Researchers capture first-ever afterglow of huge planetary collision in outer space

The study, published today in Nature, reports the sighting of two ice giant exoplanets colliding around a sun-like star, creating a blaze of light and plumes of dust. Its findings show the bright heat afterglow and resulting dust cloud, which moved in front of the parent star dimming it over time.

The international team of astronomers was formed after an enthusiast viewed the light curve of the star and noticed something strange. It showed the system doubled in brightness at infrared wavelengths some three years before the star started to fade in visible light.

Co-lead author Dr Matthew Kenworthy, from Leiden University, said: "To be honest, this observation was a complete surprise to me. When we originally shared the visible light curve of this star with other astronomers, we started watching it with a network of other telescopes.

"An astronomer on social media pointed out that the star brightened up in the infrared over a thousand days before the optical fading. I knew then this was an unusual event."

The network of professional and amateur astronomers studied the star intensively including monitoring changes in the star's brightness over the next two years. The star was named ASASSN-21qj after the network of telescopes that first detected the fading of the star at visible wavelengths.

The researchers concluded the most likely explanation is that two ice giant exoplanets collided, producing the infrared glow detected by NASA's NEOWISE mission, which uses a space telescope to hunt for asteroids and comets.

Co-lead author Dr Simon Lock, Research Fellow in Earth Sciences at the University of Bristol, said: "Our calculations and computer models indicate the temperature and size of the glowing material, as well as the amount of time the glow has lasted, is consistent with the collision of two ice giant exoplanets."

The resultant expanding debris cloud from the impact then travelled in front of the star some three years later, causing the star to dim in brightness at visible wavelengths.

Over the next few years, the cloud of dust is expected to start smearing out along the orbit of the collision remnant, and a tell-tale scattering of light from this cloud could be detected with both ground-based telescopes and NASA's largest telescope in space, known as JWST.

The astronomers plan on watching closely what happens next in this system.

Read more at Science Daily

Scientists unveil detailed cell maps of the human brain and the nonhuman primate brain

A group of international scientists have mapped the genetic, cellular, and structural makeup of the human brain and the nonhuman primate brain. This understanding of brain structure, achieved by funding through the National Institutes of Health's Brain Research Through Advancing Innovative Neurotechnologies® Initiative, or The BRAIN Initiative®, allows for a deeper knowledge of the cellular basis of brain function and dysfunction, helping pave the way for a new generation of precision therapeutics for people with mental disorders and other disorders of the brain. The findings appear in a compendium of 24 papers across Science, Science Advances, and Science Translational Medicine.

"Mapping the brain's cellular landscape is a critical step toward understanding how this vital organ works in health and disease," said Joshua A. Gordon, M.D., Ph.D., director of the National Institute of Mental Health. "These new detailed cell atlases of the human brain and the nonhuman primate brain offer a foundation for designing new therapies that can target the specific brain cells and circuits involved in brain disorders."

The 24 papers in this latest BRAIN Initiative Cell Census Network (BICCN) collection detail the exceptionally complex diversity of cells in the human brain and the nonhuman primate brain. The studies identify similarities and differences in how cells are organized and how genes are regulated in the human brain and the nonhuman primate brain. For example:

• Three papers in the collection present the first atlas of cells in the adult human brain, mapping the transcriptional and epigenomic landscape of the brain. The transcriptome is the complete set of gene readouts in a cell, which contains instructions for making proteins and other cellular products. The epigenome refers to chemical modifications to a cell's DNA and chromosomes that alter the way the cell's genetic information is expressed.
• In another paper, a comparison of the cellular and molecular properties of the human brain and several nonhuman primate brains (chimpanzee, gorilla, macaque, and marmoset brains) revealed clear similarities in the types, proportions, and spatial organization of cells in the cerebral cortex of humans and nonhuman primates. Examination of the genetic expression of cortical cells across species suggests that relatively small changes in gene expression in the human lineage led to changes in neuronal wiring and synaptic function that likely allowed for greater brain plasticity in humans, supporting the human brain's ability to adapt, learn, and change.
• A study exploring how cells vary in different brain regions in marmosets found a link between the properties of cells in the adult brain and the properties of those cells during development. The link suggests that developmental programming is embedded in cells when they are formed and maintained into adulthood and that some observable cellular properties in an adult may have their origins very early in life. This finding could lead to new insights into brain development and function across the lifespan.
• An exploration of the anatomy and physiology of neurons in the outermost layer of the neocortex -- part of the brain involved in higher-order functions such as cognition, motor commands, and language -- revealed differences in the human brain and the mouse brain that suggest this region may be an evolutionary hotspot, with changes in humans reflecting the higher demands of regulating humans' more complex brain circuits.

The core aim of the BICCN, a groundbreaking effort to understand the brain's cellular makeup, is to develop a comprehensive inventory of the cells in the brain -- where they are, how they develop, how they work together, and how they regulate their activity -- to better understand how brain disorders develop, progress, and are best treated.

"This suite of studies represents a landmark achievement in illuminating the complexity of the human brain at the cellular level," said John Ngai, Ph.D., director of the NIH BRAIN Initiative. "The scientific collaborations forged through BICCN are propelling the field forward at an exponential pace; the progress -- and possibilities -- have been simply breathtaking."

Read more at Science Daily

Neanderthal gene variants associated with greater pain sensitivity

People who carry three gene variants that have bene inherited from Neanderthals are more sensitive to some types of pain, according to a new study co-led by UCL researchers.

The findings, published in Communications Biology, are the latest findings to show how past interbreeding with Neanderthals has influenced the genetics of modern humans.

The researchers found that people carrying three so-called Neanderthal variants in the gene SCN9A, which is implicated in sensory neurons, are more sensitive to pain from skin pricking after prior exposure to mustard oil.

Previous research has identified three variations in the SCN9A gene -- known as M932L, V991L, and D1908G -- in sequenced Neanderthal genomes and reports of greater pain sensitivity among humans carrying all three variants. However, prior to this study the specific sensory responses affected by these variants was unclear.

An international team led by researchers at UCL, Aix-Marseille University, University of Toulouse, Open University, Fudan University, and Oxford University, and part-funded by Wellcome, measured the pain thresholds of 1,963 people from Colombia in response to a range of stimuli.

The SCN9A gene encodes a sodium channel that is expressed at high levels in sensory neurons that detect signals from damaged tissue. The researchers found that the D1908G variant of the gene was present in around 20% of chromosomes within this population and around 30% of chromosomes carrying this variant also carried the M932L and V991L variants.

The authors found that the three variants were associated with a lower pain threshold in response to skin pricking after prior exposure to mustard oil, but not in response to heat or pressure. Additionally, carrying all three variants was associated with greater pain sensitivity than carrying only one.

When they analysed the genomic region including SCN9A using genetic data from 5,971 people from Brazil, Chile, Colombia, Mexico and Peru, the authors found that the three Neanderthal variants were more common in populations with higher proportions of Native American ancestry, such as the Peruvian population, in which the average proportion of Native American ancestry was 66%.

The authors propose that the Neanderthal variants may sensitise sensory neurons by altering the threshold at which a nerve impulse is generated. They speculate that the variants may be more common in populations with higher proportions of Native American ancestry as a result of random chance and population bottlenecks that occurred during the initial occupation of the Americas. Although acute pain can moderate behaviour and prevent further injury, the scientists that say additional research is needed to determine whether carrying these variants and having greater pain sensitivity may have been advantageous during human evolution.

Previous research by co-corresponding author Dr Kaustubh Adhikari (UCL Genetics, Evolution & Environment and The Open University) has shown that humans also inherited some genetic material from Neanderthals affecting the shape of our noses.*

Dr Adhikari commented: "In the last 15 years, since the Neanderthal genome was first sequenced, we have been learning more and more about what we have inherited from them as a result of interbreeding tens of thousands of years ago.

"Pain sensitivity is an important survival trait that enables us to avoid painful things that could cause us serious harm. Our findings suggest that Neanderthals may have been more sensitive to certain types of pain, but further research is needed for us to understand why that is the case, and whether these specific genetic variants were evolutionarily advantageous."

Read more at Science Daily

Finding explanation for Milky Way's warp

The Milky Way is often depicted as a flat, spinning disk of dust, gas, and stars. But if you could zoom out and take an edge-on photo, it actually has a distinctive warp -- as if you tried to twist and bend a vinyl LP.

Though scientists have long known through observational data that the Milky Way is warped and its edges are flared like a skirt, no one could explain why.

Now, Harvard astronomers at the Center for Astrophysics | Harvard and Smithsonian (CfA) have performed the first calculations that fully explain this phenomenon, with compelling evidence pointing to the Milky Way's envelopment in an off-kilter halo of dark matter. The work also bolsters current thinking about how the galaxy evolved and may offer clues into some of the mysteries of dark matter.

The new calculations were led by Jiwon Jesse Han, a Griffin Graduate School of Arts and Sciences student affiliated with the CfA. Published in Nature Astronomy, the work includes co-authors Charlie Conroy and Lars Hernquist, both faculty members at the CfA and in the Department of Astronomy.

Our galaxy is located inside a diffuse cloud called the stellar halo, which extends much farther out into the universe. In groundbreaking work published last year, the Harvard team deduced that the stellar halo is tilted and elliptical in shape, like a zeppelin or football.

Building on that, the team assumed the same shape for the dark matter halo, the larger entity that encompasses everything in and around the Milky Way. Dark matter makes up 80 percent of the galaxy's mass but is invisible because it doesn't interact with light, so the shape of that halo must be inferred. Using models to calculate the orbits of stars within a tilted, oblong dark matter halo, the team found a near-perfect match to existing observations of a warped, flared galaxy.

"A tilted dark halo is actually fairly common in simulations, but no one had explored its effect on the Milky Way," Conroy said. "It turns out that the tilt is an elegant way to explain both the magnitude and direction of our galaxy's wobbly disk."

Scientists had long surmised that the Milky Way formed due to a galactic collision; the astronomers' work further underscores that hypothesis.

"If the galaxy was just evolving on its own, it would have had this nice, spherical halo, this nice, flat disk," Han said. "So the fact that the halo is tilted and has a football-like shape suggests that our galaxy experienced a merger event, where two galaxies collide."

Their calculation of the dark matter halo's probable shape may also provide clues as to the properties and particle nature of dark matter itself, which remain unsolved mysteries in physics. "The fact that the galaxy is not spherical in our data implies that there is some limit to which dark matter can interact with itself," Han explained.

Read more at Science Daily

Climate-driven extreme heat may make parts of Earth too hot for humans

If global temperatures increase by 1 degree Celsius (C) or more than current levels, each year billions of people will be exposed to heat and humidity so extreme they will be unable to naturally cool themselves, according to interdisciplinary research from the Penn State College of Health and Human Development, Purdue University College of Sciences and Purdue Institute for a Sustainable Future.

Results from a new article published today (Oct. 9) in Proceedings of the National Academy of Sciences indicated that warming of the planet beyond 1.5 C above preindustrial levels will be increasingly devastating for human health across the planet.

Humans can only withstand certain combinations of heat and humidity before their bodies begin to experience heat-related health problems, such as heat stroke or heart attack. As climate change pushes temperatures higher around the world, billions of people could be pushed beyond these limits.

Since the start of the industrial revolution, when humans began to burn fossil fuels in machines and factories, temperatures around the world have increased by about 1 C, or 1.8 degrees Fahrenheit (F). In 2015, 196 nations signed the Paris Agreement which aims to limit worldwide temperature increases to 1.5 C above pre-industrial levels.

The researcher team modeled global temperature increases ranging between 1.5 C and 4 C -- considered the worst-case scenario where warming would begin to accelerate -- to identify areas of the planet where warming would lead to heat and humidity levels that exceed human limits.

"To understand how complex, real-world problems like climate change will affect human health, you need expertise both about the planet and the human body," said co-author W. Larry Kenney, professor of physiology and kinesiology, the Marie Underhill Noll Chair in Human Performance at Penn State and co-author of the new study. "I am not a climate scientist, and my collaborators are not physiologists. Collaboration is the only way to understand the complex ways that the environment will affect people's lives and begin to develop solutions to the problems that we all must face together."

A threat to billions

The ambient wet-bulb temperature limit for young, healthy people is about 31 C, which is equal to 87.8 F at 100% humidity, according to work published last year by Penn State researchers. However, in addition to temperature and humidity, the specific threshold for any individual at a specific moment also depends on their exertion level and other environmental factors, including wind speed and solar radiation. In human history, temperatures and humidity that exceed human limits have been recorded only a limited number of times -- and only for a few hours at a time -- in the Middle East and Southeast Asia, according to the researchers.

Results of the study indicate that if global temperatures increase by 2 C above pre-industrial levels, the 2.2 billion residents of Pakistan and India's Indus River Valley, the one billion people living in eastern China and the 800 million residents of sub-Saharan Africa will annually experience many hours of heat that surpass human tolerance.

These regions would primarily experience high-humidity heatwaves. Heatwaves with higher humidity can be more dangerous because the air cannot absorb excess moisture, which limits sweat evaporates from human bodies and moisture from some infrastructure, like evaporative coolers. Troublingly, researchers said, these regions are also in lower-to-middle income nations, so many of the affected people may not have access to air conditioning or any effective way to mitigate the negative health effects of the heat.

If warming of the planet continues to 3 C above pre-industrial levels, the researchers concluded, heat and humidity levels that surpass human tolerance would begin to affect the Eastern Seaboard and the middle of the United States -- from Florida to New York and from Houston to Chicago. South America and Australia would also experience extreme heat at that level of warming.

At current levels of heating, the researchers said, the United States will experience more heatwaves, but these heatwaves are not predicted to surpass human limits as often as in other regions of the world. Still, the researchers cautioned that these types of models often do not account for the worst, most unusual weather events.

"Models like these are good at predicting trends, but they do not predict specific events like the 2021 heatwave in Oregon that killed more than 700 people or London reaching 40 C last summer," said lead author Daniel Vecellio, a bioclimatologist who completed a postdoctoral fellowship at Penn State with Kenney. "And remember, heat levels then were all below the limits of human tolerance that we identified. So, even though the United States will escape some of the worst direct effects of this warming, we will see deadly and unbearable heat more often. And -- if temperatures continue to rise -- we will live in a world where crops are failing and millions or billions of people are trying to migrate because their native regions are uninhabitable."

Understanding human limits and future warming

Over the last several years, Kenney and his collaborators have conducted 462 separate experiments to document the combined levels of heat, humidity and physical exertion that humans can tolerate before their bodies can no longer maintain a stable core temperature.

"As people get warmer, they sweat, and more blood is pumped to their skin so that they can maintain their core temperatures by losing heat to the environment," Kenney said. "At certain levels of heat and humidity, these adjustments are no longer sufficient, and body core temperature begins to rise. This is not an immediate threat, but it does require some form of relief. If people do not find a way to cool down within hours, it can lead to heat exhaustion, heat stroke and strain on the cardiovascular system that can lead to heart attacks in vulnerable people."

In 2022, Kenney, Vecellio and their collaborators demonstrated that the limits of heat and humidity people can withstand are lower than were previously theorized.

"The data collected by Kenney's team at Penn State provided much needed empirical evidence about the human body's ability to tolerate heat. Those studies were the foundation of these new predictions about where climate change will create conditions that humans cannot tolerate for long," said co-author Matthew Huber, professor of earth, atmospheric and planetary sciences at Purdue University.

When this work was published, Huber, who had already begun work on mapping the impacts of climate change, contacted Vecellio about a potential collaboration. Huber had previously published widely cited work proposing a theoretical limit of humans' heat and humidity limits.

The researchers, along with Huber's graduate student, Qinqin Kong, decided to explore how people would be affected in different regions of the world if the planet warmed by between 1.5 C and 4 C. The researchers said that 3 C is the best estimate of how much the planet will warm by 2100 if no action is taken.

"Around the world, official strategies for adapting to the weather focus on temperature only," Kong said. "But this research shows that humid heat is going to be a much bigger threat than dry heat. Governments and policymakers need to re-evaluate the effectiveness of heat-mitigation strategies to invest in programs that will address the greatest dangers people will face."

Staying safe in the heat

Regardless of how much the planet warms, the researchers said that people should always be concerned about extreme heat and humidity -- even when they remain below the identified human limits. In preliminary studies of older populations, Kenney found that older adults experience heat stress and the associated health consequences at lower heat and humidity levels than young people.

"Heat is already the weather phenomenon that kills the most people in the United States," Vecellio, now a postdoctoral researcher at George Mason University's Virginia Climate Center, said. "People should care for themselves and their neighbors -- especially the elderly and sick -- when heatwaves hit."

The data used in this study examined the body's core temperatures, but the researchers said that during heatwaves, people experience health problems from other causes as well. For example, Kenney said that most of the 739 people who died during Chicago's 1995 heatwave were over 65 and experienced a combination of high body temperature and cardiovascular problems, leading to heart attacks and other cardiovascular causes of death.

Looking to the future

To stop temperatures from increasing, the researchers cite decades of research indicating that humans must reduce the emission of greenhouse gases, especially the carbon dioxide emitted by burning fossil fuels. If changes are not made, middle-income and low-income countries will suffer the most, Vecellio said.

As one example, the researchers pointed to Al Hudaydah, Yemen, a port city of more than 700,000 people on the Red Sea. Results of the study indicated that if the planet warms by 4 C, this city can expect more than 300 days when temperatures exceed the limits of human tolerance every year, making it almost uninhabitable.

"The worst heat stress will occur in regions that are not wealthy and that are expected to experience rapid population growth in the coming decades," Huber said. "This is true despite the fact that these nations generate far fewer greenhouse gas emissions than wealthy nations. As a result, billions of poor people will suffer, and many could die. But wealthy nations will suffer from this heat as well, and in this interconnected world, everyone can expect to be negatively affected in some way."

Read more at Science Daily

Killing remains a threat to Bornean orangutans

University of Queensland research has found despite considerable conservation efforts, the illegal killing of critically endangered orangutans on Borneo may be an ongoing threat to the species.

PhD candidate Emily Massingham from UQ's Faculty of Science managed a team of researchers which visited 79 villages across the Bornean orangutan range in Kalimantan, conducting face to face interviews with 431 people.

"Our study builds on previous research which indicated killing was one of the key reasons for orangutan population decline, alongside habitat loss," Ms Massingham said.

"The aim of our project was to understand whether orangutans have been killed in recent times, to look at whether conservation projects are effectively preventing killing, and to gain insights into community perceptions and the motivations behind it.

"It has been almost 15 years since the previous study, and we did not find a clear decrease in killings despite Indonesia's commendable efforts to reduce habitat loss.

"Thirty per cent of villages reported orangutans had been killed in the last 5 -10 years, despite the practice being both illegal and taboo -- which also makes it hard to get an accurate picture of the true scale."

Ms Massingham said Borneo's orangutan population had decreased by 100,000 in recent decades, with current estimates suggesting fewer than 100,000 animals remain.

"Our findings did not indicate that conservation projects are reducing killing, highlighting an urgent need to improve the collective approach to orangutan conservation," she said.

"Killing by humans needs to be addressed, as our findings suggest it may still be occurring and poses a real threat to the species."

Ms Massingham said orangutans have long lifespans and breed slowly, so are particularly vulnerable to population declines driven by the death of adult apes.

"Our interviews revealed some of the situations which lead to the killing or displacement of individual orangutans," she said.

"They include protecting crops and taking infant apes to keep as pets."

The researchers outlined recommendations that could improve future conservation efforts.

"Working with communities and collaborating across disciplines and projects will be key," Ms Massingham said.

"Conservationists need to work closely with individual villages to understand their needs and perspectives, identify the social drivers of killing of orangutans and implement solutions that reduce human-orangutan conflict."

Read more at Science Daily

Evidence from the remains of 1918 flu pandemic victims contradicts long-held belief that healthy young adults were particularly vulnerable

New analysis of the remains of victims of the 1918 influenza pandemic, which killed an estimated 50 million people worldwide, contradicts the widespread belief the flu disproportionately impacted healthy young adults.

Because so many people fell ill so quickly, physicians at the time believed the healthy were as likely to die from the flu as those who had already been sick or frail. Despite numerous historical accounts, though, it turns out there is no concrete scientific evidence to support that belief.

Researchers at McMaster University and the University of Colorado Boulder who analyzed victims' age of death and studied lesions on victims' bones report that the most susceptible to dying of the flu had exhibited signs of previous environmental, social and nutritional stress.

"Our circumstances -- social, cultural and immunological -- are all intertwined and have always shaped the life and death of people, even in the distant past," explains Amanda Wissler, an assistant professor in the Department of Anthropology at McMaster and lead author on the study, published today in the journal PNAS.

"We saw this during COVID-19, where our social backgrounds and our cultural backgrounds influenced who was more likely to die, and who was likely to survive," she says.

Much of the research on the 1918 pandemic relies on historical documentation such as vital statistics, census data and life insurance records, none of which include information on pre-existing conditions, or general environmental, dietary or other chronic stressors which can impact one's overall health over the course of a lifetime.

For the study, researchers examined the skeletal remains of 369 individuals from the Hamman-Todd Documented skeletal collection, which is housed at the Cleveland Museum of Natural History. All had died between 1910 and 1938. The sample was divided into two groups: a control group who had died before the pandemic, and those who died during the pandemic.

A living person's skeletal structure may undergo lasting changes due to poor health, resulting in diminished height, irregular growth, developmental tooth defects and other indicators.

The team searched for lesions, or indicators of stress, on the shinbones of the pandemic victims. New bone formation occurs in response to inflammation caused by physical trauma or infection, for example. Researchers can determine if a lesion had been active, in the midst of healing or had completely healed, all of which provide evidence of underlying conditions.

"By comparing who had lesions, and whether these lesions were active or healing at the time of death, we get a picture of what we call frailty, or who is more likely to die. Our study shows that people with these active lesions are the most frail," says Sharon DeWitte, a biological anthropologist at the University Colorado Boulder and co-author on the study.

Preexisting medical conditions such as asthma or congestive heart failure are common risk factors which can contribute to poor outcomes from infectious diseases such as influenza.

Racism and institutional discrimination can amplify these effects, as evidenced in the COVID-19 pandemic, say researchers. During the Black Death in London, for example, individuals who had previously suffered environmental, nutritional and disease stressors were more likely to die from the plague than their healthier peers.

"The results of our work counter the narrative and the anecdotal accounts of the time," says Wissler. "This paints a very complicated picture of life and death during the 1918 pandemic."

Read more at Science Daily

Pulsars may make dark matter glow

The central question in the ongoing hunt for dark matter is: what is it made of? One possible answer is that dark matter consists of particles known as axions. A team of astrophysicists, led by researchers from the universities of Amsterdam and Princeton, has now shown that if dark matter consists of axions, it may reveal itself in the form of a subtle additional glow coming from pulsating stars.

Dark matter may be the most sought-for constituent of our universe. Surprisingly, this mysterious form of matter, that physicist and astronomers so far have not been able to detect, is assumed to make up an enormous part of what is out there. No less than 85% of matter in the universe is suspected to be 'dark', presently only noticeable through the gravitational pull it exerts on other astronomical objects. Understandably, scientists want more. They want to really see dark matter -- or at the very least, detect its presence directly, not just infer it from gravitational effects. And, of course: they want to know what it is.

Cleaning up two problems

One thing is clear: dark matter cannot be the same type of matter that you and I are made of. If that were to be the case, dark matter would simply behave like ordinary matter -- it would form objects like stars, light up, and no longer be 'dark'. Scientists are therefore looking for something new -- a type of particle that nobody has detected yet, and that probably only interacts very weakly with the types of particles that we know, explaining why this constituent of our world so far has remained elusive.

There are plenty of clues for where to look. One popular assumption is that dark matter could be made of axions. This hypothetical type of particle was first introduced in the 1970s to resolve a problem that had nothing to do with dark matter. The separation of positive and negative charges inside the neutron, one of the building blocks of ordinary atoms, turned out to be unexpectedly small. Scientists of course wanted to know why. It turned out that the presence of a hitherto undetected type of particle, interacting very weakly with the neutron's constituents, could cause exactly such an effect. The later Nobel Prize winner Frank Wilczek came up with a name for the new particle: axion -- not just similar to other particle names like proton, neutron, electron and photon, but also inspired by a laundry detergent of the same name. The axion was there to clean up a problem.

In fact, despite never being detected, it might clean up two. Several theories for elementary particles, including string theory, one of the leading candidate theories to unify all forces in nature, appeared to predict that axion-like particles could exist. If axions were indeed out there, could they also constitute part or even all of the missing dark matter? Perhaps, but an additional question that haunted all dark matter research was just as valid for axions: if so, then how can we see them? How does one make something 'dark' visible?

Shining a light on dark matter

Fortunately, it seems that for axions there may be a way out of this conundrum. If the theories that predict axions are correct, they are not only expected to be mass-produced in the universe, but some axions could also be converted into light in the presence of strong electromagnetic fields. Once there is light, we can see. Could this be the key to detect axions -- and therefore to detect dark matter?

To answer that question, scientists first had to ask themselves where in the universe the strongest known electric and magnetic fields occur. The answer is: in regions surrounding rotating neutron stars also known as pulsars. These pulsars -- short for 'pulsating stars' -- are dense objects, with a mass roughly the same as that of our Sun, but a radius that is around 100,000 times smaller, only about 10 km. Being so small, pulsars spin with enormous frequencies, emitting bright narrow beams of radio emission along their axis of rotation. Similar to a lighthouse, the pulsar's beams can sweep across the Earth, making the pulsating star easily observable.

However, the pulsar's enormous spin does more. It turns the neutron star into an extremely strong electromagnet. That, in turn, could mean that pulsars are very efficient axion factories. Every single second an average pulsar would be capable of producing a 50-digit number of axions. Because of the strong electromagnetic field around the pulsar, a fraction of these axions could convert into observable light. That is: if axions exist at all -- but the mechanism can now be used to answer just that question. Just look at pulsars, see if they emit extra light, and if they do, determine whether this extra light could be coming from axions.

Simulating a subtle glow

As always in science, actually performing such an observation is of course not that simple. The light emitted by axions -- detectable in the form of radio waves -- would only be a small fraction of the total light that these bright cosmic lighthouses send our way. One needs to know very precisely what a pulsar without axions would look like, and what a pulsar with axions would look like, to be able to see the difference -- let alone to quantify that difference and turn it into a measurement of an amount of dark matter.

This is exactly what a team of physicists and astronomers have now done. In a collaborative effort between the Netherlands, Portugal and the USA, the team has constructed a comprehensive theoretical framework which allows for the detailed understanding of how axions are produced, how axions escape the gravitational pull of the neutron star, and how, during their escape, they convert into low energy radio radiation.

The theoretical results were then put on a computer to model the production of axions around pulsars, using state-of-the-art numerical plasma simulations that were originally developed to understand the physics behind how pulsars emit radio waves. Once virtually produced, the propagation of the axions through the electromagnetic fields of the neutron star was simulated. This allowed the researchers to quantitatively understand the subsequent production of radio waves and model how this process would provide an additional radio signal on top of the intrinsic emission generated from the pulsar itself.

Putting axion models to a test

The results from theory and simulation were then put to a first observational test. Using observations from 27 nearby pulsars, the researchers compared the observed radio waves to the models, to see if any measured excess could provide evidence for the existence of axions. Unfortunately, the answer was 'no' -- or perhaps more optimistically: 'not yet'. Axions do not immediately jump out to us, but perhaps that was not to be expected. If dark matter were to give up its secrets that easily, it would already have been observed a long time ago.

The hope for a smoking-gun detection of axions, therefore, is now on future observations. Meanwhile, the current non-observation of radio signals from axions is an interesting result in itself. The first comparison between simulations and actual pulsars has placed the strongest limits to date on the interaction that axions can have with light.

Read more at Science Daily

Astronomers discover first step toward planet formation

Astronomers have gotten very good at spotting the signs of planet formation around stars. But for a complete understanding of planet formation, we also need to study examples where planet formation has not yet started. Looking for something and not finding it can be even more difficult than finding it sometimes, but new detailed observations of the young star DG Taurus show that it has a smooth protoplanetary disk without signs of planet formation. This successful non-detection of planet formation may indicate that DG Taurus is on the eve of planet formation.

Planets form in disks of gas and dust, known as protoplanetary disks, around protostars, young stars still in the process of forming. Planet growth is so slow that it's not possible to watch the evolution as it happens, so astronomers observe many protostars at slightly different stages of planet formation to build up a theoretical understanding.

This time an international research team led by Satoshi Ohashi at the National Astronomical Observatory of Japan (NAOJ) used the Atacama Large Millimeter/submillimeter Array (ALMA) to conduct high-resolution observations of a protoplanetary disk around a relatively young protostar, DG Taurus located 410 light-years away in the direction of the constellation Taurus. The team found that DG Taurus has a smooth protoplanetary disk, without any rings which would indicate that planets are forming. This led the team to believe that DG Taurus system will start forming planets in the future.

The team found that in this pre-planet-formation stage, the dust grains within 40 AU (about twice the size of the orbit of Uranus in the Solar System) of the central protostar are still small, while beyond this radius the dust grains have started to grow in size, the first step in planet formation. This is contrary to theoretical expectations that planet formation starts in the inner part of the disk.

Read more at Science Daily

Ancient carbon in rocks releases as much carbon dioxide as the world's volcanoes

A new study led by the University of Oxford has overturned the view that natural rock weathering acts as a CO2 sink, indicating instead that this can also act as a large CO2 source, rivalling that of volcanoes. The results, published today in the journal Nature, have important implications for modelling climate change scenarios.

Rocks contain an enormous store of carbon in the ancient remains of plants and animals that lived millions of years ago. This means that the "geological carbon cycle" acts as a thermostat that helps to regulate the Earth's temperature. For instance, during chemical weathering rocks can suck up CO2 when certain minerals are attacked by the weak acid found in rainwater. This process helps to counteract the continuous CO2 released by volcanoes around the world, and forms part of Earth's natural carbon cycle that has helped keep the surface habitable to life for a billion years or more.

However, for the first time this new study measured an additional natural process of CO2 release from rocks to the atmosphere, finding that it is as significant as the CO2 released from volcanoes around the world. Currently, this process is not included in most models of the natural carbon cycle.

The process occurs when rocks that formed on ancient seafloors (where plants and animals were buried in sediments) are pushed back up to Earth's surface, for example when mountains like the Himalayas or Andes form. This exposes the organic carbon in the rocks to oxygen in the air and water, which can react and release CO2. This means that weathering rocks could be a source of CO2, rather than the commonly assumed sink.

Up to now, measuring the release of this CO2 from weathering organic carbon in rocks has proved difficult. In the new study, the researchers used a tracer element (rhenium) which is released into water when rock organic carbon reacts with oxygen. Sampling river water to measure rhenium levels makes it possible to quantify CO2 release. However, sampling all river water in the world to get a global estimate would be a significant challenge.

To upscale over Earth's surface, the researchers did two things. First, they worked out how much organic carbon is present in rocks near the surface. Second, they worked out where these were being exposed most rapidly, by erosion in steep, mountain locations.

Dr Jesse Zondervan, the researcher who led the study at the Department of Earth Sciences, University of Oxford, said: "The challenge was then how to combine these global maps with the river data, while considering uncertainties. We fed all of our data into a supercomputer at Oxford, simulating the complex interplay of physical, chemical, and hydrological processes. By piecing together this vast planetary jigsaw, we could finally estimate the total carbon dioxide emitted as these rocks weather and exhale their ancient carbon into the air."

This could then be compared to how much CO2 could be drawn down by natural rock weathering of silicate minerals. The results identified many large areas where weathering was a CO2 source, challenging the current view about how weathering impacts the carbon cycle. Hotspots of CO2 release were concentrated in mountain ranges with high uplift rates that cause sedimentary rocks to be exposed, such as the eastern Himalayas, the Rocky Mountains, and the Andes. The global CO2 release from rock organic carbon weathering was found to be 68 megatons of carbon per year.

Professor Robert Hilton (Department of Earth Sciences, University of Oxford), who leads the ROC-CO2 research project that funded the study, said: "This is about 100 times less than present day human CO2 emissions by burning fossil fuels, but it is similar to how much CO2 is released by volcanoes around the world, meaning it is a key player in Earth's natural carbon cycle."

These fluxes could have changed during Earth's past. For instance, during periods of mountain building that bring up many rocks containing organic matter, the CO2 release may have been higher, influencing global climate in the past.

Ongoing and future work is looking into how changes in erosion due to human activities, alongside the increased warming of rocks due to anthropogenic climate changes, could increase this natural carbon leak. A question the team are now asking is if this natural CO2 release will increase over the coming century. "Currently we don't know -- our methods allow us to provide a robust global estimate, but not yet assess how it could change'' says Hilton.

Read more at Science Daily

Survival of the newest: the mammals that survive mass extinctions aren't as 'boring' as scientists thought

When an asteroid hit the Earth 66 million years ago, it set off a devastating mass extinction. The dinosaurs (except for a few birds) all died out, along with lots of the mammals. But some small mammals survived, laying the groundwork for all the mammals alive today. For decades, scientists have assumed that mammals and their relatives that survived challenging times (like those during mass extinctions) made it because they were generalists that were able to eat just about anything and adapt to whatever life threw at them. A new study into the mammal family tree through multiple mass extinctions revealed that the species that survived aren't as generic as scientists had thought: instead, having new and different traits can be the key to succeeding in the aftermath of a catastrophe.

"The idea of the 'survival of the unspecialized' goes back to the 1800s, and the conventional wisdom is that generalized animals are the least likely to go extinct. But we found that the ones that survived more often only seemed generalized in hindsight, when compared with their later descendents. They were actually pretty advanced animals for their time, with new traits that might have helped them survive and provided evolutionary flexibility," says Ken Angielczyk, the MacArthur Curator of Paleomammalogy at the Field Museum and senior author of the study in Nature Ecology and Evolution.

"What's been thought previously is that every time a new group of mammals evolves, you start out with a small generalist animal, since when disaster strikes, those are the guys that keep on trucking -- they can hide anywhere, they can eat whatever is around," says Spencer Hellert, an Assistant Professor at Columbia College Chicago, a research associate at the Field Museum, and co-lead author of the study. "The kind of mammal that survives a mass extinction won't be a specialist like a panda bear that can only eat bamboo."

David Grossnickle, an Assistant Professor at the Oregon Institute of Technology and co-lead author, published a study in 2019 that highlighted how small, insect-eating mammals are often the lineages that survive challenging times, including the extinction event that killed the dinosaurs, and serve as forerunners of major diversifications. He approached Hellert and Angielczyk to see if that trend held true for earlier mammals and their ancestors.

Hellert created a massive family tree of the synapsids, the group of animals of which mammals are the last surviving members. This family tree is one of the largest fossil trees ever produced, and it takes into account all the previous family trees made by scientists for this group. This method is a more formal, rigorous, and repeatable way to summarize information from lots of trees instead of just picking a few and sticking them together.

"We couldn't test this idea without a humongous family tree," says Angielczyk, "along with general information about the animals' diets and body sizes. Then we looked at what happened over time through the five major evolutionary radiations in synapsids," when a few species branched out into greater diversity. When a new disaster led the majority of those species to go extinct, the process repeated itself.

The researchers, including co-authors Graeme Lloyd and Christian Kammerer, found that the story of synapsid evolution wasn't one of "survival of the small and unspecialized." At some points, larger synapsids were the ones that survived, and the winners weren't just generalist insect-eaters.

"We were pretty surprised -- it's pretty well-established that those mammal radiations go from these small insectivores into the bigger taxa repeatedly, so I was kind of expecting to see that as we went back into synapsid history. And when we went back, that pattern starts to disappear," says Grossnickle.

While some of the survivors of mass extinctions at first appeared to be unspecialized, closer analysis revealed that they had newer, more novel characteristics. For instance, many mammals from the time of the dinosaurs had teeth that were good for cutting into prey. A few had tooth structures that acted like a mortar and pestle and were able to grind in addition to just cutting. This "fancier" tooth may have been an advantage in hard times with less food availability, because this more specialized tooth structure would have let them eat a wider variety of food.

These findings don't mean that hyper-specialized animals, like pandas that only eat bamboo, are less vulnerable to the threat of extinction than more generalist species, like raccoons that can eat a wider variety of foods. Instead, the study shows that the mammal relatives that made it through mass extinctions aren't as generic as previously assumed.

"Animals with novel traits like new tooth features, or jaws that work a little better at breaking down different food items, don't really take over ecologically until the incumbent, older lineages go extinct," says Grossnickle. "You often need an extinction event like the one that killed the dinosaurs to knock out some of those older groups, and then it allows those fancier animals to persist and diversify."

Read more at Science Daily

Natural GM crops: Grasses take evolutionary shortcut by borrowing genes from their neighbors

Grass may transfer genes from their neighbours in the same way genetically modified crops are made, a new study has revealed.

Research, led by the University of Sheffield, is the first to show the frequency at which grasses incorporate DNA from other species into their genomes through a process known as lateral gene transfer.

The stolen genetic secrets give them an evolutionary advantage by allowing them to grow faster, bigger or stronger and adapt to new environments quicker.

Understanding the rate is important to know the potential impact it can have on a plant's evolution and how it adapts to the environment.

Grasses are the most ecologically and economically important group of plants, covering 30% of the earth's terrestrial surface and producing a majority of our food.

The Sheffield team sequenced multiple genomes of a species of tropical grass and determined at different time points in its evolution how many genes were acquired -- giving a rate of accumulation.

It is now thought these transfers are likely to occur in the same way that some genetically modified crops are made.

These findings, published in the journal New Phytologist could inform future work to harness the process to improve crop productivity and make more resilient crops, and have implications on how we view and use controversial GM crops.

Dr. Luke Dunning, Research Fellow from the University of Sheffield's School of Biosciences, and senior author of the research, said: "There are many methods to make GM crops, some which require substantial human intervention and some that don't. Some of these methods that require minimal human intervention could occur naturally and facilitate the transfers we have observed in wild grasses.

"These methods work by contaminating the reproductive process with DNA from a third individual. Our current working hypothesis, and something we plan to test in the near future, is that these same methods are responsible for the gene transfers we document in wild grasses.

"This means, in the near future, controversial genetic modification could be perceived as more of a natural process.

"Currently, these 'natural' reproductive contamination methods are not as efficient in producing GM plants as those that are used routinely, but by further understanding how lateral gene transfer occurs in the wild we may be able to increase the success of this process."

Since Darwin, much of our understanding of evolution has been based on the assumption that genetic information is passed from parents to offspring -- the rule of common descent for plant and animal evolution.

Read more at Science Daily

Plot thickens in hunt for ninth planet

A pair of theoretical physicists are reporting that the same observations inspiring the hunt for a ninth planet might instead be evidence within the solar system of a modified law of gravity originally developed to understand the rotation of galaxies.

Researchers Harsh Mathur, a professor of physics at Case Western Reserve University, and Katherine Brown, an associate professor of physics at Hamilton College, made the assertion after studying the effect the Milky Way galaxy would have on objects in the outer solar system -- if the laws of gravity were governed by a theory known as Modified Newtonian Dynamics (or MOND).

MOND proposes Isaac Newton's famous law of gravity is valid up to a point. That is, when the gravitational acceleration predicted by Newton's law becomes small enough, MOND allows for a different gravitational behavior to take over.

The observational success of MOND on galactic scales is why some scientists consider it an alternative to "dark matter," the term physicists use to describe a hypothesized form of matter that would have gravitational effects but not emit any light.

"MOND is really good at explaining galactic-scale observations," Mathur said, "but I hadn't expected that it would have noticeable effects on the outer solar system."

Their work was recently published in The Astronomical Journal.

A 'striking' alignment

Mathur and Brown had studied MOND's effect on galactic dynamics before. But they became interested in MOND's more local effects after astronomers announced in 2016 that a handful of objects in the outer solar system showed orbital anomalies that could be explained by a ninth planet.

Orbital peculiarities have led to historic discoveries before: Neptune was discovered through its gravitational tug on the orbits of nearby object, the minute precession of Mercury provided early evidence in support of Einstein's theory of general relativity, and astronomers have recently used orbital dynamics to infer the presence of a supermassive black hole at the center of our Galaxy.

Brown realized MOND's predictions might be at odds with the observations that had motivated the search for a ninth planet. "We wanted to see if the data that support the Planet Nine hypothesis would effectively rule out MOND," she said.

Instead, Mathur and Brown found MOND predicts precisely clustering that astronomers have observed. Over millions of years, they argue, the orbits of some objects in the outer solar system would be dragged into alignment with the galaxy's own gravitational field.

When they plotted the orbits of the objects from the Planet Nine dataset against the galaxy's own gravitational field, "the alignment was striking," Mathur said.

The authors caution that the current dataset is small and that that any number of other possibilities might prove to be correct; other astronomers have argued the orbital peculiarities are the result of observational bias, for example.

Read more at Science Daily

Climate change brings earlier arrival of intense hurricanes

Intense tropical cyclones are one of the most devastating natural disasters in the world due to torrential rains, flooding, destructive winds, and coastal storm surges. New research co-authored by a University of Hawai'i at Manoa atmospheric scientist revealed that since the 1980s, Category 4 and 5 hurricanes (maximum wind speed greater than 131 miles per hour) have been arriving three to four days earlier with each passing decade of climate change. Their findings were published recently in Nature.

"When intense tropical cyclones occur earlier than usual, they cause unexpected problems for communities," said Pao-Shin Chu, atmospheric sciences professor in the UH Manoa School of Ocean and Earth Science and Technology and Hawai'i State Climatologist. "Moreover, the earlier advance of these storms will overlap with other weather systems, for example local thunderstorms or seasonal monsoon rainfall, and can produce compounding extreme events and strain the emergency response."

Changes in many characteristics of intense hurricanes under a warming climate, for example, the number, intensity, and lifespan, are fairly well-studied. However, little is known about changes in the seasonal cycle of these intense events.

Using satellite data, historical tropical cyclone tracks, NOAA rainfall records, and various statistical methods, Chu and co-authors found that there has been a significant shift of these intense tropical cyclones from autumn to summer months since the 1980s in most tropical oceans. The effect was particularly observed in the eastern North Pacific off the coast of Mexico, where most hurricanes near Hawai'i come from; the western North Pacific; the South Pacific; the Gulf of Mexico; and the Atlantic coast of Florida and the Caribbean.

"It was surprising to consistently see earlier arrivals when we independently assessed satellite data and conventional ground-based observations of intense tropical cyclones," said Chu.

In August 2017, for example, Hurricane Harvey, a Category 4 hurricane, made landfall on Texas and Louisiana and inflicted catastrophic flooding and more than 100 deaths.

Using simulations from multiple global climate models (e.g., high-resolution CMIP6 models), the team detected warmer oceanic conditions developed earlier, which favored the earlier onset of intense tropical cyclones. Further, they found that the warming was primarily driven by greenhouse gas forcing.

"In a future with high carbon dioxide emissions, the earlier shifting trend is projected to be amplified," said Chu.

In South China and the Gulf of Mexico, the earlier onset of intense tropical cyclones contributes significantly to an earlier onset of extreme rainfall.

Read more at Science Daily

The medicine of the future could be artificial life forms

Creating artificial life is a recurring theme in both science and popular literature, where it conjures images of creeping slime creatures with malevolent intentions or super-cute designer pets. At the same time, the question arises: What role should artificial life play in our environment here on Earth, where all life forms are created by nature and have their own place and purpose?

Associate professor Chenguang Lou from the Department of Physics, Chemistry, and Pharmacy, University of Southern Denmark, together with Professor Hanbin Mao from Kent State University, is the parent of a special artificial hybrid molecule that could lead to the creation of artificial life forms. They have now published a review in the journal Cell Reports Physical Science on the state of research in the field behind their creation. The field is called "hybrid peptide-DNA nanostructures," and it is an emerging field, less than ten years old.

Lou's vision is to create viral vaccines (modified and weakened versions of a virus) and artificial life forms that can be used for diagnosing and treating diseases.

"In nature, most organisms have natural enemies, but some do not. For example, some disease-causing viruses have no natural enemy. It would be a logical step to create an artificial life form that could become an enemy to them," he says.

Similarly, he envisions such artificial life forms can act as vaccines against viral infection and can be used as nanorobots or nanomachines loaded with medication or diagnostic elements and sent into a patient's body.

"An artificial viral vaccine may be about 10 years away. An artificial cell, on the other hand, is on the horizon because it consists of many elements that need to be controlled before we can start building with them. But with the knowledge we have, there is, in principle, no hindrance to produce artificial cellular organisms in the future," he says.

What are the building blocks that Lou and his colleagues in this field will use to create viral vaccines and artificial life? DNA and peptides are some of the most important biomolecules in nature, making DNA technology and peptide technology the two most powerful molecular tools in the nanotechnological toolkit today. DNA technology provides precise control over programming, from the atomic level to the macro level, but it can only provide limited chemical functions since it only has four bases: A, C, G, and T. Peptide technology, on the other hand, can provide sufficient chemical functions on a large scale, as there are 20 amino acids to work with. Nature uses both DNA and peptides to build various protein factories found in cells, allowing them to evolve into organisms.

Recently, Hanbin Mao and Chenguang Lou have succeeded in linking designed three-stranded DNA structures with three-stranded peptide structures, thus creating an artificial hybrid molecule that combines the strengths of both. This work was published in Nature Communications in 2022.

Elsewhere in the world, other researchers are also working on connecting DNA and peptides because this connection forms a strong foundation for the development of more advanced biological entities and life forms.

At Oxford University, researchers have succeeded in building a nanomachine made of DNA and peptides that can drill through a cell membrane, creating an artificial membrane channel through which small molecules can pass. (Spruijt et al., Nat. Nanotechnol. 2018, 13, 739-745)

At Arizona State University, Nicholas Stephanopoulos and colleagues have enabled DNA and peptides to self-assemble into 2D and 3D structures. (Buchberger et al., J. Am. Chem. Soc. 2020, 142, 1406-1416)

At Northwest University, researchers have shown that microfibers can form in conjunction with DNA and peptides self-assembling. DNA and peptides operate at the nano level, so when considering the size differences, microfibers are huge. (Freeman et al., Science, 2018, 362, 808-813)

At Ben-Gurion University of the Negev, scientists have used hybrid molecules to create an onion-like spherical structure containing cancer medication, which holds promise to be used in the body to target cancerous tumors. (Chotera et al., Chem. Eur. J., 2018, 24, 10128-10135)

Read more at Science Daily