New research reveals secret to Jupiter's curious aurora activity

 Auroral displays continue to intrigue scientists, whether the bright lights shine over Earth or over another planet. The lights hold clues to the makeup of a planet's magnetic field and how that field operates.

New research about Jupiter proves that point -- and adds to the intrigue.

Peter Delamere, a professor of space physics at the University of Alaska Fairbanks Geophysical Institute, is among an international team of 13 researchers who have made a key discovery related to the aurora of our solar system's largest planet.

The team's work was published April 9, 2021, in the journal Science Advances. The research paper, titled "How Jupiter's unusual magnetospheric topology structures its aurora," was written by Binzheng Zhang of the Department of Earth Sciences at the University of Hong Kong; Delamere is the primary co-author.

Research done with a newly developed global magnetohydrodynamic model of Jupiter's magnetosphere provides evidence in support of a previously controversial and criticized idea that Delamere and researcher Fran Bagenal of the University of Colorado at Boulder put forward in a 2010 paper -- that Jupiter's polar cap is threaded in part with closed magnetic field lines rather than entirely with open magnetic field lines, as is the case with most other planets in our solar system.

"We as a community tend to polarize -- either open or closed -- and couldn't imagine a solution where it was a little of both," said Delamere, who has been studying Jupiter since 2000. "Yet in hindsight, that is exactly what the aurora was revealing to us."

Open lines are those that emanate from a planet but trail off into space away from the sun instead of reconnecting with a corresponding location in the opposite hemisphere.

On Earth, for example, the aurora appears on closed field lines around an area referred to as the auroral oval. It's the high latitude ring near -- but not at -- each end of Earth's magnetic axis.

Within that ring on Earth, however, and as with some other planets in our solar system, is an empty spot referred to as the polar cap. It's a place where magnetic field lines stream out unconnected -- and where the aurorae rarely appear because of it. Think of it like an incomplete electrical circuit in your home: No complete circuit, no lights.

Jupiter, however, has a polar cap in which the aurora dazzles. That puzzled scientists.

The problem, Delamere said, is that researchers were so Earth-centric in their thinking about Jupiter because of what they had learned about Earth's own magnetic fields.

The arrival at Jupiter of NASA's Juno spacecraft in July 2016 provided images of the polar cap and aurora. But those images, along with some captured by the Hubble Space Telescope, couldn't resolve the disagreement among scientists about open lines versus closed lines.

So Delamere and the rest of the research team used computer modeling for help. Their research revealed a largely closed polar region with a small crescent-shaped area of open flux, accounting for only about 9 percent of the polar cap region. The rest was active with aurora, signifying closed magnetic field lines.

Jupiter, it turns out, possesses a mix of open and closed lines in its polar caps.

"There was no model or no understanding to explain how you could have a crescent of open flux like this simulation is producing," he said. "It just never even entered my mind. I don't think anybody in the community could have imagined this solution. Yet this simulation has produced it."

"To me, this is a major paradigm shift for the way that we understand magnetospheres."

What else does this reveal? More work for researchers.

"It raises many questions about how the solar wind interacts with Jupiter's magnetosphere and influences the dynamics," Delamere said.

Jupiter's aurorally active polar cap could, for example, be due to the rapidity of the planet's rotation -- once every 10 hours compared to Earth's once every 24 hours -- and the enormity of its magnetosphere. Both reduce the impact of the solar wind, meaning the polar cap magnetic field lines are less likely to be torn apart to become open lines.

And to what extent does Jupiter's moon Io affect the magnetic lines within Jupiter's polar cap? Io is electrodynamically linked to Jupiter, something unique in our solar system, and as such is constantly stripped of heavy ions by its parent planet.

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Discovery could help lengthen lifespan of electronic devices

Ferroelectric materials are used in many devices, including memories, capacitors, actuators and sensors. These devices are commonly used in both consumer and industrial instruments, such as computers, medical ultrasound equipment and underwater sonars.

Over time, ferroelectric materials are subjected to repeated mechanical and electrical loading, leading to a progressive decrease in their functionality, ultimately resulting in failure. This process is referred to as 'ferroelectric fatigue'.

It is a main cause of the failure of a range of electronic devices, with discarded electronics a leading contributor to e-waste. Globally, tens of millions of tonnes of failed electronic devices go to landfill every year.

Using advanced in-situ electron microscopy, the School of Aerospace, Mechanical and Mechatronic Engineering researchers were able to observe ferroelectric fatigue as it occurred. This technique uses an advanced microscope to 'see', in real-time, down to the nanoscale and atomic levels.

The researchers hope this new observation, described in a paper published in Nature Communications, will help better inform the future design of ferroelectric nanodevices.

"Our discovery is a significant scientific breakthrough as it shows a clear picture of how the ferroelectric degradation process is present at the nanoscale," said co-author Professor Xiaozhou Liao, also from the University of Sydney Nano Institute.

Dr Qianwei Huang, the study's lead researcher, said: "Although it has long been known that ferroelectric fatigue can shorten the lifespan of electronic devices, how it occurs has previously not been well understood, due to a lack of suitable technology to observe it."

Co-author Dr Zibin Chen said: "With this, we hope to better inform the engineering of devices with longer lifespans."

Observational findings spark new debate

Nobel laureate Herbert Kroemer once famously asserted "The interface is the device." The observations by the Sydney researchers could therefore spark a new debate on whether interfaces -- which are physical boundaries separating different regions in materials -- are a viable solution to the unreliability of next-generation devices.

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Caught speeding: Clocking the fastest-spinning brown dwarfs

 Astronomers at Western University have discovered the most rapidly rotating brown dwarfs known. They found three brown dwarfs that each complete a full rotation roughly once every hour. That rate is so extreme that if these "failed stars" rotated any faster, they could come close to tearing themselves apart. Identified by NASA's Spitzer Space Telescope, the brown dwarfs were then studied by ground-based telescopes including Gemini North, which confirmed their surprisingly speedy rotation.

Three brown dwarfs have been discovered spinning faster than any other found before. Astronomers at Western University in Canada first measured the rotation speeds of these brown dwarfs using NASA's Spitzer Space Telescope and confirmed them with follow-up observations with the Gemini North telescope on Maunakea in Hawai'i and the Carnegie Institution for Science's Magellan Baade telescope in Chile. Gemini North is one of the pair of telescopes that make up the international Gemini Observatory, a Program of NSF's NOIRLab.

"We seem to have come across a speed limit on the rotation of brown dwarfs," said Megan Tannock, the Western University physics and astronomy graduate student who led the discovery. "Despite extensive searches, by our own team and others, no brown dwarfs have been found to rotate any faster. In fact, faster spins may lead to a brown dwarf tearing itself apart."

Brown dwarfs are, simply put, failed stars. They form like stars but are less massive and more like giant planets.

Tannock and Western University astronomer Stanimir Metchev worked with international collaborators to find three rapidly rotating brown dwarfs spinning around their axes once every hour. This is approximately 10 times faster than normal, and about 30 percent faster than the most rapid rotations previously measured in such objects.

The astronomers used large ground-based telescopes, Gemini North in Hawai'i and Magellan Baade in Chile, to confirm the rapid rotations. They did this by measuring alterations in the brown dwarfs' light caused by the Doppler effect and using a computer model to match those alterations to spin rates. The researchers found that these brown dwarfs spin with speeds of about 350,000 kilometers per hour (around 220,000 miles per hour) at their equator, which is 10 times faster than Jupiter.

"These unusual brown dwarfs are spinning at dizzying speeds," said Sandy Leggett, an astronomer at Gemini North who studies brown dwarfs. "At about 350,000 kilometers per hour, the relatively weak gravity of the brown dwarfs is barely holding them together. This exciting discovery by the Tannock team has identified rotational limits beyond which these objects may not exist."

The team first identified the rapid rotation rates by using NASA's Spitzer Space Telescope to measure how quickly the brightness of the objects varied. "Brown dwarfs, like planets with atmospheres, can have large weather storms that affect their visible brightness," explained Metchev. "The observed brightness variations show how frequently the same storms are seen as the object spins, which reveals the brown dwarf's spin period."

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Sign-language exposure impacts infants as young as 5 months old

 While it isn't surprising that infants and children love to look at people's movements and faces, recent research from Rochester Institute of Technology's National Technical Institute for the Deaf studies exactly where they look when they see someone using sign language. The research uses eye-tracking technology that offers a non-invasive and powerful tool to study cognition and language learning in pre-verbal infants.

NTID researcher and Assistant Professor Rain Bosworth and alumnus Adam Stone studied early-language knowledge in young infants and children by recording their gaze patterns as they watched a signer. The goal was to learn, just from gaze patterns alone, whether the child was from a family that used spoken language or signed language at home.

They tested two groups of hearing infants and children that differ in their home language. One "control" group had hearing parents who spoke English and never used sign language or baby signs. The other group had deaf parents who only used American Sign Language at home. Both sets of children had normal hearing in this study. The control group saw sign language for the first time in the lab, while the native signing group was familiar with sign language.

The study, published in Developmental Science, showed that the non-signing infants and children looked at areas on the signer called "signing space," in front of the torso. The hands predominantly fall in this area about 80 percent of the time when signing. However, the signing infants and children looked primarily at the face, barely looking at the hands.

According to the findings, the expert sign-watching behavior is already present by about 5 months of age.

"This is the earliest evidence, that we know of, for effects of sign-language exposure," said Bosworth. "At first, it does seem counter-intuitive that the non-signers are looking at the hands and signers are not. We think signers keep their gaze on the face because they are relying on highly developed and efficient peripheral vision. Infants who are not familiar with sign language look at the hands in signing space perhaps because that is what is perceptually salient to them."

Another possible reason why signing babies keep their gaze on the face could be because they already understand that the face is very important for social interactions, added Bosworth.

"We think the reason perceptual gaze control matures so rapidly is because it supports later language learning, which is more gradual," Bosworth said. "In other words, you have to be able to know where to look before you learn the language signal."

Bosworth says more research is needed to understand the gaze behaviors of deaf babies who are or are not exposed to sign language.

Read more at Science Daily

Masculine traits linked to better parenting for some dads

 In some men, having traditional masculine characteristics such as competitiveness and adventurousness was linked to being better fathers to infants, a new study found.

But the men in this study -- highly educated and from dual-earner couples -- combined those stereotypically masculine traits with the belief that they should be nurturing, highly involved fathers.

The researchers were surprised that traits often seen as old-fashioned male stereotypes were linked to more positive parenting behaviors, said study lead author Sarah Schoppe-Sullivan, professor of psychology at The Ohio State University.

It suggests that some men are looking for new ways to be fathers, Schoppe-Sullivan said.

"These men are combining traditional aspects of masculinity with new nurturing ideals to create new fathering identities. They may be in the midst of transforming fatherhood."

The study was published this week in the journal Psychology of Men and Masculinities.

The seven stereotypical masculine characteristics linked to positive parenting in this study -- competitive, daring, adventurous, dominant, aggressive, courageous and stands up to pressure -- are generally seen as positive traits, Schoppe-Sullivan noted.

But a negative masculine attitude that the researchers also measured in this study -- hostile sexism -- was not linked to positive parenting. In addition, the quality of fathers' parenting of their infants was unrelated to the belief that men should be primary economic providers in the family.

The men in the study were participating in the New Parents Project, a long-term study led by Schoppe-Sullivan that is investigating how dual-earner couples adjust to becoming parents for the first time.

In the third trimester of their partners' pregnancy, the expectant fathers completed a variety of questionnaires. They were asked to rate themselves on a four-point scale (not at all like me to very much like me) on the seven stereotypically masculine characteristics.

Hostile sexism was rated by asking male participants how much they agreed with 11 statements like "Feminists are making unreasonable demands of men." Participants were also asked whether men or women should provide the majority of income for the family.

Their nurturing father role beliefs were measured by asking men to rate how much they agreed with nine statements like "Men should share with child care such as bathing, feeding and dressing the child."

Nine months after the child was born, the researchers watched the fathers interact with their infants by themselves and with the mother. The researchers rated the fathers on their positive parenting behavior and on how well they co-parented together with mothers.

Results showed, as the researchers had predicted, that men who believed they should have a nurturing father role had higher-quality interactions with their child and were better at co-parenting with their partner.

But the researchers were surprised to find that the more men said they fit the stereotypical definition of "real men," the more they were also rated as showing good parenting behavior.

"The fathers who see themselves as competitive and adventurous and the other masculine traits tended to be really engaged with their kids. They were not checked out," Schoppe-Sullivan said.

It may be that men who used these traditionally masculine characteristics to succeed in their careers are trying to find ways to apply them to their jobs as parents.

"These dads may be saying that being a father is an important job, too, and I'm going to use the same traits that help me succeed at work to make me a successful father," she said.

Schoppe-Sullivan emphasized that the fathers in this sample were highly educated and had partners who also worked. The findings here may not apply to all fathers.

But the results are encouraging, she said.

Read more at Science Daily

Metabolic changes in fat tissue in obesity associated with adverse health effects

 Researchers at the Obesity Research Unit of the University of Helsinki have found that obesity clearly reduces mitochondrial gene expression in fat tissue, or adipose tissue. Mitochondria are important cellular powerplants which process all of our energy intake. If the pathways associated with breaking down nutrients are lazy, the changes can often have health-related consequences.

A total of 49 pairs of identical twins discordant for body weight participated in the study conducted at the University of Helsinki: their body composition and metabolism were studied in detail, and biopsies from adipose and muscle tissue were collected. Multiple techniques for analysing the genome-wide gene expression, the proteome and the metabolome were used in the study.

The study was recently published in the journal Cell Reports Medicine.

According to the findings, the pathways responsible for mitochondrial metabolism in adipose tissue were greatly reduced by obesity. Since mitochondria are key to cellular energy production, their reduced function can maintain obesity. For the first time, the study also compared the effects of obesity specifically on the mitochondria in muscle tissue in these identical twin pairs: muscle mitochondria too were found to be out of tune, but the change was less distinct than in adipose tissue.

The study provided strong evidence of a connection between the low performance of adipose tissue mitochondria and a proinflammatory state. Furthermore, the findings indicate that metabolic changes in adipose tissue are associated with increased accumulation of fat in the liver, prediabetic disorders of glucose and insulin metabolism as well as cholesterol.

"If mitochondria, the cellular powerplants, are compared to the engine of a car, you could say that the power output decreases as weight increases. A low-powered mitochondrial engine may also generate toxic exhaust fumes, which can cause a proinflammatory state in adipose tissue and, consequently, the onset of diseases associated with obesity," says Professor Kirsi Pietiläinen from the Obesity Research Unit, University of Helsinki.

"What was surprising was that the mitochondrial pathways in muscle had no association with these adverse health effects," Pietiläinen adds.

Obesity also affected amino acid metabolism

In the study, changes in mitochondrial function were also seen in amino acid metabolism. The metabolism of branched-chain amino acids, which are essential to humans, was weakened in the mitochondria of both adipose tissue and muscle tissue.

"This finding was of particular significance because the reduced breakdown of these amino acids and the resulting heightened concentration in blood have also been directly linked with prediabetic changes and the accumulation of liver fat in prior twin studies," says Pietiläinen.

Obesity, with its numerous associated diseases, is a common phenomenon that is continuously increasing in prevalence. While lifestyle influence the onset of obesity, genes also have a significant role.

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Dogs act jealously even when they don't see their rival

 Past surveys have shown that more than 80% of dog owners report observing jealous behaviors from their dogs -- vocalizations, agitated behavior, pulling on a leash -- when they give attention to other dogs. New research published in the journal Psychological Science supports these observations and finds that dogs also exhibit jealous behaviors when they merely imagine that their owner is interacting with a potential rival, in this case, a highly realistic artificial dog.

"Research has supported what many dog owners firmly believe -- dogs exhibit jealous behavior when their human companion interacts with a potential rival," said Amalia Bastos with the University of Auckland and lead author on the paper. "We wanted to study this behavior more fully to determine if dogs could, like humans, mentally represent a situation that evoked jealousy."

Dogs appear to be one of the few species that might display jealous behaviors in ways similar to a human child showing jealousy when their mother gives affection to another child. In humans, jealousy is closely linked with self-awareness, which is one reason animal-cognition researchers are so interested in studying jealousy and other secondary emotions in animals.

To test how and when dogs display jealous behavior, the researchers presented 18 dogs with situations where they could imagine a social interaction between their human companion and either a realistic fake dog or a fleece cylinder. The fake dog served as a potential rival for attention while the cylinder served as a control.

In the experiment, the dogs observed the fake-dog rival positioned next to their owner. A barrier was then placed between the dog and the potential rival obscuring them from view. Despite blocking the line of sight, the dogs forcefully attempted to reach their owners when they appeared to stroke the rival fake dog behind the barrier. In a repeat experiment using a fleece cylinder rather than a fake dog, the dogs pulled on the lead with far less force.

Through their study, Bastos and her colleagues found that dogs showed three human-like signatures of jealous behavior. Jealous behavior emerged only when their owner interacted with a perceived social rival and not an inanimate object; occurred as a consequence of that interaction and not due to a potential rival's mere presence; and emerged even for an out-of-sight interaction between their owner and a social rival.

"These results support claims that dogs display jealous behavior. They also provide the first evidence that dogs can mentally represent jealousy-inducing social interactions," said Bastos. "Previous studies confounded jealous behavior with play, interest, or aggression, because they never tested the dogs' reactions to the owner and the social rival being present in the same room but not interacting."

Read more at Science Daily

The truth about doublespeak: Is it lying or just being persuasive?

Doublespeak, or the use of euphemisms to sway opinion, lets leaders avoid the reputational costs of lying while still bringing people around to their way of thinking, a new study has found.

Researchers at the University of Waterloo found that the use of agreeable euphemistic terms biases people's evaluations of actions to be more favourable. For example, replacing a disagreeable term, "torture," with something more innocuous and semantically agreeable, like "enhanced interrogation."

"Like the much-studied phenomenon of 'fake news,' manipulative language can serve as a tool for misleading the public, doing so not with falsehoods but rather with the strategic use of euphemistic language," said Alexander Walker, lead author of the study and a PhD candidate in cognitive psychology at Waterloo. "The avoidance of objectively false claims may provide the strategic user of language with plausible deniability of dishonesty, thus protecting them from the reputational cost associated with lying."

As part of a series of studies investigating the effectiveness, consequences and mechanisms of doublespeak in a psychological context, the researchers investigated whether the use of language characteristic of doublespeak can be used to influence peoples' evaluations of actions.

The researchers identified doublespeak as the strategic manipulation of language to influence the opinions of others by representing the truth in a manner that benefits one's self. To do this, the researchers assessed whether substituting an agreeable term -- for example, "working at a meat-processing plant" in place of a semantically related disagreeable term like "working at a slaughterhouse" -- has an impact on how a person's actions are interpreted.

The researchers' results confirmed that peoples' evaluations of an action can be biased in a predictable, self-serving way when an individual employs the strategic use of more or less agreeable terms when describing an action.

"Our study shows how language can be used strategically to shape peoples' opinions of events or actions," Walker said. "With a lower level of risk, individuals may be able to utilize linguistic manipulation, such as doublespeak, often without correction."

From Science Daily

Corals carefully organize proteins to form rock-hard skeletons

Charles Darwin, the British naturalist who championed the theory of evolution, noted that corals form far-reaching structures, largely made of limestone, that surround tropical islands. He didn't know how they performed this feat.

Now, Rutgers scientists have shown that coral structures consist of a biomineral containing a highly organized organic mix of proteins that resembles what is in our bones. Their study, published in the Journal of the Royal Society Interface, shows for the first time that several proteins are organized spatially -- a process that's critical to forming a rock-hard coral skeleton.

"Our research revealed an intricate network of skeletal proteins that interact spatially, which likely applies to all stony corals," said Manjula P. Mummadisetti, who led the research while she was a postdoctoral associate in the Rutgers Environmental Biophysics and Molecular Ecology Laboratory led by senior author Paul G. Falkowski. She is now a senior scientist at AVMBioMed in Pottstown, Pennsylvania. "It's important to understand the mechanisms of coral biomineralization and how these invaluable animals persist during the era of anthropogenic climate change."

"Our findings suggest that corals will withstand climate change caused by human activities, based on the precision, robustness and resilience of their impressive process for forming rock-hard skeletons," said Falkowski, a Distinguished Professor in the School of Arts and Sciences and School of Environmental and Biological Sciences at Rutgers University-New Brunswick.

Coral reefs protect shorelines threatened by erosion and storms, and provide fish habitat, nursery and spawning grounds. Indeed, coral reefs provide food for about a half-billion people, who also depend on them to make a living. However, warming ocean waters from climate change put corals at risk from deadly bleaching and disease. More acidic ocean waters, sea-level rise, unsustainable fishing, vessels that damage reefs, invasive species, marine debris and tropical cyclones pose additional threats, according to the National Oceanic and Atmospheric Administration.

Rutgers scientists studied the spatial interactions of the proteins embedded within the skeleton of Stylophora pistillata, a common stony coral in the Indo-Pacific. Stony corals have evolved over more than 400 million years, forming enormous reefs in shallow subtropical and tropical seas. They've been called the "rainforests of the sea."

Predicting the survival of corals based on how they adapted to global climate change over millions of years requires understanding, among other things, how they build reefs by secreting calcium carbonate. That process is called biomineralization.

The scientists showed that several proteins work together to create optimal conditions for biomineralization. These proteins are not located randomly but are well-organized spatially, which the scientists detailed for the first time. The scientists revealed the spatial patterns as new mineral is formed between the living tissue of the animal and its base or an older skeleton.

Read more at Science Daily

Mars didn't dry up in one go

The Perseverance rover has just landed on Mars. Meanwhile, its precursor Curiosity continues to explore the base of Mount Sharp (officially Aeolis Mons), a mountain several kilometres high at the centre of the Gale crater. Using the telescope on the ChemCam instrument to make detailed observations of the steep terrain of Mount Sharp at a distance, a French-US team headed by William Rapin, CNRS researcher at the Institut de Recherche en Astrophysique et Planétologie (CNRS/Université Toulouse III/CNES), has discovered that the Martian climate recorded there alternated between dry and wetter periods, before drying up completely about 3 billion years ago.

Spacecraft in orbit around Mars had already provided clues about the mineral composition of the slopes of Mount Sharp. But now, ChemCam has successfully made detailed observations of the sedimentary beds from the planet's surface, revealing the conditions under which they formed. Moving up through the terrain observed, which is several hundred metres thick, the types of bed change radically. Lying above the lake-deposited clays that form the base of Mount Sharp, wide, tall, cross-bedded structures are a sign of the migration of wind-formed dunes during a long, dry climate episode.

Higher up still, thin alternating brittle and resistant beds are typical of river floodplain deposits, marking the return of wetter conditions. The climate of Mars therefore likely underwent several large-scale fluctuations between dry conditions and river and lake environments, until the generally arid conditions observed today took hold. During its extended mission, Curiosity is scheduled to climb the foothills of Mount Sharp and drill into its various beds. It will test this model, characterise in more details how the ancient climate evolved, and possibly understand the origin of these major fluctuations.

From Science Daily

More than 5,000 tons of extraterrestrial dust fall to Earth each year

Every year, our planet encounters dust from comets and asteroids. These interplanetary dust particles pass through our atmosphere and give rise to shooting stars. Some of them reach the ground in the form of micrometeorites. An international program conducted for nearly 20 years by scientists from the CNRS, the Université Paris-Saclay and the National museum of natural history with the support of the French polar institute, has determined that 5,200 tons per year of these micrometeorites reach the ground. The study will be available in the journal Earth & Planetary Science Letters from April 15.

Micrometeorites have always fallen on our planet. These interplanetary dust particles from comets or asteroids are particles of a few tenths to hundredths of a millimetre that have passed through the atmosphere and reached the Earth's surface.

To collect and analyse these micrometeorites, six expeditions led by CNRS researcher Jean Duprat have taken place over the last two decades near the Franco-Italian Concordia station (Dome C), which is located 1,100 kilometres off the coast of Adélie Land, in the heart of Antarctica. Dome C is an ideal collection spot due to the low accumulation rate of snow and the near absence of terrestrial dust.

These expeditions have collected enough extraterrestrial particles (ranging from 30 to 200 micrometres in size), to measure their annual flux, which corresponds to the mass accreted on Earth per square metre per year.

If these results are applied to the whole planet, the total annual flux of micrometeorites represents 5,200 tons per year. This is the main source of extraterrestrial matter on our planet, far ahead of larger objects such as meteorites, for which the flux is less than ten tons per year.

A comparison of the flux of micrometeorites with theoretical predictions confirms that most micrometeorites probably come from comets (80%) and the rest from asteroids.

This is valuable information to better understand the role played by these interplanetary dust particles in supplying water and carbonaceous molecules on the young Earth.

Read more at Science Daily

Neanderthal ancestry identifies oldest modern human genome

 Ancient DNA from Neandertals and early modern humans has recently shown that the groups likely interbred somewhere in the Near East after modern humans left Africa some 50,000 years ago. As a result, all people outside Africa carry around 2% to 3% Neandertal DNA. In modern human genomes, those Neandertal DNA segments became increasingly shorter over time and their length can be used to estimate when an individual lived. Archaeological data published last year furthermore suggests that modern humans were already present in southeastern Europe 47-43,000 years ago, but due to a scarcity of fairly complete human fossils and the lack of genomic DNA, there is little understanding of who these early human colonists were -- or of their relationships to ancient and present-day human groups.

In a new study published in Nature Ecology & Evolution, an international team of researchers reports what is likely the oldest reconstructed modern human genome to date. First discovered in Czechia, the woman known to researchers as Zlatý kůň (golden horse in Czech) displayed longer stretches of Neanderthal DNA than the 45,000-year-old Ust'-Ishim individual from Siberia, the so-far oldest modern human genome. Analysis suggests that she was part of a population that formed before the populations that gave rise to present-day Europeans and Asians split apart.

A recent anthropological study based on the shape of Zlatý kůň's skull showed similarities with people who lived in Europe before the Last Glacial Maximum -- at least 30,000 years ago -- but radiocarbon dating produced sporadic results, some as recent as 15,000 years ago. It wasn't until Jaroslav Br??ek from the Faculty of Science, Prague and Petr Velemínský of Prague's National Museum collaborated with the genetics laboratories of the Max Planck Institute for the Science of Human History that a clearer picture came into view.

"We found evidence of cow DNA contamination in the analyzed bone, which suggests that a bovine-based glue used in the past to consolidate the skull was returning radiocarbon dates younger than the fossil's true age," says Cosimo Posth, co-lead author of the study. Posth was formerly a research group leader at the Max Planck Institute for the Science of Human History and is currently Professor of Archaeo- and Palaeogenetics at the University of Tübingen.

However, it was the Neandertal DNA that led the team to their major conclusions about the age of the fossil. Zlatý kůň carried about the same amount Neanderthal DNA in her genome, as Ust Ishim or other modern humans outside Africa, but the segments with Neanderthal ancestry were on average much longer.

"The results of our DNA analysis show that Zlatý kůň lived closer in time to the admixture event with Neanderthals," says Kay Prüfer, co-lead author of the study.

The scientists were able to estimate that Zlatý kůň lived approximately 2,000 years after the last admixture. Based on these findings, the team argues that Zlatý kůň represents the oldest human genome to date, roughly the same age as -- if not a few hundred years older than -- Ust'-Ishim.

"It is quite intriguing that the earliest modern humans in Europe ultimately didn't succeed! Just as with Ust'-Ishim and the so far oldest European skull from Oase 1, Zlatý kůň shows no genetic continuity with modern humans that lived in Europe after 40,000 years ago," says Johannes Krause, senior author of the study and director at the Max Planck Institute for Evolutionary Anthropology.

One possible explanation for the discontinuity is the Campanian Ignimbrite volcanic eruption roughly 39,000 years ago, which severely affected climate in the northern hemisphere and may have reduced the survival chances of Neanderthals and early modern humans in large parts of Ice Age Europe.

Read more at Science Daily

800-year-old medieval pottery fragments reveal Jewish dietary practices

 A team of scientists, led by the University of Bristol, with archaeologists from Oxford Archaeology, have found the first evidence of a religious diet locked inside pottery fragments excavated from the early medieval Jewish community of Oxford.

Keeping kosher is one of the oldest known diets across the world and, for an observant Jew, maintaining these dietary laws (known as Kashruth) is a fundamental part of everyday life. It is a key part of what identifies them as Jews, both amongst their own communities and to the outside world.

Oxford's Jewish quarter was established around St. Aldates in the twelfth and thirteenth centuries, following William the Conqueror's invitation to Jews in Northern France to settle in England. Recent excavations by Oxford Archaeology at St Aldates, in the historic heart of Oxford, revealed evidence for two houses, which a medieval census suggested belonged to two Jewish families. One was owned by Jacob f. mag. Moses and called Jacob's Hall, and was said to be one of the most substantial private houses in Oxford and the other house was owned by an Elekin f. Bassina.

During excavations, archaeologists found a stone-built structure, identified as a latrine, and dated to the late 11th and 12th century. A remarkable animal bone assemblage was unearthed in this latrine, dominated by domestic fowl (mainly goose), and with a complete absence of pig bones, hinting at a kosher diet. Fish bones comprised only species such as herring which are kosher. This combination of species suggests a Jewish dietary signature, identified in British zooarchaeology for the first time, and just the third time in medieval Europe.

To investigate whether the inhabitants of the two houses were eating a Jewish diet, the team used a combined chemical and isotopic approach to identify and quantify the food residues absorbed into medieval vessels found at the site.

Their findings, published recently in the journal Archaeological and Anthropological Sciences, showed that the possible Jewish vessels were only used to cook meats from cattle, sheep and goat. Evidence for pig processing was entirely absent. However, the cooking and eating of pork was evident from the pottery residues and animal bones from a contemporaneous site outside of the Jewish Quarter in Oxford (The Queen's College), and from the earlier Anglo-Saxon phase at St Aldates.

Lead author, Dr Julie Dunne from the University of Bristol's School of Chemistry, said: "This is a remarkable example of how biomolecular information extracted from medieval pottery and combined with ancient documents and animal bones, has provided a unique insight into 800-year-old Jewish dietary practices."

This is the first study of its kind that has been able to identify the practice of keeping kosher, with its associated ritual food practices and taboos, using ancient food residues found in cooking pots, opening the way for similar studies in future.

Edward Biddulph, who managed the post-excavation project at Oxford Archaeology, said: "The results of the excavation at St Aldates and Queen Street have been astonishing, not only revealing rare archaeological evidence of a medieval Jewry in Britain, but also demonstrating the enormous value of carefully focused analysis that combines traditional finds and stratigraphic analysis with scientific techniques."

Dr Lucy Cramp who is a senior lecturer in the Department of Anthropology and Archaeology at Bristol, and is a co-author of the study, added: "Human dietary choices are based on far more than availability or caloric content. What's really exciting is how this evidence for dietary patterns in Medieval Oxford informs us about the diversity of cultural practices and beliefs that were present in the past, as today."

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Origins of life could have started with DNA-like XNAs

Nagoya University scientists in Japan have demonstrated how DNA-like molecules could have come together as a precursor to the origins of life. The findings, published in the journal Nature Communications, not only suggest how life might have begun, but also have implications for the development of artificial life and biotechnology applications.

"The RNA world is widely thought to be a stage in the origin of life," says Nagoya University biomolecular engineer Keiji Murayama. "Before this stage, the pre-RNA world may have been based on molecules called xeno nucleic acids (XNAs). Unlike RNA, however, XNA replication probably didn't require enzymes. We were able to synthesize an XNA without enzymes, strongly supporting the hypothesis that an XNA world might have existed before the RNA world."

XNAs are formed of chains of linked nucleotides, similar to DNA and RNA but with a different sugar backbone. XNAs can carry genetic code very stably because the human body can't break them down. Some researchers have reported that XNAs containing specific sequences can act as enzymes and bind to proteins. This makes XNAs exciting in the field of synthetic genetics, with potential biotechnology and molecular medicine applications.

Murayama, Hiroyuki Asanuma and colleagues wanted to find out if conditions likely present on early Earth could have led to XNA chain formation. They synthesized fragments of acyclic (non-circular) L-threoninol nucleic acid (L-aTNA), a molecule that is thought to have existed before RNA came to be. They also made a longer L-aTNA with a nucleobase sequence that complemented the sequences of the fragments, similar to how DNA strands match up.

When placed together in a test tube under controlled temperature, the shorter L-aTNA fragments came together and linked up with each other on the longer L-aTNA template. Critically, this happened in the presence of a compound, called N-cyanoimidazole, and a metal ion, like manganese, both of which were possibly present in early Earth. The fragments interlinked when a phosphate at the end of one chemically attached to a hydroxyl group at the end of its neighbour, without the help of an enzyme.

"To the best of our knowledge, this is the first demonstration of template-driven, enzyme-free extension of acyclic XNA from a random fragment pool, generating phosphodiester bonding," says Murayama.

The team also demonstrated that L-aTNA fragments could interlink on DNA and RNA templates. This suggests that genetic code could be transferred from DNA and RNA onto L-aTNA and vice versa.

"Our strategy is an attractive system for experimenting with the construction of artificial life and the development of highly functional biological tools composed of acyclic XNA," says Murayama. "The data also indicate that L-aTNA could have been an RNA precursor."

Read more at Science Daily

Losing weight through exercise

Worldwide 39 percent of the adults were overweight in 2016, according to statistics of the World Health Organization. In the US the prevalence of obesity was 42.4 percent in 2017/2018, according to a survey of the National Center for Health Statistics (NCHS).

Concurrently millions of people want to lose weight. Physical exercise is an important option to achieve this. After all, more calories are consumed through sport than when sitting, standing or lying down.

But what influence does sport have on (direct) eating habits? Scientists at the Technical University of Munich (TUM) and the University of Nebraska (USA) have now investigated this question for the first time.

Randomized study

"In the sports context, we have the phenomenon of people overeating after physical activity," said Prof. Köhler, Professor of Exercise, Nutrition and Health at the Technical University of Munich. "People want to reward themselves and their bodies for being active. So we use a hypothetical experiment to find out why people eat more after exercise compared to when they don't exercise."

The aim of a randomized crossover study was to investigate the influence of exercise on hypothetical decisions regarding the amount and timing of food intake. For this purpose, 41 healthy participants (23 women, 18 men) aged between 19 and 29 years with an average BMI of 23.7 were randomly assigned to either a 45-minute exercise session or a rest period of equal duration at the first visit and completed the other study condition at the second visit.

Subjective assessment of hunger and satiety

In each case, the training group answered an electronic questionnaire before the physical activity about their subjective assessment of hunger and satiety, preferred amount of food to eat, and choice between foods that differed in timing of consumption. Subjects indicated their food quantity preferences by listing their desired portion size of each food. Preferences were obtained for both immediate and later consumption of the food after four hours.

After answering the first questionnaire, participants performed 45 minutes of aerobic exercise on a bicycle ergometer. Immediately afterwards, they completed the electronic questionnaire a second time and then a third time after a 30-minute break. The procedure for the group without training was identical; instead of 45 minutes of physical activity, these participants had a rest break.

Compared to the rest break, exercise provided a greater increase in the amount of food chosen, both immediately after exercise and 30 minutes afterwards. Physical activity also resulted in a greater increase in preference for immediate food consumption both immediately after exercise and 30 minutes afterwards.

Weight loss through exercise

"Based on this study, we were able to show for the first time that certain characteristics, such as the amount and 'urgency' with which a person wants to eat, change over the course of physical exertion," said Prof. Köhler, classifying the results. "These findings help us develop new interventions to optimize weight loss through exercise."

"The actual results suggest that physical exertion can entice those who do sport to eat larger amounts of food more quickly after the training session," says Prof. Köhler. "Since weight loss is a main motivation for exercising for many, and failure to achieve the desired weight loss makes it likely to quit exercising, it could be a good strategy to think about what you want to eat afterwards before you start to exercise."

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Genomes of the earliest Europeans

An international research team has sequenced the genomes of the oldest securely dated modern humans in Europe who lived around 45,000 years ago in Bacho Kiro Cave, Bulgaria. By comparing their genomes to the genomes of people who lived later in Europe and in Asia the researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, show that this early human group in Europe contributed genes to later people, particularly present-day East Asians. The researchers also identified large stretches of Neanderthal DNA in the genomes of the Bacho Kiro Cave people, showing that they had Neanderthal ancestors about five to seven generations back in their family histories. This suggests that mixture with Neanderthals was the rule rather than the exception when the first modern humans arrived in Europe.

Last year, a research team led by researchers from the National Institute of Archaeology with Museum at the Bulgarian Academy of Sciences and the Max Planck Institute for Evolutionary Anthropology, Germany, reported the discovery of modern human remains found in direct association with the Initial Upper Palaeolithic stone tools at the site of Bacho Kiro Cave in Bulgaria. The oldest individuals found in the cave were directly radiocarbon dated to between 43,000 and 46,000 years ago. They are thus the earliest known dispersal of modern humans across the mid-latitudes of Eurasia.

Mateja Hajdinjak and colleagues have now sequenced the genomes of five individuals found at the Bacho Kiro Cave. Four individuals are between 43,000 to 46,000-years-old and were found together with stone tools belonging to the Initial Upper Palaeolithic, the earliest culture associated with modern humans in Eurasia. An additional individual found in the cave is around 35,000-years-old and found with stone tools of a later type. It was previously thought that bearers of the Initial Upper Palaeolithic died out without contributing genetically to modern humans arriving later. However, the researchers now show that the oldest Bacho Kiro Cave individuals, or groups closely related to them, contributed genes to present-day people. Surprisingly, this contribution is found particularly in East Asia and the Americas rather than in Europe where the Bacho Kiro Cave people lived. These genetic links to Asia mirror the links seen between the Initial Upper Palaeolithic stone tools and personal ornaments found in Bacho Kiro Cave and tools and ancient jewelry found across Eurasia to Mongolia.

Genetic differences between individuals

Importantly, the later 35,000-year-old individual found in Bacho Kiro Cave belonged to a group that was genetically distinct from the earlier inhabitants of the cave. This shows that the earliest history of modern humans in Europe may have been tumultuous and involved population replacements.

The earliest people at Bacho Kiro Cave lived at a time when Neanderthals were still around. The researchers therefore scanned their genomes for fragments of Neanderthal DNA. "We found that the Bacho Kiro Cave individuals had higher levels of Neanderthal ancestry than nearly all other early humans, with the exception of a 40,000-year-old individual from Romania. Crucially, most of this Neanderthal DNA comes in extremely long stretches. This shows that these individuals had Neanderthal ancestors some five to seven generations back in their family trees" says Mateja Hajdinjak.

 Read more at Science Daily

Raindrops also keep fallin' on exoplanets

One day, humankind may step foot on another habitable planet. That planet may look very different from Earth, but one thing will feel familiar -- the rain.

In a recent paper, Harvard researchers found that raindrops are remarkably similar across different planetary environments, even planets as drastically different as Earth and Jupiter. Understanding the behavior of raindrops on other planets is key to not only revealing the ancient climate on planets like Mars but identifying potentially habitable planets outside our solar system.

"The lifecycle of clouds is really important when we think about planet habitability," said Kaitlyn Loftus, a graduate student in the Department of Earth and Planetary Sciences and lead author of the paper. "But clouds and precipitation are really complicated and too complex to model completely. We're looking for simpler ways to understand how clouds evolve, and a first step is whether cloud droplets evaporate in the atmosphere or make it to the surface as rain."

"The humble raindrop is a vital component of the precipitation cycle for all planets," said Robin Wordsworth, Associate Professor of Environmental Science and Engineering at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and senior author of the paper. "If we understand how individual raindrops behave, we can better represent rainfall in complex climate models."

An essential aspect of raindrop behavior, at least to climate modelers, is whether or not the raindrop makes it to the surface of the planet because water in the atmosphere plays a big role in planetary climate. To that end, size matters. Too big and the drop will break apart due to insufficient surface tension, regardless of whether it's water, methane or superheated, liquid iron as on an exoplanet called WASP-76b. Too small and the drop will evaporate before hitting the surface.

Loftus and Wordsworth identified a Goldilocks zone for raindrop size using just three properties: drop shape, falling speed, and evaporation speed.

Drop shapes are the same across different rain materials and primarily depend on how heavy the drop is. While many of us may picture a traditional tear-shaped droplet, raindrops are actually spherical when small, becoming squashed as they grow larger until they transition into a shape like the top of a hamburger bun. Falling speed depends on this shape as well as gravity and the thickness of the surrounding air.

Evaporation speed is more complicated, influenced by atmospheric composition, pressure, temperature, relative humidity and more.

By taking all of these properties into account, Loftus and Wordsworth found that across a wide range of planetary conditions, the math of raindrop falling means only a very small fraction of the possible drop sizes in a cloud can reach the surface.

"We can use this behavior to guide us as we model cloud cycles on exoplanets," said Loftus.

"The insights we gain from thinking about raindrops and clouds in diverse environments are key to understanding exoplanet habitability," said Wordsworth. "In the long term, they can also help us gain a deeper understanding of the climate of Earth itself."

Read more at Science Daily

Hubble spots double quasars in merging galaxies

 NASA's Hubble Space Telescope is "seeing double." Peering back 10 billion years into the universe's past, Hubble astronomers found a pair of quasars that are so close to each other they look like a single object in ground-based telescopic photos, but not in Hubble's crisp view.

The researchers believe the quasars are very close to each other because they reside in the cores of two merging galaxies. The team went on to win the "daily double" by finding yet another quasar pair in another colliding galaxy duo.

A quasar is a brilliant beacon of intense light from the center of a distant galaxy that can outshine the entire galaxy. It is powered by a supermassive black hole voraciously feeding on inflating matter, unleashing a torrent of radiation.

"We estimate that in the distant universe, for every 1,000 quasars, there is one double quasar. So finding these double quasars is like finding a needle in a haystack," said lead researcher Yue Shen of the University of Illinois at Urbana-Champaign.

The discovery of these four quasars offers a new way to probe collisions among galaxies and the merging of supermassive black holes in the early universe, researchers say.

Quasars are scattered all across the sky and were most abundant 10 billion years ago. There were a lot of galaxy mergers back then feeding the black holes. Therefore, astronomers theorize there should have been many dual quasars during that time.

"This truly is the first sample of dual quasars at the peak epoch of galaxy formation with which we can use to probe ideas about how supermassive black holes come together to eventually form a binary," said research team member Nadia Zakamska of Johns Hopkins University in Baltimore, Maryland.

The team's results appeared in the April 1 online issue of the journal Nature Astronomy.

Shen and Zakamska are members of a team that is using Hubble, the European Space Agency's Gaia space observatory, and the Sloan Digital Sky Survey, as well as several ground-based telescopes, to compile a robust census of quasar pairs in the early universe.

The observations are important because a quasar's role in galactic encounters plays a critical part in galaxy formation, the researchers say. As two close galaxies begin to distort each other gravitationally, their interaction funnels material into their respective black holes, igniting their quasars.

Over time, radiation from these high-intensity "light bulbs" launch powerful galactic winds, which sweep out most of the gas from the merging galaxies. Deprived of gas, star formation ceases, and the galaxies evolve into elliptical galaxies.

"Quasars make a profound impact on galaxy formation in the universe," Zakamska said. "Finding dual quasars at this early epoch is important because we can now test our long-standing ideas of how black holes and their host galaxies evolve together."

Astronomers have discovered more than 100 double quasars in merging galaxies so far. However, none of them is as old as the two double quasars in this study.

The Hubble images show that quasars within each pair are only about 10,000 light-years apart. By comparison, our Sun is 26,000 light-years from the supermassive black hole in the center of our galaxy.

The pairs of host galaxies will eventually merge, and then the quasars also will coalesce, resulting in an even more massive, single solitary black hole.

Finding them wasn't easy. Hubble is the only telescope with vision sharp enough to peer back to the early universe and distinguish two close quasars that are so far away from Earth. However, Hubble's sharp resolution alone isn't good enough to find these dual light beacons.

Astronomers first needed to figure out where to point Hubble to study them. The challenge is that the sky is blanketed with a tapestry of ancient quasars that flared to life 10 billion years ago, only a tiny fraction of which are dual. It took an imaginative and innovative technique that required the help of the European Space Agency's Gaia satellite and the ground-based Sloan Digital Sky Survey to compile a group of potential candidates for Hubble to observe.

Located at Apache Point Observatory in New Mexico, the Sloan telescope produces three-dimensional maps of objects throughout the sky. The team pored through the Sloan survey to identify the quasars to study more closely.

The researchers then enlisted the Gaia observatory to help pinpoint potential double-quasar candidates. Gaia measures the positions, distances, and motions of nearby celestial objects very precisely. But the team devised a new, innovative application for Gaia that could be used for exploring the distant universe. They used the observatory's database to search for quasars that mimic the apparent motion of nearby stars. The quasars appear as single objects in the Gaia data. However, Gaia can pick up a subtle, unexpected "jiggle" in the apparent position of some of the quasars it observes.

The quasars aren't moving through space in any measurable way, but instead their jiggle could be evidence of random fluctuations of light as each member of the quasar pair varies in brightness. Quasars flicker in brightness on timescales of days to months, depending on their black hole's feeding schedule.

This alternating brightness between the quasar pair is similar to seeing a railroad crossing signal from a distance. As the lights on both sides of the stationary signal alternately flash, the sign gives the illusion of "jiggling."

When the first four targets were observed with Hubble, its crisp vision revealed that two of the targets are two close pairs of quasars. The researchers said it was a "light bulb moment" that verified their plan of using Sloan, Gaia, and Hubble to hunt for the ancient, elusive double powerhouses.

Team member Xin Liu of the University of Illinois at Urbana-Champaign called the Hubble confirmation a "happy surprise." She has long hunted for double quasars closer to Earth using different techniques with ground-based telescopes. "The new technique can not only discover dual quasars much further away, but it is much more efficient than the methods we've used before," she said.

Their Nature Astronomy article is a "proof of concept that really demonstrates that our targeted search for dual quasars is very efficient," said team member Hsiang-Chih Hwang, a graduate student at Johns Hopkins University and the principal investigator of the Hubble program. "It opens a new direction where we can accumulate a lot more interesting systems to follow up, which astronomers weren't able to do with previous techniques or datasets."

The team also obtained follow-up observations with the National Science Foundation NOIRLab's Gemini telescopes. "Gemini's spatially-resolved spectroscopy can unambiguously reject interlopers due to chance superpositions from unassociated star-quasar systems, where the foreground star is coincidentally aligned with the background quasar," said team member Yu-Ching Chen, a graduate student at the University of Illinois at Urbana-Champaign.

Although the team is convinced of their result, they say there is a slight chance that the Hubble snapshots captured double images of the same quasar, an illusion caused by gravitational lensing. This phenomenon occurs when the gravity of a massive foreground galaxy splits and amplifies the light from the background quasar into two mirror images. However, the researchers think this scenario is highly unlikely because Hubble did not detect any foreground galaxies near the two quasar pairs.

Galactic mergers were more plentiful billions of years ago, but a few are still happening today. One example is NGC 6240, a nearby system of merging galaxies that has two and possibly even three supermassive black holes. An even closer galactic merger will occur in a few billion years when our Milky Way galaxy collides with neighboring Andromeda galaxy. The galactic tussle would likely feed the supermassive black holes in the core of each galaxy, igniting them as quasars.

Future telescopes may offer more insight into these merging systems. NASA's James Webb Space Telescope, an infrared observatory scheduled to launch later this year, will probe the quasars' host galaxies. Webb will show the signatures of galactic mergers, such as the distribution of starlight and the long streamers of gas pulled from the interacting galaxies.

Read more at Science Daily

Exploring comet thermal history: Burnt-out comet covered with talcum powder

 The world's first ground-based observations of the bare nucleus of a comet nearing the end of its active life revealed that the nucleus has a diameter of 800 meters and is covered with large grains of phyllosilicate; on Earth large grains of phyllosilicate are commonly available as talcum powder. This discovery provides clues to piece together the history of how this comet evolved into its current burnt-out state.

Comet nuclei are difficult to observe because when they enter the inner Solar System, where they are easy to observe from Earth, they heat up and release gas and dust which form a coma obscuring the nuclei. When Comet P/2016 BA14 (PANSTARRS) was discovered in January 2016 it was first mistaken for an asteroid, but subsequent observations revealed weak cometary activity. It is believed that after many trips through the inner Solar System, this comet has burnt off almost all of its ice and is now nearing the end of its cometary life.

On March 22, 2016, this comet passed within 3.6 million kilometers of Earth, only 9 times farther than the Moon. A team of astronomers from the National Astronomical Observatory of Japan (NAOJ) and Koyama Astronomical Observatory of Kyoto Sangyo University used this unique opportunity to observe the comet with the Subaru Telescope about 30 hours before its closest approach to Earth. They successfully observed the nucleus with minimal interference from dust grains in the coma. Previously, the surface composition of a cometary nucleus has only been observed by a few "in-situ" observations by space missions.

Because the team observed thermal infrared radiation, the same region of the infrared used by contactless thermometers, they were able to find evidence that the nucleus is 800 meters in diameter and covered with organic molecules and large grains of phyllosilicate. This is the first time hydrous silicate minerals such as talc have been found in a comet. Comparison with laboratory measurements of various minerals revealed that the hydrous silicate minerals on the surface of P/2016 BA14 have been heated to more than about 330 degrees Celsius in the past. Since the surface temperature of P/2016 BA14 cannot reach higher than about 130 degrees Celsius in its current orbit, the comet may have been in an orbit closer to the Sun in the past.

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Dark Energy Survey physicists open new window into dark energy

An analysis by Dark Energy Survey physicists yields more precise estimates of the average density of matter as well as its propensity to clump together -- two key parameters that help physicists probe the nature of dark matter and dark energy.

The universe is expanding at an ever-increasing rate, and while no one is sure why, researchers with the Dark Energy Survey (DES) at least had a strategy for figuring it out: They would combine measurements of the distribution of matter, galaxies and galaxy clusters to better understand what's going on.

Reaching that goal turned out to be pretty tricky, but now a team led by researchers at the Department of Energy's SLAC National Accelerator Laboratory, Stanford University and the University of Arizona have come up with a solution. Their analysis, published April 6 in Physical Review Letters, yields more precise estimates of the average density of matter as well as its propensity to clump together -- two key parameters that help physicists probe the nature of dark matter and dark energy, the mysterious substances that make up the vast majority of the universe.

"It is one of the best constraints from one of the best data sets to date," says Chun-Hao To, a lead author on the new paper and a graduate student at SLAC and Stanford working with Kavli Institute for Particle Astrophysics and Cosmology Director Risa Wechsler.

An early goal

When DES set out in 2013 to map an eighth of the sky, the goal was to gather four kinds of data: the distances to certain types of supernovae, or exploding stars; the distribution of matter in the universe; the distribution of galaxies; and the distribution of galaxy clusters. Each tells researchers something about how the universe has evolved over time.

Ideally, scientists would put all four data sources together to improve their estimates, but there's a snag: The distributions of matter, galaxies, and galaxy clusters are all closely related. If researchers don't take these relationships into account, they will end up "double counting," placing too much weight on some data and not enough on others, To says.

To avoid mishandling all this information, To, University of Arizona astrophysicist Elisabeth Krause and colleagues have developed a new model that could properly account for the connections in the distributions of all three quantities: matter, galaxies, and galaxy clusters. In doing so, they were able to produce the first-ever analysis to properly combine all these disparate data sets in order to learn about dark matter and dark energy.

Improving estimates

Adding that model into the DES analysis has two effects, To says. First, measurements of the distributions of matter, galaxies and galaxy clusters tend to introduce different kinds of errors. Combining all three measurements makes it easier to identify any such errors, making the analysis more robust. Second, the three measurements differ in how sensitive they are to the average density of matter and its clumpiness. As a result, combining all three can improve the precision with which the DES can measure dark matter and dark energy.

In the new paper, To, Krause and colleagues applied their new methods to the first year of DES data and sharpened the precision of previous estimates for matter's density and clumpiness.

Now that the team can incorporate matter, galaxies and galaxy clusters simultaneously in their analysis, adding in supernova data will be relatively straightforward, since that kind of data is not as closely related with the other three, To says.

"The immediate next step," he says, "is to apply the machinery to DES Year 3 data, which has three times larger coverage of the sky." This is not as simple as it sounds: While the basic idea is the same, the new data will require additional efforts to improve the model to keep up with the higher quality of the newer data, To says.

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Skin deep: Aquatic skin adaptations of whales and hippos evolved independently

 A new study shows that the similarly smooth, nearly hairless skin of whales and hippopotamuses evolved independently. The work suggests that their last common ancestor was likely a land-dwelling mammal, uprooting current thinking that the skin came fine-tuned for life in the water from a shared amphibious ancestor. The study is published today in the journal Current Biology and was led by researchers at the American Museum of Natural History; University of California, Irvine; University of California, Riverside; Max Planck Institute of Molecular Cell Biology and Genetics; and the LOEWE-Centre for Translational Biodiversity Genomics (Germany).

"How mammals left terra firma and became fully aquatic is one of the most fascinating evolutionary stories, perhaps rivaled only by how animals traded water for land in the first place or by the evolution of flight," said John Gatesy, a senior research scientist in the American Museum of Natural History's Division of Vertebrate Zoology and a corresponding author on the study. "Our latest findings contradict the current dogma in the field -- that relatives of the amphibious hippo might have been part of the transition as mammals re-entered life in the water."

Despite their contrasting appearances, fully aquatic cetaceans -- the group that includes whales, dolphins, and porpoises -- and semi-aquatic hippopotamuses are each other's closest living relatives and share a common ancestor that lived about 55 million years ago. They also share a number of characteristics that are odd for most mammals: they give birth and nurse underwater, and lack scrotal testes and sebaceous glands (that secrete oily sebum) as well as most of their hair. Since these traits are rarely found in other mammals, one would assume that they were already present in the common ancestor of hippos and cetaceans. But how and when cetacean ancestors became fully aquatic remains a subject of intense debate.

Paleontological studies on transitional extinct cetaceans suggest that entry into water was a gradual process that included amphibious phases. So did hippos and cetaceans develop adaptations for an aquatic lifestyle independently? Or was their common ancestor already amphibious, and from there, cetaceans diverged to become fully aquatic?

"The simplest hypothesis is that the ancestor of whales and hippos was already amphibious, but evolution isn't always the shortest distance between two points," said the study's lead author Mark Springer, a biology professor at the University of California, Riverside.

To help resolve this question, the researchers looked to the animals' skin, which shows profound evolutionary changes in response to aquatic life.

"When a group of animals becomes aquatic, skin becomes much more streamlined and uniform throughout," said Maksim Plikus, a co-corresponding author and a skin biologist from the University of California, Irvine. "Complex derivatives like hairs, nails, or sweat glands are no longer needed, and in fact, can become a hinderance to life under water, so those go away. And it loses the barrier function performed by the outer layer of skin, which in terrestrial mammals, is vital to keeping water from evaporating out of the body and preventing pathogens from getting in."

The researchers compared the anatomy of hippo and cetacean skin based on histology and used genomic screens to compile a comprehensive list of "skin genes" that have been inactivated in both hippos and cetaceans. This was aided by examining -- for the first time -- the genome of the pygmy hippo, Choeropsis liberiensis, one of only two living hippo species.

"When you look at the molecular signatures, there is a striking and clear answer," said study co-corresponding author and evolutionary genomicist Michael Hiller, from the Max Planck Institute of Molecular Cell Biology and Genetics and the LOEWE-Centre for Translational Biodiversity Genomics in Germany. "Our results strongly support the idea that 'aquatic' skin traits found in both hippos and cetaceans evolved independently. And not only that, we can see that the gene losses in the hippo lineage happened much later than in the cetacean lineage."

These gene results are in line with examinations of the skin itself: Unlike whales, hippos actually do have a very specialized kind of sweat gland that produces "blood sweat," an orange-colored substance that is speculated to have natural anti-microbial and sunscreen properties. And while cetaceans only have a few whiskers, hippos are fully whiskered but also have sparse body hairs, most prominent on their ears and the tip of their tail. The latter are used when hippos defecate, during which they quickly spin their tail and the brush-like hairs help to pulverize the feces all around as a way to mark territory. In addition, cetacean skin is much thicker than hippo skin, and hippos are alone in having hooves.

Read more at Science Daily

Less than a nanometer thick, stronger and more versatile than steel

 Scientists create stable nanosheets containing boron and hydrogen atoms with potential applications in nanoelectronics and quantum information technology.

What's thinner than thin? One answer is two-dimensional materials -- exotic materials of science with length and width but only one or two atoms in thickness. They offer the possibility of unprecedented boosts in device performance for electronic devices, solar cells, batteries and medical equipment.

In collaboration with Northwestern University and the University of Florida, scientists from the U.S. Department of Energy's (DOE) Argonne National Laboratory report in Science magazine a breakthrough involving a 2D material called borophane, a sheet of boron and hydrogen a mere two atoms in thickness.

One of the most exciting developments in materials science in recent decades has been a 2D sheet of carbon (graphene), which is one atom thick and 200 times stronger than steel. A similarly promising and newer material is an atom-thick sheet of boron, called borophene -- with an "e." A multi-institutional team, including researchers in Argonne's Center for Nanoscale Materials (a DOE Office of Science User Facility), first synthesized borophene in 2015.

While graphene is simply one atomic layer out of the many same layers in the common material graphite, borophene has no equivalent parent structure and is very difficult to prepare. What's more, the rapid reaction of borophene with air means it is very unstable and changes form readily.

"Borophene by itself has all kinds of problems," said Mark Hersam, Professor of Materials Science and Engineering at Northwestern University. "But when we mix borophene with hydrogen, the product suddenly becomes much more stable and attractive for use in the burgeoning fields of nanoelectronics and quantum information technology."

The research team grew borophene on a silver substrate then exposed it to hydrogen to form the borophane. They then unraveled the complex structure of borophane by combining a scanning tunneling microscope with a computer-vision based algorithm that compares theoretical simulations of structures with experimental measurements. Computer vision is a branch of artificial intelligence that trains high performance computers to interpret and understand the visual world.

Even though the borophane material is only two atoms thick, its structure is quite complex because of the many possible arrangements for the boron and hydrogen atoms. "We have tackled a significant challenge in determining the atomic structures from scanning tunneling microscopy images and computational modeling at the atomic scale with the help of computer vision," said Argonne's Maria Chan, nanoscientist at the Center for Nanoscale Materials. Given the success in unraveling this complex structure, the team's automated analytical technique should be applicable in identifying other complex nanostructures in the future.

"What is really encouraging from our results is that we found a borophane nanosheet on a silver substrate to be quite stable, unlike borophene," said Pierre Darancet, nanoscientist at Argonne's Center for Nanoscale Materials. "This means it should be easily integrated with other materials in the construction of new devices for optoelectronics, devices combining light with electronics." Such light-controlling and light-emitting devices could be incorporated into telecommunications, medical equipment and more.

Read more at Science Daily

Scientists scour genes of 53,000+ people to better battle dangerous diseases

A new analysis of the entire genetic makeup of more than 53,000 people offers a bonanza of valuable insights into heart, lung, blood and sleep disorders, paving the way for new and better ways to treat and prevent some of the most common causes of disability and death.

The analysis from the Trans-Omics for Precision Medicine (TOPMed) program examines the complete genomes of 53,831 people of diverse backgrounds on different continents. Most are from minority groups, which have been historically underrepresented in genetic studies. The increased representation should translate into better understanding of how heart, lung, blood and sleep disorders affect minorities and should help reduce longstanding health disparities.

"The Human Genome Project has generated a lot of promises and opportunities for applying genomics to precision medicine, and the TOPMed program is a major step in this direction," said Stephen S. Rich, PhD, a genetics researcher at the University of Virginia School of Medicine who helped lead the project. "An important feature of TOPMed is not only publishing the genomic data on 53,000 people with massive amounts of data related to heart, lung, blood and sleep disorders but also the great diversity of the participants who donated their blood and data."

Historic Genome Analysis

The groundbreaking work identified 400 million genetic variants, of which more than 78% had never been described. Nearly 97% were extremely rare, occurring in less than 1% of people. This sheds light on both how genes mutate and on human evolution itself, the researchers say.

Of the groups studied, people of African descent had the greatest genetic variability, the researchers found. The resulting data is the best ever produced on people of African ancestry, the scientists report in the journal Nature.

The work also offers important new insights into certain gene variants that can reduce people's ability to benefit from prescription drugs. This can vary by race and ethnic group.

"TOPMed is an important and historic effort to include under-represented minority participants in genetic studies," said Rich, who served on the project's Executive Committee and chaired the Steering Committee. "The work of TOPMed should translate not only into better scientific knowledge but increase diversity at all levels -- scientists, trainees, participants -- in work to extend personalized medicine for everyone."

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Masks, ventilation stop COVID spread better than social distancing, study shows

 A new study from the University of Central Florida suggests that masks and a good ventilation system are more important than social distancing for reducing the airborne spread of COVID-19 in classrooms.

The research, published recently in the journal Physics of Fluids, comes at a critical time when schools and universities are considering returning to more in-person classes in the fall.

"The research is important as it provides guidance on how we are understanding safety in indoor environments," says Michael Kinzel, an assistant professor in UCF's Department of Mechanical and Aerospace Engineering and study co-author.

"The study finds that aerosol transmission routes do not display a need for six feet social distancing when masks are mandated," he says. "These results highlight that with masks, transmission probability does not decrease with increased physical distancing, which emphasizes how mask mandates may be key to increasing capacity in schools and other places."

In the study, the researchers created a computer model of a classroom with students and a teacher, then modeled airflow and disease transmission, and calculated airborne-driven transmission risk.

The classroom model was 709 square feet with 9-foot-tall ceilings, similar to a smaller-size, university classroom, Kinzel says. The model had masked students -- any one of whom could be infected -- and a masked teacher at the front of the classroom.

The researchers examined the classroom using two scenarios -- a ventilated classroom and an unventilated one -- and using two models, Wells-Riley and Computational Fluid Dynamics. Wells-Riley is commonly used to assess indoor transmission probability and Computational Fluid Dynamics is often used to understand the aerodynamics of cars, aircraft and the underwater movement of submarines.

Masks were shown to be beneficial by preventing direct exposure of aerosols, as the masks provide a weak puff of warm air that causes aerosols to move vertically, thus preventing them from reaching adjacent students, Kinzel says.

Additionally, a ventilation system in combination with a good air filter reduced the infection risk by 40 to 50% compared to a classroom with no ventilation. This is because the ventilation system creates a steady current of air flow that circulates many of the aerosols into a filter that removes a portion of the aerosols compared to the no-ventilation scenario where the aerosols congregate above the people in the room.

These results corroborate recent guidelines from the U.S. Centers for Disease Control and Prevention that recommend reducing social distancing in elementary schools from six to three feet when mask use is universal, Kinzel says.

"If we compare infection probabilities when wearing masks, three feet of social distancing did not indicate an increase in infection probability with respect to six feet, which may provide evidence for schools and other businesses to safely operate through the rest of the pandemic," Kinzel says.

"The results suggest exactly what the CDC is doing, that ventilation systems and mask usage are most important for preventing transmission and that social distancing would be the first thing to relax," the researcher says.

When comparing the two models, the researchers found that Wells-Riley and Computational Fluid Dynamics generated similar results, especially in the non-ventilated scenario, but that Wells-Riley underpredicted infection probability by about 29 percent in the ventilated scenario.

As a result, they recommend some of the additional complex effects captured in Computational Fluid Dynamics be applied to Wells-Riley to develop a more complete understanding of risk of infection in a space, says Aaron Foster, a doctoral student in UCF's Department of Mechanical and Aerospace Engineering and the study's lead author.

"While the detailed Computational Fluid Dynamics results provided new insights into the risk variation and distance relationships, they also validated the more commonly used Wells-Riley models as capturing the majority of the benefit of ventilation with reasonable accuracy," Foster says. "This is important since these are publicly available tools that anyone can use to reduce risk."

The research is part of a larger overall effort to control airborne disease transmission and better understand factors related to being a super-spreader. The researchers are also testing the effects of masks on aerosol and droplet transmission distance. The work is funded in part by the National Science Foundation.

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African elephants' range is just 17 percent of what it could be

 A study reported in the journal Current Biology on April 1 has both good news and bad news for the future of African elephants. While about 18 million square kilometers of Africa -- an area bigger than the whole of Russia -- still has suitable habitat for elephants, the actual range of African elephants has shrunk to just 17%of what it could be due to human pressure and the killing of elephants for ivory.

"We looked at every square kilometer of the continent," says lead author Jake Wall of the Mara Elephant Project in Kenya. "We found that 62% of those 29.2 million square kilometers is suitable habitat."

The findings suggest that, if released from human pressures, including the threat of being killed for their ivory, elephants still have great potential for recovery into areas where the human footprint is light. They note that those 18 million square kilometers include many areas where there is still room for peaceful coexistence between humans and elephants as well as others where that prospect is clearly not realistic.

Like many wildlife species, it's long been clear that African elephant populations and their geographic range were shrinking due to killing for ivory, habitat loss, and the growth of human populations. But African savannah and forest elephants can live in many environments, from semi-deserts to tropical swamp forests. Wall's team wanted to better understand how elephants are using the space that's available to them and what's driving their ranging patterns.

To analyze the suitability of habitats over the entire continent at a kilometer-level scale, Wall and his colleagues drew on data from GPS-tracking collars fitted to 229 elephants across Africa by Save the Elephants and its partners over a 15-year period. Using Google Earth Engine, a satellite imagery computing platform, they looked at the vegetation, tree cover, surface temperature, rainfall, water, slope, aggregate human influence, and protected areas in the areas the elephants traversed. This allowed them to determine which habitats can support elephants and the extremes of conditions that they currently can tolerate.

"Combining three powerful tools -- GPS telemetry, continent-wide remote sensing at a fine resolution, and a suite of analytical techniques -- has allowed us to see what factors now control the movements and lives of these two hugely ecologically important species -- and where, if circumstances change, they could range more widely across their historical African home," said Samantha Strindberg of the Wildlife Conservation Society.

The researchers uncovered vast areas of potentially suitable habitat for elephants in the Central African Republic and the Democratic Republic of Congo. The researchers note that forests in those areas recently held hundreds of thousands of elephants but today hold only about 5,000 to 10,000. The study also highlighted the extreme habitats that African elephants do not visit.

"The major no-go areas include the Sahara, Danakil, and Kalahari deserts, as well as urban centers and high mountaintops," said Iain Douglas-Hamilton, the founder of Save the Elephants. "That gives us an idea of what the former range of elephants might have been. However, there's a dearth of information about the status of African elephants between the end of Roman times and the arrival of the first European colonizers."

The tracking data also show that elephants living in protected areas tend to have smaller home ranges. The researchers suggest that's probably because they feel unsafe ranging into unprotected lands. The study notes that approximately 57% of the current elephant range is outside of protected areas, highlighting the limited space presently reserved for their safety. To secure long-term survival of elephants, the researchers say that habitat protection, protection of elephants themselves from illegal killing, and an ethic of human-elephant coexistence will be essential.

"Elephants are generalist mega-herbivores that can occupy fringe habitats," Wall says. "Their range may have shrunk, but if we gave them the chance, they could spread back to former parts of it."

Unfortunately, trends are headed in the wrong direction. "The human footprint is increasing at an accelerated rate and expected to double by 2050, with between 50% and 70% of the planet already experiencing anthropogenic disturbance," the researchers write. "Fragmentation of wildlife habitats by humans has resulted in only 7% of wildlife habitat patches being larger than 100 km2. Development scenarios that accommodate the spatial needs of wildlife leaving large, low-human impact areas of intact habitat, and especially formally protected areas, are urgently required. In the face of increasing human pressures, proactive landscape planning at the local, national, and continental scales are critical, as well as fostering an ethic of human elephant coexistence, if the future of elephants is to be secured."

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Evidence of Antarctic glacier's tipping point confirmed

 Researchers have confirmed for the first time that Pine Island Glacier in West Antarctica could cross tipping points, leading to a rapid and irreversible retreat which would have significant consequences for global sea level.

Pine Island Glacier is a region of fast-flowing ice draining an area of West Antarctica approximately two thirds the size of the UK. The glacier is a particular cause for concern as it is losing more ice than any other glacier in Antarctica.

Currently, Pine Island Glacier together with its neighbouring Thwaites glacier are responsible for about 10% of the ongoing increase in global sea level.

Scientists have argued for some time that this region of Antarctica could reach a tipping point and undergo an irreversible retreat from which it could not recover. Such a retreat, once started, could lead to the collapse of the entire West Antarctic Ice Sheet, which contains enough ice to raise global sea level by over three metres.

While the general possibility of such a tipping point within ice sheets has been raised before, showing that Pine Island Glacier has the potential to enter unstable retreat is a very different question.

Now, researchers from Northumbria University have shown, for the first time, that this is indeed the case.

Their findings are published in leading journal, The Cryosphere.

Using a state-of-the-art ice flow model developed by Northumbria's glaciology research group, the team have developed methods that allow tipping points within ice sheets to be identified.

For Pine Island Glacier, their study shows that the glacier has at least three distinct tipping points. The third and final event, triggered by ocean temperatures increasing by 1.2C, leads to an irreversible retreat of the entire glacier.

The researchers say that long-term warming and shoaling trends in Circumpolar Deep Water, in combination with changing wind patterns in the Amundsen Sea, could expose Pine Island Glacier's ice shelf to warmer waters for longer periods of time, making temperature changes of this magnitude increasingly likely.

The lead author of the study, Dr Sebastian Rosier, is a Vice-Chancellor's Research Fellow in Northumbria's Department of Geography and Environmental Sciences. He specialises in the modelling processes controlling ice flow in Antarctica with the goal of understanding how the continent will contribute to future sea level rise.

Dr Rosier is a member of the University's glaciology research group, led by Professor Hilmar Gudmundsson, which is currently working on a major £4million study to investigate if climate change will drive the Antarctic Ice Sheet towards a tipping point.

Dr Rosier explained: "The potential for this region to cross a tipping point has been raised in the past, but our study is the first to confirm that Pine Island Glacier does indeed cross these critical thresholds.

"Many different computer simulations around the world are attempting to quantify how a changing climate could affect the West Antarctic Ice Sheet but identifying whether a period of retreat in these models is a tipping point is challenging.

"However, it is a crucial question and the methodology we use in this new study makes it much easier to identify potential future tipping points."

Hilmar Gudmundsson, Professor of Glaciology and Extreme Environments worked with Dr Rosier on the study. He added: "The possibility of Pine Island Glacier entering an unstable retreat has been raised before but this is the first time that this possibility is rigorously established and quantified.

"This is a major forward step in our understanding of the dynamics of this area and I'm thrilled that we have now been able to finally provide firm answers to this important question.

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