Scientists solve 40-year mystery over Jupiter's X-ray aurora

A research team co-led by UCL (University College London) has solved a decades-old mystery as to how Jupiter produces a spectacular burst of X-rays every few minutes.

The X-rays are part of Jupiter's aurora -- bursts of visible and invisible light that occur when charged particles interact with the planet's atmosphere. A similar phenomenon occurs on Earth, creating the northern lights, but Jupiter's is much more powerful, releasing hundreds of gigawatts of energy, enough to briefly power all of human civilisation*.

In a new study, published in Science Advances, researchers combined close-up observations of Jupiter's environment by NASA's satellite Juno, which is currently orbiting the planet, with simultaneous X-ray measurements from the European Space Agency's XMM-Newton observatory (which is in Earth's own orbit).

The research team, led by UCL and the Chinese Academy of Sciences, discovered that X-ray flares were triggered by periodic vibrations of Jupiter's magnetic field lines. These vibrations create waves of plasma (ionised gas) that send heavy ion particles "surfing" along magnetic field lines until they smash into the planet's atmosphere, releasing energy in the form of X-rays.

Co-lead author Dr William Dunn (UCL Mullard Space Science Laboratory) said: "We have seen Jupiter producing X-ray aurora for four decades, but we didn't know how this happened. We only knew they were produced when ions crashed into the planet's atmosphere.

"Now we know these ions are transported by plasma waves -- an explanation that has not been proposed before, even though a similar process produces Earth's own aurora. It could, therefore, be a universal phenomenon, present across many different environments in space."

X-ray auroras occur at Jupiter's north and south poles, often with clockwork regularity -- during this observation Jupiter was producing bursts of X-rays every 27 minutes.

The charged ion particles that hit the atmosphere originate from volcanic gas pouring into space from giant volcanoes on Jupiter's moon, Io.

This gas becomes ionised (its atoms are stripped free of electrons) due to collisions in Jupiter's immediate environment, forming a donut of plasma that encircles the planet.

Co-lead author Dr Zhonghua Yao (Chinese Academy of Sciences, Beijing) said: "Now we have identified this fundamental process, there is a wealth of possibilities for where it could be studied next. Similar processes likely occur around Saturn, Uranus, Neptune and probably exoplanets as well, with different kinds of charged particles 'surfing' the waves."

Co-author Professor Graziella Branduardi-Raymont (UCL Mullard Space Science Laboratory) said: "X-rays are typically produced by extremely powerful and violent phenomena such as black holes and neutron stars, so it seems strange that mere planets produce them too.

"We can never visit black holes, as they are beyond space travel, but Jupiter is on our doorstep. With the arrival of the satellite Juno into Jupiter's orbit, astronomers now have a fantastic opportunity to study an environment that produces X-rays up close."

For the new study, researchers analysed observations of Jupiter and its surrounding environment carried out continuously over a 26-hour period by the Juno and XMM-Newton satellites.

They found a clear correlation between waves in the plasma detected by Juno and X-ray auroral flares at Jupiter's north pole recorded by X-MM Newton. They then used computer modelling to confirm that the waves would drive the heavy particles towards Jupiter's atmosphere.

Why the magnetic field lines vibrate periodically is unclear, but the vibration may result from interactions with the solar wind or from high-speed plasma flows within Jupiter's magnetosphere.

Jupiter's magnetic field is extremely strong -- about 20,000 times as strong as Earth's -- and therefore its magnetosphere, the area controlled by this magnetic field, is extremely large. If it was visible in the night sky, it would cover a region several times the size of our moon.

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Brain functional connectivity in Tourette syndrome

Tourette syndrome, a neurodevelopmental disorder, causes motor and phonic "tics" or uncontrollable repeated behaviors and vocalizations. People affected by Tourette syndrome can often suppress these tics for some time before the urges become overwhelming, and researchers have long wondered at the neural underpinnings of the suppression effort.

Now, in a new study using a non-invasive technique to measure brain activity called high-density electroencephalography (hdEEG), researchers at Yale School of Medicine have assessed the impact of tic suppression on functional connectivity between brain regions.

The study appears in Biological Psychiatry: Cognitive Neuroscience and Neuroimaging, published by Elsevier.

"Tic suppression is an important feature of Tourette syndrome. Understanding how someone may temporarily gain control over their tics may inform several research areas in Tourette syndrome. Yet, brain correlates of tic suppression have not been studied extensively, especially in children," said Denis Sukhodolsky, PhD, senior author of the study, and Associate Professor at the Yale Child Study Center at the Yale School of Medicine, New Haven, CT, USA.

Cameron Carter, MD, Editor of Biological Psychiatry: Cognitive Neuroscience and Neuroimaging, said of the study, "Understanding brain mechanisms associated with successful coping in disorders such as Tourette syndrome opens up opportunities for developing targeted treatments to enhance the innate self-control that normally emerges as the brain matures."

The team led by Dr. Sukhodolsky recorded the brain activity of 72 children, aged 8 to 16 years old, with Tourette syndrome using hdEEG, while they were ticcing freely and while they were suppressing their tics. The researchers then assessed connectivity between the different regions in the brain.

The authors found that connectivity between multiple brain regions was increased while children suppressed their tics. "Some of these regions are part of the default mode network, an array of brain regions engaged during internal thought processes such as daydreaming," explained first author Simon Morand-Beaulieu, PhD.

Additionally, the researchers reported that functional brain connectivity during tic suppression was positively correlated with age, suggesting that the brain networks of tic suppression undergo developmental changes in response to the experience of tics. "This increase in functional connectivity as children mature is consistent with increasing tic suppression capacities developing into adolescence as well as a better awareness of the sensory phenomena accompanying tics," said Dr. Morand-Beaulieu.

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Icequakes likely rumble along geyser-spitting fractures in Saturn's icy moon Enceladus

Tidal stresses may be causing constant icequakes on Saturn's sixth largest moon Enceladus, a world of interest in the search for life beyond Earth, according to a new study. A better understanding of seismic activity could reveal what's under the moon's icy crust and provide clues to the habitability of its ocean.

Enceladus is about 500 kilometers in diameter and almost entirely covered in ice. The moon is nearly 10 times as far away from the Sun as Earth and its bright surface reflects most sunlight, making it very cold, yet researchers have long speculated that the ice encases an underlying liquid ocean.

The moon likely experiences massive tidal forces caused by Saturn and the planet's other, larger moons -- similar to the way Earth's Moon causes tides on Earth. These tidal motions inside Enceladus warm its interior, crack the surface and sometimes squeeze tall geysers of water vapor through notable cracks called the tiger stripe fractures.

The new study used observations of Antarctic ice shelves to suggest tides on Enceladus may also cause small quakes in the ice at the moon's fractures, like icequakes observed on Antarctica's floating ice sheets.

"[Moons like] these are places that are exciting because they might have life," said Kira Olsen, a geophysicist at NASA's Goddard Space Flight Center. She said that since life is thought to have first developed in our oceans, liquid oceans under the ice of other worlds could be a good place to search for life. The icy crust of Enceladus might also protect the water below from radiation, making it more habitable.

The new study was published in the Journal of Geophysical Research: Planets, AGU's journal for research on the formation and evolution of the planets, moons and objects of our solar system and beyond.

"We have ideas of how thick the ice could be, but we don't have direct observation. Studying ice quakes is a way to get at that information," Olsen said.

Internal tides

To learn more about how Enceladus' tiger fractures might be moving, Olsen and her colleagues turned to floating ice shelves in Antarctica as the closest analogue on Earth for the types of activity they were seeing on Enceladus. They could then use their knowledge about how certain surface features on our planet produce seismic activity to estimate what kind of seismic activity is happening on the distant moon.

The researchers analyzed data collected by seismometers along the Ross Ice Shelf in the southern continent between 2014 and 2016 and compared these to satellite images of the area. They paid particular attention to two seismometers placed next to large rifts on the ice slab.

They related the seismic activity to the stress occurring along these rifts. The majority of icequakes on the Ross Ice Shelf occurred when the rifts were pulling apart, which happens when tides are falling.

We have no measurements of seismic activity on Enceladus, but Olsen and her colleagues created models that compared the types of fractures they saw on the moon's surface with those on the Ross Ice Shelf.

These models showed that the largest amount of seismic activity on Enceladus likely corresponded to the tides. Peak seismic activity there occurs when Enceladus is 100 degrees past the nearest approach to Saturn during its orbit. The ocean underneath the ice at this point acts something like water inside a sloshing balloon. The ice fractures are created at the points of highest stress, where the balloon would break apart.

The icequakes aren't massive along these cracks, even at the peak periods of stress. Olsen describes them more like "almost continuous little pops and fractures.

Mark Panning, a research scientist at NASA's Jet Propulsion Laboratory who was not involved in the new study, said that while the Cassini spacecraft revealed the moon is geologically active, it's difficult to tell how that translates to seismic activity. "The study represents a really key way of investigating what seismicity on Enceladus and other tidally activated icy worlds may look like by looking at the best analogs we can find on Earth," he said.

Olsen said scientists should aim to place seismometers within 10 kilometers of these fractures in any future missions to Enceladus to learn more about what's going on below.

"It's not a quiet out of the way place, but it's a pretty good place to study," she said.

More information about the seismic activity could then teach us more about the thickness of the ice crust on Enceladus. For now, no missions to Enceladus have been planned, but the European Space Agency is planning the JUICE mission to one of Jupiter's icy moons, Europa.

Olsen said that similar work could then be conducted on Titan, Saturn's largest moon, a world also covered with ice that may conceal liquid oceans and is another top pick for potential extraterrestrial life. NASA's Dragonfly mission is scheduled to visit Titan in 2036.

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Longest known continuous record of the Paleozoic discovered in Yukon wilderness

Hundreds of millions of years ago, in the middle of what would eventually become Canada's Yukon Territory, an ocean swirled with armored trilobites, clam-like brachiopods and soft, squishy creatures akin to slugs and squid.

A trove of fossils and rock layers formed on that ancient ocean floor have now been unearthed by an international team of scientists along the banks of the Peel River a few hundred miles south of the Arctic's Beaufort Sea. The discovery reveals oxygen changes at the seafloor across nearly 120 million years of the early Paleozoic era, a time that fostered the most rapid development and diversification of complex, multi-cellular life in Earth's history.

"It's unheard of to have that much of Earth's history in one place," said Stanford University geological scientist Erik Sperling, lead author of a July 7 study detailing the team's findings in Science Advances. Most rock formations from the Paleozoic Era have been broken up by tectonic forces or eroded over time. "There's nowhere else in the world that I know of where you can study that long a record of Earth history, where there's basically no change in things like water depth or basin type."

Oxygen was scarce in the deep water of this and other oceans at the dawn of the Paleozoic, roughly 541 million years ago. It stayed scarce until the Devonian, roughly 405 million years ago, when, in a geological blink -- no more than a few million years -- oxygen likely rocketed to levels close to those in modern oceans and the diversity of life on Earth exploded. Big, predatory fish appeared. Primitive ferns and conifers marched across continents previously ruled by bacteria and algae. Dragonflies took flight. And all of this after nearly four billion years of Earth's landscapes being virtually barren.

Scientists have long debated what might have caused the dramatic shift from a low oxygen world to a more oxygenated one that could support a diverse web of animal life. But until now, it has been difficult to pin down the timing of global oxygenation or the long-term, background state of the world's oceans and atmosphere during the era that witnessed both the so-called Cambrian explosion of life and the first of Earth's "Big Five" mass extinctions, about 445 million years ago at the end of the Ordovician.

"In order to make comparisons throughout these huge swaths of our history and understand long-term trends, you need a continuous record," said Sperling, an assistant professor of geological sciences at Stanford's School of Earth, Energy & Environmental Sciences (Stanford Earth).

Context for past life

With permission from the Na Cho Nyak Dun and Tetlit Gwitch'in communities in Yukon, Sperling's team, which included researchers from Dartmouth College and the Yukon Geological Survey, spent three summers at the Peel River site. Arriving by helicopter, the research team hacked through brush with machetes beside Class VI rapids to collect hundreds of fist-sized samples of rock from more than a mile of interbedded layers of shale, chert and lime mudstone.

Back at Sperling's lab at Stanford, a small army of summer undergraduates and graduate students worked over five summers to help analyze the fossils and chemicals entombed in the rocks. "We spent a lot of time splitting open rocks and looking at graptolite fossils," Sperling said. Because graptolites evolved a vast array of recognizable body shapes relatively quickly, the pencil-like markings left by the fossils of these colony-dwelling sea creatures give geologists a way to date the rocks in which they're found.

Once the researchers had finished identifying and dating graptolite fossils, they ground the rocks in a mill, then measured iron, carbon, phosphorus and other elements in the resulting powder to assess the ocean conditions at the time and place where the layers formed. They analyzed 837 new samples from the Peel River site, as well as 106 new samples from other parts of Canada and 178 samples from around the world for comparison.

Winners and losers

The data show low oxygen levels, or anoxia, likely persisted in the world's oceans for millions of years longer than previously thought -- well into the Phanerozoic, when land plants and early animals began to diversify. "The early animals were still living in a low oxygen world," Sperling said. Contrary to long-held assumptions, the scientists found Paleozoic oceans were also surprisingly free of hydrogen sulfide, a respiratory toxin often found in the anoxic regions of modern oceans.

When oxygen eventually did tick upward in marine environments, it came about just as larger, more complex plant life took off. "There's a ton of debate about how plants impacted the Earth system," Sperling said. "Our results are consistent with a hypothesis that as plants evolved and covered the Earth, they increased nutrients to the ocean, driving oxygenation." In this hypothesis, the influx of nutrients to the sea would have given a boost to primary productivity, a measure of how quickly plants and algae take carbon dioxide and sunlight, turn them into new biomass -- and release oxygen in the process.

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Meta-analysis finds that omega-3 fatty acids improved cardiovascular outcomes

For decades, there has been great interest in whether omega-3 fatty acids can lower rates of cardiovascular events. In 2018, results from the Reduction of Cardiovascular Events with Icosapent Ethyl-Intervention Trial (REDUCE-IT) were published in the New England Journal of Medicine and showed that a high dose of a purified ethyl ester of eicosapentaenoic acid (EPA) in patients at elevated cardiac risk significantly reduced cardiovascular events. Results from the trial led to US. Food and Drug Administration, Health Canada, and European Medicines Agency approval of the prescription drug icosapent ethyl for reducing cardiovascular risk in patients with elevated triglycerides, as well as updates to worldwide guidelines. But prior and subsequent studies of omega-3 fatty acid supplements that combine EPA and docosahexaenoic acid (DHA) have had mixed results.

Investigators from Brigham and Women's Hospital and elsewhere conducted a systematic review and meta-analysis of 38 randomized controlled trials of omega-3 fatty acids. Overall, they found that omega-3 fatty acids improved cardiovascular outcomes. Results, now published in eClinical Medicine, showed a significantly greater reduction in cardiovascular risk in studies of EPA alone rather than EPA+DHA supplements.

"REDUCE-IT has ushered in a new era in cardiovascular prevention," said senior author Deepak L. Bhatt, MD, MPH, the executive director of Interventional Cardiovascular Programs at the Brigham and lead investigator of the REDUCE-IT trial. "REDUCE-IT was the largest and most rigorous contemporary trial of EPA, but there have been other ones as well. Now, we can see that the totality of evidence supports a robust and consistent benefit of EPA."

Bhatt and colleagues performed a meta-analysis of 38 randomized clinical trials of omega-3 fatty acids, including trials of EPA monotherapy and EPA+DHA therapy. In total, these trials included more than 149,000 participants. They evaluated key cardiovascular outcomes, including cardiovascular mortality, non-fatal cardiovascular outcomes, bleeding, and atrial fibrillation. Overall, omega-3 fatty acids reduced cardiovascular mortality and improved cardiovascular outcomes. The trials of EPA showed higher relative reductions in cardiovascular outcomes compared to those of EPA+DHA.

The researchers note that there are crucial biological differences between EPA and DHA -- while both are considered omega-3 fatty acids, they have different chemical properties that influence their stability and strength of the effect that they can have on cholesterol molecules and cell membranes. No trials to date have studied the effects of DHA alone on cardiovascular outcomes.

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5 million deaths a year caused by global climate related abnormal temps

More than five million extra deaths a year can be attributed to abnormal hot and cold temperatures, according to a world first international study led by Monash University.

The study found deaths related to hot temperatures increased in all regions from 2000 to 2019, indicating that global warming due to climate change will make this mortality figure worse in the future.

The international research team, led by Monash University's Professor Yuming Guo, Dr Shanshan Li, and Dr Qi Zhao from Shandong University in China and published today in The Lancet Planetary Health looked at mortality and temperature data across the world from 2000 to 2019, a period when global temperatures rose by 0.26C per decade.

The study, the first to definitively link above and below optimal temperatures (corresponding to minimum mortality temperatures) to annual increases in mortality, found 9.43 per cent of global deaths could be attributed to cold and hot temperatures. This equates to 74 excess deaths for every 100,000 people, with most deaths caused by cold exposure.

The data reveals geographic differences in the impact of non-optimal temperatures on mortality, with Eastern Europe and Sub-Saharan Africa having the highest heat and cold-related excess death rates.

Importantly, cold-related death decreased 0.51 per cent from 2000 to 2019, while heat-related death increased 0.21 per cent, leading to a reduction in net mortality due to cold and hot temperatures.

The largest decline of net mortality occurred in Southeast Asia while there was temporal increase in South Asia and Europe.

Professor Guo, from the Monash University School of Public Health and Preventive Medicine, said this shows global warming may "slightly reduce the number of temperature-related deaths, largely because of the lessening in cold-related mortality, however in the long-term climate change is expected to increase the mortality burden because hot-related mortality would be continuing to increase."?.

Professor Guo said previous studies had looked at temperature-related mortality within a single country or region.

"This is the first study to get a global overview of mortality due to non-optimal temperature conditions between 2000 and 2019, the hottest period since the Pre-Industrial era,"? he said.

"Importantly, we used 43 countries' baseline data across five continents with different climates, socioeconomic and demographic conditions and differing levels of infrastructure and public health services, so the study had a large and varied sample size, unlike previous studies."

The mortality data from this groundbreaking Monash study is significantly higher than the second-largest study published in 2015, which was based on 74 million deaths across 13 countries/regions and estimated 7.7 per cent of deaths were related to cold and hot temperatures.

Professor Guo said that showed "the importance of taking data from all points of the globe, in order to get a more accurate understanding of the real impact of non-optimal temperatures under climate change."?.

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New clues to why there's so little antimatter in the universe

Imagine a dust particle in a storm cloud, and you can get an idea of a neutron's insignificance compared to the magnitude of the molecule it inhabits.

But just as a dust mote might affect a cloud's track, a neutron can influence the energy of its molecule despite being less than one-millionth its size. And now physicists at MIT and elsewhere have successfully measured a neutron's tiny effect in a radioactive molecule.

The team has developed a new technique to produce and study short-lived radioactive molecules with neutron numbers they can precisely control. They hand-picked several isotopes of the same molecule, each with one more neutron than the next. When they measured each molecule's energy, they were able to detect small, nearly imperceptible changes of the nuclear size, due to the effect of a single neutron.

The fact that they were able to see such small nuclear effects suggests that scientists now have a chance to search such radioactive molecules for even subtler effects, caused by dark matter, for example, or by the effects of new sources of symmetry violations related to some of the current mysteries of the universe.

"If the laws of physics are symmetrical as we think they are, then the Big Bang should have created matter and antimatter in the same amount. The fact that most of what we see is matter, and there is only about one part per billon of antimatter, means there is a violation of the most fundamental symmetries of physics, in a way that we can't explain with all that we know," says Ronald Fernando Garcia Ruiz, assistant professor of physics at MIT.

"Now we have a chance to measure these symmetry violations, using these heavy radioactive molecules, which have extreme sensitivity to nuclear phenomena that we cannot see in other molecules in nature," he says. "That could provide answers to one of the main mysteries of how the universe was created."

Ruiz and his colleagues have published their results today in Physical Review Letters.

A special asymmetry

Most atoms in nature host a symmetrical, spherical nucleus, with neutrons and protons evenly distributed throughout. But in certain radioactive elements like radium, atomic nuclei are weirdly pear-shaped, with an uneven distribution of neutrons and protons within. Physicists hypothesize that this shape distortion can enhance the violation of symmetries that gave origin to the matter in the universe.

"Radioactive nuclei could allow us to easily see these symmetry-violating effects," says study lead author Silviu-Marian Udrescu, a graduate student in MIT's Department of Physics. "The disadvantage is, they're very unstable and live for a very short amount of time, so we need sensitive methods to produce and detect them, fast."

Rather than attempt to pin down radioactive nuclei on their own, the team placed them in a molecule that futher amplifies the sensitivity to symmetry violations. Radioactive molecules consist of at least one radioactive atom, bound to one or more other atoms. Each atom is surrounded by a cloud of electrons that together generate an extremely high electric field in the molecule that physicists believe could amplify subtle nuclear effects, such as effects of symmetry violation.

However, aside from certain astrophysical processes, such as merging neutron stars, and stellar explosions, the radioactive molecules of interest do not exist in nature and therefore must be created artificially. Garcia Ruiz and his colleagues have been refining techniques to create radioactive molecules in the lab and precisely study their properties. Last year, they reported on a method to produce molecules of radium monofluoride, or RaF, a radioactive molecule that contains one unstable radium atom and a fluoride atom.

In their new study, the team used similar techniques to produce RaF isotopes, or versions of the radioactive molecule with varying numbers of neutrons. As they did in their previous experiment, the researchers utilized the Isotope mass Separator On-Line, or ISOLDE, facility at CERN, in Geneva, Switzerland, to produce small quantities of RaF isotopes.

The facility houses a low-energy proton beam, which the team directed toward a target -- a half-dollar-sized disc of uranium-carbide, onto which they also injected a carbon fluoride gas. The ensuing chemical reactions produced a zoo of molecules, including RaF, which the team separated using a precise system of lasers, electromagnetic fields, and ion traps.

The researchers measured each molecule's mass to estimate of the number of neutrons in a molecule's radium nucleus. They then sorted the molecules by isotopes, according to their neutron numbers.

In the end, they sorted out bunches of five different isotopes of RaF, each bearing more neutrons than the next. With a separate system of lasers, the team measured the quantum levels of each molecule.

"Imagine a molecule vibrating like two balls on a spring, with a certain amount of energy," explains Udrescu, who is a graduate student of MIT's Laboratory for Nuclear Science. "If you change the number of neutrons in one of these balls, the amount of energy could change. But one neutron is 10 million times smaller than a molecule, and with our current precision we didn't expect that changing one would create an energy difference, but it did. And we were able to clearly see this effect."

Udrescu compares the sensitivity of the measurements to being able to see how Mount Everest, placed on the surface of the sun, could, however minutely, change the sun's radius. By comparison, seeing certain effects of symmetry violation would be like seeing how the width of a single human hair would alter the sun's radius.

The results demonstrate that radioactive molecules such as RaF are ultrasensitive to nuclear effects and that their sensitivity may likely reveal more subtle, never-before-seen effects, such as tiny symmetry-violating nuclear properties, that could help to explain the universe's matter-antimmater asymmetry.

"These very heavy radioactive molecules are special and have sensitivity to nuclear phenomena that we cannot see in other molecules in nature," Udrescu says. "This shows that, when we start to search for symmetry-violating effects, we have a high chance of seeing them in these molecules."

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There's a 'man in the moon': Why our brains see human faces everywhere

It's so commonplace we barely give it a second thought, but human brains seem hardwired to see human faces where there are none -- in objects as varied as the moon, toys, plastic bottles, tree trunks and vacuum cleaners. Some have even seen an imagined Jesus in cheese on toast.

Until now scientists haven't understood exactly what the brain is doing when it processes visual signals and interprets them as representations of the human face.

Neuroscientists at the University of Sydney now say how our brains identify and analyse real human faces is conducted by the same cognitive processes that identify illusory faces.

"From an evolutionary perspective, it seems that the benefit of never missing a face far outweighs the errors where inanimate objects are seen as faces," said Professor David Alais lead author of the study from the School of Psychology.

"There is a great benefit in detecting faces quickly," he said, "but the system plays 'fast and loose' by applying a crude template of two eyes over a nose and mouth. Lots of things can satisfy that template and thus trigger a face detection response."

This facial recognition response happens lightning fast in the brain: within a few hundred milliseconds.

"We know these objects are not truly faces, yet the perception of a face lingers," Professor Alais said. "We end up with something strange: a parallel experience that it is both a compelling face and an object. Two things at once. The first impression of a face does not give way to the second perception of an object."

This error is known as "face pareidolia." It is such a common occurrence that we accept the notion of detecting faces in objects as 'normal' -- but humans do not experience this cognitive process as strongly for other phenomena.

The brain has evolved specialised neural mechanisms to rapidly detect faces and it exploits the common facial structure as a short-cut for rapid detection.

"Pareidolia faces are not discarded as false detections but undergo facial expression analysis in the same way as real faces," Professor Alais said.

Not only do we imagine faces, we analyse them and give them emotional attributes.

The findings are published today in the Proceedings of the Royal Society B.

The researchers say this expression analysis of inanimate objects is because as deeply social beings, simply detecting a face isn't enough.

"We need to read the identity of the face and discern its expression. Are they a friend or a foe? Are they happy, sad, angry, pained?" Professor Alais said.

What the study examined was whether once a pareidolia face is detected, it is subsequently analysed for facial expression, or discarded from face processing as a false detection.

The research shows that once a false face is retained by the brain it is analysed for its facial expression in the same way that a real face is.

"We showed this by presenting sequences of faces and having participants rate each face's expression on a scale ranging from angry to happy," Professor Alais said.

What was intriguing is that a known bias in judging human faces persisted with analysis of inanimate imagined faces.

A previous study undertaken by Professor Alais showed that in a Tinder-like situation of judging face after face, a bias is observed whereby the assessment of the current face is influenced by our assessment of the previous face.

The scientists tested this by mixing up real faces with pareidolia faces -- and the result was the same.

"This 'cross-over' condition is important as it shows the same underlying facial expression process is involved regardless of image type," Professor Alais said.

"This means that seeing faces in clouds is more than a child's fantasy," he said.

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Lab analysis finds near-meat and meat not nutritionally equivalent

Plant-based meat substitutes taste and chew remarkably similar to real beef, and the 13 items listed on their nutrition labels -- vitamins, fats and protein -- make them seem essentially equivalent.

But a Duke University research team's deeper examination of the nutritional content of plant-based meat alternatives, using a sophisticated tool of the science known as 'metabolomics,' shows they're as different as plants and animals.

Meat-substitute manufacturers have gone to great lengths to make the plant-based product as meaty as possible, including adding leghemoglobin, an iron-carrying molecule from soy, and red beet, berries and carrot extracts to simulate bloodiness. The texture of near-meat is thickened by adding indigestible fibers like methyl cellulose. And to bring the plant-based meat alternatives up to the protein levels of meat, they use isolated plant proteins from soy, peas, and other plant sources. Some meat-substitutes also add vitamin B12 and zinc to further replicate meat's nutrition.

However, many other components of nutrition do not appear on the labels, and that's where the products differ widely from meat, according to the study, which appears this week in Scientific Reports.

The metabolites that the scientists measured are building blocks of the body's biochemistry, crucial to the conversion of energy, signaling between cells, building structures and tearing them down, and a host of other functions. There are expected to be more than 100,000 of these molecules in biology and about half of the metabolites circulating in human blood are estimated to be derived from our diets.

"To consumers reading nutritional labels, they may appear nutritionally interchangeable," said Stephan van Vliet, a postdoctoral researcher at the Duke Molecular Physiology Institute who led the research. "But if you peek behind the curtain using metabolomics and look at expanded nutritional profiles, we found that there are large differences between meat and a plant-based meat alternative."

The Duke Molecular Physiology Institute's metabolomics core lab compared 18 samples of a popular plant-based meat alternative to 18 grass-fed ground beef samples from a ranch in Idaho. The analysis of 36 carefully cooked patties found that 171 out of the 190 metabolites they measured varied between beef and the plant-based meat substitute.

The beef contained 22 metabolites that the plant substitute did not. The plant-based substitute contained 31 metabolites that meat did not. The greatest distinctions occurred in amino acids, dipeptides, vitamins, phenols, and types of saturated and unsaturated fatty acids found in these products.

Several metabolites known to be important to human health were found either exclusively or in greater quantities in beef, including creatine, spermine, anserine, cysteamine, glucosamine, squalene, and the omega-3 fatty acid DHA. "These nutrients have potentially important physiological, anti-inflammatory, and or immunomodulatory roles," the authors said in the paper.

"These nutrients are important for our brain and other organs including our muscles" van Vliet said. "But some people on vegan diets (no animal products), can live healthy lives -- that's very clear." Besides, the plant-based meat alternative contained several beneficial metabolites not found in beef such as phytosterols and phenols.

"It is important for consumers to understand that these products should not be viewed as nutritionally interchangeable, but that's not to say that one is better than the other," said van Vliet, a self-described omnivore who enjoys a plant-heavy diet but also eats meat. "Plant and animal foods can be complementary, because they provide different nutrients."

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Climate changed the size of our bodies and, to some extent, our brains

An interdisciplinary team of researchers, led by the Universities of Cambridge and Tübingen, has gathered measurements of body and brain size for over 300 fossils from the genus Homo found across the globe. By combining this data with a reconstruction of the world's regional climates over the last million years, they have pinpointed the specific climate experienced by each fossil when it was a living human.

The study reveals that the average body size of humans has fluctuated significantly over the last million years, with larger bodies evolving in colder regions. Larger size is thought to act as a buffer against colder temperatures: less heat is lost from a body when its mass is large relative to its surface area. The results are published today in the journal Nature Communications.

Our species, Homo sapiens, emerged around 300,000 years ago in Africa. The genus Homo has existed for much longer, and includes the Neanderthals and other extinct, related species such as Homo habilis and Homo erectus.

A defining trait of the evolution of our genus is a trend of increasing body and brain size; compared to earlier species such as Homo habilis, we are 50% heavier and our brains are three times larger. But the drivers behind such changes remain highly debated.

"Our study indicates that climate -- particularly temperature -- has been the main driver of changes in body size for the past million years," said Professor Andrea Manica, a researcher in the University of Cambridge's Department of Zoology who led the study.

He added: "We can see from people living today that those in warmer climates tend to be smaller, and those living in colder climates tend to be bigger. We now know that the same climatic influences have been at work for the last million years."

The researchers also looked at the effect of environmental factors on brain size in the genus Homo, but correlations were generally weak. Brain size tended to be larger when Homo was living in habitats with less vegetation, like open steppes and grasslands, but also in ecologically more stable areas. In combination with archaeological data, the results suggest that people living in these habitats hunted large animals as food -- a complex task that might have driven the evolution of larger brains.

"We found that different factors determine brain size and body size -- they're not under the same evolutionary pressures. The environment has a much greater influence on our body size than our brain size," said Dr Manuel Will at the University of Tubingen, Germany, first author of the study.

He added: "There is an indirect environmental influence on brain size in more stable and open areas: the amount of nutrients gained from the environment had to be sufficient to allow for the maintenance and growth of our large and particularly energy-demanding brains."

This research also suggests that non-environmental factors were more important for driving larger brains than climate, prime candidates being the added cognitive challenges of increasingly complex social lives, more diverse diets, and more sophisticated technology.

The researchers say there is good evidence that human body and brain size continue to evolve. The human physique is still adapting to different temperatures, with on average larger-bodied people living in colder climates today. Brain size in our species appears to have been shrinking since the beginning of the Holocene (around 11,650 years ago). The increasing dependence on technology, such as an outsourcing of complex tasks to computers, may cause brains to shrink even more over the next few thousand years.

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Sculpted by starlight: A meteorite witness to the solar system's birth

In 2011, scientists confirmed a suspicion: There was a split in the local cosmos. Samples of the solar wind brought back to Earth by the Genesis mission definitively determined oxygen isotopes in the sun differ from those found on Earth, the moon and the other planets and satellites in the solar system.

Early in the solar system's history, material that would later coalesce into planets had been hit with a hefty dose of ultraviolet light, which can explain this difference. Where did it come from? Two theories emerged: Either the ultraviolet light came from our then-young sun, or it came from a large nearby star in the sun's stellar nursery.

Now, researchers from the lab of Ryan Ogliore, assistant professor of physics in Arts & Sciences at Washington University in St. Louis, have determined which was responsible for the split. It was most likely light from a long-dead massive star that left this impression on the rocky bodies of the solar system. The study was led by Lionel Vacher, a postdoctoral research associate in the physics department's Laboratory for Space Sciences.

Their results are published in the journal Geochimica et Cosmochimica Acta.

"We knew that we were born of stardust: that is, dust created by other stars in our galactic neighborhood were part of the building blocks of the solar system," Ogliore said.

"But this study showed that starlight had a profound effect on our origins as well."

*Tiny time capsule

All of that profundity was packed into a mere 85 grams of rock, a piece of an asteroid found as a meteorite in Algeria in 1990, named Acfer 094. Asteroids and planets formed from the same presolar material, but they've been influenced by different natural processes. The rocky building blocks that coalesced to form asteroids and planets were broken up and battered; vaporized and recombined; and compressed and heated. But the asteroid that Acfer 094 came from managed to survive for 4.6 billion years mostly unscathed.

"This is one of the most primitive meteorites in our collection," Vacher said. "It was not heated significantly. It contains porous regions and tiny grains that formed around other stars. It is a reliable witness to the solar system's formation."

Acfer 094 is also the only meteorite that contains cosmic symplectite, an intergrowth of iron-oxide and iron-sulfide with extremely heavy oxygen isotopes -- a significant finding.

The sun contains about 6% more of the lightest oxygen isotope compared with the rest of the solar system. That can be explained by ultraviolet light shining on the solar system's building blocks, selectively breaking apart carbon monoxide gas into its constituent atoms. That process also creates a reservoir of much heavier oxygen isotopes. Until cosmic symplectite, however, no one had found this heavy isotope signature in samples of solar system materials.

With only three isotopes, however, simply finding the heavy oxygen isotopes wasn't enough to answer the question of the origin of the light. Different ultraviolet spectra could have created the same result.

"That's when Ryan came up with the idea of sulfur isotopes," Vacher said.

Sulfur's four isotopes would leave their marks in different ratios depending on the spectrum of ultraviolet light that irradiated hydrogen sulfide gas in the proto-solar system. A massive star and a young sun-like star have different ultraviolet spectra.

Cosmic symplectite formed when ices on the asteroid melted and reacted with small pieces of iron-nickel metal. In addition to oxygen, cosmic symplectite contains sulfur in iron sulfide. If its oxygen witnessed this ancient astrophysical process -- which led to the heavy oxygen isotopes -- perhaps its sulfur did, too.

"We developed a model," Ogliore said. "If I had a massive star, what isotope anomalies would be created? What about for a young, sun-like star? The precision of the model depends on the experimental data. Fortunately, other scientists have done great experiments on what happens to isotope ratios when hydrogen sulfide is irradiated by ultraviolet light."

Sulfur and oxygen isotope measurements of cosmic symplectite in Acfer 094 proved another challenge. The grains, tens of micrometers in size and a mixture of minerals, required new techniques on two different in-situ secondary-ion mass spectrometers: the NanoSIMS in the physics department (with assistance from Nan Liu, research assistant professor in physics) and the 7f-GEO in the Department of Earth and Planetary Sciences, also in Arts & Sciences.

*Putting the puzzle together

It helped to have friends in earth and planetary sciences, particularly David Fike, professor of earth and planetary sciences and director of Environmental Studies in Arts & Sciences, and Clive Jones, research scientist in earth and planetary sciences.

"They are experts in high-precision in-situ sulfur isotope measurements for biogeochemistry," Ogliore said. "Without this collaboration, we would not have achieved the precision we needed to differentiate between the young sun and massive star scenarios."

The sulfur isotope measurements of cosmic symplectite were consistent with ultraviolet irradiation from a massive star, but did not fit the UV spectrum from the young sun. The results give a unique perspective on the astrophysical environment of the sun's birth 4.6 billion years ago. Neighboring massive stars were likely close enough that their light affected the solar system's formation. Such a nearby massive star in the night sky would appear brighter than the full moon.

Today, we can look to the skies and see a similar origin story play out elsewhere in the galaxy.

"We see nascent planetary systems, called proplyds, in the Orion nebula that are being photoevaporated by ultraviolet light from nearby massive O and B stars," Vacher said.

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Methane in plumes of Saturn's moon Enceladus: Possible signs of life?

An unknown methane-producing process is likely at work in the hidden ocean beneath the icy shell of Saturn's moon Enceladus, suggests a new study published in Nature Astronomy by scientists at the University of Arizona and Paris Sciences & Lettres University.

Giant water plumes erupting from Enceladus have long fascinated scientists and the public alike, inspiring research and speculation about the vast ocean that is believed to be sandwiched between the moon's rocky core and its icy shell. Flying through the plumes and sampling their chemical makeup, the Cassini spacecraft detected a relatively high concentration of certain molecules associated with hydrothermal vents on the bottom of Earth's oceans, specifically dihydrogen, methane and carbon dioxide. The amount of methane found in the plumes was particularly unexpected.

"We wanted to know: Could Earthlike microbes that 'eat' the dihydrogen and produce methane explain the surprisingly large amount of methane detected by Cassini?" said Regis Ferriere, an associate professor in the University of Arizona Department of Ecology and Evolutionary Biology and one of the study's two lead authors. "Searching for such microbes, known as methanogens, at Enceladus' seafloor would require extremely challenging deep-dive missions that are not in sight for several decades."

Ferriere and his team took a different, easier route: They constructed mathematical models to calculate the probability that different processes, including biological methanogenesis, might explain the Cassini data.

The authors applied new mathematical models that combine geochemistry and microbial ecology to analyze Cassini plume data and model the possible processes that would best explain the observations. They conclude that Cassini's data are consistent either with microbial hydrothermal vent activity, or with processes that don't involve life forms but are different from the ones known to occur on Earth.

On Earth, hydrothermal activity occurs when cold seawater seeps into the ocean floor, circulates through the underlying rock and passes close by a heat source, such as a magma chamber, before spewing out into the water again through hydrothermal vents. On Earth, methane can be produced through hydrothermal activity, but at a slow rate. Most of the production is due to microorganisms that harness the chemical disequilibrium of hydrothermally produced dihydrogen as a source of energy, and produce methane from carbon dioxide in a process called methanogenesis.

The team looked at Enceladus' plume composition as the end result of several chemical and physical processes taking place in the moon's interior. First, the researchers assessed what hydrothermal production of dihydrogen would best fit Cassini's observations, and whether this production could provide enough "food" to sustain a population of Earthlike hydrogenotrophic methanogens. To do that, they developed a model for the population dynamics of a hypothetical hydrogenotrophic methanogen, whose thermal and energetic niche was modeled after known strains from Earth.

The authors then ran the model to see whether a given set of chemical conditions, such as the dihydrogen concentration in the hydrothermal fluid, and temperature would provide a suitable environment for these microbes to grow. They also looked at what effect a hypothetical microbe population would have on its environment -- for example, on the escape rates of dihydrogen and methane in the plume.

"In summary, not only could we evaluate whether Cassini's observations are compatible with an environment habitable for life, but we could also make quantitative predictions about observations to be expected, should methanogenesis actually occur at Enceladus' seafloor," Ferriere explained.

The results suggest that even the highest possible estimate of abiotic methane production -- or methane production without biological aid -- based on known hydrothermal chemistry is far from sufficient to explain the methane concentration measured in the plumes. Adding biological methanogenesis to the mix, however, could produce enough methane to match Cassini's observations.

"Obviously, we are not concluding that life exists in Enceladus' ocean," Ferriere said. "Rather, we wanted to understand how likely it would be that Enceladus' hydrothermal vents could be habitable to Earthlike microorganisms. Very likely, the Cassini data tell us, according to our models.

"And biological methanogenesis appears to be compatible with the data. In other words, we can't discard the 'life hypothesis' as highly improbable. To reject the life hypothesis, we need more data from future missions," he added.

The authors hope their paper provides guidance for studies aimed at better understanding the observations made by Cassini and that it encourages research to elucidate the abiotic processes that could produce enough methane to explain the data.

For example, methane could come from the chemical breakdown of primordial organic matter that may be present in Enceladus' core and that could be partially turned into dihydrogen, methane and carbon dioxide through the hydrothermal process. This hypothesis is very plausible if it turns out that Enceladus formed through the accretion of organic-rich material supplied by comets, Ferriere explained.

"It partly boils down to how probable we believe different hypotheses are to begin with," he said. "For example, if we deem the probability of life in Enceladus to be extremely low, then such alternative abiotic mechanisms become much more likely, even if they are very alien compared to what we know here on Earth."

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Vertical greenery can act as a stress buffer

Vertical greenery 'planted' on the exterior of buildings may help to buffer people against stress, a Nanyang Technological University, Singapore (NTU Singapore) study has found.

The benefits of nature on mental health and for wellbeing have long been recognised, and now a team of NTU Singapore psychologists has used Virtual Reality (VR) to examine whether vertical greenery has a stress buffering effect (ability to moderate the detrimental consequences of stress) in an urban environment.

Using VR headsets, 111 participants were asked to walk down a virtual street for five minutes. Participants were randomly assigned to either a street that featured rows of planted greenery (e.g., on balconies, walls, and pillars of buildings), or one with only buildings that had green painted walls in place of green plants. The virtual environments used in the study was developed by the NTU research team.

To match a real-world experience, heavy traffic noise was played as the participants walked through the virtual street. Heart rate variability, which is a physiological indicator of stress, was continuously monitored using a portable electrocardiogram (ECG) device.

The study found that those who viewed buildings which only had green paint experienced a signi?cant increase in stress as recorded by one measure of heart rate variability, while those who viewed the buildings with the green plants did not experience any change in stress.

Following the experiment, participants answered a questionnaire that assessed their positive (e.g., interested, excited) and negative emotions (e.g., upset, hostile), and the level of anxiety they were feeling.

Participants reported feeling less positive when walking through the street with buildings covered by only green walls, while those walking through the street with buildings covered by plants did not report feeling either more or less positive.

The findings published in the peer-reviewed academic journal Landscape and Urban Planning, have implications for the well-being of people living in urban areas and can guide greening efforts in cities, say the researchers.

Walls of greenery can help lower ambient temperature, which reduces energy consumption from cooling systems. They can also reduce carbon emissions and lessen the effect of 'urban heat island' -- a phenomenon where city centres experience much warmer temperatures than less populated areas because of limited greenery and a high concentration of built structures.

While vertical greenery is often planted for these sustainability benefits, the NTU study is one of the first to explore its contribution to mental health, and the authors say that it provides additional impetus for city planners to adopt a 'biophilic design' concept -- an approach to architecture that seeks to connect people more closely to nature -- which is favoured in cities such as Singapore, Wellington (NZ), and San Francisco.

Principal investigator of the study, Associate Professor Lin Qiu from the Psychology programme at the NTU School of Social Sciences said, "With urbanisation, more people are expected to be living in urban areas globally in future. It is thus important for urban city planners and architects to understand factors that can contribute to healthy living, as urban planning can have a direct impact on quality of life for the population. Our work can guide efforts to green cities, by providing evidence of how vertical greenery can be a viable way to integrate nature into our built environment and promote mental health."

Co-lead author of the research, Sarah Chan, a Ph.D. candidate from the Interdisciplinary Graduate Programme at NTU said, "Our ?ndings have important practical implications for city planning and design, especially for high density urban areas that face land constraints. It provides evidence that vertical greenery systems, which make use of vertical structures above-ground, may help moderate the detrimental consequences of stress.

"While previous studies looked at effects of green vegetation, the fact that the colour green could simply be a primitive visual feature, resulting in positive effects, was not considered. Thanks to emerging technology like VR, we overcame this limitation and were able to use a control condition, matching vertical greenery with the colour green in our study."

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New report aims to improve VR use in healthcare education

A new report that could help improve how immersive technologies such as Virtual Reality (VR) and Augmented Reality (AR) are used in healthcare education and training has been published with significant input from the University of Huddersfield.

Professor David Peebles, Director of the University's Centre for Cognition and Neuroscience, and Huddersfield PhD graduate Matthew Pears contributed to the report -- 'Immersive technologies in healthcare training and education: Three principles for progress' -- recently published by the University of Leeds with input from range of academics, technologists and health professionals.

The principles have also been expanded upon in a letter to the prestigious journal BMJ Simulation and Technology Enhanced Learning.

The Huddersfield contribution to the report stems from research conducted over several years, which involved another former Huddersfield PhD researcher, Yeshwanth Pulijala, and Professor Eunice Ma, now with Falmouth University.

"Yeshwanth had an interest in technology and education, and in using VR for dentistry training. Matthew was looking at soft skills and situation awareness, which could be applied to investigating how dentists were able to keep a track of what was going on around them. They were similar subjects, although with different emphases, and so it seemed a natural area for collaboration."

With only a relatively small number of dental schools in the UK, the quartet visited seven dental schools in India in early 2017, with support from travel grants from Santander Bank, to test their VR-based training materials on students. The experience gained from that visit contributed to both researchers' PhDs, and ultimately led to the involvement of Professor Peebles and Matthew Pears in the new report.

The report argues for greater standardisation of how to use immersive technologies in healthcare training and education. As Professor Peebles explains, "It's about developing a set of principles and guidelines for the use of immersive technology in medical treatment. Immersive technology is becoming increasingly popular and, as the technology is advancing, it's becoming clear that there is great potential to make training more accessible and effective.

"It is important, however, that research is driven by the needs of the user and existing evidence rather than the technology. Rather than thinking 'we have a new bit of VR or AR kit, what can we do with it?', we should be looking at the problem that needs solving -- what are the learning needs, so how do we use technology to solve it?

"Developing immersive training materials can be very time-consuming and difficult to evaluate properly. Getting surgeons and medical students to take time out to test your VR training is challenging. In our case we were lucky to have a surgeon, Professor Ashraf Ayoub, a Professor of Oral and Maxillofacial Surgery at the University of Glasgow, who granted us permission to film a surgical procedure that was then transformed into a 3D environment to train students about situation awareness while in the operating theatre."

Professor Peebles hopes the work so far will provide a basis for more investigations that could help get the most from the potential that VR and immersive technology have to offer.

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Muscles retain positional memory from fetal life

A research collaboration based in Kumamoto University, Japan has discovered that muscles and the resident stem cells (satellite cells) responsible for muscle regeneration retain memory of their location in the body. This positional memory was found to be based on the expression pattern of the homeobox (Hox) gene cluster, which is responsible for shaping the body during fetal life. These findings are expected to provide clues to elucidate the pathogenesis of muscle diseases such as muscular dystrophy, in which the position of muscle vulnerability varies depending on the type of muscle, and to help develop regenerative medicine based on positional memory.

There are various types of the intractable muscle disease muscular dystrophy and each type has a different symptom location. Similarly, age-related muscle fragility (sarcopenia) does not occur evenly throughout the body. The physical location of the symptoms of these diseases cannot be explained by differences in muscle fiber types or physical activity patterns alone, and requires a new perspective to elucidate their respective pathogeneses.

The developmental origin of cells that form muscles differ in the fetal stage. For example, most of the craniofacial muscles originate from the cranial mesoderm, while the limb muscles originate from the body segments. Development of limb and craniofacial muscles in the fetal period involves specific molecular mechanisms that depends on their origin. However, differences in the properties of mature skeletal muscle depending on body position after birth have not been fully discussed. Thus, a research collaboration worked to visualize the body's positional information by studying the epigenomic state and gene expression patterns of skeletal muscle and the muscle stem cells responsible for regeneration.

Using skeletal muscle and associated muscle stem cells isolated from the heads and hind limbs of adult mice, researchers investigated positional specificity at the epigenomic level using DNA methylome analysis. They found characteristic differences in the DNA methylation status at the homeobox (Hox) loci. Among four regions, A to D, the Hox-A locus in particular had an overall DNA hypermethylation state in hindlimb skeletal muscle and muscle stem cells compared to the head. Additionally, both skeletal muscle and muscle stem cells in the hind limbs showed high expression of the Hox-A gene. Many of these Hox-A genes reflected expression patterns in the fetal period. These findings suggest that skeletal muscle and muscle stem cells remember positional information during fetal life, and that epigenomic regulation by DNA methylation may be involved in positional memory.

The researchers then focused on the Hoxa10 gene, which was highly expressed only in the limb muscles. When hindlimb-derived muscle stem cells expressing Hoxa10 were isolated and transplanted into craniofacial muscles that do not express Hoxa10, Hoxa10 gene expression became detectable in the craniofacial muscles. In other words, hindlimb-derived muscle stem cells were able to innervate the craniofacial muscle with strong retention of positional memory even after ectopic transplantation.

They then created mice lacking the Hoxa10 gene in muscle stem cells to analyze its function. A Hoxa10 deficiency severely impaired the regeneration of hindlimb muscles but had no effect on craniofacial muscle regeneration. A detailed investigation of the mechanism behind the hindlimb muscle regeneration disorder revealed that it is caused by genomic instability due to abnormal chromosome distribution during muscle stem cell division. Furthermore, analysis of human head and leg muscle stem cells also showed that only leg muscle cells expressed the HOX-A gene and that its inhibition resulted in abnormal cell division, confirming that muscle cell positional memory is retained in humans and mice.

This research suggest that the positional memory of muscle stem cells based on the position-specific distribution of Hox gene expression may determine the position-specific properties of skeletal muscle, rather than merely persisting from fetal life.

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Kepler telescope glimpses population of free-floating planets

Tantalising evidence has been uncovered for a mysterious population of "free-floating" planets, planets that may be alone in deep space, unbound to any host star. The results include four new discoveries that are consistent with planets of similar masses to Earth, published today in Monthly Notices of the Royal Astronomical Society.

The study, led by Iain McDonald of the University of Manchester, UK, (now based at the Open University, UK) used data obtained in 2016 during the K2 mission phase of NASA's Kepler Space Telescope. During this two-month campaign, Kepler monitored a crowded field of millions of stars near the centre of our Galaxy every 30 minutes in order to find rare gravitational microlensing events.

The study team found 27 short-duration candidate microlensing signals that varied over timescales of between an hour and 10 days. Many of these had been previously seen in data obtained simultaneously from the ground. However, the four shortest events are new discoveries that are consistent with planets of similar masses to Earth.

These new events do not show an accompanying longer signal that might be expected from a host star, suggesting that these new events may be free-floating planets. Such planets may perhaps have originally formed around a host star before being ejected by the gravitational tug of other, heavier planets in the system.

Predicted by Albert Einstein 85 years ago as a consequence of his General Theory of Relativity, microlensing describes how the light from a background star can be temporarily magnified by the presence of other stars in the foreground. This produces a short burst in brightness that can last from hours to a few days. Roughly one out of every million stars in our Galaxy is visibly affected by microlensing at any given time, but only a few percent of these are expected to be caused by planets.

Kepler was not designed to find planets using microlensing, nor to study the extremely dense star fields of the inner Galaxy. This meant that new data reduction techniques had to be developed to look for signals within the Kepler dataset.

Iain notes: "These signals are extremely difficult to find. Our observations pointed an elderly, ailing telescope with blurred vision at one the most densely crowded parts of the sky, where there are already thousands of bright stars that vary in brightness, and thousands of asteroids that skim across our field. From that cacophony, we try to extract tiny, characteristic brightenings caused by planets, and we only have one chance to see a signal before it's gone. It's about as easy as looking for the single blink of a firefly in the middle of a motorway, using only a handheld phone."

Co-author Eamonn Kerins of the University of Manchester also comments, "Kepler has achieved what it was never designed to do, in providing further tentative evidence for the existence of a population of Earth-mass, free-floating planets. Now it passes the baton on to other missions that will be designed to find such signals, signals so elusive that Einstein himself thought that they were unlikely ever to be observed. I am very excited that the upcoming ESA Euclid mission could also join this effort as an additional science activity to its main mission."

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Mystery of heavy elements in galactic cosmic rays

Scientists have used data from the Southwest Research Institute-led Magnetospheric Multiscale (MMS) mission to explain the presence of energetic heavy elements in galactic cosmic rays (GCRs). GCRs are composed of fast-moving energetic particles, mostly hydrogen ions called protons, the lightest and most abundant elements in the universe. Scientists have long debated how trace amounts of heavy ions in GCRs are accelerated.

The supernova explosion of a dying star creates massive shockwaves that propagate through the surrounding space, accelerating ions in their path to very high energies, creating GCRs. How heavy ions are energized and accelerated is important because they affect the redistribution of mass throughout the universe and are essential for the formation of even heavier and more chemically complex elements. They also influence how we perceive astrophysical structures.

"Heavy ions are thought to be insensitive to an incoming shockwave because they are less abundant, and the shock energy is overwhelmingly consumed by the preponderance of protons. Visualize standing on a beach as waves move the sand under your feet, while you remain in place," said SwRI's Dr. Hadi Madanian, the lead author of the paper about this research published in Astrophysical Journal Letters. "However, that classical view of how heavy ions behave under shock conditions is not always what we have seen in high-resolution MMS observations of the near-Earth space environment."

Shock phenomena also occur in the near-Earth environment. The Sun's magnetic field is carried through interplanetary space by the supersonic solar wind flow, which is obstructed and diverted by the Earth's magnetosphere, a bubble of protection around our home planet. This interaction region is called the bow shock due to its curved shape, comparable to the bow waves that occur as a boat travels through water. The Earth's bow shock forms at a much smaller scale than supernova shocks. However, at times, conditions of this small shock resemble those of supernova remnants. The team used high-resolution in-situ measurements from the MMS spacecraft at the bow shock to study how heavy ions are accelerated.

"We observed intense amplification of the magnetic field near the bow shock, a known property associated with strong shocks such as supernova remnants. We then analyzed how different ion species behaved as they encountered the bow shock," Madanian said. "We found that these enhanced fields significantly modify the trajectory of heavy ions, redirecting them into the acceleration zone of the shock."

While this behavior was not expected to occur for heavy ions, the team identified direct evidence for this process in alpha particles, helium ions that are four times more massive than protons and have twice the charge.

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Neanderthal artists? Bones decorated over 50,000 years ago

Since the discovery of the first fossil remains in the 19th century, the image of the Neanderthal has been one of a primitive hominin. People have known for a long time that Neanderthals were able to effectively fashion tools and weapons. But could they also make ornaments, jewellery or even art? A research team led by the University of Göttingen and the Lower Saxony State Office for Heritage has analysed a new find from the Unicorn Cave (Einhornhöhle) in the Harz Mountains. The researchers conclude that, in fact, Neanderthals, genetically the closest relative to modern humans, had remarkable cognitive abilities. The results of the study were published in Nature Ecology and Evolution.

Working with the Unicornu Fossile society, the scientists have been carrying out new excavations at the Unicorn Cave in the Harz Mountains since 2019. For the first time, they succeeded in uncovering well-preserved layers of cultural artefacts from the Neanderthal period in the cave's ruined entrance area. Among the preserved remains from a hunt, an inconspicuous foot bone turned out to be a sensational discovery. After removing the soil sticking to the bone, an angular pattern of six notches was revealed. "We quickly realised that these were not marks made from butchering the animal but were clearly decorative," says the excavation leader Dr Dirk Leder of the Lower Saxony State Office for Heritage. The carved notches could then be analysed with 3D microscopy at the Department of Wood Biology and Wood Products at Göttingen University.

To make a scientific comparison, the team carried out experiments with the foot bones of today's cattle. They showed that the bone probably had to be boiled first in order to carve the pattern into the softened bone surface with stone tools and the work would take about 1.5 hours. The small ancient foot bone that had been discovered was identified as coming from a giant deer (Megaloceros giganteus). "It is probably no coincidence that the Neanderthal chose the bone of an impressive animal with huge antlers for his or her carving," says Professor Antje Schwalb from the Technical University of Braunschweig, who is involved in the project.

The team of Leibniz laboratory at Kiel University dated the carved bone at over 51,000 years using radiocarbon dating technology. This is the first time that anyone has successfully directly dated an object that must have been carved by Neanderthals. Until now, a few ornamental objects from the time of the last Neanderthals in France were known. However, these finds, which are about 40,000 years old, are considered by many to be copies of pendants made by anatomically modern humans because by this time they had already spread to parts of Europe. Decorative objects and small ivory sculptures have survived from cave sites of modern humans on the Swabian Alb in Baden-Württemberg and these were found at about the same time.

"The fact that the new find from the Unicorn Cave dates from so long ago shows that Neanderthals were already able to independently produce patterns on bones and probably also communicate using symbols thousands of years before the arrival of modern humans in Europe," says project leader Professor Thomas Terberger from Göttingen University's Department for Prehistory and Early History, and the Lower Saxony State Office for Heritage. "This means that the creative talents of the Neanderthals must have developed independently. The bone from the Unicorn Cave thus represents the oldest decorated object in Lower Saxony and one of the most important finds from the Neanderthal period in Central Europe."

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Memory making involves extensive DNA breaking

The urgency to remember a dangerous experience requires the brain to make a series of potentially dangerous moves: Neurons and other brain cells snap open their DNA in numerous locations -- more than previously realized, according to a new study -- to provide quick access to genetic instructions for the mechanisms of memory storage.

The extent of these DNA double-strand breaks (DSBs) in multiple key brain regions is surprising and concerning, said study senior author Li-Huei Tsai, Picower Professor of Neuroscience at MIT and director of The Picower Institute for Learning and Memory, because while the breaks are routinely repaired, that process may become more flawed and fragile with age. Tsai's lab has shown that lingering DSBs are associated with neurodegeneration and cognitive decline and that repair mechanisms can falter.

"We wanted to understand exactly how widespread and extensive this natural activity is in the brain upon memory formation because that can give us insight into how genomic instability could undermine brain health down the road," said Tsai, who is also a professor in the Department of Brain and Cognitive Sciences and a leader of MIT's Aging Brain Initiative. "Clearly memory formation is an urgent priority for healthy brain function but these new results showing that several types of brain cells break their DNA in so many places to quickly express genes is still striking."

Tracking breaks

In 2015, Tsai's lab provided the first demonstration that neuronal activity caused DSBs and that they induced rapid gene expression. But those findings, mostly made in lab preparations of neurons, did not capture the full extent of the activity in the context of memory formation in a behaving animal and did not investigate what happened in cells other than neurons.

In the new study published July 1 in PLOS ONE, lead author and former graduate student Ryan Stott and co-author and former research technician Oleg Kritsky sought to investigate the full landscape of DSB activity in learning and memory. To do so, they gave mice little electrical zaps to the feet when they entered a box, to condition a fear memory of that context. They then used several methods to assess DSBs and gene expression in the brains of the mice over the next half hour, particularly among a variety of cell types in the prefrontal cortex and hippocampus, two regions essential for the formation and storage of conditioned fear memories. They also made measurements in the brains of mice who did not experience the foot shock to establish a baseline of activity for comparison.

The creation of a fear memory doubled the number of DSBs among neurons in the hippocampus and the prefrontal cortex, affecting more than 300 genes in each region. Among 206 affected genes common to both regions, the researchers then looked at what those genes do. Many were associated with the function of the connections neurons make with each other, called synapses. This makes sense because learning arises when neurons change their connections (a phenomenon called "synaptic plasticity") and memories are formed when groups of neurons connect together into ensembles called engrams.

"Many genes essential for neuronal function and memory formation, and significantly more of them than expected based on previous observations in cultured neurons...are potentially hotspots of DSB formation," the authors wrote in the study.

In another analysis, the researchers confirmed through measurements of RNA that the increase in DSBs indeed correlated closely with increased transcription and expression of affected genes, including ones affecting synapse function, as quickly as 10-30 minutes after the foot shock exposure.

"Overall, we find transcriptional changes are more strongly associated with [DSBs] in the brain than anticipated," they wrote. "Previously we observed 20 gene-associated [DSB] loci following stimulation of cultured neurons, while in the hippocampus and prefrontal cortex we see more than 100-150 gene associated [DSB] loci that are transcriptionally induced."

Snapping with stress

In the analysis of gene expression, the neuroscientists looked at not only neurons but also non-neuronal brain cells, or glia, and found that they also showed changes in expression of hundreds of genes after fear conditioning. Glia called astrocytes are known to be involved in fear learning, for instance, and they showed significant DSB and gene expression changes after fear conditioning.

Among the most important functions of genes associated with fear conditioning-related DSBs in glia was the response to hormones. The researchers therefore looked to see which hormones might be particularly involved and discovered that it was glutocortocoids, which are secreted in response to stress. Sure enough, the study data showed that in glia, many of the DSBs that occurred following fear conditioning occurred at genomic sites related to glutocortocoid receptors. Further tests revealed that directly stimulating those hormone receptors could trigger the same DSBs that fear conditioning did and that blocking the receptors could prevent transcription of key genes after fear conditioning.

Tsai said the finding that glia are so deeply involved in establishing memories from fear conditioning is an important surprise of the new study.

"The ability of glia to mount a robust transcriptional response to glutocorticoids suggest that glia may have a much larger role to play in the response to stress and its impact on the brain during learning than previously appreciated," she and her co-authors wrote.

Damage and danger?

More research will have to be done to prove that the DSBs required for forming and storing fear memories are a threat to later brain health, but the new study only adds to evidence that it may be the case, the authors said.

"Overall we have identified sites of DSBs at genes important for neuronal and glial functions, suggesting that impaired DNA repair of these recurrent DNA breaks which are generated as part of brain activity could result in genomic instability that contribute to aging and disease in the brain," they wrote.

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Astronomers discover an oversized black hole population in the star cluster Palomar 5

Palomar 5 is a unique star cluster. This is firstly because it is one of the "fluffiest" clusters in the halo of our Galaxy, with the average distance between the stars being a few light-years, comparable to the distance from the Sun to the nearest star. Secondly, it has a specular stellar stream associated with it that spans more than 20 degrees across the sky. In a paper published today in Nature Astronomy, an international team of astronomers and astrophysicists led by the University of Barcelona show that both distinguishing features of Palomar 5 are likely the result of an oversized black hole population of more than 100 black holes in the center of the cluster.

"The number of black holes is roughly three times larger than expected from the number of stars in the cluster, and it means that more than 20% of the total cluster mass is made up of black holes. They each have a mass of about 20 times the mass of the Sun, and they formed in supernova explosions at the end of the lives of massive stars, when the cluster was still very young" says Prof Mark Gieles, from the Institute of Cosmos Sciences of the University of Barcelona (ICCUB) and lead author of the paper.

Tidal streams are streams of stars that were ejected from disrupting star clusters or dwarf galaxies. In the last few years, nearly thirty thin streams have been discovered in the Milky Way halo. "We do not know how these streams form, but one idea is that they are disrupted star clusters. However, none of the recently discovered streams have a star cluster associated with them, hence we can not be sure. So, to understand how these streams formed, we need to study one with a stellar system associated with it. Palomar 5 is the only case, making it a Rosetta Stone for understanding stream formation and that is why we studied it in detail" explains Gieles.

The authors simulate the orbits and the evolution of each star from the formation of the cluster until the final dissolution. They varied the initial properties of the cluster until a good match with observations of the stream and the cluster was found. The team finds that Palomar 5 formed with a lower black hole fraction, but stars escaped more efficiently than black holes, such that the black hole fraction gradually increased. The black holes dynamically puffed up the cluster in gravitational slingshot interactions with stars, which led to even more escaping stars and the formation of the stream. Just before it completely dissolves -- roughly a billion years from now -- the cluster will consist entirely of black holes. "This work has helped us understand that even though the fluffy Palomar 5 cluster has the brightest and longest tails of any cluster in the Milky Way, it is not unique. Instead, we believe that many similarly puffed up, black hole-dominated clusters have already disintegrated in the Milky Way tides to form the recently discovered thin stellar streams" says co-author Dr. Denis Erkal at the University of Surrey.

Gieles points out that in this paper "we have shown that the presence of a large black hole population may have been common in all the clusters that formed the streams." This is important for our understanding of globular cluster formation, the initial masses of stars and the evolution of massive stars. This work also has important implications for gravitational waves. "It is believed that a large fraction of binary black hole mergers form in star clusters. A big unknown in this scenario is how many black holes there are in clusters, which is hard to constrain observationally because we can not see black holes. Our method gives us a way to learn how many BHs there are in a star cluster by looking at the stars they eject.'', says Dr. Fabio Antonini from Cardiff University, a co-author of the paper.

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Solving a long-standing mystery about the desert's rock art canvas

Wander around a desert most anywhere in the world, and eventually you'll notice dark-stained rocks, especially where the sun shines most brightly and water trickles down or dew gathers. In some spots, if you're lucky, you might stumble upon ancient art -- petroglyphs -- carved into the stain. For years, however, researchers have understood more about the petroglyphs than the mysterious dark stain, called rock varnish, in which they were drawn.

In particular, science has yet to come to a conclusion about where rock varnish, which is unusually rich in manganese, comes from.

Now, scientists at the California Institute of Technology, the Department of Energy's SLAC National Accelerator Laboratory and elsewhere think they have an answer. According to a recent paper in Proceedings of the National Academy of Sciences, rock varnish is left behind by microbial communities that use manganese to defend against the punishing desert sun.

The mystery of rock varnish is old, said Usha Lingappa, a graduate student at Caltech and the study's lead author. "Charles Darwin wrote about it, Alexander von Humboldt wrote about it," she said, and there is a long-standing debate about whether it has a biological or inorganic origin.

But, Lingappa said, she and her colleagues didn't actually set out to understand where rock varnish comes from. Instead, they were interested in how microbial ecosystems in the desert interact with rock varnish. To do so, they deployed as many techniques as they could come up with: DNA sequencing, mineralogical analyses, electron microscopy, and -- aided by Stanford Synchroton Radiation Lightsource (SSRL) scientist Samuel Webb -- advanced X-ray spectroscopy methods that could map different kinds of manganese and other elements within samples of rock varnish.

"By combining these different perspectives, maybe we could draw a picture of this ecosystem and understand it in new ways," Lingappa said. "That's where we started, and then we just stumbled into this hypothesis" for rock varnish formation.

Among the team's key observations was that, while manganese in desert dust is usually in particle form, it was deposited in more continuous layers in varnish, a fact revealed by X-ray spectroscopy methods at SSRL that can tell not only what chemical compounds make up a sample but also how they are distributed, on a microscopic scale, throughout the sample.

That same analysis showed that the kinds of manganese compounds in varnish were the result of ongoing chemical cycles, rather than being left out in the sun for millennia. That information, combined with the prevalence of bacteria called Chroococcidiopsis that use manganese to combat the oxidative effects of the harsh desert sun, led Lingappa and her team to conclude that rock varnish was left behind by those bacteria.

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Being clean and hygienic need not impair childhood immunity

The theory that modern society is too clean, leading to defective immune systems in children, should be swept under the rug, according to a new study by researchers at UCL and the London School of Hygiene & Tropical Medicine.

In medicine, the 'hygiene hypothesis' states that early childhood exposure to particular microorganisms protects against allergic diseases by contributing to the development of the immune system.

However, there is a pervading view (public narrative) that Western 21st century society is too hygienic, which means toddlers and children are likely to be less exposed to germs in early life and so become less resistant to allergies.

In this paper, published in the Journal of Allergy and Clinical Immunology, researchers point to four significant reasons which, they say, disprove this theory and conclude we are not "too clean for our own good."

Lead author, Emeritus Professor of Medical Microbiology Graham Rook (UCL Infection & Immunity), said: "Exposure to microorganisms in early life is essential for the 'education' of the immune and metabolic systems.

"Organisms that populate our guts, skin and airways also play an important role in maintaining our health right into old age: so throughout life we need exposure to these beneficial microorganisms, derived mostly from our mothers, other family members and the natural environment.

"But for more than 20 years there has been a public narrative that hand and domestic hygiene practices, that are essential for stopping exposure to disease-causing pathogens, are also blocking exposure to the beneficial organisms.

"In this paper, we set out to reconcile the apparent conflict between the need for cleaning and hygiene to keep us free of pathogens, and the need for microbial inputs to populate our guts and set up our immune and metabolic systems."

In a review of evidence, the researchers point to four factors.
 

• Firstly, the microorganisms found in a modern home are, to a significant degree, not the ones that we need for immunity.
• Secondly, vaccines, in addition to protecting us from the infection that they target, do a lot more to strengthen our immune systems, so we now know that we do not need to risk death by being exposed to the pathogens.
• Thirdly, we now have concrete evidence that the microorganisms of the natural green environment are particularly important for our health; domestic cleaning and hygiene have no bearing on our exposure to the natural environment.
• Finally, recent research demonstrates that when epidemiologists find an association between cleaning the home and health problems such as allergies, this is often not caused by the removal of organisms, but rather by exposure of the lungs to cleaning products that cause a type of damage that encourages the development of allergic responses.

Professor Rook added: "So cleaning the home is good, and personal cleanliness is good, but, as explained in some detail in the paper, to prevent spread of infection it needs to be targeted to hands and surfaces most often involved in infection transmission. By targeting our cleaning practices, we also limit direct exposure of children to cleaning agents.

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More filling? Tastes great? How flies, and maybe people, choose their food

Flies have discriminating taste. Like a gourmet perusing a menu, they spend much of their time seeking sweet nutritious calories and avoiding bitter, potentially toxic food. But what happens in their brains when they make these food choices?

Yale researchers discovered an interesting way to find out. They tricked them.

In a study that could also help illuminate how people make food choices, the researchers gave hungry fruit flies the choice between sweet, nutritious food laced with bitter quinine and a less sweet, but not bitter, food containing fewer calories. Then, using neuroimaging, they tracked neural activity in their brains as they made these tough choices.

So which won? Calories or better taste?

"It depends on how hungry they are," said Michael Nitabach, professor of cellular and molecular physiology, genetics, and neuroscience at Yale School of Medicine and senior author of the study. "The hungrier they are, the more likely they will tolerate bitter taste to obtain more calories."

But the real answer to how flies make these decisions is a little more complex, according to the study published July 5 in the journal Nature Communications.

According to the research team, led by Preeti Sareen, associate research scientist at Yale, flies relay sensory information to a portion of their brain called the fan-shaped body, where signals are integrated, triggering what amounts to the insect version of an executive decision. The researchers found that patterns of neuronal activity in the fan-shaped body change adaptively when novel food choices are introduced, which dictates the fly's decision over what food to eat.

But researchers went a step further. And things got even stranger. They found they could change a fly's choice by manipulating neurons in areas of the brain that feed into the fan-shaped body. For example, when they caused a decrease in activity in the neurons involved in metabolism, the found that it made hungry flies choose the lower calorie food.

"It is one big feedback loop, not just top-down decision making," Nitabach said.

And this is where there are connections to food choices of humans, he said. Neural activity in both a fly's brain and a human's brain are regulated by the secretion of neuropeptides and the neurotransmitter dopamine, which in humans helps regulate sensations of reward. Changes in this network may alter how the brain responds to different types of food. In other words, neurochemistry may sometimes dictate food choices we think we are making consciously.

"The study provides a template to understand how it is that things like hunger and internal emotional states influence our behavior," Nitabach said.

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Why does Mercury have such a big iron core? Magnetism!

A new study disputes the prevailing hypothesis on why Mercury has a big core relative to its mantle (the layer between a planet's core and crust). For decades, scientists argued that hit-and-run collisions with other bodies during the formation of our solar system blew away much of Mercury's rocky mantle and left the big, dense, metal core inside. But new research reveals that collisions are not to blame -- the sun's magnetism is.

William McDonough, a professor of geology at the University of Maryland, and Takashi Yoshizaki from Tohoku University developed a model showing that the density, mass and iron content of a rocky planet's core are influenced by its distance from the sun's magnetic field. The paper describing the model was published on July 2, 2021, in the journal Progress in Earth and Planetary Science.

"The four inner planets of our solar system -- Mercury, Venus, Earth and Mars -- are made up of different proportions of metal and rock," McDonough said. "There is a gradient in which the metal content in the core drops off as the planets get farther from the sun. Our paper explains how this happened by showing that the distribution of raw materials in the early forming solar system was controlled by the sun's magnetic field."

McDonough previously developed a model for Earth's composition that is commonly used by planetary scientists to determine the composition of exoplanets. (His seminal paper on this work has been cited more than 8,000 times.)

McDonough's new model shows that during the early formation of our solar system, when the young sun was surrounded by a swirling cloud of dust and gas, grains of iron were drawn toward the center by the sun's magnetic field. When the planets began to form from clumps of that dust and gas, planets closer to the sun incorporated more iron into their cores than those farther away.

The researchers found that the density and proportion of iron in a rocky planet's core correlates with the strength of the magnetic field around the sun during planetary formation. Their new study suggests that magnetism should be factored into future attempts to describe the composition of rocky planets, including those outside our solar system.

The composition of a planet's core is important for its potential to support life. On Earth, for instance, a molten iron core creates a magnetosphere that protects the planet from cancer-causing cosmic rays. The core also contains the majority of the planet's phosphorus, which is an important nutrient for sustaining carbon-based life.

Using existing models of planetary formation, McDonough determined the speed at which gas and dust was pulled into the center of our solar system during its formation. He factored in the magnetic field that would have been generated by the sun as it burst into being and calculated how that magnetic field would draw iron through the dust and gas cloud.

As the early solar system began to cool, dust and gas that were not drawn into the sun began to clump together. The clumps closer to the sun would have been exposed to a stronger magnetic field and thus would contain more iron than those farther away from the sun. As the clumps coalesced and cooled into spinning planets, gravitational forces drew the iron into their core.

When McDonough incorporated this model into calculations of planetary formation, it revealed a gradient in metal content and density that corresponds perfectly with what scientists know about the planets in our solar system. Mercury has a metallic core that makes up about three-quarters of its mass. The cores of Earth and Venus are only about one-third of their mass, and Mars, the outermost of the rocky planets, has a small core that is only about one-quarter of its mass.

This new understanding of the role magnetism plays in planetary formation creates a kink in the study of exoplanets, because there is currently no method to determine the magnetic properties of a star from Earth-based observations. Scientists infer the composition of an exoplanet based on the spectrum of light radiated from its sun. Different elements in a star emit radiation in different wavelengths, so measuring those wavelengths reveals what the star, and presumably the planets around it, are made of.

"You can no longer just say, 'Oh, the composition of a star looks like this, so the planets around it must look like this,'" McDonough said. "Now you have to say, 'Each planet could have more or less iron based on the magnetic properties of the star in the early growth of the solar system.'"

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