Wednesday, November 7th, 2012

Time	Event
5:00a	New method could help communities plan for climate risk Climate scientists cannot attribute any single weather event — whether a drought, wildfire or extreme storm — to climate change. But extreme events, such as Hurricane Sandy, are glimpses of the types of occurrences the world could be more vulnerable to in the future. As the devastation left by Sandy continues to reverberate, decision-makers at every level are asking: How can we be better prepared? MIT researchers have developed a new tool to help policymakers, city planners and others see the possible local effects of climate change. Its regional projections of climate trends — such as long-term temperature and precipitation changes — allow local planners to evaluate risks, and how these risks could shape crops, roads and energy infrastructure. “As we see more extreme events like Sandy, the importance of assessing regional impacts grows,” says lead researcher Adam Schlosser, assistant director for science research at MIT’s Joint Program on the Science and Policy of Global Change. “Our approach helps decision- and policymakers balance the risks … so they can better prepare their communities for future impacts climate change might bring.” For example, Schlosser says, if a community is planning to build a bridge, it should look at — and plan for — the expected magnitude of flooding in 2050. “In areas devastated by Sandy, the rebuilding of lost property and infrastructure will come at considerable cost and effort,” Schlosser says. “But should we rebuild to better prepare for future storms like these? Or should we prepare for stronger and/or more frequent storms? There remains considerable uncertainty in these projections and that implies risk. Our technique has been developed with these questions in mind.” Schlosser’s research partner, Ken Strzepek, a research scientist at the Joint Program on the Science and Policy of Global Change, notes policymakers are now often given little more than a set of extreme circumstances to consider. “Policymakers don’t like extremes or worst-case scenarios,” Strzepek says, “because they can’t afford to plan for the worst-case scenarios. They like to see what is the likelihood of different outcomes. That’s what we’re giving them.” Getting results In this new method, the researchers quantify the likelihood of particular outcomes and add socioeconomic data, different emission levels and varying degrees of uncertainty. Their technique combines climate-model projections and analysis from the Coupled Model Intercomparison Project used by the Intergovernmental Panel on Climate Change, and the MIT Integrated Global System Modeling framework. The MIT framework is itself a combined computer model that integrates an economic, human system with a natural, earth system. “This approach allows us to widen the scope and flexibility of climate analysis,” Schlosser says. “It provides us with efficient capabilities to determine climate-change risks.” The initial study using this approach — accepted by the Journal of Climate and available on the journal’s website — compares a business-as-usual case with a scenario that reduces emissions. The researchers find that lowering emissions reduces the odds of regional warming and precipitation changes. In fact, for many places, the likelihood of the most extreme warming from the business-as-usual case could be eliminated almost entirely. The study finds diverse climate-change outcomes: southern and western Africa, the Himalayan region, and the area around Hudson Bay in Canada are expected to warm the most; southern Africa and western Europe see the greatest chance of drier conditions. Meanwhile, the Amazon and northern Siberia may become wetter. Putting the method to work Schlosser and Strzepek are pursuing partnerships with communities to put their method to work. But while it’s important for every community to begin building climate adaptation into their infrastructure plans, developing countries could reap the greatest benefits. Malcolm Smart, senior economic adviser for the U.K. Department for International Development, who was not involved in this research, says, “This is not only an innovative and multidisciplinary approach to the problem of deep uncertainty, but also a potentially very valuable tool to help vulnerable developing countries cut the cost of damages from climate change.” Strzepek explains why: In the United States, infrastructure plans are designed based on a high standard of risk, while in developing countries projects are typically built to a lower standard of risk. “But if we find that [a developing country] will see greater flooding, and if we’re fairly certain of this, then they would save money in the long run if they built roads to withstand those flooding events,” Strzepek says. Schlosser and Strzepek traveled to Finland earlier this fall to present their research at a United Nations University-World Institute for Development Economics Research conference. They’ve partnered with this organization to inform developing countries of this new tool for assessing climate change. “Our approach allows decision-makers to cut down on the level of risk they’re taking when allocating their limited funds to development projects,” Schlosser says. “This can help them see where there are economic benefits to taking a risk-averse approach today, before the damage is done.” (Comment on this)
2:00p	Stronger than a speeding bullet Providing protection against impacts from bullets and other high-speed projectiles is more than just a matter of brute strength. While traditional shields have been made of bulky materials such as steel, newer body armor made of lightweight material such as Kevlar has shown that thickness and weight are not necessary for absorbing the energy of impacts. Now, a new study by researchers at MIT and Rice University has shown that even lighter materials may be capable of doing the job just as effectively. The key is to use composites made of two or more materials whose stiffness and flexibility are structured in very specific ways — such as in alternating layers just a few nanometers thick. The research team produced miniature high-speed projectiles and measured the effects they had on the impact-absorbing material. The results of the research are reported in the journal Nature Communications, in a paper co-authored by former postdoc Jae-Hwang Lee, now a research scientist at Rice; postdoc Markus Retsch; graduate student Jonathan Singer; Edwin Thomas, a former MIT professor who is now at Rice; graduate student David Veysset; former graduate student Gagan Saini; former postdoc Thomas Pezeril, now on the faculty at Université du Maine, in Le Mans, France; and chemistry professor Keith Nelson. The experimental work was conducted at MIT’s Institute for Soldier Nanotechnologies. The team developed a self-assembling polymer with a layer-cake structure: rubbery layers, which provide resilience, alternating with glassy layers, which provide strength. They then developed a method for shooting glass beads at the material at high speed by using a laser pulse to rapidly evaporate a layer of material just below its surface. Though the beads were tiny — just millionths of a meter in diameter — they were still hundreds of times larger than the layers of the polymer they impacted: big enough to simulate impacts by larger objects, such as bullets, but small enough so the effects of the impacts could be studied in detail using an electron microscope. Seeing the layers Structured polymer composites have previously been tested for possible impact-protection applications. But nobody had found a way to study exactly how they work — so there was no way to systematically search for improved combinations of materials. The new techniques developed by the MIT and Rice researchers could provide such a method. Their work could accelerate progress on materials for applications in body and vehicle armor; shielding to protect satellites from micrometeorite impacts; and coatings for jet engine turbine blades to protect from high-speed impacts by sand or ice particles. The methods the team developed for producing laboratory-scale high-speed impacts, and for measuring the impacts’ effects in a precise way, “can be an extremely useful quantitative tool for the development of protective nanomaterials,” says Lee, the lead author of the paper, who did much of this research while in MIT’s Department of Materials Science and Engineering. “Our work presents some valuable insights to understand the contribution” of the nanoscale structure to the way such materials absorb an impact, he says. Because the layered material has such a predictable, ordered structure, the effects of the impacts are easily quantified by observing distortions in cross-section. “If you want to test out how ordered systems will behave,” Singer says, “this is the perfect structure for testing.” Which direction works best The team found that when the projectiles hit the layers head-on, they absorbed the impact 30 percent more effectively than in an edge-on impact. That information may have immediate relevance for the design of improved protective materials. Nelson has spent years developing techniques that use laser pulses to observe and quantify nanoscale shockwaves — techniques that were adapted for this research with the help of Lee, Veysset and other team members. Ideally, in future research, the team hopes to be able to observe the passage of projectiles in real time in order to get a better understanding of the sequence of events as the impacted material undergoes distortion and damage, Nelson says. In addition, now that the experimental method has been developed, the researchers would like to investigate different materials and structures to see how these respond to impacts, Nelson says: varying the composition and thickness of layers, or using different structures. Donald Shockey, director of the Center for Fracture Physics at SRI International, a nonprofit research institute in Menlo Park, Calif., says, “It’s a novel and useful approach that will provide needed understanding of the mechanisms governing how a projectile penetrates protective vests and helmets.” He adds that these results “provide the data required to develop and validate computational models” to predict the behavior of impact-protection materials and to develop new, improved materials. “The key to developing materials with better impact resistance is to understand deformation and failure behavior at the tip of an advancing projectile,” Shockey says. “We need to be able to see that.” The work was supported by the U.S. Army Research Office. (Comment on this)
4:51p	Medical devices powered by the ear itself Deep in the inner ear of mammals is a natural battery — a chamber filled with ions that produces an electrical potential to drive neural signals. In today’s issue of the journal Nature Biotechnology, a team of researchers from MIT, the Massachusetts Eye and Ear Infirmary (MEEI) and the Harvard-MIT Division of Health Sciences and Technology (HST) demonstrate for the first time that this battery could power implantable electronic devices without impairing hearing. The devices could monitor biological activity in the ears of people with hearing or balance impairments, or responses to therapies. Eventually, they might even deliver therapies themselves. In experiments, Konstantina Stankovic, an otologic surgeon at MEEI, and HST graduate student Andrew Lysaght implanted electrodes in the biological batteries in guinea pigs’ ears. Attached to the electrodes were low-power electronic devices developed by MIT’s Microsystems Technology Laboratories (MTL). After the implantation, the guinea pigs responded normally to hearing tests, and the devices were able to wirelessly transmit data about the chemical conditions of the ear to an external receiver. “In the past, people have thought that the space where the high potential is located is inaccessible for implantable devices, because potentially it’s very dangerous if you encroach on it,” Stankovic says. “We have known for 60 years that this battery exists and that it’s really important for normal hearing, but nobody has attempted to use this battery to power useful electronics.” The ear converts a mechanical force — the vibration of the eardrum — into an electrochemical signal that can be processed by the brain; the biological battery is the source of that signal’s current. Located in the part of the ear called the cochlea, the battery chamber is divided by a membrane, some of whose cells are specialized to pump ions. An imbalance of potassium and sodium ions on opposite sides of the membrane, together with the particular arrangement of the pumps, creates an electrical voltage. Although the voltage is the highest in the body (outside of individual cells, at least), it’s still very low. Moreover, in order not to disrupt hearing, a device powered by the biological battery can harvest only a small fraction of its power. Low-power chips, however, are precisely the area of expertise of Anantha Chandrakasan’s group at MTL. The MTL researchers — Chandrakasan, who heads MIT’s Department of Electrical Engineering and Computer Science; his former graduate student Patrick Mercier, who’s now an assistant professor at the University of California at San Diego; and Saurav Bandyopadhyay, a graduate student in Chandrakasan’s group — equipped their chip with an ultralow-power radio transmitter: After all, an implantable medical monitor wouldn’t be much use if there were no way to retrieve its measurements. But while the radio is much more efficient than those found in cellphones, it still couldn’t run directly on the biological battery. So the MTL chip also includes power-conversion circuitry — like that in the boxy converters at the ends of many electronic devices’ power cables — that gradually builds up charge in a capacitor. The voltage of the biological battery fluctuates, but it would take the control circuit somewhere between 40 seconds and four minutes to amass enough charge to power the radio. The frequency of the signal was thus itself an indication of the electrochemical properties of the inner ear. To reduce its power consumption, the control circuit had to be drastically simplified, but like the radio, it still required a higher voltage than the biological battery could provide. Once the control circuit was up and running, it could drive itself; the problem was getting it up and running. The MTL researchers solve that problem with a one-time burst of radio waves. “In the very beginning, we need to kick-start it,” Chandrakasan says. “Once we do that, we can be self-sustaining. The control runs off the output.” Stankovic, who still maintains an affiliation with HST, and Lysaght implanted electrodes attached to the MTL chip on both sides of the membrane in the biological battery of each guinea pig’s ear. In the experiments, the chip itself remained outside the guinea pig’s body, but it’s small enough to nestle in the cavity of the middle ear. Cliff Megerian, chairman of otolaryngology at Case Western Reserve University and University Hospitals Case Medical Center, says that he sees three possible applications of the researchers’ work: in cochlear implants, diagnostics and implantable hearing aids. “The fact that you can generate the power for a low voltage from the cochlea itself raises the possibility of using that as a power source to drive a cochlear implant,” Megerian says. “Imagine if we were able to measure that voltage in various disease states. There would potentially be a diagnostic algorithm for aberrations in that electrical output.” “I’m not ready to say that the present iteration of this technology is ready,” Megerian cautions. But he adds that, “If we could tap into the natural power source of the cochlea, it could potentially be a driver behind the amplification technology of the future.” The work was funded in part by the Focus Center Research Program, the National Institute on Deafness and Other Communication Disorders, and the Bertarelli Foundation. (Comment on this)

<< Previous Day

2012/11/07 [Calendar]

Next Day >>