Science News

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A ground-breaking census of 500 stars, 70 of which are known to host planets, has successfully linked the long-standing “lithium mystery” observed in the Sun to the presence of planetary systems. Using ESO’s successful HARPS spectrograph, a team of astronomers has found that Sun-like stars that host planets have destroyed their lithium much more efficiently than “planet-free” stars. This finding does not only shed light on the lack of lithium in our star, but also provides astronomers with a very efficient way of finding stars with planetary systems.

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NASA's Wide-field Infrared Survey Explorer, or Wise, is chilled out, sporting a sunshade and getting ready to roll. NASA's newest spacecraft is scheduled to roll to the pad on Friday, Nov. 20, its last stop before launching into space to survey the entire sky in infrared light.

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Scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory have refined a technique to manufacture solar cells by creating tubes of semiconducting material and then "growing" polymers directly inside them. The method has the potential to be significantly cheaper than the process used to make today’s commercial solar cells.

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Increasing amounts of ice mass have been lost from West Antarctica and the Antarctic peninsula over the past ten years, according to research from the University of Bristol and published online this week in Nature Geoscience. Meanwhile the ice mass in East Antarctica has been roughly stable, with neither loss nor accumulation over the past decade. http://hypography.com/gallery/files/2/5/2/6/image_thumb.jpgProfessor Jonathan Bamber at the University of Bristol and colleagues estimated the flux of ice from the ice sheet into the ocean from satellite data that cover 85% of Antarctica's coastline, which they compared with simulations of snow accumulation over the same period, obtained using a regional climate model. They arrived at a best estimate of a loss of 132 billion tonnes of ice in 2006 from West Antarctica ? up from about 83 billion tonnes in 1996 ? and a loss of about 60 billion tonnes in 2006 from the Antarctic Peninsula. Professor Bamber said: ?To put these figures into perspective, four billion tons of ice is enough to provide drinking water for the whole of the UK population for one year." The authors conclude that the Antarctic ice sheet mass budget is more complex than indicated by the evolution of its surface mass balance or climate-driven predictions. Changes in glacier dynamics are significant and may in fact dominate the ice sheet mass budget. This conclusion is contrary to model simulations of the response of the ice sheet to future climate change, which conclude that it will grow due to increased snowfall. The ice loss is concentrated at narrow glacier outlets with accelerating ice flow, which suggests that glacier flow has altered the mass balance of the entire ice sheet. Over the 10 year time period of the survey, the ice sheet as a whole was certainly losing mass, and the mass loss increased by 75% during this time. Most of the mass loss is from the Amundsen Sea sector of West Antarctica and the northern tip of the Peninsula where it is driven by ongoing, pronounced glacier acceleration. In East Antarctica, the mass balance is near zero, but the thinning of its potentially vulnerable marine sectors suggests this may change in the near future. Source: Bristol University

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Once upon a time - roughly four billion years ago - Mars was warm and wet, much like Earth. Liquid water flowed on the Martian surface in long rivers that emptied into shallow seas. A thick atmosphere blanketed the planet and kept it warm. Living microbes might have even arisen, some scientists believe, starting Mars down the path toward becoming a second life-filled planet next door to our own. But that's not how things turned out. Mars today is bitter cold and bone dry. The rivers and seas are long gone. Its atmosphere is thin and wispy, and if Martian microbes still exist, they're probably eking out a meager existence somewhere beneath the dusty Martian soil. What happened? Why did Mars dry up and freeze over? These haunting questions have long puzzled scientists. A few years from now we might finally know the answer, thanks to a new orbiter NASA will send to Mars called MAVEN (short for Mars Atmosphere and Volatile Evolution). "The goal of MAVEN is to figure out what processes were responsible for those changes in the climate," says Bruce Jakosky, Principal Investigator for MAVEN at the University of Colorado at Boulder. One way or another, scientists believe, Mars must have lost its most precious asset: its thick atmosphere of carbon dioxide. CO2 in Mars's atmosphere is a greenhouse gas, just as it is in our own atmosphere. A thick blanket of CO2 and other greenhouse gases would have provided the warmer temperatures and greater atmospheric pressure required to keep liquid water from freezing solid or boiling away. Over the last four billion years, Mars somehow lost most of that blanket. Scientists have proposed various theories for how that loss happened. Perhaps an asteroid impact blew most of the atmosphere into space in one catastrophic event. Or maybe erosion by the solar wind - a stream of charged particles emanating from the sun - could have slowly stripped the atmosphere away over eons. The planet's surface might also have absorbed the CO2 and locked it up in minerals such as carbonate. video] Ultimately, nobody knows for sure where all the missing CO2 went. MAVEN will be the first mission to Mars specifically designed to help scientists understand the ongoing escape of CO2 and other gases into space. The probe will orbit Mars for at least one Earth-year. At the elliptical orbit's low point, MAVEN will be 125 km above the surface; its high point will take it more than 6000 km out into space. This wide range of altitudes will enable MAVEN to sample Mars's atmosphere more thoroughly than ever before. As it orbits, MAVEN's instruments will track ions and molecules in this broad cross-section of the Martian atmosphere, thoroughly documenting the flow of CO2 and other molecules into space for the first time. Once Jakosky and his colleagues know how quickly Mars is losing CO2 right now, they can extrapolate backward in time to estimate the total amount lost to space during the last four billion years. "MAVEN will determine if was the most important player," Jakosky says. But just as important as "how much?" is the question of "how?" Conventional wisdom holds that Mars's atmosphere is vulnerable because the planet lacks a global magnetic field. Earth's magnetic field stretches far out into space and envelopes the whole planet in a protective bubble that deflects the solar wind. Mars has only regional, patchy magnetic fields that cover relatively small areas of the planet, mostly in the southern hemisphere. The rest of the atmosphere is fully exposed to the solar wind. So the loss could be caused by the slow erosion of the atmosphere in these exposed areas. David Brain of UC Berkeley has proposed another, seemingly contrary possibility. These small magnetic fields might actually hasten the loss of Mars's atmosphere, Brain suggests. The solar wind might buffet those magnetic field lines, occasionally pinching off a "bubble" of field lines that then drifts off into space - carrying a large chunk of the atmosphere with it. If so, having a partial magnetic field might be worse than having none at all. This possibility was described in a 2008 Science@NASA story, "Solar Wind Rips Up Martian Atmosphere." Some evidence from NASA's Mars Global Surveyor spacecraft supports Brain's theory, but decisive measurements will have to wait for MAVEN, currently scheduled to launch in 2013. The mission will be a big step toward understanding what happened to Mars - how it ended up so cold and dry after such a warm and watery beginning. After all these years, MAVEN could write the final chapter in a haunting tale of planetary woe. Source: NASA

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Researchers at the University of Pennsylvania have developed a theoretical model that informs the understanding of evolution and determines how quickly an organism will evolve using a catalogue of “evolutionary speed limits.” The model provides quantitative predictions for the speed of evolution on various “fitness landscapes,” the dynamic and varied conditions under which bacteria, viruses and even humans adapt.

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Researchers at Yale University have developed synthetic molecules capable of enhancing the body’s immune response to HIV and HIV-infected cells, as well as to prostate cancer cells. Their findings, published online in the Journal of the American Chemical Society, could lead to novel therapeutic approaches for these diseases.

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Physicists at Harvard University have created a quantum gas microscope that can be used to observe single atoms at temperatures so low the particles follow the rules of quantum mechanics, behaving in bizarre ways.

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It might not be obvious to the naked eye, but the sun is a variable star. A sensor slated for launch onboard the Solar Dynamics Observatory will probe the sun's "sneaky variability" with better time and spectral resolution than ever before.

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The combination of images taken by three exceptional telescopes, the ESO Very Large Telescope on Cerro Paranal , the MPG/ESO 2.2-metre telescope at ESO’s La Silla observatory and the NASA/ESA Hubble Space Telescope, has allowed the stunning Jewel Box star cluster to be seen in a whole new light.

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One of the largest-ever computer models explores dark matter and dark energy, two cosmic constituents that remain a mystery.

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Climate scientists recognize that climate modeling projections include a significant level of uncertainty. A team of researchers using computing facilities at Oak Ridge National Laboratory (ORNL) has identified a new method for quantifying this uncertainty.

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Peering far beyond our solar system, NASA researchers have detected the basic chemistry for life in a second hot gas planet, advancing astronomers toward the goal of being able to characterize planets where life could exist. The planet is not habitable but it has the same chemistry that, if found around a rocky planet in the future, could indicate the presence of life.

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Every hour, the sun floods Earth with more energy than the entire world consumes in a year. Yet solar power accounts for less than 0.002 percent of all electricity generated in the United States, primarily because photovoltaic cells remain expensive and relatively inefficient. But solar may not be such a marginal power source for long. Chemists at Idaho National Laboratory and Idaho State University have invented a way to manufacture highly precise, uniform nanoparticles to order. The technology, Precision Nanoparticles, has the potential to vastly improve the solar cell and further spur the growing nanotech revolution. A scientific gold rush Nanoparticles are motes of matter tens of thousands of times smaller than the width of a human hair. Because they're so small, a large percentage of nanoparticles' atoms reside on their surfaces rather than in their interiors. This means surface interactions dominate nanoparticle behavior. And, for this reason, they often have different characteristics and properties than larger chunks of the same material. While scientists have just begun to exploit nanoparticles, they already show great promise in a number of fields, from medicine to manufacturing to energy. For example, embedding certain nanoparticle types in building materials makes structures stronger and more corrosion-resistant. And nano-engineered transistors are smaller, faster and more efficient than traditional ones. "Nanoparticles are the scientific gold rush of the next generation," says INL chemist Bob Fox, who helped develop the Precision Nanoparticles technology. "They'll change our lives the way personal computers have." Because the properties of nanoparticles are so size-dependent, any little dimensional tweak can make a big difference. Thus a key to harnessing the potential of nanoparticles lies in the ability to produce them at certain prescribed sizes, with tiny margins of error. This capability has proven elusive, but it is just what Precision Nanoparticles delivers. A new way to make nanoparticles A few years ago, Fox and ISU chemists Joshua Pak and Rene Rodriguez began looking for a better way to make semiconducting components for solar cells. Specifically, they wanted to improve how raw materials are transformed into semiconducting nanoparticles. The industry's established method of doing this is relatively imprecise and energy-intensive, requiring temperatures around 300 degrees Celsius. The team hit upon the idea of using "supercritical" carbon dioxide to streamline the reaction. Supercritical fluids are a bit like a mix between a gas and a liquid. They can diffuse through solids, for example, but also dissolve substances like a liquid does. Supercritical carbon dioxide has been used for years to decaffeinate coffee. But when Fox, Pak and Rodriguez introduced supercritical carbon dioxide into their reaction vessel, the only immediately noticeable result was a thick yellow goop. "We thought it was a failed experiment," Fox says. But when the chemists looked more closely, they discovered the goop was full of very small, incredibly uniform semiconducting nanoparticles. The same reaction, roughly, that industry uses to transform raw materials into semiconducting nanoparticles had taken place — but it generated a better, less variable product. "We didn't expect that doing this would give us such homogeneity," Fox says. "That was really exciting." And because the new reaction could proceed at a much lower temperature — 65 degrees Celsius rather than 300 — it also promised to save a great deal of money and energy. After tinkering with the reaction, Fox, Pak and Rodriguez figured out how to control nanoparticle size with unprecedented precision. They can now produce prescribed particles between 1 and 100 nanometers, hitting the mark every time with great accuracy. In July, R&D magazine recognized the breakthrough technology as one of its top 100 innovations of 2009 — a prestigious award commonly referred to as an "Oscar of invention". And in September, the work won the Early-Stage Innovation of the Year prize in the Stoel Rives Idaho Innovation Awards. Fox, Pak and Rodriguez have licensed the technology to Precision Nanoparticles, Inc. The relatively new Seattle company is poised to begin production of tailor-made nanoparticles for the photovoltaic industry. A better solar cell The aims of the INL and ISU chemists — and of Precision Nanoparticles, Inc. — are to make solar cells more efficient and, ultimately, solar energy more practical. In a solar cell, photons strike atoms of a semiconducting material — historically, silicon — knocking loose some electrons. These liberated electrons then flow in a single direction, generating direct-current electricity. The amount of energy needed to jar electrons loose is specific to each material and corresponds to only a tiny sliver of the sun's radiation spectrum. This fact explains why the efficiency of most current cells maxes out at around 20 percent. To knock an electron free from silicon, for example, an incoming photon must have an energy of about 1.3 electron volts. This energy is known as silicon's band gap, and it corresponds to a photon wavelength of 950 nanometers or so. Photons with lower energies — and thus longer wavelengths — won't do the job. Shorter-wavelength photons will, but their energy above 1.3 electron volts is wasted, dissipated as heat. This is a big deal, because the most abundant photons from sunlight occur between 500 and 600 nanometers (which our eyes register as greens and yellows) — meaning that most current photocells waste a lot of energy. Engineers have been working hard to harness more of the solar spectrum, to design cells that put low-energy photons to work and use high-energy photons more efficiently. One way to do this is to build composite cells with layers of different semiconductors. Slapping a film of copper indium sulfide atop a band of silicon, say, increases a cell's photon-catching power. But building such devices is expensive and technologically tricky. "The different layers don't play well together," Fox says. That's where the Precision Nanoparticles technology comes in. One of the many properties that changes with a nanoparticle's size is its band gap. Because Fox and his team learned how to control nanoparticle dimensions so precisely, it may soon be possible to manufacture — from a single material — semiconductor building blocks tuned to specific wavelengths of light. A photovoltaic cell made of such building blocks could capture huge swathes of the solar energy spectrum. And since the cells would contain only a single semiconducting material, they would be much cheaper, more efficient and easier to construct than current multi-layer designs. Some cells' semiconductor nanoparticles, Fox believes, could even be tuned to pick up infrared wavelengths — heat, which radiates off rocks, buildings, roads and parking lots deep into the night. "So your solar panel could be working long after you've gone to bed," he says. Beyond solar power While Precision Nanoparticles' most immediate applications come in the field of its birth, photovoltaics, potential uses don't stop there. For example, the technology could also greatly advance ultracapacitor research. Ultracapacitors store electrical energy quickly and effectively, and they may someday replace batteries in electric cars and plug-in hybrids. At least one material, vanadium nitride, has much higher ultracapacitance in nano-form -but only if the nanoparticles are of strictly uniform size, Fox says. To fully blossom, the nanotech revolution will require the control needed to produce such uniformity. Technologies like that developed by Fox, Pak and Rodriguez may be able to provide this control, delivering particles of predictable size with predictable properties. As a result, nanoparticles could find their way into more designs, and more products. "The only thing limiting us at this point is our imagination," Fox says. Source: Idaho National Laboratory

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Today, at an international ESO/CAUP exoplanet conference in Porto, the team who built the High Accuracy Radial Velocity Planet Searcher, better known as HARPS, the spectrograph for ESO's 3.6-metre telescope, reports on the incredible discovery of some 32 new exoplanets, cementing HARPS's position as the world’s foremost exoplanet hunter. This result also increases the number of known low-mass planets by an impressive 30%. Over the past five years HARPS has spotted more than 75 of the roughly 400 or so exoplanets now known.

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NASA's Interstellar Boundary Explorer, or IBEX, spacecraft has made it possible for scientists to construct the first comprehensive sky map of our solar system and its location in the Milky Way galaxy. The new view will change the way researchers view and study the interaction between our galaxy and sun.

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A study published in Science and reviewed by F1000 Biology members Venkatesh Murthy and Jakob Sorensen reveals that our brains have the amazing ability to be energy efficient.

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Any child can tell you that a magnet has a “north” and a “south” pole, and that if you break it into two pieces, you invariably get two smaller magnets with two poles of their own. But scientists have spent the better part of the last eight decades trying to find, in essence, a magnet with only one pole. A team working at the National Institute of Standards and Technology (NIST) has found one.* In 1931, Paul Dirac, one of the rock stars of the physics world, made the somewhat startling prediction that “magnetic monopoles,” or particles possessing only a single pole—either north or south—should exist. His conclusion stemmed from examining a famous set of equations that explains the relationship between electricity and magnetism. Maxwell’s equations apply to long-known electric monopole particles, such as negatively charged electrons and positively charged protons; but despite Dirac’s prediction, no one has found magnetic monopole particles. Now, a research team working at NIST’s Center for Neutron Research (NCNR), led by Hiroaki Kadowaki of Tokyo Metropolitan University, has found the next best thing. By creating a compound that under certain conditions forms large, molecule-sized monopoles that behave exactly as the predicted particles should, the team has found a way to explore magnetic monopoles in the laboratory, not just on the chalkboard. (Another research team, working simultaneously, published similar findings in Science last month.**) “These are not the monopole particles Dirac predicted—ours are huge in comparison—but they behave like them in every way,” says Jeff Lynn, a NIST physicist. “Their properties will allow us to test how theoretical monopole particles should behave and interact.” The team created their monopoles in a compound made of oxygen, titanium and dysprosium that, when cooled to nearly absolute zero, forms what scientists call “spin ice.” The material freezes into four-sided crystals (a pyramid with a triangular base) and the magnetic orientation, or “spin,” of the ions at each of the four tips align so that their spins are balanced—two spins point inward and two outward. But using neutron beams at the NCNR, the team found they could knock one of the spins askew so that instead three point in, one out … “creating a monopole, or at least its mathematical equivalent,” Lynn said. Because every crystal pyramid shares its four tips with adjacent pyramids, flipping the spin of one tip creates an “anti-monopole” in the next pyramid over. The team has created monopole-antimonopole pairs repeatedly in a relatively large chunk of the spin ice, allowing them to confirm the monopoles’ existence through advanced imaging techniques such as neutron scattering. While the findings will not tell the team where in the universe to search for Dirac’s still-elusive magnetic monopole particles, Lynn says that examining the spin ice will permit scientists to test certain predictions about monopoles. “Maxwell’s equations indicate that monopoles should obey Coulomb’s Law, which indicates their interaction should weaken as distance between them increases,” he says. “Using the spin ice crystals, we can test ideas like this.” * H. Kadowaki, N. Doi, Y. Aoki, Y. Tabata, T.J. Sato, J.W. Lynn, K. Matsuhira and Z. Hiroi. Observation of magnetic monopoles in spin ice. Journal of the Physical Society of Japan,78, No. 10, Oct. 13, 2009. (The team first presented their findings in an invited talk at the International Conference on Neutron Scattering in May 2009.) ** D. J. P. Morris, et al. Dirac strings and magnetic monopoles in spin ice Dy2Ti2O7. Science, online publication Sept. 3, 2009. Source: NIST

Method Could Help Police, Firefighters, Elderly

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University of Utah engineers showed that a wireless network of radio transmitters can track people moving behind solid walls. The system could help police, firefighters and others nab intruders, and rescue hostages, fire victims and elderly people who fall in their homes. It also might help retail marketing and border control.

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Using updated information, NASA scientists have recalculated the path of a large asteroid. The refined path indicates a significantly reduced likelihood of a hazardous encounter with Earth in 2036.