Jun 12, 2021

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."

Read more at Science Daily

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."

Read more at Science Daily

Jun 11, 2021

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.

Read more at Science Daily

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."

 Read more at Science Daily

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.

Read more at Science Daily

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.

Read more at Science Daily

Jun 10, 2021

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."

Read more at Science Daily

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."

Read more at Science Daily

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.

Read more at Science Daily

Brain connections mean some people lack visual imagery

New research has revealed that people with the ability to visualise vividly have a stronger connection between their visual network and the regions of the brain linked to decision-making. The study also sheds light on memory and personality differences between those with strong visual imagery and those who cannot hold a picture in their mind's eye.

The research, from the University of Exeter, published in Cerebral Cortex Communications, casts new light on why an estimated one-three per cent of the population lack the ability to visualise. This phenomenon was named "aphantasia" by the University of Exeter's Professor Adam Zeman in 2015 Professor Zeman called those with highly developed visual imagery skills "hyperphantasics."

Funded by the Arts and Humanities Research Council, the study is the first systematic neuropsychological and brain imaging study of people with aphantasia and hypephantasia. The team conducted fMRI scans on 24 people with aphantasia, 25 with hyperphantasia and a control group of 20 people with mid-range imagery vividness. They combined the imaging data with detailed cognitive and personality tests.

The scans revealed that people with hyperphantasia have a stronger connection between the visual network which processes what we see, and which becomes active during visual imagery, and the prefrontal cortices, involved in decision-making and attention. These stronger connections were apparent in scans performed during rest, while participants were relaxing -- and possibly mind-wandering.

Despite equivalent scores on standard memory tests, Professor Zeman and the team found that people with hyperphantasia produce richer descriptions of imagined scenarios than controls, who in turn outperformed aphantasics. This also applied to autobiographical memory, or the ability to remember events that have taken place in the person's life. Aphantasics also had lower ability to recognise faces.

Personality tests revealed that aphantasics tended to be more introverted and hyperphantasics more open.

Professor Zeman said: "Our research indicates for the first time that a weaker connection between the parts of the brain responsible for vision and frontal regions involved in decision-making and attention leads to aphantasia. However, this shouldn't be viewed as a disadvantage -- it's a different way of experiencing the world. Many aphantasics are extremely high-achieving, and we're now keen to explore whether the personality and memory differences we observed indicate contrasting ways of processing information, linked to visual imagery ability."

From Science Daily

Jun 9, 2021

Scientists discover new exoplanet with an atmosphere ripe for study

An international group of collaborators, including scientists from NASA's Jet Propulsion Laboratory and The University of New Mexico, have discovered a new, temperate sub-Neptune sized exoplanet with a 24-day orbital period orbiting a nearby M dwarf star. The recent discovery offers exciting research opportunities thanks to the planet's substantial atmosphere, small star, and how fast the system is moving away from the Earth.

The research, titled TOI-1231 b: A Temperate, Neptune-Sized Planet Transiting the Nearby M3 Dwarf NLTT 24399, will be published in a future issue of The Astronomical Journal. The exoplanet, TOI-1231 b, was detected using photometric data from the Transiting Exoplanet Survey Satellite (TESS) and followed up with observations using the Planet Finder Spectrograph (PFS) on the Magellan Clay telescope at Las Campanas Observatory in Chile. The PFS is a sophisticated instrument that detects exoplanets through their gravitational influence on their host stars. As the planets orbit their hosts, the measured stellar velocities vary periodically, revealing the planetary presence and information about their mass and orbit.

The observing strategy adopted by NASA's TESS, which divides each hemisphere into 13 sectors that are surveyed for roughly 28 days, is producing the most comprehensive all-sky search for transiting planets. This approach has already proven its capability to detect both large and small planets around stars ranging from sun-like down to low-mass M dwarf stars. M dwarf stars, also known as a red dwarf, are the most common type of star in the Milky Way making up some 70 percent of all stars in the galaxy.

M dwarfs are smaller and possess a fraction of the sun's mass and have low luminosity. Because an M dwarf is smaller, when a planet of a given size transits the star, the amount of light that is blocked out by the planet is larger, making the transit more easily detectable. Imagine an Earth-like planet passing in front of a star the size of the sun, it's going to block out a tiny bit of light; but if it's passing in front of a star that's a lot smaller, the proportion of light that's blocked out will be larger. In a sense, this creates a larger shadow on the surface of the star, making planets around M dwarfs more easily detectable and easier to study.

Although it enables the detection of exoplanets across the sky, TESS's survey strategy also produces significant observational biases based on orbital period. Exoplanets must transit their host stars at least twice within TESS 's observing span to be detected with the correct period by the Science Processing Operations Center (SPOC) pipeline and the Quick Look Pipeline (QLP), which search the 2-minute and 30-minute cadence TESS data, respectively. Because 74 percent of TESS' total sky coverage is only observed for 28 days, the majority of TESS exoplanets detected have periods less than 14 days. TOI-1231b's 24-day period, therefore, makes its discovery even more valuable.

NASA JPL scientist Jennifer Burt, the lead author of the paper, along with her collaborators including Diana Dragomir, an assistant professor in UNM's Department of Physics and Astronomy, measured both the radius and mass of the planet.

"Working with a group of excellent astronomers spread across the globe, we were able to assemble the data necessary to characterize the host star and measure both the radius and mass of the planet," said Burt. "Those values in turn allowed us to calculate the planet's bulk density and hypothesize about what the planet is made out of. TOI-1231 b is pretty similar in size and density to Neptune, so we think it has a similarly large, gaseous atmosphere."

"Another advantage of exoplanets orbiting M dwarf hosts is that we can measure their masses easier because the ratio of the planet mass to the stellar mass is also larger. When the star is smaller and less massive, it makes detection methods work better because the planet suddenly plays a bigger role as it stands out more easily in relation to the star," explained Dragomir. "Like the shadow cast on the star. The smaller the star, the less massive the star, the more the effect of the planet can be detected.

"Even though TOI 1231b is eight times closer to its star than the Earth is to the Sun, its temperature is similar to that of Earth, thanks to its cooler and less bright host star," says Dragomir. "However, the planet itself is actually larger than earth and a little bit smaller than Neptune -- we could call it a sub-Neptune."

Burt and Dragomir, who actually initiated this research while they were Fellows at MIT's Kavli Institute, worked with scientists specializing in observing and characterizing the atmospheres of small planets to figure out which current and future space-based missions might be able to peer into TOI-1231 b's outer layers to inform researchers exactly what kinds of gases are swirling around the planet. With a temperature around 330 Kelvin or 140 degrees Fahrenheit, TOI-1231b is one of the coolest, small exoplanets accessible for atmospheric studies discovered thus far.

Past research suggests planets this cool may have clouds high in their atmospheres, which makes it hard to determine what types of gases surround them. But new observations of another small, cool planet called K2-18 b broke this trend and showed evidence of water in its atmosphere, surprising many astronomers.

"TOI-1231 b is one of the only other planets we know of in a similar size and temperature range, so future observations of this new planet will let us determine just how common (or rare) it is for water clouds to form around these temperate worlds," said Burt.

Additionally, with its host star's high Near-Infrared (NIR) brightness, it makes an exciting target for future missions with the Hubble Space Telescope (HST) and the James Webb Space Telescope (JWST). The first set of these observations, led by one of the paper's co-authors, should take place later this month using the Hubble Space Telescope.

"The low density of TOI 1231b indicates that it is surrounded by a substantial atmosphere rather than being a rocky planet. But the composition and extent of this atmosphere are unknown!" said Dragomir. "TOI1231b could have a large hydrogen or hydrogen-helium atmosphere, or a denser water vapor atmosphere. Each of these would point to a different origin, allowing astronomers to understand whether and how planets form differently around M dwarfs when compared to the planets around our Sun, for example. Our upcoming HST observations will begin to answer these questions, and JWST promises an even more thorough look into the planet's atmosphere."

Another way to study the planet's atmosphere is to investigate whether gas is being blown away, by looking for evidence of atoms like hydrogen and helium surrounding the planet as it transits across the face of its host star. Generally, hydrogen atoms are almost impossible to detect because their presence is masked by interstellar gas. But this planet-star system offers a unique opportunity to apply this method because of how fast it's moving away from the Earth.

"One of the most intriguing results of the last two decades of exoplanet science is that, thus far, none of the new planetary systems we've discovered look anything like our own solar system," said Burt. "They're full of planets between the size of Earth and Neptune on orbits much shorter than Mercury's, so we don't have any local examples to compare them to. This new planet we've discovered is still weird -- but it's one step closer to being somewhat like our neighborhood planets. Compared to most transiting planets detected thus far, which often have scorching temperatures in the many hundreds or thousands of degrees, TOI-1231 b is positively frigid."

Read more at Science Dialy

Cosmic cartographers map nearby universe revealing the diversity of star-forming galaxies

A team of astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) has completed the first census of molecular clouds in the nearby Universe, revealing that contrary to previous scientific opinion, these stellar nurseries do not all look and act the same. In fact, they're as diverse as the people, homes, neighborhoods, and regions that make up our own world.

Stars are formed out of clouds of dust and gas called molecular clouds, or stellar nurseries. Each stellar nursery in the Universe can form thousands or even tens of thousands of new stars during its lifetime. Between 2013 and 2019, astronomers on the PHANGS -- Physics at High Angular Resolution in Nearby GalaxieS -- project conducted the first systematic survey of 100,000 stellar nurseries across 90 galaxies in the nearby Universe to get a better understanding of how they connect back to their parent galaxies.

"We used to think that all stellar nurseries across every galaxy must look more or less the same, but this survey has revealed that this is not the case, and stellar nurseries change from place to place," said Adam Leroy, Associate Professor of Astronomy at Ohio State University (OSU), and lead author of the paper presenting the PHANGS ALMA survey. "This is the first time that we have ever taken millimeter-wave images of many nearby galaxies that have the same sharpness and quality as optical pictures. And while optical pictures show us light from stars, these ground-breaking new images show us the molecular clouds that form those stars."

The scientists compared these changes to the way that people, houses, neighborhoods, and cities exhibit like-characteristics but change from region to region and country to country.

"To understand how stars form, we need to link the birth of a single star back to its place in the Universe. It's like linking a person to their home, neighborhood, city, and region. If a galaxy represents a city, then the neighborhood is the spiral arm, the house the star-forming unit, and nearby galaxies are neighboring cities in the region," said Eva Schinnerer, an astronomer at the Max Planck Institute for Astronomy (MPIA) and principal investigator for the PHANGS collaboration "These observations have taught us that the "neighborhood" has small but pronounced effects on where and how many stars are born."

To better understand star formation in different types of galaxies, the team observed similarities and differences in the molecular gas properties and star formation processes of galaxy disks, stellar bars, spiral arms, and galaxy centers. They confirmed that the location, or neighborhood, plays a critical role in star formation.

"By mapping different types of galaxies and the diverse range of environments that exist within galaxies, we are tracing the whole range of conditions under which star-forming clouds of gas live in the present-day Universe. This allows us to measure the impact that many different variables have on the way star formation happens," said Guillermo Blanc, an astronomer at the Carnegie Institution for Science, and a co-author on the paper.

"How stars form, and how their galaxy affects that process, are fundamental aspects of astrophysics," said Joseph Pesce, National Science Foundation's program officer for NRAO/ALMA. "The PHANGS project utilizes the exquisite observational power of the ALMA observatory and has provided remarkable insight into the story of star formation in a new and different way."

Annie Hughes, an astronomer at L'Institut de Recherche en Astrophysique et Planétologie (IRAP), added that this is the first time scientists have a snapshot of what star-forming clouds are really like across such a broad range of different galaxies. "We found that the properties of star-forming clouds depend on where they are located: clouds in the dense central regions of galaxies tend to be more massive, denser, and more turbulent than clouds that reside in the quiet outskirts of a galaxy. The lifecycle of clouds also depends on their environment. How fast a cloud forms stars and the process that ultimately destroys the cloud both seem to depend on where the cloud lives."

This is not the first time that stellar nurseries have been observed in other galaxies using ALMA, but nearly all previous studies focused on individual galaxies or part of one. Over a five-year period, PHANGS assembled a full view of the nearby population of galaxies. "The PHANGS project is a new form of cosmic cartography that allows us to see the diversity of galaxies in a new light, literally. We are finally seeing the diversity of star-forming gas across many galaxies and are able to understand how they are changing over time. It was impossible to make these detailed maps before ALMA," said Erik Rosolowsky, Associate Professor of Physics at the University of Alberta, and a co-author on the research. "This new atlas contains 90 of the best maps ever made that reveal where the next generation of stars is going to form."

For the team, the new atlas doesn't mean the end of the road. While the survey has answered questions about what and where, it has raised others. "This is the first time we have gotten a clear view of the population of stellar nurseries across the whole nearby Universe. In that sense, it's a big step towards understanding where we come from," said Leroy. "While we now know that stellar nurseries vary from place to place, we still do not know why or how these variations affect the stars and planets formed. These are questions that we hope to answer in the near future."

Read more at Science Daily

Turning off lights can save migrating birds from crashing into buildings

Every night during the spring and fall migration seasons, thousands of birds are killed when they crash into illuminated windows, disoriented by the light. But a new study in PNAS shows that darkening just half of a building's windows can make a big difference for birds. Using decades' worth of data and birds collected by Field Museum scientists at Chicago's McCormick Place convention center, the researchers found that on nights when half the windows were darkened, there were 11 times fewer bird collisions during spring migration and 6 times fewer collisions during fall migration than when all the windows were lit.

"Our research provides the best evidence yet that migrating birds are attracted to building lights, often causing them to collide with windows and die," says Benjamin Van Doren, a postdoctoral associate at the Cornell Lab of Ornithology and the paper's lead author. "These insights were only possible thanks to over 40 years of work by David Willard at the Field Museum, who led collisions and light monitoring efforts."

In 1978, Willard, the museum's collections manager emeritus, heard an offhand remark about birds hitting the McCormick Place, North America's largest convention center that happens to be just a mile south of the museum. So, he investigated.

"I went down early one morning, just out of curiosity, and wandered around and actually found four or five dead birds," says Willard. "I might not have gone back if I hadn't found anything that first day, and now here we are, 40 years later and 40,000 birds later."

Willard and his colleagues, including Field Museum co-author Mary Hennen and other Field staff and volunteers, have visited the site every day before sunrise during migration season, sometimes as early as 3:30 in the morning. Some days there are no birds; other times, there are as many as 200. Willard collects the dead birds and brings them back to the museum, where he records each one in a ledger and adds them to the museum's collection.

Around twenty years ago, Willard began to notice a pattern -- on nights when the lights were out at McCormick Place, around holidays or construction work, there were fewer birds on the ground the next morning. As the building's lighting patterns began to vary more, he began gathering data on which windows were illuminated each night, in addition to collecting the birds he found on the pavement.

The new PNAS study is the most in-depth use of the data on lighting patterns to date, combining Willard's specimens and lighting observations with other conditions that might play a role in bird mortality, including weather records and radar data revealing the number of birds in the sky on a given night. "We developed a statistical model based on the number of windows illuminated at McCormick Place, weather conditions, migratory passage, and time of season. This allowed us to isolate the relationship between window lighting and collisions while accounting for these other factors," says Van Doren. "By joining these different sources of data, we were able to understand how lights, weather, and migration each contribute to collision mortality."

The team found that the total number of birds in the sky on a given night and the direction of the wind both play a role in mortality, but the biggest determining factor was light: when more windows were darkened, fewer birds died. "The sheer strength of the link between lighting and collisions was surprising," says Van Doren. "It speaks to the exciting potential to save birds simply by reducing light pollution."

The researchers were able to quantify that bird-saving potential: they predict that halving the lighted window area could decrease collision counts by 11 times in spring and 6 times in fall. By turning out half the lights during migration seasons, bird mortality at McCormick Place could be reduced by 59%.

The researchers note that McCormick Place is far from unique -- it's been monitored for longer than any other Chicago building, but, Willard says, "There's hardly an address in downtown Chicago that doesn't have a bird in the Field Museum's collection, thanks to the efforts of the Chicago Bird Collision Monitors." However, there are a few factors that make the McCormick Center especially dangerous for birds, including its massive size, its isolation from other buildings, and its proximity to Lake Michigan, which birds are sometimes hesitant to fly over.

"Buildings all across North America, all across the world, are killing birds, and those add up," says Doug Stotz, a senior conservation ecologist at the Field. "What we've learned in the past 20 years about lights being on has caused the city of Chicago to create its Lights Out program, which requires buildings' external lights to be turned off during peak migration. I hope this paper will show why it's important to turn off internal lighting as well, especially in Chicago, which is the country's deadliest city for migrating birds."

Van Doren is also eager to see the project's findings applied. "Our study contains a hopeful message: we can save birds simply by turning off lights during a handful of high-risk days each spring and fall," he says. "By adapting our existing public migration forecasts to identify nights with high collision risk, we will be able to issue targeted lights-out advisories several days in advance."

In addition to the study's implications for bird conservation, it also speaks to the importance of natural history collections in documenting global change. "These collision data are even more valuable because they are backed up by specimens that are available for study in the Field Museum," says Ben Winger, one of the paper's senior authors, an assistant professor and curator at the University of Michigan and a Field Museum graduate student alumnus . "This will allow future scientists to go a step further and study the connections between many aspects of avian biology and conservation relevant questions."

Read more at Science Daily

Taking short breaks may help our brains learn new skills

In a study of healthy volunteers, National Institutes of Health researchers have mapped out the brain activity that flows when we learn a new skill, such as playing a new song on the piano, and discovered why taking short breaks from practice is a key to learning. The researchers found that during rest the volunteers' brains rapidly and repeatedly replayed faster versions of the activity seen while they practiced typing a code. The more a volunteer replayed the activity the better they performed during subsequent practice sessions, suggesting rest strengthened memories.

"Our results support the idea that wakeful rest plays just as important a role as practice in learning a new skill. It appears to be the period when our brains compress and consolidate memories of what we just practiced," said Leonardo G. Cohen, M.D., senior investigator at the NIH's National Institute of Neurological Disorders and Stroke (NINDS) and the senior author of the study published in Cell Reports. "Understanding this role of neural replay may not only help shape how we learn new skills but also how we help patients recover skills lost after neurological injury like stroke."

The study was conducted at the NIH Clinical Center. Dr. Cohen's team used a highly sensitive scanning technique, called magnetoencephalography, to record the brain waves of 33 healthy, right-handed volunteers as they learned to type a five-digit test code with their left hands. The subjects sat in a chair and under the scanner's long, cone-shaped cap. An experiment began when a subject was shown the code "41234" on a screen and asked to type it out as many times as possible for 10 seconds and then take a 10 second break. Subjects were asked to repeat this cycle of alternating practice and rest sessions a total of 35 times.

During the first few trials, the speed at which subjects correctly typed the code improved dramatically and then leveled off around the 11th cycle. In a previous study, led by former NIH postdoctoral fellow Marlene Bönstrup, M.D., Dr. Cohen's team showed that most of these gains happened during short rests, and not when the subjects were typing. Moreover, the gains were greater than those made after a night's sleep and were correlated with a decrease in the size of brain waves, called beta rhythms. In this new report, the researchers searched for something different in the subjects' brain waves.

"We wanted to explore the mechanisms behind memory strengthening seen during wakeful rest. Several forms of memory appear to rely on the replaying of neural activity, so we decided to test this idea out for procedural skill learning," said Ethan R. Buch, Ph.D., a staff scientist on Dr. Cohen's team and leader of the study.

To do this, Leonardo Claudino, Ph.D., a former postdoctoral fellow in Dr. Cohen's lab, helped Dr. Buch develop a computer program which allowed the team to decipher the brain wave activity associated with typing each number in the test code.

The program helped them discover that a much faster version -- about 20 times faster -- of the brain activity seen during typing was replayed during the rest periods. Over the course of the first eleven practice trials, these compressed versions of the activity were replayed many times -- about 25 times -- per rest period. This was two to three times more often than the activity seen during later rest periods or after the experiments had ended.

Interestingly, they found that the frequency of replay during rest predicted memory strengthening. In other words, the subjects whose brains replayed the typing activity more often showed greater jumps in performance after each trial than those who replayed it less often.

"During the early part of the learning curve we saw that wakeful rest replay was compressed in time, frequent, and a good predictor of variability in learning a new skill across individuals," said Dr. Buch. "This suggests that during wakeful rest the brain binds together the memories required to learn a new skill."

As expected, the team discovered that the replay activity often happened in the sensorimotor regions of the brain, which are responsible for controlling movements. However, they also saw activity in other brain regions, namely the hippocampus and entorhinal cortex.

Read more at Science Daily

People who have trouble sleeping are at a higher risk of dying early - especially diabetics

In a paper published by the Journal of Sleep Research, researchers reveal how they examined data* from half a million middle-aged UK participants asked if they had trouble falling asleep at night or woke up in the middle of the night.

The report found that people with frequent sleep problems are at a higher risk of dying than those without sleep problems. This grave outcome was more pronounced for people with Type-2 diabetes: during the nine years of the research, the study found that they were 87 per cent more likely to die of any cause than people without diabetes or sleep disturbances.

The study also found that people with diabetes and sleep problems were 12 per cent more likely to die over this period than those who had diabetes but not frequent sleep disturbances.

Malcolm von Schantz, the first author of the study and Professor of Chronobiology from the University of Surrey, said:

"Although we already knew that there is a strong link between poor sleep and poor health, this illustrates the problem starkly."

"The question asked when the participants enrolled does not necessarily distinguish between insomnia and other sleep disorders, such as sleep apnoea. Still, from a practical point of view it doesn't matter. Doctors should take sleep problems as seriously as other risk factors and work with their patients on reducing and mitigating their overall risk."

Professor Kristen Knutson of Northwestern University, the senior co-author of the study, said:

"Diabetes alone was associated with a 67 per cent increased risk of mortality. However, the mortality for participants with diabetes combined with frequent sleep problems was increased to 87 per cent. In order words, it is particularly important for doctors treating people with diabetes to also investigate sleep disorders and consider treatments where appropriate."

From Science Daily

Jun 8, 2021

Physicists report definitive evidence how auroras are created

The aurora borealis, or northern lights, that fill the sky in high-latitude regions have fascinated people for thousands of years. But how they're created, while theorized, had not been conclusively proven.

In a new study, a team of physicists led by University of Iowa reports definitive evidence that the most brilliant auroras are produced by powerful electromagnetic waves during geomagnetic storms. The phenomena, known as Alfven waves, accelerate electrons toward Earth, causing the particles to produce the familiar atmospheric light show.

The study, published online June 7 in the journal Nature Communications, concludes a decades-long quest to demonstrate experimentally the physical mechanisms for the acceleration of electrons by Alfven waves under conditions corresponding to Earth's auroral magnetosphere.

"Measurements revealed this small population of electrons undergoes 'resonant acceleration' by the Alfven wave's electric field, similar to a surfer catching a wave and being continually accelerated as the surfer moves along with the wave," says Greg Howes, associate professor in the Department of Physics and Astronomy at Iowa and study co-author.

Scientists have known that energized particles that emanate from the sun -- such as electrons racing at approximately 45 million miles per hour -- precipitate along the Earth's magnetic field lines into the upper atmosphere, where they collide with oxygen and nitrogen molecules, kicking them into an excited state. These excited molecules relax by emitting light, producing the colorful hues of the aurora.

The theory was supported by spacecraft missions that frequently found Alfven waves traveling Earthward above auroras, presumably accelerating electrons along the way. Although space-based measurements had supported the theory, limitations inherent to spacecraft and rocket measurements had prevented a definitive test.

The physicists were able to find confirmatory evidence in a series of experiments conducted at the Large Plasma Device (LPD) in UCLA's Basic Plasma Science Facility, a national collaborative research facility supported jointly by the U.S. Department of Energy and National Science Foundation.

"The idea that these waves can energize the electrons that create the aurora goes back more than four decades, but this is the first time we've been able to confirm definitively that it works," says Craig Kletzing, professor in the Department of Physics and Astronomy at Iowa and a study co-author. "These experiments let us make the key measurements that show that the space measurements and theory do, indeed, explain a major way in which the aurora are created."

The phenomenon of electrons "surfing" on the electric field of a wave is a theoretical process known as Landau damping, first proposed by Russian physicist Lev Landau in 1946. Through numerical simulations and mathematical modeling, the researchers demonstrated that the results of their experiment agreed with the predicted signature for Landau damping.

The agreement of experiment, simulation, and modeling provides the first direct evidence that Alfven waves can produce accelerated electrons, causing the aurora, says Troy Carter, professor of physics at UCLA and director of the UCLA Plasma Science and Technology Institute.

Read more at Science Daily

The origin of the first structures formed in galaxies like the Milky Way identified

An international team of scientists led from the Centre for Astrobiology (CAB, CSIC-INTA), with participation from the Instituto de Astrofísica de Canarias (IAC), has used the Gran Telescopio Canarias (GTC) to study a representative sample of galaxies, both disc and spheroidal, in a deep sky zone in the constellation of the Great Bear to characterize the properties of the stellar populations of galactic bulges. The researchers have been able to determine the mode of formation and development of these galactic structures. The results of this study were recently published in The Astrophysical Journal.

The researchers focused their study on massive disc and spheroidal galaxies, using imaging data from the Hubble Space Telescope and spectroscopic data from the SHARDS (Survey for High-z Absorption Red and Dead Sources) project, a programme of observations over the complete GOODS-N (Great Observatories Origins Deep Survey -- North) region through 25 different filters taken with the OSIRIS instrument on the Gran Telescopio Canarias (GTC), the largest optical and infrared telescope in the world, at the Roque de los Muchachos Observatory (Garafía, La Palma, Canary Islands).

Analysis of the data allowed the researchers to discover something unexpected: the bulges of the disc galaxies were formed in two waves. One third of the bulges in disc galaxies were formed at redshift 6.2, which corresponds to an early epoch in the Universe, when it was only 5% of its present age, around 900 million years old. "These bulges are the relics of the first structures formed in the Universe, which we have found hidden in local disc galaxies," explains Luca Costantin, a researcher at the CAB within a programme of Attracting Talent of the Community of Madrid, and the first author on the paper.

But in contrast, almost two thirds of the bulges observed show a mean value of redshift of around 1.3, which means that they were formed much more recently, corresponding to an age of four thousand million years, or almost 35% of the age of the Universe.

A peculiar characteristic which permits the distinction between the two waves is that the central bulges of the first wave, the older bulges, are more compact and dense than those formed in the second, more recent wave. In addition, the data from the spheroidal galaxies in the sample show a mean redshift value of 1.1, which suggests that they formed in the same general time as the bulges of the second wave.

For Jairo Méndez Abreu, a researcher at the University of Granada (UGR) and a co-author of the article, who was formerly a Severo Ochoa postdoctoral researcher at the IAC, "the idea behind the technique used to observe the stars in the central bulge is fairly simple, but it has not been possible to apply it until the recent development of methods which have allowed us to separate the light from the stars in the central bulge from those in the disc, to be specific the GASP2D and C2D algorithms, which we have developed recently and which have enabled us to achieve unprecedented accuracy."

Another important result of the study is that the two waves of bulge formation differ not only in terms of the ages of their stars, but also in terms of their star formation rates. The data indicate that the stars in the bulges of the first wave formed quickly, on timescales of typically 200 million year. On the contrary, a significant fraction of the stars in the bulges of the second wave required formation times five times longer, some thousand million years.

"We have found that the Universe has two ways of forming the central zones of galaxies like our own: starting early and performing very quickly, or taking time to start, but finally forming a large number of stars in what we know as the bulge," comments Pablo G. Pérez González, a researcher at the CAB, and Principal Investigator of the SHARDS project, which gave essential data for this study. In the words of Antonio Cabrera, the Head of Science Operations at the GTC, "SHARDS is a perfect example of what is possible due to the combination of the huge collecting capacity of the GTC and the extraordinary conditions at the Roque de los Muchachos Observatory, to produce 180 hours of data with such excellent image quality, essential for the detection of the objects analysed here."

As described by Paola Dimauro, a researcher at the National Observatory of Brazil and a co-author of this article, "this study has allowed us to explore the morphological evolution and the history of the assembly of the structural components of the galaxies, analagous to archaeological studies, analysing the information encoded in the millions of stars of each galaxy. The interesting point was to find that not all the structures were formed at the same time, or in the same way."

Read more at Science Daily

Axions could be the fossil of the universe researchers have been waiting for

Finding the hypothetical particle axion could mean finding out for the first time what happened in the Universe a second after the Big Bang, suggests a new study published in Physical Review D on June 7.

How far back into the Universe's past can we look today? In the electromagnetic spectrum, observations of the Cosmic Microwave Background -- commonly referred to as the CMB -- allow us to see back almost 14 billion years to when the Universe cooled sufficiently for protons and electrons to combine and form neutral hydrogen. The CMB has taught us an inordinate amount about the evolution of the cosmos, but photons in the CMB were released 400,000 years after the Big Bang making it extremely challenging to learn about the history of the universe prior to this epoch.

To open a new window, a trio of theoretical researchers, including Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) Principal Investigator, University of California, Berkeley, MacAdams Professor of Physics and Lawrence Berkeley National Laboratory senior faculty scientist Hitoshi Murayama, Lawrence Berkeley National Laboratory physics researcher and University of California, Berkeley, postdoctoral fellow Jeff Dror (now at University of California, Santa Cruz), and UC Berkeley Miller Research Fellow Nicholas Rodd, looked beyond photons, and into the realm of hypothetical particles known as axions, which may have been emitted in the first second of the Universe's history.

In their paper, they suggest the possibility of searching for an axion analogue of the CMB, a so-called Cosmic axion Background or CaB.

While hypothetical, there are many reasons to suspect that the axion could exist in our Universe.

For one, axions are a generic prediction of string theory, one of today's best hopes for a theory of quantum gravity. The existence of an axion could further help resolve the long standing puzzle of why we have yet to measure an electric dipole moment for the neutron, an issue more formally known as the "Strong CP Problem." More recently, the axion has become a promising candidate for dark matter, and as a consequence researchers are rapidly searching for axion dark-matter.

In their paper, the researchers point out that as experimentalists develop more sensitive instruments to search for dark matter, they may stumble upon another sign of axions in the form of the CaB. But because the CaB shares similar properties with dark-matter axions, there is a risk the experiments would throw the CaB signal out as noise.

Finding the CaB at one of these instruments would be a double discovery. Not only would it confirm the existence of the axion, but researchers worldwide would immediately have a new fossil from the early Universe. Depending on how the CaB was produced, researchers could learn about various different aspects of the Universe's evolution never possible before (Figure).

"What we have proposed is that, by changing the way current experiments analyze data, we may be able to search for left-over axions from the early universe. Then, we might be able to learn about the origin of dark matter, phase transition or inflation at the beginning of the Universe. There are already experimental groups who have shown interest in our proposal, and I hope we can find out something new about the early Universe that wasn't known before," says Murayama.

"The evolution of the universe can produce axions with a characteristic energy distribution. By detecting the energy density of the universe currently made up of axions, experiments such as MADMAX, HAYSTAC, ADMX, and DMRadio could give us answers to some of the most important puzzles in cosmology, such as, 'How hot did our universe get?', 'What is nature of dark matter?', 'Did our universe undergo a period of rapid expansion known as inflation?', and 'Was there ever a cosmic phase transition?'," says Dror.

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How COVID-19 wreaks havoc on human lungs

Scientists at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory have published the first detailed atomic-level model of the SARS-CoV-2 "envelope" protein bound to a human protein essential for maintaining the lining of the lungs. The model showing how the two proteins interact, just published in the journal Nature Communications, helps explain how the virus could cause extensive lung damage and escape the lungs to infect other organs in especially vulnerable COVID-19 patients. The findings may speed the search for drugs to block the most severe effects of the disease.

"By obtaining atomic-level details of the protein interactions we can explain why the damage occurs, and search for inhibitors that can specifically block these interactions," said study lead author Qun Liu, a structural biologist at Brookhaven Lab. "If we can find inhibitors, then the virus won't cause nearly as much damage. That may give people with compromised health a much better chance for their immune systems to fight the virus successfully."

Scientists discovered the details and developed the molecular model using one of the new cryo-electron microscopes at Brookhaven Lab's Laboratory for BioMolecular Structure (LBMS), a new research facility built with funding from New York State adjacent to Brookhaven's National Synchrotron Light Source II (NSLS-II).

"LBMS opened last summer ahead of schedule because of its importance in the battle against COVID-19," said Sean McSweeney, director of LBMS and a coauthor on the paper. "LBMS and NSLS-II offer complementary protein-imaging techniques and both are playing important roles in deciphering the details of proteins involved in COVID-19. This is the first paper published based on results from the new facility."

Liguo Wang, scientific operations director of LBMS and another coauthor on the paper, explained that "cryo-electron microscopy (cryo-EM) is particularly useful for studying membrane proteins and dynamic protein complexes, which can be difficult to crystallize for protein crystallography, another common technique for studying protein structures. With this technique we created a 3-D map from which we could see how the individual protein components fit together."

"Without cryo-EM, we couldn't have gotten a structure to capture the dynamic interactions between these proteins," Liu said.

Triggering lung disruption

The SARS-CoV-2 envelope protein (E), which is found on the virus's outer membrane alongside the now-infamous coronavirus spike protein, helps to assemble new virus particles inside infected cells. Studies published early in the COVID-19 pandemic showed that it also plays a crucial role in hijacking human proteins to facilitate virus release and transmission. Scientists hypothesize that it does this by binding to human cell-junction proteins, pulling them away from their usual job of keeping the junctions between lung cells tightly sealed.

"That interaction can be good for the virus, and very bad for humans -- especially elderly COVID-19 patients and those with pre-existing medical conditions," Liu said.

When lung cell junctions are disrupted, immune cells come in to try to fix the damage, releasing small proteins called cytokines. This immune response can make matters worse by triggering massive inflammation, causing a so-called "cytokine storm" and subsequent acute respiratory distress syndrome.

Also, because the damage weakens the cell-cell connections, it might make it easier for the viruses to escape from the lungs and travel through the bloodstream to infect other organs, including the liver, kidneys, and blood vessels.

"In this scenario, most damage would occur in patients with more viruses and more E proteins being produced," Liu said. And this could become a vicious cycle: More viruses making more E proteins and more cell-junction proteins being pulled out, causing more damage, more transmission, and more viruses again. Plus, any existing damage, such as lung-cell scarring, would likely make it harder for COVID patients to recover from the damage.

"That's why we wanted to study this interaction -- to understand the atomic-level details of how E interacts with one of these human proteins to learn how to interrupt the interactions and reduce or block these severe effects," Liu said.

From specks to blobs to map to model

The scientists obtained atomic-level details of the interaction between E and a human lung-cell-junction protein called PALS1 by mixing the two proteins together, freezing the sample rapidly, and then studying the frozen sample with the cryo-EM. The electron microscopes use high-energy electrons to interact with the sample in much the same way that regular light microscopes use beams of light. But electrons allow scientists to see things at a much smaller scale due to their extremely short wavelength (100,000 times shorter than that of visible light).

The first images didn't look like much more than specks. But image-processing techniques allowed the team to select specks that were actual complexes of the two proteins.

"We used two-dimensional averaging and started to see some structural features that are shared among these particles. Our images showed the complex from different orientations but at fairly low resolution," Liu said. "Then we use computational tools and computation infrastructure at Brookhaven's Computational Science Initiative to perform three-dimensional reconstructions. These give us a 3-D model -- an experimental map of the structure."

With an overall resolution of 3.65 Angstroms (the size of just a few atoms), the map had enough information about the unique characteristics of the individual amino acids that make up the two proteins for the scientists to fit the known structures of those amino acids into the map.

"We can see how the chain of amino acids that makes up the PALS1 protein folds to form three structural components, or domains, and how the much smaller chain of amino acids that makes up the E protein fits in a hydrophobic pocket between two of those domains," Liu said.

The model provides both the structural details and an understanding of the intermolecular forces that allow E proteins deep within an infected cell to wrench PALS1 from its place at the cell's outer boundary.

"Now we can explain how the interactions pull PALS1 from the human lung-cell junction and contribute to the damage," Liu said.

Implications for drugs and evolution

"This structure provides the foundation for our computational science colleagues to run docking studies and molecular dynamics simulations to search for drugs or drug-like molecules that might block the interaction," said John Shanklin, chair of Brookhaven Lab's Biology Department and a coauthor on the paper. "And if they identify promising leads, we have the analytical capabilities to rapidly screen through such candidate drugs to identify ones that might be key to preventing severe consequences of COVID-19."

Understanding the dynamics of this protein interaction will also help scientists track how viruses like SARS-CoV-2 evolve.

"When the virus protein pulls PALS1 out of the cell junction, it could help the virus spread more easily. That would provide a selective advantage for the virus. Any traits that increase the survival, spread, or release of the virus are likely to be retained," Liu said.

Read more at Science Daily

Jun 7, 2021

Fossil secret may shed light on the diversity of Earth's first animals

A large group of iconic fossils widely believed to shed light on the origins of many of Earth's animals and the communities they lived in may be hiding a secret.

Scientists, led by two from the University of Portsmouth, UK, are the first to model how exceptionally well preserved fossils that record the largest and most intense burst of evolution ever seen could have been moved by mudflows.

The finding, published in Communications Earth & Environment, offers a cautionary note on how palaeontologists build a picture from the remains of the creatures they study.

Until now, it has been widely accepted the fossils buried in mudflows in the Burgess Shale in Canada that show the result of the Cambrian explosion 505 million years ago had all lived together but that's now in doubt.

The Cambrian explosion was responsible for kick-starting the huge diversity of animal life now seen on the planet.

Now, Dr Nic Minter and Dr Orla Bath Enright have found that some of the animals which became fossils could have remained well preserved even after being carried large distances, throwing doubt on the idea the creatures all lived together.

Dr Minter said: "This finding might surprise scientists or lead to them striking a more cautionary tone in how they interpret early marine ecosystems from half a billion years ago.

"It has been assumed that because the Burgess Shale fossils are so well preserved, they couldn't have been transported over large distances. However, this new research shows that the general type of flow responsible for the deposits in which they were buried does not cause further damage to deceased animals. This means the fossils found in individual layers of sediment, and assumed to represent animal communities, could actually have been living far apart in distance."

Drs Minter and Bath Enright, of the University of Portsmouth's School of the Environment, Geography and Geosciences, studied the Burgess Shale area of British Columbia, both on location in the field and with laboratory experiments.

The site is an area rich in fossils entombed in the deposits of mudflows and is one of the world's most important fossil sites, with more than 65,000 specimens already collected and, so far, more than 120 species counted.

The Burgess Shale area has been fundamental to scientists in understanding the origins of animal groups and the communities they lived among and has been closely studied multiple times.

The researchers, together with collaborators from the Universities of Southampton and Saskatchewan in Canada, used fieldwork to identify how the mudflows would have behaved, and then used flume tank laboratory tests to mimic the mudflows and are confident that the bodies of certain creatures could have been moved over tens of kilometres without damage, creating the illusion of animal communities which never existed.

The Burgess Shale was discovered in the early 1900s and led to the idea of the 'Cambrian explosion' of life, with the appearance of animals representing almost all the modern phyla, and inspiring copious research and discoveries.

Dr Bath Enright said: "Many would argue that it is fundamental, even ground zero for scientists in understanding the diversity of life."

It's not known precisely what caused the mudflows which buried and moved the animals which became fossilised, but the area was subject to multiple flows, causing well preserved fossils to be found at many different levels in the shale.

"We don't know over what kind of overall time frame these many flows happened, but we know each one produced an 'event bed' that we see today stacked up on top of one another. These flows could pick up animals from multiple places as they moved across the seafloor and then dropped them all together in one place," said Dr Bath Enright.

"When we see multiple species accumulated together it can give the illusion we are seeing a single community. But we argue that an individual 'event bed' could be the product of several communities of animals being picked up from multiple places by a mudflow and then deposited together to give what looks like a much more complicated single community of animals.

"Palaeontologists need to appreciate the nature of the sediments that fossils are preserved within and what the implications of that are. We could be overestimating the complexity of early marine animal communities and therefore the patterns and drivers of evolution that have led to our present day diversity and complexity."

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How a Vietnamese raw pork snack could help us keep food fresh, naturally

A traditional Vietnamese meat snack could hold the key to developing a safe and natural food preservative, addressing the twin global problems of food waste and food-borne illnesses.

The fermented pork snack, Nem Chua, is eaten raw but does not cause food poisoning when prepared correctly.

This is because friendly bacteria that thrive in the fermented meat make a special compound that destroys more dangerous bacteria.

Now researchers at RMIT University in Melbourne, Australia, have shown how this natural bacteria-killing compound could be used to keep food fresh for longer.

Food waste is a global issue that costs around $US680 billion annually in industrialised countries, consumes nearly a quarter of the water used in agriculture and produces 8% of global greenhouse emissions.

Food-borne diseases like Listeria or Salmonella affect millions each year and can be life threatening for pregnant women, older people and those who are immunocompromised.

Co-lead researcher Professor Oliver Jones said changes in consumer habits have led to a greater demand for natural alternatives to artificial food preservatives.

"Scientists have known about these bacteria-killing compounds for many years but the challenge is to produce them in large enough quantities to be used by the food industry," said Jones, Associate Dean of Biosciences and Food Technology at RMIT.

"The Nem Chua compound is colourless, odourless, tasteless and very resilient.

"Through this new research, we've identified the right growth conditions that would enable us to make it in large amounts, potentially at industrial scales.

"With further development, we hope this could be an effective, safe and all-natural solution for both food waste and food-borne disease."

Bacteria-killing weapon

A team of RMIT researchers was inspired to investigate Nem Chua for its potential antibacterial properties after travelling to Vietnam and observing people eating the raw meat snack without getting sick, despite the hot and humid climate.

The team, led by Professor Andrew Smith (now at Griffith University) and Dr Bee May, discovered a new type of bacteria-killing compound in Nem Chua.

Plantacyclin B21AG is one of a group of compounds known as bacteriocins, which are produced by bacteria to destroy rival bacterial strains.

Bacteriocins form holes in the membranes of target bacteria. This causes the contents of the cell to leak out -- effectively killing the bacteria.

The problem is most bacteriocins only work against one or two types of bacteria and they are not very stable in different environmental conditions.

Only one -- Nisin, which came to market in the 1960s -- is currently licensed for use as a food preservative, in a market estimated to be worth more than $US513 million in 2020, but this compound is temperature and pH sensitive limiting its use.

Tough and effective

The Nem Chua-derived compound is more robust than Nisin and is effective against a wide range of bacteria even after exposure to a range of environments typical in food processing.

It can survive being heated to 90C for 20 minutes and remains stable across high and low pH levels.

The compound can also destroy a range of disease-causing organisms commonly found in food including potentially life-threating Listeria, which can survive refrigeration and even freezing.

Co-lead researcher Dr Elvina Parlindungan, who completed the new study as part of her PhD research at RMIT, is now a postdoctoral fellow at APC Microbiome, part of University College Cork in Ireland.

"Using bacteriocins as food preservatives effectively means we are turning bacteria's own toxic weapons against them -- harnessing nature's smart solutions to tackle our big challenges," Parlindungan said.

"In the future, these compounds might also be useful as an antibiotic in human medicine."

Researchers at RMIT's School of Science have begun experimenting with methods to further purify the compound and are planning to incorporate it into test food products.

The team is keen to collaborate with potential industry partners to further develop the technology.

Read more at Science Daily