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Graphene Offers a Better Way to Capture T-rays

Researchers are already aware of the potential benefits of electronic devices that send and receive digital pulses at frequencies in the terahertz region of the electromagnetic spectrum. Devices for airport security, medical imaging, drug and food inspection, and high-speed communication, will be much more sensitive than today’s versions—that is, if researchers can develop better sources and detectors for that type of radiation. Now a team of scientists at the University of Maryland reports that it has used graphene to build a terahertz device that is at least as sensitive, and many times as fast, as existing detectors.

Graphene, a sheet of carbon atoms only one atomic layer thick, works well as a terahertz detector because of its ability to absorb radiation, from the ultraviolet to the terahertz regions, equally well. Meanwhile, terahertz radiation, also known as T-rays, can penetrate a wide variety of materials without the ionizing effects of x-rays, and can spectrographically identify materials, making it ideal for applications such as identifying drugs or explosives without harming people.

“[The graphene-based device] as good as any room-temperature detector in this spectral range, and potentially much better,” says Dennis Drew, a research scientist at the University of Maryland’s Center for Nanophysics and Advanced Materials. Drew and his colleagues presented their findings in the latest issue of Nature Nanotechnology.

The detector relies on the photothermoelectric effect. Photons striking the graphene cause electrons in the material to jump to a higher energy level. The affected graphene molecules want to dissipate the resulting thermal energy, but because the electrons lose the heat to the surrounding molecules rather slowly, placing metal contacts on the graphene allows the material to shed excess energy by pushing electrons to the metal. If the contacts are made of two different metals with different conductivity—in this case, gold and chromium—the result is a current. Measuring the current reveals how much terahertz power is being absorbed by the graphene.

Drew says the new detector is as sensitive as the Golay cell, another device used to detect terahertz rays. But while the Golay cell has a response time on the order of a second, the graphene detector makes the measurement in 0.1 nanosecond. Another alternative, a pyroelectric detector, has response times measured in milliseconds, and tends to be somewhat less sensitive.

The graphene detector’s ability to pick up terahertz rays might be further improved by various means, Drew says. Using multiple layers of the material may allow it to capture more radiation. Adding voltage gates to create P-N junctions could also raise such a detector’s performance. Contacts made from metals other than the ones used in the experiments detailed in the paper—aluminum, for example—might also increase the efficiency, though it’s harder to get aluminum to adhere to graphene. Drew says optimizing the performance is a relatively easy engineering challenge.

 

Iran Eases Restrictions on High-Speed Mobile Internet

Most cell phone users take mobile Internet services for granted. But Iran had to overcome the objections of hardliners before issuing the first 3G and 4G licenses for its mobile operators last week—an action that has finally empowered ordinary Iranians to swiftly upload images to Twitter and make video calls on their phones.

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Mind-blowing Advance? Direct Brain-to-Brain Communication Between Humans Demonstrated

In an experiment that one rival scientist dubbed a "stunt," Spanish researchers claim to be the first to have demonstrated direct brain-to-brain communication between humans. The researchers, led by Giulio Ruffini, CEO of Starlab in Barcelona, successfully transmitted the words "hola" and "ciao" in binary code from the brain of a person in India to the brains of three people in France. Electroencephalography (EEG), which monitors electric currents in the brain, was used to record the information from the sender's brain, and robotized transcranial magnetic stimulation (TMS), which causes neurons to fire from an electric current that is generated by a rapidly changing magnetic field, was used to deliver the message to the brains of the receivers in France. 

Researchers have for years been developing noninvasive systems for translating information directly from the human brain to the computer. These systems, called brain-computer interface, often involve brain activity-sensing tools such as EEG, functional near-infrared spectroscopy (fNIRS), and functional magnetic resonance imagine (fMRI). Researchers have also, to a lesser extent, experimented with translating information from the computer to the brain, using brain stimulating tools such as TMS — variations of which have also been used to treat depression — and transcranial focused ultrasound (FUS), which has been used to link the brains of rats

The Starlab experiment integrates two of these existing technologies to move a message from human brain to computer to human brain. The experiment was set up like this: While hooked up to an EEG device the sender was asked to imagine moving his hands or feet when shown an image that represented a 1 or 0, respectively. The EEG data was transmitted to the computer, translated into binary code, and emailed to the system at the recipients' end. The recipients, blindfolded, received electric pulses from the robotized TMS system in the visual cortex of their brains. That triggered the experience of phosphenes: the perception of seeing flashes of light that are not actually there. The recipients reported verbally when they experienced a flash, and this was translated into binary code and then to the message. It's super slow — the equivalent of telepathic Morse code. Still, the message was delivered. 

The authors published the experiment in PLoS One, describing it as "the first human brain-to-brain interface." Ruffini at Starlab said the work stemmed from his company's involvement in a four-year collaborative project funded by the European Commission to develop noninvasive brain stimulation technologies. The paper was "a way to show that our technologies work," said Ruffini in a phone interview.

It's a fun experiment, and it's exciting to think about potential (but far-fetched) applications, like soldiers with high-tech helmets communicating silently behind enemy lines. But some researchers not involved with the experiment say the paper doesn't really present a "first" and smacks of publicity grubbing. It's "pretty much a stunt I think as it's all been shown before," said Christopher James, a professor of biomedical engineering at the University of Warwick in the UK, in an email to IEEE Spectrum

A group at the University of Washington in Seattle led by Rajesh Rao last year demonstrated in an unpublished pilot study a very similar experiment involving EEG on the brain-to-computer end of the experiment and TMS on the computer-to-brain end. In that study, the researchers stimulated the motor cortex of the brain, causing the message receiver's hand to move subconsciously to strike a keyboard. The university declared it "the first noninvasive human-to-human brain interface." That was in August 2013. Rao told IEEE Spectrum he was "surprised and disappointed" that his experiment wasn't acknowledged in some way in Ruffini's paper.

Ruffini says he had seen Rao's experiment before publication of his, but that since it was unpublished "there was no paper to refer to." And he maintains that his paper was no stunt. "I believe such comments stem from not having read carefully the paper and missing the point," he says. Ruffini's experiment adds to scientific literature because unlike previous work, including Rao's, he stimulated the visual cortex, bypassing all peripheral nervous system involvement, and resulting in a conscious, rather than subconscious, brain-to-brain communication, Ruffini says. Rao's experiment "is interesting work. But I don't think's it's really brain-to-brain," he says.

Future experiments will no doubt help us define what "brain-to-brain interface" really means. In the meantime, we'll have to squabble over the few experiments under our belts. 

Converting Charge into Spin for Spintronics

Electronic circuits can only get so small before they’re overwhelmed with heat problems. Encoding bits using the spin of electrons, instead of the usual charge, promises to allow even smaller circuits—but the known processes of flipping electrons’ spins with external magnetic fields are inefficient and require very low temperatures, making such “spintronic” devices impractical.

Now, a team of researchers from Germany, the UK, the Czech Republic, and Japan have found a way to manipulate the spin of electrons using electric fields instead of magnetic ones. Their method, reported in the August issue of Nature Materials, could drastically reduce computers’ energy consumption and lessen heat problems caused by miniaturization.

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Medtronic Sees a High-Tech Solution to Global Health Woes

human os iconIf you believe that health care is a human right, as does Stephen Oesterle, Medtronic's VP of medicine and technology, you need to look for global health solutions that scale up. "We can't build enough hospitals or train enough physicians to take care of all these people," Oesterle says. The answer, he says, is a distributed model of medicine in which we put sensors in people's bodies and "a physician in every phone."

Medtronic is known for making pacemakers, brain implants, and other sophisticated medical devices that cost a pretty penny and are therefore primarily available to patients in the developed world. That's a market of about 1.5 billion people, Oesterle said in a talk at last week's meeting of the IEEE Engineering in Medicine and Biology Society. Another 1.5 billion people around the world have access to some rudimentary heath care, and 4 billion others have none. Oesterle is calling on engineers to design the tech that will bring medical care to these masses.

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Vagus Nerve Implant Fails to Fix Heart Failure

human os iconAttempts to use electronic implants to treat heart failure by stimulating one of a pair of nerves in the neck led to mixed results according to research presented this week at the 2014 European Society of Cardiology (ESC) Congress, in Barcelona. Boston Scientific's large, randomized trial failed to meet its key goals. But Cyberonics, which pioneered the use of such stimulators to combat epilepsy and depression, ran a smaller trial without controls that succeeded, according to Reuters.

Both trials used implanted electric stimulators that attached to one of a pair of key nerves in the neck, the vagus nerve. The nerve connects the brain to the heart, stomach, and other organs. It's a key target for medical device developers because it allows convenient access to the brain to treat disorders of that organ, such as epilepsy and depression, as well as to gut organs to treat other problems, such as obesity.

Heart failure, the inability of the heart to pump enough blood to satisfy the body's needs, has also been on the list of targets. The failure of Boston Scientific's trial was a big surprise to its leaders. "There is robust pre-clinical data showing the benefit of [vagus nerve stimulation], but the NECTAR-HF trial failed to demonstrate a successful clinical translation of this protocol," Faiez Zannad an investigator in the trial at l'Institut Lorrain du Coeur et des Vaisseaux Louis Mathieu, in Vandoeuvre-lès-Nancy, France, said in a press release.

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Two Galileo Satellites Are Parked In the Wrong Spots

On 22 August, a Soyuz rocket launched the fifth and sixth satellites of Europe's Galileo project, a satellite navigation system that will eventually comprise 30 satellites designed to make Europe independent of U.S., Russian, and other GPS systems. Unlike most Soyuz launches, the rocket did not lift off from Baikonur, Kazakhstan, but from Kourou, Europe's space center in French Guiana.  Apparently the launch went off without incident, but it soon became apparent that the two satellites were injected into the wrong orbits. The upper stage of the Soyuz rocket, the Fregat-MT, injected them into elliptical orbits instead of circular ones, making the satellites unusable for GPS navigation.

Initially, blame fell on the Fregat-MT’s outdated navigation system, or on the possibility that its engine malfunctioned. Kourou ground crews dealing with an unfamiliar launcher was also viewed as a possible cause. But it has since been confirmed that the crew that readied the Soyuz for launch was a Russian team. The Izvestia reported on Thursday that according to Roscosmos, the Russian Space Agency, it was likely that a software error caused the two Galileo satellites to be placed in the wrong spots. If true, it would follow on the heels of a software error earlier this year that left the Russian navigation system GLONASS out of commission for 11 hours. The Izvestia article added that software development is a weak spot for Roscosmos because of chronic underfunding.

The October 2011 launch of the first four Galileo satellites—experimental satellites to validate whether the Galileo technology actually worked in space—by Soyuz launchers was a complete success. But it was also the first time that Soyuz launchers were used outside Russia or Kazakhstan. A 28 August article in Le Monde, takes its headline, "We Would Have Done Better by Launching With Ariane," from a quote attributed to the French Coordinator of Galileo, Jean-Yves Le Gall, president of CNES, the French Space Agency.

European Space Agency spokesperson Dominique Detain disagrees: "For the early launches we needed only a middle-class launcher. The first satellites were light, and it made no sense to launch them with an Ariane 5," he told IEEE Spectrum. And the reliability of the Soyuz launchers is high. "They have the best record ever, with 1800 successful launches; and Fregat has been successful for over four years," says Detain.

There is a lot of speculation about how the project will go forward. The two satellites were intended to be part of the actual operational system of 22 satellites, but being in the wrong orbits makes this now impossible. The hydrogen fuel aboard the satellites allows for small orbit corrections, but is insufficient for the drastic orbit change that would be required to make them fully operational.

Le Gall would prefer to switch to Ariane right away, and he believes that this is what will happen, as reports Le Monde.  However this will require an extensive reorganization of the project. According to current plans, six more Soyuz will launch 12 satellites, and the remaining 12 satellites will be placed in orbit by three Ariane 5 launchers.

ESA set up an international inquiry board to ascertain what went wrong during the launch; the group will issue a report on 8 September, says Detain. "They are discussing how to rescue as much as possible of this mission, in a way to make it a "technology" mission," says Detain.  For example, one of the possibilities would be to reprogram the two satellites so that they can operate from a wrong orbit, but this will also require reprogramming the ground segment.  "It will take weeks before we make a decision," concludes Detain. 

The $7.2 billion Galileo project has now seen six years of delays and it is clear that whatever will be done to fix the latest problem will add substantially to this delay.

Medicine's Next Big Mission: Understanding Wellness

human os iconThe bioengineering pioneer Leroy Hood has seen vast changes in medicine over his decades in the biz, in part thanks to his own work on automated DNA sequencing. But he's not much for looking back — he's too busy envisioning a future model of medicine. "Contemporary medicine is all about disease, and not about wellness," he says. Hood says the medical profession must learn to measure and maximize wellness, and he's happy to show the way. 

At the annual meeting of the IEEE Engineering in Medicine and Biology Society, Hood presented his vision for "P4 medicine," which is predictive, preventive, personalized, and participatory. In a keynote speech, he described the 100K Wellness Project he launched this year as president of the Institute for Systems Biology. The ambitious study aims to enroll 100,000 participants and track their biometrics over 20 years (funding permitting). Hood wants to quantify wellness, and also to provide "actionable information" to the participants.

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10 Finalist Teams Announced for Tricorder XPrize

In the Star Trek reality of the 23rd century, a doctor like Leonard "Bones" McCoy can wave his trusty tricorder over a patient's body and get an immediate diagnosis from the device. Now, ten teams of engineers are vying to make such a device available to the consumers of our humble 21st century.

The Qualcomm Tricorder XPrize announced its ten finalist teams yesterday at the annual conference of the IEEE Engineering in Medicine and Biology Society (EMBS). Each team must now get to work on building a consumer-friendly device that can diagnose 15 diseases and measure 5 vital signs. At the EMBS meeting there's been a lot of talk about distributing healthcare technologies, shifting power from doctors to patients, and letting people manage their own care with sensors and data analytics. The Tricorder XPrize expresses this theme neatly with its tagline: "Healthcare in the palm of your hand." 

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Quantum Entanglement Camera Images Object With Photons That Never Come Near It

Conventional imaging devices like cameras and x-ray machines create pictures by detecting photons that interact with the things being imaged. Now researchers have developed a new quantum imaging technique that shines a beam of photons on an object but then, instead of using these photons to form a picture, uses instead a completely different beam that has never come near the object. If this sounds a bit spooky, it is: what connects the two sets of photons and allows this technique to work is the bizarre quantum physics phenomenon known as entanglement.

The advantage of a quantum entanglement camera like this is that you can illuminate an object using photons with a certain wavelength and then use entangled photons with a different wavelength to form the image. The scientists have already begun investigating possible biotechnological applications such as capturing images of sensitive samples that would be destroyed by conventional imaging techniques.

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