Phys.org - News and Artic Australia
Humans and climate drove giants of Madagascar to extinction - Phys.org
Nearly all Madagascan megafauna—including the famous dodo bird, gorilla-sized lemurs, giant tortoises, and the Elephant Bird, which stood 3 meters tall and weighted close to a half ton—vanished between 1,500 and 500 years ago. Were these animals overhunted to…
Nearly all Madagascan megafaunaincluding the famous dodo bird, gorilla-sized lemurs, giant tortoises, and the Elephant Bird, which stood 3 meters tall and weighted close to a half tonvanished between 1,500 and 500 years ago. Were these animals overhunted to extinction by humans? Or did they disappear because of climate change? There are numerous hypotheses, but the exact cause of this megafauna crash remains elusive and hotly debated. The Mascarene islands east of Madagascar are of special interest because they are among the last islands on Earth to be colonized by humans. Intriguingly, the islands' megafauna crashed in just a couple of centuries following human settlement. In a recent study published by Science Advances, a team of international researchers found that it was likely a "double whammy" of heightened human activities in combination with a particularly severe spell of region-wide aridity that may have doomed the megafauna. The researchers rule out climate change as the one and only cause, and instead suggest that the impact of human colonization was a crucial contributor to the megafaunal collapse. Hanying Li, a postdoctoral scholar at the Xi'an Jiaotong University in China and the lead author of this study, pieced together a detailed history of the regional climate variations. The primary source of this new paleoclimate record came from the tiny Mascarene island of Rodrigues in the southwest Indian Ocean approximately 1600 km east of Madagascar. "[It is] an island so remote and small that one will not find it on most schoolbook atlases," says Gayatri Kathayat, one of the co-authors and an associate professor of climate science at Xi'an Jiaotong University. Analysis of Cave Deposits Li and colleagues built their climate records by analyzing the trace elements and carbon and oxygen isotopes from each incremental growth layer of stalagmites, which they collected from one of the many caves on this island. The bulk of these analyses were conducted at the Quaternary Research Group at the Institute of Geology at the University of Innsbruck, led by Prof. Christoph Spötl. Variations in the geochemical signatures provided the information needed to reconstruct the region's rainfall patterns over the last 8000 years. To analyze the stalagmites, the researchers used the stable isotope method in their lab in Innsbruck. Despite the distance between the two islands, the summer rainfall at Rodrigues and Madagascar is influenced by the same global-wide tropical rain belt that oscillates north and south with the seasons. Hai Cheng, the study's senior co-author, says, "And when this belt falters and stays further north of Rodrigues, droughts can strike the whole region from Madagascar to Rodrigues." Co-author Hubert Vonhof, scientist at Max Planck Institute of Chemistry in Mainz, Germany, says, "Li's work from Rodrigues demonstrates that the hydroclimate of the region experienced a series of drying trends throughout the last eight millennia, which were frequently punctuated by 'megadroughts' that lasted for decades." Resilient to climate stress The most recent of the drying trends in the region commenced around 1,500 years ago at a time when the archeological and proxy records began to show definitive signs of increased human presence on the island. Ashish Sinha, professor of Earth science at California State University Dominguez Hills, U.S., says, "While we cannot say with 100 percent certainty whether human activity, such as overhunting or habitat destruction, was the proverbial straw that broke the camel's back, our paleoclimate records make a strong case that the megafauna had survived through all the previous episodes of even greater aridity. This resilience to past climate swings suggests that an additional stressor contributed to the elimination of the region's megafauna." "There are still many pieces missing to fully solve the riddle of megafauna collapse. This study now provides an important multi-millennial climatic context to megafaunal extinction," says Ny Rivao Voarintsoa from KU Leuven in Belgium. The study sheds new light on the decimation of flora and fauna of Mauritius and Rodrigues: "Both islands were rapidly stripped of endemic species of vertebrates within two centuries of the initial human colonization, including the well-known flightless dodo bird from Mauritius and the saddle-backed Rodrigues giant tortoise endemic to Rodrigues," adds Aurele Anquetil André, the reserve manager and chief conservator at the Francois Leguat Giant Tortoise and Cave Reserve at Rodrigues. "The story our data tells is one of resilience and adaptability of the islands' ecosystems and fauna in enduring past episodes of severe climate swings for eonsuntil they were hit by human activities and climate change," the researchers conclude. More information: Hanying Li et al. A multimillennial climatic context for the megafaunal extinctions in Madagascar and Mascarene Islands, Science Advances (2020). DOI: 10.1126/sciadv.abb2459 Citation: Humans and climate drove giants of Madagascar to extinction (2020, October 19) retrieved 19 October 2020 from https://phys.org/news/2020-10-humans-climate-drove-giants-madagascar.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
Einstein's description of gravity just got much harder to beat - Phys.org
Einstein's theory of general relativity—the idea that gravity is matter warping spacetime—has withstood over 100 years of scrutiny and testing, including the newest test from the Event Horizon Telescope collaboration, published today in the latest issue of Ph…
Einstein's theory of general relativitythe idea that gravity is matter warping spacetimehas withstood over 100 years of scrutiny and testing, including the newest test from the Event Horizon Telescope collaboration, published today in the latest issue of Physical Review Letters. According to the findings, Einstein's theory just got 500 times harder to beat. Despite its successes, Einstein's robust theory remains mathematically irreconcilable with quantum mechanics, the scientific understanding of the subatomic world. Testing general relativity is important because the ultimate theory of the universe must encompass both gravity and quantum mechanics. "We expect a complete theory of gravity to be different from general relativity, but there are many ways one can modify it. We found that whatever the correct theory is, it can't be significantly different from general relativity when it comes to black holes. We really squeezed down the space of possible modifications," said UArizona astrophysics professor Dimitrios Psaltis, who until recently was the project scientist of the Event Horizon Telescope collaboration. Psaltis is lead author of a new paper that details the researchers' findings. "This is a brand-new way to test general relativity using supermassive black holes," said Keiichi Asada, an EHT science council member and an expert on radio observations of black holes for Academia Sinica Institute of Astronomy and Astrophysics. To perform the test, the team used the first image ever taken of the supermassive black hole at the center of nearby galaxy M87 obtained with the EHT last year. The first results had shown that the size of the black-hole shadow was consistent with the size predicted by general relativity. "At that time, we were not able to ask the opposite question: How different can a gravity theory be from general relativity and still be consistent with the shadow size?" said UArizona Steward Theory Fellow Pierre Christian. "We wondered if there was anything we could do with these observations in order to cull some of the alternatives." The team did a very broad analysis of many modifications to the theory of general relativity to identify the unique characteristic of a theory of gravity that determines the size of a black hole shadow. "In this way, we can now pinpoint whether some alternative to general relativity is in agreement with the Event Horizon Telescope observations, without worrying about any other details," said Lia Medeiros, a postdoctoral fellow at the Institute for Advanced Study who has been part of the EHT collaboration since her time as a UArizona graduate student. The team focused on the range of alternatives that had passed all the previous tests in the solar system. "Using the gauge we developed, we showed that the measured size of the black hole shadow in M87 tightens the wiggle room for modifications to Einstein's theory of general relativity by almost a factor of 500, compared to previous tests in the solar system," said UArizona astrophysics professor Feryal Özel, a senior member of the EHT collaboration. "Many ways to modify general relativity fail at this new and tighter black hole shadow test." "Black hole images provide a completely new angle for testing Einstein's theory of general relativity," said Michael Kramer, director of the Max Planck Institute for Radio Astronomy and EHT collaboration member. "Together with gravitational wave observations, this marks the beginning of a new era in black hole astrophysics," Psaltis said. Testing the theory of gravity is an ongoing quest: Are the general relativity predictions for various astrophysical objects good enough for astrophysicists to not worry about any potential differences or modifications to general relativity? "We always say general relativity passed all tests with flying colorsif I had a dime for every time I heard that," Özel said. "But it is true, when you do certain tests, you don't see that the results deviate from what general relativity predicts. What we're saying is that while all of that is correct, for the first time we have a different gauge by which we can do a test that's 500 times better, and that gauge is the shadow size of a black hole." Next, the EHT team expects higher fidelity images that will be captured by the expanded array of telescopes, which includes the Greenland Telescope, the 12-meter Telescope on Kitt Peak near Tucson, and the Northern Extended Millimeter Array Observatory in France. "When we obtain an image of the black hole at the center of our own galaxy, then we can constrain deviations from general relativity even further," Özel said. Will Einstein still be right, then? More information:Physical Review Letters (2020). dx.doi.org/10.1103/PhysRevLett.125.141104 Citation: Einstein's description of gravity just got much harder to beat (2020, October 1) retrieved 1 October 2020 from https://phys.org/news/2020-10-einstein-description-gravity-harder.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
Biggest fish in the sea are girls - Phys.org
A decade-long study of the iconic fish has found male whale sharks grow quickly, before plateauing at an average adult length of about eight or nine meters.
A decade-long study of the iconic fish has found male whale sharks grow quickly, before plateauing at an average adult length of about eight or nine meters. Female whale sharks grow more slowly but eventually overtake the males, reaching an average adult length of about 14 meters. Australian Institute of Marine Science fish biologist Dr. Mark Meekan, who led the research, said whale sharks have been reported up to 18 meters long. "That's absolutely hugeabout the size of a bendy bus on a city street," he said. "But even though they're big, they're growing very, very slowly. It's only about 20cm or 30cm a year." In conducting the research, scientists visited Western Australia's Ningaloo Reef for 11 seasons between 2009 and 2019. They tracked 54 whale sharks as they grewa feat made possible by a unique 'fingerprint' of spots on each whale shark that can be used to identify individual fish. AIMS marine scientist Dr. Brett Taylor said the team recorded more than 1000 whale shark measurements using stereo-video cameras. "It's basically two cameras set up on a frame that you push along when you're underwater," he said. "It works the same way our eyes doso you can calibrate the two video recordings and get a very accurate measurement of the shark." Dr Mark Meekan, corresponding author, speaks about his research on whale sharks. Credit: AIMS The study also included data from whale sharks in aquaria. Dr. Meekan said it is the first evidence that males and female whale sharks grow differently. For the females, there are huge advantages to being big, he said. "Only one pregnant whale shark had ever been found, and she had 300 young inside her," Dr. Meekan said. "That's a remarkable number, most sharks would only have somewhere between two and a dozen. "So these giant females are probably getting big because of the need to carry a whole lot of pups." Whale sharks are Western Australia's marine emblem, and swimming with the iconic fish at Ningaloo Reef boosts the local economy to the tune of $24 million a year. But they were listed as endangered in 2016. Dr. Meekan said the discovery has huge implications for conservation, with whale sharks threatened by targeted fishing and ships strikes. "If you're a very slow-growing animal and it takes you 30 years or more to get to maturity, the chances of disaster striking before you get a chance to breed is probably quite high," he said. "And that's a real worry for whale sharks." Dr. Meekan said the finding also explains why gatherings of whale sharks in tropical regions are made up almost entirely of young males. "They gather to exploit an abundance of food so they can maintain their fast growth rates," he said. Dr. Taylor said learning that whale sharks plateau in their growth goes against everything scientists previously thought. "This paper has really re-written what we know about whale shark growth," he said. More information: Mark G. Meekan et al, Asymptotic Growth of Whale Sharks Suggests Sex-Specific Life-History Strategies, Frontiers in Marine Science (2020). DOI: 10.3389/fmars.2020.575683 Citation: Biggest fish in the sea are girls (2020, September 16) retrieved 16 September 2020 from https://phys.org/news/2020-09-biggest-fish-sea-girls.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
Why rats would win 'Australian Survivor' - Phys.org
Australian rodents skulls all correspond to one simple, size-dependent shape that is more than ten million years old but it turns out this lack of change is the secret behind their survivor reputation.
Australian rodents skulls all correspond to one simple, size-dependent shape that is more than ten million years old but it turns out this lack of change is the secret behind their survivor reputation. A new study, co-led by scientists from Flinders University and The University of Queensland, has revealed that the skulls of rodents resemble each other in any given size, meaning little adaptation seems to be necessary for a rodent to survive in a variety of habitats. Flinders University Associate Professor Vera Weisbecker, who supervised the study says everyone knows rodents all look similar, but researchers expected far more variety in the details of their skull shape when compared to what was found. "It seems intuitive that a group of animals that displays a wide variety of shapes should be more successful in evolution. However, Australian rodents demonstrate that shape diversity doesn't always mean evolutionary success. So it really does show if the skull ain't broke, don't fix it." Dr. Ariel Marcy, from The University of Queensland, says rodents first entered Australia around four million years ago, and quickly adapted to the diversity of habitats available on our continent. "Because well-adapted skulls are key to the survival of mammals, we expected to find a lot of locally adapted skull shapes." "What we found was the opposite of what we expected: there was low variation in the skull shape of rodents, and body size explained most of it." "Native rodents just scale from being a small 'mouse' shape to being a bigger 'rat' shape!" Dr. Marcy said. "And this relationship between skull shape and size is at least ten million years old, because invasive rodentslike the house mouse and Norway ratshare this pattern, too." To understand the patterns of adaptation they expected to see, the team scanned hundreds of rodent skulls of 38 species from museums using 3-D surface scanners, and analyzed their shape using a statistical procedure called geometric morphometrics. The researchers think this astonishing conservatism of shape may have to do with the very successful specialization of rodent jaws, allowing their skulls to be a true multi-purpose tool. "Rodent skulls and jaws have a complicated yet highly versatile arrangement that seems to work well in a multitude of conditions. We think that this discourages evolutionary change. We saw unusual skull shapes only in extreme cases of ecological adaptation, for example in the water mouse or rakali which is a very unusual meat-eating predatory rodent." Dr. Weisbecker notes that the results make an important point in one of the biggest questions in evolutionary biologywhy some groups of animals are more diverse than others. More information: Ariel Emily Marcy et al, Australian rodents reveal conserved Cranial Evolutionary Allometry across 10 million years of murid evolution, The American Naturalist (2020). DOI: 10.1086/711398 Citation: Why rats would win 'Australian Survivor' (2020, September 8) retrieved 8 September 2020 from https://phys.org/news/2020-09-rats-australian-survivor.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
Runaway star might explain black hole's disappearing act - Phys.org
At the center of a far-off galaxy, a black hole is slowly consuming a disk of gas that swirls around it like water circling a drain. As a steady trickle of gas is pulled into the gaping maw, ultrahot particles gather close to the black hole, above and below t…
At the center of a far-off galaxy, a black hole is slowly consuming a disk of gas that swirls around it like water circling a drain. As a steady trickle of gas is pulled into the gaping maw, ultrahot particles gather close to the black hole, above and below the disk, generating a brilliant X-ray glow that can be seen 300 million light-years away on Earth. These collections of ultrahot gas, called black hole coronas, have been known to exhibit noticeable changes in their luminosity, brightening or dimming by up to 100 times as a black hole feeds. But two years ago, astronomers watched in awe as X-rays from the black hole corona in a galaxy known as 1ES 1927+654 disappeared completely, fading by a factor of 10,000 in about 40 days. Almost immediately it began to rebound, and about 100 days later had become almost 20 times brighter than before the event. The X-ray light from a black hole corona is a direct byproduct of the black hole's feeding, so the disappearance of that light from 1ES 1927+654 likely means that its food supply had been cut off. In a new study in the Astrophysical Journal Letters, scientists hypothesize that a runaway star might have come too close to the black hole and been torn apart. If this was the case, fast-moving debris from the star could have crashed through part of the disk, briefly dispersing the gas. "We just don't normally see variations like this in accreting black holes," said Claudio Ricci, an assistant professor at Diego Portales University in Santiago, Chile, and lead author of the study. "It was so strange that at first we thought maybe there was something wrong with the data. When we saw it was real, it was very exciting. But we also had no idea what we were dealing with; no one we talked to had seen anything like this." Nearly every galaxy in the universe may host a supermassive black hole at its center, like the one in 1ES 1927+654, with masses millions or billions of times greater than our Sun. They grow by consuming the gas encircling them, otherwise known as an accretion disk. Because black holes don't emit or reflect light, they can't be seen directly, but the light from their coronas and accretion disks offers a way to learn about these dark objects. The authors' star hypothesis is also supported by the fact that a few months before the X-ray signal disappeared, observatories on Earth saw the disk brighten considerably in visible-light wavelengths (those that can be seen by the human eye). This might have resulted from the initial collision of the stellar debris with the disk. Digging Deeper The disappearing event in 1ES 1927+654 is unique not only because of the dramatic change in brightness, but also because of how thoroughly astronomers were able to study it. The visible-light flare prompted Ricci and his colleagues to request follow-up monitoring of the black hole using NASA's Neutron star Interior Composition Explorer (NICER), an X-ray telescope aboard the International Space Station. In total, NICER observed the system 265 times over 15 months. Additional X-ray monitoring was obtained with NASA's Neil Gehrels Swift Observatory which also observed the system in ultraviolet light as well as NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) and the ESA (the European Space Agency) XMM-Newton observatory (which has NASA involvement). When the X-ray light from the corona disappeared, NICER and Swift observed lower-energy X-rays from the system so that, collectively, these observatories provided a continuous stream of information throughout the event. Although a wayward star seems the most likely culprit, the authors note that there could be other explanations for the unprecedented event. One remarkable feature of the observations is that the overall drop in brightness wasn't a smooth transition: Day to day, the low-energy X-rays NICER detected showed dramatic variation, sometimes changing in brightness by a factor of 100 in as little as eight hours. In extreme cases, black hole coronas have been known to become 100 times brighter or dimmer, but on much longer timescales. Such rapid changes occurring continuously for months was extraordinary. "This dataset has a lot of puzzles in it," said Erin Kara, an assistant professor of physics at the Massachusetts Institute of Technology and a coauthor of the new study. "But that's exciting, because it means we're learning something new about the universe. We think the star hypothesis is a good one, but I also think we're going to be analyzing this event for a long time." It's possible that this kind of extreme variability is more common in black hole accretion disks than astronomers realize. Many operating and upcoming observatories are designed to search for short-term changes in cosmic phenomena, a practice known as "time domain astronomy," which could reveal more events like this one. "This new study is a great example of how flexibility in observation scheduling allows NASA and ESA missions to study objects that evolve relatively quickly and look for longer-term changes in their average behavior," said Michael Loewenstein, a coauthor of the study and an astrophysicist for the NICER mission at the University of Maryland College Park and NASA's Goddard Space Flight Center (GSFC) in Greenbelt, Maryland. "Will this feeding black hole return to the state it was in before the disruption event? Or has the system been fundamentally changed? We're continuing our observations to find out." More information: C. Ricci et al. The Destruction and Recreation of the X-Ray Corona in a Changing-look Active Galactic Nucleus, The Astrophysical Journal (2020). DOI: 10.3847/2041-8213/ab91a1 Citation: Runaway star might explain black hole's disappearing act (2020, July 17) retrieved 17 July 2020 from https://phys.org/news/2020-07-runaway-star-black-hole.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
New global study reveals 'time tree' of Earth's flowering plants - Phys.org
New research published today in Nature Ecology & Evolution by scientists from Australia and Mexico reveals the world's first complete angiosperm "time tree"—a reconstruction of the evolution of the Earth's flowering plants through time.
New research published today in Nature Ecology & Evolution by scientists from Australia and Mexico reveals the world's first complete angiosperm "time tree"a reconstruction of the evolution of the Earth's flowering plants through time. The rise of angiosperms (flowering plants) began about 140 million years ago, sparking one of the most dramatic biological revolutions of our planet's recent history. Crucial questions around the timing and location of the origin of the families involved in creating the most diverse type of plants on Earth were until now, largely unanswered. Dr. Hervé Sauquet from the Australian Institute of Botanical Science and Senior Visiting Fellow at the University of NSW is based at the Royal Botanic Garden Sydney and coordinated the dataset of 238 angiosperm fossil calibrations, the largest ever assembled. "Fossils are the most important pieces of evidence needed to understand these important evolutionary questions around angiosperm divergence times," said Dr. Sauquet. "Previous studies of this nature only used 30 to 60 fossil records and we wanted to increase this number significantly and set a higher standard for fossil calibration by documenting every part of the process. We often had to translate records from different languages and do relentless detective work to get centuries old as well as the latest fossil descriptions in our hands," Dr. Sauquet said. The researchers also analyzed the geographic distribution of existing flowering plants and looked at how angiosperm family ages were distributed across the globe by combining their new 'time tree' with over 16 million occurrence records of angiosperm species. Lead author of the study from the National Autonomous University of Mexico, Dr. Santiago Ramírez-Barahona, said we now have the most comprehensive confirmation to date that angiosperms originated in tropical environments. "But there is a twist, although tropical ecosystems are home to old families, our results imply that the angiosperm-dominated rainforests of today are a relatively recent development in Earth's history," Dr. Ramírez-Barahona said. "Every group of living species on Earth has a 'stem' age (the age of its origin) and a 'crown' age (the beginning of its diversification into the living species we see today) and birds provide a great example of this. The stem age of birds is marked by their split from crocodiles around 240 million years ago and their crown age is marked by the most recent common ancestor of all living birds, around 100 million years ago. What happened between the stem and crown ages is very interesting because this when the dinosaurs roamed the Earth. It's also when all the traits that define modern birds evolved and this is exactly what we set out to understand in our angiosperm study," said Dr. Ramírez-Barahona. Senior author from the National Autonomous University of Mexico, Professor Susana Magallón, said the study further supports the idea that the ecological dominance of modern-day flowering species was delayed until after the end of the dinosaurs, some 66 million years ago. "By estimating both the stem and crown ages for angiosperm families we found a difference of 37 to 56 million years between family origins and the beginning of their diversification into the living species we see today," said Professor Magallón. "To put this into context, the average time lag corresponds to around a third of the entire duration of angiosperm evolution, which is at least 140 million years." Dr. Sauquet said the new study sheds new light on crucial temporal and geographic aspects of the most critical phases of angiosperm evolution after their origin. "During this time is when flowering plants came to be the dominant and most important group of terrestrial plantsthe primary food source for most organisms on land and virtually all human agricultural crops," said Dr. Sauquet. The new research will also help contribute to the broader understanding of all evolution on Earth by adding another key piece to the puzzle of life. All scientific facilities, programs and living collections at the Royal Botanic Garden Sydney, Australian Botanic Garden Mount Annan and Blue Mountains Botanic Garden Mount Tomah have been united under the new Australian Institute of Botanical Science. The new Institute is advancing fundamental knowledge of flora and driving effective conservation solutions to ensure the survival of plants, and all life that depends on them. More information: Santiago Ramírez-Barahona et al. The delayed and geographically heterogeneous diversification of flowering plant families, Nature Ecology & Evolution (2020). DOI: 10.1038/s41559-020-1241-3 Citation: New global study reveals 'time tree' of Earth's flowering plants (2020, July 7) retrieved 7 July 2020 from https://phys.org/news/2020-07-global-reveals-tree-earth.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
Study reveals secret life of lithium in Sun-like stars - Phys.org
Lithium is becoming common in our everyday lives. It is the key ingredient in the batteries of our mobile phones and electric vehicles, but have you ever wondered where it comes from?
Lithium is becoming common in our everyday lives. It is the key ingredient in the batteries of our mobile phones and electric vehicles, but have you ever wondered where it comes from? A new study led by Prof. Zhao Gang and Dr. Yerra Bharat Kumar from National Astronomical Observatories of Chinese Academy of Sciences (NAOC) provides a fresh understanding of both how lithium is made, and how it is destroyed. The study was published in Nature Astronomy on July 6. Researchers studied the lithium content of hundreds of thousands of Sun-like stars to understand how this element changes over time in stars. "Lithium is quite a special element," said Dr. Yerra Bharat Kumar, first author of the study. "Our study challenges the idea that stars like the Sun only destroy lithium through their lives." "Our observations show that they actually create it later in their lives, after they have swelled to become red giants. This means that the Sun itself will also manufacture lithium in the future," he said. Lithium is one of the three elements produced in the Big Bang. It gets destroyed very easily inside stars where it is too hot for it to survive, so lithium content generally decreases as the stars age. Since lithium is such a sensitive element, it is very useful for understanding stars. It acts as a tracer for what is happening inside stars. To better understand this sensitive element, researchers used data from a huge Chinese stellar spectroscopic survey based on The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). The survey is currently building a database of the spectra of ten million stars. This study also utilized data from Australian star survey known as GALAH. "By looking at starlight, we can determine what the stars are made of," said Dr. Yerra Bharat Kumar. "Models show that our current theories about how stars evolve do not predict this lithium production at all. Thus, the study has created a tension between observations and theory." "Our findings will help us to better understand and model Sun-like stars," said Prof. Zhao Gang, the co-corresponding author of this study. "Since the newly created lithium will end up being blown off the star in stellar winds, it will also help us understand how these stars contribute to the lithium content of our Galaxy, and to planets like Earth," said Prof. Zhao. More information: Yerra Bharat Kumar et al, Discovery of ubiquitous lithium production in low-mass stars, Nature Astronomy (2020). DOI: 10.1038/s41550-020-1139-7 Citation: Study reveals secret life of lithium in Sun-like stars (2020, July 6) retrieved 6 July 2020 from https://phys.org/news/2020-07-reveals-secret-life-lithium-sun-like.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
A safe and powerful treatment for the body against deadly radiation - Phys.org
Despite the wide application of radiation in diagnostics and treatments, there is still no magic material to protect people from radiation exposure. Though Amifostine is developed as a radioprotectant, the FDA approved its application only for the protection …
Despite the wide application of radiation in diagnostics and treatments, there is still no magic material to protect people from radiation exposure. Though Amifostine is developed as a radioprotectant, the FDA approved its application only for the protection of salivary glands. Also it requires repetitive injections to be effective and it can pose severe health threats of systemic toxicity and complications when applied to those under total body irradiation conditions. Researchers at the Center for Nanoparticle Research, within the Institute for Basic Science (IBS, South Korea) in collaboration with their colleagues at Seoul National University, School of Dentistry and Dental Research Institute, have reported a highly effective and safe nanocrystal to combat dangerous doses of radiation. By growing manganese oxide (Mn3O4) nanocrystals on top of Cerium oxide (CeO2) nanocrystals, the research team boosted the catalytic activity of the CeO2/Mn3O4 nanocrystals in their ability to stave off side effects of deadly radiation. "Excessive reactive oxygen species (ROS) are found in a number of major diseases including sepsis, cancer, cardiovascular disease, and Parkinson's disease, just to name a few," says Hyeon Taeghwan, director of the IBS Center for Nanoparticle Research (Seoul National University Distinguished Professor). "A powerful antioxidant that can work at low doses only can ensure sustainable applications of radiation in medical, industrial and military settings and more. These new CeO2/Mn3O4 hetero-structured nanocrystals are five times stronger than when CeO2 or Mn3O4 does the job alone," notes Director Hyeon. When our body is exposed to high levels of radiation, a massive amount of ROS are generated within milliseconds due to the decomposition of water molecules. These ROS severely damage cells, eventually leading to their death. The research team looked to CeO2 and Mn3O4 nanoparticles for their outstanding ROS scavenging abilities. The challenge was how to apply these antioxidant nanomaterials in a safe and economic way. Though effective, CeO2 and Mn3O4 nanoparticles can remove ROS only in high doses. They are also rare materials and difficult to obtain. The researchers drew on the approach usually taken in the field of catalysis: stacking nanoparticles with different lattice parameters results in surface strain and increases oxygen vacancies on the surface of the nanocrystal. "The synergistic effect of the strain generated on Mn3O4 and the increased oxygen vacancy on the CeO2 surface improved the surface binding affinity of the ROS, boosting the catalytic activity of the nanocrystals," Han Sang Ihn, the first author of the study, explains. "Strain engineering of nanocrystals, mainly studied in the field of catalysts, has now been extended to the medical field to protect cells from ROS-related diseases," says Cho Min Gee, the co-first author of the study. The research team checked the safety, as well as effectiveness of these new antioxidant nanocrystals. Molecular dynamics are analyzed using acute radiation model of human intestinal organoids. "Organoids pretreated with the CeO2/Mn3O4 nanocrystals expressed more genes that were related to proliferation and maintenance of intestinal stem cells and fewer cell-death genes, compared with the no-pretreatment group," explains Sang-woo Lee, the first co-author of the study. In a mouse study, the CeO2/Mn3O4 nanocrystals significantly increased the survival rate of the animals to 67% with only a very small dose (1/360 of Amifostine injection dose) and decreased the oxidative stress to internal organs, circulation, and bone marrow cells, without any significant signs of toxicity "To ensure a safe and wide application of a radioprotectant in the clinic, the key is to maintain high catalytic efficacy in low doses. These CeO2/Mn3O4 nanocrystals prove their powerful antioxidant effects to protect our whole body effectively just in small doses," says Park Kyungpyo, professor at Department of Dentistry, Seoul National University. More information: Sang Ihn Han et al, Epitaxially Strained CeO2 /Mn3 O4 Nanocrystals as an Enhanced Antioxidant for Radioprotection, Advanced Materials (2020). DOI: 10.1002/adma.202001566 Citation: A safe and powerful treatment for the body against deadly radiation (2020, July 6) retrieved 6 July 2020 from https://phys.org/news/2020-07-safe-powerful-treatment-body-deadly.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
Pandemic will cause globe $US21 trillion in economic pain - Phys.Org
The global economy could lose up to U.S. $21.8 trillion dollars in 2020 alone due to COVID-19, according to new analysis from the Australian National University (ANU).
The global economy could lose up to U.S. $21.8 trillion dollars in 2020 alone due to COVID-19, according to new analysis from the Australian National University (ANU). The research, led by Professor Warwick McKibbin and Roshen Fernando, has modeled six new scenarios of the impact of the coronavirus on the world economy. The scenarios range from containing COVID-19 in mid-2020 to ongoing waves of the virus over several years. The researchers have also created an online dashboard to display their results. Professor McKibbin said even under the best case scenario the global economy will lose up to U.S. $14.7 trillion dollars. "That's a massive hit, and that loss is based on the worst of COVID-19 being over by mid-2020 but with a smaller second wave in 2021," he said. "Our modeling shows that if the virus isn't contained or if we have ongoing waves, the economic losses will climb quite steeply. The more waves we have the more losses we can expect. By our fourth scenario, which sees two waves of COVID-19 in 2020 and another two in 2021, the loss rises to U.S. $21.8 trillion. There is no doubt that COVID-19 is a significant negative shock to the world economy, and our modeling makes that clear." The researchers also modeled the total loss to the global economy between 2020 and 2025. Under these scenarios, the initial 2020 impact of COVID-19 has an ongoing "ripple effect" over five years due to sustained declines in economic activity. Under the worst case scenario, which sees four waves of the virus over two years but only lockdowns in the first year, total losses cumulative over five years for the world equal U.S. $35.3 trillion. At best, with COVID-19 largely contained by mid-2020, the cumulative five-year loss to the economy is U.S. $17.5 trillion. Co-author and Ph.D. researcher Roshen Fernando said Australia should also brace for a major economic hit. "Under our modeling, Russia, the U.S. and China will feel the biggest impact each losing U.S. $2.8, U.S. $2 and U.S. $1.9 trillion respectively. And that's under the best-case scenario of containing the virus by mid-2020," he said. "In comparison, under the same scenario Australia will lose U.S.$117 billion in 2020. And a worse-case scenario of four waves of COVID-19 over two years will see our economy lose U.S. $172 billion. Either way, those are massive losses for an economy and country the size of Australia." The modeling shows the cumulative losses to Australia's economy between 2020 and 2025 range from U.S. $151.6 billion to U.S. $306.6 billion. Professor McKibbin said the impact revealed by their modeling shows the world must work together to overcome the long-term damage of the crisis. "The current experience with the COVID-19 pandemic has revealed deep problems in existing institutions at the supernational level and within countries." Professor McKibbin said. "While policies need to be designed and implemented at the national level, for most foreseeable problems, there needs to be greater cooperation across countries. COVID-19 shows the folly of isolationist politics and policies when the natural world ignores artificial boundaries." The analysis is published online by the ANU Centre for Applied Macoeconomic Analysis. It also examines other key economic impacts of COVID-19 including the impact on government spending, wage subsidies and household transfers, country risk assessments and potential mortality and morbidity rates. More information: McKibbin et al. Global macroeconomic scenarios of the COVID-19 pandemic, (2020). cama.crawford.anu.edu.au/sites … ibbin_fernando_0.pdf Citation: Pandemic will cause globe $US21 trillion in economic pain (2020, June 25) retrieved 25 June 2020 from https://phys.org/news/2020-06-pandemic-globe-us21-trillion-economic.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
Preventing lithium loss for high-capacity lithium-ion batteries - Phys.org
A team of Korean researchers has developed a processing technology for maximizing energy densities of high-capacity batteries. The joint research team, which consists of Dr. Minah Lee and Dr. Jihyun Hong of the Clean Energy Institute, Korea Institute of Scien…
A team of Korean researchers has developed a processing technology for maximizing energy densities of high-capacity batteries. The joint research team, which consists of Dr. Minah Lee and Dr. Jihyun Hong of the Clean Energy Institute, Korea Institute of Science and Technology (KIST), have announced the development of a technology that provides a simple solution to a persistent issue associated with silicon-based anode (-) materials. Recently, silicon anode materials capable of storing four times more lithium ions than graphite anode materials in lithium-ion batteries have gained growing attention due to their potential to improve the mileage of electric vehicles. But when charged in the initial cycle, a battery with a silicon-based anode loses more than 20% of the lithium ions it uses for electricity storage, which results in an issue of reduced battery capacity. To resolve this issue, researchers have studied a method of lithium pre-loading, or pre-lithiation, which is adding extra lithium before battery assembly to compensate the lithium loss during battery cycling. Methods applied so far, such as using lithium powder, have drawbacks including safety hazards and high cost. Dr. Lee and Dr. Hong of KIST have developed a technology that enables the pre-loading of lithium ions using a lithium-containing solution rather than lithium powder, preventing lithium loss in a silicon-based anode. Submerging an electrode in the tailored solution for just five minutes is enough to achieve successful lithium pre-loading, by which electrons and lithium ions are inserted in the silicon-based anode through a spontaneous chemical reaction. Unlike the conventional method of adding lithium powder to an electrode leading to heterogeneous lithium distribution, the tailored prelithiation solution rapidly seeps into an electrode, ensuring homogeneous delivery of lithium into silicon oxide. The prelithiated silicon-based anode developed by the research team loses less than 1% of active lithium in the first charge, yielding a high initial battery efficiency of 99% or higher. A battery manufactured with the prelithated anode exhibited an energy density 25% higher than that of a comparable battery using a graphite anode available on the market (406 Wh/kg504 Wh/kg). Dr. Lee, who headed the research, said, "By incorporating a computational materials science technique into the design of an optimal molecular structure, we were able to improve the efficiency of a high-capacity, silicon-based anode by leaps and bounds with the simple method of just controlling the solution temperature and reaction time. As this technology is readily applicable to the roll-to-roll process used in existing battery manufacturing facilities, our method has potential to achieve a breakthrough in the implementation of silicon-based anodes for practical batteries." Co-lead researcher Dr. Hong said, "This collaborative work could be realized because KIST encourages joint research between members from different research teams. This prelithation technology can increase the mileage of electric vehicles by a minimum of 100 km on average." More information: Juyoung Jang et al, Molecularly Tailored LithiumArene Complex Enables Chemical Prelithiation of HighCapacity LithiumIon Battery Anodes, Angewandte Chemie International Edition (2020). DOI: 10.1002/anie.202002411 Provided by National Research Council of Science & Technology Citation: Preventing lithium loss for high-capacity lithium-ion batteries (2020, June 22) retrieved 22 June 2020 from https://phys.org/news/2020-06-lithium-loss-high-capacity-lithium-ion-batteries.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.