schwit1 shares a report from The Wall Street Journal: Nearly 150 years ago, [German physician Carl Reinhold August Wunderlich] analyzed a million temperatures from 25,000 patients and concluded that normal human-body temperature is 98.6 degrees Fahrenheit. In a new study, researchers from Stanford University argue that Wunderlich's number was correct at the time but is no longer accurate because the human body has changed. Today, they say, the average normal human-body temperature is closer to 97.5 degrees Fahrenheit (Warning: source paywalled; alternative source).

To test their hypothesis that today's normal body temperature is lower than in the past, Dr. Parsonnet and her research partners analyzed 677,423 temperatures collected from 189,338 individuals over a span of 157 years. The readings were recorded in the pension records of Civil War veterans from the start of the war through 1940; in the National Health and Nutrition Examination Survey I conducted by the U.S. Centers for Disease Control and Prevention from 1971 through 1974; and in the Stanford Translational Research Integrated Database Environment from 2007 through 2017. Overall, temperatures of the Civil War veterans were higher than measurements taken in the 1970s, and, in turn, those measurements were higher than those collected in the 2000s. The study has been published in the journal eLife.

An anonymous reader quotes a report from MIT Technology Review: In a paper published in Nature today, DeepMind, Alphabet's AI subsidiary, has once again used lessons from reinforcement learning to propose a new theory about the reward mechanisms within our brains. The hypothesis, supported by initial experimental findings, could not only improve our understanding of mental health and motivation. It could also validate the current direction of AI research toward building more human-like general intelligence. At a high level, reinforcement learning follows the insight derived from Pavlov's dogs: it's possible to teach an agent to master complex, novel tasks through only positive and negative feedback. An algorithm begins learning an assigned task by randomly predicting which action might earn it a reward. It then takes the action, observes the real reward, and adjusts its prediction based on the margin of error. Over millions or even billions of trials, the algorithm's prediction errors converge to zero, at which point it knows precisely which actions to take to maximize its reward and so complete its task.

It turns out the brain's reward system works in much the same way -- a discovery made in the 1990s, inspired by reinforcement-learning algorithms. When a human or animal is about to perform an action, its dopamine neurons make a prediction about the expected reward. Once the actual reward is received, they then fire off an amount of dopamine that corresponds to the prediction error. A better reward than expected triggers a strong dopamine release, while a worse reward than expected suppresses the chemical's production. The dopamine, in other words, serves as a correction signal, telling the neurons to adjust their predictions until they converge to reality. The phenomenon, known as reward prediction error, works much like a reinforcement-learning algorithm. The improved algorithm changes the way it predicts rewards. "Whereas the old approach estimated rewards as a single number -- meant to equal the average expected outcome -- the new approach represents them more accurately as a distribution," the report says. This lends itself to a new hypothesis: Do dopamine neurons also predict rewards in the same distributional way?

After testing this theory, DeepMind found "compelling evidence that the brain indeed uses distributional reward predictions to strengthen its learning algorithm," reports MIT Technology Review.

We've known since the 1980s that you don't need mega-constellations comprising thousands of satellites to provide global internet coverage to the world. Continuous worldwide coverage is possible with a constellation of just four satellites placed at much higher altitudes. So why don't we have that? The big obstacle is cost. Several factors work to degrade a satellite's orbit, and to combat them, you need a huge amount of propellant on the satellite to consistently stabilize its orbit. Manufacturing, launch, and operational costs are just too high for the four-satellite trick. An anonymous reader writes: A new study proposes a counterintuitive approach that turns these degrading forces into ones that actually help keep these satellites in orbit. Instead of elliptical, the satellites' orbits would be circular, letting them get by with less fuel while still providing nearly global coverage (at slower speeds). The team ran simulations and found two that would work -- but there are still too many other issues for it to ever happen.

Alan Buis of NASA's Jet Propulsion Laboratory, writes: There's an old saying that "the proof is in the pudding," meaning that you can only truly gauge the quality of something once it's been put to a test. Such is the case with climate models: mathematical computer simulations of the various factors that interact to affect Earth's climate, such as our atmosphere, ocean, ice, land surface and the Sun. For decades, people have legitimately wondered how well climate models perform in predicting future climate conditions. Based on solid physics and the best understanding of the Earth system available, they skillfully reproduce observed data. Nevertheless, they have a wide response to increasing carbon dioxide levels, and many uncertainties remain in the details. The hallmark of good science, however, is the ability to make testable predictions, and climate models have been making predictions since the 1970s. How reliable have they been? Now a new evaluation of global climate models used to project Earth's future global average surface temperatures over the past half-century answers that question: most of the models have been quite accurate.

In a study accepted for publication in the journal Geophysical Research Letters, a research team led by Zeke Hausfather of the University of California, Berkeley, conducted a systematic evaluation of the performance of past climate models. The team compared 17 increasingly sophisticated model projections of global average temperature developed between 1970 and 2007, including some originally developed by NASA, with actual changes in global temperature observed through the end of 2017. The observational temperature data came from multiple sources, including NASA's Goddard Institute for Space Studies Surface Temperature Analysis (GISTEMP) time series, an estimate of global surface temperature change. The results: 10 of the model projections closely matched observations. Moreover, after accounting for differences between modeled and actual changes in atmospheric carbon dioxide and other factors that drive climate, the number increased to 14. The authors found no evidence that the climate models evaluated either systematically overestimated or underestimated warming over the period of their projections.

sciencehabit shares a report from Science Magazine: Researchers have now created a form of concrete that not only comes from living creatures but -- given the right inputs -- can turn one brick into two, two into four, and four into eight. [...] For this project, Wil Srubar, a materials scientist at the University of Colorado, Boulder, and his colleagues wanted to engineer life into a bulk structural material. To do so, they turned to a hearty photosynthetic cyanobacterial species in the genus Synechococcus. They mixed the cyanobacterium with sand and a hydrogel that helped retain water and nutrients. The mix provided structural support to the bacteria, which -- as they grey -- lay down calcium carbonate, similar to the way some ocean creatures create shells. When dried, the resulting material was as strong as cement-based mortar. "It looks like a Frankenstein-type material," Srubar says. "That's exactly what we're trying to create, something that stays alive." Under the right conditions, which included relatively high humidity, Srubar's living material not only survived but reproduced. After the researchers split the original brick in half and added extra sand, hydrogel, and nutrients, the cyanobacteria grew in 6 hours into two full-size bricks; after three generations (in which the researchers again split the bricks), they had eight bricks, they report today in Matter.

pgmrdlm shares a report from ABC News: Some hospitals are ditching the ritual of covering reproductive organs and fetuses during imaging exams after prominent medical and scientific groups have said it's a feel-good measure that can impair the quality of diagnostic tests and sometimes inadvertently increase a patient's radiation exposure. The about-face is intended to improve care, but it will require a major effort to reassure regulators, health care workers and the public that it's better not to shield.

Lead shields are difficult to position accurately, so they often miss the target area they are supposed to protect. Even when in the right place, they can inadvertently obscure areas of the body a doctor needs to see -- the location of a swallowed object, say -- resulting in a need to repeat the imaging process, according to the American Association of Physicists in Medicine, which represents physicists who work in hospitals. Shields can also cause automatic exposure controls on an X-ray machine to increase radiation to all parts of the body being examined in an effort to "see through" the lead. Moreover, shielding doesn't protect against the greatest radiation effect: "scatter," which occurs when radiation ricochets inside the body, including under the shield, and eventually deposits its energy in tissues. "In April, the physicists' association recommended that shielding of patients be 'discontinued as routine practice,'" the report adds. "Its statement was endorsed by several groups, including the American College of Radiology and the Image Gently Alliance, which promotes safe pediatric imaging. However, experts continue to recommend that health care workers in the imaging area protect themselves with leaded barriers as a matter of occupational safety."

In December, scientists sent 40 very muscular mice to live temporarily at the International Space Station. The resulting research, they hope, could lead to new treatments for kids with muscular dystrophy, or cancer patients with muscle wasting. From a report: In early December at the Kennedy Space Center in Florida, two anxious scientists were about to send 20 years of research into orbit. "I feel like our heart and soul is going up in that thing," Dr. Emily Germain-Lee told her husband, Dr. Se-Jin Lee, as they waited arm-in-arm for a SpaceX rocket to launch. A few seconds later the spacecraft took off, transporting some very unusual mice to the International Space Station, where they would spend more than a month in near zero gravity. Ordinarily, that would cause the animals' bones to weaken and their muscles to atrophy. But Lee and Germain-Lee, a power couple in the research world, were hoping that wouldn't happen with these mice.

"It was worth waiting 20 years for," Lee said as the Falcon 9 rocket headed toward space. "And someday it may really help people," Germain-Lee added. The couple hope that what they learn from these mice will lead to new treatments for millions of people with conditions that weaken muscles and bones. Among those who might eventually benefit: children with muscular dystrophy or brittle bone disease, cancer patients with muscle wasting, bedridden patients recovering from hip fractures, older people whose bones and muscles have become dangerously weak, and astronauts on long space voyages.

A new living substance can transform from a wet sand mixture into a solid brick, and even help to reproduce copies of itself. From a report: Researchers from the University of Colorado, Boulder, used a type of photosynthetic bacteria that absorbs carbon dioxide, sunlight, and nutrients and produces calcium carbonate -- a rigid compound found in rocks, pearls, and seashells. They grew the bacteria in a warm mixture of salt water and other nutrients and combined it with sand and gelatin. The mixture was poured into a mold, and as it cooled the gelatin set, forming a "scaffold" able to support further bacterial growth. The bacteria deposited calcium carbonate throughout the scaffold, turning the soft sludge into a harder substance after about a day. The mixture looks green initially, but the color fades as it dries. The research was published in the journal Matter and was funded by DARPA, the US military's research arm.

Climate-change-related threats such as extreme weather, large-scale biodiversity losses and a failure of political leaders to slow planetary heating are now the top long-term risks facing the globe, business and other leaders said. From a report: An annual risk survey published ahead of the World Economic Forum next week put climate threats ahead of risks ranging from cyberattacks and pandemics to geopolitical conflict and weapons of mass destruction for the first time. "That's new. Last year we didn't have it," said Mirek Dusek, deputy head of the Centre for Geopolitical and Regional Affairs and an executive committee member of the World Economic Forum, of the rise of environmental issues up the list. The shift comes as climate-changing emissions continue to rise strongly globally, despite government and business commitments to reduce them, and as the potential impact of runaway climate change becomes clearer. From wildfires in Australia, Brazil and California to worsening storms, floods and droughts, "all key indicators point that this is a situation that's bad and it's getting worse," said John Drzik, chairman of Marsh & McLennan Insights, a global risk, insurance and professional services firm.

fahrbot-bot shares a report from the BBC: Scientists analyzing a meteorite have discovered the oldest material known to exist on Earth. They found dust grains within the space rock -- which fell to Earth in the 1960s -- that are as much as 7.5 billion years old. The oldest of the dust grains were formed in stars that roared to life long before our Solar System was born. A team of researchers has described the result in the journal Proceedings of the National Academy of Sciences.

The team from the U.S. and Switzerland analyzed 40 pre-solar grains contained in a portion of the Murchison meteorite, that fell in Australia in 1969. Based on how many cosmic rays had interacted with the grains, most had to be 4.6-4.9 billion years old. For comparison, the Sun is 4.6 billion years old and the Earth is 4.5 billion. However, the oldest yielded a date of around 7.5 billion years old. Previously, the oldest pre-solar grain dated with neon isotopes was around 5.5 billion years old.

According to physicist Jason Steffen, letting slower passengers board airplanes first actually results in a more efficient process and less time before takeoff. An anonymous reader shares a report from Ars Technica: Back in 2011, Jason Steffen, now a physicist at the University of Nevada, Las Vegas, became intrigued by the problem and applied the same optimization routine used to solve the famous traveling salesman problem to airline boarding strategies. Steffen fully expected that boarding from the back to the front would be the most efficient strategy and was surprised when his results showed that strategy was actually the least efficient. The most efficient, aka the "Steffen method," has the passengers board in a series of waves. "Adjacent passengers in line will be seated two rows apart from each other," Steffen wrote at The Conversation in 2014. "The first wave of passengers would be, in order, 30A, 28A, 26A, 24A, and so on, starting from the back."

Field tests bore out the results, showing that Steffen's method was almost twice as fast as boarding back-to-front or rotating blocks of rows and 20-30 percent faster than random boarding. The key is parallelism, according to Steffen: the ideal scenario is having more than one person sitting down at the same time. "The more parallel you can make the boarding process, the faster it will go," he told Ars. "It's not about structuring things as much as it is about finding the best way to facilitate multiple people sitting down at the same time." Steffen used a standard agent-based model using particles to represent individual agents. This latest study takes a different approach, modeling the boarding process using Lorentzian geometry -- the mathematical foundation of Einstein's general theory of relativity. Co-author Sveinung Erland of Western Norway University and colleagues from Latvia and Israel exploited the well-known connection between microscopic dynamics of interacting particles and macroscopic properties and applied it to the boarding process. In this case, the microscopic interacting particles are the passengers waiting in line to board, and the macroscopic property is how long it takes all the passengers to settle into their assigned seats. The paper has been published in the journal Physical Review E.

The 2010s were the hottest decade ever measured on Earth, and 2019 was the second-hottest year ever measured, scientists at NASA and the National Oceanic and Atmospheric Administration announced today. From a report: After a year of flash droughts, rampant wildfires, and searing heatwaves that set all-time records across Europe and turned parts of Greenland's ice sheet into slush, the finding was not a surprise to researchers, or likely anyone else. But it capped an anxious decade that saw human-caused climate change transform from a far-off threat to an everyday fact of life. Last year was 1.8 degree Fahrenheit -- or just under one degree Celsius -- warmer than the 20th century average, Gavin Schmidt, the chief climate scientist at NASA, said at a briefing announcing the news. Almost everywhere on the planet's surface was warmer than average, though the Arctic was especially searing. "Every decade since the 1960s has been warmer than the decade previous," he said.

In short, it's bad, but you probably knew that already. At least four different groups of scientists, each working independently, have now concluded that the 2010s were the hottest decade of the modern era. (NASA and NOAA start this era at 1880, when they say weather record-keeping became reliable and widespread enough to trust, but the nonprofit research agency Berkeley Earth argues that 2019 was the second warmest year since at least 1850.) What's worse is that greenhouse-gas pollution from fossil fuels, which are the biggest driver of climate change, also surged to an all-time high last year, according to a preliminary estimate. Deke Arndt, a chief climate scientist at NOAA, said at a briefing today that "an obvious signal" of this greenhouse-gas-powered heating had appeared in the upper layers of the ocean, which broke the all-time heat record last year.

A team of programmers scraped a pet adoption website to cheat in a $10,000 contest that was intended to help shelter pets get adopted. From a report: Kaggle, an online data science community that regularly hosts machine learning competitions with prizes often in the tens of thousands of dollars, has uncovered a cheating scandal involving a winning team. The Google subsidiary announced late last week that the winner of a competition involving a pet adoption site had been disqualified from the contest for fraudulently obtaining and obscuring test set data. The fact that a team cheated in a competition nominally intended to help shelter animals also raises questions about whether the people who participate in machine learning competitions like Kaggle are actually interested in making the world a better place, or whether they simply want to win prize money and climb virtual leaderboards.

The competition asked contestants to develop algorithms to predict the rate of pet adoption based on pet listings from PetFinder.my, a Malaysian pet adoption site. The goal, according to the competition, was to help discover what makes a shelter pet's online profile appealing for adopters. The winning team's entry would be "adapted into AI tools that will guide shelters and rescuers around the world on improving their pet profiles' appeal, reducing animal suffering and euthanization," the competition site said. The algorithm from BestPetting, the first place team, seemed to almost perfectly predict the rate of adoption for the test set against which the submissions were evaluated, winning with a nearly perfect score of 0.912 (out of 1.0). As a reward for their winning solution, the team of three was awarded the top prize of $10,000. Nine months after the close of the competition, however, one observant teenager found that the impressive results were too good to be true.

Glacial viruses are understudied, and climate change may keep it that way. From a report: 15,000 years ago, some water froze atop the Tibetan Plateau and became part of a glacier. While humans were busy domesticating dogs, the ice entrapped millions of microscopic organisms per square inch. Many of the tiny life forms died, and their genomes -- the only proof that they had been there in the first place -- slowly degraded. Then, in 2015, scientists from the U.S. and China drilled down 50 meters into the glacier to see what they could find. Five years later, these researchers have recovered evidence of ancient viruses in the glacier ice, including 28 viral groups that are new to science. Their study detailing the discovery was posted online as a pre-print on Tuesday. Records of ancient microbes, like those found in glacier ice, give scientists a glimpse into Earth's evolutionary and climate history. As our planet undergoes climate change, these frozen records can inform predictions about which microorganisms will survive, and what the resulting environment will look like.

"Glacier ice harbors diverse microbes, yet the associated viruses and their impacts on ice microbiomes have been unexplored," the authors wrote in the paper. The group declined to comment on the paper, as it has not yet been peer-reviewed -- "This is an exciting new area of research for us," co-author Lonnie Thompson said in an email. Viruses found in glacial samples known as ice cores are especially understudied because of how small they are, said Scott O. Rogers, a professor at Bowling Green State University and an author of the book Defrosting Ancient Microbes: Emerging Genomes in a Warmer World.

iONiUM writes: LIGO has detected gravitational waves deep in space. The source is currently unknown.

The Independent reports: "Scientists think they have detected an 'unknown or unanticipated' burst of gravitational waves coming from somewhere deep in space. The wobble in spacetime was picked up unexpectedly by the LIGO experiment, which was specifically built to detect gravitational waves. Astronomers have a picture of what part of the sky the burst originated from, and will look to find more information about its source by further studying the area. But for now there is very little indication of what could have caused the blast, which sent ripples through the fabric of the universe that were detected by LIGO in recent hours. Errors of this kind are predicted to happen only once every 25 years, indicating that the burst probably did really come from an astrophysical event."

In case anyone is worried, it's already been confirmed Betelgeuse is still there.

Researchers from the University Hospital Zurich, ETH Zurich, Wyss Zurich and the University of Zurich have developed a machine that repairs injured human livers and keeps them alive outside the body for one week. ScienceDaily reports: Until now, livers could be stored safely outside the body for only a few hours. With the novel perfusion technology, livers -- and even injured livers -- can now be kept alive outside of the body for an entire week. This is a major breakthrough in transplantation medicine, which may increase the number of available organs for transplantation and save many lives of patients suffering from severe liver disease or a variety of cancers. Injured cadaveric livers, initially not suitable for use in transplantation, may regain full function while perfused in the new machine for several days. The basis for this technology is a complex perfusion system, mimicking most core body functions close to physiology. The corresponding study was published in the journal Nature Biotechnology.

The inaugural study shows that six of ten perfused poor-quality human livers, declined for transplantation by all centers in Europe, recovered to full function within one week of perfusion on the machine. The next step will be to use these organs for transplantation. The proposed technology opens a large avenue for many applications offering a new life for many patients with end stage liver disease or cancer.

Sabine Hossenfelder, research fellow at the Frankfurt Institute for Advanced Studies, writes: What we have here in the foundation of physics is a plain failure of the scientific method. All these wrong predictions should have taught physicists that just because they can write down equations for something does not mean this math is a scientifically promising hypothesis. String theory, supersymmetry, multiverses. There's math for it, alright. Pretty math, even. But that doesn't mean this math describes reality. Physicists need new methods. Better methods. Methods that are appropriate to the present century. And please spare me the complaints that I supposedly do not have anything better to suggest, because that is a false accusation. I have said many times that looking at the history of physics teaches us that resolving inconsistencies has been a reliable path to breakthroughs, so that's what we should focus on. I may be on the wrong track with this, of course.

Why don't physicists have a hard look at their history and learn from their failure? Because the existing scientific system does not encourage learning. Physicists today can happily make career by writing papers about things no one has ever observed, and never will observe. This continues to go on because there is nothing and no one that can stop it. You may want to put this down as a minor worry because -- $40 billion dollar collider aside -- who really cares about the foundations of physics? Maybe all these string theorists have been wasting tax-money for decades, alright, but in the large scheme of things it's not all that much money. I grant you that much. Theorists are not expensive. But even if you don't care what's up with strings and multiverses, you should worry about what is happening here. The foundations of physics are the canary in the coal mine. It's an old discipline and the first to run into this problem. But the same problem will sooner or later surface in other disciplines if experiments become increasingly expensive and recruit large fractions of the scientific community. Indeed, we see this beginning to happen in medicine and in ecology, too.

Cy Guy writes: Having not learned the lessons of Jurassic Park and the Terminator, scientists from the University of Vermont and Tufts have created "reconfigurable organisms" using stem cells from frogs. But don't worry, the research was funded by the Department of Defense, so I'm sure nothing could possibly go wrong this time. "The robots, which are less than 1mm long, are designed by an 'evolutionary algorithm' that runs on a supercomputer," reports The Guardian. "The program starts by generating random 3D configurations of 500 to 1,000 skin and heart cells. Each design is then tested in a virtual environment, to see, for example, how far it moves when the heart cells are set beating. The best performers are used to spawn more designs, which themselves are then put through their paces."

"Because heart cells spontaneously contract and relax, they behave like miniature engines that drive the robots along until their energy reserves run out," the report adds. "The cells have enough fuel inside them for the robots to survive for a week to 10 days before keeling over."

The findings have been published in the Proceedings of the National Academy of Sciences.

Through its partnerships with health care providers, Google can view tens of millions of patient records in at least three-quarters of states, the Wall Street Journal reports. From a report: Some of these partnerships allow Google to access identifiable information about patients without their or their doctors' knowledge, raising fears about how this data may be used. Google is developing a new search tool -- designed to be used by doctors, nurses and potentially patients -- that stores and analyzes patient information on its servers. The company and some health systems say argue that data-sharing can improve patient outcomes. Google says its health endeavors aren't connected with its advertising business.

The U.S. Supreme Court stayed out of the debate over what types of medical diagnostic tests can be patented, leaving in legal limbo companies that discover ways to diagnose and treat diseases based on patients' unique characteristics. From a report: The justices rejected an appeal by Quest Diagnostics's Athena unit that sought to restore its patent for a test to detect the presence of an autoimmune disease. A lower court had ruled in favor of the nonprofit Mayo Clinic that the test wasn't eligible for a patent because it merely covered a natural law -- the correlation between the presence of an antibody and the disease. Justices on Monday also rejected appeals to clarify the rules regarding software patents. The Supreme Court's action leaves it to Congress to resolve an issue that's created a legal gray area for such discoveries.