Welcome to the Saturday Science Edition of Overnight News Digest.
Astronomy
Hubble Discovers That Milky Way Core Drives Wind At 2 Million MPH At a time when our earliest human ancestors had recently mastered walking upright, the heart of our Milky Way Galaxy underwent a titanic eruption, driving gases and other material outward at 2 million mph (3 million km/h). Now, at least 2 million years later, astronomers are witnessing the aftermath of the explosion: billowing clouds of gas towering about 30,000 light-years above and below the plane of our galaxy. The enormous structure was discovered five years ago as a gamma-ray glow on the sky in the direction of the galactic center. The balloon-like features have since been observed in X-rays and radio waves. But astronomers needed NASA's Hubble Space Telescope to measure for the first time the velocity and composition of the mystery lobes. They now seek to calculate the mass of the material being blown out of our galaxy, which could lead them to determine the outburst's cause from several competing scenarios. Astronomers have proposed two possible origins for the bipolar lobes: a firestorm of star birth at the Milky Way's center or the eruption of its supermassive black hole. Although astronomers have seen gaseous winds, composed of streams of charged particles, emanating from the cores of other galaxies, they are getting a unique, close-up view of our galaxy's own fireworks. [...] One possible cause for the outflows is a star-making frenzy near the galactic center that produces supernovae, which blow out gas. Another scenario is a star or a group of stars falling onto the Milky Way's supermassive black hole. When that happens, gas superheated by the black hole blasts deep into space. Because the bubbles are short-lived compared to the age of our galaxy, it suggests this may be a repeating phenomenon in the Milky Way's history. Whatever the trigger is, it likely occurs episodically, perhaps only when the black hole gobbles up a concentration of material. astronomy
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Do Atmospheres Spin Worlds Do Habitability? In the hunt for Earth 2.0, many astronomers are pointing their telescopes toward smaller, cooler stars. Not only are these so-called red dwarfs the most abundant type of star in the galaxy, but they’re also roughly one-quarter the Sun’s mass, bringing their habitable zones closer in and making it easier to spot any Goldilocks planets, either via their gravitational tugs on the star or when the planet passes in front of the star from our perspective.There’s just one catch. A planet that orbits close enough to its dim star to be in the habitable zone could become tidally locked. Just as our planet sees one side of the Moon at all times, red dwarfs will only see one side of a close-in planet at all times. So one side of the planet will likely see continuous day and the other perpetual darkness, potentially destabilizing chemical exchanges between the atmosphere and surface or even (in extreme instances) causing the atmosphere to collapse. In short, tidally locked planets are likely uninhabitable. New research, however, suggests not all is lost for tightly orbiting planets. Jérémy Leconte (University of Toronto and Pierre Simon Laplace Institute, France) and his colleagues think that an atmosphere’s effect might be strong enough to break any tidal locking, allowing the planet to rotate freely and exhibit a day-night cycle similar to Earth’s. [.. Astronomers have long seen this effect on the planet Venus, where the atmosphere’s influence is so powerful that it forces the planet out of synchronous rotation into a slow retrograde rotation: to a Venusian, the Sun rises in the west and sets in the east. But Venus’s large atmosphere weighs in about 90 times heavier than our own, and planetary scientists didn’t think thinner atmospheres like Earth’s could throw their weight around as effectively.Leconte’s simulations show that thinner atmospheres actually have a larger rotational effect on their planets. With less scattered sunlight, extra heat reaches the deepest atmospheric layer and creates stronger winds. If Venus were to have an atmosphere like Earth’s, it would spin 10 times faster. This is radically different from previous research, which suggested that it would spin 50 times slower. An unlocked planet should have strong atmospheric mixing and relatively stable temperatures. “This greatly increases the chances for atmospheric stability — and, hence, for life — on any of these bodies, provided they are Earth-like in terms of mass, water content, and maybe their atmospheres,” says exoplanet expert René Heller (McMaster University, Canada). skyandtelescope
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Gullies On Vesta Suggest Past Water-Mobilized Flows Protoplanet Vesta, visited by NASA's Dawn spacecraft from 2011 to 2013, was once thought to be completely dry, incapable of retaining water because of the low temperatures and pressures at its surface. However, a new study shows evidence that Vesta may have had short-lived flows of water-mobilized material on its surface, based on data from Dawn. "Nobody expected to find evidence of water on Vesta. The surface is very cold and there is no atmosphere, so any water on the surface evaporates," said Jennifer Scully, postgraduate researcher at the University of California, Los Angeles. "However, Vesta is proving to be a very interesting and complex planetary body." The study has broad implications for planetary science. "These results, and many others from the Dawn mission, show that Vesta is home to many processes that were previously thought to be exclusive to planets," said UCLA's Christopher Russell, principal investigator for the Dawn mission. "We look forward to uncovering even more insights and mysteries when Dawn studies Ceres." Dawn is currently in the spotlight because it is approaching dwarf planet Ceres, the largest object in the main asteroid belt between Mars and Jupiter. It will be captured into orbit around Ceres on March 6. Yet data from Dawn's exploration of Vesta continue to capture the interest of the scientific community. nasa
Biology
Carnivorous Marine Snails Use Insulin To Disable Their Prey “It is very unlikely that it is serving a different purpose,” said Dr Helena Safavi-Hemami from the University of Utah, who is the first author of a paper published in the Proceedings of the National Academy of Sciences. “This is a unique type of insulin. It is shorter than any insulin that has been described in any animal. We found it in the venom in large amounts,” added study senior author Prof Baldomero Olivera of the University of Utah. [...] The insulin genes were more highly expressed in the venom gland than genes for some of the established venom toxins. [...] A synthetic form of the snail insulin, when injected into zebrafish, caused blood glucose levels to plummet. The insulin also disrupted swimming behavior in fish exposed through water contact, as measured by the percentage of time spent swimming and frequency of movements. The team proposes that adding insulin to the mix of venom toxins enabled predatory cone snails to disable entire schools of swimming fish with hypoglycemic shock. sci-news
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A New Neural Circuit Controls Fear In The Brain Some people have no fear, like that 17-year-old kid who drives like a maniac. But for the nearly 40 million adults who suffer from anxiety disorders, an overabundance of fear rules their lives. Debilitating anxiety prevents them from participating in life's most mundane moments, from driving a car to riding in an elevator. Today, a team of researchers at Cold Spring Harbor Laboratory (CSHL) describes a new pathway that controls fear memories and behavior in the mouse brain, offering mechanistic insight into how anxiety disorders may arise. It is hard to imagine that an intangible emotion like fear is encoded within neuronal circuits, but researchers have found that fear is stored within a distinct region of the brain. "In our previous work, we discovered that fear learning and memory are orchestrated by neurons in the central amygdala," explains CSHL Associate Professor Bo Li, who led the team of researchers. But what controls the central amygdala? One possible candidate was a cluster of neurons that form the PVT, or paraventricular nucleus of the thalamus. This region of the brain is extremely sensitive to stress, acting as a sensor for both physical and psychological tension. As described in work published today in Nature, the researchers looked to see if the PVT plays a role in fear learning and memory in mice. "We found that the PVT is specifically activated as animals learn to fear or as they recall fear memories," says Li. The team was able to see that neurons from the PVT extend deep into the central amygdala. Disrupting the connection significantly impaired fear learning. Because the link between the PVT and the central amygdala is a critical component of fear learning, it represents an ideal target for potential drugs to treat anxiety disorders. But how is this link established? The researchers looked to data from people with post-traumatic stress disorder (PTSD) to identify chemical messengers that might connect the two structures. They focused on a molecule called BDNF that has been implicated in anxiety disorders. BDNF is a well-known neural growth factor that plays an important role in stimulating the birth of new neurons as well as new connections between neurons. Patients with anxiety disorders frequently have mutations in BDNF, suggesting that it might have a role in fear learning and memory. biologynews
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Study Projects Unprecedented Loss of Corals In Great Barrier Reef Due To Warming The coverage of living corals on Australia's Great Barrier Reef could decline to less than 10 percent if ocean warming continues, according to a new study that explores the short- and long-term consequences of environmental changes to the reef. Environmental change has caused the loss of more than half the world's reef building corals. Coral cover, a measure of the percentage of the seafloor covered by living coral, is now just 10-20 percent worldwide. The Great Barrier Reef, once thought to be one of the more pristine global reef systems, has lost half of its coral cover in only the last 27 years. Overfishing, coastal pollution and increased greenhouse gas emissions leading to increased temperatures and ocean acidification, as well as other human impacts are all affecting the delicate balance maintained in coral reef ecosystems. Now, in a new study that aims to project the composition of the future Great Barrier Reef under current and future environmental scenarios, researchers found that in the long term, moderate warming of 1-2 degrees Celsius would result in a high probability of coral cover declining to less than 10 percent, a number thought to be important for maintaining reef growth. In the short term, with increasing temperatures as well as local man-made threats like coastal development, pollution, and over-fishing, the study found that corals—tiny animals related to jellyfish—would be over-run by seaweed which would, in effect, suffocate them. In the longer term, interactions among reef organisms would lead to dominance by other groups, including sponges and soft corals known as gorgonians. nimbios
Chemistry
Self-Cleaning Sensors See The Light Scientists in Italy have engineered a cheap and simple electrochemical sensor that cleans itself when exposed to ultraviolet light. Their system offers a route towards self-cleaning electrodes with myriad environmental and biomedical sensing applications – from detecting pollutants in water to monitoring medications in blood. Open any book on chemical or biological sensors and you’ll find a lot of content on electrochemical devices. This prevalence is testament to the importance and advantages of electrode-based sensing; and electrodes containing nanomaterials are becoming increasingly popular, owing to their high surface-to-volume ratio, which can improve their sensitivity and lower costs. However, nanomaterial-based electrodes are very difficult to keep clean, hindering their application in environmental and biomedical sensing. River water, for example, contains species that can foul electrochemical sensors and prevent their reuse. In another example, dopamine – an important neurotransmitter, particularly in Parkinson’s disease – fouls sensors during its electroanalytical detection, preventing reusability. To solve the fouling problem, Luigi Falciola and his team at the University of Milan have engineered an electrochemical sensor with a photoactive top layer of titania that can be directly cleaned with ultraviolet light and repeatedly reused to detect dopamine. The titania covers a highly ordered distribution of silver nanoparticles (the actual sensing tool), arrayed on a bottom layer of silica. Self-cleaning surfaces based on titania are an increasingly common part of our everyday lives, from self-cleaning windows, cars and cements to self-sterilising medical devices. These applications all clean using the same basic chemistry: ultraviolet light – from sunlight or an artificial source – induces photocatalysis at a titania coating, which breaks down organic foulants. Falciola’s team have incorporated the same principle in their sensor. royalsocietyofchemistry
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Temporary Tattoo Measures Blood Glucose Levels Future diabetes patients won’t have to stick themselves with a needle; they’ll just need to get a tattoo. Researchers have developed a temporary paper-based tattoo that applies a mild electrical shock to the skin to measure blood glucose levels. In a study of seven individuals—four males and three females—who wore the tattoo while eating a carbohydrate-rich meal in the lab, the device was just as effective at measuring glucose levels as the traditional method, the finger stick monitor. None of the volunteers reported any discomfort during the tests, the team reports in the current issue of Analytical Chemistry, although some of them did point out a tingling feeling when the tattoo was taking its measurements. The device does not currently provide a numerical reading that diabetes patients would need to monitor their condition, but this is in the cards. Other possible applications include sending the information to the patient’s doctor in real time using Bluetooth. Now, the tattoo works for a whole day; the researchers are working on making the tattoo last longer while keeping it at its current cost of a few cents. sciencemag
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Lightweight, Tunable Lenses Made From Graphene An international team of researchers has made tunable, extremely lightweight lenses using grapheme (ACS Photonics 2015, DOI: 10.1021/ph500197j) . The lenses act like microscopic versions of ones used in lighthouses and could help focus light onto small pixels in cell phone cameras or route laser light in computer chips that move data with photons instead of electrons. Haider Butt of the University of Birmingham, in England; Qing Dai of the National Center for Nanoscience & Technology, in Beijing; and their colleagues designed Fresnel lenses, which are flat lenses consisting of concentric rings. The rings diffract light to create constructive interference, thus focusing the light. Lighthouses have long used Fresnel lenses to focus their beacons. The design would be key for miniaturized applications, such as in computer interconnects, because the lenses could have long focal lengths while remaining flatter, thinner, and lighter than curved lenses. The researchers built the 50-µm-wide lenses by depositing 0.335-nm-thick layers of graphene on glass using chemical vapor deposition and then carving out the concentric circles with photolithography. The graphene rings diffract light as it passes through the lens. The team found that the intensity of the focused light doubled when they went from five-layer to 10-layer versions of the lenses. Also, in an applied electric field, the graphene’s ability to absorb light changed, allowing the researchers to tune the intensity of the focused light. The lenses focused 850-nm light, in the near-infrared range, but the team would like to design lenses that work at terahertz frequencies, which have promising applications in security, spectroscopy, and biological imaging. chemicalandengineeringnews
Earth Science
Study Shows Brazil’s Soy Moratorium Still Needed To Preserve Amazon [...] In 2006, following a report from Greenpeace and under pressure from consumers, large companies like McDonald's and Wal-Mart decided to stop using soy grown on cleared forestland in the Brazilian Amazon. This put pressure on commodity traders, such as Cargill, who in turn agreed to no longer purchase soy from farmers who cleared rain forest to expand soy fields. The private sector agreement, a type of supply chain governance, is called the Soy Moratorium and it was intended to address the deforestation caused by soy production in the Amazon. In a new study to evaluate the agreement, published today (Jan. 22, 2015) in Science, the University of Wisconsin-Madison's Holly Gibbs and colleagues across the U.S. and Brazil show that the moratorium helped to drastically reduce the amount of deforestation linked to soy production in the region and was much better at curbing it than governmental policy alone. "What we found is that before the moratorium, 30 percent of soy expansion occurred through deforestation, and after the moratorium, almost none did; only about 1 percent of the new soy expansion came at the expense of forest," says Gibbs, a professor of environmental studies and geography in the UW-Madison Nelson Institute's Center for Sustainability and the Global Environment (SAGE). Between 2001 and 2006, prior to the moratorium, soybean fields in the Brazilian Amazon expanded by 1 million hectares, or nearly 4,000 square miles, contributing to record deforestation rates. By 2014, after eight years of the moratorium, almost no additional forest was cleared to grow new soy, even though soy production area had expanded another 1.3 million hectares. Farmers were planting on already cleared land. [...] What the team found was surprising. "Only 115 people out of several thousand soy farmers have violated the Soy Moratorium since 2006, but over 600 of them have violated the Forest Code," Gibbs says. "So, this same group of farmers is five times more likely to violate the governmental policy than they are to violate the private sector agreement." For instance, the Forest Code dictates that 80 percent of Amazon rain forest on a person's property must be held in reserve; they can only clear 20 percent. Yet, just 2 percent of soy farmers have maintained their legal reserve and even farmers abiding by the moratorium were still illegally clearing forest on their properties, just not for growing soy. wisc.news
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Arctic Ice Cap Slides Into The Ocean A team led by scientists from the Centre for Polar Observation and Modelling (CPOM) at the University of Leeds combined observations from eight satellite missions, including Sentinel-1A and CryoSat, with results from regional climate models, to unravel the story of ice decline. The findings show that over the last two decades, ice loss from the south-east region of Austfonna, located in the Svalbard archipelago, has increased significantly. In this time, ice flow has accelerated to speeds of several kilometres per year, and ice thinning has spread more than 50km inland -- to within 10km of the summit. "These results provide a clear example of just how quickly ice caps can evolve, and highlight the challenges associated with making projections of their future contribution to sea level rise," said the study's lead author Dr Mal McMillan, a member of the CPOM team from the University of Leeds. [...] Melting ice caps and glaciers are responsible for about a third of recent global sea level rise. Although scientists predict that they will continue to lose ice in the future, determining the exact amount is difficult, due both to a lack of observations and the complex nature of their interaction with the surrounding climate.
"Glacier surges, similar to what we have observed, are a well-known phenomenon," said Professor Andrew Shepherd from the University of Leeds, the Director of CPOM. "However, what we see here is unusual because it has developed over such a long period of time, and appears to have started when ice began to thin and accelerate at the coast."
sciencedaily
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Lake Tahoe's Tiny Creatures Dying Off At Dramatic Rate The smallest critters who occupy the bottom of the cold, clear waters of Lake Tahoe are dying off at an alarming rate and scientists are trying to find the cause to protect the fragile ecosystem of the lake high in the Sierra Nevada range. Scuba divers completed a first-ever circumnavigation of the shallow areas and certain deep spots last fall, collecting data that showed population drops in eight kinds of invertebrates that are only thumbnail-sized and smaller, including some only found in Lake Tahoe. "Our laboratory group was very surprised to see such a dramatic decline over a short period of time," University of Nevada, Reno scientist and associate professor Sudeep Chandra said in an email on Wednesday. "Big changes are occurring at the bottom of the lake." The findings, which researchers are still reviewing, are the latest cause for concern for the nation's second-deepest lake. Sitting at the base of a world-class ski area, Lake Tahoe is a tourist draw for its breathtaking beauty and outdoor activities, but has long faced environmental damage from development, boats and invasive species. The animals – called benthic invertebrates – include flatworms, the blind amphipod and the Tahoe stonefly. They have declined anywhere between 55 percent to 99.9 percent from measurements taken in the 1960s, said Chandra, who co-authored an article on the decline published in 2013 in the journal Freshwater Science. "These eight declining animals are multiple canaries in the coal mine indicating that we need to think the functioning of the entire Lake Tahoe ecosystem," he said. "Changes at the bottom may be an indication of things to come." reuters
Physics
Football Physics And The Science Of Deflategate News reports say that 11 of the 12 game balls used by the New England Patriots in their AFC championship game against the Indianapolis Colts were deflated, showing about 2 pounds per square inch (psi) less pressure than the 13 psi required by the rules, so it seems that the most bizarre sports scandal of recent memory is real. But there are still plenty of questions: why would a team deflate footballs? Could there be another explanation? And most importantly, what does physics tell us about all this? For New England fans, the first priority is a search for an innocent explanation. After all, party balloons and car tires deflate during cold winter weather, so might a simple temperature difference be responsible for the change in inflation pressure? The physics principle known as the ideal gas law tells us that a reduction in temperature leads to a reduction in pressure. The pressure of a confined gas multiplied by its volume is proportional to the number of molecules in the gas multiplied by the temperature. Maybe you remember the equation PV=nRT from your schooldays. So if you cool a gas while keeping its volume fixed, the pressure must decrease. But we don't need equations to check this: we can demonstrate it directly. I got a couple of old footballs from Union College's athletic department, pumped them up and popped them in the freezer. After a night in the cold, the pressure was around 2psi lower, just like the Patriots' footballs—from about 19psi at the start (I slightly overinflated the balls by using the tire pump in my car) down to about 17 psi. phys.org This is just a fun article to click on. - Editor
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Silver Nanowires Demonstrate Unexpected Self-Healing Mechanism With its high electrical conductivity and optical transparency, indium tin oxide is one of the most widely used materials for touchscreens, plasma displays and flexible electronics. But its rapidly escalating price has forced the electronics industry to search for other alternatives. One potential and more cost-effective alternative is a film made with silver nanowires—wires so extremely thin that they are one-dimensional—embedded in flexible polymers. Like indium tin oxide, this material is transparent and conductive. But development has stalled because scientists lack a fundamental understanding of its mechanical properties. [...] “Cyclic loading is an important material behavior that must be investigated for realizing the potential applications of using silver nanowires in electronics,” [Horacio Espinosa, the James N. and Nancy J. Farley Professor in Manufacturing and Entrepreneurship at Northwestern Univ.’s McCormick School of Engineering] said. “Knowledge of such behavior allows designers to understand how these conductive films fail and how to improve their durability.” By varying the tension on silver nanowires thinner than 120 nm and monitoring their deformation with electron microscopy, the research team characterized the cyclic mechanical behavior. They found that permanent deformation was partially recoverable in the studied nanowires, meaning that some of the material’s defects actually self-healed and disappeared upon cyclic loading. These results indicate that silver nanowires could potentially withstand strong cyclic loads for long periods of time, which is a key attribute needed for flexible electronics. rdmag
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Structured Photons Slow Down In A Vacuum The speed of light in a vacuum is 299,792,458 m s–1, right? Not necessarily, according to a team of physicists in the UK, which has found that the speed of an individual photon decreases by a tiny amount if it is initially sent through a patterned mask. The phenomenon – which is different to other observations of slow light – should also occur for sound waves, the researchers say. The speed of light has been measured since as far back as the 17th century, but it was not until the 1970s that physicists settled on a value that was accurate in a vacuum to just a few parts per billion. In 1983 that value became the official value, fixed against a new definition of the metre in the International System of Units. And an important value it is, for according to Einstein's special theory of relativity, the speed of light in a vacuum, c, is the maximum speed obtainable by any entity – no matter what inertial frame of reference it is measured in. Of course, light can appear to slow down if it travels through a dense medium – a result of the photons having to interact with the medium and take an indirect route through it. In water, the speed of light is roughly 225,000,000 m s–1, while in glass it is roughly 200,000,000 m s–1. The change can be even more drastic – particularly in highly "nonlinear" materials, in which light's speed can be reduced to just a few metres per second. Strange effects can also occur in a vacuum, including the Gouy phase shift, which happens when a beam of light is focused to a point and results in a tiny increase in its "phase velocity". Now it seems that physicists have come up with a new way of changing the speed of light in a vacuum. Over two years, Miles Padgett and colleagues at the University of Glasgow, together with Daniele Faccio of Heriot-Watt University in Edinburgh, designed an experiment that can determine whether light with a certain "spatial structure" travels substantially slower than regular light in a vacuum. The researchers created a source that emitted pairs of photons simultaneously. One of the photons went straight to a highly precise photon counter, while the other went via two liquid-crystal masks, which imparted their profile onto the passing particle of light. Across a propagation distance of 1 m, the team found that the spatially structured photon lagged behind its partner by between 10 and 20 wavelengths. That equated to a drop in speed of about 0.001%, says team member Jacquiline Romero. physicsworld