May 28, 2017
Now, there is a way to control the outcome, thanks to an international research group led by scientists at the National Institute of Standards and Technology (NIST). The team has developed the first switch that turns on and off this mysterious quantum behavior. The discovery promises to provide new insight into the fundamentals of quantum theory and may lead to new quantum electronic devices.
To study this quantum property, NIST physicist and fellow Joseph A. Stroscio and his colleagues studied electrons corralled in special orbits within a nanometer-sized region of graphene -- an ultrastrong, single layer of tightly packed carbon atoms. The corralled electrons orbit the center of the graphene sample just as electrons orbit the center of an atom. The orbiting electrons ordinarily retain the same exact physical properties after traveling a complete circuit in the graphene. But when an applied magnetic field reaches a critical value, it acts as a switch, altering the shape of the orbits and causing the electrons to possess different physical properties after completing a full circuit.
The researchers report their findings in the May 26, 2017, issue of Science.
The newly developed quantum switch relies on a geometric property called the Berry phase, named after English physicist Sir Michael Berry who developed the theory of this quantum phenomenon in 1983. The Berry phase is associated with the wave function of a particle, which in quantum theory describes a particle's physical state. The wave function -- think of an ocean wave -- has both an amplitude (the height of the wave) and a phase -- the location of a peak or trough relative to the start of the wave cycle.
When an electron makes a complete circuit around a closed loop so that it returns to its initial location, the phase of its wave function may shift instead of returning to its original value. This phase shift, the Berry phase, is a kind of memory of a quantum system's travel and does not depend on time, only on the geometry of the system -- the shape of the path. Moreover, the shift has observable consequences in a wide range of quantum systems.
Although the Berry phase is a purely quantum phenomenon, it has an analog in non-quantum systems. Consider the motion of a Foucault pendulum, which was used to demonstrate Earth's rotation in the 19th century. The suspended pendulum simply swings back and forth in the same vertical plane, but appears to slowly rotate during each swing -- a kind of phase shift -- due to the rotation of Earth beneath it.
Since the mid-1980s, experiments have shown that several types of quantum systems have a Berry phase associated with them. But until the current study, no one had constructed a switch that could turn the Berry phase on and off at will. The switch developed by the team, controlled by a tiny change in an applied magnetic field, gives electrons a sudden and large increase in energy.
Several members of the current research team -- based at the Massachusetts Institute of Technology and Harvard University -- developed the theory for the Berry phase switch.
To study the Berry phase and create the switch, NIST team member Fereshte Ghahari built a high-quality graphene device to study the energy levels and the Berry phase of electrons corralled within the graphene.
First, the team confined the electrons to occupy certain orbits and energy levels. To keep the electrons penned in, team member Daniel Walkup created a quantum version of an electric fence by using ionized impurities in the insulating layer beneath the graphene. This enabled a scanning tunneling microscope at NIST's nanotechnology user facility, the Center for Nanoscale Science and Technology, to probe the quantum energy levels and Berry phase of the confined electrons.
The team then applied a weak magnetic field directed into the graphene sheet. For electrons moving in the clockwise direction, the magnetic field created tighter, more compact orbits. But for electrons moving in counterclockwise orbits, the magnetic field had the opposite effect, pulling the electrons into wider orbits. At a critical magnetic field strength, the field acted as a Berry phase switch. It twisted the counterclockwise orbits of the electrons, causing the charged particles to execute clockwise pirouettes near the boundary of the electric fence.
Ordinarily, these pirouettes would have little consequence. However, says team member Christopher Gutiérrez, "the electrons in graphene possess a special Berry phase, which switches on when these magneticallyinduced pirouettes are triggered."
Read more at Science Daily
|Pictured is the Blade in situ, viewed from below.|
A new study published today reveals the science behind another 'trick of the light' that made high-profile photographs of a major piece of public art appear 'faked' to some people despite the pictures being entirely genuine.
Vision science researchers from the University of Lincoln examined photographs of the art installation, Blade, which took pride of place in the centre of Hull earlier this year. Their interest was triggered when some pictures published online of the work -- a 75-metre long, 25-tonne wind turbine blade -- made the object appear to be super-imposed.
The researchers found that this visual illusion was caused by the particular way light reflected from the blade, which then played on pre-conceived notions people have of how objects are lit in natural settings, effectively altering the object's shape to the human eye.
Daylight hitting the object from above produced shading which created the illusion that the blade was cylindrical, and was being lit from the side rather than above. This subtly reinforced the visual impression that the blade was out-of-place, and that the image of the blade and its backdrop must therefore be a composite of two different scenes.
To demonstrate this, researchers created virtual versions of a cylindrical C-shaped profile and a more complex S-shaped profile, and produced two images of each shape, one lit from above and the other lit from the front. The images demonstrated that the S-shape when lit from above and the C-shape when lit from the front both appeared cylindrical.
Professor of Vision Science, George Mather, from the University of Lincoln's School of Psychology, said: "I saw pictures of the installation in the media, and at first sight the photographs seemed to be clumsy fakes. Something else seemed to be at work too, at least to my eyes as a vision scientist.
"The blade appeared to be a cylindrical object, strangely out-of-keeping with the local environment, lit differently, as though it was superimposed on the scene digitally, but it really was there.
"We had an idea about what it was that conveyed this impression -- light and shadow on the blade which is apparently inconsistent with the surroundings. The computer generated images were a way of testing the idea."
The blade was made by turbine manufacturer Siemens and placed in Victoria Square as a major public art installation to mark the start of Hull's year as the UK City of Culture 2017. Artist Nayan Kulkarni created the installation for Look Up, a programme of temporary artworks designed for Hull's public spaces and places. It used one of the first B75 rotor blades manufactured in Hull.
Read more at Science Daily
May 27, 2017
|A micro-CT scan shows the differences in bone structure between a surface fish and a blind cavefish.|
Cavefish start their lives with symmetrical features like other fish. But when they mature, their fragmented cranial bones harden in a visibly skewed direction, the study found.
UC's researchers speculate that this adaptation helps the typically left-leaning cavefish navigate by using sensory organs called neuromasts to follow the contours of the cave as they swim in a perpetual counterclockwise pattern. This behavior was observed among captive cavefish, which keep moving around the edges of their tanks while surface fish tend to stay motionless in the shadows of their tank or swim in haphazard ways.
"That was a real big piece of the puzzle for us," said Joshua Gross, a UC biology professor and co-author. "It's a mystery how they've been able to adapt. The amazing thing is that they're not just barely surviving -- they thrive in total darkness."
Gross has been studying cavefish for years at UC. They make an excellent model to examine regressive evolution, the process by which animals lose features over generations, he said.
"The traits they've lost are very conspicuous -- their eyes, their pigmentation," Gross said. "The beauty of studying cave animals is it's a very robust model for understanding why features are lost, and it's a simple, stable set of environmental pressures that cause those features to go away."
Cave-dwelling animals as diverse as salamanders and crayfish have responded similarly by losing pigment and eyesight while gaining or augmenting other sensory structures.
"The fact that they're all moving in the same evolutionary direction is not a coincidence. They're all living in total darkness with a limited food supply," he said.
Cavefish are especially valuable for evolutionary study, Gross said, because of their genetic relationship with readily abundant surface fish. Many antecedents of other cave-dwelling animals have been lost to extinction from natural selection or calamity.
The UC biology lab has dozens of aquariums and breeding tanks full of cave and surface fish, each smaller than a goldfish. Researchers use QR-code stickers to keep track of the family history of the resident fish swimming in slow circles.
The hardy fish are easy to keep because they are not picky eaters. They get a mix of foods including flakes, brine shrimp and blackworms. UC gets its study fish from natural populations maintained by colleagues and reputable breeders.
"Our lab really tries to avoid taking any animals from nature," Gross said.
Mexican cavefish also are raised as a popular aquarium pet.
The skulls of all but a couple cavefish UC studied bend to the left. They seem to be right-finned, swimming in a lazy counterclockwise pattern around their aquariums in the biology lab.
"You could see how asymmetry might be an advantage in navigation," Powers said.
"They tend to swim in a unidirectional, circular motion around their tanks to explore their surroundings," she said. "Having asymmetry in their skull we think is attributed to handedness. If their skull is bent to the left, they could be 'right-handed.' They're feeling the wall to the right with their sensory structures."
This kind of asymmetry is uncommon in nature. Think of the fiddler crab with its outsized claw. Owls have asymmetrical ears -- one canal placed higher on the skull than the other -- perhaps to help the night predators target the faint rustling of a mouse in the dark.
In the biology lab, researchers breed surface fish with cavefish and study the resulting hybrids, co-author and recent UC graduate Shane Kaplan said. He and UC student Erin Davis also contributed to the study.
The interesting genetic combinations occur in the second generation or F2 population of hybridization, he said.
"You can capture the genetic diversity of the entire population," Kaplan said. "Some fish look exactly like surface fish. Others look exactly like cavefish. Then you'll have intermittent phenotypes. Some are pale but have eyes while others will have no eyes but are fully pigmented."
The study was funded by grants from the National Institutes of Health and the National Science Foundation.
Powers traveled with Gross to Mexico in 2013, in 2015 and again this year to study wild cavefish. They wore dust masks to guard against fungal spores associated with the respiratory disease histoplasmosis, which can be found in bat guano. Getting to the fish pools required a little spelunking.
"The group ahead of us disturbed some bats. As we were coming in, bats were going out," she said. "They have incredible echo-location. The bats knew where you were and would fly around you in the darkness, even though it was a very small chamber."
The cave had several distinct pools, each farther from the entrance. The deeper they went, the fewer surface-dwelling fish they found until they found only blind cavefish.
"Whenever you would touch the surface of the water with your finger, a swarm of cavefish would come right up to it," Powers said. "Not many fish would do that. These cavefish have zero predators so they're not afraid. That was a really cool experience."
Kaplan said it would be worthwhile to explore the cavefish's DNA to find out what prompts the asymmetry in adult cavefish.
"We haven't yet delved into why it's happening. I'd love to get more into the genetics and developmental processes that lead to these bizarre phenotypes," Kaplan said.
Read more at Science Daily
"We wanted to find out whether the idea that monkeys don't do any learning during their vocal development is actually true," says the study's senior co-author Asif Ghazanfar, a professor of psychology and the Princeton Neuroscience Institute. "So we picked a species that we know really relies on vocalizations as its primary social signals. What we found in marmoset vocal development very closely parallels pre-linguistic vocal development in humans."
Although marmoset vocal calls do not approach the complexity of human language systems, vocal development in both species begins with infants making more or less random sounds.
"When an infant blurts out something and the parent responds, that's a contingent response. And the more often a parent provides that contingent response, the faster the human infant will develop its vocalizations," Ghazanfar says.
To find out whether the same principle held true for marmosets, Ghazanfar and his colleagues set up an experiment using pairs of fraternal twin marmosets, small, highly social monkeys from South America. Starting from the day after the marmosets were born, the researchers would separate the infants from the adult marmosets for 40 minutes each day. In the first 10 minutes, they recorded the noises that the infant marmosets made while sitting alone. Then, for the next half hour, the researchers gave the young marmosets contingent feedback in the form of audio playbacks of the parent's calls.
One twin in each pair got consistent feedback, mirroring what a young marmoset would receive from an especially attentive parent; the other twin got less consistent feedback on their vocalizations. They repeated these experiments up until the infants were 2 months old, roughly the equivalent of 2 years old in marmoset years.
Even though these sessions lasted less than an hour each day, infant marmosets that received lots of contingent feedback developed adult-sounding calls more rapidly than their siblings.
"When they're infants, this call is really noisy," Ghazanfar says. "It sounds kind of coarse, and then gradually it becomes very clean and tonal like an adult call."
Previous studies had found a correlation between the amount of feedback marmosets get from parents and the rate of vocal development, but the experimental design in this study more firmly establishes the causality between parental responses and vocal development, the researchers say.
"This system of vocal learning production may be linked to the idea that an infant that more quickly produces adult-sounding calls is more likely to get care from a caregiver in a cooperative breeding environment where multiple individuals could be that caregiver in addition to the parents," Ghazanfar says. "So it's not only this process of learning that's similar to humans; the whole reproductive strategy is similar to humans."
The researchers' next steps will include collecting more detailed data on marmosets' neural activity when they are chattering or calling to neighbors, he says.
Read more at Science Daily
May 26, 2017
New DNA evidence reported in the journal Current Biology helps to provide the answer by showing that, at least in the area now known as Romania, hunter-gatherers and farmers were living side by side, intermixing with each other, and having children.
It was not necessarily love at first sight, though.
“Farmers arrived very suddenly, as a result of a fast expansion,” co-author Andrea Manica of the University of Cambridge said. “It is likely that they lived side by side with local hunter-gatherer populations for a period of time — centuries or even a millennium or two — with increasing contact and mixing among the two communities.”
Manica, lead author Gloria Gonzalez-Fortes, and their international team came to these conclusions after recovering four ancient human genomes from Romania dating to between 8.8–5.4 thousand years ago. For context, they analyzed two hunter-gatherer genomes from Spain, as well as other known early genomes from these European regions.
Co-author Clive Bonsall from the University of Edinburgh explained that indigenous hunter-gatherers can be distinguished archaeologically from immigrant farmers by their material culture, such as artifacts, architecture, burial traditions, art, and body ornamentation. The two groups also differ in subsistence practices, determined by food refuse preserved in the archaeological record and chemical analysis of human remains.
“For example, in our study region, hunter-gatherers did not cultivate or raise livestock, although they did keep domestic dogs," Bonsall said. "They did not use pottery, and buried their dead in a different way.”
The DNA analysis revealed that the early Romanian genomes had significant input from Western hunter-gatherers, but still showed a sizable contribution from Anatolian farmers. This suggests that some hunter-gatherers and farmers were mating and raising children.
The scientists suspect that the challenging climate of the region might have caused the farmers to supplement their diet with food from hunter-gatherer activities, helping to bring the two distinct groups of people together.
They additionally consumed some dairy products, even though all of the individuals examined in the study were lactose intolerant. Co-author Eppie Jones of the University of Cambridge explained that “the mutation, which allowed people to drink milk into adulthood, has not been found in Europe before the Bronze Age (starting around 2300 B.C.).”
The hunter-gatherers, on the other hand, brought plenty of nuts, plant foods, fish, and shellfish to the table. Some hunter-gatherers along the lower Danube River were so good at fishing that they lived in more permanent settlements, known as fishing villages.
Previously it was thought that farmers horned in on the hunter-gatherer territory and outcompeted the native populations, but the DNA evidence indicates that, at least in some cases, the two groups managed to live together despite large cultural differences.
Jones mentioned that the new findings, combined with prior research, reveal that “the amount of mixing between the groups varies in different regions of Europe. In Central and Western Europe, the incoming farmers largely replaced the local populations, while in areas further north, such as the Baltic, farmers didn’t make much of a genetic impact.”
Read more at Discovery News
The ice arch across the Nares Strait, which separates Greenland from Ellesmere Island in Canada’s far northeast, gave way two months earlier than usual, said Laurence Dyke, a paleoglaciologist at the Geological Survey of Denmark and Greenland.
“On May 10, this arch disintegrated, leaving the oldest and thickest sea ice in the Arctic vulnerable to being swept south where it will melt away,” Dyke told Seeker. “Over the last two weeks, the area of broken ice has expanded massively to the north, and lots of Arctic sea ice is flowing southwards through the Nares Strait.”
The channel and the Lincoln Sea, at the northern tip of Greenland, are normally covered by a sheet of ice several meters thick until around July, Dyke said. Usually, ice sheets that cover the strait are anchored to land and don’t move, blocking the passage of sea ice through the strait.
But as heat-trapping fossil-fuel emissions like carbon dioxide build up in the atmosphere, the Arctic is warming twice as fast as the rest of the globe. And this year, land-anchored ice in the strait failed to form amid the record warmth and record low sea ice coverage recorded across the Arctic. That left only an arch of ice at the northern end of the strait, where it joined the Lincoln Sea — the structure that gave way earlier this month.
“This is especially important as the Lincoln Sea contains the last bastion of old, thick multi-year sea ice,” Dyke said.
The Nares Strait is the smaller of two passages that can funnel ice from that area toward the Atlantic.
The Fram Strait, on the east side of Greenland, carries “significantly more,” said Twila Moon, a glaciologist at the National Snow and Ice Data Center in Colorado — “But every little bit counts.”
And the loss of multi-year ice is already a chronic problem in the Arctic. It forms the heart of next year’s sea ice and provides habitat for whales, seals, and birds.
“It’s also playing a role to reduce the amount of heat the ocean can take in during the summer,” Moon said. If less ice is floating on the surface of the Arctic ocean, the dark-colored sea will absorb more of the Sun’s energy — “and of course, more heat in the ocean reduces our sea ice further, and we get a runaway effect.”
“Each of these small events adds up, and they’re not good news,” she added.
This year’s event isn’t unprecedented: Something similar happened in 2007. But when that occurred, “that led to the largest flux of Arctic Sea ice through Nares Strait in at least the last 15 years,” Dyke said.
“Multi-year ice has been steadily declining over the last two decades, and this early break-up will surely destroy another large portion of it,” he said.
Since sea ice is floating in water already, its melting doesn’t add to sea-level rise — which a recent study suggests has accelerated dramatically since the 1990s. But the warming of the surrounding oceans is already starting to eat away at the miles of ice that cover Greenland.
Dykes was part of a 2015 expedition to study the Greenland’s massive Petermann Glacier, which overlooks the Nares Strait, and said that the loss of sea ice is starting to affect that structure.
Read more at Discovery News
To better understand this mindset, an international team of experts in psychology and cognitive neuroscience recently studied 66 convicted male terrorists, with an average of 33 victims per subject. Some of the men participated in massacres with death tolls exceeding 600.
The men were all Colombian right-wing paramilitaries who were imprisoned for committing terrorist acts before being freed last year. The researchers put them through a battery of cognitive and psychological tests, the results of which are published in the journal Nature Human Behavior.
Co-author Adolfo García of Favaloro University in Argentina explained that Colombia has one of the world’s highest levels of terrorism.
“Since the late 1990s, roughly 70,000 people in this country have been killed by terrorists, and thousands more have been kidnapped, tortured, or otherwise violated,” he said.
García, lead author Sandra Baez, and their colleagues assessed the moral cognition, IQ, aggressive behavior, and emotion recognition of the 66 convicted terrorists, as well as basic executive skills such as planning, memory, attention, and multitasking. The tests that the researchers administered were given to a control group of 66 people with social and demographic backgrounds that were similar to those of the convicted terrorists, but who never committed any crimes.
The results showed no significant differences in intelligence, verbal skills, or basic cognitive functions between the two study groups. The convicted terrorists did exhibit higher levels of aggression and lower levels of emotion recognition than non-terrorists.
The most striking difference, however, concerned moral judgment. The test results show that the terrorists failed to integrate intentions and outcomes in the way that the control group members did. The terrorist moral code instead prioritizes ends over means.
Grace and her friend are taking a tour of a chemical plant. When
Grace goes over to the coffee machine to pour some coffee, Grace’s
friend asks for some sugar in hers. There is white powder in a container
by the coffee. The white powder is a very toxic one left behind by a
scientist, and therefore deadly when ingested in any form. The container
is labelled ‘sugar,’ so Grace believes that the white powder by the coffee
is sugar left out by the kitchen staff. Grace puts the substance in her
friend’s coffee. Her friend drinks the coffee and dies.
The researchers then varied this scenario, changing the intentions and outcomes. For example, in one version of the fictional tale, Grace knows that the white powder is toxic, yet she still gives it to her friend.
Time and again, the terrorists judged intentional harm as more permissible and morally just than accidental harm. Terrorist logic holds that the ends, no matter how horrific, justify the means. The test results as a whole, therefore, provide evidence that distorted moral cognition is a hallmark of the terrorist mindset.
“Terrorists’ outcome-based moral judgments may reflect the conviction that any action is justifiable as long as it favors the accomplishment of an aim,” senior author Agustín Ibáñez of Favaloro University explained. “Sociological studies emphasize such a deviant moral tendency as a prominent trait in terrorists. If the actions of terrorists follow from their underlying moral cognition, that means they will prioritize the results of the outcomes over conventional moral values.”
He noted that terrorists “consider it morally appropriate to do whatever it takes in the pursuit of an aim, even when this aim contradicts normative values.”
The study supports the theory that terrorists suppress instinctive and learned moral constraints — such as empathy, fairness, and pro-sociality — against harming innocent others. This can happen even in individuals with well-above-average IQs.
Intriguingly, there is little evidence that all terrorists are psychopaths. Not all psychopaths are involved in criminal behaviors, for example, and no conclusive evidence links such traits with terrorism.
“Terrorism and radicalism are multi-factorial phenomena molded by group dynamics, biological predispositions, cultural constraints, and socio-psychological factors,” Ibáñez said. “It may even be the case that this abnormal form of moral cognition is the result of participating in terrorist practices.”
A controversial resolution released by an American Psychological Association task force a few years ago suggests that such participation might include playing violent video games, which have been linked to increases in aggressive behavior in some individuals and decreases in empathy and sensitivity to aggression. Adam Lanza, the shooter responsible for the Sandy Hook Elementary School massacre in 2012, frequently played both violent and non-violent video games.
“The influence of civil society institutions that help create social bonds, from churches to labor unions, has eroded. So has that of the progressive movements that used to give social grievance a political form,” wrote Kenan Malik, a former research psychologist who studied neurobiology. “Cracks now exist in which are spawned angry individuals, inhabiting a space beyond normal moral boundaries. There, they may find in Islamism or white nationalism the salve for their demons and a warped vindication for their actions.”
The situation in Colombia is particularly challenging because involvement in guerrilla or paramilitary warfare is often forced. Participants frequently come from extreme poverty and have little formal education. Many of the 66 convicted terrorists who participated in the study had experienced or witnessed sexual and childhood abuses.
While certain aspects of the problems in Colombia are unique, such as its political dynamics and the impact of illegal drug trafficking, terrorist acts in that country share similarities in many ways to those of other countries.
“At a global level, the size, timing and other macro-features of violent events of Colombia are comparable with those of countries with similar terrorist levels,” Ibáñez said. “Collective human activities like violence have been shown to exhibit universal-like patterns.”
Because of the determination that terrorists exhibit skewed moral judgments, have high levels of aggression, and possess emotion recognition impairments, the researchers believe that these individuals should be closely monitored after their release from prison — that is, if they ever are released — especially in light of numerous reported relapses, at least among demobilized paramilitaries. Ibáñez and his colleagues do, however, believe that psychological and social-cognitive therapies may benefit such individuals.
Read more at Discovery News
But biologists will tell you that living cells process information too, and their process isn't a simple binary exchange of ones and zeros. Instead, cells deal with multiple complex structures of sugars, proteins, lipids, and DNA. As such, the act of “programming” cells, through genetic engineering, is enormously complex.
But that's okay — scientists like a good challenge.
In research from the University of Washington, published in the journal Nature Communications, synthetic biologists announced a new method for turning organic cells into living computers. By installing the organic equivalent of the digital logic gates used in electronics, scientists can code instructions into the cell so that particular inputs result in desired outputs. Instead of silicon and solder, biologists are using DNA and yeast cells to developing this new kind of organic processor.
In a series of experiments, the UW team built the largest organic “circuit board” constructed to date, including seven logic gates assembled in series or parallel.
Each gate consists of a gene with three programmable chunks of DNA. Two act as inputs, with the third as the output. Using CRISPR technology, the researchers programmed specific proteins to act as molecular gatekeepers, determining whether a particular gate will be active or not.
If a gate is active, it sends a signal that deactivates another gate within the organic circuit, which means scientists can basically “wire” together the gates to create logical programs in the cell.
The new research is a significant step forward for synthetic biology, said senior author and UW electrical engineering professor Eric Klavins.
“Digital logic has been done at a small scale, a few gates, many times over the last decade or so,” Klavins said in an email. “Our paper is the first to produce large circuits built in a eukaryote (yeast), in which transcriptional machinery is considerable more complex.”
Eurkaryotic cells, like human cells, contain a nucleus and other structures that enable complex behaviors. These are the kinds of cells we'll need to hack for doing those really useful things — like regrow a liver.
“Cells could be reprogrammed to undergo new developmental pathways, to regrow organs, or to develop entirely new ones,” Klavins said. “In such developing tissues, cells have to make complex digital decisions about what genes to express and when, and our technology could be used to control that process.”
The organic circuit board could also be used to produce viable biofuels, which requires importing genes from several different organisms into a hybrid industrial strain, Klavins said.
“Those genes express protein enzymes that each do a particular conversion of one molecule to another, along a metabolic pathway that usually starts with sugar and ends with the fuel,” he said.
Read more at Discovery News
May 25, 2017
It went out with a whimper instead of a bang.
The star, which was 25 times as massive as our sun, should have exploded in a very bright supernova. Instead, it fizzled out -- and then left behind a black hole.
"Massive fails" like this one in a nearby galaxy could explain why astronomers rarely see supernovae from the most massive stars, said Christopher Kochanek, professor of astronomy at The Ohio State University and the Ohio Eminent Scholar in Observational Cosmology.
As many as 30 percent of such stars, it seems, may quietly collapse into black holes -- no supernova required.
"The typical view is that a star can form a black hole only after it goes supernova," Kochanek explained. "If a star can fall short of a supernova and still make a black hole, that would help to explain why we don't see supernovae from the most massive stars."
He leads a team of astronomers who have been using the Large Binocular Telescope (LBT) to look for failed supernovae in other galaxies. They published their latest results in the Monthly Notices of the Royal Astronomical Society.
Among the galaxies they've been watching is NGC 6946, a galaxy 22 million light-years away that is nicknamed the "Fireworks Galaxy" because supernovae frequently happen there -- indeed, SN 2017eaw, discovered on May 14th, is shining near maximum brightness now. Starting in 2009, one particular star in the Fireworks Galaxy, named N6946-BH1, began to brighten weakly. By 2015, it appeared to have winked out of existence.
The astronomers aimed the Hubble Space Telescope at the star's location to see if it was still there but merely dimmed. They also used the Spitzer Space Telescope to search for any infrared radiation emanating from the spot. That would have been a sign that the star was still present, but perhaps just hidden behind a dust cloud.
All the tests came up negative. The star was no longer there. By a careful process of elimination, the researchers eventually concluded that the star must have become a black hole. It's too early in the project to know for sure how often stars experience massive fails, but Scott Adams, a former Ohio State student who recently earned his Ph.D. doing this work, was able to make a preliminary estimate.
"N6946-BH1 is the only likely failed supernova that we found in the first seven years of our survey. During this period, six normal supernovae have occurred within the galaxies we've been monitoring, suggesting that 10 to 30 percent of massive stars die as failed supernovae," he said.
"This is just the fraction that would explain the very problem that motivated us to start the survey."
To study co-author Krzystof Stanek, the really interesting part of the discovery is the implications it holds for the origins of very massive black holes -- the kind that the LIGO experiment detected via gravitational waves. (LIGO is the Laser Interferometer Gravitational-Wave Observatory.)
Read more at Science Daily
"What we've learned so far is earth-shattering. Or should I say, Jupiter-shattering," said Bolton, Juno's principal investigator. "Discoveries about its core, composition, magnetosphere, and poles are as stunning as the photographs the mission is generating."
The solar-powered spacecraft's eight scientific instruments are designed to study Jupiter's interior structure, atmosphere, and magnetosphere. Two instruments developed and led by SwRI are working in concert to study Jupiter's auroras, the greatest light show in the solar system. The Jovian Auroral Distributions Experiment (JADE) is a set of sensors detecting the electrons and ions associated with Jupiter's auroras. The Ultraviolet Imaging Spectrograph (UVS) examines the auroras in UV light to study Jupiter's upper atmosphere and the particles that collide with it. Scientists expected to find similarities to Earth's auroras, but Jovian auroral processes are proving puzzling.
"Although many of the observations have terrestrial analogs, it appears that different processes are at work creating the auroras," said SwRI's Dr. Phil Valek, JADE instrument lead. "With JADE we've observed plasmas upwelling from the upper atmosphere to help populate Jupiter's magnetosphere. However, the energetic particles associated with Jovian auroras are very different from those that power the most intense auroral emissions at Earth."
Also surprising, Jupiter's signature bands disappear near its poles. JunoCam images show a chaotic scene of swirling storms up to the size of Mars towering above a bluish backdrop. Since the first observations of these belts and zones many decades ago, scientists have wondered how far beneath the gas giant's swirling façade these features persist. Juno's microwave sounding instrument reveals that topical weather phenomena extend deep below the cloudtops, to pressures of 100 bars, 100 times Earth's air pressure at sea level.
"However, there's a north-south asymmetry. The depths of the bands are distributed unequally," Bolton said. "We've observed a narrow ammonia-rich plume at the equator. It resembles a deeper, wider version of the air currents that rise from Earth's equator and generate the trade winds."
Juno is mapping Jupiter's gravitational and magnetic fields to better understand the planet's interior structure and measure the mass of the core. Scientists think a dynamo -- a rotating, convecting, electrically conducting fluid in a planet's outer core -- is the mechanism for generating the planetary magnetic fields.
"Juno's gravity field measurements differ significantly from what we expected, which has implications for the distribution of heavy elements in the interior, including the existence and mass of Jupiter's core," Bolton said. The magnitude of the observed magnetic field was 7.766 Gauss, significantly stronger than expected. But the real surprise was the dramatic spatial variation in the field, which was significantly higher than expected in some locations, and markedly lower in others. "We characterized the field to estimate the depth of the dynamo region, suggesting that it may occur in a molecular hydrogen layer above the pressure-induced transition to the metallic state."
These preliminary science results were published in two papers in a special edition of Science. Bolton is lead author of "Jupiter's interior and deep atmosphere: The initial pole-to-pole passes with the Juno spacecraft." SwRI's Dr. Frederic Allegrini, Dr. Randy Gladstone, and Valek are co-authors of "Jupiter's magnetosphere and aurorae observed by the Juno spacecraft during its first polar orbits"; lead author is Dr. John Connerney of the Space Research Corporation.
Read more at Science Daily
|This is an artistic reconstruction of Luskhan itilensis.|
Spanning more than 135 Ma during the 'Age of Dinosaurs', plesiosaur marine reptiles represent one of longest-lived radiations of aquatic tetrapods and certainly the most diverse one. Plesiosaurs possess an unusual body shape not seen in other marine vertebrates with four large flippers, a stiff trunk, and a highly varying neck length. Pliosaurs are a special kind of plesiosaur that are characterized by a large, 2m long skull, enormous teeth and extremely powerful jaws, making them the top predators of oceans during the 'Age of Dinosaurs'.
In a new study to be published today in the journal Current Biology, the team reports a new, exceptionally well-preserved and highly unusual pliosaur from the Cretaceous of Russia (about 130 million years ago). It has been found in Autumn 2002 on right bank of the Volga River, close to the city of Ulyanovsk, by Gleb N. Uspensky (Ulyanovsk State University), one of the co-authors of the paper. The skull of the new species, dubbed "Luskhan itilensis," meaning the Master Spirit from the Volga river, is 1.5m in length, indicating a large animal. But its rostrum is extremely slender, resembling that of fish-eating aquatic animals such as gharials or some species of river dolphins. "This is the most striking feature, as it suggests that pliosaurs colonized a much wider range of ecological niches than previously assumed" said Valentin Fischer, lecturer at the Université de Liège (Belgium) and lead author of the study.
By analysing two new and comprehensive datasets that describe the anatomy and ecomorphology of plesiosaurs with cutting edge techniques, the team revealed that several evolutionary convergences (a biological phenomenon where distantly related species evolve and resemble one another because they occupy similar roles, for example similar feeding strategies and prey types in an ecosystem) took place during the evolution of plesiosaurs, notably after an important extinction event at the end of the Jurassic (145 million years ago). The new findings have also ramifications in the final extinction of pliosaurs, which took place several tens of million years before that of all dinosaurs (except some bird lineages). Indeed, the new results suggest that pliosaurs were able to bounce back after the latest Jurassic extinction, but then faced another extinction that would -- this time -- wipe them off the depths of ancient oceans, forever.
From Science Daily
The research, led by scientists at Tufts University's Allen Discovery Center and its Department of Biology, addresses the forces that determine the shape to which an animal's body regenerates when severely damaged, shows that it is possible to permanently alter the target morphology of an animal with a wild-type genomic sequence, and reveals that alternative body patterns can be encoded within animals with normal anatomy and histology. The research also provides clues about why certain individuals have different biological outcomes when exposed to the same treatment as others in their group.
"With this work, we now know that bioelectric properties can permanently override the default body shape called for by a genome, that regenerative target morphology can be edited to diverge from the current anatomy, and that bioelectric networks can be a control point for investigating cryptic, previously-unobservable phenotypes," said the paper's corresponding author, Michael Levin, Ph.D., Vannevar Bush professor of biology and director of the Allen Discovery Center at Tufts and the Tufts Center for Regenerative and Developmental Biology.
The findings are important because advances in regenerative medicine require an understanding of the mechanisms by which some organisms repair damage to their bodies, said Levin. "Bioelectricity has a powerful instructive role as a mediator in the reprogramming of anatomical structure, with many implications for understanding the evolution of form and the path to regenerative therapies," he added.
Researchers worked with planaria (Dugesia japonica) -- flatworms that are known for their regenerative capacity. When cut into pieces, each fragment of flatworm regenerates what it is missing to complete its anatomy. Normally, regeneration produces an exact copy of the original, standard worm.
Building on previous work in which Levin and colleagues demonstrated it was possible to cause flatworms to grow heads and brains of another species of flatworm by altering their bioelectric circuits, the researchers briefly interrupted the flatworms' bioelectric networks. They did so by using octanol (8 OH) to temporarily interrupt gap junctions, which are protein channels -- electrical synapses -- that enable cells to communicate with each other locally and by forming networks across long distances, passing electrical signals back and forth.
Twenty five percent of the amputated trunk fragments regenerated into two-headed flatworms, while 72 percent regenerated into normal-appearing, one-headed worms; approximately 3 percent of the trunk fragments did not develop properly. At first, the researchers assumed that the single-headed treated flatworms had not been affected by the treatment, as is common when the function of a biological system is altered by any experimental treatment or environmental event. However, when the flatworms with normal body shape were then amputated repeatedly over several months in normal spring water, they produced the same ratio of two-headed worms to one-headed worms.
The flatworms' pattern memory had been altered, although this was not apparent in their intact state and was revealed only upon regeneration. The research showed that the altered target morphology -- the shape to which the worms regenerate upon damage -- was encoded not in their histology, molecular marker expression, or stem cell distribution, but rather in a bioelectric pattern that instructs one of two possible anatomical outcomes after subsequent damage.
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Their findings are published by Nature.
The team's discovery could help solve a cosmic puzzle -- a mysterious population of surprisingly massive galaxies from when the universe was only about 10 percent of its current age.
After first observing these galaxies a few years ago, astronomers proposed that they must have been created from hyper-productive precursor galaxies, which is the only way so many stars could have formed so quickly. But astronomers had never seen anything that fit the bill for these precursors until now.
This newly discovered population could solve the mystery of how these extremely large galaxies came to have hundreds of billions of stars in them when they formed only 1.5 billion years after the Big Bang, requiring very rapid star formation.
The team made this discovery by accident when investigating quasars, which are supermassive black holes that sit at the center of enormous galaxies, accreting matter. They were trying to study star formation in the galaxies that host these quasars.
"But what we found, in four separate cases, were neighboring galaxies that were forming stars at a furious pace, producing a hundred solar masses' worth of new stars per year," Decarli explained.
"Very likely it is not a coincidence to find these productive galaxies close to bright quasars. Quasars are thought to form in regions of the universe where the large-scale density of matter is much higher than average. Those same conditions should also be conducive to galaxies forming new stars at a greatly increased rate," added Fabian Walter, also of Max Planck.
"Whether or not the fast-growing galaxies we discovered are indeed precursors of the massive galaxies first seen a few years back will require more work to see how common they actually are," Bañados explained.
Decarli's team already has follow-up investigations planned to explore this question.
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May 24, 2017
The still unfinished new Grand Egyptian Museum at the foot of the pyramids will eventually house the collections of the current brimming museum in the city’s Tahrir Square.
A gilded bed and a funeral chariot from Tutankhamun’s tomb — discovered by British archaeologist Howard Carter in 1922 — were transferred on Tuesday, well packed in wooden containers complete with materials to protect them from both heat and vibration.
Two trucks bearing the ancient treasures pulled up at the new Grand Egyptian Museum shortly before 1600 GMT, escorted by police vehicles.
In one of the galleries of the new complex, technicians wearing white gloves gingerly unwrapped the precious objects.
Relocating the two pieces forms part of a joint program with the Japan International Cooperation Agency (JICA) to restore, pack and transport 71 items from the existing museum to the new facility, an antiquities ministry statement said.
“During the next weeks and months we’re going to transfer regularly more than 1,000 remaining objects in Cairo museum to be restored and prepared for the exhibition here in the first half of 2018,” said Antiquities Minister Khaled al-Enany.
‘A big event’
“Today is a big event... today we start transferring big objects,” he said.
The Grand Egyptian Museum had been scheduled to open in 2015, but construction has lagged as expenses mounted to more than $1 billion.
The museum is now scheduled to open partially in 2018.
Eventually, the vast complex will house more than 100,000 relics including the 4,500 pieces of Tutankhamun’s treasure discovered in the southern Valley of the Kings in Luxor.
But the young pharaoh’s mummy will remain in his tomb as it is too fragile to transport.
He died at the age of 19 in the year 1324 BC after a nine-year reign.
This first set of Tutankhamun artefacts destined for the new museum includes three funeral beds, five chariots and 57 pieces of textiles.
Bas-reliefs of the pharaoh Snefru, founder of the 4th dynasty, are also among the 71 selected objects being moved.
The funerary bed moved on Tuesday is gilded and features posts made of carved lion heads, representing Sekhmet, the goddess of war and healing.
The huge GEM complex will extend over 47 hectares (116 acres) and contain some 24,000 square meters (258,300 square feet) of permanent exhibition space.
It will feature alabaster facades, and its eventual opening will relieve the pressure on the current national museum that was inaugurated in 1902 and has run out of space.
Construction of the massive new archaeological facility museum was announced in 2002. But its opening has been postponed several times, including because of the political instability that has rocked the country.
Read more at Discovery News
Astronomers have nailed down the path of TRAPPIST-1h, the outermost planet in the system, finding that this world takes just under 19 Earth days to complete one lap around its small, faint host star.
The new result suggests that TRAPPIST-1h is too cold to host life as we know it, and it confirms that all seven TRAPPIST-1 worlds circle their star in a sort of gravitational lockstep with one another, study team members said.
"It's incredibly exciting that we're learning more about this planetary system elsewhere, especially about planet h, which we barely had information on until now," Thomas Zurbuchen, associate administrator of NASA's Science Mission Directorate at the agency's headquarters in Washington, DC, said in a statement.
"This finding is a great example of how the scientific community is unleashing the power of complementary data from our different missions to make such fascinating discoveries," Zurbuchen added.
TRAPPIST-1 is a dim, dwarf star just 8 percent as massive as the sun that lies about 40 light-years from Earth. In May 2016, astronomers using the TRAPPIST (Transiting Planets and Planetesimals Small Telescope) instrument in Chile announced the discovery of three roughly Earth-size planets in the system. That number jumped to seven with further observation by NASA's Spitzer Space Telescope, TRAPPIST and other ground-based telescopes.
Despite such work, astronomers had not been able to pin down the path of TRAPPIST-1h. But they had noticed that the six other planets in the system are in "orbital resonance." That is, the worlds have tugged each other into stable orbits whose periods are related to each other by a ratio of two small integers.
Similarly, the Jupiter moons Io, Europa and Ganymede are in orbital resonance: For every lap Ganymede completes around Jupiter, Europa makes two orbits and Io completes four. The TRAPPIST-1 resonances are much more complex, but they adhere to the same principle.
The six planets' relationships with each other led the research team to propose six possible resonant orbits for TRAPPIST-1h. Various observations ruled out five of the six, but the sixth was confirmed with observations made by NASA's Kepler space telescope from December 2016 through March of this year, the scientists announced in the new study, which was published Monday (May 22) in the journal Nature Astronomy.
"The resonant structure is no coincidence and points to an interesting dynamical history in which the planets likely migrated inward in lockstep," lead author Rodrigo Luger, a doctoral student at the University of Washington in Seattle, said in the same statement. "This makes the system a great test bed for planet-formation and -migration theories."
Read more at Discovery News
While previous theories hold that the impact created a ring around Earth that eventually coalesced into the moon, recent research suggests that the planet temporarily turned into a large mass of vaporized rock, with outer layers of the vaporized planet rotating in orbit around the rest of the body, forming an indented donut-shaped disk.
Two planetary scientists have proposed a new classification for this theoretical object — a transitory planetary state that has never been observed in space — which they call a “synestia.” The word the prefix “syn-” (united; together) with a reference to Hestia, the Greek goddess of architecture.
“We looked at the statistics of giant impacts, and we found that they can form a completely new structure,” said Sarah Stewart, co-author of the research and professor at the University of California, Davis, in a press statement.
The research, which was led by Simon Lock, a graduate student in planetary sciences and geophysics at Harvard University, was published in the Journal of Geophysical Research: Planets. It was supported by NASA and the US Department of Energy.
Today’s theories posit that planets in our solar system were formed billions of years ago when bits of rock and gas were attracted to each other because of gravity. As these smaller objects crashed into each other, the resulting bodies melted and eventually solidified into the rocky planets we are familiar with now: Mercury, Venus, Earth, and Mars.
When considering objects that spin, however, the formation scenario shifts. Imagine a spinning skater on ice. To slow her rate of spin, she extends her arms. To increase her rate of spin, she holds her arms close. But her angular momentum, or rotational inertia, remains the same in both scenarios.
If there are two spinning skaters on the ice, their angular momentum also remains the same if they reach out and grab each other’s hands. This is a similar scenario to when a spinning, Earth-sized rocky planet collides with high energy into another spinning object, the researchers argue. And these are the conditions under which synestias may occur.
The proposed structure of a synestia suggests that after a small body collides with a spinning planet, some of the material will go into orbit. That’s because the collision would make the planet become molten, in turn causing it to expand in volume. If the planet grows big enough and has a fast enough angular momentum, it would expand into a massive disk of rotating material.
In Earth’s case, if it formed a synestia after the big collision, it likely would have lasted that way for only a hundred years or so before heat escaped and it condensed. Synestias may persist longer if they form from larger or hotter objects such as gas giant planets or moons, however.
Read more at Discovery News
Blue whales use baleen — a filter-feeder system inside the mouth — to obtain massive amounts of prey from ocean water. The oldest members of the baleen-whale lineage appeared about 36 million years ago, yet new research published in the Proceedings of the Royal Society B finds that very large members of this lineage only appear at around 2–3 million years ago, which is a drop in the evolutionary bucket.
“What makes our study unique and important is that it’s the first one to explain how, when, and why baleen whales got so big,” said senior author Nicholas Pysenson, curator of fossil marine mammals at the Smithsonian’s National Museum of Natural History.
The museum houses the largest and most diverse skull collections for both living and extinct baleen whales, such that Pyenson recently was able to establish that the width of a whale’s skull is a good indicator of its overall body size.
Co-author Jeremy Goldbogen of Stanford University’s Hopkins Marine Station shared that large body size in filter-feeders can enable more efficient metabolism and cheaper “cost of transport,” which essentially is the biological version of the miles-per-gallon metric for automobiles. It characterizes how much energy it takes to move a given distance.
“Larger (marine) animals have lower costs of transport, and this makes transoceanic migrations easier,” he added.
The researchers theorize that when ice sheets began to cover the Northern Hemisphere at the start of the Ice Age, run off from the new ice caps would have washed nutrients into coastal waters at certain times of the year. This would have seasonally boosted food supplies.
Lead author Graham Slater of the University of Chicago said that existent gigantic whale species “all evolved very rapidly sometime within the past 4.5 million years and — this is the big thing — they all did it independently. In other words, big whales don’t come from a single big ancestor, but they each come from a much smaller ancestor.”
Pyenson explained that the earliest ancestor of baleen whales was probably about the size of today’s bottlenose dolphins. These dolphins grow to about 8 feet long, demonstrating that blue whales can now grow 12 times larger than their earliest ancestor did.
As for why baleen whales are so big, filter-feeding provides one clue to the answer.
Baleen whales that filter small prey, such as krill, out of seawater were then well-equipped to take advantage of these dense patches of food. As the marine mammals’ body size began to increase, their foraging became all the more efficient.
Clearly not all gigantic animals have been filter-feeders, though.
“Gigantism seems to have different causes and consequences in different lineages,” Slater said. “Whether you’re warm- or cold-blooded, what kind of food you eat, and where you live will all affect how quickly you can get big and how long you survive as a lineage. In the case of baleen whales, filter-feeding sets the table, but you need to serve the food to allow them to really take advantage.”
Blue whales today are endangered, though, and face threats from climate change, pollution and other human-related problems. The environmental stage then appears to be in place for baleen whales to evolve into smaller sizes again, but scientists are not sure if the marine mammal giants are capable of doing this, and within enough time for the reduced size to benefit their survival.
Read more at Discovery News
May 23, 2017
|Island peak( Imja Tse) climbing, Everest region, Nepal.|
The findings could help scientists develop new ways of treating hypoxia -- lack of oxygen -- in patients. A significant proportion of patients in intensive care units (ICUs) experience potentially life-threatening hypoxia, a complication associated with conditions from haemorrhage to sepsis.
When oxygen is scarce, the body is forced to work harder to ensure that the brain and muscles receive enough of this essential nutrient. One of the most commonly observed ways the body has of compensating for a lack of oxygen is to produce more red blood cells, which are responsible for carrying blood around the body to our organs. This makes the blood thicker, however, so it flows more slowly and is more likely to clog up blood vessels.
Mountain climbers are often exposed to low levels of oxygen, particularly at high altitudes. This is why they often have to take time during long ascents to acclimatise to their surroundings, giving the body enough time to adapt itself and prevent altitude sickness. In addition, they may take oxygen supplies to supplement the thin air.
Scientists have known for some time that people have different responses to high altitudes. While most climbers require additional oxygen to scale Mount Everest, whose peak is 8,848m above sea level, a handful of climbers have managed to do so without. Most notably, Sherpas, an ethnic group from the mountain regions of Nepal, are able to live at high altitude with no apparent consequences to their health -- as a result, many act as guides to support expeditions in the Himalayas, and two Sherpas are known to have reached the summit of Everest an incredible 21 times.
Previous studies have suggested differences between Sherpas and people living in non-high altitude areas, known collectively as 'lowlanders', including fewer red blood cells in Sherpas at altitude, but higher levels of nitric oxide, a chemical that opens up blood vessels and keeps blood flowing.
Evidence suggests that the first humans were present on the Tibetan Plateau around 30,000 years ago, with the first permanent settlers appearing between 6,000-9,000 years ago. This raises the possibility that they have evolved to adapt to the extreme environment. This is supported by recent DNA studies, which have found clear genetic differences between Sherpa and Tibetan populations on the one hand and lowlanders on the other. Some of these differences were in their mitochondrial DNA -- the genetic code that programmes mitochondria, the body's 'batteries' that generate our energy.
To understand the biological differences between the Sherpas and lowlanders, a team of researchers led by scientists at the University of Cambridge followed two groups as they made a gradual ascent up to Everest Base Camp at an elevation of 5,300m.
The study was part of Xtreme Everest, a project that aims to improve outcomes for people who become critically ill by understanding how our bodies respond to the extreme altitude on the world's highest mountain. This year marks 10 years since the group's first expedition to Everest.
The lowlanders group comprised 10 investigators selected to operate the Everest Base Camp laboratory, where the mitochondrial studies were carried out by James Horscroft and Aleks Kotwica, two PhD students at the University of Cambridge. They took samples, including blood and muscle biopsies, in London to give a baseline measurement, then again when they first arrived at Base Camp and a third time after two months at Base Camp. These samples were compared with those taken from 15 Sherpas, all of whom were living in relatively low-lying areas, rather than being the 'elite' high altitude climbers. The Sherpas' baseline measurements were taken at Kathmandu, Nepal.
The researchers found that even at baseline, the Sherpas' mitochondria were more efficient at using oxygen to produce ATP, the energy that powers our bodies.
As predicted from genetic differences, they also found lower levels of fat oxidation in the Sherpas. Muscles have two ways to get energy -- from sugars, such as glucose, or from burning fat (fat oxidation). The majority of the time we get our energy from the latter source; however, this is inefficient, so at times of physical stress, such as when exercising, we take our energy from sugars. The low levels of fat oxidation again suggest that the Sherpas are more efficient at generating energy.
The measurements taken at altitude rarely changed from the baseline measurement in the Sherpas, suggesting that they were born with such differences. However, for lowlanders, measurements tended to change after time spent at altitude, suggesting that their bodies were acclimatising and beginning to mimic the Sherpas'.
One of the key differences, however, was in phosphocreatine levels. Phosphocreatine is an energy reserve that acts as a buffer to help muscles contract when no ATP is present. In lowlanders, after two months at high altitude, phosphocreatine levels crash, whereas in Sherpas levels actually increase.
In addition, the team found that while levels of free radicals increase rapidly at high altitude, at least initially, levels in Sherpas are very low. Free radicals are molecules created by a lack of oxygen that can be potentially damaging to cells and tissue.
"Sherpas have spent thousands of years living at high altitudes, so it should be unsurprising that they have adapted to become more efficient at using oxygen and generating energy," says Dr Andrew Murray from the University of Cambridge, the study's senior author. "When those of us from lower-lying countries spend time at high altitude, our bodies adapt to some extent to become more 'Sherpa-like', but we are no match for their efficiency."
The team say the findings could provide valuable insights to explain why some people suffering from hypoxia fare much worse in emergency situations that others.
"Although lack of oxygen might be viewed as an occupational hazard for mountain climbers, for people in intensive care units it can be life threatening," explains Professor Mike Grocott, Chair of Xtreme Everest from the University of Southampton. "One in five people admitted to intensive care in the UK each year die and even those that survive might never regain their previous quality of life.
"By understanding how Sherpas are able to survive with low levels of oxygen, we can get clues to help us identify those at greatest risk in ICUs and inform the development of better treatments to help in their recovery."
Read more at Science Daily
While most textbooks demonstrate the outer surface of the Earth as the crust, the next inner level as the mantle, and then the most inner layer as the core, Liu said the reality isn't as clear-cut.
"It's not just in layers, because the Earth's interior is not stationary," Liu said.
In fact, underneath our feet there's tectonic activity that many scientists have been aware of, but Liu and his team have created a computer model to help better explain it -- a model so effective that researchers believe it has the potential to predict where earthquakes and volcanoes will occur.
Using this model, Liu, along with doctoral student Jiashun Hu, and Manuele Faccenda from the University of Padua in Italy, recently published a research paper in the journal of Earth and Planetary Science Letters that focuses on the deep mantle and its relationship to plate tectonics.
"It's well-known that there are plate tectonics driving the Earth's evolution, but exactly how this process works is not entirely clear," he said.
Liu and Hu looked specifically at the continent of South America to determine which tectonic factors contribute to the deformation, or the evolution, of the mantle.
To answer this question, the team created a data-centric model using the Blue Waters supercomputer at the National Center for Supercomputing Applications at Illinois. The sophisticated four-dimensional data-oriented geodynamic models are among the first of their kind.
"We are actually the first ones to use data assimilation models in studying mantle deformation, in an approach similar to weather forecasting," Liu said. "We are trying to produce a system model that simultaneously satisfies all the observations we have. We can then obtain a better understanding about dynamic processes of the Earth evolution."
While there are many debates in regards to how the Earth's internal evolution is driven, the model created by the team seemed to find an answer that better fits available observations and underlying physics. The team found that the subducting slab -- a portion of the oceanic plate that slides beneath a continental plate -- is the dominant driving force behind the deformation of the mantle.
Essentially, the active subduction of the slab determines most other processes that happen as part of a chain reaction. "The result is game-changing. The driving force of mantle flow is actually simpler than people thought," Liu said. "It is the most direct consequence of plate tectonics. When the slab subducts, it naturally controls everything surrounding it. In a way this is elegant, because it's simple."
By understanding this mechanism of Earth evolution, the team can make better predictions regarding the movement of the mantle and the lithosphere, or crust.
The team then evaluated the model's predictions using other data. Hu, the lead author on the paper, said that by comparing the predictions to tectonic activities such as the formation of mountains and volcanoes, a clear consistency emerged.
"We think our story is correct," Hu said.
Consequently, the model also provides interesting insight on the evolution of continents as far back as the Jurassic, when dinosaurs roamed the Earth on Pangaea, the only continent at the time. This is still the team's ongoing research.
Liu said that in a separate paper that uses the same simulation, published by Liu and Hu in Earth and Planetary Science Letters in 2016, the model provided an accurate prediction for why earthquakes happen in particular locations below South America. He explained that earthquakes aren't evenly spread within the subducting slab, meaning there are potentially areas where an earthquake is more or less likely to take place.
"We found that whenever you see a lack of earthquakes in a region, it corresponds to a hole in the slab," Liu said. "Because of the missing slab in the hole, there's no way to generate earthquakes, so we might be able to know where more earthquakes will take place."
The model also explained why certain volcanoes might exist further inland and have different compositions, despite the common thought that volcanoes should exist solely along the coast, as a result of water coming off the down-going slab. As the model helps explain, a volcano can form inland if the slab subducts at a shallower angle, and a hole in the shallow slab allows for a special type of magma to form by melting of the crust.
Read more at Science Daily