Brain waves reflect different types of learning

Researchers have identified neural signatures of explicit and implicit learning.

Figuring out how to pedal a bike and memorizing the rules of chess require two different types of learning, and now for the first time, researchers have been able to distinguish each type of learning by the brain-wave patterns it produces.

These distinct neural signatures could guide scientists as they study the underlying neurobiology of how we both learn motor skills and work through complex cognitive tasks, says Earl K. Miller, the Picower Professor of Neuroscience at the Picower Institute for Learning and Memory and the Department of Brain and Cognitive Sciences, and senior author of a paper describing the findings in the Oct. 11 edition of Neuron.

When neurons fire, they produce electrical signals that combine to form brain waves that oscillate at different frequencies. "Our ultimate goal is to help people with learning and memory deficits," notes Miller. "We might find a way to stimulate the human brain or optimize training techniques to mitigate those deficits."

The neural signatures could help identify changes in learning strategies that occur in diseases such as Alzheimer's, with an eye to diagnosing these diseases earlier or enhancing certain types of learning to help patients cope with the disorder, says Roman F. Loonis, a graduate student in the Miller Lab and first author of the paper. Picower Institute research scientist Scott L. Brincat and former MIT postdoc Evan G. Antzoulatos, now at the University of California at Davis, are co-authors.

Explicit versus implicit learning

Scientists used to think all learning was the same, Miller explains, until they learned about patients such as the famous Henry Molaison or "H.M.," who developed severe amnesia in 1953 after having part of his brain removed in an operation to control his epileptic seizures. Molaison couldn't remember eating breakfast a few minutes after the meal, but he was able to learn and retain motor skills that he learned, such as tracing objects like a five-pointed star in a mirror.

"H.M. and other amnesiacs got better at these skills over time, even though they had no memory of doing these things before," Miller says.

The divide revealed that the brain engages in two types of learning and memory -- explicit and implicit.

Explicit learning "is learning that you have conscious awareness of, when you think about what you're learning and you can articulate what you've learned, like memorizing a long passage in a book or learning the steps of a complex game like chess," Miller explains.

"Implicit learning is the opposite. You might call it motor skill learning or muscle memory, the kind of learning that you don't have conscious access to, like learning to ride a bike or to juggle," he adds. "By doing it you get better and better at it, but you can't really articulate what you're learning."

Many tasks, like learning to play a new piece of music, require both kinds of learning, he notes.

Brain waves from earlier studies

When the MIT researchers studied the behavior of animals learning different tasks, they found signs that different tasks might require either explicit or implicit learning. In tasks that required comparing and matching two things, for instance, the animals appeared to use both correct and incorrect answers to improve their next matches, indicating an explicit form of learning. But in a task where the animals learned to move their gaze one direction or another in response to different visual patterns, they only improved their performance in response to correct answers, suggesting implicit learning.

What's more, the researchers found, these different types of behavior are accompanied by different patterns of brain waves.

During explicit learning tasks, there was an increase in alpha2-beta brain waves (oscillating at 10-30 hertz) following a correct choice, and an increase delta-theta waves (3-7 hertz) after an incorrect choice. The alpha2-beta waves increased with learning during explicit tasks, then decreased as learning progressed. The researchers also saw signs of a neural spike in activity that occurs in response to behavioral errors, called event-related negativity, only in the tasks that were thought to require explicit learning.

The increase in alpha-2-beta brain waves during explicit learning "could reflect the building of a model of the task," Miller explains. "And then after the animal learns the task, the alpha-beta rhythms then drop off, because the model is already built."

By contrast, delta-theta rhythms only increased with correct answers during an implicit learning task, and they decreased during learning. Miller says this pattern could reflect neural "rewiring" that encodes the motor skill during learning.

"This showed us that there are different mechanisms at play during explicit versus implicit learning," he notes.

Future Boost to Learning

Loonis says the brain wave signatures might be especially useful in shaping how we teach or train a person as they learn a specific task. "If we can detect the kind of learning that's going on, then we may be able to enhance or provide better feedback for that individual," he says. "For instance, if they are using implicit learning more, that means they're more likely relying on positive feedback, and we could modify their learning to take advantage of that."

The neural signatures could also help detect disorders such as Alzheimer's disease at an earlier stage, Loonis says. "In Alzheimer's, a kind of explicit fact learning disappears with dementia, and there can be a reversion to a different kind of implicit learning," he explains. "Because the one learning system is down, you have to rely on another one."

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Geologic evidence is the forerunner of ominous prospects for a warming Earth

The image on the left shows eolian (lower) and runup bedding (upper) exposed in a roadcut on Old Land Road on Great Exuma Island (road elevation +23 meters). On the right are thick beds with fenestral porosity, or 'beach bubbles,' showing that massive waves ran up over older dunes exposed in a roadcut on Suzy Turn Road along the Atlantic Ocean east side of Providenciales, Turks and Caicos Islands, BWI.

While strong seasonal hurricanes have devastated many of the Caribbean and Bahamian islands this year, geologic studies on several of these islands illustrate that more extreme conditions existed in the past. A new analysis published in Marine Geology shows that the limestone islands of the Bahamas and Bermuda experienced climate changes that were even more extreme than historical events. In the interest of our future world, scientists must seek to understand the complexities of linked natural events and field observations that are revealed in the geologic record of past warmer climates.

In Bermuda and the Bahamas, the geology of the last interglacial (LIG; approximately 120,000 years ago) is exquisitely preserved in nearly pure carbonate sedimentary rocks. A record of superstorms and changing sea levels is exposed in subtidal, beach, storm, and dune deposits on multiple islands. Extensive studies by the authors over the past decades on these islands have documented stratigraphic, sedimentologic, and geomorphic evidence of major oceanic and climatic disruptions at the close of the last interglacial.

Dr. Paul J. Hearty, a retired Associate Professor at the University of North Carolina at Wilmington, and Dr. Blair. R. Tormey, a Coastal Research Scientist at Western Carolina University conducted an invited review of published findings. It demonstrates that during a global climate transition in the late last interglacial, also known as marine isotope substage 5e (MIS 5e), abrupt multi-meter sea-level changes occurred. Concurrently, coastlines of the Bahamas and Bermuda were impacted by massive storms generated in the North Atlantic Ocean, resulting in a unique trilogy of wave-transported deposits: megaboulders, chevron-shaped, storm-beach ridges, and runup deposits on high dune ridges.

While perhaps more mundane than the megaboulders (found only locally on Eleuthera), the sedimentological structures found within chevron ridge and runup deposits across islands throughout the Bahamas and Bermuda point to frequent and repeated inundation by powerful storm waves, in some locations leaving storm deposits tens of meters above sea level.

During the last interglacial, sea levels were about 3-9 meters higher than they are now. The geologic evidence indicates that the higher sea-levels were accompanied by intense "superstorms," which deposited giant wave-transported boulders at the top of cliffed coastlines, formed chevron-shaped, storm beach ridges in lowland areas, and left wave runup deposits on older dunes more than 30 meters above sea level. These events occurred at a time of only slightly warmer global climate and CO2 (about 275 ppm) was much lower than today.

The authors emphasize "the LIG record reveals that strong climate forcing is not required to yield major impacts on the ocean and ice caps." In our industrial world, rapidly increasing atmospheric CO2 has surpassed 400 ppm, levels not achieved since the Pliocene era about 3 million years ago, while global temperature has increased nearly 1 °C since the 1870s. Today, ice sheets are melting, sea level is rising, oceans are warming, and weather events are becoming more extreme.

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Newfoundland populated multiple times by distinct groups, DNA evidence shows

This schematic shows the settlement history of Newfoundland encompassing occupations by at least three distinct cultural groups: MA, Dorset Palaeoeskimo, and Beothuk.

Indigenous people have been on the far northeastern edge of Canada for most of the last 10,000 years, moving in shortly after the ice retreated from the Last Glacial Maximum. Archaeological evidence suggests that people with distinct cultural traditions inhabited the region at least three different times with a possible hiatus for a period between 2,000 and 3,000 years ago.

Now, researchers who've examined genetic evidence from mitochondrial DNA provide evidence that two of those groups, known as the Maritime Archaic and Beothuk, brought different matrilines to the island, adding further support to the notion that those groups had distinct population histories. The findings are published in Current Biology on October 12.

"Our paper suggests, based purely on mitochondrial DNA, that the Maritime Archaic were not the direct ancestors of the Beothuk and that the two groups did not share a very recent common ancestor," says Ana Duggan of McMaster University. "This in turn implies that the island of Newfoundland was populated multiple times by distinct groups."

The relationship between the older Maritime Archaic population and Beothuk hadn't been clear from the archaeological record. With permission from the current-day indigenous community, Duggan and her colleagues, led by Hendrik Poinar, examined the mitochondrial genome diversity of 74 ancient remains from the island together with the archaeological record and dietary isotope profiles. All samples were collected from tiny amounts of bone or teeth.

The sample set included a Maritime Archaic subadult more than 7,700 years old found in the L'Anse Amour burial mound, the oldest known burial mound in North America and one of the first manifestations of the Maritime Archaic tradition. The majority of the Beothuk samples came from the Notre Dame Bay area, where the Beothuk retreated in response to European expansions. Most of those samples are from people that lived on the island within the last 300 years. The DNA evidence showed that the two groups didn't share a common maternal ancestor in the recent past, but rather one that coalesces sometime in the more distant past.

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Star Dust Helps Explain Mysterious Dimming Star

This illustration depicts a hypothetical uneven ring of dust orbiting a mysterious dimming star about 1,000 light years from Earth.

Massimo Marengo's work in stellar astrophysics keeps returning to the mysterious dimming of Tabby's star some 1,000 light years from Earth.

Marengo, an Iowa State University associate professor of physics and astronomy, admits there are other projects on his research agenda, including infrared observations of older, giant stars and young planetary systems.

But this particular middle-aged star -- KIC 8462852, also known as Tabby's Star or Boyajian's Star, after Tabetha Boyajian, a Louisiana State University astronomer and lead author of a 2016 paper introducing the star -- is an interesting case.

First, it was found by citizen scientists using the Planet Hunters website to study measurements of star brightness taken by NASA's Kepler spacecraft. Tiny dips in a star's brightness can indicate a planet is passing in front of the star. But this star was dimming by up to 20 percent. It was also dimming irregularly, sometimes for days and months at a time. And smaller, longer-term dimming continues today.

"This is a very pathological case," Marengo said. "If we can understand this, we can understand other cases. This star can potentially tell us a lot about the kind of processes that happen in the planetary systems of regular stars. But this is very rare -- it's the only star we've found that shows these phenomena."

The unusual dimming led to a lot of potential explanations, including speculation that alien megastructures built to harvest the star's energy were passing in front of the star and creating the dips in brightness.

A scientific paper recently published by The Astrophysical Journal points to space dust circling the star as the source of the long-term dimming. The paper's findings are based on space observations from NASA's Spitzer and Swift missions, plus ground observations from amateur astronomers at Belgium's AstroLAB IRIS public observatory. All the observations were from October 2015 through December 2016, and from ultraviolet to mid-infrared wavelengths, including visible light.

The first author of the paper is Huan Meng who worked on the project as part of a postdoctoral fellowship at the University of Arizona. Marengo and Nicolas Trueba, a former Iowa State undergraduate student and current doctoral student at the University of Michigan, are among the paper's 13 other co-authors.

Marengo's role for this study was to analyze how the star's brightness changed across the electromagnetic spectrum. To do that, he combined NASA observations with the data from Belgium. Trueba developed software to help with the analysis.

It turns out there was less dimming of the star's infrared light than its ultraviolet and visible light.

That makes an alien megastructure as the cause of the mysterious dimming "more and more unlikely," Marengo said, because opaque solar panels would absorb all light equally.

Much more likely is circumstellar dust -- small particles orbiting the star -- blocked some of the shorter ultraviolet light but allowed larger wavelengths of infrared light to jump though, he said.

The "selective absorption" tells researchers that the dimming is caused by small particles a few microns across, just a few millionths of a meter, that are circling the star as dust clouds or perhaps a dust ring. Marengo said the data seems to indicate the dust particles are too large to be the kind usually found in interstellar dust clouds between the star and Earth.

A 2015 study by Marengo and two former Iowa State graduate students, published by The Astrophysical Journal Letters, looked at deep, short-terms dips in the star's brightness. That study concluded the sharp dips were most likely caused by a large debris cloud left by the destruction of a family of comets. (The new study extends the earlier research, but focusses on the long-term dimming that has also been observed.)

Even with all the recent attention, Marengo said there's still more to learn from this star.

Astronomers, for example, have only recently started to study dust disks close to stars, similar to the one that best explains the long-term dimming of Tabby's Star, Marengo said. These "warm discs" had been too difficult to detect so close to a star. Now, the unique situation at Tabby's Star may help astronomers better understand these disks.

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Intense storms batter Saturn’s largest moon, scientists report

Titan, Saturn's largest moon, behind the planet's rings. The much smaller moon Epimetheus is visible in the foreground.

Titan, the largest of Saturn's more than 60 moons, has surprisingly intense rainstorms, according to research by a team of UCLA planetary scientists and geologists. Although the storms are relatively rare -- they occur less than once per Titan year, which is 29 and a half Earth years -- they occur much more frequently than the scientists expected.

"I would have thought these would be once-a-millennium events, if even that," said Jonathan Mitchell, UCLA associate professor of planetary science and a senior author of the research, which was published Oct. 9 in the journal Nature Geoscience. "So this is quite a surprise."

The storms create massive floods in terrain that are otherwise deserts. Titan's surface is strikingly similar to Earth's, with flowing rivers that spill into great lakes and seas, and the moon has storm clouds that bring seasonal, monsoon-like downpours, Mitchell said. But Titan's precipitation is liquid methane, not water.

"The most intense methane storms in our climate model dump at least a foot of rain a day, which comes close to what we saw in Houston from Hurricane Harvey this summer," said Mitchell, the principal investigator of UCLA's Titan climate modeling research group.

Sean Faulk, a UCLA graduate student and the study's lead author said the study also found that the extreme methane rainstorms may imprint the moon's icy surface in much the same way that extreme rainstorms shape Earth's rocky surface.

On Earth, intense storms can trigger large flows of sediment that spread into low lands and form cone-shaped features called alluvial fans. In the new study, the UCLA scientists found that regional patterns of extreme rainfall on Titan are correlated with recent detections of alluvial fans, suggesting that they were formed by intense rainstorms.

The finding demonstrates the role of extreme precipitation in shaping Titan's surface, said Seulgi Moon, UCLA assistant professor of geomorphology and a co-senior author of the paper. Moon said the principle likely applies to Mars, which has large alluvial fans of its own, and to other planetary bodies. Greater understanding of the relationship between precipitation and the planetary surfaces could lead to new insights about the impact of climate change on Earth and other planets.

Titan's alluvial fans were detected by a radar instrument on the Cassini spacecraft, which began orbiting Saturn in late 2004. The Cassini mission ended in September 2017, when NASA programmed it to plunge into the planet's atmosphere as a way to safely destroy the spacecraft.

Juan Lora, a UCLA postdoctoral scholar and a co-author of the paper, said Cassini has revolutionized scientists' understanding of Titan.

Although Titan's alluvial fans are a new discovery, scientists have had eyes on the moon's surface for years. Shortly after Cassini reached Saturn, radar and other instruments showed that vast sand dunes dominated Titan's lower latitudes, while lakes and seas dominated its higher latitudes. The UCLA scientists found that the alluvial fans are mostly located between 50 and 80 degrees latitude -- close to the centers of the moon's northern and southern hemispheres, but generally slightly closer to the poles than to the equator.

Such variations in surface features suggest the moon has corresponding regional variations in precipitation, because rainfall and subsequent runoff play a key role in eroding land and filling lakes, while the absence of rainfall promotes the formation of dunes.

Previous models have shown that liquid methane generally concentrates on Titan's surface at higher latitudes. But no previous study had investigated the behavior of extreme rainfall events that might be capable of triggering major sediment transport and erosion, or shown their connection to surface observations.

The scientists primarily used computer simulations to study Titan's hydrologic cycle because observations of actual precipitation on Titan are difficult to obtain and because, given the length of each year on Titan, Cassini only observed the moon for three seasons. They found that while rain mostly accumulates near the poles, where Titan's major lakes and seas are located, the most intense rainstorms occur near 60 degrees latitude -- precisely the region where alluvial fans are most heavily concentrated.

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Engineers develop a programmable 'camouflaging' material inspired by octopus skin

This is Sepia apama (giant Australian cuttlefish) expressing its papillae for camouflage purposes.

For the octopus and cuttlefish, instantaneously changing their skin color and pattern to disappear into the environment is just part of their camouflage prowess. These animals can also swiftly and reversibly morph their skin into a textured, 3D surface, giving the animal a ragged outline that mimics seaweed, coral, or other objects it detects and uses for camouflage.

This week, engineers at Cornell University report on their invention of stretchable surfaces with programmable 3D texture morphing, a synthetic "camouflaging skin" inspired by studying and modeling the real thing in octopus and cuttlefish. The engineers, along with collaborator and cephalopod biologist Roger Hanlon of the Marine Biological Laboratory (MBL), Woods Hole, report on their controllable soft actuator in the October 13 issue of Science.

Led by James Pikul and Robert Shepherd, the team's pneumatically-activated material takes a cue from the 3D bumps, or papillae, that cephalopods can express in one-fifth of a second for dynamic camouflage, and then retract to swim away without the papillae imposing hydrodynamic drag.

"Lots of animals have papillae, but they can't extend and retract them instantaneously as octopus and cuttlefish do," says Hanlon, who is the leading expert on cephalopod dynamic camouflage. "These are soft-bodied molluscs without a shell; their primary defense is their morphing skin."

Papillae are examples of a muscular hydrostat, biological structures that consist of muscle with no skeletal support (such as the human tongue). Hanlon and members of his laboratory, including Justine Allen, now at Brown University, were the first to describe the structure, function, and biomechanics of these morphing 3D papillae in detail.

"The degrees of freedom in the papillae system are really beautiful," Hanlon says. "In the European cuttlefish, there are at least nine sets of papillae that are independently controlled by the brain. And each papilla goes from a flat, 2D surface through a continuum of shapes until it reaches its final shape, which can be conical or like trilobes or one of a dozen possible shapes. It depends on how the muscles in the hydrostat are arranged." The engineers' breakthrough was to develop synthetic tissue groupings that allow programmable, 2D stretchable materials to both extend and retract a range of target 3D shapes.

"Engineers have developed a lot of sophisticated ways to control the shape of soft, stretchable materials, but we wanted to do it in a simple way that was fast, strong, and easy to control," says lead author James Pikul, currently an assistant professor in the Department of Mechanical Engineering and Applied Mechanics at the University of Pennsylvania. "We were drawn by how successful cephalopods are at changing their skin texture, so we studied and drew inspiration from the muscles that allow cephalopods to control their texture, and implemented these ideas into a method for controlling the shape of soft, stretchable materials."

"This is a classic example of bio-inspired engineering" with a range of potential applications, Hanlon says. For example, the material could be controllably morphed to reflect light in its 2D spaces and absorb light in its 3D shapes. "That would have applications in any situation where you want to manipulate the temperature of a material," he says.

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Genetically Engineered Chickens Lay Cancer-Fighting Eggs

Japanese researchers have found a novel way to dramatically slash the cost of manufacturing a pricey drug used to treat cancer and hepatitis: by genetically programing chickens to lay drug-infused eggs.

The technique uses genomic editing to prompt the chickens to lay eggs containing a pharmaceutical agent known as interferon beta, a type of protein that plays an important role in the functioning immune system, according to a report in The Japan News.

The scientists introduced genes that produce interferon beta into cells that are the precursors of chicken sperm, the Japanese outlet reported. Those cells were used to fertilize eggs, which then inherited those genes. That allowed the hens grown from those eggs to themselves lay eggs containing the cancer-fighting agent.

“This is a result that we hope leads to the development of cheap drugs,” Hironobu Hojo of Osaka University said.

For now, the cancer-fighting eggs are to be used solely in a laboratory setting. But eventually, if the chicken-laid drugs pass inspection by health authorities, they could be approved for human consumption.

“In the future, it will be necessary to closely examine the characteristics of the agents contained in the eggs and determine their safety as pharmaceutical products,” Professor Hojo said.

As early as next year, the drug produced by the chickens may begin to be sold at a price about half that of the conventional means of production. Eventually, the scientists hope to reduce the price to under a tenth of the conventional method.

Conventional production requires large-scale cultivation facilities and costs roughly $250-$900 for just a few micrograms of the substance.

Read more at Seeker

Haumea, the most peculiar of Pluto companions, has a ring around it

Artist concept of Haumea, with the correct proportions of the main body and the ring. The ring is at a distance of 2287 kilometers from the center of the main body and is darker than the surface of the dwarf planet itself.

At the ends of the Solar System, beyond the orbit of Neptune, there is a belt of objects composed of ice and rocks, among which four dwarf planets stand out: Pluto, Eris, Makemake and Haumea. The latter is the least well known of the four and was recently the object of an international observation campaign which was able to establish its main physical characteristics. The study, led by astronomers from the Institute of Astrophysics of Andalusia and published in Nature, reveals the presence of a ring around the planet.

Trans-neptunian objects are difficult to study because of their small size, their low brightness, and the enormous distances that separate us from them. A very efficient but complex method lies in the study of stellar occultations, or the passing of these objects in front of a star (like a small eclipse). It allows astronomers to determine the main physical characteristics of an object (size, shape, and density) and has been successfully applied to dwarf planets Pluto, Eris and Makemake.

"We predicted that Haumea would pass in front of a star on the 21st of January 2017, and twelve telescopes from ten different European observatories converged on the phenomenon," says José Luis Ortiz, researcher at the Institute of Astrophysics of Andalusia (IAA-CSIC) in charge of the study. "This deployment of technical means allowed us to reconstruct with a very high precision the shape and size of dwarf planet Haumea, and discover to our surprise that it is considerably bigger and less reflecting than was previously believed. It is also much less dense than previously thought, which answered questions that had been pending about the object."

Haumea is an interesting object: it rotates around the Sun in an elliptic orbit which takes it 284 years to complete (it presently lies fifty times further from the Sun than the Earth), and it takes 3.9 hours to rotate around its axis, much less than any other body measuring more than a hundred kilometers long in the entire Solar System. This rotational speed causes it to flatten out, giving it an ellipsoid shape similar to a rugby ball. The recently published data reveal that Haumea measures 2,320 kilometers in its largest axis -- almost the same as Pluto -- but lacks the global atmosphere that Pluto has.

First Trans-Neptunian Object With a Ring

"One of the most interesting and unexpected findings was the discovery of a ring around Haumea. Until a few years ago we only knew of the existence of rings around the giant planets; then, recently, our team discovered that two small bodies situated between Jupiter and Neptune, belonging to a group called centaurs, have dense rings around them, which came as a big surprise. Now we have discovered that bodies even farther away than the centaurs, bigger and with very different general characteristics, can also have rings," says Pablo Santos-Sanz, another member of the IAA-CSIC team.

According to the data obtained from the stellar occultation, the ring lies on the equatorial plane of the dwarf planet, just like its biggest satellite, Hi´iaka, and it displays a 3:1 resonance with respect to the rotation of Haumea, which means that the frozen particles which compose the ring rotate three times slower around the planet than it rotates around its own axis.

"There are different possible explanations for the formation of the ring; it may have originated in a collision with another object, or in the dispersal of surface material due to the planet's high rotational speed," says Ortiz (IAA-CSIC). It is the first time a ring has been discovered around a trans-neptunian object, and it shows that the presence of rings could be much more common than was previously thought, in our Solar System as well as in other planetary systems.

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The moon once had an atmosphere

Artistic impression of the Moon, looking over the Imbrium Basin, with lavas erupting, venting gases, and producing a visible atmosphere.

A new study shows that an atmosphere was produced around the ancient Moon, 3 to 4 billion years ago, when intense volcanic eruptions spewed gases above the surface faster than they could escape to space. The study was published in Earth and Planetary Science Letters.

When one looks up at the Moon, dark surfaces of volcanic basalt can be easily seen to fill large impact basins. Those seas of basalt, known as maria, erupted while the interior of the Moon was still hot and generating magmatic plumes that sometimes breached the lunar surface and flowed for hundreds of kilometers. Analyses of Apollo samples indicate those magmas carried gas components, such as carbon monoxide, the ingredients for water, sulfur, and other volatile species.

In new work, Dr. Debra H. Needham, Research Scientist of NASA Marshall Space Flight Center, and Dr. David A. Kring, Senior Staff Scientist, at the Lunar and Planetary Institute, calculated the amounts of gases that rose from the erupting lavas as they flowed over the surface and showed that those gases accumulated around the Moon to form a transient atmosphere. The atmosphere was thickest during the peak in volcanic activity about 3.5 billion years ago and, when created, would have persisted for about 70 million years before being lost to space.

The two largest pulses of gases were produced when lava seas filled the Serenitatis and Imbrium basins about 3.8 and 3.5 billion years ago, respectively. The margins of those lava seas were explored by astronauts of the Apollo 15 and 17 missions, who collected samples that not only provided the ages of the eruptions, but also contained evidence of the gases produced from the erupting lunar lavas.

This new picture of the Moon has important implications for future exploration. The analysis of Needham and Kring quantifies a source of volatiles that may have been trapped from the atmosphere into cold, permanently shadowed regions near the lunar poles and, thus, may provide a source of ice suitable for a sustained lunar exploration program. Volatiles trapped in icy deposits could provide air and fuel for astronauts conducting lunar surface operations and, potentially, for missions beyond the Moon.

The new research was initiated from the LPI-Johnson Space Center's Center for Lunar Science and Exploration, led by Kring and supported by NASA's Solar System Exploration Research Virtual Institute. Needham is a former postdoctoral researcher at the LPI.

From Science Daily

Devourer of planets? Astronomers dub star 'Kronos'

Sun-like star Kronos shows signs of having ingested 15 Earth masses worth of rocky planets, prompting Princeton astronomers to nickname it for the Titan who ate his young. This artist's rendering of the diverse rocky planets in our galaxy hints at what Kronos's planets might have looked like before the star enveloped them.

In mythology, the Titan Kronos devoured his children, including Poseidon (better known as the planet Neptune), Hades (Pluto) and three daughters.

So when a group of Princeton astronomers discovered twin stars, one of which showed signs of having ingested a dozen or more rocky planets, they named them after Kronos and his lesser-known brother Krios. Their official designations are HD 240430 and HD 240429, and they are both about 350 light years from Earth.

The keys to the discovery were first confirming that the widely separated pair are in fact a binary pair, and secondly observing Kronos' strikingly unusual chemical abundance pattern, explained Semyeong Oh, a graduate student in astrophysical sciences who is lead author on a new paper describing Kronos and Krios. Oh works with David Spergel, the Charles A. Young Professor of Astronomy on the Class of 1897 Foundation and director of the Flatiron Institute's Center for Computational Astrophysics.

Other co-moving star pairs have had different chemistries, Oh explained, but none as dramatic as Kronos and Krios.

Most stars that are as metal-rich as Kronos "have all the other elements enhanced at a similar level," she said, "whereas Kronos has volatile elements suppressed, which makes it really weird in the general context of stellar abundance patterns."

In other words, Kronos had an unusually high level of rock-forming minerals, including magnesium, aluminum, silicon, iron, chromium and yttrium, without an equally high level of volatile compounds -- those that are most often found in gas form, like oxygen, carbon, nitrogen and potassium.

Kronos is already outside the galactic norm, said Oh, and in addition, "because it has a stellar companion to compare it to, it makes the case a little stronger."

Kronos and Krios are far enough apart that some astronomers have questioned whether the two were in fact a binary pair. Both are about 4 billion years old, and like our own, slightly older sun, both are yellow G-type stars. They orbit each other infrequently, on the order of every 10,000 years or so. An earlier researcher, Jean-Louis Halbwachs of the Observatoire Astronomique of Strasbourg, had identified them as co-moving -- moving together -- in his 1986 survey, but Oh independently identified them as co-moving based on two-dimensional astrometric information from the European Space Agency's Gaia mission.

During a group research discussion at the Flatiron Institute, a colleague suggested pooling their data sets. John Brewer, a postdoctoral researcher from Yale University visiting at Columbia University, had been using data from the Keck Observatory on Mauna Kea, Hawaii, to calculate the spectrographic chemistries and radial velocities of stars.

"John suggested that maybe we should cross-match my co-moving catalogue with his chemical-abundance catalogue, because it's interesting to ask whether they have the same compositions," Oh said.

Binary stars should have matching radial velocities, but that information hadn't been available in the Gaia dataset, so seeing their matching velocities in Brewer's data supported the theory that Kronos and Krios, though two light years apart, were a binary set.

Then the researchers noticed the extreme chemical differences between them.

"I'm very easily excitable, so as soon as they had the same radial velocities and different chemistry, my mind already started racing," said Adrian Price-Whelan, a Lyman Spitzer, Jr. Postdoctoral Fellow in Astrophysical Sciences and a co-author on the paper.

Oh took more convincing, both scientists recalled. "Semyeong is careful and was skeptical," said Price-Whelan, so her first step was to double-check all the data. Once simple error had been ruled out, they began entertaining various theories. Maybe Kronos and Krios had accreted their planetary disks at different times during stellar formation. That one can't be tested, said Price-Whelan, but it seems unlikely.

Maybe they only started moving together more recently, after trading partners with another pair of binary stars, a process known as binary exchange. Oh ruled that out with "a simple calculation," she said. "She's very modest," Price-Whelan noted.

Oh's skepticism was finally overcome when she plotted the chemical abundance pattern as a function of condensation temperature -- the temperatures at which volatiles condense into solids. Condensation temperatures play a key role in planetary formation because rocky planets tend to form where it's warm -- closer to a star -- while gas giants form more easily in the colder regions far from their star.

She immediately observed that all of the minerals that solidify below 1200 Kelvin were the ones Kronos was low in, while all the minerals that solidify at warmer temperatures were abundant.

"Other processes that change the abundance of elements generically throughout the galaxy don't give you a trend like that," said Price-Whelan. "They would selectively enhance certain elements, and it would appear random if you plotted it versus condensation temperatures. The fact that there's a trend there hinted towards something related to planet formation rather than galactic chemical evolution."

That was her "Aha!" moment, Oh said. "All of the elements that would make up a rocky planet are exactly the elements that are enhanced on Kronos, and the volatile elements are not enhanced, so that provides a strong argument for a planet engulfment scenario, instead of something else."

Oh and her colleagues calculated that gaining this many rock-forming minerals without many volatiles would require engulfing roughly 15 Earth-mass planets.

Eating a gas giant wouldn't give the same result, Price-Whelan explained. Jupiter, for example, has an inner rocky core that could easily have 15 Earth masses of rocky material, but "if you were to take Jupiter and throw it into a star, Jupiter also has this huge gaseous envelope, so you'd also enhance carbon, nitrogen -- the volatiles that Semyeong mentioned," he said. "To flip it around, you have to throw in a bunch of smaller planets."

While no known star has 15 Earth-sized planets in orbit around it, the Kepler space telescope has detected many multi-planet systems, said Jessie Christiansen, an astronomer at the NASA Exoplanet Science Institute at the California Institute of Technology, who was not involved in the research. "I see no problem with there being more than 15 Earth masses of accretable material around a solar-type star." She pointed to Kepler-11, which has more than 22 Earth masses of material in six planets with close orbits, or HD 219134, which has at least 15 Earth masses of material in its inner four planets.

"At the moment, we are still at the stage of piecing together different observations to determine how and when exoplanets form," said Christiansen. "It's difficult to directly observe planet formation around young stars -- they are typically shrouded in dust, and the stars themselves are very active, which makes it hard to disentangle any signals from the planets. So we have to infer what we can from the limited information we have. If borne out, this new window onto the masses and compositions of the material in the early stages of planetary systems may provide crucial constraints for planet formation theories."

Read more at Science Daily

Paleogenomic analysis sheds light on Easter Island mysteries

Rapa Nui National Park on Easter Island.

Easter Island is a place of mystery that has captured the public imagination. Famous for ancient carved statues and a location so remote it boggles the mind, the island presents a captivating puzzle for researchers eager to understand how and when it became inhabited, and by whom.

New paleogenomic research conducted by an international team led by UC Santa Cruz sheds light on those questions by ruling out the likelihood that inhabitants of Easter Island intermixed with South Americans prior to the arrival of Europeans on the island in 1722.

Lars Fehren-Schmitz, associate professor of anthropology at UC Santa Cruz, presents his findings in a new paper published in the Oct. 12 edition of Current Biology.

The team analyzed bone fragments from the ancient skeletal remains of five individuals that were excavated in the 1980s and became part of the Kon-Tiki Museum's collection in Oslo. Each sample, which had been used in a previous study, yielded less than 200 milligrams of material. Three individuals lived prior to European contact, and two lived after.

"We found no evidence of gene flow between the inhabitants of Easter Island and South America," said Fehren-Schmitz. "We were really surprised we didn't find anything. There's a lot of evidence that seems plausible, so we were convinced we would find direct evidence of pre-European contact with South America, but it wasn't there."

Questions surrounding Pacific islanders' contact with South Americans are hotly debated among anthropologists. An earlier study found genetic traces of early inhabitants of the Americas in present-day indigenous residents of Easter Island. Those researchers posited that the intermixing most likely occurred between 1280 and 1425. Fehren-Schmitz was the first to use paleogenomic analysis to directly test that hypothesis; his findings indicate that contact must have taken place after 1722.

Slavery, whaling, mass deportations, and other activities that followed European contact gave rise to opportunities for intermixing that likely left the genetic imprint seen in islanders today, he said.

"The most likely scenario is that there wasn't a single episode," said Fehren-Schmitz. Acknowledging that his results answer one question but leave many others unanswered, he said, "The story is simply more complicated than we expected."

A member of the UC Santa Cruz Paleogenomics Laboratory, Fehren-Schmitz uses DNA sequences recovered from preserved biological remains to trace molecular evolutionary processes through time. The analysis of DNA from ancient humans sheds light on human evolution, researchers' understanding of how humans diverged and interacted over time, and how the forces of culture and biology have shaped human genetic diversity.

"This study highlights the value of ancient DNA to test hypotheses about past population dynamics," said Fehren-Schmitz. "We know the island's modern populations have some Native American ancestry, and now we know that early inhabitants did not. So the big questions remain: Where and when did these groups interact to change the genetic signature of Easter Islanders?"

One of the mysteries of Easter Island -- also called Rapa Nui -- is how the island came to be populated. Located nearly 1,300 miles from the nearest inhabited island, it is 2,200 miles from central Chile on the nearest continent of South America. Some archaeologists have suggested that sea travel between Polynesia and the Americas was plausible, leading to the intermingling of those populations and perhaps even the peopling of the Americas. But plausibility isn't proof, noted Fehren-Schmitz.

"We want to do more work to determine more precisely when this gene flow between Native Americans and the people of Rapa Nui occurred, and where in the Americas it originated," he said. "The population dynamics of these regions are fascinating. We need to study the ancient populations of other islands -- if remains exist."

This project also demonstrates the value of using recently developed research methods on materials from older museum collections. Tropical conditions make preservation difficult, and rib fragments are generally too soft to be desirable, but recent technological advances opened up new possibilities, said Fehren-Schmitz.

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Genes responsible for diversity of human skin colors identified

This is a Mursi woman of Nilo-Saharan ancestry. Nilo-Saharan pastoralist populations possess some of the darkest skin in Africa. Researchers from the University of Pennsylvania found mutations associated with both light and dark pigmentation in a genome-wide association study of diverse African populations.

Human populations feature a broad palette of skin tones. But until now, few genes have been shown to contribute to normal variation in skin color, and these had primarily been discovered through studies of European populations.

Now, a study of diverse African groups led by University of Pennsylvania geneticists has identified new genetic variants associated with skin pigmentation. The findings help explain the vast range of skin color on the African continent, shed light on human evolution and inform an understanding of the genetic risk factors for conditions such as skin cancer.

"We have identified new genetic variants that contribute to the genetic basis of one of the most strikingly variable traits in modern humans," said Sarah Tishkoff, a Penn Integrates Knowledge Professor and the David and Lyn Silfen University Professor in Genetics and Biology with appointments in the Perelman School of Medicine and School of Arts and Sciences. "When people think of skin color in Africa most would think of darker skin, but we show that within Africa there is a huge amount of variation, ranging from skin as light as some Asians to the darkest skin on a global level and everything in between. We identify genetic variants affecting these traits and show that mutations influencing light and dark skin have been around for a long time, since before the origin of modern humans."

The findings are published in the journal Science. Tishkoff, senior author, collaborated with first author and lab member Nicholas Crawford, a postdoctoral fellow, and a multi-institutional, international team.

Tishkoff has long studied the genetics of African populations, looking at traits such as height, lactose tolerance, bitter-taste sensitivity and high-altitude adaptation. Skin color emerged as a trait of interest from her experience working on the continent and seeing the diversity present across groups.

"Skin color is a classic variable trait in humans, and it's thought to be adaptive," Tishkoff said. "Analysis of the genetic basis of variation in skin color sheds light on how adaptive traits evolve, including those that play a role in disease risk."

Both light and dark skin pigmentations confer benefits: Darker skin, for example, is believed to help prevent some of the negative impacts of ultraviolet light exposure, while lighter skin is better able to promote synthesis of vitamin D in regions with low ultraviolet light exposure.

To objectively capture the range of skin pigmentation in Africa, Tishkoff and colleagues used a color meter to measure the light reflectance of the skin of more than 2,000 Africans from ethnically and genetically diverse populations. They took the measurement from the inner arm, when sun exposure is minimal. The measurements can be used to infer levels of the skin pigment melanin. They obtained a range of measurements; the darkest skin was observed in Nilo-Saharan pastoralist populations in eastern Africa, and the lightest skin was observed in San hunter-gatherer populations in southern Africa.

The researchers obtained genetic information from nearly 1,600 people, examining more than 4 million single nucleotide polymorphisms across the genome, places where the DNA code may differ by one "letter." From this dataset the researchers were able to do a genome-wide association study and found four key areas of the genome where variation closely correlated with skin color differences.

The region with the strongest associations was in and around the SLC24A5 gene, one variant of which is known to play a role in light skin color in European and some southern Asian populations and is believed to have arisen more than 30,000 years ago. This variant was common in populations in Ethiopia and Tanzania that were known to have ancestry from southeast Asia and the Middle East, suggesting it was carried into Africa from those regions and, based on its frequency, may have been positively selected.

Another region, which contains the MFSD12 gene, had the second strongest association to skin pigmentation. This gene is expressed at low levels in depigmented skin in individuals with vitiligo, a condition where the skin loses pigment in some areas.

"I still rememeber the 'ah ha!' moment when we saw this gene was associated with vitiligo," said Crawford. "That's when we knew we'd found something new and exciting."

The team found that mutations in and around this gene that were associated with dark pigmentation were present at high frequencies in populations of Nilo-Saharan ancestry, who tend to have very dark skin, as well as across sub-Saharan populations, except the San, who tend to have lighter skin. They also identified these variants, as well as others associated with dark skin pigmentation, in South Asian Indian and Australo-Melanesian populations, who tend to have the darkest skin coloration outside of Africa.

"The origin of traits such as hair texture, skin color and stature, which are shared between some indigenous populations in Melanesia and Australia and some sub-Saharan Africans, has long been a mystery." Tishkoff said. "Some have argued it's because of convergent evolution, that they independently evolved these mutations, but our study finds that, at genes associated with skin color, they have the identical variants associated with dark skin as Africans.

"Our data are consistent with a proposed early migration event of modern humans out of Africa along the southern coast of Asia and into Australo-Melanesia and a secondary migration event into other regions. However, it is also possible that there was a single African source population that contained genetic variants associated with both light and dark skin and that the variants associated with dark pigmentation were maintained only in South Asians and Australo-Melanesians and lost in other Eurasians due to natural selection."

Also of interest was that genetic variants at MFSD12, OCA2, and HERC2 associated with light skin pigmentation were at highest frequency in the African San population, which has the oldest genetic lineages in the world, as well as in Europeans.

MFSD12 is highly expressed in melanocytes, the cells that produce melanin. To verify the gene's role in contributing to skin pigmentation, the researchers blocked expression of the gene in cells in culture and found an increase in production of eumelanin, the pigment type responsible for black and brown skin, hair and eye color. Knocking out the gene in zebrafish caused a loss of cells that produce yellow pigment. And in mice, knocking out the gene changed the color of their coat from agouti, caused by hairs with a red and yellow pigment, to a uniform gray by eliminating production of pheomelanin, a type of pigment also found in humans.

"Apart from one study showing that MFSD12 was associated with vitiligo lesions, we didn't know much else about it," said Crawford, "so these functional assays were really crucial."

"We went beyond most genome-wide association studies to do functional assays," Tishkoff said, "and found that knocking out MFSD12 dramatically impacted the pigmentation of fish and mice. It's pointing to this being a very conserved trait across species.

"We don't know exactly why, but blocking this gene causes a loss of pheomelanin production and an increase in eumelanin production," Tishkoff added. "We also showed that Africans have a lower level of MFSD12 expression, which makes sense, as low levels of the gene means more eumelanin production."

A collaborator on the work, Michael Marks, a professor in the departments of Pathology & Laboratory Medicine and of Physiology at Children's Hospital of Philadelphia and at Penn Medicine, demonstrated that the MFSD12 gene influences eumelanin pigmentation in a novel manner. Unlike other pigmentation genes, which are expressed mainly in melanosomes, the organelle where melanin is produced, MFSD12 is expressed in lysosomes, a distinct organelle from the melanosomes that produce eumelanin.

"Our results suggest there must be some kind of as-yet-uncharacterized form of cross-talk between lysosomes and the melanosomes that make eumelanins," Marks said. "Figuring out how this works might provide new ideas for ways to manipulate skin pigmentation for therapeutic means.

"In addition," Marks said, "the fact that loss of MFSD12 expression had opposite effects on the two types of melanins, increasing eumelanin production while suppressing pheomelanin, suggests that melanosomes that make pheomelanins might be more related to lysosomes than those that make eumelanin."

Additional associations with skin color were found in the OCA2 and HERC2 genes, which have been linked with skin, eye and hair color variation in Europeans, though the mutations identified are novel. Mutations in OCA2 also cause a form of albinism that is more common in Africans than in other populations. The researchers observed genetic variants in a neighboring gene, HERC2, which regulates the expression of OCA2. Within OCA2, they identified a variant common in Europeans and San that is associated with a shorter version of the protein, with an altered function. They observed a signal of balancing selection of OCA2, meaning that two different versions of the gene have been maintained, in this case for more than 600,000 years.

"What this tells us," Tishkoff said, "is there is likely some selective force maintaining these two alleles. It is likely that this gene is playing a role in other aspects of human physiology which are important."

A final genetic region the researchers found to be associated with skin pigmentation included genes that play a role in ultraviolet light response and melanoma risk. The top candidate gene in the region is DDB1, involved in repairing DNA after exposure to UV light.

"Africans don't get melanoma very often," Tishkoff said. "The variants near these genes are highest in populations who live in areas of the highest ultraviolet light intensity, so it makes sense that they may be playing a role in UV protection."

The mutations identified by the team play a role in regulating expression of DDB1 and other nearby genes.

"Though we don't yet know the mechanism by which DDB1 is impacting pigmentation, it is of interest to note that this gene, which is highly conserved across species, also plays a role in pigmentation in plants such as tomatoes," said Tishkoff.

The team saw evidence that this region of the genome has been a strong target of natural selection outside of Africa; mutations associated with light skin color swept to nearly 100 percent frequency in non-Africans, one of few examples of a "selective sweep" in all Eurasians; the age of the selective sweep was estimated to be around 60,000 to 80,000 years old, around the time of migration of modern humans out of Africa.

One additional takeaway from this work is a broader picture of the evolution of skin color in humans. Most of the genetic variants associated with light and dark pigmentation from the study appear to have originated more than 300,000 years ago, and some emerged roughly 1 million years ago, well before the emergence of modern humans. The older version of these variants in many cases was the one associated with lighter skin, suggesting that perhaps the ancestral state of humans was moderately pigmented rather than darkly pigmented skin.

"If you were to shave a chimp, it has light pigmentation," Tishkoff said, "so it makes sense that skin color in the ancestors of modern humans could have been relatively light. It is likely that when we lost the hair covering our bodies and moved from forests to the open savannah, we needed darker skin. Mutations influencing both light and dark skin have continued to evolve in humans, even within the past few thousand years."

Tishkoff noted that the work underscores the diversity of African populations and the lack of support for biological notions of race.

Read more at Science Daily

One of planet's largest volcanic eruptions

The Palouse River in southeastern Washington State drops nearly 200 feet through cliffs of basalt created by scores of lava flows 10 to 16 million years ago. Washington State University researchers have determined that one flow constituted one of the Earth's largest known volcanic eruptions, a millennia-long spewing of sulfuric gas that blocked out the sun and cooled the planet.

Washington State University researchers have determined that the Pacific Northwest was home to one of the Earth's largest known volcanic eruptions, a millennia-long spewing of sulfuric gas that blocked out the sun and cooled the planet.

Only two other eruptions -- the basalt floods of the Siberian Traps and the Deccan Traps -- were larger, and they led to two of the Earth's great extinctions.

"This would have been devastating regionally because of the acid-rain effect from the eruptions," said John Wolff, a professor in the WSU School of the Environment. "It did have a global effect on temperatures, but not drastic enough to start killing things, or it did not kill enough of them to affect the fossil record."

The research, which was funded by the National Science Foundation, appears in Geology, the top journal in the field. Starting 16.5 million years ago, they say, vents in southeast Washington and northeast Oregon put out a series of flows that reached nearly to Canada and all the way to the Pacific Ocean. The flows created the Wapshilla Ridge Member of the Grande Ronde Basalt, a kilometer-thick block familiar to travelers in the Columbia Gorge and most of Eastern Washington. The researchers say it is "the largest mapped flood basalt unit on Earth."

The researchers estimate that, over tens of thousands of years, the floods put out between 242 and 305 billion tons of sulfur dioxide. That's more than 4,000 times the output of the 1815 Mount Tambora eruption in present-day Indonesia. That eruption blanketed the Earth in an aerosol veil, creating the "Year Without A Summer" and food shortages across the northern hemisphere.

The volume of gas emitted from the Wapshilla Ridge lavas, said the researchers, "is equivalent to a Tambora eruption every day for 11 to 16 years."

Most of the lava's gases were released during the eruptions, but some of the gas remained trapped in crystals near the volcanic vents. Klarissa Davis, lead author of the paper, analyzed the gases as part of her doctoral studies. The other authors are Michael Rowe, now at the University of Auckland, and Owen Neill, now at the University of Michigan.

Wolff puts the eruption into one of three classes of cataclysms, the other two being a caldera eruption like the Yellowstone volcano and the impact of an asteroid. A similar eruption today "would devastate modern society globally," said Wolff.

The eruption also provides an insight into the workings of climate change. It took place in what is known as the Miocene Climactic Optimum, or MCO, when some 50 million years of cooling was interrupted by 5 to 6 degrees Fahrenheit of warming. But at its peak, the MCO had a brief cooling period that coincides with the Wapshilla eruption and its profusion of sulfur dioxide.

Sulfur dioxide is now bandied about as a possible tool for engineering a break in the Earth's current warming trend, though Wolff is not particularly keen on the idea.

Read more at Science Daily

Scientists discover one of the most luminous 'new stars' ever

Left: the nova system before eruption. Right: the nova system in outburst.

Astronomers have today announced that they have discovered possibly the most luminous 'new star' ever -- a nova discovered in the direction of one of our closest neighboring galaxies: The Small Magellanic Cloud.

Astronomers from the University of Leicester contributed to the discovery by using the Swift satellite observatory to help understand what was likely the most luminous white dwarf eruption ever seen.

A nova happens when an old star erupts dramatically back to life. In a close binary star system consisting of a white dwarf and a Sun-like companion star, material is transferred from the companion to the white dwarf, gradually building up until it reaches a critical pressure. Then uncontrolled nuclear burning occurs, leading to a sudden and huge increase in brightness. It is called a nova because it appeared to be a new star to the ancients.

Novae are usually found in visible light, but often go on to emit higher energy X-rays as well. Together, these different datasets provide information on the white dwarf, such as its temperature and chemical composition.

Using telescopes from South Africa to Australia to South America, as well as the orbiting Swift observatory, a team led by the South African Astronomical Observatory has revealed that the nova SMCN 2016-10a, which was discovered on 14th October 2016, is the most luminous nova ever discovered in the SMC, and one of the brightest ever seen in any galaxy. The observations that they made are the most comprehensive ever for a nova in this galaxy.

The SMC, 200,000 light-years away, is one of our closest companion galaxies; it is a dwarf galaxy, very much less massive than our own. Novae occur frequently in our Galaxy, with a rate of around 35 each year, but SMCN 2016-10a is the first nova to have been detected in the SMC since 2012.

Dr Kim Page, a member of the Swift team at the University of Leicester, led the X-ray analysis, while Paul Kuin, from the Mullard Space Science Laboratory, University College London, organised the UV data.

Dr Page said: "Swift's ability to respond rapidly, together with its daily-planned schedule, makes it ideal for the follow-up of transients, including novae. It was able to observe the nova throughout its eruption, starting to collect very useful X-ray and UV data within a day of the outburst first being reported. The X-ray data were essential in showing that the mass of the white dwarf is close to the theoretical maximum; continued accretion might cause it eventually to be totally destroyed in a supernova explosion."

Dr Kuin added:"The present observations provide the kind of coverage in time and spectral colour that is needed to make progress for gaining understanding of a nova in a neighbouring galaxy. Observing the nova in different wavelengths using world-class telescopes such as Swift and the Southern African Large Telescope help us reveal the condition of matter in nova ejecta as if it were nearby."

Professor Julian Osborne, who leads the Swift team at the University of Leicester, and was also involved in this study, said: "Although it is difficult to measure the distance to novae directly, its position in the SMC on the sky, and everything else we know about this nova point to it being in this dwarf galaxy. This makes the nova as intrinsically bright as the most luminous ever seen, and thus very interesting in trying to understand these explosions."

Read more at Science Daily

‘Don’t Risk It’: Viral Social Media Post Warns Against Eyeball Tattooing

Video still showing physicians removing tattoo ink from a patient's eye following a botched sclera staining procedure

In a series of videos and images, Canadian Catt Gallinger has issued what amounts to a DIY, public service message on the danger of eyeball tattoos.

For anyone freaked out by those words separately, never mind together, the images that Gallinger has posted to her Facebook page could be rather traumatic.

But, hey, knock yourself out.

Gallinger said she agreed to an impromptu tattoo session that included sclera staining, a process in which a tattoo needle is used to inject ink into the white part of a person’s eye. Gallinger chose her favorite color — purple.

In one Facebook post, Gallinger described her experience and included images that show her left eye swollen shut. In one rather startling shot, a lavender tear is seen rolling down her cheek.

“I don't want this to happen to anyone else,” Gallinger wrote.

Gallinger said the tattoo artist that performed the sclera staining — her ex-boyfriend — bungled the procedure by using too large of a needle and injecting pure ink into the eye, rather than ink diluted with saline.

The artist, who Gallinger was dating at the time, defended his work, saying she didn't maintain proper aftercare.

"I wholeheartedly believe it wasn't my fault," Brown said last week in an email to CBC. "I told her she needed to get more eye drops that day… She was fine, but neglected to get eye drops."

After multiple trips to the hospital, Gallinger says she remains in severe pain, suffers from blurred vision, and may require surgery to prevent losing vision entirely in her eye.

Sclera staining involves injecting ink just under the conjunctiva, the mucus membrane that covers the front of the eye and lines the inside of the eyelids. Properly done, the ink solution will coat the outer, white part of the eye — the sclera — in the desired color and tint.

The dangers, and there are several, exist whether the inking is done properly or not, according to the American Academy of Ophthalmology. The most common problem occurs when the ink penetrates through the conjunctiva and sclera and into the vitreous humor, the gelatinous tissue that fills the eyeball behind the lens.

The academy warns the procedure can cause decreased vision, infection, increased sensitivity to light, and possibly blindness.

Eyeball tattoos have been an increasing problem for doctors since the mid-2000s, according to AAO. Sclera staining has become popular among adherents of extreme body modification — think scaring, subdermal implants, and tongue splitting.

“Eyeball tattoos have serious risks and have not been medically or scientifically studied,” reads the AAO warning. “Because they are not a traditional part of tattooing, artists who are doing eyeball tattoos may not be properly trained.”

Read more at Seeker

The Nocebo Effect Shows Pain Isn’t All in Your Brain

Everybody’s heard of the placebo effect — the phenomenon in which people report positive health impacts of drugs that are, in fact, nothing more than sugar pills. But there’s also an opposite reaction called the nocebo effect, when patients report negative side effects — dizziness, headaches, nausea — from drugs that aren’t really drugs.

Both the placebo and nocebo effect are known to wreak havoc on drug trials. In fact, it’s become nearly impossible to win approval for new pain meds because the placebo effect is so strong, making the real medication seem weak in comparison. And research shows that when you list a bunch of potential negative side effects to participants in a drug trial, participants will report back those very symptoms whether they get the real drug or a placebo.

Until recently, the placebo and nocebo effects were thought to be entirely psychological, our brain tricking itself into believing that we feel good or bad. But advances in real-time functional MRI technology have revealed a two-way signaling pathway between pain receptors along the spine and higher-order processing areas in the brain. It turns out that the brain feels pain because the body says, “Ouch!”

A team of German researchers developed a new fMRI protocol that allowed them to measure real-time nervous system activity in both the spinal cord and the brain. The idea was to trigger a nocebo response and pinpoint exactly where it was coming from — the body, the brain, or both.

In a paper published in the journal Science, lead investigator Alexandra Tinnermann of the University Medical Center Hamburg-Eppendorf in Hamburg, Germany, described her team’s experiment involving two types of anti-rash creams. Nearly 50 participants were divided into two groups. One was treated with a supposedly cheap rash cream from a generic-labeled box. The other was treated with what they were told was an expensive, brand-name cream. In truth, both creams were identical and neither contained any active ingredients.

Both groups were told that their anti-rash cream — both cheap and expensive — had one potential side effect, that it might increase their sensitivity to pain. To determine the strength of the side effect, participants were told, the researchers were going to treat half their arm with a control cream and the other half with a target drug, either the expensive or cheap version of the cream. Heat pads were then applied to each half of the arm to compare pain levels.

In reality, though, all the creams were identical. 

When asked to rate their pain, both groups exhibited a nocebo response, citing increased pain sensitivity in the region treated with the target cream as opposed to the control. But interestingly, the people who received the “expensive” treatment exhibited a much stronger nocebo response, rating their pain as twice as bad compared to the “cheap” group.

In their paper, Tinnermann and her colleagues equate the participants’ nocebo response to earlier findings from placebo studies, theorizing that “participants infer that expensive medication contains a more potent and effective agent and, consequently, produces more side effects.”

But the more interesting question is where the nocebo effect originates. Clearly there’s some higher-order brain activity required to look at a package and determine if a cream is “cheap” or “expensive.” But does that mean that the pain is all in the patient’s head?

Luana Colloca, a professor, researcher, and physician in the department of anesthesiology at the University of Maryland School of Medicine, has been studying the nocebo effect for a decade and wrote an accompanying commentary in the same issue of Science. Colloca has run trials where participants were told that pain medication was stopped, when it fact it was continued, and people immediately reported higher levels of pain. She’s also seen the opposite, where pain meds were covertly turned off and participants reported no increased pain.

Despite the clear psychological component of the placebo and nocebo effect, Colloca says studies like the anti-rash experiment point to something more complicated at play. First off, we know that pain requires more than the brain.

“The reason we can say this stimulus is painful, it’s hurting me, is because there’s a signal from our arm reaching the spinal cord, and then from the spinal cord to the brain,” Colloca told Seeker.

And that’s exactly what the fMRI scans found in the rash-cream experiment. When participants thought they were being treated with an expensive cream, the nerve endings in the peripheral nervous system (as opposed to the central nervous system) sent more pain signals to the spinal cord, which were then transmitted to the brain.

“This is revolutionary,” said Colloca. “For the first time, we switch from a concept and phenomenon that we believed was merely psychological to something more — a neurobiological phenomenon. You believe that you’re going to experience more pain and your spinal cord lets in more information from the periphery signaling an increase of pain.”

Read more at Seeker

Mass extinctions led to low species diversity, dinosaur rule

Earth

Two of Earth's five mass extinction events -- times when more than half of the world's species died -- resulted in the survival of a low number of so-called "weedy" species that spread their sameness across the world as Earth recovered from these dramatic upheavals. The findings could shed light on modern high extinction rates and how biological communities may change in the future.

David J. Button, an NC State and North Carolina Museum of Natural Sciences postdoctoral research scholar, and colleagues examined fossil records of almost 900 vertebrate species dating back between 260 and 175 million years ago -- from the late Permian through the Triassic and early Jurassic periods. Two mass extinction events occurred during this time. Button says that similar patterns arising after two mass extinctions implies that other extinction events may have the same results -- including current biodiversity loss.

"Mass extinctions not only reduced animal diversity, but also affected the distribution of animals and ecosystems, or biogeography," Button said. "As species are removed by extinction, their ecological niches are left vacant. Following the extinction event, these niches are occupied by surviving and newly evolving 'weedy' species. These few generalists spread out and dominated for a time, leading to a low-diversity global 'disaster fauna.'"

One of these generalists was the Lystrosaurus, a plant-eating early mammal relative that ranged from dog- to pig-sized. It had tusks to help it dig up plant matter.

The late-Permian event -- occurring around 252 million years ago -- allowed new groups to evolve, including the earliest dinosaurs, crocodiles and relatives of mammals and lizards, Button said. The late-Triassic event, which occurred around 201 million years ago, wiped out many major groups, setting the stage for dinosaurs to take over.

"The late-Permian event caused about 90 percent of sea life and 70 percent of land-living vertebrates to become extinct, probably as a result of climate change from hyperactive volcanism -- when volcanoes spewed basalt lava and released gases into the atmosphere causing large increases in carbon dioxide and severe warming resulting in desertification," Button said. "The late-Triassic event is also associated with volcanism."

"Mass extinctions were global disasters that fundamentally reshaped ecosystems," said Richard Butler, professor of palaeobiology at the University of Birmingham and a co-author of the study. "Our new analyses provide crucial data that show just how profoundly these cataclysmic events changed and influenced animal distribution."

"The fossil record has the potential to test evolutionary hypotheses in long time spans, which is not possible if evolutionary research is limited to living plant and animals," said Martín Ezcurra, a researcher at the Museo Argentino de Ciencias Naturales who co-authored the paper.

Identifying patterns across mass extinction events in the fossil record can help researchers make predictions about the consequences of current biodiversity loss, Button said.

"Further understanding of these ancient crises will help to inform conservation efforts to prevent modern animals from suffering a similar fate," he added.

Read more at Science Daily

Microexplosions on the Sun's Surface Are Superheating the Solar Corona

One of the biggest mysteries about our sun is why the corona — as the upper part of the solar atmosphere is known — can be thousands of times hotter than the surface of the sun itself. It’s as though the air around a scorching, burning fireplace is hotter than the flames. While activity such as solar flares and coronal mass ejections can inject large amounts of energy into the corona, these events are too infrequent to maintain the consistently high temperatures found there.

For decades, scientists have been studying the mechanisms of coronal heat generation and transfer in an attempt to understand this phenomenon. While several ideas have been proposed, the leading theory for the last few years has focused on what solar physicists call “nanoflares.” These are tiny explosions on the sun's surface that occur almost non-stop.

Nanoflares are a billion times less energetic than ordinary  flares,  and are so small that they can’t be observed with current telescopes or spacecraft. Scientists have also theorized that they take place on regions of the sun that have no other type of eruptive activity.

While the sun emits light in many wavelengths, researchers have proposed that the spectrum of light emitted from nanoflares would be in the high energy X-rays, known as hard X-rays.

“Hard X-rays are a signature of particles accelerating on the sun,” said Steven Christe, a scientist at NASA's Goddard Space Flight Center, in a statement about the Focusing Optics X-ray Solar Imager, or FOXSI, a small instrument launched on a sounding rocket. “The sun accelerates particles when it releases magnetic energy. The biggest events like solar flares release giant bursts of energy and send particles flying, sometimes directed towards the Earth. But the sun is actually releasing energy all the time and that process is not well-understood.”

No currently operating spacecraft has the specialized X-ray optics needed to make observations of hard X-rays. But in December 2014, the FOXSI mission launched aboard a NASA Black Brant IX suborbital sounding rocket from the White Sands Missile Range in New Mexico. It made a 15-minute flight, gathering six minutes of data with very sensitive hard X-ray optics to observe the sun.

The payload flew to an altitude of 210 miles (337 km) before descending by parachute to Earth, where it was recovered.

FOXSI made the detection of very hot solar plasma above a region of the sun that was exhibiting no other eruptive activity, suggesting the presence of nanoflares.

“Usually, we observe a solar flare as a brightening, intensity increase,” Shin- nosuke  Ishikawa, from the Institute of Space and Astronautical Science at the Japan Aerospace Exploration Agency (JAXA), said in an email to Seeker. Ishikawa is the lead author of a study of the FOXSI observations, published this week in Nature Astronomy.

“In our study, we found a super-hot plasma, an evidence of nanoflares, without any detection of  other brightening ,” he said. “It's surprising that there are nanoflares from a region we couldn't see any flaring activity by the other instruments.”

Ishikawa, Christe, and their colleagues identified the very energetic X-rays, a signature of plasma heated at more than 10 million degrees Kelvin, and concluded that such heated plasma could be generated only by the action of nanoflares.

“This observation provides the most direct evidence to date for the presence of hot plasma in a quiescent solar active region,” the team wrote in their paper.

They corroborated FOXSI data with data from other spacecraft, such as one of the GOES satellites and the X-ray telescope onboard Japan’s Hinode satellite, to verify that no brightening was detected in other wavelengths. They also checked data from NASA’s Solar Dynamics Observatory taken at the same time to look at other basic features of the region.

Viewing the faint nanoflares requires extra-sensitive optics. Observing high energy X-rays streaming from the sun is extremely difficult because these wavelengths cannot be focused with conventional lenses, as visible light can. When X-rays encounter most materials — including a standard glass lens — they usually pass right through or are absorbed. Therefore, regular lenses can't be used to adjust the X-ray's path and focus the incoming light.

FOXSI carried grazing-incidence optics, which haven't been used on any previous solar-observing instruments. This employs mirrors that can successfully cause X-rays to reflect, as long as the mirrors are nearly parallel to the incoming X-rays.

Several of these mirrors in combination help collect the X-ray light before funneling it to the detector. This focusing makes faint events appear brighter and  crisper,  and allowed for the detection of the super-heated X-ray plasma.

Dean Pesnell, the project scientist for the Solar Dynamics Observatory, who wasn't involved with the FOXSI study, once compared the tiny nanoflares that happen almost constantly near the surface of the sun to heating elements in an electric blanket.

“Think of heating elements that run through an electric blanket,” he said. “Just as one small element can’t heat the entire blanket, individual nanoflares can’t heat the entire corona. But together, the tiny but consistent flares send enough energy to heat up the entire blanket of the solar atmosphere.”

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The Mystery of the Universe's Missing ‘Normal’ Matter Has Begun to Unravel

Astronomers and cosmologists have an inventory problem: They haven’t been able to account for a fair amount of the stuff that makes up our universe.

There are the longstanding challenges with pinpointing dark energy and dark matter, two invisible components that together make up more than 95 percent of the cosmos. But there is also the lesser-known problem of missing baryon particles.

Baryons are subatomic particles that include protons and neutrons, which form the nuclei of atoms. Baryonic matter — part of what we consider “normal matter” in the universe — makes up everything we are familiar with: stars, planets, the chair you are sitting on, the device you are using to read this, and you.

So there was understandable excitement this week when it emerged that two separate teams of researchers may have found this “missing” baryonic matter.

When astronomers observe the universe, they find just 10 percent of normal baryonic matter as easily observable matter in stars and nebulae, and another 40 percent has been found in diffuse clouds within galaxies.

It has been theorized that the remaining regular matter must exist as a diffuse gas between galaxies. And now the two new research papers indicate that baryonic matter does indeed exist in the form of filaments of gas between galaxies, making up the missing percentage.

Hideki Tanimura is from the Institute of Space Astrophysics in Orsay, France, and led one of the teams.

“The half of baryons (missing baryons) are considered to exist in filamentary structures between dark matter halos as a diffuse gas, WHIM ( warm hot  intergalactic medium),” he told Seeker in an email. “We show that most of our detection is due to unbound diffuse gas in filaments between dark matter halos, not bound gas in dark matter halos.”

Tanimura's team and another team led by Anna de Graaff at the University of Edinburgh in Scotland looked at data from the Planck satellite for a thermal signal called the Sunyaev-Zel'dovich effect. This effect allows for the detection of very faint  objects,  and looks for photons from the Cosmic Microwave Background as it travels through hot gas.

The interaction, which only the Planck satellite so far has been able to detect, allows astronomers to spot the presence of matter, even if it is very faint at high redshifts.

In 2015, Planck data was used to create a map of this effect throughout the observable universe. But because the filaments of gas between galaxies are so diffuse, it is very difficult to detect them directly on Planck’s map without using points of reference.

Both of the teams of researchers used data from the Sloan Digital Sky Survey to look at galaxies that were predicted to be connected by filaments of faint gas. They stacked the Planck data to look in the areas between the galaxies.

Tanimura’s group stacked data on 260,000 pairs of galaxies, and de Graaff’s team used over a million pairs. Both teams found conclusive evidence of the baryonic gas filaments between the galaxies.

Tanimura said the results between the two groups are consistent within margins.

“The biggest surprise is that the gas we detected is very low-dense, lower than expected,” Tanimura said. “It is very surprising and very important because we prove that we can detect it now! It means that we can now start to make an entire map of the universe, including filaments as well as galaxies.”

Tanimura said that the total amount of baryons has been measured by other observations such as the CMB observations and Lyman Alpha observations, and their results are consistent within margins with cosmological simulations.

“There is already a consensus about it and we prove that it is true,” he said. “But we know more than that. We estimate the distribution and physical states of the (missing) baryons. By comparing the result (which was unknown) with current models such as cosmological simulations, we can make [a] more precise picture of the current universe and constrain the evolution of the universe.”

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