Study finds brain areas involved in seeking information about bad possibilities

The term "doomscrolling" describes the act of endlessly scrolling through bad news on social media and reading every worrisome tidbit that pops up, a habit that unfortunately seems to have become common during the COVID-19 pandemic.

The biology of our brains may play a role in that. Researchers at Washington University School of Medicine in St. Louis have identified specific areas and cells in the brain that become active when an individual is faced with the choice to learn or hide from information about an unwanted aversive event the individual likely has no power to prevent.

The findings, published June 11 in Neuron, could shed light on the processes underlying psychiatric conditions such as obsessive-compulsive disorder and anxiety -- not to mention how all of us cope with the deluge of information that is a feature of modern life.

"People's brains aren't well equipped to deal with the information age," said senior author Ilya Monosov, PhD, an associate professor of neuroscience, of neurosurgery and of biomedical engineering. "People are constantly checking, checking, checking for news, and some of that checking is totally unhelpful. Our modern lifestyles could be resculpting the circuits in our brain that have evolved over millions of years to help us survive in an uncertain and ever-changing world."

In 2019, studying monkeys, Monosov laboratory members J. Kael White, PhD, then a graduate student, and senior scientist Ethan S. Bromberg-Martin, PhD, identified two brain areas involved in tracking uncertainty about positively anticipated events, such as rewards. Activity in those areas drove the monkeys' motivation to find information about good things that may happen.

But it wasn't clear whether the same circuits were involved in seeking information about negatively anticipated events, like punishments. After all, most people want to know whether, for example, a bet on a horse race is likely to pay off big. Not so for bad news.

"In the clinic, when you give some patients the opportunity to get a genetic test to find out if they have, for example, Huntington's disease, some people will go ahead and get the test as soon as they can, while other people will refuse to be tested until symptoms occur," Monosov said. "Clinicians see information-seeking behavior in some people and dread behavior in others."

To find the neural circuits involved in deciding whether to seek information about unwelcome possibilities, first author Ahmad Jezzini, PhD, and Monosov taught two monkeys to recognize when something unpleasant might be headed their way. They trained the monkeys to recognize symbols that indicated they might be about to get an irritating puff of air to the face. For example, the monkeys first were shown one symbol that told them a puff might be coming but with varying degrees of certainty. A few seconds after the first symbol was shown, a second symbol was shown that resolved the animals' uncertainty. It told the monkeys that the puff was definitely coming, or it wasn't.

The researchers measured whether the animals wanted to know what was going to happen by whether they watched for the second signal or averted their eyes or, in separate experiments, letting the monkeys choose among different symbols and their outcomes.

Much like people, the two monkeys had different attitudes toward bad news: One wanted to know; the other preferred not to. The difference in their attitudes toward bad news was striking because they were of like mind when it came to good news. When they were given the option of finding out whether they were about to receive something they liked -- a drop of juice -- they both consistently chose to find out.

"We found that attitudes toward seeking information about negative events can go both ways, even between animals that have the same attitude about positive rewarding events," said Jezzini, who is an instructor in neuroscience. "To us, that was a sign that the two attitudes may be guided by different neural processes."

By precisely measuring neural activity in the brain while the monkeys were faced with these choices, the researchers identified one brain area, the anterior cingulate cortex, that encodes information about attitudes toward good and bad possibilities separately. They found a second brain area, the ventrolateral prefrontal cortex, that contains individual cells whose activity reflects the monkeys' overall attitudes: yes for info on either good or bad possibilities vs. yes for intel on good possibilities only.

Understanding the neural circuits underlying uncertainty is a step toward better therapies for people with conditions such as anxiety and obsessive-compulsive disorder, which involve an inability to tolerate uncertainty.

"We started this study because we wanted to know how the brain encodes our desire to know what our future has in store for us," Monosov said. "We're living in a world our brains didn't evolve for. The constant availability of information is a new challenge for us to deal with. I think understanding the mechanisms of information seeking is quite important for society and for mental health at a population level."

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New discovery shows human cells can write RNA sequences into DNA

Cells contain machinery that duplicates DNA into a new set that goes into a newly formed cell. That same class of machines, called polymerases, also build RNA messages, which are like notes copied from the central DNA repository of recipes, so they can be read more efficiently into proteins. But polymerases were thought to only work in one direction DNA into DNA or RNA. This prevents RNA messages from being rewritten back into the master recipe book of genomic DNA. Now, Thomas Jefferson University researchers provide the first evidence that RNA segments can be written back into DNA, which potentially challenges the central dogma in biology and could have wide implications affecting many fields of biology.

"This work opens the door to many other studies that will help us understand the significance of having a mechanism for converting RNA messages into DNA in our own cells," says Richard Pomerantz, PhD, associate professor of biochemistry and molecular biology at Thomas Jefferson University. "The reality that a human polymerase can do this with high efficiency, raises many questions." For example, this finding suggests that RNA messages can be used as templates for repairing or re-writing genomic DNA.

The work was published June 11th in the journal Science Advances.

Together with first author Gurushankar Chandramouly and other collaborators, Dr. Pomerantz's team started by investigating one very unusual polymerase, called polymerase theta. Of the 14 DNA polymerases in mammalian cells, only three do the bulk of the work of duplicating the entire genome to prepare for cell division. The remaining 11 are mostly involved in detecting and making repairs when there's a break or error in the DNA strands. Polymerase theta repairs DNA, but is very error-prone and makes many errors or mutations. The researchers therefore noticed that some of polymerase theta's "bad" qualities were ones it shared with another cellular machine, albeit one more common in viruses -- the reverse transcriptase. Like Pol theta, HIV reverse transcriptase acts as a DNA polymerase, but can also bind RNA and read RNA back into a DNA strand.

In a series of elegant experiments, the researchers tested polymerase theta against the reverse transcriptase from HIV, which is one of the best studied of its kind. They showed that polymerase theta was capable of converting RNA messages into DNA, which it did as well as HIV reverse transcriptase, and that it actually did a better job than when duplicating DNA to DNA. Polymerase theta was more efficient and introduced fewer errors when using an RNA template to write new DNA messages, than when duplicating DNA into DNA, suggesting that this function could be its primary purpose in the cell.

The group collaborated with Dr. Xiaojiang S. Chen's lab at USC and used x-ray crystallography to define the structure and found that this molecule was able to change shape in order to accommodate the more bulky RNA molecule -- a feat unique among polymerases.

"Our research suggests that polymerase theta's main function is to act as a reverse transcriptase," says Dr. Pomerantz. "In healthy cells, the purpose of this molecule may be toward RNA-mediated DNA repair. In unhealthy cells, such as cancer cells, polymerase theta is highly expressed and promotes cancer cell growth and drug resistance. It will be exciting to further understand how polymerase theta's activity on RNA contributes to DNA repair and cancer-cell proliferation."

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Astronomers spot a 'blinking giant' near the centre of the Galaxy

Astronomers have spotted a giant 'blinking' star towards the centre of the Milky Way, more than 25,000 light years away.

An international team of astronomers observed the star, VVV-WIT-08, decreasing in brightness by a factor of 30, so that it nearly disappeared from the sky. While many stars change in brightness because they pulsate or are eclipsed by another star in a binary system, it's exceptionally rare for a star to become fainter over a period of several months and then brighten again.

The researchers believe that VVV-WIT-08 may belong to a new class of 'blinking giant' binary star system, where a giant star -- 100 times larger than the Sun -- is eclipsed once every few decades by an as-yet unseen orbital companion. The companion, which may be another star or a planet, is surrounded by an opaque disc, which covers the giant star, causing it to disappear and reappear in the sky. The study is published in Monthly Notices of the Royal Astronomical Society.

The discovery was led by Dr Leigh Smith from Cambridge's Institute of Astronomy, working with scientists at the University of Edinburgh, the University of Hertfordshire, the University of Warsaw in Poland and Universidad Andres Bello in Chile.

"It's amazing that we just observed a dark, large and elongated object pass between us and the distant star and we can only speculate what its origin is," said co-author Dr Sergey Koposov from the University of Edinburgh.

Since the star is located in a dense region of the Milky Way, the researchers considered whether some unknown dark object could have simply drifted in front of the giant star by chance. However, simulations showed that there would have to be an implausibly large number of dark bodies floating around the Galaxy for this scenario to be likely.

One other star system of this sort has been known for a long time. The giant star Epsilon Aurigae is partly eclipsed by a huge disc of dust every 27 years, but only dims by about 50%. A second example, TYC 2505-672-1, was found a few years ago, and holds the current record for the eclipsing binary star system with the longest orbital period -- 69 years -- a record for which VVV-WIT-08 is currently a contender.

The UK-based team has also found two more of these peculiar giant stars in addition to VVV-WIT-08, suggesting that these may be a new class of 'blinking giant' stars for astronomers to investigate.

VVV-WIT-08 was found by the VISTA Variables in the Via Lactea survey (VVV), a project using the British-built VISTA telescope in Chile and operated by the European Southern Observatory, that has been observing the same one billion stars for nearly a decade to search for examples with varying brightness in the infrared part of the spectrum.

Project co-leader Professor Philip Lucas from the University of Hertfordshire said, "Occasionally we find variable stars that don't fit into any established category, which we call 'what-is-this?', or 'WIT' objects. We really don't know how these blinking giants came to be. It's exciting to see such discoveries from VVV after so many years planning and gathering the data."

While VVV-WIT-08 was discovered using VVV data, the dimming of the star was also observed by the Optical Gravitational Lensing Experiment (OGLE), a long-running observation campaign run by the University of Warsaw. OGLE makes more frequent observations, but closer to the visible part of the spectrum. These frequent observations were key for modelling VVV-WIT-08, and they showed that the giant star dimmed by the same amount in both the visible and infrared light.

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Star's death will play a mean pinball with rhythmic planets

Four planets locked in a perfect rhythm around a nearby star are destined to be pinballed around their solar system when their sun eventually dies, according to a study led by the University of Warwick that peers into its future.

Astronomers have modelled how the change in gravitational forces in the system as a result of the star becoming a white dwarf will cause its planets to fly loose from their orbits and bounce off each other's gravity, like balls bouncing off a bumper in a game of pinball.

In the process, they will knock nearby debris into their dying sun, offering scientists new insight into how the white dwarfs with polluted atmospheres that we see today originally evolved. The conclusions by astronomers from the University of Warwick and the University of Exeter are published in the Monthly Notices of the Royal Astronomical Society.

The HR 8799 system is 135 light years away and comprises a 30-40 million year-old A type star and four unusually massive planets, all over five times the mass of Jupiter, orbiting very close to each other. The system also contains two debris discs, inside the orbit of the innermost planet and another outside the outermost. Recent research has shown that the four planets are locked in a perfect rhythm that sees each one completing double the orbit of its neighbour: so for every orbit the furthest completes, the next closest completes two, the next completes four, while the closest completes eight.

The team from Warwick and Exeter decided to learn the ultimate fate of the system by creating a model that allowed them to play 'planetary pinball' with the planets, investigating what may cause the perfect rhythm to destabilise.

They determined that the resonance that locks the four planets is likely to hold firm for the next 3 billion years, despite the effects of Galactic tides and close flybys of other stars. However, it always breaks once the star enters the phase in which it becomes a red giant, when it will expand to several hundred times its current size and eject nearly half its mass, ending up as a white dwarf.

The planets will then start to pinball and become a highly chaotic system where their movements become very uncertain. Even changing a planet's position by a centimetre at the start of the process can dramatically change the outcome.

Lead author Dr Dimitri Veras from the University of Warwick Department of Physics said: "The planets will gravitationally scatter off of one another. In one case, the innermost planet could be ejected from the system. Or, in another case, the third planet may be ejected. Or the second and fourth planets could switch positions. Any combination is possible just with little tweaks.

"They are so big and so close to each other the only thing that's keeping them in this perfect rhythm right now is the locations of their orbits. All four are connected in this chain. As soon as the star loses mass their locations will deviate, then two of them will scatter off one another, causing a chain reaction amongst all four."

Dr Veras was supported by an Ernest Rutherford Fellowship from the Science and Technology Facilities Council, part of UK Research and Innovation.

Regardless of the precise movements of the planets, one thing that the team is certain of is that the planets will move around enough to dislodge material from the system's debris discs into the atmosphere of the star. It is this type of debris that astronomers are analysing today to discover the histories of other white dwarf systems.

Dr Veras adds: "These planets move around the white dwarf at different locations and can easily kick whatever debris is still there into the white dwarf, polluting it.

"The HR 8799 planetary system represents a foretaste of the polluted white dwarf systems that we see today. It's a demonstration of the value of computing the fates of planetary systems, rather than just looking at their formation."

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Researchers develop tool to aid in development, efficiency of hydrogen-powered cars

Widespread adoption of hydrogen-powered vehicles over traditional electric vehicles requires fuel cells that can convert hydrogen and oxygen safely into water -- a serious implementation problem.

Researchers at the University of Colorado Boulder are addressing one aspect of that roadblock by developing new computational tools and models needed to better understand and manage the conversion process. Hendrik Heinz, an associate professor in the Department of Chemical and Biological Engineering, is leading the effort in partnership with the University of California Los Angeles. His team recently published new findings on the subject in Science Advances.

Fuel cell electric vehicles combine hydrogen in a tank with oxygen taken from the air to produce the electricity needed to run. They don't need to be plugged in to charge and have the added benefit of producing water vapor as a byproduct. Those, plus other factors, have made them an intriguing option in the green and renewable energy transportation areas.

Heinz said a key goal to making the vehicles viable is to find an effective catalyst in the fuel cell that can "burn" the hydrogen with oxygen under controlled conditions needed for safe travel. At the same time, researchers are looking for a catalyst that can do this at near room temperature, with high efficiency and a long lifetime in acidic solution. Platinum metal is commonly used, but predicting the reactions and best materials to use for scaling up or different conditions has been a challenge to date.

"For decades, researchers have struggled to predict the complex processes needed for this work, though enormous progress has been made using nanoplates, nanowires and many other nanostructures," Heinz said. "To address this, we have developed models for metal nanostructures and oxygen, water and metal interactions that exceed the accuracy of current quantum methods by more than 10 times. The models also enable the inclusion of the solvent and dynamics and reveal quantitative correlations between oxygen accessibility to the surface and catalytic activity in the oxygen reduction reaction."

Heinz said the quantitative simulations his team developed show the interaction between oxygen molecules as they encounter different barriers by molecular layers of water on the platinum surface. These interactions make the difference between a slow or fast follow-on reaction and need to be controlled for the process to work efficiently. These reactions happen quite fast -- the conversion into water takes about a millisecond per square nanometer to complete -- and happen on a tiny catalyst surface. All of those variables come together in an intricate, complex "dance" that his team has found a way to model in predictive ways.

The computational and data-intensive methods described in the paper can be used to create designer-nanostructures that would max out the catalytic efficiency, as well as possible surface modifications to further optimize the cost-benefit ratio of fuel cells, Heinz added. His collaborators are exploring the commercial implication of that aspect, and he is applying the tools to help to study a wider range of potential alloys and gain further insights into the mechanics at play.

"The tools described in the paper, especially the interface force field for order-of-magnitude more reliable molecular dynamics simulations, can also be applied to other catalyst and electrocatalyst interfaces for similar groundbreaking and practically useful advances," he said.

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Cell phone use while driving may be tied to other risky road behaviors in young adults

A new study from researchers at Children's Hospital of Philadelphia (CHOP) and the University of Pennsylvania's Annenberg Public Policy Center found that 18- to 24-year-olds who use cell phones while driving are more likely to engage in other risky driving behaviors associated with "acting-without-thinking," a form of impulsivity. These findings suggest the importance of developing new strategies to prevent risky driving in young adults, especially those with impulsive personalities. The study was recently published in the International Journal of Environmental Research Public Health.

Cell phone use while driving has been linked to increased crash and near-crash risk. Despite bans on handheld cell phone use while driving in many states, crash reduction results are inconsistent. One explanation may be that those who use cell phones while driving are more likely to engage in other intentionally risky behaviors. Instead of solely addressing the use of cell phones while driving, the authors suggest training young drivers to avoid all risky behaviors associated with impulsivity and sensation seeking.

"This study found that frequent cell phone use while driving was only one indicator of a more general pattern of risky driving practices associated with prior crashes in young drivers," said lead study author Elizabeth Walshe, PhD, a research scientist at the Center for Injury Research and Prevention (CIRP) at CHOP and co-leader of CHOP's Neuroscience of Driving research program. "Assessment of personality traits, such as impulsivity and sensation seeking, may be helpful to identify drivers most at risk in order to provide more targeted interventions promoting safe driving."

This retrospective study recruited 384 young drivers from across the U.S. to complete an online survey measuring risky driving practices -- including cell phone use -- as well as history of crashes and impulse-related personality traits. The study found that 44.5% of drivers reported being in at least one crash, and 73% of them reported cell phone use while driving. Those who used cell phones while driving were also more likely to participate in other risky driving behaviors, including ignoring speed limits, aggressively passing vehicles going in the same direction, and running red lights. The use of cell phones was not uniquely associated with prior crashes but was one of several risky activities related to crashes.

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An omega-3 that's poison for tumors

So-called "good fatty acids" are essential for human health and much sought after by those who try to eat healthily. Among the Omega-3 fatty acids, DHA or docosahexaenoic acid is crucial to brain function, vision and the regulation of inflammatory phenomena.

In addition to these virtues, DHA is also associated with a reduction in the incidence of cancer. How it works is the subject of a major discovery by a multidisciplinary team of University of Louvain (UCLouvain) researchers, who have just elucidated the biochemical mechanism that allows DHA and other related fatty acids to slow the development of tumours. This is a major advance that has recently been published in the journal Cell Metabolism.

Key to the discovery: interdisciplinarity

In 2016, Olivier Feron's UCLouvain team, which specialises in oncology, discovered that cells in an acidic microenvironment (acidosis) within tumours replace glucose with lipids as an energy source in order to multiply. In collaboration with UCLouvain's Cyril Corbet, Prof. Feron demonstrated in 2020 that these same cells are the most aggressive and acquire the ability to leave the original tumour to generate metastases. Meanwhile, Yvan Larondelle, a professor in the UCLouvain Faculty of Bioengineering, whose team is developing improved dietary lipid sources, proposed to Prof. Feron that they combine their skills in a research project, led by PhD candidate Emeline Dierge, to evaluate the behaviour of tumour cells in the presence of different fatty acids.

Thanks to the support of the Fondation Louvain, the Belgian Cancer Foundation and the Télévie telethon, the team quickly identified that these acidotic tumour cells responded in diametrically opposite ways depending on the fatty acid they were absorbing. Within a few weeks, the results were both impressive and surprising. "We soon found that certain fatty acids stimulated the tumour cells while others killed them," the researchers explained. DHA literally poisons them.

A fatal overload

The poison acts on tumour cells via a phenomenon called ferroptosis, a type of cell death linked to the peroxidation of certain fatty acids. The greater the amount of unsaturated fatty acids in the cell, the greater the risk of their oxidation. Normally, in the acidic compartment within tumours, cells store these fatty acids in lipid droplets, a kind of bundle in which fatty acids are protected from oxidation. But in the presence of a large amount of DHA, the tumour cell is overwhelmed and cannot store the DHA, which oxidises and leads to cell death. By using a lipid metabolism inhibitor that prevents the formation of lipid droplets, researchers were able to observe that this phenomenon is further amplified, which confirms the identified mechanism and opens the door to combined treatment possibilities.

For their study, UCLouvain researchers used a 3D tumour cell culture system, called spheroids. In the presence of DHA, spheroids first grow and then implode. The team also administered a DHA-enriched diet to mice with tumours. The result: tumour development was significantly slowed compared to that in mice on a conventional diet.

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Astronomers discover a 'changing-look' blazar

A University of Oklahoma doctoral student, graduate and undergraduate research assistants, and an associate professor in the Homer L. Dodge Department of Physics and Astronomy in the University of Oklahoma College of Arts and Sciences are lead authors on a paper describing a "changing-look" blazar -- a powerful active galactic nucleus powered by supermassive blackhole at the center of a galaxy. The paper is published in The Astrophysical Journal.

Hora D. Mishra, a Ph.D. student, and faculty member Xinyu Dai are lead authors of the paper, along with Christopher Kochanek and Kris Stanek at the Ohio State University and Ben Shappee at the University of Hawaii. The paper represents the findings of researchers from 12 different institutions who participated in a two-year collaborative project involving the collection of spectra or imaging data in different electromagnetic bands. The OU team led the effort in analyzing all the data collected from the collaboration and contributed primarily on the interpretation of the analysis results, assisted by OU graduate student Saloni Bhatiani and undergraduate students Cora DeFrancesco and John Cox who performed ancillary analyses to the project.

Blazars, explains Mishra, who also serves as president of Lunar Sooners, appear as parallel rays of light or particles, or jets, pointing to observers and radiating across all wavelengths of the electromagnetic spectrum. These jets span distances on the million light-year scales and are known to impact the evolution of the galaxy and galaxy cluster in which they reside via the radiation. These features make blazars ideal environments in which to study the physics of jets and their role in galaxy evolution.

"Blazars are a unique kind of AGN with very powerful jets," she said. "Jets are a radio mode of feedback and because of their scales, they penetrate the galaxy into their large-scale environment. The origin of these jets and processes driving the radiation are not well-known. Thus, studying blazars allows us to understand these jets better and how they are connected to other components of the AGN, like the accretion disk. These jets can heat up and displace gas in their environment affecting, for example, the star formation in the galaxy."

The team's paper highlights the results of a campaign to investigate the evolution of a blazar known as B2 1420+32. At the end of 2017, this blazar exhibited a huge optical flare, a phenomenon captured by the All Sky Automated Survey for SuperNovae telescope network.

"We followed this up by observing the evolution of its spectrum and light curve over the next two years and also retrieved archival data available for this object," Mishra said. "The campaign, with data spanning over a decade, has yielded some most exciting results. We see dramatic variability in the spectrum and multiple transformations between the two blazar sub-classes for the first time for a blazar, thus giving it the name 'changing-look' blazar."

The team concluded that this behavior is caused by the dramatic continuum flux changes, which confirm a long-proposed theory that separates blazars into two major categories.

"In addition, we see several very large multiband flares in the optical and gamma-ray bands on different timescales and new spectral features," Mishra said. "Such extreme variability and the spectral features demand dedicated searches for more such blazars, which will allow us to utilize the dramatic spectral changes observed to reveal AGN/jet physics, including how dust particles around supermassive black holes are destructed by the tremendous radiation from the central engine and how energy from a relativistic jet is transferred into the dust clouds, providing a new channel linking the evolution of the supermassive black hole with its host galaxy."

"We are very excited by the results of discovering a changing-look blazar that transforms itself not once, but three times, between its two sub-classes, from the dramatic changes in its continuum emission," she added. "In addition, we see new spectral features and optical variability that is unprecedented. These results open the door to more such studies of highly variable blazars and their importance in understanding AGN physics."

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CHIME telescope detects more than 500 mysterious fast radio bursts in its first year of operation

To catch sight of a fast radio burst is to be extremely lucky in where and when you point your radio dish. Fast radio bursts, or FRBs, are oddly bright flashes of light, registering in the radio band of the electromagnetic spectrum, that blaze for a few milliseconds before vanishing without a trace.

These brief and mysterious beacons have been spotted in various and distant parts of the universe, as well as in our own galaxy. Their origins are unknown, and their appearance is unpredictable. Since the first was discovered in 2007, radio astronomers have only caught sight of around 140 bursts in their scopes.

Now, a large stationary radio telescope in British Columbia has nearly quadrupled the number of fast radio bursts discovered to date. The telescope, known as CHIME, for the Canadian Hydrogen Intensity Mapping Experiment, has detected 535 new fast radio bursts during its first year of operation, between 2018 and 2019.

Scientists with the CHIME Collaboration, including researchers at MIT, have assembled the new signals in the telescope's first FRB catalog, which they will present this week at the American Astronomical Society Meeting.

The new catalog significantly expands the current library of known FRBs, and is already yielding clues as to their properties. For instance, the newly discovered bursts appear to fall in two distinct classes: those that repeat, and those that don't. Scientists identified 18 FRB sources that burst repeatedly, while the rest appear to be one-offs. The repeaters also look different, with each burst lasting slightly longer and emitting more focused radio frequencies than bursts from single, nonrepeating FRBs.

These observations strongly suggest that repeaters and one-offs arise from separate mechanisms and astrophysical sources. With more observations, astronomers hope soon to pin down the extreme origins of these curiously bright signals.

"Before CHIME, there were less than 100 total discovered FRBs; now, after one year of observation, we've discovered hundreds more," says CHIME member Kaitlyn Shin, a graduate student in MIT's Department of Physics. "With all these sources, we can really start getting a picture of what FRBs look like as a whole, what astrophysics might be driving these events, and how they can be used to study the universe going forward."

Seeing flashes

CHIME comprises four massive parabolic radio antennas, roughly the size and shape of snowboarding half-pipes, located at the Dominion Radio Astrophysical Observatory in British Columbia, Canada. CHIME is a stationary array, with no moving parts. The telescope receives radio signals each day from half of the sky as the Earth rotates. While most radio astronomy is done by swiveling a large dish to focus light from different parts of the sky, CHIME stares, motionless, at the sky, and focuses incoming signals using a correlator -- a powerful digital signaling processor that can work through huge amounts of data, at a rate of about 7 terabits per second, equivalent to a few percent of the world's internet traffic.

"Digital signal processing is what makes CHIME able to reconstruct and 'look' in thousands of directions simultaneously," says Kiyoshi Masui, assistant professor of physics at MIT, who will lead the group's conference presentation. "That's what helps us detect FRBs a thousand times more often than a traditional telescope."

Over the first year of operation, CHIME detected 535 new fast radio bursts. When the scientists mapped their locations, they found the bursts were evenly distributed in space, seeming to arise from any and all parts of the sky. From the FRBs that CHIME was able to detect, the scientists calculated that fast radio bursts, bright enough to be seen by a telescope like CHIME, occur at a rate of about 9,000 per day across the entire sky -- the most precise estimate of FRBs overall rate to date.

"That's kind of the beautiful thing about this field -- FRBs are really hard to see, but they're not uncommon," says Masui, who is a member of MIT's Kavli Institute for Astrophysics and Space Research. "If your eyes could see radio flashes the way you can see camera flashes, you would see them all the time if you just looked up."

Mapping the universe

As radio waves travel across space, any interstellar gas, or plasma, along the way can distort or disperse the wave's properties and trajectory. The degree to which a radio wave is dispersed can give clues to how much gas it passed through, and possibly how much distance it has traveled from its source. For each of the 535 FRBs that CHIME detected, Masui and his colleagues measured its dispersion, and found that most bursts likely originated from far-off sources within distant galaxies. The fact that the bursts were bright enough to be detected by CHIME suggests that they must have been produced by extremely energetic sources. As the telescope detects more FRBs, scientists hope to pin down exactly what kind of exotic phenomena could generate such ultrabright, ultrafast signals.

Scientists also plan to use the bursts, and their dispersion estimates, to map the distribution of gas throughout the universe.

"Each FRB gives us some information of how far they've propagated and how much gas they've propagated through," Shin says. "With large numbers of FRBs, we can hopefully figure out how gas and matter are distributed on very large scales in the universe. So, alongside the mystery of what FRBs are themselves, there's also the exciting potential for FRBs as powerful cosmological probes in the future."

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Better-fitting face masks greatly improve COVID-19 protection

Even the best face masks work only as well as their fit.

And poorly fitting face masks greatly increase the risk of infection from airborne pathogens compared to custom-fitted masks, according to a new study by the University of Cincinnati.

Researchers in UC's College of Engineering and Applied Science used computerized tomography or CT scans of three different-sized face masks attached to three different-sized dummy heads to measure the gaps between the face and the fabric. Then they calculated the leaks from these gaps to determine the infection risk.

They found that while N95 masks are effective barriers against airborne diseases like COVID-19, poorly fitting masks can have substantial leaks around the face that reduce their effectiveness and increase the risk of infection.

"Many people do not realize that the fit of face masks can vary. There are different face shapes and different sizes of masks," said Rupak Banerjee, a professor in UC's Department of Mechanical and Materials Engineering.

"If you do not match them well, you can lead to greater leaks and higher risks of infection," he said.

The study was published in the Nature journal Scientific Reports.

Banerjee collaborated on the study with his former students, including UC graduates Prasanna Hariharan, Neha Sharma and Gavin D'Souza. Hariharan, the study's lead author, works for the U.S. Food and Drug Administration's Division of Applied Mechanics.

UC's use of CT scans improved the accuracy of contact modeling from previous studies that relied on gap geometry and computational models for estimates.

UC used three different sized N95 face masks from the National Institute for Occupational Safety and Health along with three standard mannequin heads identified as small, medium and large. From the CT scans, they could create a 3D computer-aided design model that showed the gaps between the masks and the face on each subject.

They calculated the airflow rates through the gaps to identify the relative infection risk for each mask on each face.

The aerosol transport attributed to leaking out the sides of the masks varied from as little as 30% to as much as 95% for the worst-fitting masks. Researchers found the leaks were most likely around the nose. Interestingly, they noticed that the gaps were often asymmetrical on the symmetrical dummy faces.

Researchers found that poorly fitted face masks can as much as double the infection risk to the wearers and people around them.

"A lot of people don't wear masks properly. They keep the nose exposed, which isn't helpful," Banerjee said.

But understanding that masks can often leak around the nose could help people pay more attention to the fit when buying and wearing masks.

Editor of the American Society of Mechanical Engineering Journal of Medical Devices, Banerjee said innovations in infection control have been hot topics this year.

"We are going to have a special issue soon about pandemic-response medical devices, including face masks and face shields," he said.

Meanwhile, UC's research could educate consumers and help manufacturers design better-fitting masks, he said.

While many countries are relaxing social-distancing mandates, Banerjee said he isn't putting his face masks away just yet.

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