Culture

The extreme summer drought of 2018 was a special situation for both nature and scientists. It was very hard on the forest. At the same time, it offered researchers from the Universities of Basel (Switzerland) and Würzburg (Germany) the opportunity to study the reaction of trees to this climatic phenomenon.

Research in the treetops

"The summer of 2018 was hotter and drier than in any other year since weather records began," says ecophysiologist Professor Bernhard Schuldt from the University of Wuerzburg. Together with Dr Matthias Arend and Professor Ansgar Kahmen from the University of Basel, he was significantly involved in the study, which is published in the scientific journal PNAS. "A unique opportunity arose for us to study the influence of extreme heat and drought on large and old trees."

Using a crane set up in the forest, the researchers examined ten randomly selected spruce trees near Basel. They were all over 100 years old and around 30 metres high. The seasonal fluctuations of the water balance were measured directly in the uppermost tree crown.

Low but continuous water loss

The researchers are particularly interested in the duration and intensity of the drought that causes the water-conducting system in the wood to collapse. Due to its shallow root system, spruce in particular is susceptible to drought stress.

"We were able to show that the trees eventually die because their water-conducting system collapses within a very short time after a long drought," says Professor Schuldt. This, he says, is due to the small but continuous loss of water that takes place via the surfaces of the needles despite the fact that the leaf pores are closed.

The realisation that trees in general, and spruce in particular, suffer from drought is not news. For research, however, it is important to understand the processes underlying tree death in detail. This is exactly what the scientists from Basel and Wuerzburg have achieved with the study. "Our results provide an important contribution to improve predictions of drought-induced tree mortality," explains Schuldt.

Death comes very suddenly

The new results prove how dangerous heat waves are for trees due to the high dryness of the atmosphere and the associated high evaporation. According to the findings, the trees' hydraulic system can collapse completely within a very short time during the drought. Until now, it was assumed that this happens gradually as soon as the water supply from the soil is interrupted and the internal water reservoir are empty.

The decisive factor here is that the dehydration of the plant tissue does not seem to be a continuous process, but rather takes place abruptly after a species-specific threshold value has been exceeded. The spruce trees were unable to recover from this. "Whether this applies to other tree species such as beech, which was also severely affected by the drought, still needs to be clarified," says Schuldt.

A new paper in the Review of Economic Studies indicates that disease can alter the social networks and economic growth of countries for generations, even after the disease itself is eradicated.

Social networks are an important determinant of a country's growth as they affect the diffusion of ideas and the rate of technological progress. But social networks also diffuse diseases that can rapidly spread and dampen growth.

As ideas and germs diffuse through the same human interactions, the network structure of a country ultimately depends on its epidemiological environment. In countries with low prevalence of infectious diseases, high diffusion networks are more likely to emerge as they are better suited to diffuse technology and foster growth. On the other hand, in countries characterized by high prevalence of infectious diseases, low diffusion networks are more likely to emerge as limited connectivity protects people from epidemics. This insight has become particularly pertinent as economists reflect on the long term economic impact of the COVID-19 pandemic.

Using a newly assembled dataset for 71 countries and a theoretical model where germs, networks and technology evolve endogenously, the researchers show that small initial differences in a nation's epidemiological environment can trigger large and persistent differences in network structure that, over time, give rise to substantially different levels of technological diffusion and economic output. Speci?cally, a one-standard-deviation change in social network structure can increase the growth of output per worker by up to 2% per year.

The researchers then conduct policy experiments in which they hold constant the level of disease in the economy and exogenously change several features of the network structure that determine the speed of diffusion. What is the effect of introducing higher diffusion network on growth? Interestingly, the answer depends on the initial prevalence of disease.

Their benchmark is the United States, which has very low disease prevalence (0.05 percent for communicable diseases). In this environment, they find high-diffusion networks have a strongly positive impact on economic growth. Doubling the number of highly mobile or connected individuals raises growth rates substantially. But in a high-disease environment (using Ghana's 18 percent prevalence), altering the social network to facilitate faster diffusion lowers national income. Doubling the number of highly connected people causes output to fall by 90 percent.

The paper shows that how networks a?ect economic growth depends on the disease environment. In low disease countries, high diffusion networks promote the dissemination of new ideas and enhance growth. However, in a place where disease is prevalent networks can also lead to epidemics and humanitarian crisis.

"Germs, networks and growth are deeply interconnected," said the paper's lead author, Alessandra Fogli. "Strong networks have allowed our global economy to grow at an unprecedented rate. But they have also made it more vulnerable to the diffusion of new diseases. As social networks adapt to the new epidemiological environment, the COVID-19 pandemic can have long term consequences on economic growth."

An estimated 334,000 COVID-19 cases are attributable to meatpacking plants, resulting in $11.2 billion in economic damage, according to a new study led by a researcher at the University of California, Davis. The study was published in the journal Food Policy.

It found that beef- and pork-processing plants more than doubled per capita infection rates in counties that had them. Chicken-processing plants increased transmission rates by 20 percent. The study looked specifically at large meatpacking plants generating more than 10 million pounds per month.

Conservative estimate

Researchers said both the economic impact and infection rate estimate is conservative. The study looked at infection rates within a county and did not account for cases that might have been contracted at a meatpacking plant but spread to other counties.

"Similarly, our study likely understates true economic losses," said lead author Tina Saitone, a livestock and rangeland economics cooperative extension specialist in the Department of Agricultural and Resource Economics at UC Davis.

The study looked at lost wages and mortality and did not include long-term health care costs, or costs for measures put in place to protect worker safety.

"While we did see an initial ramp up in cases attributable to meatpacking facilities, over time infection rates were the same per capita as counties without them, partly because meatpacking plants implemented a lot of protocols to protect employees," said Saitone.

Driving factors

A variety of factors can drive county-level COVID-19 transmission rates. Saitone said the research controlled for those potential drivers, such as the number of nursing homes or correctional facilities in a county. It also considered stay-at-home orders and other regulations, population density, demographics, economic factors and health characteristics. The study looked at infections within 150 days after the first documented COVID-19 case in each county.

Essential industry

Increased COVID-19 transmission rates have prompted some critics to call for a smaller, more geographically dispersed industry to make it less susceptible to a pandemic and massive disruptions in the food supply chain. Researchers caution that such a move would come at a price, adding costs to a system designed to eliminate them and ultimately increasing food prices. Economists instead suggest research and investigation into the automation and technological innovations that made the poultry segment of the industry more resilient to the COVID-19 pandemic.

Study co-authors include K. Aleks Schaefer with Michigan State University and Daniel Scheitrum with the University of Arizona.

Philadelphia, April 15, 2021 - A new study shows that markers of fear recall differ between men and women, but in a hormone-dependent manner.

Aberrant fear-memory processing in the brain is thought to underlie anxiety disorders, which affect hundreds of millions of people worldwide. The neurobiological mechanisms underlying these disorders remain poorly understood, but recent studies suggest that neural oscillations in the prefrontal cortex can reflect the strength of fear recall activity, providing a physiological measure.

Women suffer from anxiety disorders at twice the rate of men and indeed the literature shows that there are sex differences in fear recall behaviors, but this area of study has not been extended to neural oscillations. Additional studies suggest a modulatory role for the female sex hormone estradiol (E2) for fear recall and extinction recall.

The new study led by Ursula Stockhorst, PhD, at the University of Osnabrück, Germany, specifically shows that peripheral and brain markers of fear recall differ in a hormone-dependent manner between men and women.

The work appears in Biological Psychiatry: Cognitive Neuroscience and Neuroimaging, published by Elsevier.

Cameron Carter, MD, Editor of Biological Psychiatry: Cognitive Neuroscience and Neuroimaging, said of the work: "This study sheds light on the well-known differences between men and women in their vulnerability to anxiety disorders and shows that aspects of fear learning and extinction that contribute to vulnerability in women are related to differences in estrogen levels."

For the study, first author and PhD student Philipp Bierwirth, MSc, and colleagues examined 20 men, 20 women using oral hormonal contraceptives (OC) and 20 free-cycling women during their mid-cycle (MC). Women taking OC have suppressed and thus low endogenous E2 levels, whereas free-cycling MC women have higher levels of E2.

Participants underwent a fear-conditioning paradigm in which two of four photographs of neutral male faces were paired with a loud burst of white noise. Following the conditioning, the subjects underwent fear extinction, in which two photographs - only one of which had been paired with the noise - were again presented, but this time with no noise stimulus. The next day, subjects were shown all four photographs again, including the two that had been presented in the extinction phase and thus ready for extinction recall, and two of them without previous extinction - thus subject to fear recall. During all presentations, the researchers measured skin conductance responses (SCR), a peripheral readout of fear expression, and brain oscillations measured by electroencephalography.

Mr. Bierwirth said: "We found stronger peripheral fear expression (via SCR) during fear recall and extinction recall under low-E2 conditions, that is, in men and in OC women, compared to mid-cycle women with higher E2 levels. Most importantly, we also observed enhanced theta oscillations in the medial prefrontal cortex and especially in the dorsal anterior cingulate cortex (dACC), in men and OC women compared to MC women."

Importantly, the authors also point out that subjects were examined during their natural E2 status. They were not randomized to experimentally manipulated estrogen levels and so causal inferences about estrogen cannot be drawn.

Fear recall-related dACC theta oscillations were attenuated in women with higher E2 levels, which, importantly, supports previous findings suggesting a protective role for E2 against fear overexpression during the recall of fear and extinction memories. The data demonstrate that peripheral and brain oscillatory correlates of fear memory recall do not differ between the sexes per se but vary with E2 status, even among women.

PITTSBURGH, April 15, 2021 - Oncologists faced with treating older women with breast cancer often must decide if the treatment may be more detrimental than the cancer. A study published today in JAMA Network Open by researchers at UPMC Hillman Cancer Center and the University of Pittsburgh School of Medicine sheds new light on this choice and suggests the rate of cancer recurrence or survival may be no different in treated vs. untreated elderly patients diagnosed in the early stages of the cancer diagnosed most commonly in women.

"As a breast surgeon, I want to give my patients the best chance of survival with the best quality of life," said senior author Priscilla McAuliffe, M.D., Ph.D., surgical oncologist at UPMC Hillman Cancer Center and attending surgeon in the Department of Surgery at Pitt. "However, we have found that overtreatment of early-stage breast cancer in older patients may actually cause harm while not improving recurrence or survival rates."

Despite guidelines recommending the de-escalation of treatment among older women with early-stage cancer, there has been no definitive study of this patient cohort, who often are excluded in clinical trials because of their age.

To determine whether patients were being overtreated, the researchers analyzed deidentified data from more than 3,000 women over the age of 70 who were diagnosed with ER-positive, HER2-negative breast cancer from 2010 to 2018. Age 70 was used because clinical trials in breast cancer don't often include women in this age category. The data, collected at 15 UPMC Hillman Cancer Center community and academic sites, were evaluated with the UPMC Network Cancer Registry, which tracks cancer patients using UPMC's electronic health record system.

The study looked at two procedures: sentinel lymph node biopsy (SLNB), which is a surgical procedure to remove the lymph nodes from the underarm to determine if the cancer has spread beyond the breast, and radiotherapy (RT), which is standard treatment after breast-conserving surgery, given in multiple doses to control or kill any residual tumor. Side effects including nerve pain, lymphedema and skin irritation can sometimes occur after these procedures, which may be more difficult for the older patient to overcome.

The researchers found that the number of SLNB and RT procedures among patients over age 70 remained high at 65.3% and 54.4% respectively. The rates of SLNB also steadily increased by 1% per year, while rates of RT declined by 3.4% per year over the study period.

Most importantly, they found that the rates of disease recurrence or survival remained the same, whether the carefully selected patients received SLNB or RT, or not--no matter their comorbidities or tumor grade.

"This study is an example of how we can use big data to deliver on the promise of precision medicine--getting the right treatment to the right patient at the right time," said Adrian Lee, Ph.D., investigator at the Women's Cancer Research Center at UPMC Hillman Cancer Center and Magee Womens Research Institute, and director of the UPMC/Pitt Institute of Precision Medicine. "Sometimes--as it happens to be in this case--that could mean deciding not to provide a certain treatment to ensure better care for the patient."

The American Society of Breast Surgeons has released its second list of specific tests or procedures that clinicians and patients should question as part of Choosing Wisely®, an initiative of the ABIM Foundation. Lee hopes this study will further validate that a de-escalation of treatment for certain breast cancers will not affect the quality of life or outcome for patients and that SLNB and RT can safely be omitted.

"Our study is unique in that we were able to look at very granular patient data, thanks to the size of our health system and the availability of electronic medical records, which makes the findings more robust than any other such study to date," said Neil Carleton, lead author and an M.D./Ph.D. student at the Pitt. "This is the result of an incredible collaborative of researchers, oncologists and clinical analytics experts."

This video features the investigators discussing their study.

Hafnium-based thin films, with a thickness of only a few nanometres, show an unconventional form of ferroelectricity. This allows the construction of nanometre-sized memories or logic devices. However, it was not clear how ferroelectricity could occur at this scale. A study that was led by scientists from the University of Groningen showed how atoms move in a hafnium-based capacitor: migrating oxygen atoms (or vacancies) are responsible for the observed switching and storage of charge. The results, which were published online by the journal Science on 15 April, point the way to new ferroelectric materials.

Ferroelectric materials exhibit spontaneous polarization, which can be reversed or switched using an electric field. It is used in non-volatile memories or the construction of logic devices. One drawback of these materials is that when the size of the crystals is reduced to below a certain limit, the ferroelectric properties are lost. However, some years ago, it was suggested that hafnium-based oxides could exhibit ferroelectricity at nanoscale dimensions.

Microscope

In 2018, a team led by Beatriz Noheda, Professor of Functional Nanomaterials at the University of Groningen, confirmed these special properties of hafnium oxides. 'However, we didn't know exactly how this ferroelectricity occurred,' she says. 'We knew that the mechanism in these hafnium-based thin membranes is different. As ferroelectric switching is something that occurs at an atomic scale, we decided to study how the atomic structure of this material responds to an electric field, both using the powerful x-ray source at the MAX-IV synchrotron in Lund and our formidable electron microscope in Groningen.'

The University houses a state-of-the-art electron microscope at the electron microscopy centre of the Zernike Institute for Advanced Materials, with which the group of Bart Kooi, co-author of the Science paper, successfully imaged the lightest atoms in the periodic table - hydrogen - for the first time in 2020. This is where first author Pavan Nukala comes in. He worked as a Marie Curie Research Fellow at the University of Groningen and had a background in electron microscopy and materials science, especially in these ferroelectric hafnium systems.

Oxygen

However, if the preparation of a sample for the imaging of atoms is tricky, then the need to apply an electric field across a device in situ increases the difficulty by several orders of magnitude. Luckily, at around the same time, Majid Ahmadi (a master of in situ experiments) joined Kooi's group. 'All of us were quite convinced that if there was one place where switching of hafnium could be visualized in situ at an atomic scale, it would be here at the ZIAM electron microscopy centre. It benefits from a unique combination of the right expertise in materials science, microscopy and infrastructure,' Noheda explains.

The proper protocols for building hafnium-based electron-transparent capacitors using focused ion beam facility were developed by Ahmadi and Nukala. 'We imaged the atomic lattice of hafnium-zirconium oxide between two electrodes, including the light oxygen atoms,' Nukala explains. 'People believed that oxygen atom displacement in hafnium gives rise to polarization. So, any microscopy would only make sense if oxygen could be imaged and we had the exact tool for that. Then we applied an external voltage to the capacitor and watched the atomic changes in real time.' Such an in situ experiment with direct imaging of oxygen atoms inside the electron microscope had never been done.

Migration

'A significant feature that we observed is that the oxygen atoms move,' explains Nukala. 'They are charged and migrate following the electric field between the electrodes through the hafnium layer. Such a reversible charge transport enables ferroelectricity.' Noheda adds: 'This was a big surprise.' There is indeed also a small shift in atomic positions at the picometre scale inside the unit cells but the overall effect of the oxygen migration from one side to the other side on the device response is much larger. This discovery paves the way for new materials that could be used for nanometre-sized storage and logic devices. 'Hafnium-based ferroelectric memories are already in production, even though the mechanism behind their behaviour was unknown,' says Nukala. 'We have now opened up the road towards a new generation of oxygen-conducting, silicon-compatible ferroelectric materials.'

Noheda, who is the director of CogniGron, the Groningen Cognitive Systems and Materials Center, which develops new materials for cognitive computing, can see interesting applications for the new type of ferroelectric materials. 'Oxygen migration is much slower than dipole switching. In memory systems that could emulate the short-term and the long-term memory of brain cells, material scientists currently try to make hybrid systems from different materials to combine these two mechanisms. 'We can now do it in the same material. And by controlling oxygen movement, we could create intermediate states, again, like you find in neurons.'

Defects

Nukala, who is now an Assistant Professor at the Indian Institute of Science, is also interested in exploring the piezoelectric or electromechanical properties of the material. 'All conventional ferroelectrics are also piezoelectric. What about these new non-toxic, silicon-friendly ferroelectrics? There is an opportunity here to explore their potential in microelectromechanical systems.'

In the end, the properties of this new material stem from imperfections. 'The oxygen can only travel because there are oxygen vacancies inside the crystal structure,' says Nukala. 'In fact, you could also describe what happens as a migration of these vacancies. These structural defects are the key to the ferroelectric behaviour and, in general, give materials novel properties.'

Fifty-five years ago, America's death toll from automobile crashes was sky-high. Nearly 50,000 people died every year from motor vehicle crashes, at a time when the nation's population was much smaller than today.

But with help from data generated by legions of researchers, the country's policymakers and industry made changes that brought the number killed and injured down dramatically.

Research led to changes in everything from road construction and driver's license rules, to hospital trauma care, to laws and social norms about wearing seatbelts and driving while drunk or using a cell phone.

Now, researchers at the University of Michigan and beyond hope the country can do the same thing for the nearly 40,000 deaths and tens of thousands of injuries that now result from firearms each year, including homicides, suicides and unintentional incidents.

Two new papers on ways to reduce firearm use by people who are a danger to themselves and others are among their recent contributions.

Back in the headlines

A spate of recent mass shooting incidents, and an announcement from the White House about new actions at the federal level, have brought the issue back into the spotlight amid the COVID-19 pandemic.

But the research effort is starting almost from scratch, because of a 25-year near-total hiatus on federal research funding for firearm-related studies due to political reasons.

A 2019 U-M Injury Prevention Center study found that on a per-death basis, funding for pediatric firearm research is 30 times lower than it would have to be to keep pace with research on other child health threats.

That's despite the fact that since 2017, more Americans have died each year from firearm injuries than from the effects of motor vehicle crashes. Another U-M study showed that the rate of firearm death has risen sharply since 2015.

Using some of the scarce federal research funding available in recent years, U-M injury prevention researchers have worked to produce evidence to inform policies that strike a balance between preventing harm and respecting Second Amendment rights.

"Firearm violence leads to more than 100 deaths per day across the country, and so in order for us to address this public health crisis, we need researchers to work together, generating new knowledge and advancing innovative solutions," says Rebecca Cunningham, M.D., U-M vice president for research and the William G. Barsan Collegiate Professor of Emergency Medicine at the U-M Medical School. "We are starting to see some momentum in terms of increased funding to support this important work, which hopefully will strengthen the pipeline of researchers who can devote their careers to studying firearm injury prevention and provide data and solutions toward decreasing injury and death."

Initial research efforts

U-M launched a Firearm Injury Prevention Research initiative in 2019 to build on that momentum, and overcome the lack of firearm-related research funding available from federal sources that fund most other biomedical and social research.

Michigan experts have joined with academics and health professionals across the country to share research data, and evaluate interventions based on past research through the Firearm Safety Among Children and Teens consortium, funded by the National Institutes of Health.

The FACTS consortium has done deep-dives into the state of research on firearm death and injury in children and adolescents, and laid out priorities for future research efforts.

Its members have already launched several studies, including one whose results were published this week.

It finds that Oregon's "red flag" law is indeed being used to remove firearms from people who are determined by a judge to be at extreme risk of committing violence against themselves or others, but that it's not often used for its other intended purpose, to prevent gun purchases by such individuals. The White House announcement called for more use of "red flag" laws, also called extreme risk protection orders (ERPOs) or gun violence restraining orders.

Cunningham and U-M President Mark Schlissel, M.D., Ph.D., recently hosted a virtual panel discussion of U-M faculty who are doing a wide range of research on firearm injury prevention.

Patrick Carter, M.D., director of the U-M Injury Prevention Center, and like Cunningham, an emergency medicine physician at Michigan Medicine, welcomes the news from the federal government.

"An exciting aspect of President Biden's announcement is the renewed focus on advancing the science of firearm injury prevention through federal research funding," he says. "Such research is crucial to developing a better understanding of the factors underlying this critical public health problem, as well as advancing evidence-based solutions that will reduce the number of Americans that die or are injured by firearms every year."

In addition to producing new research results, it's also important to turn research findings into useful tools for families and community leaders. That includes fact-based information about firearm safety for parents.

It also includes the entire kit to help primary care providers use the SaferTeens approach developed and tested by U-M. It screens young people for risk of violence and conducts a brief intervention to help them focus on reducing that risk.

A focus on firearm suicide risk

In addition to the recent spate of mass shootings, and a sharp uptick in gun sales, the pandemic's impact on the mental health and the economic state of many Americans also makes this a crucial time to study ways to reduce firearm-related death and injury due to suicidal actions.

In 2018, 52% of all suicides in Michigan involved a firearm, according to data in the newly released report from the Michigan Suicide Prevention Commission. Nearly all suicide attempts involving firearms result in a death, past research has shown.

John Greden, M.D., professor emeritus of psychiatry and neurosciences at U-M, serves on the commission. He is the founding director and immediate past director of the Frances and Kenneth Eisenberg and Family Depression Center, as well as past chair of the U-M Department of Psychiatry.

In its list of recommendations, the commission calls for more efforts to reduce suicide by firearm, including more awareness and training involving everyone from shooting sports clubs and gun shops to veterans' groups. It also calls for health care providers to routinely assess their patients' access to firearms and other lethal means, if the patient is at risk for suicide. The new report includes a list of research projects now under way at U-M specifically focused on suicide risk identification and reduction.

One group of patients with such a high risk includes those with depression, and those with bipolar disorder, a mental illness that involves sharp swings between manic periods and depressed periods.

That's what prompted U-M psychiatrist Melvin McInnis, M.D., and U-M Law School professor Carl Schneider, J.D., to write a recent paper that sets out a legal framework for people with depression and bipolar disorder to place themselves on an official list that would keep them from purchasing firearms.

"Bipolar and depressive disorders very often include suicidal thinking that may lead to suicide," says McInnis, who directs the Heinz C. Prechter Bipolar Research Program at the Eisenberg Family Depression Center. "When well individuals with these disorders live productive lives and have no wish to harm themselves or anyone. A powerful gun-violence prevention tool is a volunteer self-exclusion option for anyone for any reason to register with the Department of Justice and be placed on a list that would prevent them from purchasing guns or firearms."

The U-M Injury Prevention Center also recently held a Suicide Prevention Summit to share the latest results from suicide-related research, including research on firearm-based suicide. Recordings of the presentations are available online.

Among the topics discussed was an effort to reduce suicide by firearm among young people living in rural communities, who have an especially high risk. Working with community groups, U-M Department of Psychiatry and IPC researcher Cynthia Ewell-Foster, Ph.D., and colleagues are trying to encourage evidence-based safe firearm storage among families with children in rural northern Michigan.

Race as a risk factor

The other major issue brought to great public attention in the past year - the effects of systemic, long-term race-based discrimination on the health of people of color - also has importance for the firearm issue and research.

Firearms are the number-one cause of death for young black men, and firearm injury rates are more than three and a half times higher for Black children and teens than for whites.

Cunningham, Carter and their colleagues have studied the role of firearms in the lives of teens and young adults in Flint, Michigan for nearly a decade, through interactions begun in the emergency department. The SaferTeens program grew out of that work.

Now, they're testing an approach based on a mobile app that enables remote counseling for youth at risk of firearm violence through an effort called Project IntERact.

These projects, and more getting started around the country as research funding grows, are an important start. The increased availability of funding is also likely to draw more junior researchers and injury prevention students to the field of firearm injury, because the promise of a stable source of research funding is crucial to the choice of subject a researcher chooses for their career. That's also what happened 50 years ago with motor vehicle crash research.

"This is a complex problem, but it's not a more complex problem," than motor vehicle-related injuries and deaths, says Cunningham. "There is an awakening that we can really do more."

Scientists at the University of Southampton have conducted a study that highlights the importance of studying a full range of organisms when measuring the impact of environmental change - from tiny bacteria, to mighty whales.

Researchers at the University's School of Ocean and Earth Science, working with colleagues at the universities of Bangor, Sydney and Johannesburg and the UK's National Oceanography Centre, undertook a survey of marine animals, protists (single cellular organisms) and bacteria along the coastline of South Africa.

Lead researcher and postgraduate student at the University of Southampton, Luke Holman explains: "Typically, biodiversity and biogeography studies focus on one group of species at a time, often animals. Studying animals, protist and bacteria together - organisms vastly different in size, separated by billions of years of evolution - gave us the opportunity to take a broader view of the marine ecosystem. We discovered remarkably consistent biogeographic groupings for the three across the coastline - consistent with previously studied patterns, driven by regional currents."

Findings are published in the journal Nature Ecology and Evolution.

The team took seawater samples in numerous locations along the length of the South African coast, from the warmer seas of the east, to the cooler waters of the west and the intermediate temperatures in the south. The samples were filtered, had environmental DNA extracted and underwent sophisticated lab analysis to indicate the diverse range of organisms found in particular locations.

Results showed a broad range of animals living in the sea along the whole length of coast, but with differences in the exact species in warm, cold and intermediate regions. This same pattern of difference was also shown in bacteria and protists - demonstrating consistency in the biodiversity of life for each region.

Furthermore, the scientists found that among the variables examined temperature had the greatest impact on determining the diversity of animals and bacteria, whereas protists were associated more with chlorophyll concentration in the water. The team also revealed that while all three groups were affected to some extent by human activity, such as shipping, fishing and building of marinas, this wasn't to the extent they'd expected.

Commenting on the study, Luke said: "We hope our work encourages researchers to consider other groups of organisms, both in biogeographic assessments and marine protection and restoration projects. For example, a project aiming to restore a coral reef might also need to consider the bacterial communities, or the protection of a river system might also ensure the protists communities are monitored in addition to the fish."

Moving forwards the team hope to learn more about the causes and consequences of global marine biodiversity change for all life, from microscopic bacteria and protists to macroscopic organisms like fish and marine mammals.

The dynamics of the neural activity of a mouse brain behave in a peculiar, unexpected way that can be theoretically modeled without any fine tuning, suggests a new paper by physicists at Emory University. Physical Review Letters published the research, which adds to the evidence that theoretical physics frameworks may aid in the understanding of large-scale brain activity.

"Our theoretical model agrees with previous experimental work on the brains of mice to a few percent accuracy -- a degree which is highly unusual for living systems," says Ilya Nemenman, Emory professor of physics and biology and senior author of the paper.

The first author is Mia Morrell, who did the research for her honors thesis as an Emory senior majoring in physics. She graduated from Emory last year and is now in a post-baccalaureate physics program at Los Alamos National Laboratory in New Mexico.

"One of the wonderful things about our model is that it's simple," says Morrell, who will start a Ph.D. program in physics at New York University in the fall. "A brain is really complex. So to distill neural activity to a simple model and find that the model can make predictions that so closely match experimental data is exciting."

The new model may have applications for studying and predicting a range of dynamical systems that have many components and have varying inputs over time, from the neural activity of a brain to the trading activity of a stock market.

Co-author of the paper is Audrey Sederberg, a former post-doctoral fellow in Nemenman's group, who is now on the faculty at the University of Minnesota.

The work is based on a physics concept known as critical phenomena, used to explain phase transitions in physical systems, such as water changing from liquid to a gas.

In liquid form, water molecules are strongly correlated to one another. In a solid, they are locked into a predictable pattern of identical crystals. In a gas phase, however, every molecule is moving about on its own.

"At what is known as a critical point for a liquid, you cannot distinguish whether the material is liquid or vapor," Nemenman explains. "The material is neither perfectly ordered nor disordered. It's neither totally predictable nor totally unpredictable. A system at this 'just right' Goldilocks spot is said to be 'critical.'"

Very high temperature and pressure generate this critical point for water. And the structure of critical points is the same in many seemingly unrelated systems. For example, water transitioning into a gas and a magnet losing its magnetism as it is heated up are described by the same critical point, so the properties of these two transitions are similar.

In order to actually observe a material at a critical point to study its structure, physicists must tightly control experiments, adjusting the parameters to within an extraordinarily precise range, a process known as fine-tuning.

In recent decades, some scientists began thinking about the human brain as a critical system. Experiments suggest that brain activity lies in a Goldilocks spot -- right at a critical transition point between perfect order and disorder.

"The neurons of the brain don't function just as one big unit, like an army marching together, but they are also not behaving like a crowd of people running in all different directions," Nemenman says. "The hypothesis is that, as you increase the effective distance between neurons, the correlations between their activity are going to fall, but they will not fall to zero. The entire brain is coupled, acting like a big, interdependent machine, even while individual neurons vary in their activity."

Researchers began searching for actual signals of critical phenomena within brains. They explored a key question: What fine tunes the brain to reach criticality?

In 2019, a team at Princeton University recorded neurons in the brain of a mouse as it was running in a virtual maze. They applied theoretical physics tools developed for non-living systems to the neural activity data from the mouse brain. Their results suggested that the neural activity exhibits critical correlations, allowing predictions about how different parts of the brain will correlate with one another over time and over effective distances within the brain.

For the current paper, the Emory researchers wanted to test whether fine-tuning of particular parameters were necessary for the observation of criticality in the mouse brain experiments, or whether the critical correlations in the brain could be achieved simply through the process of it receiving external stimuli. The idea came from previous work that Nemenman's group collaborated on, explaining how biological systems can exhibit Zipf's law -- a unique pattern of activity found in disparate systems.

"We previously created a model that showed Zipf's law in a biological system, and that model did not require fine tuning," Nemenman says. "Zipf's law is a particular form of criticality. For this paper, we wanted to make that model a bit more complicated, to see if could predict the specific critical correlations observed in the mouse experiments."

The model's key ingredient is a set of a few hidden variables that modulate how likely individual neurons are to be active.

Morrell wrote the computer code to run simulations and test the model on her home desktop computer. "The biggest challenge was to write the code in a way that would allow it to run fast even when simulating a large system with limited computer memory without a huge server," she says.

The model was able to closely reproduce the experimental results in the simulations. The model does not require the careful tuning of parameters, generating activity that is apparently critical by any measure over a wide range of parameter choices.

"Our findings suggest that, if you do not view a brain as existing on its own, but you view it as a system receiving stimuli from the external world, then you can have critical behavior with no need for fine tuning," Nemenman says. "It raises the question of whether something similar could apply to non-living physical systems. It makes us re-think the very notion of criticality, which is a fundamental concept in physics."

The computer code for the model is now available online, so that anyone with a laptop computer can access it and run the code to simulate a dynamic system with varying inputs over time.

"The model we developed may apply beyond neuroscience, to any system in which widespread coupling to hidden variables is extant," Nemenman says. "Data from many biological or social systems are likely to appear critical via the same mechanism, without fine-tuning."

Scientists at the Institute for Cooperative Upcycling of Plastics (iCOUP), an Energy Frontier Research Center led by Ames Laboratory, have discovered a chemical process that provides biodegradable, valuable chemicals, which are used as surfactants and detergents in a range of applications, from discarded plastics. The process has the potential to create more sustainable and economically favorable lifecycles for plastics.

The researchers targeted their work on the deconstruction of polyolefins, which represents more than half of all discarded plastics, and includes nearly every kind of product imaginable-- toys, food packaging, pipe systems, water bottles, fabrics, shoes, cars, and furniture.

"Plastics, and especially polyolefins, are materials you could call too successful," said iCOUP Director Aaron Sadow. "They are fantastic-- strong, lightweight, thermally stable, chemically resistant-- for all the applications that we use them for, but the problem comes when we don't need them anymore."

It's all in the chemical construction of polyolefin plastics that makes them so tough and durable-- long strong chains of carbon-carbon bonds-- that also makes them hard to break down. Polyolefins also generally lack the chemical groups which could be targeted in deconstruction processes. Many existing processes to recycle plastic result in less-valuable, less usable components, making the economic feasibility of recycling far less appealing.

The new process uses what science already knows about key steps of polymerization-- the assembling of long polymer strands-- but in reverse, by breaking some of the carbon-carbon bonds in the chains. Once a few carbon-carbon bonds are broken, the shortened polymer chains transfer to an aluminum end group to form reactive species. The catalysts and reactions for this new process are related to those used in alkene polymerization, leveraging well-understood catalytic chemistry. Finally, the intermediates of this new transformation are easily converted into fatty alcohols or fatty acids, or used in other synthetic chemistry, to create chemicals or materials that are valuable in a whole host of ways: as detergents, emulsifiers, pharmaceuticals, and cosmetics. Because the process is catalytically controlled, desirable product chain lengths can be targeted for synthesis.

The best part about the process is that its end products are biodegradable, unlike polyethylene and polypropylene starting materials.

"Fatty acids and alcohols biodegrade in the environment relatively quickly. If these byproducts go on to find a new use elsewhere, that's wonderful, but it also has an end of life, which means it won't accumulate in the environment as plastics have," said Sadow.

There is consistent, strong evidence that the SARS-CoV-2 virus, which causes COVID-19, is predominantly transmitted through the air, according to a new assessment published today in the medical journal Lancet. Therefore, public health measures that fail to treat the virus as predominantly airborne leave people unprotected and allow the virus to spread, according to six experts from the UK, USA and Canada, including Jose-Luis Jimenez, chemist at the Cooperative Institute for Research in Environmental Sciences (CIRES) and University of Colorado Boulder.

"The evidence supporting airborne transmission is overwhelming, and evidence supporting large droplet transmission is almost non-existent," Jimenez said. "It is urgent that the World Health Organization and other public health agencies adapt their description of transmission to the scientific evidence so that the focus of mitigation is put on reducing airborne transmission."

The team of experts, led by the University of Oxford's Trish Greenhalgh, reviewed published research and identified 10 lines of evidence to support the predominance of the airborne route.

At the top of their list: Super-spreader events such as the Skagit Choir outbreak, in which 53 people became infected from a single infected case. Studies have confirmed these events cannot be adequately explained by close contact or touching shared surfaces or objects.

Moreover, transmission rates of SARS-CoV-2 are much higher indoors than outdoors, and transmission is greatly reduced by indoor ventilation.

The team highlighted research estimating that silent (asymptomatic or presymptomatic) transmission of SARS-CoV-2 from people who are not coughing or sneezing accounts for at least 40 percent of all transmission. This silent transmission is a key way COVID-19 has spread around the world, "supporting a predominantly airborne mode of transmission," according to the assessment. The researchers also cited work demonstrating long-range transmission of the virus between people in adjacent rooms in hotels; people who were never in each other's presence.

By contrast, the team found little to no evidence that the virus spreads easily via large droplets, which fall quickly through the air and contaminate surfaces.

"We were able to identify and interpret highly complex and specialist papers on the dynamics of fluid flows and the isolation of live virus," lead author Greenhalgh said. "While some individual papers were assessed as weak, overall the evidence base for airborne transmission is extensive and robust. There should be no further delay in implementing measures around the world to protect against such transmission."

The new work has serious implications for public health measures designed to mitigate the pandemic. First, "droplet measures" such as handwashing and surface cleaning, while not unimportant, should be given less emphasis than airborne measures, which deal with inhalation of infectious particles suspended in the air.

If an infectious virus is primarily airborne, someone can potentially be infected when they inhale aerosols produced when an infected person exhales, speaks, shouts, sings, or sneezes. So airborne control measures include ventilation, air filtration, reducing crowding and the amount of time people spend indoors, wearing masks whenever indoors (even if not within 6 feet or 2 meters of others), attention to mask quality and fit, and higher-grade PPE for healthcare and other staff when working in contact with potentially infectious people.

"It is quite surprising that anyone is still questioning whether airborne transmission is the predominant transmission pathway for this virus or not," said co-author Professor Kimberly Prather, an aerosol scientist from the University of California San Diego. "Only by including inhalation of aerosols at both close and long range can we explain the many indoor outbreaks that have occurred around the globe. Once we acknowledge this virus is airborne, we know how to fix it. There are many examples of places that have fared much better by acknowledging this virus is airborne from the start. The world needs to follow their lead as soon as possible."

More from the authors

Professor David Fisman, a physician-epidemiologist at the University of Toronto: "It's critically important for public health experts to work collaboratively with aerosol scientists and engineers. Establishment of aerosol transmission as the dominant mode of transmission of SARS-2 is actually good news, because we have abundant expertise for reducing the risk from aerosols. But these tools won't be put into use as long as there is a lack of clarity from public health agencies on how this disease spreads."

Infectious diseases physician Professor Robert Schooley from the University of California San Diego: "When one starts with the understanding that the virus replicates in the lungs and is exhaled with each breath in a range of particle sizes, some of which can travel well beyond the magical 6-foot curtain posited as the limit for droplets--and can persist in poorly ventilated locations--it is inevitable to conclude that public health strategies must center on those that reduce airborne spread of respiratory pathogens."

Professor Zeynep Tufekci, a sociologist from University of North Carolina, Chapel Hill said: "it's essential that the guidelines to the public explain accurately explain transmission mechanisms and their relative importance rather than focusing on binary rules like "six feet" that do not apply the same way across different contexts. Even after a whole year, we still see the widespread practice of unnecessary levels of cleaning to the detriment of public health, use of plexiglass indoors that is far from sufficiently protective and, depending on air flows, may even be contraindicated, instead of attention to ventilation and aerosol risks. We cannot fix this situation without accurately informing the public so that people feel empowered to make decisions to better protect themselves across different contexts, and adjusting guidelines globally to fit the best available evidence."

From cancer treatment to sunlight, radiation and toxins can severely damage DNA in both harmful and healthy cells. While the body has evolved to efficiently treat and restore damaged cells, the mechanisms that allow this natural repair remain misunderstood.

In a new study, Northwestern University researchers have used cryogenic electron microscopy (cryo-EM) to visualize this process by illuminating the mysterious cycle of DNA breakage sensing and repair. The researchers believe this new information could potentially form the basis for understanding how cells respond to chemotherapy and radiation and potentially even lead to improved cancer treatments.

Published Wednesday, April 14 in the journal Nature, the research offers new insight into how proteins work in concert to identify and resolve DNA double-strand breaks (DSB).

When a double strand break, or DSB -- the most severe form of DNA damage -- occurs, the repair pathway may insert or delete genes at the break site or potentially rearrange genes throughout the strand. In cases where chromosomal rearrangement occurs, catastrophic changes can lead to the development of cancer.

Using cryo-EM, researchers can obtain 3D images of macromolecular structures at atomic resolution. According to Yuan He, an assistant of molecular bioscience in the Weinberg College of Arts and Sciences, cryo-EM's ability to image dynamic machinery "goes way beyond the capabilities" of other structural biology techniques.

Imaging DNA-protein complexes at various transitory phases allowed He's team to identify and create a model of a cell's repair pathway.

"There are many factors that work in concert to seal the nick," said He, the study's corresponding author. "We're taking the most straightforward way to solve the problem -- by looking at proteins as they identify and repair a break."

The resulting model shows that, at times, two copies of DSB recognition complexes can hold together and bridge DSBs as the complexes signal for other factors to come to the breaking site. In another essential state, proteins align the two strands of DNA for a ligase to come and seal the nick. The lab then proposed a model of this pathway, showing how DNA bridges and aligns as it transfers between states.

[VIDEO] As the bottom component of the DNA-protein structure comes under stress, DNA strands are bridged to close proximity; once the component returns to a more relaxed state, the movement then joins the two DNA strands together.

"Seeing is believing" is a common saying in molecular biology, and one He thinks applies to his research directly. By observing the elegant process directly, an observer can easily make connections and understand how the complex system works together. But before this technology was available, He said it was akin to a blind person identifying an elephant by touch.

"Breakthroughs are usually thought of for something big and complex," said Siyu Chen, a postdoctoral student in He's lab and first author on the paper. "The question we're answering is fundamental and straightforward: DNA has been broken apart -- so how do proteins join them together?"

The lab hopes findings have implications for how our cells come back from and respond to radiation and chemotherapy. Future research could bring more targeted therapies for this newly understood pathway.

Infection with parasitic intestinal worms (helminths) can apparently cause sexually transmitted viral in-fections to be much more severe elsewhere in the body. This is shown by a study led by the Universities of Cape Town and Bonn. According to the study, helminth-infected mice developed significantly more severe symptoms after infection with a genital herpes viruses (Herpes Simplex Virus). The researchers suspect that these results can also be transferred to humans. The results have now appeared in the journal Cell Host & Microbe.

In sub-Saharan Africa, both worm infections and sexually transmitted viral diseases are extremely com-mon. These viral infections are also often particularly severe. It is possible that these findings are related. At least, this is the conclusion suggested by the current findings from mice.

The scientists involved in the study investigated how an infestation with helminths affects the course of a herpes infection of the female genital tract in the animals. "The results themselves surprised us in their clarity," explains Prof. William Horsnell PhD., of the Institute of Infectious Diseases and Molecular Medi-cine at the University of Cape Town. "Genital herpes disease is often accompanied by scarring of the vagi-na, known as necrosis. In our study, this serious symptomatology occurred twice as often as normal after helminth infestation."

The finding is also surprising because the worms themselves never infest the female genital tract. They are parasites that are ingested with food or through the skin and eventually migrate to the intestines. "So this is a remote effect of helminth infection that was not known before," explains Dr. Laura Layland of the Insti-tute of Medical Microbiology, Immunology and Parasitology at Bonn University Hospital.

Misdirected immune response

The researchers were able to show that a specific group of immune cells, the eosinophil granulocytes, is responsible for the necrotization. These are white blood cells that are specialized in fighting worms and other parasites. They are armed with cell-decomposing enzymes that they carry around inside them. However, these are not freely available - they are too dangerous for that. Instead, they are packed in so-called granules (hence the name "granulocytes"). Upon contact with a parasite, the cells channel these granules to the outside, where they release their deadly cargo.

"In our case, however, the worm infestation in the intestine causes eosinophilic granulocytes to accumu-late in the vagina during a concurrent genital herpes infection," Horsnell points out. "They then secrete their cell-damaging enzymes there, even though no helminths are present. And it's this misdirected im-mune response that leads to the serious damage in the mucosa of the vagina that we've observed."

A specific immune messenger, interleukin-33, appears to play an important role in this process, indirectly causing the accelerated maturation of granulocytes in the vagina. "We inhibited IL-33 with a specific com-pound," Horsnell explains. "The mice then developed significantly less tissue damage in the genital tract." The scientists are now looking for potential drugs that are also suitable for use in humans and that can be produced inexpensively.

Successful cooperation program

The fact that the study could be carried out successfully is also thanks to a cooperation program between Germany and Africa funded by the German Research Foundation (DFG). "The Institute of Medical Micro-biology, Immunology and Parasitology at the University of Bonn sees its role in this as being, among other things, the transfer of know-how," explains Dr. Laura Layland. "We train researchers in the countries on site, for example, in the use of analytical techniques and scientific methods, an offer that also benefits young scientists in particular."

To this end, Layland and her colleagues are conducting workshops in African countries and in Bonn, among other places. The aim is to strengthen existing scientific expertise in the affected regions and thus significantly improve research into and control of parasitic worm infections in the medium term.

A new analysis of antibody and B cell responses in 44 people who received either the Pfizer or Moderna mRNA SARS-CoV-2 mRNA vaccines shows that only one dose may be needed for previously infected patients who have since recovered. The study also supported that two doses is optimal to induce strong antibody and B cell responses in patients who are immunologically naïve for SARS-CoV-2, and antibodies induced by the vaccination could protect against the more infectious and deadly South African variant. The results build on an increasing body of research suggesting that people previously infected with SARS-CoV-2 may only require one dose of mRNA vaccination for optimal immune responses, including new correlations with SARS-CoV-2-specific B cell responses in these patients. Rishi Goel and colleagues studied the antibody and B cell responses in the blood of 33 SARS-CoV-2-naïve patients and 11 patients previously infected with the virus at multiple time points before, during, and after vaccination. Consistent with previous findings, they confirmed that the mRNA vaccines induced antibodies that could neutralize the D614C and B.1.351 variants. These responses peaked one week after the second vaccine dose in naïve patients but peaked two weeks after the first dose in recovered patients, with similar patterns in B cell responses for both groups. Older patients had lower antibody and B cell responses after the second dose, and the generation of new antibody responses relied on SARS-CoV-2-specific B cells in all ages. Thus, Goel et al. confirm previous findings on antibody responses to SARS-CoV-2 mRNA vaccination, while expanding on the importance of B cell responses.

A new study from North Carolina State University found that, on average, voters and local leaders showed greater concern about plastic and other garbage in the ocean after watching kids' presentations.

The findings, published in the journal Frontiers in Political Science, built on previous research that found educating kids about climate change was linked to an increase in concern in parents. The new findings indicate kids can have a broader impact outside of their families.

"Our lab has already established that kids can have an impact across the dinner table, and it's cool to see that they can also have an impact within town halls, too," said the study's lead author Jenna Hartley, a Ph.D. student in the NC State Department of Parks, Recreation and Tourism Management. "We also saw that kids could help close partisan gaps in how community members view this issue."

In the study, researchers surveyed adults after watching educational events or videos developed by approximately 2,500 fourth- and fifth-graders in North Carolina. The students first completed lessons developed by the Duke University Marine Lab Community Science Initiative on how plastics and other trash can end up in waterways.

Then, the students either made in-person presentations or public service announcement (PSA) videos that could be shared virtually with voters and local political leaders.

During the 2018-19 school year, students held eight in-person events including two school plays, an art show, and presentations at a restaurant and school board meeting. Due to the COVID-19 pandemic, all but one of the in-person presentations during the 2019-20 school year were canceled, and students developed PSAs that could be sent online instead.

Researchers received surveys from 172 adults, including 65 voters and 107 local officials, who either attended an in-person event or received a PSA online. The surveys asked the adults to rate their level of concern, on a scale of 1 through 5, about marine debris before and after the presentations, with 1 being extremely unconcerned, and 5 being extremely concerned. They also asked the adults to rate their level of support for policy initiatives on marine debris before and after the presentation on a scale of 1 to 5.

Adults' concern about marine debris increased from an average score of 3.93 to a 4.42. Adults also reported greater support for marine debris policies, with their average score among all participants increasing from a 3.92 to 4.40.

Voters had larger gains in concern about marine debris compared to local officials. Researchers did not find differences in concern or support for policy changes among adults depending on their gender or race, if adults knew the kids or not, or whether the presentations were in-person or virtual.

"Together with some of our other work on kids influencing adults, this study is pointing to a real potential for kids to have a powerful seat at the table," said Kathryn Stevenson, assistant professor of parks, recreation and tourism management at NC State. "Kids can play a real and needed part in the political process, especially if we're making decisions about their futures. We need to consider their perspectives."

The researchers also found kids' presentations could help narrow political divides. Conservatives had a lower average level of concern about marine debris initially at a score of 3.69, while liberals had a higher average at 4.36. Both groups increased their concern on average, with levels of concern among conservatives approaching that of liberals, after the presentations. Conservatives' average score after the presentations was a 4.33, and liberals averaged a score of 4.64.

They found that in terms of support for policy change to prevent or clean up trash in the ocean, liberals and conservatives' average scores remained relatively polarized.

"We have a lot to learn about how powerful this effect is, how long these effects last, how big a difference it can make, and with whom," Stevenson said. "But so far, it's really encouraging. Kids should take heart in that, and know they have power. And educators and parents should understand that kids have an important voice in the community."