Thursday, April 28, 2011

Good Eggs: Nanomagnets Offer Food for Thought About Computer Memories

For a study described in a new paper, NIST researchers used electron-beam lithography to make thousands of nickel-iron magnets, each about 200 nanometers (billionths of a meter) in diameter. Each magnet is ordinarily shaped like an ellipse, a slightly flattened circle. Researchers also made some magnets in three different egglike shapes with an increasingly pointy end. It's all part of NIST research on nanoscale magnetic materials, devices and measurement methods to support development of future magnetic data storage systems.

It turns out that even small distortions in magnet shape can lead to significant changes in magnetic properties. Researchers discovered this by probing the magnets with a laser and analyzing what happens to the"spins" of the electrons, a quantum property that's responsible for magnetic orientation. Changes in the spin orientation can propagate through the magnet like waves at different frequencies. The more egg-like the magnet, the more complex the wave patterns and their related frequencies. (Something similar happens when you toss a pebble in an asymmetrically shaped pond.) The shifts are most pronounced at the ends of the magnets.

To confirm localized magnetic effects and"color" the eggs, scientists made simulations of various magnets using NIST's object-oriented micromagnetic framework (OOMMF). Lighter colors indicate stronger frequency signals.

The egg effects explain erratic behavior observed in large arrays of nanomagnets, which may be imperfectly shaped by the lithography process. Such distortions can affect switching in magnetic devices. The egg study results may be useful in developing random-access memories (RAM) based on interactions between electron spins and magnetized surfaces. Spin-RAM is one approach to making future memories that could provide high-speed access to data while reducing processor power needs by storing data permanently in ever-smaller devices. Shaping magnets like eggs breaks up a symmetric frequency pattern found in ellipse structures and thus offers an opportunity to customize and control the switching process.

"For example, intentional patterning of egg-like distortions into spinRAM memory elements may facilitate more reliable switching," says NIST physicist Tom Silva, an author of the new paper.

"Also, this study has provided the Easter Bunny with an entirely new market for product development."


Tuesday, April 26, 2011

Romance Is Not Dead: Digital Puts the Spark Back Into Relationships

Few people mull over a text message, however heartfelt, in the same way as a handwritten declaration of love, but a Newcastle University team is looking to prove that using digital communication doesn't necessarily mean that romance is dead.

They have created digital 'Lovers' Boxes' that draw on the aesthetics of traditional wooden jewellery boxes, but actually contain the latest technology to enable couples to record romantic messages for each other.

Featured in the current edition of International Journal of Human-Computer Studies (May 2011), the initial boxes they designed for couples to trial are made from four different woods (cherry, beech, apple and walnut).

Each box consists of two halves connected by brass hinges, decorated with ornate carvings, with an antique keyhole at the front.

A computer with an integrated RFID reader is hidden inside the box. Other than the screen itself, all visible trappings of digital technology are hidden from view.

Once unlocked, the box opens in a book-like manner, and a screen becomes visible. A wooden passé-partout with rounded edges frames the screen to counter the usual connotations of a digital display.

When placed within the box, the RFID tag in the key fob triggers a video message stored within. To avoid evoking the sense of a wooden laptop-like device, the videos created by participants are not played in a typical 16:9 landscape format on the screen, but in a portrait orientation.

"The aesthetic appeal of these objects, with the mix of the antique wooden box that has to be unlocked with a physical key is really important in terms of keeping the personal messages between partners private and treasured," said Anja Thieme, the lead researcher on the project.

The Lovers' Box has been described as akin to 'an interactive storybook or jewellery box', which the participants chose to treat carefully and stow away like a precious family heirloom. This distinguishes it from more traditional and function-orientated media such as mobile phones or laptops.

The five couples in the Newcastle University study were able to create video content for one another by working with a digital media artist. Video was chosen by the research team as the media format as it allows the scope and flexibility to not only present text and pictures, but also moving pictures and sound.

They could personalise their messages further by configuring the time, window and dates at which the message would play, and the amount of times it could be played. For example, they could set it so the video message could be played just once, on a particular day.

The research findings showed that the creation, exchange and display of personal messages embedded in the box served as both mirrors and sources for reflection within their relationships.

Participants perceived their box as a keepsake or digital storybook of their meaningful experiences, and looked upon the exchange as an enjoyable shared hobby with their partner. The video content was also regarded as a way of providing a snapshot into their minds and thoughts.

"The process of reflecting on what content to present, of putting effort into the creation of the video and handing the box over to their beloved was perceived as giving a gift of high personal significance," said Ms Thieme."In this sense, the interaction with the box created space for partners to display mutual social and emotional support and to feel valued and loved.

"This project builds on a strand of research developed in the Digital Interaction group at Culture Lab in recent years into ways of making emotionally meaningful forms of digital technologies. The Lovers' Boxes clearly illustrate the potential for a new 'breed' of digital artefacts which have the potential to enrich our personal and emotional lives."


Monday, April 25, 2011

Fractal Dimension Analysis Aids Breast Cancer Prognosis

Currently, a useful factor for deciding the best treatment strategy for early-stage breast cancer is tumour grade, a score assigned by a pathologist based on how abnormal cancer cells from a patient tissue sample look under the microscope. However, tumour grade is somewhat subjective and can vary between pathologists. Hence, there is a need for more objective methods to assess cancer tissue, which could improve risk assessment and therapeutic decisions.

Using a mathematical computer program developed at the U of C , Mauro Tamabsco, PhD, and his team used fractal dimension analysis to quantitatively assess the degree of abnormality and aggressiveness of breast cancer tumours obtained through biopsy. Fractal analysis of images of breast tissue specimens provides a numeric description of tumour growth patterns as a continuous number between 1 and 2. This number, the fractal dimension, is an objective and reproducible measure of the complexity of the tissue architecture of the biopsy specimen. The higher the number, the more abnormal the tissue is.

According to the team's published study, this novel method of analysis is more accurate and objective than pathological grade."This new technology is not meant to replace pathologists, but is just a new digital tool for them to use" says Tambasco, a medical physicist at the University of Calgary Faculty of Medicine and the Tom Baker Cancer Center.

Researchers say they will continue to study this new digital method and hope in the next few years that it could become another tool used in the clinical setting.

The retrospective study analysed tissue specimens from 379 breast cancer patients and the findings were published in the January 2011 edition of theJournal of Translational Medicine.


Friday, April 22, 2011

'Time Machine' Made to Visually Explore Space and Time in Videos: Time-Lapse GigaPans Provide New Way to Access Big Data

Viewers, for instance, can use the system to focus in on the details of a booth within a panorama of a carnival midway, but also reverse time to see how the booth was constructed. Or they can watch a group of plants sprout, grow and flower, shifting perspective to watch some plants move wildly as they grow while others get eaten by caterpillars. Or, they can view a computer simulation of the early universe, watching as gravity works across 600 million light-years to condense matter into filaments and finally into stars that can be seen by zooming in for a close up.

"With GigaPan Time Machine, you can simultaneously explore space and time at extremely high resolutions," said Illah Nourbakhsh, associate professor of robotics and head of the CREATE Lab."Science has always been about narrowing your point of view -- selecting a particular experiment or observation that you think might provide insight. But this system enables what we call exhaustive science, capturing huge amounts of data that can then be explored in amazing ways."

The system is an extension of the GigaPan technology developed by the CREATE Lab and NASA, which can capture a mosaic of hundreds or thousands of digital pictures and stitch those frames into a panorama that be interactively explored via computer. To extend GigaPan into the time dimension, image mosaics are repeatedly captured at set intervals, and then stitched across both space and time to create a video in which each frame can be hundreds of millions, or even billions of pixels.

An enabling technology for time-lapse GigaPans is a feature of the HTML5 language that has been incorporated into such browsers as Google's Chrome and Apple's Safari. HTML5, the latest revision of the HyperText Markup Language (HTML) standard that is at the core of the Internet, makes browsers capable of presenting video content without use of plug-ins such as Adobe Flash or Quicktime.

Using HTML5, CREATE Lab computer scientists Randy Sargent, Chris Bartley and Paul Dille developed algorithms and software architecture that make it possible to shift seamlessly from one video portion to another as viewers zoom in and out of Time Machine imagery. To keep bandwidth manageable, the GigaPan site streams only those video fragments that pertain to the segment and/or time frame being viewed.

"We were crashing the browsers early on," Sargent recalled."We're really pushing the browser technology to the limits."

Guidelines on how individuals can capture time-lapse images using GigaPan cameras are included on the site created for hosting the new imagery's large data files, Sargent explained the CREATE Lab is eager to work with people who want to capture Time Machine imagery with GigaPan, or use the visualization technology for other applications.

Once a Time Machine GigaPan has been created, viewers can annotate and save their explorations of it in the form of video"Time Warps."

Though the time-lapse mode is an extension of the original GigaPan concept, scientists already are applying the visualization techniques to other types of Big Data. Carnegie Mellon's Bruce and Astrid McWilliams Center for Cosmology, for instance, has used it to visualize a simulation of the early universe performed at the Pittsburgh Supercomputing Center by Tiziana Di Matteo, associate professor of physics.

"Simulations are a huge bunch of numbers, ugly numbers," Di Matteo said."Visualizing even a portion of a simulation requires a huge amount of computing itself." Visualization of these large data sets is crucial to the science, however."Discoveries often come from just looking at it," she explained.

Rupert Croft, associate professor of physics, said cosmological simulations are so massive that only a segment can be visualized at a time using usual techniques. Yet whatever is happening within that segment is being affected by forces elsewhere in the simulation that cannot be readily accessed. By converting the entire simulation into a time-lapse GigaPan, however, Croft and his Ph.D. student, Yu Feng, were able to create an image that provided both the big picture of what was happening in the early universe and the ability to look in detail at any region of interest.

Using a conventional GigaPan camera, Janet Steven, an assistant professor of biology at Sweet Briar College in Virginia, has created time-lapse imagery of rapid-growing brassicas, known as Wisconsin Fast Plants."This is such an incredible tool for plant biology," she said."It gives you the advantage of observing individual plants, groups of plants and parts of plants, all at once."

Steven, who has received GigaPan training through the Fine Outreach for Science program, said time-lapse photography has long been used in biology, but the GigaPan technology makes it possible to observe a number of plants in detail without having separate cameras for each plant. Even as one plant is studied in detail, it's possible to also see what neighboring plants are doing and how that might affect the subject plant, she added.

Steven said creating time-lapse GigaPans of entire landscapes could be a powerful tool for studying seasonal change in plants and ecosystems, an area of increasing interest for understanding climate change. Time-lapse GigaPan imagery of biological experiments also could be an educational tool, allowing students to make independent observations and develop their own hypotheses.

Google Inc. supported development of GigaPan Time Machine.


Thursday, April 21, 2011

CAPTCHAs With Chaos: Strong Protection for Weak Passwords

Researchers at the Max Planck Institute for the Physics of Complex Systems in Dresden have been inspired by the physics of critical phenomena in their attempts to significantly improve password protection. The researchers split a password into two sections. With the first, easy-to-memorize section they encrypt a CAPTCHA ("completely automated public Turing test to tell computers and humans apart") -- an image that computer programs per se have difficulty in deciphering. The researchers also make it more difficult for computers, whose task it is to automatically crack passwords, to read the passwords without authorization. They use images of a simulated physical system, which they additionally make unrecognizable with a chaotic process. These p-CAPTCHAs enable the Dresden physicists to achieve a high level of password protection, even though the user need only remember a weak password.

Computers sometimes use brute force. Hacking programs use so-called brute-force attacks to try out all possible character combinations to guess passwords. CAPTCHAs are therefore intended as an additional safeguard the input of which originates from a human being and not from a machine. They pose a task for the user which is simple enough for any human, yet very difficult for a program. Users must enter a distorted text which is displayed on the screen, for example. CAPTCHAs are increasingly being bypassed, however. Personal data of members of the"SchülerVZ" social network for school pupils have already been stolen in this way.

Researchers at the Max Planck Institute for the Physics of Complex Systems in Dresden have now developed a new type of password protection that is based on a combination of characters and a CAPTCHA. They also use mathematical methods from the physics of critical phenomena to protect the CAPTCHA from being accessed by computers."We thus make the password protection both more effective and simpler," says Konstantin Kladko, who had the idea for this interdisciplinary approach during his time at the Dresden Max Planck Institute; he is currently a researcher at Axioma Research in Palo Alto/USA.

The Dresden-based researchers initially combine password and CAPTCHA in a completely novel way. The CAPTCHA is no longer generated anew each time in order to distinguish the human user from a computer on a case-by-case basis. Rather, the physicists use the codeword in the image, which can only be deciphered by humans as the real password, which provides access to a social network or an online bank account, for example. The researchers additionally encrypt this password using a combination of characters.

However, that's not all: the CAPTCHA is a snapshot of a dynamic, chaotic Hamiltonian system in two dimensions. For the sake of simplicity, his image can be imagined as a grey-scale pixel matrix, where every pixel represents an oscillator. The oscillators are coupled in a network. Every oscillator oscillates between two states and is affected by the neighbouring oscillators as it does so, thus resulting in the grey scales.

Chaotic development makes password unreadable

The physicists then leave the system to develop chaotically for a period of time. The grey-scale matrix changes the colour of its pixels. The result is an image that no longer contains a recognizable word. The researchers subsequently encrypt this image with the combination of characters and save the result."We therefore talk of a password-protected CAPTCHA or p-CAPTCHA," says Sergej Flach, who teamed up with Tetyana Laptyeva to achieve the decisive research results at the Max Planck Institute for the Physics of Complex Systems. Since the chaotic evolution of the initial image is deterministic, i.e. reversible, the whole procedure can be reversed using the combination of characters, so that the user can again read the password hidden in the CAPTCHA.

"The character combination we use to encrypt the password in the CAPTCHA can be very easy to remember," explains Konstantin Kladko."We thus take account of the fact that most people only want to, or can only, remember simple passwords." The fact that the passwords are correspondingly weak is now no longer important, because the real protection comes from the encrypted password in the CAPTCHA.

On the one hand, the password hidden in the CAPTCHA is too long for computers to be able to guess it using a brute-force attack in a reasonable length of time. On the other, the physicists use a critical system to generate the password image. This system is close to a phase transition: with a phase transition, the system changes from one physical state to another, from the paramagnetic to the ferromagnetic state, for example. Close to the transition, regions repeatedly form which temporarily have already completed the transition."The resulting image is always very grainy. Therefore, a computer cannot distinguish it from the original it is searching for," explains Sergej Flach.

"Although the study has just been submitted to a specialist journal and is only available online in an archive, it has already provoked a large number of responses in the community -- and not only in Hacker News," says Sergej Flach."I was very impressed by the depth of some comments in certain forums -- in Slashdot, for example." The specialists are obviously impressed by the ingenuity of the approach, which means passwords could be very difficult to crack in the future. Moreover, the method is easy and quick to implement in conventional computer systems."An expansion to several p-CAPTCHA levels is obvious," says Sergej Flach. Hoiwever, this requires increased computing power to reverse the chaotic development in a reasonable time:"We therefore want to investigate various Hamiltonian and non-Hamiltonian systems in the future to see whether they provide faster and even more effective protection."


Wednesday, April 20, 2011

Clumsy Avatars: Perfection Versus Mortality in Games and Simulation

The shop is one of several projects Chang uses to explore humanity in technology. Chang, an electronic artist and recently appointed co-director of the Games and Simulation Arts and Sciences program at Rensselaer, sees the dialogue between perfection and mortality as an important influence in the growing world of games and simulation.

"There's this transcendence that technology promises us. At its extreme is the notion of immortality that -- with artificial intelligence, robotics, and virtual reality -- you could download your consciousness and take yourself out of the limitations of the physical body," said Chang."But at the same time, that's what makes us human: our frailty and our mortality."

In other words, while the"sell" behind technology is often about achieving perfection (with a smart phone all the answers are at hand, with GPS we never lose our way, in Second Life we are beautiful), the risk is a loss of humanity.

That dialogue and tension leads Chang to believe that the nascent world of gaming and simulation could become"a new cultural form" as great as literature, art, music, and theater.

"This is just the beginning; we don't really know what this is going to be, and 'games and simulation' is just the best term we have to describe a much larger form," said Chang."Twenty years ago nobody knew what the Web was going to be. There was this huge form on the horizon that we were sort of fumbling toward with different technological experiments, artistic experiments; I think this is what's going on with games and simulation right now.

"There are many things that are very difficult to do hands-on -- it's very difficult to simulate a disaster, it's very difficult to manipulate atoms and molecules at the atomic level -- and this is where simulation comes in handy," said Chang."That kind of learning experience, that way of gaining knowledge that's intuitive, that comes through experience and involvement, can be expanded to many other realms."

As an electronic artist, Chang's own work is at the intersection of virtual environments, experimental gaming, and contemporary media art.

"I'm interested in what you could call evocative and poetic experiences within technological systems -- creating that powerful experience that you can get from great music, theater, books, and paintings through immersive and interactive simulations as well," Chang said."But I'm also interested in the experiences of being human within technological systems."

Other recent projects include"Becoming," a computer-driven video installation in which the attributes of two animated figures -- each inhabiting their own space -- are interchanged."Over time, this causes each figure to take on the attributes of the other, distorted by the structure of their digital information."

In"Insecurity Camera," an installation shown at art exhibits around the country, a"shy" security camera turns away at the approach of subjects.

"What I'm interested in is getting at those human qualities that are still there," Chang said."Some of this has to do with frailty, with fumbling, weakness, and failure. These are things that can get disguised, they can get swept under the rug when we think about technology."

Chang earned a bachelor of arts in computer science from Amherst College, and a master of fine arts in art and technology studies from the Art Institute of Chicago. His installations, performances, and immersive virtual reality environments have been exhibited in numerous venues and festivals worldwide, including Boston CyberArts, SIGGRAPH, the FILE International Electronic Language Festival in Sao Paulo, the Athens MediaTerra Festival, the Wired NextFest, and the Vancouver New Forms Festival, among others. He has designed interactive exhibits for museums such as the Museum of Contemporary Art in Chicago and the Field Museum of Natural History.

Chang teaches a two-semester game development course that joins students with backgrounds in all aspects of games -- computer programming, computer science, design, art, and writing -- in the process of creating games. The students start with a design, and proceed through all the steps of planning, creating art work, writing code, and refining their game.

"Think of it as a foundation into developing games that you can take into experimental game design and stretch beyond it," Chang said.

As the"new cultural form" evolves, Chang sees ample room for exploration.

For example, said Chang, virtual reality, in which experiences are staged in a wholly digital world, leads to different implications than augmented reality, in which digital elements overlay the physical world. One implication of virtual reality -- in which, as in Second Life, users can experiment with their identity -- lies in research which suggests that personal growth gains made within the virtual world transfer to the real world. One implication of augmented reality -- in which users may add digital elements that only they can access -- is the possibility of several people sharing the same physical world while experiencing divergent realities.

In the near term, the most immediate implications for the emerging form are, as might be expected, in entertainment and education.

"What's already happening is this enrichment of the notion of what entertainment is through games," Chang said."When you talk about games, you often have ideas of simple first-person shooter or action games. But within the realm of entertainment is an immense diversity of possibilities -- from complex emotional dramatic story-based games to casual games on your cell phone. There's this range of ways of playing from competitive, multiplayer, social to creative. This is just within the entertainment realm."


Tuesday, April 19, 2011

Super-Small Transistor Created: Artificial Atom Powered by Single Electrons

The researchers report inNature Nanotechnologythat the transistor's central component -- an island only 1.5 nanometers in diameter -- operates with the addition of only one or two electrons. That capability would make the transistor important to a range of computational applications, from ultradense memories to quantum processors, powerful devices that promise to solve problems so complex that all of the world's computers working together for billions of years could not crack them.

In addition, the tiny central island could be used as an artificial atom for developing new classes of artificial electronic materials, such as exotic superconductors with properties not found in natural materials, explained lead researcher Jeremy Levy, a professor of physics and astronomy in Pitt's School of Arts and Sciences. Levy worked with lead author and Pitt physics and astronomy graduate student Guanglei Cheng, as well as with Pitt physics and astronomy researchers Feng Bi, Daniela Bogorin,and Cheng Cen. The Pitt researchers worked with a team from the University of Wisconsin at Madison led by materials science and engineering professor Chang-Beom Eom, including research associates Chung Wun Bark, Jae-Wan Park, and Chad Folkman. Also part of the team were Gilberto Medeiros-Ribeiro, of HP Labs, and Pablo F. Siles, a doctoral student at the State University of Campinas in Brazil.

Levy and his colleagues named their device SketchSET, or sketch-based single-electron transistor, after a technique developed in Levy's lab in 2008 that works like a microscopic Etch A SketchTM, the drawing toy that inspired the idea. Using the sharp conducting probe of an atomic force microscope, Levy can create such electronic devices as wires and transistors of nanometer dimensions at the interface of a crystal of strontium titanate and a 1.2 nanometer thick layer of lanthanum aluminate. The electronic devices can then be erased and the interface used anew.

The SketchSET -- which is the first single-electron transistor made entirely of oxide-based materials -- consists of an island formation that can house up to two electrons. The number of electrons on the island -- which can be only zero, one, or two -- results in distinct conductive properties. Wires extending from the transistor carry additional electrons across the island.

One virtue of a single-electron transistor is its extreme sensitivity to an electric charge, Levy explained. Another property of these oxide materials is ferroelectricity, which allows the transistor to act as a solid-state memory. The ferroelectric state can, in the absence of external power, control the number of electrons on the island, which in turn can be used to represent the 1 or 0 state of a memory element. A computer memory based on this property would be able to retain information even when the processor itself is powered down, Levy said. The ferroelectric state also is expected to be sensitive to small pressure changes at nanometer scales, making this device potentially useful as a nanoscale charge and force sensor.

The research inNature Nanotechnologyalso was supported in part by grants from the U.S. Defense Advanced Research Projects Agency (DARPA), the U.S. Army Research Office, the National Science Foundation, and the Fine Foundation.


Sunday, April 17, 2011

Hydrocarbons Deep Within Earth: New Computational Study Reveals How

The thermodynamic and kinetic properties of hydrocarbons at high pressures and temperatures are important for understanding carbon reservoirs and fluxes in Earth.

The work provides a basis for understanding experiments that demonstrated polymerization of methane to form high hydrocarbons and earlier methane forming reactions under pressure.

Hydrocarbons (molecules composed of the elements hydrogen and carbon) are the main building block of crude oil and natural gas. Hydrocarbons contribute to the global carbon cycle (one of the most important cycles of Earth that allows for carbon to be recycled and reused throughout the biosphere and all of its organisms).

The team includes colleagues at UC Davis, Lawrence Livermore National Laboratory and Shell Projects& Technology. One of the researchers, UC Davis Professor Giulia Galli, is the co-chair of the Deep Carbon Observatory's Physics and Chemistry of Deep Carbon Directorate and former LLNL researcher.

Geologists and geochemists believe that nearly all (more than 99 percent) of the hydrocarbons in commercially produced crude oil and natural gas are formed by the decomposition of the remains of living organisms, which were buried under layers of sediments in Earth's crust, a region approximately 5-10 miles below Earth's surface.

But hydrocarbons of purely chemical deep crustal or mantle origin (abiogenic) could occur in some geologic settings, such as rifts or subduction zones said Galli, a senior author on the study.

"Our simulation study shows that methane molecules fuse to form larger hydrocarbon molecules when exposed to the very high temperatures and pressures of the Earth's upper mantle," Galli said."We don't say that higher hydrocarbons actually occur under the realistic 'dirty' Earth mantle conditions, but we say that the pressures and temperatures alone are right for it to happen.

Galli and colleagues used the Mako computer cluster in Berkeley and computers at Lawrence Livermore to simulate the behavior of carbon and hydrogen atoms at the enormous pressures and temperatures found 40 to 95 miles deep inside Earth. They used sophisticated techniques based on first principles and the computer software system Qbox, developed at UC Davis.

They found that hydrocarbons with multiple carbon atoms can form from methane, (a molecule with only one carbon and four hydrogen atoms) at temperatures greater than 1,500 K (2,240 degrees Fahrenheit) and pressures 50,000 times those at Earth's surface (conditions found about 70 miles below the surface).

"In the simulation, interactions with metal or carbon surfaces allowed the process to occur faster -- they act as 'catalysts,'" said UC Davis' Leonardo Spanu, the first author of the paper.

The research does not address whether hydrocarbons formed deep in Earth could migrate closer to the surface and contribute to oil or gas deposits. However, the study points to possible microscopic mechanisms of hydrocarbon formation under very high temperatures and pressures.

Galli's co-authors on the paper are Spanu; Davide Donadio at the Max Planck Institute in Meinz, Germany; Detlef Hohl at Shell Global Solutions, Houston; and Eric Schwegler of Lawrence Livermore National Laboratory.


Saturday, April 16, 2011

New Way to Control Magnetic Properties of Graphene Discovered

The finding by a team of Maryland researchers, led by Physics Professor Michael S. Fuhrer of the UMD Center for Nanophysics and Advanced Materials is the latest of many amazing properties discovered for graphene.

A honeycomb sheet of carbon atoms just one atom thick, graphene is the basic constituent of graphite. Some 200 times stronger than steel, it conducts electricity at room temperature better than any other known material (a 2008 discovery by Fuhrer, et. al). Graphene is widely seen as having great, perhaps even revolutionary, potential for nanotechnology applications. The 2010 Nobel Prize in physics was awarded to scientists Konstantin Novoselov and Andre Geim for their 2004 discovery of how to make graphene.

In their new graphene discovery, Fuhrer and his University of Maryland colleagues have found that missing atoms in graphene, called vacancies, act as tiny magnets -- they have a"magnetic moment." Moreover, these magnetic moments interact strongly with the electrons in graphene which carry electrical currents, giving rise to a significant extra electrical resistance at low temperature, known as the Kondo effect. The results appear in the paper"Tunable Kondo effect in graphene with defects" published this month inNature Physics.

The Kondo effect is typically associated with adding tiny amounts of magnetic metal atoms, such as iron or nickel, to a non-magnetic metal, such as gold or copper. Finding the Kondo effect in graphene with vacancies was surprising for two reasons, according to Fuhrer.

"First, we were studying a system of nothing but carbon, without adding any traditionally magnetic impurities. Second, graphene has a very small electron density, which would be expected to make the Kondo effect appear only at extremely low temperatures," he said.

The team measured the characteristic temperature for the Kondo effect in graphene with vacancies to be as high as 90 Kelvin, which is comparable to that seen in metals with very high electron densities. Moreover the Kondo temperature can be tuned by the voltage on an electrical gate, an effect not seen in metals. They theorize that the same unusual properties of that result in graphene's electrons acting as if they have no mass also make them interact very strongly with certain kinds of impurities, such as vacancies, leading to a strong Kondo effect at a relatively high temperature.

Fuhrer thinks that if vacancies in graphene could be arranged in just the right way, ferromagnetism could result."Individual magnetic moments can be coupled together through the Kondo effect, forcing them all to line up in the same direction," he said.

"The result would be a ferromagnet, like iron, but instead made only of carbon. Magnetism in graphene could lead to new types of nanoscale sensors of magnetic fields. And, when coupled with graphene's tremendous electrical properties, magnetism in graphene could also have interesting applications in the area of spintronics, which uses the magnetic moment of the electron, instead of its electric charge, to represent the information in a computer.

"This opens the possibility of 'defect engineering' in graphene -- plucking out atoms in the right places to design the magnetic properties you want," said Fuhrer.

This research was supported by grants from the National Science Foundation and the Office of Naval Research.


Friday, April 15, 2011

New Spin on Graphene Makes It Magnetic

The results, reported inScience, could be a potentially huge breakthrough in the field of spintronics.

Spintronics is a group of emerging technologies that exploit the intrinsic spin of the electron, in addition to its fundamental electric charge that is exploited in microelectronics.

Billions of spintronics devices such as sensors and memories are already being produced. Every hard disk drive has a magnetic sensor that uses a flow of spins, and magnetic random access memory (MRAM) chips are becoming increasingly popular.

The findings are part of a large international effort involving research groups from the US, Russia, Japan and the Netherlands.

The key feature for spintronics is to connect the electron spin to electric current as current can be manipulated by means routinely used in microelectronics.

It is believed that, in future spintronics devices and transistors, coupling between the current and spin will be direct, without using magnetic materials to inject spins as it is done at the moment.

So far, this route has only been demonstrated by using materials with so-called spin-orbit interaction, in which tiny magnetic fields created by nuclei affect the motion of electrons through a crystal. The effect is generally small which makes it difficult to use.

The researchers found a new way to interconnect spin and charge by applying a relatively weak magnetic field to graphene and found that this causes a flow of spins in the direction perpendicular to electric current, making a graphene sheet magnetised.

The effect resembles the one caused by spin-orbit interaction but is larger and can be tuned by varying the external magnetic field.

The Manchester researchers also show that graphene placed on boron nitride is an ideal material for spintronics because the induced magnetism extends over macroscopic distances from the current path without decay.

The team believes their discovery offers numerous opportunities for redesigning current spintronics devices and making new ones such as spin-based transistors.

Professor Geim said:"The holy grail of spintronics is the conversion of electricity into magnetism or vice versa.

"We offer a new mechanism, thanks to unique properties of graphene. I imagine that many venues of spintronics can benefit from this finding."

Antonio Castro Neto, a physics professor from Boston who wrote a news article for theSciencemagazine which accompanies the research paper commented:"Graphene is opening doors for many new technologies.

"Not surprisingly, the 2010 Nobel Physics prize was awarded to Andre Geim and Kostya Novoselov for their groundbreaking experiments in this material.

"Apparently not satisfied with what they have accomplished so far, Geim and his collaborators have now demonstrated another completely unexpected effect that involves quantum mechanics at ambient conditions. This discovery opens a new chapter to the short but rich history of graphene."


Thursday, April 14, 2011

Creative, Online Learning Tool Helps Students Tackle Real-World Problems

A new computer interface developed at Iowa State University is helping students use what they've learned in the horticulture classroom and apply it to problems they'll face when they are on the job site.

The project, called ThinkSpace, is led by a group of ISU faculty including Ann Marie VanDerZanden, professor of horticulture and associate director of ISU's Center for Excellence in Learning and Teaching.

ThinkSpace has many different features that make it an effective way to teach using ill-structured problems. This type of problem allows students to choose from multiple paths to arrive at a solution.

By contrast, well-structured problems have a straight path to the one, clear solution.

In horticulture, the ThinkSpace platform is being used for upper-level classes and requires students to access what they've learned throughout their time studying horticulture and apply it to real-world problems.

In these classes, VanDerZanden gives students computer-delivered information about residential landscape.

That information includes illustrations of the work site, descriptions of the trees on the property, explanations of the problems the homeowner is experiencing, mock audio interview files with the property owner, and about anything else a horticulture professional would discover when approaching a homeowner with a landscape problem.

Also, just like in real life, some of the information is relevant to the problem, and some information is not.

"It forces students to take this piece of information, and that piece of information, and another piece of information, and then figure out what is wrong -- in this case with a plant," said VanDerZanden.

When the students think they have determined the problem, they enter their responses into the online program.

VanDerZanden can then check the responses.

For those students on the right track, she allows them to continue toward a solution.

For those who may have misdiagnosed the situation, VanDerZanden steers the students toward the right track before allowing them to move forward.

So far, the response from students has been very positive.

"The students like the variety," said VanDerZanden."They like struggling with real-world problems, rather that something that is just made up. On the other hand, they can get frustrated because there is not a clear-cut answer."

The entire process leverages the classroom experience into something the students can use at work.

"I think this really enhances student learning," said VanDerZanden."Students apply material from previous classes to a plausible, real-world situation. For instance students see what happens when a tree was pruned really hard to allow a piece of equipment to get into the customer's yard. As a result, the tree sends out a lot of new succulent shoots, and then there is an aphid infestation in the tree. It helps students start making all of those connections."

The ThinkSpace interface was developed from existing technologies already being used in ISU's College of Veterinary Medicine, College of Engineering and department of English.

VanDerZanden and her group recently received a$446,000 grant from the United States Department of Agriculture Higher Education Challenge Grant program to further develop ThinkSpace so it could more useful to other academic areas and universities.

As part of this research, VanDerZanden is also working with faculty members at University of Pennsylvania, Philadelphia; University of Wisconsin, Madison; and Kansas State University, Manhattan.


Wednesday, April 13, 2011

Privacy Mode Helps Secure Android Smartphones

"There are a lot of concerns about potential leaks of personal information from smartphones," says Dr. Xuxian Jiang, an assistant professor of computer science at NC State and co-author of a paper describing the research."We have developed software that creates a privacy mode for Android systems, giving users flexible control over what personal information is available to various applications." The privacy software is called Taming Information-Stealing Smartphone Applications (TISSA).

TISSA works by creating a privacy setting manager that allows users to customize the level of information each smartphone application can access. Those settings can be adjusted any time that the relevant applications are being run -- not just when the applications are installed.

The TISSA prototype includes four possible privacy settings for each application. These settings are Trusted, Anonymized, Bogus and Empty. If an application is listed as Trusted, TISSA does not impose additional information access restrictions. If the user selects Anonymized, TISSA provides the application with generalized information that allows the application to run, without providing access to detailed personal information. The Bogus setting provides an application with fake results when it requests personal information. The Empty setting responds to information requests by saying the relevant information does not exist or is unavailable.

Jiang says TISSA could be easily modified to incorporate additional settings that would allow more fine-grained control of access to personal information."These settings may be further specialized for different types of information, such as your contact list or your location," Jiang says."The settings can also be specialized for different applications."

For example, a user may install a weather application that requires location data in order to provide the user with the local weather forecast. Rather than telling the application exactly where the user is, TISSA could be programmed to give the application generalized location data -- such as a random location within a 10-mile radius of the user. This would allow the weather application to provide the local weather forecast information, but would ensure that the application couldn't be used to track the user's movements.

The researchers are currently exploring how to make this software available to Android users."The software modification is relatively minor," Jiang says,"and could be incorporated through an over-the-air update."

The paper,"Taming Information-Stealing Smartphone Applications (on Android)," was co-authored by Jiang; Yajin Zhou, a Ph.D. student at NC State; Dr. Vincent Freeh, an associate professor of computer science at NC State; and Dr. Xinwen Zhang of Huawei America Research Center. The paper will be presented in June at the 4th International Conference on Trust and Trustworthy Computing, in Pittsburgh, Pa. The research was supported by the National Science Foundation and NC State's Secure Open Systems Initiative, which receives funding from the U.S. Army Research Office.


Tuesday, April 12, 2011

Wii Key to Helping Kids Balance

The Rice engineering students created the new device using components of the popular Nintendo game system to create a balance training system.

What the kids may see as a fun video game is really a sophisticated way to help them advance their skills. The Wii Balance Boards lined up between handrails will encourage patients age 6 to 18 to practice their balance skills in an electronic gaming environment. The active handrails, which provide feedback on how heavily patients depend on their arms, are a unique feature.

Many of the children targeted for this project have cerebral palsy, spina bifida or amputations. Using the relatively inexpensive game console components improves the potential of this system to become a cost-effective addition to physical therapy departments in the future.

Steven Irby, an engineer at Shriners' Motion Analysis Laboratory, pitched the idea to Rice's engineering mentors after the success of last year's Trek Tracker project, a computer-controlled camera system for gait analysis that was developed by engineering students at Rice's Oshman Engineering Design Kitchen (OEDK).

The engineering seniors who chose to tackle this year's new project -- Michelle Pyle, Drew Berger and Matt Jones, aka Team Equiliberators -- hope to have the system up and running at Shriners Hospital before they graduate next month.

"He (Irby) wants to get kids to practice certain tasks in their games, such as standing still, then taking a couple of steps and being able to balance, which is pretty difficult for some of them," Pyle said."The last task is being able to take a couple of steps and then turn around."

"This isn't a measurement device as much as it is a game," Irby said."But putting the two systems together is what makes it unique. The Wii system is not well suited to kids with significant balance problems; they can't play it. So we're making something that is more adaptable to them."

The game requires patients to shoot approaching monsters by hitting particular spots with their feet as they step along the Wii array, computer science student Jesus Cortez, one of the game's creators, explained. The game gets harder as the patients improve, he said, and the chance to rack up points gives them an incentive.

A further step, not yet implemented, would be to program feedback from the handrails into the game. Leaning on the rails would subtract points from the users' scores, encouraging them to improve their postures. The game would also present challenges specific to younger and older children to keep them engaged.

The programming team also includes undergraduate Irina Patrikeeva and graduate student Nick Zhu. Studio arts undergraduate Jennifer Humphreys created the artwork.

The system's components include a PC, the Wii boards (aligned in a frame) and two balance beam-like handrails that read how much force patients are putting on their hands. Communications to the PC are handled via the Wii's native Bluetooth protocol.

The students said their prototype cost far less than the$2,000 they'd budgeted. Rice supplied the computer equipment and LabVIEW software they needed to create the diagnostic software that interfaces with Shriners' existing systems, and they purchased the Wii Balance Boards on eBay.

"Small force plates that people commonly use for such measurements cost at least a couple of grand, but Wii boards -- and people have done research on this -- give you a pretty good readout of your center of balance for what they cost," Pyle said.

Jones, who is building the final unit for delivery to Shriners, said he wants patients to see the Wii boards."We're putting clear acrylic over the boards so there aren't any gaps that could trip up the younger ones," he said."We wanted to use a device that's familiar to them, but they might not be convinced it's a Wii board unless they can see it."


Monday, April 11, 2011

Mapping the Brain: New Technique Poised to Untangle the Complexity of the Brain

A new area of research is emerging in the neuroscience known as 'connectomics'. With parallels to genomics, which maps the our genetic make-up, connectomics aims to map the brain's connections (known as 'synapses'). By mapping these connections -- and hence how information flows through the circuits of the brain -- scientists hope to understand how perceptions, sensations and thoughts are generated in the brain and how these functions go wrong in diseases such as Alzheimer's disease, schizophrenia and stroke.

Mapping the brain's connections is no trivial task, however: there are estimated to be one hundred billion nerve cells ('neurons') in the brain, each connected to thousands of other nerve cells -- making an estimated 150 trillion synapses. Dr Tom Mrsic-Flogel, a Wellcome Trust Research Career Development Fellow at UCL (University College London), has been leading a team of researchers trying to make sense of this complexity.

"How do we figure out how the brain's neural circuitry works?" he asks."We first need to understand the function of each neuron and find out to which other brain cells it connects. If we can find a way of mapping the connections between nerve cells of certain functions, we will then be in a position to begin developing a computer model to explain how the complex dynamics of neural networks generate thoughts, sensations and movements."

Nerve cells in different areas of the brain perform different functions. Dr Mrsic-Flogel and colleagues focus on the visual cortex, which processes information from the eye. For example, some neurons in this part of the brain specialise in detecting the edges in images; some will activate upon detection of a horizontal edge, others by a vertical edge. Higher up in visual hierarchy, some neurons respond to more complex visual features such as faces: lesions to this area of the brain can prevent people from being able to recognise faces, even though they can recognise individual features such as eyes and the nose, as was famously described in the book The Man Who Mistook Wife for a Hat by Oliver Sachs.

In a study published online April 10 in the journalNature, the team at UCL describe a technique developed in mice which enables them to combine information about the function of neurons together with details of their synaptic connections.

The researchers looked into the visual cortex of the mouse brain, which contains thousands of neurons and millions of different connections. Using high resolution imaging, they were able to detect which of these neurons responded to a particular stimulus, for example a horizontal edge.

Taking a slice of the same tissue, the researchers then applied small currents to a subset of neurons in turn to see which other neurons responded -- and hence which of these were synaptically connected. By repeating this technique many times, the researchers were able to trace the function and connectivity of hundreds of nerve cells in visual cortex.

The study has resolved the debate about whether local connections between neurons are random -- in other words, whether nerve cells connect sporadically, independent of function -- or whether they are ordered, for example constrained by the properties of the neuron in terms of how it responds to particular stimuli. The researchers showed that neurons which responded very similarly to visual stimuli, such as those which respond to edges of the same orientation, tend to connect to each other much more than those that prefer different orientations.

Using this technique, the researchers hope to begin generating a wiring diagram of a brain area with a particular behavioural function, such as the visual cortex. This knowledge is important for understanding the repertoire of computations carried out by neurons embedded in these highly complex circuits. The technique should also help reveal the functional circuit wiring of regions that underpin touch, hearing and movement.

"We are beginning to untangle the complexity of the brain," says Dr Mrsic-Flogel."Once we understand the function and connectivity of nerve cells spanning different layers of the brain, we can begin to develop a computer simulation of how this remarkable organ works. But it will take many years of concerted efforts amongst scientists and massive computer processing power before it can be realised."

The research was supported by the Wellcome Trust, the European Research Council, the European Molecular Biology Organisation, the Medical Research Council, the Overseas Research Students Award Scheme and UCL.

"The brain is an immensely complex organ and understanding its inner workings is one of science's ultimate goals," says Dr John Williams, Head of Neuroscience and Mental Health at the Wellcome Trust."This important study presents neuroscientists with one of the key tools that will help them begin to navigate and survey the landscape of the brain."


Sunday, April 10, 2011

Element Germanium Under Pressure Matches Predictions of Modern Condensed Matter Theory

New research conducted by Xiao-Jia Chen, Viktor Struzhkin, and Ho-Kwang (Dave) Mao from Geophysical Laboratory at Carnegie Institution for Science, along with collaborators from China, reveals details of the element's transitions under pressure. Their results show extraordinary agreement with the predictions of modern condensed matter theory.

Germanium (atomic number 32) is used in fiber-optic systems, specialized camera and microscope lenses, circuitry, and solar cells. Under ambient conditions it is brittle and semiconducting. But under pressure, the element should exhibit superconductivity, meaning that there is no resistance to the flow of an electric current.

The team's research, published inPhysical Review Letters, discovered that under pressure of 66 GPa (about 650,000 atmospheres), germanium undergoes a structural change from one type of solid material to another that is metallic -- meaning it conducts electricity. It then undergoes another structural change under pressure of 90 GPa (about 890,000 atmospheres). These findings matched theoretical predictions about the element's behavior under extreme pressure.

"A series of phase transitions was observed on compression of germanium that creates structures with increased density," Chen said."We found extraordinary agreement between theory and experiment for the structures, energies, and compressional behavior. Though some of this behavior had been noted earlier, the agreement between the new highly accurate experimental results and theory really was quite remarkable."

The team's results show that superconductivity in this simple element is caused by phonons, or collective vibrations in the crystal structures that germanium assumes under pressure.


Saturday, April 9, 2011

Free Software Makes Computer Mouse Easier for People With Disabilities

So it often goes for computer users whose motor disabilities prevent them from easily using a mouse.

As the population ages, more people are having trouble with motor control, but a University of Washington team has invented two mouse cursors that make clicking targets a whole lot easier. And neither requires additional computer hardware -- just some free, downloadable software. The researchers hope that in exchange for the software, users offer feedback.

The Pointing Magnifier combines an area cursor with visual and motor magnification, reducing need for fine, precise pointing. The UW's AIM Research Group, which invented the Pointing Magnifier, learned that users can much more easily acquire targets, even small ones, 23 percent faster with the Pointing Magnifier.

The magnifier runs on Windows-based computer systems. It replaces the conventional cursor with a larger, circular cursor that can be made even larger for users who have less motor control. To acquire a target, the user places the large cursor somewhere over the target, and clicks. The Pointing Magnifier then magnifies everything under that circular area until it fills the screen, making even tiny targets large. The user then clicks with a point cursor inside that magnified area, acquiring the target. Although the Pointing Magnifier requires two clicks, it's much easier to use than a conventional mouse, which can require many clicks to connect with a target.

Screen magnifiers for people with visual impairments have been around a long time, but such magnifiers affect only the size of screen pixels, not the motor space in which users act, thus offering no benefit to users with motor impairments. The Pointing Magnifier enlarges both visual and motor space.

Software for the Pointing Magnifier includes a control panel that allows the user to adjust color, transparency level, magnification factor, and area cursor size. User preferences are saved when the application is closed. Keyboard shortcuts quickly enable or disable the Pointing Magnifier. The UW team is also making shortcuts customizable.

"It's less expensive to create computer solutions for people who have disabilities if you focus on software rather than specialized hardware, and software is usually easier to procure than hardware," said Jacob O. Wobbrock, an assistant professor in the Information School who leads the AIM Group.

His group's paper on enhanced area cursors, including the Pointing Magnifier, was presented at the 2010 User Interface Software and Technology symposium in New York. A follow-on paper will be presented at a similar conference in May.

Another AIM technology, the Angle Mouse, similarly helps people with disabilities. Like the Pointing Magnifier, it may be downloaded, and two videos, one for general audiences and another for academic ones, are available as well.

When the Angle Mouse cursor initially blasts towards a target, the spread of movement angles, even for people with motor impairments, tends to be narrow, so the Angle Mouse keeps the cursor moving fast. However, when the cursor nears its target and the user tries to land, the angles formed by movements diverge sharply, so the Angle Mouse slows the cursor, enlarges motor space and makes the target easier to get into. The more trouble a user has, the larger the target will be made in motor space. (The target's visual appearance will not change.)

Wobbrock compares the Angle Mouse to a race car."On a straightaway, when the path is open, the car whips along, but in a tight corner, the car slows and makes a series of precise corrections, ensuring its accuracy."

A study of the Angle Mouse included 16 people, half of whom had motor impairments. The Angle Mouse improved motor-impaired pointing performance by 10 percent over the regular Windows™ default mouse and 11 percent over sticky icons -- an earlier innovation in which targets slow the cursor when it is inside them.

"Pointing is an essential part of using a computer, but it can be quite difficult and time consuming if dexterity is a problem," Wobbrock said."Even shaving one second off each time a person points may save hours over the course of a year."

Wobbrock suggests that users try both the Pointing Magnifier and the Angle Mouse before deciding which they prefer.

"Our cursors make ubiquitous mice, touchpads, and trackballs more effective for people with motor impairments without requiring new, custom hardware," Wobbrock said."We're achieving accessibility by improving devices that computer users already have. Making computers friendlier for everyone is the whole point of our work."

The Pointing Magnifier work was funded by the National Science Foundation and the Natural Sciences and Engineering Research Council of Canada.

Co-authors of the research paper that included the Pointing Magnifier are Leah Findlater, Alex Jansen, Kristen Shinohara, Morgan Dixon, Peter Kamb, Joshua Rakita and Wobbrock.

The Angle Mouse work was supported by Microsoft Research, Intel Research and the National Science Foundation.

Co-authors of the Angle Mouse paper are Wobbrock, James Fogarty, Shih-Yen (Sean) Liu, Shunichi Kimuro, and Susumi Harada.


Friday, April 8, 2011

iPad Helps Archaeologists

UC teams of archaeologists have spent more than a decade at the site of the Roman city that was buried under a volcano in 79 AD. The project is producing a complete archaeological analysis of homes, shops and businesses at a forgotten area inside one of the busiest gates of Pompeii, the Porta Stabia.

Through years of painstaking recording of their excavations, the researchers are exploring the social and cultural scene of a lost city and how the middle class neighborhood influenced Pompeian and Roman culture.

The standard archaeological approach to recording this history -- a 300-year tradition -- involves taking precise measurements, drawings and notes, all recorded on paper with pencil. But last summer, the researchers found that the handheld computers and their ability to digitally record and immediately communicate information held many advantages over a centuries-honed tradition of archaeological recording.

"There's a common, archival nature to what we're doing. There's a precious timelessness, a priceless sort of quality to the data that we're gathering, so we have made an industry of being very, very careful about how we record things," explains Ellis."Once we've excavated through it, it's gone, so ever since our undergraduate years, we've become very, very good and consistent at recording. We're excited about discovering there's another way," Ellis says.

"Because the trench supervisor is so busy, it can take days to share handwritten notes between trenches," explains Wallrodt."Now, we can give them an (electronic) notebook every day if they want it."

Wallrodt says one of the biggest concerns of adopting the new technology was switching from drawing on a large sheet of paper to sticking one's finger on the iPad's glass."With the iPad, there's also a lot less to carry. There's no big board for drawing, no ruler and no calculator."

The researchers say they plan to pack even more iPads on their trip to Pompeii this June. The research project is funded by the Louise Taft Semple Fund through the UC Department of Classics.

*The iPad research experiment, led by Steven Ellis, UC assistant professor of classics, and John Wallrodt, a senior research associate for the Department of Classics, has been featured on the National Geographic Channel as well as Apple's website. That's after the researchers took six iPads to UC's excavation site at Pompeii last summer. The iPads themselves were just being introduced at the time.


Thursday, April 7, 2011

Technique for Letting Brain Talk to Computers Now Tunes in Speech

In a new study, scientists from Washington University demonstrated that humans can control a cursor on a computer screen using words spoken out loud and in their head, holding huge applications for patients who may have lost their speech through brain injury or disabled patients with limited movement.

By directly connecting the patient's brain to a computer, the researchers showed that the computer could be controlled with up to 90% accuracy even when no prior training was given.

Patients with a temporary surgical implant have used regions of the brain that control speech to"talk" to a computer for the first time, manipulating a cursor on a computer screen simply by saying or thinking of a particular sound.

"There are many directions we could take this, including development of technology to restore communication for patients who have lost speech due to brain injury or damage to their vocal cords or airway," says author Eric C. Leuthardt, MD, of Washington University School of Medicine in St. Louis.

Scientists have typically programmed the temporary implants, known as brain-computer interfaces, to detect activity in the brain's motor networks, which control muscle movements.

"That makes sense when you're trying to use these devices to restore lost mobility -- the user can potentially engage the implant to move a robotic arm through the same brain areas he or she once used to move an arm disabled by injury," says Leuthardt, assistant professor of neurosurgery, of biomedical engineering and of neurobiology,"But that has the potential to be inefficient for restoration of a loss of communication."

Patients might be able to learn to think about moving their arms in a particular way to say hello via a computer speaker, Leuthardt explains. But it would be much easier if they could say hello by using the same brain areas they once engaged to use their own voices.

The research appears April 7 inThe Journal of Neural Engineering.

The devices under study are temporarily installed directly on the surface of the brain in epilepsy patients. Surgeons like Leuthardt use them to identify the source of persistent, medication-resistant seizures and map those regions for surgical removal. Researchers hope one day to install the implants permanently to restore capabilities lost to injury and disease.

Leuthardt and his colleagues have recently revealed that the implants can be used to analyze the frequency of brain wave activity, allowing them to make finer distinctions about what the brain is doing. For the new study, Leuthardt and others applied this technique to detect when patients say or think of four sounds:

  • oo, as in few
  • e, as in see
  • a, as in say
  • a, as in hat

When scientists identified the brainwave patterns that represented these sounds and programmed the interface to recognize them, patients could quickly learn to control a computer cursor by thinking or saying the appropriate sound.

In the future, interfaces could be tuned to listen to just speech networks or both motor and speech networks, Leuthardt says. As an example, he suggests that it might one day be possible to let a disabled patient both use his or her motor regions to control a cursor on a computer screen and imagine saying"click" when he or she wants to click on the screen.

"We can distinguish both spoken sounds and the patient imagining saying a sound, so that means we are truly starting to read the language of thought," he says."This is one of the earliest examples, to a very, very small extent, of what is called 'reading minds' -- detecting what people are saying to themselves in their internal dialogue."

"We want to see if we can not just detect when you're saying dog, tree, tool or some other word, but also learn what the pure idea of that looks like in your mind," he says."It's exciting and a little scary to think of reading minds, but it has incredible potential for people who can't communicate or are suffering from other disabilities."

The next step, which Leuthardt and his colleagues are working on, is to find ways to distinguish what they call"higher levels of conceptual information."

The study identified that speech intentions can be acquired through a site that is less than a centimetre wide which would require only a small insertion into the brain. This would greatly reduce the risk of a surgical procedure.


Monday, April 4, 2011

Self-Cooling Observed in Graphene Elctronics

Led by mechanical science and engineering professor William King and electrical and computer engineering professor Eric Pop, the team will publish its findings in the April 3 advance online edition of the journalNature Nanotechnology.

The speed and size of computer chips are limited by how much heat they dissipate. All electronics dissipate heat as a result of the electrons in the current colliding with the device material, a phenomenon called resistive heating. This heating outweighs other smaller thermoelectric effects that can locally cool a device. Computers with silicon chips use fans or flowing water to cool the transistors, a process that consumes much of the energy required to power a device.

Future computer chips made out of graphene -- carbon sheets 1 atom thick -- could be faster than silicon chips and operate at lower power. However, a thorough understanding of heat generation and distribution in graphene devices has eluded researchers because of the tiny dimensions involved.

The Illinois team used an atomic force microscope tip as a temperature probe to make the first nanometer-scale temperature measurements of a working graphene transistor. The measurements revealed surprising temperature phenomena at the points where the graphene transistor touches the metal connections. They found that thermoelectric cooling effects can be stronger at graphene contacts than resistive heating, actually lowering the temperature of the transistor.

"In silicon and most materials, the electronic heating is much larger than the self-cooling," King said."However, we found that in these graphene transistors, there are regions where the thermoelectric cooling can be larger than the resistive heating, which allows these devices to cool themselves. This self-cooling has not previously been seen for graphene devices."

This self-cooling effect means that graphene-based electronics could require little or no cooling, begetting an even greater energy efficiency and increasing graphene's attractiveness as a silicon replacement.

"Graphene electronics are still in their infancy; however, our measurements and simulations project that thermoelectric effects will become enhanced as graphene transistor technology and contacts improve" said Pop, who is also affiliated with the Beckman Institute for Advanced Science, and the Micro and Nanotechnology Laboratory at the U. of I.

Next, the researchers plan to use the AFM temperature probe to study heating and cooling in carbon nanotubes and other nanomaterials.

King also is affiliated with the department of materials science and engineering, the Frederick Seitz Materials Research Laboratory, the Beckman Institute, and the Micro and Nanotechnology Laboratory.

The Air Force Office of Scientific Research and the Office of Naval Research supported this work. Co-authors of the paper included graduate student Kyle Grosse, undergraduate Feifei Lian and postdoctoral researcher Myung-Ho Bae.


Friday, April 1, 2011

World First: Calculations With 14 Quantum Bits

The term entanglement was introduced by the Austrian Nobel laureate Erwin Schrödinger in 1935, and it describes a quantum mechanical phenomenon that while it can clearly be demonstrated experimentally, is not understood completely. Entangled particles cannot be defined as single particles with defined states but rather as a whole system. By entangling single quantum bits, a quantum computer will solve problems considerably faster than conventional computers."It becomes even more difficult to understand entanglement when there are more than two particles involved," says Thomas Monz, junior scientist in the research group led by Rainer Blatt at the Institute for Experimental Physics at the University of Innsbruck."And now our experiment with many particles provides us with new insights into this phenomenon," adds Blatt.

World record: 14 quantum bits

Since 2005 the research team of Rainer Blatt has held the record for the number of entangled quantum bits realized experimentally. To date, nobody else has been able to achieve controlled entanglement of eight particles, which represents one quantum byte. Now the Innsbruck scientists have almost doubled this record. They confined 14 calcium atoms in an ion trap, which, similar to a quantum computer, they then manipulated with laser light. The internal states of each atom formed single qubits and a quantum register of 14 qubits was produced. This register represents the core of a future quantum computer. In addition, the physicists of the University of Innsbruck have found out that the decay rate of the atoms is not linear, as usually expected, but is proportional to the square of the number of the qubits. When several particles are entangled, the sensitivity of the system increases significantly."This process is known as superdecoherence and has rarely been observed in quantum processing," explains Thomas Monz. It is not only of importance for building quantum computers but also for the construction of precise atomic clocks or carrying out quantum simulations.

Increasing the number of entangled particles

By now the Innsbruck experimental physicists have succeeded in confining up to 64 particles in an ion trap."We are not able to entangle this high number of ions yet," says Thomas Monz."However, our current findings provide us with a better understanding about the behavior of many entangled particles." And this knowledge may soon enable them to entangle even more atoms. Some weeks ago Rainer Blatt's research group reported on another important finding in this context in the scientific journalNature: They showed that ions might be entangled by electromagnetic coupling. This enables the scientists to link many little quantum registers efficiently on a micro chip. All these findings are important steps to make quantum technologies suitable for practical information processing," Rainer Blatt is convinced.

The results of this work are published in the scientific journalPhysical Review Letters. The Innsbruck researchers are supported by the Austrian Science Fund (FWF), the European Commission and the Federation of Austrian Industries Tyrol.