James Webb Telescope catches glimpse of possible first-ever 'dark stars'

Stars beam brightly out of the darkness of space thanks to fusion, atoms melding together and releasing energy. But what if there's another way to power a star?

A team of three astrophysicists -- Katherine Freese at The University of Texas at Austin, in collaboration with Cosmin Ilie and Jillian Paulin '23 at Colgate University -- analyzed images from the James Webb Space Telescope (JWST) and found three bright objects that might be "dark stars," theoretical objects much bigger and brighter than our sun, powered by particles of dark matter annihilating. If confirmed, dark stars could reveal the nature of dark matter, one of the deepest unsolved problems in all of physics.

"Discovering a new type of star is pretty interesting all by itself, but discovering it's dark matter that's powering this -- that would be huge," said Freese, director of the Weinberg Institute for Theoretical Physics and the Jeff and Gail Kodosky Endowed Chair in Physics at UT Austin.

Although dark matter makes up about 25% of the universe, its nature has eluded scientists. Scientists believe it consists of a new type of elementary particle, and the hunt to detect such particles is on. Among the leading candidates are Weakly Interacting Massive Particles. When they collide, these particles annihilate themselves, depositing heat into collapsing clouds of hydrogen and converting them into brightly shining dark stars. The identification of supermassive dark stars would open up the possibility of learning about the dark matter based on their observed properties.

The research is published in the Proceedings of the National Academy of Sciences.

Follow-up observations from JWST of the objects' spectroscopic properties -- including dips or excess of light intensity in certain frequency bands -- could help confirm whether these candidate objects are indeed dark stars.

Confirming the existence of dark stars might also help solve a problem created by JWST: There seem to be too many large galaxies too early in the universe to fit the predictions of the standard model of cosmology.

"It's more likely that something within the standard model needs tuning, because proposing something entirely new, as we did, is always less probable," Freese said. "But if some of these objects that look like early galaxies are actually dark stars, the simulations of galaxy formation agree better with observations."

The three candidate dark stars (JADES-GS-z13-0, JADES-GS-z12-0, and JADES-GS-z11-0) were originally identified as galaxies in December 2022 by the JWST Advanced Deep Extragalactic Survey (JADES). Using spectroscopic analysis, the JADES team confirmed the objects were observed at times ranging from about 320 million to 400 million years after the Big Bang, making them some of the earliest objects ever seen.

"When we look at the James Webb data, there are two competing possibilities for these objects," Freese said. "One is that they are galaxies containing millions of ordinary, population-III stars. The other is that they are dark stars. And believe it or not, one dark star has enough light to compete with an entire galaxy of stars."

Dark stars could theoretically grow to be several million times the mass of our sun and up to 10 billion times as bright as the sun.

"We predicted back in 2012 that supermassive dark stars could be observed with JWST," said Ilie, assistant professor of physics and astronomy at Colgate University. "As shown in our recently published PNAS article, we already found three supermassive dark star candidates when analyzing the JWST data for the four high redshift JADES objects spectroscopically confirmed by Curtis-Lake et al, and I am confident we will soon identify many more."

The idea for dark stars originated in a series of conversations between Freese and Doug Spolyar, at the time a graduate student at the University of California, Santa Cruz. They wondered: What does dark matter do to the first stars to form in the universe? Then they reached out to Paolo Gondolo, an astrophysicist at the University of Utah, who joined the team. After several years of development, they published their first paper on this theory in the journal Physical Review Letters in 2008.

Together, Freese, Spolyar and Gondolo developed a model that goes something like this: At the centers of early protogalaxies, there would be very dense clumps of dark matter, along with clouds of hydrogen and helium gas. As the gas cooled, it would collapse and pull in dark matter along with it. As the density increased, the dark matter particles would increasingly annihilate, adding more and more heat, which would prevent the gas from collapsing all the way down to a dense enough core to support fusion as in an ordinary star. Instead, it would continue to gather more gas and dark matter, becoming big, puffy and much brighter than ordinary stars. Unlike ordinary stars, the power source would be evenly spread out, rather than concentrated in the core. With enough dark matter, dark stars could grow to be several million times the mass of our sun and up to 10 billion times as bright as the sun.

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Fear is in the eye of the beholder

Averting our eyes from things that scare us may be due to a specific cluster of neurons in a visual region of the brain, according to new research at the University of Tokyo. Researchers found that in fruit fly brains, these neurons release a chemical called tachykinin which appears to control the fly's movement to avoid facing a potential threat. Fruit fly brains can offer a useful analogy for larger mammals, so this research may help us better understand our own human reactions to scary situations and phobias. Next, the team want to find out how these neurons fit into the wider circuitry of the brain so they can ultimately map out how fear controls vision.

Do you cover your eyes during horror movies? Or perhaps the sight of a spider makes you turn and run? Avoiding looking at things which scare us is a common experience, for humans and animals. But what actually makes us avert our gaze from the things we fear? Researchers have found that it may be due to a group of neurons in the brain which regulates vision when feeling afraid.

"We discovered a neuronal mechanism by which fear regulates visual aversion in the brains of Drosophila (fruit flies). It appears that a single cluster of 20-30 neurons regulates vision when in a state of fear. Since fear affects vision across animal species, including humans, the mechanism we found may be active in humans as well," explained Assistant Professor Masato Tsuji from the Department of Biological Sciences at the University of Tokyo.

The team used puffs of air to simulate a physical threat and found that the flies' walking speed increased after being puffed at. The flies also would choose a puff-free route if offered, showing that they perceived the puffs as a threat (or at least preferred to avoid them). Next the researchers placed a small black object, roughly the size of a spider, 60 degrees to the right or left of the fly. On its own the object didn't cause a change in behavior, but when placed following puffs of air, the flies avoided looking at the object and moved so that it was positioned behind them.

To understand the molecular mechanism underlying this aversion behavior, the team then used mutated flies in which they altered the activity of certain neurons. While the mutated flies kept their visual and motor functions, and would still avoid the air puffs, they did not respond in the same fearful manner to visually avoid the object.

"This suggested that the cluster of neurons which releases the chemical tachykinin was necessary for activating visual aversion," said Tsuji. "When monitoring the flies' neuronal activity, we were surprised to find that it occurred through an oscillatory pattern, i.e., the activity went up and down similar to a wave. Neurons typically function by just increasing their activity levels, and reports of oscillating activity are particularly rare in fruit flies because up until recently the technology to detect this at such a small and fast scale didn't exist."

By giving the flies genetically encoded calcium indicators, the researchers could make the flies' neurons shine brightly when activated. Thanks to the latest imaging techniques, they then saw the changing, wavelike pattern of light being emitted, which was previously averaged out and missed.

Next, the team wants to figure out how these neurons fit into the broader circuitry of the brain. Although the neurons exist in a known visual region of the brain, the researchers do not yet know from where the neurons are receiving inputs and to where they are transmitting them, to regulate visual escape from objects perceived as dangerous.

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Multiple ecosystems in hot water after marine heatwave surges across the Pacific

Rising ocean temperatures are sweeping the seas, breaking records and creating problematic conditions for marine life. Unlike heatwaves on land, periods of abrupt ocean warming can surge for months or years. Around the world these 'marine heatwaves' have led to mass species mortality and displacement events, economic declines and habitat loss. New research reveals that even areas of the ocean protected from fishing are still vulnerable to these extreme events fueled by climate change.

A study published today in Global Change Biology, led by researchers at UC Santa Barbara, found that while California's network of marine protected areas (MPAs) provide many social and ecological benefits, they are not resilient to the effects of ocean warming. MPAs are locations in the ocean where human activities such as fishing are restricted to conserve and protect marine ecosystems, habitats, species and cultural resources. The study, part of a 10-year review of California's MPA network conducted at UCSB's National Center for Ecological Analysis & Synthesis (NCEAS), found that marine heatwaves impact ecological communities regardless of whether they are protected inside MPAs.

"MPAs in California and around the world have many benefits, such as increased fish abundance, biomass and diversity," said Joshua Smith, who led the study while he was a postdoctoral researcher at NCEAS . "But they were never designed to buffer the impacts of climate change or marine heatwaves."

Smith and co-authors from all over the world were part of an NCEAS working group formed to synthesize decades of long-term ecological monitoring data from California's diverse ocean habitats. The group, co-led by Jenn Caselle, a researcher with UCSB's Marine Science Institute, and Kerry Nickols, a professor from Cal State University Northridge who now works with the non-profit Ocean Visions, aimed to provide actionable scientific results to California's policy makers and natural resource managers, as part of a statewide Decadal Evaluation of the MPA network. Their analyses spanned the largest marine heatwave on record, which rolled through the Pacific Ocean toward California from 2014-2016. The monster marine heatwave was formed from an environmental double-whammy -- unusual ocean warming nicknamed "The Blob," followed by a major El Niño event that prolonged the sweltering sea temperatures. The marine heatwave blanketed the West Coast from Alaska to Baja and left a wake of altered food webs, collapsed fisheries, and shifted populations of marine life among various other consequences.

As MPA managers around the world face increasing climate shocks, the extent to which MPAs can buffer the worst of these events has become an important question. The working group scientists asked how the ecological communities in California's protected areas fared after such a severe and prolonged heatwave: Would the communities shift and if so, how? Would they 'bounce back' when the marine heatwave subsided? Could the marine protected areas protect sensitive populations or facilitate recovery?

To find answers to their questions, they synthesized over a decade of data collected from 13 no-take MPAs located in a variety of ecosystems along the Central Coast: rocky intertidal zones, kelp forests, shallow and deep rocky reefs. The team looked at fish, invertebrates and seaweed populations inside and outside these areas, using data from before, during and after the heatwave.

They also focused on two of these habitats, rocky intertidal and kelp forests, at 28 MPAs across the full statewide network to gauge whether these locations promoted one particular form of climate resilience -- maintaining both population and community structure.

"We used no-take MPAs as a type of comparison to see whether the protected ecological communities fared better to the marine heatwave than places where fishing occurred," said Smith, now an Ocean Conservation Research Fellow at Monterey Bay Aquarium.

The results are somewhat sobering, though not altogether unexpected.

"The MPAs did not facilitate resistance or recovery across habitats or across communities," Caselle said. "In the face of this unprecedented marine heatwave, communities did change dramatically in most habitats. But, with one exception, the changes occurred similarly both inside and outside the MPAs. The novelty of this study was that we saw similar results across many different habitats and taxonomic groups, from deepwater to shallow reefs and from fishes to algae."

The implication of these findings, according to Smith, is that every part of the ocean is under threat from climate change. "MPAs are effective in many of the ways they were designed, but our findings suggest that MPAs alone are not sufficient to buffer the effects of climate change."

The key question now is what will happen in the future? At the time of this study using data through 2020, the ecological communities have not returned to their former, pre-heatwave state. According to the paper, these ecological communities shifted toward a "pronounced decline in the relative proportion of cold-water species and an increase in warm water species." For example, increases in the abundance of the señorita fish (Oxyjulis californica), a subtropical species with warm water affinity and previously rare in central California, had an outsized influence on the shift of communities. Whether these species persist in their new locations remains to be seen.

"This study makes it clear why long-term monitoring of California's MPAs is so critical," said Caselle. "Some of these time series are longer than 25 years at this point and the data are critical to understanding and readying human communities for the changes occurring in our marine communities." Continued study will show if future shifts in marine communities occur at different rates or to different base states in MPAs compared to fished areas.

Despite the limited ability of MPAs to resist the grip of the marine heatwave, they do confer benefits, not the least of which is the ability to study the complex effects of climate change in areas not impacted by fishing. As areas of minimal human interference that are regularly monitored, they present opportunities to study the response of marine ecosystems to shifting conditions and potentially tailor management techniques accordingly. Moreover, as Smith stated, "the ecological communities in MPAs are still being protected, even if they are different as a result of the heatwave. Given that marine heatwaves are anticipated to increase in frequency and magnitude into the future, swift climate action and nature-based solutions are needed as additional pathways to enhance the health of our oceans."

Kerry Nickols adds, "With the devastating impacts of climate change already apparent, it is very important that we are upfront about climate solutions -- as long as we are burning fossil fuels and warming the globe marine ecosystems will be at risk, even if they are protected from fishing."

Read more at Science Daily

Genes for learning and memory are 650 million years old

A team of scientists led by researchers from the University of Leicester have discovered that the genes required for learning, memory, aggression and other complex behaviours originated around 650 million years ago.

The findings led by Dr Roberto Feuda, from the Neurogenetic group in the Department of Genetics and Genome Biology and other colleagues from the University of Leicester and the University of Fribourg (Switzerland), have now been published in Nature Communications.

Dr Feuda said: "We've known for a long time that monoamines like serotonin, dopamine and adrenaline act as neuromodulators in the nervous system, playing a role in complex behaviour and functions like learning and memory, as well as processes such as sleep and feeding.

"However, less certain was the origin of the genes required for the production, detection, and degradation of these monoamines. Using the computational methods, we reconstructed the evolutionary history of these genes and show that most of the genes involved in monoamine production, modulation, and reception originated in the bilaterian stem group.

"This finding has profound implications on the evolutionary origin of complex behaviours such as those modulated by monoamines we observe in humans and other animals."

The authors suggest that this new way to modulate neuronal circuits might have played a role in the Cambrian Explosion -- known as the Big Bang -- which gave rise to the largest diversification of life for most major animal groups alive today by providing flexibility of the neural circuits to facilitate the interaction with the environment.

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Webb celebrates first year of science with close-up on birth of sun-like stars

From our cosmic backyard in the solar system to distant galaxies near the dawn of time, NASA's James Webb Space Telescope has delivered on its promise of revealing the universe like never before in its first year of science operations. To celebrate the completion of a successful first year, NASA has released Webb's image of a small star-forming region in the Rho Ophiuchi cloud complex.

"In just one year, the James Webb Space Telescope has transformed humanity's view of the cosmos, peering into dust clouds and seeing light from faraway corners of the universe for the very first time. Every new image is a new discovery, empowering scientists around the globe to ask and answer questions they once could never dream of," said NASA Administrator Bill Nelson. "Webb is an investment in American innovation but also a scientific feat made possible with NASA's international partners that share a can-do spirit to push the boundaries of what is known to be possible. Thousands of engineers, scientists, and leaders poured their life's passion into this mission, and their efforts will continue to improve our understanding of the origins of the universe -- and our place in it."

The new Webb image released today features the nearest star-forming region to us. Its proximity at 390 light-years allows for a highly detailed close-up, with no foreground stars in the intervening space.

"On its first anniversary, the James Webb Space Telescope has already delivered upon its promise to unfold the universe, gifting humanity with a breathtaking treasure trove of images and science that will last for decades," said Nicola Fox, associate administrator of NASA's Science Mission Directorate in Washington. "An engineering marvel built by the world's leading scientists and engineers, Webb has given us a more intricate understanding of galaxies, stars, and the atmospheres of planets outside of our solar system than ever before, laying the groundwork for NASA to lead the world in a new era of scientific discovery and the search for habitable worlds."

Webb's image shows a region containing approximately 50 young stars, all of them similar in mass to the Sun, or smaller. The darkest areas are the densest, where thick dust cocoons still-forming protostars. Huge bipolar jets of molecular hydrogen, represented in red, dominate the image, appearing horizontally across the upper third and vertically on the right. These occur when a star first bursts through its natal envelope of cosmic dust, shooting out a pair of opposing jets into space like a newborn first stretching her arms out into the world. In contrast, the star S1 has carved out a glowing cave of dust in the lower half of the image. It is the only star in the image that is significantly more massive than the Sun.

"Webb's image of Rho Ophiuchi allows us to witness a very brief period in the stellar lifecycle with new clarity. Our own Sun experienced a phase like this, long ago, and now we have the technology to see the beginning of another's star's story," said Klaus Pontoppidan, who served as Webb project scientist at the Space Telescope Science Institute in Baltimore, Maryland, since before the telescope's launch and through the first year of operations.

Some stars in the image display tell-tale shadows indicating protoplanetary disks -- potential future planetary systems in the making.

A Full Year, Across the Full Sky

From its very first deep field image, unveiled by President Joe Biden, Vice President Kamala Harris, and Nelson live at the White House, Webb has delivered on its promise to show us more of the universe than ever before. However, Webb revealed much more than distant galaxies in the early universe.

"The breadth of science Webb is capable of exploring really becomes clear now, when we have a full year's worth of data from targets across the sky," said Eric Smith, associate director for research in the Astrophysics Division at NASA Headquarters and Webb program scientist. "Webb's first year of science has not only taught us new things about our universe, but it has revealed the capabilities of the telescope to be greater than our expectations, meaning future discoveries will be even more amazing." The global astronomy community has spent the past year excitedly poring over Webb's initial public data and getting a feel for how to work with it.

Beyond the stunning infrared images, what really has scientists excited are Webb's crisp spectra -- the detailed information that can be gleaned from light by the telescope's spectroscopic instruments. Webb's spectra have confirmed the distances of some of the farthest galaxies ever observed, and have discovered the earliest, most distant supermassive black holes. They have identified the compositions of planet atmospheres (or lack thereof) with more detail than ever before, and have narrowed down what kinds of atmospheres may exist on rocky exoplanets for the first time. They also have revealed the chemical makeup of stellar nurseries and protoplanetary disks, detecting water, organic carbon-containing molecules, and more. Already, Webb observations have resulted in hundreds of scientific papers answering longstanding questions and raising new ones to address with Webb.

The breadth of Webb science is also apparent in its observations of the region of space we are most familiar with -- our own solar system. Faint rings of gas giants appear out of the darkness, dotted by moons, while in the background Webb shows distant galaxies. By comparing detections of water and other molecules in our solar system with those found in the disks of other, much younger planetary systems, Webb is helping to build up clues about our own origins -- how Earth became the ideal place for life as we know it.

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Marine fossils unearth story about Panama's deep past

Between 6.4 and 5.8 million years ago, most of the land bridge that connects North and South America had already emerged and the channels connecting both Pacific and Atlantic oceans were shallow. Recent fossil discoveries in the northern Panama Canal area suggest that marine species interchange persisted across these shallow waters during the final stages of formation of the isthmus.

In 2017 and 2019, Aldo Benites-Palomino was studying fossils collected in Caribbean Panama, when he came across some unexpected specimens. He was a biology student in Perú, where his training had been very classical. As an intern and later a fellow at the Smithsonian Tropical Research Institute (STRI), his mindset shifted. His mentor, STRI staff scientist and paleobiologist Carlos Jaramillo, encouraged his students to change their focus when looking at fossils: instead of thinking about specimens or methods, to think about the questions that the fossils could help answer.

"I wanted to go to STRI because it is the most important tropical biology center in the world," said Benites-Palomino. "There I was able to learn a lot about the way biology and ecology is done in the modern world."

The fossil remains belonged to small-sized cetaceans, a group of aquatic mammals that includes whales and dolphins, and the specimens were new for the region. Most of them had been collected by Carlos de Gracia from STRI and Jorge Velez Juarbe from the Los Angeles Museum of Natural History, both co-authors in a new paper published in Biology Letters. In the article, Benites-Palomino and his colleagues go beyond describing the specimens, they also unearth the story they reveal about the isthmus' deep past.

The fossils belonged to the Late Miocene, around 6.4 to 5.8 million years ago, when the final stages of formation of the isthmus had already started. This event affected oceanic waters and marine currents across the globe and triggered speciation events, where species separated by the land bridge developed their own unique characteristics on either ocean.

However, these cetaceans found in Caribbean Panama shared similarities with other Late Miocene species from the North and South Pacific Ocean, particularly the Pisco Formation in Peru, suggesting that some organisms were still able to disperse via the shallowing seaway at a time when deep water interchange between both oceans was no longer occurring.

The lack of fossil marine mammals from the western Caribbean has thus far hampered understanding of the region's deep past, so these new findings help strengthen current knowledge regarding the connectivity between the Pacific and Caribbean marine faunas during the final phases of formation of the isthmus.

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One third of normal-weight individuals are obese, according to study based on body fat percentage

Researchers from the School of Public Health at TAU's Faculty of Medicine examined the anthropometric data of about 3,000 Israeli women and men and concluded that body fat percentage is a much more reliable indicator of an individual's overall health and cardiometabolic risk than the BMI index, widely used in clinics today. The researchers suggest that body fat percentage should become the gold standard in this respect and recommend equipping clinics all over Israel with suitable devices.

The study -- the largest of its kind ever conducted in Israel -- was led by Prof. Yftach Gepner and PhD student Yair Lahav, in collaboration with Aviv Kfir. It and was based on data from the Yair Lahav Nutrition Center in Tel Aviv. The paper was published in Frontiers in Nutrition.

Prof. Gepner: "Israel is a leader in childhood obesity and more than 60% of the country's adults are defined as overweight. The prevailing index in this respect is BMI, based on weight and height measures, which is considered a standard indicator of an individual's general health. However, despite the obvious intuitive connection between excess weight and obesity, the actual measure for obesity is the body's fat content, with the maximum normal values set at 25% for males and 35% for females. Higher fat content is defined as obesity and can cause a range of potentially life-threatening cardiometabolic diseases: heart disease, diabetes, fatty liver, kidney dysfunction, and more. The disparity between the two indexes has generated a phenomenon called 'the paradox of obesity with normal weight' -- higher than normal body fat percentage in normal-weight individuals. In this study we examined the prevalence of this phenomenon in Israel's adult population."

The researchers analyzed the anthropometric data of 3,000 Israeli women and men, accumulated over several years: BMI scores; DXA scans (using X-rays to measure body composition, including fat content); and cardiometabolic blood markers. About one third of the participants, 1,000 individuals, were found to be within the normal weight range. Of these, 38.5% of the women and 26.5% of the men were identified as 'obese with normal weight' -- having excess fat content despite their normal weight. Matching body fat percentage with blood markers for each of these individuals, the study found a significant correlation between 'obesity with normal weight' and high levels of sugar, fat, and cholesterol -- major risk factors for a range of cardiometabolic diseases. At the same time, 30% of the men and 10% of the women identified as overweight were found to have a normal body fat percentage.

Prof. Gepner: "Our findings were somewhat alarming, indicating that obesity with normal weight is much more common in Israel than we had assumed. Moreover, these individuals, being within the norm according to the prevailing BMI index, usually pass 'under the radar'. Unlike people who are identified as overweight, they receive no treatment or instructions for changing their nutrition or lifestyle -- which places them at an even greater risk for cardiometabolic diseases."

Based on their findings, the researchers concluded that body fat percentage is a more reliable indicator of an individual's general health than BMI. Consequently, they suggest that body fat percentage should become the prevailing standard of health, and recommend some convenient and accessible tools for this purpose: skinfold measurements that estimate body fat based on the thickness of the fat layer under the skin; and a user-friendly device measuring the body's electrical conductivity, already used in many fitness centers.

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Detailed map of the heart provides new insights into cardiac health and disease

In a new study, published today (12 July) in Nature, researchers have produced the most detailed and comprehensive human Heart Cell Atlas to date, including the specialised tissue of the cardiac conduction system -- where the heartbeat originates.

The multi-centre team is led by the Wellcome Sanger Institute and the National Heart and Lung Institute at Imperial College London, and has also presented a new drug-repurposing computational tool called Drug2cell, which can provide insights into the effects of drugs on heart rate.

This study is part of the international Human Cell Atlas* (HCA) initiative, which is mapping every cell type in the human body, to transform our understanding of health and disease, and will form the foundation for a fully integrated HCA Human Heart Cell Atlas.

Charting eight regions of the human heart, the work describes 75 different cell states including the cells of the cardiac conduction system -- the group of cells responsible for the heartbeat -- not understood at such a detailed level in humans before. The human cardiac conduction system, the heart's 'wiring', sends electrical impulses from the top to the bottom of the heart and coordinates the heartbeat.

By using spatial transcriptomics, which gives a "map" of where cells sit within a tissue, researchers were also able to understand how these cells communicate with each other for the first time. This map acts as a molecular guidebook, showing what healthy cells look like, and providing a crucial reference to understand what goes wrong in disease. The findings will help understand diseases such as those affecting the heart rhythm.

The assembly of a Human Heart Cell Atlas is key given that cardiovascular diseases are the leading cause of death globally. Around 20,000 electronic pacemakers are implanted each year in the UK for these disorders. These can be ineffective and are prone to complications and side-effects. Understanding the biology of the cells of the conduction system and how they differ from muscle cells paves the way to therapies to boost cardiac health and develop targeted treatments for arrhythmias.

The team also presents a new computational tool called Drug2cell. The tool can predict drug targets as well as drug side effects. It leverages single-cell profiles and the 19 million drug-target interactions in the EMBL-EBI ChEMBL database.

Unexpectedly, this tool identified that pacemaker cells express the target of certain medications, such as GLP1 drugs, which are used for diabetes and weight loss and are known to increase the heart rate as a side-effect, the mechanism of which was unclear. This study suggests that the increase in heart rate might be partly due to a direct action of these drugs on pacemaker cells, a finding the team also showed in an experimental stem cell model of pacemaker cells.

Dr James Cranley, joint first author, a cardiologist specialising in heart rhythm disorders and PhD student at the Wellcome Sanger Institute, said: "The cardiac conduction system is critical for the regular and coordinated beating of our hearts, yet the cells which make it up are poorly understood. This study sheds new light by defining the profiles of these cells, as well as the multicellular niches they inhabit. This deeper understanding opens the door to better, targeted anti-arrhythmic therapies in the future."

Dr Kazumasa Kanemaru, joint first author and Postdoctoral Fellow in the Gene Expression Genomics team at the Wellcome Sanger Institute, said: "The mechanism of activating and suppressing pacemaker cell genes is not clear, especially in humans. This is important for improving cell therapy to facilitate the production of pacemaker cells or to prevent the excessive spontaneous firing of cells. By understanding these cells at an individual genetic level, we can potentially develop new ways to improve heart treatments."

The study unearthed an unexpected discovery: a close relationship between conduction system cells and glial cells. Glial cells are part of the nervous system and are traditionally found in the brain. They have been explored very little in the heart. This research suggests that glial cells are in physical contact with conduction system cells and may play an important supporting role: communicating with the pacemaker cells, guiding nerve endings to them, and supporting their release of glutamate, a neurotransmitter.

Another key finding of the study is an immune structure on the heart's outer surface. This contains plasma cells, which release antibodies into the space around the heart to prevent infection from the nearby lungs. The researchers also identified a cellular niche enriching for a hormone that could be interpreted as an early warning sign of heart failure.

Dr Michela Noseda, senior Lecturer in Cardiac Molecular Pathology at the National Heart and Lung Institute, Imperial College London, a Coordinator of the Human Cell Atlas Heart BioNetwork and a lead author, said: "We often don't fully know what impact a new treatment will have on the heart and its electrical impulses -- this can mean a drug is withdrawn or fails to make it to the market. Our team developed the Drug2cell platform to improve how we evaluate new treatments and how they can affect our hearts, and potentially other tissues too. This could provide us with an invaluable tool to identify new drugs which target specific cells, as well as help to predict any potential side-effects early on in drug development."

Professor Metin Avkiran, Associate Medical Director at the British Heart Foundation, which part-funded the research with the German Centre for Cardiovascular Research (DZHK), said: "Using cutting-edge technologies, this research provides further intricate detail about the cells that make up specialised regions of the human heart and how those cells communicate with each other. The new findings on the heart's electrical conduction system and its regulation are likely to open up new approaches to preventing and treating rhythm disturbances that can impair the heart's function and may even become life-threatening."

"International collaboration is key to scientific progress. This impactful study and other discoveries from the broader Human Cell Atlas initiative are excellent examples of what can be achieved when the international research community works together across borders. Our combined efforts can ultimately produce better outcomes for patients worldwide."

Read more at Science Daily

Satellite security lags decades behind the state of the art

Thousands of satellites are currently orbiting the Earth, and there will be many more in the future. Researchers from Ruhr University Bochum and the CISPA Helmholtz Center for Information Security in Saarbrücken have assessed the security of these systems from an IT perspective. They analysed three current low-earth orbit satellites and found that, from a technical point of view, hardly any modern security concepts were implemented. Various security mechanisms that are standard in modern mobile phones and laptops were not to be found: for example, there was no separation of code and data. Interviews with satellite developers also revealed that the industry relies primarily on security through obscurity.

The results were presented by a team headed by Johannes Willbold, a PhD student from Bochum, Dr. Ali Abbasi, a researcher from Saarbrücken, and Professor Thorsten Holz, formerly in Bochum, now in Saarbrücken, at the IEEE Symposium on Security and Privacy, which took place in San Francisco from 22 to 25 May 2023. The paper was awarded a Distinguished Paper Award at the conference.

Research satellites and commercial satellite put to the test

The examined satellites were two small models and one medium-sized model -- research satellites as well as a satellite of a commercial company -- which orbit the Earth at a short distance and are used to observe the Earth. Gaining access to satellites and their software was a challenge for the team, as commercial providers in particular rarely wish to reveal any details. The researchers eventually gained access through cooperation with the European Space Agency (ESA), various universities involved in the construction of satellites, and a commercial enterprise.

The team from Bochum and Saarbrücken conducted a thorough security analysis of the three models. They looked in detail at what the software running on the devices does and which communication protocols are used. They emulated the systems, i.e., rebuilt them virtually, so that they could test the software as if it were in a real satellite. "It was a very different world from the systems we usually study. For example, completely different communication protocols were used," as Thorsten Holz outlines the process.

Systems with specific requirements

Satellites orbiting the Earth can only be reached by their ground station on Earth within a time window of a few minutes. The systems must be robust against the radiation in space, and, since they can only consume a small amount of energy, they have a low power output. "The data rates are like those of modems in the 1990s," as Holz elaborates the challenges satellite developers face.

Based on the findings gained from the software analysis, the researchers worked out various attack scenarios. They showed that they could cut off the satellites from ground control and seize control of the systems, for example in order to take pictures with the satellite camera. "We were surprised that the technical security level is so low," points out Thorsten Holz, adding the following caveat with regard to potential ramifications: "It wouldn't be all that easy to steer the satellite to another location, for example, to crash it or have it collide with other objects."

Survey among developers

To find out how the people who develop and build satellites approach security, the research team compiled a questionnaire and submitted it to research institutions, the ESA, the German Aerospace Centre and various enterprises. Nineteen developers participated anonymously in the survey. "The results show us that the understanding of security in the industry is different than in many other areas, specifically that it's security by obscurity," concludes Johannes Willbold. Many of the respondents therefore assumed that satellites could not be attacked because there is no documentation of the systems, i.e., nothing is known about them. Only a few said that they encrypt data when communicating with satellites or use authentication in order to ensure that only the ground station is allowed to communicate with the satellite.

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Widespread illegal trade of hazardous chemicals

54 chemicals and groups of chemicals are covered by the Rotterdam Convention due to their high potential to cause severe harm on human health and the environment. These include mercury compounds, various pesticides and five of the six types of asbestos. The Convention, also known as the PIC Convention (Prior Informed Consent), does not ban these hazardous substances. However, the parties may only trade them among themselves if the importing country has expressly consented to the import.

The PIC procedure is primarily intended to protect developing countries from the uncontrolled import of highly hazardous chemicals, since these countries often lack the necessary infrastructure to safely process and dispose of them. Now, a new study initiated by Empa scientists delivers sobering results: The PIC procedure is defaulted on in nearly half of the traded volume of these chemicals.

Worldwide violations

For the study, published on 10 July in the journal Nature Sustainability, researchers from China and Switzerland analyzed public trade data from the United Nations Comtrade database for 46 of the 54 listed chemicals. A total of 64.5 million tons were traded globally from 2004 to 2019. Of these, 27.5 million tons were traded illegally, i.e., exported to countries that had explicitly refused to import them.

Non-compliance with the Rotterdam Convention is a worldwide phenomenon, especially by many countries in Western, Central and Southern Europe, as well as South and Southeast Asia. At the same time, these regions were also the most affected by illegal imports, along with the Middle East and North Africa, as well as Latin America. "This prevalent illegal trade is highly concerning because it undermines global efforts to protect us and our environment from hazardous chemicals," says Empa researcher Zhanyun Wang, who initiated the study.

According to Wang and his co-authors, the result of the study is a rather conservative estimate of the illicit trade in hazardous chemicals, as situations such as smuggling and black markets were not includes in the analysis. In addition, the US, for example, exported about four million tons of chemicals to countries that refuse to import them under the Convention. However, this is not necessarily illegal -- because the US has not ratified the Rotterdam Convention and is subject to different rules.

Ongoing large-scale trade

Wang also considers the very high overall volume of hazardous substances being traded as problematic. Of the total 64.5 million tons, the majority -- 55.3 million tons -- is ethylene dichloride, a carcinogenic and organ-damaging solvent used in the production of polyvinyl chloride (PVC). In second place, with 6.3 million tons, is the toxic reagent, disinfectant and pesticide ethylene dioxide.

The other chemicals, which are predominantly pesticides, make up a relatively small portion of the total. "But we see that these highly toxic compounds are still being traded in significant quantities," Wang says. "Since the Rotterdam Convention came into force, trade has decreased only slightly. Yet for many of these substances, we've known for decades how harmful they are."

Surprisingly, the authors also discovered a brisk trade in some substances that have been severely restricted or even banned for years to decades. These include, for instance, the legacy toxic pesticides aldrin, chlordane, heptachlor and dieldrin, which have been banned worldwide as the "Dirty Dozen" under the Stockholm Convention since 2004. Also still traded, albeit in much smaller quantities of several thousand tons, are the notoriously neurotoxic compounds tetraethyl lead and tetramethyl lead. Despite decades of global efforts to phase them out in gasoline for normal cars, they seem to be still used in certain specialty fuels.

Strengthening national and international action

All of the data used in the study are public -- so why aren't the countries addressing the defaults? There are several reasons. "For many countries, the environmental ministry is responsible for implementing the Rotterdam Convention," Wang explains. "But trade is supervised by the customs authority." In addition, there are often insufficient resources available to monitor chemical trade, especially in developing countries.

The researchers recommend that international and national action needs to step up to address global trade of highly hazardous chemicals, particularly illegal trade. Among others, other problematic chemicals should be listed under the Convention, such as chrysotile asbestos. This type of asbestos is by far the most common -- and the only one of the six types of asbestos not yet covered by the Convention. "Switzerland has recently taken the initiative here to bring about changes, along with several other countries, but so far without success," Wang says.

The Rotterdam Convention, meanwhile, has only had a Compliance Committee to monitor and address its implementation since 2020. "We are hopeful that this, together with national efforts on reducing the production and use of highly hazardous chemicals, will greatly reduce illegal trade in the future," Wang says.

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