Physicists describe new type of aurora

For millennia, humans in the high latitudes have been enthralled by auroras -- the northern and southern lights. Yet even after all that time, it appears the ethereal, dancing ribbons of light above Earth still hold some secrets.

In a new study, physicists led by the University of Iowa report a new feature to Earth's atmospheric light show. Examining video taken nearly two decades ago, the researchers describe multiple instances where a section of the diffuse aurora -- the faint, background-like glow accompanying the more vivid light commonly associated with auroras -- goes dark, as if scrubbed by a giant blotter. Then, after a short period of time, the blacked-out section suddenly reappears.

The researchers say the behavior, which they call "diffuse auroral erasers," has never been mentioned in the scientific literature. The findings appear in the Journal of Geophysical Research Space Physics.

Auroras occur when charged particles flowing from the sun -- called the solar wind -- interact with Earth's protective magnetic bubble. Some of those particles escape and fall toward our planet, and the energy released during their collisions with gases in Earth's atmosphere generate the light associated with auroras.

"The biggest thing about these erasers that we didn't know before but know now is that they exist," says Allison Jaynes, assistant professor in the Department of Physics and Astronomy at Iowa and study co-author. "It raises the question: Are these a common phenomenon that has been overlooked, or are they rare?

"Knowing they exist means there is a process that is creating them," Jaynes continues, "and it may be a process that we haven't started to look at yet because we never knew they were happening until now."

It was on March 15, 2002, that David Knudsen, a physicist at the University of Calgary, set up a video camera in Churchill, a town along Hudson Bay in Canada, to film auroras. Knudsen's group was a little disheartened; the forecast called for clear, dark skies -- normally perfect conditions for viewing auroras -- but no dazzling illumination was happening. Still, the team was using a camera specially designed to capture low-level light, much like night-vision goggles.

Though the scientists saw only mostly darkness as they gazed upward with their own eyes, the camera was picking up all sorts of auroral activity, including an unusual sequence where areas of the diffuse aurora disappeared, then came back.

Knudsen, looking at the video as it was being recorded, scribbled in his notebook, "pulsating 'black out' diffuse glow, which then fills in over several seconds."

"What surprised me, and what made me write it in the notebook, is when a patch brightened and turned off, the background diffuse aurora was erased. It went away," says Knudsen, a Fort Dodge, Iowa, native who has studied aurora for more than 35 years and is a co-author on the study. "There was a hole in the diffuse aurora. And then that hole would fill back in after a half-minute or so. I had never seen something like that before."

The note lay dormant, and the video unstudied, until Iowa's Jaynes handed it to graduate student Riley Troyer to investigate. Jaynes learned about Knudsen's recording at a scientific meeting in 2010 and referenced the eraser note in her doctoral thesis on diffuse aurora a few years later. Now on the faculty at Iowa, she wanted to learn more about the phenomenon.

"I knew there was something there. I knew it was different and unique," says Jaynes, assistant professor in the Department of Physics and Astronomy. "l had some ideas how it could be analyzed, but I hadn't done that yet. I handed it to Riley, and he went much further with it by figuring out his own way to analyze the data and produce some significant conclusions."

Troyer, from Fairbanks, Alaska, took up the assignment with gusto.

"I've seen hundreds of auroras growing up," says Troyer, who is in his third year of doctoral studies at Iowa. "They're part of my heritage, something I can study while keeping ties to where I'm from."

Troyer created a software program to key in on frames in the video when the faint erasers were visible. In all, he cataloged 22 eraser events in the two-hour recording.

"The most valuable thing we found is showing the time that it takes for the aurora to go from an eraser event (when the diffuse aurora is blotted out) to be filled or colored again," says Troyer, who is the paper's corresponding author, "and how long it takes to go from that erased state back to being diffuse aurora. Having a value on that will help with future modeling of magnetic fields."

Jaynes says learning about diffuse auroral erasers is akin to studying DNA to understand the entire human body.

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Children likely to be pleading guilty when innocent

The study says differences in children's brains, which affect their sensitivity to pressure and rewards, and differences in the way they process information, make it more likely they will admit to crimes they didn't commit when incentivized to do so.

These developmental vulnerabilities mean solicitors and barristers should get extra support to help them better support young people deciding whether to admit guilt.

Dr Rebecca Helm, from the University of Exeter, who led the research, published in the Journal of Law and Society, said: "The criminal justice system relies almost exclusively on the autonomy of defendants, rather than accuracy, when justifying convictions via guilty plea. But children don't necessarily have the capacity to make truly autonomous decisions in this context, where they face a variety of really compelling pressures. Children are likely to misunderstand information, not admit they don't understand and agree with statements, or succumb to pressure from others and the system. They may be unsure whether they have committed a legal offence, or whether there is a defence they can rely on.

"The incentives offered to encourage guilty pleas, and time pressures associated with them, are likely to interact with developmental vulnerabilities in children to create an environment in which innocent children are systematically pleading guilty."

In England and Wales, the majority of defendants plead guilty rather than contest their guilt at trial. In 2019, 61 per cent of child defendants in the Crown Court pleaded guilty (with 58 per cent pleading guilty at their first hearing), and 47 per cent of child defendants in the Youth Court pleaded guilty at their first hearing.

Children who enter a guilty plea at the earliest possible opportunity to do so can get a reduction in their sentence of up to a third compared to what they would receive if convicted at trial, or receive a referral order or a youth rehabilitation order when they would face a custodial sentence at trial. The study says that these reductions are not appropriate in children and have the potential to create pressures to plead. It would be better to award tailored reductions to children based on less prescriptive guidelines and individual case circumstances, including defendant age.

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Feeling younger buffers older adults from stress, protects against health decline

People who feel younger have a greater sense of well-being, better cognitive functioning, less inflammation, lower risk of hospitalization and even live longer than their older-feeling peers. A study published by the American Psychological Association suggests one potential reason for the link between subjective age and health: Feeling younger could help buffer middle-aged and older adults against the damaging effects of stress.

In the study, published in Psychology and Aging, researchers from the German Centre of Gerontology analyzed three years of data from 5,039 participants in the German Ageing Survey, a longitudinal survey of residents of Germany age 40 and older. The survey included questions about the amount of perceived stress in peoples' lives and their functional health -- how much they were limited in daily activities such as walking, dressing and bathing. Participants also indicated their subjective age by answering the question, "How old do you feel?"

The researchers found, on average, participants who reported more stress in their lives experienced a steeper decline in functional health over three years, and that link between stress and functional health decline was stronger for chronologically older participants.

However, subjective age seemed to provide a protective buffer. Among people who felt younger than their chronological age, the link between stress and declines in functional health was weaker. That protective effect was strongest among the oldest participants.

"Generally, we know that functional health declines with advancing age, but we also know that these age-related functional health trajectories are remarkably varied. As a result, some individuals enter old age and very old age with quite good and intact health resources, whereas others experience a pronounced decline in functional health, which might even result in need for long-term care," said study lead author Markus Wettstein, PhD, who is now at University of Heidelberg. "Our findings support the role of stress as a risk factor for functional health decline, particularly among older individuals, as well as the health-supporting and stress-buffering role of a younger subjective age."

The results suggest that interventions that aim to help people feel younger could reduce the harm caused by stress and improve health among older adults, according to the researchers -- though further study is needed to help determine what kind of interventions would work best. For example, Wettstein said, messaging campaigns to counteract ageism and negative age stereotypes and to promote positive views on aging could help people feel younger. In addition, more general stress-reduction interventions and stress management training could prevent functional health loss among older adults, according to Wettstein.

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Supernovae twins open up new possibilities for precision cosmology

Cosmologists have found a way to double the accuracy of measuring distances to supernova explosions -- one of their tried-and-true tools for studying the mysterious dark energy that is making the universe expand faster and faster. The results from the Nearby Supernova Factory (SNfactory) collaboration, led by Greg Aldering of the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab), will enable scientists to study dark energy with greatly improved precision and accuracy, and provide a powerful crosscheck of the technique across vast distances and time. The findings will also be central to major upcoming cosmology experiments that will use new ground and space telescopes to test alternative explanations of dark energy.

Two papers published in The Astrophysical Journal report these findings, with Kyle Boone as lead author. Currently a postdoctoral fellow at the University of Washington, Boone is a former graduate student of Nobel Laureate Saul Perlmutter, the Berkeley Lab senior scientist and UC Berkeley professor who led one of the teams that originally discovered dark energy. Perlmutter was also a co-author on both studies.

Supernovae were used in 1998 to make the startling discovery that the expansion of the universe is speeding up, rather than slowing down as had been expected. This acceleration -- attributed to the dark energy that makes up two-thirds of all the energy in the universe -- has since been confirmed by a variety of independent techniques as well as with more detailed studies of supernovae.

The discovery of dark energy relied on using a particular class of supernovae, Type Ia. These supernovae always explode with nearly the same intrinsic maximum brightness. Because the observed maximum brightness of the supernova is used to infer its distance, the small remaining variations in the intrinsic maximum brightness limited the precision with which dark energy could be tested. Despite 20 years of improvements by many groups, supernovae studies of dark energy have until now remained limited by these variations.

Quadrupling the number of supernovae

The new results announced by the SNfactory come from a multi-year study devoted entirely to increasing the precision of cosmological measurements made with supernovae. Measurement of dark energy requires comparisons of the maximum brightnesses of distant supernovae billions of light-years away with those of nearby supernovae "only" 300 million light-years away. The team studied hundreds of such nearby supernovae in exquisite detail. Each supernova was measured a number of times, at intervals of a few days. Each measurement examined the spectrum of the supernova, recording its intensity across the wavelength range of visible light. An instrument custom-made for this investigation, the SuperNova Integral Field Spectrometer, installed at the University of Hawaii 2.2-meter telescope at Maunakea, was used to measure the spectra.

"We've long had this idea that if the physics of the explosion of two supernovae were the same, their maximum brightnesses would be the same. Using the Nearby Supernova Factory spectra as a kind of CAT scan through the supernova explosion, we could test this idea," said Perlmutter.

Indeed, several years ago, physicist Hannah Fakhouri, then a graduate student working with Perlmutter, made a discovery key to today's results. Looking at a multitude of spectra taken by the SNfactory, she found that in quite a number of instances, the spectra from two different supernovae looked very nearly identical. Among the 50 or so supernovae, some were virtually identical twins. When the wiggly spectra of a pair of twins were superimposed, to the eye there was just a single track. The current analysis builds on this observation to model the behavior of supernovae in the period near the time of their maximum brightness.

The new work nearly quadruples the number of supernovae used in the analysis. This made the sample large enough to apply machine-learning techniques to identify these twins, leading to the discovery that Type Ia supernova spectra vary in only three ways. The intrinsic brightnesses of the supernovae also depend primarily on these three observed differences, making it possible to measure supernova distances to the remarkable accuracy of about 3%.

Just as important, this new method does not suffer from the biases that have beset previous methods, seen when comparing supernovae found in different types of galaxies. Since nearby galaxies are somewhat different than distant ones, there was a serious concern that such dependence would produce false readings in the dark energy measurement. Now this concern can be greatly reduced by measuring distant supernovae with this new technique.

In describing this work, Boone noted, "Conventional measurement of supernova distances uses light curves -- images taken in several colors as a supernova brightens and fades. Instead, we used a spectrum of each supernova. These are so much more detailed, and with machine-learning techniques it then became possible to discern the complex behavior that was key to measuring more accurate distances."

The results from Boone's papers will benefit two upcoming major experiments. The first experiment will be at the 8.4-meter Rubin Observatory, under construction in Chile, with its Legacy Survey of Space and Time, a joint project of the Department of Energy and the National Science Foundation. The second is NASA's forthcoming Nancy Grace Roman Space Telescope. These telescopes will measure thousands of supernovae to further improve the measurement of dark energy. They will be able to compare their results with measurements made using complementary techniques.

Aldering, also a co-author on the papers, observed that "not only is this distance measurement technique more accurate, it only requires a single spectrum, taken when a supernova is brightest and thus easiest to observe -- a game changer!" Having a variety of techniques is particularly valuable in this field where preconceptions have turned out to be wrong and the need for independent verification is high.

The SNfactory collaboration includes Berkeley Lab, the Laboratory for Nuclear Physics and High Energy at Sorbonne University, the Center for Astronomical Research of Lyon, the Institute of Physics of the 2 Infinities at the University Claude Bernard, Yale University, Germany's Humboldt University, the Max Planck Institute for Astrophysics, China's Tsinghua University, the Center for Particle Physics of Marseille, and Clermont Auvergne University.

This work was supported by the Department of Energy's Office of Science, NASA's Astrophysics Division, the Gordon and Betty Moore Foundation, the French National Institute of Nuclear and Particle Physics and the National Institute for Earth Sciences and Astronomy of the French National Centre for Scientific Research, the German Research Foundation and German Aerospace Center, the European Research Council, Tsinghua University, and the National Natural Science Foundation of China.

Additional background

In 1998, two competing groups studying supernovae, the Supernova Cosmology Project and the High-z Supernova Search team, both announced they had found evidence that, contrary to expectations, the expansion of the universe was not slowing but becoming faster and faster. Dark energy is the term used to describe the cause of the acceleration. The 2011 Nobel Prize was awarded to leaders of the two teams: Saul Perlmutter of Berkeley Lab and UC Berkeley, leader of the Supernova Cosmology Project, and to Brian Schmidt of the Australian National University and Adam Riess of Johns Hopkins University, from the High-z team.

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The cerebellum may have played an important role in the evolution of the human brain

The cerebellum -- a part of the brain once recognized mainly for its role in coordinating movement -- underwent evolutionary changes that may have contributed to human culture, language and tool use. This new finding appears in a study by Elaine Guevara of Duke University and colleagues, published May 6th in the journal PLOS Genetics.

Scientists studying how humans evolved their remarkable capacity to think and learn have frequently focused on the prefrontal cortex, a part of the brain vital for executive functions, like moral reasoning and decision making. But recently, the cerebellum has begun receiving more attention for its role in human cognition. Guevara and her team investigated the evolution of the cerebellum and the prefrontal cortex by looking for molecular differences between humans, chimpanzees, and rhesus macaque monkeys. Specifically, they examined genomes from the two types of brain tissue in the three species to find epigenetic differences. These are modifications that do not change the DNA sequence but can affect which genes are turned on and off and can be inherited by future generations.

Compared to chimpanzees and rhesus macaques, humans showed greater epigenetic differences in the cerebellum than the prefrontal cortex, highlighting the importance of the cerebellum in human brain evolution. The epigenetic differences were especially apparent on genes involved in brain development, brain inflammation, fat metabolism and synaptic plasticity -- the strengthening or weakening of connections between neurons depending on how often they are used.

The epigenetic differences identified in the new study are relevant for understanding how the human brain functions and its ability to adapt and make new connections. These epigenetic differences may also be involved in aging and disease. Previous studies have shown that epigenetic differences between humans and chimpanzees in the prefrontal cortex are associated with genes involved in psychiatric conditions and neurodegeneration. Overall, the new study affirms the importance of including the cerebellum when studying how the human brain evolved.

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Sharks use Earth's magnetic fields to guide them like a map

Sea turtles are known for relying on magnetic signatures to find their way across thousands of miles to the very beaches where they hatched. Now, researchers reporting in the journal Current Biology on May 6 have some of the first solid evidence that sharks also rely on magnetic fields for their long-distance forays across the sea.

"It had been unresolved how sharks managed to successfully navigate during migration to targeted locations," said Save Our Seas Foundation project leader Bryan Keller, also of Florida State University Coastal and Marine Laboratory. "This research supports the theory that they use the earth's magnetic field to help them find their way; it's nature's GPS."

Researchers had known that some species of sharks travel over long distances to reach very specific locations year after year. They also knew that sharks are sensitive to electromagnetic fields. As a result, scientists had long speculated that sharks were using magnetic fields to navigate. But the challenge was finding a way to test this in sharks.

"To be honest, I am surprised it worked," Keller said. "The reason this question has been withstanding for 50 years is because sharks are difficult to study."

Keller realized the needed studies would be easier to do in smaller sharks. They also needed a species known for returning each year to specific locations. He and his colleagues settled on bonnetheads (Sphyrna tiburo).

"The bonnethead returns to the same estuaries each year," Keller said. "This demonstrates that the sharks knows where 'home' is and can navigate back to it from a distant location."

The question then was whether bonnetheads managed those return trips by relying on a magnetic map. To find out, the researchers used magnetic displacement experiments to test 20 juvenile, wild-caught bonnetheads. In their studies, they exposed sharks to magnetic conditions representing locations hundreds of kilometers away from where the sharks were actually caught. Such studies allow for straightforward predictions about how the sharks should subsequently orient themselves if they were indeed relying on magnetic cues.

If sharks derive positional information from the geomagnetic field, the researchers predicted northward orientation in the southern magnetic field and southward orientation in the northern magnetic field, as the sharks attempted to compensate for their perceived displacement. They predicted no orientation preference when sharks were exposed to the magnetic field that matched their capture site. And, it turned out, the sharks acted as they'd predicted when exposed to fields within their natural range.

The researchers suggest that this ability to navigate based on magnetic fields may also contribute to the population structure of sharks. The findings in bonnetheads also likely help to explain impressive feats by other shark species. For instance, one great white shark was documented to migrate between South Africa and Australia, returning to the same exact location the following year.

"How cool is it that a shark can swim 20,000 kilometers round trip in a three-dimensional ocean and get back to the same site?" Keller asked. "It really is mind blowing. In a world where people use GPS to navigate almost everywhere, this ability is truly remarkable."

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Bats know the speed of sound from birth, scientists discovery

A new Tel Aviv University study has revealed, for the first time, that bats know the speed of sound from birth. In order to prove this, the researchers raised bats from the time of their birth in a helium-enriched environment in which the speed of sound is higher than normal. They found that unlike humans, who map the world in units of distance, bats map the world in units of time. What this means is that the bat perceives an insect as being at a distance of nine milliseconds, and not one and a half meters, as was thought until now.

The study was published in the Proceedings of the National Academy of Sciences.

In order to determine where things are in a space, bats use sonar -- they produce sound waves that hit objects and are reflected back to the bat. Bats can estimate the position of the object based on the time that elapses between the moment the sound wave is produced and the moment it is returned to the bat. This calculation depends on the speed of sound, which can vary in different environmental conditions, such as air composition or temperature. For example, there could be a difference of almost 10% between the speed of sound at the height of the summer, when the air is hot and the sound waves spread faster, and the winter season. Since the discovery of sonar in bats 80 years ago, researchers have been trying to figure out whether bats acquire the ability to measure the speed of sound over the course of their lifetime or are born with this innate, constant sense.

Now, researchers led by Prof. Yossi Yovel, head of the Sagol School of Neuroscience and a faculty member of the School of Zoology in the Faculty of Life Sciences and his former doctoral student Dr. Eran Amichai (currently studying at Dartmouth College) have succeeded in answering this question. The researchers conducted an experiment in which they were able to manipulate the speed of sound. They enriched the air composition with helium to increase the speed of sound, and under these conditions raised bat pups from the time of their birth, as well as adult bats. Neither the adult bats nor the bat pups were able to adjust to the new speed of sound and consistently landed in front of the target, indicating that they perceived the target as being closer -- that is, they did not adjust their behavior to the higher speed of sound.

Because this occurred both in the adult bats that had learned to fly in normal environmental conditions and in the pups that learned to fly in an environment with a higher-than-normal speed of sound, the researchers concluded that the rate of the speed of sound in bats is innate -- they have a constant sense of it. "Because bats need to learn to fly within a short time of their birth," explains Prof. Yovel, "we hypothesize that an evolutionary 'choice' was made to be born with this knowledge in order to save time during the sensitive development period."

Another interesting conclusion of the study is that bats do not actually calculate the distance to the target according to the speed of sound. Because they do not adjust the speed of sound encoded in their brains, it seems that they also do not translate the time it takes for the sound waves to return into units of distance. Therefore, their spatial perception is actually based on measurements of time and not distance.

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Earliest evidence of humans changing ecosystems with fire

Mastery of fire has given humans dominance over the natural world. A Yale-led study provides the earliest evidence to date of ancient humans significantly altering entire ecosystems with flames.

The study, published on May 5 in the journal Science Advances, combines archaeological evidence -- dense clusters of stone artifacts dating as far back as 92,000 years ago -- with paleoenvironmental data on the northern shores of Lake Malawi in eastern Africa to document that early humans were ecosystem engineers. They used fire in a way that prevented regrowth of the region's forests, creating a sprawling bushland that exists today.

Yale paleoanthropologist Jessica Thompson describes the earliest evidence of humans altering their ecosystem with fire in this video.

"This is the earliest evidence I have seen of humans fundamentally transforming their ecosystem with fire," said Jessica Thompson, assistant professor of anthropology in the Faculty of Arts and Sciences and the paper's lead author. "It suggests that by the Late Pleistocene, humans were learning to use fire in truly novel ways. In this case, their burning caused replacement of the region's forests with the open woodlands you see today."

Thompson authored the study with 27 colleagues from institutions in the United States, Africa, Europe, Asia, and Australia. Thompson led the archaeological work in collaboration with the Malawi Department of Museums and Monuments; David Wright of the University of Oslo, who led efforts to date the study's archaeological sites; and Sarah Ivory of Penn State, who led the paleoenvironmental analyses.

The artifacts examined by the researchers are of the type produced across Africa in the Middle Stone Age, a period dating back at least 315,000 years. The earliest modern humans made their appearance during this period, with the African archaeological record showing significant advances in cognitive and social complexity.

Thompson and Wright logged several field seasons of archaeological work in the region before a conversation with Ivory helped them make sense of the patterns they observed in their data. The researchers discovered that the regional archaeological record, its ecological changes, and the development of alluvial fans near Lake Malawi -- an accumulation of sediment eroded from the region's highland -- dated to the same period of origin, suggesting that they were connected.

Lake Malawi's water levels have fluctuated drastically over the ages. During the lake's driest periods, the last of which ended about 85,000 years ago, it diminished into two small, saline bodies of water. The lake recovered from these arid stretches and its levels have remained high ever since, according to the study.

The archaeological data were collected from more than 100 pits excavated across hundreds of kilometers of the alluvial fan that developed during this time of steady lake levels. The paleoenvironmental data are based on counts of pollen and charcoal that settled to the floor of the lakebed and were later recovered in a long sediment core drilled from a modified barge.

According to the researchers, the data revealed that a spike in charcoal accumulation occurred shortly before the flattening of the region's species richness -- the number of distinct species inhabiting it. Despite the consistently high lake levels, which imply greater stability in the ecosystem, the species richness went flat following the last arid period based on information from fossilized pollen sampled from the lakebed, the study found. This was unexpected because over previous climate cycles, rainy environments had produced forests that provide rich habitat for an abundance of species, Ivory explained.

"The pollen that we see in this most recent period of stable climate is very different than before," she said. "Specifically, trees that indicate dense, structurally complex forest canopies are no longer common and are replaced by pollen from plants that deal well with frequent fire and disturbance."

The increase in archaeological sites after the last arid period, paired with the spike in charcoal and absence of forest, suggests that people were manipulating the ecosystem with fire, the researchers conclude. The scale of their environmental impact over the long term is something typically associated with farmers and herders, rather than hunter-gatherers. This suggests early ecological manipulation on par with modern people and may also explain why the archaeological record formed.

The burning paired with climate-driven changes created the conditions that allowed for preservation of millions of artifacts in the region, the researchers explained. "Dirt rolls downhill unless there is something to stop it," Wright said. "Take the trees away, and when it rains, there is a lot of dirt moving downhill in this environment."

Previous transitions from dry to wet conditions in the region didn't yield a similar alluvial fan and were not preceded by the same charcoal spike, the researchers noted.

It's not clear why people were burning the landscape, Thompson said. It's possible that they were experimenting with controlled burns to produce mosaic habitats conducive to hunting and gathering, a behavior documented among hunter-gatherers. It could be that their fires burned out of control, or that there were simply a lot of people burning fuel in their environment that provided for warmth, cooking, or socialization, she explained.

"One way or another, it's caused by human activity," she said. "It shows early people, over a long period of time, took control over their environment rather than being controlled by it. They changed entire landscapes, and for better or for worse that relationship with our environments continues today."

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A new window to see hidden side of magnetized universe

New observations and simulations show that jets of high-energy particles emitted from the central massive black hole in the brightest galaxy in galaxy clusters can be used to map the structure of invisible inter-cluster magnetic fields. These findings provide astronomers with a new tool for investigating previously unexplored aspects of clusters of galaxies.

As clusters of galaxies grow through collisions with surrounding matter, they create bow shocks and wakes in their dilute plasma. The plasma motion induced by these activities can drape intra-cluster magnetic layers, forming virtual walls of magnetic force. These magnetic layers, however, can only be observed indirectly when something interacts with them. Because it is simply difficult to identify such interactions, the nature of intra-cluster magnetic fields remains poorly understood. A new approach to map/characterize magnetic layers is highly desired.

An international team of astronomers including Haruka Sakemi, a graduate student at Kyushu University (now a research fellow at the National Astronomical Observatory of Japan -- NAOJ), used the MeerKAT radio telescope located in the Northern Karoo desert of South Africa to observe a bright galaxy in the merging galaxy cluster Abell 3376 known as MRC 0600-399. Located more than 600 million light-years away in the direction of the constellation Columba, MRC 0600-399 is known to have unusual jet structures bent to 90-degree angles. Previous X-ray observations revealed that MRC 0600-399 is the core of a sub-cluster penetrating the main cluster of galaxies, indicating the presence of strong magnetic layers at the boundary between the main and sub-clusters. These features make MRC 0600-399 an ideal laboratory to investigate interactions between jets and strong magnetic layers.

The MeerKAT observations revealed unprecedented details of the jets, most strikingly, faint "double-scythe" structure extending in the opposite direction from the bend points and creating a "T" shape. These new details show that, like a stream of water hitting a pane of glass, this is a very chaotic collision. Dedicated computer simulations are required to explain the observed jet morphology and possible magnetic field configurations.

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Your stomach may be the secret to fighting obesity

Scientists believe a stomach-specific protein plays a major role in the progression of obesity, according to new research in Scientific Reports. The study co-authored by an Indiana University School of Medicine researcher, could help with development of therapeutics that would help individuals struggling with achieving and maintaining weight loss.

Researchers focused on Gastrokine-1 (GKN1) -- a protein produced exclusively and abundantly in the stomach. Previous research has suggested GKN1 is resistant to digestion, allowing it to pass into the intestine and interact with microbes in the gut.

In the Scientific Reports study, researchers show that inhibiting GKN1 produced significant differences in weight and levels of body fat in comparison to when the protein was expressed.

"While diet and exercise are critical to maintaining a healthy weight, some individuals struggle with weight loss -- even in cases of bariatric surgery, maintaining weight loss can be a challenge," said David Boone, PhD, associate professor of microbiology and immunology at IU School of Medicine, an adjunct professor in the Department of Biology at the University of Notre Dame and a co-author of the study. "These results are an example of how a better understanding of the gut microbiome and the physiological aspects of obesity -- how our bodies regulate metabolism and accumulate body fat -- could help inform new therapies."

Data from the Centers for Disease Control show adult obesity rates have increased to 42.4 percent in the United States. In addition to increasing an individual's risk of stroke, diabetes, certain cancers and other health issues, obesity can also increase the risk of severe illness due to COVID-19.

Boone and his team conducted a microbiome analysis of mouse models with and without the GKN1 protein expressed. Researchers measured food intake, caloric extraction, blood sugar, insulin and triglyceride levels. They used magnetic resonance imagining to monitor body composition. The team also calculated energy expenditure and observed inflammation levels.

Models without GKN1 weighed less and had lower levels of total body fat and higher percentages of lean mass -- despite consuming the same amount of food. When put on a high-fat diet, models without GKN1 showed a resistance to weight gain, increased body fat and hepatic inflammation, which can lead to liver disease. Researchers also found no evidence of adverse effects such as cancer, diabetes, loss of appetite, malabsorption or inflammation -- and results were consistent in male and female models.

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Shining new light on stepparent fairy-tale stereotype

Although the fairy tale of the wicked stepmother is a tale as old as time, the effects of blending children with their new stepfamilies may not be as grim as once thought.

In fact, new research shows that stepchildren are not at a disadvantage compared to their peers from single-parent households and actually experience better outcomes than their halfsiblings -- good news for the more than 113 million Americans that are part of a steprelationship.

Led by East Carolina University anthropologist Ryan Schacht and researchers from the University of Utah, the study, "Was Cinderella just a fairy tale? Survival differences between stepchildren and their half-siblings," is available in the May edition of the Philosophical Transactions of the Royal Society B.

The study challenges the "Cinderella effect" theory. The effect contends that conflict within stepfamilies over physical, financial and emotional resources leads to higher mortality risks for stepchildren, and is a main factor in higher rates of abuse and neglect. The phenomenon suggests that stepparents play a major role in this abuse, hoarding resources for their biological children and leading to negative outcomes for stepchildren.

Schacht proposes that previous studies have placed blame for the negative outcomes associated with parental loss on stepparents yet have done so through an an "apples-to-oranges comparison." Specifically, they compare of the long-term outcomes of children who have suffered trauma like parental loss versus children from stable households. When the team compared stepchild outcomes more appropriately among those children who too have experienced the economic and emotional hardships associated with parental loss, they found no difference. Specifically, the introduction stepparenents did not increase stepchild mortality.

"The idea of a stepparent, especially the stepmother, as being an agent of evil seems to be a story as old as time," Schacht said. "It's easy to sell the Cinderella effect's result because we've been told these stories about the problems that stepfamilies experience for hundreds of years.

"We're not denying that some stepchildren suffer," he said. "However, if we truly believe it is the stepparent that is the source of negative outcomes for a stepchild, then we need to compare similar environments and experiences. A child that hasn't lost a parent through death or divorce hasn't experienced the same trauma that a stepchild has; comparing those two experiences and blaming the stepparent for diverging outcomes isn't a fair comparison."

The study compared the mortality of stepchildren whose parents remarried after the death of a spouse to children whose parents did not remarry and found three key findings:

* Parental mortality has a negative effect on children under 18 years old, especially for infants losing a mother;

* Children whose parents remarried after the loss of a spouse did not suffer a mortality rate any greater than children whose parents did not remarry; and

* Stepchildren received a protective effect when a halfsibling was introduced to their new family.

"The metrics of what makes a family successful -- household stability, relationship stability and economic stability -- are achieved by stepparents investing in their stepchildren to make that a reality. Coming in with an antagonistic approach doesn't make sense if stepparents want their relationship to succeed."

The research team analyzed a data set of more than 400,000 children from Utah from 1847-1940. Schacht said the time period provided an opportunity to analyze stepchild mortality rates in families during a natural fertility period where families were larger in size and most stepfamilies were formed due to the death of a parent.

The study adds that children who have suffered parental loss have more in common with their peers from single-parent households, facing many of the same educational, economic and health care disparities.

Read more at Science Daily

Too much, too little sleep linked to elevated heart risks in people free from disease

People who clock six to seven hours of sleep a night had the lowest chance of dying from a heart attack or stroke when compared with those who got less or more sleep, according to a study being presented at the American College of Cardiology's 70th Annual Scientific Session. This trend remained true even after the research team accounted for other known conditions or risk factors for heart disease or stroke.

The study, according to researchers, is the first to explore the association between baseline cardiovascular risk and duration of sleep and adds to mounting evidence that sleep -- similar to diet, smoking and exercise -- may play a defining role in someone's cardiovascular risk.

"Sleep is often overlooked as something that may play a role in cardiovascular disease, and it may be among the most cost-effective ways to lower cardiovascular risk," said Kartik Gupta, MD, resident, Division of Internal Medicine, Henry Ford Hospital in Detroit and lead author of the study. "Based on our data, sleeping six to seven hours a night is associated with more favorable heart health."

For the study, Gupta and his team included data from 14,079 participants in the 2005-2010 National Health and Nutrition Examination Survey. Participants were followed for a median duration of 7.5 years to determine if they died due to heart attack, heart failure or stroke. Those surveyed were 46 years old on average, half were women and 53% were non-white. Less than 10% of participants had a history of heart disease, heart failure or stroke.

Researchers divided participants into three groups based on answers to a survey question about their average length of sleep -- less sleep (seven hours). Researchers then assessed participants' atherosclerotic cardiovascular disease (ASCVD) risk scores and levels of C-reactive protein (CRP), a key inflammatory marker known to be associated with heart disease.

The ASCVD risk score, which accounts for age, gender, race, blood pressure and cholesterol, is widely used to predict how likely someone is to have a heart attack or stroke or die from atherosclerosis, a hardening of the arteries, in the next 10 years. An ASCVD risk score less than 5% is considered low risk.

While the median ASCVD risk was 3.5% among all participants, there was a U-shape relationship based on sleep duration such that participants with six to seven hours had the lowest risk. The median 10-year ASCVD risk among people with less than six, six to seven and more than seven hours of sleep were 4.6%, 3.3% and 3.3%, respectively.

"Participants who slept less than six hours or more than seven hours had a higher chance of death due to cardiac causes. ASCVD risk score was, however, the same in those who sleep six to seven hours versus more than seven hours," Gupta said, adding that the ASCVD risk score may not adequately capture elevated cardiac risk in this subgroup and that results are perhaps stronger for participants sleeping less than six hours a night.

Levels of CRP, a protein made in the liver that rises when there is inflammation in the body, were also higher in participants with longer or shorter durations of sleep.

"Participants who sleep less or more than six to seven hours have higher ASCVD risk scores, which is likely driven by heightened inflammation as measured by CRP, which was found to be higher among those who had less or more sleep," Gupta said, adding that CRP levels were only collected at the start of the study. "The effect of sleep probably accrues over time; it takes time for the damage to happen."

According to the researchers, unlike some risk factors for heart disease that can't be changed, such as age or genetics, sleep habits can be adjusted and should be routinely asked about during medical visits.

"It's important to talk about not only the amount of sleep but the depth and quality of sleep too. Just because you are lying in bed for seven hours doesn't mean that you are getting good quality sleep," Gupta said, adding that this study is limited to sleep quantity, not quality or how well or deeply someone sleeps. For example, sleep apnea, which is a sleep disorder that results in frequent awakenings, is increasingly associated with cardiovascular disease.

Read more at Science Daily

'Oddball supernova' appears strangely cool before exploding

A curiously yellow star has caused astrophysicists to reevaluate what's possible within our universe.

Led by Northwestern University, the international team used NASA's Hubble Space Telescope to examine the massive star two-and-a-half years before it exploded into a supernova. At the end of their lives, cool, yellow stars are typically shrouded in hydrogen, which conceals the star's hot, blue interior. But this yellow star, located 35 million lightyears from Earth in the Virgo galaxy cluster, was mysteriously lacking this crucial hydrogen layer at the time of its explosion.

"We haven't seen this scenario before," said Northwestern's Charles Kilpatrick, who led the study. "If a star explodes without hydrogen, it should be extremely blue -- really, really hot. It's almost impossible for a star to be this cool without having hydrogen in its outer layer. We looked at every single stellar model that could explain a star like this, and every single model requires that the star had hydrogen, which, from its supernova, we know it did not. It stretches what's physically possible."

The team describes the peculiar star and its resulting supernova in a new study, which was published today (May 5) in the Monthly Notices of the Royal Astronomical Society. In the paper, the researchers hypothesize that, in the years preceding its death, the star might have shed its hydrogen layer or lost it to a nearby companion star.

Kilpatrick is a postdoctoral fellow at Northwestern's Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and member of the Young Supernova Experiment, which uses the Pan-STARSS telescope at Haleakal?, Hawaii, to catch supernovae right after they explode.

Catching a star before it explodes

After the Young Supernova Experiment spotted supernova 2019yvr in the relatively nearby spiral galaxy NGC 4666, the team used deep space images captured by NASA's Hubble Space Telescope, which fortunately already observed this section of the sky.

"What massive stars do right before they explode is a big unsolved mystery," Kilpatrick said. "It's rare to see this kind of star right before it explodes into a supernova."

The Hubble images showed the source of the supernova, a massive star imaged just a couple years before the explosion. Although the supernova itself appeared completely normal, its source -- or progenitor star -- was anything but.

"When it exploded, it seemed like a very normal hydrogen-free supernova," Kilpatrick said. "There was nothing outstanding about this. But the progenitor star didn't match what we know about this type of supernova."

Direct evidence of violent death

Several months after the explosion, however, Kilpatrick and his team discovered a clue. As ejecta from the star's final explosion traveled through its environment, it collided with a large mass of hydrogen. This led the team to hypothesize that the progenitor star might have expelled the hydrogen within a few years before its death.

"Astronomers have suspected that stars undergo violent eruptions or death throes in the years before we see supernovae," Kilpatrick said. "This star's discovery provides some of the most direct evidence ever found that stars experience catastrophic eruptions, which cause them to lose mass before an explosion. If the star was having these eruptions, then it likely expelled its hydrogen several decades before it exploded."

In the new study, Kilpatrick's team also presents another possibility: A less massive companion star might have stripped away hydrogen from the supernova's progenitor star. The team, however, will not be able to search for the companion star until after the supernova's brightness fades, which could take up to 10 years.

Read more at Science Daily

Circadian rhythm research could turn early birds into night owls

How body clocks work could lead to science that can turn an early bird into a night owl or vice versa as well as other advances, like helping crops grow all year long.

In Applied Physics Reviews, by AIP Publishing, scientists at Penn State report on their work advancing knowledge about circadian rhythms, the natural process that governs sleep and waking patterns in humans, animals, and plants.

Researchers have identified a set of genes, called clock genes, that control these rhythms. But a more complicated network of genes than previously known appears related to circadian rhythms. More fully understanding this network is key to understanding how the rhythms work and could potentially be changed.

The authors detail a statistical model they are using to help identify all the genes involved in this network. With the help of scientists from other disciplines, they hope to fully understand how these genes work together to make one person more productive in the early morning while another thrives in the middle of the night.

Doing so could lead to the creation of medicines that would help someone who is naturally a day person but required to work nights, or one who struggles to be productive first thing in the morning.

"If we understand the gene for a night owl, we can develop a drug to activate that gene for an early bird who has to live a lifestyle like a night owl," said author Rongling Wu, director of the Center for Statistical Genetics at Penn State.

There are also possible health benefits. Disrupted circadian rhythms have been linked to health issues including depression, anxiety, weight gain, and cardiovascular disease.

And while most people probably think of circadian rhythms in humans, plants and animals have them, too. A breakthrough in understanding the clock-gene network could help increase crop production.

For example, wheat, which tends to "rest" during the middle of the day, could be modified to grow all day long and be harvested more quickly. Or a crop that does not grow well in northern areas with less daylight and colder temperatures could have genes altered to make it ignore those conditions.

Read more at Science Daily

New study deconstructs Dunbar's number (number of friends)

An individual human can maintain stable social relationships with about 150 people. This is the proposition known as 'Dunbar's number' -- that the architecture of the human brain sets an upper limit on our social lives. A new study from Stockholm University indicates that a cognitive limit on human group sizes cannot be derived in this manner.

Dunbar's number is named after the British anthropologist Robin Dunbar, who proposed the theory in the 1990s. The number 150 is based on an extrapolation of the correlation between the relative size of the neocortex and group sizes in non-human primates. Some empirical studies have found support for this number, while other have reported other group sizes.

"The theoretical foundation of Dunbar's number is shaky. Other primates' brains do not handle information exactly as human brains do, and primate sociality is primarily explained by other factors than the brain, such as what they eat and who their predators are. Furthermore, humans have a large variation in the size of their social networks," says Patrik Lindenfors, Associate Professor of Zoological Ecology at Stockholm University and the Institute for Futures Studies, and one of the authors of the study.

When the Swedish researchers repeated Dunbar's analyses using modern statistical methods and updated data on primate brains, the results were simultaneously much larger and far lower than 150.

The average maximum group size often turned out to be lower than 150 persons. But the main problem was that the 95% confidence intervals for these estimates were between 2 and 520 people.

"It is not possible to make an estimate for humans with any precision using available methods and data," says Andreas Wartel, co-author of the study.

Dunbar's number' is often cited and has had a great impact in popular culture, not the least after featuring prominently in Malcolm Gladwell's book "The Tipping Point." In 2007, Swedish media reported that the Swedish Tax Authority reorganized their offices to stay within the 150-person limit.

"This reorganization would then be based on the implicit but hopefully unintended assumption that their employees have neither family nor friends outside of work," says Patrik Lindenfors and adds, "I think Dunbar's number is widely spread, also among researchers, since it's so easy to understand. Our claim that it is not possible to calculate a number is not quite as entertaining"

Ideas such as Dunbar's number highlight questions about the long reach of the gene.

Read more at Science Daily

Our immune systems blanket the SARS-CoV-2 spike protein with antibodies

 The most complete picture yet is coming into focus of how antibodies produced in people who effectively fight off SARS-CoV-2 work to neutralize the part of the virus responsible for causing infection. In the journal Science, researchers at The University of Texas at Austin describe the finding, which represents good news for designing the next generation of vaccines to protect against variants of the virus or future emerging coronaviruses.

Previous research focused on one group of antibodies that target the most obvious part of the coronavirus's spike protein, called the receptor-binding domain (RBD). Because the RBD is the part of the spike that attaches directly to human cells and enables the virus to infect them, it was rightly assumed to be a primary target of the immune system. But, testing blood plasma samples from four people who recovered from SARS-CoV-2 infections, the researchers found that most of the antibodies circulating in the blood -- on average, about 84% -- target areas of the viral spike protein outside the RBD -- and, apparently, for good reason.

"We found these antibodies are painting the entire spike, both the arc and the stalk of the spike protein, which looks a bit like an umbrella," said co-corresponding author Greg Ippolito, who is a research associate professor in UT Austin's Department of Molecular Biosciences and an assistant professor of oncology at the university's Dell Medical School. "The immune system sees the entire spike and tries to neutralize it."

Many of these non-RBD-directed antibodies the team identified act as a potent weapon against the virus by targeting a region in a part of the spike protein located in what would be the umbrella's canopy called the N-terminal domain (NTD). These antibodies neutralize the virus in cell cultures and were shown to prevent a lethal mouse-adapted version of the virus from infecting mice.

The NTD is also a part of the viral spike protein that mutates frequently, especially in several variants of concern. This suggests that one reason these variants are so effective at evading our immune systems is that they can mutate around one of the most common and potent types of antibody in our arsenals.

"There's an evolutionary arms race going on between the virus and our immune systems," said Jason Lavinder, research associate in the McKetta Department of Chemical Engineering and co-corresponding author of the new study. "We're all developing a standard immune response to this virus that includes targeting this one spot and that's exerting selective pressure on the virus. But then the virus is also exerting its evolutionary strength by trying to change around our selective immune pressures."

Despite these maneuvers by SARS-CoV-2, the researchers said about 40% of the circulating antibodies target the stalk of the spike protein, called the S2 subunit, which is also a part that the virus does not seem able to change easily.

"That's reassuring," Ippolito said. "That's an advantage our immune system has. It also means our current vaccines are eliciting antibodies targeting that S2 subunit, which are likely providing another layer of protection against the virus."

That's also good news for designing vaccine boosters or next-generation vaccines against variants of concern, and even for developing a vaccine that can protect against future pandemics from other strains of the coronavirus.

"It means we have a strong rationale for developing next-generation SARS-CoV-2 vaccines or even a pan-coronavirus vaccine that targets every strain," Ippolito said.

UT Austin researchers are among several in the world now aiming to develop a single coronavirus vaccine to fight infection from all coronaviruses, not just SARS-CoV-2.

The first author of the study is William Voss, a graduate student at UT Austin. In addition to Lavinder and Ippolito, senior authors from UT Austin are Jimmy Gollihar, Ilya Finkelstein, Brent Iverson, Jason McLellan and George Georgiou. Georgiou and Ippolito are also affiliated with UT Austin's Dell Medical School. Gollihar is also affiliated with the Army Research Laboratory South.

Read more at Science Daily

Hubble watches how a giant planet grows

 NASA's Hubble Space Telescope is giving astronomers a rare look at a Jupiter-sized, still-forming planet that is feeding off material surrounding a young star.

"We just don't know very much about how giant planets grow," said Brendan Bowler of the University of Texas at Austin. "This planetary system gives us the first opportunity to witness material falling onto a planet. Our results open up a new area for this research."

Though over 4,000 exoplanets have been cataloged so far, only about 15 have been directly imaged to date by telescopes. And the planets are so far away and small, they are simply dots in the best photos. The team's fresh technique for using Hubble to directly image this planet paves a new route for further exoplanet research, especially during a planet's formative years.

This huge exoplanet, designated PDS 70b, orbits the orange dwarf star PDS 70, which is already known to have two actively forming planets inside a huge disk of dust and gas encircling the star. The system is located 370 light-years from Earth in the constellation Centaurus.

"This system is so exciting because we can witness the formation of a planet," said Yifan Zhou, also of the University of Texas at Austin. "This is the youngest bona fide planet Hubble has ever directly imaged." At a youthful five million years, the planet is still gathering material and building up mass.

Hubble's ultraviolet light (UV) sensitivity offers a unique look at radiation from extremely hot gas falling onto the planet. "Hubble's observations allowed us to estimate how fast the planet is gaining mass," added Zhou.

The UV observations, which add to the body of research about this planet, allowed the team to directly measure the planet's mass growth rate for the first time. The remote world has already bulked up to five times the mass of Jupiter over a period of about five million years. The present measured accretion rate has dwindled to the point where, if the rate remained steady for another million years, the planet would only increase by approximately an additional 1/100th of a Jupiter-mass.

Zhou and Bowler emphasize that these observations are a single snapshot in time -- more data are required to determine if the rate at which the planet is adding mass is increasing or decreasing. "Our measurements suggest that the planet is in the tail end of its formation process."

The youthful PDS 70 system is filled with a primordial gas-and-dust disk that provides fuel to feed the growth of planets throughout the entire system. The planet PDS 70b is encircled by its own gas-and-dust disk that's siphoning material from the vastly larger circumstellar disk. The researchers hypothesize that magnetic field lines extend from its circumplanetary disk down to the exoplanet's atmosphere and are funneling material onto the planet's surface.

"If this material follows columns from the disk onto the planet, it would cause local hot spots," Zhou explained. "These hot spots could be at least 10 times hotter than the temperature of the planet." These hot patches were found to glow fiercely in UV light.

These observations offer insights into how gas giant planets formed around our Sun 4.6 billion years ago. Jupiter may have bulked up on a surrounding disk of infalling material. Its major moons would have also formed from leftovers in that disk.

A challenge to the team was overcoming the glare of the parent star. PDS 70b orbits at approximately the same distance as Uranus does from the Sun, but its star is more than 3,000 times brighter than the planet at UV wavelengths. As Zhou processed the images, he very carefully removed the star's glare to leave behind only light emitted by the planet. In doing so, he improved the limit of how close a planet can be to its star in Hubble observations by a factor of five.

Read more at Science Daily

Was North America populated by 'stepping stone' migration across Bering Sea?

Ice agFor thousands of years during the last ice age, generations of maritime migrants paddled skin boats eastward across shallow ocean waters from Asia to present-day Alaska. They voyaged from island to island and ultimately to shore, surviving on bountiful seaweeds, fish, shellfish, birds and game harvested from coastal and nearshore biomes. Their island-rich route was possible due to a shifting archipelago that stretched almost 900 miles from one continent to the other.

A new study from the University of Kansas in partnership with universities in Bologna and Urbino, Italy, documents the newly named Bering Transitory Archipelago and then points to how, when and where the first Americans may have crossed. The authors' stepping-stones hypothesis depends on scores of islands that emerged during the last ice age as sea level fell when ocean waters were locked in glaciers and later rose when ice sheets melted. The two-part study, just published in the open-access journal Comptes Rendus Geoscience, may answer what writer Fen Montaigne calls "one of the greatest mysteries of our time . . . when humans made the first bold journey to the Americas."

The "stepping-stones" idea hinges on retrospective mapping of sea levels while accounting for isostacy -- deformation of the Earth's crust due to the changing depth and weight of ice and water, reaching its greatest extreme during the Last Glacial Maximum about 20,500 years ago.

"We digitally discovered a geographic feature of considerable size that had never been properly documented in scientific literature," said principal author Jerome Dobson, professor emeritus of geography at KU. "We named it the Bering Transitory Archipelago; it existed from about 30,000 years ago through 8,000 years ago. When we saw it, we immediately thought, 'Wow, maybe that's how the first Americans came across.' And, in fact, everything we've tested seems to bear that out -- it does seem to be true."

For more than a decade, researchers have pondered a mystery within a mystery. Mitochondrial DNA indicates that migrants were isolated somewhere for up to 15,000 years on their way over from Asia to North America. The Beringian Standstill Hypothesis arises from the fact that today Native American DNA is quite different from Asian DNA, a clear indication of genetic drift of such magnitude that it can only have happened over long periods of time in nearly complete isolation from the Asian source population. The Bering Transitory Archipelago provides a suitable refugium with internal connectivity and outward isolation.

Dobson said people crossing the Bering Sea probably didn't have sails but could have been experienced in paddling skin boats like the kayaks and umiaks that Inuits use today.

"They probably traveled in small groups," he said, "either from Asia or islands off the coast of Asia. Some maritime people are known to have existed 27,000 years ago on northern Japanese islands. They probably were maritime people -- not just living on islands, but actually practicing maritime culture, economy and travel."

Dobson recently received the American Geographical Society's Cullum Geographical Medal (the same gold medal that Neil Armstrong won for flying to the moon and Rachel Carson won for writing "Silent Spring"). He named and continuously champions "aquaterra" -- all lands that were exposed and inundated repeatedly during the Late Pleistocene ice ages -- thus creating a zone of archeological promise scattered offshore from all coastal regions around the globe.

Recently, Dobson and co-authors Giorgio Spada of the University of Bologna and Gaia Galassi of Urbino University "Carlo Bo" applied an improved Glacial Isostatic Adjustment model to nine global choke points, meaning isthmuses and straits that have funneled transport and trade throughout history. Significant human migrations are known to have occurred across some of them, including "Beringia" -- all portions of the Bering Sea that were exposed before, during and after the Last Glacial Maximum.

"These Italian ocean scientists read my 'Aquaterra' paper and took it upon themselves to refine the boundaries of aquaterra for the whole world at coarse resolution and for Beringia itself at fine resolution," Dobson said. "Later we agreed to join forces and tackle those nine global choke points. At the end of that study, we suddenly spotted these islands in the Bering Sea, and that became our focus. This had an immediate potential because it could be a real game-changer in terms of all sciences understanding how migration worked in the past. We found startling results in certain other choke points and have begun analyzing them as well."

In Beringia, the three investigators contend, this action produced a "conveyor belt" of islands that rose from the sea and fell back again, pushing bands of people eastward. "The first islands to appear were just off the coast of Siberia," the KU researcher said. "Then islands appeared ever eastward. Most likely migrants kept expanding eastward, too, generally to islands within view and an easy paddle away."

By 10,500 years ago, when the Bering Strait itself first appeared, almost all islands in the west had submerged. Only three islands remained, and paddling distances had increased accordingly. Thus, occupants were forced to evacuate, and they faced a clear choice: return to Asia, which they knew to be populated and may even have left due to population pressures and resource constraints, or paddle east to less known territory, perhaps less populated islands with ample resources.

To fully confirm the idea set forth in the new paper, Dobson said researchers from many fields will need to collaborate as one geographer and two ocean scientists have done here.

Read more at Science Daily

Global glacier retreat has accelerated

 An international research team including scientists from ETH Zurich has shown that almost all the world's glaciers are becoming thinner and losing mass' and that these changes are picking up pace. The team's analysis is the most comprehensive and accurate of its kind to date.

Glaciers are a sensitive indicator of climate change -- and one that can be easily observed. Regardless of altitude or latitude, glaciers have been melting at a high rate since the mid-20th century. Until now, however, the full extent of ice loss has only been partially measured and understood. Now an international research team led by ETH Zurich and the University of Toulouse has authored a comprehensive study on global glacier retreat, which was published online in Nature on 28 April. This is the first study to include all the world's glaciers -- around 220,000 in total -- excluding the Greenland and Antarctic ice sheets. The study's spatial and temporal resolution is unprecedented -- and shows how rapidly glaciers have lost thickness and mass over the past two decades.

Rising sea levels and water scarcity What was once permanent ice has declined in volume almost everywhere around the globe. Between 2000 and 2019, the world's glaciers lost a total of 267 gigatonnes (billion tonnes) of ice per year on average -- an amount that could have submerged the entire surface area of Switzerland under six metres of water every year. The loss of glacial mass also accelerated sharply during this period. Between 2000 and 2004, glaciers lost 227 gigatonnes of ice per year, but between 2015 and 2019, the lost mass amounted to 298 gigatonnes annually. Glacial melt caused up to 21 percent of the observed rise in sea levels during this period -- some 0.74 millimetres a year. Nearly half of the rise in sea levels is attributable to the thermal expansion of water as it heats up, with meltwaters from the Greenland and Antarctic ice sheets and changes in terrestrial water storage accounting for the remaining third.

Among the fastest melting glaciers are those in Alaska, Iceland and the Alps. The situation is also having a profound effect on mountain glaciers in the Pamir mountains, the Hindu Kush and the Himalayas. "The situation in the Himalayas is particularly worrying," explains Romain Hugonnet, lead author of the study and researcher at ETH Zurich and the University of Toulouse. "During the dry season, glacial meltwater is an important source that feeds major waterways such as the Ganges, Brahmaputra and Indus rivers. Right now, this increased melting acts as a buffer for people living in the region, but if Himalayan glacier shrinkage keeps accelerating, populous countries like India and Bangladesh could face water or food shortages in a few decades." The findings of this study can improve hydrological models and be used to make more accurate predictions on a global and local scales -- for instance, to estimate how much Himalayan glacier meltwater one can anticipate over the next few decades.

To their surprise, the researchers also identified areas where melt rates slowed between 2000 and 2019, such as on Greenland's east coast and in Iceland and Scandinavia. They attribute this divergent pattern to a weather anomaly in the North Atlantic that caused higher precipitation and lower temperatures between 2010 and 2019, thereby slowing ice loss. The researchers also discovered that the phenomenon known as the Karakoram anomaly is disappearing. Prior to 2010, glaciers in the Karakoram mountain range were stable -- and in some cases, even growing. However, the researchers' analysis revealed that Karakoram glaciers are now losing mass as well.

Study based on stereo satellite images As a basis for the study, the research team used imagery captured on board NASA's Terra satellite, which has been orbiting the Earth once every 100 minutes since 1999 at an altitude of nearly 700 kilometres. Terra is home to ASTER, a multispectral imager with two cameras that record pairs of stereo images, allowing researchers to create high-resolution digital elevation models of all the world's glaciers. The team used the full archive of ASTER images to reconstruct a time series of glacial elevation, which enabled them to calculate changes in the thickness and mass of the ice over time.

Lead author Romain Hugonnet is a doctoral student at ETH Zurich and the University of Toulouse. He worked on this project for nearly three years and spent 18 months analysing the satellite data. To process the data, the researchers used a supercomputer at the University of Northern British Columbia. Their findings will be included in the next Assessment Report of the United Nations Intergovernmental Panel on Climate Change (IPCC), which is due to be published later this year. "Our findings are important on a political level. The world really needs to act now to prevent the worst-case climate change scenario," says co-author Daniel Farinotti, head of the glaciology group at ETH Zurich and the Swiss Federal Institute for Forest, Snow and Landscape Research WSL.

Read more at Science Daily

Greta Thunberg and Fridays For Future, from global myth to local mobilization

In 2019 the climate movement experienced an unprecedented growth in its mobilization capacity and its political and media impact. The success of the movement is closely linked to the figure of Greta Thunberg and the global impact of her discourse and the "Fridays for Future" movement in hundreds of cities around the world.

A study by Silvia Díaz-Pérez, Roger Soler-i-Martí and Mariona Ferrer-Fons, members of the UPF JOVIS research group of the Department of Communication, analyses the activist's speeches and messages on social networks and their legitimization through her personal story, and it also looks into the "Fridays for Future" movement in Barcelona, based on Twitter and Instagram posts. The research was based on a project that has received funding from UPF's Planetary Wellbeing call.

Greta Thunberg creates a framework for collective action that is present in her speeches and posts on social networks and has great strength and a great impact

"What it analyses, therefore the article is how Greta Thunberg creates a framework for collective action that is present in her speeches and posts on social networks and has great strength and a great impact because it is accompanied by a personal story that follows the monomyth structure," Roger Soler-Martí explains. In mythology and art, the monomyth takes the shape of the archetypal journey of the hero who achieves such status by overcoming dangers and adventures after a calling or suffering an event that takes him from an ordinary world to a mythical world.

"Fridays for Future," an international, principally student movement that protests to demand action against global warming and climate change, gained momentum when the activist Greta Thunberg began to demonstrate in front of Swedish Parliament, in August 2018. The "Fridays for Future" movement, despite its diversity, serves Greta Thunberg as an agent of mobilization and resonance.

The "Fridays for Future" movement, despite its diversity, serves as an agent of mobilization and resonance in the activist's frame

The authors studied how Thunberg's global frame is incorporated locally, for which they focused on the case of "Fridays for Future" in Barcelona via Twitter and Instagram content from its creation (February 2019) until the outbreak of the covid-19 pandemic.

The results show a clear influence of the activist in the discourse of local movements and among their followers. As Soler-i-Martí, co-author of the work explains, "despite the rejection of personalist leaderships and despite the particular characteristics of the local group, the activist's global framework is very present in the discourse broadcast on "Fridays for Future" Barcelona social networks."

The construction of the frames in social movements arise from two-way dialogue between the global and the local dimensions

And Soler-i-Martí adds, "In addition, the study reveals how the experience of local groups of the movement also influenced the evolution of Thunberg's discourse, which has changed over time, incorporating new actors and strategies. This element highlights how the construction of the frames in social movements arise from two-way dialogue between the global and the local dimensions."

The analysis provides empirical evidence of the importance of global and local dynamics in social movements on the Internet and highlights that the use of the basic elements of Thunberg's frame lead messages from the local "Fridays for Future" Barcelona movement to have a greater impact on social networks among its followers.

Read more at Science Daily

Equipping crop plants for climate change

Biologists at Ludwig-Maximilians-Universitaet (LMU in Munich) have significantly enhanced the tolerance of blue-green algae to high light levels -- with the aid of artificial evolution in the laboratory.

Sunlight, air and water are all that cyanobacteria (more commonly known as blue-green algae), true algae and plants need for the production of organic (i.e. carbon-based) compounds and molecular oxygen by means of photosynthesis. Photosynthesis is the major source of building blocks for organisms on Earth. However, too much sunlight reduces the efficiency of photosynthesis because it damages the 'solar panels', i.e. the photosynthetic machineries of cyanobacteria, algae and plants. A team of researchers led by LMU biologist Dario Leister has now used "artificial laboratory evolution" to identify mutations that enable unicellular cyanobacteria to tolerate high levels of light. The long-term aim of the project is to find ways of endowing crop plants with the ability to cope with the effects of climate change.

The cyanobacteria used in the study were derived from a strain of cells that were used to grow at low levels of light. "To enable them to emerge from the shadows, so to speak, we exposed these cells to successively higher light intensities," says Leister. In an evolutionary process based on mutation and selection, the cells adapted to the progressive alteration in lighting conditions -- and because each cell divides every few hours, the adaptation process proceeded at a far higher rate than would have been possible with green plants. To help the process along, the researchers increased the natural mutation rate by treating cells with mutagenic chemicals and irradiating them with UV light. By the end of the experiment, the surviving blue-green algae were capable of tolerating light intensities that were higher than the maximal levels that can occur on Earth under natural conditions.

To the team's surprise, most of the over 100 mutations that could be linked to increased tolerance to bright light resulted in localized changes in the structures of single proteins. "In other words, the mutations involved primarily affect the properties of specific proteins rather than altering the regulatory mechanisms that determine how much of any given protein is produced," Leister explains. As a control, the team then introduced the genes for two of the altered proteins, which affect photosynthesis in different ways, into non-adapted strains. -- And in each case, they found that the change indeed enabled the altered cells to tolerate higher light intensities than the progenitor strain.

Enhancing the tolerance of crop plants to higher or fluctuating light intensities potentially provides a means of increasing productivity, and is of particular interest against the background of ongoing global climate change. "Application of genetic engineering techniques to plant breeding has so far concentrated on quantitative change -- on making more or less of a specific protein," says Leister. "Our strategy makes qualitative change possible, allowing us to identify new protein variants with novel functions. Insofar as these variants retain their function in multicellular organisms, it should be possible to introduce them into plants."

 From Science Daily

Human behavior must be factored into climate change analyses

A new Cornell University-led study examines how temperature affects fishing behavior and catches among inland fisher households in Cambodia, with important implications for understanding climate change.

The research, which used household surveys, temperature data and statistical models, revealed that when temperatures rise, people fish less often. At the same time, the study's authors indirectly found that stocks of fish and other aquatic foods also rise with temperatures, leading to slightly larger catches each time peopled fished. Without careful analysis, it would appear that overall fish catches appear unchanged annually, when in fact, more nuanced dynamics are at play.

The study highlights why it's necessary when studying changing environmental conditions to include human behavior along with ecosystem responses; both are key variables when considering how climate change affects rural livelihoods, food production and food access.

The paper, "Fishers' Response to Temperature Change Reveals the Importance of Integrating Human Behavior in Climate Change Analysis," published April 30 in the journal Science Advances.

"This study underscores the importance of pulling human behavior into climate change modeling," said Kathryn Fiorella, an assistant professor in the Department of Population Medicine and Diagnostic Sciences and Master of Public Health Program in the College of Veterinary Medicine. "To accurately predict the impacts of climate change, we need to know about the effects on ecological systems, and also the effects on people who use them."

In the study, Fiorella and colleagues used data provided by partner organization WorldFish, which collected survey data every two months over three years for households in Cambodia, which has the world's highest per-capita consumption of inland fish. WorldFish collected information on how often people fished, how much time they spent when they fished, and what method they used.

The researchers used remotely sensed temperature data over the same three-year period, which revealed a range of 24 to 31 degrees Celsius (75 to 88 degrees Fahrenheit). The researchers also controlled for rainfall and flooding.

"The temperatures in the range of the study compare to regional climate projections in the area, which suggest around a 1.5 to 2.5 degrees Celsius [2.7 to 4.5 F] temperature rise above the average of 28 degrees Celsius [82.4 F]," Fiorella said. "What we observed is in range for what we might expect under climate change scenarios."

The researchers found time spent fishing per outing and the gear choices were not affected by temperature, but fewer people fished as temperatures rose.

They also analyzed fish catch. It turns out that, with effort holding constant, fish catch per outing went up as temperatures rose, which meant the ecosystem became a little more productive when it was warmer. The same pattern was true for other aquatic animals, like frogs or snakes, and aquatic plants. However, without factoring in effects of temperature on human behavior, it might have looked like temperature had no effect.

The researchers suspect that fishing frequency declined as temperatures rose due to competing interests. "These households have a suite of different activities they are engaged in at the same time," Fiorella said, noting many of them are rice farmers or run small businesses. At the same time, heat may also be a factor, she added.

Fiorella added that large swaths of the population migrate to cities or nearby countries for work, and these dynamics could be pulling them away from fishing.

"Ultimately," she said, "understanding both ecosystem responses and people's responses to temperature is going to be fundamental to understanding how climate change affects people who are directly reliant on the natural resources for their food and income."

Read more at Science Daily

Natural immunity to malaria provides clues to potential therapies

WEHI researchers have identified how natural human antibodies can block malaria parasites from entering red blood cells, potentially indicating how new protective therapies could be developed against this globally significant disease.

The research provides greater insight into how antibodies block the entry of Plasmodium vivax malaria parasites into young red blood cells called reticulocytes. It builds on an earlier discovery that the P. vivax latches onto the transferrin receptor 1 (TfR1) to enter cells.

The research, led by Associate Professor Wai-Hong Tham and PhD student Li-Jin Chan from WEHI, alongside Professor Christopher King from Case Western University, US, was published in Nature Communications.

At a glance
 

• By examining antibodies from people with a history of malaria infection, researchers observed that naturally occurring antibodies can block Plasmodium vivax from latching onto transferrin receptor 1 on reticulocytes.
• One way the antibodies work is by preventing parasite proteins from getting close enough to the cell to allow parasite entry.
• The discovery opens up new avenues for developing antibody-based therapies for malaria.
   
• Shedding light on pathogen-blocking antibodies
   
• Plasmodium vivax is the most widespread malaria parasite in the world, and the predominant cause of malaria in the vast majority of countries outside Africa. It is also the main parasite responsible for recurrent malaria infections.

The malaria parasite is a complex single-celled organism, with diverse proteins that help it to invade red blood cells, reproduce and spread. Adhesins on the surface of the parasite are key-like proteins that 'unlock' cells, allowing the parasite to enter.

Previous research studies in Papua New Guinea, Thailand and Brazil showed antibodies against P. vivax adhesins were correlated with protection against infection and disease, Associate Professor Tham said.

"We wanted to understand how these human antibodies in natural infection block the parasite from getting in. By extracting and examining antibodies from people who have had P. vivax infections, we identified the different ways human antibodies against P. vivax work. One of these ways, is by stopping the parasite adhesins from getting too close to the reticulocyte membrane, denying the parasite entry," she said.

This discovery opens the door to potentially preventing not only P. vivax malaria, but also P. falciparum malaria, another significant cause of deaths globally.

"Although this was a vivax study, we believe the implications are that a broadly neutralising antibody could be created to target both P. vivax and P. falciparum malaria infections," Associate Professor Tham said.

Improving detection of relapsing malaria

WEHI Professor Ivo Mueller said beyond understanding how antibodies can block infection, there was also a crucial need to understand the development of immunity and how this could be used to detect P. vivax infections in endemic populations.

"We are currently using this information to develop diagnostic tests that will be used in the field to identify and treat people with hidden vivax infection in their livers and spleens. This is a key step towards eliminating malaria, by preventing silently infected people reinfecting their communities," he said.

Read more at Science Daily

Genetics, not the intrauterine environment, controls abnormal development

Yale researchers have shown that developmental abnormalities, including those that lead to pregnancy loss and autism, are controlled by the genetics of the fetus and placenta -- and not the mother's intrauterine environment.

The findings are reported in the April 28 online edition of the journal Placenta.

One out of every 33 children is diagnosed with a birth defect each year in the United States, according to the Centers for Disease Control and Prevention (CDC). This translates into one baby born every 4 ½ minutes -- or 120,000 per year.

"Mothers often feel that they are responsible for these defects. But it's not their fault," said senior author Dr. Harvey Kliman, a research scientist in the Department of Obstetrics, Gynecology & Reproductive Services at the Yale School of Medicine. "This new research points to the genetics of these children as being the most important cause."

For the study, Kliman's team examined placental data for nearly 50 sets of identical and non-identical twins. The researchers found that abnormal cell growths called trophoblast inclusions (TIs) which are markers for many developmental abnormalities, occurred with similar frequency in identical twins, while non-identical twins showed a markedly different TI count.

Identical twins share the same DNA sequence; non-identical twins share half of their DNA sequence. The researchers found that identical twins often had the same number of TIs or were within one of having the same TI count. Non-identical twins had TI counts that were, on average, different by four or five.

"This work suggests that developmental abnormalities are much more likely to be due to the genetics of the child, and not the mother's fault," Kliman said.

Lead author Julia Katz, a former Yale undergraduate who is now a medical student at Hofstra University, provided the inspiration for the study.

Katz and her brother, Jesse, who was born underweight and with several congenital abnormalities, are non-identical twins. "I had a lot of guilt, growing up, about why my twin had certain conditions that I didn't," Katz said. "I think mothers also tend to blame themselves."

Katz approached Kliman after a Yale lecture and asked him what causes babies to be born undersized. The conversation led to a discussion about developmental abnormalities and Katz's desire to seek out information about her and her twin's genetics -- including looking at her own placental slides from birth.

It also led Kliman, Katz, and co-author Parker Holzer, a graduate student in the Yale Department of Statistics and Data Science, to conduct the new study.

"Julia's need to resolve this burden is what propelled our study," Kliman said. "Hopefully, this finding will help many other people, as well."

Read more at Science Daily

Not just for finding planets: Exoplanet-hunter TESS telescope spots bright gamma-ray burst

NASA has a long tradition of unexpected discoveries, and the space program's TESS mission is no different. SMU astrophysicist and her team have discovered a particularly bright gamma-ray burst using a NASA telescope designed to find exoplanets -- those occurring outside our solar system -- particularly those that might be able to support life.

It's the first time a gamma-ray burst has been found this way.

Gamma-ray bursts are the brightest explosions in the universe, typically associated with the collapse of a massive star and the birth of a black hole. They can produce as much radioactive energy as the sun will release during its entire 10-billion-year existence.

Krista Lynne Smith, an assistant professor of physics at Southern Methodist University, and her team confirmed the blast -- called GRB 191016A -- happened on Oct. 16 and also determined its location and duration. A study on the discovery has been published in The Astrophysical Journal.

"Our findings prove this TESS telescope is useful not just for finding new planets, but also for high-energy astrophysics," said Smith, who specializes in using satellites like TESS (Transiting Exoplanet Survey Satellite) to study supermassive black holes and gas that surrounds them. Such studies shed light on the behavior of matter in the deeply warped spacetime around black holes and the processes by which black holes emit powerful jets into their host galaxies.

Smith calculated that GRB 191016A had a peak magnitude of 15.1, which means it was 10,000 times fainter than the faintest stars we can see with the naked eyes.

That may sound quite dim, but the faintness has to do with how far away the burst occurred. It is estimated that light from GRB 191016A's galaxy had been travelling 11.7 billion years before becoming visible in the TESS telescope.

Most gamma ray bursts are dimmer -- closer to 160,000 times fainter than the faintest stars.

The burst reached its peak brightness sometime between 1,000 and 2,600 seconds, then faded gradually until it fell below the ability of TESS to detect it some 7000 seconds after it first went off.

This gamma-ray burst was first detected by a NASA's satellite called Swift-BAT, which was built to find these bursts. But because GRB 191016A occurred too close to the moon, the Swift-BAT couldn't do the necessary follow-up it normally would have to learn more about it until hours later.

NASA's TESS happened to be looking at that same part of the sky. That was sheer luck, as TESS turns its attention to a new strip of the sky every month.

While exoplanet researchers at a ground-base for TESS could tell right away that a gamma-ray burst had happened, it would be months before they got any data from the TESS satellite on it. But since their focus was on new planets, these researchers asked if any other scientists at a TESS conference in Sydney, Australia were interested in doing more digging on the blast.

Smith was one of the few high-energy astrophysics specialists there at that time and quickly volunteered.

"The TESS satellite has a lot of potential for high-energy applications, and this was too good an example to pass up," she said. High-energy astrophysics studies the behavior of matter and energy in extreme environments, including the regions around black holes, powerful relativistic jets, and explosions like gamma-ray bursts.

TESS is an optical telescope that collects light curves on everything in its field of view, every half hour. Light curves are a graph of light intensity of a celestial object or region as a function of time. Smith analyzed three of these light curves to be able to determine how bright the burst was.

She also used data from ground-based observatories and the Swift gamma-ray satellite to determine the burst's distance and other qualities about it.

Read more at Science Daily

Risk of developmental difficulties remains high among children born early

 Children born preterm (before 37 weeks of pregnancy) remain at high risk of developmental difficulties that can affect their behaviour and ability to learn, finds a study published by The BMJ today.

These difficulties were found not only in children born extremely preterm (22-26 weeks) but also in those born very and moderately preterm (between 27 and 34 weeks), say researchers.

Survival of preterm babies has increased worldwide. Children born early often have developmental issues, but studies have mainly focused on those born extremely preterm (22-26 weeks' gestation) and less is known about children born very and moderately preterm (27-34 weeks' gestation).

Given how important it is to identify children most at risk of developmental difficulties, researchers in France set out to describe neurodevelopment among children born before 35 weeks compared with children born at full term.

Their findings are based on 3,083 French children aged 5½ born after 24-26, 27-31, and 32-34 weeks gestation who were taking part in the EPIPAGE-2 study (designed to investigate outcomes of preterm children over the past 15 years) and a comparison group of 600 children born at full term.

Neurodevelopmental outcomes such as cerebral palsy, sensory impairments (blindness and deafness), and brain function (cognition), as well as behavioural difficulties and movement disorders, were assessed using recognised tests.

To further assess the family and social burden of prematurity, measures such as the need for extra support at school, visits to a psychiatrist, speech therapist or physiotherapist, and parental concerns about development, were also recorded.

After adjusting for other potentially influential factors, the researchers found that rates of neurodevelopmental disabilities increased as gestational age decreased.

For example, among the 3,083 children assessed, rates of severe to moderate neurodevelopmental disabilities were 28%, 19% and 12% and rates of mild disabilities were 39%, 36%, and 34% among children born at 24-26, 27-31 and 32-34 weeks, respectively.

Assistance at school was used by 27%, 14% and 7% of children born at 24-26, 27-31, and 32-34 weeks, respectively. And about half of children born at 24-26 weeks received at least one developmental intervention which fell to 26% for those born at 32-34 weeks.

Behaviour was the concern most commonly reported by parents.

Rates of neurodevelopmental disabilities were also higher in families with low socioeconomic status.

This is an observational study, so can't establish cause, and the researchers point to some limitations that may have affected their results. However, by assessing a wide range of developmental and behavioural issues, they were better able to reflect the complexity of difficulties faced by these children and their families.

As such, they say their findings indicate that preterm birth "continues to pose a large burden for families, healthcare, and educational systems."

Although rates of severe to moderate neurodevelopmental disabilities decreased with increasing gestational age, they point out that around 35% of the moderately to extremely preterm born children had mild disabilities requiring special care or educational services.

And a considerable proportion of parents had concerns about their child's development, particularly about behaviour, which warrant attention, they add.

Read more at Science Daily