Science News

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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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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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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.

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Scientists have been warning for decades that the explosion of human activity since the industrial revolution is pushing the Earth's resources and natural systems to their limits.
The data confirm that 6 billion people are capable of generating a global geophysical force the equivalent to some of the great forces of nature – just by going about their daily lives.

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NASA's Spitzer Space Telescope has discovered an enormous ring around Saturn -- by far the largest of the giant planet's many rings. The new belt lies at the far reaches of the Saturnian system, with an orbit tilted 27 degrees from the main ring plane.

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Quantum mechanics could help build ultra-high-resolution electron microscopes that won't destroy living cells, according to MIT electrical engineers.

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A new research project at Idaho National Laboratory (INL) and Argonne National Laboratory will use an innovative approach to learn how to get more use from nuclear fuel. The project demonstrates the U.S. Department of Energy's commitment to conduct more basic research on nuclear fuel recycling. Thanks to $2 million in funding from DOE's Office of Science, INL researcher Gilles Youinou aims to give nuclear scientists a better understanding of how elements within fuel rods respond to neutron irradiation.

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In 1980, Luis Alvarez and his collaborators stunned the world with their discovery that an asteroid impact 65 million years ago probably killed off the dinosaurs and much of the the world's living organisms. But ever since, there has been an ongoing debate about how long it took for life to return to the devastated planet and for ecosystems to bounce back. Now, researchers from MIT and their collaborators have found that at least some forms of microscopic marine life — the so called "primary producers," or photosynthetic organisms such as algae and cyanobacteria in the ocean — recovered within about a century after the mass extinction. Previous research had indicated the process might have taken millions of years. It has taken so long to uncover the quick recovery because previous studies looked mostly at fossils in the layers of sediment from that period, and apparently the initial recovery was dominated by tiny, soft-bodied organisms such as cyanobacteria, which do not have shells or other hard body parts that leave fossil traces. The new research looked instead for "chemical fossils" — traces of organic molecules (compounds composed of mostly carbon and hydrogen) that can reveal the presence of specific types of organisms, even though all other parts of the organisms themselves are long gone. The new research, published in the Oct. 2 issue of Science, was led by Julio Sepúlveda, an MIT postdoc who carried out part of the work while still a graduate student at the University of Bremen, Germany, and MIT Professor of Geobiology Roger Summons, among others. The team had two major advantages that helped to make the new findings possible. One was a section of the well-known cliff face at Stevns Klint, Denmark, that happens to have an unusually thick layer of sediment from the period of the mass extinction — about 40 centimeters thick, compared to the few cm thickness of the layers that Alvarez originally studied from that period at Gubbio (Italy) and Stevns Klint (Denmark). And team members tapped one of the most powerful Gas Chromatograph-Mass Spectrometers (GC-MS) in the world, a device that can measure minute quantities of different molecules in the rock. MIT's advanced GC-MS is one of only a few such powerful instruments currently available at U.S. universities. When people look at microfossils in the sediments from the period but are unable to detect the chemical biomarkers with the level of sensitivity the MIT team was able to achieve, they "miss a big part of the picture," Sepúlveda says. "Many of these microorganisms" that were detected through molecular signatures "are at the base of the food chain, but if you don't look with biochemical techniques you miss them." The analysis clarified the sequence of events after the big impact. Immediately after the impact, certain areas of the ocean were devoid of oxygen and hostile to most algae, but close to the continent, microbial life was inhibited for only a relatively short period: in probably less than 100 years, algal productivity showed the first signs of recovery. In the open ocean, however, this recovery took much longer: previous studies have estimated that the global ocean ecosystem did not return to its former state until 1 to 3 million years following the impact. Because of the rebound of primary producers, Sepúlveda says "very soon after the impact, the food supply was not likely a limitation" for other organisms, and yet "the whole ecology of the system remained disrupted" and took much longer to recover. The findings provide observational evidence supporting models suggesting that global darkness after the impact was rather short. "Primary productivity came back quickly, at least in the environment we were studying," says Summons, referring to the near-shore environment represented by the Danish sediments. "The atmosphere must have cleared up rapidly," he says. "People will have to rethink the recovery of the ecosystems. It can't be just the lack of food supply" that made it take so long to recover. The team hopes to be able to study other locations with relatively thick deposits from the extinction aftermath, to determine whether the quick recovery really was a widespread phenomenon after the mass extinction. These findings seem to rule out one theory about how the global ecosystem responded to the impact, which held that for more than a million years there was a "Strangelove ocean" — a reference to the post-apocalyptic scenario in the movie Dr. Strangelove — in which all the primary producers remained absent for a prolonged period, Summons says. In addition to Sepúlveda and Summons, the work was carried out by Jens Wendler of the Friedrich-Schiller University in Jena, Germany, and Kai-Uwe Hinrichs of the University of Bremen. The work was funded by the DFG, European Graduate College Europrox and the NASA Astrobiology and Exobiology Programs. Source: MIT