For most of the last century, T. rex was pictured as a sluggish, tail-dragging reptile that had to warm up in the sun before it could go anywhere. Then, further research changed that view, replacing it with the active, bird-like animal shown in the movie Jurassic Park. But whether T. rex used warm blood to power that activity remained a question. Now we might have gotten closer to an answer.

A team of researchers led by Randon J. Flores and Robert A. Eagle, geochemists at the University of California, Los Angeles, has measured the T. rex body temperature by analyzing its teeth. This dental thermometer read about 36° Celsius—roughly the body temperature of a modern elephant.

Dental thermometry

Paleontologists have long argued about dinosaur physiology based on indirect evidence like bone microstructure, growth rates, and where fossils turn up on the map. Some studies suggested many dinosaurs were endotherms, generating their own body heat like birds and mammals. Others argued that each lineage may have had its own thermal strategy.

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Learning another language is a highly complex mental activity. It requires people to remember words, distinguish unfamiliar sounds, recognize patterns, work out grammatical rules, and retrieve the right expression at the right moment. All of this happens while listening, interpreting, and preparing a response.

Could all this mental activity also help keep an aging brain healthier? Research suggests it can.

Concerns about memory and dementia can send aging adults looking for ways to exercise their brain and maintain cognitive function, whether it is solving crossword puzzles or playing a musical instrument. Language learning might not seem like the same kind of brain exercise, but it is a complex activity that engages several mental processes at once.

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For decades, astronomers thought rings were something only giant planets had. That changed in 2013, when a small, dark body orbiting between Saturn and Uranus passed in front of a star and blinked twice on either side of the main event, revealing two narrow rings around an object barely 250 kilometers across. “It was a surprise,” says Pablo Santos-Sanz, an astronomer at the Instituto de Astrofísica de Andalucía in Granada, Spain. Ever since, the question has been what such rings are made of and how long they can last.

In a recent study, Santos-Sanz and his colleagues used the James Webb Space Telescope to watch the same body, now known as Chariklo, pass in front of a background star again. They found one of its rings had grown denser and the other had almost vanished. We don’t know exactly why.

Shadowing a star

The technique behind the observation is simple. “We predict when a Solar System object passes in front of a star,” Santos-Sanz said. The starlight dims for a moment, and the shape of that dip reveals the size, shape, and surroundings of the object that caused it. “This is particularly challenging for minor bodies, and more challenging for distant minor bodies,” he said.

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For a long time, sleep research has treated the cerebral cortex as a passive follower reacting to signals from the deep brain. “Usually, sleep is associated with being controlled by subcortical regions,” said Geoffrey Terral, a neuroscientist at the Albert Einstein College of Medicine in New York.

The cortex is where the slow rhythms of deep sleep can be seen, but researchers assumed the signals that triggered them originated elsewhere. In a recent Nature study, Terral and Renata Batista-Brito, who runs the lab, report a population of cortical cells that challenges that assumption.

These cortical cells make up only around one percent of the cortex's inhibitory neurons, and switching them on in a mouse puts the animal to sleep. “What our work shows is that the cortex can not only see this rhythm but also initiate it by itself, and this is sufficient to promote sleep,” Terral said.

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A Chinese optical engineer is the winner of this year's Small World in Motion competition, sponsored by Nikon. Ning Xu of Tsinghua University in Beijing beat out 346 other video entries from 40 different countries with his super-resolution video (above) of the abnormal beating of cilia in the airways of a child with a rare genetic respiratory disorder.

Founded in 2011, the Nikon Small World in Motion competition is a spinoff of the company's Small World Photomicrography Competition, which has been around since 1974. Both are meant "to showcase the beauty and complexity of things seen through the light microscope"—one through still photographs, the other through photovideography, taking advantage of all the technological advances that now allow users to make movies or time-lapse images through the microscope.

Primary ciliary dyskinesia (PCD) is a genetic disorder that adversely affects the tiny hairlike structures that line the lungs, among other areas. Their wavelike motion helps move around germs, mucus, dust, and other irritants so the body can dispel them via coughing or sneezing. In people born with PCD, there is something wrong with those cilia, so those irritants build up, causing respiratory infections, among other complications. The cilia might be the wrong size, the wrong shape, or missing altogether. They might move abnormally or not move at all.

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Days after finalizing a rule that would eliminate climate rules for power plants, the Environmental Protection Agency (EPA) was sued by groups who say the EPA’s repeal was shockingly short-sighted and risked leaving the country’s single largest source of industrial climate pollution unchecked.

On Thursday, the American Lung Association, the American Public Health Association (APHA), the Clean Air Council, Clean Wisconsin, the Environmental Defense Fund, and the Natural Resources Defense Council (NRDC) filed a petition requesting that the US Court of Appeals for the DC Circuit review if the EPA’s action conflicts with the Clean Air Act.

“Clean air is a basic human right,” APHA CEO Georges C. Benjamin said.

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Staff at the Lady Elliott Island Eco Resort off the southern Great Barrier Reef in Australia are well acquainted with the shenanigans of a male bottlenose dolphin they've nicknamed Bubbles. Bubbles has been around since at least 2017 and regularly harasses local bigeye trevally, chasing a fish around and stressing it so much that the fish throws up what it has consumed. Bubbles then devours the regurgitated food. The dolphin's unusual behavior is the focus of a new paper published in the journal Ecology and Evolution.

If you're thinking that Bubbles sounds like kind of a jerk and Flipper would never behave like this, think again. "This perception of dolphins as the ‘good guys of the sea’ has more to do with anthropomorphism—our tendency to assign human characteristics to them—and perhaps that’s because dolphins appear to be smiling," said co-author Asia Haines of the University of the Sunshine Coast. "Dolphins are predators and actively hunt their prey, whether it has been stolen from another species or not.”

The technical term is kleptoparasitism, and it usually involves one species taking food away from another, often via aggressive confrontation. Bees and wasps are common culprits, such as the cuckoo wasp, which lays its eggs in the nests of other wasp species. The behavior is often opportunistic across many species, including bears, coyotes, and wolves. Raptors, gulls, terns, and bald eagles have been known to attack other birds and take their food. Skuas and frigatebirds steal from other seabirds; masked shrikes steal food from wheatears; and Eurasian blackbirds have been seen stealing smashed snails from thrushes. Hyenas and jackals steal food all the time.

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The International Meteor Organization, the nonprofit that coordinates and publishes amateur and professional observations of meteor phenomena, said its infrastructure has suffered a “critical blow” from a cyberattack.

“We recently suffered a cyberattack that dealt a critical blow to aging infrastructure, taking much of our site offline," a static page on its website on Wednesday said. “We expect several weeks of partial downtime as we transition to new infrastructure and services.”

“I am very sad to see the site down”

In the meantime, the IMO said it’s prioritizing the reporting of fireball observations, which can be reported here. The organization is also providing some information on its Facebook page.

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In recent years, there has been a lot of excitement about the potential for studying human diseases in what are called "organoids." These small patches of tissue, formed using stem cells, appear to produce many of the same cell types and at least some of the structures normally formed in actual organs, and thus can provide a better model for diseases that rely on the sometimes complex interactions among multiple specialized cell types that are a feature of the human body.

But even the most sophisticated organoids lack a lot of the features of a real human body. This is especially true for brain organoids, which don't form any of the connections with specialized brain structures needed to behave "normally." On Wednesday, a research group at Stanford University described a possible way to study brain organoids in a somewhat more natural context: They genetically wiped out a large portion of the mouse brain and replaced it with human brain organoid cells.

The replacements

Organoids, because they adopt a three-dimensional tissue structure and consist of various specialized cells, provide a much better model for an intact tissue than simply having a bunch of disassociated cells lying flat on a culture dish. But they still have a lot of limitations—they're not hooked up to a circulatory system that allows the liver to process chemicals the organoid produces and don't have immune cells moving through them, to give just a couple of examples.

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The Vesuvius Challenge is an ongoing project that combines "digital unwrapping" with crowdsourced machine learning to decipher the so-called Herculaneum scrolls, badly charred 2,000-year-old papyri too fragile to be physically unrolled. The effort just got an additional boost. A team of researchers created their own contemporary model papyrus scrolls—charring them just like the originals—to validate a screening method to determine which of the Herculaneum scrolls were written in lead-based ink and hence are the most promising candidates for further analysis. They described the process in a new paper published in the journal PLoS ONE.

As previously reported, the ancient Roman resort town of Pompeii wasn’t the only city destroyed in the catastrophic 79 AD eruption of Mount Vesuvius. Several other cities in the area, including the wealthy enclave of Herculaneum, were fried by clouds of hot gas, called pyroclastic pulses and flows. But still, some remnants of Roman wealth survived. One palatial residence in Herculaneum—believed to have once belonged to a man named Piso—contained hundreds of priceless written scrolls made from papyrus, singed into carbon by volcanic gas.

The scrolls stayed buried under volcanic mud until they were excavated in the 1700s from a single room that archaeologists believe held the personal working library of an Epicurean philosopher named Philodemus. The few opened fragments helped scholars identify various Greek philosophical texts, including On Nature by Epicurus and several by Philodemus himself, as well as a handful of Latin works. But the more than 600 rolled-up scrolls were so fragile that it was long believed they would never be readable, since even touching them could cause them to crumble.

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Our basic understanding of core-collapse supernovae hasn't changed in decades. Large stars burn through all the fuel at their cores and start creating heavier elements in reactions that consume energy. The lack of energy from these reactions allows gravity to pull the interior of the star in on itself, collapsing it into a neutron star or black hole. The energy released by this process then blows the remainder of the star apart.

And, generally, that's right. But there's an entire busload of devils in the details. The statistics of supernovae that we've observed indicate that the model may be seriously incomplete. And on the theoretical side, there are still plenty of uncertainties, including over some of the basics, such as whether all core collapses actually result in a supernova.

A paper being released by Physical Review D provides what might be a potential explanation for the discrepancy: flavor-changing neutrinos. Neutrinos play a key role in our current models of supernovae, and right now, those models don't take into account one of neutrinos' most striking features: their ability to change identity.

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Chimpanzees are known to use rudimentary tools when foraging for food. According to a new paper in the journal Frontiers in Psychology, this learned behavior is passed down from adults to offspring through social learning. Specifically, adult chimps deliberately model the behavior, then turn their tools over to the youngsters so they can mimic the same motions.

"Receiving food and tools from experienced individuals, which we call food or tool transfer, may help chimpanzees learn to use technology to extract foods that are difficult to access,” said co-author Andreu Sánchez-Megías, a graduate student at the University of Barcelona and the Jane Goodall Institute Spain in Senegal. “Tool transfers thus appear to be a form of teaching, together with observation and supervised practice. It appears that mothers are the main models and teachers for young chimpanzees in this manner.”

As we have previously reported, tool use was once thought to be one of the defining features of humans, although Charles Darwin observed chimpanzees using stones to crack nuts in 1871. In 1960, the late primatologist Jane Goodall observed a chimp named David Greybeard bend a twig, strip off the leaves, and use it to spoon termites out of a nest and into his mouth. When he learned of the behavior, Goodall's mentor, Louis Leakey, famously observed, “Now we must redefine ‘tool,’ redefine ‘man,’ or accept chimpanzees as humans.” Since then, chimps have been observed making sponges out of leaves to soak up liquids, shaping sticks to collect algae, and sharpening rudimentary spears for hunting.

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On the heels of the hottest summer on record and a United Nations report warning that global temperatures are likely to push climate risks to “increasingly dangerous heights,” the Trump administration overturned most of a Biden-era rule limiting climate pollution from power plants, the second-largest source of greenhouse gas emissions.

The Environmental Protection Agency announced a final plan Monday that guts the 2024 Carbon Pollution Standards, which the agency said exceeds its authority under the Clean Air Act by requiring control technologies “that are not adequately demonstrated.” The agency also proposed revoking “all remaining GHG emissions requirements for power plants,” arguing their emissions “have no material impact on climate change.”

The plan to revoke the Carbon Pollution Standards was initially revealed last spring.

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Last week, the Atlantic hurricane season blew through its traditional peak—which comes around September 10—with nary a tropical wave in sight, let alone a storm or hurricane.

This is remarkable. Usually this is the time of year when sea surface temperatures reach their warmest in the tropics, and with a favorable atmosphere it should be smooth skating for tropical systems. But this year, the main region where most tropical systems develop is choked with Saharan dust and wind shear.

No one is complaining. Landfalling hurricanes are incredibly destructive for coastal areas and have the potential for considerable inland rainfall. Even storms at sea, in the Gulf of Mexico, can send energy prices skyrocketing—the last thing needed this year.

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Air Force Secretary Troy Meink made the first public declaration Monday that the United States has placed "space control weapons" in orbit, an announcement that will surely reverberate in the power centers of Beijing and Moscow.

Space Force officials have previously expressed their interest in acquiring space-based weapons, and Pentagon leaders have become more open to discussing space warfare in recent years. Therefore, Meink's announcement Monday at the Air and Space Forces Association's annual Air, Space & Cyber Conference near Washington, DC, was not entirely unexpected.

“Today, we continue to ensure we remain ready to meet the challenges of evolving threats, wherever they exist. This is why the United States now has on-orbit space control weapons capable of defending the joint force against hostile adversary action,” Meink said in prepared remarks.

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In one episode of the Hanna-Barbera cartoon Birdman, the eponymous hero struggles to fight the evil Dr. Shark aboard a submarine without solar energy to recharge his powers. So Birdman would surely appreciate the new perovskite solar cells developed by a team led by Simin Ma at Yunnan University, since they are designed to work underwater.

Solar cells made from perovskites rather than silicon are always a tale of trade-offs. They can be made cheaply, they can take interesting forms (like thin, flexible, transparent films), and they can convert substantially more of the incoming solar energy into electricity. The difficulty is that they tend to degrade quite quickly.

Tuned for the deep

Moisture is particularly destructive to perovskites, making them a seemingly odd choice for an underwater solar panel. But these materials have another critical superpower: They can be tuned to work with different wavelengths of light. Water quickly blocks the wavelengths of light that silicon solar panels absorb, but a carefully designed perovskite cell could still make electricity in the deep blue sea. And actually, the lower light levels and cooler temperatures should help it live longer.

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Stonehenge is the most famous example of megalithic architecture across Britain and Ireland, but there are plenty of others, including Calanais, Newgrange, and Avebury, as well as the Devil's Arrows. The latter is Britain's tallest standing stone alignment, yet little is known about the provenance of its stones. Scientists have confirmed that the stones came from a site 18 kilometers (11 miles) away, transported by humans rather than glacial movement, according to a paper published in the Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences.

"Sites in southern England and Scotland receive considerable attention but monuments like the Devil's Arrows have remained comparatively understudied despite their significance," said co-author Jim Leary of the University of York. "We have now proved that Neolithic communities moved several 25-ton stones across Yorkshire, transforming a familiar site into an epic quest to create a sacred landscape."

Stonehenge has been the focus of recent chemical analyses identifying where all the stones that make up the structure came from, revealing that many originated in quarries a significant distance away. For instance, a 2019 study concluded that the 42 bluestones that make up the inner ring came all the way from western Wales. The outer layer of sarsen stones hails from much closer to home: Marlborough Downs, an area of round, grassy hills 25 to 30 km (17 miles) north of Stonehenge, which has the largest concentration of sarsen in the UK.

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If you ask most satellite companies aside from SpaceX, they will tell you the world doesn't have enough capacity for launching payloads into orbit. This is despite the blistering launch cadence we've seen around the world in recent years, led by SpaceX's Falcon 9 rocket.

Customers in any sector will, of course, usually welcome competition. Theoretically, competition will lead to lower prices and allow the best to rise to the top. It seems like the customers buying launch services were right. SpaceX is dialing back its Falcon 9 launch program, and there is no certainty about when SpaceX's reusable next-generation super-heavy-lift rocket, Starship, will carry anything to orbit besides the company's own Starlink satellites.

So it's no surprise satellite operators are cheering the success of a new launch provider. This was especially the case a few days ago, when Germany's Isar Aerospace reached orbit for the first time with its Spectrum rocket. The launcher delivered a batch of CubeSats to low-Earth orbit from a spaceport in northern Norway, and Isar tasted success after its first test flight ended in failure last year.

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Games may be life with all the hard bits removed, but they provide a way to study why people make the choices they make. Traditional games are usually played against a static background: the rewards per outcome are constant. That limits their relevance to behavior because, in real life, the rewards and consequences of strategic choices are ever changing. Now, researchers have used a mathematical model to study a series of games that include evolving strategies and randomly varying returns.

A bit of history

Perhaps the most famous game-theory contest is the prisoner’s dilemma. In the prisoner’s dilemma, a pair of thieves have been captured and are being separately interrogated by the police. If both clam up, they will be punished for a lesser crime. If one prisoner makes a deal (defects) then that prisoner gets to go free and the other gets a heavier sentence. If both make a deal, they both get an in-between punishment.

The person running the game can start it with different rewards for cooperating and defecting to explore how the optimum strategy varies with reward and risk, which the players can figure out by varying the strategies across multiple rounds. Depending on the balance between the reward for staying silent (cooperating) and betrayal, the game stabilizes with everyone betraying everyone. In this simple situation, everyone loses.

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