Engineers design ‘living materials’: Hybrid materials combine bacterial cells with nonliving elements that emit light

Inspired by natural materials such as bone — a matrix of minerals and other substances, including living cells — MIT engineers have coaxed bacterial cells to produce biofilms that can incorporate nonliving materials, such as gold nanoparticles and quantum dots.These “living materials” combine the advantages of live cells, which respond to their environment, produce complex biological molecules, and span multiple length scales, with the benefits of nonliving materials, which add functions such as conducting electricity or emitting light.The new materials represent a simple demonstration of the power of this approach, which could one day be used to design more complex devices such as solar cells, self-healing materials, or diagnostic sensors, says Timothy Lu, an assistant professor of electrical engineering and biological engineering. Lu is the senior author of a paper describing the living functional materials in the March 23 issue of Nature Materials.”Our idea is to put the living and the nonliving worlds together to make hybrid materials that have living cells in them and are functional,” Lu says. “It’s an interesting way of thinking about materials synthesis, which is very different from what people do now, which is usually a top-down approach.”The paper’s lead author is Allen Chen, an MIT-Harvard MD-PhD student. Other authors are postdocs Zhengtao Deng, Amanda Billings, Urartu Seker, and Bijan Zakeri; recent MIT graduate Michelle Lu; and graduate student Robert Citorik.Self-assembling materialsLu and his colleagues chose to work with the bacterium E. coli because it naturally produces biofilms that contain so-called “curli fibers” — amyloid proteins that help E. coli attach to surfaces. Each curli fiber is made from a repeating chain of identical protein subunits called CsgA, which can be modified by adding protein fragments called peptides. These peptides can capture nonliving materials such as gold nanoparticles, incorporating them into the biofilms.By programming cells to produce different types of curli fibers under certain conditions, the researchers were able to control the biofilms’ properties and create gold nanowires, conducting biofilms, and films studded with quantum dots, or tiny crystals that exhibit quantum mechanical properties. They also engineered the cells so they could communicate with each other and change the composition of the biofilm over time.First, the MIT team disabled the bacterial cells’ natural ability to produce CsgA, then replaced it with an engineered genetic circuit that produces CsgA but only under certain conditions — specifically, when a molecule called AHL is present. This puts control of curli fiber production in the hands of the researchers, who can adjust the amount of AHL in the cells’ environment. …

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Simple changes to homework improved student learning

A new study offers evidence that simple and inexpensive changes to existing courses can help students learn more effectively.The study from Rice University and Duke University found that making a few changes to homework assignments in an upper-level undergraduate engineering course at Rice led to improved scores on exams. The study appears this week in the journal Educational Psychology Review.The findings by a team from Rice’s Center for Digital Learning and Scholarship and Duke’s Department of Psychology and Neuroscience demonstrate how technology and cognitive science can be combined to develop inexpensive but effective educational changes that required no changes to course curriculum.”Based on laboratory studies, we know a lot about how people learn,” said lead author Andrew Butler, a postdoctoral researcher at Duke. “To test how well some of those cognitive science principles worked in a classroom, we made subtle changes to standard homework practice.””The results exceeded everyone’s expectations,” said Rice co-author Richard Baraniuk, the instructor of the upper-level “signals and systems” engineering course where the experiment took place. “These simple changes produced a larger effect than the average improvement for classroom interventions that require a complete overhaul of curricula and/or teaching methods.”In the study, students switched back and forth from week to week between two different styles of homework. One style, which followed the standard practice that Baraniuk has used for years, consisted of one homework assignment per week, which was graded and returned the following week. The second style, which was called the “intervention,” incorporated three principles from cognitive science that have been shown to promote learning and increase long-term retention.The principles were implemented in the following way:Repeated retrieval practice — In addition to receiving the standard homework assignment, students were given follow-up problems on the same topic in two additional assignments that counted only toward their course participation grade. Spacing — Rather than giving all the problem sets for a week’s lectures in one assignment, the researchers spaced the problems over three weeks of assignments. Feedback — Rather than waiting one week to learn how they did, students received immediate feedback on intervention homework, and they were required to view the feedback to get credit for the assignment. “Giving students multiple opportunities to practice retrieving and applying their knowledge on new problems is a very powerful way to promote learning, especially when this practice is spaced out over time,” said study co-author Elizabeth Marsh, associate professor of psychology and neuroscience at Duke. “Feedback also is critical to learning, and previous studies have shown that students will often skip looking at feedback.”To alleviate any concerns that individual differences in ability might skew the study results, the researchers split the class into two groups and assigned each group standard homework and intervention homework during alternating weeks; in any given week, half of the students were assigned to the intervention and half to the standard practice homework.The course covered 11 broad topics and approximately five core concepts per topic. …

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Moon of Saturn: Surface of Titan sea is mirror smooth

The surface of Ligeia Mare, Titan’s second largest sea, has a mirror-like smoothness, possibly due to a lack of winds, geophysicists say. As the only other solar system body with an Earth-like weather system, Titan could serve as a model for studying our own planet’s early history.New radar measurements of an enormous sea on Titan offer insights into the weather patterns and landscape composition of the Saturnian moon. The measurements, made in 2013 by NASA’s Cassini spacecraft, reveal that the surface of Ligeia Mare, Titan’s second largest sea, possesses a mirror-like smoothness, possibly due to a lack of winds.”If you could look out on this sea, it would be really still. It would just be a totally glassy surface,” said Howard Zebker, professor of geophysics and of electrical engineering at Stanford who is the lead author of a new study detailing the research.The findings, recently published online in Geophysical Research Letters, also indicate that the solid terrain surrounding the sea is likely made of solid organic materials and not frozen water.Saturn’s second largest moon, Titan has a dense, planet-like atmosphere and large seas made of methane and ethane. Measuring roughly 260 miles (420 km) by 217 miles (350 km), Ligeia Mare is larger than Lake Superior on Earth. “Titan is the best analog that we have in the solar system to a body like the Earth because it is the only other body that we know of that has a complex cycle of solid, liquid, and gas constituents,” Zebker said.Titan’s thick cloud cover makes it difficult for Cassini to obtain clear optical images of its surface, so scientists must rely on radar, which can see through the clouds, instead of a camera.To paint a radar picture of Ligeia Mare, Cassini bounced radio waves off the sea’s surface and then analyzed the echo. The strength of the reflected signal indicated how much wave action was happening on the sea. To understand why, Zebker said, imagine sunlight reflecting off of a lake on Earth. “If the lake were really flat, it would act as a perfect mirror and you would have an extremely bright image of the sun,” he said. “But if you ruffle up the surface of the sea, the light gets scattered in a lot of directions, and the reflection would be much dimmer. …

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New wireless network to revolutionize soil testing

A University of Southampton researcher has helped to develop a wireless network of sensors that is set to revolutionize soil-based salinity measuring.Dr Nick Harris, from Electronics and Electrical Engineering, worked with a group of professors from the University of Western Australia (UWA) to produce the revolutionary sensor that can carry out non-destructive testing of soil samples.The sensor is capable of measuring the chloride (salt) in the soil moisture and linking up with other sensors to create a wireless network that can collate and relay the measurement readings. The network can also control the time intervals at which measurements are taken.The sensor is placed in the soil and measures the chloride levels in the soil moisture in a non-destructive way. These chloride levels make up a high proportion of the overall soil salinity.Dr Harris says: “Traditionally, soil-based measurements involve taking samples and transporting them to the laboratory for analysis. This is very labor and cost intensive and therefore it usually means spot checks only with samples being taken every two to three months. It also doesn’t differentiate between chloride in crystallized form and chloride in dissolved form. This can be an important difference as plants only ‘see’ chloride in the soil moisture.”The removal of a soil sample from its natural environment also means that the same sample can only be measured once, so the traditional (destructive) method is not suited to measuring changes at a point over a period of time..”The new sensors are connected to a small unit and can be ‘planted’ in the ground and left to their own devices. The limiting factor for lifetime is usually the sensor. However, these sensors are expected to have a lifetime in excess of one year. The battery-powered unit can transmit data and information by short range radio, Bluetooth, satellite or mobile phone network, as well as allowing data to be logged to a memory card to be collected later.The novel device allows up to seven sensors to be connected at a time to a single transmitter allowing multi-point measurements to be simply taken.Dr Harris adds: “These soil-based chloride sensors can benefit a wide range of applications. Large parts of the world have problems with salt causing agricultural land to be unusable, but the new sensors allow the level of salt to be measured in real time, rather than once every few months as was previously the case.”At plant level, probes can be positioned at continuous levels of depth to determine the salt concentration to which roots are exposed and whether this concentration changes with the depth of the soil or in different weather conditions. …

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Brain signals move paralyzed limbs in new experiment

To help people suffering paralysis from injury, stroke or disease, scientists have invented brain-machine interfaces that record electrical signals of neurons in the brain and translate them to movement. Usually, that means the neural signals direct a device, like a robotic arm.Cornell University researcher Maryam Shanechi, assistant professor of electrical and computer engineering, working with Ziv Williams, assistant professor of neurosurgery at Harvard Medical School, is bringing brain-machine interfaces to the next level: Instead of signals directing a device, she hopes to help paralyzed people move their own limb, just by thinking about it.When paralyzed patients imagine or plan a movement, neurons in the brain’s motor cortical areas still activate even though the communication link between the brain and muscles is broken. By implanting sensors in these brain areas, neural activity can be recorded and translated to the patient’s desired movement using a mathematical transform called the decoder. These interfaces allow patients to generate movements directly with their thoughts.In a paper published online Feb. 18 in Nature Communications, Shanechi, Williams and colleagues describe a cortical-spinal prosthesis that directs “targeted movement” in paralyzed limbs. The research team developed and tested a prosthesis that connects two subjects by enabling one subject to send its recorded neural activity to control limb movements in a different subject that is temporarily sedated. The demonstration is a step forward in making brain-machine interfaces for paralyzed humans to control their own limbs using their brain activity alone.The brain-machine interface is based on a set of real-time decoding algorithms that process neural signals by predicting their targeted movements. In the experiment, one animal acted as the controller of the movement or the “master,” then “decided” which target location to move to, and generated the neural activity that was decoded into this intended movement. The decoded movement was used to directly control the limb of the other animal by electrically stimulating its spinal cord.”The problem here is not only that of decoding the recorded neural activity into the intended movement, but also that of properly stimulating the spinal cord to move the paralyzed limb according to the decoded movement,” Shanechi said.The scientists focused on decoding the target endpoint of the movement as opposed to its detailed kinematics. This allowed them to match the decoded target with a set of spinal stimulation parameters that generated limb movement toward that target. …

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Revealing how the brain recognizes speech sounds

UC San Francisco researchers are reporting a detailed account of how speech sounds are identified by the human brain, offering an unprecedented insight into the basis of human language. The finding, they said, may add to our understanding of language disorders, including dyslexia.Scientists have known for some time the location in the brain where speech sounds are interpreted, but little has been discovered about how this process works.Now, in Science Express (January 30th, 2014), the fast-tracked online version of the journal Science, the UCSF team reports that the brain does not respond to the individual sound segments known as phonemes — such as the b sound in “boy” — but is instead exquisitely tuned to detect simpler elements, which are known to linguists as “features.”This organization may give listeners an important advantage in interpreting speech, the researchers said, since the articulation of phonemes varies considerably across speakers, and even in individual speakers over time.The work may add to our understanding of reading disorders, in which printed words are imperfectly mapped onto speech sounds. But because speech and language are a defining human behavior, the findings are significant in their own right, said UCSF neurosurgeon and neuroscientist Edward F. Chang, MD, senior author of the new study.”This is a very intriguing glimpse into speech processing,” said Chang, associate professor of neurological surgery and physiology. “The brain regions where speech is processed in the brain had been identified, but no one has really known how that processing happens.”Although we usually find it effortless to understand other people when they speak, parsing the speech stream is an impressive perceptual feat. Speech is a highly complex and variable acoustic signal, and our ability to instantaneously break that signal down into individual phonemes and then build those segments back up into words, sentences and meaning is a remarkable capability.Because of this complexity, previous studies have analyzed brain responses to just a few natural or synthesized speech sounds, but the new research employed spoken natural sentences containing the complete inventory of phonemes in the English language.To capture the very rapid brain changes involved in processing speech, the UCSF scientists gathered their data from neural recording devices that were placed directly on the surface of the brains of six patients as part of their epilepsy surgery.The patients listened to a collection of 500 unique English sentences spoken by 400 different people while the researchers recorded from a brain area called the superior temporal gyrus (STG; also known as Wernicke’s area), which previous research has shown to be involved in speech perception. The utterances contained multiple instances of every English speech sound.Many researchers have presumed that brain cells in the STG would respond to phonemes. But the researchers found instead that regions of the STG are tuned to respond to even more elemental acoustic features that reference the particular way that speech sounds are generated from the vocal tract. “These regions are spread out over the STG,” said first author Nima Mesgarani, PhD, now an assistant professor of electrical engineering at Columbia University, who did the research as a postdoctoral fellow in Chang’s laboratory. “As a result, when we hear someone talk, different areas in the brain ‘light up’ as we hear the stream of different speech elements.””Features,” as linguists use the term, are distinctive acoustic signatures created when speakers move the lips, tongue or vocal cords. …

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Breakthrough in rechargeable batteries: New twist to sodium-ion battery technology

A Kansas State University engineer has made a breakthrough in rechargeable battery applications.Gurpreet Singh, assistant professor of mechanical and nuclear engineering, and his student researchers are the first to demonstrate that a composite paper — made of interleaved molybdenum disulfide and graphene nanosheets — can be both an active material to efficiently store sodium atoms and a flexible current collector. The newly developed composite paper can be used as a negative electrode in sodium-ion batteries.”Most negative electrodes for sodium-ion batteries use materials that undergo an ‘alloying’ reaction with sodium,” Singh said. “These materials can swell as much as 400 to 500 percent as the battery is charged and discharged, which may result in mechanical damage and loss of electrical contact with the current collector.””Molybdenum disulfide, the major constituent of the paper electrode, offers a new kind of chemistry with sodium ions, which is a combination of intercalation and a conversion-type reaction,” Singh said. “The paper electrode offers stable charge capacity of 230 mAh.g-1, with respect to total electrode weight. Further, the interleaved and porous structure of the paper electrode offers smooth channels for sodium to diffuse in and out as the cell is charged and discharged quickly. This design also eliminates the polymeric binders and copper current collector foil used in a traditional battery electrode.”The research appears in the latest issue of the journal ACS Nanoin the article “MoS2/graphene composite paper for sodium-ion battery electrodes.”For the last two years the researchers have been developing new methods for quick and cost-effective synthesis of atomically thin two-dimensional materials — graphene, molybdenum and tungsten disulfide — in gram quantities, particularly for rechargeable battery applications.For the latest research, the engineers created a large-area composite paper that consisted of acid-treated layered molybdenum disulfide and chemically modified graphene in an interleaved structured. The research marks the first time that such a flexible paper electrode was used in a sodium-ion battery as an anode that operates at room temperature. Most commercial sodium-sulfur batteries operate close to 300 degrees Celsius, Singh said.Singh said the research is important for two reasons:1. Synthesis of large quantities of single or few-layer-thick 2-D materials is crucial to understanding the true commercial potential of materials such as transition metal dichalcogenides, or TMD, and graphene.2. Fundamental understanding of how sodium is stored in a layered material through mechanisms other than the conventional intercalation and alloying reaction. …

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Mesothelioma Alternative Therapy – What Are Your Options?

Quite a number of patients afflicted with asbestos related diseases such as asbestosis and mesothelioma now-a days use different types of complimentary and alternative therapies in addition to conventional therapies like surgery and drugs.These alternative therapies are used by patients coping with asbestos related disease as a form of pain management, to improve general health, and also to provide symptomatic relief.Although these treatments do not offer a cure, they certainly help you to live more comfortable lives by providing relief from pain and stress.The most commonly used alternative therapies include the following:1} AcupunctureThis is one of the commonest forms of available alternative therapies today, and there are a lot of insurance companies offering coverage for this type of treatment. Acupuncture involves the …

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Alternative Mesothelioma Treatments

Alternative Mesothelioma TreatmentsBy Bill CassAlternative treatments for mesothelioma are often described as holistic treatments because not only do they help patients’ physical well being but also mentally, emotionally, and spiritually. Alternative treatments help ease stress and reduce the side effects caused by conventional treatments for mesothelioma cancer. Alternative treatments for mesothelioma therefore are a great compliment to medical treatment.Alternative TreatmentsIn order to make the most of your cancer treatment, it is a good idea to discuss alternative treatments with your doctor. Anything deemed outside the traditional treatments (surgery, chemotherapy, radiation) are alternative treatments. Alternative mesothelioma treatments can include:AcupunctureYogaMeditationMassage TherapyNutritional Supplements and HerbsAromatherapyTENS therapyThese treatments may be expensive and most are not covered by health insurance.AcupunctureThis technique involves thin, long needles being inserted into certain …

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Software uses cyborg swarm to map unknown environs

Oct. 16, 2013 — Researchers from North Carolina State University have developed software that allows them to map unknown environments — such as collapsed buildings — based on the movement of a swarm of insect cyborgs, or “biobots.””We focused on how to map areas where you have little or no precise information on where each biobot is, such as a collapsed building where you can’t use GPS technology,” says Dr. Edgar Lobaton, an assistant professor of electrical and computer engineering at NC State and senior author of a paper on the research.”One characteristic of biobots is that their movement can be somewhat random,” Lobaton says. “We’re exploiting that random movement to work in our favor.”Here’s how the process would work in the field. A swarm of biobots, such as remotely controlled cockroaches, would be equipped with electronic sensors and released into a collapsed building or other hard-to-reach area. The biobots would initially be allowed to move about randomly. Because the biobots couldn’t be tracked by GPS, their precise locations would be unknown. However, the sensors would signal researchers via radio waves whenever biobots got close to each other.Once the swarm has had a chance to spread out, the researchers would send a signal commanding the biobots to keep moving until they find a wall or other unbroken surface — and then continue moving along the wall. This is called “wall following.”The researchers repeat this cycle of random movement and “wall following” several times, continually collecting data from the sensors whenever the biobots are near each other. The new software then uses an algorithm to translate the biobot sensor data into a rough map of the unknown environment.”This would give first responders a good idea of the layout in a previously unmapped area,” Lobaton says.The software would also allow public safety officials to determine the location of radioactive or chemical threats, if the biobots have been equipped with the relevant sensors.The researchers have tested the software using computer simulations and are currently testing the program with robots. …

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Scientists demonstrate new method for harvesting energy from light

Sep. 9, 2013 — Researchers from the University of Pennsylvania have demonstrated a new mechanism for extracting energy from light, a finding that could improve technologies for generating electricity from solar energy and lead to more efficient optoelectronic devices used in communications.Dawn Bonnell, Penn’s vice provost for research and Trustee Professor of Materials Science and Engineering in the School of Engineering and Applied Science, led the work, along with David Conklin, a doctoral student. The study involved a collaboration among additional Penn researchers, through the Nano/Bio Interface Center, as well as a partnership with the lab of Michael J. Therien of Duke University.”We’re excited to have found a process that is much more efficient than conventional photoconduction,” Bonnell said. “Using such an approach could make solar energy harvesting and optoelectronic devices much better.”The study was published in the journal ACS Nano and was discussed at a press conference at the American Chemical Society National Meeting and Exhibition in Indianapolis today.The new work centers on plasmonic nanostructures, specifically, materials fabricated from gold particles and light-sensitive molecules of porphyin, of precise sizes and arranged in specific patterns. Plasmons, or a collective oscillation of electrons, can be excited in these systems by optical radiation and induce an electrical current that can move in a pattern determined by the size and layout of the gold particles, as well as the electrical properties of the surrounding environment.Because these materials can enhance the scattering of light, they have the potential to be used to advantage in a range of technological applications, such as increasing absorption in solar cells.In 2010, Bonnell and colleagues published a paper in ACS Nano reporting the fabrication of a plasmonic nanostructure, which induced and projected an electrical current across molecules. In some cases they designed the material, an array of gold nanoparticles, using a technique Bonnell’s group invented, known as ferroelectric nanolithography.The discovery was potentially powerful, but the scientists couldn’t prove that the improved transduction of optical radiation to an electrical current was due to the “hot electrons” produced by the excited plasmons. Other possibilities included that the porphyin molecule itself was excited or that the electric field could focus the incoming light.”We hypothesized that, when plasmons are excited to a high energy state, we should be able to harvest the electrons out of the material,” Bonnell said. “If we could do that, we could use them for molecular electronics device applications, such as circuit components or solar energy extraction.”To examine the mechanism of the plasmon-induced current, the researchers systematically varied the different components of the plasmonic nanostructure, changing the size of the gold nanoparticles, the size of the porphyin molecules and the spacing of those components. They designed specific structures that ruled out the other possibilities so that the only contribution to enhanced photocurrent could be from the hot electrons harvested from the plasmons.”In our measurements, compared to conventional photoexcitation, we saw increases of three to 10 times in the efficiency of our process,” Bonnell said. …

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An easier way to control genes

Sep. 3, 2013 — MIT researchers have shown that they can turn genes on or off inside yeast and human cells by controlling when DNA is copied into messenger RNA — an advance that could allow scientists to better understand the function of those genes.The technique could also make it easier to engineer cells that can monitor their environment, produce a drug or detect disease, says Timothy Lu, an assistant professor of electrical engineering and computer science and biological engineering and the senior author of a paper describing the new approach in the journal ACS Synthetic Biology.”I think it’s going to make it a lot easier to build synthetic circuits,” says Lu, a member of MIT’s Synthetic Biology Center. “It should increase the scale and the speed at which we can build a variety of synthetic circuits in yeast cells and mammalian cells.”The new method is based on a system of viral proteins that have been exploited recently to edit the genomes of bacterial and human cells. The original system, called CRISPR, consists of two components: a protein that binds to and slices DNA, and a short strand of RNA that guides the protein to the right location on the genome.”The CRISPR system is quite powerful in that it can be targeted to different DNA binding regions based on simple recoding of these guide RNAs,” Lu says. “By simply reprogramming the RNA sequence you can direct this protein to any location you want on the genome or on a synthetic circuit.”Lead author of the paper is Fahim Farzadfard, an MIT graduate student in biology. Samuel Perli, a graduate student in electrical engineering and computer science, is also an author.Targeting transcriptionIn previous studies, CRISPR has been used to snip out pieces of a gene to disable it or replace it with a new gene. Lu and his colleagues decided to use the CRISPR system for a different purpose: controlling gene transcription, the process by which a sequence of DNA is copied into messenger RNA (mRNA), which carries out the gene’s instructions.Transcription is tightly regulated by proteins called transcription factors. These proteins bind to specific DNA sequences in the gene’s promoter region and either recruit or block the enzymes needed to copy that gene into mRNA.For this study, the researchers adapted the CRISPR system to act as a transcription factor. First, they modified the usual CRISPR protein, known as Cas9, so that it could no longer snip DNA after binding to it. They also added to the protein a segment that activates or represses gene expression by modulating the cell’s transcriptional machinery.To get Cas9 to the right place, the researchers also delivered to the target cells a gene for an RNA guide that corresponds to a DNA sequence on the promoter of the gene they want to activate.The researchers showed that once the RNA guide and the Cas9 protein join together inside the target cell, they accurately target the correct gene and turn on transcription. …

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Brain circuit can tune anxiety

Aug. 21, 2013 — Anxiety disorders, which include posttraumatic stress disorder, social phobias and obsessive-compulsive disorder, affect 40 million American adults in a given year. Currently available treatments, such as antianxiety drugs, are not always effective and have unwanted side effects.To develop better treatments, a more specific understanding of the brain circuits that produce anxiety is necessary, says Kay Tye, an assistant professor of brain and cognitive sciences and member of MIT’s Picower Institute for Learning and Memory.”The targets that current antianxiety drugs are acting on are very nonspecific. We don’t actually know what the targets are for modulating anxiety-related behavior,” Tye says.In a step toward uncovering better targets, Tye and her colleagues have discovered a communication pathway between two brain structures — the amygdala and the ventral hippocampus — that appears to control anxiety levels. By turning the volume of this communication up and down in mice, the researchers were able to boost and reduce anxiety levels.Lead authors of the paper, which appears in the Aug. 21 issue of Neuron, are technical assistant Ada Felix-Ortiz and postdoc Anna Beyeler. Other authors are former research assistant Changwoo Seo, summer student Christopher Leppla and research scientist Craig Wildes.Measuring anxietyBoth the hippocampus, which is necessary for memory formation, and the amygdala, which is involved in memory and emotion processing, have previously been implicated in anxiety. However, it was unknown how the two interact.To study those interactions, the researchers turned to optogenetics, which allows them to engineer neurons to turn their electrical activity on or off in response to light. For this study, the researchers modified a set of neurons in the basolateral amygdala (BLA); these neurons send long projections to cells of the ventral hippocampus.The researchers tested the mice’s anxiety levels by measuring how much time they were willing to spend in a situation that normally makes them anxious. Mice are naturally anxious in open spaces where they are easy targets for predators, so when placed in such an area, they tend to stay near the edges.When the researchers activated the connection between cells in the amygdala and the hippocampus, the mice spent more time at the edges of an enclosure, suggesting they felt anxious. …

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‘Groovy’ hologram creates strange state of light

Aug. 20, 2013 — Applied physicists at the Harvard School of Engineering and Applied Sciences (SEAS) have demonstrated that they can change the intensity, phase, and polarization of light rays using a hologram-like design decorated with nanoscale structures.As a proof of principle, the researchers have used it to create an unusual state of light called a radially polarized beam, which — because it can be focused very tightly — is important for applications like high-resolution lithography and for trapping and manipulating tiny particles like viruses.This is the first time a single, simple device has been designed to control these three major properties of light at once. (Phase describes how two waves interfere to either strengthen or cancel each other, depending on how their crests and troughs overlap; polarization describes the direction of light vibrations; and the intensity is the brightness.)”Our lab works on using nanotechnology to play with light,” says Patrice Genevet, a research associate at Harvard SEAS and co-lead author of a paper published this month in Nano Letters. “In this research, we’ve used holography in a novel way, incorporating cutting-edge nanotechnology in the form of subwavelength structures at a scale of just tens of nanometers.” One nanometer equals one billionth of a meter.Genevet works in the laboratory of Federico Capasso, Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering at Harvard SEAS. Capasso’s research group in recent years has focused on nanophotonics — the manipulation of light at the nanometer scale — with the goal of creating new light beams and special effects that arise from the interaction of light with nanostructured materials.Using these novel nanostructured holograms, the Harvard researchers have converted conventional, circularly polarized laser light into radially polarized beams at wavelengths spanning the technologically important visible and near-infrared light spectrum.”When light is radially polarized, its electromagnetic vibrations oscillate inward and outward from the center of the beam like the spokes of a wheel,” explains Capasso. “This unusual beam manifests itself as a very intense ring of light with a dark spot in the center.””It is noteworthy,” Capasso points out, “that the same nanostructured holographic plate can be used to create radially polarized light at so many different wavelengths. Radially polarized light can be focused much more tightly than conventionally polarized light, thus enabling many potential applications in microscopy and nanoparticle manipulation.”The new device resembles a normal hologram grating with an additional, nanostructured pattern carved into it. Visible light, which has a wavelength in the hundreds of nanometers, interacts differently with apertures textured on the ‘nano’ scale than with those on the scale of micrometers or larger. By exploiting these behaviors, the modular interface can bend incoming light to adjust its intensity, phase, and polarization.Holograms, beyond being a staple of science-fiction universes, find many applications in security, like the holographic panels on credit cards and passports, and new digital hologram-based data-storage methods are currently being designed to potentially replace current systems. …

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Scientists watch live brain cell circuits spark and fire

Aug. 8, 2013 — Scientists used fruit flies to show for the first time that a new class of genetically engineered proteins can be used to watch electrical activity in individual brain cells in live brains. The results, published in Cell, suggest these proteins may be a promising new tool for mapping brain cell activity in multiple animals and for studying how neurological disorders disrupt normal nerve cell signaling. Understanding brain cell activity is a high priority of the President’s Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative.Share This:Brain cells use electricity to control thoughts, movements and senses. Ever since the late nineteenth century, when Dr. Luigi Galvani induced frog legs to move with electric shocks, scientists have been trying to watch nerve cell electricity to understand how it is involved in these actions. Usually they directly mo nitor electricity with cumbersome electrodes or toxic voltage-sensitive dyes, or indirectly with calcium detectors. This study, led by Michael Nitabach, Ph.D., J.D., and Vincent Pieribone, Ph.D., at the Yale School of Medicine, New Haven, CT, shows that a class of proteins, called genetically encoded fluorescent voltage indicators (GEVIs), may allow researchers to watch nerve cell electricity in a live animal.Dr. Pieribone and his colleagues helped develop ArcLight, the protein used in this study. ArcLight fluoresces, or glows, as a nerve cell’s voltage changes and enables researchers to watch, in real time, the cell’s electrical activity. …

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‘Soft’ approach leads to revolutionary energy storage: Graphene-based supercapacitors

Aug. 1, 2013 — Monash University researchers have brought next generation energy storage closer with an engineering first — a graphene-based device that is compact, yet lasts as long as a conventional battery.Published today in Science, a research team led by Professor Dan Li of the Department of Materials Engineering has developed a completely new strategy to engineer graphene-based supercapacitors (SC), making them viable for widespread use in renewable energy storage, portable electronics and electric vehicles.SCs are generally made of highly porous carbon impregnated with a liquid electrolyte to transport the electrical charge. Known for their almost indefinite lifespan and the ability to re-charge in seconds, the drawback of existing SCs is their low energy-storage-to-volume ratio — known as energy density. Low energy density of five to eight Watt-hours per litre, means SCs are unfeasibly large or must be re-charged frequently.Professor Li’s team has created an SC with energy density of 60 Watt-hours per litre — comparable to lead-acid batteries and around 12 times higher than commercially available SCs.”It has long been a challenge to make SCs smaller, lighter and compact to meet the increasingly demanding needs of many commercial uses,” Professor Li said.Graphene, which is formed when graphite is broken down into layers one atom thick, is very strong, chemically stable and an excellent conductor of electricity.To make their uniquely compact electrode, Professor Li’s team exploited an adaptive graphene gel film they had developed previously. They used liquid electrolytes — generally the conductor in traditional SCs — to control the spacing between graphene sheets on the sub-nanometre scale. In this way the liquid electrolyte played a dual role: maintaining the minute space between the graphene sheets and conducting electricity.Unlike in traditional ‘hard’ porous carbon, where space is wasted with unnecessarily large ‘pores’, density is maximised without compromising porosity in Professor Li’s electrode.To create their material, the research team used a method similar to that used in traditional paper making, meaning the process could be easily and cost-effectively scaled up for industrial use.”We have created a macroscopic graphene material that is a step beyond what has been achieved previously. It is almost at the stage of moving from the lab to commercial development,” Professor Li said.

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Neural simulations hint at the origin of brain waves

July 24, 2013 — For almost a century, scientists have been studying brain waves to learn about mental health and the way we think. Yet the way billions of interconnected neurons work together to produce brain waves remains unknown. Now, scientists from EPFL’s Blue Brain Project in Switzerland, at the core of the European Human Brain Project, and the Allen Institute for Brain Science in the United States, show in the July 24th edition of the journal Neuron how a complex computer model is providing a new tool to solve the mystery.The brain is composed of many different types of neurons, each of which carry electrical signals. Electrodes placed on the head or directly in brain tissue allow scientists to monitor the cumulative effect of this electrical activity, called electroencephalography (EEG) signals. But what is it about the structure and function of each and every neuron, and the way they network together, that give rise to these electrical signals measured in a mammalian brain?Modeling Brain CircuitryThe Blue Brain Project is working to model a complete human brain. For the moment, Blue Brain scientists study rodent brain tissue and characterize different types of neurons to excruciating detail, recording their electrical properties, shapes, sizes, and how they connect.To answer the question of brain-wave origin, researchers at EPFL’s Blue Brain Project and the Allen Institute joined forces with the help of the Blue Brain modeling facilities. Their work is based on a computer model of a neural circuit the likes of which have never been seen before, encompassing an unprecedented amount of detail and simulating 12,000 neurons.”It is the first time that a model of this complexity has been used to study the underlying properties of brain waves,” says EPFL scientist Sean Hill.In observing their model, the researchers noticed that the electrical activity swirling through the entire system was reminiscent of brain waves measured in rodents. Because the computer model uses an overwhelming amount of physical, chemical and biological data, the supercomputer simulation allows scientists to analyze brain waves at a level of detail simply unattainable with traditional monitoring of live brain tissue.”We need a computer model because it is impossible to relate the electrical activity of potentially billions of individual neurons and the resulting brain waves at the same time,” says Hill. “Through this view, we’re able to provide an interpretation, at the single-neuron level, of brain waves that are measured when tissue is actually probed in the lab.”Finding brain wave analogsNeurons are somewhat like tiny batteries, needing to be charged in order to fire off an electrical impulse known as a “spike.” It is through these “spikes” that neurons communicate with each other to produce thought and perception. To “recharge” a neuron, charged particles called ions must travel through miniscule ionic channels. …

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A new weapon against stroke

July 23, 2013 — One of regenerative medicine’s greatest goals is to develop new treatments for stroke. So far, stem cell research for the disease has focused on developing therapeutic neurons — the primary movers of electrical impulses in the brain — to repair tissue damaged when oxygen to the brain is limited by a blood clot or break in a vessel. New UC Davis research, however, shows that other cells may be better suited for the task.Published today in the journal Nature Communications, the large, collaborative study found that astrocytes — neural cells that transport key nutrients and form the blood-brain barrier — can protect brain tissue and reduce disability due to stroke and other ischemic brain disorders.”Astrocytes are often considered just ‘housekeeping’ cells because of their supportive roles to neurons, but they’re actually much more sophisticated,” said Wenbin Deng, associate professor of biochemistry and molecular medicine at UC Davis and senior author of the study. “They are critical to several brain functions and are believed to protect neurons from injury and death. They are not excitable cells like neurons and are easier to harness. We wanted to explore their potential in treating neurological disorders, beginning with stroke.”Deng added that the therapeutic potential of astrocytes has not been investigated in this context, since making them at the purity levels necessary for stem cell therapies is challenging. In addition, the specific types of astrocytes linked with protecting and repairing brain injuries were not well understood.The team began by using a transcription factor (a protein that turns on genes) known as Olig2 to differentiate human embryonic stem cells into astrocytes. This approach generated a previously undiscovered type of astrocyte called Olig2PC-Astros. More importantly, it produced those astrocytes at almost 100 percent purity.The researchers then compared the effects of Olig2PC-Astros, another type of astrocyte called NPC-Astros and no treatment whatsoever on three groups of rats with ischemic brain injuries. The rats transplanted with Olig2PC-Astros experienced superior neuroprotection together with higher levels of brain-derived neurotrophic factor (BDNF), a protein associated with nerve growth and survival. …

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Ability to learn new words based on efficient communication between brain areas that control movement and hearing

July 22, 2013 — For the first time scientists have identified how a pathway in the brain which is unique to humans allows us to learn new words.The average adult’s vocabulary consists of about 30,000 words. This ability seems unique to humans as even the species closest to us — chimps — manage to learn no more than 100.It has long been believed that language learning depends on the integration of hearing and repeating words but the neural mechanisms behind learning new words remained unclear. Previous studies have shown that this may be related to a pathway in the brain only found in humans and that humans can learn only words that they can articulate.Now researchers from King’s College London Institute of Psychiatry, in collaboration with Bellvitge Biomedical Research Institute (IDIBELL) and the University of Barcelona, have mapped the neural pathways involved in word learning among humans. They found that the arcuate fasciculus, a collection of nerve fibres connecting auditory regions at the temporal lobe with the motor area located at the frontal lobe in the left hemisphere of the brain, allows the ‘sound’ of a word to be connected to the regions responsible for its articulation. Differences in the development of these auditory-motor connections may explain differences in people’s ability to learn words. The results of the study are published in the journal Proceedings of the National Academy of Sciences (PNAS).Dr Marco Catani, co-author from King’s College London Institute of Psychiatry said: “Often humans take their ability to learn words for granted. This research sheds new light on the unique ability of humans to learn a language, as this pathway is not present in other species. The implications of our findings could be wide ranging — from how language is taught in schools and rehabilitation from injury, to early detection of language disorders such as dyslexia. In addition these findings could have implications for other disorders where language is affected such as autism and schizophrenia.”The study involved 27 healthy volunteers. Researchers used diffusion tensor imaging to image the structure of the brain before a word learning task and functional MRI, to detect the regions in the brain that were most active during the task. …

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Helping robots become more touchy-feely, literally: Paper-thin e-skin responds to touch by lighting up

July 21, 2013 — A new milestone by engineers at UC Berkeley can help robots become more touchy-feely, literally.A research team led by Ali Javey, UC Berkeley associate professor of electrical engineering and computer sciences, has created the first user-interactive sensor network on flexible plastic. The new electronic skin, or e-skin, responds to touch by instantly lighting up. The more intense the pressure, the brighter the light it emits.”We are not just making devices; we are building systems,” said Javey, who also has an appointment as a faculty scientist at the Lawrence Berkeley National Laboratory. “With the interactive e-skin, we have demonstrated an elegant system on plastic that can be wrapped around different objects to enable a new form of human-machine interfacing.”Shown is a 16-by-16 pixel interactive e-skin created by UC Berkeley engineers. Organic LEDs light up when touched. (Photo by Ali Javey and Chuan Wang)This latest e-skin, described in a paper published online July 21 in the journal Nature Materials, builds on Javey’s earlier work using semiconductor nanowire transistors layered on top of thin rubber sheets.In addition to giving robots a finer sense of touch, the engineers believe the new e-skin technology could also be used to create things like wallpapers that double as touchscreen displays and dashboard laminates that allow drivers to adjust electronic controls with the wave of a hand.”I could also imagine an e-skin bandage applied to an arm as a health monitor that continuously checks blood pressure and pulse rates,” said study co-lead author Chuan Wang, who conducted the work as a post-doctoral researcher in Javey’s lab at UC Berkeley.The experimental samples of the latest e-skin measure 16-by-16 pixels. Within each pixel sits a transistor, an organic LED and a pressure sensor.”Integrating sensors into a network is not new, but converting the data obtained into something interactive is the breakthrough,” said Wang, who is now an assistant professor of electrical and computer engineering at Michigan State University. “And unlike the stiff touchscreens on iPhones, computer monitors and ATMs, the e-skin is flexible and can be easily laminated on any surface.”To create the pliable e-skin, the engineers cured a thin layer of polymer on top of a silicon wafer. Once the plastic hardened, they could run the material through fabrication tools already in use in the semiconductor industry to layer on the electronic components. After the electronics were stacked, they simply peeled off the plastic from the silicon base, leaving a freestanding film with a sensor network embedded in it.”The electronic components are all vertically integrated, which is a fairly sophisticated system to put onto a relatively cheap piece of plastic,” said Javey. …

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