More stories

  • in

    Muon magnetism could hint at a breakdown of physics’ standard model

    A mysterious magnetic property of subatomic particles called muons hints that new fundamental particles may be lurking undiscovered.

    In a painstakingly precise experiment, muons’ gyrations within a magnetic field seem to defy predictions of the standard model of particle physics, which describes known fundamental particles and forces. The result strengthens earlier evidence that muons, the heavy kin of electrons, behave unexpectedly.

    “It’s a very big deal,” says theoretical physicist Bhupal Dev of Washington University in St. Louis. “This could be the long-awaited sign of new physics that we’ve all hoped for.”

    Muons’ misbehavior could point to the existence of new types of particles that alter muons’ magnetic properties. Muons behave like tiny magnets, each with a north and south pole. The strength of that magnet is tweaked by transient quantum particles that constantly flit into and out of existence, adjusting the muon’s magnetism by an amount known as the muon magnetic anomaly. Physicists can predict the value of the magnetic anomaly by considering the contributions of all known particles. If any fundamental particles are in hiding, their additional effects on the magnetic anomaly could give them away.

    Sign Up For the Latest from Science News

    Headlines and summaries of the latest Science News articles, delivered to your inbox

    Muons and electrons share a family resemblance, but muons are about 200 times as massive. That makes muons more sensitive to the effects of hypothetical heavy particles. “The muon kind of hits the sweet spot,” says Aida El-Khadra of the University of Illinois at Urbana-Champaign.

    To measure the magnetic subtleties of the muon, physicists flung billions of the particles around the huge, doughnut-shaped magnet of the Muon g−2 experiment at Fermilab in Batavia, Ill. (SN: 9/19/18). Inside that magnet, the orientation of the muons’ magnetic poles wobbled, or precessed. Notably, the rate of that precession diverged slightly from the standard model expectation, physicists report April 7 in a virtual seminar, and in a paper published in Physical Review Letters.

    “This is a really complex experiment,” says Tsutomu Mibe of the KEK High Energy Accelerator Research Organization in Japan. “This is excellent work.”

    To avoid bias, the team worked under self-imposed secrecy, keeping the final number hidden from themselves as they analyzed the data. At the moment the answer was finally revealed, says physicist Meghna Bhattacharya of the University of Mississippi in Oxford, “I was having goose bumps.” The researchers found a muon magnetic anomaly of 0.00116592040, accurate to within 46 millionths of a percent. The theoretical prediction pegs the number at 0.00116591810. That discrepancy “hints toward new physics,” Bhattacharya says.

    A previous measurement of this type, from an experiment completed in 2001 at Brookhaven National Laboratory in Upton, N.Y., also seemed to disagree with theoretical predictions  (SN: 2/15/01). When the new result is combined with the earlier discrepancy, the measurement diverges from the prediction by a statistical measure of 4.2 sigma — tantalizingly close to the typical five-sigma benchmark for claiming a discovery. “We have to wait for more data from the Fermilab experiment to really be convinced that this is a real discovery, but it is becoming more and more interesting,” says theoretical physicist Carlos Wagner of the University of Chicago.

    According to quantum physics, muons are constantly emitting and absorbing particles in a frenzy that makes theoretical calculations of the magnetic anomaly extremely complex. An international team of more than 170 physicists, co-led by El-Khadra, finalized the theoretical prediction in December 2020 in Physics Reports.

    Many physicists believe that this theoretical prediction is solid, and unlikely to budge with further investigation. But some debate lingers. Using a computational technique called lattice QCD for a particularly thorny part of the calculation gives an estimate that falls closer to the experimentally measured value, physicist Zoltan Fodor and colleagues report April 7 in Nature. If Fodor and colleagues’ calculation is correct, “it could change how we see the experiment,” says Fodor, of Pennsylvania State University, perhaps making it easier to explain the experimental results with the standard model. But he notes that his team’s prediction would need to be confirmed by other calculations before being taken as seriously as the “gold standard” prediction.

    As theoretical physicists continue to refine their predictions, experimental estimates will improve too: Muon g−2 (pronounced gee-minus-two) physicists have analyzed only a fraction of their data so far. And Mibe and colleagues are planning an experiment using a different technique at J-PARC, the Japan Proton Accelerator Research Complex in Tokai, to begin in 2025.

    If the discrepancy between experiment and prediction holds up, scientists will need to find an explanation that goes beyond the standard model. Physicists already believe that the standard model can’t explain everything that’s out there: The universe seems to be pervaded by invisible dark matter, for example, that standard model particles can’t account for.

    Some physicists speculate that the explanation for the muon magnetic anomaly may be connected to known puzzles of particle physics. For example, a new particle might simultaneously explain dark matter and the Muon g−2 result. Or there may be a connection to unexpected features of certain particle decays observed in the LHCb experiment at the CERN particle physics lab near Geneva (SN: 4/20/17), recently strengthened by new results posted at arXiv.org on March 22.

    The Muon g−2 measurement will intensify such investigations, says Muon g−2 physicist Jason Crnkovic of the University of Mississippi. “This is an exciting result because it’s going to generate a lot of conversations.” More

  • in

    Do school-based interventions help improve reading and math in at-risk children?

    School-based interventions that target students with, or at risk of, academic difficulties in kindergarten to grade 6 have positive effects on reading and mathematics, according to an article published in Campbell Systematic Reviews.
    The review analyzed evidence from 205 studies, 186 of which were randomized controlled trials, to examine the effects of targeted school-based interventions on students’ performance on standardized tests in reading and math.
    Peer-assisted instruction and small-group instruction by adults were among the most effective interventions. The authors noted that these have substantial potential to boost skills in students experiencing academic difficulties.
    “It is exciting to see that there are many interventions with substantial impacts on math and reading skills, especially in these times when many students have not been able to attend school and the number of students who need extra help may be even larger than usual,” said lead author Jens Dietrichson, PhD, of VIVE, the Danish Center for Social Science Research. “It is also interesting that there is large variation: far from all interventions have positive effects, and there are substantial and robust differences between the types of interventions. Thus, schools can boost the skills of students with difficulties by implementing targeted interventions, but it matters greatly how they do it.”
    Story Source:
    Materials provided by Wiley. Note: Content may be edited for style and length. More

  • in

    The incredible bacterial 'homing missiles' that scientists want to harness

    Imagine there are arrows that are lethal when fired on your enemies yet harmless if they fall on your friends. It’s easy to see how these would be an amazing advantage in warfare, if they were real. However, something just like these arrows does indeed exist, and they are used in warfare … just on a different scale.
    These weapons are called tailocins, and the reality is almost stranger than fiction.
    “Tailocins are extremely strong protein nanomachines made by bacteria,” explained Vivek Mutalik, a research scientist at Lawrence Berkeley National Laboratory (Berkeley Lab) who studies tailocins and phages, the bacteria-infecting viruses that tailocins appear to be remnants of. “They look like phages but they don’t have the capsid, which is the ‘head’ of the phage that contains the viral DNA and replication machinery. So, they’re like a spring-powered needle that goes and sits on the target cell, then appears to poke all the way through the cell membrane making a hole to the cytoplasm, so the cell loses its ions and contents and collapses.”
    A wide variety of bacteria are capable of producing tailocins, and seem to do so under stress conditions. Because the tailocins are only lethal to specific strains — so specific, in fact, that they have earned the nickname “bacterial homing missiles” — tailocins appear to be a tool used by bacteria to compete with their rivals. Due to their similarity with phages, scientists believe that the tailocins are produced by DNA that was originally inserted into bacterial genomes during viral infections (viruses give their hosts instructions to make more of themselves), and over evolutionary time, the bacteria discarded the parts of the phage DNA that weren’t beneficial but kept the parts that could be co-opted for their own benefit.
    But, unlike most abilities that are selected through evolution, tailocins do not save the individual. According to Mutalik, bacteria are killed if they produce tailocins, just as they would be if they were infected by true phage virus, because the pointed nanomachines erupt through the membrane to exit the producing cell much like replicated viral particles. But once released, the tailocins only target certain strains, sparing the other cells of the host lineage.
    “They benefit kin but the individual is sacrificed, which is a type of altruistic behavior. But we don’t yet understand how this phenomenon happens in nature,” said Mutalik. Scientists also don’t know precisely how the stabbing needle plunger of the tailocin functions. More

  • in

    Scientists harness chaos to protect devices from hackers

    Researchers have found a way to use chaos to help develop digital fingerprints for electronic devices that may be unique enough to foil even the most sophisticated hackers.
    Just how unique are these fingerprints? The researchers believe it would take longer than the lifetime of the universe to test for every possible combination available.
    “In our system, chaos is very, very good,” said Daniel Gauthier, senior author of the study and professor of physics at The Ohio State University.
    The study was recently published online in the journal IEEE Access.
    The researchers created a new version of an emerging technology called physically unclonable functions, or PUFs, that are built into computer chips.
    Gauthier said these new PUFs could potentially be used to create secure ID cards, to track goods in supply chains and as part of authentication applications, where it is vital to know that you’re not communicating with an impostor. More

  • in

    Screening for skin disease on your laptop

    The founding chair of the Biomedical Engineering Department at the University of Houston is reporting a new deep neural network architecture that provides early diagnosis of systemic sclerosis (SSc), a rare autoimmune disease marked by hardened or fibrous skin and internal organs. The proposed network, implemented using a standard laptop computer (2.5 GHz Intel Core i7), can immediately differentiate between images of healthy skin and skin with systemic sclerosis.
    “Our preliminary study, intended to show the efficacy of the proposed network architecture, holds promise in the characterization of SSc,” reports Metin Akay, John S. Dunn Endowed Chair Professor of biomedical engineering. The work is published in the IEEE Open Journal of Engineering in Medicine and Biology.
    “We believe that the proposed network architecture could easily be implemented in a clinical setting, providing a simple, inexpensive and accurate screening tool for SSc.”
    For patients with SSc, early diagnosis is critical, but often elusive. Several studies have shown that organ involvement could occur far earlier than expected in the early phase of the disease, but early diagnosis and determining the extent of disease progression pose significant challenge for physicians, even at expert centers, resulting in delays in therapy and management.
    In artificial intelligence, deep learning organizes algorithms into layers (the artificial neural network) that can make its own intelligent decisions. To speed up the learning process, the new network was trained using the parameters of MobileNetV2, a mobile vision application, pre-trained on the ImageNet dataset with 1.4M images.
    “By scanning the images, the network learns from the existing images and decides which new image is normal or in an early or late stage of disease,” said Akay.
    Among several deep learning networks, Convolutional Neural Networks (CNNs) are most commonly used in engineering, medicine and biology, but their success in biomedical applications has been limited due to the size of the available training sets and networks.
    To overcome these difficulties, Akay and partner Yasemin Akay combined the UNet, a modified CNN architecture, with added layers, and they developed a mobile training module. The results showed that the proposed deep learning architecture is superior and better than CNNs for classification of SSc images.
    “After fine tuning, our results showed the proposed network reached 100% accuracy on the training image set, 96.8% accuracy on the validation image set, and 95.2% on the testing image set,” said Yasmin Akay, UH instructional associate professor of biomedical engineering.
    The training time was less than five hours.
    Joining Metin Akay and Yasemin Akay, the paper was co-authored by Yong Du, Cheryl Shersen, Ting Chen and Chandra Mohan, all of University of Houston; and Minghua Wu and Shervin Assassi of the University of Texas Health Science Center (UT Health).
    Story Source:
    Materials provided by University of Houston. Original written by Laurie Fickman. Note: Content may be edited for style and length. More

  • in

    Deep learning networks prefer the human voice — just like us

    The digital revolution is built on a foundation of invisible 1s and 0s called bits. As decades pass, and more and more of the world’s information and knowledge morph into streams of 1s and 0s, the notion that computers prefer to “speak” in binary numbers is rarely questioned. According to new research from Columbia Engineering, this could be about to change.
    A new study from Mechanical Engineering Professor Hod Lipson and his PhD student Boyuan Chen proves that artificial intelligence systems might actually reach higher levels of performance if they are programmed with sound files of human language rather than with numerical data labels. The researchers discovered that in a side-by-side comparison, a neural network whose “training labels” consisted of sound files reached higher levels of performance in identifying objects in images, compared to another network that had been programmed in a more traditional manner, using simple binary inputs.
    “To understand why this finding is significant,” said Lipson, James and Sally Scapa Professor of Innovation and a member of Columbia’s Data Science Institute, “It’s useful to understand how neural networks are usually programmed, and why using the sound of the human voice is a radical experiment.”
    When used to convey information, the language of binary numbers is compact and precise. In contrast, spoken human language is more tonal and analog, and, when captured in a digital file, non-binary. Because numbers are such an efficient way to digitize data, programmers rarely deviate from a numbers-driven process when they develop a neural network.
    Lipson, a highly regarded roboticist, and Chen, a former concert pianist, had a hunch that neural networks might not be reaching their full potential. They speculated that neural networks might learn faster and better if the systems were “trained” to recognize animals, for instance, by using the power of one of the world’s most highly evolved sounds — the human voice uttering specific words.
    One of the more common exercises AI researchers use to test out the merits of a new machine learning technique is to train a neural network to recognize specific objects and animals in a collection of different photographs. To check their hypothesis, Chen, Lipson and two students, Yu Li and Sunand Raghupathi, set up a controlled experiment. They created two new neural networks with the goal of training both of them to recognize 10 different types of objects in a collection of 50,000 photographs known as “training images.”
    One AI system was trained the traditional way, by uploading a giant data table containing thousands of rows, each row corresponding to a single training photo. The first column was an image file containing a photo of a particular object or animal; the next 10 columns corresponded to 10 possible object types: cats, dogs, airplanes, etc. A “1” in any column indicates the correct answer, and nine 0s indicate the incorrect answers. More

  • in

    Understanding fruit fly behavior may be next step toward autonomous vehicles

    With over 70% of respondents to a AAA annual survey on autonomous driving reporting they would fear being in a fully self-driving car, makers like Tesla may be back to the drawing board before rolling out fully autonomous self-driving systems. But new research from Northwestern University shows us we may be better off putting fruit flies behind the wheel instead of robots.
    Drosophila have been subjects of science as long as humans have been running experiments in labs. But given their size, it’s easy to wonder what can be learned by observing them. Research published today in the journal Nature Communications demonstrates that fruit flies use decision-making, learning and memory to perform simple functions like escaping heat. And researchers are using this understanding to challenge the way we think about self-driving cars.
    “The discovery that flexible decision-making, learning and memory are used by flies during such a simple navigational task is both novel and surprising,” said Marco Gallio, the corresponding author on the study. “It may make us rethink what we need to do to program safe and flexible self-driving vehicles.”
    According to Gallio, an associate professor of neurobiology in the Weinberg College of Arts and Sciences, the questions behind this study are similar to those vexing engineers building cars that move on their own. How does a fruit fly (or a car) cope with novelty? How can we build a car that is flexibly able to adapt to new conditions?
    This discovery reveals brain functions in the household pest that are typically associated with more complex brains like those of mice and humans.
    “Animal behavior, especially that of insects, is often considered largely fixed and hard-wired — like machines,” Gallio said. “Most people have a hard time imagining that animals as different from us as a fruit fly may possess complex brain functions, such as the ability to learn, remember or make decisions.”
    To study how fruit flies tend to escape heat, the Gallio lab built a tiny plastic chamber with four floor tiles whose temperatures could be independently controlled and confined flies inside. They then used high-resolution video recordings to map how a fly reacted when it encountered a boundary between a warm tile and a cool tile. They found flies were remarkably good at treating heat boundaries as invisible barriers to avoid pain or harm. More

  • in

    A spike in Arctic lightning strikes may be linked to climate change

    Climate change may be sparking more lightning in the Arctic.

    Data from a worldwide network of lightning sensors suggest that the frequency of lightning strikes in the region has shot up over the last decade, researchers report online March 22 in Geophysical Research Letters. That may be because the Arctic, historically too cold to fuel many thunderstorms, is heating up twice as fast as the rest of the world (SN: 8/2/19).

    The new analysis used observations from the World Wide Lightning Location Network, which has sensors across the globe that detect radio waves emitted by lightning bolts. Researchers tallied lightning strikes in the Arctic during the stormiest months of June, July and August from 2010 to 2020. The team counted everywhere above 65° N latitude, which cuts through the middle of Alaska, as the Arctic.

    The number of lightning strikes that the detection network precisely located in the Arctic spiked from about 35,000 in 2010 to about 240,000 in 2020. Part of that uptick in detections may have resulted from the sensor network expanding from about 40 stations to more than 60 stations over the decade.

    Sign Up For the Latest from Science News

    Headlines and summaries of the latest Science News articles, delivered to your inbox

    And just looking at the 2010 and 2020 values alone may overstate the increase in lightning, because “there’s such variability, year to year,” and 2020 was a particularly stormy year, says Robert Holzworth, an atmospheric and space scientist at the University of Washington in Seattle. In estimating the increase in average annual lightning strikes, “I would argue that we have really good evidence that the number of strokes in the Arctic has increased by, say, 300 percent,” Holzworth says.

    That increase happened while global summertime temperatures rose from about 0.7 degrees Celsius above the 20th century average to about 0.9 degrees C above — hinting that global warming may create more favorable conditions for lightning in the Arctic.

    It makes sense that a warmer climate could generate more lightning in historically colder climes, says Sander Veraverbeke, an earth systems scientist at VU University Amsterdam who was not involved in the work. If it does, that could potentially ignite more wildfires (SN: 4/11/19). But the apparent trend in Arctic lightning strikes should be taken with a grain of salt because it covers such a short period of time and the detection network includes few observing stations at high latitudes, Veraverbeke says. “We need more stations in the high north to really accurately monitor the lightning there.” More