Welcome to the Saturday Science Edition of Overnight News Digest.
Astronomy
2015: Year Of The Exomoon? By the last day of the American Astronomical Society meeting in Seattle, attendees can tend to feel all astronomy-ed out. But if you persevered until Thursday, you were gifted with still more great talks and presentations, including a session on habitability. One of my personal favorites was an update by David Kipping on his Hunt for Exomoons with Kepler (HEK). Aside from just being an interesting way to understand when and how moons form, moons around exoplanets could be a huge win for astrobiology. We're still exploring the possibility for oceans and maybe even life on the moons of Jupiter and Saturn. When you think about all the Jupiter-sized exoplanets we've found, with plenty in the habitable zone, the allure of exomoons should become obvious. David has been hard at work for a while, selecting a good sample of Kepler planets to investigate and honing his search algorithms. He now has a program that is amazingly sensitive to digging out signals of exomoons hidden in the Kepler data. So far, he and his team have analyzed 40 of their list of 400 targets. They haven't found any exomoons yet, and they can rule out satellites down to Ganymede size in the best cases. David told us that he spent most of last year very excited about one planet in particular, Kepler-90g, which showed a highly promising signal. Unfortunately, it turned out to be a very tricky false positive. Never fear. There are still plenty of planets to test. Statistically, David tells us it's still entirely possible for up to a third of planets to harbor moons. We just have to test more planets to know for sure. Running the searches takes an amazing amount of computing time, which has slowed the work, but the HEK team is getting access to one of NASA's superclusters this year and should be able to churn through 300 of their targets over the coming twelve months. David said 2015 could be the "year of the exomoon." I've got my fingers crossed. astronomy
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A Balloon-Borne Telescope Successfully Heads To The 'Edge Of Space' With a noise like giant flags billowing in the wind, the massive white helium balloon rose into the air and carried SPIDER, a telescope designed to investigate the origin of the universe, high above Antarctica. The successful Jan. 1 launch signaled the beginning of a roughly 20-day mission above the continent. "At this early stage things are looking as good as we could hope," said William Jones, an assistant professor of physics at Princeton University, in an email from Antarctica. Jones is the leader of the multi-institution effort to launch the balloon-borne telescope. Updates from the SPIDER team are posted to Princeton's SPIDER blog, and the instrument can be tracked on the Columbia Scientific Balloon Facility's website. A September story and video detailing the SPIDER mission are available on Princeton's website. Pushed by circumpolar winds, the balloon will carry SPIDER at an altitude of roughly 120,000 feet while the instrument's six cameras search for faint remnants of gravitational waves left over from the Big Bang during a rapid-expansion process known as inflation. According to Jones, SPIDER is "an experiment that can extend the horizons of our knowledge to, quite literally, the beginning of time." princeton
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What Makes Moonlight Special? A moonlit stroll is starkly different from a walk in the sunshine. Moonlight's dark, spooky quality contrasts with the clarity of sunlight. And while it may not grow hair on your face, we can't help but notice the blacker shadows, blurred details, and lack of color in the landscape on a moonlit night. We peer into the gloom straining to see what's there, but lacking the usual visual cues, we're liable to fill in the darkness with our imagination. Is that Bigfoot up ahead or the neighbor's garbage can? For these reasons, it's often used in scary movies where exaggerated contrasts under studio moonlight create an unfamiliar landscape where anything can happen, including romance. For many of us, both moonless and moon-full nights simply aren't bright enough to stimulate the retina's cone cells responsible for detail and color vision. At low light levels, a different group of light-sensing cells called rods go to work. Rod cells are seriously sensitive, able to detect a single photon of light, but they lack the ability to see color and detail. On a moonless night away from city lights, the nightscape is painted in shades of gray, charcoal black, and bony whites. [...] Moonlight is essentially sunlight reflected from the Moon's surface. Makes sense. Because that surface is asphalt-black, it returns only 11% of the light lavished upon it by our star. Light striking the Moon's ubiquitous pulverized dust is actually somewhat redder than sunlight, but we don't see this with our eyes because it's offset by all the other colors contained in moonlight. A high-riding Moon gleams with silvery-white radiance. skyandtelescope
Biology
Revealed: How Bacteria Drill Into Our Cells And Kill Them A team of scientists has revealed how certain harmful bacteria drill into our cells to kill them. Their study shows how bacterial 'nanodrills' assemble themselves on the outer surfaces of our cells, and includes the first movie of how they then punch holes in the cells' outer membranes. The research, published [2Dec2014] in the journal eLife, supports the development of new drugs that target this mechanism, which is implicated in serious diseases. The team brings together researchers from UCL, Birkbeck, University of London, the University of Leicester, and Monash University (Melbourne). Unlike drills from a DIY kit, which twist and grind their way through a surface, bacterial nanodrills do not contain rotating parts. Rather, they are ring-like structures (similar to an eyelet) built out of self-assembling toxin molecules. Once assembled, the toxins deploy a blade around the ring's inside edge that slices down into the cell membrane, forming a hole. To determine how these rings are built, team member Natalya Dudkina made several thousand images of artificial cell membranes coated with toxins, using an electron microscope. Dudkina is a member of Helen Saibil's group at Birkbeck, University of London, which specialises in mapping biological structures using electron microscopy. "Each ring was formed of around 37 copies of the toxin molecule. But aside from complete rings, we also observed arc-shaped, incomplete rings," Dudkina said. "One problem we had, though, was that our method can only record snapshots of the membrane perforation process frozen at different intermediate stages." The solution to this was to produce a 'movie' of what happens when the toxins are placed on a cell membrane. This was carried out with atomic force microscopy (AFM) at Bart Hoogenboom's lab at the London Centre for Nanotechnology at UCL. AFM uses an ultrafine needle to feel, rather than see, a surface. This needle repeatedly scans the surface to produce a moving image that refreshes fast enough to show how the toxins move over the membrane and then cut holes in the membrane as they sink in. biologynews
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Dogs Migrated To Americas Only 10,000 Years Ago The study looked at the genetic characteristics of 84 individual dogs from more than a dozen sites in North and South America, and is the largest analysis so far of ancient dogs in the Americas. Unlike their wild wolf predecessors, ancient dogs learned to tolerate human company and generally benefited from the association: they gained access to new food sources, enjoyed the safety of human encampments and, eventually, traveled the world with their two-legged masters. Dogs also were pressed into service as beasts of burden, and sometimes were served as food, particularly on special occasions. “Their 11,000 to 16,000-year association with humans makes dogs a promising subject for the study of ancient human behavior, including migratory behavior,” said Kelsey Witt of the University of Illinois, who is the lead author on the study.“Human remains are not always available for study because living populations who are very connected to their ancestors in some cases may be opposed to the destructive nature of genetic analysis. “Analysis of ancient dog remains is often permitted when analysis of human remains is not.” sci-news
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Killer Whales Learn How To Speak Dolphin Killer whales are smart; that we know. Here's a thing that might tip them into "scary smart" territory: they can learn the language of another species. Orcas that were socialized with bottlenose dolphins started making similar sounds as the dolphins, with more clicks and fewer longer calls, according to a study by University of San Diego graduate student Whitney Musser and Hubbs-SeaWorld Research Institute senior research scientist Dr. Ann Bowles published in The Journal of the Acoustical Society of America. Does this mean that killer whales have language, in the way that we understand it? It's known that orcas communicate in so-called dialects, complex vocalizations comprised of clicks, whistles and pulsed calls. And whales that live together in the same pod use the same sounds to communicate, according to a press release. "There's been an idea for a long time that killer whales learn their dialect, but it isn't enough to say they all have different dialects so therefore they learn. There needs to be some experimental proof so you can say how well they learn and what context promotes learning," Bowles said. Bats, some bird species and cetaceans, which includes whales and dolphins, have all exhibited vocal learning. Scientists know quite a lot about songbirds, since their small size makes it easy to study their brains and neural pathways, the press release said. discovery
Chemistry
Flowing Rivers Of Mercury The Chinese emperor had done all he could to become immortal, but in vain. His physicians had prepared herbal and alchemical elixirs, but none could stave off his decline. He had sent a minister on a voyage far over the eastern seas in search of a mythical potion of eternal life. But that expedition never returned, and now the quest seemed hopeless. So Qin Shi Huangdi, the First Emperor of a unified China in the third century BC, had begun preparations for the next best thing to an endless life on Earth. He would continue his cosmic rule from the spirit world, and his underground tomb would be a palace for the afterlife, complete with its own army of life-size clay soldiers. Those terracotta warriors lay hidden for two thousand years beneath several metres of sandy soil a mile from the First Emperor’s burial mound at Mount Li, to the northeast of the city of Xi’an in Shaanxi province of north-central China. They were rediscovered in 1974 by farmers digging a well, and Chinese archaeologists were astonished to find over the next decade that there were at least 8000 of them, once brightly painted and equipped with clay horses and wooden chariots. As further excavation revealed the extent of the emperor’s mausoleum, with offices, stables and halls, along with clay figures of officials, acrobats and labourers and life-size bronze animals, it became clear that the Han dynasty historian Sima Qian, writing in second century BC, hadn’t been exaggerating after all. He claimed that 700,000 men had worked on the emperor’s tomb, constructing entire palaces, towers and scenic landscapes through which which the emperor’s spirit might roam. No one knows what other wonders the mausoleum might house, for the main burial chamber – a football-pitch-sized hall beneath a great mound of earth – remains sealed. Most enticing of all is a detail relayed by Qian: ‘Mercury was used to fashion the hundred rivers, the Yellow river and the Yangtze river, and the seas in such a way that they flowed’. This idea that the main chamber contains a kind of microcosm of all of China (as it was then recognised) with rivers, lakes and seas of shimmering mercury had long seemed too fantastic for modern historians to grant it credence. But if Qian had not been inventing stories about other elaborate features of the mausoleum site, might his account of the tomb chamber be reliable too? In the 1980s Chinese researchers found that the soil in the burial mound above the tomb contains mercury concentrations way above those elsewhere in the vicinity. Now some archaeologists working on the site believe that the body of the First Emperor may indeed lie amidst vast puddles of the liquid metal. Yet it seems unlikely that anyone will gaze on such a sight in the foreseeable future. ‘We have no current plan to open the chambers,’ explains archaeologist Qingbo Duan of Northwest University in Xi’an, who led the mausoleum excavations from 1998 to 2008. ‘We have no mature technologies and effective measures to protect the relics,’ he says. So can we ever know the truth about Qin Shi Huangdi’s rivers of mercury? chemistryworld
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New Tracers Can Identify Coal Ash Contamination In Water Duke University scientists have developed new forensic tracers to identify coal ash contamination in water and distinguish it from contamination coming from other sources. "These new tools can be used by federal and state regulatory agencies to monitor the environmental effects of coal ash and determine whether it has or hasn't impacted the environment," said Avner Vengosh, professor of geochemistry and water quality at Duke's Nicholas School of the Environment. "They can be used to trace the coal ash effluents to their source, even in watersheds where there are multiple possible sources of contamination." Previous methods to identify coal ash contaminants in the environment were based solely on the contaminants' chemical variations, he said. The newly developed tracers provide additional forensic fingerprints that give regulators a more accurate and systematic tool. The tracers, which have been tested both in the laboratory and the field, are based on the distinctive isotopic and geochemical signatures of two elements, boron and strontium, found in coal ash effluent. "The isotopic signature of boron coming from coal ash is always different from naturally occurring boron or boron from other sources," said Laura S. Ruhl, assistant professor of earth sciences at the University of Arkansas at Little Rock. "The signature of strontium is not always distinct, but when used together, the two tracers provide definitive evidence if the contamination is coming from coal ash or another source." chemistrytimes
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What's In The Grime Tarnishing The Taj Mahal? Every several years, workers apply a clay mask to India's iconic but yellowing Taj Mahal to remove layers of grime and reveal the white marble underneath. Now scientists are getting to the bottom of what kinds of pollutants are discoloring one of the world's celebrated wonders. Their findings, published in the ACS journal Environmental Science & Technology, could help inform efforts to protect the mausoleum and other surfaces from pollution. Mike H. Bergin, Sachchida Nand Tripathi and colleagues note that Indian officials have tried to reduce the effects of pollution on the Taj Mahal by restricting nearby traffic and limiting local industrial emissions. But despite regulations and an occasional deep clean, the domes and minarets continue to accrue a layer of soot. So far, no published studies have looked closely at what specific compounds are causing it to appear yellow. Bergin's and Tripathi's teams wanted to find out. The researchers analyzed particles in the air and on marble samples near the main dome over several months. Using a novel method they developed, the team estimated how these specks reflect light and therefore affect the color of the building. They conclude that black carbon and brown carbon from the burning of trash, fuels and other materials are among the primary pollutants tarnishing the Taj Mahal. In the future, their approach could be used to craft strategies to address the chronic yellowing and improve air quality, they say. sciencedaily
Earth Science
Salt Glaciers In the Zagros Mountains of Iran, salt domes break through the surface to produce flowing glaciers of salt. The arid climate does not produce enough rain to dissolve the salt and carry it away. Most people are familiar with ice glaciers. They are masses of ice on land that slowly flow downslope or spread laterally like an extremely viscous fluid. Flow occurs because ice has the ability to deform internally and flow in response to gravity. Salt has those same abilities. If a large mass of salt is placed on a slope it will very slowly respond to gravity and slowly flow down the slope. If a mass of salt is on level ground it will slowly spread laterally under its own weight. These flowing masses of salt on land are called "salt glaciers" or "namakiers." For sustained flow, salt glaciers need a steady supply of salt. Most salt glaciers are fed by a flow of salt from the subsurface. The most common delivery mechanism is a salt dome (often referred to as a "salt diapir") that has pierced Earth's surface. Salt domes form when a layer of salt is deeply buried by other rock units. Salt has a lower specific gravity than most other rocks. If it is buried by rocks of higher specific gravity it will become buoyant. It will attempt to rise through the overlying rocks like a bubble of air through a bottle of shampoo. As soon as the salt starts moving upwards at one location, the pressure of the overlying rocks on the rest of the layer will squeeze the salt towards the location where upward movement has begun. This forces the salt upwards until it reaches the surface, or until a condition of equilibrium is established. If it breaks the surface and upward movement continues, the salt flows out onto the surface to form a salt glacier. geology
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NASA Finds Good News On Forests And Carbon Dioxide A new NASA-led study shows that tropical forests may be absorbing far more carbon dioxide than many scientists thought, in response to rising atmospheric levels of the greenhouse gas. The study estimates that tropical forests absorb 1.4 billion metric tons of carbon dioxide out of a total global absorption of 2.5 billion -- more than is absorbed by forests in Canada, Siberia and other northern regions, called boreal forests. "This is good news, because uptake in boreal forests is already slowing, while tropical forests may continue to take up carbon for many years," said David Schimel of NASA's Jet Propulsion Laboratory, Pasadena, California. Schimel is lead author of a paper on the new research, appearing online today in the Proceedings of National Academy of Sciences. Forests and other land vegetation currently remove up to 30 percent of human carbon dioxide emissions from the atmosphere during photosynthesis. If the rate of absorption were to slow down, the rate of global warming would speed up in return. The new study is the first to devise a way to make apples-to-apples comparisons of carbon dioxide estimates from many sources at different scales: computer models of ecosystem processes, atmospheric models run backward in time to deduce the sources of today's concentrations (called inverse models), satellite images, data from experimental forest plots and more. The researchers reconciled all types of analyses and assessed the accuracy of the results based on how well they reproduced independent, ground-based measurements. They obtained their new estimate of the tropical carbon absorption from the models they determined to be the most trusted and verified. "Until our analysis, no one had successfully completed a global reconciliation of information about carbon dioxide effects from the atmospheric, forestry and modeling communities," said co-author Joshua Fisher of JPL. "It is incredible that all these different types of independent data sources start to converge on an answer." nasa
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NFL Fans Will Help Test Earthquake Warning System Want a side of science with your sports? Tune in to a Seattle Seahawks game this NFL playoff season. Seismologists will be tracking the shimmies and shakes of Seattle's CenturyLink Field in order to test their earthquake early-warning system. "It's a silly experiment that gives us a chance to work on our equipment," said John Vidale, a professor at the University of Washington and director of the Pacific Northwest Seismic Network (PNSN). Vidale and his colleagues at the U.S. Geological Survey and other universities are developing a system called ShakeAlert, with the goal of giving residents in earthquake-prone areas a few seconds' warning before potentially deadly shaking starts. [History's 10 Biggest Earthquakes] The Seahawks entered this picture in 2011, when Vidale wondered if seismic monitors near the team's home stadium had picked up the eruption of the crowd after an impressive touchdown run by player Marshawn Lynch during a game against the New Orleans Saints. As it turned out, they had. The shaking, Vidale found, was equivalent to a very localized magnitude-1.0 or magnitude-2.0 earthquake. Since then, scientists have turned to seismometer networks to "see" the vibrations caused by NASCAR races as well as football crowds. And it's not just a game; monitoring the seismic vibrations of a structure may provide a way to monitor the building's unseen cracks and stresses. livescience
Physics
Metamaterial Prism Creates A Reverse Rainbow In a normal rainbow, red is always on "top" while violet is on the "bottom." This is true whether the rainbow is created by a glass prism or by water droplets in the sky, and is due to the way that these materials refract light of different wavelengths: colors with longer wavelengths (red) are less refracted/bent than colors with shorter wavelengths (violet). Now in a new study, scientists have designed a prism that does the opposite: it refracts longer wavelengths more strongly than shorter wavelengths. The result is a reverse rainbow. The researchers, Tiago A. Morgado, et al., from the University of Coimbra, the University Institute of Lisbon, and the University of Lisbon, all in Portugal, have published their paper on creating a reverse rainbow in the microwave part of the spectrum using the new prism in a recent issue of Applied Physics Letters. The new prism is made of metamaterials, which are man-made materials that have properties not typically found in natural materials. In this case, the atypical property is non-local topology, which gives rise to the stronger refraction of longer wavelengths and the reverse rainbow. As the scientists explain, natural crystalline materials such as glass and water have a local structure, in which the atoms lie isolated at lattice points and mainly interact only with their nearest neighbors. In contrast, atoms in the new metamaterial are all interconnected by crossed metallic wires. In the resulting non-local structure, each atom's response to light is fundamentally entangled with the responses of other atoms, even those located far away in the crystal. This nonlocal, interconnected response of the atoms changes the way that the metamaterial disperses different frequencies of light, producing an effect called "anomalous dispersion." The anomaly is that the refractive index of the material, and therefore the transmission angle of the light, increases as frequency decreases. This is the opposite of what happens in a conventional glass prism or water droplets. phys
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Filming Light At Light Speed The human visual system can perceive only about 10 distinct images per second. So to record everyday life as we experience it, a standard video capture rate of 24 frames per second more than suffices. But many physical phenomena unfold faster than the eye can see. To record them, researchers seek ever-faster cameras. Now Lihong Wang and coworkers at Washington University in St. Louis have developed a camera that can capture 1011 frames per second, good enough to record the movement of light at millimeter length scales. The camera exploits a technology called streak photography: Instead of opening and closing a shutter to capture a sequence of discrete images, a streak camera deflects incoming light in a way that maps a scene’s temporal component to a spatial dimension on the camera’s two-dimensional pixel array. Because one of the array’s dimensions is reserved for mapping time, conventional streak cameras can film in only one spatial dimension. Wang and company, however, found that they could record a 2D scene if they used a programmable mask to encode incoming light with a known pixel pattern. That allows them to detect information about all three dimensions—two spatial dimensions and time—on a single pixel array and then mathematically parse that information to recover a frame sequence that closely approximates the original scene. To demonstrate the technique, the group filmed light pulses reflecting off a mirror, illuminating striped walls, and exciting fluorescence in rhodamine dye. In the frame sequence pictured here, a light pulse nearly perfectly reproduces the path (dashed line) predicted by ray optics as it refracts at an air–resin interface. scitation
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Nanostructure Puts The Gloss On Avian Eggshells The family of chicken-sized birds native to South America called tinamous lay brightly coloured eggs that are some of the glossiest in nature. Now, an international team of scientists has discovered the secret to the eggs' mirror-like sheen, which rivals that of highly polished man-made materials. "Imagine a shiny, brand new car. The eggs of these birds are so shiny that they are reflective," says Branislav Igic, an avian biologist from the University of Akron in Ohio, who did the work with colleagues in the US, the Czech Republic and New Zealand. In the new study, Igic and his team used a combination of microscopy and chemical analyses to show that the glossiness of tinamou eggs is down not to pigments, but rather the nanostructure of the shell itself. In particular, the outermost layer of the shells, called the cuticle, is extremely smooth and composed of a unique mix of proteins and chemical elements such as calcium carbonate and calcium phosphate. "A smooth surface means that light gets reflected back at the same angle that it comes in at," says Igic. "A rough surface has tiny valleys and hills that scatter the light in all directions, and that leads to a more matt appearance." The study also reveals that the blue eggs of the great-tinamou bird are weakly iridescent – that is, the colour perceived by the viewer changes depending on the angle of observation and illumination. This optical effect, common in moth and butterfly wings, has never been seen in bird eggs before. "It's a very subtle iridescence," says Igic. "Human eyes may not be able to discern it, but birds have better colour acuity, so they are probably more sensitive to these changes in colour." physicsworld
Social Science
Are Bilinguals Really Smarter Many people believe that bilinguals—persons who speak two languages—have an advantage over monolinguals on tasks that require executive control. “Executive control” is a term used by psychological scientists to refer to the management and regulation of specific cognitive processes like working memory and task-switching (shifting attention from one task to another). Belief in the so-called bilingual advantage (BA) is based on a large number of scientific studies. These studies have repeatedly demonstrated that bilinguals, as a group, perform better than monolinguals on tasks that involve task-switching or inhibitory control (the ability to block a cognitive response). Bilinguals, for example, typically perform better on tasks that require the participant to suppress a response that is inappropriate within a specific context. Bilinguals are presumably good at these kinds of tasks because they’ve had lots of practice. In their daily lives, unbidden words pop into their heads—words that are not helpful at that moment and in that context. The bilingual Spaniard instinctively wants to yell “¡Cuidado!” even when he’s in London and knows that “Look out!” would be a more helpful warning. In these kinds of situations, bilingual speakers learn how to suppress their initial urges and substitute a more appropriate word or phrase. psychologytoday
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China's Remote Fortresses Lose Residents, Gain Tourists It started like a game. How many of these strange, fortress-like structures could I tally from a vehicle window? They were so big, looming like spaceships in the countryside of Fujian Province in southeastern China. Every village seemed to have at least one, two, more. An obsession grew. I would ask to be left off at the edge of villages tucked between hills, and I would start walking and counting. [...] Soon I wasn't satisfied with merely standing outside and gawking at tulou, which come in various shapes but are mostly square or circular. I had to go inside each one I counted. The front doors were usually open. So I entered and kept entering. And this is what I found. First off, the outside doesn't prepare you for what's inside. If the somber exterior resembles a penitentiary, the interior bursts open like a concert hall. Timbered galleries rise majestically as many as five stories high around a light-filled courtyard. Each floor is built of dark wood, with small rooms placed one after another, identical in size, like an architectural chant. Corridors turn or bend the lengths of each floor. In the open-air courtyard, paved with lumpy cobblestones, there is usually a well or two, plus a small, ornate enclosure for the worship of ancestors. The space commands you to turn around and around to marvel at the dizzying sweep of rooms, the view overhead of sky and mountains, and the audacity of a design that contains a community within a giant impregnable building. nationalgeographic