New technique offers spray-on solar power

 

It may look more like Junk Yard Wars than high-tech, but U of T researcher Illan Kramer's (pictured) device is the first step towards spray-on solar cells. Pretty soon, powering your tablet could be as simple as wrapping it in cling wrap. That's Illan Kramer's (ECE) hope. Kramer and colleagues have just invented a new way to spray solar cells onto flexible surfaces using miniscule light-sensitive materials known as colloidal quantum dots (CQDs) -- a major step toward making spray-on solar cells easy and cheap to manufacture. "My dream is that one day you'll have two technicians with Ghostbusters backpacks come to your house and spray your roof," said Kramer, a post-doctoral fellow with The Edward S. Rogers Sr. Department of Electrical & Computer Engineering at the University of Toronto and IBM Canada's Research and Development Centre. Solar-sensitive CQDs printed onto a flexible film could be used to coat all kinds of weirdly shaped surfaces, from patio furniture to an airplane's wing. A surface the size of your car's roof wrapped with CQD-coated film would produce enough energy to power three 100-Watt light bulbs -- or 24 compact fluorescents. He calls his system sprayLD, a play on the manufacturing process called ALD, short for atomic layer deposition, in which materials are laid down on a surface one atom-thickness at a time. Until now, it was only possible to incorporate light-sensitive CQDs onto surfaces through batch processing -- an inefficient, slow and expensive assembly-line approach to chemical coating. SprayLD blasts a liquid containing CQDs directly onto flexible surfaces, such as film or plastic, like printing a newspaper by applying ink onto a roll of paper. This roll-to-roll coating method makes incorporating solar cells into existing manufacturing processes much simpler. In two recent papers in the journals Advanced Materials and Applied Physics Letters, Kramer showed that the sprayLD method can be used on flexible materials without any major loss in solar-cell efficiency. Kramer built his sprayLD device using parts that are readily available and rather affordable -- he sourced a spray nozzle used in steel mills to cool steel with a fine mist of water, and a few regular air brushes from an art store. "This is something you can build in a Junkyard Wars fashion, which is basically how we did it," said Kramer. "We think of this as a no-compromise solution for shifting from batch processing to roll-to-roll." "As quantum dot solar technology advances rapidly in performance, it's important to determine how to scale them and make this new class of solar technologies manufacturable," said Professor Ted Sargent (ECE), vice dean, research in the Faculty of Applied Science & Engineering at University of Toronto and Kramer's supervisor. "We were thrilled when this attractively manufacturable spray-coating process also led to superior performance devices showing improved control and purity." In a third paper in the journal ACS Nano, Kramer and his colleagues used IBM's BlueGeneQ supercomputer to model how and why the sprayed CQDs perform just as well as -- and in some cases better than -- their batch-processed counterparts. This work was supported by the IBM Canada Research and Development Centre, and by King Abdullah University of Science and Technology.

Diamond Magnetometer Breaks Sensitivity Records

 

Diamonds are a physicist’s best friend–when it comes to measuring the tiniest magnetic fields. Back in 1896, a young physicist called Pieter Zeeman was fired for carrying out an experiment against the specific wishes of his laboratory supervisor. Despite the consequences, the experiment led to a remarkable discovery that changed Zeeman’s life. The experiment involved measuring the light emitted by elements placed in a powerful magnetic field. When he did this, Zeeman discovered that the spectral lines were split by the field. In 1902, he was awarded the Nobel Prize in physics for this discovery which is now known as the Zeeman effect. It is particularly useful for measuring magnetic fields at a distance. For example, astrophysicists use it to map variations in the magnetic field on the sun. But it can also be used to measure fields on a much smaller scale. In theory, the effect could be used to observe the influence of a magnetic field on a single atom. While they have not got quite this far, Thomas Wolf at the University of Stuttgart in Germany and a few pals, have come pretty close. These guys have used the spectra from nitrogen atoms embedded in diamond to build perhaps the most sensitive magnetometer ever made. They say their new device could soon be capable of measuring the magnetic field associated with protons. First, some background about magnetometers. In recent years, physicists have made increasingly sensitive magnetometers using a variety of different techniques. One problem they all come up against is that magnetic fields decay very quickly with distance, as 1/r^3. That means the size of the sensor has an important impact on what it can detect, since magnetic field can change significantly throughout the volume of the sensor. So an important task is to make magnetometers as small as possible. That’s where diamond comes in. Diamond is a three-dimensional crystal made of carbon. However, when a carbon atom in the structure is replaced with nitrogen, this produces an additional unbound electron. When this electron is excited with laser light, it then fluoresces at a frequency that depends on its environment. A magnetic field in particular can change this frequency, via the Zeeman effect, making nitrogen defects in diamond a promising type of magnetometer. Of course, addressing a single atom in such a structure and recording its fluorescence accurately is a tricky business. So Wolf and co use an entire ensemble of nitrogen defects in a volume of diamond occupying just a fraction of a cubic millimetre. They estimate that this contains several billion nitrogen atoms. Although a centre of this size is many orders of magnitude larger than an individual atom, it produces a fluorescent signal that is much easier to measure. That makes the device practical. Even at this size, the magnetometer is one of the smallest ever made. To find out how sensitive, Wolf and co put the device through its paces, carefully eliminating noise at every step. The results are impressive. The team eventually measured a field strength of only 100 femtoTesla.  That’s comparable with the most sensitive magnetometers on the planet. And they think they can do even better with relatively straightforward improvements that should increase the sensitivity by two orders of magnitude. But here’s the thing: what’s unique about this device is that it is both small and sensitive, a combination that has never been achieved before. That makes this device a kind of record breaker. It can measure magnetic field strengths in tiny volumes that have never been accessible before. In other words, it opens up magnetic field strength detection on an entirely new scale using a solid state device that works at room temperature. One goal in this area is to measure the magnetic fields of protons in water. The sensitivity of this device looks to make this possible. “This value itself allows for detection of proton spins in a microscopically resolvable volume in less than one second,” says Wolf and co. Magnetometers are used in a wide range of applications, ranging from mineral exploration and archaeology to weapon systems positioning and heartbeat monitors. So a robust, highly sensitive solid-state device that works at room temperature is likely to come in handy. Zeeman would have been impressed. Ref: arxiv.org/abs/1411.6553  A Subpicotesla Diamond Magnetometer

Computers that teach by example: New computer system enables pattern-recognition systems to convey what they learn to humans

 

Computers are good at identifying patterns in huge data sets. Humans, by contrast, are good at inferring patterns from just a few examples. In a paper appearing at the Neural Information Processing Society's conference next week, MIT researchers present a new system that bridges these two ways of processing information, so that humans and computers can collaborate to make better decisions. The system learns to make judgments by crunching data but distills what it learns into simple examples. In experiments, human subjects using the system were more than 20 percent better at classification tasks than those using a similar system based on existing algorithms. "In this work, we were looking at whether we could augment a machine-learning technique so that it supported people in performing recognition-primed decision-making," says Julie Shah, an assistant professor of aeronautics and astronautics at MIT and a co-author on the new paper. "That's the type of decision-making people do when they make tactical decisions -- like in fire crews or field operations. When they're presented with a new scenario, they don't do search the way machines do. They try to match their current scenario with examples from their previous experience, and then they think, 'OK, that worked in a previous scenario,' and they adapt it to the new scenario." In particular, Shah and her colleagues -- her student Been Kim, whose PhD thesis is the basis of the new paper, and Cynthia Rudin, an associate professor of statistics at the MIT Sloan School of Management -- were trying to augment a type of machine learning known as "unsupervised." In supervised machine learning, a computer is fed a slew of training data that's been labeled by humans and tries to find correlations -- say, those visual features that occur most frequently in images labeled "car." In unsupervised machine learning, on the other hand, the computer simply looks for commonalities in unstructured data. The result is a set of data clusters whose members are in some way related, but it may not be obvious how. Balancing act The most common example of unsupervised machine learning is what's known as topic modeling, in which a system clusters documents together according to their most characteristic words. Since the data is unlabeled, the system can't actually deduce the topics of the documents. But a human reviewing its output would conclude that, for instance, the documents typified by the words "jurisprudence" and "appellate" are legal documents, while those typified by "tonality" and "harmony" are music-theory papers. The MIT researchers made two major modifications to the type of algorithm commonly used in unsupervised learning. The first is that the clustering was based not only on data items' shared features, but also on their similarity to some representative example, which the researchers dubbed a "prototype." The other is that rather than simply ranking shared features according to importance, the way a topic-modeling algorithm might, the new algorithm tries to winnow the list of features down to a representative set, which the researchers dubbed a "subspace." To that end, the algorithm imposes a penalty on subspaces that grow too large. So when it's creating its data clusters, it has to balance three sometimes-competing objectives: similarity to prototype, subspace size, and clear demarcations between clusters. "You have to pick a good prototype to describe a good subspace," Kim explains. "At the same time, you have to pick the right subspace such that the prototype makes sense. So you're doing it all simultaneously." The researchers' first step was to test their new algorithm on a few classic machine-learning tasks, to make sure that the added constraints didn't impair its performance. They found that on most tasks, it performed as well as its precursor, and on a few, it actually performed better. Shah believes that that could be because the prototype constraint prevents the algorithm from assembling feature lists that contain internal contradictions. Suppose, for instance, that an unsupervised-learning algorithm was trying to characterize voters in a population. A plurality of the voters might be registered as Democrats, but a plurality of Republicans may have voted in the last primary. The conventional algorithm might then describe the typical voter as a registered Democrat who voted in the last Republican primary. The prototype constraint makes that kind of result very unlikely, since no single voter would match its characterization. Road test Next, the researchers conducted a set of experiments to determine whether prototype-based machine learning could actually improve human decision-making. Kim culled a set of recipes from an online database in which they had already been assigned categories -- such as chili, pasta, and brownies -- and distilled them to just their ingredient lists. Then she fed the lists to both a conventional topic-modeling algorithm and the new, prototype-constrained algorithm. For each category, the new algorithm found a representative example, while the conventional algorithm produced a list of commonly occurring ingredients. Twenty-four subjects were then given 16 new ingredient lists each. Some of the lists were generated by the new algorithm and some by the conventional algorithm, and the assignment was random. With lists produced by the new algorithm, subjects were successful 86 percent of the time, while with lists produced by the conventional algorithm, they were successful 71 percent of the time. "I think this is a great idea that models the machine learning and the interface with users appropriately," says Ashutosh Saxena, an assistant professor of computer science at Cornell University. Saxena leads a research project called Robo Brain, which uses machine learning to comb the Internet and model the type of common-sense associations that a robot would need to navigate its environment. "In Robo Brain, the machine-learning algorithm is trying to learn something, and it may not be able to do things properly, so it has to show what it has learned to the users to get some feedback so that it can improve its learning," Saxena says. "We would be very interested in using such a technique to show the output of Robo Brain project to users."

45-year physics mystery shows a path to quantum transistors

 

Samarium hexaboride, abbreviated SmB6, is a compound made of the metal samarium and the rare metalloid boron. University of Michigan researchers have confirmed its unusual electrical properties and shown how it could advance the development of next-generation transistors for quantum computers. An odd, iridescent material that's puzzled physicists for decades turns out to be an exotic state of matter that could open a new path to quantum computers and other next-generation electronics. Physicists at the University of Michigan have discovered or confirmed several properties of the compound samarium hexaboride that raise hopes for finding the silicon of the quantum era. They say their results also close the case of how to classify the material--a mystery that has been investigated since the late 1960s. The researchers provide the first direct evidence that samarium hexaboride, abbreviated SmB6, is a topological insulator. Topological insulators are, to physicists, an exciting class of solids that conduct electricity like a metal across their surface, but block the flow of current like rubber through their interior. They behave in this two-faced way despite that their chemical composition is the same throughout. The U-M scientists used a technique called torque magnetometry to observe tell-tale oscillations in the material's response to a magnetic field that reveal how electric current moves through it. Their technique also showed that the surface of samarium hexaboride holds rare Dirac electrons, particles with the potential to help researchers overcome one of the biggest hurdles in quantum computing. These properties are particularly enticing to scientists because SmB6 is considered a strongly correlated material. Its electrons interact more closely with one another than most solids. This helps its interior maintain electricity-blocking behavior. This deeper understanding of samarium hexaboride raises the possibility that engineers might one day route the flow of electric current in quantum computers like they do on silicon in conventional electronics, said Lu Li, assistant professor of physics in the College of Literature, Science, and the Arts and a co-author of a paper on the findings published in Science. "Before this, no one had found Dirac electrons in a strongly correlated material," Li said. "We thought strong correlation would hurt them, but now we know it doesn't. While I don't think this material is the answer, now we know that this combination of properties is possible and we can look for other candidates." The drawback of samarium hexaboride is that the researchers only observed these behaviors at ultracold temperatures. Quantum computers use particles like atoms or electrons to perform processing and memory tasks. They could offer dramatic increases in computing power due to their ability to carry out scores of calculations at once. Because they could factor numbers much faster than conventional computers, they would greatly improve computer security. In quantum computers, "qubits" stand in for the 0s and 1s of conventional computers' binary code. While a conventional bit can be either a 0 or a 1, a qubit could be both at the same time--only until you measure it, that is. Measuring a quantum system forces it to pick one state, which eliminates its main advantage. Dirac electrons, named after the English physicist whose equations describe their behavior, straddle the realms of classical and quantum physics, Li said. Working together with other materials, they could be capable of clumping together into a new kind of qubit that would change the properties of a material in a way that could be measured indirectly, without the qubit sensing it. The qubit could remain in both states. While these applications are intriguing, the researchers are most enthusiastic about the fundamental science they've uncovered. "In the science business you have concepts that tell you it should be this or that and when it's two things at once, that's a sign you have something interesting to find," said Jim Allen, an emeritus professor of physics who studied samarium hexaboride for 30 years. "Mysteries are always intriguing to people who do curiosity-driven research." Allen thought for years that samarium hexaboride must be a flawed insulator that behaved like a metal at low temperatures because of defects and impurities, but he couldn't align that with all of its other properties. "The prediction several years ago about it being a topological insulator makes a lightbulb go off if you're an old guy like me and you've been living with this stuff your whole life," Allen said. In 2010, Kai Sun, assistant professor of physics at U-M, led a group that first posited that SmB6 might be a topological insulator. He and Allen were also involved in seminal U-M experiments led by physics professor Cagliyan Kurdak in 2012 that showed indirectly that the hypothesis was correct. "But the scientific community is always critical," Sun said. "They want very strong evidence. We think this experiment finally provides direct proof of our theory."

Chemicals released during natural gas extraction may harm reproduction, development

 

December 5, 2014 University of Missouri-Columbia Unconventional oil and gas operations combine directional drilling and hydraulic fracturing to release natural gas from rock. Discussions have centered on potential air and water pollution from chemicals and how they affect the more than 15 million Americans living within one mile of UOG operations. Now, a researcher has conducted the largest review of research centered on fracking byproducts and their effects on human reproductive and developmental health. Unconventional oil and gas (UOG) operations combine directional drilling and hydraulic fracturing, or "fracking," to release natural gas from underground rock. Recent discussions have centered on potential air and water pollution from chemicals used in these processes and how it affects the more than 15 million Americans living within one mile of UOG operations. Now, Susan C. Nagel, a researcher with the University of Missouri, and national colleagues have conducted the largest review to date of research centered on fracking byproducts and their effects on human reproductive and developmental health. They determined that exposure to chemicals released in fracturing may be harmful to human health in men, women and children and recommend further scientific study. "We examined more than 150 peer-reviewed studies reporting on the effects of chemicals used in UOG operations and found evidence to suggest there is cause for concern for human health," said Nagel. "Further, we found that previous studies suggest that adult and early life exposure to chemicals associated with UOG operations can result in adverse reproductive health and developmental defects in humans." The "weight of evidence" review of scientific literature and peer-reviewed publications, where studies are examined thoroughly for patterns and links, included international studies that focused on UOG chemicals. Reviewers say these chemicals have been measured in air and water near UOG operations, and have been associated with harmful effects in both animals and humans. The reviewers concluded that exposure to air and water pollution caused by UOG operations may be linked to health concerns including infertility, miscarriage, impaired fetal growth, birth defects and reduced semen quality. "There are far fewer human studies than animal studies; however, taken together, the studies did show that humans can be harmed by these chemicals released from fracking," Nagel said. "There is strong evidence of decreased semen quality in men, higher miscarriages in women and increased risk of birth defects in children. There is a striking need for continued research on UOG processes and chemicals and the health outcomes in people." Nagel, an associate professor of obstetrics, gynecology and women's health in the School of Medicine, and adjunct associate professor of biological sciences in the College of Arts and Science at MU, conducted the review with colleagues from the University of Missouri as well as researchers at the Institute for Health and the Environment and the Center for Environmental Health. Story Source: The above story is based on materials provided by University of Missouri-Columbia. Note: Materials may be edited for content and length. Journal Reference: Ellen Webb, Sheila Bushkin-Bedient, Amanda Cheng, Christopher D. Kassotis, Victoria Balise, Susan C. Nagel. Developmental and reproductive effects of chemicals associated with unconventional oil and natural gas operations. Reviews on Environmental Health, 2014; 29 (4) DOI: 10.1515/reveh-2014-0057

5 Quick Phone Charging Hacks For When You're Short on Time

 

Being Short on Time Doesn't Mean You Have to Be Short on Battery paolomartinezphotography/Moment Open/Getty Images If keeping your smartphone charged is a challenge in everyday life, it's even worse when you're traveling. Long days in transit or out exploring a new city will make that battery icon start flashing before you know it, especially when you're relying on your phone for navigation, entertainment and more. Even worse, you've often only got limited time to get some juice in it – a short layover, coffee break in a café or quick return to the hotel room to freshen up – before you're out of reach of a charging cable for another few hours. Here are five hacks for getting more charge in your phone when you're short on time. Charge From a Wall Socket Always charge from a wall socket rather than a laptop when you're in a hurry. All else being equal, it takes longer – in some cases, an extra hour or more – to charge a smartphone over USB than from the wall. If your charger didn't come with an adapter to plug it into the wall, they're small and cost as little as $10 for a good one. Use a High-Power USB Adapter Speaking of good wall to USB adapters, be sure to use one that can put out as much power as your smartphone can handle. For example, the iPhone 6 ships with a 1 amp power adapter – but it can actually handle the 2.1amp charger from an iPad just fine, and will charge much faster if you use one. By contrast, if you use an old 0.5 amp USB adapter you've got lying around, your phone might not even charge at all. You can't damage your phone by doing this – the number on the adapter is a maximum rating, but it will only send as much power as your device actually requests. Check the specifications of the adapter you're planning to use, and get a better one if you need to. The small extra cost is well worth the substantial time saving. Charge Your Battery Pack Instead Certain portable battery packs can charge much faster than the smartphone or tablet you'll be connecting them to. The Pronto battery, for instance, boasts of being able to fully recharge an iPhone 5 after being plugged into the wall for just 5-15 minutes depending on the model. If you leave it connected for an hour, it'll have enough juice to charge that same iPhone between three and nine times! Just plug the battery into the wall while you're waiting to board or taking a shower, then slip it into your pocket and charge your phone up once you're on the move again. Put Your Phone in Flight Mode All of those useful features on your smartphone chew up battery life, but the wi-fi and (especially) cellular radios are one of the biggest power hogs of all. To make sure you get as much juice as possible into your phone in a hurry, put it in flight mode while you're charging. If you're waiting for a call or text, at least turn off mobile data and wi-fi to save a little battery. Stop Checking the Charge Level The only thing that kills your battery faster than cell data is that big, bright screen – so stop looking at it while you're charging the phone! Every little bit helps, and continually turning on the display to check the battery percentage is only going to make matters worse.

ER docs can treat pediatric pain without a needle

 

Children in emergency departments can safely be treated for pain from limb injuries using intranasal ketamine, a drug more typically used for sedation, according to the results of the first randomized, controlled trial comparing intranasal analgesics in children in the emergency department. The study was published online last month in Annals of Emergency Medicine ("The PICHFORK (Pain in Children Fentanyl OR Ketamine) Trial: A Randomized Controlled Trial Comparing Intranasal Ketamine and Fentanyl for the Relief of Moderate to Severe Pain in Children with Limb Injuries"). "This is great news for emergency physicians and their young patients, especially those who may not tolerate other intranasal pain medications such as fentanyl," said lead study author Professor Andis Graudins, MD, of Monash University in Clayton, Victoria, Australia. "For children in pain and distress, the option of treating their pain without a needle is a huge benefit as well. The intranasal option using fentanyl is accepted already for children, but the safe use of ketamine is new." Researchers compared pain relief resulting from ketamine and fentanyl, both delivered intranasally, for children 3 to 13 years old whose pain from isolated limb injuries registered seven or higher on a 10 point scale. Median baseline pain rating was eight out of ten. After 30 minutes, the median reductions in pain for ketamine were 4.45 and for fentanyl were 4.0. The pain reduction was maintained in both groups at 60 minutes. Satisfaction for ketamine was slightly higher at 83 percent. Fentanyl had a 72 percent satisfaction rating. Adverse events were reported more frequently for ketamine (78 percent of patient) than for fentanyl (40 percent of patients), but they were all mild (dizziness or drowsiness were common). "Ketamine is a great alternative for injured children in the ER who may not be able to tolerate opiates, like fentanyl," said Prof. Graudins. "And being able to deliver pain-relief with minimal upset, such as that triggered in some children by even the sight of needles, is a great boon to our youngest patients." Story Source: The above story is based on materials provided by American College of Emergency Physicians. Note: Materials may be edited for content and length. Journal Reference: Andis Graudins, Robert Meek, Dianna Egerton-Warburton, Ed Oakley, Robert Seith. The PICHFORK (Pain in Children Fentanyl or Ketamine) Trial: A Randomized Controlled Trial Comparing Intranasal Ketamine and Fentanyl for the Relief of Moderate to Severe Pain in Children With Limb Injuries. Annals of Emergency Medicine, 2014; DOI: 10.1016/j.annemergmed.2014.09.024

Social networking during a campus emergency

 

December 5, 2014 Inderscience Publishers Emergencies at educational establishments are on the increase in recent years and campus officials are beginning to recognize that better communications with their students are now needed. Researchers now describe how social networking sites might be exploited when an emergency situation arises to help safeguard students as well as keeping those not directly involved in the situation informed of events. Emergencies at educational establishments are on the increase in recent years and campus officials are beginning to recognize that better communications with their students are now needed. Writing in the International Journal of Business Information Systems, US researchers describe how social networking sites might be exploited when an emergency situation arises to help safeguard students as well as keeping those not directly involved in the situation informed of events. The same insights might be applied in the business environment too. Wencui Han of the Department of Management Science and Systems at the University at Buffalo, New York and colleagues, explain how in the last two decades criminal incidents such as shootings on campus, assaults and robberies, natural disasters including tornadoes, hurricanes and snow storms and disease outbreaks have put students and staff at risk. While sensationalist reporting in the media of some events increases anxiety for all those in education, it is true that there has been an increase in frequency of lethal shootings in recent years, for instance. The occurrence of such events, whether criminal, environmental or health related seems random and, as such, there is no predicting when the next emergency situation might arise. Han and colleagues argue that campus officials need to have their response plans in place and that such plans should, in the era of almost ubiquitous mobile connectivity and social networking, accommodate these new communications tools. Of course, campus administrators have already adopted a variety of emergency notification technologies, including campus radio and TV, warning sirens and even text and email announcements for their students and staff. Each of these channels should continue to be employed, but Han and colleagues argue that they all have their limitations and that social networking sites might counter such shortcomings for today's always-connected students. One might imagine that almost every student on a US campus has a Facebook page, while not all will be regular listeners to the campus radio station nor viewers of its TV channel. Moreover, it is common that Facebook users are compelled to check for new notifications on their smart phones and other devices regularly. The team explains that there will be little cost to establishing a social networking presence via Facebook or Twitter that could be promoted to students on enrolment and accessing the page or updates encouraged throughout campus life. These outlets, which might also include the likes of LinkedIn and other tools, could be actively maintained to provide additional useful information and guidance for students during normal times as well as during and after disasters or emergency situations. Story Source: The above story is based on materials provided by Inderscience Publishers. Note: Materials may be edited for content and length. Journal Reference: Han, W., Ada, S., Sharman, R., Gray, R.H. and Simha, A. Factors impacting the adoption of social network sites for emergency notification purposes in universities. Int. J. Business Information Systems, DOI: 2015; Vol. 18, No. 1, pp.85-106.