Computer Simulations Indicate Calcium Carbonate Has a Dense Liquid Phase

 Computer simulations conducted at the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) could help scientists make sense of a recently observed and puzzling wrinkle in one of nature's most important chemical processes. It turns out that calcium carbonate -- the ubiquitous compound that is a major component of seashells, limestone, concrete, antacids and myriad other naturally and industrially produced substances -- may momentarily exist in liquid form as it crystallizes from solution.

Calcium carbonate is a huge player in the planet's carbon cycle, so any new insight into how it behaves is potentially big news. The prediction of a dense liquid phase during the conversion of calcium carbonate to a solid could help scientists understand the response of marine organisms to changes in seawater chemistry due to rising atmospheric CO₂ levels. It could also help them predict the extent to which geological formations can act as carbon storage reservoirs, among other examples.

The research is published in the August 23 issue of the journalScience. It was performed in support of the Center for Nanoscale Control of Geologic CO₂, an Energy Frontier Research Center established at Berkeley Lab by the U.S. Department of Energy.

The research may also reconcile some confounding experimental observations. For more than a century, scientists believed that crystals nucleate from solution by overcoming an energy barrier. But recent studies of calcium carbonate revealed the presence of nanoscopic clusters which, under certain conditions, appear to circumvent the barrier by following an alternative aggregation-based crystallization pathway.

"Because nucleation is ubiquitous in both natural and synthetic systems, those findings have forced diverse scientific communities to reevaluate their longstanding view of this process," says the study's co-corresponding author Jim De Yoreo, formerly of Berkeley Lab and now a scientist at Pacific Northwest National Laboratory.

The Berkeley Lab-led team used molecular dynamics simulations to study the onset of calcium carbonate formation. The simulations predict that in sufficiently supersaturated calcium carbonate solutions, nanoscale dense liquid droplets can spontaneously form. These droplets then coalesce to form an amorphous solid prior to crystallization.

The findings support the aggregation-based mechanism of calcium carbonate formation. They also indicate that the presence of the nanoscale phase is consistent with a process called liquid-liquid separation, which is well known in alloys and polymers, but unexpected for salt solutions.

"Our simulations suggest the existence of a dense liquid form of calcium carbonate," says co-corresponding author Adam Wallace. He conducted the research while a post-doctoral researcher in Berkeley Lab's Earth Sciences Division, and is now an assistant professor in the Department of Geological Sciences at the University of Delaware.

"This is important because it is an as-yet unappreciated component of the carbon cycle," adds Wallace. "It also provides a means of explaining the unusual presence of nanoscale clusters in solution within the context of established physical mechanisms."

This research was supported by the U.S. Department of Energy's Office of Science through the Energy Frontier Research Center program established in 2009. The work was conducted at Berkeley Lab's Molecular Foundry, a Department of Energy national user facility. The research also used resources of the Department of Energy's National Energy Research Scientific Computing Center, which is located at Berkeley Lab.

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Wolves Howl Because They Care: Social Relationship Can Explain Variation in Vocal Production

 When a member of the wolf pack leaves the group, the howling by those left behind isn't a reflection of stress but of the quality of their relationships. So say researchers based on a study of nine wolves from two packs living at Austria's Wolf Science Center that appears in Current Biology, a Cell Press publication, on August 22.

The findings shed important light on the degree to which animal vocal production can be considered as voluntary, the researchers say.

"Our results suggest the social relationship can explain more of the variation we see in howling behavior than the emotional state of the wolf," says Friederike Range of the Messerli Research Institute at the University of Veterinary Medicine Vienna. "This suggests that wolves, to a certain extent, may be able to use their vocalizations in a flexible way."

Scientists have known very little about why animals make the sounds that they do. Are they uncontrollable emotional responses? Or do animals have the ability to change those vocalizations based on their own understanding of the social context?

At the Wolf Science Center, human handlers typically take individual wolves out for walks on a leash, one at a time. On those occasions, they knew, the remaining pack mates always howl.

To better understand why, Range and her colleagues measured the wolves' stress hormone levels. They also collected information on the wolves' dominance status in the pack and their preferred partners. As they took individual wolves out for long walks, they recorded the reactions of each of their pack mates.

Those observations show that wolves howl more when a wolf they have a better relationship with leaves the group and when that individual is of high social rank. The amount of howling did not correspond to higher levels of the stress hormone cortisol.

"Our data suggest that howling is not a simple stress response to being separated from close associates but instead may be used more flexibly to maintain contact and perhaps to aid in reuniting with allies," Range says.

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Space Slinky: Jet of Superheated Gas -- 5,000 Light-Years Long -- Ejected from Supermassive Black Hole

 More than thirteen years of observations from NASA's Hubble Space Telescope have allowed astronomers to assemble time-lapse movies of a 5,000-light-year-long jet of superheated gas being ejected from a supermassive black hole in the center of the giant elliptical galaxy M87.

The movies promise to give astronomers a better understanding of how active black holes shape galaxy evolution. While matter drawn completely into a black hole cannot escape its enormous gravitational pull, most infalling material drawn toward it first joins an orbiting region known as an accretion disk encircling the black hole. Magnetic fields surrounding the black hole are thought to entrain some of this ionized gas, ejecting it as very high-velocity jets.

"Central supermassive black holes are a key component in all big galaxies," said Eileen T. Meyer of the Space Telescope Science Institute (STScI) in Baltimore, Md., the Hubble study's lead author. "Most of these black holes are believed to have gone through an active phase, and black-hole-powered jets from this active phase play a key role in the evolution of galaxies. By studying the details of this process in the nearest galaxy with an optical jet, we can hope to learn more about galaxy formation and black hole physics in general."

The Hubble movies reveal for the first time that the jet's river of plasma travels in a spiral motion. This motion is considered strong evidence that the plasma may be traveling along a magnetic field, which the team thinks is coiled like a helix. The magnetic field is believed to arise from a spinning accretion disk of material around a black hole. Although the magnetic field cannot be seen, its presence is inferred by the confinement of the jet along a narrow cone emanating from the black hole.

"We analyzed several years' worth of Hubble data of a relatively nearby jet, which allowed us to see lots of details," Meyer said. "The only reason you see the distant jet in motion at all over just a few years is because it is traveling very fast."

Meyer found evidence for the magnetic field's suspected helical structure in several locations along the jet. In the outer part of the M87 jet, for example, one bright gas clump, called knot B, appears to zigzag, as if it were moving along a spiral path. Several other gas clumps along the jet also appear to loop around an invisible structure. "Past observations of black hole jets couldn't distinguish between radial motion and side-to-side motion, so they didn't provide us with detailed information of the jet's behavior," Meyer explained.

M87 resides at the center of the neighboring Virgo cluster of roughly 2,000 galaxies, located 50 million light-years away. The galaxy's monster black hole is several billion times more massive than our Sun.

In addition, the Hubble data provided information on why the jet is composed of a long string of gas blobs, which appear to brighten and dim over time.

"The jet structure is very clumpy. Is this a ballistic effect, like cannonballs fired sequentially from a cannon?" Meyer asked. "Or, is there some particularly interesting physics going on, such as a shock that is magnetically driven?"

Meyer's team found evidence for both scenarios. "We found things that move quickly," Meyer said. "We found things that move slowly. And, we found things that are stationary. This study shows us that the clumps are very dynamic sources."

The research team spent eight months analyzing 400 observations from Hubble's Wide Field Planetary Camera 2 and Advanced Camera for Surveys. The observations were taken from 1995 to 2008. Several team members, however, have been observing M87 for 20 years. Only Hubble's sharp vision allowed the research team to measure the jet's slight motion in the sky over 13 years. Meyer's team also measured features in the hot plasma as small as 20 light-years wide.

It's too soon to tell whether all black-hole-powered jets behave like the one in M87. That's why Meyer plans to use Hubble to study three more jets. "It's always dangerous to have exactly one example because it could be a strange outlier," Meyer said. "The M87 black hole is justification for looking at more jets."

The team's results will appear Aug. 22 in the online issue of The Astrophysical Journal Letters.

In addition to Eileen Meyer, other members of the science team are William Sparks, John Biretta, Jay Anderson, Sangmo Tony Sohn, and Roeland van der Marel of STScI; Colin Norman of Johns Hopkins University, Baltimore, Md.; and Masanori Nakamura of Academia Sinica, Taipei, Taiwan.

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Mending a Broken Heart? Scientists Transform Non-Beating Human Cells Into Heart-Muscle Cells

In the aftermath of a heart attack, cells within the region most affected shut down. They stop beating. And they become entombed in scar tissue. But now, scientists at the Gladstone Institutes have demonstrated that this damage need not be permanent -- by finding a way to transform the class of cells that form human scar tissue into those that closely resemble beating heart cells.

Last year, these scientists transformed scar-forming heart cells, part of a class of cells known as fibroblasts, into beating heart-muscle cells in live mice. And in the latest issue of Stem Cell Reports, researchers in the laboratory of Gladstone Cardiovascular and Stem Cell Research Director Deepak Srivastava, MD, reveal that they have done the same to human cells in a petri dish.

"Fibroblasts make up about 50% of all cells in the heart and therefore represent a vast pool of cells that could one day be harnessed and reprogrammed to create new muscle," said Dr. Srivastava, who is also a professor at the University of California, San Francisco, with which Gladstone is affiliated. "Our findings here serve as a proof of concept that human fibroblasts can be reprogrammed successfully into beating heart cells."

In 2012, Dr. Srivastava and his team reported in the journalNature that fibroblasts could be reprogrammed into beating heart cells by injecting just three genes, together known as GMT, into the hearts of live mice that had been damaged by a heart attack. They reasoned that the same three genes could have the same effect on human cells. But initial experiments on human fibroblasts from three sources -- fetal heart cells, embryonic stem cells and neonatal skin cells -- revealed that the GMT combination alone was not sufficient.

"When we injected GMT into each of the three types of human fibroblasts, nothing happened -- they never transformed -- so we went back to the drawing board to look for additional genes that would help initiate the transformation," said Gladstone Staff Scientist Ji-dong Fu, PhD, the study's lead author. "We narrowed our search to just 16 potential genes, which we then screened alongside GMT, in the hopes that we could find the right combination."

The research team began by injecting all candidate genes into the human fibroblasts. They then systematically removed each one to see which were necessary for reprogramming, and which were dispensable. In the end, the team found that injecting a cocktail of five genes -- the 3-gene GMT mix plus the genes ESRRG and MESP1 -- were sufficient to reprogram the fibroblasts into heart-like cells. They then found that with the addition of two more genes, called MYOCD and ZFPM2, the transformation was even more complete. To help things along, the team initiated a chemical reaction known as the TGF-ß signaling pathway during the early stages of reprogramming, which further improved reprogramming success rates.

"While almost all the cells in our study exhibited at least a partial transformation, about 20% of them were capable of transmitting electrical signals -- a key feature of beating heart cells," said Dr. Fu. "Clearly, there are some yet-to-be-determined barriers preventing a more complete transformation for many of the cells. For example, success rates might be improved by transforming the fibroblasts within living hearts rather than in a dish -- something we also observed during our initial experiments in mice."

The immediate next steps are to test the five-gene cocktail in hearts of larger mammals, such as pigs. Eventually, the team hopes that a combination of small, drug-like molecules could be developed to replace the cocktail, offering a safer and easier method of delivery.

"With more than five million heart attack survivors in the United States, who have hearts that are no longer able to beat at full capacity, our findings -- along with recently published findings from our colleagues -- come at a critical time," added Dr. Srivastava. "We've now laid a solid foundation for developing a way to reverse the damage -- something previously thought impossible -- and changing the way that doctors may treat heart attacks in the future."

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Sea Ice Decline Spurs the Greening of the Arctic

Sea ice decline and warming trends are changing the vegetation in nearby arctic coastal areas, according to two University of Alaska Fairbanks scientists.

Uma Bhatt, an associate professor with UAF's Geophysical Institute, and Skip Walker, a professor at UAF's Institute of Arctic Biology, contributed to a recent review of research on the response of plants, marine life and animals to declining sea ice in the Arctic.

"Our thought was to see if sea ice decline contributed to greening of the tundra along the coastal areas," Bhatt said. "It's a relatively new idea."

The review appeared in a recent issue of Science magazine. It is a close, comprehensive look at how the losses of northern sea ice affect surrounding areas. Bhatt and Walker were two of ten authors.

The review team analyzed 10 years worth of data and research on the subject. The findings show that sea ice loss is changing marine and terrestrial food chains. Sea-ice disappearance means a loss of sea-ice algae, the underpinning of the marine food web. Larger plankton is thriving, replacing smaller, but more nutrient dense plankton. What that means exactly is not yet understood.

Above water, loss of sea ice has destroyed old pathways of animal migration across sea ice while opening new pathways for marine animals in others. Some animals and plants will become more isolated. In the case of the farthest north and coldest parts of the Arctic, entire biomes may be lost without the cooling effects of disappearing summer sea ice.

Walker, a plant biologist, says warming soils provide an opportunity for new vegetation to grow where less vegetation occurred previously. This contributes to a general greening of the Arctic that is visible from space. Bhatt, an atmospheric scientist, examined a 1982-2010 time series of remote sensing data to examine trends in sea ice, land-surface temperatures and changes in the vegetation abundance.

A surprise and puzzling finding shows that despite a general warming and greening of Arctic lands in North America, some areas in northern Russia and along the Bering Sea coast of Alaska are showing recent cooling trends and declines in vegetation productivity.

"We don't know why," Bhatt said.

This all illustrates the complexity of the arctic system and why scientists from different disciplines should work together to understand it, Bhatt said. The review article is one of the first steps in this direction.

"It's not a simple story here," Bhatt said. "I'm an atmospheric scientist and Skip (Walker) is a plant biologist. We have had many conversations to understand each other so we might better understand what's happening in the Arctic."

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Lab-Made Complexes Are 'Sun Sponges'

A ring of protein and pigments, half synthetic and half natural, can be used to quickly prototype light-harvesting antennas that absorb more sunlight than fully natural ones

In diagrams it looks like a confection of self-curling ribbon with bits of bling hung off the ribbon here and there. In fact it is a carefully designed ring of proteins with attached pigments that self-assembles into a structure that soaks up sunlight.

The scientists who made it call it a testbed, or platform for rapid prototyping of light-harvesting antennas-structures found in plants and photosynthesizing bacteria-that take the first step in converting sunlight into usable energy. The antennas consist of protein scaffolding that holds pigment molecules in ideal positions to capture and transfer the sun's energy. The number and variety of the pigment molecules determines how much of the sun's energy the antennas can grab and dump into an energy trap.

In the August 6, 2013 online edition of Chemical Science, a new publication of the Royal Society of Chemistry, the scientists describe two prototype antennas they've built on their testbed. One incorporated synthetic dyes called Oregon Green and Rhodamine Red and the other combined Oregon Green and a synthetic version of the bacterial pigment bacteriochlorophyll that absorbs light in the near-infrared region of the spectrum.

Both designs soak up more of the sun's spectrum than native antennas in purple bacteria that provided the inspiration and some components for the testbed. The prototypes were also far easier to assemble than synthetic antennas made entirely from scratch. In this sense they offer the best of both worlds, combining human synthetic ingenuity with the repertoire of robust chemical machinery selected by evolution.

One day a two-part system (consisting of an antenna and a second unit called a reaction center) might serve as a miniature power outlet into which photochemical modules could be plugged. The sun's energy could then be used directly to split water, generate electricity, or build molecular-scale devices.

The project was organized by the Photosynthetic Antenna Research Center (PARC) at Washington University in St. Louis, one of 46 Energy Frontier Research Centers funded by the Department of Energy in 2009. The team tapped the expertise of many PARC-affiliated scientists, including Dewey Holten and Christine Kirmaier of Washington University in St. Louis, Paul Loach and Pamela Parkes-Loach of Northwestern University, Jonathan Lindsey of North Carolina State University, David Bocian of the University of California, Riverside, and Neil Hunter of University of Sheffield in the United Kingdom.

Designer pigments

Nature has evolved many different systems to capture the sun's energy, but they all rely on pigments, molecules that appear strongly colored because they are selectively absorbing some wavelengths, or colors, of light in the solar spectrum.

The pigment we are most familiar with is chlorophyll, the molecule that makes plants appear green. But that green color is a tipoff about the plant's solar absorption. We see plants as green because they're reflecting the green part of the spectrum and absorbing in the violet and the red parts of the spectrum instead.

Not only do plants miss the middle of the visible spectrum, they also miss light at wavelengths longer than we can see, including near-infrared photons absorbed by photosynthetic bacteria. The accessory pigments such as carotenoids that give leaves their splendid fall colors fill some gaps but large swaths of the solar spectrum pass through untouched.

"Since plant pigments actually reject a lot of the light that falls on them," Hunter said, "potentially there's a lot of light you could gather that plants don't bother with."

The team relies on Jonathan Lindsey to design and synthesize pigments that can absorb at wavelengths that will fill some of the holes in the absorption of natural systems. "It can't be done from first principles," Lindsey said, "but we have a large database of known absorbers and so drawing on that and reasoning by analogy we can design a large variety of pigments."

More than one synthetic or natural pigment can be attached to the protein scaffolding. "The prototypes in the Chemical Sciencepaper both have two but ultimately we'd like to add three or four or even more," said Lindsey. "One of our goals is to understand to what extent the protein can be derivatized with pigments."

"The effectiveness of the design depends not only on having extra pigments but also pigments able to talk to one another, so that energy that lands on any one of them is able to hop onto the next pigment and then to the next one after that. They have to work together," Hunter explained.

"The energy cascades down like a waterfall," Hunter said. "So you pour the energy at the top of the waterfall and it hits one pigment and jumps to the next and the next and finally to the pigment at the bottom, which in terms of energy is the pigment that is reddest in color."

Self assembly line

If broad spectral coverage was one goal of the project, another was to avoid the laborious synthesis typically required to make designer light-harvesting antennas.

Fortunately light-harvesting antennas from purple bacteria are modular devices that self assemble under appropriate conditions, conditions that have been worked out by team members Paul Loach and Pamela Parkes-Loach. The basic module is a pair of peptides (short proteins) called alpha and beta that in turn house two bacteriochlorophyll molecules that both absorb light and act as the trap for all the harvested energy.

Thanks to the chemical affinities of the components, they self-assemble into dyads when added together in detergent (detergent is used instead of water alone because parts of the peptides shun water). By adjusting the detergent concentration and temperature, the dyads form rings, which in native antenna contain up to 16 alpha/beta dyads and thus as many as 32 bacteriochlorophylls.

In the testbed, the scientists use peptides that have been slightly modified from the native amino acid sequence for attachment of the extra pigments to increase solar spectral coverage. The attachment sites were chosen to avoid disrupting the self assembly of the components into dyads and dyads into rings.

"This is an example of what the field would refer to as semi-synthesis," Lindsey said. "We take naturally occurring materials and combine them with synthetic ones to make something that doesn't exist in nature. By taking lots of material from nature we can make molecules that are architecturally more complex than those we can make from scratch."

Once assembled, the antenna are sent to the Holten/Kirmaier lab, where a variety of spectroscopic methods including ultra-fast laser spectroscopy are used to excite each pigment molecule and to follow the energy transfer from one pigment to the next and down to the target bacteriochlorophyll. Given the right pigments in the right locations, this transfer is extremely efficient, and little energy is lost on the way.

Samples also went to the Bocian laboratory where they are probed for structural integrity and to the Hunter laboratory where images are made of the rings, which are only 11 to 16 nanometers (a billionth of a meter) across and must be magnified tens of thousands of times to be visible.

"I've been working in photosynthesis for 50 years," said Loach, "and I can't think of many other times when there were so many good people with so many different talents coming together to try to solve problems. It's fun to be part of it and to see what comes out of the collaboration."

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Human Brains Are Hardwired for Empathy, Friendship

Perhaps one of the most defining features of humanity is our capacity for empathy -- the ability to put ourselves in others' shoes. A new University of Virginia study strongly suggests that we are hardwired to empathize because we closely associate people who are close to us -- friends, spouses, lovers -- with our very selves.

"With familiarity, other people become part of ourselves," said James Coan, a psychology professor in U.Va.'s College of Arts & Sciences who used functional magnetic resonance imaging brain scans to find that people closely correlate people to whom they are attached to themselves. The study appears in the August issue of the journal Social Cognitive and Affective Neuroscience.

"Our self comes to include the people we feel close to," Coan said.

In other words, our self-identity is largely based on whom we know and empathize with. Coan and his U.Va. colleagues conducted the study with 22 young adult participants who underwent fMRI scans of their brains during experiments to monitor brain activity while under threat of receiving mild electrical shocks to themselves or to a friend or stranger. The researchers found, as they expected, that regions of the brain responsible for threat response -- the anterior insula, putamen and supramarginal gyrus -- became active under threat of shock to the self. In the case of threat of shock to a stranger, the brain in those regions displayed little activity. However when the threat of shock was to a friend, the brain activity of the participant became essentially identical to the activity displayed under threat to the self.

"The correlation between self and friend was remarkably similar," Coan said. "The finding shows the brain's remarkable capacity to model self to others; that people close to us become a part of ourselves, and that is not just metaphor or poetry, it's very real. Literally we are under threat when a friend is under threat. But not so when a stranger is under threat."

Coan said this likely is because humans need to have friends and allies who they can side with and see as being the same as themselves. And as people spend more time together, they become more similar.

"It's essentially a breakdown of self and other; our self comes to include the people we become close to," Coan said. "If a friend is under threat, it becomes the same as if we ourselves are under threat. We can understand the pain or difficulty they may be going through in the same way we understand our own pain."

This likely is the source of empathy, and part of the evolutionary process, Coan reasons. "A threat to ourselves is a threat to our resources," he said. "Threats can take things away from us. But when we develop friendships, people we can trust and rely on who in essence become we, then our resources are expanded, we gain. Your goal becomes my goal. It's a part of our survivability."

People need friends, Coan added, like "one hand needs another to clap."

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High-Precision Measurement of Subatomic Shape Shifting and New Result On Differences Among Neutrino Masses

The international Daya Bay Collaboration has announced new results about the transformations of neutrinos -- elusive, ghostlike particles that carry invaluable clues about the makeup of the early universe. The latest findings include the collaboration's first data on how neutrino oscillation -- in which neutrinos mix and change into other "flavors," or types, as they travel -- varies with neutrino energy, allowing the measurement of a key difference in neutrino masses known as "mass splitting."

"Understanding the subtle details of neutrino oscillations and other properties of these shape-shifting particles may help resolve some of the deepest mysteries of our universe," said Jim Siegrist, Associate Director of Science for High Energy Physics at the U.S. Department of Energy (DOE), the primary funder of U.S. participation in Daya Bay.

U.S. scientists have played essential roles in planning and running of the Daya Bay experiment, which is aimed at filling in the details of neutrino oscillations and mass hierarchy that will give scientists new ways to test for violations of fundamental symmetries. For example, if scientists detect differences in the way neutrinos and antineutrinos oscillate that are beyond expectations, it would be a sign of charge-parity (CP) violation, one of the necessary conditions that resulted in the predominance of matter over antimatter in the early universe. The new results from the Daya Bay experiment about mass-splitting represent an important step towards understanding how neutrinos relate to the structure of our universe today.

"Mass splitting represents the frequency of neutrino oscillation," says Kam-Biu Luk of the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab), the Daya Bay Collaboration's Co-spokesperson, who identified the ideal site for the experiment. "Mixing angles, another measure of oscillation, represent the amplitude. Both are crucial for understanding the nature of neutrinos." Luk is a senior scientist in Berkeley Lab's Physics Division and a professor of physics at the University of California (UC) Berkeley.

The Daya Bay Collaboration, which includes more than 200 scientists from six regions and countries, is led in the U.S. by DOE's Berkeley Lab and Brookhaven National Laboratory (BNL). The Daya Bay Experiment is located close to the Daya Bay and Ling Ao nuclear power plants in China, 55 kilometers northeast of Hong Kong. The latest results from the Daya Bay Collaboration will be announced at the XVth International Workshop on Neutrino Factories, Super Beams and Beta Beams in Beijing, China.

"These new precision measurements are a great indication that our efforts will pay off with a deeper understanding of the structure of matter and the evolution of the universe -- including why we have a universe made of matter at all," says Steve Kettell, a Senior Scientist at BNL and U.S. Daya Bay Chief Scientist.

U.S. contributions to the Daya Bay experiment include coordinating detector engineering; perfecting the recipe for the liquid used to track neutrinos in the Daya Bay detectors; overseeing the photo-detector systems used to observe neutrino interactions and muons; building the liquid-holding acrylic vessels and the detector-filling and automated calibration systems; constructing the muon veto system; developing essential software and data analysis techniques; and managing the overall project.

Measuring neutrino mass and flavors

Neutrinos come in three "flavors" (electron, muon, and tau) and each of these exists as a mixture of three masses. Measuring oscillations of neutrinos from one flavor to another gives scientists information on the probability of each flavor occupying each mass state (the mixing angles) and the differences between these masses (mass splitting).

Daya Bay measures neutrino oscillation with electron neutrinos -- actually antineutrinos, essentially the same as neutrinos for the purpose of these kinds of measurements. Millions of quadrillions of them are created every second by six powerful reactors. As they travel up to two kilometers to underground detectors, some seem to disappear.

The missing neutrinos don't vanish; instead they have transformed, changing flavors and becoming invisible to the detectors. The rate at which they transform is the basis for measuring the mixing angle, and the mass splitting is determined by studying how the rate of transformation depends on the neutrino energy.

Daya Bay's first results were announced in March 2012 and established the unexpectedly large value of the mixing angle theta one-three, the last of three long-sought neutrino mixing angles. The new results from Daya Bay put the precise number for that mixing angle at sin2213=0.090 plus or minus 0.009. The improvement in precision is a result of having more data to analyze and having the additional measurements of how the oscillation process varies with neutrino energy.

The energy-dependence measurements also open a window to the new analysis that will help scientists tease out the miniscule differences among the three masses. From the KamLAND experiment in Japan, they already know that the difference, or "split," between two of the three mass states is small. They believe, based on the MINOS experiment at Fermilab, that the third state is at least five times smaller or five times larger. Daya Bay scientists have now measured the magnitude of that mass splitting, |Δm2ee|, to be (2.540.20)10-3 eV2.

The result establishes that the electron neutrino has all three mass states and is consistent with that from muon neutrinos measured by MINOS. Precision measurement of the energy dependence should further the goal of establishing a "hierarchy," or ranking, of the three mass states for each neutrino flavor.

MINOS, and the Super-K and T2K experiments in Japan, have previously determined the complementary effective mass splitting (Δm2μμ) using muon neutrinos. Precise measurement of these two effective mass splittings would allow calculations of the two mass-squared differences (Δm232 and Δm231) among the three mass states. KamLAND and solar neutrino experiments have previously measured the mass-squared difference Δm221 by observing the disappearance of electron antineutrinos from reactors about 100 miles from the detector and the disappearance of neutrinos from the sun

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A Brighter Method for Measuring the Surface Gravity of Distant Stars

Astronomers have found a clever new way to slice and dice the flickering light from a distant star in a way that reveals the strength of gravity at its surface. That is important because a star's surface gravity is one of the key properties that astronomers use to calculate a star's physical properties and assess its evolutionary state.

The new technique can also be used to significantly improve estimates of the sizes of the hundreds of exoplanets that have been discovered in the last 20 years. Current estimates have uncertainties ranging from 50 percent to 200 percent. Using the improved figures for the surface gravity of the host stars calculated by the new method should cut these uncertainties at least in half.

The technique was developed by a team of astronomers headed by Vanderbilt Professor of Physics and Astronomy Keivan Stassun and is described in the Aug. 22 issue of the journal Nature.

"Once you know a star's surface gravity then you only need one other measurement, its temperature, which is pretty easy to obtain, to determine its mass, size and other important physical properties," said Stassun.

"Measuring stellar surface gravities well has always been a difficult business," added Gibor Basri, professor of astronomy at the University of California, Berkeley who contributed to the study. "So it is a very pleasant surprise to find that the subtle flickering of a star's light provides a relatively easy way to do it."

"This actually could be the breakthrough we've needed to pin down the sizes of hundreds more stars and exoplanets," said Maria Womack, the program director at the National Science Foundation which funded the research. "Getting accurate sizes is critical to measuring exoplanet density, which has been a missing puzzle piece for so many planets. So, in addition to having implications for stellar evolution, this innovative work will be invaluable for identifying hundreds of exoplanets as either rocky or gaseous."

Measuring stellar gravity

There are three traditional methods for estimating a star's surface gravity: photometric, spectroscopic and asteroseismic. The new flicker method is simpler than the older methods and more accurate than all but one of them.

Photometric methods look at how bright a star is in different colors. This distribution is linked to its surface gravity, temperature and chemical composition. It is a relatively easy observation to make and can be performed even on fairly faint stars, but does not produce a very accurate figure for surface gravity, having an uncertainty range of 90 to 150 percent.

The spectroscopic technique is more involved and is limited to relatively bright stars, but it has a lower uncertainty range of 25 to 50 percent. It works by closely examining the narrow spectral bands of light emitted by the elements in the star's atmosphere. Generally speaking, high surface gravity widens the lines and lower surface gravity narrows them.

Asteroseismology is the gold standard, with accuracies of a few percent, but the measurements are even more difficult to make than spectroscopy and it is restricted to several hundred of the closest, brightest stars. The technique traces sound pulses that travel through the interior of a star at specific frequencies that are tied to its surface gravities. Small stars, like the sun, ring at a higher pitch while giant stars ring a lower pitch.

Much like asteroseismology, the new flicker method looks at variations in the star's brightness, In this case it zeroes in on variations that last eight hours or less. These variations appear to be linked to granulation, the network of small cells that cover the surface of a star that are caused by columns of gas rising from the interior. On stars with high surface gravity, the granulation is finer and flickers at a higher frequency. On stars with low surface gravity, the granulation is coarser and they flicker at a lower frequency.

Exquisitely simple

The new method is remarkably simple -- requiring only five lines of computer code to make the basic measurement -- substantially reducing the cost and effort required to calculate the surface gravities of thousands of stars.

"The spectroscopic methods are like surgery. The analysis is meticulous and involved and very fine-grained," said Stassun. "Flicker is more like ultrasound. You just run the probe around the surface and you see what you need to see. But its diagnostic power -- at least for the purpose of measuring gravity -- is as good if not better."

To determine the accuracy of the flicker method, they used it to calculate the surface gravity of stars that have been analyzed using asteroseismology. They found that it has an uncertainty of less than 25 percent, which is better than both the photometric and spectroscopic methods. Its major limitation is that it requires extremely high quality data taken over long time periods. But this is precisely the type of observations made by Kepler while it was searching for periodic dips in light caused when exoplanets cross the face of a star. So the Flicker method can be applied to the tens of thousands of stars already being monitored by Kepler.

"The exquisite precision of the data from Kepler allows us to monitor the churning and waves on the surfaces of stars," said team member Joshua Pepper, assistant professor of physics at Lehigh University. "This behavior causes subtle changes to a star's brightness on the time scale of a few hours and tells us in great detail how far along these stars are in their evolutionary lifetimes."

Playing with data yields discovery

Graduate student Fabienne Bastien was responsible for discovering that valuable information was embedded in starlight flicker. The discovery began when she was "playing around" with Kepler data using special data visualization software that Vanderbilt astronomers have developed for investigating large, multi-dimensional astronomy datasets.

[The data visualization tool that enabled this discovery, called Filtergraph, is free to use at filtergraph.vanderbilt.edu]

"I was plotting various parameters looking for something that correlated with the strength of stars' magnetic fields," said Bastien. "I didn't find it, but I did find an interesting correlation between certain flicker patterns and stellar gravity."

When Bastien showed her discovery to Stassun, he was intrigued. So they performed the operation on the archived Kepler light curves of a few hundred sun-like stars. When they plotted the overall variation in brightness of stars against their flicker intensity, they found an interesting pattern. As stars age, their overall variation falls gradually to a minimum. This is easily understood because the rate at which a star spins decreases gradually over time. As stars approach this minimum, their flicker begins to grow in complexity -- a characteristic that the astronomers have labeled "crackle." Once they reach this point, which they call the flicker floor, the stars appear to maintain this low level of variability for the rest of their lives, though it does appear to grow again as the stars approach the ends of their lives as red giant stars.

"This is an interesting new way to look at stellar evolution and a way to put our Sun's future evolution into a grander perspective," said Stassun.

When they ran their analysis on the sun's light curve, for example, the researchers found that it is hovering just above the flicker floor, leading them to the prediction that the sun is approaching a time when it will undergo a fundamental transition to a state of minimum variability and, in the process, will lose its spots.

The research was funded by the Vanderbilt Initiative in Data-intensive Astrophysics (VIDA) and National Science Foundation grants AST-0849736 and AST-1009810.

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Computer Can Read Letters Directly from the Brain

 By analysing MRI images of the brain with an elegant mathematical model, it is possible to reconstruct thoughts more accurately than ever before. In this way, researchers from Radboud University Nijmegen have succeeded in determining which letter a test subject was looking at.

The journal Neuroimage has accepted the article, which will be published soon.

Functional MRI scanners have been used in cognition research primarily to determine which brain areas are active while test subjects perform a specific task. The question is simple: is a particular brain region on or off? A research group at the Donders Institute for Brain, Cognition and Behaviour at Radboud University has gone a step further: they have used data from the scanner to determine what a test subject is looking at.

The researchers 'taught' a model how small volumes of 2x2x2 mm from the brain scans -- known as voxels -- respond to individual pixels. By combining all the information about the pixels from the voxels, it became possible to reconstruct the image viewed by the subject. The result was not a clear image, but a somewhat fuzzy speckle pattern. In this study, the researchers used hand-written letters.

Prior knowledge improves model performance

'After this we did something new', says lead researcher Marcel van Gerven. 'We gave the model prior knowledge: we taught it what letters look like. This improved the recognition of the letters enormously. The model compares the letters to determine which one corresponds most exactly with the speckle image, and then pushes the results of the image towards that letter. The result was the actual letter, a true reconstruction.'

'Our approach is similar to how we believe the brain itself combines prior knowledge with sensory information. For example, you can recognise the lines and curves in this article as letters only after you have learned to read. And this is exactly what we are looking for: models that show what is happening in the brain in a realistic fashion. We hope to improve the models to such an extent that we can also apply them to the working memory or to subjective experiences such as dreams or visualisations. Reconstructions indicate whether the model you have created approaches reality.'

Improved resolution; more possibilities

'In our further research we will be working with a more powerful MRI scanner,' explains Sanne Schoenmakers, who is working on a thesis about decoding thoughts. 'Due to the higher resolution of the scanner, we hope to be able to link the model to more detailed images. We are currently linking images of letters to 1200 voxels in the brain; with the more powerful scanner we will link images of faces to 15,000 voxels.'

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'Zombie Vortices' May Be Key Step in Star Formation

A new theory by fluid dynamics experts at the University of California, Berkeley, shows how "zombie vortices" help lead to the birth of a new star.

Reporting Aug. 20 in the journal Physical Review Letters, a team led by computational physicist Philip Marcus shows how variations in gas density lead to instability, which then generates the whirlpool-like vortices needed for stars to form.

Astronomers accept that in the first steps of a new star's birth, dense clouds of gas collapse into clumps that, with the aid of angular momentum, spin into one or more Frisbee-like disks where a protostar starts to form. But for the protostar to grow bigger, the spinning disk needs to lose some of its angular momentum so that the gas can slow down and spiral inward onto the protostar. Once the protostar gains enough mass, it can kick off nuclear fusion.

"After this last step, a star is born," said Marcus, a professor in the Department of Mechanical Engineering.

What has been hazy is exactly how the cloud disk sheds its angular momentum so mass can feed into the protostar.

Destabilizing forces

The leading theory in astronomy relies on magnetic fields as the destabilizing force that slows down the disks. One problem in the theory has been that gas needs to be ionized, or charged with a free electron, in order to interact with a magnetic field. However, there are regions in a protoplanetary disk that are too cold for ionization to occur.

"Current models show that because the gas in the disk is too cool to interact with magnetic fields, the disk is very stable," said Marcus. "Many regions are so stable that astronomers call them dead zones -- so it has been unclear how disk matter destabilizes and collapses onto the star."

The researchers said current models also fail to account for changes in a protoplanetary disk's gas density based upon its height.

"This change in density creates the opening for violent instability," said study co-author Pedram Hassanzadeh, who did this work as a UC Berkeley Ph.D. student in mechanical engineering. When they accounted for density change in their computer models, 3-D vortices emerged in the protoplanetary disk, and those vortices spawned more vortices, leading to the eventual disruption of the protoplanetary disk's angular momentum.

"Because the vortices arise from these dead zones, and because new generations of giant vortices march across these dead zones, we affectionately refer to them as 'zombie vortices,'" said Marcus. "Zombie vortices destabilize the orbiting gas, which allows it to fall onto the protostar and complete its formation."

The researchers note that changes in the vertical density of a liquid or gas occur throughout nature, from the oceans -- where water near the bottom is colder, saltier and denser than water near the surface -- to our atmosphere, where air is thinner at higher altitudes. These density changes often create instabilities that result in turbulence and vortices such as whirlpools, hurricanes and tornadoes. Jupiter's variable-density atmosphere hosts numerous vortices, including its famous Great Red Spot.

Connecting the steps leading to a star's birth

This new model has caught the attention of Marcus's colleagues at UC Berkeley, including Richard Klein, adjunct professor of astronomy and a theoretical astrophysicist at the Lawrence Livermore National Laboratory. Klein and fellow star formation expert Christopher McKee, UC Berkeley professor of physics and astronomy, were not part of the work described in Physical Review Letters, but are collaborating with Marcus to put the zombie vortices through more tests.

Klein and McKee have worked over the last decade to calculate the crucial first steps of star formation, which describes the collapse of giant gas clouds into Frisbee-like disks. They will collaborate with Marcus's team by providing them with their computed velocities, temperatures and densities of the disks that surround protostars. This collaboration will allow Marcus's team to study the formation and march of zombie vortices in a more realistic model of the disk.

"Other research teams have uncovered instabilities in protoplanetary disks, but part of the problem is that those instabilities required continual agitations," said Klein. "The nice thing about the zombie vortices is that they are self-replicating, so even if you start with just a few vortices, they can eventually cover the dead zones in the disk."

The other UC Berkeley co-authors on the study are Suyang Pei, Ph.D. student, and Chung-Hsiang Jiang, postdoctoral researcher, in the Department of Mechanical Engineering.

The National Science Foundation helped support this research.

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Astronomers Take Sharpest Photos Ever of the Night Sky

 Astronomers at the University of Arizona, the Arcetri Observatory near Florence, Italy and the Carnegie Observatory have developed a new type of camera that allows scientists to take sharper images of the night sky than ever before.

The team has been developing this technology for more than 20 years at observatories in Arizona, most recently at the Large Binocular Telescope, or LBT, and has now deployed the latest version of these cameras in the high desert of Chile at the Magellan 6.5-meter telescope.

"It was very exciting to see this new camera make the night sky look sharper than has ever before been possible," said UA astronomy professor Laird Close, the project's principal scientist. "We can, for the first time, make long-exposure images that resolve objects just 0.02 arcseconds across -- the equivalent of a dime viewed from more than a hundred miles away. At that resolution, you could see a baseball diamond on the moon."

The twofold improvement over past efforts rests on the fact that for the first time, a telescope with a large diameter primary mirror is being used for digital photography at its theoretical resolution limit in visible wavelengths -- light that the human eye can see.

"As we move towards shorter wavelengths, image sharpness improves," said Jared Males, a NASA Sagan Fellow at the UA's department of astronomy. "Until now, large telescopes could make the theoretically sharpest photos only in infrared -- or long wavelength -- light, but our new camera can take photos that are twice as sharp in the visible light spectrum."

These images are also at least twice as sharp as what the Hubble Space Telescope can make, because with its 21-foot diameter mirror, the Magellan telescope is much larger than Hubble with its 8-foot mirror. Until now, Hubble always produced the best visible light images, since even large ground-based telescope with complex adaptive optics imaging cameras could only make blurry images in visible light.

To overcome atmospheric turbulence, which plagues earth-based telescopes by causing the image to blur, Close's team developed a very powerful adaptive optics system that floats a thin (1/16th of an inch) curved glass mirror (2.8 feet across) on a magnetic field 30 feet above the telescope's primary mirror.

This so-called Adaptive Secondary Mirror (ASM) can change its shape at 585 points on its surface 1,000 times each second, counteracting the blurring effects of the atmosphere.

"As a result, we can see the visible sky more clearly than ever before," Close said. "It's almost like having a telescope with a 21-foot mirror in space."

The new adaptive optics system, called MagAO for "Magellan Adaptive Optics," has already made some important scientific discoveries, published today in three scientific papers in theAstrophysical Journal. As the system was being tested and received what astronomers call "first light," the team pointed it to a famous and well-studied massive star that gives the Great Orion Nebula (Object M42) most of its UV light. The Orion Nebula, located just below Orion's Belt visible as smudge of light even with regular binoculars.

Considered young at about 1 million years old, this star, called Theta 1 Ori C, has been previously known to be in fact a binary star pair made up of two stars called C1 and C2. However, the separation between the two is so small -- about the average distance between Earth and Uranus -- that astronomers had never been able to resolve the famous pair in a direct telescope photo.

Once MagAO and its visible science camera called VisAO were pointed towards Theta Ori 1 C, the results were immediate.

"I have been imaging Theta 1 Ori C for more than 20 years and never could directly see that it was in fact two stars," Close said. "But as soon as we turned on the MagAO system it was beautifully split into two stars."

In another result, MagAO has shed light on another mystery: How do how planets form from disks of dust and gas affected by the strong ionizing light called stellar wind coming from a massive star like Theta 1 Ori C, which has about 44 times the mass of the sun?

The team used MagAO and VisAO to look for red light from ionized hydrogen gas to trace out how the strong UV radiation and stellar wind from Theta 1 Ori C affects the disks around its neighboring stars.

"Close to Theta 1 Ori C, there are two very young stars surrounded by disks of gas and dust," said Ya-Lin Wu, a graduate student and lead author on one of the publications. "Theta 1 Ori C pummels those disks with stellar wind and UV light. It looks like they are being bent backwards by a strong wind."

MagAO's photo revealed that the two stars and their protoplanetary disks are heavily distorted into teardrop shapes as the strong UV light and wind create shock fronts and drag gas downwind of the pair.

The distribution of gas and dust in young planetary systems is another unsolved problem in planet formation. The team used VisAO's simultaneous/spectral differential imager, or SDI, to estimate the mass of another intriguing object in the Orion Nebula: one of a few stars in Orion sporting a rare "silhouette disk." The SDI camera allowed the light from the star to be removed at a very high level -- offering, for the first time, a clear look at the inner regions of the silhouette.

"The disk lies in front of the bright Orion nebula, so we see the dark shadow cast as the dust in the disk absorbs background light from the nebula," said Kate Follette, a graduate student and lead author of one of the three papers published in theAstrophysical Journal. "Picture a moth flying across a bright movie screen: Its body will appear opaque, while the wings will be partially transparent. Our SDI instrument allows us to peer into the silhouette and trace how much dust is at each location in the disk based on how transparent or opaque it is."

"We were surprised to find that the amount of attenuated light from the nebula never reached an opaque point," she said. "It seems as though the outer parts of this disk have less dust than we would have expected."

"It is important to understand how dust is laid out in these objects because that dust and gas is what nature uses to build planets," Close explained. "Our new imaging capabilities revealed there is very little dust and gas in the outer part of the disk."

According to Close, the silhouette disk might have been close to the massive star Theta 1 Ori C at some point, which might have blown away its outer dust and gas.

"This tells us something about planet-forming disks in these dense, stellar nurseries," Close said. "There appears to be a limit to the formation of massive planets very far away from their parent stars. One possible explanation might be the presence of a massive star like Theta 1 Ori C stripping away the outer gas and dust."

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Mother's Genes Can Impact Aging Process

As we age, our cells change and become damaged. Now, researchers at Karolinska Institutet and the Max Planck Institute for Biology of Aging have shown that aging is determined not only by the accumulation of changes during our lifetime but also by the genes we acquire from our mothers. The results of the study are published in the journal Nature.

There are many causes of aging that are determined by an accumulation of various kinds of changes that impair the function of bodily organs. Of particular importance in aging, however, seems to be the changes that occur in the cell's power plant -- the mitochondrion. This structure is located in the cell and generates most of the cell's supply of ATP which is used as a source of chemical energy.

"The mitochondria contains their own DNA, which changes more than the DNA in the nucleus, and this has a significant impact on the aging process," said Nils-Göran Larsson, Ph.D., professor at the Karolinska Institutet and principal investigator at the Max Planck Institute for Biology of Aging, and leader of the current study alongside Lars Olson, Ph.D., professor in the Department of Neuroscience at the Karolinska Institutet. "Many mutations in the mitochondria gradually disable the cell's energy production," said Larsson.

For the first time, the researchers have shown that the aging process is influenced not only by the accumulation of mitochondrial DNA damage during a person's lifetime, but also by the inherited DNA from their mothers.

"Surprisingly, we also show that our mother's mitochondrial DNA seems to influence our own aging," said Larsson. "If we inherit mDNA with mutations from our mother, we age more quickly."

Normal and damaged DNA is passed down between generations. However, the question of whether it is possible to affect the degree of mDNA damage through lifestyle intervention is yet to be investigated. All that the researchers know now is that mild DNA damage transferred from the mother contributes to the aging process.

"The study also shows that low levels of mutated mDNA can have developmental effects and cause deformities of the brain," said lead author Jaime Ross, Ph.D., at the Karolinska Institutet.

"Our findings can shed more light on the aging process and prove that the mitochondria play a key part in aging; they also show that it's important to reduce the number of mutations," said Larsson.

"These findings also suggest that therapeutic interventions that target mitochondrial function may influence the time course of aging," said Barry Hoffer, M.D., Ph.D., a co-author of the study from the Department of Neurosurgery at University Hospitals Case Medical Center and Case Western Reserve University School of Medicine. He is also a visiting professor at the Karolinska Institutet. "There are various dietary manipulations and drugs that can up-regulate mitochondrial function and/or reduce mitochondrial toxicity. An example would be antioxidants. This mouse model would be a 'platform' to test these drugs/diets," said Dr. Hoffer.

The data published in the paper come from experiments on mice. The researchers now intend to continue their work on mice, and on fruit flies, to investigate whether reducing the number of mutations can extend their lifespan.

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