A misfit gang of superconducting materials may be losing their outsider status.

Certain copper-based compounds superconduct, or transmit electricity without resistance, at unusually high temperatures. It was thought that the standard theory of superconductivity, known as Bardeen-Cooper-Schrieffer theory, couldn’t explain these oddballs. But new evidence suggests that the standard theory applies despite the materials’ quirks, researchers report in the Dec. 8 Physical Review Letters.

All known superconductors must be chilled to work. Most must be cooled to temperatures that hover above absolute zero (–273.15° Celsius). But some copper-based superconductors work at temperatures above the boiling point of liquid nitrogen (around –196° C). Finding a superconductor that functions at even higher temperatures — above room temperature — could provide massive energy savings and new technologies (SN: 12/26/15, p. 25). So scientists are intent upon understanding the physics behind known high-temperature superconductors.
When placed in a magnetic field, many superconductors display swirling vortices of electric current — a hallmark of the standard superconductivity theory. But for the copper-based superconductors, known as cuprates, scientists couldn’t find whirls that matched the theory’s predictions, suggesting that a different theory was needed to explain how the materials superconduct. “This was one of the remaining mysteries,” says physicist Christoph Renner of the University of Geneva. Now, Renner and colleagues have found vortices that agree with the theory in a high-temperature copper-based superconductor, studying a compound of yttrium, barium, copper and oxygen.

Vortices in superconductors can be probed with a scanning tunneling microscope. As the microscope tip moves over a vortex, the instrument records a change in the electrical current. Renner and colleagues realized that, in their copper compound, there were two contributions to the current that the probe was measuring, one from superconducting electrons and one from nonsuperconducting ones. The nonsuperconducting contribution was present across the entire surface of the material and masked the signature of the vortices.

Subtracting the nonsuperconducting portion revealed the vortices, which behaved in agreement with the standard superconductivity theory. “That, I think, is quite astonishing; it’s quite a feat,” says Mikael Fogelström of Chalmers University of Technology in Gothenburg, Sweden, who was not involved with the research.
The result lifts some of the fog surrounding cuprates, which have so far resisted theoretical explanation. But plenty of questions still surround the materials, Fogelström says. “It leaves many things still open, but it sort of gives a new picture.”

One person infected with strep bacteria might get a painful sore throat; another might face a life-threatening blood infection. Now, scientists are trying to pin down why.

Variation between individuals’ immune systems may not be entirely to blame. Instead, extra genes picked up by some pathogens can cause different strains to have wildly different effects on the immune system, even in the same person, researchers report January 11 in PLOS Pathogens.

The idea that different strains of bacteria can behave differently in the body isn’t new. Take E. coli: Some strains of the bacteria that can cause foodborne illness make people far sicker than other strains­. But bacteria have exceptionally large amounts of genetic variation, even between members of the same species. Scientists are still trying to figure out how that genetic diversity affects the way microbes interact with the immune system.
Any species of bacteria has a core set of genes that all its members share. Then there’s a whole pot of genes that different strains of the species pick and choose to create what’s known as an accessory genome. These genes are custom add-ons that specific strains have acquired over time, from their environment or from other microbes — something like an expansion pack for a card game. Sometimes, that extra genetic material gives bacteria new traits.

Uri Sela and his colleagues at the Rockefeller University in New York City tested the way these extra genes influenced the way two common species of bacteria, Staphylococcus aureus and Streptococcus pyogenes, interacted with the immune system. Staphylococcus bacteria can cause everything from rashes to food poisoning to blood infections. Streptococcus bacteria can cause strep throat, as well as a host of more serious illnesses (SN: 10/4/14, p. 22).

Different strains of the same species provoked wildly different immune responses in blood samples collected from the same patient, the researchers first showed. But the strain-specific responses were consistent across patients. Some strains triggered lots of T cells to be made in every sample, for example; others increased B cell activity. (T cells and B cells are the two main weapons of the adaptive immune response, which enables the body to build long-lasting immunity against a particular pathogen.) In tests of strains missing some of their extra genes, though, the T cells didn’t respond as strongly as they did to a matching strain that contained the extra genes. This finding suggests that the variation in immune response across strains was coming, at least in part, from differences in these supplementary genes.
“Currently when a patient comes to the hospital with an infection, we don’t define the strain of the species” for common infections like strep and staph, says Sela, an immunologist. In the future, he says, information about the strain could help doctors predict how a patient’s illness will unfold and decide on the best treatment.

The new study “adds fuel to an active debate” about the role of accessory genes, says Alan McNally, a microbiologist at the University of Birmingham in England — whether or not the collections of genetic add-ons that bacteria maintain are shaped by natural selection, the process that fuels evolution. This research suggests that for some kinds of bacteria, genetic customization might aid survival of certain strains by enabling them to provoke a tailored immune response.

But more research needs to be done to link the strain-to-strain variation in immune response to the accessory genome, he says, as this study looked at only a few extra genes, not the entire accessory genome.

Volcano-fueled holes in Earth’s ozone layer 252 million years ago may have repeatedly sterilized large swaths of forest, setting the stage for the world’s largest mass extinction event. Such holes would have allowed ultraviolet-B radiation to blast the planet. Even radiation levels below those predicted for the end of the Permian period damage trees’ abilities to make seeds, researchers report February 7 in Science Advances.

Jeffrey Benca, a paleobotanist at the University of California, Berkeley, and his colleagues exposed plantings of modern dwarf pine tree (Pinus mugo) to varying levels of UV-B radiation. Those levels ranged from none to up to 93 kilojoules per square meter per day. According to previous simulations, UV-B radiation at the end of the Permian may have increased from a background level of 10 kilojoules (just above current ambient levels) to as much as 100 kilojoules, due to large concentrations of ozone-damaging halogens spewed from volcanoes (SN: 1/15/11, p. 12).

Exposure to higher UV-B levels led to more malformed pollen, the researchers found, with up to 13 percent of the pollen grains deformed under the highest conditions. And although the trees survived the heightened irradiation, the trees’ ovulate cones — cones that, when fertilized by pollen, become seeds — did not. But the trees weren’t permanently sterilized: Once removed from extra UV-B exposure, the trees could reproduce again.

The finding supports previous research suggesting that colossal volcanic eruptions in what’s now Siberia, about 300,000 years before the onset of the extinction event, probably triggered the die-off of nearly all marine species and two-thirds of species living on land (SN: 9/19/15, p. 10). Repeated pulses of volcanism at the end of the Permian may have led to several periods of irradiation that sterilized the forests, causing a catastrophic breakdown of food webs, the researchers say — an indirect but effective way to kill.

AUSTIN, Texas — Stretchy sensors that stick to the throat could track the long-term recovery of stroke survivors.

These new Band-Aid‒shaped devices contain motion sensors that detect muscle movement and vocal cord vibrations. That sensor data could help doctors diagnose and monitor the effectiveness of certain treatments for post-stroke conditions like difficulty swallowing or talking, researchers reported February 17 in a news conference at the annual meeting of the American Association for the Advancement of Science. Up to 65 percent of stroke survivors have trouble swallowing, and about a third of survivors have trouble carrying on conversations.
The devices can monitor speech patterns more reliably than microphones by sensing tissue movement rather than recording sound. “You don’t pick up anything in terms of ambient noise,” says study coauthor John Rogers, a materials scientist and bioengineer at Northwestern University in Evanston, Ill. “You can be next to an airplane jet engine. You’re not going to see that in the [sensor] signal.”

Developed by Rogers’ team, the sensors have built-in 12-hour rechargeable batteries and continually stream motion data to a smartphone. Researchers are now testing the sensors with real stroke patients to see how the devices can be made more user-friendly. For instance, Rogers’ team realized that patients were unlikely to wear sensors that were too easily visible. By equipping the patches with more sensitive motion sensors, they can be worn lower on a person’s neck, hidden behind a buttoned-up shirt, and still pick up throat motion.

These kinds of sensors could also track the recovery of neck cancer patients, who commonly develop swallowing and speaking problems caused by radiation therapy and surgery, Rogers says. The devices can also measure breathing and heart rates to monitor sleep quality and help diagnose sleep apnea. Rogers expects this wearable tech to be ready for widespread use within the next year or two.

With fevers, chills and aches, the flu can pound the body. Some influenza viruses may hammer the brain, too. Months after being infected with influenza, mice had signs of brain damage and memory trouble, researchers report online February 26 in the Journal of Neuroscience.

It’s unclear if people’s memories are affected in the same way as those of mice. But the new research adds to evidence suggesting that some body-wracking infections could also harm the human brain, says epidemiologist and neurologist Mitchell Elkind of Columbia University, who was not involved in the study.
Obvious to anyone who has been waylaid by the flu, brainpower can suffer at the infection’s peak. But not much is known about any potential lingering effects on thinking or memory. “It hasn’t occurred to people that it might be something to test,” says neurobiologist Martin Korte of Technische Universität Braunschweig in Germany.

The new study examined the effects of three types of influenza A — H1N1, the strain behind 2009’s swine flu outbreak; H7N7, a dangerous strain that only rarely infects people; and H3N2, the strain behind much of the 2017–2018 flu season misery (SN: 2/17/18, p. 12). Korte and colleagues shot these viruses into mice’s noses, and then looked for memory problems 30, 60 and 120 days later.

A month after infection, the mice all appeared to have recovered and gained back weight. But those that had received H3N2 and H7N7 had trouble remembering the location of a hidden platform in a pool of water, the researchers found. Mice that received no influenza or the milder H1N1 virus performed normally at the task.
Researchers also studied the brain tissue of the infected mice under a microscope and found that the memory problems tracked with changes in nerve cells. A month after H7N7 or H3N2 infection, mice had fewer nerve cell connectors called dendritic spines on cells in the hippocampus, a brain region involved in memory. Electrical experiments on the nerve cell samples in dishes also suggested the cells’ signal-sending abilities were impaired.
What’s more, these mice’s brains looked inflamed under the microscope, full of immune cells called microglia that were still revved up 30 and 60 days after infection. Cell counts revealed that mice that had suffered through H3N2 or H7N7 had more active microglia than mice infected with H1N1 or no virus at all. That lingering activity was surprising, Korte says; most immune cells in the body usually settle down soon after an infection clears.

These memory problems and signs of brain trouble were gone by 120 days, which translates to about a decade in human time, Korte says. “I’m not saying that everyone who has influenza is cognitively impaired for 10 years,” he says, noting that human brains are much more complex than those of mice. “The news is more that we should not only look at lung functionality after the flu, but also cognitive effects, weeks and months after infection.”

H7N7 can infect brain cells directly. But H1N1 and H3N2 don’t typically get into the brain (and Korte and colleagues confirmed that in their experiments). Some flu viruses may be causing brain trouble remotely, perhaps through inflammatory signals in the blood making their way into the brain, the study suggests. If that pathway is confirmed, then many types of infections could cause similar effects on the brain. “It is plausible that this is a general phenomenon,” Elkind says.

Proxima Centauri has a temper. Earth’s nearest planet-hosting neighbor released a gigantic flare in March 2017, a new analysis of observations of the star shows. And that’s bad news for the potential for life on the star’s planet, Proxima b.

The star got 1,000 times brighter over 10 seconds before dimming again. That can best be explained by an enormous stellar flare, astronomer Meredith MacGregor of the Carnegie Institution for Science in Washington, D.C., and colleagues report February 26 in Astrophysical Journal Letters.
Because Proxima b is so much closer to its star than Earth is to the sun, the flare would have blasted Proxima b with 4,000 times more radiation than Earth typically gets from the sun’s flares. “If there are flares like this at all frequently, then [the exoplanet] is likely not in the best shape,” MacGregor says.

Proxima b was one of the most sought-after sites for finding life outside the solar system. Just four light-years away, it has a mass about the same as Earth’s and probably has temperatures suitable for liquid water (SN: 12/24/16, p. 20). But its star is an M dwarf, a class of small dim stars notoriously prone to flares that could rip away their planets’ atmospheres (SN: 6/24/17, p. 18).
MacGregor and her colleagues reanalyzed data from a recent study led by astronomer Guillem Anglada of the Institute of Astrophysics of Andalusia in Granada, Spain. Anglada and his colleagues had observed Proxima Centauri with the Atacama Large Millimeter Array telescopes in Chile. The team saw extra light that it interpreted as a ring of dust analogous to the solar system’s Kuiper Belt, scattering the light in all directions, the team reported November 15 in Astrophysical Journal Letters.
But Anglada and his colleagues had averaged the amount of light over 10 hours of observations. That smeared out any short-term changes in the star’s brightness — such as a bright flare.

When MacGregor’s team reanalyzed the data, they found that all the excess light came from the same two-minute period on March 24. A massive flare explains all the extra light, she says — none of it was masquerading as a glittering dust ring.

Anglada says he and his colleagues are aware of the March 24 flare and are currently revising their original claim. But he says the flare can’t account for all the extra light, so the dust ring theory might still survive.

Physicist Stephen Hawking, a black hole whisperer who divined secrets of the universe’s most inscrutable objects, died March 14 at age 76. In addition to his scientific research, Hawking, a professor at the University of Cambridge, was known for his popular science books, including the best-selling A Brief History of Time, which captivated readers with lucid explanations of the universe’s birth and the physical laws that rule the cosmos.

In one of his best-known discoveries, Hawking determined that black holes are not truly black. Instead, they emit a faint haze of particles, known as Hawking radiation (SN: 5/31/14, p. 16). This discovery, which arose at the interface of gravity and quantum mechanics, had remarkable consequences. It suggested that black holes are not eternal, but eventually evaporate. That led to a conundrum known as the black hole information paradox (SN: 10/3/15, p. 10): When a black hole disappears, what happens to the information that fell into it? Physicists are still puzzling over that question.

In the face of physical disabilities due to amyotrophic lateral sclerosis, which profoundly limited his mobility and ability to communicate, Hawking became one of science’s most well-known figures, and survived far beyond the timeline initially expected given his condition.

Science News has covered Hawking’s work extensively over the past decades, including his four laws of black hole mechanics, his work on miniature black holes and, most recently, Hawking’s search for a solution to the black hole paradox.

In the United States, cartoon characters are a no-no in cigarette ads, and candy- or fruit-flavored cigarettes can’t be sold. But that’s not the case for e-cigarettes, and these youth-appealing tactics are luring teens who have never used tobacco products to give e-cigs and even cigarettes a try, a new study suggests.

Researchers analyzed surveys of nearly 7,000 kids ages 12 to 17 who had never used a tobacco product as of 2013 to 2014. Teens who recalled seeing or liking e-cigarette ads were 1.6 times as likely to be open to trying e-cigs or to actually try them the next year as kids who didn’t remember the ads, researchers report online March 26 in JAMA Pediatrics. E-cig ads often feature celebrities, cartoons (one product shows a unicorn vomiting a rainbow) or references to sweet flavors, such as Skittles.
Past research has shown a link between traditional cigarette advertisements and receptive nonsmoking adolescents going on to light up. Nearly nine out of 10 smokers tried their first cigarette by age 18. Gearing traditional cigarette ads toward teens has been restricted since 1998.

In 2016, more than 2.1 million U.S. middle and high school students reported using e-cigarettes. That same year, an estimated 20.5 million — or four in five — were exposed to e-cigarette ads.

But e-cigarette ads are doing more than hyping vaping, the study suggests. The ads also appeared to nudge some teens and young adults to take up cigarette smoking. Of a larger group of about 10,500 kids ages 12 to 21 who had never used tobacco products, 18 percent recalled seeing or liking e-cigarette ads but not cigarette ads. Five percent of those teens had started to smoke by the next year.

Extrapolating to the U.S. population, “105,000 12- to 21- year olds appear to have smoked their first cigarette because of the influence of e-cigarette advertising,” says John Pierce, a behavioral epidemiologist at the University of California, San Diego.
Previous research has found that teens who use e-cigarettes are more likely to smoke traditional cigarettes (SN: 9/19/15, p. 14). The fact that e-cigarette ads may up the risk of smoking “raises an unprecedented concern for adolescent tobacco control,” addiction psychologist Adam Leventhal and epidemiologist Jessica L. Barrington-Trimis, both of the University of Southern California’s Keck School of Medicine in Los Angeles, write in an accompanying editorial in the journal.

In an interview, Leventhal adds that restricting such advertising is an important target for public health campaigns and policies to limit youth use of tobacco products.

Birds can sense Earth’s magnetic field, and this uncanny ability may help them fly home from unfamiliar places or navigate migrations that span tens of thousands of kilometers.

For decades, researchers thought iron-rich cells in birds’ beaks acted as microscopic compasses (SN: 5/19/12, p. 8). But in recent years, scientists have found increasing evidence that certain proteins in birds’ eyes might be what allows them to see magnetic fields (SN: 10/28/09, p. 12).

Scientists have now pinpointed a possible protein behind this “sixth sense.” Two new studies — one examining zebra finches published March 28 in Journal of the Royal Society Interface, the other looking at European robins published January 22 in Current Biology — both single out Cry4, a light-sensitive protein found in the retina. If the researchers are correct, this would be the first time a specific molecule responsible for the detection of magnetic fields has been identified in animals.
“This is an exciting advance — we need more papers like these,” says Peter Hore, a chemist at the University of Oxford who has studied chemical reactions involved in bird navigation.

Cry4 is part of a class of proteins called cryptochromes, which are known to be involved in circadian rhythms, or biological sleep cycles (SN: 10/02/17, p. 6). But at least some of these proteins are also thought to react to Earth’s magnetic field thanks to the weirdness of quantum mechanics (SN: 7/23/16, p. 8). The protein’s quantum interactions could help birds sense this field, says Atticus Pinzon-Rodriguez, a biologist at the University of Lund in Sweden who was involved with the zebra finch study.

To figure out which of three cryptochromes is responsible for this quantum compass, Pinzon-Rodriguez and his colleagues examined the retinas, muscles and brains of 39 zebra finches for the presence of the three proteins Cry1, Cry2 and Cry4.
The team found that while levels of Cry1 and Cry2 followed a rhythmic pattern that rose and fell over the day, Cry4 levels remained constant, indicating the protein was being produced steadily.

“We assume that birds use magnetic compasses any time of day or night,” says Lund biologist Rachel Muheim, a coauthor on the zebra finch study.

European robins also showed constant levels of Cry4 during a 24-hour cycle, and higher levels during their migratory season. And the researchers in that study found Cry4 in an area of the robin’s retina that receives a lot of light — a position that would help it work as a compass, the study says.

“We have quite a lot of evidence, but [Cry4] is not proven,” says Henrik Mouritsen, an animal navigation expert at the Institute of Biology and Environmental Sciences in Oldenburg, Germany, who participated in the robin study. More definitive evidence might come from observing birds without a functioning Cry4 protein, to see if they still seem to have an internal compass.

Even then, Hore says, we still may not understand how birds actually perceive magnetic fields. To know, you’d have to be a bird.

There’s a fine line between immersive and unnerving when it comes to touch sensation in virtual reality.

More realistic tactile feedback in VR can ruin a user’s feeling of immersion, researchers report online April 18 in Science Robotics. The finding suggests that the “uncanny valley” — a term that describes how humanoid robots that look almost but not quite human are creepier than their more cartoonish counterparts — also applies to virtual touch (SN Online: 11/22/13).
Experiment participants wearing VR headsets and gripping a controller in each hand embodied a virtual avatar holding the two ends of a stick. At first, users felt no touch sensation. Then, the hand controllers gave equally strong vibrations every half-second. Finally, the vibrations were finely tuned to create the illusion that the virtual stick was being touched in different spots. For instance, stronger vibrations in the right controller gave the impression that the stick was nudged on that side.

Compared with scenarios in which users received either no touch or even buzzing sensations, participants reported feeling far less immersed in the virtual environment when they received the realistic, localized touch. This result demonstrates the existence of a tactile uncanny valley, says study coauthor Mar Gonzalez-Franco, a human-computer interaction researcher at Microsoft Research in Redmond, Washington.

But when users were shown a marble touching the virtual stick wherever they felt the localized touch, the participants found this realistic tactile feedback highly immersive rather than bothersome. The finding indicates that rich tactile feedback in VR may need to be paired with other sensory cues that explain the source of the sensation to avoid spooking users, Gonzalez-Franco says.

Better understanding how realistic touch sensations can break the VR illusion may help developers create more engaging virtual environments for games and virtual reality therapy, says Sean Follmer, a human-computer interaction researcher at Stanford University not involved in the study.