New tool gives structural strength to 3-D printed works

ScienceDaily (Sep. 18, 2012) — Objects created using 3-D printing have a common flaw: They are fragile and often fall apart or lose their shape.

"I have an entire zoo of broken 3-D printed objects in my office," said Bedrich Benes, an associate professor of computer graphics at Purdue University.

The printed fabrications often fail at points of high stress.

"You can go online, create something using a 3-D printer and pay $300, only to find that it isn't strong enough to survive shipping and arrives in more than one piece," said Radomir Mech, senior research manager from Adobe's Advanced Technology Labs.

The 3-D printers create shapes layer-by-layer out of various materials, including metals and plastic polymers. Whereas industry has used 3-D printing in rapid prototyping for about 15 years, recent innovations have made the technology practical for broader applications, he said.

"Now 3-D printing is everywhere," Benes said. "Imagine you are a hobbyist and you have a vintage train model. Parts are no longer being manufactured, but their specifications can be downloaded from the Internet and you can generate them using a 3-D printer."

The recent rise in 3-D printing popularity has been fueled by a boom in computer graphics and a dramatic reduction of the cost of 3-D printers, Benes said.

Researchers at Purdue and Adobe's Advanced Technology Labs have jointly developed a program that automatically imparts strength to objects before they are printed.

"It runs a structural analysis, finds the problematic part and then automatically picks one of the three possible solutions," Benes said.

Findings were detailed in a paper presented during the SIGGRAPH 2012 conference in August. Former Purdue doctoral student Ondrej Stava created the software application, which automatically strengthens objects either by increasing the thickness of key structural elements or by adding struts. The tool also uses a third option, reducing the stress on structural elements by hollowing out overweight elements.

"We not only make the objects structurally better, but we also make them much more inexpensive," Mech said. "We have demonstrated a weight and cost savings of 80 percent."

The new tool automatically identifies "grip positions" where a person is likely to grasp the object. A "lightweight structural analysis solver" analyzes the object using a mesh-based simulation. It requires less computing power than traditional finite-element modeling tools, which are used in high-precision work such as designing jet engine turbine blades.

"The 3-D printing doesn't have to be so precise, so we developed our own structural analysis program that doesn't pay significant attention to really high precision," Benes said.

The paper was authored by Stava, now a computer scientist at Adobe, doctoral student Juraj Vanek; Benes; Mech; and Nathan Carr, a principal scientist at Adobe's Advanced Technology Labs.

Future research may focus on better understanding how structural strength is influenced by the layered nature of 3-D-printed objects. The researchers may also expand their algorithms to include printed models that have moving parts.

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The above story is reprinted from materials provided by Purdue University. The original article was written by Emil Venere.

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19 Sep, 2012

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Quasars: Mileposts marking the universe's expansion

ScienceDaily (Sep. 18, 2012) — Scientists can't travel deep space the way Columbus sailed and charted the New World or Lewis and Clark mapped the west. But, researchers at Case Western Reserve University and two partnering institutions have found a possible way to map the spread and structure of the universe, guided by the light of quasars.

The technique, combined with the expected discovery of millions more far-away quasars over the next decade, could yield an unprecedented look back to a time shortly after the Big Bang, when the universe was a fraction the size it is today.

Researchers found the key while analyzing the visible light from a small group of quasars.

Patterns of light variation over time were consistent from one quasar to another when corrected for the quasar's redshift. This redshift occurs because an expanding universe carries the quasars away from us, thus making the light from them appear redder (hence the term), and also making the time variations appear to occur more slowly.

Turning this around, by measuring the rate at which a quasar's light appears to vary and comparing this rate to the standard rate at which quasars sampled actually vary, the researchers were able to infer the redshift of the quasar.

Knowing the quasar redshift enables the scientists to calculate the relative size of the universe when the light was emitted, compared to today.

"It appears we may have a useful tool for mapping out the expansion history of the universe," said Glenn Starkman, a physics professor at Case Western Reserve and an author of the study, published this summer in Physical Review Letters.

"If we could measure the redshifts of millions of quasars, we could use them to map the structures in the universe out to a large redshift."

The larger the redshift, the farther and older the light source.

The group plans to seek larger samples of quasars, to confirm the patterns are consistent and can be used to calculate their redshifts everywhere across the universe.

The work was led by De-Chang Dai, who earned his PhD working with Starkman and was most recently a member of the Astrophysics, Cosmology and Gravity Centre, University of Cape Town. The other authors include Amanda Weltman, PhD, a senior cosmology lecturer at the Centre, and brothers Branislav Stojkovic, a doctoral student in computer science and engineering, and Dejan Stojkovic, a physics professor at the State University of New York at Buffalo. Dejan Stojkovic also earned his PhD with Starkman and was later a visiting assistant professor at Case Western Reserve.

The scientists graphed the amount of light from 14 quasars recorded by the Massive Compact Halo Objects project, which sought evidence of dark matter in and around the Milky Way. Light from each quasar was measured repeatedly over hundreds of days.

Graphing revealed phases during which the amount of light would either increase or decrease in a linear fashion over an extended period of time.

Although other properties varied, the rate at which the measurable light changed was nearly identical among all 14 quasars, once scientists corrected for the effects of the universe's expansion.

"It's as if there was a dimmer switch on them with someone turning it to the left then the right," Starkman said. "The overall trend was surprisingly consistent."

This consistency of patterns enabled the scientists to accurately calculate the cosmological redshift of one quasar from another.

The researchers tested this capability in two ways.

They fit segments of the light curves, that is, the measured light over time, to straight lines. The slopes of the lines were consistent and appeared to be directly related to the quasars' redshifts.

By comparing corresponding slopes of 13 quasars with a known redshift value to the slopes of one other quasar, the researchers could calculate the redshift of the lone quasar within two percentage points.

In a second approach, the researchers took large sections of the light curves of two quasars and concentrated on the segments that matched most closely. By varying the ratio of the redshifts of the two quasars to try to get the best possible match of the two light curves, they were able to determine the ratio of the quasars' redshifts to within 1.5 percentage points.

Astronomers have used the bright light of supernovae with redshifts up to about 1.7 to measure the accelerating expansion of the universe. A star with a redshift of 1.7 would have been emitting that light when the universe was 2.7 times smaller than today.

Quasars are older and farther away and have been measured with redshifts of up to 7.1, which means they emitted the light we are seeing when the universe was as small as one-eighth the size it is today.

If this method of determining quasar redshifts proves applicable to higher redshift quasars, scientists could have millions of markers to trace the growth and evolution of structure and the expansion of the universe out to large distances and early times.

"This could help us learn about how gravity has assembled structure in the universe." Starkman said. "And, the rate of structure growth can help us determine whether dark energy or modified laws of gravity drive the accelerated expansion of the universe."

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Journal Reference:

1. De-Chang Dai, Glenn Starkman, Branislav Stojkovic, Dejan Stojkovic, Amanda Weltman. Using Quasars as Standard Clocks for Measuring Cosmological Redshift. Physical Review Letters, 2012; 108 (23) DOI: 10.1103/PhysRevLett.108.231302

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18 Sep, 2012

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Tasered youth fare as well as adults, study finds

ScienceDaily (Sep. 18, 2012) — Adolescents who are tasered by law enforcement officers do not appear to be at higher risk for serious injury than adults, according to new a new study from Wake Forest Baptist Medical Center researchers.

This latest research from Wake Forest Baptist is the first to specifically investigate Taser use on adolescents. Lead author Alison R. Gardner, M.D., an assistant professor of emergency medicine at Wake Forest Baptist, found no major differences in the injury rates or types of injuries to youth when compared to adults.

"We were looking closely for increased risk of cardiac effects and bodily injuries because of the differing body size and build of adolescents, but there were no significant injuries reported for this age group," said Gardner. "There were 20 mild injuries recorded and the majority of these were expected superficial puncture wounds from the weapons' probes."

The research appears this month online ahead of print in Pediatric Emergency Care. This was a retrospective study of Taser use from law enforcement data collected by the largest, independent multicenter database established in 2005 with funding by the National Institute of Justice. Tasers, or conducted electrical weapons, are non-lethal defense weapons used by law enforcement personnel to shock a person with probes from a distance.

Gardner and colleagues reviewed 2,026 Taser uses and found that 100, or 4.9 percent, were against adolescent suspects ranging in age from 13 to 17, with an average age of 16. Most of the youth were tasered by law enforcement officers during incidents involving civil disturbance, assault, robbery and burglary. Alcohol or other drug intoxication was known or suspected by police in 30 of the 100 cases, according to the study.

A limitation of the study is that the mean age (16), weight (168 pounds) and height (5 feet 8 inches tall) of the individuals reviewed indicates that this "population of minors mirrored the physiology of older adolescents and adults, more so than that of young or small children," Gardner said. "In real-life situations, Tasers were used in adolescents who were larger and older. This implies that law enforcement personnel are using Tasers as apprehension aids when physical apprehension is not easily accomplished, as would be the case in smaller and younger subjects."

This latest research builds on the work of its senior author William P. Bozeman, M.D., also of Wake Forest Baptist, who conducted the world's first large, independent study of injuries associated with Tasers to assess the overall risk and severity of injuries in real world conditions. Published in 2009, those results showed that the rate of significant injuries was low (less than 1 percent) and most injuries appeared to be minor.

Bozeman followed up with additional research in 2009 that evaluated the immediate cardiac and cardiovascular effects on a group of volunteer police officers, finding that CEW exposure overall was safe and well tolerated. His was only the second study to document the heart rhythm before, during and after a Taser application. In June he published a new study of real-life Taser uses by law enforcement agencies and found none in which the devices could be linked to cardiac complications, even when the probes landed on the upper chest area.

"Tasers have been proven to reduce the risk of injury in both suspects and officers and have prevented far more injuries and deaths than they have produced," said Bozeman. "While no tool is risk free, Tasers are clearly safer than alternate force options available to law enforcement officers such as batons, hand-to-hand combat and firearms, and the appropriate use of Tasers by police officers should be supported." William E. Hauda II, M.D., operational medical director, Fairfax County Police Department, Va., was also a co-author.

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Journal Reference:

1. Alison R. Gardner, William E. Hauda, William P. Bozeman. Conducted Electrical Weapon (TASER) Use Against Minors. Pediatric Emergency Care, 2012; 28 (9): 873 DOI: 10.1097/PEC.0b013e31826763d1

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18 Sep, 2012

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Canadian homes a kill zone for up to 22 million birds a year, researchers estimate

ScienceDaily (Sep. 14, 2012) — The thud of a bird hitting a window is something many Canadian home owners experience. Up until now, little research has been done to document the significant these collisions for Canada's bird populations. A University of Alberta biology class project supervised by researcher Erin Bayne suggests that many birds meet their end in run-ins with Canadian homes.

The U of A students estimate a staggering 22 million birds a year die from colliding with windows of homes across the country.

The research was done in Edmonton and surrounding area using evidence gathered from more than 1,700 homeowners. Homeowners were recruited to become citizen scientists for the study. The citizen scientists were required to complete an online survey where they were asked to recall fatal bird hits over the previous year.

Bayne and his team processed the Edmonton data and concluded that with approximately 300,000 homes in the study area the death toll for birds from window strikes might reach 180,000 per year.

The researchers applied that figure to national housing statistics and arrived at the 22 million figure for bird vs. window fatalities. Bayne says that many people recalled bird strikes at their homes, but there was little awareness that residential window deaths might affect bird populations.

The main factors influencing the frequency of bird -- window collisions were the age of the trees in the yard and whether or not people fed birds.

"In many cases people who go out of their way to help birds by putting up feeders and bird friendly plants are unwittingly contributing to the problem," said Bayne.

One tip the researchers have for the safer placement of a bird feeder concerns its distance from the house. Bayne says the safety factor has to do with a bird's flying speed. As with car crashes; speed kills.

"A feeder three to four metres from a window is bad because the bird has space to pickup lots of speed as it leaves the feeder," said Bayne.

Fast-flying birds like sparrows and chickadees and aggressive birds like robins are apt to collide with windows placed too close to free food.

Placing the feeder either closer or much further are options.

Researchers believe many window collisions are caused by in-flight mistakes. "It's called a panic flight; a bird startled by a cat or competing with other birds at the feeder may suddenly take flight and doesn't recognize the window as a hazard" said Bayne.

The research was published in the journal Wildlife Research.

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The above story is reprinted from materials provided by University of Alberta. The original article was written by Brian Murphy.

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Journal Reference:

1. Erin M. Bayne, Corey A. Scobie and Michael Rawson-Clark. Factors influencing the annual risk of bird–window collisions at residential structures in Alberta, Canada. Wildlife Research, 2012 [link]

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15 Sep, 2012

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The jacket that talks to Facebook in an emergency

ScienceDaily (Sep. 17, 2012) — In an emergency situation, we cannot expect rescue crews to do their jobs while fumbling with a tiny mobile phone when they need to read and send messages. Instead the scientists decided to create a prototype jacket that could communicate with Facebook.

Collision. Fire. Accidents. Chaos. In a rescue operation, it's no use trying to communicate via a small mobile phone display. But a jacket -- now you're talking!

The EU Societies project is all about technology and communication in extreme situations, such as rescue operations following major accidents. ICT researchers at SINTEF have been working on this topic for a long time, and the idea of developing a physical user interface for social media came from seeing how limited a normal mobile phone is as an aid during a chaotic emergency situation.

Screen is a minus in an emergency Most of our focus when we use computers is on the screen. We communicate via a display. But in an emergency situation, we cannot expect rescue crews to do their jobs while fumbling with a tiny mobile phone when they need to read and send messages. It doesn't just require full concentration -- it also requires two hands.

Similarly, a firefighter called out to an emergency doesn't have time to put on anything special -- he or she just grabs a jacket and helmet, and runs. "Crews therefore need devices with a much simpler user interface. That was the basic idea behind making the jackets," says researcher Babak Farshchian of SINTEF ICT.

BlueTooth A group of students at the Norwegian University of Science and Technology's (NTNU) Department of Computer and Information Science (IDI) decided to create a prototype jacket that could communicate with Facebook, and have been working on the assignment for the last six months. They decided to use the Arduino platform to create the physical user interface with social media. Arduino is a popular system used to develop physical prototypes that integrate with ICT. The platform that supports the jacket communicates with an ordinary Android mobile phone via BlueTooth. This means that the user does not get tangled in cables.

Keyboard in the sleeve They bought a simple lined jacket from a popular sports retailer called XXL, and inserted the cables and sensors between the inner and outer layers. Then they put a battery-operated circuit in the pocket, which controls the sensors and microphone. All the cables and electronics are concealed from the user. Instead of a telephone display, the jacket sleeve has a display sewn into it, showing a line of rolling text. The user will also feel a vibration in his or her neck, made via a small vibrator inserted in the collar. A vibration means that the person has received a message, which he or she can read by lifting an arm and looking at the display. Rescue work is often carried out in large groups, with professionals from different units and organizations that need to communicate and coordinate their actions efficiently during a rescue operation. "By using social media technology, we can enable these groups to communicate, and this jacket with a similar, customized user interface makes it easy and practical to use more advanced ICT in demanding rescue work," says Farshchian.

Better adapted to needs Easier access to social media is an idea that could be of interest to those with sight and hearing impairments, since these groups have problems using a screen. Being able to dictate and hear messages would not only be more user friendly, but also better adapted to their needs.

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17 Sep, 2012

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Damaged metal surfaces repair themselves

ScienceDaily (Sep. 17, 2012) — A coating filled with tiny lubricant capsules could come to the rescue when metal surfaces dry out and friction builds up.

A ball bearing -- or a slide bearing around an axle -- needs lubricating at all times. If a leak causes the lubrication in the bearings of large machines to dry out, there can be huge cost implications. Metal surfaces can grate against each other and seize up, in the worst case resulting in a total write-off. Wind turbines, for example, have high maintenance costs, of which overhaul of their mechanical components alone accounts for 30 per cent. Other cost savings for the industry involve energy consumption, personnel, lubrication expenses and maintenance and spare parts.

Lubrication in tiny capsules

As part of an internal project at the Gemini Tribology Centre (friction, wear, lubrication), a group of researchers from SINTEF and the Norwegian University of Science and Technology (NTNU) have spent two years building ground-breaking expertise in coatings and thermal spraying. The researchers are now testing whether it is possible -- where two metal surfaces are in contact with each other -- to apply a coating to the surfaces formed of hard particles and capsules filled with liquid lubricant. "We apply the lubricant using a thermal spray technique, where powder and capsules are fired at the surface using a flame," says Sergio Armada of SINTEF Materials and Chemistry. "When the metal surfaces come into contact with each other, the coating is broken down in a controlled manner, releasing the contents of the capsules, and the lubricant will then prevent further friction."

The researchers have carried out a number of tests on slide bearings in industrial settings, in which they have measured friction on surfaces with and without the capsules. When a coating without capsules was applied to the slide bearing, the friction coefficient was 0.7, while friction was reduced to 0.15 in bearings coated with a layer of capsules.

Industry on the lookout

The idea of self-repairing metals is not a new one. Two years ago, a metallic coating of capsules and the "electroplated layer" lubrication method was presented in the Economist magazine. Materials researchers from Fraunhofer and the University of Stuttgart were behind the article. The disadvantage of this method was that since the lubrication was applied using electricity, it was only possible to apply a single metallic layer.

Another challenge was that the capsules in the coating were too big. Since a surface layer should preferably be only 15-20 micrometres thick, the capsules must be a fraction of this size if they are not to be released too quickly.

"In our case, the capsules must be smaller than 10 micrometres, so that they do not block the nozzles and cause problems during the spraying process. We have now created capsules as small as 2 micrometres," says SINTEF researcher Christian Simon.

His colleague Ruth Schmid is producing capsules with an extremely low friction coefficient that could prove to provide the coating with even better tribological properties.

Many applications

"Our method has many potential applications, and is suitable for a wide range of coatings," says researcher Sergio Armada. "It will be possible to apply the coating to large surfaces and components, and the actual material of the coating can also be varied -- from metals to polymers and ceramics."

Armada thinks that the coating could also be used in the medical sector in hip and knee replacements. These are also places where surfaces move against each other, and grating can occur if there is not enough fluid in the joint. Patients would therefore benefit from lubricants applied in a coating of capsules which is sprayed onto the implant before it is inserted. Nuria Espallargas and Ragnhild Aune of NTNU are working on new materials that have capsules filled with medication or antibiotics that can be released when they are needed. The project has now come to an end, but the parties have written a project proposal and applied to the EU to be able to continue their work on thermal spraying and biocompatible coatings.

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17 Sep, 2012

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Improved positioning indoors

ScienceDaily (Sep. 17, 2012) — Whether you're walking, biking or driving, navigation systems can help you get from A to B -- as long as you have a GPS signal. This positioning technology usually works fine in both urban and rural outdoor areas, but it is of limited use indoors. To find our way around large and complex buildings like hospitals or airports, we often need to rely on vague signs.

Researchers at Technische Universität München (TUM) have come up with a new technology. The NAVVIS system uses visual information and realistic 3D images to point users in the right direction.

The NAVVIS positioning system is primarily based on visual information. The TUM researchers had to develop a special location recognition system for this project. They started by taking photos of a building, simultaneously mapping prominent features like stairs and signs. A smartphone app then lets users view the map images to find their current location. All they have to do is take a photo of their surroundings. The program then compares the photo with the images stored in its database and works out the user's exact position (down to the nearest meter) and the direction in which they are facing. The app uses arrows to point the way in a 3D view.

NAVVIS is currently being tested at TUM: "With multiple floors and winding corridors, the main campus is something of a maze after several decades of expansion. This makes it an ideal testing ground for NAVVIS," declares Georg Schroth, who is heading up the project at TUM's Institute for Media Technology. NAVVIS has other potential uses besides navigation, as his colleague Robert Huitl explains: "The software can also be used for augmented reality applications if you add on special programs. So for instance, visitors to the Louvre would not only be able to locate the Mona Lisa, but also view information about the painting or find directions to other works by da Vinci." Another possibility would be virtual tours on a PC or smartphone.

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18 Sep, 2012

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How birds master courtship songs: Zebra finches shed light on brain circuits and learning

ScienceDaily (Sep. 17, 2012) — By studying how birds master songs used in courtship, scientists at Duke University have found that regions of the brain involved in planning and controlling complex vocal sequences may also be necessary for memorizing sounds that serve as models for vocal imitation.

In a paper appearing in the September 2012 issue of the journal Nature Neuroscience, researchers at Duke and Harvard universities observed the imitative vocal learning habits of male zebra finches to pinpoint which circuits in the birds' brains are necessary for learning their songs.

Knowing which brain circuits are involved in learning by imitation could have broader implications for diagnosing and treating human developmental disorders, the researchers said. The finding shows that the same circuitry used for vocal control also participates in auditory learning, raising the possibility that vocal circuits in our own brain also help encode auditory experience important to speech and language learning.

"Birds learn their songs early in life by listening to and memorizing the song of their parent or other adult bird tutor, in a process similar to how humans learn to speak," said Todd Roberts, Ph.D., the study's first author and postdoctoral associate in neurobiology at Duke University. "They shape their vocalizations to match or copy the tutor's song."

A young male zebra finch, Roberts said, learns his song in two phases -- memorization and practice. He said the pupil can rapidly memorize the song of an adult tutor, but may need to practice singing as many as 100,000 times in a 45-day period in order to accurately imitate the tutor's song.

During the study, voice recognition software was paired with optogenetics, a technology that combines genetics and optics to control the electrical activity of nerve cells, or neurons. Using these tools, the researchers were able to scramble brain signals coordinating small sets of neurons in the young bird's brain for a few hundred milliseconds while he was listening to his teacher, enabling them to test which brain regions were important during the learning process.

The study's results show that a song pre-motor region in the pupil's brain plays two different roles. Not only does it control the execution of learned vocal sequences, it also helps encode information when the pupil is listening to his tutor, Roberts said.

"We learn some of our most interesting behaviors, including language, speech and music, by listening to an appropriate model and then emulating this model through intensive practice," said senior author Richard Mooney, Ph.D., professor of neurobiology and member of the Duke Institute for Brain Sciences. "A traditional view is that this two-step sequence -- listening followed by motor rehearsal -- first involves activation by the model of brain regions important to auditory processing. This is followed days, weeks or even months later by activation of brain regions important to motor control."

"Here we found that a brain region that is essential to the motor control of song also has an essential role in helping in auditory learning of the tutor song," Mooney said. "This finding raises the possibility that the premotor circuits important to planning and controlling speech in our own brains also play an important role in auditory learning of speech sounds during early infancy." This brain region, known as Broca's area, is located in the frontal lobe of the left hemisphere.

The research has implications for the role of premotor circuits in the brain and suggests that these areas are important targets to consider when assessing developmental disorders that affect speech, language and other imitative behaviors in humans, Roberts said.

In addition to Roberts and Mooney, study authors include Sharon M. H. Gobes of Harvard University and Wellesley College; Malavika Murugan of Duke; and Bence P. Ölveczky of Harvard.

The research was supported by grants from the National Science Foundation and the National Institutes of Health (R01 DC02524) to Richard Mooney; and grants from NIH (R01 NS066408) and the Klingenstein, Sloan and McKnight Foundations to Bence P. Ölveczky; and a Rubicon fellowship from the Netherlands Organization for Scientific Research to Sharon M.H. Gobes.

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Journal Reference:

1. Todd F Roberts, Sharon M H Gobes, Malavika Murugan, Bence P Ölveczky, Richard Mooney. Motor circuits are required to encode a sensory model for imitative learning. Nature Neuroscience, 2012; DOI: 10.1038/nn.3206

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18 Sep, 2012

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Sex matters: Men recognize cars and women recognize living things best, psychological analysis finds

ScienceDaily (Sep. 17, 2012) — Women are better than men at recognizing living things and men are better than women at recognizing vehicles.

That is the unanticipated result of an analysis Vanderbilt psychologists performed on data from a series of visual recognition tasks collected in the process of developing a new standard test for expertise in object recognition.

"These results aren't definitive, but they are consistent with the following story," said Gauthier. "Everyone is born with a general ability to recognize objects and the capability to get really good at it. Nearly everyone becomes expert at recognizing faces, because of their importance for social interactions. Most people also develop expertise for recognizing other types of objects due to their jobs, hobbies or interests. Our culture influences which categories we become interested in, which explains the differences between men and women."

The results were published online on Aug. 3 in the Vision Research journal in an article titled, "The Vanderbilt Expertise Test Reveals Domain-General and Domain-Specific Sex Effects in Object Recognition."

"Our motivation was to assess the role that expertise plays in object recognition with a new test that includes many different categories, so we weren't looking for this result," said Professor of Psychology Isabel Gauthier. She directs the lab where post-doctoral fellow Rankin McGugin conducted the study.

"This isn't the first time that sex differences have been found in perceptual tasks. For example, previous studies have shown that men have an advantage in mental rotation tasks. In fact, a recent study looking only at car recognition found that men were better than women but attributed this to the male advantage in mental rotation. Our finding that women are better than men at recognizing objects in other categories suggests that this explanation is incorrect."

Discovery of the sex effect in object recognition also casts doubt on several studies that claim an individual's ability to recognize faces is largely independent of his or her ability to recognize objects.

"Face recognition abilities are exciting to study because they have been found to have a clear genetic basis," said Gauthier, "and many studies conclude that abilities in face recognition are not predicted by abilities in object recognition. But this is usually based on comparing faces to only one object category for men and women."

It took the multi-category analysis to reveal that face recognition abilities are correlated to the ability to recognize different object categories for men and women. For example, men who are better at recognizing vehicles also tend to be better at recognizing faces, while women who are better at recognizing living things tend to be better at recognizing faces.

The researchers modeled their new test after the well-established Cambridge Face Memory Task, which effectively measures a person's ability to recognize faces. After familiarizing themselves with a number of images, participants are shown three images at a time -- one from the study group and two that they haven't seen before -- and then are asked to pick out the image that they had studied.

While one goal of the new study was to compare object and face recognition skills, another goal was to develop a better way to measure who has exceptional skills in one domain: how to find the experts in the recognition of cars or birds or even mushrooms. To do this, the Vanderbilt researchers reasoned that performance on any category of interest needed to be compared to performance on many other categories, to ensure that the self-proclaimed bird expert is not only better with birds than most people, but also better with birds than with most other categories. So they designed the new test with eight categories of visually similar objects: leaves, owls, butterflies, wading birds, mushrooms, cars, planes and motorcycles.

To evaluate the new test, they administered it to 227 subjects -- 75 male and 82 female -- with a mean age of 23. When the results of the entire group were analyzed, the researchers found that increasing the number of categories revealed a large sex difference: Women proved significantly better at recognizing living things while men were better at recognizing vehicles. In addition, the researchers administered a face recognition test to about half of the participants, which allowed them to determine the correlation between vehicle recognition and face recognition in men and the correlation between recognition of living things and faces in women.

Vanderbilt post-doctoral fellow Jennifer Richler as well as Grit Herzmann, a post-doctoral fellow at the University of Colorado, Boulder and Research Assistant Magen Speegle also contributed to the study.

The research was supported by the National Eye Institute grants EYO13441-06A2 and P30-EY008126 and by the National Science Foundation's Temporal Dynamics of Learning Center grant SBE-0542013.

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The above story is reprinted from materials provided by Vanderbilt University.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

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Journal Reference:

1. Rankin W. McGugin, Jennifer J. Richler, Grit Herzmann, Magen Speegle, Isabel Gauthier. The Vanderbilt Expertise Test reveals domain-general and domain-specific sex effects in object recognition. Vision Research, 2012; 69: 10 DOI: 10.1016/j.visres.2012.07.014

Note: If no author is given, the source is cited instead.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

18 Sep, 2012

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Source: http://feeds.sciencedaily.com/~r/sciencedaily/strange_science/~3/GiRG07ulFyE/120917132022.htm
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How bees decide what to be: Reversible 'epigenetic' marks linked to behavior patterns

ScienceDaily (Sep. 16, 2012) — Johns Hopkins scientists report what is believed to be the first evidence that complex, reversible behavioral patterns in bees -- and presumably other animals -- are linked to reversible chemical tags on genes.

The scientists say what is most significant about the new study, described online September 16 in Nature Neuroscience, is that for the first time DNA methylation "tagging" has been linked to something at the behavioral level of a whole organism. On top of that, they say, the behavior in question, and its corresponding molecular changes, are reversible, which has important implications for human health.

According to Andy Feinberg, M.D., M.P.H., Gilman scholar, professor of molecular medicine and director of the Center for Epigenetics at Hopkins' Institute for Basic Biomedical Sciences, the addition of DNA methylation to genes has long been shown to play an important role in regulating gene activity in changing biological systems, like fate determination in stem cells or the creation of cancer cells. Curious about how epigenetics might contribute to behavior, he and his team studied a tried-and-true model of animal behavior: bees.

Working with bee expert Gro Amdam, Ph.D., associate professor of life sciences at Arizona State University and the Norwegian University of Life Sciences, Feinberg's epigenetics team found significant differences in DNA methylation patterns in bees that have identical genetic sequences but vastly different behavioral patterns.

Employing a method that allows the researchers to analyze the whole genome at once, dubbed CHARM (comprehensive high-throughput arrays for relative methylation), the team analyzed the location of DNA methylations in the brains of worker bees of two different "professions." All worker bees are female and, within a given hive, are all genetically identical sisters. However, they don't all do the same thing; some nurse and some forage.

Nurses are generally younger and remain in the hive to take care of the queen and her larvae. When nurses mature, they become foragers that leave the hive to gather pollen and other supplies for the hive. "Genes themselves weren't going to tell us what is responsible for the two types of behavior," Feinberg says. "But epigenetics -- and how it controls genes -- could."

Feinberg and Amdam started their experiment with new hives populated by bees of the same age. That removed the possibility that any differences they might find could be attributed to differences of age. "When young, age-matched bees enter a new hive, they divvy up their tasks so that the right proportion becomes nurses and foragers," explains Amdam. It is these two populations that were tested after painstakingly characterizing and marking each bee with its "professional," or behavioral, category.

Analyzing the patterns of DNA methylation in the brains of 21 nurses and 21 foragers, the team found 155 regions of DNA that had different tag patterns in the two types of bees. The genes associated with the methylation differences were mostly regulatory genes known to affect the status of other genes. "Gene sequences without these tags are like roads without stop lights -- gridlock," says Feinberg.

Once they knew differences existed, they could take the next step to determine if they were permanent. "When there are too few nurses, the foragers can step in and take their places, reverting to their former practices," says Amdam. The researchers used this strategy to see whether foraging bees would maintain their foraging genetic tags when forced to start acting like nurses again. So they removed all of the nurses from their hives and waited several weeks for the hive to restore balance.

That done, the team again looked for differences in DNA methylation patterns, this time between foragers that remained foragers and those that became nurses. One hundred and seven DNA regions showed different tags between the foragers and the reverted nurses, suggesting that the epigenetic marks were not permanent but reversible and connected to the bees' behavior and the facts of life in the hive.

Dramatically, Feinberg noted, more than half of those regions had already been identified among the 155 regions that change when nurses mature into foragers. These 57 regions are likely at the heart of the different behaviors exhibited by nurses and foragers, says Amdam. "It's like one of those pictures that portray two different images depending on your angle of view," she says. "The bee genome contains images of both nurses and foragers. The tags on the DNA give the brain its coordinates so that it knows what kind of behavior to project."

The researchers say they hope their results may begin to shed light on complex behavioral issues in humans, such as learning, memory, stress response and mood disorders, which all involve interactions between genetic and epigenetic components similar to those in the study. A person's underlying genetic sequence is acted upon by epigenetic tags, which may be affected by external cues to change in ways that create stable -- but reversible -- behavioral patterns.

Authors on the paper include Brian Herb, Kasper Hansen, Martin Aryee, Ben Langmead, Rafael Irizarry and Andrew Feinberg from The Johns Hopkins University, and Florian Wolschin and Gro Amdam of the Norwegian University of Life Sciences and Arizona State University.

This work was funded through the NIH Director's Pioneer Award through the National Institute of Environmental Health Sciences (#DP1ES022579), the Research Council of Norway and the Pew Charitable Trust.

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The above story is reprinted from materials provided by Johns Hopkins Medicine, via Newswise.

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Journal Reference:

1. Brian R Herb, Florian Wolschin, Kasper D Hansen, Martin J Aryee, Ben Langmead, Rafael Irizarry, Gro V Amdam, Andrew P Feinberg. Reversible switching between epigenetic states in honeybee behavioral subcastes. Nature Neuroscience, 2012; DOI: 10.1038/nn.3218

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Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

17 Sep, 2012

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Source: http://feeds.sciencedaily.com/~r/sciencedaily/strange_science/~3/EWXP9thK5nU/120916160845.htm
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