Anatomy of the red planet: Mars-quakes reveal interior

Since early 2019, researchers have been recording and analysing marsquakes as part of the InSight mission. This relies on a seismometer whose data acquisition and control electronics were developed at ETH Zurich. Using this data, the researchers have now measured the red planet's crust, mantle and core -- data that will help determine the formation and evolution of Mars and, by extension, the entire solar system.

Mars once completely molten

We know that Earth is made up of shells: a thin crust of light, solid rock surrounds a thick mantle of heavy, viscous rock, which in turn envelopes a core consisting mainly of iron and nickel. Terrestrial planets, including Mars, have been assumed to have a similar structure. "Now seismic data has confirmed that Mars presumably was once completely molten before dividing into the crust, mantle and core we see today, but that these are different from Earth's," says Amir Khan, a scientist at the Institute of Geophysics at ETH Zurich and at the Physics Institute at the University of Zurich. Together with his ETH colleague Simon Stähler, he analysed data from NASA's InSight mission, in which ETH Zurich is participating under the leadership of Professor Domenico Giardini.

No plate tectonics on Mars

The researchers have discovered that the Martian crust under the probe's landing site near the Martian equator is between 15 and 47 kilometres thick. Such a thin crust must contain a relatively high proportion of radioactive elements, which calls into question previous models of the chemical composition of the entire crust.

Beneath the crust comes the mantle with the lithosphere of more solid rock reaching 400-600 kilometres down -- twice as deep as on Earth. This could be because there is now only one continental plate on Mars, in contrast to Earth with its seven large mobile plates. "The thick lithosphere fits well with the model of Mars as a 'one-plate planet'," Khan concludes.

The measurements also show that the Martian mantle is mineralogically similar to Earth's upper mantle. "In that sense, the Martian mantle is a simpler version of Earth's mantle." But the seismology also reveals differences in chemical composition. The Martian mantle, for example, contains more iron than Earth's. However, theories as to the complexity of the layering of the Martian mantle also depend on the size of the underlying core -- and here, too, the researchers have come to new conclusions.

The core is liquid and larger than expected

The Martian core has a radius of about 1,840 kilometres, making it a good 200 kilometres larger than had been assumed 15 years ago, when the InSight mission was planned. The researchers were now able to recalculate the size of the core using seismic waves. "Having determined the radius of the core, we can now calculate its density," Stähler says.

"If the core radius is large, the density of the core must be relatively low," he explains: "That means the core must contain a large proportion of lighter elements in addition to iron and nickel." These include sulphur, oxygen, carbon and hydrogen, and make up an unexpectedly large proportion. The researchers conclude that the composition of the entire planet is not yet fully understood. Nonetheless, the current investigations confirm that the core is liquid -- as suspected -- even if Mars no longer has a magnetic field.

Reaching the goal with different waveforms

The researchers obtained the new results by analysing various seismic waves generated by marsquakes. "We could already see different waves in the InSight data, so we knew how far away from the lander these quake epicentres were on Mars," Giardini says. To be able to say something about a planet's inner structure calls for quake waves that are reflected at or below the surface or at the core. Now, for the first time, researchers have succeeded in observing and analysing such waves on Mars.

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Eyes wide shut: How newborn mammals dream the world they're entering

As a newborn mammal opens its eyes for the first time, it can already make visual sense of the world around it. But how does this happen before they have experienced sight?

A new Yale study suggests that, in a sense, mammals dream about the world they are about to experience before they are even born.

Writing in the July 23 issue of Science, a team led by Michael Crair, the William Ziegler III Professor of Neuroscience and professor of ophthalmology and visual science, describes waves of activity that emanate from the neonatal retina in mice before their eyes ever open.

This activity disappears soon after birth and is replaced by a more mature network of neural transmissions of visual stimuli to the brain, where information is further encoded and stored.

"At eye opening, mammals are capable of pretty sophisticated behavior," said Crair, senior author of the study, who is also vice provost for research at Yale." But how do the circuits form that allow us to perceive motion and navigate the world? It turns out we are born capable of many of these behaviors, at least in rudimentary form."

In the study, Crair's team, led by Yale graduate students Xinxin Ge and Kathy Zhang, explored the origins of these waves of activity. Imaging the brains of mice soon after birth but before their eyes opened, the Yale team found that these retinal waves flow in a pattern that mimics the activity that would occur if the animal were moving forward through the environment.

"This early dream-like activity makes evolutionary sense because it allows a mouse to anticipate what it will experience after opening its eyes, and be prepared to respond immediately to environmental threats," Crair noted.

Going further, the Yale team also investigated the cells and circuits responsible for propagating the retinal waves that mimic forward motion in neonatal mice. They found that blocking the function of starburst amacrine cells, which are cells in the retina that release neurotransmitters, prevents the waves from flowing in the direction that mimics forward motion. This in turn impairs the development of the mouse's ability to respond to visual motion after birth.

Intriguingly, within the adult retina of the mouse these same cells play a crucial role in a more sophisticated motion detection circuit that allows them to respond to environmental cues.

Mice, of course, differ from humans in their ability to quickly navigate their environment soon after birth. However, human babies are also able to immediately detect objects and identify motion, such as a finger moving across their field of vision, suggesting that their visual system was also primed before birth.

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Astrophysicist outlines plans for the gravitational wave observatory on the moon

Vanderbilt astrophysicist Karan Jani has led a series of studies that make the first case for a gravitational wave infrastructure on the surface of the moon. The experiment, dubbed Gravitational-Wave Lunar Observatory for Cosmology, uses the moon's environment and geocentric orbit to analyze mergers of black holes, neuron stars and dark matter candidates within almost 70 percent of the entire observable volume of the universe, he said.

"By tapping into the natural conditions on the moon, we showed that one of the most challenging spectrum of gravitational waves can be measured better from the lunar surface, which so far seems impossible from Earth or space," Jani said.

"The moon offers an ideal backdrop for the ultimate gravitational wave observatory, since it lacks an atmosphere and noticeable seismic noise, which we must mitigate at great cost for laser interferometers on Earth," said Avi Loeb, professor of science at Harvard University and bestselling author of books about black holes, the first stars, the search for extraterrestrial life and the future of the universe. "A lunar observatory would provide unprecedented sensitivity for discovering sources that we do not anticipate and that could inform us of new physics. GLOC could be the jewel in the crown of science on the surface of the moon."

This work comes as NASA revives its Artemis program, which aims to send the first woman and the next man to the moon as early as 2024. Ongoing commercial work by aerospace companies, including SpaceX and BlueOrigin, also has added to the momentum behind planning for ambitious scientific infrastructure on the surface of the moon.

"In the coming years, we hope to develop a pathfinder mission on the moon to test the technologies of GLOC," Jani said. "Unlike space missions that last only a few years, the great investment benefit of GLOC is it establishes a permanent base on the moon from where we can study the universe for generations, quite literally the entirety of this century." Currently the observatory is theoretical, with Jani and Loeb receiving a strong endorsement from the international gravitational-wave community.

"It was a great privilege to collaborate with an innovative young thinker like Karan Jani," Loeb said. "He may live long enough to witness the project come to fruition."

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New measure of tropical forest vulnerability to help avoid 'tipping point'

Humid tropical forests, vital in global efforts to limit rising temperatures, are under threat as a result of changes in land use and climate. Now, researchers reporting in the journal One Earth on July 23 have developed a new way to keep tabs on the vulnerability of these forests on a global scale using satellite data. Called the tropical forest vulnerability index (TFVI), the hope is that this method will serve as an early warning for areas that are under the greatest threat to enable actions aimed at protecting these forests before it's too late.

"Frequent droughts, higher temperature, and longer dry seasons, along with increasing pressures from deforestation and degradation in the last two decades, have pushed the tropical rainforests to the verge of a tipping point," said Sassan Saatchi of NASA's Jet Propulsion Laboratory. "What we predicted using climate models a decade ago, we are observing on the ground. Now is the time to do something and not later. This work takes advantage of a suite of satellite observations made for the past few decades to show how and where the tipping points may be reached and to help policy makers plan for conservation and restoration of these forests."

There have been other ways to measure the vulnerability of rainforests. However, most of them relied on local studies and couldn't easily be extended to larger regions or the globe. This lack of consistency and ability to make comparisons from one region to another has led to confusion and inaction. To get around these stumbling blocks, Saatchi and colleagues set out to develop a unique tropical rainforest vulnerability index that could work across all rainforests based on observations of climate and vegetation from satellites.

The new index combines numerous measurements and indicators of forest ecological functions and services, including carbon and water fluxes and biodiversity. It also provides spatial information with monthly updates and allows researchers to identify and monitor areas with increasing vulnerability or potential threats before it's too late.

Their studies have shown that different regions of the tropics are responding differently to climate threats, with some regions showing more apparent resilience than others. For instance, forests in the Americas appear to be more vulnerable to stresses than those in Africa, where they are showing relative resilience to changing climate. In Asia, tropical forests appear more vulnerable to land use and fragmentation.

Individual rain forests also show important differences in their response to climate and land use pressures. For instance, the Amazon Basin shows large-scale vulnerability to drying condition in the atmosphere, with frequent droughts and large-scale land use changes. The Congo Basin, on the other hand, appears more resilient because of the historical impacts of droughts, the overall dryer condition, and smaller-scale land use change and fragmentation.

The researchers also uncovered strong interactions between climate, land use, and biodiversity that define the vulnerability and resilience of forests. The new index allowed them to identify the nature of these interactions over all global rainforests.

"The findings show that the vulnerability of rainforests is much larger than predicted in the past, and areas that are disturbed or fragmented have almost no resilience to climate warming and droughts," Saatchi said. "In addition, the results of our study suggest that rainforests are losing their capacity to cycle carbon and water as before. This is occurring gradually at the continental scale and more rapidly at the regional scale, with significant implications for the global carbon sink and climate."

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Bio-based coating for wood outperforms traditional synthetic options

Due to the global efforts to meet sustainability standards, many countries are currently looking to replace concrete with wood in buildings. France, for example, will require that all new public buildings will be made from at least 50 percent wood or other sustainable materials starting in 2022.

Because wood is prone to degradation when exposed to sunlight and moisture, protective coatings can help bring wood into wider use. Researchers at Aalto University have used lignin, a natural polymer abundant in wood and other plant sources, to create a safe, low-cost and high-performing coating for use in construction.

'Our new coating has great potential to protect wood. It's more water repellent than a lot of commercial coatings because it retains the natural structure of wood and its micro-scaled roughness. Since it's hydrophobic, the coating is also quite resistant to stains, while lignin's inherent structure resists colour changes from sunlight. It also does an excellent job of retaining wood's breathability,' explains Alexander Henn, doctoral candidate at Aalto University, The School of Chemical Engineering.

Lignin is often regarded as a waste product of pulping and biorefinery processes. Each year, about 60-120 million tonnes of lignin is isolated worldwide, of which 98 percent is incinerated for energy recovery. Lignin has several beneficial properties; however, the poor solubility of most lignin types and the mediocre performance of lignin-based products have so far limited its commercial applications.

'Lignin as a coating material is actually very promising with its many benefits compared to the synthetic and bio-based coatings currently used. It has excellent anti-corrosion, anti-bacterial, anti-icing, and UV-shielding properties. Our future research will concentrate on developing characteristics like elasticity of the coating', says Monika Österberg, Head of the Department of Bioproducts and Biosystems at Aalto University.

Currently, widely used mechanically protective coatings for materials such as wood, concrete, metals, and composites are petroleum-based, which include substances that are harmful for the environment. Vegetable-oil coatings -- like those made from tall, linseed, coconut, soybean, and castor -- can be more sustainable alternatives but they often lack durability. As a result, these oils are often combined with synthetic materials to improve their performance.

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Brain-repair discovery could lead to new epilepsy treatments

University of Virginia School of Medicine researchers have discovered a previously unknown repair process in the brain that they hope could be harnessed and enhanced to treat seizure-related brain injuries.

Common seizure-preventing drugs do not work for approximately a third of epilepsy patients, so new and better treatments for such brain injuries are much needed. UVA's discovery identifies a potential avenue, one inspired by the brain's natural immune response.

Using high-powered imaging, the researchers were able to see, for the first time, that immune cells called microglia were not just removing damaged material after experimental seizures but actually appeared to be healing damaged neurons.

"There has been mounting generic support for the idea that microglia could be used to ameliorate seizures, but direct, visualized evidence for how they could do this has been lacking," said researcher Ukpong B. Eyo, PhD, of UVA's Department of Neuroscience, the UVA Brain Institute and UVA's Center for Brain Immunology and Glia (BIG). "Our results indicate that microglia may not be simply clearing debris but providing structural support for neuronal integrity that may have implications even beyond the scope of seizures and epilepsy."

A Surprising Response to Seizures

The new findings come from a collaboration of scientists at UVA, Mayo Clinic and Rutgers University. They used an advanced imaging technique called two-photon microscopy to examine what happened in the brains of lab mice after severe seizures. What they saw was strange and unexpected.

Rather than simply cleaning up debris, the microglia began forming pouches. These pouches didn't swallow up damaged material, as many immune cells do. Instead, they began tending to swollen dendrites -- the branches of nerve cells that transmit nerve impulses. They weren't removing, the scientists realized; they appeared to be healing.

These odd little pouches -- the scientists named them "microglial process pouches" -- stuck around for hours. They often shrank, but they were clearly doing something beneficial because the dendrites they targeted ended up looking better and healthier than those they didn't.

"We did not find microglia to be 'eating' the neuronal elements in this context," Eyo said. "Rather, we saw a strong correlation between these interactions and a structural resolution of injured neurons suggestive of a 'healing' process."

The new insights into the brain's immune response points scientists in promising new directions. "Although these findings are exciting, there is yet a lot to follow-up on them. For example, the precise mechanisms that regulate the interactions remain to be identified. Moreover, at present, the 'healing' feature is suggested from correlational results and more definitive studies are required to certify the nature of the 'healing,'" Eyo said. "If these questions can be answered, they will provide a rationale for developing approaches to enhance this process ... in seizure contexts."

Eyo has already received two grants totaling almost $5 million from the National Institutes of Health to continue his study of microglia. The funding will allow him to study how the immune cells help regulate vascular function, which could be important in diseases such as Alzheimer's, and their role in brain-hyperactivity disorders such as febrile seizures that can trigger epilepsy.

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Long-period oscillations of Sun discovered

These motions were measured by analyzing 10 years of observations from NASA's Solar Dynamics Observatory (SDO). Using computer models, the scientists have shown that the newly discovered oscillations are resonant modes and owe their existence to the Sun's differential rotation. The oscillations will help establish novel ways to probe the Sun's interior and obtain information about our star's inner structure and dynamics. The scientists describe their findings in today's issue of the journal Astronomy & Astrophysics.

In the 1960s the Sun'ss high musical notes were discovered: The Sun rings like a bell. Millions of modes of acoustic oscillations with short periods, near 5 minutes, are excited by convective turbulence near the solar surface and are trapped in the solar interior. These 5-minute oscillations have been observed continuously by ground-based telescopes and space observatories since the mid 1990s and have been used very successfully by helioseismologists to learn about the internal structure and dynamics of our star -- just like seismologists learn about the interior of the Earth by studying earthquakes. One of the triumphs of helioseismology is to have mapped the Sun's rotation as a function of depth and latitude (the solar differential rotation).

In addition to the 5-minute oscillations, much longer-period oscillations were predicted to exist in stars more than 40 years ago, but had not been identified on the Sun until now. "The long-period oscillations depend on the Sun's rotation; they are not acoustic in nature," says Laurent Gizon, lead author of the new study and director at the MPS. "Detecting the long-period oscillations of the Sun requires measurements of the horizontal motions at the Sun's surface over many years. The continuous observations from the Helioseismic and Magnetic Imager (HMI) onboard SDO are perfect for this purpose."

The team observed many tens of modes of oscillation, each with its own oscillation period and spatial dependence. Some modes of oscillation have maximum velocity at the poles, some at mid-latitudes, and some near the equator. The modes with maximum velocity near the equator are Rossby modes, which the team had already identified in 2018. "The long-period oscillations manifest themselves as very slow swirling motions at the surface of the Sun with speeds of about 5 kilometers per hour -- about how fast a person walks," says Zhi-Chao Liang from MPS. Kiran Jain from NSO, together with B. Lekshmi and Bastian Proxauf from MPS, confirmed the results with data from the Global Oscillation Network Group (GONG), a network of six solar observatories in the USA, Australia, India, Spain, and Chile.

To identify the nature of these oscillations, the team compared the observational data to computer models. "The models allow us to look inside the Sun's interior and determine the full three-dimensional structure of the oscillations," explains MPS graduate student Yuto Bekki. To obtain the model oscillations, the team began with a model of the Sun's structure and differential rotation inferred from helioseismology. In addition, the strength of the convective driving in the upper layers, and the amplitude of turbulent motions are accounted for in the model. The free oscillations of the model are found by considering small-amplitude perturbations to the solar model. The corresponding velocities at the surface are a good match to the observed oscillations and enabled the team to identify the modes.

"All of these new oscillations we observe on the Sun are strongly affected by the Sun's differential rotation," says MPS scientist Damien Fournier. The dependence of the solar rotation with latitude determines where the modes have maximum amplitudes. "The oscillations are also sensitive to properties of the Sun's interior: in particular to the strength of the turbulent motions and the related viscosity of the solar medium, as well as to the strength of the convective driving," says Robert Cameron from MPS. This sensitivity is strong at the base of the convection zone, about two hundred thousand kilometers beneath the solar surface. "Just like we are using acoustic oscillations to learn about the sound speed in the solar interior with helioseismology, we can use the long-period oscillations to learn about the turbulent processes," he adds.

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No link between moderate coffee consumption and increased risk of cardiac arrhythmia, researchers find

In the largest study of its kind, an investigation by UC San Francisco has found no evidence that moderate coffee consumption leads to a greater risk of cardiac arrhythmia.

In fact, each additional daily cup of coffee consumed among several hundred thousand individuals was associated with a 3 percent lower risk of any arrhythmia occurring, including atrial fibrillation, premature ventricular contractions, or other common heart conditions, the researchers report. The study included a four-year follow up.

The paper is published July 19, 2021, in JAMA Internal Medicine.

"Coffee is the primary source of caffeine for most people, and it has a reputation for causing or exacerbating arrhythmias," said senior and corresponding author Gregory Marcus, MD, professor of medicine in the Division of Cardiology at UCSF.

"But we found no evidence that caffeine consumption leads to a greater risk of arrhythmias," said Marcus, who specializes in the treatment of arrhythmias. "Our population-based study provides reassurance that common prohibitions against caffeine to reduce arrhythmia risk are likely unwarranted."

While some professional societies suggest avoiding caffeinated products to lower the risk for arrhythmia, this connection has not been consistently demonstrated -- indeed, coffee consumption may have anti-inflammatory benefits and is associated with reduced risks of some illnesses including cancer, diabetes, and Parkinson disease.

In the new study, UCSF scientists explored whether habitual coffee intake was associated with a risk of arrhythmia, and whether genetic variants that affect caffeine metabolism could modify that association. Their investigation was conducted via the community-based UK Biobank, a prospective study of participants in England's National Health Services.

Some 386,258 coffee drinkers took part in the coffee research, with an average mean age of 56 years; slightly more than half were female. It was an unprecedented sample size for this type of inquiry.

In addition to a conventional analysis examining self-reported coffee consumption as a predictor of future arrhythmias, the investigators employed a technique called "Mendelian Randomization," leveraging genetic data to infer causal relationships. As those with the genetic variants associated with faster caffeine metabolism drank more coffee, this analysis provided a method to test the caffeine-arrhythmia relationship in a way that did not rely on participant self-report and should have been immune to much of the confounding inherent to most observational studies.

With a mean four-year follow up, data were adjusted for demographic characteristics, health and lifestyle habits.

Ultimately, approximately 4 percent of the sample developed an arrhythmia. No evidence of a heightened risk of arrhythmias was observed among those genetically predisposed to metabolize caffeine differently. The researchers said that higher amounts of coffee were actually associated with a 3 percent reduced risk of developing an arrhythmia.

The authors noted limitations including the self-reporting nature of the study, and that detailed information on the type of coffee -- such as espresso or not -- was unavailable.

"Only a randomized clinical trial can definitively demonstrate clear effects of coffee or caffeine consumption," said Marcus. "But our study found no evidence that consuming caffeinated beverages increased the risk of arrhythmia. Coffee's antioxidant and anti-inflammatory properties may play a role, and some properties of caffeine could be protective against some arrhythmias."

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'Springing forward' affects early birds less than night owls

Every spring, the Daylight Saving Time shift robs people of an hour of sleep -- and a new study shows that DNA plays a role in how much the "spring forward" time change affects individuals.

People whose genetic profile makes them more likely to be "early birds" the rest of the year can adjust to the time change in a few days, the study shows. But those who tend to be "night owls" could take more than a week to get back on track with sleep schedule, according to new data published in Scientific Reports by a team from the University of Michigan.

The study uses data from continuous sleep tracking of 831 doctors in the first year of post-medical school training when the time shift occurred in spring 2019. All were first-year residents or "interns" in medical parlance, and taking part in the Intern Health Study based at the Michigan Neuroscience Institute.

From the large UK Biobank dataset, the researchers calculated genomic "chronotype" predisposition information, also known as the Objective Sleep Midpoint polygenic score. People with low scores were genomically predisposed to be "early birds" and those with high scores were genomically "night owls."

The team then applied these genomic scores in the intern sample and focused on the two groups of about 130 physicians each that had the strongest tendencies to be "early birds" and "night owls" based on their scores. The researchers looked at how their sleep patterns changed from the week before DST to the weekend after it.

In general, the difference in post-DST weekday wakeup times between the two groups was not large -- probably because first-year medical residents have very strict work schedules.

In fact, the stressful duties and demanding schedules that interns endure is what made this population such an interesting one to study, and the larger Intern Health Study that the data come from has yielded important findings about the relationship between stress, sleep, genetics, mood and mental health.

But the time they got to sleep on the nights before workdays, and both sleep and wake times on the weekend, varied significantly between the two groups. The DST change made the differences even more pronounced.

Early birds had adjusted their sleep times by Tuesday, but night owls were still off track on the following Saturday.

Margit Burmeister, Ph.D., the U-M neuroscientist and geneticist who is the paper's senior and corresponding author, says the study gives one more strong reason for abolishing Daylight Saving Time.

"It's already known that DST has effects on rates of heart attacks, motor vehicle accidents, and other incidents, but what we know about these impacts mostly comes from looking for associations in large data pools after the fact," she says. "These data from direct monitoring and genetic testing allows us to directly see the effect, and to see the differences between people with different circadian rhythm tendencies that are influenced by both genes and environment. To put it plainly, DST makes everything worse for no good reason."

The study's first author is Jonathan Tyler, Ph.D., a postdoctoral assistant professor of mathematics at U-M.

Sleep schedules depend on a combination of many factors -- but the fact that people can react so differently to the same abrupt change in time makes it important to study further. The researchers also looked at the "fall back" time change in autumn and found no significant differences between early birds and night owls in how they reacted to the abrupt addition of an hour of sleep.

The findings have implications not just for the annual spring time change, but also for shift workers, travelers across time zones and even people deciding which profession to choose, the researchers note. Burmeister says she hopes to look further at differences between people in different professions in future studies.

Co-author Srijan Sen, M.D., Ph.D. who leads the Intern Health Study and directs the Frances and Kenneth Eisenberg and Family Depression Center at U-M, continues to lead other studies of how each year's crop of interns at over 100 hospitals react to the stresses of their training. The interns in the newly published study, like all interns, are in general chronically sleep-deprived because of the number of hours they need to be on duty or preparing for duty.

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Effectiveness of mRNA vaccines against the Alpha and Beta variants in France

Over the past six months, the World Health Organization has categorized four SARS-CoV-2 variants as being "of concern" because they are more transmissible or may escape the immune response. They have been termed the Alpha, Beta, Gamma and Delta variants.

Scientists from the Institut Pasteur, in collaboration with the French National Health Insurance Fund (CNAM), Ipsos and Santé publique France, conducted a nationwide case-control study to evaluate the effectiveness of mRNA vaccines against symptomatic forms of SARS-CoV-2 infection, be that non-variant virus or the Alpha and Beta variants. The results show that the two-dose vaccination regimen of mRNA vaccines provides 88% protection against non-variant virus, 86% against the Alpha variant and 77% against the Beta variant. The results of this study were published in The Lancet Regional Health Europe on July 14, 2021.

In late 2020, two new variants of SARS-CoV-2 were reported in the United Kingdom and in South Africa, respectively. This occurred at a time when the United Kingdom was experiencing a resurgence in the incidence of SARS-CoV-2 infections. This was later attributed to the emergence of the Alpha variant, which has now demonstrated increased transmissibility as compared to the original SARS-CoV-2. The Beta variant was first reported in South Africa and later identified to carry a mutation known as E484K and which is associated with immune evasion. The reporting of the first SARS-CoV-2 variants occurred as mass COVID-19 vaccination campaigns were commencing at global level. In France, both Alpha and Beta were circulating in the first months of 2021. It was therefore important to analyze the effectiveness of the messenger RNA (mRNA) COVID-19 vaccines against these SARS-CoV-2 variants of concern.

In October 2020, the Institut Pasteur, in collaboration with the French National Health Insurance Fund (CNAM), Ipsos and Santé publique France, launched the ComCor study, a case-control study at national level to analyze the sociodemographic, behavioral and practical factors associated with SARS-CoV-2 infection. All those infected with SARS-CoV-2 were invited to take part in the study by the CNAM, while non-infected control were identified through an Ipsos representative panel. The first results of the study were published in The Lancet Regional Health on June 7, 2021.

In February 2021, the scientists adapted the ComCor questionnaire to add information about vaccination against COVID-19, previous SARS-CoV-2 infection and information on the variants responsible for infection, provided as part of test results. This information was used to assess the effectiveness of two doses of mRNA vaccine against the Alpha and Beta variants, and to evaluate the protection conferred by previous SARS-CoV-2 infection.

In this study, 7,288 people infected with the original strain, 31,313 people infected with the Alpha variant, 2,550 people infected with the Beta variant and 3,644 non-infected controls were included between February and May 2021. The study enabled the scientists to demonstrate that two doses of mRNA vaccine conferred 88% (81-92) effectiveness against infection with original virus, 86% (81-90) effectiveness against infection with the Alpha variant and 77% (71-90) effectiveness against infection with the Beta variant, as measured seven days after the second dose. No difference in vaccine effectiveness was found between different categories of age, sex or occupational exposure.

"There was much expectation surrounding the (vaccine effectiveness) results for the Beta variant, known for its E484K mutation associated with immune evasion. Our estimate of 77% protection is very close to the estimate of 75% reached by the only other study worldwide to have evaluated the effectiveness of mRNA vaccines against this variant. These analyses confirm the effectiveness of the COVID-19 vaccines and the key role that they have to play in tackling the epidemic," explains Arnaud Fontanet, Head of the Epidemiology of Emerging Diseases Unit at the Institut Pasteur and Professor at the Conservatoire National des Arts et Métiers (CNAM).

Another important finding of the study related to previous SARS-CoV-2 infection. The scientists demonstrated that recent infection (in the past 2 to 6 months) confers similar protection to that observed with mRNA vaccines.

The analyses will now be extended to estimate vaccine effectiveness against the Delta variant, which has been the dominant variant in France since early July 2021.

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Supermassive black holes put a brake on stellar births

Black holes with masses equivalent to millions of suns do put a brake on the birth of new stars, say astronomers. Using machine learning and three state of the art simulations to back up results from a large sky survey, the researchers resolve a 20-year long debate on the formation of stars. Joanna Piotrowska, a PhD student at the University of Cambridge, will present the new work today (Tuesday 20 July) at the virtual National Astronomy Meeting (NAM 2021).

Star formation in galaxies has long been a focal point of astronomy research. Decades of successful observations and theoretical modelling resulted in our good understanding of how gas collapses to form new stars both in and beyond our own Milky Way. However, thanks to all-sky observing programmes like the Sloan Digital Sky Survey (SDSS), astronomers realised that not all galaxies in the local Universe are actively star-forming -- there exists an abundant population of "quiescent" objects which form stars at significantly lower rates.

The question of what stops star formation in galaxies remains the biggest unknown in our understanding of galaxy evolution, debated over the past 20 years. Piotrowska and her team set up an experiment to find out what might be responsible.

Using three state-of-the-art cosmological simulations -- EAGLE, Illustris and IllustrisTNG -- the astronomers investigated what we would expect to see in the real Universe as observed by the SDSS, when different physical processes were halting star formation in massive galaxies.

The astronomers applied a machine learning algorithm to classify galaxies into star-forming and quiescent, asking which of three parameters: the mass of the supermassive black holes found at the centre of galaxies (these monster objects have typically millions or even billions of times the mass of our Sun), the total mass of stars in the galaxy, or the mass of the dark matter halo around galaxies, best predicts how galaxies turn out.

These parameters then enabled the team to work out which physical process: energy injection by supermassive black holes, supernova explosions or shock heating of gas in massive halos is responsible for forcing galaxies into semi-retirement.

The new simulations predict the supermassive black hole mass as the most important factor in putting the brakes on star formation. Crucially, the simulation results match observations of the local Universe, adding weight to the researchers' findings.

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Dark heart of the nearest radio galaxy

An international team anchored by the Event Horizon Telescope (EHT) Collaboration, which is known for capturing the first image of a black hole in the galaxy Messier 87, has now imaged the heart of the nearby radio galaxy Centaurus A in unprecedented detail. The astronomers pinpoint the location of the central supermassive black hole and reveal how a gigantic jet is being born. Most remarkably, only the outer edges of the jet seem to emit radiation, which challenges our theoretical models of jets. This work, led by Michael Janssen from the Max Planck Institute for Radio Astronomy in Bonn and Radboud University Nijmegen is published in Nature Astronomy on July 19th.

At radio wavelengths, Centaurus A emerges as one of the largest and brightest objects in the night sky. After it was identified as one of the first known extragalactic radio sources in 1949, Centaurus A has been studied extensively across the entire electromagnetic spectrum by a variety of radio, infrared, optical, X-ray, and gamma-ray observatories. At the center of Centaurus A lies a black hole with the mass of 55 million suns, which is right between the mass scales of the Messier 87 black hole (six and a half billion suns) and the one in the center of our own galaxy (about four million suns).

In a new paper in Nature Astronomy, data from the 2017 EHT observations have been analyzed to image Centaurus A in unprecedented detail. "This allows us for the first time to see and study an extragalactic radio jet on scales smaller than the distance light travels in one day. We see up close and personally how a monstrously gigantic jet launched by a supermassive black hole is being born," says astronomer Michael Janssen.

Compared to all previous high-resolution observations, the jet launched in Centaurus A is imaged at a tenfold higher frequency and sixteen times sharper resolution. With the resolving power of the EHT, we can now link the vast scales of the source, which are as big as 16 times the angular diameter of the Moon on the sky, to their origin near the black hole in a region of merely the width of an apple on the Moon when projected on the sky. That is a magnification factor of one billion.

Understanding jets

Supermassive black holes residing in the center of galaxies like Centaurus A are feeding off gas and dust that is attracted by their enormous gravitational pull. This process releases massive amounts of energy and the galaxy is said to become 'active'. Most matter lying close to the edge of the black hole falls in. However, some of the surrounding particles escape moments before capture and are blown far out into space: Jets -- one of the most mysterious and energetic features of galaxies -- are born.

Astronomers have relied on different models of how matter behaves near the black hole to better understand this process. But they still do not know exactly how jets are launched from its central region and how they can extend over scales that are larger than their host galaxies without dispersing out. The EHT aims to resolve this mystery.

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Championing chrononutrition with protein, the morning elixir for muscle growth

Proteins constitute an essential dietary component that help in the growth and repair of the body. Composed of long chains of amino acids, proteins promote the growth of skeletal muscles, the group of muscles that help us move. Humans have been aware of the benefits of proteins for long. However, recent studies have shown that having the right amount of protein at the right time of the day is essential for proper growth. This is called 'Chrononutrition,' in which when you eat is as important as what and how you eat.

The reason behind this is the body's internal biological clock, called the 'circadian rhythm.' This rhythm is followed by all cells and controls life functions like metabolism and growth. Interestingly, protein digestion and absorption have been found to fluctuate across day and night according to this clock. Moreover, earlier studies have reported that intake of protein at breakfast and lunch promotes skeletal muscle growth in adults. However, details on the effect of the time of protein intake on muscle growth and function have remained elusive till date.

Fortunately, researchers from Waseda University, led by Professor Shigenobu Shibata, recently endeavored to understand the effect of the distribution of protein intake through the day on muscles. They fed laboratory mice two meals per day containing either high (11.5% by proportion) or low (8.5% by proportion) protein concentrations. The researchers noted that protein intake at breakfast induced an increase in muscle growth, determined by assessing induced hypertrophy of the plantaris muscle in the leg, when compared with the effects of protein intake at dinner. Specifically, the ratio of muscle hypertrophy determined against the growth of the control muscle was 17% higher in mice fed 8.5% protein at breakfast, than that in mice fed 11.5% protein at dinner, despite the former group consuming a low proportion of protein overall. They also found that intake of a type of protein called the BCCA, short for branched-chain amino acids, early in the day increased the size of skeletal muscles specifically.

To confirm the association of these effects with the workings of the circadian rhythm, the researchers next engineered whole-body mutant Clock?19 or muscle-specific Bmal1 knockout mice lacking the genes that control the biological clock. They repeated diet distribution experiments on these mice but did not observe similar muscle change, which confirmed the involvement of the circadian rhythm in muscle growth in the context of protein intake.

Excited about the findings of their study published in a recent issue of the Cell Reports, Prof. Shibata emphasizes, "Protein-rich diet at an early phase of the daily active period, that is at breakfast, is important to maintain skeletal muscle health and enhance muscle volume and grip strength."

To check if their findings were applicable to humans, the team recruited women in their study and tested if their muscle function, determined by measuring skeletal muscle index (SMI) and grip strength, varied with the timing of the protein-rich diet consumed. Sixty women aged 65 years and above who took protein at breakfast rather than at dinner showed better muscle functions, suggesting the possibility of the findings to be true across species. Additionally, the researchers also found a strong association between SMI and the proportion of protein intake at breakfast relative to total protein intake through the day.

Prof. Shibata is hopeful that the findings of their study will lead to a widespread modification in the current diet regime of most people across the Western and Asian countries, who traditionally consume low amounts of protein at breakfast. He therefore stresses, "For humans, in general, the protein intake at breakfast averages about 15 grams, which is less than what we consume at dinner, which is roughly 28 grams. Our findings strongly support changing this norm and consuming more protein at breakfast or morning snacking time."

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Living near woodlands is good for children and young people's mental health

Analysis of children and young people's proximity to woodlands has shown links with better cognitive development and a lower risk of emotional and behavioural problems, in research led by UCL and Imperial College London scientists that could influence planning decisions in urban areas.

In what is believed to be one of the largest studies of its kind, researchers used longitudinal data relating to 3,568 children and teenagers, aged nine to 15 years, from 31 schools across London. This period is a key time in the development of adolescents' thinking, reasoning and understanding of the world.

The study, published in Nature Sustainability, looked at the links between different types of natural urban environments and the pupils' cognitive development, mental health and overall well-being.

The environments were divided into what planners call green space (woods, meadows and parks) and blue space (rivers, lakes and the sea), with green space separated further into grassland and woodland. Researchers used satellite data to help calculate each adolescent's daily exposure rate to each of these environments within 50m, 100m, 250m and 500m of their home and school.

After adjusting for other variables, the results showed that higher daily exposure to woodland (but not grassland) was associated with higher scores for cognitive development, and a 16% lower risk of emotional and behavioural problems two years later.

A similar but smaller effect was seen for green space, with higher scores for cognitive development, but this was not seen for blue space. The researchers note though that access to blue space in the cohort studied was generally low.

Examples of other explanatory variables considered included the young person's age, ethnic background, gender, parental occupation and type of school, e.g., state or independent. The level of air pollution might have influenced adolescents' cognitive development, but researchers did not feel these observations were reliable or conclusive, and these require further investigations.

It is already estimated that one in 10 of London's children and adolescents between the ages of five and 16 suffer from a clinical mental health illness and excess costs are estimated between £11,030 and £59,130 annually for each person. As with adults, there is also evidence that natural environments play an important role in children and adolescents' cognitive development and mental health into adulthood, but less is known about why this is.

The results of this study suggest that urban planning decisions to optimise ecosystem benefits linked to cognitive development and mental health should carefully consider the type of natural environment included. Natural environments further away from an adolescent's residence and school may play an important role too, not just their immediate environment.

Lead author, PhD student Mikaël Maes (UCL Geography, UCL Biosciences and Imperial College London School of Public Health) said: "Previous studies have revealed positive associations between exposure to nature in urban environments, cognitive development and mental health. Why these health benefits are received remains unclear, especially in adolescents.

"These findings contribute to our understanding of natural environment types as an important protective factor for an adolescent's cognitive development and mental health and suggest that not every environment type may contribute equally to these health benefits.

"Forest bathing, for example (being immersed in the sights, sounds and smells of a forest), is a relaxation therapy that has been associated with physiological benefits, supporting the human immune function, reducing heart rate variability and salivary cortisol, and various psychological benefits. However, the reasons why we experience these psychological benefits from woodland remain unknown."

Joint senior author Professor Mireille Toledano (Director, Mohn Centre for Children's Health and Wellbeing and Investigator, MRC Centre for Environment and Health and Principal Investigator of the SCAMP study, Imperial College London) said: "It's been suggested previously that the benefits of natural environments to mental health are comparable in magnitude to family history, parental age and even more significant than factors like the degree of urbanisation around you, but lower than your parents' socio-economic status. Sensory and non-sensory pathways have been suggested as potentially important for delivering cognition and mental health benefits received from exposure to nature.

"It's critical for us to tease out why natural environments are so important to our mental health throughout the life course -- does the benefit derive from the physical exercise we do in these environments, from the social interactions we often have in them, or from the fauna and flora we get to enjoy in these environments or a combination of all of these?"

Joint senior author Professor Kate Jones (UCL Centre for Biodiversity & Environment Research, UCL Biosciences) said: "One possible explanation for our findings may be that audio-visual exposure through vegetation and animal abundance provides psychological benefits, of which both features are expected in higher abundance in woodland. Even though our results show that urban woodland is associated with adolescent's cognitive development and mental health, the cause of this association remains unknown. Further research is fundamental to our understanding of the links between nature and health."

To arrive at the findings, researchers analysed a longitudinal dataset of 3,568 adolescents between 2014 and 2018, whose residence was known, from the Study of Cognition, Adolescents and Mobile Phones (SCAMP) across the London metropolitan area. They assessed adolescents' mental health and overall well-being from a self-reported Strengths and Difficulties Questionnaire (SDQ) -- covering areas such as emotional problems, conduct, hyperactivity and peer problems -- and the KIDSCREEN-10 Questionnaire taken by each adolescent for SCAMP.

Limitations of the study include an assumption that living or going to school near natural environments means more exposure to them, which may not always be the case due to how easily they can be accessed by a child or young person or how usable they are.

Also, a considerable proportion of the participants (52.21%) were in the group whose parents had a managerial/professional occupation, so adolescents in less favourable socio-economic groups may be underrepresented and pupils requiring special needs may be differently affected compared with their peers. Crime rates, which may have influenced the results too, were not taken into account.

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Spinal fluid biomarkers detect neurodegeneration, Alzheimer's disease in living patients

Alzheimer's disease and related diseases can still only be confirmed in deceased patients' brains via autopsy. Even so, the development of biomarkers can give patients and their families answers during life: Alzheimer's disease can be accurately detected via peptides and proteins in a patient's cerebrospinal fluids (CSF), which can be collected through a lumbar puncture and tested while the patient is alive. In 2018, a new framework suggested combining three Alzheimer's disease biomarkers in CSF -- pathologic amyloid plaques (A), tangles (T), and neurodegeneration (N), collectively called ATN. According to recent research from the Perelman School of Medicine at the University of Pennsylvania, the ATN framework can be extended to detect another neurodegenerative condition: frontotemporal degeneration.

Patients with frontotemporal degeneration can experience a range of symptoms, including behavioral changes, executive dysfunction, and language impairments. Distinguishing frontotemporal degeneration from Alzheimer's disease can be a challenge for clinicians: the symptoms of frontotemporal degeneration can sometimes overlap with Alzheimer's disease, and a subset of patients can even have both pathologies. Biomarkers can fill the gap by providing evidence of whether Alzheimer's pathology underlies a patient's symptoms.

"CSF biomarkers work similarly to a pregnancy test, offering a simple positive or negative result when enough of a substance is detected. But like a pregnancy test, biomarkers for Alzheimer's disease can provide false negatives or positives," said lead investigator Katheryn A.Q. Cousins, PhD, a research associate in the Frontotemporal Degeneration Center in the Department of Neurology at Penn Medicine. "Alzheimer's is a diverse disease, and it is common for other conditions to also be present in the brain. The ATN framework may provide a more complete look at a person's diagnosis and give us a much richer understanding of not only Alzheimer's disease, but other co-occurring neurodegenerative conditions. However, to accomplish this, additional biomarkers that can detect other neurodegenerative conditions are critically needed."

The findings, published in Alzheimer's and Dementia: The Journal of the Alzheimer's Association, show that ATN incorporating neurofilament light chain (NfL) may provide a more accurate and precise diagnosis for patients with frontotemporal degeneration. NfL is a protein abundant in the brain, whose levels increase as degeneration progresses. Cousins' work shows that CSF NfL may be a more accurate marker of neurodegeneration for patients with frontotemporal degeneration, including for Alzheimer's disease.

"While the ATN framework is very exciting and offers much opportunity for patients with Alzheimer's disease, these biomarkers don't capture every case of the disease. We want to be able to detect and treat every patient with neurodegenerative disease as early as possible, and more research is needed to fully understand how biofluids track with the disease process," said Cousins. "I am eager to conduct additional research into which patients might be missed by these markers, what they have in common, and what causes the pathological and clinical differences in the disease."

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Cosmic rays help supernovae explosions pack a bigger punch

The final stage of cataclysmic explosions of dying massive stars, called supernovae, could pack an up to six times bigger punch on the surrounding interstellar gas with the help of cosmic rays, according to a new study led by researchers at the University of Oxford. The work will be presented by PhD student Francisco Rodríguez Montero today (19 July) at the virtual National Astronomy Meeting (NAM 2021).

When supernovae explode, they emit light and billions of particles into space. While the light can freely reach us, particles become trapped in spiral loops by magnetic shockwaves generated during the explosions. Crossing back and forth through shock fronts, these particles are accelerated almost to the speed of light and, on escaping the supernovae, are thought to be the source of the mysterious form of radiation known as cosmic rays.

Due to their immense speed, cosmic rays experience strong relativistic effects, effectively losing less energy than regular matter and allowing them to travel great distances through a galaxy. Along the way, they affect the energy and structure of interstellar gas in their path and may play a crucial role in shutting down the formation of new stars in dense pockets of gas. However, to date, the influence of cosmic rays in galaxy evolution has not been well understood.

In the first high-resolution numerical study of its kind, the team ran simulations of the evolution of the shockwaves emanating from supernovae explosions over several million years. They found that cosmic rays can play a critical role in the final stages of a supernova's evolution and its ability to inject energy into the galactic gas that surrounds it.

Rodríguez Montero explains: "Initially, the addition of cosmic rays does not appear to change how the explosion evolves. Nevertheless, when the supernova reaches the stage in which it cannot gain more momentum from the conversion of the supernova's thermal energy to kinetic energy, we found that cosmic rays can give an extra push to the gas, allowing for the final momentum imparted to be up to 4-6 times higher than previously predicted."

The results suggest that gas outflows driven from the interstellar medium into the surrounding tenuous gas, or circumgalactic medium, will be dramatically more massive than previously estimated.

Contrary to state-of-the-art theoretical arguments, the simulations also suggest that the extra push provided by cosmic rays is more significant when massive stars explode in low-density environments. This could facilitate the creation of super-bubbles powered by successive generations of supernovae, sweeping gas from the interstellar medium and venting it out of galactic discs.

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New alpine moth solves 180-year-old mystery

Butterflies and moths (order Lepidoptera) are one of the most diverse animal groups. To date, scientists have found as many as 5,000 species from the Alps alone. Having been a place of intensive research interest for 250 years, it is considered quite a sensation if a previously unknown species is discovered from the mountain range these days. This was the case when a Swiss-Austrian team of researchers described a new species of alpine moth in the open-access, peer-reviewed journal Alpine Entomology, solving a 180-year-old mystery.

Decades of research work

Initially, the team -- Jürg Schmid, a full-time dentist, author and passionate butterfly and moth researcher from Switzerland, and Peter Huemer, head of the natural science collections of the Tyrolean State Museums in Innsbruck and author of more than 400 publications, needed a lot of patience.

Almost thirty years ago, in the 1990s, the two researchers independently discovered the same moth species. While they found it was similar to a moth of the leaf-roller family Tortricidae and commonly named as Dichrorampha montanana which had been known to science since 1843, it was also clearly different. Wing pattern and internal morphology of genitalia structures supported a two-species hypothesis. Moreover, the two were found at the same time in the same places -- a further indication that they belong to separate species. Extensive genetic investigations later confirmed this hypothesis, but the journey of presenting a new species to science was far from over.

The Hidden Alpine Moth

To "baptise" a new species and give it its own name, scientists first have to check that it hasn't already been named. This prevents the same species from having two different names, and essentially means looking at descriptions of similar species and comparing the new one against them to prove it is indeed unknown to science. In the case of this new moth, there were six potentially applicable older names that had to be ruled out before it could be named as new.

Intensive and time-consuming research of original specimens in the nature museums of Paris, Berlin, Frankfurt and London eventually led to the finding that all six ancient names actually referred to one and the same species -- Dichrorampha alpestrana, which has been known since 1843 and had to be adopted as the valid older name for Dichrorampha montanana as having been described a couple of months earlier. Similarly, all other available names proved to belong to Dichrorampha alpestrana. The species discovered by Schmid and Huemer, however, was different, not yet named, and could finally be described as new to science. The authors chose to name it Dichrorampha velata -- the Latin species name means "veiled" or "hidden," pointing to the complicated story behind its discovery.

Lots of unanswered questions

The Hidden Alpine Moth is a striking species with a wingspan of up to 16 mm and a characteristic olive-brown color of the forewings with silvery lines. It belongs to a group of mainly diurnal moths and is particularly common locally in colorful mountain flower meadows. For now, we know that its distribution extends at least from Salzburg and Tyrol through southern Switzerland and the Jura to the French and Italian Alps, with isolated finds known from the Black Forest in Germany, but the researchers believe it might have a wider range in Central Europe.

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Unsustainable Arctic shipping risks accelerating damage to the Arctic environment

The economic and environmental pros and cons of melting Arctic ice creating shorter shipping routes through the polar region are weighed up in ground-breaking research from UCL experts in energy and transport.

They conclude that policy makers must properly assess the environmental trade-offs and costs in addition to the commercial benefits and opportunities in Arctic shipping. The authors also want to see more incentives to drive technological developments that will accelerate the uptake of green fuels and technologies.

The Arctic is the fastest-warming region on the planet.

Shorter Arctic shipping routes, which mean less fuel used are already used by a handful of ships, when areas of the Arctic ice melt during the summer. But the period when these routes are navigable is predicted to extend with increases in global warming and, if warming fails to remain within the 1.5?C/2?C limit set out in the Paris agreement, permanent Arctic ice may be a thing of the past.

The research, published in Transportation Research Part A: Policy and Practice, looked at the financial competitiveness of Arctic shipping, considering the impact of emissions from these vessels on the environment.

They looked at two policy scenarios, one being business-as-usual, where there is no policy on emissions, and the other operating under an Arctic specific zero-emissions policy, where ships which could run using energy from renewable sources were considered.

When environmental costs are ignored, fossil fuel based residual fuel oil is cheaper than alternative fuels. However, when the environmental impacts of accelerating climate change and the adverse effects of ship emissions on human health are considered, residual fuel ships are no longer feasible because of their contribution to greenhouse gas and air pollutant emissions.

The experts conclude that, in the second scenario, green ammonia fuel cell ships are the most commercially viable and that policies which facilitate the introduction of such zero carbon fuels and zero emission technologies should be encouraged. Green ammonia is an example of a fuel that can be emissions free in both its production and use, given a green electric infrastructure.

Lead author Joseph Lambert (UCL Energy Institute) said: "Significant change is under way in the Arctic region due to global warming and from a shipping perspective we should prepare for what this means through assessing all the opportunities, risks and trade-offs that aren't exclusively financial. These routes may become more financially competitive as global warming increases and Arctic ice retreats, but more factors must be considered. It is critical that the Arctic ice maintains its permanency -- in order to stay within global warming targets and to protect the region's ecology."

Co-author Dr Tristan Smith (UCL Energy Institute), who supervised the research, said: "This is a novel work that shows the economic costs alongside the environmental costs for the Arctic route, as well as showing how certain technology choices, that could be incentivised through policy, could significantly reduce the environmental costs that would otherwise arise from Arctic shipping. The paper shows a clear justification for governments to intervene now to prevent a melting Arctic's enabling of a reduction in shipping costs because of further acceleration of the degradation of this crucial ecosystem."

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Firefighters found to have persistent lung damage from Fort McMurray wildfire

Firefighters at the centre of the battle against the massive Fort McMurray wildfire in 2016 have persistent lung damage, according to new findings published by a University of Alberta occupational health research team.

"Those who were dealing with burning organic matter were exposed to a barrage of small particles in the smoke, and the ones with the highest exposure have long-term consequences," said principal investigator Nicola Cherry, an occupational epidemiologist, professor of medicine and Tripartite Chair of Occupational Health in the Faculty of Medicine & Dentistry.

The firefighters had more than double the risk of developing asthma compared with the general population. They also exhibited a number of changes in lung function tests supportive of an effect on the lungs, including greater lung hyperreactivity and increased thickening of the bronchial wall.

"The impact was correlated to exposure -- those who had more exposure had more effects," said Cherry.

For three years after the fire, Cherry's team followed 1,234 Alberta firefighters.The firefighters' exposure to fire-related particles was estimated based on the hours they worked on the blaze, the dates they were there, the firefighting tasks they were performing, and Alberta Environment estimates of particulate matter at different locations.

The Fort McMurray fire broke out in May 2016 and was under control by the fall, but it was not officially declared out until the following year. The highest exposure to particulate matter happened during the first week, Cherry said. Firefighters were deployed from across Alberta from crews that specialize in structural fires (i.e., buildings), oil and gas industry fires and wildland fires.

Many did not have sufficient supplies of specialized lung protection equipment or were not able to wear it while fighting the Fort McMurray fire, Cherry said.

"It was an extraordinarily violent fire," she said. "It's very difficult to rush uphill pulling equipment behind you if you have a heavy mask on that doesn't let you breathe."

Cherry modelled her study, which was funded by the Canadian Institutes for Health Research and the Government of Alberta, on studies that examined the respiratory health of first responders following the World Trade Center collapse in New York City in September 2001.

"It's not easy to do this kind of study during a catastrophe," said Cherry, who had serendipitously taken delivery of a mobile lung assessment lab the week before the Fort McMurray fire broke out.

"At the World Trade Center, the exposure was mainly to inorganic dust, whereas in Fort McMurray it was burning vegetation, as well as buildings," Cherry said. "It's interesting that we saw similar results from very different exposure."

Cherry's research team looked at three main sources of evidence about the lung health of the firefighters before and after the fire. First, they asked for permission to link to their administrative health record, which showed doctor's visits and diagnoses. The records for each firefighter were matched with five patients from the general population of similar age, sex, geographic location and health status as a control group for comparison.

The team also measured the firefighters' lung function, which shows how much air goes in and out of the lungs. Finally, some of the firefighters with no history of chronic respiratory disease or smoking were randomly selected for clinical followup, including CT scans of their lungs and methacholine challenge testing, used to check for asthma.

This is one of several papers Cherry has published on the mental and physical health of the Fort McMurray firefighters.

"They take enormous risks," she said. "This study shows clearly that it is possible for exposures to cause changes in the lung that don't get better over time."

Cherry said she will continue to study the occupational health of firefighters -- including crews currently fighting wildfires in the interior of British Columbia and Alberta -- in hopes of recommending ways to make the work safer. She is studying whether wearing a mask or washing skin more often could reduce exposure to chemicals from smoke. Putting more crews through shorter rotations at fire scenes might also help to lessen health impacts, she said.

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A common ancestor for cells involved in hearing and touch

The sensory cells in the inner ear and the touch receptors in the skin actually have a lot in common, according to a new study from the USC Stem Cell laboratory of Neil Segil published in the Proceedings of the National Academy of Sciences (PNAS).

"There are striking similarities in the development of two types of specialized sensory cells: the so-called 'hair cells' that receive sound vibrations in the inner ear, and the Merkel cells that sense light touch at the surface of the skin," said Segil, who is a Professor in the Department of Stem Cell Biology and Regenerative Medicine, and the USC Tina and Rick Caruso Department of Otolaryngology -- Head and Neck Surgery. "Ultimately, these developmental similarities are a legacy of shared evolutionary history. This demonstrates how the story of evolutionary developmental biology, or 'evo devo,' also extends to what we call the 'epigenetic level' -- or how genes are regulated."

In the study, PhD student Haoze (Vincent) Yu, postdoctoral scholar Litao Tao, and their colleagues identified a shared mechanism involved in gene regulation or epigenetics, that enables stem cells and progenitor cells to differentiate into more specialized hair cells and Merkel cells.

In order to begin the process of differentiation, the right parts of a stem cell's DNA need to be taken out of storage. Each human cell can store around six feet of DNA in its nucleus, because this DNA is wound around tiny "spools" made up of proteins called histones. These spools of DNA and histone protein are further packed together to form what are known are nucleosomes, which are stacked to create chromatin, which is the material that makes up the chromosomes.

When DNA is wound tightly into this storage configuration, the chromatin is closed and inaccessible to the protein ATOH1. This protein is a "master regulator" that can activate a network of differentiation genes in the DNA within the chromatin -- but not without first gaining access.

To this end, ATOH1 stimulates the production of a second protein known as POU4F3, an aptly named "pioneer factor" with the ability to venture into new frontiers by binding to closed and inaccessible chromatin. After POU4F3 blazes a trail by binding to the closed chromatin, ATOH1 is able to move forward with engaging and activating the network of genes that drives differentiation into hair cells and Merkel cells.

Strikingly, there is significant overlap in the specific regions of chromatin that POU4F3 makes accessible to ATOH1 in hair cells and Merkel cells.

"It's remarkable that these two cell types, which are both involved in sensing mechanical stimuli but derive from distinct parts of the embryo, both rely on the same ATOH1/POU4F3 mechanism in order to differentiate," said Segil. "Our study suggests that this mechanism is extremely ancient, and emerged before hair cells and Merkel cells diverged from a common evolutionary ancestor -- an 'ur-mechanoreceptor' cell type."

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T-cell 'training grounds' behind robust immune system response seen in adenovirus vaccines

Adenovirus vaccine vectors, such as the ChAdOx1 nCov-19 construct which has risen to prominence as a major vaccine for COVID-19, may generate robust long-term immune system responses, according to scientists from the Universities of Oxford and the Cantonal Hospital St.Gallen, Switzerland.

Writing in the journal Nature Immunology, they detail an investigation into one of the key features of adenovirus vaccines -- their ability to generate strong and sustained populations of the 'killer' T-cell element of the immune system.

In an animal model, they observed that adenoviruses are able to get into long-lived tissue cells, known as fibroblastic reticular cells, which in turned formed small, well organised clusters, acting as 'training grounds' for these T-cells, appearing to explain how these vaccines sustain robust immune system responses.

Paul Klenerman, Sidney Truelove Professor of Gastroenterology at the University of Oxford's Nuffield Department of Medicine, and one of the lead authors of the paper, said:

"Millions of people will have received adenovirus vaccines around the world, not only the Oxford-AstraZeneca vaccine, but the J&J vaccine, and also the Chinese and Russian versions. The ultimate goal with these vaccines is the induction of long-term immune system protection using both antibodies and T-cells. This research helps us to understand more on the process of vaccination, and why the effects on killer T-cells are so prolonged."

The researchers show that adenovirus vectors can target specific cells -- known as stromal cells in tissues such as the lung -- generating antigen 'depots' in these long-lived cells. These stromal cells were originally thought just to provide an inert scaffold for the tissues, but it appears that they are very dynamic cells with a major role in immune control. The long lived nature of the cells means that the antigen can be 'shown' to the immune system many times, effectively boosting the response, a critical element of generation of protective T-cells.

They were also able to investigate other mechanisms which may explain the particular efficacy of adenovirus vectors, including the key chemical messenger involved in signalling to T cells. This is a factor called IL-33 -- a so-called "alarmin" released when the stromal cells receive signals of distress. IL-33 acts to strongly boost to the metabolism of the T cells, resulting in effectively more energetic cells and a highly protective immune response.

Burkhard Ludewig, Professor at the University of Zurich, and Head of the Medical Research Center, Cantonal Hospital St. Gallen, Switzerland, also a lead author of the paper, said:

"Adenoviruses have co-evolved with humans over a very long time, and learned a lot about the human immune system in the process. Viruses are always the best teachers, and here they have taught us an important lesson about how best to boost killer T cell responses. The T cells that come from these cellular training camps appear to have a very high level of "fitness." Hopefully we can put this to good use in designing new vaccines -- vaccines that we still desperately need for diseases such as TB, HIV, hepatitis C and cancers."

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