Brain Cap Technology Turns Thought Into Motion; Mind-Machine Interface Could Lead to New Life-Changing Technologies for Millions of People

Brain Cap Technology Turns Thought Into Motion; Mind-Machine Interface Could Lead to New Life-Changing Technologies for Millions of People

  3:10:00 PM    Science Lover

---

"Brain cap" technology being developed at the University of Maryland allows users to turn their thoughts into motion. Associate Professor of Kinesiology José 'Pepe' L. Contreras-Vidal and his team have created a non-invasive, sensor-lined cap with neural interface software that soon could be used to control computers, robotic prosthetic limbs, motorized wheelchairs and even digital avatars.

University of Maryland associate professor of 
kinesiology Jose "Pepe" Contreras-Vidal wears his 
Brain Cap, a noninvasive, sensor-lined cap with neural 
interface software that soon could be used to control 
computers, robotic prosthetic limbs, motorized 
wheelchairs and even digital avatars. (Credit: John 
Consoli, University of Maryland)

"We are on track to develop, test and make available to the public- within the next few years -- a safe, reliable, noninvasive brain computer interface that can bring life-changing technology to millions of people whose ability to move has been diminished due to paralysis, stroke or other injury or illness," said Contreras-Vidal of the university's School of Public Health.

The potential and rapid progression of the UMD brain cap technology can be seen in a host of recent developments, including a just published study in the Journal of Neurophysiology, new grants from the National Science Foundation (NSF) and National Institutes of Health, and a growing list of partners that includes the University of Maryland School of Medicine, the Veterans Affairs Maryland Health Care System, the Johns Hopkins University Applied Physics Laboratory, Rice University and Walter Reed Army Medical Center's Integrated Department of Orthopaedics & Rehabilitation.

"We are doing something that few previously thought was possible," said Contreras-Vidal, who is also an affiliate professor in Maryland's Fischell Department of Bioengineering and the university's Neuroscience and Cognitive Science Program. "We use EEG [electroencephalography] to non-invasively read brain waves and translate them into movement commands for computers and other devices.

Peer Reviewed

Contreras-Vidal and his team have published three major papers on their technology over the past 18 months, the latest a just released study in the Journal of Neurophysiology in which they successfully used EEG brain signals to reconstruct the complex 3-D movements of the ankle, knee and hip joints during human treadmill walking. In two earlier studies they showed (1) similar results for 3-D hand movement and (2) that subjects wearing the brain cap could control a computer cursor with their thoughts.

Alessandro Presacco, a second-year doctoral student in Contreras-Vidal's Neural Engineering and Smart Prosthetics Lab, Contreras-Vidal and co-authors write that their Journal of Neurophysiology study indicated "that EEG signals can be used to study the cortical dynamics of walking and to develop brain-machine interfaces aimed at restoring human gait function."

There are other brain computer interface technologies under development, but Contreras-Vidal notes that these competing technologies are either very invasive, requiring electrodes to be implanted directly in the brain, or, if noninvasive, require much more training to use than does UMD's EEG-based, brain cap technology.

Partnering to Help Sufferers of Injury and Stroke

Contreras-Vidal and his team are collaborating on a rapidly growing cadre projects with researchers at other institutions to develop thought-controlled robotic prosthetics that can assist victims of injury and stroke. Their latest partnership is supported by a new $1.2 million NSF grant. Under this grant, Contreras-Vidal's Maryland team is embarking on a four-year project with researchers at Rice University, the University of Michigan and Drexel University to design a prosthetic arm that amputees can control directly with their brains, and which will allow users to feel what their robotic arm touches.



"There's nothing fictional about this," said Rice University co-principal investigator Marcia O'Malley, an associate professor of mechanical engineering. "The investigators on this grant have already demonstrated that much of this is possible. What remains is to bring all of it -- non-invasive neural decoding, direct brain control and [touch] sensory feedback -- together into one device."

In a NIH-supported project underway, Contreras-Vidal and his colleagues are pairing their brain cap's EEG-based technology with a DARPA-funded next-generation robotic arm designed by researchers at the Johns Hopkins Applied Physics Laboratory to function like a normal limb. And the UMD team is developing a new collaboration with the New Zealand's start-up Rexbionics, the developer of a powered lower-limb exoskeleton called Rex that could be used to restore gait after spinal cord injury.

Two of the earliest partnerships formed by Contreras-Vidal and his team are with the University of Maryland School of Medicine in Baltimore and the Veterans Affairs Medical Center in Baltimore. A particular focus of this research is the use of the brain cap technology to help stroke victims whose brain injuries affect their motor-sensory control. Originally funded by a seed grant from the University of Maryland, College Park and the University of Maryland, Baltimore, the work now also is supported by a VA merit grant (anklebot BMI) and an NIH grant (Stroke).

"There is a big push in brain science to understand what exercise does in terms of motor learning or motor retraining of the human brain," says Larry Forrester, an associate professor of physical therapy and rehabilitation science at the University of Maryland School of Medicine.

For the more than a year, Forrester and the UMD team have tracked the neural activity of people on a treadmill doing precise tasks like stepping over dotted lines. The researchers are matching specific brain activity recorded in real time with exact lower-limb movements.

This data could help stroke victims in several ways, Forrester says. One is a prosthetic device, called an "anklebot," or ankle robot, that stores data from a normal human gait and assists partially paralyzed people. People who are less mobile commonly suffer from other health issues such as obesity, diabetes or cardiovascular problems, Forrester says, "so we want to get [stroke survivors] up and moving by whatever means possible."

The second use of the EEG data in stroke victims is more complex, yet offers exciting possibilities. "By decoding the motion of a normal gait," Contreras-Vidal says, "we can then try and teach stroke victims to think in certain ways and match their own EEG signals with the normal signals." This could "retrain" healthy areas of the brain in what is known as neuroplasticity.

One potential method for retraining comes from one of the Maryland research team's newest members, Steve Graff, a first-year bioengineering doctoral student. He envisions a virtual reality game that matches real EEG data with on-screen characters. "It gives us a way to train someone to think the right thoughts to generate movement from digital avatars. If they can do that, then they can generate thoughts to move a device," says Graff, who brings a unique personal perspective to the work. He has congenital muscular dystrophy and uses a motorized wheelchair. The advances he's working on could allow him to use both hands -- to put on a jacket, dial his cell phone or throw a football while operating his chair with his mind.

No Surgery Required

During the past two decades a great deal of progress has been made in the study of direct brain to computer interfaces, most of it through studies using monkeys with electrodes implanted in their brains. However, for use in humans such an invasive approach poses many problems, not the least of which is that most people don't' want holes in their heads and wires attached to their brains. "EEG monitoring of the brain, which has a long, safe history for other applications, has been largely ignored by those working on brain-machine interfaces, because it was thought that the human skull blocked too much of the detailed information on brain activity needed to read thoughts about movement and turn those readings into movement commands for multi-functional high-degree of freedom prosthetics," said Contreras-Vidal. He is among the few who have used EEG, MEG or other sensing technologies to develop non-invasive neural interfaces, and the only one to have demonstrated decoding results comparable to those achieved by researchers using implanted electrodes.

A paper Contreras-Vidal and colleagues published in the Journal of Neuroscience in March 2010 showed the feasibility of Maryland's EEG-based technology to infer multidimensional natural movement from noninvasive measurements of brain activity. In their two latest studies, Contreras-Vidal and his team have further advanced the development of their EEG brain interface technology, and provided powerful new evidence that it can yield brain computer interface results as good as or better than those from invasive studies, while also requiring minimal training to use.

In a paper published in April in the Journal of Neural Engineering, the Maryland team demonstrated that people wearing the EEG brain cap, could after minimal training control a computer cursor with their thoughts and achieve performance levels comparable to those by subjects using invasive implanted electrode brain computer interface systems. Contreras-Vidal and his co-authors write that this study also shows that compared to studies of other noninvasive brain control interface systems, training time with their system was substantially shorter, requiring only a single 40-minute session.

Read More

New Invisibility Cloak Hides Objects from Human View

New Invisibility Cloak Hides Objects from Human View

  2:26:00 PM    Science Lover

---

For the first time, scientists have devised an invisibility cloak material that hides objects from detection using light that is visible to humans. The new device is a leap forward in cloaking materials, according to a report in the ACS journal Nano Letters.

A real-life invisibility cloak, shown in this cross- sectional 
illustration, can hide objects from human view. (Credit: ACS)

Xiang Zhang and colleagues note that invisibility cloaks, which route electromagnetic waves around an object to make it undetectable, "are still in their infancy." Most cloaks are made of materials that can only hide things using microwave or infrared waves, which are just below the threshold of human vision. To remedy this, the researchers built a reflective "carpet cloak" out of layers of silicon oxide and silicon nitride etched in a special pattern. The carpet cloak works by concealing an object under the layers, and bending light waves away from the bump that the object makes, so that the cloak appears flat and smooth like a normal mirror.

Although the study cloaked a microscopic object roughly the diameter of a red blood cell, the device demonstrates that it may be "capable of cloaking any object underneath a reflective carpet layer. In contrast to the previous demonstrations that were limited to infrared light, this work makes actual invisibility for the light seen by the human eye possible," the scientists write.



The authors acknowledge funding from the U.S. Army Research Office, the Natural Sciences and Engineering Research Council of Canada, and the NSF Graduate Research Fellowship Program.

Read More

Southampton engineers fly the world's first 'printed' aircraft

Southampton engineers fly the world's first 'printed' aircraft

  10:10:00 AM    Science Lover

---

Engineers at the University of Southampton have designed and flown the world's first 'printed' aircraft, which could revolutionise the economics of aircraft design.

SULSA is the world's first "printed" aircraft.
Credit: University of Southampton

The SULSA (Southampton University Laser Sintered Aircraft) plane is an unmanned air vehicle (UAV) whose entire structure has been printed, including wings, integral control surfaces and access hatches. It was printed on an EOS EOSINT P730 nylon laser sintering machine, which fabricates plastic or metal objects, building up the item layer by layer.

No fasteners were used and all equipment was attached using 'snap fit' techniques so that the entire aircraft can be put together without tools in minutes.

The electric-powered aircraft, with a 2-metres wingspan, has a top speed of nearly 100 miles per hour, but when in cruise mode is almost silent. The aircraft is also equipped with a miniature autopilot developed by Dr Matt Bennett, one of the members of the team.

Laser sintering allows the designer to create shapes and structures that would normally involve costly traditional manufacturing techniques. This technology allows a highly-tailored aircraft to be developed from concept to first flight in days. Using conventional materials and manufacturing techniques, such as composites, this would normally take months. Furthermore, because no tooling is required for manufacture, radical changes to the shape and scale of the aircraft can be made with no extra cost.

This project has been led by Professors Andy Keane and Jim Scanlan from the University's Computational Engineering and Design Research group.

Professor Scanlon says: "The flexibility of the laser sintering process allows the design team to re-visit historical techniques and ideas that would have been prohibitively expensive using conventional manufacturing. One of these ideas involves the use of a Geodetic structure. This type of structure was initially developed by Barnes Wallis and famously used on the Vickers Wellington bomber which first flew in 1936. This form of structure is very stiff and lightweight, but very complex. If it was manufactured conventionally it would require a large number of individually tailored parts that would have to be bonded or fastened at great expense."



Professor Keane adds: "Another design benefit that laser sintering provides is the use of an elliptical wing planform. Aerodynamicists have, for decades, known that elliptical wings offer drag benefits. The Spitfire wing was recognised as an extremely efficient design but it was notoriously difficult and expensive to manufacture. Again laser sintering removes the manufacturing constraint associated with shape complexity and in the SULSA aircraft there is no cost penalty in using an elliptical shape."

SULSA is part of the EPSRC-funded DECODE project, which is employing the use of leading edge manufacturing techniques, such as laser sintering, to demonstrate their use in the design of UAVs.

The University of Southampton has been at the forefront of UAV development since the early 1990s, when work began on the Autosub programme at its waterfront campus at the National Oceanography Centre, Southampton. A battery powered submarine travelled under sea ice in more than 300 voyages to map the North Sea, and assess herring stocks.

Now, the University is launching a groundbreaking course which enables students to take a Master's Degree in unmanned autonomous vehicle (UAV) design.

Provided by University of Southampton

Read More

New Way to Measure Expansion of Universe

New Way to Measure Expansion of Universe

  12:38:00 AM    Science Lover

---

Using a measurement of the clustering of the galaxies surveyed, plus other information derived from observations of the early universe, researchers have measured the Hubble constant with an uncertainly of less than 5 percent. The new work draws on data from a survey of more than 125,000 galaxies.

The 6df Galaxy Survey data, each dot is a galaxy and 
Earth is at the center of the sphere. (Credit: Image courtesy 
of International Centre for Radio Astronomy Research)

A PhD student from The International Centre for Radio Astronomy Research (ICRAR) in Perth has produced one of the most accurate measurements ever made of how fast the Universe is expanding.

Florian Beutler, a PhD candidate with ICRAR at the University of Western Australia, has calculated how fast the Universe is growing by measuring the Hubble constant.

"The Hubble constant is a key number in astronomy because it's used to calculate the size and age of the Universe," said Mr Beutler.

As the Universe swells, it carries other galaxies away from ours. The Hubble constant links how fast galaxies are moving with how far they are from us.

By analysing light coming from a distant galaxy, the speed and direction of that galaxy can be easily measured. Determining the galaxy's distance from Earth is much more difficult. Until now, this has been done by observing the brightness of individual objects within the galaxy and using what we know about the object to calculate how far away the galaxy must be.

This approach to measuring a galaxy's distance from Earth is based on some well-established assumptions but is prone to systematic errors, leading Mr Beutler to tackle the problem using a completely different method.



Published July 26 in the Monthly Notices of the Royal Astronomical Society, Mr Beutler's work draws on data from a survey of more than 125,000 galaxies carried out with the UK Schmidt Telescope in eastern Australia. Called the 6dF Galaxy Survey, this is the biggest survey to date of relatively nearby galaxies, covering almost half the sky.

Galaxies are not spread evenly through space, but are clustered. Using a measurement of the clustering of the galaxies surveyed, plus other information derived from observations of the early Universe, Mr Beutler has measured the Hubble constant with an uncertainly of less than 5%.*

"This way of determining the Hubble constant is as direct and precise as other methods, and provides an independent verification of them," says Professor Matthew Colless, Director of the Australian Astronomical Observatory and one of Mr Beutler's co-authors. "The new measurement agrees well with previous ones, and provides a strong check on previous work."

The measurement can be refined even further by using data from larger galaxy surveys.

"Big surveys, like the one used for this work, generate numerous scientific outcomes for astronomers internationally," says Professor Lister Staveley-Smith, ICRAR's Deputy Director of Science.

* The new measurement of the Hubble constant is 67.0 ± 3.2 km s-1 Mpc-1

Read More

Scientists Discover Tipping Point for the Spread of Ideas

Scientists Discover Tipping Point for the Spread of Ideas

  9:46:00 AM    Science Lover

---

Scientists at Rensselaer Polytechnic Institute have found that when just 10 percent of the population holds an unshakable belief, their belief will always be adopted by the majority of the society. The scientists, who are members of the Social Cognitive Networks Academic Research Center (SCNARC) at Rensselaer, used computational and analytical methods to discover the tipping point where a minority belief becomes the majority opinion. The finding has implications for the study and influence of societal interactions ranging from the spread of innovations to the movement of political ideals.

In this visualization, we see the tipping point where minority opinion (shown in red) quickly becomes majority opinion. Over time, the minority opinion grows. Once the minority opinion reached 10 percent of the population, the network quickly changes as the minority opinion takes over the original majority opinion (shown in green). (Credit: SCNARC/Rensselaer Polytechnic Institute)

"When the number of committed opinion holders is below 10 percent, there is no visible progress in the spread of ideas. It would literally take the amount of time comparable to the age of the universe for this size group to reach the majority," said SCNARC Director Boleslaw Szymanski, the Claire and Roland Schmitt Distinguished Professor at Rensselaer. "Once that number grows above 10 percent, the idea spreads like flame."

As an example, the ongoing events in Tunisia and Egypt appear to exhibit a similar process, according to Szymanski. "In those countries, dictators who were in power for decades were suddenly overthrown in just a few weeks."

The findings were published in the July 22, 2011, early online edition of the journal Physical Review E in an article titled "Social consensus through the influence of committed minorities."

An important aspect of the finding is that the percent of committed opinion holders required to shift majority opinion does not change significantly regardless of the type of network in which the opinion holders are working. In other words, the percentage of committed opinion holders required to influence a society remains at approximately 10 percent, regardless of how or where that opinion starts and spreads in the society.

To reach their conclusion, the scientists developed computer models of various types of social networks. One of the networks had each person connect to every other person in the network. The second model included certain individuals who were connected to a large number of people, making them opinion hubs or leaders. The final model gave every person in the model roughly the same number of connections. The initial state of each of the models was a sea of traditional-view holders. Each of these individuals held a view, but were also, importantly, open minded to other views.

Once the networks were built, the scientists then "sprinkled" in some true believers throughout each of the networks. These people were completely set in their views and unflappable in modifying those beliefs. As those true believers began to converse with those who held the traditional belief system, the tides gradually and then very abruptly began to shift.



"In general, people do not like to have an unpopular opinion and are always seeking to try locally to come to consensus. We set up this dynamic in each of our models," said SCNARC Research Associate and corresponding paper author Sameet Sreenivasan. To accomplish this, each of the individuals in the models "talked" to each other about their opinion. If the listener held the same opinions as the speaker, it reinforced the listener's belief. If the opinion was different, the listener considered it and moved on to talk to another person. If that person also held this new belief, the listener then adopted that belief.

"As agents of change start to convince more and more people, the situation begins to change," Sreenivasan said. "People begin to question their own views at first and then completely adopt the new view to spread it even further. If the true believers just influenced their neighbors, that wouldn't change anything within the larger system, as we saw with percentages less than 10."

The research has broad implications for understanding how opinion spreads. "There are clearly situations in which it helps to know how to efficiently spread some opinion or how to suppress a developing opinion," said Associate Professor of Physics and co-author of the paper Gyorgy Korniss. "Some examples might be the need to quickly convince a town to move before a hurricane or spread new information on the prevention of disease in a rural village."

The researchers are now looking for partners within the social sciences and other fields to compare their computational models to historical examples. They are also looking to study how the percentage might change when input into a model where the society is polarized. Instead of simply holding one traditional view, the society would instead hold two opposing viewpoints. An example of this polarization would be Democrat versus Republican.

The research was funded by the Army Research Laboratory (ARL) through SCNARC, part of the Network Science Collaborative Technology Alliance (NS-CTA), the Army Research Office (ARO), and the Office of Naval Research (ONR).

The research is part of a much larger body of work taking place under SCNARC at Rensselaer. The center joins researchers from a broad spectrum of fields -- including sociology, physics, computer science, and engineering -- in exploring social cognitive networks. The center studies the fundamentals of network structures and how those structures are altered by technology. The goal of the center is to develop a deeper understanding of networks and a firm scientific basis for the newly arising field of network science. More information on the launch of SCNARC can be found at http://news.rpi.edu/update.do?artcenterkey=2721&setappvar=page(1)

Szymanski, Sreenivasan, and Korniss were joined in the research by Professor of Mathematics Chjan Lim, and graduate students Jierui Xie (first author) and Weituo Zhang.

Read More

Researchers develop prototype to detect fake websites

Researchers develop prototype to detect fake websites

  10:16:00 AM    Science Lover

---

Do you go online to pay bills, shop, transfer funds, sign up for classes, send email or instant messages or search for medical information? If so, then this pertains to you.

It seems logical that a more Internet-driven world would translate into a heightened awareness of fake websites. But it isn't so. The vast majority of people still are unable to determine the authenticity of websites, resulting in tremendous monetary loses. That is what is driving the work of UA Artificial Intelligence Lab members who, along with a UA alumnus, have earned a top honor from MIS Quarterly for their research.

Members of a University of Arizona Eller College of Management team and a UA alumnus developed a prototype system to detect fake websites. When tested against other existing commercial systems, the team found that its system resulted in effective and more accurate detections of spoof sites – better than a human can.

The team's subsequent article, “Detecting Fake Websites: The Contribution of Statistical Learning Theory" was published last year in an issue of MIS Quarterly, or MISQ. A preeminent peer-reviewed journal in the field of management information systems, MISQ has since been named the article its top paper for 2010.

"Even to get into MISQ is very difficult, and this is probably the first technical paper to receive the Best Paper award," said Hsinchun Chen, the UA Artificial Intelligence Lab director, one of the paper's five authors.

MISQ will formally honor the researchers in Shanghai, China later this year during the International Conference on Information Systems.

"The topic of detecting fake websites and also our computational approach are both considered major contributions. This topic has great relevance to the industry, the society and the citizens in general," said Chen, also the McClelland Professor of Management Information Systems.

"This award is not something just for me, or my lab, but also for our department," he said, adding that the team's eventual goal is technology transfer.

UA alumnus Ahmed Abbasi, now a University of Virginia assistant professor of information technology, is lead author on the paper. Chen served as his dissertation adviser. Other co-authors are UA Eller College's department of management information systems faculty members Zhu Zhang and Jay F. Nunamaker Jr.; and David Zimbra, a doctoral student in the Artificial Intelligence Lab.



For the research, the team used the prototype and several other detection systems to evaluate the authenticity of 900 websites.

It is easy to pick up on a site's authenticity by checking whether the URL contains "http" when it should read "https," when it was last updated, if a security key is missing or if images appear strangely pixelated.

The team found that its system – founded on statistical learning technology, which evaluates a large accumulation of data – was more apt to detect imitation sites and those that were entirely concocted, said Abbasi, who earned his doctoral degree in management information systems from the UA in 2008.

The major difference between the authors’ prototype and the other systems? Their system relied on a tremendously rich set of fraud cues.

The team developed five categories with thousands of cues, finding that the best results were attained when utilizing thousands of highly visible and also deeply embedded cues, such as placement, URL length, the number of links, characters types on the site and how thorough the site's "frequently asked questions" section is detailed, among other features.

The project's origins were born out of the Artificial Intelligence Lab, where Abbasi developed the mathematical formula the team eventually used while working as a project lead and research associate. He continued the work after having taken a faculty position at the University of Wisconsin-Milwaukee.

"It creates a greater awareness for a problem that has been around for a while yet still remains an issue as we increasingly move to the Internet for everything – online banking, online health initiatives and medical information," Abbasi said.

Given the pervasive nature of online phishing scams, being able to readily and frequently detect a site's validity is crucial, Abbasi said, also noting research that indicates people are less than 60 percent accurate in detecting fake sites, and other security issues.

"The problem we're looking at is quite big. Fake websites constitute much of the Internet fraud's multi-billion dollar industry, and that is monetary loss…we can’t even quantify the social ramifications," Abbasi said. "That's the whole motivation. It is so profitable for fraudsters, and it is slipping through the cracks."

Today, Chen and more than one dozen of his collaborators are continuing to investigate fake sites. Meanwhile, Abbasi is undertaking an investigation of peoples' abilities to detect fake sites through a grant funded by the National Science Foundation.

Today, Chen and more than one dozen of his collaborators are continuing to investigate fake sites. Meanwhile, Abbasi is undertaking an investigation of users and peoples' abilities to detect fake sites.

Abbasi said developing better detection systems requires improved statistical learning technology that utilize larger quantities of cues. It also is important to dismiss long-held perceptions about how fake sites might and should appear.

Read More

Eat, Prey, Rain: New Model of Dynamics of Clouds and Rain Is Based On a Predator-Prey Population Model

Eat, Prey, Rain: New Model of Dynamics of Clouds and Rain Is Based On a Predator-Prey Population Model

  10:10:00 AM    Science Lover

---

What do a herd of gazelles and a fluffy mass of clouds have in common? A mathematical formula that describes the population dynamics of such prey animals as gazelles and their predators has been used to model the relationship between cloud systems, rain and tiny floating particles called aerosols. This model may help climate scientists understand, among other things, how human-produced aerosols affect rainfall patterns. The research recently appeared in the Proceedings of the National Academy of Sciences (PNAS).

A new mathematical model may help climate scientists 
understand, among other things, how human-produced 
aerosols affect rainfall patterns. (Credit: © Brian 
Jackson / Fotolia)

Clouds are major contributors to the climate system. In particular the shallow marine stratocumulus clouds that form huge cloud decks over the subtropical oceans cool the atmosphere by reflecting part of the incoming solar energy back to space. Drs. Ilan Koren of the Weizmann Institute's Environmental Sciences and Energy Research Department (Faculty of Chemistry) and Graham Feingold of the NOAA Earth System Research Laboratory, Colorado, found that equations for modeling prey-predator cycles in the animal world were a handy analogy for cloud-rain cycles: Just as respective predator and prey populations expand and contract at the expense of one another, so too rain depletes clouds, which grow again once the rain runs out. And just as the availability of grass affects herd size, the relative abundance of aerosols -- which "feed" the clouds as droplets condense around them -- affects the shapes of those clouds. A larger supply of airborne particles gives rise to more droplets, but these droplets are smaller and thus remain high up in the cloud rather than falling as rain.

In previous research, Feingold and Koren had "zoomed in" to discover oscillations in convective cells in marine stratocumulus. Now they returned to their data, but from a "top down" angle to see if a generalized formula could reveal something about these systems. Using just three simple equations, they developed a model showing that cloud-rain dynamics mimic three known predator-prey modes. Like gazelles and lions, the two can oscillate in tandem, the "predator" rain cycle following a step behind peak cloud formation. Or the two can reach a sort of steady state in which the clouds are replenished at the same rate as they are diminished (as in a light, steady drizzle). The third option is chaos -- the crash that occurs when predator populations get out of hand or a strong rain destroys the cloud system.



The model shows that as the amounts of aerosols change, the system can abruptly shift from one state to another. It also reveals a bifurcation -- two scenarios at different ends of the aerosol scale that lend themselves to stable patterns. In the first, relatively low aerosol levels lead to clouds in which development depends heavily on aerosol concentrations. In the second, high levels produce saturation; these clouds depend solely on the initial environmental conditions.

Using this so-called systems approach, says Koren, "can open new windows to view and understand the emergent behavior of the complex relationships between clouds, rain and aerosols, giving us a more useful view of the big picture and helping us to understand how shifting aerosol levels can lead to different climate patterns."

Read More

Improving batteries' energy storage

Improving batteries' energy storage

  12:35:00 AM    Science Lover

---

MIT researchers have found a way to improve the energy density of a type of battery known as lithium-air (or lithium-oxygen) batteries, producing a device that could potentially pack several times more energy per pound than the lithium-ion batteries that now dominate the market for rechargeable devices in everything from cellphones to cars.

Photo: Jin Suntivich

The work is a continuation of a project that last year demonstrated improved efficiency in lithium-air batteries through the use of noble-metal-based catalysts. In principle, lithium-air batteries have the potential to pack even more punch for a given weight than lithium-ion batteries because they replace one of the heavy solid electrodes with a porous carbon electrode that stores energy by capturing oxygen from air flowing through the system, combining it with lithium ions to form lithium oxides.

The new work takes this advantage one step further, creating carbon-fiber-based electrodes that are substantially more porous than other carbon electrodes, and can therefore more efficiently store the solid oxidized lithium that fills the pores as the battery discharges.

"We grow vertically aligned arrays of carbon nanofibers using a chemical vapor deposition process. These carpet-like arrays provide a highly conductive, low-density scaffold for energy storage," explains Robert Mitchell, a graduate student in MIT's Department of Materials Science and Engineering (DMSE) and co-author of a paper describing the new findings in the journal Energy and Environmental Science.

This diagram depicts the essential functioning of the lithium-air battery. Ions of lithium combine with oxygen from the air to form particles of lithium oxides, which attach themselves to carbon fibers on the electrode as the battery is being used. During recharging, the lithium oxides separate again into lithium and oxygen and the process can begin again. Graphic: Courtesy of Mitchell, Gallant, and Shao-Horn

During discharge, lithium-peroxide particles grow on the carbon fibers, adds co-author Betar Gallant, a graduate student in MIT's Department of Mechanical Engineering. In designing an ideal electrode material, she says, it's important to "minimize the amount of carbon, which adds unwanted weight to the battery, and maximize the space available for lithium peroxide," the active compound that forms during the discharging of lithium-air batteries.



"We were able to create a novel carpet-like material — composed of more than 90 percent void space — that can be filled by the reactive material during battery operation," says Yang Shao-Horn, the Gail E. Kendall Professor of Mechanical Engineering and Materials Science and Engineering and senior author of the paper. The other senior author of the paper is Carl Thompson, the Stavros Salapatas Professor of Materials Science and Engineering and interim head of DMSE.

In earlier lithium-air battery research that Shao-Horn and her students reported last year, they demonstrated that carbon particles could be used to make efficient electrodes for lithium-air batteries. In that work, the carbon structures were more complex but only had about 70 percent void space.

As the battery is used, particles of
lithium peroxide form as small dots
on the sides of carbon nanofibers
(top), and eventually assume larger
toroidal (donut) shapes as the battery
continues to discharge (bottom), as
seen in these scanning electron
microscope images. Photo: Courtesy
of Mitchell, Gallant, and Shao-Horn

The gravimetric energy stored by these electrodes — the amount of power they can store for a given weight — "is among the highest values reported to date, which shows that tuning the carbon structure is a promising route for increasing the energy density of lithium-air batteries," Gallant says. The result is an electrode that can store four times as much energy for its weight as present lithium-ion battery electrodes.

In the paper published last year, the team had estimated the kinds of improvement in gravimetric efficiency that might be achieved with lithium-air batteries; this new work "realizes this gravimetric gain," Shao-Horn says. Further work is still needed to translate these basic laboratory advances into a practical commercial product, she cautions.

Because the electrodes take the form of orderly "carpets" of carbon fibers — unlike the randomly arranged carbon particles in other electrodes — it is relatively easy to use a scanning electron microscope to observe the behavior of the electrodes at intermediate states of charge. The researchers say this ability to observe the process, an advantage that they had not anticipated, is a critical step toward further improving battery performance. For example, it could help explain why existing systems degrade after many charge-discharge cycles.

Ji-Guang Zhang, a laboratory fellow in battery technology at the Pacific Northwest National Laboratory, says this is "original and high-quality work." He adds that this research "demonstrates a very unique approach to preparing high-capacity electrodes for lithium-air batteries." 

This story is republished courtesy of MIT News (http://web.mit.edu/newsoffice/), a popular site that covers news about MIT research, innovation and teaching.

Read More

Cellular Stress Can Induce Yeast to Promote Prion Formation

Cellular Stress Can Induce Yeast to Promote Prion Formation

  6:53:00 PM    Science Lover

---

It's a chicken and egg question. Where do the infectious protein particles called prions come from? Essentially clumps of misfolded proteins, prions cause neurodegenerative disorders, such as mad cow/Creutzfeld-Jakob disease, in humans and animals. Prions trigger the misfolding and aggregation of their properly folded protein counterparts, but they usually need some kind of "seed" to get started.

Biochemists at Emory University School of Medicine have identified a yeast protein called Lsb2 that can promote spontaneous prion formation. This unstable, short-lived protein is strongly induced by cellular stresses such as heat. Lsb2's properties also illustrate how cells have developed ways to control and regulate prion formation. Research in yeast has shown that sometimes, prions can actually help cells adapt to different conditions.

The results are published in the July 22 issue of the journal Molecular Cell. The senior author is Keith Wilkinson, PhD, professor of biochemistry at Emory University School of Medicine The first author is senior associate Tatiana Chernova, PhD.

The aggregated form of proteins connected with several other neurodegenerative diseases such as Alzheimer's, Parkinson's and Huntington's can, in some circumstances, act like prions. So the Emory team's finding provides insight into how the ways that cells deal with stress might lead to poisonous protein aggregation in human diseases.

"A direct human homolog of Lsb2 doesn't exist, but there may be a protein that performs the same function," Wilkinson says. "The mechanism may say more about other types of protein aggregates than about classical prions in humans, This mechanism of seeding and growth may be more important for aggregate formation in diseases such as Huntington's."



Lsb2 does not appear to form stable prions by itself. Rather, it seems to bind to and encourage the aggregation of another protein, Sup35, which does form prions.

"Our model is that stress induces high levels of Lsb2, which allows the accumulation of misfolded prion proteins," Wilkinson says. "Lsb2 protects enough of these newborn prion particles from the quality control machinery for a few of them to get out."

The research was supported by the National Institutes of Health.

More information: T.A. Chernova et al. Prion Induction by the Short-lived Stress Induced Protein Lsb2 Is Regulated by Ubiquitination and Association with the Actin Cytoskeleton Mol. Cell (2011).
Provided by Emory University

Read More

Engineering a new face after injury

Engineering a new face after injury

  1:19:00 AM    Science Lover

---

Today, surgeons face many limitations when it comes to helping a patient who suffers from a severe craniofacial injury, or an injury pertaining to the skull and the face. Most often a result of cancer or war-related circumstances, the injury is both psychologically and physically damaging.

Evolution of a patient's recovery from facial injury through the use of topological optimization. Credit: Hanlon, Beckman ITG, University of Illinois

Will the patients ever recover their appearance? Or more importantly, recover their ability to speak, breathe or eat correctly again?

Rebuilding the delicate facial bone structure of an individual is a complicated procedure. The surgeon constructs a facial frame with bone from other parts of the body (called autologous tissue), in order to guarantee the functionality of the specialized organs responsible for vital roles such as breathing, seeing, communicating and eating. Since there are no analogous bone structures to a person's face, the procedure depends on experience and skill. As Glaucio Paulino, program director of the mechanics of materials program at the National Science Foundation (NSF), noted, this procedure does not always generate the desired outcome.

"The middle of the face is the most complicated part of the human skeleton," said Paulino. "What makes the reconstruction more complicated is the fact that the bones are small, delicate, highly specialized and located in a region highly susceptible to contamination by bacteria."

Facial bones are unique and using bone tissue extracted from different parts of the body, such as the bones of the forearm, isn't the most effective form of recovery.

"The patient may be improved, but still suffer from significant deformity," said Paulino.

Implementation of loads, boundary conditions and different cavity constraints to a design domain and the consequent optimized results. Credit: Glaucio H. Paulino

In contrast, topological optimization is a feasible alternative to make such a recovery possible.

Topological optimization isn't native to the surgery room--it's a mathematical method that uses given loads, the applied force on an area, and boundary conditions or spatial limits, to optimize a specific structure's layout. Imagine a building grid in which you can determine where there should be material and where there shouldn't. Moreover, you can express loads and supports that would affect certain parts of this block of material. Your final result is an optimized structure that fits your established constraints.

This mathematical method is successfully used to engineer spaceships and airplanes. The Airbus 380 wing, for example, was designed with topological optimization. Today, extensive research is underway to apply topological optimization to the engineering of future high-rise buildings. Paulino is responsible for some of the recent advances in this field.



Together with Alok Sutradhar and Michael Miller, from the Ohio State University Medical Center, and Tam Nguyen, from the department of civil and environmental engineering at the University of Illinois, Paulino is studying how to bring topological optimization to the surgery room. With the recent advances in tissue engineering, Paulino believes that the method can be used to construct patient-specific bone frames.

"The key idea is to have a technique that is tailored for the specific patient. It's not one formula that fits all. People are different, therefore, you cannot have one solution for all patients," said Paulino.

Final optimized result with denture inserted into the craniofacial skeleton. Credit: Glaucio H. Paulino

Engineering a face

In an experiment, researchers explored the creation of a three-dimensional structure for a patient with severe gunshot injury. After selecting a design domain from the craniofacial skeleton, supports, loads and cavity constraints (areas with no bone, such as eye cavities) were applied. Topological optimization generated many possible structures to fit the patient-specific requirements.

Watch this video to see the process of creating a structure for a patient with severe gunshot injury using topological optimization. Although the results did not necessarily resemble the natural bone structure, they would preserve the vital functions of facial organs while providing a safe platform for prosthetics and plastic surgery.

The process will "show surgeons their alternatives before going into the operating room," said Paulino.

At the moment, such structures would be built using titanium, which is light and strong. Unfortunately, titanium may cause infections because it's foreign to the body. With future advances in tissue engineering, however, molding human bone tissue into a structure is a possibility. Researchers are still investigating how to ensure that the bone structure created through this process, a living tissue, will maintain the desired shape after implanted in the patient.

Paulino and his team of researchers hope to continue translating applicable concepts between different fields, such as engineering and medicine, to make innovative discoveries. With the development of tissue engineering and topological optimization, in the future, complete recovery from craniofacial injuries will hopefully be enabled by a routine procedure in the surgery room.

Provided by National Science Foundation

Read More

Artificial leaves make fuel from sunlight

Artificial leaves make fuel from sunlight

  10:06:00 AM    Science Lover

---

Two teams of researchers in the US have taken important steps towards the creation of commercially viable "artificial leaf" – a hypothetical device that can turn sunlight into electrical energy or fuel by mimicking some aspects of photosynthesis.

Daniel Nocera in his lab at the
Massachusetts Institute of Technology.
(Courtesy: Donna Coveney/MIT)

Earlier this year, the chemist Daniel Nocera at the Massachusetts Institute of Technology (MIT) announced artificial-leaf prototypes at the annual meeting of the American Chemical Society in California. Now, working with two different teams of researchers, he has published two papers on different devices that represent progress towards effective and commercially viable versions of the artificial leaf.

Here comes the Sun

Both teams made their devices from silicon wafers that are coated with catalytic metals and protective layers. The prototype solar cells are about the size of a credit card and can capture sunlight and then use the energy to split water into its constituent oxygen and hydrogen. This is different to conventional photovoltaic cells, which convert light directly into electricity. With these new devices, the ultimate plan is to recombine the two gases in an integrated fuel cell, thus converting the chemical energy to electrical energy. Producing fuel rather than electricity has the advantage that the fuel can be easily stored until it is needed.

Both artificial leaves use a silicon n–p junction: a bilayer of n-type and p-type silicon. An incident photon is absorbed to create an electron–hole pair in the semiconductor. The electrons migrate to the n-side and the holes to the p-side. The holes then drive the splitting of water in a process mediated by the outermost layer of the cell, which is a photocatalyst. Unlike some of the exotic photocatalysts used in earlier devices, the catalyst in these new devices are made of cobalt phosphate, which is an abundant and cheap material.

The main challenge in creating both devices was how to prevent the silicon from reacting with the water. The two teams took different approaches to the problem. One group led by electrical engineer Vladimir Bulovic used the catalyst itself as a protective layer, binding a thin film of pure cobalt firmly to the silicon before converting it to the phosphate form. The other team, led by mechanical engineer Tonio Buonassisi, used a thin film of conductive indium tin oxide in front of the p-type silicon as the protective layer.

Bubbles needed



Buonassisi and colleagues connected two of their cells in series and managed to split water with a solar-to-oxygen conversion efficiency of 0.25%. While this does not sound like much, the efficiency of photosynthesis is only a few per cent. However, the cells make hydrogen ions, and turning this into gas could add considerable cost to the device. "Platinum electrodes are good catalysts for reducing hydrogen ions to hydrogen gas", says Devens Gust of Arizona State University, who was not involved in the research. "However, the rarity of platinum limits its usefulness."

Gust describes the MIT work as "very important in that it demonstrates a workable, inexpensive water-oxidation catalyst". However, he says that the technology is entering a crowded market, pointing out that there is already a production technology for solar fuel that is "pretty much ready to go now". This system uses photovoltaic cells coupled to an electrolyzer that splits water into oxygen and hydrogen. "Electrolyzer efficiencies can be as high as 70–80%, and currently available photovoltaic efficiencies are as high as 15–20%", he points out. "None of the artificial photosynthetic systems can compete with this at the moment."

The MIT technology must also compete with other water-splitting systems based on silicon solar cells coated with photocatalysts. These have been in development since at least 1998 and some have reached solar-to-hydrogen conversion efficiencies of 7% or better.

"Challenges remain"

One of these cells was developed at California Institute of Technology by Nathan Lewis and Harry Atwater. Atwater told physicsworld.com that "Nocera's work is interesting, but many challenges remain." It is not clear, for example, whether the catalyst and devices remain stable beyond the few days of operation for which they have so far been tested. Atwater also thinks there is room for improvement in the materials themselves.

Gust agrees, pointing out that while cobalt and other catalysts based on common materials are promising, researchers have yet to develop an inexpensive catalyst that works near the thermodynamic potential for water oxidation/reduction. This property would help to optimize the performance of an artificial-leaf system. Nocera hopes to have a fully working device within about three years, and he has formed a company called SunCatalytix to develop it.

The work by Bulovic's group is published in Energy & Environmental Science, while the research by Buonassisi's group is outlined in Proceedings of the National Academy of Sciences USA.

Read More

Report Faults BBC Science Coverage

Report Faults BBC Science Coverage

  12:33:00 AM    Science Lover

---

Journalists should focus more on accurately representing the science of climate change and vaccinations and less on impartiality, a new review finds.

Meltic Arctic sea ice
NASA Godard Space Flight Center

There may be two sides to every story, but sometimes only one is right. That’s the gist of a new review of BBC’s science coverage, which suggests journalists should focus more on accurately presenting the scientific consensus and less on presenting both sides on controversial issues such as climate change, genetically engineered foods, or the discredited link between vaccines and autism.

Overall, however, the review, which was commissioned by the BBC Trust, praised BBC’s science coverage. But the analysis of 8 weeks of media content conducted by Imperial College London geneticist Steve Jones did highlight several areas for improvement. In addition to giving too much space to fringe views such as climate change skepticism, the report also faulted the media outlet for lacking strong science contacts and for depending too heavily on press releases. The BBC has reviewed the findings and is already on board with one of its recommendations: hiring a science news editor, ScienceInsider reports.

Read More

Endangered river turtle's genes reveal ancient influence of Maya Indians

Endangered river turtle's genes reveal ancient influence of Maya Indians

  7:35:00 PM    Science Lover

---

A genetic study focusing on the Central American river turtle (Dermatemys mawii) recently turned up surprising results for a team of Smithsonian scientists involved in the conservation of this critically endangered species. Small tissue samples collected from 238 wild turtles at 15 different locations across their range in Southern Mexico, Belize and Guatemala revealed a "surprising lack" of genetic structure, the scientists write in a recent paper in the journal Conservation Genetics.

A genetic study focusing on the Central American river
turtle (Dermatemys mawii) recently turned up surprising
results for a team of Smithsonian scientists involved in
conserving this critically endangered species. Small tissue
samples collected from 238 wild turtles at 15 different
locations across their range in Southern Mexico, Belize and
Guatemala revealed a "surprising lack" of genetic structure.
Credit: Photo courtesy of Gracia González-Porter

The turtles, which are entirely aquatic, represent populations from three different river basins that are geographically isolated by significant distance and high mountain chains.

"We were expecting to find a different genetic lineage in each drainage basin," explains the paper's main author Gracia González-Porter of the Center for Conservation and Evolutionary Genetics at the Smithsonian Conservation Biology Institute. "Instead, we found the mixing of lineages. It was all over the place." Despite appearing isolated, the genetic data showed the different turtle populations had been in close contact for years.

"But how?" the researchers wondered.

The best possible explanation, González-Porter and her colleagues say, is that for centuries humans have been bringing them together. The turtles have been used as food, in trade and in rituals for millennia, widely transported and customarily kept in holding ponds till they were needed.

"For centuries, this species has been part of the diet of the Mayans and other indigenous people who lived in its historic distribution range," the scientists point out in their paper. "D. mawii was a very important source of animal protein for the ancient Mayans of the Peten (Preclassic period 800-400 B.C.)…. And it is possible that these turtles were part of the diet of the Olmec culture more than 3,000 years ago."



One specimen of D. mawii was found in an ancient Teotihuacan burial site in Mexico, a spot located more than 186 miles from the known range of this turtle, the researchers say. An ancient sculpture of a Central American river turtle at the National Museum of Anthropology in Mexico City was found in the Basin of Mexico, more than 217 miles from the turtle's range.

"The Central American River turtle is tame and resilient," González-Porter explains, "which makes it easy to transport. Their shells give them lots of protection. People don't have refrigeration so they put the turtles in ponds in their back yards."

During the rainy season in the tropics, the water flows are huge, she says. Rivers and ponds flood, captive turtles escape and mix with the local turtles.

This ancient practice still persists today. In Guatemala, Central American river turtles are kept in medium-sized ponds where they can be easily captured when needed. Similarly, in the State of Tabasco, Mexico, captured turtles are kept in rustic ponds and raised until they are either consumed or sold.

The genetic analysis of the Central American River turtle was initiated because these animals are critically endangered, González-Porter says.

They are the last surviving species of the giant river turtles of the family Dermatemydidae. D. mawii is currently the most endangered turtle species in Central America. A recent increase in the commercial demand for its meat has pushed it to the brink of extinction—2.2 pounds of their meat can fetch $100. Most local populations have disappeared and this turtle is now largely restricted to remote areas that are inaccessible to humans.

Read More