3D-printed blood vessels bring artificial organs closer to reality

Growing functional human organs outside the body is a long-sought "holy grail" of organ transplantation medicine that remains elusive. New research from Harvard's Wyss Institute for Biologically Inspired Engineering and John A. Paulson School of Engineering and Applied Science (SEAS) brings that quest one big step closer to completion.

A team of scientists created a new method to 3D print vascular networks that consist of interconnected blood vessels possessing a distinct "shell" of smooth muscle cells and endothelial cells surrounding a hollow "core" through which fluid can flow, embedded inside a human cardiac tissue. This vascular architecture closely mimics that of naturally occurring blood vessels and represents significant progress toward being able to manufacture implantable human organs. The achievement is published in Advanced Materials.

"In prior work, we developed a new 3D bioprinting method, known as "sacrificial writing in functional tissue" (SWIFT), for patterning hollow channels within a living cellular matrix. Here, building on this method, we introduce coaxial SWIFT (co-SWIFT) that recapitulates the multilayer architecture found in native blood vessels, making it easier to form an interconnected endothelium and more robust to withstand the internal pressure of blood flow," said first author Paul Stankey, a graduate student at SEAS in the lab of co-senior author and Wyss Core Faculty member Jennifer Lewis, Sc.D.

The key innovation developed by the team was a unique core-shell nozzle with two independently controllable fluid channels for the "inks" that make up the printed vessels: a collagen-based shell ink and a gelatin-based core ink. The interior core chamber of the nozzle extends slightly beyond the shell chamber so that the nozzle can fully puncture a previously printed vessel to create interconnected branching networks for sufficient oxygenation of human tissues and organs via perfusion. The size of the vessels can be varied during printing by changing either the printing speed or the ink flow rates.

To confirm the new co-SWIFT method worked, the team first printed their multilayer vessels into a transparent granular hydrogel matrix. Next, they printed vessels into a recently created matrix called uPOROS composed of a porous collagen-based material that replicates the dense, fibrous structure of living muscle tissue. They were able to successfully print branching vascular networks in both of these cell-free matrices. After these biomimetic vessels were printed, the matrix was heated, which caused collagen in the matrix and shell ink to crosslink, and the sacrificial gelatin core ink to melt, enabling its easy removal and resulting in an open, perfusable vasculature.

Moving into even more biologically relevant materials, the team repeated the printing process using a shell ink that was infused with smooth muscle cells (SMCs), which comprise the outer layer of human blood vessels. After melting out the gelatin core ink, they then perfused endothelial cells (ECs), which form the inner layer of human blood vessels, into their vasculature. After seven days of perfusion, both the SMCs and the ECs were alive and functioning as vessel walls -- there was a three-fold decrease in the permeability of the vessels compared to those without ECs.

Finally, they were ready to test their method inside living human tissue. They constructed hundreds of thousands of cardiac organ building blocks (OBBs) -- tiny spheres of beating human heart cells, which are compressed into a dense cellular matrix. Next, using co-SWIFT, they printed a biomimetic vessel network into the cardiac tissue. Finally, they removed the sacrificial core ink and seeded the inner surface of their SMC-laden vessels with ECs via perfusion and evaluated their performance.

Not only did these printed biomimetic vessels display the characteristic double-layer structure of human blood vessels, but after five days of perfusion with a blood-mimicking fluid, the cardiac OBBs started to beat synchronously -- indicative of healthy and functional heart tissue. The tissues also responded to common cardiac drugs -- isoproterenol caused them to beat faster, and blebbistatin stopped them from beating. The team even 3D-printed a model of the branching vasculature of a real patient's left coronary artery into OBBs, demonstrating its potential for personalized medicine.

"We were able to successfully 3D-print a model of the vasculature of the left coronary artery based on data from a real patient, which demonstrates the potential utility of co-SWIFT for creating patient-specific, vascularized human organs," said Lewis, who is also the Hansjörg Wyss Professor of Biologically Inspired Engineering at SEAS.

In future work, Lewis' team plans to generate self-assembled networks of capillaries and integrate them with their 3D-printed blood vessel networks to more fully replicate the structure of human blood vessels on the microscale and enhance the function of lab-grown tissues.

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Detecting climate change using aerosols

Researchers analyzed long-term aerosol satellite observation big data focusing on the Pacific Ocean downwind of China. Using a newly developed metric that considered aerosols as tracers, they detected altered atmospheric transport patterns associated with climate change. They observed that the distance of transboundary air pollution moving east from China had shortened. Thus, long-term satellite-based Earth observations are crucial for early climate change detection and accurate evaluation of this trend.

Climate change is one of the most significant environmental challenges of present times, leading to extreme weather events, including droughts, forest fires, and floods. The primary driver for climate change is the release of greenhouse gases into the atmosphere due to human activities, which trap heat and raise Earth's temperature. Aerosols (such as particulate matter, PM2.5) not only affect public health but also influence the Earth's climate by absorbing and scattering sunlight and altering cloud properties. Although future climate change predictions are being reported, it is possible that the impacts of climate change could be more severe than predicted. Therefore, it is necessary to detect climate change accurately and as early as possible.

Building on these insights, a research team from Japan, led by Professor Hitoshi Irie from the Center for Environmental Remote Sensing at Chiba University, utilized long-term observational data to study the effect of climate change on transboundary air pollution in the downwind area of China by using aerosols. They utilized a completely unique perspective on how aerosols impact climate and developed a new metric to detect climate change by considering aerosols as tracers.

"The significance of this study lies in the fact that most of its results are derived from observational data. In natural sciences focused on Earth studies, the ultimate goal is to piece together highly accurate data obtained from observations to quantitatively understand the processes occurring on Earth and to pursue immutable truths. Therefore, the more observational data we have, the better. With the continued Earth observations by Japan's major Earth observation satellites (such as the GCOM series, GOSAT series, Himawari series, and ALOS series), we aim to complement these efforts with numerical simulations and data science methodologies to achieve a safe and secure global environment that mitigates the impacts of the climate crisis." explains Prof. Irie.

The research team included Ms. Ying Cai from the Graduate School of Science and Engineering, Chiba University, Dr. Alessandro Damiani from the Center for Climate Change Adaptation, National Institute for Environmental Studies, Dr. Syuichi Itahashi and Professor Toshihiko Takemura from the Research Institute for Applied Mechanics, Kyushu University, and Dr. Pradeep Khatri from Faculty of Science and Engineering, Soka University. Their study was made available online on May 23, 2024, and published in Science of The Total Environment on August 20, 2024.

China is a major contributor to air pollution in East Asia. The downwind area of China analyzed in this study is a unique open ocean area with minimal human interference yet an important zone of transboundary air pollution pathways, making it an ideal location for studying meteorological variations due to climate change.

In their study, the researchers analyzed aerosol optical depth (AOD) datasets derived from satellites, reanalysis datasets, and numerical simulations focused on the Pacific Ocean in the downwind area of China, over 19 years from 2003 to 2021. AOD, a measure of the amount of sunlight blocked by aerosols, is a key factor is analyzing aerosols and their impact on climate change.

The researchers developed a new metric called RAOD which utilized the potential of aerosols as tracers to evaluate the impact of climate change on transboundary air pollution pathways. Using RAOD the researchers were able to quantify significant temporal variations in aerosol transport. They discovered that long-term changes in RAOD due to climate change were outweighed by larger year-to-year variations in the meteorological field. Moreover, seasonal trends showed that aerosols moved west to east during spring and winter, and northward in summer. They concluded that the probability of aerosols from China to be transported far eastward was low, highlighting a shift in transboundary pollution pathways due to global warming. In this study the authors successfully detected climate change using long-term satellite observational data, in contrast to most existing studies that tracked transboundary air pollution using model simulations.

"These results suggest that RAOD is a valuable metric for quantifying the long-term changes in transboundary air pollution pathways due to climate change. These results are particularly significant because most of them are derived from observational data," says Prof. Irie, highlighting the importance of the study. Sharing the future implications of their study he concludes, "The effects of climate change could be more severe than currently predicted. This study will help verify climate change predictions from an unconventional perspective of 'aerosol observation,' enabling a more accurate understanding of climate change progression and implementation of rational countermeasures."

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Early mammals lived longer

What distinguishes the growth and development patterns of early mammals of the Jurassic period? This is the question jointly investigated by researchers of Queen Mary University of London and the University of Bonn. Paleontologists have been able to gauge the lifespan and growth rates of these ancient animals, and even when they reached sexual maturity, by studying growth rings in fossilized tooth roots. The study has now been published in the journal Science Advances.

"Never before have we been able to reconstruct the growth patterns of these early mammals in such detail," says lead author Dr. Elis Newham, a postdoc at Queen Mary University of London who during the study was an Alexander von Humboldt Research Fellow at the University of Bonn, up to March 31, 2024.

For the study, the team analyzed fossilized tooth roots of mammal species from the Early to Late Jurassic periods (200-150 million years ago) found at three separate sites. The finds made in Wales are of some of the oldest known mammalian precursors from the Early Jurassic period, while the fossils found in Oxfordshire, UK are of a very broad array of coexisting early mammals. The fossils from the third site in Portugal date from the Late Jurassic.

Fossil tooth roots X-rayed

The research team studied the fossils using a technique called synchrotron X-ray tomography in which electrons are accelerated to near light speed (unlike regular X-ray imaging). The technique affords several advantages, starting with the fact that the fossils no longer have to be prepared, i.e. cut up into slices, so they can be analyzed whole. Furthermore, images obtained via synchrotron X-ray tomography are of higher quality than images from conventional X-ray microtomography.

Researchers were able to image tiny growth rings in fossilized root cement -- the bone tissue that attaches the teeth to the jaw. "The rings are similar to those in trees, but on a microscopic level," explains Professor Thomas Martin of the Vertebrates -- Mammals working group at the University of Bonn Institute of Organismic Biology, who is a senior author of the study. "Counting the rings and analyzing their thickness and texture enabled us to reconstruct the growth patterns and lifespans of these extinct animals."

The researchers determined that the first signs of the growth patterns characteristic of modern mammals, such as a puberty growth spurt, started emerging roughly 150 million years ago. Early mammals grew much more slowly but lived substantially longer than today's small mammals, with lifespans of eight to fourteen years instead of just one or two as in modern mice, for example. However, it took early mammals years to reach sexual maturity, again in contrast to their modern descendants which reach sexual maturity in just a few months.

"Our findings suggest that the distinctive life history patterns of mammals, characterized by high metabolic rates and extended parental care phases for example, have evolved over millions of years," Dr. Elis Newham explains, "The Jurassic period appears to have been a crucial time for this shift."

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Record-breaking recovery of rocks that originated in Earth's mantle could reveal secrets of planet's history

Scientists have recovered the first long section of rocks that originated in the Earth's mantle, the layer below the crust and the planet's largest component.

The rocks will help unravel the mantle's role in the origins of life on Earth, the volcanic activity generated when it melts, and how it drives the global cycles of important elements such as carbon and hydrogen, according to the team.

The nearly continuous 1,268 metres of mantle rock was recovered from a "tectonic window," a section of the seabed where rocks from the mantle were exposed along the Mid-Atlantic Ridge, during Expedition 399 "Building Blocks of Life, Atlantis Massif" of the ocean drilling vessel JOIDES Resolution in Spring 2023.

With attempts dating back to the early 1960s, the recovery was a record-breaking achievement led by the International Ocean Discovery Program, an international marine research consortium of more than 20 countries that retrieves cores -- cylindrical samples of sediment and rock -- from the ocean floor to study Earth's history.

Since then, the expedition team has been compiling an inventory of the recovered mantle rocks to understand their composition, structure and context.

Their findings, presented in the journal Science, reveal a more extensive history of melting in the recovered rocks than expected.

Lead author Professor Johan Lissenberg from Cardiff University's School of Earth and Environmental Sciences, said: "When we recovered the rocks last year, it was a major achievement in the history of the Earth sciences, but, more than that, its value is in what the cores of mantle rocks could tell us about the makeup and evolution of our planet.

"Our study begins to look at the composition of the mantle by documenting the mineralogy of the recovered rocks, as well as their chemical makeup.

"Our results differ from what we expected. There is a lot less of the mineral pyroxene in the rocks, and the rocks have got very high concentrations of magnesium, both of which results from much higher amounts of melting than what we would have predicted."

This melting occurred as the mantle rose from the deeper parts of the Earth towards the surface.

Results from further analysis of this process could have major implications for the understanding of how magma is formed and leads to volcanism, the researchers claim.

"We also found channels through which melt was transported through the mantle, and so we are able to track the fate of magma after it is formed and travels upwards to the Earth's surface.

"This is important because it tells us how the mantle melts and feeds volcanoes, particularly those on the ocean floor that account for the majority of volcanism on Earth. Having access to these mantle rocks will allow us to make the connection between the volcanoes and the ultimate source of their magmas."

The study also provides initial results on how olivine, an abundant mineral in mantle rocks, reacts with seawater, leading to a series of chemical reactions that produce hydrogen and other molecules that can fuel life.

Scientists believe this might have been one of the underpinning processes in the origin of life on Earth.

Dr Susan Q Lang, an associate scientist in Geology and Geophysics at the Woods Hole Oceanographic Institution, who was a co-chief scientist on the expedition and part of a team continuing to analyse rock and fluid samples, said: "The rocks that were present on early Earth bear a closer resemblance to those we retrieved during this expedition than the more common rocks that make up our continents today.

"Analysing them gives us a critical view into the chemical and physical environments that would have been present early in Earth's history, and that could have provided a consistent source of fuel and favorable conditions over geologically long timeframes to have hosted the earliest forms of life."

The international team of more than 30 scientists from the JOIDES Resolution expedition will continue their research on the recovered drill cores to address a wide range of problems.

Read more at Science Daily

Scientists lay out revolutionary method to warm Mars

Ever since we learned that the surface of planet Mars is cold and dead, people have wondered if there is a way to make it friendlier to life.

In a groundbreaking study published Aug. 7 in Science Advances, researchers from the University of Chicago, Northwestern University, and the University of Central Florida have proposed a revolutionary approach towards terraforming Mars. This new method, using engineered dust particles released to the atmosphere, could potentially warm the Red Planet by more than 50 degrees Fahrenheit, to temperatures suitable for microbial life -- a crucial first step towards making Mars habitable.

The proposed method is over 5,000 times more efficient than previous schemes to globally warm Mars, representing a significant leap forward in our ability to modify the Martian environment.

What sets this approach apart is its use of resources readily available on Mars, making it far more feasible than earlier proposals that relied on importing materials from Earth or mining rare Martian resources.

This strategy would take decades. But it appears logistically easier than other plans proposed so far.

"This suggests that the barrier to warming Mars to allow liquid water is not as high as previously thought," said Edwin Kite, an associate professor of geophysical sciences at the University of Chicago and corresponding author on the study. The lead author was Samaneh Ansari, a graduate student in Prof. Hooman Mohseni's group at Northwestern University.

Astronauts still won't be able to breathe Mars' thin air; making the planet suitable for humans to walk on the surface unaided requires much more work. But perhaps groundwork could be laid, by making the planet habitable for microbes and food crops that could gradually add oxygen to the atmosphere -- much as they have done for Earth during its geologic history.

A new approach to an age-old dream

There is a rich history of proposals to make Mars habitable; Carl Sagan himself came up with one back in 1971. These have ranged from outright daydreams, such as science fiction writers depicting turning one of Mars' moons into a sun, to more recent and scientifically plausible ideas, such as engineering transparent gel tiles to trap heat.

Any plan to make Mars habitable must address several hurdles, including deadly UV rays and salty soil. But the biggest is the planet's temperature; the surface of Mars averages about -80 degrees Fahrenheit.

One strategy to warm the planet could be the same method that humans are unintentionally using here on Earth: releasing material into the atmosphere, which would enhance Mars' natural greenhouse effect, trapping solar heat at the surface.

The trouble is that you would need tons of these materials -- literally. Previous schemes depended on bringing gases from Earth to Mars, or attempting to mine Mars for a large mass of ingredients that aren't very common there -- both are costly and difficult propositions. But the team wondered whether it could be done by processing materials that already exist abundantly on Mars.

We know from rovers like Curiosity that dust on Mars is rich in iron and aluminum. By themselves, those dust particles aren't suitable to warm the planet; their size and composition mean they tend to cool the surface slightly rather than warm it. But if we engineered dust particles that had different shapes or compositions, the researchers hypothesized, perhaps they could trap heat more efficiently.

The researchers designed particles shaped like short rods -- similar in size to commercially available glitter. These particles are designed to trap escaping heat and scatter sunlight towards the surface, enhancing Mars' natural greenhouse effect.

"How light interacts with sub-wavelength objects is fascinating. Importantly, engineering

nanoparticles can lead to optical effects that far exceed what is conventionally expected from

such small particles," said Ansari. Mohseni, who is a co-author, believes that they have just scratched the surface: "We believe it is possible to design nanoparticles with higher efficiency, and even those that can dynamically change their optical properties."

"You'd still need millions of tons to warm the planet, but that's five thousand times less than you would need with previous proposals to globally warm Mars," said Kite. "This significantly increases the feasibility of the project."

Calculations indicate that if the particles were released into Mars' atmosphere continuously at 30 liters per second, the planet would warm by more than 50 degrees Fahrenheit -- and the effect could be noticeable within as soon as months. Similarly, the warming would be reversible, stopping within a few years if release was switched off.

Potential impact and future research

Much work remains to be done, the scientists said. We don't know exactly how fast the engineered dust would cycle out of Mars' atmosphere, for example. Mars does have water and clouds, and, as the planet warms, it's possible that water would increasingly start to condense around the particles and fall back to the surface as rain.

"Climate feedbacks are really difficult to model accurately," Kite cautioned. "To implement something like this, we would need more data from both Mars and Earth, and we'd need to proceed slowly and reversibly to ensure the effects work as intended."

While this method represents a significant leap forward in terraforming research, the researchers emphasize that the study focuses on warming Mars to temperatures suitable for microbial life and possibly growing food crops -- not on creating a breathable atmosphere for humans.

"This research opens new avenues for exploration and potentially brings us one step closer to the long-held dream of establishing a sustainable human presence on Mars," said Kite.

Read more at Science Daily

New report on Great Barrier Reef shows coral cover increases before onset of serious bleaching, cyclones

Coral cover has increased in all three regions on the Great Barrier Reef and is at regional highs in two of the three regions, according to a report by the Australian Institute of Marine Science (AIMS). But the results come with a note of caution.

Most of the underwater surveys contributing to these findings published today, were conducted before and during the recent mass bleaching event, one of the most extensive and serious on record, and have not yet captured how many corals survived or died following the bleaching.    

Surveys in the Central region were also completed before the passage of tropical Cyclone Jasper in December 2023.    

AIMS' Long-Term Monitoring Program (LTMP) leader Dr Mike Emslie said coral cover increases were a positive sign but did not reflect the potentially destructive consequences of the 2024 mass bleaching event. 

"We saw evidence of early onset mortality, particularly in the Southern region, but the full picture of mortality was not yet apparent during this year's surveys," he said.

"While bleached corals are very stressed, they are still alive and are recorded as live coral on our surveys. 

"Some types of corals can remain bleached for months, remaining on a knife edge between survival and death. This is why returning and repeating surveys of the reefs in this vast, complex and dynamic system is so important. This year's results serve as a very important reference against which to measure the impacts of the summer's events."

The next (LTMP) survey season recommences in September and will capture impacts on coral cover from this summer's mass bleaching event and the cyclones, with a full assessment complete by mid-2025.  

"Climate change remains the greatest threat to the Reef because it drives these mass bleaching events. This most recent one was the fifth such event since 2016. These more frequent and extensive marine heatwaves will lead to shortened 'windows' for coral recovery. Recent gains, while encouraging, can be lost in a short amount of time," Dr Emslie said.

Surveys were conducted at 94 Reefs spread through the Northern, Central and Southern Great Barrier Reef between August 2023 and June 2024.    

The Report recorded the following average hard coral coverage:    

•     Northern region (north of Cooktown) -- 39.5%, up from 35.8% last year;    
•     Central region (Cooktown to Proserpine) -- 34%, up from 30.7%;   
•     Southern region (south of Proserpine) -- 39.1%, up from 34%.   

The AIMS report finds that small rises in coral cover this year bring the Northern and Central regions to their highest levels in 38 years of monitoring.  

The surveys also found that crown-of-thorns starfish outbreaks have persisted on some reefs in the Southern region.    

The long term monitoring team surveyed reefs off Townsville after the passage of tropical Cyclone Kirrily in late January, finding evidence of storm damage and declines in hard coral cover ranging from 6% to 10% at Kelso, John Brewer, Helix and Chicken Reefs. Other reefs appear to have escaped with little impact.    

AIMS Research Program Director Dr David Wachenfeld said the regional increases in coral cover are encouraging, showing the Reef's capacity for recovery after reaching their lowest levels within the last 15 years. However, climate change and other disturbances mean this recovery is fragile and Reef resilience is not limitless.    

"In many ways the Reef has had some lucky escapes in recent years. The 2020 and 2022 mass bleaching events had levels of heat stress that were not as intense as the 2016 and 2017 events or the 2024 event. Coupled with very few other events causing widespread coral death, that has led to the levels of coral cover increase we have seen," he said.   

"But the frequency and intensity of bleaching events is unprecedented, and that is only forecast to escalate under climate change, alongside the persistent threat of crown-of-thorns starfish outbreaks and tropical cyclones."    

Aerial surveys undertaken by AIMS and the Great Barrier Reef Marine Park Authority in February and March found bleached corals in the shallows of 73% of reefs surveyed across all three regions.  

In recent weeks, AIMS scientists in separate monitoring programs observed substantial mortality in reefs that were particularly hard hit by the 2024 event.  

"We are only one large scale disturbance event away from a reversal of the recent recovery. The 2024 bleaching event could be that event -- almost half of the 3000 or so reefs that make up the marine park experienced more heat stress than ever recorded," Dr Wachenfeld said.    

"We still don't know how much mortality this event has caused. Our monitoring over the next 12 months will help us to understand how this bleaching event stacks up against the others in the last decade." 

AIMS CEO Professor Selina Stead said AIMS was prioritising research to develop scientific solutions to boost reef resilience under a warming climate.   

"Climate change is increasing pressure on reef systems around the world," she said.  "The 2024 bleaching event was part of the fourth global bleaching event, announced in April.

"These vitally important ecosystems that millions rely upon need strong greenhouse gas emissions reduction, science-based management of local pressures, and input from multiple fields of research if they are to endure.

"At AIMS we are developing a toolbox of interventions to help reefs adapt to and recover from the effects of climate change."

Read more at Science Daily

Giant prehistoric flying reptile took off using similar method to bats, study finds

The pterosaur likely used all four limbs to propel itself in the air, as seen in bats today, researchers have found.

The findings, published today in PeerJ, provide new insights into how pterosaurs managed to take flight despite reaching sizes far larger than modern animals.

The research sheds new light on the flight initiating jumping ability of these animals, some of which had wingspans of over ten meters.

The study, carried out by scientists at the University of Bristol, Liverpool John Moores University, Universidade Federal do ABC and the University of Keele, follows years of analysis and modelling of how muscles interact with bones to create movement in other animals and is now being used to start answering the question of how the largest flying animals known managed to get off the ground.

The team created the first computer model for this kind of analysis of a pterosaur to test three different ways pterosaurs may have taken off: a vertical burst jump using just the legs like those used by primarily ground-dwelling birds, a less vertical jump using just the legs more similar to the jump used by birds that fly frequently, and a four-limbed jump using its wings as well in a motion more like the take-off jump of a bat.

By mimicking these motions, the researchers aimed to understand the leverage available to push the animal into the air.

"Larger animals have greater challenges to overcome in order to fly making the ability of animals as large as pterosaurs to do so especially fascinating." Dr Ben Griffin, the lead author of the study, said.

"Unlike birds which mainly rely on their hindlimbs, our models indicate that pterosaurs were more likely to rely on all four of their limbs to propel themselves into the air."

Read more at Science Daily

Carvings at ancient monument may be world's oldest calendars

Markings on a stone pillar at a 12,000 year-old archaeological site in Turkey likely represent the world's oldest solar calendar, created as a memorial to a devastating comet strike, experts suggest.

The markings at Göbekli Tepe in southern Turkey -- an ancient complex of temple-like enclosures adorned with intricately carved symbols -- could record an astronomical event that triggered a key shift in human civilisation, researchers say.

The research suggests ancient people were able to record their observations of the sun, moon and constellations in the form of a solar calendar, created to keep track of time and mark the change of seasons.

Fresh analysis of V-shaped symbols carved onto pillars at the site has found that each V could represent a single day. This interpretation allowed researchers to count a solar calendar of 365 days on one of the pillars, consisting of 12 lunar months plus 11 extra days.

The summer solstice appears as a separate, special day, represented by a V worn around the neck of a bird-like beast thought to represent the summer solstice constellation at the time. Other statues nearby, possibly representing deities, have been found with similar V-markings at their necks.

Since both the moon's and the sun's cycles are depicted, the carvings could represent the world's earliest so-called lunisolar calendar, based on the phases of the moon and the position of the sun -- pre-dating other known calendars of this type by many millennia.

Ancient people may have created these carvings at Göbekli Tepe to record the date a swarm of comet fragments hit Earth nearly 13,000 years ago -- or 10,850 BC -- researchers say.

The comet strike is suggested to have ushered in a mini ice age lasting over 1,200 years, wiping out many species of large animals. It could also have triggered changes in lifestyle and agriculture thought to be linked to the birth of civilisation soon afterwards in the fertile crescent of West Asia.

Another pillar at the site appears to picture the Taurid meteor stream -- which is thought to be the source of the comet fragments -- lasting 27 days and emanating from the directions of Aquarius and Pisces.

The find also appears to confirm that ancient people were able to record dates using precession -- the wobble in Earth's axis which affects the movement of constellations across the sky -- at least 10,000 years before the phenomenon was documented by Hipparchus of Ancient Greece in 150 BC.

The carvings appear to have remained important to the people of Göbekli Tepe for millennia, suggesting the impact event may have triggered a new cult or religion that influenced the development of civilisation.

The find also supports a theory that Earth faces increased comet strikes as its orbit crosses the path of circling comet fragments, which we normally experience as meteor streams.

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Astronomers uncover risks to planets that could host life

A groundbreaking study has revealed that red dwarf stars can produce stellar flares that carry far-ultraviolet (far-UV) radiation levels much higher than previously believed. This discovery suggests that the intense UV radiation from these flares could significantly impact whether planets around red dwarf stars can be habitable. Led by current and former astronomers from the University of Hawaii Institute for Astronomy (IfA), the research was recently published in the Monthly Notices of the Royal Astronomical Society.

"Few stars have been thought to generate enough UV radiation through flares to impact planet habitability. Our findings show that many more stars may have this capability," said astronomer Vera Berger, who undertook the study while in the Research Experiences for Undergraduates program at IfA, an initiative supported by the National Science Foundation.

Berger and her team used archival data from the GALEX space telescope to search for flares among 300,000 nearby stars. GALEX is a now-decommissioned NASA mission that simultaneously observed most of the sky at near-and far-UV wavelengths from 2003 to 2013. Using new computational techniques, the team mined novel insights from the data.

"Combining modern computer power with gigabytes of decades-old observations allowed us to search for flares on thousands and thousands of nearby stars," said Michael Tucker, a PhD graduate of IfA and now a postdoctoral fellow at Ohio State University.

UV's double edge

According to researchers, UV radiation from stellar flares can either erode planetary atmospheres, threatening their potential to support life, or contribute to the formation of RNA building blocks, which are essential for the creation of life.

This study challenges existing models of stellar flares and exoplanet habitability, showing that far-UV emission from flares is on average three times more energetic than typically assumed, and can reach up to twelve times the expected energy levels.

"A change of three is the same as the difference in UV in the summer from Anchorage, Alaska to Honolulu, where unprotected skin can get a sunburn in less than 10 minutes," said Benjamin J. Shappee, an Associate Astronomer at IfA who mentored Berger.

Hidden causes

The exact cause of this stronger far-UV emission remains unclear. The team believes it might be that flare radiation is concentrated at specific wavelengths, indicating the presence of atoms like carbon and nitrogen.

"This study has changed the picture of the environments around stars less massive than our Sun, which emit very little UV light outside of flares," said Jason Hinkle, a PhD candidate at IfA who co-authored the study.

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Antarctic-wide survey of plant life to aid conservation efforts

The first continent-wide mapping study of plant life across Antarctica reveals growth in previously uncharted areas and is set to inform conservation measures across the region.

The satellite survey of mosses, lichens and algae across the continent will form a baseline for monitoring how Antarctica's vegetation responds to climate change.

Scientists used a European Space Agency satellite to sweep the continent, combined with field measurements taken over several summer seasons, and detected almost 45 square kilometers of vegetation -- roughly three times the size of Lake Windermere in the Lake District, UK.

The international team, led by the University of Edinburgh with the Norwegian Institute for Nature Research, British Antarctic Survey and Scottish Association for Marine Science, found that over 80 per cent of the vegetation growth was contained within the Antarctic Peninsula and neighbouring islands.

The team estimates this growth makes up only 0.12 percent of Antarctica's total ice-free area, highlighting the importance of monitoring key areas of vegetation abundance, which is inadequately protected under the existing Antarctic Specially Protected Area (ASPA) system, experts say.

Antarctic vegetation, dominated by mosses and lichens, has adapted to survive the harsh polar conditions and each type plays an important role in carbon and nutrient recycling on a local level, experts say.

Until now, their spatial coverage and abundance across the continent remained unknown.

Previous research has shown that the environmental sensitivity of Antarctica's vegetative species makes them excellent barometers of regional climate change.

Monitoring their presence in Antarctica, a minimally disturbed landscape, could provide clues as to how similar vegetation types may respond to climate in other fragile ecosystems across the globe, such as parts of the Arctic.

Charlotte Walshaw, PhD researcher from the School of GeoSciences, University of Edinburgh, who led the study, said: "Our continent-scale map provides key information on vegetation presence in areas that are rarely visited by people. This will have profound implications for our understanding of where vegetation is located across the continent, and what factors influence this distribution."

Dr Claudia Colesie, researcher at the University of Edinburgh's School of GeoSciences, who took part in the study, said: "Lichens and mosses in Antarctica encounter the harshest living conditions on the planet on a daily basis. Only the most resilient organisms can thrive there. Now that we know where to look for them, we can provide more targeted conservation measures to safeguard their future."

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Smallest arm bone in human fossil record sheds light on the dawn of Homo floresiensis

A paper out today in Nature Communications reports the discovery of extremely rare early human fossils from the Indonesian island of Flores, including an astonishingly small adult limb bone.

Dated to about 700,000 years old, the new findings shed light on the evolution of Homo floresiensis, the so-called 'Hobbits' of Flores whose remains were uncovered in 2003 at Liang Bua cave in the island's west by a team co-led by Australian-New Zealand archaeologist Professor Mike Morwood (1950-2013).

Archaeological evidence suggests these diminutive, small-brained humans inhabited Liang Bua as recently as 50,000 years ago, a time when our own species (Homo sapiens) was already long established in Australia to the south.

There has been much debate about the origin of the mysterious humans from Flores. It was first hypothesised that Homo floresiensis was a dwarfed descendant of early Asian Homo erectus.

Another theory is that the 'Hobbit' is a late-surviving remnant of a more ancient hominin from Africa that pre-dates Homo erectus and was small in stature to begin with, in which case possible candidates include Homo habilis or the famous 'Lucy' (Australopithecus afarensis).

Other than Liang Bua, hominin fossils have only ever been found at a single location on Flores: the open-air site of Mata Menge 75km to the east of the cave. Located in the sparsely populated tropical grasslands of the So'a Basin, this site has previously yielded several hominin fossils (a jaw fragment and six teeth) excavated from a layer of sandstone laid down by a small stream around 700,000 years ago.

Pre-dating the Liang Bua hominins by 650,000 years, the Mata Menge fossil remains have been shown to belong to at least three individuals with even slightly smaller jaws and teeth than Homo floresiensis, implying that small body size evolved early in the history of Flores hominins.

However, as postcranial elements (bones from below the head) had not been found in the fossil record at this site it could not be confirmed that these So'a Basin hominins were at least as small as, if not slightly smaller than, Homo floresiensis.

It was also unclear what species the Mata Menge fossils belonged to, owing to the lack of more diagnostic specimens. However, some teeth were deemed to be intermediate in form between those of early Asian Homo erectus and Homo floresiensis.

The new study published in Nature Communications was led by Professor Yousuke Kaifu of the University of Tokyo, Iwan Kurniawan of the Center for Geological Survey in Indonesia, and Associate Professor Gerrit van den Bergh from the University of Wollongong.

It reports the discovery of three additional hominin fossils from Mata Menge dating to 700,000 years ago, the outcome of several field seasons of excavations at this site. Most importantly, the new assemblage includes the first postcranial element, a distal shaft of an adult humerus (lower half of the upper arm bone).

The recovery of a fossil limb bone from the Mata Menge excavation site has been long-awaited because of the wealth of evidence it provides regarding the ancestral origin of Homo floresiensis.

Digital microscopy of the microstructure indicates that the small humerus is from an adult individual. Based on the estimated length of the bone, the team was able to calculate the body height of this hominin to be about 100cm tall. This is around 6cm shorter than the estimated body height of the 60,000-year-old Homo floresiensis skeleton from Liang Bua (~106cm, based on the femoral length).

"This 700,000-year-old adult humerus is not just shorter than that of Homo floresiensis, it is the smallest upper arm bone known from the hominin fossil record worldwide," said Professor Adam Brumm from Griffith University's Australian Research Centre for Human Evolution, a co-author of the paper.

"This very rare specimen confirms our hypothesis that the ancestors of Homo floresiensis were extremely small in body size; however, it is now apparent from the tiny proportions of this limb bone that the early progenitors of the 'Hobbit' were even smaller than we had previously thought."

The two additional hominin teeth from Mata Menge are also small in size and one bears shape characteristics that are most consistent with early Homo erectus of Java. This similarity does not support the hypothesis that Homo floresiensis evolved from an earlier and more primitive type of hominin, the likes of which have never been recovered from Indonesia, or indeed the wider region outside Africa.

The Mata Menge human remains, which now total 10 fossil specimens, are from at least four individuals (including two children). All of them are very similar anatomically to the Liang Bua Homo floresiensis and can now be regarded as an older variant of this hominin. However, while a direct ancestor of the 'Hobbit', this earlier form had a less specialised dentition (more primitive teeth) than its descendant at Liang Bua.

Further, it is evident from the tiny arm bone that extreme body size reduction occurred early in the history of the Flores hominins.

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Cracking the code of life: new AI model learns DNA's hidden language

DNA contains foundational information needed to sustain life. Understanding how this information is stored and organized has been one of the greatest scientific challenges of the last century. With GROVER, a new large language model trained on human DNA, researchers could now attempt to decode the complex information hidden in our genome. Developed by a team at the Biotechnology Center (BIOTEC) of Dresden University of Technology, GROVER treats human DNA as a text, learning its rules and context to draw functional information about the DNA sequences. This new tool, published in Nature Machine Intelligence, has the potential to transform genomics and accelerate personalized medicine.

Since the discovery of the double helix, scientists have sought to understand the information encoded in DNA. 70 years later, it is clear that the information hidden in the DNA is multilayered. Only 1-2 % of the genome consists of genes, the sequences that code for proteins.

"DNA has many functions beyond coding for proteins. Some sequences regulate genes, others serve structural purposes, most sequences serve multiple functions at once. Currently, we don't understand the meaning of most of the DNA. When it comes to understanding the non-coding regions of the DNA, it seems that we have only started to scratch the surface. This is where AI and large language models can help," says Dr. Anna Poetsch, research group leader at the BIOTEC.

DNA as a Language

Large language models, like GPT, have transformed our understanding of language. Trained exclusively on text, the large language models developed the ability to use the language in many contexts.

"DNA is the code of life. Why not treat it like a language?" says Dr. Poetsch. The Poetsch team trained a large language model on a reference human genome. The resulting tool named GROVER, or "Genome Rules Obtained via Extracted Representations," can be used to extract biological meaning from the DNA.

"GROVER learned the rules of DNA. In terms of language, we are talking about grammar, syntax, and semantics. For DNA this means learning the rules governing the sequences, the order of the nucleotides and sequences, and the meaning of the sequences. Like GPT models learning human languages, GROVER has basically learned how to 'speak' DNA," explains Dr. Melissa Sanabria, the researcher behind the project.

The team showed that GROVER can not only accurately predict the following DNA sequences but can also be used to extract contextual information that has biological meaning, e.g., identify gene promoters or protein binding sites on DNA. GROVER also learns processes that are generally considered to be "epigenetic," i.e., regulatory processes that happen on top of the DNA rather than being encoded.

"It is fascinating that by training GROVER with only the DNA sequence, without any annotations of functions, we are actually able to extract information on biological function. To us, it shows that the function, including some of the epigenetic information, is also encoded in the sequence," says Dr. Sanabria.

The DNA Dictionary

"DNA resembles language. It has four letters that build sequences and the sequences carry a meaning. However, unlike a language, DNA has no defined words," says Dr. Poetsch. DNA consists of four letters (A, T, G, and C) and genes, but there are no predefined sequences of different lengths that combine to build genes or other meaningful sequences.

To train GROVER, the team had to first create a DNA dictionary. They used a trick from compression algorithms. "This step is crucial and sets our DNA language model apart from the previous attempts," says Dr. Poetsch.

"We analyzed the whole genome and looked for combinations of letters that occur most often. We started with two letters and went over the DNA, again and again, to build it up to the most common multi-letter combinations. In this way, in about 600 cycles, we have fragmented the DNA into 'words' that let GROVER perform the best when it comes to predicting the next sequence," explains Dr. Sanabria.

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Cold antimatter for quantum state-resolved precision measurements

Why does the universe contain matter and (virtually) no antimatter? The BASE international research collaboration at the European Organisation for Nuclear Research (CERN) in Geneva, headed by Professor Dr Stefan Ulmer from Heinrich Heine University Düsseldorf (HHU), has achieved an experimental breakthrough in this context. It can contribute to measuring the mass and magnetic moment of antiprotons more precisely than ever before -- and thus identify possible matter-antimatter asymmetries. BASE has developed a trap, which can cool individual antiprotons much more rapidly than in the past, as the researchers now explain in the scientific journal Physical Review Letters.

After the Big Bang more than 13 billion years ago, the universe was full of high-energy radiation, which constantly generated pairs of matter and antimatter particles such as protons and antiprotons. When such a pair collides, the particles are annihilated and converted into pure energy again. So, all in all, exactly the same quantities of matter and antimatter should be generated and annihilated again, meaning that the universe should be largely matterless as a consequence.

However, there is clearly an imbalance -- an asymmetry -- as material objects do exist. A minuscule amount more matter than antimatter has been generated -- which contradicts the standard model of particle physics. Physicists have therefore been seeking to expand the standard model for decades. To this end, they also need extremely precise measurements of fundamental physical parameters.

This is the starting point for the BASE collaboration ("Baryon Antibaryon Symmetry Experiment"). It involves the universities in Düsseldorf, Hanover, Heidelberg, Mainz and Tokyo, the Swiss Federal Institute of Technology in Zurich and the research facilities at CERN in Geneva, the GSI Helmholtz Centre in Darmstadt, the Max Planck Institute for Nuclear Physics in Heidelberg, the National Metrology Institute of Germany (PTB) in Braunschweig and RIKEN in Wako/Japan.

"The central question we are seeking to answer is: Do matter particles and their corresponding antimatter particles weigh exactly the same and do they have exactly the same magnetic moments, or are there minuscule differences?" explains Professor Stefan Ulmer, spokesperson of BASE. He is a professor at the Institute for Experimental Physics at HHU and also conducts research at CERN and RIKEN.

The physicists want to take extremely high resolution measurements of the so-called spin-flip -- quantum transitions of the proton spin -- for individual, ultra-cold and thus extremely low-energy antiprotons; i.e. the change in orientation of the spin of the proton. "From the measured transition frequencies, we can, among other things, determine the magnetic moment of the antiprotons -- their minute internal bar magnets, so to speak," explains Ulmer, adding: "The aim is to see with an unprecedented level of accuracy whether these bar magnets in protons and antiprotons have the same strength."

Preparing individual antiprotons for the measurements in a way that enables such levels of accuracy to be achieved is an extremely time-consuming experimental task. The BASE collaboration has now taken a decisive step forward in this regard.

Dr Barbara Maria Latacz from CERN and lead author of the study that has now been published as an "editor's suggestion" in Physical Review Letters, says: "We need antiprotons with a maximum temperature of 200 mK, i.e. extremely cold particles. This is the only way to differentiate between various spin quantum states. With previous techniques, it took 15 hours to cool antiprotons, which we obtain from the CERN accelerator complex, to this temperature. Our new cooling method shortens this period to eight minutes."

The researchers achieved this by combining two so-called Penning traps into a single device, a "Maxwell's daemon cooling double trap." This trap makes it possible to prepare solely the coldest antiprotons on a targeted basis and use them for the subsequent spin-flip measurement; warmer particles are rejected. This eliminates the time needed to cool the warmer antiprotons.

The significantly shorter cooling time is needed to obtain the required measurement statistics in a significantly shorter period of time so that measuring uncertainties can be reduced further. Latacz: "We need at least 1,000 individual measurement cycles. With our new trap, we need a measurement time of around one month for this -- compared with almost ten years using the old technique, which would be impossible to realise experimentally."

Ulmer: "With the BASE trap, we have already been able to measure that the magnetic moments of protons and antiprotons differ by max. one billionth -- we are talking about 10-9. We have been able to improve the error rate of the spin identification by more than a factor of 1,000. In the next measurement campaign, we are hoping to improve magnetic moment accuracy to 10-10."

Professor Ulmer on plans for the future: "We want to construct a mobile particle trap, which we can use to transport antiprotons generated at CERN in Geneva to a new laboratory at HHU. This is set up in such a way that we can hope to improve the accuracy of measurements by at least a further factor of 10."

Background: Traps for fundamental particles

Traps can store individual electrically charged fundamental particles, their antiparticles or even atomic nuclei for long periods of time using magnetic and electric fields. Storage periods of over ten years are possible. Targeted particle measurements can then be made in the traps.

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Scientists and climate change: Extreme concern and high level of engagement

Scientists from across academic disciplines are extremely concerned about climate change. Many of them have already changed their own lifestyles or engaged in advocacy and protest, with even more being willing to do so in future. This is evident from a large-scale survey of scientists from all over the world, conducted by an international research team led by the University of Amsterdam. The researchers not only looked at the views of scientists and the extent to which they are engaged in climate action, but also at how the involvement of scientists with climate change can be increased. The research was published on Monday, 5 August, in the journal Nature Climate Change.

'Climate change is an existential threat to humanity,' says postdoctoral researcher Fabian Dablander of the UvA's Institute for Biodiversity and Ecosystem Dynamics and one of the lead authors of the study. 'To secure a liveable future, each of us needs to ask ourselves: how can I best contribute at this crucial moment in human history? Scientists are well placed to help tackle climate change beyond conducting academic research. However, little is known about their wider engagement with the issue. Hence our study, in which we conducted quantitative and qualitative analyses of a survey of over 9,000 researchers from all scientific disciplines, not just climate science.'

Fundamental and personal

Most respondents (83%) in the survey say they are 'quite a bit' or 'a great deal' worried about climate change. The vast majority (91%) of them believe that fundamental changes in social, political and economic systems are needed to truly tackle climate change. Most respondents (84%) also think that significant changes in personal behaviour and lifestyle are needed. Many of them say they have already made significant changes to their lifestyle, by driving less (69%), flying less (51%) and switching to a more plant-based diet (39%).

Willingness to engage

A majority of scientists in the survey believe that climate activist groups can bring about positive change and that scientists should be more engaged in climate advocacy and even protest. A significant proportion of respondents are already engaged in climate advocacy (29%), have participated in legal protest (23%) and/or have even engaged in civil disobedience (10%), and about half say they would be willing to engage in some of these in the future.

Breaking down barriers

Based on the data, Dablander and colleagues then looked at which factors predict scientists' engagement in advocacy and protest. They propose a two-step model of engagement. First, in order for scientists to be willing to engage, they need to overcome mostly intellectual barriers such as a lack of belief in the effectiveness of the actions, lack of identification with activists, lack of knowledge, fear of losing credibility, and fear of repercussions. Second, to actually engage they need to overcome mostly practical barriers such as a perceived lack of skills, lack of time, lack of opportunities, and not knowing any groups involved in climate action.

Based on their two-step model, the researchers propose ways to increase scientists' engagement, such as facilitating interactions between scientists who are already engaged and those who are not, and making institutional reforms, for example by offering more time and money for climate-related actions or rewarding public engagement.

Wake-up call

'Governments and corporations continue to make empty promises that downplay the level of transformation that is required to prevent climate breakdown,' says Adam Aron, professor of psychology at the University of California, San Diego, and a co-author of the study: 'This study makes clear that scientists from all disciplines are very worried and are calling for this fundamental transformation. I hope it helps wake people up and get engaged -- more and more scientists are.'

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Custom implants on demand? Bandages for the heart? 3D printing method makes it possible

In the quest to develop life-like materials to replace and repair human body parts, scientists face a formidable challenge: Real tissues are often both strong and stretchable and vary in shape and size.

A CU Boulder-led team, in collaboration with researchers at the University of Pennsylvania, has taken a critical step toward cracking that code. They've developed a new way to 3D print material that is at once elastic enough to withstand a heart's persistent beating, tough enough to endure the crushing load placed on joints, and easily shapable to fit a patient's unique defects.

Better yet, it sticks easily to wet tissue.

Their breakthrough, described in the Aug. 2 edition of the journal Science, helps pave the way toward a new generation of biomaterials, from internal bandages that deliver drugs directly to the heart to cartilage patches and needle-free sutures.

"Cardiac and cartilage tissues are similar in that they have very limited capacity to repair themselves. When they're damaged, there is no turning back," said senior author Jason Burdick, a professor of chemical and biological engineering at CU Boulder's BioFrontiers Institute. "By developing new, more resilient materials to enhance that repair process, we can have a big impact on patients."

Worm 'blobs' as inspiration

Historically, biomedical devices have been created via molding or casting, techniques which work well for mass production of identical implants but aren't practical when it comes to personalizing those implants for specific patients. In recent years, 3D printing has opened a world of new possibilities for medical applications by allowing researchers to make materials in many shapes and structures.

Unlike typical printers, which simply place ink on paper, 3D printers deposit layer after layer of plastics, metals or even living cells to create multidimensional objects.

One specific material, known as a hydrogel (the stuff that contact lenses are made of), has been a favorite prospect for fabricating artificial tissues, organs and implants.

But getting these from the lab to the clinic has been tough because traditional 3D-printed hydrogels tend to either break when stretched, crack under pressure or are too stiff to mold around tissues.

"Imagine if you had a rigid plastic adhered to your heart. It wouldn't deform as your heart beats," said Burdick. "It would just fracture."

To achieve both strength and elasticity within 3D printed hydrogels, Burdick and his colleagues took a cue from worms, which repeatedly tangle and untangle themselves around one another in three-dimensional "worm blobs" that have both solid and liquid-like properties. Previous research has shown that incorporating similarly intertwined chains of molecules, known as "entanglements," can make them tougher.

Their new printing method, known as CLEAR (for Continuous-curing after Light Exposure Aided by Redox initiation), follows a series of steps to entangle long molecules inside 3D-printed materials much like those intertwined worms.

When the team stretched and weight-loaded those materials in the lab (one researcher even ran over a sample with her bike) they found them to be exponentially tougher than materials printed with a standard method of 3D printing known as Digital Light Processing (DLP). Better yet: They also conformed and stuck to animal tissues and organs.

"We can now 3D print adhesive materials that are strong enough to mechanically support tissue," said co-first author Matt Davidson, a research associate in the Burdick Lab. "We have never been able to do that before."

Revolutionizing care

Burdick imagines a day when such 3D-printed materials could be used to repair defects in hearts, deliver tissue-regenerating drugs directly to organs or cartilage, restrain bulging discs or even stitch people up in the operating room without inflicting tissue damage like a needle and suture can.

His lab has filed for a provisional patent and plans to launch more studies soon to better understand how tissues react to the presence of such materials.

But the team stresses that their new method could have impacts far beyond medicine -- in research and manufacturing too. For instance, their method eliminates the need for additional energy to cure, or harden, parts, making the 3D printing process more environmentally friendly.

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New model refutes leading theory on how Earth's continents formed

The formation of Earth's continents billions of years ago set the stage for life to thrive. But scientists disagree over how those land masses formed and if it was through geological processes we still see today.

A recent paper from the University of Illinois Chicago's David Hernández Uribe in Nature Geoscience adds new information to that debate, poking holes in the leading theory of continent formation.

Hernández Uribe used computer models to study the formation of magmas thought to hold clues to the origin of continents.

Magma is the molten substance that, when it cools, forms rocks and minerals.

Hernández Uribe looked for magmas that match the compositional signature of rare mineral deposits called zircons that date back to the Archaean period of 2.5 to 4 billion years ago, when scientists believed that continents first formed.

Last year, scientists from China and Australia published a paper arguing that Archaean zircons could only be formed by subduction -- when two tectonic plates collide underwater, pushing land mass to the surface.

That process still happens today, causing earthquakes and volcanic eruptions and reshaping the coasts of continents.

But Hernández Uribe, assistant professor of earth and environmental sciences, found that subduction was not necessary to create Archaean zircons.

Instead, he found that the minerals could form through high pressure and temperatures associated with the melting of the Earth's thick primordial crust.

"Using my calculations and models, you can get the same signatures for zircons and even provide a better match through the partial melting of the bottom of the crust," Hernández Uribe said.

"So based on these results, we still do not have enough evidence to say which process formed the continents."

The results also raise uncertainty about when plate tectonics started on Earth.

If Earth's first continents formed by subduction, that meant that continents started moving between 3.6 to 4 billion years ago -- as little as 500 million years into the planet's existence.

But the alternative theory of melting crust forming the first continents means that subduction and tectonics could have started much later.

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Scientists devise method to secure Earth's biodiversity on the moon

New research led by scientists at the Smithsonian proposes a plan to safeguard Earth's imperiled biodiversity by cryogenically preserving biological material on the moon. The moon's permanently shadowed craters are cold enough for cryogenic preservation without the need for electricity or liquid nitrogen, according to the researchers.

The paper, published today in BioScience and written in collaboration with researchers from the Smithsonian's National Zoo and Conservation Biology Institute (NZCBI), Smithsonian's National Museum of Natural History, Smithsonian's National Air and Space Museum and others, outlines a roadmap to create a lunar biorepository, including ideas for governance, the types of biological material to be stored and a plan for experiments to understand and address challenges such as radiation and microgravity. The study also demonstrates the successful cryopreservation of skin samples from a fish, which are now stored at the National Museum of Natural History.

"Initially, a lunar biorepository would target the most at-risk species on Earth today, but our ultimate goal would be to cryopreserve most species on Earth," said Mary Hagedorn, a research cryobiologist at NZCBI and lead author of the paper. "We hope that by sharing our vision, our group can find additional partners to expand the conversation, discuss threats and opportunities and conduct the necessary research and testing to make this biorepository a reality."

The proposal takes inspiration from the Global Seed Vault in Svalbard, Norway, which contains more than 1 million frozen seed varieties and functions as a backup for the world's crop biodiversity in case of global disaster. By virtue of its location in the Arctic nearly 400 feet underground, the vault was intended to be capable of keeping its seed collection frozen without electricity. However, in 2017, thawing permafrost threatened the collection with a flood of meltwater. The seed vault has since been waterproofed, but the incident showed that even an Arctic, subterranean bunker could be vulnerable to climate change.

Unlike seeds, animal cells require much lower storage temperatures for preservation (-320 degrees Fahrenheit or -196 degrees Celsius). On Earth, cryopreservation of animal cells requires a supply of liquid nitrogen, electricity and human staff. Each of these three elements are potentially vulnerable to disruptions that could destroy an entire collection, Hagedorn said.

To reduce these vulnerabilities, scientists needed a way to passively maintain cryopreservation storage temperatures. Since such cold temperatures do not naturally exist on Earth, Hagedorn and her co-authors looked to the moon.

The moon's polar regions feature numerous craters that never receive sunlight due to their orientation and depth. These so-called permanently shadowed regions can be −410 degrees Fahrenheit (−246 degrees Celsius) -- more than cold enough for passive cryopreservation storage. To block out the DNA-damaging radiation present in space, samples could be stored underground or inside a structure with thick walls made of moon rocks.

At the Hawai?i Institute of Marine Biology, the research team cryopreserved skin samples from a reef fish called the starry goby. The fins contain a type of skin cell called fibroblasts, the primary material to be stored in the National Museum of Natural History's biorepository. When it comes to cryopreservation, fibroblasts have several advantages over other types of commonly cryopreserved cells such as sperm, eggs and embryos. Science cannot yet reliably preserve the sperm, eggs and embryos of most wildlife species. However, for many species, fibroblasts can be cryopreserved easily. In addition, fibroblasts can be collected from an animal's skin, which is simpler than harvesting eggs or sperm. For species that do not have skin per se, such as invertebrates, Hagedorn said the team may use a diversity of types of samples depending on the species, including larvae and other reproductive materials.

The next steps are to begin a series of radiation exposure tests for the cryopreserved fibroblasts on Earth to help design packaging that could safely deliver samples to the moon. The team is actively seeking partners and support to conduct additional experiments on Earth and aboard the International Space Station. Such experiments would provide robust testing for the prototype packaging's ability to withstand the radiation and microgravity associated with space travel and storage on the moon.

If their idea becomes a reality, the researchers envision the lunar biorepository as a public entity to include public and private funders, scientific partners, countries and public representatives with mechanisms for cooperative governance akin to the Svalbard Global Seed Bank.

"We aren't saying what if the Earth fails -- if the Earth is biologically destroyed this biorepository won't matter," Hagedorn said. "This is meant to help offset natural disasters and, potentially, to augment space travel. Life is precious and, as far as we know, rare in the universe. This biorepository provides another, parallel approach to conserving Earth's precious biodiversity."

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How the rising earth in Antarctica will impact future sea level rise

The rising earth beneath the Antarctic Ice Sheet will likely become a major factor in future sea level rise, a new study suggests.

Despite feeling like a stationary mass, most solid ground is undergoing a process of deformation, sinking and rising in response to many environmental factors. In Antarctica, melting glacial ice means less weight on the bedrock below, allowing it to rise. How the rising earth interacts with the overlying ice sheet to affect sea level rise is not well-studied, said Terry Wilson, co-author of the study and a senior research scientist at the Byrd Polar and Climate Research Center at The Ohio State University.

In the new study, Wilson's colleagues at McGill University developed a model to predict how these interactions could impact global sea level, finding that if humans can lower greenhouse gas emissions and global warming is slowed, upward shifts in the solid earth could reduce Antarctica's contribution to sea level rise by about 40%, significantly bolstering the best case scenarios for global sea level rise. In this low-emissions scenario, land uplift slows the flow of ice from land to ocean, allowing for more of the ice sheet to be preserved.

Conversely, if humans are unable to lower carbon emissions in time, ice retreat will outpace uplift, pushing ocean water away from Antarctica and amplifying sea level rise. These events could significantly worsen the most dire models of projected sea level rise along populated coastlines, said Wilson.

"Our measurements show that the solid earth that forms the base of the Antarctic ice sheet is changing shape surprisingly quickly," said Wilson. "The land uplift from reduced ice on the surface is happening in decades, rather than over thousands of years."

The study was published today in Science Advances.

To arrive at these conclusions, the team developed a 3D model of the Earth's interior using geophysical field measurements from the Antarctic Network (ANET) of the Polar Earth Observing Network (POLENET) project. The mission is focused on studying the changing polar regions by collecting GPS and seismic data from an array of autonomous systems across Antarctica.

Researchers then performed a number of simulations to capture many possible evolutions of Antarctica's ice sheet and the extent of global sea level rise Earth may experience until the year 2500, according to those parameters.

"We can project what difference it actually will make if we all contribute to a low-emission scenario now, versus what's come to be called 'business as usual' emissions," said Wilson, who is also the lead investigator of the ANET-POLENET project.

She attributes the model's unprecedented level of detail to how deftly it incorporates data from Antarctica. GPS stations monitor how the land is moving and seismometers measure how fast seismic waves from earthquakes travel through the earth, yielding important insight into where the land uplift will be fast or slow.

Surprisingly, according to some of the team's GPS observations processed by researchers at Ohio State, Wilson said, the Antarctic Ice Sheet is currently experiencing a solid earth uplift of about 5 centimeters per year, about 5 times the rate that North America experiences.

Another significant aspect of the study is how the changes in Antarctica under different carbon emissions scenarios will impact coastlines around the world. Because sea level change will not be uniform, the study notes that nearly 700 million people around the world living in coastal regions will be most impacted by rising seas due to Antarctic ice loss.

Since some regions, such as small island nations, will be more vulnerable than others, mitigating environmental conditions like atmospheric and ocean warming is a vital issue for society, said Wilson.

"Many people are now more aware they're experiencing the effects of climate change," she said. "This work reinforces that our actions as individuals, nations and globally can make a difference in what kind of Earth our offspring will experience in their lifetimes."

The study results highlight how complex the relationship between the solid earth and the processes that happen atop it is, as well as the importance of continuing to gather enough data to make prompt and accurate predictions about what the next few centuries of our planet will look like.

"There's a lot of uncertainty in every model and every prediction that you make," said Wilson. "But to document how fast our world is changing, it's very important to continue advancing our ability to make predictions that are more certain, which is the only path that will allow us to tend to our future in a meaningful way."

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What gave the first molecules their stability?

The origins of life remain a major mystery. How were complex molecules able to form and remain intact for prolonged periods without disintegrating? A team at ORIGINS, a Munich-based Cluster of Excellence, has demonstrated a mechanism that could have enabled the first RNA molecules to stabilize in the primordial soup. When two RNA strands combine, their stability and lifespan increase significantly.

In all likelihood, life on Earth began in water, perhaps in a tide pool that was cut off from seawater at low tide but flooded by waves at high tide. Over billions of years, complex molecules like DNA, RNA and proteins formed in this setting before, ultimately, the first cells emerged. To date, however, nobody has been able to explain exactly how this happened.

"We know which molecules existed on the early earth," says Job Boekhoven, Professor of Supramolecular Chemistry at the Technical University of Munich (TUM). "The question is: Can we use this to replicate the origins of life in the lab?" The team led by Boekhoven at the ORIGINS Cluster of Excellence is primarily interested in RNA. "RNA is a fascinating molecule," says Boekhoven. "It can store information and also catalyze biochemical reactions." Scientists therefore believe that RNA must have been the first of all complex molecules to form.

The problem, however, is that active RNA molecules are composed of hundreds or even thousands of bases and are very unstable. When immersed in water, RNA strands quickly break down into their constituent parts -- a process known as hydrolysis. So, how could RNA have survived in the primordial soup?

How did double strands form in the primordial soup?

In laboratory testing, the researchers from TUM and LMU used a model system of RNA bases that join together more easily than naturally occurring bases in our cells today. "We didn't have millions of years available and wanted an answer quickly," explains Boekhoven. The team added these fast-joining RNA bases into a watery solution, provided an energy source and examined the length of the RNA molecules that formed. Their findings were sobering, as the resulting strands of up to five base pairs only survived for a matter of minutes.

The results were different, however, when the researchers started by adding short strands of pre-formed RNA. The free complementary bases quickly joined with this RNA in a process called hybridization. Double strands of three to five base pairs in length formed and remained stable for several hours. "The exciting part is that double strands lead to RNA folding, which can make the RNA catalytically active," explains Boekhoven. Double-stranded RNA therefore has two advantages: it has an extended lifespan in the primordial soup and serves as the basis for catalytically active RNA.

But how could a double strand have formed in the primordial soup? "We're currently exploring whether it's possible for RNAs to form their own complementary strand," says Boekhoven. It is conceivable for a molecule comprising three bases to join with a molecule comprising three complementary bases -- the product of which would be a stable double-strand. Thanks to its prolonged lifespan, further bases could join with it and the strand would grow.

Evolutionary advantage for protocells

Another characteristic of double-stranded RNA could have helped bring about the origin of life. It is firstly important to note that RNA molecules can also form protocells. These are tiny droplets with an interior fully separated from the outside world. Yet, these protocells do not have a stable cell membrane and so easily merge with other protocells, which causes their contents to mix. This is not conducive to evolution because it prevents individual protocells from developing a unique identity. However, if the borders of these protocells are composed of double-stranded DNA, the cells become more stable and merging is inhibited.

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