New insights on how galaxies are formed

Astronomers can use supercomputers to simulate the formation of galaxies from the Big Bang 13.8 billion years ago to the present day. But there are a number of sources of error. An international research team, led by researchers in Lund, has spent a hundred million computer hours over eight years trying to correct these.

The last decade has seen major advances in computer simulations that can realistically calculate how galaxies form.

These cosmological simulations are crucial to our understanding of where galaxies, stars and planets come from.

However, the predictions from such models are affected by limitations in the resolution of the simulations, as well as assumptions about a number of factors, such as how stars live and die and the evolution of the interstellar medium.

To minimise the sources of error and produce more accurate simulations, 160 researchers from 60 higher education institutions -- led by Santi Roca-Fàbrega at Lund University, Ji-hoon Kim at Seoul National University and Joel R. Primack at the University of California -- have collaborated and now present the results of the largest comparison of simulations done ever.

"To make progress towards a theory of galaxy formation, it is crucial to compare results and codes from different simulations. We have now done this by bringing together competing code groups behind the world's best galaxy simulators in a kind of supercomparison," says Santi Roca-Fàbrega, a researcher in astrophysics.

Three papers from this collaboration, known as the CosmoRun simulations, have now been published in The Astrophysical Journal. In these, the researchers have analysed the formation of a galaxy with the same mass as the Milky Way.

The simulation is based on the same astrophysical assumptions about the ultraviolet background radiation produced by the first stars in the Universe, the gas cooling and heating, and the process of star formation.

The new results allow the researchers to conclude that disc galaxies like the Milky Way formed very early in the history of the Universe, in line with observations from the James Webb Telescope.

They have also found a way to make the number of satellite galaxies -- galaxies orbiting larger galaxies -- consistent with observations finally solving a problem well known in the community and known as "the missing satellites problem."

In addition, the team has revealed how the gas surrounding galaxies is the key to realistic simulations, rather than the number and distribution of stars, which had previously been the standard.

"The work has been going on for the past eight years and has entailed running hundreds of simulations and using a hundred million hours of supercomputing facilities," says Santi Roca-Fàbrega.

Now the journey continues to further refine the simulations of galaxy formation.

With each technological achievement, Santi Roca-Fàbrega and his colleagues hope to add new pieces to the dizzying puzzle of the birth and evolution of the universe and galaxies.

Read more at Science Daily

Surprising methane discovery in Yukon glaciers: 'Much more widespread than we thought'

Global melting is prying the lid off methane stocks, the extent of which we do not know. A young researcher from University of Copenhagen has discovered high concentrations of the powerful greenhouse gas in meltwater from three Canadian mountain glaciers, where it was not thought to exist -- adding new unknowns to the understanding of methane emissions from Earth's glaciated regions

The helicopter's rotor blades spin as its skillful pilot performs aerial acrobatics between the steep Yukon mountain sides where PhD student Sarah Elise Sapper is leading her first field expedition deep into the heart of the mountains of northwestern Canada. From the helicopter windows, her eyes fall on the jagged edge of the Donjek glacier: meltwater swirls out from beneath the ice like a whirlpool.

Soon after landing, it becomes apparent that Sarah has stumbled upon an unusual find on the first attempt. Seconds after starting up her portable methane analyzer it is clear that the air is enriched with methane and the culprit is soon found. Collecting a sample of meltwater, she measures concentrations of methane that far exceed expectations.

"We expected to find low values in the meltwater because it is believed that glacial methane emissions require larger ice masses such as vast ice sheets. But the result was quite the opposite. We measured concentrations up to 250 times higher than those in our atmosphere," explains Sarah Elise Sapper of the University of Copenhagen's Department of Geosciences and Natural Resource Management.

The field party lifted off and continued to two more mountain glaciers, Kluane and Dusty. And after measuring the methane in the meltwater of each of those two glaciers, the preliminary finding turned out to be more than an anomaly. Here too, measurements showed high methane concentrations. Somewhere beneath the ice, there are previously unknown sources of the gas.

Demonstrates possibility of widespread methane emissions

"The finding is surprising and raises several important questions within this area of research," says Associate Professor Jesper Riis Christiansen of the Department of Geosciences and Natural Resource Management.

Christiansen, the research article's co-author, believes that the finding demonstrates the possibility of methane being present beneath many of the world's glaciers, ones that have thus far been written off.

"When we suddenly see that even mountain glaciers, which are small in comparison with an ice sheet, are able to form and emit methane, it expands our basic understanding of carbon cycling in extreme environments on the planet. The formation and release of methane under ice is more comprehensive and much more widespread than we thought," he says.

Until now, the prevailing view has been that methane in meltwater could only be found in oxygen- free environments under large masses of ice like the Greenland Ice Sheet.

The researchers assume that the production of methane is biological and happens when an organic carbon source -- e.g., deposits from prehistoric marine organisms, soils, peat or forests -- is decomposed by microorganisms in the absence of oxygen, such as we know from wetlands. As such, it is surprising that the mountain glaciers emit methane.

"The meltwater from the surface of glaciers is oxygen-rich when it travels to the bottom of the ice. So we found it quite surprising that all this oxygen is used up somewhere along the way, so that oxygen-free environments form underneath these mountain glaciers. And even more surprising that it happens to such a degree, that microbes start producing methane and we can observe these high methane concentrations in the water flowing out at the glacier edges" states Sarah Elise Sapper.

"Sarah's findings change our basic understanding and send us back to the drawing board in relation to some of the key mechanisms at play," adds Jesper Riis Christiansen.

An uncertain role for the climate of the future

According to the researchers, the findings in Canada do not immediately spur an increased concern in relation to their effect on climate change. However that conclusion may be temporary.

"Methane plays a major role in warming our planet. The challenge with methane is that it is a super-potent greenhouse gas and increasing emissions will accelerate climate warming. From a global perspective, we can measure how much is emitted into the atmosphere and, roughly speaking, where the methane comes from, using the isotopes found in the atmospheric methane. And for now, the contribution of methane from ice-covered regions on our planet, including ice sheets and glaciers, isn't increasing," explains Jesper Riis Christiansen.

However, he emphasizes that the measurements cannot distinguish between methane from glaciated regions and methane from wetlands. Therefore, the numbers could be deceiving. And, the effect of melting remains unknown.

Jesper Riis Christiansen believes that the findings demand vigilance.

"The three sites Sarah measured were randomly selected due to the availability of a research station and helicopter, yet methane was found in all three. In itself, that is a good reason to better understand the area. There's too much that we don't know, and the melting glaciers expose unknown environments that have remained hidden for thousands of years. In reality, no one knows how emissions will behave," says Jesper Riis Christiansen.

He hopes that a better understanding of methane behaviour beneath glaciers will also help researchers better understand the mechanisms at play when wetlands release methane, and thereby contribute to the development of solutions to remove methane from the atmosphere through oxidation -- e.g., through the use of certain soil types.

A subglacial black box

The actual sources and locations of subglacial methane production actually remain somewhat of a mystery, hidden beneath ice masses of all sizes. Indeed, this methane can only be measured as the meltwater emerges from beneath the ice. And because it originates from large areas below the ice masses, this makes it difficult to access exactly where the production happens.

It is known to not originate from the ice itself, as concentrations both in the ice and meltwater atop it are lower than what is measured at the glacier edge. As such, the researchers believe that the methane must derive from a source beneath the ice. And the best theory, as mentioned, is that it is formed by microbes in oxygen-free pockets and then carried out with meltwater.

But this indirect knowledge of the source leaves a great deal of uncertainty about how much methane is hidden beneath the ice.

"It's a big black box under the ice -- and you could say that the meltwater is prying the lid off it. We do not know whether methane emissions from glacial areas will increase in the future with increased melting, or whether the 'lid' has already been opened to such a degree that the methane beneath the ice is actually being washed out with the meltwater," says Sarah Elise Sapper.

Methane and CO2 are different greenhouse gases

The half-life of methane in the atmosphere is 12 years.

CO2 has a much longer half-life, at roughly 1000 years.

On the other hand, methane is about 25 times more powerful as a greenhouse gas on a 100-year basis and a far more serious threat to global climate in the shorter term.

Due to greenhouse gas-driven climate change, researchers around the world are working to develop ways to capture or store CO2.

Similarly, solutions are being devised to limit the emission of -- or increase the oxidation of -- methane. Doing so requires more knowledge about how methane is formed.

Facts: Carbon circulation of methane and CO2

Biological traces from animal and plant material in the subsoil consist of carbon.

Within these environments, microorganisms have developed an ability to convert carbon into energy in a process where methane is created as a byproduct in the absence of oxygen (e.g. in beneath ice sheets or in wetlands).

However, if the methane is released into an oxygen-rich environment, it can effectively be oxidized and converted into CO2 by microbes. Wetlands play an important role in this process.

Once, in the atmosphere, methane reacts with other chemicals (hydroxyl radicals) which keep the concentrations down.

Read more at Science Daily

Slimming down a colossal fossil whale

A 30 million year-old fossil whale may not be the heaviest animal of all time after all, according to a new analysis by paleontologists at UC Davis and the Smithsonian Institution. The new analysis puts Perucetus colossus back in the same weight range as modern whales and smaller than the largest blue whales ever recorded. The work is published Feb. 29 in PeerJ.

A fossil skeleton of Perucetus was discovered in Peru and described in a paper in Nature last year.

The animal lived about 39 million years ago and belonged to an extinct group of early whales called the basilosaurids.

Perucetus' bones are unusually dense. Mammal bones usually have a solid exterior and are spongy or hollow in the center.

Some animals have more of the center filled in with solid bone, making them dense and heavy.

In aquatic animals, heavy bones can offset buoyancy from body fat and blubber, allowing the animal to maintain neutral buoyancy in water or -- in the case of the hippopotamus -- to walk on river beds.

The fossil whale bones have both extensive in-filling and extra growth of bone on the outside as well, a condition called pachyostosis also seen in some modern aquatic mammals, such as manatees.

Based on a series of assumptions, the original authors (Giovanni Bianucci at the University of Pisa, Italy and colleagues) estimated a body mass for Perucetus of 180 metric tons (ranging from 85 to 340 metric tons). This would make Perucetus as heavy as, or heavier than the biggest blue whales known, even though it is considerably shorter at 17 meters long compared to a blue whale at about 30 meters.

How to weigh a whale?

Professor Ryosuke Motani, a paleobiologist at the UC Davis Department of Earth and Planetary Sciences, said that these estimates would make Perucetus impossibly dense.

"It would have been a job for the whale to stay at the surface, or even to leave the sea bottom -- it would have required continuous swimming against the gravity to do anything in the water," Motani said.

Motani and Nick Pyenson at the Smithsonian Institute National Museum of Natural History reexamined the assumptions used to make those estimates.

The first problem is that Bianucci et al used the fossil bones to estimate the weight of the skeleton, then extrapolated to the weight of the entire animal, assuming that the skeletal and non-skeletal mass would scale at the same rate with increasing body size.

But measurements of other animals show this is not the case, Motani and Pyenson argue.

The original estimates also overestimated how much overall body mass increases as a result of pachyostosis.

But evidence from manatees shows that their bodies are relatively light relative to their skeletal mass.

Motani and Pyenson estimate that the 17-meter long Perucetus weighed in at 60 to 70 tons, considerably less than the known weights of blue whales.

A Perucetus that grew to 20 meters could weigh over 110 tons, still well short of the largest blue whales at 270 tons.

"The new weight allows the whale to come to the surface and stay there while breathing and recovering from a dive, like most whales do," Motani said.

Read more at Science Daily

Human stem cells coaxed to mimic the very early central nervous system

The first stem cell culture method that produces a full model of the early stages of the human central nervous system has been developed by a team of engineers and biologists at the University of Michigan, the Weizmann Institute of Science, and the University of Pennsylvania.

"Models like this will open doors for fundamental research to understand early development of the human central nervous system and how it could go wrong in different disorders," said Jianping Fu, U-M professor of mechanical engineering and corresponding author of the study in Nature.

The system is an example of a 3D human organoid -- stem cell cultures that reflect key structural and functional properties of human organ systems but are partial or otherwise imperfect copies.

"We try to understand not only the basic biology of human brain development, but also diseases -- why we have brain-related diseases, their pathology, and how we can come up with effective strategies to treat them," said Guo-Li Ming, who along with Hongjun Song, both Perelman Professors of Neuroscience at UPenn and co-authors of the study, developed protocols for growing and guiding the cells and characterized the structural and cellular characteristics of the model.

For example, organoids developed using patient-derived stem cells may be used for identifying which drugs offer the most successful treatment. Already, human brain and spinal cord organoids are used to study neurological and neuropsychiatric diseases, but they often mimic one part of the central nervous system and are disorganized. The new model, in contrast, recapitulates the development of all three sections of embryonic brain and spinal cord simultaneously, a feat that has not been achieved in previous models.

"The system itself is really groundbreaking," said Orly Reiner, the Berstein-Mason Professorial Chair of Neurochemistry at Weizmann and co-author of the study who developed cellular tools to identify neural cell types in the model. "A model that mimics this structure and organization has not been done before, and it offers numerous possibilities for studying human brain development and especially developmental brain diseases."

While the model is faithful to many aspects of the early development of the brain and spinal cord, the team notes several important differences. For one, neural tube formation -- the very first stage of central nervous system development -- is very different. The model can't be used to simulate disorders that stem from improper closure of the neural tube such as spina bifida.

Instead, the model started with a row of stem cells roughly the size of the neural tube found in a 4-week-old embryo -- about 4 millimeters long and 0.2 millimeters in width. The team stuck the cells to a chip patterned with tiny channels that the team used to introduce materials that enabled the stem cells to grow and guided them toward building a central nervous system.

The team then added a gel that allowed the cells to grow in three dimensions and chemical signals that nudged them to become the precursors of neural cells. In response, the cells formed a tubular structure. Next, the team introduced chemical signals that helped the cells identify where they were within the structure and progress to more specialized cell types. As a result, the system organized itself to mimic the forebrain, midbrain, hindbrain and spinal cord in a way that mirrors embryonic development.

"As an engineer, the challenging part is to learn neural development and stem cell biology," said Xufeng Xue, first author of the study and a postdoctoral fellow in mechanical engineering U-M. "It was a team effort to make this happen, with amazing collaborators at UPenn and Weizmann."

The team grew the cells for 40 days, simulating development of the central nervous system to about 11 weeks post-fertilization. In this time, the team was able to demonstrate the roles of specific genes in spinal cord development and learn how certain cell types in the early human nervous system differentiate into different cells with specialized functions.

"In many cases, animal models simply do not recapitulate either the characteristics or the degree of severity seen in human brain diseases such as microcephaly," Song said. "Even nonhuman primates are not the same. So in the context of disease biology and treatment strategies, a human cell model is almost irreplaceable."

The team plans to apply the model to study different human brain diseases using patient derived stem cells.

Xue hopes to continue using this model to study the interplay among different parts of the brain during development. He is also interested in studying how the brain sends instructions for movement via the spinal cord. This line of inquiry, which could shed new light on disorders like paralysis, would require the neurons to link up into working circuits -- something that was not observed in this study.

Insoo Hyun, a bioethicist at the Museum of Science in Boston who was not part of the study, notes that experiments like these are closely scrutinized before they are allowed to move forward.

"Research groups must be clear about the scientific question they are trying to answer -- and that the degree of development they allow in the model is the minimum to answer the question," he said.

The model does not include peripheral nerves or functioning neural circuitry -- features that are critical for humans' ability to experience our environment and process that experience.

Read more at Science Daily

Biomolecules from formaldehyde on ancient Mars

Organic materials discovered on Mars may have originated from atmospheric formaldehyde, according to new research, marking a step forward in our understanding of the possibility of past life on the Red Planet.

Scientists from Tohoku University have investigated whether the early atmospheric conditions on Mars had the potential to foster the formation of biomolecules -- organic compounds essential for biological processes.

Their findings, published in Scientific Reports, offer intriguing insights into the plausibility of Mars harboring life in its distant past.

Today, Mars presents a harsh environment characterized by dryness and extreme cold, but geological evidence hints at a more hospitable past.

About 3.8-3.6 billion years ago, the planet probably had a temperate climate, sustained by the warming properties of gases like hydrogen.

In such an environment, Mars may have had liquid water, a key ingredient for life as we know it.

The researchers investigated whether formaldehyde could have formed in the early Martian environment.

Formaldehyde is a simple organic compound that plays a crucial role as a precursor for the formation of vital biomolecules through purely chemical or physical processes.

These biomolecules, like amino acids and sugars, serve as the fundamental building blocks for proteins and RNA, essential components of life.

Using an advanced computer model, the team simulated the potential atmospheric composition of early Mars to explore the potential for formaldehyde production.

The model was built with the assumption that the atmosphere was rich in carbon dioxide, hydrogen, and carbon monoxide.

Their simulations suggest that the ancient Martian atmosphere could have provided a continuous supply of formaldehyde which would have potentially led to the creation of various organic compounds.

This raises the intriguing possibility that the organic materials detected on the Martian surface could have originated from atmospheric sources, particularly during the planet's two earliest geological periods.

"Our research provides crucial insights into the chemical processes that may have occurred on ancient Mars, offering valuable clues to the possibility of past life on the planet," says Shungo Koyama, lead author of the study.

By revealing that there were conditions favorable for the formation of bio molecules, the research broadens our understanding of the planet's ancient capacity to sustain life.

Read more at Science Daily

80 mph speed record for glacier fracture helps reveal the physics of ice sheet collapse

There's enough water frozen in Greenland and Antarctic glaciers that if they melted, global seas would rise by many feet. What will happen to these glaciers over the coming decades is the biggest unknown in the future of rising seas, partly because glacier fracture physics is not yet fully understood.

A critical question is how warmer oceans might cause glaciers to break apart more quickly. University of Washington researchers have demonstrated the fastest-known large-scale breakage along an Antarctic ice shelf. The study, recently published in AGU Advances, shows that a 6.5-mile (10.5 kilometer) crack formed in 2012 on Pine Island Glacier -- a retreating ice shelf that holds back the larger West Antarctic ice sheet -- in about 5 and a half minutes. That means the rift opened at about 115 feet (35 meters) per second, or about 80 miles per hour.

"This is to our knowledge the fastest rift-opening event that's ever been observed," said lead author Stephanie Olinger, who did the work as part of her doctoral research at the UW and Harvard University, and is now a postdoctoral researcher at Stanford University. "This shows that under certain circumstances, an ice shelf can shatter. It tells us we need to look out for this type of behavior in the future, and it informs how we might go about describing these fractures in large-scale ice sheet models."

A rift is a crack that passes all the way through the roughly 1,000 feet (300 meters) of floating ice for a typical Antarctic ice shelf. These cracks are the precursor to ice shelf calving, in which large chunks of ice break off a glacier and fall into the sea. Such events happen often at Pine Island Glacier -- the iceberg observed in the study has long since separated from the continent.

"Ice shelves exert a really important stabilizing influence on the rest of the Antarctic ice sheet. If an ice shelf breaks up, the glacier ice behind really speeds up," Olinger said. "This rifting process is essentially how Antarctic ice shelves calve large icebergs."

In other parts of Antarctica, rifts often develop over months or years. But it can happen more quickly in a fast-evolving landscape like Pine Island Glacier, where researchers believe the West Antarctic Ice Sheet has already passed a tipping point on its collapse into the ocean.

Satellite images provide ongoing observations. But orbiting satellites pass by each point on Earth only every three days. What happens during those three days is harder to pin down, especially in the dangerous landscape of a fragile Antarctic ice shelf.

For the new study, the researchers combined tools to understand the rift's formation. They used seismic data recorded by instruments placed on the ice shelf by other researchers in 2012 with radar observations from satellites.

Glacier ice acts like a solid on short timescales, but it's more like a viscous liquid on long timescales.

"Is rift formation more like glass breaking or like Silly Putty being pulled apart? That was the question," Olinger said. "Our calculations for this event show that it's a lot more like glass breaking."

If the ice were a simple brittle material, it should have shattered even faster, Olinger said. Further investigation pointed to the role of seawater. Seawater in the rifts holds the space open against the inward forces of the glacier. And since seawater has viscosity, surface tension and mass, it can't just instantly fill the void. Instead, the pace at which seawater fills the opening crack helps slow the rift's spread.

"Before we can improve the performance of large-scale ice sheet models and projections of future sea-level rise, we have to have a good, physics-based understanding of the many different processes that influence ice shelf stability," Olinger said.

Read more at Science Daily

Predatory fish use rapid color changes to coordinate attacks

Striped marlin are some of the fastest animals on the planet and one of the ocean's top predators. When hunting in groups, individual marlin will take turns attacking schools of prey fish one at a time. Now a new study reported in the journal Current Biology on February 5 helps to explain how they might coordinate this turn-taking style of attack on their prey to avoid injuring each other. The key, according to the new work, is rapid color changes.

"We documented for the first time rapid color change in a group-hunting predator, the striped marlin, as groups of marlin hunted schools of sardines," says Alicia Burns of Humboldt University in Berlin, Germany.

"We found that the attacking marlin 'lit up' and became much brighter than its group-mates as it made its attack before rapidly returning to its 'non-bright' coloration after its attack ended."

Burns and her colleagues, including Jens Krause, explained that the use of drones in their research has given them a new perspective of how marlins move and hunt.

As they examined the video footage they'd captured via drone, they noticed something unexpected: the stripes on individual marlins got obviously brighter as a fish moved in for an attack.

As they swam away, those stripes dimmed again. Were the fish changing colors to communicate with one another?

To explore this question in the new study, the researchers analyzed 12 high-resolution video clips, each containing two separate attacks on a school of sardines by two different marlin.

They also quantified the contrast of the stripes on the two attacking marlins compared to a randomly chosen marlin that wasn't attacking.

Their analysis confirms that the predatory fish rapidly change color, suggesting that the color change might serve as a reliable signal of an individual's motivation to go in for an attack.

"Color change in predators is rare, but especially so in group-hunting predators," Burns said.

"Although it is known that marlin can change color, this is the first time it's been linked to hunting or any social behavior."

The discovery suggests that marlins have more complicated communication channels than had been suspected.

The researchers propose that the color changes might even serve a dual purpose of confusing their prey.

They now hope to explore this idea, alongside other questions.

For example, they want to find out whether marlins use their color-changing abilities in other contexts.

They're curious to know whether they still change color when hunting solo and how the changes affect their prey.

They are also looking into similar color changes in other predatory species of fish.

Read more at Science Daily

Blindness from some inherited eye diseases may be caused by gut bacteria

Sight loss in certain inherited eye diseases may be caused by gut bacteria, and is potentially treatable by antimicrobials, finds a new study in mice co-led by a UCL and Moorfields researcher.

The international study observed that in eyes with sight loss caused by a particular genetic mutation, known to cause eye diseases that lead to blindness, gut bacteria were found within the damaged areas of the eye.

The authors of the new paper, published in Cell and jointly led by researchers in China, say their findings suggest that the genetic mutation may relax the body's defences, thus allowing harmful bacteria to reach the eye and cause blindness.

The gut contains trillions of bacteria, many of which are key to healthy digestion. However, they can also be potentially harmful.

The researchers were investigating the impact of the Crumbs homolog 1 (CBR1) gene, which is known to be expressed in the retina (the thin layer of cells at the back of the eye) and is crucial to building the blood-retina barrier to regulate what flows in and out of the eye.

The CRB1 gene is associated with inherited eye disease, most commonly forms of Leber congenital amaurosis (LCA) and retinitis pigmentosa (RP); the gene is the cause of 10% of LCA cases and 7% of RP cases worldwide.

Using mouse models, the research team discovered the CRB1 gene is key to controlling the integrity of the lower gastrointestinal tract, the first ever such observation. There, it combats pathogens and harmful bacteria by regulating what passes between the contents of the gut and the rest of the body.

The team found that when the gene has a particular mutation, dampening its expression (reducing its effect), these barriers in both the retina and the gut can be breached, enabling bacteria in the gut to move through the body and into the eye, leading to lesions in the retina that cause sight loss.

Crucially, treating these bacteria with antimicrobials, such as antibiotics, was able to prevent sight loss in the mice even though it did not rebuild the affected cell barriers in the eye.

Inherited eye diseases are the UK's leading cause of blindness in working-age people. Onset of disease may vary from very early childhood to adulthood, but deterioration is irreversible and has lifelong implications. To date, the development of treatments has largely focused on gene therapies.

The findings of this study suggest that simply using antimicrobials might help prevent deterioration in CRB1-associated inherited eye diseases. Future work will investigate whether this applies in humans.

Co-lead author Professor Richard Lee (UCL Institute of Ophthalmology and Moorfields Eye Hospital NHS Foundation Trust) said: "We found an unexpected link between the gut and the eye, which might be the cause of blindness in some patients.

"Our findings could have huge implications for transforming treatment for CRB1-associated eye diseases. We hope to continue this research in clinical studies to confirm if this mechanism is indeed the cause of blindness in people, and whether treatments targeting bacteria could prevent blindness.

"Additionally, as we have revealed an entirely novel mechanism linking retinal degeneration to the gut, our findings may have implications for a broader spectrum of eye conditions, which we hope to continue to explore with further studies."

Read more at Science Daily

Three years later, search for life on Mars continues

In the three years since NASA's Perseverance rover touched down on Mars, the NASA science team has made the daily task of investigating the red planet seem almost mundane.

The rover and its helicopter sidekick Ingenuity have captured stunning images of Mars and collected 23 unique rock core samples along 17 miles of an ancient river delta.

One science team member, University of Cincinnati Associate Professor Andy Czaja, said he sometimes has to remind himself that the project is anything but ordinary.

"This is so cool. I'm exploring another planet," he said.

Czaja teaches in the Department of Geosciences in UC's College of Arts and Sciences. He is a paleobiologist and astrobiologist helping NASA look for evidence of ancient life on Mars using a rover outfitted with custom geoscience and imaging tools with three of his UC graduate students, Andrea Corpolongo, Brianna Orrill and Sam Hall.

Three years into the mission, the rover has performed like a champ, he said.

"Perseverance has excelled. It's been fantastic. It has such capable instrumentation for doing the geology work. It's able to explore distant objects with its zoom lens cameras and can focus on tiny objects at incredible resolution," Czaja said.

Along the way, the mission has recorded a number of firsts: first powered flight, first recorded sounds of Mars, the longest autonomous drive (nearly a half-mile) and new discoveries about the planet's geology, atmosphere and climate.

Czaja was part of the NASA team that decided where on Mars to land the rover. And he remained on the science team that would pore over its daily data and discoveries to decide what the rover should do next.

Among the new discoveries was finding primary igneous rocks in Jezero Crater. These rocks are the hardened result of liquid magma. They offer scientists promising clues about refining the known age of the planet.

Scientists suspect Mars once had long-lived rivers, lakes and streams. Today, water on Mars is found in ice at the poles and trapped below the Martian surface.

Czaja and his student Corpolongo were co-lead authors of a paper published in the Journal of Geophysical Research, Planets that revealed that Mars also may have had hydrothermal systems based on the hydrated magnesium sulfate the rover identified in the volcanic rocks.

"When those rocks cool off and fracture, they become a habitable environment for life," Czaja said.

Corpolongo also led a similar research paper in the same journal co-authored by Czaja detailing the results of the rover's analysis of samples using the SHERLOC deep ultraviolet Raman and fluorescence instrument. Both papers featured contributions from dozens of their fellow NASA researchers on the project.

Samples collected by the rover may finally answer the question about whether we are alone in the universe.

"We have not found any definitive evidence of life in these deposits yet. But if there were fossil microorganisms trapped in the rocks, they would be too small to see with the rover," Czaja said.

Czaja is hopeful funding will be approved for the anticipated Mars Sample Return mission to retrieve the hermetically sealed titanium tubes scientists have spent three years filling with interesting rock cores.

"These hydrated minerals trap water within themselves and record the history of how and when they formed," the study said. "Returning samples of these minerals to Earth would allow researchers to explore the history of Mars' water and climate and possibly evidence of ancient life with the most sensitive instruments possible."

But that was just the beginning. Perseverance began its deliberate exploration from the floor of the crater to the front of the delta, formed by an ancient river or drainage channel where it encountered sedimentary rocks that often contain trapped minerals and another avenue for evidence of ancient life.

And last year the rover made it to the crater's margin in what used to be an enormous lake where it is exploring deposits of magnesium carbonate, which can form geologically or biologically from bacteria.

Czaja said the decision to send Perseverance to Jezero Crater appears to be paying off.

"Absolutely. There were other places we could have gone that might have been just as good," he said. "You won't know until you explore them all. But Jezero was picked for good reason and it has been completely justified."

The helicopter Ingenuity's flying days appear to be over after it sustained rotor damage in January after landing on its 72nd flight. But Perseverance is still going strong. It still has 15 sample tubes at its disposal to capture additional interesting geologic specimens.

Next the rover will make its way out of Jezero Crater to explore the wider area. Czaja said they are likely to find rocks dating back 4 billion years or more. And Mars could harbor stromatolites or rocks that contain evidence of ancient layered mats of bacteria visible to the naked eye. On Earth, these rocks are sometimes found in extreme environments such as geyser basins.

Read more at Science Daily

New study is first step in predicting carbon emissions in agriculture

For the first time, researchers at the University of Minnesota Twin Cities (UMN) and the University of Illinois Urbana-Champaign (UIUC) have demonstrated that it is possible to provide accurate, high-resolution predictions of carbon cycles in agroecosystems, which could help mitigate the impacts of climate change.

The study by scholars from the UMN-led National Artificial Intelligence Institute for Climate-Land Interactions, Mitigation, Adaptation, Tradeoffs and Economy (AI-CLIMATE) and UIUC-led Agroecosystem Sustainability Center was recently published in Nature Communications, a peer-reviewed, open access, scientific journal.

The study's findings are a critical first step in developing a credible Measurement, Monitoring, Reporting, and Verification (MMRV) of agricultural emissions that can be used to incentivize the implementation of climate smart practices while boosting rural economies. This follows the national strategy, set by the White House, highlighting the need to quantify greenhouse gas emission across sectors with a goal of net-zero emissions by no later than 2050.

Accurate, scalable, and cost-effective monitoring and reporting of greenhouse gas emissions are needed to verify what are called "carbon credits" or permits that offset greenhouse gas emissions. Farmers can be reimbursed for practices that reduce greenhouse gas emissions. Agriculture accounts for about 25 percent of greenhouse gas emissions, but large corporations can be hesitant about purchasing these credits without knowing how much carbon is being stored.

Right now, to accurately gather carbon data, a farmer would need to hire someone to come to their farm, take what is called a soil core (vertical profile of the soil), and send that back to the lab for analysis.

"To gather the amount of data needed at each individual farm, it could cost the farmers time and money that they may not be willing to give," said Licheng Liu, the lead author and a research scientist in the University of Minnesota Department of Bioproducts and Biosystems Engineering.

The emerging field of Knowledge-Guided Machine Learning (KGML), pioneered by researchers at the University of Minnesota, combines the strength of artificial intelligence (AI) and process-based models from physical sciences. With observations in the United States Corn Belt, the KGML-ag framework significantly surpasses both process-based and pure machine learning models in accuracy, especially with limited data. Remarkably, KGML-ag operates over 10,000 times faster than traditional process-based models, delivering high-resolution and high-frequency predictions cost-effectively.

"These knowledge-guided machine learning (KGML) techniques are fundamentally more powerful than standard machine learning approaches and traditional models used by the scientific community to address environmental problems," said Vipin Kumar, a University of Minnesota Regents Professor and William Norris Endowed Chair in the Department of Computer Science and Engineering and a researcher in the AI-CLIMATE Institute, whose group has pioneered the development of the KGML framework.

Instead of taking soil cores at every farm, with KGML-ag, researchers can use the power of satellite remote sensing, computational models, and AI to provide an estimate of carbon in each individual field. This allows for compensation to individual farmers that are fair and accurate. The researchers say this is key to fostering trust in carbon markets and supporting the adoption of sustainable practices.

"KGML-ag combines the most advanced understanding of mechanisms in agriculture with the state-of-the-art AI techniques and thus offers a new powerful lens to monitor and manage our agricultural ecosystems," said Zhenong Jin, the corresponding author for this study and assistant professor in the University of Minnesota Department of Bioproducts and Biosystems Engineering, who co-leads the KGML special interest group in the AI-CLIMATE.

Now, AI-CLIMATE researchers are investigating the potential of the KGML framework for forestry, leveraging its capabilities to address the pressing challenges in sustainable forestry management and the capturing and storing of carbon. The team is also exploring a KGML-based data assimilation approach to make use of the rapidly growing different kinds of satellite data flexibly.

"The KGML is one of the key research topics of the AI-CLIMATE," said Shashi Shekhar, a University of Minnesota ADC Chair and Distinguished McKnight University Professor in the Department of Computer Science and Engineering and the lead researcher of the AI-CLIMATE Institute. "These initial results demonstrate the immense potential of AI for developing more accurate and cheaper methods for estimating emissions from agriculture. This may lubricate carbon markets and incentivize adoption of climate-smart practices."

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High resolution techniques reveal clues in 3.5 billion-year-old biomass

To learn about the first organisms on our planet, researchers have to analyse the rocks of the early Earth. These can only be found in a few places on the surface of the Earth. The Pilbara Craton in Western Australia is one of these rare sites: there are rocks there that are around 3.5 billion years old containing traces of the microorganisms that lived at that time. A research team led by the University of Göttingen has now found new clues about the formation and composition of this ancient biomass, providing insights into the earliest ecosystems on Earth. The results were published in the journal Precambrian Research.

Using high-resolution techniques such as nuclear magnetic resonance spectroscopy (NMR) and near-edge X-ray Absorption Fine Structure (NEXAFS), the researchers analysed carbonaceous particles found rocks made of barium sulphate.

This enabled scientists to obtain important information about the structure of microscopically small particles and show that they are of biological origin.

It is likely that the particles were deposited as sediment in the body of water of a "caldera" -- a large cauldron-shaped hollow that forms after volcanic activity.

In addition, some of the particles must have been transported and changed by hydrothermal waters just beneath the surface of the volcano.

This indicates a turbulent history of sediment deposits. By analysing various carbon isotopes, the researchers concluded that different types of microorganisms were already living in the vicinity of the volcanic activity, similar to those found today at Icelandic geysers or at hot springs in Yellowstone National Park.

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Significant glacial retreat in West Antarctica began in 1940s

Among the vast expanse of Antarctica lies the Thwaites Glacier, the world's widest glacier measuring about 80 miles on the western edge of the continent. Despite its size, the massive landform is losing about 50 billion tons of ice more than it is receiving in snowfall, which places it in a precarious position in respect to its stability.

Accelerating ice loss has been observed since the 1970s, but it is unclear when this significant melting initiated -- until now. A new study published in the journal PNAS, led by researchers at the University of Houston, suggests that significant glacial retreat began in the 1940s. Their results on the Thwaites Glacier coincide with previous work that studied retreat on Pine Island Glacier and found glacial retreat began in the '40s as well.

"What is especially important about our study is that this change is not random nor specific to one glacier," said Rachel Clark, corresponding author, who graduated from UH last year with a doctorate in geology. "It is part of a larger context of a changing climate. You just can't ignore what's happening on this glacier."

Clark and the study authors posit that the glacial retreat was likely kicked off by an extreme El Niño climate pattern that warmed the west Antarctic. Since then, the authors say, the glacier has not recovered and is currently contributing to 4% of global sea-level rise.

"It is significant that El Niño only lasted a couple of years, but the two glaciers, Thwaites and Pine Island, remain in significant retreat," said Julia Wellner, UH associate professor of geology and U.S. lead investigator of the Thwaites Offshore Research project, or THOR, an international collaboration whose team members are authors of the study.

"Once the system is kicked out of balance, the retreat is ongoing," she added.

Their findings also make it clear the retreat at the glaciers' grounding zone, or the area where the glaciers lose contact with the seabed and start to float, was due to external factors.

"The finding that both Thwaites Glacier and Pine Island Glacier share a common history of thinning and retreat corroborates the view that ice loss in the Amundsen Sea sector of the West Antarctic ice sheet is predominantly controlled by external factors, involving changes in ocean and atmosphere circulation, rather than internal glacier dynamics or local changes, such as melting at the glacier bed or snow accumulation on the glacier surface," said Claus-Dieter Hillenbrand, U.K. lead investigator of THOR and study co-author.

"A significant implication of our findings is that once an ice sheet retreat is set in motion, it can continue for decades, even if what started it gets no worse," added James Smith, a marine geologist at the British Antarctic Survey and study co-author. "It is possible that the changes we see today on Thwaites and Pine Island glaciers -- and potentially across the entire Amundsen Sea embayment -- were essentially set in motion in the 1940s."

Dating of Sediment Cores Plays Key Role in Study

Clark and the team used three primary methods to reach their conclusion. One of those methods was marine sediment core collection that was closer to the Thwaites Glacier than ever before. They retrieved the cores during their trip to the Amundsen Sea near Thwaites in early 2019 aboard the Nathaniel B. Palmer icebreaker and research vessel. The researchers then used the cores to reconstruct the glacier's history from the early Holocene epoch to the present. The Holocene is the current geological epoch that began after the last ice age, roughly 11,700 years ago.

CT scans were used to take x-rays of the sediment to gather details from its history. Geochronology, or the science of dating earth materials, was then used to reach the conclusion that significant ice melt began in the '40s.

Clark used 210Pb (lead-210), an isotope that's naturally buried in the sediment cores and is radioactive, as the most important isotope in her geochronology. This process is similar to radiocarbon dating, which measures the age of organic materials as far back as 60,000 years.

"But lead-210 has a short half-life of about 20 years, whereas something like radiocarbon has a half-life of about 5,000 years," Clark said. "That short half-life allows us to build a timeline for the past century that's detailed."

This methodology is important because although satellite data exists to help scientists understand glacial retreat, these observations only go as far back as a few decades, a time frame that is too short to determine how Thwaites responds to ocean and atmosphere changes. Pre-satellite records are needed for scientists to understand the glacier's longer-term history, which is why sediment cores are used.

Study Informs Future Modeling to Reduce Uncertainty of Sea-Level Rise

Thwaites Glacier plays a vital role in regulating the West Antarctic ice sheet stability and, thus, global sea-level rise, according to Antarctic researchers.

"The glacier is significant not only because of its contribution to sea-level rise but because it is acting as a cork in the bottle holding back a broader area of ice behind it," Wellner said. "If Thwaites is destabilized, then there's potential for all the ice in West Antarctica to become destabilized."

If Thwaites Glacier were to collapse entirely, global sea levels are predicted to rise by 65 cm (25 in).

"Our study helps to better understand what factors are most critical in driving thinning and retreat of glaciers draining the West Antarctic ice sheet into the Amundsen Sea," Hillenbrand said. "Therefore, our results will improve numerical models that attempt to predict the magnitude and rate of future Antarctic ice sheet melting and its contributions to sea levels."

Researchers with THOR are part of an even larger initiative, the International Thwaites Glacier Collaboration, a joint U.S.-U.K. partnership to reduce uncertainty in the projection of sea-level rise from Thwaites Glacier.

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Metal scar found on cannibal star

When a star like our Sun reaches the end of its life, it can ingest the surrounding planets and asteroids that were born with it. Now, using the European Southern Observatory's Very Large Telescope (ESO's VLT) in Chile, researchers have found a unique signature of this process for the first time -- a scar imprinted on the surface of a white dwarf star. The results are published today in The Astrophysical Journal Letters.

"It is well known that some white dwarfs -- slowly cooling embers of stars like our Sun -- are cannibalising pieces of their planetary systems. Now we have discovered that the star's magnetic field plays a key role in this process, resulting in a scar on the white dwarf's surface," says Stefano Bagnulo, an astronomer at Armagh Observatory and Planetarium in Northern Ireland, UK, and lead author of the study.

The scar the team observed is a concentration of metals imprinted on the surface of the white dwarf WD 0816-310, the Earth-sized remnant of a star similar to, but somewhat larger than, our Sun.

"We have demonstrated that these metals originate from a planetary fragment as large as or possibly larger than Vesta, which is about 500 kilometres across and the second-largest asteroid in the Solar System," says Jay Farihi, a professor at University College London, UK, and co-author on the study.

The observations also provided clues to how the star got its metal scar.

The team noticed that the strength of the metal detection changed as the star rotated, suggesting that the metals are concentrated on a specific area on the white dwarf's surface, rather than smoothly spread across it. They also found that these changes were synchronised with changes in the white dwarf's magnetic field, indicating that this metal scar is located on one of its magnetic poles.

Put together, these clues indicate that the magnetic field funneled metals onto the star, creating the scar.*

"Surprisingly, the material was not evenly mixed over the surface of the star, as predicted by theory. Instead, this scar is a concentrated patch of planetary material, held in place by the same magnetic field that has guided the infalling fragments," says co-author John Landstreet, a professor at Western University, Canada, who is also affiliated with the Armagh Observatory and Planetarium.

"Nothing like this has been seen before."

To reach these conclusions, the team used a 'Swiss-army knife' instrument on the VLT called FORS2, which allowed them to detect the metal scar and connect it to the star's magnetic field.

"ESO has the unique combination of capabilities needed to observe faint objects such as white dwarfs, and sensitively measure stellar magnetic fields," says Bagnulo.

In their study, the team also relied on archival data from the VLT's X-shooter instrument to confirm their findings.

Harnessing the power of observations like these, astronomers can reveal the bulk composition of exoplanets, planets orbiting other stars outside the Solar System.

This unique study also shows how planetary systems can remain dynamically active, even after 'death'.

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Utah's Bonneville Salt Flats has long been in flux

It has been long assumed that Utah's Bonneville Salt Flats was formed as its ancient namesake lake dried up 13,000 years ago. But new research from the University of Utah has gutted that narrative, determining these crusts did not form until several thousand years after Lake Bonneville disappeared, which could have important implications for managing this feature that has been shrinking for decades to the dismay of the racing community and others who revere the saline pan 100 miles west of Salt Lake City.

This salt playa, spreading across 40 square miles of the Great Basin Desert, perfectly level and white, has served as a stage for land-speed records and a backdrop for memorable scenes in numerous films, including "Buckaroo Banzai" and "Pirates of the Caribbean."

Relying on radiocarbon analysis of pollen found in salt cores, the study, published Friday in the journal Quaternary Research, concludes the salt began accumulating between 5,400 and 3,500 years ago, demonstrating how this geological feature is not a permanent fixture on the landscape.

"This now gives us a record of how the Bonneville Salt Flats landscape responds to environmental change. Originally, we thought this salt had formed here right after Lake Bonneville and it was a static landscape in the past 10,000 years," said the study's lead author, Jeremiah Bernau, a former U graduate student in geology. "This data shows us that that's not the case, that during a very dry period in the past 10,000 years, we actually saw a lot of erosion and then the accumulation of gypsum sand. And as the climate was becoming cooler and wetter, then the salt began to accumulate."

And even more intriguing, according to the researchers, is the sediments immediately under the salt are far older, predating even the existence of Lake Bonneville. In other words, the old lake bed had largely blown away, indicating this landscape is far more dynamic than previously understood.

"We can show that a lot of material was removed before the salt came in," said senior author Brenda Bowen, a geology professor and chair of the Department of Atmospheric Sciences who heads the U's Global Change and Sustainability Center. "That's really interesting when we think about what's happening right now with the Great Salt Lake's exposed lake beds and the potential for dust to be blown away and eroded."

The nearby Great Salt Lake, a surviving remnant of Lake Bonneville, has greatly receded over the past two decades thanks to drought and decades of upstream water diversions. The research offers a potential forecast of what might happen if the Great Salt Lake continues to shrink.

Since 1960, scientists have been monitoring the Bonneville Salt Flats, as a part of lease agreements and management plans overseen by the federal Bureau of Land Management. The playa lost about a third of its salt volume over the past six decades.

Today, the crusts are 5 feet at their thickest point and cover an area of 5 by 12 miles at the foot of the Silver Island Mountains. Bowen began measuring the salt in 2016 with a research team that included Bernau, who joined the Utah Geological Survey after completing his doctorate.

But they went deeper than others had previously, drilling into the sediments below the salt, which is difficult to core through.

"The salt is quite brittle," Bowen said. "You can't use fluids or water generally [to aid in drilling] because it would dissolve the sediments."

Instead, they used sonic drilling, which uses vibration.

"Once you get to the mud below the salt," she said, "it's like toothpaste and it just slides right through."

Bowen and Bernau collaborated with the U geography department's Records of Environmental Disturbance (or RED) Lab to drill additional cores in 2018 and 2020, this time using a device called a "vibracorer," built by Isaac Hart, a former construction worker and welder who was then a graduate student in anthropology.

The equipment consists of a 21-foot-long irrigation tube affixed to a concrete mixer motor.

"The vibration of the motor allows the tube to be pushed down into the ground if the sediment is relatively fine-grained and soft (like the floor of the Lake Bonneville basin), after which we fill the tube with water and cap it off to create a vacuum so the dirt doesn't drop out of the tube when we pull it out of the ground," said Hart, a coauthor in the study, said in an email. He is now a field director for the international nonprofit American Center for Mongolian Studies.

Added Bernau: "This method was manually laborious, but we pulled out really gorgeous cores."

They shared these cores, varying in length from 10 to 13 feet, with Charles "Jack" Oviatt, a coauthor in the study, emeritus professor of geology at Kansas State University and a leading expert in Pleistocene lake beds, especially Lake Bonneville's. After examining the sediments, Oviatt concluded they bore little resemblance to the Bonneville lake bed elsewhere.

"That really gave us the hint that we had something interesting on our hands," recalled Bernau, who now works for private industry in Texas. To make sense of the cores, the researchers had to first pinpoint the ages of the salt crusts and their underlying sediments.

Scientists can determine. Applying this technique to the sediments, the researchers found dates going back more than 40,000 years, older even than Lake Bonneville itself, suggesting the prior presence of intermittent lakes.

Dating the overlying salt crusts was more tricky since radiocarbon dating requires organic material to analyze. In examining the salt cores under a microscope, however, researchers found what they needed to carbon date the salt: minute grains of pollen.

The team also examined sediment structures, mineralogy, diatoms and geochemistry to characterize the depositional record. Gypsum and carbonate strontium isotope ratio measurements were used to determine sources of water that carried the sediments to the salt flats.

"We threw all our tools into this study to get as much of a robust understanding of how this environment was changing through time," said Bowen, whose study constructs a revisionist history for this place.

Lakes have been coming and going for tens of thousands, if not hundreds of thousands, of years in response to climatic changes, disappearing and reappearing as conditions alternate between wet and dry periods.

The data indicate the area now supporting the salt flats hosted a series of three shallow lakes between 45,000 to 28,000 years ago, that is, prior to the arrival of Lake Bonneville. After 13,000 years ago, the lake bed was exposed to wind erosion.

Three to six feet of sediment blew away before the water returned around 8,300 years ago, bringing the brines that eventually formed the salt flats we see today. The study shows that the Bonneville Salt Flats are more ephemeral than many appreciate, offering insights into how this special place could be managed differently.

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New cloud model could help with climate research

When clouds meet clear skies, cloud droplets evaporate as they mix with dry air. A new study involving researchers from the University of Gothenburg has succeeded in capturing what happens in a model. Ultimately, this could lead to more accurate climate modeling in the future.

The clouds in the sky have a significant impact on our climate.

Not only do they produce precipitation and provide shade from the sun, they also act as large reflectors that prevent the radiation of heat from the Earth -- commonly known as the greenhouse effect.

"Although clouds have been studied for a long time, they are one of the biggest sources of uncertainty in climate models," explains Bernhard Mehlig, Professor of Complex Systems at the University of Gothenburg.

"This is because there are so many factors that determine how the clouds affect radiation. And the turbulence in the atmosphere means that everything is in constant motion. This makes things even more complicated."

Focusing on the cloud edge

A scientific article in Physical Review Letters presents a new statistical model that describes how the number of water droplets, their sizes and the water vapour interact at the turbulent cloud edge.

The distribution of water droplets is important because it affects how clouds reflect radiation.

"The model describes how the droplets shrink and grow at the cloud edge when turbulence mixes in drier air," adds Johan Fries, a former doctoral student in physics and co-author of the study.

The researchers have identified the most important parameters, and have built their model accordingly.

In brief, the model takes into account the laws of thermodynamics and the turbulent motion of the droplets.

The model corresponds well with earlier numerical computer simulations, and explains their results.

The importance of evaporation

"But we're still a long way from the finish line," continues Professor Mehlig.

"Our model is currently able to describe what is happening in one cubic metre of cloud. Say, fifteen years ago it was only one cubic centimetre, so we're making progress."

When policymakers discuss climate change, great importance is attached to IPCC climate models.

However, according to the IPCC, the microphysical properties of clouds are among the least understood factors in climate science.

"Moreover, the evaporation of droplets is an important process, not only in the context of atmospheric clouds, but also within the field of infectious medicine. Tiny droplets that are produced when we sneeze can contain virus particles. If these droplets evaporate, the virus particles can remain in the air and infect others."

Professor Mehlig has also co-authored another study that describes how solid particles, such as ice crystals, move within clouds.

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Biggest Holocene volcano eruption found by seabed survey

A detailed survey of the volcanic underwater deposits around the Kikai caldera in Japan clarified the deposition mechanisms as well as the event's magnitude. As a result, the Kobe University research team found that the event 7,300 years ago was the largest volcanic eruption in the Holocene by far.

In addition to lava, volcanos eject large amounts of pumice, ashes and gases as a fast-moving flow, known as "pyroclastic flow," and its sediments are a valuable data source on past eruptions.

For volcanoes on land, geologists understand the sedimentation mechanism of pyroclastic flows well, but the sediments themselves get lost easily due to erosion.

On the other hand, for volcanoes on oceanic islands or near the coast, the pyroclastic flow deposition process is largely unclear, both because the interaction with water is less well understood and because reliable data is difficult to obtain and therefore sparse.

For these reasons, it is difficult to estimate the impact of many past eruptions on the climate and on history.

A Kobe University research team around SEAMA Nobukazu and SHIMIZU Satoshi took to the seas on the Kobe University-owned training vessel Fukae Maru (since replaced by the newly built Kaijin Maru) and conducted seismic imaging as well as sediment sampling around the Kikai caldera, off the south coast of Japan's Ky?sh?

island. The outstanding detail of the seismic reflection data revealed the sedimentary structure with a vertical resolution of 3 meters and down to a depth of several hundred meters below the seafloor.

Shimizu explains: "Due to the fact that volcanic ejecta deposited in the sea preserve well, they record a lot of information at the time of eruption. By using seismic reflection surveys optimized for this target and by identifying the collected sediments, we were able to obtain important information on the distribution, volume, and transport mechanisms of the ejecta."

In their article published in the Journal of Volcanology and Geothermal Research, the geoscientists report that an eruption that happened 7,300 years ago ejected a large amount of volcanic products (ash, pumice, etc.) that settled in an area measuring more than 4,500 square kilometers around the eruption site.

With a dense-rock equivalent volume of between 133 and 183 cubic kilometers, the event was the largest volcanic eruption to have taken place within the Holocene (the most recent 11,700 years of Earth's history following the end of the last ice age) known to science.

In the process of their analysis, the research team confirmed that the sedimentations on the ocean floor and those deposited on nearby islands have the same origin and from their distribution around the eruption site they could clarify the interaction between the pyroclastic flow and water.

They noticed that the underwater portion of the flow could travel vast distances even uphill.

Their findings yield new insights into the elusive dynamics of volcanic mega events that may prove useful in identifying the remains of other events as well as in estimating their size.

Seama explains, "Large volcanic eruptions such as those yet to be experienced by modern civilization rely on sedimentary records, but it has been difficult to estimate eruptive volumes with high precision because many of the volcanic ejecta deposited on land have been lost due to erosion. But giant caldera eruptions are an important phenomenon in geoscience, and because we also know that they influenced the global climate and thus human history in the past, understanding this phenomenon has also social significance." In this light, it is fascinating to think that the event that created a caldera about the size of a modern capital city was in fact the largest volcanic event since humans have spread all over the globe.

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Webb finds evidence for neutron star at heart of young supernova remnant

NASA's James Webb Space Telescope has found the best evidence yet for emission from a neutron star at the site of a recently observed supernova. The supernova, known as SN 1987A, was a core-collapse supernova, meaning the compacted remains at its core formed either a neutron star or a black hole. Evidence for such a compact object has long been sought, and while indirect evidence for the presence of a neutron star has previously been found, this is the first time that the effects of high-energy emission from the probable young neutron star have been detected.

Supernovae -- the explosive final death throes of some massive stars -- blast out within hours, and the brightness of the explosion peaks within a few months.

The remains of the exploding star will continue to evolve at a rapid rate over the following decades, offering a rare opportunity for astronomers to study a key astronomical process in real time.

Supernova 1987A

The supernova SN 1987A occurred 160,000 light-years from Earth in the Large Magellanic Cloud.

It was first observed on Earth in February 1987, and its brightness peaked in May of that year.

It was the first supernova that could be seen with the naked eye since Kepler's Supernova was observed in 1604.

About two hours prior to the first visible-light observation of SN 1987A, three observatories around the world detected a burst of neutrinos lasting only a few seconds.

The two different types of observations were linked to the same supernova event, and provided important evidence to inform the theory of how core-collapse supernovae take place.

This theory included the expectation that this type of supernova would form a neutron star or a black hole.

Astronomers have searched for evidence for one or the other of these compact objects at the center of the expanding remnant material ever since.

Indirect evidence for the presence of a neutron star at the center of the remnant has been found in the past few years, and observations of much older supernova remnants -such as the Crab Nebula -- confirm that neutron stars are found in many supernova remnants.

However, no direct evidence of a neutron star in the aftermath of SN 1987A (or any other such recent supernova explosion) had been observed, until now.

Claes Fransson of Stockholm University, and the lead author on this study, explained: "From theoretical models of SN 1987A, the 10-second burst of neutrinos observed just before the supernova implied that a neutron star or black hole was formed in the explosion. But we have not observed any compelling signature of such a newborn object from any supernova explosion. With this observatory, we have now found direct evidence for emission triggered by the newborn compact object, most likely a neutron star."

Webb's Observations of SN 1987A

Webb began science observations in July 2022, and the Webb observations behind this work were taken on July 16, making the SN 1987A remnant one of the first objects observed by Webb.

The team used the Medium Resolution Spectrograph (MRS) mode of Webb's MIRI (Mid-Infrared Instrument), which members of the same team helped to develop.

The MRS is a type of instrument known as an Integral Field Unit (IFU).

IFUs are able to image an object and take a spectrum of it at the same time.

An IFU forms a spectrum at each pixel, allowing observers to see spectroscopic differences across the object.

Analysis of the Doppler shift of each spectrum also permits the evaluation of the velocity at each position.

Spectral analysis of the results showed a strong signal due to ionized argon from the center of the ejected material that surrounds the original site of SN 1987A.

Subsequent observations using Webb's NIRSpec (Near-Infrared Spectrograph) IFU at shorter wavelengths found even more heavily ionized chemical elements, particularly five times ionized argon (meaning argon atoms that have lost five of their 18 electrons). Such ions require highly energetic photons to form, and those photons have to come from somewhere.

"To create these ions that we observed in the ejecta, it was clear that there had to be a source of high-energy radiation in the center of the SN 1987A remnant," Fransson said.

"In the paper we discuss different possibilities, finding that only a few scenarios are likely, and all of these involve a newly born neutron star."

More observations are planned this year, with Webb and ground-based telescopes.

The research team hopes ongoing study will provide more clarity about exactly what is happening in the heart of the SN 1987A remnant.

Read more at Science Daily

Cloud clustering causes more extreme rain

Understanding cloud patterns in our changing climate is essential to making accurate predictions about their impact on society and nature. Scientists at the Institute of Science and Technology Austria (ISTA) and the Max-Planck-Institute for Meteorology published a new study in the journal Science Advances that uses a high-resolution global climate model to understand how the clustering of clouds and storms impacts rainfall extremes in the tropics. They show that with rising temperatures, the severity of extreme precipitation events increases.

Extreme rainfall is one of the most damaging natural disasters costing human lives and causing billions in damage.

Their frequency has been increasing over the last years due to the warming climate.

For several decades, scientists have been using computer models of the Earth's climate to better understand the mechanisms behind these events and to predict future trends.

In a new study, now published in the journal Science Advances, a team of researchers from the Institute of Science and Technology Austria (ISTA) and the Max-Planck-Institute for Meteorology (MPI-M) led by ISTA postdoc Jiawei Bao used a new state-of-the-art climate model to study how cloud and storm clustering impacts extreme rainfall events -- specifically in the tropics -- in more detail than has been possible before.

"This new type of model with a much finer resolution showed that, with a warmer climate, extreme rainfall events in the tropics increase in severity more than was expected from theory due to clouds being more clustered," Bao, who originally started this project during his previous postdoc position at the MPI-M, explains.

"We can see that when clouds are more clustered, it rains for a longer time, so the total amount of rainfall increases. We also found that more extreme rain over high-precipitation areas happens at the cost of expansion of dry areas -- a further shift to extreme weather patterns. This is due to how clouds and storms cluster together, which we could now simulate with this new climate model." This new model, first proposed in 2019, simulates the climate with a much higher resolution than previous ones.

Previous models could not factor in clouds and storms in as much detail, therefore missing much of the complex dynamics of air movement that create clouds and make them congregate to form more intense storms.

While the model simulates the whole world at once, the scientists focused their analysis on the area of the tropics around the equator.

They did this because cloud and storm formation there works differently than in other latitudes.

Caroline Muller, Assistant Professor at ISTA, adds, "Previous models have hinted at the influence of clouds clustering on precipitation extremes but could not provide the necessary data. In collaboration with our colleagues Bjorn Stevens and Lukas Kluft from the Max Planck Institute for Meteorology, our findings add to the growing body of evidence showing that cloud formation on a smaller scale has a crucial impact on the outcomes of climate change."

Collaborative Models

Researchers all over the world are collaborating on creating more detailed and realistic models of the world's climate to understand the effects of climate change.

Climate models divide the Earth's atmosphere into three-dimensional chunks, each with its own data about temperature, pressure, humidity, and many more physical properties.

They then employ physical equations to simulate how these chunks interact and change over time to create a representation of the real world.

As computing power and storage are not unlimited, these models have to introduce simplifications and scientist continuously work to making them more accurate.

Older generations of climate models use chunks of around 100 kilometers in horizontal length, which still result in tens to hundreds of thousands of them covering the whole globe.

Advances in algorithms and supercomputers enabled scientists to increase the resolution of the models more and more.

"We used a climate model developed at MPI-M and analyzed the data hosted at the German Climate Computing Centre in Hamburg with a resolution of just five kilometers which was very computationally expensive," Bao adds.

"All climate research is an immense collaborative effort by hundreds of people who want to contribute to our understanding of the world and our impact on it."

Bao, who first got interested in climate research during his PhD at the University of New South Wales, Australia, and who now works as an IST-BRIDGE postdoctoral fellow at ISTA, wants to continue his work on extreme precipitation events to find more evidence for their causes and impacts using additional models.

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Killer instinct drove evolution of mammals' predatory ancestors

The evolutionary success of the first large predators on land was driven by their need to improve as killers, researchers at the University of Bristol and the Open University suggest.

The forerunners of mammals ruled the Earth for about 60 million years, long before the origin of the first dinosaurs.

They diversified as the top predators on land between 315-251 million years ago.

Researchers studied the jaw anatomy and body size of carnivorous synapsids, using these traits to reconstruct the likely feeding habits of these ancient predators and chart their ecological evolution through time.

They found a major shift in synapsid jaw function roughly 270 million years ago linked to a significant shift in predatory behaviour that has important implications for the evolution of our earliest ancestors.

As herbivores grew larger and faster, carnivores adapted to become bigger and better predators to survive.

"Earlier synapsid predators such as the famous sail backed Dimetrodon, had fairly long jaws with lots of teeth to ensure that once they ensnared their prey, it wouldn't escape," explained lead author Dr Suresh Singh based in Bristol's School of Earth Sciences.

"The change shows that later synapsid carnivores placed more emphasis on heavily injuring and so more quickly killing their prey. Among these later synapsids were the very first sabertoothed carnivores! This change highlights that predators were facing new selective pressures from their prey."

This finding provides important context for a key step in synapsid evolution.

"The reorganisation of synapsid jaws through this time has long been known as a big step towards the evolution of mammals," added Dr Armin Elsler, a collaborator on the study.

"These changes don't just make the jaw more efficient; they also mark the very earliest redevelopment of the jaw that also created the complex ear found in mammals. What drove this first step? Our study suggests that it was partly driven by ecological pressures from their prey."

Co-author Dr Tom Stubbs said: "The timing of the shift in jaw function corresponds with the evolution of new larger, faster herbivores that would have posed a greater challenge for predators to tackle.

"The risks to carnivores of getting injured or killed went up, so some synapsid carnivores became bigger, better killers to overcome these risks."

This shift reflects a new dynamism in predator-prey interactions that shows that life on land was moving more quickly.

"The late Palaeozoic was the time when animals first began to live, eat and reproduce entirely on land," said Professor Mike Benton, a co-supervisor on the study

"They became fully terrestrial, colonising new habitats and exploiting new resources further inland from the aquatic environments they'd previously relied on.

"Our findings show how the selective pressures on these early land animals changed as they became better adapted for life on land -- catching another animal that can move fast and grow to larger sizes is much more difficult than catching a slippery little fish or amphibian."

Professor Emily Rayfield also co-supervised the study.

"It highlights how palaeontologists can use the relationship between form and function to explore how different prehistoric animals may have lived, which can tell us so much about the evolution of life on Earth."

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Drug limits dangerous reactions to allergy-triggering foods, Stanford Medicine-led study of kids finds

A drug can make life safer for children with food allergies by preventing dangerous allergic responses to small quantities of allergy-triggering foods, according to a new study led by scientists at the Stanford School of Medicine.

The research will be published Feb. 25 in the New England Journal of Medicine. The findings suggest that regular use of the drug, omalizumab, could protect people from severe allergic responses, such as difficulty breathing, if they accidentally eat a small amount of a food they are allergic to.

"I'm excited that we have a promising new treatment for multifood allergic patients. This new approach showed really great responses for many of the foods that trigger their allergies," said the study's senior author, Sharon Chinthrajah, MD, associate professor of medicine and of pediatrics, and the acting director of the Sean N. Parker Center for Allergy and Asthma Research at Stanford Medicine.

"Patients impacted by food allergies face a daily threat of life-threatening reactions due to accidental exposures," said the study's lead author, Robert Wood, MD, professor of pediatrics at Johns Hopkins University School of Medicine. "The study showed that omalizumab can be a layer of protection against small, accidental exposures."

Omalizumab, which the Food and Drug Administration originally approved to treat diseases such as allergic asthma and chronic hives, binds to and inactivates the antibodies that cause many kinds of allergic disease. Based on the data collected in the new study, the FDA approved omalizumab for reducing risk of allergic reactions to foods on Feb. 16.

All study participants were severely allergic to peanuts and at least two other foods. After four months of monthly or bimonthly omalizumab injections, two-thirds of the 118 participants receiving the drug safely ate small amounts of their allergy-triggering foods. Notably, 38.4% of the study participants were younger than 6 years, an age group at high risk from accidental ingestions of allergy-triggering foods.

Allergies are common

Food allergies affect about 8% of children and 10% of adults in the United States. People with severe allergies are advised to fully avoid foods containing their allergy triggers, but common allergens such as peanuts, milk, eggs and wheat can be hidden in so many places that everyday activities such as attending parties and eating in restaurants can be challenging.

"Food allergies have significant social and psychological impacts, including the threat of allergic reactions upon accidental exposures, some of which can be life-threatening," Chinthrajah said. Families also face economic impacts from purchasing more expensive foods to avoid allergens, she added.

In the best available treatment for food allergies, called oral immunotherapy, patients ingest tiny, gradually increasing doses of allergy-triggering foods under a doctor's supervision to build tolerance. But oral immunotherapy itself can trigger allergic responses, desensitization to allergens can take months or years, and the process is especially lengthy for people with several food allergies, as they are usually treated for one allergy at a time. Once they are desensitized to an allergen, patients also must continue to eat the food regularly to maintain their tolerance to it -- but people often dislike foods they were long required to avoid.

"There is a real need for treatment that goes beyond vigilance and offers choices for our food allergic patients," Chinthrajah said.

Omalizumab is an injected antibody that binds and deactivates all types of immunoglobin E, or IgE, the allergy-causing molecule in the blood and on the body's immune cells. So far, omalizumab appears able to provide relief from multiple food allergens at once.

"We think it should have the same impact regardless of what food it is," Chinthrajah said.

Injections stave off severe reactions

The study included 177 children with at least three food allergies each, of whom 38% were 1 to 5 years old, 37% were 6 to 11 years old, and 24% were 12 or older. Participants' severe food allergies were verified by skin-prick testing and food challenges; they reacted to less than 100 milligrams of peanut protein and less than 300 milligrams of each other food.

Two-thirds of the participants were randomly assigned to receive omalizumab injections, and one-third received an injected placebo; the injections took place over 16 weeks. Medication doses were set based on each participant's body weight and IgE levels, with injections given once every two or four weeks, depending on the dose needed. The participants were re-tested between weeks 16 and 20 to see how much of each allergy-triggering food they could safely tolerate.

Upon re-testing, 79 patients (66.9%) who had taken omalizumab could tolerate at least 600 mg of peanut protein, the amount in two or three peanuts, compared with only four patients (6.8%) who had the placebo. Similar proportions of patients showed improvement in their reactions to the other foods in the study.

About 80% of patients taking omalizumab were able to consume small amounts of at least one allergy-triggering food without inducing an allergenic reaction, 69% of patients could consume small amounts of two allergenic foods and 47% could eat small amounts of all three allergenic foods.

Omalizumab was safe and did not cause side effects, other than some instances of minor reactions at the site of injection. This study marks the first time its safety has been assessed in children as young as 1.

More questions

More research is needed to further understand how omalizumab could help people with food allergies, the researchers said.

"We have a lot of unanswered questions: How long do patients need to take this drug? Have we permanently changed the immune system? What factors predict which people will have the strongest response?" Chinthrajah said. "We don't know yet."

The team is planning studies to answer these questions and others, such as finding what type of monitoring would be needed to determine when a patient gains meaningful tolerance to an allergy-triggering food.

Many patients who have food allergies also experience other allergic conditions treated by omalizumab, Chinthrajah noted, such as asthma, allergic rhinitis (hay fever and allergies to environmental triggers such as mold, dogs or cats, or dust mites) or eczema. "One drug that could improve all of their allergic conditions is exactly what we're hoping for," she said.

The drug could be especially helpful for young children with severe food allergies, she added, because they tend to put things in their mouths and may not understand the dangers their allergies pose, she added.

The drug could also make it safer for community physicians to treat food allergy patients, since it cannot trigger dangerous allergic reactions, as oral immunotherapy sometimes does. "This is something that our food allergy community has been waiting a long time for," Chinthrajah said. "It's an easy drug regimen to implement in a medical practice, and many allergists are already using this for other allergic conditions."

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Little groundwater recharge in ancient Mars aquifer, according to new models

Mars was once a wet world. The geological record of the Red Planet shows evidence for water flowing on the surface -- from river deltas to valleys carved by massive flash floods.

But a new study shows that no matter how much rainfall fell on the surface of ancient Mars, very little of it seeped into an aquifer in the planet's southern highlands.

A graduate student at The University of Texas at Austin made the discovery by modeling groundwater recharge dynamics for the aquifer using a range of methods -- from computer models to simple back-of-the-envelope calculations.

No matter the degree of complexity, the results converged on the same answer -- a miniscule .03 millimeters of groundwater recharge per year on average.

That means that wherever rain fell in the model, only an average of .03 millimeters per year could have entered the aquifer and still produced the landforms remaining on the planet today.

For comparison, the annual rate of groundwater recharge for the Trinity and Edwards-Trinity Plateau aquifers that provide water to San Antonio generally ranges from 2.5 to 50 millimeters per year, or about 80 to 1,600 times the Martian aquifer recharge rate calculated by the researchers.

There are a variety of potential reasons for such low groundwater flow rates, said lead author Eric Hiatt, a doctoral student at the Jackson School of Geosciences.

When it rained, the water may have mostly washed across the Martian landscape as runoff.

Or it may have just not rained very much at all.

These findings can help scientists constrain the climatic conditions capable of producing rainfall on early Mars.

They also suggest a very different water regime on the Red Planet than what exists on Earth today.

"The fact that the groundwater isn't as big of a process could mean that other things are," Hiatt said.

"It might magnify the importance of runoff, or it could mean that it just didn't rain as much on Mars. But it's just fundamentally different from how we think about [water] on Earth."

The results were published in the journal Icarus. The paper's co-authors are Mohammad Afzal Shadab, a doctoral student at the Jackson School and faculty members Sean Gulick, Timothy Goudge and Marc Hesse.

The models used in the study work by simulating groundwater flow in a "steady state" environment where inflow and outflow of water into the aquifer is balanced.

Scientists then changed the parameters affecting the flow -- for example, where rain falls or the average porosity of the rock -- and observed what other variables would have to change to maintain the steady state and how plausible those charges are.

While other researchers have simulated groundwater flow on Mars using similar techniques, this model is the first to incorporate the influence of the oceans that existed on the surface of Mars more than three billion years ago in the Hellas, Argyre, and Borealis basins.

The study also incorporates modern topographical data collected by satellites.

The modern landscape, Hiatt said, still preserves one of the planet's oldest and most influential topographical features -- an extreme difference in elevation between the northern hemisphere -- the lowlands -- and the southern hemisphere -- the highlands -- known as the "great dichotomy." The dichotomy preserves signs of past groundwater upwelling in which groundwater rose up from the aquifer to the surface.

The researchers used geological markers of these past upwelling events to evaluate different model outputs.

Across different models, the researchers found the mean groundwater recharge rate of .03 millimeters per year to match most closely with what's known about the geologic record.

The research isn't just about understanding the Red Planet's past.

It has implications for future Mars exploration too. Understanding groundwater flow can help inform where to find water today, Hiatt said.

Whether you're looking for signs of ancient life, trying to sustain human explorers, or making rocket fuel to get back home to Earth, it's essential to know where the water would most likely be.

Read more at Science Daily

Air pollution hides increases in rainfall

We know that greenhouse gas emissions like carbon dioxide should increase rainfall. The emissions heat the atmosphere, causing a one-two punch: warmer oceans make it easier for water to evaporate, and warmer air can hold more water vapor, meaning more moisture is available to fall as rain. But for much of the 20th century, that increase in precipitation didn't clearly show up in the data.

A new study led by researchers at the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) finds that the expected increase in rain has been largely offset by the drying effect of aerosols -- emissions like sulfur dioxide that are produced by burning fossil fuels, and commonly thought of as air pollution or smog.

The research is published today in the journal Nature Communications.

"This is the first time that we can really understand what's causing extreme rainfall to change within the continental U.S.," said Mark Risser, a research scientist at Berkeley Lab and one of the lead authors for the study.

He noted that until the 1970s, the expected increases to extreme rainfall were offset by aerosols.

But the Clean Air Act caused a drastic reduction in air pollution in the United States.

"The aerosol masking was turned off quite suddenly. That means rainfall might ramp up much more quickly than we would have otherwise predicted."

Traditional climate models have struggled to confidently predict the human impact on rainfall at scales smaller than a continent -- and that regional level is precisely where most climate change adaptations and mitigations take place.

By using a new method and relying heavily on measurements from rain gauges from 1900 to 2020, researchers were able to more robustly determine how human activities have influenced rainfall in the United States.

"Prior to our study, the Intergovernmental Panel on Climate Change [IPCC] had concluded that the evidence was mixed and inconclusive for changes in U.S. precipitation due to global warming," said Bill Collins, associate laboratory director for the Earth and Environmental Sciences Area at Berkeley Lab and co-lead author on the study.

"We have now provided conclusive evidence for higher rainfall and also helped explain why past studies assessed by the IPCC reached conflicting conclusions."

Specifically, the study isolates how greenhouse gas and aerosol emissions affect both average and extreme rainfall.

Researchers confirmed that increased greenhouse gas emissions, which quickly disperse over the whole planet, cause an increase in rainfall.

The impact from aerosols is more nuanced. Over the long term, aerosols cool the planet, which causes a drying effect.

But they also have a faster, more local response. That fast impact depends on the season, with aerosols generally reducing rainfall in the winter and spring, and amplifying it in summer and fall over much of the United States.

"The seasonality piece is really important," Risser said. "For rainfall, the nature of climate change depends on what season you're talking about, since different kinds of weather systems create precipitation in different parts of the year."

Some of the conflicting studies looking at precipitation trends of the last century can be explained by how the effect of aerosols offsets the effect of greenhouse gases, and how models and simulations factor in these two driving forces.

The researchers noted that tracking aerosols and incorporating them more fully into models and simulations will be important for improving the predictions used for infrastructure design and water resource management.

The United States has already seen examples of recent increases in extreme precipitation, with several intense, record-setting storms in the past few years.

Read more at Science Daily