper could be reused. People who were pressing hard were more likely to categorize faces as male, while the soft writers were more likely to choose female.

“We were really surprised,” says Slepian, who cowrote the study with Max Weisbuch of the University of Denver, Nicholas O. Rule at the University of Toronto, and Nalini Ambady of Tufts University. “It’s remarkable that the feeling of handling something hard or soft can influence how you visually perceive a face.” The results show that knowledge about social categories, such as gender, is like other kinds of knowledge—it’s partly carried in the body.

Association for Psychological Science


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Sometimes it’s almost impossible to talk without using your hands. These gestures seem to be important to how we think. They provide a visual clue to our thoughts and, a new theory suggests, may even change our thoughts by grounding them in action.

University of Chicago psychological scientists Sian Beilock and Susan Goldin-Meadow are bringing together two lines of research: Beilock’s work on how action affects thought and Goldin-Meadow’s work on gesture. After a chat at a conference instigated by Ed Diener, the founding editor of Perspectives on Psychological Science, they designed a study together to look at how gesture affects thought.

For the study, published in Psychological Science, a journal of the Association for Psychological Science, Beilock and Goldin-Meadow had volunteers solve a problem known as the Tower of Hanoi. It’s a game in which you have to move stacked disks from one peg to another. After they finished, the volunteers were taken into another room and asked to explain how they did it. (This is virtually impossible to explain without using your hands.) Then the volunteers tried the task again. But there was a trick: For some people, the weight of the disks had secretly changed, such that the smallest disk, which used to be light enough to move with one hand, now needed two hands.

People who had used one hand in their gestures when talking about moving the small disk were in trouble when that disk got heavier. They took longer to complete the task than did people who used two hands in their gestures—and the more one-handed gestures they used, the longer they took. This shows that how you gesture affects how you think; Goldin-Meadow and Beilock suggest that the volunteers had cemented how to solve the puzzle in their heads by gesturing about it (and were thrown off by the invisible change in the game).

In another version of the experiment, published in Perspectives in Psychological Science, the volunteers were not asked to explain their solution; instead, they solved the puzzle a second time before the disk weights were changed. But moving the disks didn’t affect performance in the way that gesturing about the disks did. The people who gestured did worse after the disk weights switched, but the people who moved the disks did not—they did just as well as before. “Gesture is a special case of action. You might think it would have less effect because it does not have a direct impact on the world,” says Goldin-Meadow. But she and Beilock think it may actually be having a stronger effect, “because gesturing about an act requires you to represent that act.” You aren’t just reaching out and handling the thing you’re talking about; you have to abstract from it, indicating it by a movement of your hands.

In the article published in Perspectives in Psychological Science, the two authors review the research on action, gesture, and thought. Gestures make thought concrete, bringing movement to the activity that’s going on in your mind.

This could be useful in education; Goldin-Meadow and Beilock have been working on helping children to understand abstract concepts in mathematics, physics, and chemistry by using gesture. “When you’re talking about angular momentum and torque, you’re talking about concepts that have to do with action,” Beilock says. “I’m really interested in whether getting kids to experience some of these actions or gesture about them might change the brain processes they use to understand these concepts.” But even in math where the concepts have little to do with action, gesturing helps children learn—maybe because the gestures themselves are grounded in action.

Association for Psychological Science


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One of the most enduring mysteries in solar physics is why the Sun's outer atmosphere, or corona, is millions of degrees hotter than its surface.

Now scientists believe they have discovered a major source of hot gas that replenishes the corona: jets of plasma shooting up from just above the Sun's surface.

The finding addresses a fundamental question in astrophysics: how energy is moved from the Sun's interior to create its hot outer atmosphere.

"It's always been quite a puzzle to figure out why the Sun's atmosphere is hotter than its surface," says Scott McIntosh, a solar physicist at the High Altitude Observatory of the National Center for Atmospheric Research (NCAR) in Boulder, Colo., who was involved in the study.

"By identifying that these jets insert heated plasma into the Sun's outer atmosphere, we can gain a much greater understanding of that region and possibly improve our knowledge of the Sun's subtle influence on the Earth's upper atmosphere."

The research, results of which are published this week in the journal Science, was conducted by scientists from Lockheed Martin's Solar and Astrophysics Laboratory (LMSAL), NCAR, and the University of Oslo. It was supported by NASA and the National Science Foundation (NSF), NCAR's sponsor.

"These observations are a significant step in understanding observed temperatures in the solar corona," says Rich Behnke of NSF's Division of Atmospheric and Geospace Sciences, which funded the research.

"They provide new insight about the energy output of the Sun and other stars. The results are also a great example of the power of collaboration among university, private industry and government scientists and organizations."

The research team focused on jets of plasma known as spicules, which are fountains of plasma propelled upward from near the surface of the Sun into the outer atmosphere.

For decades scientists believed spicules could send heat into the corona. However, following observational research in the 1980s, it was found that spicule plasma did not reach coronal temperatures, and so the theory largely fell out of vogue.

"Heating of spicules to millions of degrees has never been directly observed, so their role in coronal heating had been dismissed as unlikely," says Bart De Pontieu, the lead researcher and a solar physicist at LMSAL.

In 2007, De Pontieu, McIntosh, and their colleagues identified a new class of spicules that moved much faster and were shorter-lived than the traditional spicules.

These "Type II" spicules shoot upward at high speeds, often in excess of 100 kilometers per second, before disappearing.

The rapid disappearance of these jets suggested that the plasma they carried might get very hot, but direct observational evidence of this process was missing.

The researchers used new observations from the Atmospheric Imaging Assembly on NASA's recently launched Solar Dynamics Observatory and NASA's Focal Plane Package for the Solar Optical Telescope (SOT) on the Japanese Hinode satellite to test their hypothesis.

"The high spatial and temporal resolution of the newer instruments was crucial in revealing this previously hidden coronal mass supply," says McIntosh.

"Our observations reveal, for the first time, the one-to-one connection between plasma that is heated to millions of degrees and the spicules that insert this plasma into the corona."

The findings provide an observational challenge to the existing theories of coronal heating.

During the past few decades, scientists proposed a wide variety of theoretical models, but the lack of detailed observation significantly hampered progress.

"One of our biggest challenges is to understand what drives and heats the material in the spicules," says De Pontieu.

A key step, according to De Pontieu, will be to better understand the interface region between the Sun's visible surface, or photosphere, and its corona.

Another NASA mission, the Interface Region Imaging Spectrograph (IRIS), is scheduled for launch in 2012 to provide high-fidelity data on the complex processes and enormous contrasts of density, temperature and magnetic field between the photosphere and corona. Researchers hope this will reveal more about the spicule heating and launch mechanism.

The LMSAL is part of the Lockheed Martin Space Systems Company, which designs and develops, tests, manufactures and operates a full spectrum of advanced-technology systems for national security and military, civil government and commercial customers.

(Photo: NASA)

National Science Foundation


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Growing up poor can suppress a child's genetic potential to excel cognitively even before the age of 2, according to research from psychologists at The University of Texas at Austin.

Half of the gains that wealthier children show on tests of mental ability between 10 months and 2 years of age can be attributed to their genes, the study finds. But children from poorer families, who already lag behind their peers by that age, show almost no improvements that are driven by their genetic makeup.

The study of 750 sets of twins by Assistant Professor Elliot Tucker-Drob does not suggest that children from wealthier families are genetically superior or smarter. They simply have more opportunities to reach their potential.

These findings go to the heart of the age-old debate about whether "nature" or "nurture" is more important to a child's development. They suggest the two work together and that the right environment can help children begin to reach their genetic potentials at a much earlier age than previously thought.

"You can't have environmental contributions to a child's development without genetics. And you can't have genetic contributions without environment," says Tucker-Drob, who is also a research associate in the university's Population Research Center. "Socioeconomic disadvantages suppress children's genetic potentials."

The study, published in the journal Psychological Science, was co-authored by K. Paige Harden of The University of Texas at Austin, Mijke Rhemtulla of The University of Texas at Austin and the University of British Columbia, and Eric Turkheimer and David Fask of the University of Virginia.

The researchers looked at test results from twins who had taken a version of the Bayley Scales of Infant Development at about 10 months and again at about 2 years of age. The test, which is widely used to measure early cognitive ability, asks children to perform such tasks as pulling a string to ring a bell, putting three cubes in a cup and matching pictures.

At 10 months, there was no difference in how the children from different socioeconomic backgrounds performed. By 2 years, children from high socioeconomic background scored significantly higher than those from low socioeconomic backgrounds.

In general, the 2-year-olds from poorer families performed very similarly to one another. That was true among both fraternal and identical twins, suggesting that genetic similarity was unrelated to similarities in cognitive ability. Instead, their environments determine their cognitive success.

Among 2-year-olds from wealthier families, identical twins (who share identical genetic makeups) performed very similarly to one another. But fraternal twins were not as similar — suggesting their different genetic makeups and potentials were already driving their cognitive abilities.

"Our findings suggest that socioeconomic disparities in cognitive development start early," says Tucker-Drob. "For children from poorer homes, genetic influences on changes in cognitive ability were close to zero. For children from wealthier homes, genes accounted for about half of the variation in cognitive changes."

The study notes that wealthier parents are often able to provide better educational resources and spend more time with their children but does not examine what factors, in particular, help their children reach their genetic potentials. Tucker-Drob is planning follow-up studies to examine that question.

The University of Texas at Austin


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Researchers at North Carolina State University have created the first coils of silicon nanowire on a substrate that can be stretched to more than double their original length, moving us closer to incorporating stretchable electronic devices into clothing, implantable health-monitoring devices, and a host of other applications.

“In order to create stretchable electronics, you need to put electronics on a stretchable substrate, but electronic materials themselves tend to be rigid and fragile,” says Dr. Yong Zhu, one of the researchers who created the new nanowire coils and an assistant professor of mechanical and aerospace engineering at NC State. “Our idea was to create electronic materials that can be tailored into coils to improve their stretchability without harming the electric functionality of the materials.”

Zhu's research team has created the first coils of silicon nanowire on a substrate that can be stretched to more than double their original length, moving us closer to developing stretchable electronic devices.

Other researchers have experimented with “buckling” electronic materials into wavy shapes, which can stretch much like the bellows of an accordion. However, Zhu says, the maximum strains for wavy structures occur at localized positions – the peaks and valleys – on the waves. As soon as the failure strain is reached at one of the localized positions, the entire structure fails.

“An ideal shape to accommodate large deformation would lead to a uniform strain distribution along the entire length of the structure – a coil spring is one such ideal shape,” Zhu says. “As a result, the wavy materials cannot come close to the coils’ degree of stretchability.” Zhu notes that the coil shape is energetically favorable only for one-dimensional structures, such as wires.

Zhu’s team put a rubber substrate under strain and used very specific levels of ultraviolet radiation and ozone to change its mechanical properties, and then placed silicon nanowires on top of the substrate. The nanowires formed coils upon release of the strain. Other researchers have been able to create coils using freestanding nanowires, but have so far been unable to directly integrate those coils on a stretchable substrate.

While the new coils’ mechanical properties allow them to be stretched an additional 104 percent beyond their original length, their electric performance cannot hold reliably to such a large range, possibly due to factors like contact resistance change or electrode failure, Zhu says. “We are working to improve the reliability of the electrical performance when the coils are stretched to the limit of their mechanical stretchability, which is likely well beyond 100 percent, according to our analysis.”

(Photo: NCSU)

North Carolina State University


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In a groundbreaking achievement that could help scientists "build" new biological systems, Princeton University scientists have constructed for the first time artificial proteins that enable the growth of living cells.

The team of researchers created genetic sequences never before seen in nature, and the scientists showed that they can produce substances that sustain life in cells almost as readily as proteins produced by nature's own toolkit.

"What we have here are molecular machines that function quite well within a living organism even though they were designed from scratch and expressed from artificial genes," said Michael Hecht, a professor of chemistry at Princeton, who led the research. "This tells us that the molecular parts kit for life need not be limited to parts -- genes and proteins -- that already exist in nature."

The work, Hecht said, represents a significant advance in synthetic biology, an emerging area of research in which scientists work to design and fabricate biological components and systems that do not already exist in the natural world. One of the field's goals is to develop an entirely artificial genome composed of unique patterns of chemicals.

"Our work suggests," Hecht said, "that the construction of artificial genomes capable of sustaining cell life may be within reach."

Nearly all previous work in synthetic biology has focused on reorganizing parts drawn from natural organisms. In contrast, Hecht said, the results described by the team show that biological functions can be provided by macromolecules that were not borrowed from nature, but designed in the laboratory.

Although scientists have shown previously that proteins can be designed to fold and, in some cases, catalyze reactions, the Princeton team's work represents a new frontier in creating these synthetic proteins.

The research, which Hecht conducted with three former Princeton students and a former postdoctoral fellow, is described in a report published online Jan. 4 in the journal Public Library of Science ONE.

Hecht and the students in his lab study the relationship between biological processes on the molecular scale and processes at work on a larger magnitude. For example, he is studying how the errant folding of proteins in the brain can lead to Alzheimer's disease, and is involved in a search for compounds to thwart that process. In work that relates to the new paper, Hecht and his students also are interested in learning what processes drive the routine folding of proteins on a basic level -- as proteins need to fold in order to function -- and why certain key sequences have evolved to be central to existence.

Proteins are the workhorses of organisms, produced from instructions encoded into cellular DNA. The identity of any given protein is dictated by a unique sequence of 20 chemicals known as amino acids. If the different amino acids can be viewed as letters of an alphabet, each protein sequence constitutes its own unique "sentence."

And, if a protein is 100 amino acids long (most proteins are even longer), there are an astronomically large number of possibilities of different protein sequences, Hecht said. At the heart of his team's research was to question how there are only about 100,000 different proteins produced in the human body, when there is a potential for so many more. They wondered, are these particular proteins somehow special? Or might others work equally well, even though evolution has not yet had a chance to sample them?

Hecht and his research group set about to create artificial proteins encoded by genetic sequences not seen in nature. They produced about 1 million amino acid sequences that were designed to fold into stable three-dimensional structures.

"What I believe is most intriguing about our work is that the information encoded in these artificial genes is completely novel -- it does not come from, nor is it significantly related to, information encoded by natural genes, and yet the end result is a living, functional microbe," said Michael Fisher, a co-author of the paper who earned his Ph.D. at Princeton in 2010 and is now a postdoctoral fellow at the University of California-Berkeley. "It is perhaps analogous to taking a sentence, coming up with brand new words, testing if any of our new words can take the place of any of the original words in the sentence, and finding that in some cases, the sentence retains virtually the same meaning while incorporating brand new words."

Once the scientists had created this new library of artificial proteins, they inserted those proteins into various mutant strains of bacteria in which certain natural genes previously had been deleted. The deleted natural genes are required for survival under a given set of conditions, including a limited food supply. Under these harsh conditions, the mutant strains of bacteria died -- unless they acquired a life-sustaining novel protein from Hecht's collection. This was significant because formation of a bacterial colony under these selective conditions could occur only if a protein in the collection had the capacity to sustain the growth of living cells.

In a series of experiments exploring the role of differing proteins, the scientists showed that several different strains of bacteria that should have died were rescued by novel proteins designed in the laboratory. "These artificial proteins bear no relation to any known biological sequences, yet they sustained life," Hecht said.

Added Kara McKinley, also a co-author and a 2010 Princeton graduate who is now a Ph.D. student at the Massachusetts Institute of Technology: "This is an exciting result, because it shows that unnatural proteins can sustain a natural system, and that such proteins can be found at relatively high frequency in a library designed only for structure."

In addition to Hecht, Fisher and McKinley, other authors on the paper include Luke Bradley, a former postdoctoral fellow in Hecht's lab who is now an assistant professor at the University of Kentucky, and Sara Viola, a 2008 Princeton graduate who is now a medical student at Columbia University.

(Photo: Brian Wilson)

Princeton University




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