Tech

People are different. New technology is good for patients and the healthcare system. But it could also expand the already significant health disparities in Norway and other countries.

"Women and men with higher education in Norway live five to six years longer than people with that only have lower secondary school education," says Emil Øversveen, a postdoctoral fellow at the Norwegian University of Science and Technology's (NTNU) Department of Sociology and Political Science.

He is affiliated with CHAIN, the Centre for Global Health Inequalities Research. The centre works to reduce social health inequalities worldwide.

Both Norwegian and international research shows that people with low occupational status, low income and less education have poorer health and live shorter lives than people higher up in the social hierarchy.

Øversveen has looked at whether new technology might be further increasing health disparities. His study compares differences between countries and between people within various countries.

"Vaccines are a health technology, too. The new knowledge can be used to understand why the COVID-19 vaccine is being unequally distributed around the world," says Øversveen.

We see that wealthy players like the USA, England and the EU countries are securing vaccines for themselves. These countries and people are buying their way to the front of the queue.

Norway has greater internal health inequities than many other European countries. These health discrepancies crop up in all age groups, including among children and young people.

The survey indicates that the differences have increased over time. Men's life expectancy between districts in Oslo has now grown to an eight-year difference.

In general, new health technology offers more opportunities for better treatment of patients and a more efficient health care system.

"For example, our smartwatch can send reports about our health directly to our doctor, and we can follow statistics and get recommendations on medication dosages on a phone app," Øversveen says.

These options are great for the folks who can benefit from them. But in practice, not everyone in Norway has equal access to the latest technology.

Øversveen has investigated how patients with diabetes use medical technology. At the same time, he has looked at how doctors and nurses decide who has access to the technology.

"Based on my qualitative research, I see that this patient group generally experiences that diabetes technology is difficult to access in the Norwegian health care system," says Øversveen.

But the technology isn't equally difficult for everyone. Patients' social characteristics and status play an important role when healthcare professionals prioritize who should be allowed to use the technology.

"The resourceful patients learn how they can 'buy their way in' as qualified, active and competent patients who 'deserve' the expensive technology," Øversveen says.

His work shows how the development, distribution and use of medical technology can contribute to creating and maintaining social health inequities in the public health care system.

"This is new and important knowledge about a large and global societal problem," says Øversveen.

Social inequalities in health care access exist in many countries, if not all. The study shows systematic links between health status and social position, causing a lot of people to lose out.

"Social health inequities are unfair and represent a loss for individuals, families and society," says Øversveen.

CHAIN is an interdisciplinary centre at NTNU that studies global health inequalities.

In the dry air and soil of Texas' Southern High Plains, improving soil health can be tough. We usually think of healthy soil as moist and loose with lots of organic matter. But this can be hard to achieve in this arid area of Texas.

Lindsey Slaughter, a member of the Soil Science Society of America, set out with her fellow researchers to test a solution that kills two birds with one stone. They put excess cow manure on these soils to see if they could make them healthier.

The team recently published their research in the Soil Science Society of America Journal.

"We know that planting perennial grasslands for cattle production can help protect and restore soil in semi-arid lands that are likely to erode and degrade from intense farming," Slaughter says. "But producers need additional ways to increase soil carbon and nutrient stores."

What makes a healthy or unhealthy soil?

Slaughter describes soil health as the ability of a living soil ecosystem to perform a variety of important functions. These include cycling nutrients, storing and purifying water, helping plants and animals, and more.

This "living" part is made up of various microorganisms that help a soil be healthy. They, for example, help break down materials like manure so that it and its nutrients become part of the soil.

"Improving the soil's ability to perform these roles and support plant and animal life is our target for soil health," Slaughter says. "Adding the manure can provide a boost of material that can be incorporated into soil organic matter. This helps provide a stronger foundation for more microbial activity and nutrient cycling."

This is why in their study they applied a low one-time amount of manure to two types of pastures to look into this. The pastures they put the manure on had either grass only that was fertilized occasionally or were a mix of grass and legumes that was not fertilized.

Manure helps, but results take time

Overall, they did find that manure helped increase soil organic carbon and the number of microbes in the soil. These are two important characteristics of a healthy soil.

It took almost a year and a half to see these changes, although they say this is not totally surprising.

"This tells us that it can take a long time for even a little added compost to become incorporated into the soil organic matter of semi-arid grasslands, but it definitely helps," Slaughter explains.

"We think this is mostly due to the dry climate at our study site," says Slaughter. "We commonly get little rainfall per year. The microbial community was not able to work quickly or efficiently to decompose the manure without water."

Their results also showed that the pastures receiving fertilizer responded better to the manure. They believe this is because the nitrogen in the fertilizer helped the microbes decompose the manure better.

"Microbes help directly with releasing nutrients from organic material in a form that plants can use, as well as decomposing those residues to build soil organic matter," Slaughter says. "A lot of work has been done on how this can help improve cropping systems. However, we wanted to also test this on forage pastures."

Slaughter adds that the next steps in this work include whether more manure or multiple applications would get faster results. In addition, they hope to investigate if irrigation or fertilizer would help incorporate the manure faster.

"We need more research along these lines to help us design strategies that quickly and effectively increase soil health and productivity in these grasslands," she says. "This helps farmers save money on nutrients and amendments while building soil organic matter and nutrient cycling capacity. This also saves them water and protects against soil degradation."

The per-capita rates of new COVID-19 cases and COVID-19 deaths were higher in states with Democrat governors in the first months of the pandemic last year, but became much higher in states with Republican governors by mid-summer and through 2020, possibly reflecting COVID-19 policy differences between GOP- and Democrat-led states, according to a study led by researchers at the Johns Hopkins Bloomberg School of Public Health and the Medical University of South Carolina.

For their study, the researchers analyzed data on SARS-CoV-2-positive nasal swab tests, COVID-19 diagnoses, and COVID-19 fatalities, for the 50 U.S. states and the District of Columbia. After adjusting for confounding factors such as state population density, they found that Republican-governed states began to have consistently higher rates of positive swab tests in May, of COVID-19 diagnoses in June, and of COVID-19 mortality in July.

The results, published online March 10 in the American Journal of Preventive Medicine, suggest that policy differences between Republican- and Democrat-governed states, including mitigation measures such as mask mandates and social distancing requirements, may have led to systematic differences in COVID-19's impact on public health, the researchers say.

"Governors' party affiliation may have contributed to a range of policy decisions that, together, influenced the spread of the virus," says study senior author Sara Benjamin-Neelon, PhD, professor in the Bloomberg School's Department of Health, Behavior and Society. "These findings underscore the need for state policy actions that are guided by public health considerations rather than by partisan politics."

The analysis covered March 15 to December 15, 2020, and included the number of SARS-CoV-2 tests, positive tests, COVID-19 case diagnoses, and COVID-19 fatalities. The researchers used a sophisticated statistical tool called a Bayesian negative binomial model to estimate, for each day in the nine-month study window, the relative risks or chances of getting tested, testing positive, getting COVID-19, or dying of COVID-19, for people in 26 GOP-governed vs. 25 Democrat-governed states. Washington, D.C. was treated as Democrat-governed.

The researchers were aware that many other factors, including the natural progression of the pandemic from early waves in urban areas, such as New York City and Seattle, to later waves in rural areas, might have contributed to differences between Republican- and Democrat-led states. However, they attempted to correct for these confounding factors in their analysis.

Their findings, even when factoring in these confounders, revealed a clear pattern in which Democrat-led states were hardest-hit early in the pandemic, but after a few months Republican-led states on average began to have more positive tests, COVID-19 cases, and more COVID-19 deaths. The transition occurred for testing-positivity on May 30, for COVID-19 case diagnoses on June 3, and for COVID-19 deaths on July 4. The differences between the two groups of states peaked in the period from late June to early August--for example, on August 5 the relative risk of dying of COVID-19 was 1.8 times higher in GOP-led states.

Testing rates were similar for the two sets of states until late September when Republican-led states began to have lower testing rates.

Other studies have found evidence that Republican governors in 2020 were broadly less strict than their Democrat counterparts in setting policies on mask-wearing, social distancing, and other pandemic-related measures. The researchers say that those studies, along with the links they found between Republican governorship and greater COVID-19 impact, are consistent with the idea that the political polarization of the COVID-19 response has contributed to less effective COVID-19 policies and worse case-related statistics in some states.

"Despite a more coordinated federal response this year, governors still play a key role in the pandemic response," says Benjamin-Neelon. "As we're seeing, several states have lifted mask requirements even though we have yet to make substantial progress in controlling the spread of the virus."

Immune cells specialize to ensure the most efficient defense against viruses and other pathogens. Researchers at the University of Basel have shed light on this specialization of T cells and shown that it occurs differently in the context of an acute and a chronic infection. This could be relevant for new approaches against chronic viral infections.

Researchers led by Professor Carolyn King of the University of Basel have developed a method to study the specialization of T cells in the context of infections. In the journal eLife, they report the different directions this specialization takes, depending on whether it happens in the context of an acute viral infection such as influenza or a chronic one such as HIV infection or malaria, which can no longer be overcome by the body.

The study focused on so-called T-helper cells. When such a cell is activated by a viral infection, it can specialize in one of two ways: into a Th1 cell, which drives a more inflammation-heavy T killer cell response, or into a T follicular helper (Tfh) cell, which primarily supports antibody production. The balance between Th1 and Tfh cells therefore has important implications for how inflammatory the body's immune response is.

However, there are still gaps in our knowledge of how exactly a T helper cell decides which path to take when specializing. One factor that may play an important role is how strongly the T helper cell is activated - or, more precisely, its T cell receptor. The T-cell receptor is a kind of molecular sensor on the surface of the cell that more or less matches a part of the pathogen. The better they match, the more the receptor is activated.

Until now, however, it has not been possible to study the role of T-cell receptor signaling strength in the context of viral infections because researchers lacked a suitable experimental model. King and her team have now been able to develop one (see box) in collaboration with the research group of Professor Daniel Pinschewer, like King at the Department of Biomedicine.

The results of their analysis surprised the researchers: T-cell receptor activation does play a role, but an opposing one, depending on whether the infection was acute or chronic. Strong activation led to more inflammatory Th1 cells in acute viral infection. However, in chronic infection, strong activation produced more non-inflammatory Tfh cells.

"The reason behind this could be an evolutionary adaptation of nature to protect its own body," explains Dr. Marco Künzli, first author of the study. "If too many inflammatory Th1 cells are produced for too long during chronic infections, this would harm the body's own organs in the long run."

The experiments also yielded another interesting finding: Th1 cells that form as a result of weak activation could remain functional longer in chronic infection than if their specialization was triggered by strong activation of the receptor. This is relevant because Th1 cells "fatigue" over time in chronic infections.

"Our results add a piece to the puzzle of T cell exhaustion and might - as a first step - contribute to new approaches in treating chronic viral infections," King summarizes the significance of the findings.

Context box: Measuring the fate of T cells

For their new method, the research group relied on mice with T helper cells that all carry the same receptor, which recognizes a specific virus (lymphocytic choriomeningitis virus, or LCMV). The researchers specifically mutated this LCMV to activate the T cell receptor strongly, at an intermediate level or only weakly. In addition, there are two minimally different types of LCMV, one leading to acute infections and the other leading to chronic infections. Thus, the researchers were able to infect the mice with the different virus variants and study the further development of the T cells in their blood - on the one hand in the context of an acute, on the other hand in the context of a chronic virus infection.

The scientists of the National University of Science and Technology "MISIS" (NUST MISIS) being a part of an international team of researches managed to increase the capacity and extend the service life of lithium-ion batteries. According to the researchers, they have synthesized a new nanomaterial that can replace low-efficiency graphite used in lithium-ion batteries today. The results of the research are published in the Journal of Alloys and Compounds.

Lithium-ion batteries are widely used for household appliances from smartphones to electric vehicles. The charge-discharge cycle in such battery is provided by the movement of lithium ions between two electrodes -- from a negatively charged anode to a positively charged cathode.

The scope of application of lithium-ion batteries is constantly expanding, but at the same time, according to the scientists, their capacity is still limited by the properties of graphite -- the main anode material. Scientists from NUST MISIS managed to obtain a new material for anodes that can provide a significant increase in capacity and extend battery service life.

"Porous nanostructured microspheres with the composition Cu0.4Zn0.6Fe2O4, that we have extracted, used as anode material provide three times higher capacity than the batteries existing on market. Besides, it allows to increase the number of charge-discharge cycles by 5 times compared to other promising alternatives to graphite. This improvement is achieved due to a synergistic effect with a combination of a special nanostructure and the composition of used elements", -- Evgeny Kolesnikov, an assistant at the Department of Functional Nanosystems and High-Temperature Materials, NUST MISIS said.

The synthesis of the final material happens via one step process without intermediate stages due to the use of the spray-pyrolysis method. As the scientists explained, aqueous solution with ions of special metals is converted into fog with the help of ultrasound, and then water is evaporated at temperatures up to 1200 ° C with decomposition of the original metal salts. As the result, micron or submicron spheres with the porosity, that is required to operate in a lithium-ion system, are extracted.

Energy-efficient light-emitting diodes (LEDs) have been used in our everyday life for many decades. But the quest for better LEDs, offering both lower costs and brighter colours, has recently drawn scientists to a material called perovskite. A recent joint-research project co-led by the scientist from City University of Hong Kong (CityU) has now developed a 2D perovskite material for the most efficient LEDs.

From household lighting to mobile phone displays, from pinpoint lighting needed for endoscopy procedures to light source to grow vegetables in Space, LEDs are everywhere. Yet current high-quality LEDs still need to be processed at high temperatures and using elaborated deposition technologies -- which make their production cost expensive.

Scientists have recently realised that metal halide perovskites - semiconductor materials with the same structure as calcium titanate mineral, but with another elemental composition - are extremely promising candidates for next-generation LEDs. These perovskites can be processed into LEDs from solution at room temperature, thus largely reducing their production cost. Yet, the electro-luminescence performance of perovskites in LEDs still has room for improvement.

Led by Professor Andrey Rogach, Chair Professor at the Department of Materials Science and Engineering at CityU, and his collaborator Professor Yang Xuyong from Shanghai University, the team has found a kind of dimmer switch: they could turn one light emission from perovskites to a brighter level!

They worked with two-dimensional (2D) perovskites (also known as Ruddlesden-Popper perovskites) and succeeded to realise very efficient and bright LEDs, with best-reported performance on both current efficiency and external quantum efficiency for devices based on this kind of perovskites. This work has now put the perovskite LEDs close on the heels of current commercial display technologies, such as organic LEDs.

Their findings were published in the scientific journal Nature Communications, titled "Smoothing the energy transfer pathway in quasi-2D perovskite films using methanesulfonate leads to highly efficient light-emitting devices".

The key to the powerful change lies in the addition of around 10% of a simple organic molecule called methanesulfonate (MeS).

In this study, the 2D perovskites used by the team have a nanometre level thickness. The MeS reconstructs the structure of the 2D perovskite nanosheets, while at the same time enhancing exciton energy transfer between sheets of different thicknesses. Both of these changes have greatly enhanced the electro-luminescence of the thicker, green-emitting perovskite sheets within the 2D structure.

The MeS is also useful in reducing the number of defects in the 2D perovskite structure. During the process of light production, where radiative recombination took place, part of the excitons required for the process will be "wasted" in the non-radiative recombination which produces no light. MeS reduces the number of uncoordinated Pb2+ cations, the cause for excitons to undergo the non-radiative recombination, making sure more excitons participating in light production.

The results of the research for producing better LEDs has been encouraging. The brightness of 13,400 candela/m2 at a low applied voltage of 5.5 V, and external quantum efficiency of 20.5% were recorded. This is close to the maximum that many existing LED technologies can achieve, and has almost doubled the external quantum efficiency level of 10.5% reported in their previous study two years ago.

"My CityU team has built-up its expertise on perovskite materials to a very high level in a relatively short period of time, thanks to funding support from Senior Research Fellowship by the Croucher Foundation. And already we see the benefit, especially in the outcomes detailed in this latest publication," said Professor Rogach.

"The achieved high brightness, excellent colour purity, and commercial grade operating efficiency mark 2D perovskites as extremely attractive materials for future commercial LEDs, and potentially also display technology. It's a tangible outcome from both fundamental and applied research into novel nano-scale materials" he adds.

Researchers hope to use an agricultural pest's genetic code against it to prevent billions of dollars in annual losses in the United States.

Stable flies, or Stomoxys calcitrans, are spotted, tan-colored flies found around the world. They are easily mistaken for the common housefly but for one notable distinction: They bite.

"If you get one in your house and it bites you, it's a stable fly," said Joshua Benoit, an assistant professor of biology at the University of Cincinnati.

Stable flies don't bite so much as chomp. They are the scourge of beachgoers in Florida and recreational boaters in upstate New York. According to Thomas Jefferson, they tormented signatories of the Declaration of Independence.

"You shoo it away and shoo it away but it's persistent and lands on you. And then it bites. And it's not a pleasant bite. It's a pretty vicious, painful bite," Benoit said.

UC joined an international team that unlocked the genome of stable flies. Benoit and his students contributed to a fundamental research project called i5k that has the ambitious goal to sequence the genes of 5,000 species of arthropods, the group that includes spiders, insects and crabs.

"It's a pretty cool project. Molecular research on stable flies is far behind many other organisms. Our goal was to jump it up so we have a good model system to understand the biology of stable flies," Benoit said.

Previously, UC worked on similar projects for bedbugs and the agricultural menaces thrips and screwworms.

With stable flies, Benoit said they were looking for possible weaknesses to exploit in its genetic code. Researchers examined stable fly biology using genomic sequencing and RNA analysis over the fly's development. They also identified 1,600 genes related to stable fly reproduction, which could lead to new biological controls without the use of pesticides.

"Conducting research for its own sake is reward enough, but it is always heartening when the findings generate interesting novel avenues for exploration," study co-author and UC postdoctoral researcher Christopher Holmes said.

The study was published in the journal BMC Biology. Pia Untalan Olafson of the U.S. Department of Agriculture was the study's lead author.

"Stable flies are arguably one of the most important pests of livestock in the United States," Olafson said.

The project has huge economic implications from tourism to agriculture. Nobody can nap in a beach chair with stable flies for company. The flies cause an estimated $2.2 billion in livestock production each year, according to the U.S. Department of Agriculture. Cows beset by stable flies produce less milk and put on less weight.

Unlike mosquitoes, both male and female stable flies bite. 

"It's a nonstop onslaught all the time. The flies need a blood meal to survive and reproduce. So they will keep trying to bite and trying to bite. They are very persistent," Benoit said.

"When you get a thousand of these biting a cow, it can have a huge impact on agricultural productivity."

Olafson said the research has implications far beyond the United States.

"Worldwide, these flies have become a societal issue of public and political importance," she said. "Growing international agroindustries, like pineapple, coffee and sugarcane, produce large amounts of byproduct that are ideal sites for stable fly larvae to develop. These sites can produce upwards of hundreds of thousands of flies per acre. Livestock producers and communities that neighbor these industries feel the impact."

UC's study also helps scientists better understand why some flies evolved to feed on blood while similar species didn't. The flies lay their eggs in wet or rotting vegetation like the wet hay or straw found around barns and stables that give them their associated name.

By understanding the genes responsible for stable fly reproduction, researchers hope to design novel biological controls similar to methods that have worked to eradicate other pests such as screwworms. The USDA raises screwworms by the millions, releasing sterilized males over Central America to keep them from pushing north to plague North American cattle ranches.

"Any targeted control like that is probably better than widescale pesticide application, which will kill all insects. So you don't have to release chemicals into the environment," Benoit said.

DALLAS - March 10, 2021 - UT Southwestern scientists have identified key genes involved in brain waves that are pivotal for encoding memories. The findings, published online this week in Nature Neuroscience, could eventually be used to develop novel therapies for people with memory loss disorders such as Alzheimer's disease and other forms of dementia.

Making a memory involves groups of brain cells firing cooperatively at various frequencies, a phenomenon known as neural oscillations. However, explain study leaders Bradley C. Lega, M.D., associate professor of neurological surgery, neurology, and psychiatry, and Genevieve Konopka, Ph.D., associate professor of neuroscience, the genetic basis of this process is not clear.

"There's a famous saying for 100 years in neuroscience: Neurons that fire together will wire together," says Lega. "We know that cells involved in learning fire in groups and form new connections because of the influence of these oscillations. But how genes regulate this process in people is completely unknown."

Lega and Konopka, both members of the Peter O'Donnell Jr. Brain Institute, collaborated on a previous study to explore this question, collecting data on neural oscillations from volunteers and using statistical methods to connect this information to data on gene activity collected from postmortem brains. Although these results identified a promising list of genes, Konopka says, there was a significant shortcoming in the research: The oscillation and genetic data came from different sets of individuals.

More recently, the duo capitalized on an unprecedented opportunity - performing a similar study on patients undergoing surgeries in which damaged parts of their brains were removed to help control their epilepsy.

The researchers worked with 16 volunteers from UT Southwestern's Epilepsy Monitoring Unit, where epilepsy patients stay for several days before having surgery to remove the damaged parts of their brains that spark seizures. Electrodes implanted in these patients' brains over this time not only help their surgeons precisely identify the focus of the seizure, Lega says, but can also provide valuable information on the brain's inner workings.

While recording the electrical activity in the brains of 16 volunteers, the researchers had them do "free recall" tasks that involved reading a list of 12 words, doing a short math problem to distract them, and then recalling as many words as possible. As these patients were memorizing the word lists, their brain waves were recorded, creating a dataset that differed slightly from person to person.

About six weeks later, each volunteer underwent a temporal lobectomy - removal of the brain's temporal lobe - to cure their seizures. This area frequently serves as an originator of epileptic seizures and is also important for memory formation. Within five minutes of the surgery, the damaged brain tissue was sent for processing to assess genetic activity.

Konopka's team first performed whole RNA sequencing, a technique that identifies active genes, in temporal lobe samples that included all the brain's cell types. Using statistical techniques that linked this activity to the patients' neural oscillations during the free recall task, the researchers identified 300 genes that appeared to play a part in oscillatory activity. The researchers narrowed this number to a dozen "hub genes" that appeared to control separate gene networks.

Next, the researchers looked at the activity of these hub genes in separate cell types within the samples. Surprisingly, they found that several of these hubs weren't active within nerve cells themselves but in a different population of cells known as glia. These cells provide support and protection for nerve cells, including manufacturing the fatty layer that insulates nerve cells so they can efficiently pass electrical signals.

Finally, the researchers used a technique called ATAC-seq, which identifies areas of DNA that are open for molecules called transcription factors to attach to and activate genes. Using this approach, they honed in on SMAD3, a gene that appears to serve as a master regulator to control activity of many of the hub genes and the genes they control in return.

Konopka and Lega note that several of the genes they identified as important in human neural oscillations have been linked to other disorders that can affect learning and memory, such as autism spectrum disorder, attention deficit hyperactivity disorder, bipolar disorder, and schizophrenia. With further research into these genes and the networks they operate within, it may eventually be possible to target select genes with pharmaceuticals to improve memory in individuals with these and other conditions, the researchers say.

"This gives us an entry point," says Konopka, a Jon Heighten Scholar in Autism Research. "It's something we can focus on to learn more about the underpinnings of human memory."

When we recall a memory, we retrieve specific details about it: where, when, with whom. But we often also experience a vivid feeling of remembering the event, sometimes almost reliving it. Memory researchers call these processes objective and subjective memory, respectively. A new study from the Center for Mind and Brain at the University of California, Davis, shows that objective and subjective memory can function independently, involve different parts of the brain, and that people base their decisions on subjective memory -- how they feel about a memory -- more than on its accuracy.

"The study distinguishes between how well we remember and how well we think we remember, and shows that decision making depends primarily on the subjective evaluation of memory evidence," said co-author Simona Ghetti, professor at the UC Davis Department of Psychology and Center for Mind and Brain. The work is published March 9 in the journal eLife.

Postdoctoral researcher Yana Fandakova, now an investigator at the Max Planck Institute for Human Development in Berlin, graduate student Elliott Johnson and Ghetti tested objective and subjective memory. After showing volunteers a series of images of common objects, the researchers showed them pairs of images and asked them to determine which of the two they had seen before. The volunteers were asked to rate the memory as "recollected," if they experienced it as vivid and detailed, or as "familiar" if they felt that the memory lacked detail. In some of the tests, image pairs included a target image and a similar image of the same object. In others, the target was shown with an unrelated image from the same original set. For example, a chair might be shown with another chair shown from a different angle, or with an apple.

This experimental design allowed the researchers to score objective memory by how well the volunteers recalled previously seeing an image, and subjective memory by how they rated their own memory as vividly recollected or merely familiar. Finally, participants were asked to select which images to keep or discard, assigning them to a treasure chest or trash bin.

The team also used functional MRI to measure brain activity during this task.

Scoring objective and subjective memory

The results showed higher levels of objective memory when participants were tested with pairs of similar images. But, people were more likely to claim that they remembered vividly when looking at pairs of dissimilar images.

Participants were more likely to base their decision about whether to keep or trash an image on how they felt about a memory rather than its objective accuracy.

To give a real-world example, a person could have a vivid memory of going to an event with friends. Some of the actual details of that memory might be a bit off, but they may feel it is a vivid memory, so they might decide to go out with the same people again (after the pandemic).

On the other hand, if someone has learned to use similar power tools doing odd jobs around the house, their memories about those objects may be quite specific.

"But you might still feel that you are not recalling vividly because you might question whether you are remembering the right procedure about the right tool. So, you may end up asking for help instead of relying on your memory," Ghetti said.

The fMRI data showed that objective and subjective memory recruited distinct cortical regions in the parietal and prefrontal regions. The regions involved in subjective experiences were also involved in decision making, bolstering the connection between the two processes.

"By understanding how our brains give rise to vivid subjective memories and memory decisions, we are moving a step closer to understanding how we learn to evaluate memory evidence in order to make effective decisions in the future," Fandakova said.

An international team led by Artem R. Oganov, a Professor at Skoltech and MISIS, and Dr. Ivan Troyan from the Institute of Crystallography of RAS performed theoretical and experimental research on a new high-temperature superconductor, yttrium hydride (YH6). Their findings were published in the journal Advanced Materials.

Yttrium hydrides rank among the three highest-temperature superconductors known to date. The leader among the three is a material with an unknown S-C-H composition and superconductivity at 288 K, which is followed by lanthanum hydride, LaH10, superconducting at temperatures up to 259 K), and, finally, yttrium hydrides, YH6 and YH9, with maximum superconductivity temperatures of 224 K and 243 K, respectively. The superconductivity of YH6 was predicted by Chinese scientists in 2015. All of these hydrides reach their maximum superconductivity temperatures at very high pressures: 2.7 million atmospheres for S-C-H and about 1.4-1.7 million atmospheres for LaH10 and YH6. The high pressure requirement remains a major roadblock for quantity production.

"Until 2015, 138 K (or 166 K under pressure) was the record of high-temperature superconductivity. Room-temperature superconductivity, which would have been laughable just five years ago, has become a reality. Right now, the whole point is to attain room-temperature superconductivity at lower pressures," says Dmitry Semenok, a co-author of the paper and a PhD student at Skoltech.

The highest-temperature superconductors were first predicted in theory and then created and investigated experimentally. When studying new materials, chemists start by making theoretical predictions and then testing new material in practice.

"First, we look at the bigger picture and study a multitude of different materials on the computer. This makes things much faster. More detailed calculations follow the initial screening. Sorting through fifty or a hundred materials takes about a year, while an experiment with a single material of particular interest may last a year or two," Oganov comments.

Typically, critical superconductivity temperatures are predicted by theory with an error of about 10-15%. Similar accuracy is achieved in critical magnetic field predictions. In the case of YH6, the agreement between theory and experiment is rather poor. For example, the critical magnetic field observed in the experiment is 2 to 2.5 times greater as compared to theoretical predictions. This is the first time scientists encounter such a discrepancy which is yet to be explained. Perhaps, some additional physical effects contribute to this material's superconductivity and were not accounted for in theoretical calculations.

A new study, published this week in Proceedings of the National Academy of Sciences, reveals that nitrogen-fixing trees play an underrecognized role in recovering tropical forests by enriching nutrient-poor soils with scarce elements such as phosphorus and molybdenum.

Coauthor Sarah Batterman, a tropical forest ecologist at Cary Institute of Ecosystem Studies, explains, "We've long known that nitrogen-fixing trees work with soil microbes to make atmospheric nitrogen available to plants. Our study found that nitrogen fixers also play a vital role in unlocking other nutrients by weathering rocks beneath their roots. These nutrients include things like phosphorus, which is very limited in tropical forest soils and important to plant growth."

In this study, the team compared the soils of nitrogen-fixing and non-fixing trees across young recovering tropical forest plots that are part of the Agua Salud Secondary Forest Dynamics Network in the Panama Canal Area. They measured soil pH and mineral weathering - a process that releases nutrients trapped in rocks. They also assessed the composition of the soil microbial community.

To measure weathering, they buried 504 mesh bags of rocks (crushed dunite) under trees, and measured nutrient weathering from the rocks over eight months. Dunite was chosen because it weathers at a rate comparable to minerals in local soils. Trees sampled included five species of nitrogen fixers (51 trees), five species of non-fixers situated in a legume-rich area (39 trees), and five species of non-fixers situated far from any legumes (36 trees).

Batterman explains, "Mineral weathering under nitrogen fixers happened twice as fast as weathering under non-fixers. The soil under nitrogen fixers was far more acidic than the soil under non-fixers. This increased acidity promotes weathering and the release of chemical elements locked in minerals as they break down."

The team also discovered that soils beneath nitrogen fixers were teeming with a bacterial genus new to science (Candidatus Acidoferrum) that thrives in the acidic conditions created by nitrogen-fixing trees. These bacteria are highly enriched under nitrogen fixers, where they enable phosphorus release by breaking down iron-bearing minerals.

Two important products of weathering include available phosphorus and molybdenum. Phosphorus boosts plant growth, and molybdenum helps plants assimilate nitrogen. Before weathering, these scarce but critical elements are trapped in the aluminum and iron found in Panamanian soils. The acidic conditions found beneath the roots of nitrogen fixers catalyze the weathering needed to release phosphorus and molybdenum in bioavailable forms that plants can use.

Co-author Kristin Saltonstall of Smithsonian Tropical Research Institute explains, "Together, acidic soil conditions and a distinct community of bacteria enhance nitrogen fixers' ability to weather rocks and access nutrients. Benefits aren't limited to fixers themselves. We also found that nitrogen fixers help fertilize other plants throughout the forest, with broad effects on nutrient cycling in the forest community."

Lead author Dimitar Epihov of the University of Sheffield points out, "Tree diversity has long been recognized as vital for successful forest recovery. Current views dictate that nitrogen-fixing trees supply nitrogen to help speed up the recovery process. Our work expands these views by revealing that these trees also modulate the microbiome of soils belowground, enabling the release of other non-nitrogen nutrients from rocks. Benefits can be passed on to neighboring trees, and aid in the productivity of regrowing forests in the tropics."

Batterman notes, "Nitrogen-fixing trees have presented ecologists with a longstanding paradox. They are abundant in tropical forests, but so is nitrogen in the soil. Why are they so common, if access to nitrogen does not typically limit growth? Our findings offer an answer to this puzzle. Regardless of whether they are actively fixing, nitrogen fixers also have a unique ability to unlock phosphorus, which is very limited."

Tropical forests are responsible for 70% of the global forest carbon sink, yet they are under threat due to mining, logging, agriculture, development, and climate change. Understanding how different tree species influence tropical forests is essential to informing science-based reforestation strategies.

Batterman concludes, "Tropical soils tend to be nutrient-poor, which can slow forest recovery. Including nitrogen-fixing species in reforestation projects could helping neighboring trees obtain more nutrients, grow quicker, and ultimately help protect the tropical carbon sink."

A study conducted by researchers at the University of São Paulo in Brazil shows that competition for nutrients and lack of cooperation among bacteria of the species Escherichia coli in the same population and in situations of food scarcity prevent mutants that are better adapted to the environment from flourishing, except those that organize in small groups. The phenomenon masks the emergence of novel bacterial variants, making the mutation rate seem lower than it is in fact.

Mutants constantly emerge and accumulate from one generation to the next. Mutation frequency determines the evolution of a given species. Understanding the origin of mutations is also important to explain biological processes. In the case of bacteria, for example, it helps explain the potential evolutionary divergence of a pathogen in an epidemic or resistance to antibiotics.

In an article on the study published in the journal BMC Biology, the researchers compare what happens in colonies of E. coli with the "tragedy of the commons", a term used by economists as well as ecologists to refer to the problems that occur when individuals pursue personal gain to the detriment of their community, resulting in the destruction of public goods or natural resources.

"At times of nutritional scarcity, bacteria don't interact for mutual benefit, to assure growth of the colony. We found that even the emergence of a few individuals that can use the available food sources doesn't prevent this lack of cooperation from jeopardizing the entire population. Only a small number of mutants are able to multiply and form new colonies," said Beny Spira, a professor at the university's Biomedical Sciences Institute (ICB-USP) and last author of the article.

The finding explains the longstanding question of why the frequency of mutants capable of cleaving certain nutrients (breaking them down into molecules that can be metabolized) is always much lower in practice than in theory.

The research on mutant frequency masking is part of a project supported by São Paulo Research Foundation - FAPESP via a Research Regular Grant, a doctoral scholarship and a scientific initiation grant.

Tragedy of the commons

Unlike wild-type E. coli, bacteria with PHO-constitutive mutations overexpress the enzyme alkaline phosphatase and hence can cleave glycerol-2-phosphate (G2P) to release phosphate and glycerol, an important source of carbon, especially in situations of nutritional scarcity. PHO stands for phosphate. The "PHO regulon" helps plant cells survive and thrive despite nutrient scarcity and phosphate depletion in the environment.

The frequency of PHO-constitutive colonies on G2P selective plates (cell culture dishes) is exceptionally low. "When we measure actual mutant frequency, we find that in a population of 100 billion bacteria there are tens of thousands of PHO-constitutive mutants. Yet only 50 to 100 manage to multiply and produce new colonies with the mutation that confers the ability to cleave G2P," Spira told.

The mutant, he explained, is capable of expressing large amounts of alkaline phosphatase, which is compartmentalized in the cell periplasm (a region between the inner cytoplasmic and outer membranes). Thus when G2P is cleaved and glycerol produced, the nutrient can be stored by the bacterium or released into the external environment, where it will be promptly taken up by the many wild-type (non-mutant) bacteria in the vicinity.

However, the glycerol released by mutants is not sufficient for colonies of wild-type bacteria to grow. Some 20,000 bacteria can be found in the vicinity of every mutant. "The few mutants that succeed in multiplying are those that cooperate with each other to form clusters and swap glycerol. Otherwise, the nutrient becomes scarce, mutants are inhibited, and the population dies out," Spira said.

Wild-type and mutant bacteria normally compete for insufficient glycerol. "Mutants don't multiply owing to the scarcity of this nutrient, creating the impression that there are no mutations and drastically reducing the frequency of PHO-constitutive mutants in the population," he said.

Inhibition of PHO-constitutive mutants, therefore, is an example of mutation frequency masked by competition between mutants and their ancestral wild-type cells. "The example shows that cases similar to a 'tragedy of the commons' may occur in other settings and should be taken into consideration when mutation rates are estimated," he said.

University of Texas at Dallas chemist Dr. Jie Zheng has spent much of his career investigating gold nanoparticles for their potential impact in the field of nanomedicine. In new research, he and his colleagues show how these nanoparticles could play a key role in a simple blood test to detect acute liver damage earlier than current methods.

The study, published online Feb. 19 in the journal Science Advances, expands on corresponding author Zheng's work, which has previously demonstrated the use of nanoparticles for targeted delivery of cancer drugs and better understanding of kidney disease.

"Our goal is to make it simple for family doctors to easily catch liver injury earlier. If they can detect and treat such injury earlier, the patient has a better chance of faster recovery," said Zheng, professor of chemistry and biochemistry and the Cecil H. and Ida Green Professor in Systems Biology Science in the School of Natural Sciences and Mathematics.

The gold standard for monitoring and diagnosing liver disease is a liver biopsy, which is invasive and can be painful or cause complications. In a clinical setting, physicians also can monitor liver function noninvasively with tests that record levels of certain enzymes and proteins in the blood, such as alanine aminotransferase (ALT) and aspartate aminotransferase (AST), which are released by liver cells, or hepatocytes, when the organ is damaged.

"Conventional blood biomarkers like ALT and AST are released when hepatocytes die -- the damage has already been done," Zheng said. "Another drawback to these tests is that other factors, such as inflammation, can cause these biomarkers to be abnormally high. Because of this, in many cases, clinicians may not intervene right away. That creates a problem because it can delay detection and treatment of liver injury."

Targeting Key Antioxidant

In the study, which was conducted in mice, Zheng and his colleagues focused on a chemical called glutathione, which is the master antioxidant produced by the liver. The constant release, or efflux, of glutathione by hepatocytes helps maintain the detoxification function of a healthy liver. When the liver is damaged, however, glutathione production is blocked.

"Glutathione depletion has been found to strongly correlate with an increased risk of many liver diseases, including drug-induced liver injury, alcohol-related and nonalcoholic fatty liver diseases, liver fibrosis and cirrhosis," Zheng said. "People have been studying glutathione for decades, but it's not easy to monitor noninvasively."

Noninvasive monitoring of glutathione has proved difficult because the biomolecule is diluted nearly three orders of magnitude once it enters the bloodstream, and it is rapidly consumed by other organs and cleared quickly by the kidneys.

Zheng and his colleagues combined their expertise with gold nanoparticles with the behavior of glutathione to develop their nanoprobe for acute liver injury, which they then tested in mice. They began by chemically connecting -- or conjugating -- onto gold nanoparticles an organic fluorescent dye called indocyanine green (ICG), which has widespread clinical use.

"Because of this conjugation, the ICG molecules do not fluoresce. The gold nanoparticles carry the dye specifically to the liver. The beauty of this work is that the probe can be selectively activated in the liver at high specificity," Zheng said.

The researchers injected conjugated gold nanoparticles into mice that had been given an excessive dose of acetaminophen (APAP). Overdose of acetaminophen, also known by the brand name Tylenol, is one of the most common causes of drug-induced liver injury and the most common cause of acute liver failure in the U.S.

Tracking Toxicity

Once the nanoparticles reached a part of the liver called the sinusoid, glutathione molecules knocked ICG molecules off the gold nanoparticles and took their place.

"Remember, when liver cells are injured, glutathione efflux is significantly reduced; therefore, you have fewer glutathione and more ICG molecules remaining on the gold particles' surfaces," Zheng said.

The gold nanoparticles returned to the bloodstream fairly quickly. Within about half an hour, the researchers were able to detect glutathione depletion in a small amount of blood.

"A simple blood test shows how much ICG is left on the surface of the gold particles," Zheng said. "The more ICG that remains, the less glutathione in the liver, which directly correlates to liver damage. Our particle was able to detect APAP overdose with 93% accuracy, which is very high. And it's at a stage that is much earlier than traditional biomarkers can detect."

Dr. William Lee, professor of internal medicine at UT Southwestern Medical Center, is a co-author of the study and one of the world's leading experts on acute liver failure and acetaminophen toxicity in the liver. Lee has been site investigator for four networks sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK): the Hepatitis C Antiviral Long-Term Treatment Against Cirrhosis (HALT-C) Trial, the Acute Liver Failure Study Group, the Drug-Induced Liver Injury Network and the Hepatitis B Research Network.

"Glutathione flux is at the heart of acetaminophen metabolism, and Dr. Zheng's new method of tracking glutathione is a big step forward in our ability to understand and prevent acetaminophen toxicity," Lee said.

Dr. Neil Kaplowitz, professor of medicine and chief of the gastroenterology and liver diseases at the Keck School of Medicine of the University of Southern California, who was not involved in the study, said: "The study authors developed a novel approach to dynamic assessment of the status of glutathione in the liver sinusoids. Their technological advance shows that they can image sinusoidal blood glutathione or measure this indicator of sinusoidal plasma glutathione specifically in collected peripheral blood, which accurately reflects the amount of glutathione in liver cells."

While the current study was focused on drug-induced, acute liver injury, Zheng said future work will further deepen fundamental understanding of liver-nanoparticle interactions, continue improving the test's sensitivity and accuracy, and extend the technology to help detect chronic liver injury as well. He said the research is an exciting extension of his previous efforts to develop nanomedicines that are easily cleared from the body.

"I spent much of my career developing clearable nanomedicines for treating conditions like cancer or kidney disease, and this new research is a big breakthrough," Zheng said. "We think our new work could lead to a clearable nanomedicine that can help detect liver injury much earlier with a simple blood test, and that could help a lot of people."

Material behaviors depend on many things including not just the composition of the material but also the arrangement of its molecular parts. For the first time, researchers have found a way to coax carbon nanotubes into creating moiré patterns. Such structures could be useful in materials research, in particular in the field of superconducting materials.

Professor Hiroyuki Isobe from the Department of Chemistry at the University of Tokyo, and his team create nanoscopic material structures, primarily from carbon. Their aim is to explore new ways to create carbon nanostructures and to find useful applications for them. The most recent breakthrough from their lab is a new form of carbon nanotube with a very specific arrangement of atoms that has attracted much attention in the field of nanomaterials.

"We successfully created different kinds of atom-thick carbon nanotubes which self-assemble into complex structures," said Isobe. "These nanotubes are made from rolled up sheets of carbon atoms arranged hexagonally. We made wide ones and narrow ones which fit inside them. This means the resulting complex tube structure has a double-layered wall. The hexagonal patterns of these layers are offset such that the two layers together create what is known as a moiré pattern. And this is significant for materials researchers."

You may see moiré patterns in your everyday life. When repeating patterns overlay one another a new resultant pattern emerges. If you then move one of the layers, or if you move relative to the layers, this resultant pattern will change slightly. For example, if you look at a screen door through a mesh curtain, or if you hold two sieves together. In the case of the team's moiré patterns, they are made when one hexagonal grid of carbon atoms is rotated slightly relative to another similar hexagonal grid.

These patterns aren't just for show, they can imbue materials with functional properties. Two areas that might especially benefit from the properties created here are synthetic chemistry, as the moiré carbon bilayer tubes could be challenging yet attractive targets of molecular self-assembly, and superconducting materials, which could lead to a generational leap in electrical devices which require far less power to run and would be far more capable than current devices.

The human brain is less accessible than other organs because it is covered by a thick, hard skull. As a result, researches have been limited to low-resolution imaging or analysis of brain signals measured outside the skull. This has proved to be a major hindrance in brain research, including research on the different developmental stages, causes of diseases, and their treatments. Recently, studies have been performed using primary neurons from rats or human-derived *induced pluripotent stem cells (iPSCs) to create artificial brain models that have been applied to investigate brain developmental processes and the causes of brain diseases. These studies are expected to play a key role to unlocking the mysteries of the brain.

* iPSCs are stem cells made capable of differentiating into diverse organs, like embryonic stem cells, by injecting differentiation-inducing proteins into somatic cells, such as adult skin cells.

In the past, artificial brain models were created and studied in 2D; however, in 2017, a research team from KIST developed a 3D artificial brain model that more closely resembled the real brain. Unfortunately, due to the absence of an analytical framework for studying signals in a 3D brain model, studies were limited to analyses of surface signals or had to reform the 3D structure to a flat shape. As such, tracking neural signals in a complex, interconnected artificial network remained a challenge.

The Korea Institute of Science and Technology (KIST) announced that the research teams of Doctors Il-Joo Cho and Nakwon Choi have developed a analysis system that can apply precise non-destructive stimuli to a 3D artificial neural circuit and measure neural signals in real-time from multiple locations inside the model at the cellular level.

The 3D multifunctional system for measuring neural signals is in the form of a 50μm-wide needel shaped silicon probe array (about half the width of a human hair) integrated with 63 microelectrodes. When this system is inserted in the artificial brain model, it is capable of simultaneously measuring signals from multiple locations inside the neural circuit. The probe contains an optical fiber and drug-delivery channels, enabling precise stimulation of neurons using light or drugs. By measuring functional changes in the brain model in response to these stimuli, the model can be used to study brain function and brain diseases.

Using this system to stimulate neural circuits in the artificial brain model optically and simultaneously measure the spread of the response signal in multiple locations, the research team demonstrated that the propagation speed of neural signals were different according to directions inside the 3D brain modeln. In addition to **structural brain maps, which can be constructed using electron microscopy, this study demonstrated the possibility of constructing 3D ***functional brain maps that show how different circuits are functionally connected within complex artificial brain networks.

**Structural brain map: A map showing the physical connections between brain cells or brain regions.
***Functional brain map: A map showing the connections between neurons or regions that exchange signals to perform specific brain functions.

Dr. Choi, from KIST, stated that, "The newly developed system allows us to study various developmental brain disorders and the causes of and treatments for brain diseases." Co-PI Dr. Cho added, "This system enables functional measurements from 3D artificial brain models, which was previously impossible. We expect that the development of this system will help to radically reduce the time required to develop drug or treatments for various brain diseases."