Tuesday, 29 October 2013

Super-Thin Membranes Clear the Way for Chip-Sized Pumps


But a super-thin silicon membrane developed at the University of Rochester could now make it possible to drastically shrink the power source, paving the way for diagnostic devices the size of a credit card.

"Up until now, electroosmotic pumps have had to operate at a very high voltage -- about 10 kilovolts," said James McGrath, associate professor of biomedical engineering. "Our device works in the range of one-quarter of a volt, which means it can be integrated into devices and powered with small batteries."

McGrath's research paper is being published this week by the journal Proceedings of the National Academy of Sciences.

McGrath and his team use porous nanocrystalline silicon (pnc-Si) membranes that are microscopically thin -- it takes more than one thousand stacked on top of each other to equal the width of a human hair. And that's what allows for a low-voltage system.

A porous membrane needs to be placed between two electrodes in order to create what's known as electroosmotic flow, which occurs when an electric field interacts with ions on a charged surface, causing fluids to move through channels. The membranes previously used in EOPs have resulted in a significant voltage drop between the electrodes, forcing engineers to begin with bulky, high-voltage power sources. The thin pnc Si membranes allow the electrodes to be placed much closer to each other, creating a much stronger electric field with a much smaller drop in voltage. As a result, a smaller power source is needed.

"Up until now, not everything associated with miniature pumps was miniaturized," said McGrath. "Our device opens the door for a tremendous number of applications."

Along with medical applications, it's been suggested that EOPs could be used to cool electronic devices. As electronic devices get smaller, components are packed more tightly, making it easier for the devices to overheat. With miniature power supplies, it may be possible to use EOPs to help cool laptops and other portable electronic devices.

McGrath said there's one other benefit to the silicon membranes. "Due to scalable fabrication methods, the nanocrystalline silicon membranes are inexpensive to make and can be easily integrated on silicon or silica-based microfluid chips."

Saturday, 26 October 2013

Persuading Light to Mix It Up With Matter

A sample of bismuth selenide, a topological insulator, is seen inside the test apparatus in Nuh Gedik's lab, ready to be studied using the team's femtosecond laser system and electron spectrometer.

The researchers suggest that this finding could lead to the creation of materials whose electronic properties could be "tuned" in real time simply by shining precise laser beams at them. The work "opens up a new avenue for optical manipulation of quantum states of matter," says Nuh Gedik, the Lawrence C. (1944) and Sarah W. Biedenharn Associate Professor of Physics and senior author of a paper published this week in Science.

Gedik, postdoc Yihua Wang (now at Stanford University), and two other MIT researchers carried out the experiments using a technique Gedik's lab has been developing for several years. Their method involves shooting femtosecond (millionths of a billionth of a second) pulses of mid-infrared light at a sample of material and observing the results with an electron spectrometer, a specialized high-speed camera the team developed.

They demonstrated the existence of a quantum-mechanical mixture of electrons and photons, known as a Floquet-Bloch state, in a crystalline solid. As first theorized by Swiss physicist Felix Bloch, electrons move in a crystal in a regular, repeating pattern dictated by the periodic structure of the crystal lattice. Photons are electromagnetic waves that have a distinct, regular frequency; their interaction with matter leads to Floquet states, named after the French mathematician Gaston Floquet. "Entangling" electrons with photons in a coherent manner generates the Floquet-Bloch state, which is periodic both in time and space.

Victor Galitski, an associate professor of physics at the University of Maryland who was not involved in this research, says, "The importance of this work is difficult to overestimate." He says it "opens new avenues not only for optical control of topological states, but also more generally for engineering of new kinds of electronic states in solid-state systems."

The researchers mixed the photons from an intense laser pulse with the exotic surface electrons on a topological insulator. Their high-speed camera captured snapshots of the exotic state, from its generation to its rapid disappearance, a process lasting only a few hundred femtoseconds. They also found there were different kinds of mixed states when the polarization of the photons changed.

Their findings suggest that it's possible to alter the electronic properties of a material -- for example, changing it from a conductor to a semiconductor -- just by changing the laser beam's polarization. Normally, to produce such dramatic changes in a material's properties, "you have to do something violent to it," Gedik says. "But in this case, it may be possible to do this just by shining light on it. That actually modifies how electrons move in this system. And when we do this, the light does not even get absorbed."

In other situations, light can modify a material's behavior -- but only when it's absorbed, transferring its energy to the material. In this experiment, Gedik says, the light's energy is below the absorption threshold. This is exciting, he says, because it opens up the possibility of switching a material's behavior back and forth without inducing other effects, such as heating -- which would happen if the light were absorbed.

It will take some time to assess possible applications, Gedik says. But, he suggests, this could be a way of engineering materials for specific functions. "Suppose you want a material to do something -- to conduct electricity, or to be transparent, for example. We usually do this by chemical means. With this new method, it may be possible to do this by simply shining light on the materials."

For example, a property called a bandgap -- a crucial characteristic for materials used in computer chips and solar cells -- can be altered by shining a polarized laser beam at the material, Wang says. "You can directly change it, open the bandgap, just with light. It means you can change it from a metal to a semiconductor, for example," he says.

Gedik says that while this experiment was done using bismuth selenide crystals, a basic topological insulator, "what we have done is not specific to topological insulators. It should also be realizable in other materials as well, such as graphene."

"In solid-state physics, we often have no other choice but to rely on serendipity when looking for interesting materials," Galitski says. The new MIT findings "partially challenge this fundamental paradigm by experimentally demonstrating that one can control at will the band structure of a material by subjecting it to an intense optical pulse."

In addition to Gedik and Wang, the team included Pablo Jarillo-Herrero, the Mitsui Career Development Associate Professor in Contemporary Technology, and visiting scientist Hadar Steinberg, both of MIT's physics department. The work was supported by the U.S. Department of Energy and the Army Research Office, and made use of shared facilities at the MIT Center for Materials Science.

Friday, 25 October 2013

The Best Cut for Machining


A new and verified computer model improves the machining of nanoscale semiconductor parts for the electronics industry

Brittle materials such as silicon and ceramics are used extensively in the semiconductor industry to make component parts. Materials cut to have a mirror-like surface yield the best performance, but the precision required is difficult to achieve at such a tiny scale.

Xinquan Zhang at A*STAR's Singapore Institute of Manufacturing Technology, along with co-workers at the same institute and the National University of Singapore, has developed a computer model that allows engineers to predict the best way of cutting different materials using vibration-assisted machining (VAM)1. This technique periodically interrupts the cutting process via the application of small-amplitude and high-frequency displacement to the cutting tool.

"Many researchers have observed that using VAM instead of conventional cutting techniques allows them to make cleaner, fracture-free cuts to most brittle materials," explains Zhang. "Because no theory or model exists to explain or predict this phenomenon, we decided to investigate."

At the nanoscale, brittle materials exhibit a certain degree of plasticity. Each material has a particular depth of cut that allows clean shearing to occur without chipping or fracturing on, or beneath, its surface. This point, known as the critical undeformed chip thickness, is directly correlated with material properties and machining conditions.

Zhang and his team studied the behavior of different brittle materials cut with VAM, during which two modes of cutting occur. In the ductile mode, plastic deformation caused by cutting is followed by elastic rebound and recovery of the material structure between vibrations. The brittle mode, on the other hand, removes material by uncontrolled crack propagation. Making a clean cut during ductile mode -- before the brittle mode dominates -- is therefore desirable.

The researchers modeled the energy consumption of each mode in terms of material removal as the vibrating tool moved, taking into account tool geometry, material properties and the cutting speed.

"By examining energy consumption and material deformation we were able to describe the mechanics when VAM moved from the ductile to the brittle mode," explains Zhang. "We then established a model to predict [the] critical undeformed chip thicknesses by finding the transition point between the two modes."

By examining energy consumption and material deformation we were able to describe the mechanics when VAM moved from the ductile to the brittle mode," explains Zhang. "We then established a model to predict [the] critical undeformed chip thicknesses by finding the transition point between the two modes."

Through a series of experiments, the team verified that the model accurately predicts the critical undeformed chip thicknesses of single-crystal silicon when cut at various VAM speeds.

"Our model will help engineers to select optimized machining parameters depending on their desired material," says Zhang. "Advantages could include higher productivity, lower costs, and improved product quality for semiconductor parts and other nanoscale technologies."

The A*STAR-affiliated researchers contributing to this research are from the Singapore Institute of Manufacturing Technology

Thursday, 24 October 2013

People Tend to Communicate With Similar People, Even More Than Previously Thought


The results were obtained by means of a computational method developed by the research group and then applied to massive amounts of anonymised mobile phone call data. The data came from a mobile phone operator's billing system and includes detailed information about the timing of hundreds of millions of mobile phone calls and the age, gender and billing types of anonymised callers and recipients.

The research is linked to computational social science, an area of multidisciplinary research that has become highly important in recent years. In this area, computational methods are used to mine information about human behavior from massive data sets. Rather than focusing on the individual, computational social science strives to understand general properties in the behavior of large groups of people. This contrasts with data collection and mining used for intelligence purposes, which has recently attracted a lot of publicity. Furthermore, the data used is always anonymised.

The research group's computational method is based on statistical analysis of the precise timing of phone calls. This allowed researchers to show that various patterns where phone calls immediately follow each other (for example, A calls B, who then calls C) are more common between people who are similar in terms of age, gender and mutual friends than could be observed based only on numbers of calls made.

Application of the developed method is not only limited to research on communication between people; it also has potential uses in areas like brain research.

Improving the efficiency of solar panels

Light scattering was promoted in the visible part of sunlight's spectrum

At the heart of the blooming solar power industry is the semiconductor material, like silicon or gallium arsenide, which absorbs sunlight and forms the basis of solar panels. It converts electromagnetic energy in the form of sunlight to electrical energy. Now, researchers from London have demonstrated a technique to increase the amount of electrical current produced by a solar panel simply by augmenting its light-facing surface with aluminium nanostructures.

When photons, particles of light, are absorbed by the semiconductor, they knock out electrons, which are passed through a circuit and then to a battery for storage as electricity. However, scientists now want to find ways of increasing the absorption of light in thin layers of semiconductors, so that solar panels can be made using less raw-material and at a lower cost.

Recent research from the Imperial College, London (ICL), has demonstrated one way to increase the electrical current produced by devices in the lab by 22 per cent. By studding the light-receiving surface of gallium-arsenide (Ga-As) devices with aluminium nanocylinders, like the ridges on Lego blocks, the researchers were able to promote the scattering of light in the visible part of the spectrum, which dominates the energy in sunlight.

The scattered light then travels a longer path inside the semiconductor, meaning that more photons can be absorbed and converted into current. It is important that the metal nanocylinders do not absorb the light themselves, as that would prevent it from reaching the panel.

“The advantage of aluminium structures is that their absorption occurs in the ultraviolet part of the spectrum. That means that the absorption losses are limited to the ultraviolet and scattering from the aluminium particle dominates in both the visible and near infrared,” said Dr. Nicholas Hylton, a Research Associate at the Blackett Laboratory, ICL, in an email. Dr. Hylton was lead author of the research group’s paper, published in Scientific Reports on October 18.

This isn’t the first time such nanostructures have been deployed to enhance the performance of solar panels. Earlier, silver and gold nanoparticles have been used because they improved the performance of the devices in the near-infrared part of the electromagnetic spectrum.

“We were able to demonstrate that gold and silver scatter light in the near infrared part of the spectrum but absorb visible light strongly,” Dr. Hylton wrote.

The significance of Dr.Hylton’s work lies in demonstrating aluminium’s better performance over silver and gold nanostructures. For one, aluminium is more abundant and less costly than silver and gold. For another, the 22 per cent spike that aluminium provides, as their paper notes, makes thinner-film solar panels technically feasible without “compromising power conversion efficiencies, thus reducing material consumption.”

Higher efficiency devices could play a significant role in realising energy goals even in India, making them more cost-effective. Already, according to industry trackers, the price of solar power in India has come from Rs. 18/kWh in 2011 to Rs. 7/kWh in 2013, while the price of thermal power is pushing Rs. 4/kWh with subsidies.

Wednesday, 23 October 2013

Researchers Advance Scheme to Design Seamless Integrated Circuits Etched On Graphene

Bulk materials commonly used to make CMOS transitors and interconnects pose fundamental challenges in continuous shrinking of their feature-sizes and suffer from increasing "contact resistance" between them, both of which lead to degrading performance and rising energy consumption. Graphene-based transistors and interconnects are a promising nanoscale technology that could potentially address issues of traditional silicon-based transistors and metal interconnects.

"In addition to its atomically thin and pristine surfaces, graphene has a tunable band gap, which can be adjusted by lithographic sketching of patterns -- narrow graphene ribbons can be made semiconducting while wider ribbons are metallic. Hence, contiguous graphene ribbons can be envisioned from the same starting material to design both active and passive devices in a seamless fashion and lower interface/contact resistances," explained Kaustav Banerjee, professor of electrical and computer engineering and director of the Nanoelectronics Research Lab at UCSB. Banerjee's research team also includes UCSB researchers Jiahao Kang, Deblina Sarkar and Yasin Khatami. Their work was recently published in the journal Applied Physics Letters.

"Accurate evaluation of electrical transport through the various graphene nanoribbon based devices and interconnects and across their interfaces was key to our successful circuit design and optimization," explained Jiahao Kang, a PhD student in Banerjee's group and a co-author of the study. Banerjee's group pioneered a methodology using the Non-Equilibrium Green's Function (NEGF) technique to evaluate the performance of such complex circuit schemes involving many heterojunctions. This methodology was used in designing an "all-graphene" logic circuit reported in this study.

"This work has demonstrated a solution for the serious contact resistance problem encounterd in conventional semiconductor technology by providing an innovative idea of using an all-graphene device-interconnect scheme. This will significantly simplify the IC fabrication process of graphene based nanoelectronic devices." commented Philip Kim, professor of physics at Columbia University.

As reported in their study, the proposed all-graphene circuits have achieved 1.7X higher noise margins and 1-2 decades lower static power consumption over current CMOS technology. According to Banerjee, with the ongoing worldwide efforts in patterning and doping of graphene, such circuits can be realized in the near future.

"We hope that this work will encourage and inspire other researchers to explore graphene and beyond-graphene emerging 2-dimensional crystals for designing such 'band-gap engineered' circuits in the near future," added Banerjee.

Their research was supported by the National Science Foundation.

Tuesday, 22 October 2013

Production of Non-Toxic Flame Retardants Simplified


Alarmingly, some 600 people die in household fires in Germany ever year. Often started by nothing more than a small tea light, such fires can soon take hold. Once a few objects are alight, room temperatures shoot up as high as 800 degrees Celsius, and flames quickly spread to other rooms, leaving inhabitants with precious little time to escape after a fire has broken out -- usually no more than around two minutes.

Modern-day apartments and offices contain considerably more combustible materials than they did a few decades ago. Items such as furniture, electronics and electrical equipment are predominantly made up of highly flammable materials that ignite easily, meaning such products would be ablaze in no time at all if it were not for addition of flame retardants. For instance, it only takes eight minutes for a television that has not been fire- proofed to go up in flames, whereas a TV set that has been treated with retardants remains undamaged. Prof. Dr. Manfred Döring and his team at the Fraunhofer Institute for Structural Durability and System Reliability LBF develop flame retardants for polymer materials. These are used inthe transport and construction industries, in electronics and electrical appliances, and many other applications. "Flame retardants prevent fires and slow the spread of the blaze. People are given more time to escape, sometimes up to 20 minutes, which significantly increases the chance of surviving a fire unharmed," says Döring.

Flame retardants must meet high standards

Flame retardants have to satisfy a number of challenging criteria. They must be environmentally friendly, non-hazardous to humans, animals and plants, and must not release any additional toxic fumes when they burn. These additives should not escape the finished product into the atmosphere, or when it comes into contact with water. And researchers must make sure the flame retardant does not react with the plastic or other components in unwelcome ways that might alter the material, influence its functionality or affect its appearance. "Flame resistant work clothing, for instance, has to be machine washable, but cannot lose its protective properties every time it is washed. To prevent the chance of a short circuit developing into a fire, printed circuit boards in electronic devices must remain fully functional and flame retardant over many years, at temperatures that can range from -40 to +60 degrees Celsius," says Döring. He and his team of scientists only work with halogen-free, non-toxic flame retardant additives, and tailor each substance to the particular plastic in question. Depending on the intended application for the material, they use inorganic compounds and compounds containing nitrogen and phosphorus.

One such product will be on display at the K 2013 trade fair from 16 to 23 October in Düsseldorf. Fraunhofer LBF scientists are presenting a halogen-free, polymeric flame retardant for fibers that is suitable for use in flame retardant seat covers, for instance. What is unique about their product is that the scientists introduce the polymeric flame retardant as part of the extrusion process, a technique that is commonly used in the plastics industry. A polymer that is suitable for fiber spinning is mixed with a flame retardant polymer in the extruder. This is the machine that feeds raw plastic material along a jacketed screw that heats, melts and compacts the plastic before passing it through another tool under pressure to form a continuous profile. The flame retardant is evenly mixed into the base polymer by simple mechanical action. This method gives plastics manufacturers the advantage of being able to personally control the amount of flame retardant polymer that gets added, meaning that they are able to produce flame resistant polymers according to their own formulae for the very first time.

The research team at Fraunhofer LBF is in the process of setting up a fire safety laboratory that will offer a broad range of services towards the end of 2014. Chemists and engineers will then conduct efficiency tests on flame retardants found in polymers, and develop formulae for synthetic polymers such as thermoplastics, thermosets and composites. They will examine and test the efficiency of multi-component systems, or what experts refer to as "synergetic mixtures" -- compounds that multiply the inherent properties of their individual components. The scientists can also synthesize halogen-free fire retardants and scale up the synthesis as required. The range of possible applications is vast, given the growing share of components made of plastic, all of which have to be treated with flame retardants.

Topological Light: Living On the Edge



Artistic rendering of real data and real SEM image (false colored) from experiment. The lit resonators show light racing around the edge of the silicon chip unimpeded, avoiding defects (here a missing resonator). (Credit: E. Edwards/JQI. Figure attributes (color, lighting) altered for artistic purposes with permission of authors.)

Quantum Hall physics, inherently topological, has been seen in electronic devices and in dilute atomic ensembles. In the two-dimensional electron case, current flows along an edge/interface ("edge states") even in the presence of defects or other physical distortions in the sample -- this arises from global properties of the material. This is strange when contrasted with conventional conductors/insulators, where the transport is impeded due the presence of disorder.

In this week's issue of Nature Photonics scientists at the Joint Quantum Institute report the first observation of such topological effects for light in two dimensions. To accomplish this, they built a structure to guide infrared light over the surface of a room temperature, silicon-on-insulator chip. Amazingly, they directly observed light racing around the boundary, impervious to defects. These photonic "edge states" are directly analogous to the quantum Hall effect for electrons.

Since silicon is the preferred material for most electronics this novel design assists with the miniaturization of optical communication technology, bringing photons a little closer to their electronic circuit counterparts. The work is a realization of a theoretical proposal by this same group of JQI scientists and their collaborators more than a year ago.

Edge States and Ring Resonators

Electrons can occupy topological edge states because they are charged particles whose energy spectrum can be dramatically modified by large magnetic fields. To simplify, a magnetic interaction is key for realizing quantum Hall states. The question here to ask is how researchers can design a material where photons -- massless, charge-free, packets of energy -- flow as if they are being manipulated by a super strong magnet. To put it another way, how can the energy spectrum of light be modified to support robust topological states? And what do these photonic edge states look like?

In the JQI design, the light moves through a 2D landscape consisting of nearly flat ring-shaped silicon waveguides called resonators. By comparison, the arena for electrons is typically at the two-dimensional interface between two sheets of semiconductor. What the JQI scientists showed was that indeed light can, under the right circumstances, circulate around the edge of the silicon chip, without significant loss of energy, and do so even in the presence of defects.

The array of silicon rings is designed to only let the light waves inside-- "resonate"-- if they have the right wavelength (the circumference of the ring equaling an integral number of wavelengths). In other words, if the light frequency matches the resonant conditions of the ring it will enter the waveguide and make many circuits. For an off-resonance condition less light will inhabit the ring. Light with one polarization (the light's electric field pointing up or down) will, furthermore, circulate preferentially in one direction around the ring, clockwise or anti-clockwise. For the enthusiasts, the clockwise and anti-clockwise modes, in combination with the resonator array design, allows the photonic system to be analogous to an electron (spin) interacting with a magnet. The researchers created a photonic system that experiences a so-called synthetic or effective magnetic field [[see this link on the design proposal by this same group and this link on synthetic fields in ultracold atoms]].

This breaking of the symmetry of travel around rings is what can cause the cancelling-out of light propagation through the body of the device but not around the edge. It is also what reduces the amount of light energy wasted when light scatters or moves backwards around the edge or meets with a defect such as a defective resonator ring. Thus the JQI device displays the hallmark of topological behavior: persistent flow in the form of an edge state and near immunity against defects. The scientists went out of their way to deliberately turn off some resonators, thus simulating the industrial conditions of mass production -- a process prone to the presence of faulty components even in the best of fabrication circumstances. They also demonstrated the edge flow in the presence of unpredicted defects in the device.

In all of those resonator-to-resonator transfers, at least a little bit of the light gets lost, and this wasted energy is what the researchers use to image the light paths through the device. When the resonator array is tuned with the right frequency and temperature for general (non-topological) transmission, that's what you get: light moves through the whole of the array. However, when the system is tuned to facilitate edge states, sure enough, no light moves through the body of the array; it only skirts the edge of the array -- in a direct analogy to electron movement in a quantum Hall state. Notably, this scheme is a realization of the quantum spin Hall effect, where photonic (pseudo-)spins take the place of electron charge.

Possible Applications

"By tuning the resonators with temperature, we can make this topological array quite flexible," says Jacob Taylor, one of the JQI researchers. "The array isn't designed for one frequency only." Furthermore, the architecture of the array, which can be expanded to suite the need, fits in with the expectation that components such as this will need to be scaled up for use in future quantum computers, especially those that use photons as parts of hybrid electron-photon-atom systems.

JQI scientist and lead author, Mohammad Hafezi explains why edge states for photons might have an advantage over electron edge states for certain applications: "Photonic systems are remarkably malleable since photons can be easily guided inside the waveguides. Therefore, one can think of making photonic systems with non-trivial topologies, like Mobius strip, tori etc."

What can be done with a photonic array like this? One immediate advantage of edge states is that the arrays can be used for producing delays in photonic chips, where it is desirable to slow down a signal without being sensitive to fabrication errors. Other future uses: as filters and optical switches. Furthermore, by concentrating light in only two dimensions rather than three, the JQI scientists believe they can achieve certain nonlinear quantum effects, which can only occur with intense light.

Sunday, 20 October 2013

Gravitational Waves Help Us Understand Black-Hole Weight Gain

A paper in today's issue of Science pits the front-running ideas about the growth of supermassive black holes against observational data -- a limit on the strength of gravitational waves, obtained with CSIRO's Parkes radio telescope in eastern Australia.

"This is the first time we've been able to use information about gravitational waves to study another aspect of the Universe -- the growth of massive black holes," co-author Dr Ramesh Bhat from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR) said.

"Black holes are almost impossible to observe directly, but armed with this powerful new tool we're in for some exciting times in astronomy. One model for how black holes grow has already been discounted, and now we're going to start looking at the others."

The study was jointly led by Dr Ryan Shannon, a Postdoctoral Fellow with CSIRO, and Mr Vikram Ravi, a PhD student co-supervised by the University of Melbourne and CSIRO.

Einstein predicted gravitational waves -- ripples in space-time, generated by massive bodies changing speed or direction, bodies like pairs of black holes orbiting each other.

When galaxies merge, their central black holes are doomed to meet. They first waltz together then enter a desperate embrace and merge.

"When the black holes get close to meeting they emit gravitational waves at just the frequency that we should be able to detect," Dr Bhat said.

Played out again and again across the Universe, such encounters create a background of gravitational waves, like the noise from a restless crowd.

Astronomers have been searching for gravitational waves with the Parkes radio telescope and a set of 20 small, spinning stars called pulsars.

Pulsars act as extremely precise clocks in space. The arrival time of their pulses on Earth are measured with exquisite precision, to within a tenth of a microsecond.

When the waves roll through an area of space-time, they temporarily swell or shrink the distances between objects in that region, altering the arrival time of the pulses on Earth.

The Parkes Pulsar Timing Array (PPTA), and an earlier collaboration between CSIRO and Swinburne University, together provide nearly 20 years worth of timing data. This isn't long enough to detect gravitational waves outright, but the team say they're now in the right ballpark.

"The PPTA results are showing us how low the background rate of gravitational waves is," said Dr Bhat.

"The strength of the gravitational wave background depends on how often supermassive black holes spiral together and merge, how massive they are, and how far away they are. So if the background is low, that puts a limit on one or more of those factors."

Armed with the PPTA data, the researchers tested four models of black-hole growth. They effectively ruled out black holes gaining mass only through mergers, but the other three models are still a possibility.

Dr Bhat also said the Curtin University-led Murchison Widefield Array (MWA) radio telescope will be used to support the PPTA project in the future.

"The MWA's large view of the sky can be exploited to observe many pulsars at once, adding valuable data to the PPTA project as well as collecting interesting information on pulsars and their properties," Dr Bhat said.

Wednesday, 16 October 2013

Method of Recording Brain Activity Could Lead to Mind-Reading Devices, Stanford Scientists Say


Using a novel method, the researchers collected the first solid evidence that the pattern of brain activity seen in someone performing a mathematical exercise under experimentally controlled conditions is very similar to that observed when the person engages in quantitative thought in the course of daily life.

"We're now able to eavesdrop on the brain in real life," said Josef Parvizi, MD, PhD, associate professor of neurology and neurological sciences and director of Stanford's Human Intracranial Cognitive Electrophysiology Program. Parvizi is the senior author of the study, published Oct. 15 in Nature Communications. The study's lead authors are postdoctoral scholar Mohammad Dastjerdi, MD, PhD, and graduate student Muge Ozker.

The finding could lead to "mind-reading" applications that, for example, would allow a patient who is rendered mute by a stroke to communicate via passive thinking. Conceivably, it could also lead to more dystopian outcomes: chip implants that spy on or even control people's thoughts.

"This is exciting, and a little scary," said Henry Greely, JD, the Deane F. and Kate Edelman Johnson Professor of Law and steering committee chair of the Stanford Center for Biomedical Ethics, who played no role in the study but is familiar with its contents and described himself as "very impressed" by the findings. "It demonstrates, first, that we can see when someone's dealing with numbers and, second, that we may conceivably someday be able to manipulate the brain to affect how someone deals with numbers."

The researchers monitored electrical activity in a region of the brain called the intraparietal sulcus, known to be important in attention and eye and hand motion. Previous studies have hinted that some nerve-cell clusters in this area are also involved in numerosity, the mathematical equivalent of literacy.

However, the techniques that previous studies have used, such as functional magnetic resonance imaging, are limited in their ability to study brain activity in real-life settings and to pinpoint the precise timing of nerve cells' firing patterns. These studies have focused on testing just one specific function in one specific brain region, and have tried to eliminate or otherwise account for every possible confounding factor. In addition, the experimental subjects would have to lie more or less motionless inside a dark, tubular chamber whose silence would be punctuated by constant, loud, mechanical, banging noises while images flashed on a computer screen.

"This is not real life," said Parvizi. "You're not in your room, having a cup of tea and experiencing life's events spontaneously." A profoundly important question, he said, is: "How does a population of nerve cells that has been shown experimentally to be important in a particular function work in real life?"

His team's method, called intracranial recording, provided exquisite anatomical and temporal precision and allowed the scientists to monitor brain activity when people were immersed in real-life situations. Parvizi and his associates tapped into the brains of three volunteers who were being evaluated for possible surgical treatment of their recurring, drug-resistant epileptic seizures.

The procedure involves temporarily removing a portion of a patient's skull and positioning packets of electrodes against the exposed brain surface. For up to a week, patients remain hooked up to the monitoring apparatus while the electrodes pick up electrical activity within the brain. This monitoring continues uninterrupted for patients' entire hospital stay, capturing their inevitable repeated seizures and enabling neurologists to determine the exact spot in each patient's brain where the seizures are originating.

During this whole time, patients remain tethered to the monitoring apparatus and mostly confined to their beds. But otherwise, except for the typical intrusions of a hospital setting, they are comfortable, free of pain and free to eat, drink, think, talk to friends and family in person or on the phone, or watch videos.

The electrodes implanted in patients' heads are like wiretaps, each eavesdropping on a population of several hundred thousand nerve cells and reporting back to a computer.

In the study, participants' actions were also monitored by video cameras throughout their stay. This allowed the researchers later to correlate patients' voluntary activities in a real-life setting with nerve-cell behavior in the monitored brain region.

As part of the study, volunteers answered true/false questions that popped up on a laptop screen, one after another. Some questions required calculation -- for instance, is it true or false that 2+4=5? -- while others demanded what scientists call episodic memory -- true or false: I had coffee at breakfast this morning. In other instances, patients were simply asked to stare at the crosshairs at the center of an otherwise blank screen to capture the brain's so-called "resting state."

Consistent with other studies, Parvizi's team found that electrical activity in a particular group of nerve cells in the intraparietal sulcus spiked when, and only when, volunteers were performing calculations.

Afterward, Parvizi and his colleagues analyzed each volunteer's daily electrode record, identified many spikes in intraparietal-sulcus activity that occurred outside experimental settings, and turned to the recorded video footage to see exactly what the volunteer had been doing when such spikes occurred.

They found that when a patient mentioned a number -- or even a quantitative reference, such as "some more," "many" or "bigger than the other one" -- there was a spike of electrical activity in the same nerve-cell population of the intraparietal sulcus that was activated when the patient was doing calculations under experimental conditions.

That was an unexpected finding. "We found that this region is activated not only when reading numbers or thinking about them, but also when patients were referring more obliquely to quantities," said Parvizi.

"These nerve cells are not firing chaotically," he said. "They're very specialized, active only when the subject starts thinking about numbers. When the subject is reminiscing, laughing or talking, they're not activated." Thus, it was possible to know, simply by consulting the electronic record of participants' brain activity, whether they were engaged in quantitative thought during nonexperimental conditions.

Any fears of impending mind control are, at a minimum, premature, said Greely. "Practically speaking, it's not the simplest thing in the world to go around implanting electrodes in people's brains. It will not be done tomorrow, or easily, or surreptitiously."

Parvizi agreed. "We're still in early days with this," he said. "If this is a baseball game, we're not even in the first inning. We just got a ticket to enter the stadium."

The study was funded by the National Institutes of Health (grant R01NS0783961), the Stanford NeuroVentures Program, and the Gwen and Gordon Bell Family. Additional co-authors were postdoctoral scholar Brett Foster, PhD, and research assistant Vinitha Rangarajan.

An Optical Switch Based On a Single Nano-Diamond


The scientific results of this study have been published in Nature Physics.

Electronic transistors have become a key component to modern electronics, drastically improving the speed of information processing of current technologies. An electronic transistor is a semiconductor device used to amplify and switch electronic signals. The much sought after optical transistor (the photonic counterpart of the electronic transistor) is poised to become a central ingredient in the development of optical signal processing. The motivation for using photons rather than electrons not only comes from their faster dynamics but also from their weaker interaction with the environment, which enable a high degree of integration and the realization of quantum operations.

Prior studies have demonstrated that single dye molecules can be operated as optical transistors with the disadvantage that they worked exclusively at extremely low temperatures. Such restrictions on the temperature made these optical transistors cumbersome for application to quantum computing.

However in this recent ICFO study, scientists have shown that a nano-size diamond at room temperature can act as an efficient optical switch controllable with light. A Nano-diamond containing a nitrogen impurity behaves like an artificial atom although much more stable at room temperature than a real atom due to its encapsulation. The ICFO scientists discovered a novel physical mechanism that enables the control of the way the nano-diamond interacts with light. While excited to its ON state by a green laser, a suitable near infrared illumination was found to act as an efficient and fast way to switch it OFF. Based on this simple concept, they were able to modulate the optical nano-diamond ON and OFF at extremely high speeds, demonstrating its robustness and viability for very fast information processing and quantum computer operations.

Quidant remarks that "what is really attractive about our discovery is that our nano-switch combines very small dimensions (compatible with integrating a large number of them in a small area) with very fast response time (meaning lots of operations in a short time) and operation at room temperature."

This new technique will contribute to the development of future integrated optical circuits as well as quantum information processing for quantum computing.

This work is a collaborative effort between the research groups at ICFO led by ICREA Professors at ICFO Javier García de Abajo and Romain Quidant.

World Record: Wireless Data Transmission at 100 Gbit/S

In their record experiment, 100 gigabits of data per second were transmitted at a frequency of 237.5 GHz over a distance of 20 m in the laboratory. In previous field experiments under the "Millilink" project funded by the BMBF, rates of 40 gigabits per second and transmission distances of more than 1 km were reached. For their latest world record, the scientists applied a photonic method to generate the radio signals at the transmitter. After radio transmission, fully integrated electronic circuits were used in the receiver.

"Our project focused on integration of a broadband radio relay link into fiber-optical systems," Professor Ingmar Kallfass says. He coordinated the "Millilink" project under a shared professorship funded by the Fraunhofer Institute for Applied Solid State Physics (IAF) and the Karlsruhe Institute of Technology (KIT). Since early 2013, he has been conducting research at Stuttgart University. "For rural areas in particular, this technology represents an inexpensive and flexible alternative to optical fiber networks, whose extension can often not be justified from an economic point of view." Kallfass also sees applications for private homes: "At a data rate of 100 gigabits per second, it would be possible to transmit the contents of a blue-ray disk or of five DVDs between two devices by radio within two seconds only."

In the experiments, latest photonic and electronic technologies were combined: First, the radio signals are generated by means of an optical method. Several bits are combined by so-called data symbols and transmitted at the same time. Upon transmission, the radio signals are received by active integrated electronic circuits.

The transmitter generates the radio signals by means of an ultra-broadband so-called photon mixer made by the Japanese company NTT-NEL. For this, two optical laser signals of different frequencies are superimposed on a photodiode. An electrical signal results, the frequency of which equals the frequency difference of both optical signals, here, 237.5 GHz. The millimeter-wave electrical signal is then radiated via an antenna.

"It is a major advantage of the photonic method that data streams from fiber-optical systems can directly be converted into high-frequency radio signals," Professor Jürg Leuthold says. He proposed the photonic extension that was realized in this project. The former head of the KIT Institute of Photonics and Quantum Electronics (IPQ) is now affiliated with ETH Zurich. "This advantage makes the integration of radio relay links of high bit rates into optical fiber networks easier and more flexible." In contrast to a purely electronic transmitter, no intermediate electronic circuit is needed. "Due to the large bandwidth and the good linearity of the photon mixer, the method is excellently suited for transmission of advanced modulation formats with multiple amplitude and phase states. This will be a necessity in future fiber-optical systems," Leuthold adds.

Reception of radio signals is based on electronic circuits. In the experiment, a semiconductor chip was employed that was produced by the Fraunhofer Institute of Applied Solid State Physics (IAF) within the framework of the "Millilink" project. The semiconductor technology is based on high-electron-mobility transistors (HEMT) enabling the fabrication of active, broadband receivers for the frequency range between 200 and 280 GHz. The integrated circuits have a chip size of a few square millimeters only. The receiver chip can also cope with advanced modulation formats. As a result, the radio link can be integrated into modern optical fiber networks in a bit-transparent way.

Already in May this year the team succeeded in transmitting a data rate of 40 gigabits per second over a long distance in the laboratory using a purely electronic system. In addition, data were transmitted successfully over a distance of one kilometer from one high-riser to another in the Karlsruhe City center. "The long transmission distances in "Millilink" were reached with conventional antennas that may be replaced by fully integrated miniaturized antenna designs in future compact systems for indoor use," says Professor Thomas Zwick, Head of the KIT Institut für Hochfrequenztechnik und Elektronik (Institute of High-Frequency Technology and Electronics). The present data rate can be still increased. "By employing optical and electrical multiplexing techniques, i.e., by simultaneously transmitting multiple data streams, and by using multiple transmitting and receiving antennas, the data rate could be multiplied," says Swen König from the KIT Institute of Photonics and Quantum Electronics (IPQ), who conceived and conducted the recent world-record experiment. "Hence, radio systems having a data rate of 1 terabit per second appear to be feasible."

Friday, 11 October 2013

Superlative Supercapacitors - A Moonshot Idea

Batteries have a bad reputation. They're made of toxic materials and charge very slowly. Richard Kaner talks about his solution in The Super Supercapacitor, a SolveForX talk created as part of the GE Focus Forward series.

In general batteries have high energy storage but take a long time to charge and discharge. A capacitor can charge and discharge quickly but have very low energy storage capabilities. Kaner is expecting his new graphene supercapacitors to store high amounts of energy and charge at least one hundred times faster than a battery.



http://www.kurzweilai.net/graphene-micro-supercapacitors-to-replace-batteries-for-microelectonics-devices

Kaner was researching graphene in his lab. Graphene is a strong flexible carbon-based material but production methods were not efficient. Kaner and his research assistant Maher El-Kady developed a new process using sheets of plastic and curing through dvds and a personal computer disc drive.

Serendipity came when Maher found that graphene could act as a supercapacitor. With a specimen of graphene and two leads he charged a light in a few seconds and kept the light running for five minutes.

The possibilities here are wide open. Immediately charging our electronic devices will bring convenience to most of us, but further down the line energy storage and transmission could be changed to meet future energy needs. Charging an electric vehicle could take minutes, and when exhausted graphene can be recycled back into its carbon components much easier than battery materials.



http://dailybruin.com/2013/02/28/professor-and-graduate-student-develop-battery-like-product/


Thursday, 10 October 2013

New technique lets you feel textures on touchscreen:

Smartphone users can now ‘feel’ images and objects seen on their touchscreen!

In a game-changing invention, engineers at Disney Research, Pittsburgh, have developed a new technique that allows you to feel the texture of objects seen on a flat touchscreen.

The novel algorithm enables a person sliding a finger across a topographic map displayed on a touchscreen to feel the bumps and curves of hills and valleys, despite the screen’s smooth surface.

The technique is based on the fact that when a person slides a finger over a real physical bump, he perceives the bump largely because lateral friction forces stretch and compress skin on the sliding finger.

By altering the friction encountered as a person’s fingertip glides across a surface, the Disney algorithm can create a perception of a 3D bump on a touch surface.

The method can be used to simulate the feel of a wide variety of objects and textures.

“Our brain perceives the 3D bump on a surface mostly from information that it receives via skin stretching,” said Ivan Poupyrev, who directs Disney Research, Pittsburgh’s Interaction Group.

“Therefore, if we can artificially stretch skin on a finger as it slides on the touchscreen, the brain will be fooled into thinking an actual physical bump is on a touchscreen even though the touch surface is completely smooth,” Poupyrev said in a statement.

In experiments, researchers used electrovibration to modulate the friction between the sliding finger and the touch surface with electrostatic forces.

Researchers created and validated a psychophysical model that closely simulates friction forces perceived by the human finger when it slides over a real bump.

The model was then incorporated into an algorithm that dynamically modulates the frictional forces on a sliding finger so that they match the tactile properties of the visual content displayed on the touchscreen along the finger’s path.

A broad variety of visual artifacts thus can be dynamically enhanced with tactile feedback that adjusts as the visual display.

“The traditional approach to tactile feedback is to have a library of canned effects that are played back whenever a particular interaction occurs,” said Ali Israr, a Disney Research, Pittsburgh research engineer who was the lead on the project.

“This makes it difficult to create a tactile feedback for dynamic visual content, where the sizes and orientation of features constantly change. With our algorithm we do not have one or two effects, but a set of controls that make it possible to tune tactile effects to a specific visual artifact on the fly,” Israr said.

The new research will be presented at the ACM Symposium on User Interface Software and Technology in St Andrews, Scotland.

Wednesday, 9 October 2013

Continuous Monitoring Contact Lenses:


Current medical science only gives us body scans at one point in time. Babak Parviz discusses his solution to this problem in his SolveForX talk, Continuous Body Monitoring.

Today’s data collection devices, if not in physical contact with the body, are not sending out information. There are possibilities for implanting but our bodies generally react poorly to foreign objects. Parviz’s targeted interface on the human body is the surface of the eye.

Tears exist with much of the same chemical makeup as blood, so contact lenses are a solution to show what is going on inside a patient’s body without actually going inside the body. Contact lenses are used by more than one hundred million people and have existed for decades, giving users a comfortable method of existing with a continuous sensor.

As a receiver the lens could act as a display for the user, with cell phone towers beaming information to a unit in the user’s pocket. An augmented reality application is the most feasible use for a lens receiver. Long term Babak says that screens exist to bring information to the retina, and many screens could be consolidated into one display per human being.

The semiconductor industry is constantly churning out smaller sensors allowing the lenses to collect and disperse information. Some sensors are down to 50 nanometers, approaching the size of a single cell in the body. Using miniaturization technology along with flexible sensor technology Babak is developing the contact lens sensors.

Lenses are being tested now with miniature glucose sensors, antenna and readout circuits. The system can be powered remotely with RF broadcast to wake up, take the measurement and send the data before powering back down. Very small devices consume very small amounts of power, and the entire system can be run with 3 microWatts.

video:http://www.youtube.com/embed/d6g581tJ7bM

Printed Electronics: A Multi-Touch Sensor Customizable With Scissors

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

— If a pair of long pants is too long, it is cut to length. A board that does not fit into a bookcase is sawed to the right length. People often customize the size and shape of materials like textiles and wood without turning to specialists like tailors or carpenters. In the future this should be possible with electronics, according to the vision of computer scientists from Saarbrücken. Together with researchers from the MIT Media Lab, they developed a printable multi-touch sensor whose shape and size everybody can alter. A new circuit layout makes it robust against cuts, damage, and removed areas.

Today the researchers are presenting their work at the conference "User Interface and Technology" (UIST) in St. Andrews, Scotland.

"Imagine a kid takes our sensor film and cuts out a flower with stem and leaves. If you touch the blossom with a finger, you hear the buzzing of a bumblebee," Jürgen Steimle says. He reports that programs and apps are easily imaginable to help parents connect touching a sensor film with the suitable sound effect. Steimle, 33, has a doctoral degree in computer science and is doing research at the Max-Planck Institute for Informatics. He also heads the Embodied Interaction research group at the Cluster of Excellence on Multimodal Computing and Interaction.

Simon Olberding is the doctoral candidate and the lead developer of the new sensor. He sees a further application of the new technology in so-called interactive walls used for discussions and brainstorming. "So far, such a wall frays and scuffs quickly as we hammer nails into it, stick notes or posters on it, and damage it while removing them. By customizing and pasting on our new sensor you can make every surface interactive no matter if it is the wristband of a watch, a cloth on a trade fair table, or wallpaper," Olberding says.

As basic technology the scientists use so-called "printed electronics." This term summarizes electrical components and devices which are printed. The approach is similar to that of inkjet printers. Instead of printing with normal ink, electrically-functional electronic ink is printed on flexible, thin films (so-called substrates). "The factory costs are so low that printing our DIN A4 film on our special printer in the lab costs us about one US dollar," Steimle says.

But you need more than printed electronics to make a sensor robust against cuts, damage, and removed areas. So far the circuit layout of a multi-touch sensor has been similar to graph paper. The wires run horizontally, vertically, and parallel to each other. At the intersection of one parallel and one horizontal layer you find the touch-sensitive electrodes. Via the wires they are connected to a controller. This type of layout requires only a minimal number of wires, but is not robust. Since each wire addresses several electrodes, a small cut has a huge effect: many electrodes become unusable and possibly large sensor areas do not work anymore. "It was not easy to find an alternative layout, robust enough for our approach," Olberding says. They took their inspiration from nature, looking at the human nerve system and fungal root networks, and thus came up with two basic layouts. The so-called star topology has the controller in the center. It is connected to every electrode separately. The so-called tree topology also has the controller in its center connected to each electrode separately. But the wires are bundled similarly to a tree structure. They all run through a vertical line in the middle and then branch off to reach their electrodes.

The scientists found out that the star topology supports often-used basic forms like triangles, rectangles, or ovals best. Furthermore, it is suitable for shapes commonly used for crafts, like stars, clouds, or hearts. In contrast, with the tree topology it is possible to cut out whole areas. The researchers were also able to combine both layouts in a space-saving way, so that the sensor supports all basic forms.

"We assume that printed sensors will be so inexpensive that multi-touch sensing capability will become an inherent part of the material. Users can take it to create interactive applications or just to write on it," Steimle explains. This vision is not so far away, as a prediction from the "Organic and Printed Electronic Association" shows. The international industry association forecast that flexible consumer electronics will be available for end-users between the years 2017 and 2020.

Tuesday, 8 October 2013

Higgs, Englert get Physics Nobel for God particle research

The Nobel Prize for physics in 2013 has been awarded to Peter Higgs and Francois Englert, a Briton and a Belgian, "for the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles, and which recently was confirmed through the discovery of the predicted fundamental particle, by the ATLAS and CMS experiments at CERN's Large Hadron Collider".

Almost 50 years ago in 1964, Englert and Robert Brout, who died in 2011, and Peter Higgs independently published their work in the span of a few days. They had described a mechanism making use of what was known about particle physics at that time to try to answer a perplexing problem: How do particles acquire mass?

Higgs and Englert hypothesised a quantum field, which is a distribution of some energy, throughout the universe. When the field is disturbed, waves travel through it. The dimmest possible wave is called a particle. In this field, since called a Higgs field, the associated particle is called the Higgs boson.

For physicists, finding the Higgs boson meant that the Higgs field exists. And because of the Higgs field and its properties, any fundamental particles that wade through it cause Higgs bosons to clump around the particles. This clumping causes the particle to acquire energy and, therefore, mass.

The existence of the Higgs boson was confirmed at the Large Hadron Collider, near Geneva, Switzerland, over the last year. On July 4, 2012, first hints of the boson's existence were spotted at the collider. Ever since, a series of tests on the particle have yielded confirmation, establishing Higgs's and Englert's work as a cornerstone of modern particle physics.

Through an Edinburgh University statement, where Higgs is an emeritus professor, he said he was overwhelmed to receive the award and congratulated "all those who have contributed to the discovery of this new particle and to thank my family, friends and colleagues for their support. I hope this recognition of fundamental science will help raise awareness of the value of blue-sky research."

Sunday, 6 October 2013

First Cloud Map of a Planet Beyond Our Solar System:

The planet is marked by high clouds in the west and clear skies in the east. Previous studies from Spitzer have resulted in temperature maps of planets orbiting other stars, but this is the first look at cloud structures on a distant world.

"By observing this planet with Spitzer and Kepler for more than three years, we were able to produce a very low-resolution 'map' of this giant, gaseous planet," said Brice-Olivier Demory of Massachusetts Institute of Technology in Cambridge. Demory is lead author of a paper accepted for publication in the Astrophysical Journal Letters. "We wouldn't expect to see oceans or continents on this type of world, but we detected a clear, reflective signature that we interpreted as clouds."

Kepler has discovered more than 150 exoplanets, which are planets outside our solar system, and Kepler-7b was one of the first. The telescope's problematic reaction wheels prevent it from hunting planets any more, but astronomers continue to pore over almost four years' worth of collected data.

Kepler's visible-light observations of Kepler-7b's moon-like phases led to a rough map of the planet that showed a bright spot on its western hemisphere. But these data were not enough on their own to decipher whether the bright spot was coming from clouds or heat. The Spitzer Space Telescope played a crucial role in answering this question.

Like Kepler, Spitzer can fix its gaze at a star system as a planet orbits around the star, gathering clues about the planet's atmosphere. Spitzer's ability to detect infrared light means it was able to measure Kepler-7b's temperature, estimating it to be between 1,500 and 1,800 degrees Fahrenheit (1,100 and 1,300 Kelvin). This is relatively cool for a planet that orbits so close to its star -- within 0.06 astronomical units (one astronomical unit is the distance from Earth and the sun) -- and, according to astronomers, too cool to be the source of light Kepler observed. Instead, they determined, light from the planet's star is bouncing off cloud tops located on the west side of the planet.

"Kepler-7b reflects much more light than most giant planets we've found, which we attribute to clouds in the upper atmosphere," said Thomas Barclay, Kepler scientist at NASA's Ames Research Center in Moffett Field, Calif. "Unlike those on Earth, the cloud patterns on this planet do not seem to change much over time -- it has a remarkably stable climate."

The findings are an early step toward using similar techniques to study the atmospheres of planets more like Earth in composition and size.

"With Spitzer and Kepler together, we have a multi-wavelength tool for getting a good look at planets that are trillions of miles away," said Paul Hertz, director of NASA's Astrophysics Division in Washington. "We're at a point now in exoplanet science where we are moving beyond just detecting exoplanets, and into the exciting science of understanding them."

Kepler identified planets by watching for dips in starlight that occur as the planets transit, or pass in front of their stars, blocking the light. This technique and other observations of Kepler-7b previously revealed that it is one of the puffiest planets known: if it could somehow be placed in a tub of water, it would float. The planet was also found to whip around its star in just less than five days.

Explore all 900-plus exoplanet discoveries with NASA's "Eyes on Exoplanets," a fully rendered 3D visualization tool, available for download at http://eyes.nasa.gov/exoplanets. The program is updated daily with the latest findings from NASA's Kepler mission and ground-based observatories around the world as they search for planets like our own.

Other authors include: Julien de Wit, Nikole Lewis, Andras Zsom and Sara Seager of Massachusetts Institute of Technology; Jonathan Fortney of the University of California, Santa Cruz; Heather Knutson and Jean-Michel Desert of the California Institute of Technology, Pasadena; Kevin Heng of the University of Bern, Switzerland; Nikku Madhusudhan of Yale University, New Haven, Conn.; Michael Gillon of the University of Liège, Belgium; Vivien Parmentier of the French National Center for Scientific Research, France; and Nicolas Cowan of Northwestern University, Evanston, Ill. Lewis is also a NASA Sagan Fellow.

The technical paper is online at http://www.mit.edu/~demory/preprints/kepler-7b_clouds.pdf .

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA. Science operations are conducted at the Spitzer Science Center at Caltech. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA. For more information about Spitzer, visit: http://spitzer.caltech.edu and http://www.nasa.gov/spitzer .

Ames is responsible for Kepler's ground system development, mission operations and science data analysis. JPL managed Kepler mission development. Ball Aerospace & Technologies Corp. in Boulder, Colo., developed the Kepler flight system and supports mission operations with the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder. The Space Telescope Science Institute in Baltimore archives, hosts and distributes Kepler science data. Kepler is NASA's 10th Discovery Mission and was funded by the agency's Science Mission Directorate. For more information about the Kepler mission, visit: http://www.nasa.gov/kepler and http://www.kepler.nasa.gov .

Well-Connected Hemispheres of Einstein's Brain May Have Sparked His Brilliance

— The left and right hemispheres of Albert Einstein's brain were unusually well connected to each other and may have contributed to his brilliance, according to a new study conducted in part by Florida State University evolutionary anthropologist Dean Falk.

"This study, more than any other to date, really gets at the 'inside' of Einstein's brain," Falk said. "It provides new information that helps make sense of what is known about the surface of Einstein's brain."

The study, "The Corpus Callosum of Albert Einstein's Brain: Another Clue to His High Intelligence," was published in the journal Brain. Lead author Weiwei Men of East China Normal University's Department of Physics developed a new technique to conduct the study, which is the first to detail Einstein's corpus callosum, the brain's largest bundle of fibers that connects the two cerebral hemispheres and facilitates interhemispheric communication.

"This technique should be of interest to other researchers who study the brain's all-important internal connectivity," Falk said.

Men's technique measures and color-codes the varying thicknesses of subdivisions of the corpus callosum along its length, where nerves cross from one side of the brain to the other. These thicknesses indicate the number of nerves that cross and therefore how "connected" the two sides of the brain are in particular regions, which facilitate different functions depending on where the fibers cross along the length. For example, movement of the hands is represented toward the front and mental arithmetic along the back.

In particular, this new technique permitted registration and comparison of Einstein's measurements with those of two samples -- one of 15 elderly men and one of 52 men Einstein's age in 1905. During his so-called "miracle year" at 26 years old, Einstein published four articles that contributed substantially to the foundation of modern physics and changed the world's views about space, time, mass and energy.

The research team's findings show that Einstein had more extensive connections between certain parts of his cerebral hemispheres compared to both younger and older control groups.

The research of Einstein's corpus callosum was initiated by Men, who requested the high-resolution photographs that Falk and other researchers published in 2012 of the inside surfaces of the two halves of Einstein's brain. In addition to Men, the current research team included Falk, who served as second author; Tao Sun of the Washington University School of Medicine; and, from East China Normal University's Department of Physics, Weibo Chen, Jianqi Li, Dazhi Yin, Lili Zang and Mingxia Fan.

Saturday, 5 October 2013

Wireless Devices Go Battery-Free With New Communication Technique

University of Washington engineers have created a new wireless communication system that allows devices to interact with each other without relying on batteries or wires for power.

The new communication technique, which the researchers call "ambient backscatter," takes advantage of the TV and cellular transmissions that already surround us around the clock. Two devices communicate with each other by reflecting the existing signals to exchange information. The researchers built small, battery-free devices with antennas that can detect, harness and reflect a TV signal, which then is picked up by other similar devices.

The technology could enable a network of devices and sensors to communicate with no power source or human attention needed.
"We can repurpose wireless signals that are already around us into both a source of power and a communication medium," said lead researcher Shyam Gollakota, a UW assistant professor of computer science and engineering. "It's hopefully going to have applications in a number of areas including wearable computing, smart homes and self-sustaining sensor networks."

The researchers published their results at the Association for Computing Machinery's Special Interest Group on Data Communication 2013 conference in Hong Kong, which begins Aug. 13. They have received the conference's best-paper award for their research.

"Our devices form a network out of thin air," said co-author Joshua Smith, a UW associate professor of computer science and engineering and of electrical engineering. "You can reflect these signals slightly to create a Morse code of communication between battery-free devices."

Smart sensors could be built and placed permanently inside nearly any structure, then set to communicate with each other. For example, sensors placed in a bridge could monitor the health of the concrete and steel, then send an alert if one of the sensors picks up a hairline crack. The technology can also be used for communication -- text messages and emails, for example -- in wearable devices, without requiring battery consumption.

The researchers tested the ambient backscatter technique with credit card-sized prototype devices placed within several feet of each other. For each device the researchers built antennas into ordinary circuit boards that flash an LED light when receiving a communication signal from another device.
Groups of the devices were tested in a variety of settings in the Seattle area, including inside an apartment building, on a street corner and on the top level of a parking garage. These locations ranged from less than half a mile away from a TV tower to about 6.5 miles away.

They found that the devices were able to communicate with each other, even the ones farthest from a TV tower. The receiving devices picked up a signal from their transmitting counterparts at a rate of 1 kilobit per second when up to 2.5 feet apart outdoors and 1.5 feet apart indoors. This is enough to send information such as a sensor reading, text messages and contact information.

It's also feasible to build this technology into devices that do rely on batteries, such as smartphones. It could be configured so that when the battery dies, the phone could still send text messages by leveraging power from an ambient TV signal.
The applications are endless, the researchers say, and they plan to continue advancing the capacity and range of the ambient backscatter communication network.

The other researchers involved are David Wetherall, a UW professor of computer science and engineering, Vincent Liu, a doctoral student in computer science and engineering, and Aaron Parks and Vamsi Talla, both doctoral students in electrical engineering.

The research was funded by the University of Washington through a Google Faculty Research Award and by the National Science Foundation's Research Center for Sensorimotor Neural Engineering at the UW.

Friday, 4 October 2013

Breakthrough in Photonics Could Allow for Faster and Faster Electronics

The research team, led by CU-Boulder researcher Milos Popovic, an assistant professor of electrical, computer and energy engineering, developed a new technique that allows microprocessors to use light, instead of electrical wires, to communicate with transistors on a single chip, a system that could lead to extremely energy-efficient computing and a continued skyrocketing of computing speed into the future.
Popovic and his colleagues created two different optical modulators -- structures that detect electrical signals and translate them into optical waves -- that can be fabricated within the same processes already used in industry to create today's state-of-the-art electronic microprocessors. The modulators are described in a recent issue of the journal Optics Letters.
First laid out in 1965, Moore's Law predicted that the size of the transistors used in microprocessors could be shrunk by half about every two years for the same production cost, allowing twice as many transistors to be placed on the same-sized silicon chip. The net effect would be a doubling of computing speed every couple of years.
The projection has held true until relatively recently. While transistors continue to get smaller, halving their size today no longer leads to a doubling of computing speed. That's because the limiting factor in microelectronics is now the power that's needed to keep the microprocessors running. The vast amount of electricity required to flip on and off tiny, densely packed transistors causes excessive heat buildup.
"The transistors will keep shrinking and they'll be able to continue giving you more and more computing performance," Popovic said. "But in order to be able to actually take advantage of that you need to enable energy-efficient communication links."
Microelectronics also are limited by the fact that placing electrical wires that carry data too closely together can result in "cross talk" between the wires.
In the last half-dozen years, microprocessor manufacturers, such as Intel, have been able to continue increasing computing speed by packing more than one microprocessor into a single chip to create multiple "cores." But that technique is limited by the amount of communication that then becomes necessary between the microprocessors, which also requires hefty electricity consumption.
Using light waves instead of electrical wires for microprocessor communication functions could eliminate the limitations now faced by conventional microprocessors and extend Moore's Law into the future, Popovic said.
Optical communication circuits, known as photonics, have two main advantages over communication that relies on conventional wires: Using light has the potential to be brutally energy efficient, and a single fiber-optic strand can carry a thousand different wavelengths of light at the same time, allowing for multiple communications to be carried simultaneously in a small space and eliminating cross talk.
Optical communication is already the foundation of the Internet and the majority of phone lines. But to make optical communication an economically viable option for microprocessors, the photonics technology has to be fabricated in the same foundries that are being used to create the microprocessors. Photonics have to be integrated side-by-side with the electronics in order to get buy-in from the microprocessor industry, Popovic said.
"In order to convince the semiconductor industry to incorporate photonics into microelectronics you need to make it so that the billions of dollars of existing infrastructure does not need to be wiped out and redone," Popovic said.
Last year, Popovic collaborated with scientists at MIT to show, for the first time, that such integration is possible. "We are building photonics inside the exact same process that they build microelectronics in," Popovic said. "We use this fabrication process and instead of making just electrical circuits, we make photonics next to the electrical circuits so they can talk to each other."
In two papers published last month in Optics Letters with CU-Boulder postdoctoral researcher Jeffrey Shainline as lead author, the research team refined their original photonic-electronic chip further, detailing how the crucial optical modulator, which encodes data on streams of light, could be improved to become more energy efficient. That optical modulator is compatible with a manufacturing process -- known as Silicon-on-Insulator Complementary Metal-Oxide-Semiconductor, or SOI CMOS -- used to create state-of-the-art multicore microprocessors such as the IBM Power7 and Cell, which is used in the Sony PlayStation 3.
The researchers also detailed a second type of optical modulator that could be used in a different chip-manufacturing process, called bulk CMOS, which is used to make memory chips and the majority of the world's high-end microprocessors.
Vladimir Stojanovic, who leads one of the MIT teams collaborating on the project and who is the lead principal investigator for the overall research program, said the group's work on optical modulators is a significant step forward.
"On top of the energy-efficiency and bandwidth-density advantages of silicon-photonics over electrical wires, photonics integrated into CMOS processes with no process changes provides enormous cost-benefits and advantage over traditional photonic systems," Stojanovic said.

Thursday, 3 October 2013

AUGMENTED REALITY MANUAL HELPS VOLKSWAGEN OWNERS REPAIR A CONCEPT CAR [VIDEO]


Early this year, Volkswagen revealed their ultra-limited edition hybrid XL1 car and promised to showcase the final model at the Geneva Motor Show. The Volkswagen XL1 is one of the the most futuristic, fuel-efficient vehicles on the planet. With such a reputable name, it is only fitting to have an equally impressive repair manual to match.

In collaboration with Metaio, Volkswagen developed the iPad app MARTA that employs the tablet’s built-in camera to provide step-by-step details on how to dismantle, repair, replace, and put back together all the intricate components of the motorized beauty. The augmented reality of maintenance instructions might just be a way automatics is headed in the future.

Audi has also released a similar application to introduce new A3 owners around the car’s interior features, as well as under the hood mechanical directions for automobile mechanics.

Wednesday, 2 October 2013

Accelerator On a Chip: Technology Could Spawn New Generations of Smaller, Less Expensive Devices for Science, Medicine:


The achievement was reported today in Nature by a team including scientists from the U.S. Department of Energy's (DOE) SLAC National Accelerator Laboratory and Stanford University.
"We still have a number of challenges before this technology becomes practical for real-world use, but eventually it would substantially reduce the size and cost of future high-energy particle colliders for exploring the world of fundamental particles and forces," said Joel England, the SLAC physicist who led the experiments. "It could also help enable compact accelerators and X-ray devices for security scanning, medical therapy and imaging, and research in biology and materials science."
Because it employs commercial lasers and low-cost, mass-production techniques, the researchers believe it will set the stage for new generations of "tabletop" accelerators.
At its full potential, the new "accelerator on a chip" could match the accelerating power of SLAC's 2-mile-long linear accelerator in just 100 feet, and deliver a million more electron pulses per second.
This initial demonstration achieved an acceleration gradient, or amount of energy gained per length, of 300 million electronvolts per meter. That's roughly 10 times the acceleration provided by the current SLAC linear accelerator.
"Our ultimate goal for this structure is 1 billion electronvolts per meter, and we're already one-third of the way in our first experiment," said Stanford Professor Robert Byer, the principal investigator for this research.
Today's accelerators use microwaves to boost the energy of electrons. Researchers have been looking for more economical alternatives, and this new technique, which uses ultrafast lasers to drive the accelerator, is a leading candidate.
Particles are generally accelerated in two stages. First they are boosted to nearly the speed of light. Then any additional acceleration increases their energy, but not their speed; this is the challenging part.
In the accelerator-on-a-chip experiments, electrons are first accelerated to near light-speed in a conventional accelerator. Then they are focused into a tiny, half-micron-high channel within a fused silica glass chip just half a millimeter long. The channel had been patterned with precisely spaced nanoscale ridges. Infrared laser light shining on the pattern generates electrical fields that interact with the electrons in the channel to boost their energy.
Turning the accelerator on a chip into a full-fledged tabletop accelerator will require a more compact way to get the electrons up to speed before they enter the device.
A collaborating research group in Germany, led by Peter Hommelhoff at the Max Planck Institute of Quantum Optics, has been looking for such a solution. It simultaneously reports in Physical Review Letters its success in using a laser to accelerate lower-energy electrons.
Applications for these new particle accelerators would go well beyond particle physics research. Byer said laser accelerators could drive compact X-ray free-electron lasers, comparable to SLAC's Linac Coherent Light Source, that are all-purpose tools for a wide range of research.
Another possible application is small, portable X-ray sources to improve medical care for people injured in combat, as well as provide more affordable medical imaging for hospitals and laboratories. That's one of the goals of the Defense Advanced Research Projects Agency's (DARPA) Advanced X-Ray Integrated Sources (AXiS) program, which partially funded this research. Primary funding for this research is from the DOE's Office of Science.

Solar Power's Future Brawl

Andrei Kryjevski and his colleagues, Dimitri Kilin and Svetlana Kilina, report in AIP Publishing's Journal of Renewable and Sustainable Energy that they used computational chemistry models to predict the electronic and optical properties of three types of nanoscale (billionth of a meter) silicon structures with a potential application for solar energy collection: a quantum dot, one-dimensional chains of quantum dots and a nanowire. The ability to absorb light is substantially enhanced in nanomaterials compared to those used in conventional semiconductors. Determining which form -- quantum dots or nanowire -- maximizes this advantage was the goal of the numerical experiment conducted by the three researchers.
"We used Density Functional Theory, a computational approach that allows us to predict electronic and optical properties that reflect how well the nanoparticles can absorb light, and how that effectiveness is affected by the interaction between quantum dots and the disorder in their structures," Kryjevski said. "This way, we can predict how quantum dots, quantum dot chains and nanowires will behave in real life even before they are synthesized and their working properties experimentally checked."
The simulations made by Kryjevski, Kilin and Kilina indicated that light absorption by silicon quantum dot chains significantly increases with increased interactions between the individual nanospheres in the chain. They also found that light absorption by quantum dot chains and nanowires depends strongly on how the structure is aligned in relation to the direction of the photons striking it. Finally, the researchers learned that the atomic structure disorder in the amorphous nanoparticles results in better light absorption at lower energies compared to crystalline-based nanomaterials.
"Based on our findings, we believe that putting the amorphous quantum dots in an array or merging them into a nanowire are the best assemblies for maximizing the efficiency of silicon nanomaterials to absorb light and transport charge throughout a photovoltaic system," Kryjevski said. "However, our study is only a first step in a comprehensive computational investigation of the properties of semiconductor quantum dot assemblies.
"The next steps are to build more realistic models, such as larger quantum dots with their surfaces covered by organic ligands and simulate the processes that occur in actual solar cells," he added.