A new step towards using graphene in electronic applications

(A) This image is a diagram of molecular precursors, the resulting graphene nanoribbons and the heterostructured ones. (B) Tunnel microscopy images of the heterostructures synthesized on gold surfaces. Credit: UPV/EHU

Few materials have received as much attention from the scientific world or have raised so many hopes with a view to their potential deployment in new applications as graphene has. This is largely due to its superlative properties: it is the thinnest material in existence, almost transparent, the strongest, the stiffest and at the same time the most strechable, the best thermal conductor, the one with the highest intrinsic charge carrier mobility, plus many more fascinating features. Specifically, its electronic properties can vary enormously through its confinement inside nanostructured systems, for example. That is why ribbons or rows of graphene with nanometric widths are emerging as tremendously interesting electronic components. On the other hand, due to the great variability of electronic properties upon minimal changes in the structure of these nanoribbons, exact control on an atomic level is an indispensable requirement to make the most of all their potential.

The lithographic techniques used in conventional nanotechnology do not yet have such resolution and precision. In the year 2010, however, a way was found to synthesise nanoribbons with atomic precision by means of the so-called molecular self-assembly. 

Molecules designed for this purpose are deposited onto a surface in such a way that they react with each other and give rise to perfectly specified graphene nanoribbons by means of a highly reproducible process and without any other external mediation than heating to the required temperature. In 2013 a team of scientists from the University of Berkeley and the Centre for Materials Physics (CFM), a mixed CSIC (Spanish National Research Council) and UPV/EHU (University of the Basque Country) centre, extended this very concept to new molecules that were forming wider graphene nanoribbons and therefore with new electronic properties. This same group has now managed to go a step further by creating, through this self-assembly, heterostructures that blend segments of graphene nanoribbons of two different widths.

The forming of heterostructures with different materials has been a concept widely used in electronic engineering and has enabled huge advances to be made in conventional electronics. "We have now managed for the first time to form heterostructures of graphene nanoribbons modulating their width on a molecular level with atomic precision. What is more, their subsequent characterisation by means of scanning tunnelling microscopy and spectroscopy, complemented with first principles theoretical calculations, has shown that it gives rise to a system with very interesting electronic properties which include, for example, the creation of what are known as quantum wells," pointed out the scientist Dimas de Oteyza, who has participated in this project. This work, the results of which are being published this very week in the journal Nature Nanotechnology, therefore constitutes a significant success towards the desired deployment of graphene in commercial electronic applications.

Dr Dimas G. de Oteyza, who was previously at Berkeley and at the CFM, is currently working at the Donostia International Physics Center (DIPC) as a Fellow Gipuzkoa.

Source: University of the Basque Country

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Printing in the hobby room: Paper-thin and touch-sensitive displays on various materials

Paper- thin and touch-sensitive displays on various materials.
Credit: Image courtesy of University Saarland

Until now, if you want to print a greeting card for a loved one, you can use colorful graphics, fancy typefaces or special paper to enhance it. But what if you could integrate paper-thin displays into the cards, which could be printed at home and which would be able to depict self-created symbols or even react to touch? Those only some of the options computer scientists in Saarbrücken can offer. They developed an approach that in the future will enable laypeople to print displays in any desired shape on various materials and therefore could change everyday life completely.

For example: A postcard depicts an antique car. If you press a button, the back axle and the steering wheel rim light up in the same color. Two segments on a flexible display, which have the same shape as those parts of the car, can create this effect. Computer scientists working with Jürgen Steimle printed the post card using an off-the-shelf inkjet printer. It is electro-luminescent: If it is connected to electric voltage, it emits light. This effect is also used to light car dashboards at night.

Steimle is leader of the research group "Embodied Interaction" at the Cluster of Excellence "Multimodal Computing and Interaction." Simon Olberding is one of his researchers. "Until now, this was not possible," explains Olberding. "Displays were mass-produced, they were inflexible, they always had a rectangular shape." Olberding and Steimle want to change that. The process they developed works as follows: The user designs a digital template with programs like Microsoft Word or Powerpoint for the display he wants to create.

By using the methods the computer scientists from Saarbrücken developed, called "Screen Printing" and "Conductive Inkjet Printing," the user can print those templates. Both approaches have strengths and weaknesses, but a single person can use them within either a few minutes or two to four hours. The printing results are relatively high-resolution displays with a thickness of only 0.1 millimeters. It costs around €20 to print on a DIN A4 page; the most expensive part is the special ink. Since the method can be used to print on materials like paper, synthetic material, leather, pottery, stone, metal and even wood, two-dimensional and even three-dimensional shapes can be realized. Their depiction can either consist of one segment (surface, shape, pattern, raster graphics), several segments or variously built-up matrixes. "We can even print touch-sensitive displays," says Olberding.

The possibilities for the user are various: displays can be integrated into almost every object in daily life -- users can print not only on paper objects, but also on furniture or decorative accessories, bags or wearable items. For example, the strap of a wristwatch could be upgraded so that it lights up if a text message is received. "If we combine our approach with 3D printing, we can print three-dimensional objects that display information and are touch-sensitive," explains Steimle.

Source: University Saarland

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Live adaptation of organ models in the OR

The non-deformed liver model (red) adapts to the deformed surface profile (blue). Credit: Graphics: Dr. Stefanie Speidel, KIT, in Medical Physics, 41

During minimally invasive operations, a surgeon has to trust the information displayed on the screen: A virtual 3D model of the respective organ shows where a tumor is located and where sensitive vessels can be found. Soft tissue, such as the tissue of the liver, however, deforms during breathing or when the scalpel is applied. Endoscopic cameras record in real time how the surface deforms, but do not show the deformation of deeper structures such as tumors. Young scientists of the Karlsruhe Institute of Technology (KIT) have now developed a real-time capable computation method to adapt the virtual organ to the deformed surface profile.

The principle appears to be simple: Based on computer tomography image data, the scientists construct a virtual 3D model of the respective organ, including the tumor, prior to operation. During the operation, cameras scan the surface of the organ and generate a stiff profile mask. To this virtual mold, the 3D model then is to fit snuggly, like jelly to a given form. The Young Investigator Group of Dr. Stefanie Speidel analyzed this geometrical problem of shape adaptation from the physical perspective. "We model the surface profile as electrically negative and the volume model of the organ as electrically positive charged," Speidel explains. "Now, both attract each other and the elastic volume model slides into the immovable profile mask." The adapted 3D model then reveals to the surgeon how the tumor has moved with the deformation of the organ.

Simulations and experiments using a close-to-reality phantom liver have demonstrated that the electrostatic-elastic method even works when only parts of the deformed surface profile are available. This is the usual situation at the hospital. The human liver is surrounded by other organs and, hence, only partly visible by endoscopic cameras. "Only those structures that are clearly identified as parts of the liver by our system are assigned an electric charge," says Dr. Stefan Suwelack who, as part of Speidel's group, wrote his Ph.D. thesis on this subject. Problems only arise, if far less than half of the deformed surface is visible. To stabilize computation in such cases, the KIT researchers can use clear reference points, such as crossing vessels. Their method, however, in contrary to others does not rely on such references from the outset.

In addition, the model of the KIT researchers is more precise than conventional methods, because it also considers biomechanical factors of the liver, such as the elasticity of the tissue. So for instance, the phantom liver used by the scientists consists of two different silicones: A harder material for the capsule, i.e. the outer shell of the liver, and a softer material for the inner liver tissue.

As a result of their physical approach, the young scientists also succeeded in accelerating the computation process. As shape adaptation was described by electrostatic and elastic energies, they found a single mathematical formula. Using this formula, even conventional computers equipped with a single processing unit only work so quickly that the method is competitive. Contrary to conventional computation methods, however, the new method is also suited for parallel computers. Using such a computer, the Young Investigator Group now plans to model organ deformations stably in real time.

Source: Karlsruhe Institute of Technology

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Self-repairing software tackles malware

Eric Eide, University of Utah research assistant professor of computer science, stands in the computer science department's "Machine Room" where racks of web servers sit. It is on these computers that Eide, U computer science associate professor John Regehr, and their research team created and tested A3, a suite of computer applications that defeat malware and automatically repair the damage it causes. The project could help lead to better consumer software defenses.
Credit: Dan Hixson/University of Utah College of Engineering

University of Utah computer scientists have developed software that not only detects and eradicates never-before-seen viruses and other malware, but also automatically repairs damage caused by them. The software then prevents the invader from ever infecting the computer again.

A3 is a software suite that works with a virtual machine -- a virtual computer that emulates the operations of a computer without dedicated hardware. The A3 software is designed to watch over the virtual machine's operating system and applications, says Eric Eide, University of Utah research assistant professor of computer science leading the university's A3 team with U computer science associate professor John Regehr. A3 is designed to protect servers or similar business-grade computers that run on the Linux operating system. It also has been demonstrated to protect military applications.

The new software called A3, or Advanced Adaptive Applications, was co-developed by Massachusetts-based defense contractor, Raytheon BBN, and was funded by Clean-Slate Design of Resilient, Adaptive, Secure Hosts, a program of the Defense Advanced Research Projects Agency (DARPA). The four-year project was completed in late September.

There are no plans to adapt A3 for home computers or laptops, but Eide says this could be possible in the future.

"A3 technologies could find their way into consumer products someday, which would help consumer devices protect themselves against fast-spreading malware or internal corruption of software components. But we haven't tried those experiments yet," he says.

U computer scientists have created "stackable debuggers," multiple de-bugging applications that run on top of each other and look inside the virtual machine while it is running, constantly monitoring for any out-of-the-ordinary behavior in the computer.

Unlike a normal virus scanner on consumer PCs that compares a catalog of known viruses to something that has infected the computer, A3 can detect new, unknown viruses or malware automatically by sensing that something is occurring in the computer's operation that is not correct. It then can stop the virus, approximate a repair for the damaged software code, and then learn to never let that bug enter the machine again.

While the military has an interest in A3 to enhance cybersecurity for its mission-critical systems, A3 also potentially could be used in the consumer space, such as in web services like Amazon. If a virus or attack stops the service, A3 could repair it in minutes without having to take the servers down.

To test A3's effectiveness, the team from the U and Raytheon BBN used the infamous software bug called Shellshock for a demonstration to DARPA officials in Jacksonville, Florida, in September. A3 discovered the Shellshock attack on a Web server and repaired the damage in four minutes, Eide says. The team also tested A3 successfully on another half-dozen pieces of malware.

Shellshock was a software vulnerability in UNIX-based computers (which include many web servers and most Apple laptops and desktop computers) that would allow a hacker to take control of the computer. It was first discovered in late September. Within the first 24 hours of the disclosure of Shellshock, security researchers reported that more than 17,000 attacks 

by hackers had been made with the bug.

"It is a pretty big deal that a computer system could automatically, and in a short amount of time, find an acceptable fix to a widespread and important security vulnerability," Eide says. 

"It's pretty cool when you can pick the Bug of the Week and it works."

Now that the team's project into A3 is completed and proves their concept, Eide says the U team would like to build on the research and figure out a way to use A3 in cloud computing, a way of harnessing far-flung computer networks to deliver storage, software applications and servers to a local user via the Internet.

The A3 software is open source, meaning it is free for anyone to use, but Eide believes many of the A3 technologies could be incorporated into commercial products.

Other U members of the A3 team include research associate David M. Johnson, systems programmer Mike Hibler and former graduate student Prashanth Nayak.

Source: University of Utah

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Software models more detailed evolutionary networks from genetic data

Phylogenetic networks depict the movement of genetic sequences from one species to another as a means of showing where horizontal gene transfer may have taken place. Software by scientists at Rice University aims to reveal far more about species’ evolutionary histories than traditional tree models are able to. Credit: Luay Nakhleh/Rice University

The tree has been an effective model of evolution for 150 years, but a Rice University computer scientist believes it's far too simple to illustrate the breadth of current knowledge.

Rice researcher Luay Nakhleh and his group have developed PhyloNet, an open-source software package that accounts for horizontal as well as vertical inheritance of genetic material among genomes. His "maximum likelihood" method, detailed this month in the Proceedings of the National Academy of Sciences, allows PhyloNet to infer network models that better describe the evolution of certain groups of species than do tree models.

"Inferring" in this case means analyzing genes to determine their evolutionary history with the highest probability -- the maximum likelihood -- of connections between species. Nakhleh and Rice colleague Christopher Jermaine recently won a $1.1 million National Science Foundation grant to analyze evolutionary patterns using Bayesian inference, a statistics-based technique to estimate probabilities based on a data set.

To build networks that account for all of the genetic connections between species, the software infers the probability of variations that phylogenetic trees can't illustrate, such as horizontal gene transfers. These transfers circumvent simple parent-to-offspring evolution and allow genetic variations to move from one species to another by means other than reproduction.

Biologists want to know when and how these transfers happened, but tree structures conceal such information. "When horizontal transfer occurs, as with the hybridization of two species, the tree model becomes inadequate to describe the evolutionary history, and networks that incorporate horizontal gene transfer become the more appropriate model," Nakhleh said.

Nakhleh's Java-based software accounts for incomplete lineage sorting, in which clues to gene evolution that don't match the established lineage of species appear in the genetic record.

"We are the first group to develop a general model that will allow biologists to estimate hybridization while accounting for all these complexities in evolution," Nakhleh said.

Most existing programs for phylogenetics (the study of evolutionary relationships) ignore such complexities. "They end up overestimating the amount of hybridization," Nakhleh said. 

"They start seeing lots of complexities in the data and say, 'Oh, it's complex here; it must be hybridization,' and end up inferring too much. Our method acknowledges that part of the complexity has nothing to do with hybridization; it has to do with other random processes that happened during evolution."

The Rice researchers used two data sets to test the new program. One, a computer-generated set of data that mimics a realistic model of evolution, allowed them to evaluate the accuracy of the program. The second involved multiple genomes of mice found across Europe and Asia. "There have been stories about mice hybridizing," Nakhleh said. "Now that we have the first method to allow for systematic analysis, we ran it on a very large amount of data from five mouse samples and we detected hybridization" -- most notably in the presence of a genetic signal from a mouse in Kazakhstan that found its way to mice in France and Germany, he said.

Nakhleh hopes evolutionary biologists will use PhyloNet to take a fresh look at the massive amount of genomic data collected over the past few decades. "The exciting thing for me about this is that biologists can now systematically go through lots of data they have generated and check to see if there has been hybridization."

Source: Rice University

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Cheaper 3-D virtual reality system: Powerful enough for a gamer, made for an engineer

It's like a scene from a gamer's wildest dreams: 12 high-definition, 55-inch 3D televisions all connected to a computer capable of supporting high-end, graphics-intensive gaming.
Credit: Image courtesy of Brigham Young University

It's like a scene from a gamer's wildest dreams: 12 high-definition, 55-inch 3D televisions all connected to a computer capable of supporting high-end, graphics-intensive gaming.

On the massive screen, images are controlled by a Wii remote that interacts with a Kinnect-like Bluetooth device (called SmartTrack), while 3D glasses worn by the user create dizzying added dimensions.

But this real-life, computer-powered mega TV is not for gaming. It's for engineering.

Welcome to Brigham Young University's VuePod, a 3D immersive visualization environment run by BYU's Department of Civil and Environmental Engineering. Student-built and operated, under the supervision of civil engineering professor Dan Ames, the VuePod is changing the way engineers are viewing environmental engineering challenges.

"This is gold," said fellow BYU civil engineering professor Kevin Franke. "This technology has the ability to revolutionize my job as an earthquake engineer."

That's because the VuePod allows users to virtually fly over, wander through or hover above 3D environments that are otherwise difficult to visit. The images are created by point data from aircraft equipped with LIDAR (think RADAR, but with lasers). The LIDAR scans the landscape and records millions of data points that are then viewed as an image on the VuePod. Point data can also be created from stitched-together photographs taken from low-cost drones, which is Franke's research focus.

One set of data currently available for study in the VuePod captured a canyon area beneath a plateau in southern Idaho. With 3D glasses and the Wii controller, a user can virtually drop down into the canyon from above, and then fly from one end to the other.

As cool as it is to fly through a canyon, the real engineering application comes in when you combine two sets of data for the same canyon, taken five years a part. With the second set of data, changes in the natural landscape that are invisible to the human eye become clear as day. Thanks to the VuePod's massive 108-square-foot screen, all of the image-making data can be presented for viewing.

"Our eyes and our brains are so amazing; we need to take full advantage of them," Ames said. "That's the value of this project: we're presenting more information for the human eyes to detect changes."

In addition to natural change detection, the VuePod has the potential to assist in infrastructure monitoring -- such as tracking how highways hold up (or slough and crack) over time and seeing the affect on buildings after severe weather or earthquakes.

While the VuePod is certainly not the first immersive visualization system in academia, it may just be the most cost efficient built to date. Some systems cost as much as $10 million to build and maintain, while BYU's VuePod just barely topped the $30,000 mark.

Ames details how BYU was able to build such a powerful system for so little in a new paper published by the Journal of Computing in Civil Engineering.

"Our question has been: How can we make this technology accessible?" Ames said. "We're trying to determine the threshold for getting the most function at the most affordable cost. Ultimately, the goal is to take an expensive tool and make it cheaper for an everyday engineering firm to use."

And even though Ames and his students have achieved that, they believe much more can be done.

"We want whoever reads this paper to be able to build a better system than we built," he said.

Source: Brigham Young University

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Playing action video games can boost learning, study finds

A new study shows for the first time that playing action video games improves not just the skills taught in the game, but learning capabilities more generally.

A new study shows for the first time that playing action video games improves not just the skills taught in the game, but learning capabilities more generally.

"Prior research by our group and others has shown that action gamers excel at many tasks. In this new study, we show they excel because they are better learners," explained Daphne Bavelier, a research professor in brain and cognitive sciences at the University of Rochester. "And they become better learners," she said, "by playing the fast-paced action games."

According to Bavelier, who also holds a joint appointment at the University of Geneva, our brains keep predicting what will come next -- whether when listening to a conversation, driving, or even preforming surgery. "In order to sharpen its prediction skills, our brains constantly build models, or 'templates,' of the world," she explained. "The better the template, the better the performance. And now we know playing action video game actually fosters better templates."

Action Players vs. Non-Action Players

In the current study, published in the Proceedings of the National Academy of Sciences, Bavelier and her team first used a pattern discrimination task to compare action video game players' visual performance with that of individuals who do not play action video games.
The action-gamers outperformed the non-action gamers. The key to the action-gamers success, the researchers found, was that their brains used a better template for the task at 
hand.

Video Training

Then, the team conducted another experiment to determine if habitual players of fast-paced, action-rich video games may be endowed with better templates independently of their game play, or if the action game play lead them to have better templates.

Individuals with little video game experience were recruited, and as part of the experiment, they were asked to play video games for 50 hours over the course of nine weeks. One group played action video games, e.g., Call of Duty. The second group played 50 hours of non-action video games, such as The Sims.

The trainees were tested on a pattern discrimination task before and after the video game "training." The test showed that the action video games players improved their templates, compared to the control group who played the non-action video games. The authors then turned to neural modeling to investigate how action video games may foster better templates.

Measuring Learning

When the researchers gave action gamers a perceptual learning task, the team found that the action video game players were able to build and fine tune templates quicker than non-action game control participants. And they did so on the fly as they engaged in the task.
Being a better learner means developing the right templates faster and thus better performance. And playing action video games, the research team found boosts that process.
"When they began the perceptual learning task, action video gamers were indistinguishable from non-action gamers; they didn't come to the task with a better template," said Bavelier. "Instead, they developed better templates for the task, much, much faster showing an accelerated learning curve."

The researchers also found that the action gamers' improved performance is a lasting effect. When tested several months to a year later, the action-trained participants still outperformed the other participants, suggesting that they retained their ability to build better templates.

Bavelier's team is currently investigating which characteristics in action video games are key to boost players' learning. "Games other than action video games may be able to have the same effect," she said. "They may need to be fast paced, and require the player to divide his or her attention, and make predictions at different time scales."

Vikranth R. Bejjanki of the University of Rochester and Princeton University, and Ruyuan Zhang of the University of Rochester are co-lead authors of the study. In addition to Bavelier and the lead authors, researchers from the University of Geneva, University of Wisconsin-Madison, and Ohio State University also contributed to the study.

The Office of Naval Research, the Swiss National Foundation, The Human Frontier Science Program, and the National Eye Institute supported the research.

Source: University of Rochester

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Researchers develop a system to reconstruct grape clusters in 3D, assess quality

Antonio José Sánchez Salmerón, researcher at the Instituto ai2 of the UPV, explains that, today, grape classification is based on an inspection by a panel of experts, that award it score depending on a series of parameters that determine its quality. Credit: Image courtesy of Asociación RUVID

Researchers of the Universitat Politècnica de València (UPV) have developed software to help reconstruct grape clusters with three-dimensional computer vision techniques. The system helps to automatically assess different parameters that define the quality of the wine grape during harvest time.

During the work, the researchers of the UPV collaborated with the Research Centre of Vine and Wine related Sciences of the University of La Rioja, the Spanish National Research Council (CSIC, in Spanish) and the Government of La Rioja. The results of this work were released last September in the journal Food Control.

Antonio José Sánchez Salmerón, researcher at the Instituto ai2 of the UPV, explains that, today, grape classification is based on an inspection by a panel of experts, that award it score depending on a series of parameters that determine its quality. Moreover, different tests are performed in the laboratory in order to estimate the quantity of sugar, the pH, the total acidity and the phenolic quality.

"Among the factors that define the quality of a wine, one of the most important is the quality of the grape as the raw material, but this concept is difficult to assess, due to problems such as subjective parameters, the short period of time available in the field to do the analysis during harvest time, the lack of measuring instruments and their high price, as well as the mixing of good quality and bad quality grape in the trucks. The introduction of this 3D grape reconstruction system helps assess different quality parameters for a wine grape cluster avoiding these problems. One of these parameters is the average size of the grape, which is a very important factor as it establishes the ratio between the quantity of skin and pulp," explains the researcher.

"Increasing the objectivity and automating the grape quality monitoring tasks would be a technological breakthrough with regard to the traditional evaluation system of the grape, based on the knowledge of an expert, and it would have a great impact on the wine industry," adds Sánchez.

Source: Asociación RUVID

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