How disorderly young galaxies grow up and mature

Using a supercomputer simulation, a research team at Lund University in Sweden has succeeded in following the development of a galaxy over a span of 13.8 billion years. The study shows how, due to interstellar frontal collisions, young and chaotic galaxies over time mature into spiral galaxies such as the Milky Way.

Soon after the Big Bang 13.8 billion years ago, the Universe was an unruly place. Galaxies constantly collided. Stars formed at an enormous rate inside gigantic gas clouds. However, after a few billion years of intergalactic chaos, the unruly, embryonic galaxies became more stable and over time matured into well-ordered spiral galaxies. The exact course of these developments has long been a mystery to the world's astronomers. However, in a new study published in Monthly Notices of the Royal Astronomical Society, researchers have been able to provide some clarity on the matter.

"Using a supercomputer, we have created a high-resolution simulation that provides a detailed picture of a galaxy's development since the Big Bang, and how young chaotic galaxies transition into well-ordered spirals" says Oscar Agertz, astronomy researcher at Lund University.

In the study, the astronomers, led by Oscar Agertz and Florent Renaud, use the Milky Way's stars as a starting point. The stars act as time capsules that divulge secrets about distant epochs and the environment in which they were formed. Their positions, speeds and amounts of various chemical elements can therefore, with the assistance of computer simulations, help us understand how our own galaxy was formed.

"We have discovered that when two large galaxies collide, a new disc can be created around the old one due to the enormous inflows of star-forming gas. Our simulation shows that the old and new discs slowly merged over a period of several billion years. This is something that not only resulted in a stable spiral galaxy, but also in populations of stars that are similar to those in the Milky Way," says Florent Renaud, astronomy researcher at Lund University.

The new findings will help astronomers to interpret current and future mappings of the Milky Way. The study points to a new direction for research in which the main focus will be on the interaction between large galaxy collisions and how spiral galaxies' discs are formed. The research team in Lund has already started new super computer simulations in cooperation with the research infrastructure PRACE (Partnership for Advanced Computing in Europe).

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New fossil species represents ancient forerunner of most modern reptiles

Lizards and snakes are a key component of most terrestrial ecosystems on earth today. Along with the charismatic tuatara of New Zealand (a "living fossil" represented by a single living species), squamates (all lizards and snakes) make up the Lepidosauria -- the largest group of terrestrial vertebrates in the planet today with approximately 11,000 species, and by far the largest modern group of reptiles. Both squamates and tuataras have an extremely long evolutionary history. Their lineages are older than dinosaurs having originated and diverged from each other at some point around 260 million years ago. However, the early phase of lepidosaur evolution 260-150 million years ago, is marked by very fragmented fossils that do not provide much useful data to understand their early evolution, leaving the origins of this vastly diverse group of animals embedded in mystery for decades.

In a study published August 25 in Nature an international team of researchers describe a new species that represents the most primitive member of lepidosaurs, Taytalura alcoberi, found in the Late Triassic deposits of Argentina. Discovered by lead author Dr. Ricardo N. Martínez, Universidad Nacional de San Juan, Argentina, and curator at the Instituto y Museo de Ciencias Naturales, Taytalura is the first three-dimensionally preserved early lepidosaur fossil. It allowed scientists to infer with great confidence it's placement in the evolutionary tree of reptiles and aids in closing the gap of our knowledge of the origin and early evolution of lepidosaurs.

Martínez and co-author Dr. Sebastián Apesteguía, Universidad Maimónides, Buenos Aires, Argentina,conducted high-resolution CT scans of Taytalura which provided confirmation that it was something related to ancient lizards. They then contacted co-author Dr. Tiago R. Simões, postdoctoral fellow in The Department of Organismic and Evolutionary Biology, Harvard University, to help identify and analyze the fossil. Simões specializes in studying these creatures and in 2018 published the largest existing dataset to understand the evolution of the major groups of reptiles (living and extinct) in Nature.

"I knew the age and locality of the fossil and could tell by examining some of its external features that it was closely related to lizards, but it looked more primitive than a true lizard and that is something quite special," said Simões.

The researchers then contacted co-author Dr. Gabriela Sobral, Department of Palaeontology, Staatliches Museum für Naturkunde Stuttgart, Germany, to process the CT scan data. Sobral, a specialist in processing CT data, created a mosaic of colors for each bone of the skull allowing the team to understand the fossil's anatomy in high-detail resolution on a scale of only a few micrometers -- about the same thickness as a human hair.

With Sobral's data, Simões was able to apply a Bayesian evolutionary analysis to determine the proper placement of the fossil in the reptile dataset. Simões had recently applied the Bayesian method -- which was adapted from methods originally developed in epidemiology to study how viruses like COVID-19 evolve -- to precisely estimate the time and rates of anatomical evolution during the rise of tetrapods. The statistical analysis confirmed their suspicions that Taytalura was in fact the most primitive member of the lineage that eventually originated all lizards and snakes. "It's not even a lizard in the evolutionary tree," said Simões, "but it's the very next thing there, between true liizards and tuataras, and all other reptiles."

"This beautifully 3D preserved fossil is really an important finding. It is the most complete fossil representing the early stages of lepidosaur evolution that we have so far. All other known fossils are too incomplete, which makes it difficult to classify them for sure, but the complete and articulated nature of Taytalura makes its relationships much more certain," said Sobral.

Simões agreed, "Taytalura is a major point in the reptile tree of life that was previously missing. Because these fossils are so small they are very difficult to preserve in the fossil record. And what candidate fossils we do have are very fragmented and poorly preserved, so they don't provide as much useful data for analysis."

Taytalura's skull reveals that the first lepidosaurs looked substantially more like the tuataras than squamates, and therefore, that squamates represent a major deviation from this ancestral pattern. Further, it has a unique dentition, differing from the teeth found in any living or extinct group of lepidosaurs. "What our analyses tells us, besides some other anatomical traits that we could see on it, in the skull specifically, is that this sphenodontian body type, at least for the skull, is the ancestral pattern for lepidosaurs. The ancestral pattern seems to be more similar to tuataras," said Simões.

"Taytalura preserves a composition of features that we were not expecting to find in such an early fossil. For instance, it shows some features that we thought were exclusive for the tuatara group. On the other hand, it made us question how truly "primitive" certain lizard features are, and it will make scientists reconsider several points in the evolution of this group," said Sobral.

"The almost perfectly preserved Taytalura skull shows us details of how a very successful group of animals, including more than 10,000 species of snakes, lizards, and tuataras, originated," said Martínez. "But it also highlights the paleontological importance of the paleontological site of Ischigualasto Formation, known for preserving some of the most primitive dinosaurs known in the world. The extraordinary quality of preservation of the fossils at this site allowed something as fragile and tiny as this specimen to be preserved for 231 million years."

"Contrary to almost all fossils of Triassic lepidosaurs found in Europe, this is the first early lepidosaur found in South America, suggesting lepidosaurs were able to migrate across vastly distant geographic regions early in their evolutionary history," agreed Simões.

"We are accustomed to accept that the Mesozoic Era was an age of gigantic reptiles, enormous proto-mammals, and huge trees, and thus we commonly look for fossils that are visible at human height, just walking," said Apesteguía. "However, the largest part of the ancient ecosystem components was small, as today. There was a universe of fauna sneaking among bigger, clawed or hoofy paws. Taytalura teaches us that we were missing important information by looking not only for bigger animals, but for also thinking that the origin of lizards occurred only in the Northern Hemisphere as evidence seemed to support until now."

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Will it be safe for humans to fly to Mars?

Sending human travelers to Mars would require scientists and engineers to overcome a range of technological and safety obstacles. One of them is the grave risk posed by particle radiation from the sun, distant stars and galaxies.

Answering two key questions would go a long way toward overcoming that hurdle: Would particle radiation pose too grave a threat to human life throughout a round trip to the red planet? And, could the very timing of a mission to Mars help shield astronauts and the spacecraft from the radiation?

In a new article published in the peer-reviewed journal Space Weather, an international team of space scientists, including researchers from UCLA, answers those two questions with a "no" and a "yes."

That is, humans should be able to safely travel to and from Mars, provided that the spacecraft has sufficient shielding and the round trip is shorter than approximately four years. And the timing of a human mission to Mars would indeed make a difference: The scientists determined that the best time for a flight to leave Earth would be when solar activity is at its peak, known as the solar maximum.

The scientists' calculations demonstrate that it would be possible to shield a Mars-bound spacecraft from energetic particles from the sun because, during solar maximum, the most dangerous and energetic particles from distant galaxies are deflected by the enhanced solar activity.

A trip of that length would be conceivable. The average flight to Mars takes about nine months, so depending on the timing of launch and available fuel, it is plausible that a human mission could reach the planet and return to Earth in less than two years, according to Yuri Shprits, a UCLA research geophysicist and co-author of the paper.

"This study shows that while space radiation imposes strict limitations on how heavy the spacecraft can be and the time of launch, and it presents technological difficulties for human missions to Mars, such a mission is viable," said Shprits, who also is head of space physics and space weather at GFZ Research Centre for Geosciences in Potsdam, Germany.

The researchers recommend a mission not longer than four years because a longer journey would expose astronauts to a dangerously high amount of radiation during the round trip -- even assuming they went when it was relatively safer than at other times. They also report that the main danger to such a flight would be particles from outside of our solar system.

Shprits and colleagues from UCLA, MIT, Moscow's Skolkovo Institute of Science and Technology and GFZ Potsdam combined geophysical models of particle radiation for a solar cycle with models for how radiation would affect both human passengers -- including its varying effects on different bodily organs -- and a spacecraft. The modeling determined that having a spacecraft's shell built out of a relatively thick material could help protect astronauts from radiation, but that if the shielding is too thick, it could actually increase the amount of secondary radiation to which they are exposed.

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Secrets of COVID-19 transmission revealed in turbulent puffs

Turbulence is everywhere -- in the movement of the wind, the ocean waves and even magnetic fields in space. It can also be seen in more transient phenomena, like smoke billowing from a chimney, or a cough.

Understanding this latter type of turbulence -- called puff turbulence -- is important not only for the advancement of fundamental science, but also for practical health and environmental measures, like calculating how far cough droplets will travel, or how pollutants released from a chimney or cigarette might disperse into the surroundings. But creating a complete model of how turbulent puffs of gases and liquids behave has so far proven elusive.

"The very nature of turbulence is chaotic, so it's hard to predict," said Professor Marco Edoardo Rosti, who leads the Complex Fluids and Flows Unit at Okinawa Institute of Science and Technology Graduate University (OIST). "Puff turbulence, which occurs when the ejection of a gas or liquid into the environment is disrupted, rather than continuous, has more complicated characteristics, so it's even more challenging to study. But it's of vital importance -- especially right now for understanding airborne transmission of viruses like SARS-CoV-2."

Until now, the most recent theory was developed in the 1970s, and focused on the dynamics of a puff only at the scale of the puff itself, like how fast it moved and how wide it spread.

The new model, developed in a collaboration between Prof. Rosti from OIST, Japan and Prof. Andrea Mazzino from the University of Genova in Italy, builds on this theory to include how minute fluctuations within the puff behave, and how both large-scale and small-scale dynamics are impacted by changes in temperature and humidity. Their findings were published in Physical Review Letters on August 25th 2021.

Interestingly, the scientists found that at cooler temperatures (15°C or lower), their model deviated from the classical model for turbulence.

In the classical model, turbulence reigns supreme -- determining how all the little swirls and eddies within the flow behave. But once temperatures dipped, buoyancy started to have a greater impact.

"The effect of buoyancy was initially very unexpected. It's a completely new addition to the theory of turbulent puffs," said Prof. Rosti.

Buoyancy exerts an effect when the gas or liquid puff is much warmer than the temperature of the immediate surroundings it is released into. Warm gas or fluid is much less dense than the cold gas or fluid of the environment, and therefore the puff rises, allowing it to travel further.

"Buoyancy generates a very different kind of turbulence -- not only do you see changes in the large-scale movement of the puff, but also changes in the minute movements within the puff," said Prof. Rosti.

The scientists used a powerful supercomputer, capable of resolving behavior of the puff at the large-scale and the small-scale, to run simulations of turbulent puffs, which confirmed their new theory.

The new model could now allow scientists to better predict the movement of droplets in the air that are released when someone coughs or speaks unmasked.

While larger droplets fall quickly to the ground, reaching distances of around one meter, smaller droplets can remain airborne for much longer and travel further.

"How fast the droplets evaporate -- and therefore how small they are -- depends on turbulence, which in turn is affected by the humidity and temperature of the surroundings," explained Prof. Rosti. "We can now start to take these differences in environmental conditions, and how they affect turbulence, into consideration when studying airborne viral transmission."

Next, the researchers plan to study how puffs behave when made of more complicated non-Newtonian fluids, where how easily the fluid flows can change depending on the forces it is under.

"For COVID, this could be useful for studying sneezes, where non-Newtonian fluids like saliva and mucus are forcefully expelled," said Dr. Rosti.

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From couch to ultra-marathon – mental imagery technique can aid running challenge completion

A motivational intervention known as functional imagery training (FIT) can help self-professed non-runners to complete an ultra-marathon (50km plus), according to new research.

The study, led by the University of Plymouth, started by examining the motivation of 31 non-runners who wanted to get fitter, by giving them a recognised behaviour change technique, often used by counsellors, known as Motivational Interviewing (MI). Participants were then left for five months to do whatever they presumed would benefit their fitness and health. After this period all were contacted and asked if they would consider completing an ultra-marathon.

Fifteen participants went on to express an interest in attempting an ultra-marathon as they continued to improve their fitness. Seven were randomly assigned FIT, while eight continued with just MI.

MI is a technique that sees a counsellor support someone to develop, highlight and verbalise their need or motivation for change, and their reasons for wanting to change. Functional Imagery Training builds on MI, as it teaches clients how to elicit and practice motivational imagery themselves, with participants encouraged to utilise all their senses to visualise how it would feel to achieve their goal.

Of the eight participants in the MI only group, four started the race, and two finished. Meanwhile, all seven of the FIT group started, and six finished -- showing that those assigned to the technique were five times more likely to complete the challenge.

While researchers acknowledge the small population size, the study, published in the Journal of Imagery Research in Sport and Physical Activity, adds to the growing body of evidence that FIT can significantly reinforce a person's motivation to complete a challenging goal.

FIT has also previously been shown to boost weight loss, with another Plymouth-led study showing that overweight people who used it lost an average of five times more weight than those using motivational interviewing alone.

Developed at the University of Plymouth, FIT is a unique approach to behaviour change that uses mental imagery to motivate change.

It teaches people new ways of thinking about their immediate future to help them stay motivated as they achieve each small step towards their goal -- with users describing it as a 'mindset shift', where they exercised because they wanted to, rather than feeling they had to.

For example, at difficult points in the race, a participant in the new study -- a teacher -- pictured the conversation they would have at work on Monday morning: visualising the staff room, holding a coffee in hand, imagining the smell and the taste, talking about the challenges with a peer, then using this self-developed image to imagine the feeling at the finish line, as they go from little exercise to ultra-athlete.

Lead author Dr Jon Rhodes, who has worked with professional athletes to improve their resilience, said: "An ultra-marathon requires a huge amount of mental, as well as physical, strength -- even from people who run regularly. Trialling Functional Imagery Training on historically self-professed non-runners was a real test of its efficacy, and to see that it made a difference was a promising finding.

"It shows that multi-sensory imagery is the key difference between those who reach the starting line and then go on to finish, and those who do not -- showing it is critical to maintaining changes and pushing the boundaries of physical and mental performance."

Melissa King, aged 38 from Newquay in Cornwall, was allocated the FIT intervention as she prepared for the Exmoor Ultra Marathon earlier this year. Completing the event successfully, she said: "My honest reason for starting running in the first place was just to see if I could do it.

"FIT has been a huge mindset shift, and I now use imagery as a way to reset; to ground me and help me to focus on being present, appreciating why I am here while also prompting me to cue my immediate, medium- and long-term goals. Having never run before, my ultimate aim is now a running trip in South America which will take a couple of months. It's in three years' time, so I'm starting training early and really embracing the challenge."

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Diverse DNA signatures linked to heart disease

Risk for heart disease does not look the same on the genetic level for different population groups, report an international team of researchers this month in the journal JAMA Cardiology. The study, led by Texas Biomedical Research Institute (Texas Biomed) and Columbia University Mailman School of Public Health, begins to outline gene activity patterns that could serve as early warning indicators for cardiovascular disease.

"We shouldn't expect it to be same for every population group," said Associate Professor Shelley Cole, Ph.D., senior author and co-lead of the Population Health Program at Texas Biomed. "There are some universal factors affecting risk for heart disease, where you live in the world, your environment, your lifestyle, your access to health care, those all influence disease risk and progression. Advances in querying the entire genome or DNA of an individual, and statistical analyses, coupled with large, long-term studies are enabling us to see those influences on the genetic level for different populations."

External influences that leave a mark on DNA are part of the growing field called epigenetics. Essentially, modifications occur that affect how DNA is expressed, without changing the basic genetic code. Identifying epigenetic patterns associated with particular diseases could one day help screen for illness years or even decades before symptoms develop.

"In this study, we harness the country's best clinical data on heart disease from diverse populations to begin to unlock the specific epigenetic changes involved the complex biology that leads to disease," said Ana Navas-Acien, M.D., Ph.D., the study's first author and professor of environmental health sciences at Columbia University Mailman School of Public Health.

Navas-Acien, Cole and their collaborators compiled data from nearly 9,400 participants in four long-term health studies: the Strong Heart Study, which has studied cardiovascular disease among American Indians since the 1980s; the Women's Health Initiative, which follows African-American, Hispanic and white women across the U.S.; the Framingham Heart Study, which follows men and women in Massachusetts; and Atherosclerosis Risk in Communities Study (ARIC), which follows men and women in four U.S. communities. (For this study, the ARIC data was split into two cohorts: Black and white.)

Researchers analyzed the entire genome of each person for DNA methylation, which causes changes to DNA activity without altering the genetic sequence, and compared that with individuals known to have developed coronary heart disease. Among the Strong Heart Study volunteers, there were about 505 methylation points associated with heart disease.

Those sites were compared with the other cohorts. Only 33 were also found in three additional groups with mixed results -- sometimes a common site was associated with heart disease, while other times, it was actually associated with a lower risk of heart disease.

"This underscores the need to tailor indicators of risk and resilience, as well as interventions and treatments, for subpopulations as we move away from a one-size-fits-all approach and towards precision medicine," said Cole, who chairs the Strong Heart Study Steering Committee and directs the Strong Heart Study Genetics Center.

By incorporating data from the Strong Heart Study, which involves 12 tribes in Arizona, Oklahoma, and North and South Dakota, this paper successfully brings advanced genetic analyses to traditionally underserved, rural populations.

"It can be challenging to do field research with remote population groups that don't have easy access to hospitals and clinics, so they are often left out of research projects like this," Cole said. "The Strong Heart Study is providing extremely valuable insights for the participating tribes as well as for the broader global community about how environmental factors influence our health."

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New class of habitable exoplanets represent a big step forward in the search for life

A new class of exoplanet very different to our own, but which could support life, has been identified by astronomers, which could greatly accelerate the search for life outside our Solar System.

In the search for life elsewhere, astronomers have mostly looked for planets of a similar size, mass, temperature and atmospheric composition to Earth. However, astronomers from the University of Cambridge believe there are more promising possibilities out there.

The researchers have identified a new class of habitable planets, dubbed 'Hycean' planets -- hot, ocean-covered planets with hydrogen-rich atmospheres -- which are more numerous and observable than Earth-like planets.

The researchers say the results, reported in The Astrophysical Journal, could mean that finding biosignatures of life outside our Solar System within the next two or three years is a real possibility.

"Hycean planets open a whole new avenue in our search for life elsewhere," said Dr Nikku Madhusudhan from Cambridge's Institute of Astronomy, who led the research.

Many of the prime Hycean candidates identified by the researchers are bigger and hotter than Earth, but still have the characteristics to host large oceans that could support microbial life similar to that found in some of Earth's most extreme aquatic environments.

These planets also allow for a far wider habitable zone, or 'Goldilocks zone', compared to Earth-like planets. This means that they could still support life even though they lie outside the range where a planet similar to Earth would need to be in order to be habitable.

Thousands of planets outside our Solar System have been discovered since the first exoplanet was identified nearly 30 years ago. The vast majority are planets between the sizes of Earth and Neptune and are often referred to as 'super-Earths' or 'mini-Neptunes': they can be predominantly rocky or ice giants with hydrogen-rich atmospheres, or something in between.

Most mini-Neptunes are over 1.6 times the size of Earth: smaller than Neptune but too big to have rocky interiors like Earth. Earlier studies of such planets have found that the pressure and temperature beneath their hydrogen-rich atmospheres would be too high to support life.

However, a recent study on the mini-Neptune K2-18b by Madhusudhan's team found that in certain conditions these planets could support life. The result led to a detailed investigation into the full range of planetary and stellar properties for which these conditions are possible, which known exoplanets may satisfy those conditions, and whether their biosignatures may be observable.

The investigation led the researchers to identify a new class of planets, Hycean planets, with massive planet-wide oceans beneath hydrogen-rich atmospheres. Hycean planets can be up to 2.6 times larger than Earth and have atmospheric temperatures up to nearly 200 degrees Celsius, but their oceanic conditions could be similar to those conducive for microbial life in Earth's oceans. Such planets also include tidally locked 'dark' Hycean worlds that may have habitable conditions only on their permanent night sides, and 'cold' Hycean worlds that receive little radiation from their stars.

Planets of this size dominate the known exoplanet population, although they have not been studied in nearly as much detail as super-Earths. Hycean worlds are likely quite common, meaning that the most promising places to look for life elsewhere in the Galaxy may have been hiding in plain sight.

However, size alone is not enough to confirm whether a planet is Hycean: other aspects such as mass, temperature and atmospheric properties are required for confirmation.

When trying to determine what the conditions are like on a planet many light years away, astronomers first need to determine whether the planet lies in the habitable zone of its star, and then look for molecular signatures to infer the planet's atmospheric and internal structure, which govern the surface conditions, presence of oceans and potential for life.

Astronomers also look for certain biosignatures which could indicate the possibility of life. Most often, these are oxygen, ozone, methane and nitrous oxide, which are all present on Earth. There are also a number of other biomarkers, such as methyl chloride and dimethyl sulphide, that are less abundant on Earth but can be promising indicators of life on planets with hydrogen-rich atmospheres where oxygen or ozone may not be as abundant.

"Essentially, when we've been looking for these various molecular signatures, we have been focusing on planets similar to Earth, which is a reasonable place to start," said Madhusudhan. "But we think Hycean planets offer a better chance of finding several trace biosignatures."

"It's exciting that habitable conditions could exist on planets so different from Earth," said co-author Anjali Piette, also from Cambridge.

Madhusudhan and his team found that a number of trace terrestrial biomarkers expected to be present in Hycean atmospheres would be readily detectable with spectroscopic observations in the near future. The larger sizes, higher temperatures and hydrogen-rich atmospheres of Hycean planets make their atmospheric signatures much more detectable than Earth-like planets.

The Cambridge team identified a sizeable sample of potential Hycean worlds which are prime candidates for detailed study with next-generation telescopes, such as the James Webb Space Telescope (JWST), which is due to be launched later this year. These planets all orbit red dwarf stars between 35-150 light years away: close by astronomical standards. Planned JWST observations of the most promising candidate, K2-18b, could lead to the detection of one or more biosignature molecules.

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Central European prehistory was highly dynamic

Centrally located along trade routes and tightly nestled around the important waterways such as the Elbe River, Bohemia attracted many different archaeological cultures, rendering it a key region in understanding the prehistory of Europe. In addition to the expansions associated with the spread of agriculture and "steppe"-related ancestry previously discovered, this new study identifies at least another three migratory events which shaped central European prehistory.

The genetic profiles of people associated with Funnelbeaker and Globular Amphora cultures show evidence of being recent migrants to the region. This finding shows that the period between arrival of agriculture and "steppe"-related ancestry, hitherto thought of as an uneventful period, was more dynamic than previously hypothesised.

Drastic changes to the genetic landscape

The large sample size of the study, particularly concentrated on the Late Neolithic and Early Bronze Age (~6,000-3,700 years ago), also allowed novel insights into social processes to be made. Individuals associated with the Corded Ware culture expanded from Eastern Europe and then assimilated preferentially central European women into their culture, giving them the same burial ritual as members of the immigrating group. "We were finally able to fill key temporal gaps, especially in the transition period around 5,000 years ago, when we see the genetic landscape changing drastically," says Max Planck researcher Wolfgang Haak, senior author and principal investigator of the study. "Intriguingly, in this early horizon we find individuals with high amounts of 'steppe' ancestry next to others with little or none, all buried according to the same customs."

Once established, individuals of the Corded Ware culture (4,900-4,400 years ago) changed genetically through time. One important change seems to have been the sharp decline in Y-chromosome lineage diversity. Although initially carrying five different Y-lineages, later Corded Ware males carry almost exclusively only a single lineage, essentially being descended from the same man in the recent past. "This pattern may reflect the emergence of a new social structure or regulation of mating in which only a subset of men fathered the majority of offspring," says first author Luka Papac, a researcher at the Max Planck Institute for the Science of Human History.

This social structure seems to have been even stricter in the following Bell Beaker society (4,500-4,200 years ago) where every single male sampled belonged to a single, newly introduced Y-lineage. Remarkably, this Bell Beaker Y-lineage is never seen before in Bohemia, implying that a new clan arrived in the region and almost immediately replaced all pre-existing Y-lineages with not a single lineage from Corded Ware or previous societies found among Bell Beaker males.

Cultural, biological, and social changes

The Early Bronze Age Unetice culture has traditionally been thought of descending from Bell Beaker individuals, with perhaps limited input from the southeast (Carpathian Basin). However, the new genetic data supports yet another genetic turnover originating from regions northeast of Bohemia. Remarkably, also 80 percent of the early Unetice Y-lineages are new to Bohemia, some of which are previously found in individuals from north-eastern Europe, providing clues to where they originated from. "This finding was very surprising to us archaeologists as we did not expect to see such clear patterns, even though the region has played a critical role, e.g. in the emerging trade of amber from the Baltic and became an important trading hub during the Bronze and Iron Ages," adds co-author and co-PI Michal Ernée from the Czech Academy of Sciences.

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Artificial intelligence to help predict Arctic sea ice loss

A new AI (artificial intelligence) tool is set to enable scientists to more accurately forecast Arctic sea ice conditions months into the future. The improved predictions could underpin new early-warning systems that protect Arctic wildlife and coastal communities from the impacts of sea ice loss.

Published this week (Thursday 26 August) in the journal Nature Communications, an international team of researchers led by British Antarctic Survey (BAS) and The Alan Turing Institute describe how the AI system, IceNet, addresses the challenge of producing accurate Arctic sea ice forecasts for the season ahead -- something that has eluded scientists for decades.

Sea ice, a vast layer of frozen sea water that appears at the North and South poles, is notoriously difficult to forecast because of its complex relationship with the atmosphere above and ocean below. The sensitivity of sea ice to increasing temperatures has caused the summer Arctic sea ice area to halve over the past four decades, equivalent to the loss of an area around 25 times the size of Great Britain. These accelerating changes have dramatic consequences for our climate, for Arctic ecosystems, and Indigenous and local communities whose livelihoods are tied to the seasonal sea ice cycle.

IceNet, the AI predictive tool, is almost 95% accurate in predicting whether sea ice will be present two months ahead -- better than the leading physics-based model.

Lead author Tom Andersson, Data Scientist at the BAS AI Lab and funded by The Alan Turing Institute, explains: "The Arctic is a region on the frontline of climate change and has seen substantial warming over the last 40 years. IceNet has the potential to fill an urgent gap in forecasting sea ice for Arctic sustainability efforts and runs thousands of times faster than traditional methods."

Dr Scott Hosking, Principal Investigator, Co-leader of the BAS AI Lab and Senior Research Fellow at The Alan Turing Institute, says: "I'm excited to see how AI is making us rethink how we undertake environmental research. Our new sea ice forecasting framework fuses data from satellite sensors with the output of climate models in ways traditional systems simply couldn't achieve."

Unlike conventional forecasting systems that attempt to model the laws of physics directly, the authors designed IceNet based on a concept called deep learning. Through this approach, the model 'learns' how sea ice changes from thousands of years of climate simulation data, along with decades of observational data to predict the extent of Arctic sea ice months into the future.

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One in three Americans had COVID-19 by the end of 2020, study estimates

A new study published in the journal Nature estimates that 103 million Americans, or 31 percent of the U.S. population, had been infected with SARS-CoV-2 by the end of 2020. Columbia University Mailman School of Public Health researchers modeled the spread of the coronavirus, finding that fewer than one-quarter of infections (22%) were accounted for in cases confirmed through public health reports based on testing.

The study is the first to comprehensively quantify the overall burden and characteristics of COVID-19 in the U.S. during 2020. The researchers simulated the transmission of SARS-CoV-2 within and between all 3,142 U.S. counties using population, mobility, and confirmed case data.

Infections were more widespread in some areas of the country

In areas of the upper Midwest and Mississippi valley, including the Dakotas, Minnesota, Wisconsin and Iowa, more than 60 percent of the population is estimated to have been infected by the end of 2020. In five metropolitan areas the researchers examined, 48 percent of residents of Chicago, 52 percent of Los Angeles, 42 percent of Miami, 44 percent of New York City, and 27 percent of people in Phoenix, had been infected in the same timeframe.

Testing picked up on a growing number of infections but offered an incomplete picture

The portion of confirmed cases reflected in the study's estimates, i.e. the ascertainment rate, rose from 11 percent in March to 25 percent in December, reflecting improved testing capacity, a relaxation of initial restrictions on test usage, and increasing recognition, concern, and care-seeking among the public. However, the ascertainment rate remained well below 100 percent, as individuals with mild or asymptomatic infections, who could still spread the virus, were less likely to be tested.

"The vast majority of infectious were not accounted for by the number of confirmed cases," says Jeffrey Shaman, PhD, professor of environmental health sciences at Columbia University Mailman School of Public Health. "It is these undocumented cases, which are often mild or asymptomatic infectious, that allow the virus to spread quickly through the broader population."

One in 130 Americans was contagious at year's end

Roughly 1 in 130 Americans (0.77%) was contagious with SARS-CoV-2 on December 31, 2020. A similar percentage (0.83%) was estimated to be latently infected, i.e. infected but not yet contagious. In some metropolitan areas, the percentage of individuals who was contagious at year's end was much higher.

Fatality rates fell with strengthening treatments and public health measures

The percentage of people with infections who died from COVID-19 fell from 0.8 percent during the spring wave to 0.3 percent by year's end. Urban areas like New York City that peaked in the spring saw the worst numbers for reasons that include delays in testing availability and masking mandates, overwhelmed hospitals, and lack of effective treatments.

Cities peaked at different times of the year

New York and Chicago experienced strong spring and fall/winter waves but little activity during summer; Los Angeles and Phoenix underwent summer and fall/winter waves; and Miami experienced all three waves. Los Angeles County, the largest county in the U.S. with a population of more than 10 million people, was particularly hard-hit during the fall and winter and had a community infection rate of 2.4 percent on December 31.

A new pandemic landscape for 2021

Looking ahead, the authors write that several factors will alter population susceptibility to infection. The virus will continue to spread to those who haven't yet been infected. While vaccines protect against severe and fatal disease, breakthrough infections, including those that are mild or asymptomatic, will contribute to the spread of the virus. The current study does account for the possibility of reinfection, although there is evidence of waning antibodies and reinfection. New more contagious variants make reinfection and breakthrough infections more likely.

"While the landscape has changed with the availability of vaccines and the spread of new variants, it is important to recognize just how dangerous the pandemic was in its first year," concludes Sen Pei, PhD, assistant professor of environmental health sciences at Columbia University Mailman School of Public Health.

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CT scan of an ancient reptile skull reveals little evolutionary change over 22 million years

A CT scan of the skull of a long-necked plesiosaur shows the cranial architecture of these long-extinct marine reptiles didn't evolve much over 22 million years that they lived during the Cretaceous time.

That's very unusual, said SMU paleontologist Louis Jacobs, an expert on prehistoric creatures and co-author of a study published in PLOS One.

"Basically, in anything except living fossils, you don't go 22 million years without evolving," said Jacobs, professor emeritus of Earth Sciences at SMU and president of ISEM at SMU.

Elasmosaurid plesiosaurs, lookalikes of the mythical Loch Ness monster, were the largest of the long-necked plesiosaurs, growing as long as 43 feet with half of that length deriving from their small heads and very long necks. Paleontologists from SMU (Southern Methodist University), as part of an international team called Projecto PaleoAngola, based their findings on a CT scan of the 71.5 million year old skull from a species of elasmosaurid called Cardiocorax mukulu.

This detailed 3D model allowed the paleontologists to compare the well-preserved skull of C. mukulu found in Angola to that of other species of elasmosaurids. They found that C. mukulu looked nearly identical to skulls that came from much older elasmosaurids, including one found at Cedar Hill, Texas, in 1931, whose 93-million-years old remains can be found at SMU's Shuler Museum of Paleontology.

"The skull shape, organization of muscles, and the shape and arrangement of the teeth largely reflect how an animal acquired prey," said co-author Michael J. Polcyn, research associate and director of SMU's Digital Earth Sciences Laboratory "The interesting aspect of Cardiocorax mukulu is that it appears that this animal's predecessors adopted a particular feeding style early in their evolutionary history, and then maintained the same basic skull structure for the next 22 million years"

It will take more research to pinpoint why elasmosaurids might have been different from other reptiles in their evolutionary journey.

Elasmosaurids lived during the Cretaceous Period, which spanned from 145 million years ago to 66 million years ago. They were predators, thriving on fish and other marine life. Projecto PaleoAngola paleontologists first discovered C. mukulu in Angola in 2015.

The lead author of the CT scan study is Miguel P. Marx, who will be starting a Ph.D. program at Lund University in Sweden later this month and was a researcher in SMU's Earth Science department during this study. Other co-authors include Jacobs and Polcyn of SMU.; OctávioMateus of Universidade Nova de Lisboa and Museu da Lourinhã, Portugal; Anne S. Schulp of the Naturalis Biodiversity Center and Utrecht University in the Netherlands; and A. Olímpio Gonçalves of the Universidade Agostinho Neto in Angola.

Skull found in the same area that yielded Smithsonian Museum exhibit

Mateus found the nearly complete cranium and jaw of C. mukulu, along with 12 associated teeth and other fossilized parts of the reptile's body in Bentiaba, Angola in 2017. That area is on the coast of Angola that Jacobs has called a "museum in the ground," because so many fossils have been found in the rocks there.

Many of those fossils are currently on display at the Smithsonian's National Museum of Natural History. The museum's "Sea Monsters Unearthed" exhibit, co-produced with SMU, features large marine reptiles from the Cretaceous Period -- mosasaurs, turtles, and plesiosaurs.

Jacobs and Polcyn forged the Projecto PaleoAngola partnership with collaborators in Angola, Portugal, and the Netherlands to explore and excavate Angola's rich fossil history and began laying the groundwork for returning the fossils to the West African nation. Back in Dallas, Jacobs, Polcyn, and research associate Diana Vineyard went to work over a period of 13 years with a small army of SMU students to prepare the fossils excavated by Projecto PaleoAngola.

Like the Smithsonian exhibit, the discovery of the Cardiocorax mukulu remains were the result of that collaboration.

CT scan shows jaws and teeth of elasmosaurids didn't evolve much

Marx's computed tomography (CT) scan of the skull was designed to reveal parts of the skull that are otherwise difficult to see, such as the braincase. Only part of the skull was actually freed from the Angolan rock in which it was discovered because elasmosaurids skulls are so fragile. So the CT scan was taken largely through the rock that preserved the specimen.

However, "the good resolution of the resulting CT images allowed me to discriminate between the bone, the rock matrix, and the plaster jacket the skull was protected in," Marx said. "Thus, I could build a 3D model of the skull and be able to study the fragile parts of it, such as the braincase and palate, without touching it."

The team's conclusions about the cranial anatomy of C. mukulu were drawn from comparisons to the skull of Libonectes morgani, a much older elasmosaurid housed at SMU.

"The skull of L. morgani at SMU is so complete that the sutures between different bones can clearly be delineated," he said. "The skull of Libonectes morgani worked as a guide for me when making the skull model of Cardiocorax mukulu. This made the process of building the model much faster."

Marx and the PaleoAngola team also compared the 3D imaging to the skulls of Styxosaurus snowii and Thalassomedon haningtoni -- all elasmosaurids from different time periods.

The similarity between the jaws, teeth and other skull anatomy of C. mukulu and its predecessors was a surprising discovery, Marx said.

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Unveiling a century-old mystery: Where the Milky Way's cosmic rays come from

Astronomers have succeeded for the first time in quantifying the proton and electron components of cosmic rays in a supernova remnant. At least 70% of the very-high-energy gamma rays emitted from cosmic rays are due to relativistic protons, according to the novel imaging analysis of radio, X-ray, and gamma-ray radiation. The acceleration site of protons, the main components of cosmic rays, has been a 100-year mystery in modern astrophysics, this is the first time that the amount of cosmic rays being produced in a supernova remnant has been quantitatively shown and is an epoch-making step in the elucidation of the origin of cosmic rays.

The origin of cosmic rays, the particles with the highest energy in the universe, has been a great mystery since their discovery in 1912. Because cosmic rays promote the chemical evolution of interstellar matter, understanding their origin is critical in understanding the evolution of our Galaxy. The cosmic rays are thought to be accelerated by supernova remnants (the after-effects of supernova explostions) in our Galaxy and traveled to the Earth at almost the speed of light. Recent progress in gamma-ray observations has revealed that many supernova remnants emit gamma-rays at teraelectronvolts (TeV) energies. If gamma rays are produced by protons, which are the main component of cosmic rays, then the supernova remnant origin of cosmic rays can be verified. However, gamma rays are also produced by electrons, it is necessary to determine whether the proton or electron origin is dominant, and to measure the ratio of the two contributions. The results of this study provide compelling evidence of gamma rays originating from the proton component, which is the main component of cosmic rays, and clarify that Galactic cosmic rays are produced by supernova remnants.

The originality of this research is that gamma-ray radiation is represented by a linear combination of proton and electron components. Astronomers knew a relation that the intensity of gamma-ray from protons is proportional to the interstellar gas density obtained by radio-line imaging observations. On the other hand, gamma-rays from electrons are also expected to be proportional to X-ray intensity from electrons. Therefore, they expressed the total gamma-ray intensity as the sum of two gamma-ray components, one from the proton origin and the other from the electron origin. This led to a unified understanding of three independent observables. This method was first proposed in this study. As a result, it was shown that gamma rays from protons and electrons account for 70% and 30% of the total gamma-rays, respectively. This is the first time that the two origins have been quantified. The results also demonstrate that gamma rays from protons are dominated in interstellar gas-rich regions, whereas gamma rays from electrons are enhanced in the gas-poor region. This confirms that the two mechanisms work together and supporting the predictions of previous theoretical studies.

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There’s a bright side to being a ‘Debbie Downer’

New research shows that keeping busy with a variety of activities can elicit both positive and negative emotions, and some of the relationship could depend on your age. A new study published in the Journal of Gerontology finds that engaging in diverse daily activities is associated with a diverse set of emotions.

"Experiencing a broad spectrum of emotions is adaptive and beneficial to health because it means having a more balanced and nuanced appraisal of daily life," said Soomi Lee, assistant professor of aging studies in the University of South Florida College of Behavioral and Community Sciences. "For example, even for negative emotions, feeling intense anger across situations may mean that the individual has a narrow appraisal of situations, whereas feeling a mix of anger, sadness and shame may indicate a broader and more nuanced appraisal."

Lee reviewed data collected on nearly 3,000 middle-aged participants enrolled in the Midlife in the United States Study who are considered relatively healthy and well-educated. She found individuals who regularly participated in a broad range of daily activities experienced diverse emotional experiences -- both positive and negative -- with those between ages 33-44 experiencing more diverse positive emotions compared to those between ages 68-84.

The study looked at the amount of time individuals spent participating in seven activities: paid work, spending time with children, chores, leisure, physical activities, formal volunteering and helping someone outside of their household, such as a neighbor. Participants recorded their activities for eight consecutive days, as well as their positive and negative emotions, which were used to calculate emodiversity scores.

Emodiversity is a term used to describe rich and balanced emotions. Emodiversity was broken into 13 positive emotions: cheerful, in good spirits, extremely happy, calm and peaceful, satisfied, full of life, enthusiastic, attentive, proud, active, close to others, belonging and confident, as well as 14 negative emotions: worthlessness, nervous, restless or fidgety, hopeless, afraid, jittery, irritable, ashamed, upset, lonely, angry, frustrated, that everything is an effort and so sad that nothing could cheer you up.

Lee says the younger demographic may have stronger emotions than older adults since their activities are more diverse. Many spend more time at work and with children, which tends to decrease with age. Also, older adults may have more muted or monotonic emotions as a result of wisdom or their strategy to reduce the range of novel social interactions to avoid potentially negative situations. Interestingly, the overall amount of time spent participating in activities was not associated with neither positive nor negative emodiversity, suggesting that total activity time is not what matters, but rather that an even amount of time is spent participating in a broad range of activities.

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Using your smartwatch to reduce stress

The old adage "never let them see you sweat," doesn't apply in the electrical and computer engineering lab of Rose Faghih, assistant professor of electrical and computer engineering in the University of Houston Cullen College of Engineering. In fact, Faghih seeks sweat, the kind that beads on your upper lip when you're nervous -- skin conductance response (SCR) as the change in sweat activity is scientifically called. It is through that measure that Faghih is reporting the ability to monitor stress and even help lower it.

To collect and study these physiological signals of stress, Faghih's research team has built a new closed-loop technology by placing two electrodes on smartwatch-type wearables. Once the signal for stress is detected, a reminder is sent through the smartwatch, for example, to listen to relaxing music to calm down. Thus, the loop is closed as the detected stress launches the subtle suggestion.

"This study is one of the very first steps toward the ultimate goal of monitoring brain responses using wearable devices and closing the loop to keep a person's stress state within a pleasant range," reports Faghih in the journal IEEE Xplore.

Electrodermal activity (i.e., the electrical conductivity of the skin) carries important information about the brain's cognitive stress. Faghih uses signal processing techniques to track the hidden stress state and design an appropriate control algorithm for regulating the stress state and closing the loop. The results of the research illustrate the efficiency of the proposed approach and validate its feasibility of being implemented in real life.

"To the best of our knowledge, this research is one of the very first to relate the cognitive stress state to the changes in SCR events and design the control mechanism to close the loop in a real-time simulation system," said UH doctoral student and lead study author Fekri Azgomi, who accomplished the task of closed-loop cognitive stress regulation in a simulation study based on experimental data.

Due to the increased ubiquity of wearable devices capable of measuring cognitive stress-related variables, the proposed architecture is an initial step toward treating cognitive disorders using non-invasive brain state decoding.

"The final results verify that the proposed architecture has great potential to be implemented in a wrist-worn wearable device and used in daily life," said Faghih.

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Why do short-lived lung infections lead to long-lasting lung damage?

The deadliest time in a viral respiratory illness sometimes is actually after the virus is cleared from the body. Destructive processes that are set in motion during an infection crest in the weeks after the virus is defeated, leading to organ damage that can cause chronic illness or even death. After an initial bout of COVID-19, for example, some people struggle with persistent cough, difficulty breathing and shortness of breath -- signs of ongoing lung disease.

Researchers at Washington University School of Medicine in St. Louis have found clues to just how lung damage develops in the aftermath of a respiratory infection. Studying mice, they found that infection triggers the expression of a protein called IL-33, which is needed for stem cells in the lung to overgrow into air spaces, and increases mucus production and inflammation in the lung. The findings, published Aug. 24 in the Journal of Clinical Investigation, reveal potential points of intervention to prevent chronic lung damage caused by viral infections.

"Vaccines, antivirals, antibody therapies are all helpful, but they are not a solution for people who are already on the road to progressive disease," said senior author Michael J. Holtzman, MD, the Selma and Herman Seldin Professor of Medicine and a professor of cell biology & physiology. "We've gotten better at taking care of the acute illness due to COVID-19, but what happens after that initial injury phase is still a major obstacle to a better outcome. At this point, we are also faced with tens of millions of people who already had infection, and a high percentage of them are having long-term disease, especially with respiratory symptoms. We don't have a treatment that can correct the problem."

It's long been recognized that acute respiratory infections can lead to chronic lung disease. Children hospitalized with respiratory syncytial virus, for example, are two to four times more likely to develop asthma that persists for long periods, maybe even for a lifetime. How exactly an acute respiratory infection triggers chronic disease, however, is not fully understood, making it difficult to develop therapies to prevent or treat it.

As part of this study, Holtzman and colleagues, including first author Kangyun Wu, PhD, an instructor in medicine, studied mice infected with Sendai virus. Sendai doesn't cause serious disease in people, but it naturally infects other animals including mice and causes respiratory infections that develop much like respiratory infections in people.

The researchers examined lung tissues from mice 12 and 21 days after infection with Sendai virus, and compared the samples to lung tissues of uninfected mice. They found that two populations of stem cells help maintain the barrier between the lung and the outside world in uninfected mice. After infection with Sendai virus, however, these two populations separately begin to multiply and spread into air spaces. Basal cells take over small airways and air sacs while AT2 cells remain confined to air sacs. Some of the new basal cells become mucus-producing cells while others release molecules that recruit immune cells to the lungs. Altogether, the process results in lungs with less air space, more mucus and ongoing inflammation that together interfere with breathing.

Further experiments showed that this process hinges on the protein IL-33. Under normal conditions, IL-33 increases in the nuclei of lung stem cells in response to stress or injury and helps the lung repair damaged barriers. During and after infection, though, IL-33 can take on a more detrimental role.

To assess the role of IL-33 in post-viral lung damage, the researchers genetically modified mice to lack IL-33 in the basal set of lung stem cells. The scientists then infected those mice -- and a separate group of unmodified mice -- with Sendai virus. The two groups of mice were equally effective at fighting off an initial Sendai virus infection. But three weeks after infection, the lungs of the mice that lacked IL-33 exhibited less cellular overgrowth, mucus and inflammation, indicating that they had fewer signs of harmful lung changes. At seven weeks after infection, the mice without IL-33 in basal cells also had higher oxygen levels in their blood and less airway hyperresponsiveness, both of which are signs of improvement in their chronic lung disease.

"These results were really nice to see because getting rid of IL-33 and in turn losing basal stem cells could have made things worse," Holtzman said. "The engineered mice could have died because they were no longer able to perform the normal repair of the viral damage to the lung barrier. But that's not the case. The mice lacking this population of basal cells instead had much better outcomes. That's what we're excited about. These findings put us on firm ground to find therapies that correct the bad behavior of basal stem cells."

Targeting steps on the pathway between IL-33 and basal cell activation could form the basis of broadly effective therapies to prevent or treat lung disease caused by a variety of viruses and perhaps other forms of injury in the lung and other sites where the body meets the outside world, Holtzman said.

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Cosmic rays may be key to understanding galactic dynamics

Cosmic rays are charged subnuclear particles that move close to the speed of light, constantly raining down on the Earth. These particles are relativistic, as defined by Albert Einstein's special relativity, and manage to generate a magnetic field that controls the way they move within the galaxy.

Gas within the interstellar medium is composed of atoms, mostly hydrogen and mostly ionized, meaning its protons and electrons are separated. While moving around within this gas, cosmic rays kickstart the background protons, which causes a collective plasma wave movement akin to the ripples on a lake when you toss in a stone.

The big question is how cosmic rays deposit their momentum into the background plasma that composes the interstellar medium. In Physics of Plasmas, from AIP Publishing, plasma astrophysicists in France review recent developments within the field of studying the streaming instability triggered by cosmic rays within astrophysical and space plasma.

"Cosmic rays may help explain aspects of our galaxy from its smallest scales, such as protoplanetary disks and planets, to its largest scales, such as galactic winds," said Alexandre Marcowith, from the University of Montpellier.

Until now, cosmic rays were viewed as being a bit apart within galaxy "ecology." But because instability works well and is stronger than expected around cosmic ray sources, such as supernova remnants and pulsars, these particles likely have far more impacts on galactic dynamics and the star formation cycle than previously known.

"This is not really a surprise, but more of a paradigm shift," Marcowith said. "In science and astrophysics, everything is connected."

Supernova shock waves expanding the interstellar/intergalactic medium "are known to accelerate cosmic rays, and because cosmic rays are streaming away, they may have contributed to generating the magnetic field seeds necessary to explain the actual magnetic field strengths we observe around us," said Marcowith.

After the amplitude of a plasma wave is reduced or damped over time, much like those generated by a stone thrown into a lake, it heats the gas of the plasma. Meanwhile, it helps scatter cosmic rays.

For this to occur, the waves need wavelengths of the same order as the cosmic ray gyro radius. Cosmic rays possess a helical (spiral) motion around the magnetic field, and its radius is called the Larmor radius.

"Say you are driving a car on a winding road. If the wavelength is of the same order as your wheel size, it will be difficult to drive," said Marcowith.

Cosmic rays are strongly scattered by these waves, and the main instability at the origin of these perturbations (waves) is the streaming instability associated with the collective streaming motion of cosmic rays.

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Drinking sufficient water could prevent heart failure

Staying well-hydrated throughout life could reduce the risk of developing heart failure, according to research presented at ESC Congress 2021.

“Our study suggests that maintaining good hydration can prevent or at least slow down the changes within the heart that lead to heart failure,” said study author Dr. Natalia Dmitrieva of the National Heart, Lung, and Blood Institute, part of the National Institutes of Health, Bethesda, US. “The findings indicate that we need to pay attention to the amount of fluid we consume every day and take action if we find that we drink too little.”

Recommendations on daily fluid intake vary from 1.6 to 2.1 litres for women and 2 to 3 litres for men. However, worldwide surveys have shown that many people do not meet even the lower ends of these ranges. Serum sodium is a precise measure of hydration status: when people drink less fluid, the concentration of serum sodium increases. The body then attempts to conserve water, activating processes known to contribute to the development of heart failure.

Dr. Dmitrieva said: “It is natural to think that hydration and serum sodium should change day to day depending on how much we drink on each day. However, serum sodium concentration remains within a narrow range over long periods,3 which is likely related to habitual fluid consumption.”

This study examined whether serum sodium concentration in middle age, as a measure of hydration habits, predicts the development of heart failure 25 years later. The researchers also examined the connection between hydration and thickening of the walls of the heart's main pumping chamber (left ventricle) – called left ventricular hypertrophy – which is a precursor to heart failure diagnosis.

The analysis was performed in 15,792 adults in the Atherosclerosis Risk in Communities (ARIC) study. Participants were 44 to 66 years old at recruitment and were evaluated over five visits until age 70 to 90.

Participants were divided into four groups based on their average serum sodium concentration at study visits one and two (conducted in the first three years): 135–139.5, 140–141.5, 142–143.5, and 144–146 mmol/l. For each sodium group, the researchers then analysed the proportion of people who developed heart failure and left ventricular hypertrophy at visit five (25 years later).

Higher serum sodium concentration in midlife was associated with both heart failure and left ventricular hypertrophy 25 years later. Serum sodium remained significantly associated with heart failure and left ventricular hypertrophy after adjusting for other factors related to the development of heart failure: age, blood pressure, kidney function, blood cholesterol, blood glucose, body mass index, sex and smoking status. Every 1 mmol/l increase in serum sodium concentration in midlife was associated with 1.20 and 1.11 increased odds of developing left ventricular hypertrophy and heart failure, respectively, 25 years later.

The risks of both left ventricular hypertrophy and heart failure at age 70 to 90 began to increase when serum sodium exceeded 142 mmol/l in midlife.

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Studying mosquito immune cells could improve understanding of disease transmission

A new study that details mosquito immune cells could shed light on the insect immune system and how mosquitoes transmit parasites that cause malaria.

A new study, published recently in the peer-reviewed scientific journal eLife, identifies several new forms of mosquito immune cells, providing new clarity into the mosquito immune system. Immune cells play a central role in the immune response of mosquitoes toward malaria parasites and viruses after these pathogens are taken up upon feeding on an infected person. It's a field of study that has remained poorly understood due to the lack of genetic tools, said Ryan Smith, an associate professor of entomology at Iowa State University and lead author of the study.

"These experiments lay the foundation for a better understanding of how these immune cells function that could lead to a future when humans are able to make mosquitoes unable to transmit disease," Smith said.

The new study utilized single-cell RNA sequencing, a relatively new technique that allows researchers to examine the cellular messages within individual cells, to characterize mosquito immune cells, known as hemocytes. The study found mosquito hemocytes show greater complexity than previously thought, evidence of cell differentiation, and that some cells may even undergo a maturation process. The authors also provided comparative analysis to single-cell studies in other insect systems, highlighting important similarities and differences between mosquitoes and other insects. The new study is an important first step for future exploration of the mosquito immune system, which could be important for gaining better understanding of how mosquitoes transmit pathogens, such as malaria parasites, to humans through their bite.

"There's a big body of evidence that suggests that immune cells of mosquitoes are really critical to their ability to transmit disease," Smith said. "From that perspective, we haven't really known a great deal about the molecular aspect of what those immune cells look like."

Previous evidence suggests immune cells mediate disease pathways in mosquitoes, and play vital roles in killing malaria parasites at multiple stages in the mosquito host. The new study sets the stage for future research aimed at answering those questions, he said.

Smith even envisions a future, though it's still years away, when this line of research could lead to the production of mosquitoes genetically modified to overexpress certain immune cell populations that reduce the ability of a mosquito to transmit pathogens that cause mosquito-borne disease. These resistant mosquitoes could then be introduced into wild mosquito populations to breed and spread these genetic traits. The result could be mosquito populations that are less likely to spread disease to humans, though Smith cautions it's all purely theoretical at this point.

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Male Y chromosome facilitates the evolution of sex differences in body size

Females and males differ in many ways and yet they share the same genome. The only exception is the male Y chromosome. Using beetles as a study system, new research from Uppsala University, now published in Nature Ecology & Evolution, shows that despite of the Y chromosome containing very few genes, it can dramatically change male body size and thus facilitate the evolution of sex differences.

Females and males typically differ in many ways in their morphology, physiology and behaviour. How such sex differences, known as sexual dimorphism, evolve is a puzzle because females and males share the same set of genes and an evolutionary change in one sex should cause a correlated change even in the other sex, thereby preventing sex differences from evolving. The new study shows that even small amounts of genetic differences between the sexes can facilitate the evolution of sexual dimorphism such that it can evolve in just a few generations.

"Our experiments show that the autosomes as well as both sex chromosomes, the X and Y, can harbor genetic variation important for sexual dimorphism, but the Y chromosome alone can alter the sex difference in size by as much as 30 percent. This is remarkable because in these beetles the Y chromosome contains just a handful of genes and represents a very small fraction of the genome, just like in humans. Many have thought that the Y only affects the most important reproductive processes in males, namely sperm production. Our findings suggest that the Y chromosome may have a broader role than previously appreciated," says Philipp Kaufmann, a PhD student at the Uppsala University's Department of Ecology and Genetics and the first author of the study.

The evolution of sexual dimorphism is however not only dependent on where in the genome genetic variation resides, but also on how natural and sexual selection can act on it. With the help of lab evolution, the research team showed that sexual size dimorphism could evolve when selecting on male size, but that when selection acted only on females, the shared part of the genome caused a correlated evolutionary response in males preventing dimorphism from evolving.

"The most drastic change in sexual dimorphism, an increase by 50 percent in only ten generations, occurred when we applied selection sexually antagonistically -- favoring the opposite body size in the two sexes. This shows that under right kind of selection sex differences can clearly evolve rapidly, perhaps more easily than was previously thought," says Elina Immonen, Assistant Professor at the Department of Ecology and Genetics, Uppsala University, and the principle investigator of the study.

"Combining information of what kind of genetic variation is available to selection with different forms of selection is a powerful way to test the determinants of evolution of sex differences. By isolating the effect of Y chromosome variation from the rest of the genome, we could directly demonstrate how large the effect of the Y chromosome is, something we didn't expect to see when we started the work and this has helped understand how sexual dimorphism has evolved in this species. Future work will tell us more regarding how the Y chromosome can have such a large effect on males and how general its role is in the evolution of sex differences across taxa," Immonen concludes.

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Geologists dig into Grand Canyon's mysterious gap in time

A new study led by the University of Colorado Boulder reveals the complex history behind one of the Grand Canyon's most well-known geologic features: A mysterious and missing gap of time in the canyon's rock record that covers hundreds of millions of years.

The research comes closer to solving a puzzle, called the "Great Unconformity," that has perplexed geologists since it was first described nearly 150 years ago.

Think of the red bluffs and cliffs of the Grand Canyon as Earth's history textbook, explained Barra Peak, lead author of the new study and a graduate student in geological sciences at CU Boulder. If you scale down the canyon's rock faces, you can jump back almost 2 billion years into the planet's past. But that textbook is also missing pages: In some areas, more than 1 billion years' worth of rocks have disappeared from the Grand Canyon without a trace.

Geologists want to know why.

"The Great Unconformity is one of the first well-documented geologic features in North America," Peak said. "But until recently, we didn't have a lot of constraints on when or how it occurred."

Now, she and her colleagues think they may be narrowing in on an answer in a paper published this month in the journal Geology. The team reports that a series of small yet violent faulting events may have rocked the region during the breakup of an ancient supercontinent called Rodinia. The resulting havoc likely tore up the earth around the canyon, causing rocks and sediment to wash away and into the ocean.

The team's findings could help scientists fill in missing pieces of what happened during this critical period for the Grand Canyon -- today one of North America's foremost natural wonders.

"We have new analytical methods in our lab that allow us to decipher the history in the missing window of time across the Great Unconformity," said Rebecca Flowers, coauthor of the new study and a professor of geological sciences. "We are doing this in the Grand Canyon and at other Great Unconformity localities across North America."

Beautiful lines

It's a mystery that goes back a long way. John Wesley Powell, the namesake of today's Lake Powell, first saw the Great Unconformity during his famed 1869 expedition by boat down the rapids of the Colorado River.

Peak, who completed a similar research rafting trip through the Grand Canyon in spring 2021, said that the feature is stark enough that you can see it from the river.

"There are beautiful lines," Peak said. "At the bottom, you can see very clearly that there are rocks that have been pushed together. Their layers are vertical. Then there there's a cutoff, and above that you have these beautiful horizontal layers that form the buttes and peaks that you associate with the Grand Canyon."

The difference between those two types of rocks is significant. In the western part of the canyon toward Lake Mead, the basement stone is 1.4 to 1.8 billion years old. The rocks sitting on top, however, are just 520 million years old. Since Powell's voyage, scientists have seen evidence of similar periods of lost time at sites around North America.

"There's more than a billion years that's gone," Peak said. "It's also a billion years during an interesting part of Earth's history where the planet is transitioning from an older setting to the modern Earth we know today."

A continent splits

To explore the transition, Peak and her colleagues employed a method called "thermochronology," which tracks the history of heat in stone. Peak explained that, when geologic formations are buried deep underground, the pressure building on top of them can cause them to get toasty. That heat, in turn, leaves a trace in the chemistry of minerals in those formations.

Using this approach, the researchers conducted a survey of samples of rock collected from throughout the Grand Canyon. They discovered that the history of this feature may be more convoluted than scientists have assumed. In particular, the western half of the canyon and its eastern portion (the part that tourists are most familiar with) may have undergone different geologic contortions throughout time.

"It's not a single block with the same temperature history," Peak said.

Roughly 700 million years ago, basement rock in the west seems to have risen to the surface. In the eastern half, however, that same stone was under kilometers of sediment.

The difference likely came down to the breakup of Rodinia, a gigantic land mass that began to pull apart at about the same time, Peak said. The researchers results suggest that this major upheaval may have torn at the eastern and western halves of the Grand Canyon in different ways and at slightly different times -- producing the Great Unconformity in the process.

Peak and her colleagues are now looking at other sites of the Great Unconformity in North America to see how general this picture might be. For now, she's excited to watch geologic history play out in one of the country's most picturesque landscapes.

"There are just so many things there that aren't present anywhere else," she said. "It's a really amazing natural lab."

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Interstellar comets like Borisov may not be all that rare

In 2019, astronomers spotted something incredible in our backyard: a rogue comet from another star system. Named Borisov, the icy snowball traveled 110,000 miles per hour and marked the first and only interstellar comet ever detected by humans.

But what if these interstellar visitors -- comets, meteors, asteroids and other debris from beyond our solar system -- are more common than we think?

In a new study published Monday in the Monthly Notices of the Royal Astronomical Society, astronomers Amir Siraj and Avi Loeb at the Center for Astrophysics | Harvard & Smithsonian (CfA) present new calculations showing that in the Oort Cloud -- a shell of debris in the farthest reaches of our solar system -- interstellar objects outnumber objects belonging to our solar system.

"Before the detection of the first interstellar comet, we had no idea how many interstellar objects there were in our solar system, but theory on the formation of planetary systems suggests that there should be fewer visitors than permanent residents," says Siraj, a concurrent undergraduate and graduate student in Harvard's Department of Astronomy and lead author of the study. "Now we're finding that there could be substantially more visitors."

The calculations, made using conclusions drawn from Borisov, include significant uncertainties, Siraj points out. But even after taking these into consideration, interstellar visitors prevail over objects that are native to the solar system.

"Let's say I watch a mile-long stretch of railroad for a day and observe one car cross it. I can say that, on that day, the observed rate of cars crossing the section of railroad was one per day per mile," Siraj explains. "But if I have a reason to believe that the observation was not a one-off event -- say, by noticing a pair of crossing gates built for cars -- then I can take it a step further and begin to make statistical conclusions about the overall rate of cars crossing that stretch of railroad."

But if there are so many interstellar visitors, why have we only ever seen one?

We just don't have the technology to see them yet, Siraj says.

Consider, he says, that the Oort Cloud spans a region some 200 billion to 100 trillion miles away from our Sun -- and unlike stars, objects in the Oort Cloud don't produce their own light. Those two factors make debris in the outer solar system incredibly hard to see.

Senior astrophysicist Matthew Holman, who was not involved in the research, says the study results are exciting because they have implications for objects even closer than the Oort Cloud.

"These results suggest that the abundances of interstellar and Oort cloud objects are comparable closer to the Sun than Saturn. This can be tested with current and future solar system surveys," says Holman, who is the former director of the CfA's Minor Planet Center, which tracks comets, asteroids and other debris in the solar system.

"When looking at the asteroid data in that region, the question is: are there asteroids that really are interstellar that we just didn't recognize before?" he asks.

Holman explains that there are some asteroids that get detected but aren't observed or followed up on year after year. "We think they are asteroids, then we lose them without doing a detailed look."

Loeb, study co-author and Harvard astronomy professor, adds that "interstellar objects in the planetary region of the solar system would be rare, but our results clearly show they are more common than solar system material in the dark reaches of the Oort cloud."

Observations with next-generation technology may help confirm the team's results.

The launch of the Vera C. Rubin Observatory, slated for 2022, will "blow previous searches for interstellar objects out of the water," Siraj says, and hopefully help detect many more visitors like Borisov.

The Transneptunian Automated Occultation Survey (TAOS II), which is specifically designed to detect comets in the far reaches of our solar system, may also be able to detect one of these passersby. TAOS II may come online as early as this year.

The abundance of interstellar objects in the Oort Cloud suggests that much more debris is left over from the formation of planetary systems than previously thought, Siraj says.

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The Hobbit’s bite gets a stress test

If you've ever suffered from a sore jaw that popped or clicked when you chewed gum or crunched hard foods, you may be able to blame it on your extinct ancestors.

That's according to a Duke University-led study of the chewing mechanics of an ancient human relative called Homo floresiensis, which inhabited the Indonesian island of Flores before our species arrived there some 50,000 years ago.

Not much more than three feet tall, the hominin's diminutive size earned it the nickname "the Hobbit," after the characters in J.R.R. Tolkien's "The Lord of the Rings." For the new study, which was published Aug. 13 in the journal Interface Focus, the researchers wanted to understand how the Hobbit's skull behaved while it ate its food.

However, thousands of years of fossilization had left its skull -- the only one that has been found so far -- damaged and misshapen. Before the researchers could test it out, they had to restore it as close to its original shape as possible. Collaborators at Italy's University of Bologna created a 3D virtual model, built from X-ray CT scans, digitally filling in the missing pieces to reconstruct what the skull of Homo floresiensis might have looked like when it roamed the island some 100,000 to 60,000 years ago.

From that, they used computer simulations and a technique called finite element analysis to give the virtual skull characteristics that mimic the real thing, such as the stiffness of the bones and the pulling action of the muscles. Then they had the virtual skull chomp down with its back teeth -- premolars and molars -- and analyzed the forces at work with each bite, essentially subjecting it to a digital crash test.

The researchers mapped the strains within their digital model of the Hobbit's facial bones during biting, comparing the results to similar simulations for earlier human relatives called australopiths that lived some two to three million years ago in Africa, along with chimpanzees and humans living today.

The team determined that the Hobbit's bite could have exerted around 1300 Newtons of force, comparable to the chomping power of modern humans and several of our extinct cousins. But had it bitten down too vigorously on a hard nut or a tough hunk of meat, the findings suggest Homo floresiensis would have been at greater risk than our earlier human kin of straining its facial bones, or dislocating the joint where the lower and upper jaws meet.

"We don't really know what Homo floresiensis ate," said first author Rebecca Cook, a doctoral student in evolutionary anthropology at Duke. Patterns of wear on the teeth, combined with pygmy elephant bones and other animal remains unearthed from the same cave where the Hobbit was found suggest that it ate at least some meat.

But the results suggest that exceedingly hard or tough foods, which would have been no problem for an australopith to gnaw on or crack open, might have given the Hobbit a TMJ headache.

"Similar patterns are observed in modern humans," Cook said.

Millions of years of human evolution gave us smaller teeth and more lightweight skulls, because cooking our food and slicing and pounding it with stone tools, and probably also eating meat, made having overbuilt skulls unnecessary.

But years after the Hobbit's discovery its facial features remain a puzzle. Its skull had a curious mix of traits, some of which -- like its heavyset lower jaw -- are similar to our earlier and more ape-like ancestors, while others -- like its small delicate face -- resemble humans today.

"This can make it confusing as to where this species falls on the family tree of hominin evolutionary relationships," Cook said.

The new study suggests this shift to smaller faces, weaker bites and achey jaws evolved early, before the common ancestors of Homo floresiensis and modern humans went their separate ways.

Justin Ledogar, Duke researcher and senior author of the study, says the next step is to do similar analyses on earlier members of the genus Homo, including Homo erectus. The first known hominin to use fire and cook food, this species also had smaller teeth, jaws and faces than earlier hominins, and is thought by some to be the ancestor of Homo floresiensis.

The researchers say the work could help answer lingering questions about where Homo floresiensis came from, how it lived and how it fits into the human evolutionary tree.

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Lightweight composite material inspects itself: Changes in color indicate deformations

ETH Zurich researchers have developed a new type of laminate that changes colour as soon as the material is deformed. This way, the materials researchers can kill two birds with one stone: a lightweight composite material that inspects itself.

Lightweight construction has found its way into many areas, especially automotive manufacturing, shipbuilding and aircraft construction. In addition to traditional lightweight metals such as aluminium, magnesium or titanium, load-​bearing applications are increasingly featuring composite materials. This is driving a concurrent need to develop new techniques and methods for the early detection of damage to or even the possible failure of such as yet understudied materials.

Researchers from the Complex Materials Group at ETH Zurich, working in collaboration with researchers from the University of Fribourg, have now adopted an approach that has recently garnered attention in materials research: they have created a lightweight material that uses a colour change to indicate internal deformation and thus possible material failure at an early stage. Composed of individual layers, their laminate is translucent, break-​resistant and yet very lightweight.

Artificial mother-​of-pearl combined with polymer

The laminate is composed of alternating layers of a plastic polymer and artificial nacre or mother-​of-pearl. The latter is a speciality of the Complex Materials Laboratory and is modelled on the biological example of the mussel shell. It consists of countless glass platelets arranged in parallel, which are compacted, sintered and solidified using an polymeric resin. This makes it extremely hard and break-​resistant.

The second layer consists of a polymer to which the researchers added an indicator molecule synthesised specifically for this application at the University of Fribourg. The molecule is activated as soon as the polymer experiences stretching forces, and this changes its fluorescence. The more the material stretches and the more of these molecules are activated, the more intense the fluorescence becomes.

Fluorescence indicates overstressed parts

"We used fluorescent molecules because you can measure the increase in fluorescence very well and you don't have to rely on subjective perception," says Tommaso Magrini, lead author of the study, which was recently published in the journal ACS Applied Materials and Interfaces. The system could also have been set up to produce a colour change that would be directly perceptible from the outside. But: "The perception of colours is subjective and it is difficult to draw conclusions about changes in the material," Magrini says.

With the help of fluorescence, the researchers can now identify overstressed areas within the composite material even before fractures form. This allows early detection of vulnerable areas in a structure before catastrophic failure occurs. One possible application of the novel laminate is in components in the load-​bearing structures found in buildings, aircraft or vehicles, where it is essential to detect their failure at an early stage.

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Gene editing could render mosquitoes infertile, reducing disease spread

Mosquitoes spread viruses that cause potentially deadly diseases such as Zika, dengue fever and yellow fever. New U.S. Army-funded research uses gene editing to render certain male mosquitoes infertile and slow the spread of these diseases.

Researchers at the Army's Institute for Collaborative Biotechnologies and the University of California Santa Barbara used a gene editing tool known as CRISPR-Cas9 to target a specific gene tied to fertility in male mosquitoes. CRISPR-Cas9 is a genome editing tool that is creating a buzz in the science world, according to yourgenome.org. It is "faster, cheaper and more accurate than previous techniques of editing DNA and has a wide range of potential applications."

Researchers experimented with the Aedes aegypti mosquitoes, which are found in tropical, subtropical and temperate regions throughout the world. The study, published in the Proceedings of the National Academy of Sciences, discerned how a mutation can suppress the fertility of female mosquitoes.

"This is yet one more important and exciting example of how synthetic biology tools are demonstrating unparalleled utility," said Dr. James Burgess, ICB program manager for the U.S. Army Combat Capabilities Development Command, now known as DEVCOM, Army Research Laboratory. "In this case, it's a precision increase from chainsaw to a scalpel leading to the correct biochemical outcome that could substantially reduce the population of a very infectious mosquito."

To manage populations, scientists use a vector-control practice called the sterile insect technique in which they raise a lot of sterile male insects and they then release these males in numbers that overwhelm their wild counterparts. Females that mate with sterile males before finding a fertile one are themselves rendered infertile, thereby decreasing the size of the next generation.

Repeating this technique several times has the potential to crash the population because each generation is smaller than the last; releasing a similar number of sterile males has a stronger effect over time.

The sterile insect technique is effective in managing a number of agricultural pests, including the Mediterranean fruit fly, a crop pest in California. It has also been attempted with Aedes aegypti mosquitoes, but with limited success.

In the past, scientists used chemicals or radiation to sterilize male Aedes aegypti, but the chemicals or radiation impacted the mosquitoes' health to such an extent that they were less successful in mating with females, which undercuts the effectiveness of the sterile insect technique.

The research team wanted to identify a more targeted approach with less collateral damage, mutating a gene in mosquitoes that specifically caused male sterility without otherwise impacting the insects' health.

"When CRISPR/Cas9 came out several years ago it just offered new opportunities to do things that you couldn't do before," said Dr. Craig Montell, distinguished professor at UC Santa Barbara. "So, the time seemed right to for us to start working on Aedes aegypti."

Using gene editing in male Aedes aegypti, researchers found that the mutant male mosquitoes produced no sperm, and unlike in previous efforts, the sterile studs were otherwise completely healthy; however, the team wasn't sure whether sperm, albeit defective sperm from the sterile males, was needed to render female mosquitoes infertile, or whether the transfer of seminal fluid was all it took.

In one experiment, researchers introduced 15 mutant males into a group of 15 females for 24 hours. Then they swapped the males for 15 wild-type males, and left them there.

"Essentially, all of the females remained sterile," Montell said. "This confirmed that males could suppress female fertility without producing sperm."

Next the researchers set out to determine how timing played into the effect. They exposed the females to mutant males for different lengths of time. The scientists noticed little difference after 30 minutes, but female fertility quickly dropped after that. Montell noted that females copulated twice on average, even during the first 10 minutes. This indicated that females have to mate with many sterile males before being rendered infertile themselves.

Combining the females with the males for four hours cut female fertility to 20% of normal levels. After eight hours the numbers began leveling out around 10%.

According to Montell, Aedes aegypti populations could easily bounce back from an 80% drop in fertility. The success of sterile insect technique comes from subsequent, successive releases of sterile males, where each release will be more effective than the last as sterile males account for an ever-growing proportion of the population.

The team plans to continue investigating mosquito mating behaviors and fertility. They are devising a way to maintain stocks of males so they are only sterile in the wild and not in the lab. In addition, they are characterizing male mating behavior to uncover new ways to suppress mosquito populations.

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