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New U.S. Military Chip Self Destructs on Command

A new chip built on strained glass can shatter within 10 seconds when remotely triggered. It’s not quite as fast as the fictional Mission: Impossible messages that self-destruct in five seconds, but such vanishing electronics could prove tremendously useful for the U.S. military and corporations by keeping data secure and out of unwanted hands.

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Stimulating Damaged Spines Rewires Rats for Recovery

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A promising new study shows that the nervous system can rewire itself—with a little help from neural engineers. 

For someone with a spinal cord injury, destroyed neurons act like a roadblock that prevents movement commands from traveling down the spinal cord and along the nerves. Although an injured person wills his fingers to grasp a cup, for example, the command never makes it to his hand.

But a study published today suggests that precisely controlled electrical stimulation can encourage the nervous system to create detours around that roadblock, allowing the command to get through. 

Neuroscientist Steve Perlmutter and his colleagues at the University of Washington devised a clever experiment using rats. The animals were first trained to perform a task in which they reached through narrow slots with their dominant forelimbs to grab food pellets. The rats were then given incomplete spinal cord injuries that almost totally paralyzed those limbs.

Next the rats were divided into three groups and, as if they were in physical therapy, trained again on the same task. The control group tried to perform the reach-and-grasp task unaided, the second group received random pulses of electrical stimulation in their spinal cords during the task, and the third group received stimulation pulses that were triggered by the rats’ attempts to move their immobilized limbs. 

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Image: Perlmutter et al.
The head-mounted neurochip device recorded electrical signals from the muscles (called electromyographic or EMG activity) and triggered pulses of intraspinal microstimulation (ISMS).

The key advance here is that triggering technique. The researchers used a device called the neurochip-2, which recorded the weak electrical signal from the limb muscles and used that signal as the cue to initiate a pulse of electrical stimulation in the spinal cord. When the attempted muscle movement was synchronized with neural stimulation, the researchers believe that surviving neurons in the spinal cord formed new connections linking the muscles to the brain’s motor control region.  

What’s the underlying mechanism behind this remarkable repair work? I have just one word for you: neuroplasticity. Neural networks are malleable, and changing the patterns of connections between neurons can restore lost function. That’s why people who’ve suffered spinal cord injuries do rehab: They’re not trying to bring dead neurons back to life, but rather to teach the nervous system to work around them. However, people typically don’t recover much function with rehab alone. 

Perlmutter’s research suggests that adding electrical stimulation to rehab could provide a real boost. Over the course of the three-month study, the rats with neurochips showed dramatic improvement. The synchronized-stimulation rats ultimately performed the task 63 percent as well as they had before their injuries. Both the control group and the random-stimulation group performed about 30 percent as well as they did pre-injury.

Spectrum has covered “closed-loop” neurostimulation systems before, most notably in this feature article written by researchers from the companies Medronic, Cyberonics, and Neuropace. The authors described systems that used various bodily signals to trigger electrical pulses that countered epilepsy attacks and chronic pain. Such smart and responsive systems, which are now being used in humans, seem a clear step forward in electrical therapeutics

While the study from Perlmutter and his colleagues was conducted in rats, it points the way toward a new rehab strategy for people with spinal cord injuries. What’s more, it serves as a proof of principle for a strategy that may help people with other nervous system dysfunctions. By leveraging “the nervous system’s intrinsic capacity for reorganization and repair,” the authors write, electrical stimulation could help people regain lost motor abilities, perhaps, or bladder, bowel, or sexual function. 

"Tardis" Memory Could Enable Huge Multi-Core Computer Chips

Future generations of computer chips could become much more powerful, with processors containing hundreds or even thousands of cores. But these huge multi-core processors will also require loads of memory so their directories can keep track of data on each individual core and coordinate updates to shared data. A new MIT technique promises to greatly reduce the required memory for such coordination as multi-core processors scale up in the coming years.

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What's Next After 25 Years of Wi-Fi?

In 1997, the first version of Wi-Fi appeared. (The same year saw about half of U.S. homes using AOL as their Internet Service Provider, Netscape with the most web browser users, and Microsoft rescuing Apple from the verge of bankruptcy.) Today, the the Wi-Fi standard known as IEEE 802.11 celebrates its 25th anniversary in a world where many people take Wi-Fi access for granted while streaming high-definition video and checking in on social media through their smartphones and laptops.

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Experiments Show How Lasers Can Despin Asteroids by Turning Them Into Rockets

Sometime in the 2020s, NASA will launch the Asteroid Redirect Mission (ARM) towards a 30-meter space rock with the goal of picking a boulder up off of its surface and returning the rock to Earth for us to have a look at. NASA has to be very careful in deciding which asteroid to plunder for this mission, because the spacecraft the space agency plans to send won't have a good way of dealing with an asteroid that's spinning, which lots of asteroids are. And realistically, how the heck do you stop a giant space boulder from spinning, anyway? The answer is of course to use lasers, because, well, lasers solve everything.

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Metasurface Optics for Better Cellphone Cameras and 3-D Displays

Engineers at the California Institute of Technology have created a metasurface out of tiny pillars of silicon that act as waveguides for light. The way they arrange the pillars allows them to control the phase of light passing through the surface; this ability gives them control over how the light is focused, as well as its polarization, which is important for uses such as liquid crystal displays and 3-D glasses. Metasurfaces are structured planes so thin that they count as being two-dimensional; their periodic designs manipulate light in unusual ways.

“We're trying to create kind of a new platform for optics,” says Amir Arbabi, a postdoc in Andrei Faraon's Nanoscale and Quantum Optics Lab. The team described their work in the latest issue of Nature Nanotechnology.

The silicon pillars have to be somewhat shorter than the wavelength of light they're designed to manipulate. In the case of the metasurface described in the paper, the pillars are 715 nanometers tall, to handle infrared light with a wavelength of 915 nm. But they could easily be made shorter for visible light, Arbabi says. The pillars range in diameter from 65 to 455 nm, and they're elliptical in shape. The ellipses are not all oriented in the same direction; the pillars’ thickness and orientation determine how they focus and polarize the light passing through them.

Many of the same effects can be achieved with traditional optics, but that requires lining up multiple components such as lenses and prisms and beam splitters. The metasurface gets the job done with less bulk, allowing, among other things, thinner, lighter-weight cell phone camera lenses and better systems for directing the beams of industrial cutting lasers. It could also lead to novel applications. Using one of these devices, a display could switch between two polarizations and display two different holographic images. Or with an intermediate polarization, it could superimpose one image on the other. The metasruface could provide the optics for an LCD to create a 3-D display viewable from many angles without glasses.

What’s more, all of this can be done using the same lithography techniques used to build computer chips, doing away with individual fabrication and manual alignment of components. “We're trying to take these free-space components that are bulky and large and put them on a chip,” Arbabi says.

It shouldn't take much effort to move these metasurfaces from the lab to the marketplace, says Faraon. It's mainly a question of figuring out which optical system applications could benefit from the kind of mass production this technology makes possible. The array of potential applications is vast, Faraon says. “It gives you a unified framework, so you can design whatever optical component you would like.”

            

Say Hello to MIAOW, the First Open Source Graphics Processor

While open-source hardware is already available for CPUs, researchers from the Vertical Research Group at the University of Wisconsin-Madison have announced at the Hot Chips Event in Cupertino, Calif., that they have created the first open source general-purpose graphics processor (GPGPU). 

Called MIAOW, which stands for Many-core Integrated Accelerator Of the Waterdeep, the processor is a resistor-transistor logic implementation of AMD's open source Southern Islands instruction set architecture. The researchers published a white paper on the device. 

The creation of MIAOW is the latest in a series of steps meant to keep processor development in step with Moore's Law, explains computer scientist Karu Sankaralingham, who leads the Wisconsin research group. 

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Europe Mismanages 10 Times the Amount of E-Waste It Exports

Broken electronics shipped off to foreign shores can lead to environmental damage and health risks for scavenging workers. But a European Union-funded report has found that mismanagement and illegal trading of electronic waste within Europe itself can involve 10 times the amount of e-waste that ends up as undocumented exports to other countries.

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How to Build a Space Elevator From Scratch

Even with innovations like SpaceX’s reusable robotic boosters, chemical rockets remain an expensive, dangerous and unreliable way to reach orbit. How much easier it would be if astronauts could simply step into an elevator, press O for Orbit, and ascend gracefully to outer space.

This is the dream of the collection of scientists, engineers, and entrepreneurs in the International Space Elevator Consortium (ISEC) who got together for its annual conference last week in Seattle.

The idea of a space elevator has been around for over a century. The basic concept is simple: a tether descends from a spacecraft in geostationary orbit to a floating platform at the equator, probably in the eastern Pacific Ocean. Because of a counterweight that would extend far into space, the space elevator’s tether would be gravitationally stable, allowing electric elevator cars to make the week-long climb to orbit powered by solar panels and ground-based lasers.

Such a system, ISEC researchers believe, could eventually slash the cost of raising a kilogram of payload into geosynchronous orbit from roughly US $25,000 to $300 or less. The key word, of course, is “eventually.” Technical challenges are legion, including building the aircraft carrier–size floating platform, designing safe, speedy climbers, and avoiding space debris and other satellites. But the truly fundamental obstacle is the lack of a material strong and resilient enough to form the elevator’s tether.

In current designs, the space elevator’s tether is not a thick round cable as originally proposed, but a paper-thin ribbon, a meter wide and 100,000 kilometers long. Even with such a slimmed-down approach, the strain of simply keeping its own mass aloft would instantly shred any tether made from steel, Kevlar, carbon composites, or even the best carbon nanotubes we can currently make.

In the ISEC conference’s keynote address, Mark Haase, a materials engineer from the University of Cincinnati, talked about how a tether at least ten times stronger than anything existing today might be made. His idea started with carbon nanotubes, which still hold tremendous promise for the manufacturing of superstrong materials. Discovered in 1991, carbon nanotubes are cylindrical structures formed by sheets of single carbon atoms. They are already being manufactured in bulk, mostly as an additive to other materials in order to boost their strength and thermal or electrical conductivity.

But while individual carbon nanotubes can be immensely strong, they are awkward to tease into macroscopic-scale objects. They can’t be melted and extruded like Kevlar, nor sorted and aligned like natural fibers. The longest carbon nanotube made so far, if stood on its end, would barely reach a child’s knee, let alone one-quarter of the way to the Moon. Haase believes that the way forward is to cross-link nanotube molecules using minuscule amounts of polymer glue.

ISEC is not putting all of its eggs in a basket made from carbon nanotubes, however. Graphene, a single-atom-thick sheet of carbon, is also a promising material, although it does not respond as well as nanotubes to the kind of twisting and bending that a 100,000-km-long tether moving back and forth through the atmosphere would certainly experience.

More exotic still are boron nitride nanotubes. Similar in form to carbon nanotubes but made up of alternating boron and nitrogen atoms, this ceramic is incredibly chemically stable. That quality should help it survive long periods situated high in Earth’s atmosphere where highly reactive atomic oxygen would likely degrade a carbon nanotube tether. (Engineers on the nanotube track say they have devised a solution to this cosmic erosion: a gold coating for vulnerable sections of the tether.) Boron nitride nanotubes could also cope well with solar and cosmic radiation beyond the magnetosphere.

“As we gain more knowledge about these materials, we have a real chance to improve strengths,” says Haase. He predicts that the most promising candidates, nanotube-polymer composites, will reach the minimum strength needed for a space elevator tether “in about 20 years.”

Bryan Laubscher, a director at ISEC, believes that the search for a tether material will have an impact long before then. Laubscher, who left his job as an engineer at Lockheed Martin in 2010 to form a company developing high strength materials for use in aviation and space applications, says, “Imagine a Boeing 797 made from carbon nanotubes. It would have one-tenth of the mass of today’s aircraft, and an airframe that won’t come apart in a crash.” 

In fact, ISEC is relying on the private sector for every dime of the space elevator’s estimated $18 billion price-tag. In a position paper published earlier this year, ISEC noted, “To this point, we have found no needed capability within the government that must be incorporated in the space elevator architecture.”

That might be a swipe at NASA, which in 2012 abandoned a $2 million competition aimed at creating ultra-strong tether materials. But when even the world’s richest and most visionary space agency can’t help with your moonshot, you might want to at least consider that your lofty ambitions for a space elevator seem destined to stay firmly on the ground floor.

Developmental Gaming System for Autistic Children

To help children with autistic spectrum disorder improve their social skills, researchers from the University of Kentucky have developed a prototype of a social narrative and gaming system, called MEBook.

A Microsoft Kinect camera wired to a PC tracks a child’s facial expressions, body movements and other behavioral patterns. The system’s current instantiation uses video self-modeling (VSM), an evidence-based approach in which kids watch videos of themselves successfully performing social behaviors, such as waving or smiling, during the intervention. Video footage of the successful moments are spliced together and reviewed with the child afterward. Researchers hope to release a free, downloadable version of MEBook for parents to use at home by the end of this year.

“The incorporation of the gaming system encourages the child to practice what s/he has learned in the social narrative by rewarding the correct behaviors with points and praises,” says Sen-ching Samson Cheung, an associate professor of electrical and computer engineering at the University of Kentucky.

Inspired by his own son’s autism spectrum disorder, Cheung is leading this project and searching for ways to help others affected by the same disorder. “Since his diagnosis six years ago, I have been thinking of different ways to apply my research to improve autism diagnosis and interventions,” he says.

The problem with teaching autistic children using social narratives such as animated stories illustrating social situations, Cheung says, is that kids on the autism spectrum have difficulty relating the social behavior in fictitious scenarios to those that occur in real life. The researchers believe that showing “real” videos of the child himself, as the main character, performing precise behavioral patterns, will help him or her relate those patterns to real life. Eventually, this helps the child build confidence for similar social environments.

Nkiruka Uzuegbunam, a Ph.D. student collaborating with Cheung on this project, talks about the system in the video below.

The system uses computer vision and signal processing algorithms to separate the subject from the background and to identify when certain behaviors emerge. Some of these algorithms are based on the researchers’ previous work, in which a video surveillance system protected the privacy of certain individuals by detecting them and erasing them from the video footage.

Cheung says they’ve already finished a preliminary clinical study utilizing the prototype system with three autistic children. “The results are very encouraging; all of our subjects showed an increase of social greeting skills after the intervention,” he says. His team is currently summarizing the results for an IEEE journal.

His team of collaborators in education, psychology, and medicine are also in the early alpha stage of developing a virtual-mirror system. They are looking to start clinical studies on it in 2016. With that system, the child’s behavior is captured and modified in real-time, and the image is rendered on a mirror-like display. This is part of a four-year NSF grant to apply advanced multimedia technology to enhance “self-model and mirror feedback imageries” for behavior therapies for children with autism.

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