Welcome to the Saturday Science Edition of Overnight News Digest.
Astronomy
The Very Large Array Finds Unexpected “Storm” At Galaxy’s Core Astronomers using the National Science Foundation's Very Large Array (VLA) found surprisingly energetic activity in what they otherwise considered a "boring" galaxy, and their discovery provides important insight on how supermassive black holes can have a catastrophic effect on the galaxies in which they reside. "It appears that a supermassive black hole is explosively heating and blasting around the gas in this galaxy and, as a result, is transforming it from an actively star-forming galaxy into one devoid of gas that can no longer form stars," said Chris Harrison from the Center for Extragalactic Astronomy at Durham University in the United Kingdom. Two major types of galaxies are spirals, rich in gas and actively forming stars, and ellipticals, gas-poor and with very little star formation. The massive ellipticals, astronomers think, started life as active star-forming galaxies. Powerful jets and winds of material, powered by supermassive black holes at the galaxies' centers, are believed to remove or destroy the raw material needed for continued star formation. "For many years, we've seen direct evidence of this happening in galaxies that are extremely bright when viewed through radio telescopes. These rare radio-bright galaxies harbor powerful jets, launched at the black hole, that plow into the surrounding gas," Harrison said. "However, to understand how all galaxies in our universe formed, we needed to know if these same processes occur in less extreme galaxies that better represent the majority. This was the focus of our study." [...] "This storm in the Teacup means that the jet-driven process in which a black hole is removing or destroying star-forming material may be much more typical than we knew before and could be a crucial piece in the puzzle of understanding how the galaxies we see around us were formed," Harrison said. astronomy
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Is There Such A Thing As A Random Meteor? We've all seen them. The sporadics. Those random meteors that flash across the sky on any old clear night. If you were to make a lifelong tally of meteors, the sporadics would easily outnumber those from meteor showers. But where do they come from? Are they truly random, or were they once members of long-lost meteor showers witnessed by our distant ancestors? No question about it, some sporadic meteors originate from ancient meteor showers that have long since dispersed. Over time, meteoroids that are dribbled out by vaporizing comets and colliding asteroids can spread into streams so broad we no longer know from whence they came. Jupiter can bounce meteoroids right out of the Solar System; others get pulled in by the Sun's gravity or blown out by its wind. A couple thousand years from now, an amateur astronomer, looking up to see a former Perseid meteoroid ionize its signature across the sky, will dismiss it as an unknown. The number of sporadic meteors visible varies over the course of the night, rising from a minimum of 4–6 per hour around 6 p.m. to twice that at the start of dawn. At dusk, the direction of our orbital motion is opposite that at sunset, forcing meteoroids to catch up to Earth from behind. Around dawn, the planet plows straight into whatever dribs and drabs of comet lie ahead skyandtelescope
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A New Way To View Titan: 'Despeckle' It During 10 years of discovery, NASA's Cassini spacecraft has pulled back the smoggy veil that obscures the surface of Titan, Saturn's largest moon. Cassini's radar instrument has mapped almost half of the giant moon's surface; revealed vast, desert-like expanses of sand dunes; and plumbed the depths of expansive hydrocarbon seas. What could make that scientific bounty even more amazing? Well, what if the radar images could look even better? Thanks to a recently developed technique for handling noise in Cassini's radar images, these views now have a whole new look. The technique, referred to by its developers as "despeckling," produces images of Titan's surface that are much clearer and easier to look at than the views to which scientists and the public have grown accustomed. Typically, Cassini's radar images have a characteristic grainy appearance. This "speckle noise" can make it difficult for scientists to interpret small-scale features or identify changes in images of the same area taken at different times. Despeckling uses an algorithm to modify the noise, resulting in clearer views that can be easier for researchers to interpret. Antoine Lucas got the idea to apply this new technique while working with members of Cassini's radar team when he was a postdoctoral researcher at the California Institute of Technology in Pasadena. "Noise in the images gave me headaches," said Lucas, who now works at the astrophysics division of France's nuclear center (CEA). Knowing that mathematical models for handling the noise might be helpful, Lucas searched through research published by that community, which is somewhat disconnected from people working directly with scientific data. He found that a team near Paris was working on a “de-noising” algorithm, and he began working with them to adapt their model to the Cassini radar data. The collaboration resulted in some new and innovative analysis techniques. nasa
Biology
Oyster Disease Thrives In Nightly Dead Zones In shallow waters around the world, where nutrient pollution runs high, oxygen levels can plummet to nearly zero at night. Oysters living in these zones are far more likely to pick up the lethal Dermo disease, a team of scientists from the Smithsonian Environmental Research Center discovered. Their findings were published Wednesday in the journal PLOS ONE. Oxygen loss in the shallows is a global phenomenon, but it is not nearly as well known as the dead zones of the deep. Unlike deep-water dead zones, which can persist for months, oxygen in shallow waters swings in day-night cycles, called diel-cycling hypoxia. When algae photosynthesize during the day, they release oxygen into the water. But at night, when photosynthesis stops, plants and animals continue to respire and take oxygen from the water, causing dissolved oxygen to drop. Lack of oxygen can cripple the oysters' ability to fight off the parasite Perkinsus marinus that causes Dermo and slowly takes over their bodies. [...] In a field experiment, Breitburg and her colleagues suspended hundreds of eastern oysters (Crassostrea virginica) in underwater cages at each of 14 sites around Chesapeake Bay. Some that were only a year old and did not show signs of being infected were used to test the vulnerability of new populations, especially where oyster restoration is concerned. Others that were older and had already been infected were used to test whether low-oxygen made the disease more severe. After four months, they randomly sampled oysters from each cage to uncover Dermo infections at each site. Across the various sites, infection prevalence ranged from at least half to up to 100 percent. Oysters in areas with more severe low oxygen were much more likely to acquire the disease. The disease also advanced to more intense levels in oysters deployed at sites with both low oxygen and salinities at or above 12 parts per thousand. These higher-salinity waters are where Dermo causes extensive mortality in wild populations of oysters. [...] "Our results suggest that we will need to think about the effects of even short periods of exposure to low oxygen when choosing sites for oyster restoration," says Breitburg. "But, in spite of the problems we've found, these shallow waters may be high-priority candidates. If restoration is done at sufficiently large scales in shallow-water sites, where oysters can access and filter the entire water column, the oysters themselves may be able to transform habitats with water quality that is harmful to oysters to habitats in which oysters thrive." biologynews
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New Species Of Rock-Wallaby Discovered In Australia Rock-wallabies (genus Petrogale) are small to medium-sized marsupials, weighing from 1 to 12 kg. These animals are only found in mainland Australia and some offshore islands, being absent from Tasmania and New Guinea. They represent one of the largest groups of extant macropods (kangaroos, wallabies and their relatives) distributed across the country, where they inhabit complex rocky environments such as cliffs, gorges, outcrops and escarpments. In a new DNA study, Dr Potter and her colleagues found that two populations of a widespread and common species, the short-eared rock-wallaby (Petrogale brachyotis), – one from the Kimberley and western Northern Territory, the other from the northern and eastern Northern Territory – are genetically distinct species. The scientists said that members of the latter population are not only smaller (2.6 – 3.5 kg), but differ in coloration and markings being predominately dark grey/brown, with distinct head and side stripes, as well as brightly colored limbs. In contrast, the short-eared rock-wallaby from the Kimberley is larger (3.9 – 4.5 kg), lighter and greyer, with much less prominent marking. “Our study has shown that the Top End and Kimberley rock-wallaby populations are genetically and morphologically distinct and should be regarded as separate species,” said Dr Potter, who is the lead author of a paper published in the Australian Journal of Zoology. This discovery means there are now 17 known species of rock-wallabies. sci-news
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The Hives Of Others: Bees Wage War Across Species Jane Goodall discovered 40 years ago that chimpanzees wage war. Until then, she thought they were “rather nicer” than humans. But her shocking observation of animal warfare was not the first. It was the second. By then scientists had known for at least 80 years that we were not the only species to kill others of our own kind. Some insects do it, too. The Australian stingless bee Tetragonula carbonaria is notorious for inciting war, usually to usurp the hive of another. Instead of wasting time building their own hives, they just steal one and redecorate. The fights between stingless bee colonies are epic in scale, according to John Paul Cunningham of Queensland University of Technology in Australia, with “swarms from the attacking and defending hives colliding midair and fighting bees falling to the ground locked in a death grip from which neither combatant survives.” While studying such skirmishes, Cunningham and his colleagues were surprised to find that the stingless bees were being attacked not only by other colonies of their own species but also by colonies of a different species entirely, Tetragonula hockingsi. This insight marks the first known description of interspecies warfare in bees—the only other instance of this type of conflict observed throughout the animal kingdom occurs among some ant species. The stingless bees' aggression against others was so remarkable that the researchers monitored approximately 260 colonies of T. carbonaria in Queensland over five years to make sure they were not wrong. Because the bees are hard to distinguish by sight, Cunningham's team identified instances of usurpation of one species by the other by assessing the structure of the hives each year when they were opened for honey extraction. The hives of T. carbonaria are made up of well-organized cells built in a spiral pattern. Those of T. hockingsi contain cells that look haphazardly arranged. If a hive known to hold T. carbonaria had the structure of a T. hockingsi hive the following year, then that was the site of a successful seizure of territory. The researchers recorded evidence of 46 such interspecies usurpations, with victors coming from either species in equal proportion. The findings were detailed last December in the American Naturalist. [...] What induces thousands of bees to go into battle and risk death? One clue comes from the genetic analysis of the dead conducted by University of Queensland researcher James Hereward. He found that the new queen was most likely the daughter of the attacking hive's own queen—brought to her new home to continue the ruling species' lineage. When the reproductive capacity of the royal class is at stake, the potential benefits to either colony may outweigh the risks of massive casualties. scientificamerican
Chemistry
Silver-Glass Sandwich Structure Acts As Inexpensive Color Filter Northwestern University researchers have created a new technique that can transform silver into any color of the rainbow. Their simple method is a fast, low-cost alternative to color filters currently used in electronic displays and monitors. "Our technique doesn't require expensive nanofabrication techniques or a lot of materials," said Koray Aydin, assistant professor of electrical engineering and computer science at Northwestern's McCormick School of Engineering. "And it can be completed in a half hour or so." The filter's secret lies within its "sandwich-like" structure. Aydin and his team created a three-layer design, where glass is wedged two thin layers of silver film. The silver layers are thin enough to allow optical light to pass through, which then transmits a certain color through the glass and reflects the rest of the visible spectrum. By changing the thickness of the glass, Aydin was able to filter and produce different colors. "Controlling the thickness of the glass controls the color," Aydin said. "This way, we can create any color desired." [...] By making the bottom silver layer even thicker, Aydin found that the structure also acts as a color absorber because it traps light between the two metal layers. The team demonstrated a narrow bandwidth super absorber with 97 percent maximum absorption, which could have potential applications for optoelectric devices with controlled bandwidth, such as narrow-band photodetectors and light-emitting devices. The performance of Aydin's structure is comparable to that of nanostructure-based devices but bypasses the complications of nanotechnology. sciencedaily
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Researchers Report Better Solar Cells Through Chemistry In the quest for the perfect solar cell – efficient, thin, reliable and cheap – new Cornell research offers quantifiable insight into the complex chemistry of getting it just right. A research team that includes Uli Wiesner, the Spencer T. Olin Professor of Materials Science and Engineering, and Lara Estroff, associate professor of materials science and engineering, has demonstrated how to optimize the fabrication conditions of a thin film solar cell widely believed to show promise for photovoltaic applications. Their work was published Jan. 30 in Nature Communications. Thin film solar cells are made by depositing a thin layer of photovoltaic material onto a substrate, such as silicon. The type of films the Cornell researchers made are organic-inorganic metal halide perovskites, which have been widely studied for solar applications over the last several years, according to Wiesner. The researchers arrived at near-perfect solar cells using a new liquid source, called a non-halide lead acetate. While perovskite solar cells have improved rapidly in a few short years, some basic properties of the light-absorbing material still weren't well understood. Making the solar material starts with a solution of organic and inorganic molecules, and tuning the solution for smooth, defect-free perovskite films hadn't been perfected [...] The method they settled on for growing the solar cells is also a simple solution-coating, which makes it particularly appealing for commercial applications.
"By choosing the right precursor chemistry and via a simple one-step solution casting process, we obtained perovskite films with a smoothness surpassing that of vapor-deposited films, resulting in record power conversion efficiencies," Wiesner said.
phys.org
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GM Bacteria Convert Solar Energy To Liquid Fuels A new scheme for storing the energy from photovoltaic cells, in which genetically modified bacteria reduce carbon dioxide to liquid fuels with hydrogen from water-splitting, has been proposed and partially demonstrated by US researchers. Photovoltaic cells can convert solar energy to electricity, and the most obvious way of getting fuel from this process is to use the power generated to split water into hydrogen and oxygen. But this approach is problematic – hydrogen, as a gas, is difficult to transport safely, and compressed hydrogen has an energy density of only 5.6 MJ/l, compared with 32.4 MJ/l for petrol. A desirable alternative is to produce liquid hydrocarbons such as alcohols, as far more energy can be stored in the carbon-carbon bond. Solar electrochemical production of fuels, however, is not straightforward. In principle, hydrogen can reduce carbon dioxide to an alcohol. Unfortunately, inorganic catalysts for CO2 reduction often produce multiple different products. Nature, of course, has been using sunlight to convert CO2 and water into glucose for billions of years through photosynthesis. But plants are much less efficient than modern solar cells at capturing light, typically converting only 1% of the energy falling on them to biomass, whereas the best modern solar cells can convert over 40% of the incident light to electricity. In new research, Daniel Nocera and colleagues at Harvard University, US, propose coupling the efficiency of a man-made solar cell with the biofuel production capabilities of bacteria. They designed a single reaction vessel which uses solar-powered ‘artificial leaf’ technology to split water, generating hydrogen which a bacterium called Ralstonia eutropha H16 then uses to reduce carbon dioxide constantly fed into the vessel. The researchers first tried the experiment with wild-type R. eutropha, which converted about 18% of the energy supplied to bacterial biomass over the course of a single day. Next, they used a genetically modified strain of R. Eutropha, developed last year by another group, that produces isopropanol, a potential substitute for petrol with an energy density of 23.9 MJ/l. Overall, the bacteria were able to convert 4% of the electricity supplied to isopropanol. A commercial solar cell converts around 18% of incident light to electricity, which would give overall light-to-biomass and light-to-isopropanol values of 3.2% and 0.7%, respectively. These values are already on a par with fuel crops, and the researchers believe they can be increased further by optimising the reaction and producing better bacteria. royalsocietyofchemistry
Earth Science
Cleaning Up An Oily Threat New industry advice that will place Australia at the global cutting edge in the clean-up of petroleum-based contaminants in groundwater was released by the Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE) on Feb. 9. The report provides state-of-the-art technical advice to industry and government on the best ways to assess, remediate and manage petroleum contamination in soil and groundwater. Of all contaminated sites in Australia, over two-thirds feature petroleum hydrocarbons. The report specifically addresses the difficult issue of petroleum light non-aqueous phase liquids (LNAPLs). Less dense than water, these substances float on top of water and can migrate long distances, contaminating drinking water supplies and agricultural water, and emitting toxic vapours into homes and workplaces. The first of its kind in Australia, the report fills a major gap in Australia’s approach to managing a serious and widespread issue. The new guide is part of a series aimed at industry managers, environmental consultants, remediators, the owners and operators of contaminated sites, and Australian state and federal regulators seeking lasting solutions for petroleum-contaminated sites. environment.co.za
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Historic Tide Gauge Data To Shed Light On Ancient Tsunamis A tide gauge, installed in the Maltese port of Valetta in 1871, offers the only continuous record of the sea level in the Southern Mediterranean that goes back further than fifty years. However, some of the paper records it produced have deteriorated. The project coordinator, NOC’s Elizabeth Bradshaw said, “there are a limited number of long-term records of climate data in the world, so rescuing and recovering data is vital for answering questions on climate change and oceanography”. [...] The Department for Business, Innovation and Skills (BIS) have provided £32,000 from its’ ‘Breakthrough Fund’ to NOC and the UKHO in order to restore these records and make them available to the public. They hope to digitise the data via a citizen science activity, once this project is complete. Once digitised, scientists will be able to use the data to look for evidence of past tsunamis and climate change. Professor Kevin Horsburgh, from the NOC, said “Preserving long term data records like these is essential for our understanding of sea level change. The data allows scientists to identify the mechanisms that contribute to long term variability of sea level, as well as to measure the impact of each process. These variations range from long term tidal changes through to century scale change due to climate change". nationaloceanograpycenter.uk
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The Future Of Droughts In The US Central Plains And Southwest In the recent film Interstellar, a mysterious phenomenon known as "the blight" is wiping out agriculture around the world until only corn—for some reason—survives. Humanity is on the brink of starvation. While the blight may be science fiction, global warming is not, and a new study finds that future warming could decimate the U.S.'s Central Plains and Southwest regions over the next century, topping even the worst drought of the last thousand years. "I was honestly surprised at just how dry the future is likely to be," said co-author Toby Ault at Cornell University. The research, published in the first edition of Science Advances, found that future drought conditions are likely to exceed a megadrought that swept through the western U.S. in the 12th and 13th Centuries. This Medieval megadrought across the Southwest was so bad it has been blamed, at least in part, for the collapse of the Anasazi people, who disappeared from the region around that time. A megadrought is a drought that lasts longer than decade, which means the Dust Bowl of the 1930s doesn't even apply. To predict future drought risk, the scientist first turned to tree ring data going back to 1,000 AD to document past conditions, including the megadrought of the 12th and 13 centuries. Then they ran 17 computer models of future climate predictions from 2050 to 2099, including both a business-as-usual—i.e. high—carbon emission scenario and a moderate one. The researchers consistently found that future drought in the American Central Plains and Southwest "will likely exceed even the most severe megadrought periods of the Medieval era...representing an unprecedented fundamental climate shift with respect to the last millennium," they write. According to the paper, there is over an 80 percent chance of a megadrought lasting for decades in the region in the second half of this century. enn
Physics
How Iron Feels The Heat As you heat up a piece of iron, the arrangement of the iron atoms changes several times before melting. This unusual behavior is one reason why steel, in which iron plays a starring role, is so sturdy and ubiquitous in everything from teapots to skyscrapers. But the details of just how and why iron takes on so many different forms have remained a mystery. Recent work at Caltech in the Division of Engineering and Applied Science, however, provides evidence for how iron's magnetism plays a role in this curious property—an understanding that could help researchers develop better and stronger steel. [...] The laws of thermodynamics govern the natural behavior of materials, such as the temperature at which water boils and the timing of chemical reactions. These same principles also determine how atoms in solids are arranged, and in the case of iron, nature changes its mind several times at high temperatures. At room temperature, the iron atoms are in an unusual loosely packed open arrangement; as iron is heated past 912 degrees Celsius, the atoms become more closely packed before loosening again at 1,394 degrees Celsius and ultimately melting at 1,538 degrees Celsius. Iron is magnetic at room temperature, and previous work predicted that iron's magnetism favors its open structure at low temperatures, but at 770 degrees Celsius iron loses its magnetism. However, iron maintains its open structure for more than a hundred degrees beyond this magnetic transition. This led the researchers to believe that there must be something else contributing to iron's unusual thermodynamic properties. For this missing link, graduate student Lisa Mauger and her colleagues needed to turn up the heat. Solids store heat as small atomic vibrations—vibrations that create disorder, or entropy. At high temperatures, entropy dominates thermodynamics, and atomic vibrations are the largest source of entropy in iron. By studying how these vibrations change as the temperature goes up and magnetism is lost, the researchers hoped to learn more about what is driving these structural rearrangements. [...] When coupling these vibrational measurements with previously known data about the magnetic behavior of iron at these temperatures, the researchers found that iron's vibrational entropy was much larger than originally suspected. In fact, the excess was similar to the entropy contribution from magnetism—suggesting that magnetism and atomic vibrations interact synergistically at moderate temperatures. This excess entropy increases the stability of the iron's open structure even as the sample is heated past the magnetic transition. phys.org
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UCLA and USC scientists devise breakthrough technique for mapping temperature in tiny electronic devices Overheating is a major problem for the microprocessors that run our smartphones and computers. But a team of UCLA and USC scientists have made a breakthrough that should enable engineers to design microprocessors that minimize that problem: They have developed a thermal imaging technique that can “see” how the temperature changes from point to point inside the smallest electronic circuits. The technique, called plasmon energy expansion thermometry, or PEET, allows temperatures to be mapped in units as small as a nanometer, a unit of measure equal to one-billionth of a meter. This shatters the previous record for thermal imaging resolution, and it could eventually lead to faster and more capable electronics. [...] Modern microelectronic circuits contain billions of nanometer-scale transistors. Although each transistor generates only a tiny bit of heat as it operates, with that many transistors operating at once, computer chips get very hot, which is why cellphones get warm and computers need fans to run properly. To better understand precisely where the heat is being generated, engineers want to be able to map temperature in tiny electronic circuits. Currently, they use one of two thermal imaging techniques: capturing the infrared radiation the device emits or dragging a tiny thermometer back and forth across the device’s surface. But both standard techniques have fundamental limitations. Radiation-based thermometers struggle to resolve devices that are smaller than the wavelengths of the detected radiation, which typically are several thousand nanometers. And bringing a thermometer into contact with a small device generally disturbs the device’s temperature. In addition, neither has demonstrated the resolution necessary to “see” the active features in modern transistors, which are typically 22 nanometers across or smaller. Without a way to measure the temperature of extremely small circuitry, manufacturers have worked blindly, relying on simulations to estimate the devices’ temperatures. Now, PEET mapping will enable them to heat a transistor and accurately map which parts of it heat up and track how the heat is transported away — knowledge that could help engineers revolutionize the design of the nanoscale electronics inside the next generation of computing devices. ucla