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Skeletal remains of 24,000-year-old boy raise new questions about first Americans

Nov. 20, 2013 — Results from a DNA study of a young boy's skeletal remains believed to be 24,000 years old could turn the archaeological world upside down -- it's been demonstrated that nearly 30 percent of modern Native American's ancestry came from this youngster's gene pool, suggesting First Americans came directly from Siberia, according to a research team that includes a Texas A&M University professor.

Kelly Graf, assistant professor in the Center for the Study of First Americans and Department of Anthropology at Texas A&M, is part of an international team spearheaded by Eske Willerslev and Maanasa Raghaven from the Centre for GeoGenetics at the University of Copenhagen, Denmark and additional researchers from Sweden, Russia, United Kingdom, University of Chicago and University of California-Berkeley. Their work, funded by the Danish National Science Foundation, Lundbeck Foundation, and the National Science Foundation, is published in the current issue of Nature magazine.

Graf and Willerslev conceived the project and traveled to the Hermitage State Museum in St. Petersburg, Russia, where the remains are now housed to collect samples for ancient DNA. The skeleton was first discovered in the late 1920s near the village of Mal'ta in south-central Siberia, and since then it has been referred to as "the Mal'ta child" because until this DNA study the biological sex of the skeleton was unknown.

"Now we can say with confidence that this individual was a male" says Graf.

Graf helped extract DNA material from the boy's upper arm and "the results surprised all of us quite a bit," she explains.

"It shows he had close genetic ties to today's Native Americans and some western Eurasians, specifically some groups living in central Asia, South Asia, and Europe. Also, he shared close genetic ties with other Ice-Age western Eurasians living in European Russia, Czech Republic and even Germany. We think these Ice-Age people were quite mobile and capable of maintaining a far-reaching gene pool that extended from central Siberia all the way west to central Europe."

Another significant result of the study is that the Mal'ta boy's people were also ancestors of Native Americans, explaining why some early Native American skeletons such as Kennewick Man were interpreted to have some European traits.

"Our study proves that Native Americans ancestors migrated to the Americas from Siberia and not directly from Europe as some have recently suggested," Graf explains.

The DNA work performed on the boy is the oldest complete genome of a human sequenced so far, the study shows. Also found near the boy's remains were flint tools, a beaded necklace and what appears to be pendant-like items, all apparently placed in the burial as grave goods.

The discovery raises new questions about the timing of human entry in Alaska and ultimately North America, a topic hotly debated in First Americans studies.

"Though our results cannot speak directly to this debate, they do indicate Native American ancestors could have been in Beringia -- extreme northeastern Russia and Alaska -- any time after 24,000 years ago and therefore could have colonized Alaska and the Americas much earlier than 14,500 years ago, the age suggested by the archaeological record."

"What we need to do is continue searching for earlier sites and additional clues to piece together this very big puzzle."

Science

U.S. national survey finds frog abnormalities are rare

Nov. 20, 2013 — A 10-year study shows some good news for frogs and toads on national wildlife refuges. The rate of abnormalities such as shortened or missing legs was less than 2 percent overall -- indicating that the malformations first reported in the mid-1990s were rarer than feared. But much higher rates were found in local "hotspots," suggesting that where these problems occur they have local causes.

The results were published Nov. 18 in the journal PLOS ONE.

"We now know what the baseline is and the 2 percent level is relatively good news, but some regions need a deeper look," said Marcel Holyoak, professor of environmental science and policy at the University of California, Davis, and a co-author on the study. Hotspot regions included the Mississippi River Valley, California and south-central and eastern Alaska.

Mari Reeves, a graduate student working with Holyoak, led the data analysis and is corresponding author on the paper. Reeves now works at the U.S. Fish and Wildlife Service in Alaska.

Fieldwork for the study was carried out by the Fish and Wildlife Service at 152 refuges across the country between 2000 and 2009. Researchers collected more than 68,000 frogs and toads for the study. The complete dataset is available to researchers and the public online.

The aim of the study was to understand where and when these abnormalities occur -- are they widespread, or localized? Are they persistent, or do they appear and fade away? -- rather than to identify specific causes, Holyoak said. Understanding the patterns of these hotspots in space and time can help researchers home in on likely causes, he said.

The results show that abnormality hotspots occur in specific places, but within these hotspots the rate of malformations can change over time, Holyoak said.

"We see them at an elevated frequency one year or for a few years, and then they recover," he said.

The most common problems observed were missing or shortened toes or legs, and skin cysts. Only 12 cases of frogs with extra legs were found.

Many different potential causes have been put forward for the abnormalities, including pollution from industry or agriculture, parasites, ultraviolet exposure and naturally occurring heavy metals leaching into water bodies. The exact cause may vary from place to place, Holyoak noted.

The study comes against a background of a general decline in amphibian populations both in the U.S. and worldwide. For example, the California red-legged frog celebrated by Mark Twain's story is now listed as threatened. Frogs and toads may be especially sensitive to changes in climate and air or water quality. It's not clear whether hotspots of malformations contribute to this general decline, Holyoak said, but the new dataset will help researchers explore the problem.

The study was funded by the Fish and Wildlife Service. Other authors were: Kimberly Medley and Pieter Johnson, University of Colorado, Boulder; Alfred Pinkney, U.S. Fish and Wildlife Service, Annapolis; and Michael Lannoo, Indiana University School of Medicine.

Science

3-D printing hits fast lane: Engineers cut time to 3-D-print heterogeneous objects from hours to minutes

Nov. 20, 2013 — Researchers at the USC Viterbi School of Engineering have developed a faster 3D printing process and are now using it to model and fabricate heterogeneous objects, which comprise multiple materials.

Although 3D printing -- or direct digital manufacturing -- has the potential to revolutionize various industries by providing faster, cheaper and more accurate manufacturing options, fabrication time and the complexity of multi-material objects have long been a hurdle to its widespread use in the marketplace. With this newly developed 3D printing process, however, USC Viterbi professor Yong Chen and his team have shaved the fabrication time down to minutes, bringing the manufacturing world one step closer to achieving its goal.

"Digital material design and fabrication enables controlled material distributions of multiple base materials in a product component for significantly improved design performance. Such fabrication capability opens up exciting new options that were previously impossible," said Yong Chen, Ph.D., professor in the Daniel J. Epstein Department of Industrial and Systems Engineering and the study's lead researcher.

Traditional modeling and prototyping approaches used to take days, but over the past several decades various additive manufacturing (AM) processes have been developed to fabricate both homogeneous and heterogeneous objects more quickly. Currently, AM processes such as multi-jet modeling, which create a solid 3D object from a digital model by laying down successive layers of material, can fabricate a complex object in a matter of hours.

Last year, Chen and another team of USC Viterbi researchers improved an AM-related process called mask-image-projection-based stereolithography (MIP-SL) to drastically speed up the fabrication of homogeneous 3D objects. In the MIP-SL process, a 3D digital model of an object is sliced by a set of horizontal planes and each slice is converted into a two-dimensional mask image. The mask image is then projected onto a photocurable liquid resin surface and light is projected onto the resin to cure it in the shape of the related layer.

Furthermore, the USC Viterbi team developed a two-way movement design for bottom-up projection so that the resin could be quickly spread into uniform thin layers. As a result, production time was cut from hours to a few minutes. In their latest paper, the team successfully applies this more efficient process to the fabrication of heterogeneous objects that comprise different materials that cure at different rates. This new 3D printing process will allow heterogeneous prototypes and objects such as dental and robotics models to be fabricated more cost- and time-efficiently than ever before.

In future work, Chen and his team will investigate how to develop an automatic design approach for heterogeneous material distribution according to user-specified physical properties and how to improve the fabrication speed.

Chen and USC Viterbi industrial and systems engineering doctoral candidates students Pu Huang and Dongping Deng are presenting their findings at ASME's 2013 International Mechanical Engineering Congress and Exposition in San Diego on November 20th.

Video: http://vimeo.com/79412743

Science

Scientists break a theoretical time barrier on bouncing droplets

Nov. 20, 2013 — Those who study hydrophobic materials -- water-shedding surfaces such as those found in nature and created in the laboratory -- are familiar with a theoretical limit on the time it takes for a water droplet to bounce away from such a surface. But MIT researchers have now found a way to burst through that perceived barrier, reducing the contact time by at least 40 percent.

Their finding is reported in a paper in the journal Nature co-authored by Kripa Varanasi, the Doherty Associate Professor of Mechanical Engineering at MIT, along with James Bird, a former MIT postdoc who is now an assistant professor of mechanical engineering at Boston University, former MIT postdoc Rajeev Dhiman, and recent MIT PhD recipient Hyukmin Kwon.

"The time that the drop stays in contact with a surface is important because it controls the exchange of mass, momentum, and energy between the drop and the surface," Varanasi says. "If you can get the drops to bounce faster, that can have many advantages."

For example, in trying to prevent the buildup of ice on an airplane wing, the contact time of raindrops is critical: The longer a droplet stays in contact with a surface before bouncing off, the greater its chances of freezing in place.

According to the theoretical limit, the minimum time a bouncing droplet can stay in contact with a surface -- first spreading out into a pancake-like shape, then pulling back inward due to surface tension and bouncing away -- depends on the time period of oscillations in a vibrating drop, also known as the Rayleigh time. The way to achieve that minimum contact time, the conventional wisdom holds, is to minimize interaction between the water and the surface, such as by creating low-adhesion superhydrophobic surfaces.

But Varanasi's team found that increasing the surface interaction in a particular way can speed the process beyond that previous limit. To facilitate this interaction, they added macroscopic features -- such as ridges that break a droplet's symmetry and can serve to split it, causing it to recoil in highly irregular shapes. These ridged surfaces can have contact times that are 40 percent shorter than control surfaces.

"We've demonstrated that we can use surface texture to reshape a drop as it recoils, in such a way that the overall contact time is significantly reduced," says Bird, the paper's lead author. "The upshot is that the surface stays drier longer if this contact time is reduced, which has the potential to be useful for a variety of applications."

With this reduction in contact time, the researchers were able to show that droplets bounced off before freezing on these symmetry-breaking surfaces; on control surfaces, droplets arrested and solidified on the surface. "We can reduce it further," Varanasi says, through optimization of the texture. "I hope we can manage to get a 70 to 80 percent reduction."

Varanasi's team's findings may also have implications for ecology: The researchers found that some butterfly wings naturally produce the same effect, limiting the likelihood that water will spread out over the wings and curtail their aerodynamic properties -- a clear survival advantage. (In the case of the wings, it is the veins within that create the droplet-busting surface ridges.)

Similarly, the veins of nasturtium leaves, unlike those of most leaves, are on top, where they serve to break up droplets that land there. The MIT researchers found that drops bounced off both butterfly wings and nasturtium leaves faster than they bounced off lotus leaves, which are often considered the "gold standard" of nonwetting surfaces.

Varanasi points out that creating the needed surface textures is actually very simple: The ridges can be produced by ordinary milling tools, such as on the surface of an aluminum plate, making the process scalable to industrial levels. Such textures could also be created on fabric surfaces, he says, as a potential replacement for existing waterproof coatings whose safety has been called into question by the Environmental Protection Agency.

Howard Stone, a professor of mechanical and aerospace engineering at Princeton University who was not involved in this work, says, "This paper provides new ideas and new insights for how a surface texture can reduce the contact time of a bouncing drop. … It will be interesting to see possible ways these ideas might be applied in the future."

In addition to waterproofing and prevention of surface icing, the technique could have applications in other areas, Varanasi says. For example, the turbine blades in electric power plants become less efficient if water builds up on their surfaces. "If you can make the blades stay dry longer, you get a bump up in efficiency," he says. The new technique could also reduce corrosion on surfaces where droplets, especially if they are acidic or contain contaminants, contribute to degradation.

Video: http://www.youtube.com/watch?v=-qQirthIyh0

The research received support from the Defense Advanced Research Projects Agency, the MIT Energy Initiative, the National Science Foundation, and the MIT-Deshpande Center for Technological Innovation.

Science

Listen to this: New research upends understanding of how humans perceive sound

Nov. 20, 2013 — A key piece of the scientific model used for the past 30 years to help explain how humans perceive sound is wrong, according to a new study by researchers at the Stanford University School of Medicine.

The long-held theory helped to explain a part of the hearing process called "adaptation," or how humans can hear everything from the drop of a pin to a jet engine blast with high acuity, without pain or damage to the ear. Its overturning could have significant impact on future research for treating hearing loss, said Anthony Ricci, PhD, the Edward C. and Amy H. Sewall Professor of Otolaryngology and senior author of the study.

"I would argue that adaptation is probably the most important step in the hearing process, and this study shows we have no idea how it works," Ricci said. "Hearing damage caused by noise and by aging can target this particular molecular process. We need to know how it works if we are going to be able to fix it."

The study was published Nov. 20 in Neuron. The lead author is postdoctoral scholar Anthony Peng, PhD.

Deep inside the ear, specialized cells called hair cells detect vibrations caused by air pressure differences and convert them into electrochemical signals that the brain interprets as sound. Adaptation is the part of this process that enables these sensory hair cells to regulate the decibel range over which they operate. The process helps protect the ear against sounds that are too loud by adjusting the ears' sensitivity to match the noise level of the environment.

The traditional explanation for how adaptation works, based on earlier research on frogs and turtles, is that it is controlled by at least two complex cellular mechanisms both requiring calcium entry through a specific, mechanically sensitive ion channel in auditory hair cells. The new study, however, finds that calcium is not required for adaptation in mammalian auditory hair cells and posits that one of the two previously described mechanisms is absent in auditory cochlear hair cells.

Experimenting mostly on rats, the Stanford scientists used ultrafast mechanical stimulation to elicit responses from hair cells as well as high-speed, high-resolution imaging to track calcium signals quickly before they had time to diffuse. After manipulating intracellular calcium in various ways, the scientists were surprised to find that calcium was not necessary for adaptation to occur, thus challenging the 30-year-old hypothesis and opening the door to new models of mechanotransduction (the conversion of mechanical signals into electrical signals) and adaptation.

"This somewhat heretical finding suggests that at least some of the underlying molecular mechanisms for adaptation must be different in mammalian cochlear hair cells as compared to that of frog or turtle hair cells, where adaptation was first described," Ricci said.

The study was conducted to better understand how the adaptation process works by studying the machinery of the inner ear that converts sound waves into electrical signals.

"To me this is really a landmark study," said Ulrich Mueller, PhD, professor and chair of molecular and cellular neuroscience at the Scripps Research Institute in La Jolla, who was not involved with the study. "It really shifts our understanding. The hearing field has such precise models -- models that everyone uses. When one of the models tumbles, it's monumental."

Humans are born with 30,000 cochlear and vestibular hair cells per ear. When a significant number of these cells are lost or damaged, hearing or balance disorders occur. Hair cell loss occurs for multiple reasons, including aging and damage to the ear from loud sounds. Damage or impairment to the process of adaptation may lead to the further loss of hair cells and, therefore, hearing. Unlike many other species, including birds, humans and other mammals are unable to spontaneously regenerate these hearing cells.

As the U.S. population has aged and noise pollution has grown more severe, health experts now estimate that one in three adults over the age of 65 has developed at least some degree of hearing disability because of the destruction of these limited number of hair cells.

"It's by understanding just how the inner machinery of the ear works that scientists hope to eventually find ways to fix the parts that break," Ricci said. "So when a key piece of the puzzle is shown to be wrong, it's of extreme importance to scientists working to cure hearing loss."

Stanford postdoctoral scholar Thomas Effertz, PhD, is also an author of the study.

Science

Sun-powered battery woven into material overcomes hurdle for ‘wearable electronics’

Nov. 20, 2013 — Though some people already seem inseparable from their smartphones, even more convenient, wearable, solar-powered electronics could be on the way soon, woven into clothing fibers or incorporated into watchbands. This novel battery development, which could usher in a new era of "wearable electronics," is the topic of a paper in the ACS journal Nano Letters.

Taek-Soo Kim, Jung-Yong Lee, Jang Wook Choi and colleagues explain that electronic textiles have the potential to integrate smartphone functions into clothes, eyeglasses, watches and materials worn on the skin. Possibilities range from the practical -- for example, allowing athletes to monitor vital signs -- to the aesthetic, such as lighting up patterns on clothing. The bottleneck slowing progress toward development of a wider range of flexible e-fabrics and materials is the battery technology required to power them. Current wearable electronics, such as smartwatches and Google Glass, still require a charger with a cord, and already-developed textile batteries are costly and impractical. To unlink smart technology from the wall socket, the team had to rethink what materials are best suited for use in a flexible, rechargeable battery that's also inexpensive.

They tested unconventional materials and found that they could coat polyester yarn with nickel and then carbon, and use polyurethane as a binder and separator to produce a flexible battery that kept working, even after being folded and unfolded many times. They also integrated lightweight solar cells to recharge the battery without disassembling it from clothing or requiring the wearer to plug in.

The authors acknowledge funding from the National Research Foundation of Korea.

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The above story is based on materials provided by American Chemical Society.

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Journal Reference:

  1. Yong-Hee Lee, Joo-Seong Kim, Jonghyeon Noh, Inhwa Lee, Hyeong Jun Kim, Sunghun Choi, Jeongmin Seo, Seokwoo Jeon, Taek-Soo Kim, Jung-Yong Lee, Jang Wook Choi. Wearable Textile Battery Rechargeable by Solar Energy. Nano Letters, 2013; 13 (11): 5753 DOI: 10.1021/nl403860k

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

Science

Computer searches web 24/7 to analyze images and teach itself common sense

Nov. 20, 2013 — A computer program called the Never Ending Image Learner (NEIL) is running 24 hours a day at Carnegie Mellon University, searching the Web for images, doing its best to understand them on its own and, as it builds a growing visual database, gathering common sense on a massive scale.

NEIL leverages recent advances in computer vision that enable computer programs to identify and label objects in images, to characterize scenes and to recognize attributes, such as colors, lighting and materials, all with a minimum of human supervision. In turn, the data it generates will further enhance the ability of computers to understand the visual world.

But NEIL also makes associations between these things to obtain common sense information that people just seem to know without ever saying -- that cars often are found on roads, that buildings tend to be vertical and that ducks look sort of like geese. Based on text references, it might seem that the color associated with sheep is black, but people -- and NEIL -- nevertheless know that sheep typically are white.

"Images are the best way to learn visual properties," said Abhinav Gupta, assistant research professor in Carnegie Mellon's Robotics Institute. "Images also include a lot of common sense information about the world. People learn this by themselves and, with NEIL, we hope that computers will do so as well."

A computer cluster has been running the NEIL program since late July and already has analyzed three million images, identifying 1,500 types of objects in half a million images and 1,200 types of scenes in hundreds of thousands of images. It has connected the dots to learn 2,500 associations from thousands of instances.

The public can now view NEIL's findings at the project website, http://www.neil-kb.com.

The research team, including Xinlei Chen, a Ph.D. student in CMU's Language Technologies Institute, and Abhinav Shrivastava, a Ph.D. student in robotics, will present its findings on Dec. 4 at the IEEE International Conference on Computer Vision in Sydney, Australia.

One motivation for the NEIL project is to create the world's largest visual structured knowledge base, where objects, scenes, actions, attributes and contextual relationships are labeled and catalogued.

"What we have learned in the last 5-10 years of computer vision research is that the more data you have, the better computer vision becomes," Gupta said.

Some projects, such as ImageNet and Visipedia, have tried to compile this structured data with human assistance. But the scale of the Internet is so vast -- Facebook alone holds more than 200 billion images -- that the only hope to analyze it all is to teach computers to do it largely by themselves.

Shrivastava said NEIL can sometimes make erroneous assumptions that compound mistakes, so people need to be part of the process. A Google Image search, for instance, might convince NEIL that "pink" is just the name of a singer, rather than a color.

"People don't always know how or what to teach computers," he observed. "But humans are good at telling computers when they are wrong."

People also tell NEIL what categories of objects, scenes, etc., to search and analyze. But sometimes, what NEIL finds can surprise even the researchers. It can be anticipated, for instance, that a search for "apple" might return images of fruit as well as laptop computers. But Gupta and his landlubbing team had no idea that a search for F-18 would identify not only images of a fighter jet, but also of F18-class catamarans.

As its search proceeds, NEIL develops subcategories of objects -- tricycles can be for kids, for adults and can be motorized, or cars come in a variety of brands and models. And it begins to notice associations -- that zebras tend to be found in savannahs, for instance, and that stock trading floors are typically crowded.

NEIL is computationally intensive, the research team noted. The program runs on two clusters of computers that include 200 processing cores.

Science

Brain activity in severely brain injured patients who ‘wake up’ with sleeping pill: Other patients may also respond

Nov. 20, 2013 — George Melendez has been called a medical miracle. After a near drowning deprived his brain of oxygen, Melendez remained in a fitful, minimally conscious state until his mother, in 2002, decided to give him the sleep aid drug Ambien to quiet his moaning and writhing. The next thing she knew, her son was quietly looking at her and trying to talk. He has been using the drug ever since to maintain awareness, but no one could understand why Ambien led to such an awakening.

Now, a team of scientists led by Weill Cornell Medical College has discovered a signature of brain activity in Melendez and two other similarly "awakened" patients they say explain why he and others regain some consciousness after using Ambien or other drugs or treatments. The pattern of activity, reported Nov. 19 in the journal eLife, was identified by analyzing the common electroencephalography (EEG) test, which tracks brain waves.

"We found a surprisingly consistent picture of electrical activity in all three patients before they receive the drug. Most interesting is that their specific pattern of activity suggests a particular process occurring in the brain cells of the cerebral cortex and also supports the role of a crucial brain circuit," says the study's senior investigator, Dr. Nicholas Schiff, the Jerold B. Katz Professor of Neurology and Neuroscience and professor of public health at Weill Cornell. "These findings may help predict other patients who might similarly harbor reserve capacity, whether they are able to respond to Ambien or other approaches." Dr. Schiff is also on the faculty of the Feil Family Brain and Mind Research Institute at Weill Cornell and is a neurologist at NewYork-Presbyterian Hospital/Weill Cornell Medical Center.

"We are focused on finding ways to identify patients who have a functional reserve of cognitive capacities that can be rescued and how to achieve this result," Dr. Schiff adds. "These findings give us a very important lead to follow, and we will now rigorously test their implications in other patients."

Although it is not precisely known how many Americans are diagnosed as severely brain injured with disorders of consciousness, by one estimate there are nearly 300,000 patients trapped in a minimally conscious state who may retain some awareness, according to Dr. Schiff.

Riding a Wave of Excitation

The three patients in the study suffered brain damage in different ways. One fell and the other had a brain aneurysm that led to multiple strokes. Melendez was in a car accident that led to his nearly drowning. All three patients -- two men and a woman -- become aware when Ambien was used, a rare response that has been documented in fewer than 15 brain-injured patients.

The research team, which included scientists from Memorial Sloan-Kettering Cancer Center, Boston University School of Medicine, and the University Hospital of Liège in Belgium, used EEG to measure electrical activity in the patients' brains before and after they were given the drug.

Although each patient's brain was damaged in different ways, all showed the same unique features of low frequency waves in their EEG readings. These low frequency oscillations are most prominent over the frontal cortex, a region strongly dependent for its activity on other brain structures, particularly the central thalamus and the striatum, which together support short-term memory, reward, motivation, attention, alertness and sleep, among other functions.

In this setting of an idling brain, the investigators propose that Ambien works like any anesthesia drug, in that it briefly triggers a fast wave of excitation in brain cells before producing sleep -- a phenomenon known as paradoxical excitation. Instead of going on to produce sedation and sleep, as it does in healthy people who use the drug, zolpidem further activates the brain after it's affected the idling cells, allowing the patients to become more awake than at baseline. "What we think is happening in these patients is that the initial excitation produced by Ambien turns on a specific circuit. The drug creates the opportunity for the brain to effectively catch a ride on this initial wave of excitation, and turn itself back on," Dr. Schiff says.

This proposed "mesocircuit" links the cortical regions of the brain to the central thalamus and striatum. Neurons in the central thalamus are highly connected to other parts of the brain, "so damage in one part of the brain or another will affect the thalamus, which is key to consciousness," Dr. Schiff says. Neurons in the striatum "will only fire if there is a lot of electrical input coming to them quickly," he says.

"We believe the switch that Ambien turns on is at the level of the joint connections between these three brain structures," Dr. Schiff says.

The pattern of brain activity seen in the EEG on Ambien was also the same in all the patients in the study. But the circuit turns off again when the effects of the drug diminish. Using the drug regularly at mealtimes, Melendez can speak fluently, and read and write simple phrases. His tremors and spasticity are significantly reduced on Ambien and he can use objects, such as a spoon, and is alert and can communicate. The first patient in the study can reliably move from minimally conscious to "the mid-range of what is called a confusional state -- a more alert status, but not full consciousness," Dr. Schiff says. "Use of Ambien offers a step in the right direction, but certainly not a cure."

Different Ways to Kick-Start the Brain

The resting EEG pattern the researchers saw in the patients indicates they have a "recruitable reserve" of function in these critical brain areas that Ambien can harness to turn the brain on, even if only temporarily. "The idea is that hopefully we can screen other patients with EEG to find out if they also have such a reserve," Dr. Schiff says.

And while some of these patients may not respond to Ambien -- as the drug works at a very specific brain receptor and individuals can vary considerably in having enough of it in the key components of the proposed circuit -- other drugs may target the same structures and potentially produce similar effects, he says. For example, two drugs (amantadine and L-Dopa) that provide extra dopamine, a brain chemical that fuels the part of the brain damaged in the study's patients, have been shown to have similar effects on restoring function in patients with severe brain injuries, as has electrical brain stimulation of the central thalamus.

"Now that we have uncovered important insight into fundamental mechanisms underlying the dramatic and rare response of some severely brain-injured patients to Ambien, we hope to systematically explore ways to achieve such kick-starts in other patients -- that is our goal," Dr. Schiff says.

Science

CT and 3-D printers used to recreate dinosaur fossils

Nov. 20, 2013 — Data from computed tomography (CT) scans can be used with three-dimensional (3-D) printers to make accurate copies of fossilized bones, according to new research published online in the journal Radiology.

Fossils are often stored in plaster casts, or jackets, to protect them from damage. Getting information about a fossil typically requires the removal of the plaster and all the sediment surrounding it, which can lead to loss of material or even destruction of the fossil itself.

German researchers studied the feasibility of using CT and 3-D printers to nondestructively separate fossilized bone from its surrounding sediment matrix and produce a 3-D print of the fossilized bone itself.

"The most important benefit of this method is that it is non-destructive, and the risk of harming the fossil is minimal," said study author Ahi Sema Issever, M.D., from the Department of Radiology at Charité Campus Mitte in Berlin. "Also, it is not as time-consuming as conventional preparation."

Dr. Issever and colleagues applied the method to an unidentified fossil from the Museum für Naturkunde, a major natural history museum in Berlin. The fossil and others like it were buried under rubble in the basement of the museum after a World War II bombing raid. Since then, museum staff members have had difficulty sorting and identifying some of the plaster jackets.

Researchers performed CT on the unidentified fossil with a 320-slice multi-detector system. The different attenuation, or absorption of radiation, through the bone compared with the surrounding matrix enabled clear depiction of a fossilized vertebral body.

After studying the CT scan and comparing it to old excavation drawings, the researchers were able to trace the fossil's origin to the Halberstadt excavation, a major dig from 1910 to 1927 in a clay pit south of Halberstadt, Germany. In addition, the CT study provided valuable information about the condition and integrity of the fossil, showing multiple fractures and destruction of the front rim of the vertebral body.

Furthermore, the CT dataset helped the researchers build an accurate reconstruction of the fossil with selective laser sintering, a technology that uses a high-powered laser to fuse together materials to make a 3-D object.

Dr. Issever noted that the findings come at a time when advances in technology and cheaper availability of 3-D printers are making them more common as a tool for research. Digital models of the objects can be transferred rapidly among researchers, and endless numbers of exact copies may be produced and distributed, greatly advancing scientific exchange, Dr. Issever said. The technology also potentially enables a global interchange of unique fossils with museums, schools and other settings.

"The digital dataset and, ultimately, reproductions of the 3-D print may easily be shared, and other research facilities could thus gain valuable informational access to rare fossils, which otherwise would have been restricted," Dr. Issever said. "Just like Gutenberg's printing press opened the world of books to the public, digital datasets and 3-D prints of fossils may now be distributed more broadly, while protecting the original intact fossil."

Science

World’s first known magnetic cellulose loudspeakers: Potential for magnetic cellulose comes in crisp and clear

Nov. 20, 2013 — They're flat, ultra-thin and great-sounding. The world's first known magnetic cellulose loudspeakers have been demonstrated at KTH.

Throughout the ages, Swedes have relied on their country's vast forests as a source of sustenance and economic growth. Now add the world's first magnetic cellulose membrane loudspeakers to the list of products that can be produced from wood.

These flat, sonorous and environmentally-friendly speakers are made with a new material derived from wood pulp -- magnetic cellulose gel -- which was developed at Stockholm's KTH Royal Institute of Technology. Unlike ordinary speakers, they require no heavy permanent magnets.

Richard Olsson, a KTH researcher in chemical sciences who supervised the doctoral research behind the magnetic cellulose gel, says the new material may open the way for innovations in such areas as acoustic applications for automobiles.

Olsson and his colleagues at KTH, Lars Berglund, also a researcher in chemical sciences, and Valter Ström, a scientist in engineering physics of materials, recently demonstrated the speakers for the first time. Their paper is published by the Royal Society of Chemistry.

"This is, to our knowledge, the first reported magnetic speaker membrane," Olsson says. He adds that the sound quality is at least as good as in conventional speakers -- possibly better because of the even distribution of forces created in the membrane.

The idea is to show the potential of natural and environmentally-sustainable materials in everyday products. "We want to use this first prototype to see how the cellulose can be used in new applications," he says.

He and his research colleagues have patented the material, which was created by attaching magnetic nanoparticles to cellulose nanofibrils. The cellulose comes from renewable wood pulp and involves environmentally-friendly water chemistry. The gel is cast into a membrane which is then allowed to dry. The membrane's strength is that it has a rapid reaction capability, which means a high degree of precision in sound reproduction.

Ordinary speakers include a large permanent magnet. The speaker cone's movement, which creates sound waves, is driven by a voice coil that is wrapped around the permanent magnet and attached to the cone.

With the cellulose membrane speakers, the magnetic particles are part of the membrane itself. The KTH speaker has a coil, but it has no direct contact with the cone, so the only thing that creates sound is the movement of air. All of these components can be manufactured at a very small scale.

The technology has potentially other uses, he says. "We want to look at applications for the material that are driven by magnetic fields. It may, for example, be a form of active damping for cars and trains." It could also involve technology that cancels out noise.

Research in materials from the Swedish forests is conducted at Wallenberg Wood Science Center (WWSC). The doctoral students in the project are Sylvain Gallan, Richard Andersson and Michaela Salajkova.

Science

The Galaxy’s ancient brown dwarf population revealed

Nov. 20, 2013 — A team of astronomers led by Dr David Pinfield at the University of Hertfordshire have discovered two of the oldest brown dwarfs in the Galaxy. These ancient objects are moving at speeds of 100-200 kilometres per second, much faster than normal stars and other brown dwarfs and are thought to have formed when the Galaxy was very young, more than 10 billion years ago. Intriguingly the scientists believe they could be part of a vast and previously unseen population of objects.

The researchers publish their results in the Oxford University Press journal Monthly Notices of the Royal Astronomical Society.

Brown dwarfs are star-like objects but are much less massive (with less than 7% of the Sun's mass), and do not generate internal heat through nuclear fusion like stars. Because of this brown dwarfs simply cool and fade with time and very old brown dwarfs become very cool indeed -- the new discoveries have temperatures of 250-600 degrees Celsius, much cooler than stars (in comparison the Sun has a surface temperature of 5600 degrees Celsius).

Pinfield's team identified the new objects in the survey made by the Wide-field Infrared Survey Explorer (WISE), a NASA observatory that scanned the mid-infrared sky from orbit in 2010 and 2011. The object names are WISE 0013+0634 and WISE 0833+0052, and they lie in the Pisces and Hydra constellations respectively. Additional measurements confirming the nature of the objects came from large ground-based telescopes (Magellan, Gemini, VISTA and UKIRT). The infrared sky is full of faint red sources, including reddened stars, faint background galaxies (large distances from our own Milky Way) and nebulous gas and dust. Identifying cool brown dwarfs in amongst this messy mixture is akin to finding needles in a haystack. But Pinfield's team developed a new method that takes advantage of the way in which WISE scans the sky multiple times. This allowed them to identify cool brown dwarfs that were fainter than other searches had revealed.

The team of scientists then studied the infrared light emitted from these objects, which are unusual compared to typical slower moving brown dwarfs. The spectral signatures of their light reflects their ancient atmospheres, which are almost entirely made up of hydrogen rather than having the more abundant heavier elements seen in younger stars. Pinfield comments on their venerable ages and high speeds, "Unlike in other walks of life, the Galaxy's oldest members move much faster than its younger population."

Stars near to the Sun (in the so-called local volume) are made up of 3 overlapping populations -- the thin disk, the thick disk and the halo. The thick disk is much older than the thin disk, and its stars move up and down at a higher velocity. Both these disk components sit within the halo that contains the remnants of the first stars that formed in the Galaxy.

Thin disk objects dominate the local volume, with thick disk and halo objects being much rarer. About 97% of local stars are thin disk members, while just 3% are from the thick-disk or halo. Brown dwarfs population numbers probably follow those of stars, which explains why these fast-moving thick-disk/halo objects are only now being discovered.

There are thought to be as many as 70 billion brown dwarfs in the Galaxy's thin disk, and the thick disk and halo occupy much larger Galactic volumes. So even a small (3%) local population signifies a huge number of ancient brown dwarfs in the Galaxy. "These two brown dwarfs may be the tip of an iceberg and are an intriguing piece of astronomical archaeology," said Pinfield. "We have only been able to find these objects by searching for the faintest and coolest things possible with WISE. And by finding more of them we will gain insight into the earliest epoch of the history of the Galaxy."