Amazing Science

Want to swim with the fishes? New research unravels what makes fish fins so strong yet flexible at the same time.

Fish fins do not contain muscles, yet fish can change their shape with high precision and speed to produce large and complex hydrodynamic forces—a combination of high morphing efficiency and high flexural stiffness that is rare in modern morphing and robotic materials. These “flexo-morphing” capabilities are rare in modern morphing and robotic materials of human design. The thin rays that stiffen the fins and transmit actuation include mineral segments, a prominent feature whose mechanics and function are not fully understood. 

Now, a group of scientists and engineers use mechanical modeling and mechanical testing on 3D-printed ray models to show that the function of the segmentation is to provide combinations of high flexural stiffness and high morphing amplitude that are critical to the performance of the fins and would not be possible with rays made of a continuous material.

Fish fin–inspired designs that combine very soft materials and very stiff segments can provide robotic materials with large morphing amplitudes and strong grasping forces.

The study, published recently in the journal Nature Neuroscience, is one of the largest genome-wide association studies of its kind ever conducted.

An analysis of data from 1.5 million people has identified 579 locations in the genome associated with a predisposition to different behaviors and disorders related to self-regulation, including addiction and child behavioral problems. With these findings in hand, researchers have constructed a genetic risk score -- a number reflecting a person's overall genetic propensity based on how many risk variants they carry -- that predicts a range of behavioral, medical and social outcomes, including education levels, obesity, opioid use disorder, suicide, HIV infections, criminal convictions and unemployment.

"This study illustrates that genes don't code for a particular disorder or outcome; there are no genes 'for' substance use disorder, or 'for' behavior problems," said joint senior author Danielle Dick, Ph.D., Commonwealth Professor of Psychology and Human and Molecular Genetics at Virginia Commonwealth University. "Instead, genes influence the way our brains are wired, which can make us more at risk for certain outcomes. In this case, we find that there are genes that broadly influence self-control or impulsivity, and that this predisposition then confers risk for a variety of life outcomes."

The study, "Multivariate analysis of 1.5 million people identifies genetic associations with traits related to self-regulation and addiction," was published today in the journal Nature Neuroscience and was conducted by a consortium of 26 researchers at 17 institutions in the United States and the Netherlands.

The breast milk of lactating mothers vaccinated against COVID-19 contains a significant supply of antibodies that may help protect nursing infants.

The breast milk of lactating mothers vaccinated against COVID-19 contains a significant supply of antibodies that may help protect nursing infants from the illness, according to new research from the University of Florida. "Our findings show that vaccination results in a significant increase in antibodies against SARS-CoV-2 -- the virus that causes COVID-19 -- in breast milk, suggesting that vaccinated mothers can pass on this immunity to their babies, something we are working to confirm in our ongoing research," said Joseph Larkin III, Ph.D., senior author of the study and an associate professor in the UF/IFAS department of microbiology and cell science.

When babies are born, their immune systems are underdeveloped, making it hard for them to fight infections on their own. They are also often too young to respond adequately to certain types of vaccines, said Josef Neu, M.D., one of the study's co-authors and a professor in the UF College of Medicine's department of pediatrics, division of neonatology. During this vulnerable period, breast milk allows nursing mothers to provide infants with "passive immunity," Neu explained.

"Think of breast milk as a toolbox full of all the different tools that help prepare the infant for life. Vaccination adds another tool to the toolbox, one that has the potential to be especially good at preventing COVID-19 illness," Neu said. "The results of our study strongly suggest that vaccines can help protect both mom and baby, another compelling reason for pregnant or lactating women to get vaccinated."

The study was conducted between December 2020 and March 2021, when the Pfizer and Moderna vaccines first became available to health care workers. For the study, researchers recruited 21 lactating health care workers who had never contracted COVID-19. The research team sampled the mothers' breast milk and blood three times: before vaccination, after the first dose and after the second dose.

"We saw a robust antibody response in blood and breast milk after the second dose -- about a hundred-fold increase compared with levels before vaccination," said Lauren Stafford, a doctoral student in Larkin's lab. "These levels are also higher than those observed after natural infection with the virus," said Vivian Valcarce, M.D., a resident in the UF College of Medicine's department of pediatrics, division of neonatology. Valcarce and Stafford share primary authorship of the study's findings.

The work sheds light on the web of hydrogen bonds that gives water its strange properties, which play a vital role in many chemical and biological processes.

New research led by astronomers from the Harvard & Smithsonian’s Center for Astrophysics shows that the current census of supermassive black holes is incomplete and that a substantial population of off-center wanderers likely exists.

Supermassive black holes are thought to exist at the center of most large galaxies, including the center of our own Milky Way Galaxy. Their masses correlate with properties of the inner regions of their host galaxies, probably because the black holes grow and evolve as galaxy themselves grow, through mergers with other galaxies and the infall of material from the intergalactic medium. When material makes its way to the galactic center and accretes onto the supermassive black hole, it produces an active galactic nucleus. Outflows or other feedback from the active galactic nucleus then act disruptively to quench star formation in the galaxy.

Modern cosmological simulations now self-consistently trace star formation and supermassive black hole growth in galaxies from the early Universe to the present day, confirming these ideas.

The merger process naturally results in some supermassive black holes that are slightly offset from the center of the enlarged galaxy. The path to a single, combined supermassive black hole is complex. Sometimes a binary supermassive black hole is first formed which then gradually merges into one. Detectable gravitational wave emission can be produced in this process. However, the merger can sometimes stall or be disrupted — understanding why is one of the key puzzles in the evolution of supermassive black holes.

According to the new research, even after a billions of years of evolution some supermassive black holes do not join the nucleus but end up instead wandering through the galaxy. “We characterize the population of wandering black holes, defined as those physically offset from their halo centers, in the ROMULUS cosmological simulations,” said Dr. Angelo Ricarte from the Harvard & Smithsonian’s Center for Astrophysics and the Black Hole Initiative at Harvard University and colleagues. “Unlike most other currently available cosmological simulations, black holes are seeded based on local gas properties and are permitted to evolve dynamically without being fixed at halo centers. Tracking these black holes allows us to make robust predictions about the offset population.”

The company believes its Codex machine learning algorithm is the next step in programming—a sidekick for coders to speed up the work and ease the drudgery.

In the beginning, computer programmers translated their desires into the language of machines. Now, those machines are becoming conversant in the language of their programmers. OpenAI’s newly released Codex, a machine learning algorithm that can parse everyday language and computer code, sits between these worlds.

Recently, in a blog post and demo, OpenAI showed off Codex’s skills. The algorithm can turn written prompts into computer code with, at times, impressive results. OpenAI believes Codex will prove a worthy sidekick for coders, accelerating their work.

What Is Codex?

Codex is a descendent of OpenAI’s GPT-3, a sprawling natural-language machine learning algorithm released last year. After digesting and analyzing billions of words, GPT-3 could write (sometimes eerily) passable text with nary but a simple prompt.

But when OpenAI released GPT-3 to developers, they quickly learned it could do more. One fascinating discovery was that GPT-3 could write simple code from prompts. But it wasn’t very good at it, so the team decided to fine-tune the algorithm with coding in mind from the start. They took a version of GPT-3 and trained it on billions of lines of publicly available code, and Codex was born.

According OpenAI, Codex is proficient in over a dozen computer languages, but it’s particularly good at Python and, of course, everyday language. These skills in hand, Codex can digest a prompt like, “Add this image of a rocket ship,” and spit out the code necessary to embed an image (provided by the programmer) on the screen. In a demo, the OpenAI team showed how to code a simple video game—from blank screen to playable—using naught but a series of chatty prompts.

The demos are very impressive, but Codex is not about to replace programmers. OpenAI researchers say Codex currently completes around 37 percent of requests. That’s an improvement on an earlier iteration called Copilot, a kind of autocomplete for coders released as a product on Github, which had a success rate of 27 percent. But it took some manual labor in the form of supervised learning with labeled data sets to get it there. (GPT-3, by contrast, was trained on unlabeled data.) So, there’s room for improvement.

And like any demo, it’s difficult to predict how useful Codex will be in the real world. OpenAI acknowledges this is just a start, calling it a “taste of the future.” They expect it will get better over time, but part of their motivation for this week’s release was to get Codex into the hands of developers, a strategy that paid off richly for GPT-3.

Even with improvements, OpenAI doesn’t see tools like this as a replacement for coders. Rather, they hope to speed up programming and remove some of the drudgery. In the live demo, for example, OpenAI CEO Sam Altman casually noted Codex completed a step in seconds that would have taken him a half hour back when he was programming. Further, writing good software isn’t only about the actual coding bit, they suggest. “Programming is really about having a dream,” OpenAI CTO Greg Brockman told Wired, “It’s about having this picture of what you want to build, understanding your user, asking yourself, ‘How ambitious should we make this thing, or should we get it done by the deadline?’i” Codex doesn’t come up with what to design or how to design it. It will need significant direction, oversight, and quality control for the foreseeable future. Which is true of its sibling GPT-3 as well.

For now, these kinds of programs will be more like sidekicks as opposed to the story’s hero. They may also be a next step in the long-running evolution of computer languages. In a companion op-ed in TechCrunch, Brockman and Hadi Partovi, founder and CEO of Code.org, emphasize how far we’ve come from the days when a select few scientists laboriously programmed computers with punch cards and machine code. In a long progression, computer language has evolved from what suited machines to what suits us.

“With Al-generated code, one can imagine an evolution in every programming tool, in every programming class, and a Cambrian explosion of new software,” they wrote. “Does this mean coding is dead? No! It doesn’t replace the need for a programmer to understand code. It means coding just got much easier, higher impact and thus more important, just as when punch cards were replaced by keyboards, or when Grace Hopper invented the compiler.”

Given its potential, it’s likely OpenAI will eventually make Codex a paid product developers can access and build apps on (like GPT-3). And it’s possible this proves controversial. After Copilot’s release, some in the developer community cried foul, noting the makers of the algorithm would profit on the work of others without compensating them. OpenAI argues the data is protected under “fair use” laws. Brockman told The Verge OpenAI welcomes the debate and is open to adjusting course. Still, he argues the community will benefit overall.

The feeding patterns of black holes offer insight into their size, researchers report. A new study revealed that the flickering in the brightness observed in actively feeding supermassive black holes is related to their mass.

Supermassive black holes are millions to billions of times more massive than the sun and usually reside at the center of massive galaxies. When dormant and not feeding on the gas and stars surrounding them, SMBHs emit very little light; the only way astronomers can detect them is through their gravitational influences on stars and gas in their vicinity. However, in the early universe, when SMBHs were rapidly growing, they were actively feeding—or accreting—materials at intensive rates and emitting an enormous amount of radiation—sometimes outshining the entire galaxy in which they reside, the researchers said.

The new study, led by the University of Illinois Urbana-Champaign astronomy graduate student Colin Burke and professor Yue Shen, uncovered a definitive relationship between the mass of actively feeding SMBHs and the characteristic timescale in the light-flickering pattern. The findings are published in the journal Science.

The observed light from an accreting SMBH is not constant. Due to physical processes that are not yet understood, it displays a ubiquitous flickering over timescales ranging from hours to decades. "There have been many studies that explored possible relations of the observed flickering and the mass of the SMBH, but the results have been inconclusive and sometimes controversial," Burke said.

The team compiled a large data set of actively feeding SMBHs to study the variability pattern of flickering. They identified a characteristic timescale, over which the pattern changes, that tightly correlates with the mass of the SMBH. The researchers then compared the results with accreting white dwarfs, the remnants of stars like our sun, and found that the same timescale-mass relation holds, even though white dwarfs are millions to billions times less massive than SMBHs.

The light flickers are random fluctuations in a black hole's feeding process, the researchers said. Astronomers can quantify this flickering pattern by measuring the power of the variability as a function of timescales. For accreting SMBHs, the variability pattern changes from short timescales to long timescales. This transition of variability pattern happens at a characteristic timescale that is longer for more massive black holes.

The team compared black hole feeding to our eating or drinking activity by equating this transition to a human belch. Babies frequently burp while drinking milk, while adults can hold in the burp for a more extended amount of time. Black holes kind of do the same thing while feeding, they said. "These results suggest that the processes driving the flickering during accretion are universal, whether the central object is a supermassive black hole or a much more lightweight white dwarf," Shen said.

More than 199.98 million people have been reported to be infected by the novel coronavirus globally and 4,414,781​ have died, according to a Reuters tally.

Infections have been reported in more than 210 countries and territories since the first cases were identified in China in December 2019. Interactive graphic tracking global spread of coronavirus: open https://tmsnrt.rs/2FThSv7 in an external browser.

The global surge in cases is highlighting the widening gap in inoculation rates between wealthy and poor nations. Cases are rising in about one-third of the world's countries, many of which have not even given half their population a first dose.

The World Health Organization (WHO) on Wednesday called for a moratorium on COVID-19 vaccine boosters until at least 10% of the population in every country was vaccinated. "We need an urgent reversal, from the majority of vaccines going to high-income countries, to the majority going to low-income countries," WHO Director-General Tedros Adhanom Ghebreyesus said.

The Delta variant is upending all assumptions about the virus and roiling economies, with disease experts scrambling to find whether the latest version of coronavirus is making people, especially unvaccinated individuals, sicker than before.

At least 2.6% of the world's population has been infected since the pandemic started, with the true figure likely higher due to limited testing in many places. If the number of infected people were a country, it would be eighth most populous in the world, behind Nigeria, according to a Reuters analysis.

It took over a year for COVID-19 cases to hit 100 million mark, while the next 100 million were reported in just over six months, according to the analysis. The pandemic has left close to 4.4 million people dead.

The countries reporting the most cases on a seven-day average - the United States, Brazil, Indonesia, India and Iran - represent about 38% of all global cases reported each day.

Billionaires Jeff Bezos and Richard Branson traveled to the edge of space and hope more people will do the same. It could mean huge carbon emissions.

When Jeff Bezos announced his flight to space last month, he said, "If you see the Earth from space, it changes you. It changes your relationship with this planet, with humanity." 

For a long time, only astronauts could have this experience. But the Amazon billionaire has dreamed of it since he was a kid. On Tuesday, Bezos briefly entered suborbital space in a curiously shaped vehicle. His fellow billionaire Richard Branson, the founder of the Virgin Group of companies, also journeyed to the edge of space earlier this month on a Virgin Galactic flight. Next year, the billionaire Elon Musk plans to make the trip on one of Branson's spaceflights. 

The cost to participate: mega-millions. The carbon-pollution bill: to be determined. Instead of NASA's long list of qualifications and required experience, Blue Origin passengers train for 14 hours over two days. Virgin Galactic gives passengers three days of training and preparation. For these billionaires, success would mean many more civilians taking similar pricey journeys for this rare view of Earth. But, with the limited passenger capacity for each flight and the environmental impacts from launch emissions (which could worsen extreme climate-related weather events), this burgeoning "space tourism" industry isn't sustainable. 

The effects on humans of increased exposure to carbon dioxide can include a variety of health problems, including headaches, dizziness, difficulty breathing, fatigue, suffocation, and convulsions. Higher levels of nitrogen dioxide can impair a person's ability to breathe and increase their vulnerability to respiratory infections and asthma. Long-term exposure to nitrogen oxide can also cause chronic lung disease and reduce a person's sense of smell, according to the Australian government.

Uncertainty about the climate effects

There's been little disclosed about the total carbon footprint of these new spaceflights. This makes it difficult to determine the overall effect of rocket launches on the atmosphere, especially when companies like Virgin Galactic anticipate offering 400 spaceflights annually. But experts say emissions per passenger from a voyage with Branson's company are roughly equivalent to driving a typical car around the circumference of the Earth.

A potentially very large problem

While the propellants used to launch Blue Origin's New Shepard, Virgin's VSS Unity, and SpaceX's Falcon rockets vary, the ignition and burning process often generate greenhouse gases, water vapor, and heat, according to the University College London associate professor Eloise Marais. While the number of space flights is small compared to long-haul commercial aviation, the difference in carbon dioxide is magnitudes higher. Instead of one to three tons of carbon dioxide emitted per passenger, a rocket carrying four or more passengers will produce 200 to 300 tons of carbon dioxide. "So it doesn't need to grow that much more to compete with other sources," Marais told The Guardian. 

More environmental waste from the superrich

These spaceflights will join helicopters, private jets, and superyachts as modes of transportation with enormous carbon footprints. But operational rockets like the SpaceX Falcon Heavy already show that carbon dioxide emissions from commercial space launches are significantly higher. These are difficult to cancel out through carbon offsets or other individual choices, like going vegan.

In 2019, Ripple et al. (2020) warned of untold suffering and declared a climate emergency together with more than 11,000 scientist signatories from 153 countries. They presented graphs of planetary vital signs indicating very troubling trends, along with little progress by humanity to address climate change. On the basis of these data and scientists’ moral obligation to “clearly warn humanity of any catastrophic threat,” they called for transformative change.

Since the article's publication, more than 2,800 additional scientists have signed that declaration of a climate emergency (see supplemental file S1 for the current signatory list); in addition, 1,990 jurisdictions in 34 countries have now formally declared or recognized a climate emergency. But, at the same time, there has been an unprecedented surge in climate-related disasters since 2019, including devastating flooding in South America and Southeast Asia, record shattering heat waves and wildfires in Australia and the Western United States, an extraordinary Atlantic hurricane season, and devastating cyclones in Africa, South Asia, and the West Pacific. There is also mounting evidence that we are nearing or have already crossed tipping points associated with critical parts of the Earth system, including the West Antarctic and Greenland ice sheets, warm-water coral reefs, and the Amazon rainforest (supplemental file).

Given these alarming developments, we need short, frequent, and easily accessible updates on the climate emergency.

Ever since humanity has grasped the idea of a robot, we’ve wanted to imagine them into walking humanoid form. But making a robot walk like a human is not an easy task, and even the best of them end up with the somewhat shuffling gait of a Honda Asimo rather than the graceful poise of a balerina. Only in recent years have walking robots appeared to come of age, and then not by mimicking the human gait but something more akin to a bird.

We’ve seen it in the Boston Dynamics models, and also now in a self-balancing two-legged robot developed at Oregon State University that has demonstrated its abilities by completing an unaided 5 km run having used its machine learning skills to teach itself to run from scratch. It’s believed to be the first time a robot has achieved such a feat without first being programmed for the specific task.

The university’s PR piece envisages a time in which walking robots of this type have become commonplace, and when humans interact with them on a daily basis. We can certainly see that they could perform a huge number of autonomous outdoor tasks that perhaps a wheeled robot might find to be difficult, so maybe they have a bright future. Decide for yourself, after watching the video.

Genetically encoded reporter proteins have been a mainstay of biotechnology research, allowing scientists to track gene expression, understand intracellular processes and debug engineered genetic circuits. But conventional reporting schemes that rely on fluorescence and other optical approaches come with practical limitations that could cast a shadow over the field's future progress. Now, researchers at the University of Washington and Microsoft have created a "nanopore-tal" into what is happening inside these complex biological systems, allowing scientists to see reporter proteins in a whole new light.

The team introduced a new class of reporter proteins that can be directly read by a commercially available nanopore sensing device. The new system ? dubbed "Nanopore-addressable protein Tags Engineered as Reporters" or "NanoporeTERs" can detect multiple protein expression levels from bacterial and human cell cultures far beyond the capacity of existing techniques.

The study was published Aug. 12, 2021 in Nature Biotechnology. "NanoporeTERs offer a new and richer lexicon for engineered cells to express themselves and shed new light on the factors they are designed to track. They can tell us a lot more about what is happening in their environment all at once," said co-lead author Nicolas Cardozo, a doctoral student with the UW Molecular Engineering and Sciences Institute.

"We're essentially making it possible for these cells to 'talk' to computers about what's happening in their surroundings at a new level of detail, scale and efficiency that will enable deeper analysis than what we could do before." For conventional labeling methods, researchers can track only a few optical reporter proteins, such as green fluorescent protein, simultaneously because of their overlapping spectral properties. For example, it's difficult to distinguish between more than three different colors of fluorescent proteins at once. In contrast, NanoporeTERs were designed to carry distinct protein "barcodes" composed of strings of amino acids that, when used in combination, allow at least ten times more multiplexing possibilities.

These synthetic proteins are secreted outside of a cell into the surrounding environment, where researchers can collect and analyze them using a commercially available nanopore array. Here, the team used the Oxford Nanopore Technologies MinION device.

Scientists at Cambridge and Leeds have successfully reversed age-related memory loss in mice and say their discovery could lead to the development of treatments to prevent memory loss in people as they age.

In a study recently published in Molecular Psychiatry, the scientists show that changes in the extracellular matrix of the brain -- 'scaffolding' around nerve cells -- lead to loss of memory with aging, but that it is possible to reverse these using genetic treatments. Recent evidence has emerged of the role of perineuronal nets (PNNs) in neuroplasticity -- the ability of the brain to learn and adapt -- and to make memories. PNNs are cartilage-like structures that mostly surround inhibitory neurons in the brain. Their main function is to control the level of plasticity in the brain. They appear at around five years old in humans, and turn off the period of enhanced plasticity during which the connections in the brain are optimized. Then, plasticity is partially turned off, making the brain more efficient but less plastic.

PNNs contain compounds known as chondroitin sulphates. Some of these, such as chondroitin 4-sulphate, inhibit the action of the networks, inhibiting neuroplasticity; others, such as chondroitin 6-sulphate, promote neuroplasticity. As we age, the balance of these compounds changes, and as levels of chondroitin 6-sulphate decrease, so our ability to learn and form new memories changes, leading to age-related memory decline.

Researchers at the University of Cambridge and University of Leeds investigated whether manipulating the chondroitin sulphate composition of the PNNs might restore neuroplasticity and alleviate age-related memory deficits. To do this, the team looked at 20-month old mice -- considered very old -- and using a suite of tests showed that the mice exhibited deficits in their memory compared to six-month old mice. For example, one test involved seeing whether mice recognized an object. The mouse was placed at the start of a Y-shaped maze and left to explore two identical objects at the end of the two arms. After a short while, the mouse was once again placed in the maze, but this time one arm contained a new object, while the other contained a copy of the repeated object. The researchers measured the amount of the time the mouse spent exploring each object to see whether it had remembered the object from the previous task. The older mice were much less likely to remember the object.

The team treated the aging mice using a 'viral vector', a virus capable of reconstituting the amount of 6-sulphate chondroitin sulphates to the PNNs and found that this completely restored memory in the older mice, to a level similar to that seen in the younger mice. Dr Jessica Kwok from the School of Biomedical Sciences at the University of Leeds said: "We saw remarkable results when we treated the aging mice with this treatment. The memory and ability to learn were restored to levels they would not have seen since they were much younger."

To explore the role of chondroitin 6-sulphate in memory loss, the researchers bred mice that had been genetically-manipulated such that they were only able to produce low levels of the compound to mimic the changes of aging. Even at 11 weeks, these mice showed signs of premature memory loss. However, increasing levels of chondroitin 6-sulphate using the viral vector restored their memory and plasticity to levels similar to healthy mice. Prof James Fawcett from the John van Geest Centre for Brain Repair at the University of Cambridge said: "What is exciting about this is that although our study was only in mice, the same mechanism should operate in humans -- the molecules and structures in the human brain are the same as those in rodents. This suggests that it may be possible to prevent humans from developing memory loss in old age."

The team might have already identified a potential drug, licensed for human use, that can be taken by mouth and inhibits the formation of PNNs. When this compound is given to mice and rats it can restore memory in aging and also improves recovery in spinal cord injury. The researchers are investigating whether it might help alleviate memory loss in animal models of Alzheimer's disease. The approach taken by Professor Fawcett's team -- using viral vectors to deliver the treatment -- is increasingly being used to treat human neurological conditions. A second team at the Centre recently published research showing their use for repairing damage caused by glaucoma and dementia.

A new kind of neural interface system that coordinates the activity of hundreds of tiny brain sensors could one day deepen understanding of the brain and lead to new medical therapies.

Brain-computer interfaces (BCIs) are emerging assistive devices that may one day help people with brain or spinal injuries to move or communicate. BCI systems depend on implantable sensors that record electrical signals in the brain and use those signals to drive external devices like computers or robotic prosthetics. Most current BCI systems use one or two sensors to sample up to a few hundred neurons, but neuroscientists are interested in systems that are able to gather data from much larger groups of brain cells.

The asteroid 2021 PH27 has a semi-major axis of 70 million km (43 million miles, 0.46 AU), giving it a 113-day orbital period on an unstable elongated orbit that crosses the orbits of both Mercury and Venus. This means that within a few million years it will likely be destroyed in a collision with one of these planets or the Sun, or it will be ejected from its current position.

2021 PH27 was discovered by Carnegie Institution for Science’s Dr. Scott Sheppard in images taken by Brown University astronomers Ian Dell’Antonio and Shenming Fu on August 13, 2021. “Most likely 2021 PH27 was dislodged from the main asteroid belt between Jupiter and Mars and the gravity of the inner planets shaped its orbit into its current configuration,” Dr. Sheppard said. “Although, based on its large angle of inclination of 32 degrees, it is possible that 2021 PH27 is an extinct comet from the outer Solar System that ventured too close to one of the planets as the path of its voyage brought it into proximity with the inner Solar System.”

Because 2021 PH27 is so close to the Sun’s massive gravitational field, it experiences the largest general relativistic effects of any known solar system object. This is seen in a slight angular deviation in its elliptical orbit over time, a movement called precession, which occurs at about one arcminute per century. Observation of Mercury’s precession puzzled scientists until Albert Einstein’s theory of general relativity explained its orbital adjustments over time. The precession of 2021 PH27 is even faster than Mercury’s. “2021 PH27 gets so close to the Sun that its surface temperature gets to 482 degrees Celsius (900 degrees Fahrenheit) at closest approach, hot enough to melt lead,” Dr. Sheppard said.

People infected with the Delta variant of SARS-CoV-2 are more likely to spread the virus before developing symptoms than are people infected with earlier versions, suggests a detailed analysis of an outbreak in Guangdong, China1.

“It is just tougher to stop,” says Benjamin Cowling, an epidemiologist at the University of Hong Kong and a co-author of the study. Cowling and his colleagues analyzed exhaustive test data from 101 people in Guangdong who were infected with Delta between May and June 2021, and data from those individuals’ close contacts. They found that, on average, people began having symptoms 5.8 days after infection with Delta — 1.8 days after they first tested positive for viral RNA. That left almost two days for individuals to shed viral RNA before they showed any sign of COVID-19.

An earlier study2 and an unpublished analysis by Cowling and others estimate that before Delta emerged, individuals infected with SARS-CoV-2 took an average of 6.3 days to develop symptoms and 5.5 days to test positive for viral RNA, leaving a narrower window of 0.8 days for oblivious viral shedding. In the latest work, the researchers also found that those infected with Delta had higher concentrations of viral particles, or viral load, in their bodies than did people infected with the original version of SARS-CoV-2. “Somehow the virus is appearing quicker and in higher amounts,” says Cowling.

As a result, 74% of infections with Delta took place during the pre-symptomatic phase — a higher proportion than for previous variants. This high rate “helps explain how this variant has been able to outpace both the wild-type virus and other variants to become the dominant strain worldwide”, says Barnaby Young, an infectious-disease clinician at the National Centre for Infectious Diseases in Singapore.

DeepMind has released a new paper that shows impressive advances in reinforcement learning. How far does it bring us toward general AI?

One of the key challenges of deep reinforcement learning models—the kind of AI systems that have mastered Go, StarCraft 2, and other games—is their inability to generalize their capabilities beyond their training domain. This limit makes it very hard to apply these systems to real-world settings, where situations are much more complicated and unpredictable than the environments where AI models are trained.

But scientists at AI research lab DeepMind claim to have taken the “first steps to train an agent capable of playing many different games without needing human interaction data,” according to a blog post about their new “open-ended learning” initiative. Their new project includes a 3D environment with realistic dynamics and deep reinforcement learning agents that can learn to solve a wide range of challenges.

The new system, according to DeepMind’s AI researchers, is an “important step toward creating more general agents with the flexibility to adapt rapidly within constantly changing environments.” The paper’s findings show some impressive advances in applying reinforcement learning to complicated problems. But they are also a reminder of how far current systems are from achieving the kind of general intelligence capabilities that the AI community has been coveting for decades.

The key advantage of reinforcement learning is its ability to develop behavior by taking actions and getting feedback, similar to the way humans and animals learn by interacting with their environment. Some scientists describe reinforcement learning as “the first computational theory of intelligence.” The combination of reinforcement learning and deep neural networks, known as deep reinforcement learning, has been at the heart of many advances in AI, including DeepMind’s famous AlphaGo and AlphaStar models. In both cases, the AI systems were able to outmatch human world champions at their respective games.

But reinforcement learning systems are also notoriously renowned for their lack of flexibility. For example, a reinforcement learning model that can play StarCraft 2 at an expert level won’t be able to play a game with similar mechanics (e.g., Warcraft 3) at any level of competency. Even slight changes to the original game will considerably degrade the AI model’s performance.

“These agents are often constrained to play only the games they were trained for – whilst the exact instantiation of the game may vary (e.g. the layout, initial conditions, opponents) the goals the agents must satisfy remain the same between training and testing. Deviation from this can lead to catastrophic failure of the agent,” DeepMind’s researchers write in a paper that provides the full details on their open-ended learning.

A shutdown would have devastating global impacts and must not be allowed to happen, researchers say

Climate scientists have detected warning signs of the collapse of the Gulf Stream, one of the planet’s main potential tipping points. The research found “an almost complete loss of stability over the last century” of the currents that researchers call the Atlantic meridional overturning circulation (AMOC). The currents are already at their slowest point in at least 1,600 years, but the new analysis shows they may be nearing a shutdown.

Such an event would have catastrophic consequences around the world, severely disrupting the rains that billions of people depend on for food in India, South America and West Africa; increasing storms and lowering temperatures in Europe; and pushing up the sea level in the eastern North America. It would also further endanger the Amazon rainforest and Antarctic ice sheets.

The complexity of the AMOC system and uncertainty over levels of future global heating make it impossible to forecast the date of any collapse for now. It could be within a decade or two, or several centuries away. But the colossal impact it would have means it must never be allowed to happen, the scientists said.

“The signs of destabilization being visible already is something that I wouldn’t have expected and that I find scary,” said Niklas Boers, from the Potsdam Institute for Climate Impact Research in Germany, who did the research. “It’s something you just can’t allow to happen.”

It is not known what level of CO2 would trigger an AMOC collapse, he said. “So the only thing to do is keep emissions as low as possible. The likelihood of this extremely high-impact event happening increases with every gram of CO2 that we put into the atmosphere”.

The special ESA/Hubble Space Telescope Word Bank provides insightful explanations of various astronomical concepts and objects in simple language.

This resource was developed to be an informative and educative resource for students, parents, educators, communicators, and the general public alike. Each of the words featured in this unique glossary is accompanied by a simple definition and an explanation of various astronomical concepts and objects in simple and accessible language. These descriptions also provide context and connections to Hubble’s relevance and contributions to the respective areas or objects of research.

The Word Bank will continue to be regularly developed and expanded. Please contact us if you have a suggestion for a word or concept you’d like to see included in the Word Bank. You can view the whole visual collection of Word Bank words and their definitions in this gallery.

Like a perpetual motion machine, a time crystal forever cycles between states without consuming any energy. Physicists claim to have built this new phase of matter inside a quantum computer.

Quantum many-body systems display rich phase structure in their low-temperature equilibrium states. However, much of nature is not in thermal equilibrium at all. Remarkably, it was recently predicted that out-of-equilibrium systems can exhibit novel dynamical phases that may otherwise be forbidden by equilibrium thermodynamics, a paradigmatic example being the discrete time crystal (DTC). Concretely, dynamical phases can be defined in periodically driven many-body localized systems via the concept of eigenstate order. In eigenstate-ordered phases, the entire many-body spectrum exhibits quantum correlations and long-range order, with characteristic signatures in late-time dynamics from all initial states. It is, however, challenging to experimentally distinguish such stable phases from transient phenomena, wherein few select states can mask typical behavior.

Now, a team at Google and collaborators implemented a continuous family of tunable CPHASE gates on an array of superconducting qubits to experimentally observe an eigenstate-ordered DTC. They were able to demonstrate the characteristic spatiotemporal response of a DTC for generic initial states. This work employs a time-reversal protocol that discriminates external decoherence from intrinsic thermalization, and leverages quantum typicality to circumvent the exponential cost of densely sampling the eigenspectrum. In addition, they were able to locate the phase transition out of the DTC with an experimental finite-size analysis.

Taken together, these results establish a scalable approach to study non-equilibrium phases of matter on current quantum processors.

For more detailed information, read the original Google paper here.

Over the last few decades, life expectancy has increased dramatically around the globe. The average person born in 1960, the earliest year the United Nations began keeping global data, could expect to live to 52.5 years of age. Today, the average is 72. In the UK, where records have been kept longer, this trend is even greater. In 1841, a baby girl was expected to live to just 42 years of age, a boy to 40. In 2016, a baby girl could expect to reach 83; a boy, 79.

The natural conclusion is that both the miracles of modern medicine and public health initiatives have helped us live longer than ever before – so much so that we may, in fact, be running out of innovations to extend life further. In September 2018, the Office for National Statistics confirmed that, in the UK at least, life expectancy has stopped increasing. Beyond the UK, these gains are slowing worldwide. This belief that our species may have reached the peak of longevity is also reinforced by some myths about our ancestors: it’s common belief that ancient Greeks or Romans would have been flabbergasted to see anyone above the age of 50 or 60, for example.

In fact, while medical advancements have improved many aspects of healthcare, the assumption that human life span has increased dramatically over centuries or millennia is misleading. Overall life expectancy, which is the statistic reflected in reports like those above, hasn’t increased so much because we’re living far longer than we used to as a species. It’s increased because more of us, as individuals, are making it that far.

“There is a basic distinction between life expectancy and life span,” says Stanford University historian Walter Scheidel, a leading scholar of ancient Roman demography. “The life span of humans – opposed to life expectancy, which is a statistical construct – hasn’t really changed much at all, as far as I can tell.”

Life expectancy is an average. If you have two children, and one dies before their first birthday but the other lives to the age of 70, their average life expectancy is 35. That’s mathematically correct – and it certainly tells us something about the circumstances in which the children were raised. But it doesn’t give us the full picture. It also becomes especially problematic when looking at eras, or in regions, where there are high levels of infant mortality. Most of human history has been blighted by poor survival rates among children, and that continues in various countries today.