In the classic fairy tale, Hansel and Gretel dropped bread crumbs while walking through a treacherous forest so they wouldn’t lose their way. Rovers may one day use a similar trick to traverse other planets without losing their data.
Typically, if a rover permanently loses communication during a mission, all the information that it has gathered is lost. To avoid this, researchers suggest using a multi-rover system in which a smaller rover piggybacks on a larger “mother rover.” The smaller rover would then venture into any especially uncertain territory, such as a cave or lava tubes, deploying sensors the size of an AirPods case like bread crumbs as it goes. The sensors could then communicate with each other via a wireless network and funnel any collected data back to the mother rover, theoretical physicist Wolfgang Fink and colleagues propose February 11 in Advances in Space Research. As proof of concept, the team built prototype sensors that communicate via Wi-Fi.
It’s not that the smaller rover would be following the “bread crumbs” back the way it came. Instead, “we use [the sensors] for the data to find its way communication-wise out of the cave to the mother rover,” says Fink, of the University of Arizona in Tucson.
The technology could also be useful here on Earth, especially after a natural disaster such as an earthquake. A rover could be sent with the deployable sensors into rubble where it’s too dangerous for people to perform search-and-rescue missions (SN: 12/3/14).
The bread crumb–like communication network could allow researchers to “cater to the essence of scientific exploration,” Fink says, by allowing rovers to overcome some of the constraints posed by tricky terrain. “To get to the real exciting science, you most of the time have to go to exotic places, hard-to-get-to places.”
For the first time, astronomers have caught a glimpse of shock waves rippling along strands of the cosmic web — the enormous tangle of galaxies, gas and dark matter that fills the observable universe.
Combining hundreds of thousands of radio telescope images revealed the faint glow cast as shock waves send charged particles flying through the magnetic fields that run along the cosmic web. Spotting these shock waves could give astronomers a better look at these large-scale magnetic fields, whose properties and origins are largely mysterious, researchers report in the Feb. 17 Science Advances. Finally, astronomers “can confirm what so far has only been predicted by simulations — that these shock waves exist,” says astrophysicist Marcus Brüggen of the University of Hamburg in Germany, who was not involved in the new study.
At its grandest scale, our universe looks something like Swiss cheese. Galaxies aren’t distributed evenly through space but rather are clumped together in enormous clusters connected by ropy filaments of dilute gas, galaxies and dark matter and separated by not-quite-empty voids (SN: 10/3/19).
Tugged by gravity, galaxy clusters merge, filaments collide, and gas from the voids falls onto filaments and clusters. In simulations of the cosmic web, all that action consistently sets off enormous shock waves in and along filaments.
Filaments make up most of the cosmic web but are much harder to spot than galaxies (SN: 1/20/14). While scientists have observed shock waves around galaxy clusters before, shocks in filaments “have never been really seen,” says astronomer Reinout van Weeren of Leiden University in the Netherlands, who was not involved in the study. “But they should be basically all around the cosmic web.”
Shock waves around filaments would accelerate charged particles through the magnetic fields that suffuse the cosmic web (SN: 6/6/19). When that happens, the particles emit light at wavelengths that radio telescopes can detect — though the signals are very weak. A single shock wave in a filament “would look like nothing, it’d look like noise,” says radio astronomer Tessa Vernstrom of the International Centre for Radio Astronomy Research in Crawley, Australia.
Instead of looking for individual shock waves, Vernstrom and her colleagues combined radio images of more than 600,000 pairs of galaxy clusters close enough to be connected by filaments to create a single “stacked” image. This amplified weak signals and revealed that, on average, there is a faint radio glow from the filaments between clusters.
“When you can dig below the noise and still actually get a result — to me, that’s personally exciting,” Vernstrom says.
The faint signal is highly polarized, meaning that the radio waves are mostly aligned with one another. Highly polarized light is unusual in the cosmos, but it is expected from radio light cast by shock waves, van Weeren says. “So that’s really, I think, very good evidence for the fact that the shocks are likely indeed present.” The discovery goes beyond confirming the predictions of cosmic web simulations. The polarized radio emissions also offer a rare peek at the magnetic fields that permeate the cosmic web, if only indirectly.
“These shocks,” Brüggen says, “are really able to show that there are large-scale magnetic fields that form [something] like a sheath around these filaments.”
He, van Weeren and Vernstrom all note that it’s still an open question how cosmic magnetic fields arose in the first place. The role these fields play in shaping the cosmic web is equally mysterious.
“It’s one of the four fundamental forces of nature, right? Magnetism,” Vernstrom says. “But at least on these large scales, we don’t really know how important it is.”
An uncomfortable truth is that there is another influenza pandemic in humankind’s future. Whether it will be a relative of the lethal avian flu strain currently wreaking havoc in bird populations around the globe is anyone’s guess.
Because the virus, called H5N1, can be deadly to birds, mammals and people, researchers closely monitor reports of new cases. Worryingly, a new variant of H5N1 that emerged in 2020 has not only spread farther than ever before among birds, but has also spilled over into other animals, raising the specter of a human outbreak (SN: 12/12/22).
The variant was linked to a seal die-off in Maine last summer. In October, there was an H5N1 outbreak on a mink farm in Spain, researchers reported in January in Eurosurveillance. (It’s unclear how the mink were exposed, but the animals were fed poultry by-products.) Sea lions off the coast of Peru and wild bears, foxes and skunks, which prey upon or scavenge birds, in the United States and Europe have also tested positive for the virus.
Globally, hundreds of millions of domestic poultry have been culled or died from the new variant. It’s also likely that millions of wild birds have died, though few governmental agencies are counting, says Michelle Wille a viral ecologist at the University of Sydney who studies avian influenza. “This virus is catastrophic for bird populations.”
A handful of human cases have also been reported, though there’s no evidence that the virus is spreading among people. Of seven cases, six people recovered and one person from China died. In February, health officials in China reported an eighth case in a woman whose current condition is unknown.
What’s more, four of the reported human cases — including a U.S. case from Colorado and two workers linked to the Spanish mink farm — were in people who didn’t have any respiratory symptoms. That leaves open the possibility that those people were not truly infected. Instead, tests may have picked up viral contamination, say in the nose, that the people breathed in while handling infected birds.
The impossibility of predicting which avian influenza viruses might make the jump to people and spark an outbreak is in part related to knowledge gaps. These bird pathogens don’t typically easily infect or circulate among mammals including humans. And scientists don’t have a full grasp on how these viruses might need to change for human transmission to occur.
For now, it’s encouraging that so few people have gotten infected amid such a large outbreak among birds and other animals, says Marie Culhane, a food animal veterinarian at the University of Minnesota in St. Paul. Still, experts around the globe are diligently watching for any signs the virus may be evolving to spread more easily between people.
The good news is that flu drugs and vaccines that work against the virus already exist, Wille says. Compared with where the world was when the coronavirus behind the COVID-19 pandemic came on the scene, “we are already ahead of the game.”
How the virus would need to change to spread among people is a big unknown This new iteration of bird flu is what’s called a highly pathogenic avian influenza, one that is particularly lethal for both domestic and wild birds. Aquatic birds such as ducks naturally carry avian flus with no or minor signs of infection. But when influenza viruses shuffle between poultry and waterfowl, variants with changes that make them lethal to birds can emerge and spread.
Avian viruses can be severe or even deadly for people. Since 2003, there have been 873 human cases of H5N1 infections reported to the World Health Organization. A little less than half of those people died. In February, an 11-year-old girl in Cambodia died after she developed severe pneumonia from an avian flu virus, the country’s first reported infection since 2014. Her father was also infected with the virus — a different variant than the one behind the widespread outbreak in birds —though he has not developed symptoms. It’s unknown how the two people were exposed.
Some of what scientists know about H5N1’s pandemic potential comes from controversial research on ferrets done more than a decade ago (SN: 6/21/13). Experiments showed that some changes to proteins that help the virus break into cells and make more copies of itself could help the virus travel through the air to infect ferrets, a common laboratory stand-in for humans in influenza research.
While researchers know these mutations are important in lab settings, it’s still unclear how crucial those changes are in the real world, says Jonathan Runstadler, a disease ecologist and virologist at Tufts University’s Cummings School of Veterinary Medicine in North Grafton, Mass. Viruses change constantly, but not all genetic tweaks work together. A change may help one version of the virus transmit better, while also hurting another variant and making it less likely to spread.
“We’re not sure how critical or how big a difference or how much to worry about those mutations when they happen in the wild,” Runstadler says. “Or when they happen five years down the road when there are other changes in the virus’s genetic background that are impacting those [original] mutations.”
That doesn’t stop researchers from trying to pinpoint specific changes. Runstadler and his team look for viruses in nature that have jumped into new animals and work backward to figure out which mutations were crucial. And virologist Louise Moncla says her lab is trying to develop ways to scan entire genetic blueprints of viruses from past outbreaks to look for signatures of a virus that can jump between different animal species.
“There’s a ton that we don’t know about avian influenza viruses and host switching,” says Moncla, of the University of Pennsylvania.
Genetic analyses of H5N1 circulating on the mink farm in Spain, for instance, revealed a change known to help the virus infect mice and mammalian cells grown in the lab. Such a change could make it easier for the virus to spread among mammals, including people. There could have been mink-to-mink transmission on the farm, the researchers concluded, but it remains unclear how much of a role that specific mutation played in the outbreak.
It’s a numbers game for when influenza viruses with the ability to transmit among mammals might make the jump from birds, Runstadler says. “The more chances you give the virus to spill over and adapt, the higher the risk will be that one of those adaptations will be effective [at helping the virus spread among other animals] or take root and be a real problem.”
The ongoing outbreak is still a big problem for birds Irrespective of our inability to forecast human’s future with H5N1, it’s clear that many species of birds — and some other animals that eat them — are dying now. And more species of birds are dying in this outbreak than previous ones, Culhane and Wille say.
“We have seen huge outbreaks in raptors and seabirds, which were never really affected before,” Wille says. It’s possible that genetic changes have helped the virus to spread more efficiently among birds than previous versions of H5N1, but that’s unknown. “There are a number of studies underway to try and figure it out,” Wille says. Historically, these deadly avian flus have not been a persistent problem in the Americas, Moncla says. Sporadic outbreaks of H5N1 variants are typically limited to places such as parts of Asia, where the virus has circulated in birds since its emergence in the late 1990s, and northern Africa.
North America’s last big avian flu outbreak was in 2015, when experts detected more than 200 cases of a different bird flu virus in commercial and backyard poultry across the United States. The poultry industry culled more than 45 million birds to stop that virus’s spread, Culhane says. “But it didn’t go away from the rest of the world.”
The latest version of H5N1 arrived on North American shores from Europe in late 2021, first popping up in Canada in Newfoundland and Labrador. From there, it spread south into the United States, where so far tens of millions of domestic poultry have been culled to prevent transmission on farms where the virus has been detected. By December 2022, the virus had made it to South America. In Peru, tens of thousands of pelicans and more than 700 sea lions have died since mid-January.
It’s important to understand exactly how nonbird animals are getting exposed, Culhane says. Highly pathogenic avian influenzas infect every organ of a bird’s body. So, a fox chowing down on an infected bird is exposing its own mouth, nose and stomach to a lot of virus as it eats its meal.
For now, experts are keeping an eye on infected animals to raise the alarm early if H5N1 starts transmitting among mammals.
“I do think that the mink outbreak, and then the sea lion outbreak, is a wake-up call,” Moncla says. “We should be doing our very best to implement all the science we can to try and understand what’s happening with these viruses so that if the situation does change, we are better prepared.”
LAS VEGAS — It’s a bold claim: The quest to create a superconductor that works under practical conditions is finally fulfilled, a team of researchers says. But controversy has dogged the team’s earlier claim of record-breaking superconductivity, and the new result is already facing extreme scrutiny.
The ultimate test will be whether the result can be confirmed by other researchers, says physicist Mikhail Eremets of the Max Planck Institute for Chemistry in Mainz, Germany. “I repeat it like [a] mantra: ‘Reproduce.’” Many materials become superconductors, able to transmit electricity with no resistance, provided they’re cooled to very low temperatures. A few superconductors work under warmer conditions, but those must be squeezed to crushing pressures, so they’re impractical to use.
Now physicist Ranga Dias of the University of Rochester in New York and colleagues say they have created a superconductor that works at both room temperature and relatively low pressure. A superconductor that operates under such commonplace conditions could herald a new age of high-efficiency machines, supersensitive instrumentation and revolutionary electronics.
“This is the start of the new type of material that’s useful for practical applications,” Dias said March 7 at the American Physical Society meeting, where he reported the feat.
The superconductor is made of hydrogen mixed with nitrogen and a rare earth element called lutetium, Dias and colleagues report March 8 in Nature. The team combined the elements and squeezed them in a device known as a diamond anvil cell. The researchers then varied the pressure and temperature and measured the resistance to electrical flow in the compound.
At temperatures as high as 294 kelvins (about 21° Celsius or 70° Fahrenheit), the material seemed to lose any electrical resistance. It still required pressures of 10 kilobar, which is about 10,000 times the pressure of Earth’s atmosphere. But that’s far lower than the millions of atmospheres of pressure typically required for superconductors that operate near room temperature. If confirmed, that makes the material much more promising for real-world applications.
The material displayed several hallmarks of a superconductor, the team reports. Not only did the electrical resistance suddenly drop as it became superconducting, but the material also expelled magnetic fields and exhibited an abrupt change in its heat capacity, Dias says.
When the researchers put the squeeze on the material in the diamond anvil cell, it suddenly turned from a bluish hue to hot pink. “I had never seen a color change like this in a material,” Dias says. “It was like, wow.” That color change indicated a shift in the electrical properties of the material as it became a superconductor, Dias says. This superconductor might be able to escape the confines of a diamond anvil cell, Dias says, opening it up to practical applications. A technique called strain engineering, for example, could mimic the required pressure. In such a process, researchers grow a material on a surface that constrains growth, putting a strain on the material that replicates the effects of externally applied squeezing.
Still, the research faces significant skepticism, in part because of the firestorm over the team’s earlier publication that claimed the discovery of superconductivity in a compound of carbon, sulfur and hydrogen at 15° C (SN: 10/14/20). Editors at Nature retracted that paper, over the objection of Dias and his coauthors, citing irregularities in the researchers’ data handling that undermined the editors’ confidence in the claims (SN: 10/3/22).
Several experts have expressed a lack of confidence in the new results presented by Dias’ group, based on that history. Not only was the previous result retracted, but other researchers were unable to reproduce it, says Eremets, including his own group at the Max Planck Institute. “The main test of validity — reproducibility — was failed, and from my point of view that’s the most important thing.”
The stakes are high. “If it’s true, it’s a great discovery,” says physicist Eugene Gregoryanz of the University of Edinburgh. But he views the researchers with suspicion. “Whether it’s true or not, I guess time will show.”
Others are more positive. “It’s an excellent study,” says materials chemist Russell Hemley of the University of Illinois Chicago. “The data as presented, in terms of evidence for superconductivity, is very strong.” Hemley was not involved with the study but has collaborated with Dias in the past, including on a follow-up to the retracted superconductor paper. Submitted February 16 at arXiv.org, that paper, which has not yet passed peer-review, reports that the previously claimed superconductor does function near room temperature.
The new superconductor is a hydrogen-rich type known as a hydride. Scientists predict that pure hydrogen should be a room-temperature superconductor, but only at extremely high pressures that make it difficult to produce. To lower the pressure, scientists have added in other elements, making hydride superconductors.
In 2015, Eremets and colleagues produced a compound of sulfur and hydrogen that was superconducting up to −70° C, a record high temperature at the time (SN: 12/15/15). A few years later, a compound of lanthanum and hydrogen was found to superconduct under still chilly conditions, but even closer to room temperature (SN: 9/10/18). Both materials require pressures too high for practical use.
It’s difficult to understand how the new superconductor fits in with other hydrides. Theoretical calculations of how similar hydrides behave wouldn’t suggest that such a material would be superconducting at the reported temperatures and pressures, says theoretical physicist Lilia Boeri of the Sapienza University of Rome. “For me, it looks very strange,” Boeri says. “It’s something completely unexpected…. If it’s true, it’s very different from the other hydrides.”
WASHINGTON — The tale of the first horseback riders may be written on the bones of the ancient Yamnaya people.
Five excavated skeletons dated to about 3000 to 2500 B.C. show clear signs of physical stress that hint these Yamnaya individuals may have frequently ridden horses, researchers reported March 3 at the American Association for the Advancement of Science Annual Meeting and in Science Advances. That makes the Yamnaya the earliest humans identified as likely horseback riders so far. Five thousand years ago, the Yamnaya migrated widely, spreading Indo-European languages and altering the human gene pool across Europe and Asia (SN: 11/15/17; SN: 9/5/19). Their travels eventually stretched from modern-day Hungary to Mongolia, roughly 4,500 kilometers, and are thought to have taken place over only a couple of centuries.
“In many ways, [the Yamnaya] changed the history of Eurasia,” says archaeologist Volker Heyd of the University of Helsinki.
Horse domestication became widely established around 3500 B.C., probably for milk and meat (SN: 7/6/17). Some researchers have suggested the Botai people in modern-day Kazakhstan started riding horses during that time, but that’s debated (SN: 3/5/09). The Yamnaya had horses as well, and archaeologists have speculated that the people probably rode them, but evidence was lacking.
But the oldest known depictions of horseback riding are from about 2000 B.C. Complicating efforts to determine when the behavior emerged, possible riding gear would have been made of long-decayed natural materials, and scientists rarely, if ever, find complete horse skeletons from that time. Heyd and colleagues weren’t seeking evidence of horsemanship. They were working on a massive project called the Yamnaya Impact on Prehistoric Europe to understand every aspect of the people’s lives.
While assessing over 200 human skeletons excavated from countries including Romania, Bulgaria and Hungary, bioanthropologist Martin Trautmann noticed that one individual’s bones carried distinct traits on the femur and elsewhere that he’d seen before. He immediately suspected horseback riding.
“It was just kind of a surprise,” says Trautmann, also of the University of Helsinki.
If it were a one-off case, he says he would have dismissed it. But as he continued analyzing skeletons, he noticed that several had the same traits.
Trautmann, Heyd and colleagues assessed all the skeletons for the presence of six physical signs of horseback riding that have been documented in previous research, a constellation of traits dubbed horsemanship syndrome. These signs included pelvis and femur marks that could have come from the biomechanical stress of sitting with spread legs while holding onto a horse, as well as healed vertebrae damage from injuries that could have come from falling off. The team also created a scoring system to account for the skeletal traits’ severity, preservation and relative importance.
“Bones are living tissue,” Trautmann says. “So they react to any type of environmental stimulus.”
The team deemed five Yamnaya male individuals as frequent horseback riders because they had four or more signs of horsemanship. Nine other Yamnaya males probably rode horses, but the researchers were less confident because the skeletons each displayed only three markers. “Hypothetically speaking, it’s very logical,” says bioarchaeologist Maria Mednikova of the Russian Academy of Sciences in Moscow, who was not involved in the new study. The Yamnaya were very close to horses, she says, so at some point, they probably experimented with riding.
She now plans to check for the horse-riding traits in the Yamnaya skeletons she has access to. “The human skeletal system is like a book — if you have some knowledge, you can read it,” Mednikova says.
Archaeologist Ursula Brosseder, who also was not involved in the work, warns not to interpret this finding as equestrianism reaching its full bloom within the Yamnaya culture. Brosseder, formerly of the University of Bonn in Germany, sees the paper’s discovery as humans still figuring out what they could do with horses as part of early domestication.
As for Heyd, he says he has long suspected that the Yamnaya rode horses, considering that they had the animals and expanded so rapidly across such a large area. “Now, we have proof.”
For generations of dogs, home is the radioactive remains of the Chernobyl Nuclear Power Plant.
In the first genetic analysis of these animals, scientists have discovered that dogs living in the power plant industrial area are genetically distinct from dogs living farther away.
Though the team could distinguish between dog populations, the researchers did not pinpoint radiation as the reason for any genetic differences. But future studies that build on the findings, reported March 3 in Science Advances, may help uncover how radioactive environments leave their mark on animal genomes. That could have implications for other nuclear disasters and even human space travel, says Timothy Mousseau, an evolutionary ecologist at the University of South Carolina in Columbia. “We have high hopes that what we learn from these dogs … will be of use for understanding human exposures in the future,” he says.
Since his first trip in 1999, Mousseau has stopped counting how many times he’s been to Chernobyl. “I lost track after we hit about 50 visits.”
He first encountered Chernobyl’s semi-feral dogs in 2017, on a trip with the Clean Futures Fund+, an organization that provides veterinary care to the animals. Not much is known about how local dogs survived after the nuclear accident. In 1986, an explosion at one of the power plant’s reactors kicked off a disaster that lofted vast amounts of radioactive isotopes into the air. Contamination from the plant’s radioactive cloud largely settled nearby, in a region now called the Chernobyl Exclusion Zone.
Dogs have lived in the area since the disaster, fed by Chernobyl cleanup workers and tourists. Some 250 strays were living in and around the power plant, among spent fuel-processing facilities and in the shadow of the ruined reactor. Hundreds more roam farther out in the exclusion zone, an area about the size of Yosemite National Park. During Mousseau’s visits, his team collected blood samples from these dogs for DNA analysis, which let the researchers map out the dogs’ complex family structures. “We know who’s related to who,” says Elaine Ostrander, a geneticist at the National Human Genome Research Institute in Bethesda, Md. “We know their heritage.”
The canine packs are not just a hodgepodge of wild feral dogs, she says. “There are actually families of dogs breeding, living, existing in the power plant,” she says. “Who would have imagined?”
Dogs within the exclusion zone share ancestry with German shepherds and other shepherd breeds, like many other free-breeding dogs from Eastern Europe, the team reports. And though their work revealed that dogs in the power plant area look genetically different from dogs in Chernobyl City, about 15 kilometers away, the team does not know whether radiation caused these differences or not, Ostrander says. The dogs may be genetically distinct simply because they’re living in a relatively isolated area.
The new finding is not so surprising, says Jim Smith, an environmental scientist at the University of Portsmouth in England. He was not part of the new study but has worked in this field for decades. He’s concerned that people might assume “that the radiation has something to do with it,” he says. But “there’s no evidence of that.”
Scientists have been trying to pin down how radiation exposure at Chernobyl has affected wildlife for decades (SN: 5/2/14). “We’ve been looking at the consequences for birds and rodents and bacteria and plants,” Mousseau says. His team has found animals with elevated mutation rates, shortened life spans and early-onset cataracts.
It’s not easy to tease out the effects of low-dose radiation among other factors, Smith says. “[These studies] are so hard … there’s lots of other stuff going in the natural environment.” What’s more, animals can reap some benefits when humans leave contaminated zones, he says.
How, or if, radiation damage is piling up in dogs’ genomes is something the team is looking into now, Ostrander says. Knowing the dogs’ genetic backgrounds will make it easier to spot any radiation red flags, says Bridgett vonHoldt, an evolutionary geneticist at Princeton University, who was not involved in the work.
“I feel like it’s a cliffhanger,” she says. “I want to know more.”
A form of lightning with a knack for sparking wildfires may surge under climate change.
An analysis of satellite data suggests “hot lightning” — strikes that channel electrical charge for an extended period — may be more likely to set landscapes ablaze than more ephemeral flashes, researchers report February 10 in Nature Communications. Each 1 degree Celsius of warming could spur a 10 percent increase in the most incendiary of these Promethean bolts, boosting their flash rate to about four times per second by 2090 — up from nearly three times per second in 2011. That’s dangerous, warns physicist Francisco Javier Pérez-Invernón of the Institute of Astrophysics of Andalusia in Granada, Spain. “There will be more risk of lightning-ignited wildfires.”
Among all the forces of nature, lightning sets off the most blazes. Flashes that touch down amid minimal or no rainfall — known as dry lightning — are especially effective fire starters. These bolts have initiated some of the most destructive wildfires in recent years, such as the 2020 blazes in California (SN: 12/21/20).
But more than parched circumstances can influence a blast’s ability to spark flames. Field observations and laboratory experiments have suggested the most enduring form of hot lightning — “long continuing current lightning”— may be especially combustible. These strikes channel current for more than 40 milliseconds. Some last longer than one-third of a second — the typical duration of a human eye blink.
“This type of lightning can transport a huge amount of electrical discharge from clouds to the ground or to vegetation,” Pérez-Invernón says. Hot lightning’s flair for fire is analogous to lighting a candle; the more time a wick or vegetation is exposed to incendiary energy, the easier it kindles.
Previous research has proposed lightning may surge under climate change (SN: 11/13/14). But it has remained less clear how hot lightning — and its ability to spark wildfires — might evolve.
Pérez-Invernón and his colleagues examined the relationship between hot lightning and U.S. wildfires, using lightning data collected by a weather satellite and wildfire data from 1992 to 2018.
Long continuing current lightning could have sparked up to 90 percent of the roughly 5,600 blazes encompassed in the analysis, the team found. Since less than 10 percent of all lightning strikes during the summer in the western United States have long continuing current, the relatively high ignition count led the researchers to infer that flashes of hot lightning were more prone to sparking fire than typical bolts. The researchers also probed the repercussions of climate change. They ran computer simulations of the global activity of lightning during 2009 to 2011 and from 2090 to 2095, under a future scenario in which annual greenhouse gas emissions peak in 2080 and then decline.
The team found that in the later period, climate change may boost updraft within thunderstorms, causing hot lightning flashes to increase in frequency to about 4 strikes per second globally — about a 40 percent increase from 2011. Meanwhile, the rate of all cloud-to-ground strikes might increase to nearly 8 flashes per second, a 28 percent increase.
After accounting for changes in precipitation, humidity and temperature, the researchers predicted wildfire risk will significantly increase in Southeast Asia, South America, Africa and Australia, and risk will go up most dramatically in North America and Europe. However, risk may decrease in many polar regions, where rainfall is projected to increase while hot lightning rates remain constant.
It’s valuable to show that risk may evolve differently in different places, says Earth systems scientist Yang Chen of the University of California, Irvine, who was not involved in the study. But, he notes, the analysis uses sparse data from polar regions, so there is a lot of uncertainty. Harnessing additional data from ground-based lightning detectors and other data sources could help, he says. “That [region is] important, because a lot of carbon can be released from permafrost.”
Pérez-Invernón agrees more data will help improve projections of rates of lightning-induced wildfire, not just in the polar regions, but also in Africa, where blazes are common but fire reports are lacking.
To shrink error rates in quantum computers, sometimes more is better. More qubits, that is.
The quantum bits, or qubits, that make up a quantum computer are prone to mistakes that could render a calculation useless if not corrected. To reduce that error rate, scientists aim to build a computer that can correct its own errors. Such a machine would combine the powers of multiple fallible qubits into one improved qubit, called a “logical qubit,” that can be used to make calculations (SN: 6/22/20).
Scientists now have demonstrated a key milestone in quantum error correction. Scaling up the number of qubits in a logical qubit can make it less error-prone, researchers at Google report February 22 in Nature. Future quantum computers could solve problems impossible for even the most powerful traditional computers (SN: 6/29/17). To build those mighty quantum machines, researchers agree that they’ll need to use error correction to dramatically shrink error rates. While scientists have previously demonstrated that they can detect and correct simple errors in small-scale quantum computers, error correction is still in its early stages (SN: 10/4/21).
The new advance doesn’t mean researchers are ready to build a fully error-corrected quantum computer, “however, it does demonstrate that it is indeed possible, that error correction fundamentally works,” physicist Julian Kelly of Google Quantum AI said in a news briefing February 21. Logical qubits store information redundantly in multiple physical qubits. That redundancy allows a quantum computer to check if any mistakes have cropped up and fix them on the fly. Ideally, the larger the logical qubit, the smaller the error rate should be. But if the original qubits are too faulty, adding in more of them will cause more problems than it solves.
Using Google’s Sycamore quantum chip, the researchers studied two different sizes of logical qubits, one consisting of 17 qubits and the other of 49 qubits. After making steady improvements to the performance of the original physical qubits that make up the device, the researchers tallied up the errors that still slipped through. The larger logical qubit had a lower error rate, about 2.9 percent per round of error correction, compared to the smaller logical qubit’s rate of about 3.0 percent, the researchers found. That small improvement suggests scientists are finally tiptoeing into the regime where error correction can begin to squelch errors by scaling up. “It’s a major goal to achieve,” says physicist Andreas Wallraff of ETH Zurich, who was not involved with the research.
However, the result is only on the cusp of showing that error correction improves as scientists scale up. A computer simulation of the quantum computer’s performance suggests that, if the logical qubit’s size were increased even more, its error rate would actually get worse. Additional improvement to the original faulty qubits will be needed to enable scientists to really capitalize on the benefits of error correction.
Still, milestones in quantum computation are so difficult to achieve that they’re treated like pole jumping, Wallraff says. You just aim to barely clear the bar.
When New Zealand Prime Minister Jacinda Ardern, who garnered international praise for how she handled the pandemic in her country, recently announced her intention to resign, here’s how she summed up her surprise decision: “I know what the job takes, and I know that I no longer have enough in the tank to do it justice.”
Social scientists and journalists worldwide largely interpreted Ardern’s words in her January 19 speech as a reference to burnout. “She’s talking about an empty tank,” says Christina Maslach, a psychological researcher who has been interviewing and observing workers struggling with workplace-related distress for decades. In almost 50 years of interviews, says Maslach of the University of California, Berkeley, “that phrase [has come] up again and again and again.”
Numerous studies and media reports suggest that burnout, already high before the pandemic, has since skyrocketed worldwide, particularly among workers in certain professions, such as health care, teaching and service. The pandemic makes clear that the jobs needed for a healthy, functioning society are burning people out, Maslach says.
But disagreement over how to define and measure burnout is pervasive, with some researchers even questioning if the syndrome is simply depression by another name. Such controversy has made it difficult to estimate the prevalence of burnout or identify how to best help those who are suffering.
Here are some key questions researchers are asking to get a handle on the problem.
When did today’s understanding of burnout emerge? Some researchers argue that burnout is a strictly modern-day phenomenon, brought on by overwork and hustle culture. But others contend that burnout is merely the latest iteration of a long line of exhaustion disorders, starting with the Ancient Greek concept of acedia. This condition, wrote 5th century monk and theologian John Cassian, is marked by “bodily listlessness and yawning hunger.”
The more contemporary notion of burnout originated in the 1970s. Herbert Freudenberger, the consulting psychologist for volunteers working with drug addicts at St. Mark’s Free Clinic in New York City, used the term to describe the volunteers’ gradual loss of motivation, emotional depletion and reduced commitment to the cause. Roughly simultaneously, Maslach was interviewing social service workers in California and began observing similar characteristics. That prompted Maslach and her then–graduate student, Susan Jackson, now at Rutgers University in Piscataway, N.J., to develop the first tool to measure burnout, the Maslach Burnout Inventory. The duo defined burnout as comprising of three components: exhaustion, cynicism and inefficacy, or persistent feelings of low personal accomplishment.
Respondents rated statements on a scale from 0 (“never”) to 6 (“daily”). Sample statements read: “I feel emotionally drained from my work” for exhaustion; “I doubt the significance of my work” for cynicism; and “I have accomplished many worthwhile things in this job” for inefficacy. High scores for exhaustion and cynicism, and low scores for inefficacy, indicated that a person was struggling with burnout.
Maslach’s scale turned burnout into a legitimate area of inquiry, says Renzo Bianchi, an occupational health psychologist at the Norwegian University of Science and Technology in Trondheim. “Before [the Maslach Burnout Inventory], burnout was pop psychology.”
What is the best way to define burnout? Maslach’s inventory remains the most widely used tool to study burnout. But many criticize that definition of the syndrome (SN: 10/26/22).
Conceptualizing burnout as a combination of exhaustion, cynicism and inefficacy is “arbitrary,” wrote organizational psychologists Wilmar Schaufeli and Dirk Enzmann in their 1998 book, The Burnout Companion to Study and Practice: A Critical Analysis. “What would have happened if other items had been included? Most likely, other dimensions would have appeared.”
Moreover, those three components and what’s causing them are themselves poorly defined, says work and organizational psychologist Evangelia Demerouti of Eindhoven University of Technology in the Netherlands. For instance, numerous nonwork factors can trigger exhaustion, such as health problems and caregiving responsibilities.
Disagreements over what constitutes burnout, and how to measure the phenomenon, has led to a chaotic body of literature. A key point of contention is how to use Maslach’s inventory. Maslach never designated a cutoff point at which a worker tips from not burnt out to burnt out. Rather the inventory was designed as a tool to help researchers identify patterns of burnout within a given work environment or profession.
But in practice, Maslach has little control over how researchers use the inventory. A review of 182 studies on physician burnout in 45 countries reported in September 2018 in JAMA is illustrative. Almost 86 percent of studies in that review used a version of the Maslach Burnout Inventory. But roughly a quarter of those studies used unofficial versions of Maslach’s scale, such as halving the number of statements or measuring exhaustion only. Those versions are clinically invalid, Maslach contends.
Moreover, most researchers using the inventory, or a modified version, did designate cutoff scores, though teams’ definitions for high, medium and low burnout showed little agreement. Consequently, estimates for the prevalence of physician burnout varied from 0 to 80.5 percent — figures that are impossible to interpret, the researchers note.
What’s more, across all the studies, the JAMA team identified 142 definitions of burnout. And among the subset of studies not using a version of the inventory, the researchers identified 11 unique methods for measuring burnout.
Those many concerns are prompting some researchers to call for a return to the drawing board on how to define and measure burnout. That process should start with qualitative interviews to see how people struggling at work speak about their own experiences, Demerouti says. “We don’t [have] a good conceptualization and diagnosis of burnout.… We need to start from scratch.”
Do researchers agree on any features of burnout? Surprisingly, yes. Researchers concur that exhaustion is a core feature of the syndrome, wrote Bianchi and his team in March 2021 in Clinical Psychological Science.
Research in the past two decades is also converging on the idea that burnout appears to involve changes to cognition, such as problems with memory and concentration. Those cognitive problems can take the form of people becoming forgetful — missing a recurring meeting or struggling to perform routine tasks, for instance, says Charlie Renaud, an occupational health psychologist at the University of Rennes in France. Such struggles can carry over into people’s personal lives, causing leisure activities, such as reading and watching movies, to become laborious.
As these findings mount, some researchers have begun to incorporate questions on cognitive changes into their burnout scales, Renaud says. Is burnout a form of depression? At first glance, the two concepts appear contradictory. Depression is typically seen as stemming from within the individual and burnout as stemming from societal forces, chiefly the workplace (SN: 2/12/23). But some researchers have begun to question if burnout exists as a standalone diagnosis. The concepts are not mutually exclusive, research shows. Chronic stress in one’s environment can trigger depression and certain temperaments can make one more prone to burnout.
For instance, scoring high for the personality trait neuroticism — characterized by irritability and a tendency to worry — better predicted a person’s likelihood of experiencing burnout than certain work-related factors, such as poor supervisor support and lack of rapport with colleagues, Bianchi and his team reported in 2018 in Psychiatry Research.
Moreover, exhaustion occurred together with depression more frequently than with either cynicism or inefficacy, Bianchi and his team reported in the 2021 paper. If burnout is characterized by a suite of symptoms, then exhaustion and depression appear a more promising combination than the Maslach trifecta, the team reported.
“The real problem is that we want to believe that burnout is not a depressive condition, [or] as severe as a depressive condition,” Bianchi says. But that, he adds, simply isn’t true.
Should people be able to get a diagnosis of “burnout”? Not everyone thinks that’s a good idea. “Burnout was never, ever thought of as a clinical diagnosis,” Maslach says.
Bianchi and his team disagree. The researchers have developed their own scale, the Occupational Depression Inventory, which assesses nine core symptoms associated with major depression, including cognitive impairment and suicidal thinking, through the lens of work. For instance, instead of rating a statement like “I feel like a failure,” participants rate the statement, “My experience at work made me feel like a failure.”
If burnout is a form of depression, then it can be treated as such, Bianchi says. And, unlike burnout, treatments for depression, such as therapy and, in severe cases, medication, are already established. “Hopefully the interventions, the treatments, the forms of support that exist for depressed people can then be applied for occupational depression,” he says.
But treating the individual, while often a necessary first step, does nothing to alleviate the work-related stress that triggered the crisis, says occupational health psychologist Kirsi Ahola of the Finnish Institute of Occupational Health in Helsinki. “[Imagine] the person is on sick leave, for example, for a few weeks and recuperates and rests … and he comes back to the exactly same situation where the demands are too high and no support and whatever. Then he or she starts burning out again.” That cycle is difficult to break.
Burnout is not included in the American Psychiatric Association’s current Diagnostic and Statistical Manual. The World Health Organization adopted Maslach’s conceptualization of burnout when they outlined the syndrome in their 2019 International Classification of Diseases. Burnout constitutes “an occupational phenomenon,” not a medical condition, the agency noted.
With the evidence so murky, is there any help for people struggling at work? Most researchers agree that interventions must target work-related distress at all levels, from the individual to the workplace to governing bodies.
Interventions at the individual level include therapy, exercise, developing hobbies outside of work and crafting one’s job to better fit one’s goals (SN: 1/10/23). Additionally, cognitive training programs that help restore memory, attention and other cognitive deficits have shown promise in alleviating the cognitive problems associated with burnout, Renaud and University of Rennes developmental psychologist Agnès Lacroix reported January 2 in the International Journal of Stress Management.
At the workplace level, simple fixes, such as fewer video meetings and reducing distractions during the workday, can alleviate distress (SN: 4/7/21). It’s time to chip away at all the little changes that have increased people’s workload over time, Maslach says. “Everybody adds stuff to people’s work. They never subtract.”
Ultimately, though, it may take systemic changes, such as more stringent labor laws, to combat burnout in countries like the United States, where sick leave is seldom guaranteed and few rules protect employees from overwork and job insecurity.
But even without regulations forcing employers’ hands, governments and companies that prioritize healthy workplaces have a competitive advantage. “When people are feeling well and cope well and have energy, they are also better workers,” Ahola says.
Scientists have identified the stem cells behind the liver’s legendary ability to replenish its tissue.
Stem cells not only bolster their own numbers but also become other kinds of cells through a process called differentiation, thereby keeping an organ populated as mature cells die off. The stem cells underpinning this process in the liver had never been identified.
To trace the lineage of liver cells, scientists used a telltale marker — the cells’ response to signals delivered by a known stem-cell regulator called Wnt. In mice, a gene called Axin2 became more active when Wnt was present. Using a fluorescent tag to track cells with these Wnt-responsive genes, the scientists were drawn to a cluster of cells around the central vein in the liver. A population of cells there behaved like stem cells. Specifically, the Axin2-producing cells self-renewed, a cardinal characteristic of a stem cell. They also looked like stem cells, with two copies of each chromosome rather than a multiple chromosome arrangement that mature liver cells often have, the scientists report August 5 in Nature.
