Welcome to the Saturday Science Edition of Overnight News Digest
Overnight News Digest is a regular daily feature which provides noteworthy news items and commentary from around the world. The editorial staff includes side pocket, maggiejean, wader, Doctor RJ, rfall, and JML9999.
Neon Vincent is our editor-in-chief.
Special thanks go to Magnifico for starting this venerable series.
Astronomy
Does Dark Matter Cause Mass Extinctions And Geologic Upheavals? Research by New York University Biology Professor Michael Rampino concludes that Earth's infrequent but predictable path around and through our galaxy's disk may have a direct and significant effect on geological and biological phenomena occurring on Earth. In a new paper, he concludes that movement through dark matter may perturb the orbits of comets and lead to additional heating in the Earth's core, both of which could be connected with mass extinction events. The galactic disk is the region of the Milky Way Galaxy where our solar system resides. It is crowded with stars and clouds of gas and dust and also a concentration of elusive dark matter — small subatomic particles that can be detected only by their gravitational effects. Previous studies have shown that Earth rotates around the disk-shaped galaxy once every 250 million years. But Earth's path around the galaxy is wavy, with the Sun and planets weaving through the crowded disk approximately every 30 million years. Analyzing the pattern of Earth's passes through the galactic disk, Rampino notes that these disk passages seem to correlate with times of comet impacts and mass extinctions of life. The famous comet strike 66 million years ago that led to the extinction of the dinosaurs is just one example. [...] While traveling through the disk, the dark matter concentrated there disturbs the pathways of comets typically orbiting far from Earth in the outer solar system, Rampino observes. This means that comets that would normally travel at great distances from Earth instead take unusual paths, causing some of them to collide with the planet. But even more remarkably, with each dip through the disk, the dark matter can apparently accumulate within Earth's core. Eventually, the dark matter particles annihilate each other, producing considerable heat. The heat created by the annihilation of dark matter in Earth's core could trigger events such as volcanic eruptions, mountain building, magnetic field reversals, and changes in sea level, which also show peaks every 30 million years. Rampino therefore suggests that astrophysical phenomena derived from Earth's winding path through the galactic disk and the consequent accumulation of dark matter in the planet's interior can result in dramatic changes in Earth's geological and biological activity. astronomy
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The Mysterious Martian “Plumes” A paper published February 16th in Nature chronicles an unusual cloud seen for several weeks at sunrise on Mars. Beginning on March 12, 2012, amateur planetary photographers reported the small “protrusion” along the morning terminator line in the Martian southern hemisphere, within the Terra Cimmeria region at roughly 45° south, 195° west. It was visible for only a short period, lasting 50 to 70 minutes, and disappeared once the Sun rose high enough to fully illuminate the landscape. The feature became more prominent over the following days, varying in size and shape each day, and remained through much of April 2012. This “plume” was not detected by the MARCI instrument aboard the Mars Reconnaissance Orbiter, which records the planet’s surface and thin atmosphere in imaging strips much later in the Martian day, when the feature is not visible. In fact, observations were reported exclusively from amateur observers using telescopes of 8- to 16-inch in aperture and high-speed video cameras for 11 consecutive days from March 12th to 23rd, and also from April 6th to 16th. In all, 18 individual imagers detected the repeating cloud. Agustín Sánchez-Lavega (Universidad del País Vasco and Unidad Asociada Grupo Ciencias Planetarias, Spain) and colleagues measured the brightness of these features using amateur images recorded through red, green, and blue color filters, and determined the clouds to be brightest in shorter (blue) wavelengths. They used the sharpest amateur images to estimate the height of these plumes as 200 to 250 km (120 to 150 miles) above the planet’s surface. This latter estimate is what has caught so many researchers’ attention: clouds should not exist this high in Mars’s atmosphere. Clouds and dust aerosols are all over the place up to about 50 km, with water-vapor clouds being especially prominent when Mars is farthest from the Sun (as it was during these 2012 observations), says Todd Clancy (Space Science Institute). Smaller, carbon-dioxide clouds and hazes (both invisible from Earth because they’re so small and faint) also exist up to about 70 km (for the clouds) and 120 km (hazes). Above about 120 km from the surface, physical conditions in the atmosphere simply shouldn’t allow dust or ice aerosols to exist. [...] Taken together, these observations are certainly tantalizing. But the underlying topography of Mars might offer an explanation for the latest plumes. Given that Mars is relatively small, topography and meteorology would affect the shape of the night-day terminator line. If the terrain beneath the clouds is higher than the area at the sunrise terminator, the clouds might be illuminated well before the expected sunrise. The effect would make them seem higher than they are. The repeating nature of this 2012 event could then simply be a combination of the Sun’s position in the Martian sky as it enters the winter season in the southern hemisphere and illuminates thin morning clouds, which could arise for a few weeks as the season progresses. This doesn’t require the clouds to be at an unusual height at all. skyandtelescope
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The Curiosity Robot Confirms The Existence Of Methane In Mars’ Atmosphere The tunable laser spectrometer in the SAM (Sample Analysis at Mars) instrument of the Curiosity robot has unequivocally detected an episodic increase in the concentration of methane in Mars’ atmosphere after an exhaustive analysis of data obtained during 605 soles or Martian days This has been revealed in an article authored by scientists from the MSL (Mars Science Laboratory) mission, recently published in Science. One of the authors of this article is Francisco Javier Martín-Torres, a researcher at the Andalusian Institute of Earth Sciences (CSIC-UGR) This puts an end to the long controversy on the presence of methane in Mars, which started over a decade ago when this gas was first detected with telescopes from Earth. The controversy increased afterwards with the measurements obtained by orbiting satellites, some of which were occasionally contradictory. These new and incontrovertible data open paths for new research that can identify the sources that produce this gas—which could include some type of biological activity—and the mechanisms by means of which the gas is eliminated with such inexplicable speed. Ever since the Telescope in the Mauna Kea Canada-France-Hawaii Observatory first announced the detection of methane in the Martian atmosphere, several other measurements of the gas have been conducted by means of a diversity of instruments, both remotely from earth, and also by means of satellites like the Mars Express and the Mars Global Surveyor. Since methane can be the product of biological activity—practically all the existing methane in Earth’s atmosphere originates in this way—this has created great expectations that Martian methane could also be of a similar origin. canalugr
Biology
Aggressive Plant Fungus Threatens Wheat Production The spread of exotic and aggressive strains of a plant fungus is presenting a serious threat to wheat production in the UK, according to research published in Genome Biology. The research uses a new surveillance technique that could be applied internationally to respond to the spread of a wide variety of plant diseases. Wheat is a critical staple and provides 20% of the calories and over 25% of the protein consumed by humans. 'Yellow rust' caused by the fungus Puccinia striiformis f. sp. tritici (PST) is one of the plant's major diseases and is widespread across the major wheat-producing areas of the world. Infections lead to significant reductions in both grain quality and yield, with some rare events leading to the loss of an entire crop. New fungus strains have recently emerged that adapt to warmer temperatures, are more aggressive and have overcome many of the major defensive genes in wheat. Lead author Diane Saunders of the John Innes Centre and The Genome Analysis Centre (TGAC), UK, said: "Increased virulence, globalization, and climate change, are all increasing the scale and frequency of emerging plant diseases, and threatening global food security. "Our research shows that in the UK we have a newly emerging population of wheat rust fungus that could be the result of an influx of more exotic and aggressive strains that are displacing the previous population. By continuing to use these new surveillance techniques, not only can we track and respond to the ongoing threat of wheat rust, but our technology opens the door for tracking other plant pathogens, including ash dieback." [...] This new diagnostic technique, called "field pathogenomics", could be applied internationally to respond to the spread of a wide variety of plant diseases. By rapidly pinpointing a fungus's genetic make-up from field samples, the technique is able to confirm outbreaks on particular wheat varieties and provides an efficient means of confirming whether previously resistant wheat varieties have been broken by virulent strains of the pathogen. This is in contrast to current techniques which can be lengthy, costly and are only able to sample a relatively small proportion of the fungal population. biologynews
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Study Outlines Threat Of Ocean Acidification To Coastal Communities In U.S. Coastal communities in 15 states that depend on the $1 billion shelled mollusk industry (primarily oysters and clams) are at long-term economic risk from the increasing threat of ocean acidification, a new report concludes. This first nationwide vulnerability analysis, which was funded through the National Science Foundation’s National Socio-Environmental Synthesis Center, was published today in the journal Nature Climate Change. The Pacific Northwest has been the most frequently cited region with vulnerable shellfish populations, the authors say, but the report notes that newly identified areas of risk from acidification range from Maine to the Chesapeake Bay, to the bayous of Louisiana. “Ocean acidification has already cost the oyster industry in the Pacific Northwest nearly $110 million and jeopardized about 3,200 jobs,” said Julie Ekstrom, who was lead author on the study while with the Natural Resources Defense Council. She is now at the University of California at Davis. [...]
“This clearly illustrates the vulnerability of communities dependent on shellfish to ocean acidification,” said Waldbusser, a researcher in OSU’s College of Earth, Ocean, and Atmospheric Sciences and co-author on the paper. “We are still finding ways to increase the adaptive capacity of these communities and industries to cope, and refining our understanding of various species’ specific responses to acidification. “Ultimately, however, without curbing carbon emissions, we will eventually run out of tools to address the short-term and we will be stuck with a much larger long-term problem,” Waldbusser added.
oregonstate.edu
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Toxic Algae Proliferating In European, North American Lakes “We found that cyanobacterial populations have expanded really strongly in many lakes since the advent of industrial fertilizers and rapid urban growth,” said Zofia Taranu, who is the first author of the paper published in the journal Ecology Letters. “While we already knew that cyanobacteria prefer warm and nutrient-rich conditions, our study is also the first to show that the effect of nutrients, such as phosphorus and nitrogen, overwhelm those of global warming.” According to the scientists, cyanobacteria can produce toxins that cause damage to the liver or nervous system. The most common symptoms of acute exposure to harmful algal blooms are skin rash or irritation, gastroenteritis and respiratory distress. Chronic, low dose exposures over a lifetime may also result in liver tumors or endocrine disruption. Preliminary studies also suggest that a recently isolated cyanotoxin may become more concentrated across food chains and may be associated with the formation of progressive neurodegenerative diseases such as Alzheimer’s, Parkinson’s and ALS diseases. The rapid increase in cyanobacteria identified by Zofia Taranu and her colleagues in the new study points to the potential for a parallel increase in the concentration of harmful cyanotoxins. sci-news
Chemistry
Sun Rises On New Solar Route To Hydrogen A new, more efficient way of using sunlight to split water into hydrogen and oxygen has been developed by researchers in China and Israel.1 The water is first oxidised to hydrogen peroxide, which is then decomposed by a cheap chemical catalyst. The researchers believe the process, which needs only cheap, stable and environmentally friendly catalysts, is already among the most viable photolysis techniques, but that it has significant scope for optimisation too. Producing hydrogen from sunlight is challenging. The best-known procedure is photoelectrolysis: a photovoltaic cell captures the energy from the photons and the potential difference is used to split water. The minimum energy needed is 1.23eV, but the direct water-splitting reaction proceeds by a complex, four-electron pathway, so a voltage of around 2V is required to achieve a respectable reaction rate. This can call for three or even four solar cells, which increases the expense. A simpler option is photocatalysis, in which a powdered light-absorbent catalyst is simply suspended in the water, absorbing photons and catalysing the splitting process. This is, in principle, much cheaper and easier to industrialise. However, many photocatalysts are less than 0.1% efficient, require expensive materials, such as gold, or stop working quickly, often because side reactions, such as hydrogen peroxide production, poison the catalyst. Researchers at Soochow University in China led by Zhenhui Kang decided to maximise hydrogen peroxide production. They designed a composite catalyst containing cheap, earth-abundant C3N4 in a specially-designed composite containing carbon nanodots. The C3N4 photocatalyst splits water into hydrogen and hydrogen peroxide, which would normally stick to the surface of the catalyst poisoning it. However, the carbon nanodots act as a chemical catalyst that decomposes the hydrogen peroxide into water and oxygen. The nanodots also allow the catalyst to absorb more light. The new catalyst has a solar-to-hydrogen conversion efficiency of 2%. The best water-splitting photocatalyst to date is nanocrystalline cobalt oxide, which has a conversion efficiency of around 5%.2 However, this began to lose its activity within 1 hour. The current photocatalyst, however, showed no degradation after 200 days. The researchers calculate that if they optimised their photocatalyst so it had a 5% conversion rate this would lower the cost of hydrogen production to $2.30/kg (£1.50/kg) – well below the US Department of Energy's target of $4/kg. ‘Even at this stage, the number we get is only about $6,’ says co-author Yeshayahu Lifshitz, now at Technion – Israel Institute of Technology. royalscocietyofchemistry
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Consumers Can Be Confident In the Safety Of Polystyrene Foodservice Packaging The California Environmental Protection Agency’s Office of Environmental Health Hazard Assessment (OEHHA) has begun the process of listing styrene under the state’s Safe Drinking Water and Toxic Enforcement Act of 1986, which is commonly referred to as Proposition 65. In response to inquiries about OEHHA’s action related to styrene, the American Chemistry Council (ACC) issued the following statement to both highlight regulatory bodies’ determinations that polystyrene has been safely used in foodservice products for more than 50 years and that polystyrene is fundamentally different from styrene. The following statement can be attributed to Mike Levy, Senior Director for ACC’s Plastics Foodservice Packaging Group: “For more than 50 years, the U.S. Food and Drug Administration (FDA) and regulators around the world have concluded that polystyrene is safe for use in foodservice packaging. Consumers should know that styrene is a fundamentally different material with distinctly dissimilar properties from polystyrene, and therefore California’s action related to styrene under Proposition 65 has no bearing on polystyrene’s safe use in foodservice products. “OEHHA’s announcement of its Notice of Intent to List styrene under Proposition 65 merely starts an administrative process. This action is based on a review of styrene by the National Toxicology Program, which itself agrees the safety of polystyrene in foodservice is not in question - pointedly saying that styrene in polystyrene foodservice packaging is ‘not an issue.’ “Polystyrene is an FDA-approved and sanitary choice for foodservice packaging made by schools, hospitals, restaurants, food carts and stadiums. Its ability to insulate and maintain food temperature make polystyrene a great choice for keeping food fresh, hot or cold and ready to eat. It is also used in a variety of other important consumer products, such as insulation and cushioning for shipping delicate electronics.” americanchemistrycouncil
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Modern Day Alchemists Turn Toxic Runoff Into Valuable Pigments Artists have long used odd things in their work – Marcel Duchamp’s urinal on a pedestal comes to mind – but even when unusual ingredients are less obvious, they can be present. As my co-blogger Glendon Mellow points out in his superb Pinch of Pigment series, everything from raw earth minerals to ground up mummies has been used to achieve coveted colors in paints over the ages. So it may come as no surprise that an artist in Ohio is incorporating toxic river sludge into his paintings. Perhaps more fascinating is the process by which this sludge is being turned from undesireable waste to valuable art supplies. On the surface, it’s enough to make you believe in alchemy. According to the Ohio Department of Natural Resources more than 3.6 billion tons of coal have been extracted from the state since 1800. This has killed life in some 1,300 miles of streams as runoff from abandoned mines makes its way into the waterways. The polluted streams aren’t hard to find – the highly acidic water pulls heavy metals like iron out of the surrounding bedrock and turns the streams an arresting shade of orange as the iron oxidizes. Encouraged by well-established knowledge that stream reclamation could be accomplished by neutralizing the pH of the water and forcing the heavy metals to settle out, John Sabraw and Guy Riefler, both professors at Ohio University, were curious to know if the reclamation could pay for itself. So they embarked on an experiment to see whether the iron hydroxide that settled out of water they treated could be reliably turned into high quality pigments that might be subsequently incorporated into artists’ oil and acrylic paints. The answer? Yes. Natural and synthetic iron oxides have a long history as colorants because they are relatively inexpensive, non-toxic, and they occur in a wide range of colors – from pale yellows through rusty oranges, earthy reds and browns, to pure black. Artists (and the odd fan of the 1980s TV legend Bob Ross) might recognize the names of the ochers, siennas, and umbers that come from variations of this one type of pigment: iron oxide. Sabraw has been experimenting with the pigments he and Riefler have extracted and his resulting paintings are as spectacular as the story behind them.
Resonance: A exhibition of work by John Sabraw at the Thomas McCormick Gallery, Chicago.
scientificamerican
Earth Science
The Response Of The Southern Greenland Ice Sheet To The Holocene Thermal Maximum Abstract To determine the long-term sensitivity of the Greenland ice sheet to a warmer climate, we explored how it responded to the Holocene thermal maximum (8–5 cal. kyr B.P.; calibrated to calendar years before present, i.e., A.D. 1950), when lake records show that local atmospheric temperatures in Greenland were 2–4 °C warmer than the present. Records from five new threshold lakes complemented with existing geological data from south of 70°N show that the ice margin was retracted behind its present-day extent in all sectors for a limited period between ca. 7 and 4 cal. kyr B.P. and in most sectors from ca. 1.5 to 1 cal. kyr B.P., in response to higher atmospheric and ocean temperatures. Ice sheet simulations constrained by observations show good correlation with the timing of minimum ice volume indicated by the threshold lake observations; the simulated volume reduction suggests a minimum contribution of 0.16 m sea-level equivalent from the entire Greenland ice sheet, with a centennial ice loss rate of as much as 100 Gt/yr for several millennia during the Holocene thermal maximum. Our results provide an estimate of the long-term rates of volume loss that can be expected in the future as regional air and ocean temperatures approach those reconstructed for the Holocene thermal maximum. geology
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Agricultural Insecticides Pose A Global Risk To Surface Water Bodies Streams within approximately 40% of the global land surface are at risk from the application of insecticides. These were the results from the first global map to be modeled on insecticide runoff to surface waters, which has just been published in the journal Environmental Pollution by researchers from the Helmholtz Center for Environmental Research (UFZ) and the University of Koblenz-Landau together with the University of Milan, Aarhus University and Aachen University. According to the publication, particularly streams in the Mediterranean, the USA, Central America and Southeast Asia are at risk. Unlike other chemicals, agricultural pesticides are intentionally applied to the environment to help farmers control insects, weeds and other potentially harmful pests threatening agricultural production. They can therefore affect land ecosystems but also surface waters from runoff. According to estimates, ca. 4 million tons of agricultural pesticides are applied annually, equating to an average of 0.27 kilograms per hectare of the global land surface. "We know from earlier investigations for example that pesticides can reduce the biodiversity of invertebrates in freshwater ecosystems by up to 42 percent and that we can expect an increased application of pesticides as a result of climate change", explains Prof. Dr. Matthias Liess from the UFZ, who was recently appointed to a term of five years on the scientific advisory board "National Action Plan on Sustainable Use of Plant Protection Products" where he advises the Federal Ministry of Food and Agriculture. Liess warns of an increase in the application of pesticides in many developing countries as farmers increasingly switch from traditionally extensive agricultural practices to more intensive ones. Until now the global extent of the potential water pollution from the application of insecticides has remained largely unknown. enn
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Where Have All The Forests Gone? Using 5,444 Landsat satellite photographs, Do-Hyung Kim Joseph Sexton and John Townshend from the University of Maryland have proved FAO estimates of tropical forest cover to be misleading. Instead of losing a lot of forest, it seems we have lost much more, with accelerated deforestation especially between 2000 and 2005. The 20 years of HR maps reveal an accurate picture that so far has been unobtainable. We have been deceived by profit-motivated loggers and gullible UN agencies although it is impossible to penetrate rainforests enough to gain an exact picture from the ground. In fact there was a 62% acceleration in deforestation from 1990 to 2010, while the FAO were claiming to have recorded an actual 25% reduction in their Forest Resource assessments (FRA.) Venezuela, Bolivia and Brazil, the DRC and Congo and Indonesia are shown up as the grossest losers but many smaller countries have lost an equivalent amount, as a percentage of their total forest. This kind of research provides the necessary benchmark we can use now to contradict false claims ar proceed with saving those Reserves and National Parks that are often misused, instead of being maintained as habitat for vital plants and animals. It is relatively easy, for example, to provide corridors for organisms to use between small areas of forest, but maintaining those remaining trees, against an economic background of corruption and so-called productivity must be difficult for local people and national politicians alike. The tragic situation is that out of 34 nations studied, 16 had failed to provide information, or the FRA had failed to record increases in the rate of deforestation. Instead of simply losing rainforest, we also have a large increase in greenhouse gases, as these forest plants will no longer absorb carbon. The role of forest in climate cycles is also now very obvious as drought strikes areas that have never been short of water during human history. Forest, in upland areas particularly, holds water back almost like a swamp, but that precious liquid drains directly into the sea without that tree cover. The solution, now that our eyes have been opened? These people simply have to be stopped. Even the logging companies know well that they will force prices up as the last forests are removed from the planet. And their petty excuse that they will replace the trees? If only! Their expertise in acquiring new tractors to efficiently degrade habitat cannot be matched by our ability to recreate the extreme biodiversity that belongs to South America, Africa and Asia. These rare and often unknown species do not belong to the furniture and zoos of richer nations. earthtimes
Physics
How Would Life Develop If Fundamental Physics Constants Were Different? For all the progress physicists have made in figuring out the universe, they still don't know some pretty basic things. Why, for example, do fundamental particles possess the specific values of mass that they have? Presently, physicists have no explanation for this and similar questions. They do know something pretty significant, however. If the masses of particles or the values of fundamental constants were much different from what physicists have measured, carbon-based intelligent beings might not be here to measure them, because fundamental particles might not assemble into stable atoms, atoms might not form rocky planets and dying stars might not produce the chemical elements we find in our bodies. These observations have led some physicists to describe the universe as "fine-tuned" for carbon-based life. Imagine the universe is like a machine with dials used to set the properties of each important piece -- from the masses of the constituents of protons and neutrons to the rate of expansion of the universe. If many combinations of dial settings yield conditions in which complex life can evolve, physicists would say the universe is not fine-tuned. But if some of the dials have to be set very precisely to values that are not readily explained by theory, physicists would consider these parameters to be fine-tuned. [...] For the parameters that describe forces inside the atom, physicists have few hints at how fine the tuning is. In other words, how many different dial settings would create a universe that supports life as we know it? To try to answer such questions, nuclear physicist Ulf Meissner of the University of Bonn in Germany and colleagues ran complex computer simulations at the Juelich Supercomputing Center, home of the largest supercomputer in Europe. In their simulations, the scientists created a simplified model universe that included specific values for the masses of particles and the way they interact. The simulations were based on the Standard Model, physicists' main theory of fundamental particles and the strong, weak and electromagnetic forces. (The other fundamental force, gravity, is described by the general theory of relativity.) The recent development of extremely powerful computers that can crunch through a thousand trillion calculations per second has now made this possible, said Meissner. With these computers, he said, "We can explore worlds where the constants have different values." science20
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Life 'Not As We Know It' Possible On Saturn's Moon Titan A new type of methane-based, oxygen-free life form that can metabolize and reproduce similar to life on Earth has been modeled by a team of Cornell University researchers. Taking a simultaneously imaginative and rigidly scientific view, chemical engineers and astronomers offer a template for life that could thrive in a harsh, cold world - specifically Titan, the giant moon of Saturn. A planetary body awash with seas not of water, but of liquid methane, Titan could harbor methane-based, oxygen-free cells. Their theorized cell membrane, composed of small organic nitrogen compounds and capable of functioning in liquid methane temperatures of 292 degrees below zero, is published in Science Advances, Feb. 27. The work is led by chemical molecular dynamics expert Paulette Clancy and first author James Stevenson, a graduate student in chemical engineering. The paper's co-author is Jonathan Lunine, director for Cornell's Center for Radiophysics and Space Research. Lunine is an expert on Saturn's moons and an interdisciplinary scientist on the Cassini-Huygens mission that discovered methane-ethane seas on Titan. Intrigued by the possibilities of methane-based life on Titan, and armed with a grant from the Templeton Foundation to study non-aqueous life, Lunine sought assistance about a year ago from Cornell faculty with expertise in chemical modeling. Clancy, who had never met Lunine, offered to help. "We're not biologists, and we're not astronomers, but we had the right tools," Clancy said. "Perhaps it helped, because we didn't come in with any preconceptions about what should be in a membrane and what shouldn't. We just worked with the compounds that we knew were there and asked, 'If this was your palette, what can you make out of that?'" phys.org
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Synopsis: Heat-Carrying Dark Matter In Sun The brightest object in the sky may be hiding dark matter under its surface. To explain certain discrepancies between solar observations and theory, a new model proposes that a special sort of dark matter accumulates in the Sun and affects the transport of heat within the star. The standard solar model, derived from measurements of solar luminosity and other observables, predicts the temperature and density profile inside the Sun. The model has been largely successful, but it has recently come into conflict with helioseismology observations that measure pressure waves propagating through the Sun. To resolve the discrepancies, researchers have explored the possible effects of dark matter, which presumably collects in the Sun through collisions and gravitational trapping. However, theorists have so far been unable to find a dark matter model that improves the fit to solar data. Aaron Vincent of Durham University in the UK and his colleagues have devised a dark matter scenario that appears to have the right effect on the Sun’s properties. Like previous studies, they assume the dark matter consists of very little antimatter (it is “asymmetric”), in which case there are effectively no annihilations that can decrease the dark matter density inside the Sun. Their novelty is to assume that dark matter interactions with normal matter depend critically on the momentum change during particle collision. They show that dark matter particles fitting this description could carry a significant amount of heat from the core to the outer solar layers. The result would be a reduced temperature gradient that matches helioseismology measurements better than the standard solar model. The team also verified that their dark matter candidate is consistent with all existing constraints from dark matter searches. physics.aps