Brain

GAINESVILLE, Fla. --- According to a well-studied but controversial principle known as Bergmann's Rule, species tend to be larger in cold climates and smaller in warm ones. As human impacts heat the planet, will animals shrink over time?

To test this, a new study, published today in Scientific Reports, analyzed 70 years of records of the North American deer mouse, Peromyscus maniculatus, arguably the most common and best-documented mammal in the U.S.

Unexpectedly, researchers found deer mice are generally decreasing in mass over time, but this trend may not be linked to changes in climate or human population density, a proxy for urbanization. In another surprise finding, larger-bodied deer mouse populations are getting smaller and smaller-bodied populations are getting larger.

"The most exciting aspect of this study was one that still remains mysterious - deer mice appear to be getting smaller over time, but it doesn't seem to directly relate to climatic drivers or urbanization," said study co-lead author Robert Guralnick, curator of bioinformatics at the Florida Museum of Natural History. "Is this generally true for mammals?"

Why study body-size trends in the first place? Body size is a particularly important physical characteristic in warm-blooded animals because it helps maintain the right body temperature for biological functions such as metabolism and heat transfer.

"Even in a small mammal like this, a minor change in body mass could have really important consequences for optimizing those energy balances," said study co-author Bryan McLean, assistant professor at the University of North Carolina Greensboro and a former postdoctoral fellow researcher at the Florida Museum.

Larger-bodied animals have less body surface - which releases heat - relative to the volume of their bodies, so they may cope with the cold better than their smaller-bodied kin, the thermodynamic foundation of Bergmann's Rule. Because body size affects thermoregulation, changes in body size could influence animals' resilience to climate change.

To examine changes in the deer mouse's body size in relation to space, time, climate and human population density, Guralnick and his collaborators turned to three sources of data: museum collections, the "North American Census of Small Mammals" and the National Ecological Observatory Network, known as NEON. Using these resources, they compiled body length and mass measurements taken by thousands of researchers across the U.S. over seven decades. The result? A certifiable time machine to observe these mice throughout recent history and the first study of body-size trends in mammals that combines data from published surveys and museum collections.

"I don't think anyone has combined museum data with NEON data and historical data like we have. We have such a larger dataset because of this," said study co-lead author Maggie Hantak, a postdoctoral researcher at the Florida Museum. "It's a really novel way to see how body size is changing over space and time."

Their findings indicate deer mice in colder climates tend to be longer and have bigger body mass, consistent with Bergmann's Rule. As temperature changed across space, deer mice body mass decreased, which also aligned with the researchers' hypothesis. As precipitation increased, however, researchers expected an increase in mouse body mass due to the boost rainfall can give to foraging resources. Instead, body mass also decreased.

The findings were more complicated in cities: Urban areas are significantly warmer than the surrounding rural landscape, a phenomenon known as the urban heat island effect. According to Bergmann's Rule, mice should be smaller in urban areas to beat the heat. But since human food and garbage abound in cities, mice could grow larger by tapping into that constant supply of fuel.

The data showed that as human population density increased, deer mice populations tended to retain the same body mass, but grow shorter in length. This could mean the urban heat island effect trumps the benefit of endless food resources - or simply that shorter mice are better at hiding from humans.

But the real head-scratcher came when the team decoupled mouse mass from all of these factors. They still noted a general decrease in mass over time, hinting that the roles of climate and urbanization in influencing body size may be more complicated than previously thought.

"Preliminarily, this is very intriguing, but we still don't know what drives this decrease in mass," Guralnick said.

The team will now turn its attention to analyzing body size across all mammals, he said.

"One big question is what the future will look like for mammals across the planet, and the way we're going to know best is by knowing what's happened in the past," Guralnick said. "Natural history collections and their data are excellent ways for us to get a comprehensive, often broad, view of change. Body size is a hugely important variable, and it's one that's recorded in literally millions of specimen records."

In the periodic table of elements there is one golden rule for carbon, oxygen, and other light elements. Under high pressures they have similar structures to heavier elements in the same group of elements. Only nitrogen always seemed unwilling to toe the line. However, high-pressure researchers of the University of Bayreuth have actually disproved this special status. Out of nitrogen, they have created a crystalline structure which under normal conditions occurs in black phosphorus and arsenic. The structure contains two-dimensional atomic layers, and is therefore of great interest for high-tech electronics. The scientists have presented this "black nitrogen" in "Physical Review Letters".

Nitrogen - an exception in the periodic system?

When you arrange the chemical elements in ascending order according to their number of protons, and look at their properties, it soon becomes obvious that certain properties recur at large intervals ("periods"). The periodic table of elements brings these repetitions into focus. Elements with similar properties are placed one below the other in the same column, and thus form a group of elements. At the top of a column is the element that has the fewest protons and the lowest weight compared to the other group members. Nitrogen heads element group 15, but was previously considered the "black sheep" of the group. The reason: in earlier high-pressure experiments, nitrogen showed no structures similar to those the heavier elements of this group - especially phosphorus, arsenic, and antimony - exhibit under normal conditions. Instead, exactly this kind of similarities could be observed at high pressures in the neighbouring groups headed by carbon and oxygen.

Black nitrogen - a high-pressure material with technologically attractive properties

In fact, nitrogen is no exception after all. Researchers at the Bavarian Research Institute of Experimental Geochemistry & Geophysics (BGI) and the Laboratory for Crystallography at the University of Bayreuth have now been able to prove this with the help of a measuring method they recently developed. Under the leadership of Dr. Dominique Laniel, they have made an unusual discovery. At very high pressures and temperatures, nitrogen atoms form a crystalline structure that is characteristic of black phosphorus, which is a particular variant of phosphorus. It also occurs in arsenic and antimony. This structure is composed of two-dimensional layers in which nitrogen atoms are cross-linked in a uniform zigzag pattern. In terms of their conductive properties, these 2D layers are similar to graphene, which shows great promise as a material for high-tech applications. Therefore, black phosphorus is currently being studied for its potential as a material for highly efficient transistors, semiconductors, and other electronic components in the future.

The Bayreuth researchers are proposing an analogous name for the allotrope of nitrogen they have discovered: black nitrogen. Some technologically attractive properties, in particular its directional dependence (anisotropy), are even more pronounced than in black phosphorus. However, black nitrogen can only exist thanks to the exceptional pressure and temperature conditions under which it is produced in the laboratory. Under normal conditions it dissolves immediately. "Because of this instability, industrial applications are currently not feasible. Nevertheless, nitrogen remains a highly interesting element in materials research. Our study shows by way of example that high pressures and temperatures can produce material structures and properties that researchers previously did not know existed," says Laniel.

Determining structure with particle accelerators

It took truly extreme conditions to produce black nitrogen. The compression pressure was 1.4 million times the pressure of the Earth's atmosphere, and the temperature exceeded 4,000 degrees Celsius. To find out how atoms arrange themselves under these conditions, the Bayreuth scientists cooperated with the German Electron Synchrotron (DESY) in Hamburg and the Advanced Photon Source (APS) at the Argonne National Laboratory in the USA. Here, X-rays generated by particle acceleration were fired at the compressed samples. "We were surprised and intrigued by the measurement data suddenly providing us with a structure characteristic of black phosphorus. Further experiments and calculations have since confirmed this finding. This means there is no doubt about it: nitrogen is, in fact, not an exceptional element, but follows the same golden rule of the periodic table as carbon and oxygen do," says Laniel, who came to the University of Bayreuth in 2019 as an Alexander von Humboldt Foundation research fellow.

A key atomic building block for all living organisms and one of the most abundant elements in the galaxy, nitrogen is an essential part of our ecosystem. But for our ecosystem to function, nitrogen-based compounds must cycle through air, water, and soil in a delicate balance among the other organic chemical drivers of life.

Human activity significantly disrupts the natural balance of nitrogen, posing a threat to the health of both terrestrial and aquatic life. Bearing that in mind, Atmospheric and Oceanic Science Letters (AOSL) published a special issue on May 21, 2020 dedicated to the topic, bringing together a collection of 13 papers that explore the cascading consequences of rising levels of nitrogen in circulation.

The biggest human driver of nitrogen emissions into the air is food production. The global agriculture sector depends on ammonia-based fertilizers to prime the soil each season to grow new crops. Rain and artificial irrigation sweep much of the nitrogen-based fertilizer away, landing it in lakes and oceans, doing damage to aquatic ecosystems.

Biofuels and fossil fuels combustion also release enormous amounts of nitrogen into the atmosphere. Controlled burns to prepare land for crop farming, also known as biomass burning, leads to a host of quality of life issues, one of the most notable of which is the visible reddish haze urban dwellers refer to as 'smog'. Atmospheric nitrogen is eventually returned to land via rainstorms, but emissions often far outpace the Earth's natural ability to cleanse the air. That ongoing cycle of excess nitrogen continues to drive the trend of reduced biodiversity, especially in oceans.

Yuepeng Pan, Ph.D, AOSL editor and scientist with Institute of Atmospheric Physics at Chinese Academy of Sciences, said the special issue titled "Reactive nitrogen in the air: Emissions, Process, Deposition and Impacts" advances the scientific community's understanding of atmospheric transport of nitrogen and all its consequences. "It is imperative that we continue to better understand the flow of nitrogen compounds in and out of the atmosphere so policymakers can deliver more effective interventions," Pan said.

The AOSL series suggests that a next generation of studies on nitrogen deposition should further consider the impact of ammonia, considering increasing emissions from livestock waste, fertilizers, and fossil fuel combustions. Previous papers derived their data mostly from field experiments involving spraying nitrogen solution onto soils and thus largely ignored the direct impacts of ammonia.

Though top emitter China has succeeded in decreasing nitrogen output over the last five years, worldwide emissions continue to grow. That, Dr. Pan says, is cause for concern among the scientific community. Without further research and actionable interventions, more damage to ecosystems will likely occur. "We've set the stage for further global research collaboration on this urgent issue," Pan said.

An immunotherapy drug called 'avelumab' has been shown to significantly improve survival in patients with the most common type of bladder cancer, according to results from a phase III clinical trial led by Professor Tom Powles from Queen Mary University of London and Barts Cancer Centre, UK.

This is the first time an immune therapy has resulted in a survival advantage in this setting in bladder cancer, and will potentially benefit thousands of patients each year.

The results will be presented in the plenary session at the American Society of Clinical Oncology, the world's largest annual cancer meeting (ASCO20). They found that avelumab led to a 31 per cent reduction in risk of death of bladder cancer and extended median survival in advanced bladder cancer by more than seven months.

Approximately 550,000 new cases of bladder cancer are diagnosed each year (10,200 of which are in the UK), making it the tenth most common cancer worldwide. This trial focused on the group of these patients whose cancer had spread beyond the bladder (advanced or stage 4 disease), which is difficult to treat.

Chemotherapy is the current initial standard of care in the treatment of these advanced cancers. After chemotherapy is finished, patients are checked regularly because the cancer tends to return quickly. When it returns it is difficult to treat and outcomes are poor.

The phase III global trial, named JAVELIN Bladder 100 and funded by Pfizer and Merck KGaA Darmstadt, Germany, evaluated the efficacy of the immunotherapy drug 'avelumab' in patients with locally advanced or metastatic urothelial carcinoma which they received after the initial chemotherapy.

A total of 700 patients from over 200 sites around the world were then assigned to two treatment groups after the completion of chemotherapy - one group receiving regular checking (standard care) on its own, and the other receiving avelumab in addition to standard care.

Treatment with avelumab resulted in a 31 per cent reduction in risk of death and median overall survival of 21.4 months compared with 14.3 months in patients who did not receive the drug. Side effects were in line with expectations with immune therapy and 11 per cent of patients stopped avelumab due to treatment problems.

Study lead Thomas Powles, Professor of Genitourinary Oncology at Queen Mary University of London, and Director of Barts Cancer Centre, Barts Health NHS Trust, said: "This is the first time that an immune therapy clinical trial has shown a survival benefit for first-line therapy in metastatic bladder cancer.

"We saw a meaningful reduction in the risk of death and a significant overall survival benefit with avelumab, which underscores the potential for this immunotherapy to be practice-changing for patients. This highlights the potential benefits of a maintenance approach with avelumab in patients to prolong their lives following chemotherapy."

Avelumab is a type of immunotherapy, known as a checkpoint inhibitor, which blocks a protein called PD-L1 on the surface of tumour cells. When PD-L1 is active it helps cancers hide from the immune system. By blocking PD-L1 the immune system finds it easier to identify and kill the cancer.

Different human tumor types each harbor their own unique bacterial communities, researchers report in a new study that profiled the microbiomes of more than 1,500 individual tumors across seven types of human cancer - the most comprehensive tumor microbiome study to date. It has long been known that bacteria are present in tumors that originate from tissues routinely exposed to microbes (e.g., the gastrointestinal tract) but whether they are present in tumors arising from "sterile" tissues has been less clear. Deborah Nejman and colleagues collected over 1,500 tumor samples and samples of adjacent normal tissue from nine medical centers in four countries. The samples included melanoma, bone and brain cancer, tumor types whose association with bacteria had not previously been explored. Applying a variety of methods to detect bacterial DNA, RNA and protein, and taking rigorous measures to exclude contamination, they found that most tumors and their adjacent normal tissues harbor bacteria. Different tumor types had distinct microbiomes, with breast tumors displaying a particularly rich and diverse community of bacteria. What's more, the authors found that bacteria within the tumors were present in both cancer cells and immune cells. While there were intriguing associations between specific species of intra-tumor bacteria and factors such as patient smoking status, further work will be required to determine whether and how intratumor bacteria contribute to tumor development, progression, and response to therapy. "Achieving a comprehensive understanding of the tumor microenvironment is a daunting yet critical step toward an organism-wide mechanistic model of cancer progression and, if successful, may unlock the next wave of precision cancer diagnostics and therapeutics," write Chloe Atreya and Peter Turnbaugh in a related Perspective.

What The Study Did: Patients with COVID-19 who were discharged from the hospital and had recurrent positive reverse transcriptase-polymerase chain reaction (RT-PCR) results were the focus of this case series.

Authors: Zhixia Jiang, M.S., of the Affiliated Hospital of Zunyi Medical University in Zunyi, China, is the corresponding author.

To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/

(doi:10.1001/jamanetworkopen.2020.10475)

Editor's Note: Please see the article for additional information, including other authors, author contributions and affiliations, conflicts of interest and financial disclosures, and funding and support.

Opioids regulate the feelings of pleasure and pain in the brain. A study by the national Turku PET Centre in Finland shows that age, sex and smoking influence μ-opioid receptor density in the brain. The results of the study help to better understand the differences between individuals when it comes to neuropsychiatric disorders.

Dysfunctions of the brain's opioid system are associated with several disorders, such as addiction, and chronic pain problems.

- We noticed in our study that age, sex and smoking have fundamental influence on the organisation of the human brain's opioid system. This suggests that there are significant differences in the opioid system between individuals, which may explain why some individuals are prone to develop opioid-linked pathological states, such as psychiatric disorders, explains Tatu Kantonen, Doctor of Medicine.

Brain's μ-opioid receptors act as important mediators for body's own opioids in the brain. This study analysed positron emission tomography (PET) brain scans targeting μ-opioid receptors from 204 individuals with no neurologic or psychiatric disorders. This database was compiled with new computational tools developed at the Turku PET Centre.

- When an opioid molecule binds to a dock-like receptor in the brain, it may cause a feeling of reduced pain or increased pleasure. Putting it more simply, opioids are like the body's own ambassadors of pleasure and relief, explains Kantonen.

Older age was associated with increased μ-opioid receptors in the cerebral cortex, whereas in the deeper parts of the brain they were decreased. The increase in receptors was stronger in males. Smoking was associated with decreased μ-opioid receptors in most brain regions.

The researchers also discovered that there are more μ-opioid receptors in the right versus the left hemisphere of the brain. This observation may help to explain the previously reported differences between the two hemispheres in the processing of emotions and pain.

(Philadelphia, PA) - The main thoroughfare that carries oxygen-rich blood from the heart to the abdomen is known as the abdominal aorta. Strong and thick-walled, this main highway is built to withstand a lifetime of use. But just like expressways traveled by cars and trucks, too much force on its surfaces and exposure to certain environmental factors can cause the vessel to wear and weaken over time - weakening that can lead to abdominal aortic aneurysm (AAA), a bulge in the aorta wall that has a high risk of rupturing.

Risk of AAA is high in smokers, particularly men over age 50, and there is no cure. Long-term survival is poor, especially for patients with large aneurysms and for those who are not able to undergo surgery to prevent eventual rupture.

But now, new research by scientists at the Lewis Katz School of Medicine at Temple University (LKSOM) suggests that AAA can be prevented therapeutically. In work published online May 28 in the journal Cardiovascular Research, they show for the first time in animals that blocking a molecule known as dynamin-related protein 1 (Drp1) can stop AAA from developing.

"While the molecular mechanism of AAA has been unknown, we suspected a connection with mitochondria, which supply cells with energy," explained Satoru Eguchi, MD, PhD, FAHA, Professor of Physiology and Professor in the Cardiovascular Research Center, Sol Sherry Thrombosis Research Center, and Center for Metabolic Disease Research at LKSOM. "We were interested especially in how processes called mitochondrial fission and fusion impact AAA."

Fission and fusion are normal processes by which mitochondria divide and recombine to maintain their function. But blood vessel inflammation, which can be caused by smoking, aging, and other factors, causes mitochondria to shift toward fission. This harmful fragmentation process, which is regulated by Drp1, severely compromises the integrity of the aortic thoroughfare - like the subsurface of an expressway crumbling.

Dr. Eguchi and colleagues, including Hannah A. Cooper, an MD, PhD student in Dr. Eguchi's laboratory at the Cardiovascular Research Center and lead author on the new paper, and collaborators at Okayama University in Japan, observed elevated Drp1 levels in the abdominal aortas of human patients with AAA. They also observed similar Drp1 increases in AAA tissues from mice engineered to develop the condition.

To investigate the significance of elevated Drp1, the researchers treated AAA mice with a compound called mdivi1, which acts as a Drp1 inhibitor. Mdivi1 turned out to attenuate AAA development, based on measurement of the diameter of the abdominal aorta and on molecular study of vascular smooth muscle cells. While treated mice still had high blood pressure associated with their condition, mdivi1 completely protected them against aortic rupture.

Drp1 inhibition was further associated with reduced stress responses in vascular cells. These responses included reduced infiltration of inflammatory cells and decreased senescence, which is characterized by aging-related cellular deterioration.

Dr. Eguchi thinks senescence may be a driving factor behind AAA. Mitochondrial fragmentation accompanied by decreased mitochondrial function and accelerated vascular aging set the stage for increased premature senescence and senescence-associated secretory phenotype (SASP), an aging-related chronic inflammatory condition.

"Human patients and animals with AAA appear young on the outside, but their vascular systems typically show significant aging," Dr. Eguchi said. "Maintaining the mitochondrial fission-fusion balance appears to be fundamental to attenuating senescence and having healthy cardiovascular function. A Drp1 inhibitor may be the therapeutic answer to achieving this goal for persons at risk of AAA."

In future work, Dr. Eguchi and colleagues plan to more deeply explore the mechanisms involved in Drp1-mediated mitochondrial fission and fusion and how they tie into AAA and other cardiovascular diseases.

Capable school graduates sometimes choose low-ranking universities which do not match their abilities. According to the findings of HSE University researchers, up to one-quarter of school graduates in Moscow enrol in low-quality universities despite scoring highly on their USE (Unified State Exam, the final school exam and a standard university admission mechanism in Russia). This academic mismatch limits their life opportunities and often stems from unequal starting conditions in the family and at school. Parents without a university education are not always aware of the difference in quality among universities and therefore cannot give useful advice to their children. Non-elite secondary schools do not normally provide vocational guidance or discuss university admission options with students. As a result, many top academic performers from less privileged families and schools do not even attempt to enrol in high-ranking universities.

Inequality Starts Early

Generally, the USE system lives up to its promise of expanding access to higher education. However, inequality persists due to students' family and school backgrounds. Limiting attitudes projected by their parents and teachers often prevent school graduates from making the right decision: those who could boost their upward social mobility by entering a prestigious university often do not even consider this option.

Having monitored enrolment in Moscow universities for the correlation between students' academic ability and the ranking of universities they choose, researchers found a significant mismatch: up to 28% of students chose a university below the level that they deserved based on their USE score. This finding is striking, given that students in Moscow enjoy 'the widest range of options for entering Moscow-based universities; unlike aspiring students from the provinces, Muscovites do not need to relocate to attend the university of their choice', says the study co-author Ilya Prakhov https://www.hse.ru/en/staff/prakhov.

In the regions, the rate of mismatch between the academic potential of students and the quality of universities they choose may be even higher. Not many aspiring students take the risk of applying to a university in another city. Educational migration is constrained by what the student's family can afford; local living standards also play a role, as regions with growing economies and good job opportunities are more likely to retain young people.

This new research is based on a sample of 718 observations from the HSE's Trajectories in Education and Careers longitudinal study (Moscow panel). The researchers compared individual students' USE scores in the school subjects required for university admission against the quality of enrolment for their chosen university, i.e. the average USE score of all students admitted to subsidised slots in this university. A positive difference between a student's USE score and the average USE score of all students attending their university indicates an undermatch, i.e. a choice of university below the student's ability.

How Can You Tell That Your Child Has Undermatched?

Suppose your son scored 75 in Russian, 85 in Mathematics and 80 in Physics, giving an average USE score of 80. Suppose further that the average USE score of students attending his university ranges between 65 and 75, averaging 70. By subtracting the university average from your son's USE score, you can see that he has undermatched by 10 points (80-70=10) and could have entered a higher-quality university where the students' average USE score is 80.

While undermatching, according to Prakhov, 'only affects one-quarter of school graduates, inequality in access to higher education can occur at earlier stages in secondary school, because USE scores often depend on family and school characteristics'.

Doomed by Parents

A key factor in undermatching is family influence. It was proven more than half a century ago that family background has a powerful impact on children's education.

Parents' socioeconomic status (SES) -- their level of education, income and cultural involvement -- tends to 'program' their child's path in life. The family largely determines a youngster's achievements in school and their desire or reluctance to graduate from high school and pursue higher education.

Parents can underestimate their children's abilities and discourage attempts to pursue higher education - or suggest less prestigious universities which are easier to enter. This often happens to students from poorer and less educated families. Not having first-hand experience of studying at a university, parents may not have enough information on preparation and enrolment to provide proper guidance to children. This situation hinders intergenerational mobility and causes children to follow the path of their parents and fail to improve their socioeconomic status.

Termed parentocracy by social scientists, this creates a system where parents, voluntarily or otherwise, determine the future of their offspring based on the family's socioeconomic background and attitudes rather than the child's individual abilities and achievements.

In addition to this, according to Prakhov, a student's family can affect their USE results, since 'a lack of parental investment in the child's human capital (knowledge and skills) tends to limit the latter's academic achievement'.

In contrast, young people from high-status families are at an advantage and far less likely to undermatch. This finding is confirmed by other studies stating that children from families with high professional and educational status are twice as likely to enter a prestigious university as their peers from low-resource families.

Researchers explain this through three family-related factors: strong family attitudes towards a good education, parental investment in their children's studies and the child's high academic performance associated with it. Awareness of available higher education options also makes a difference: it has been found that more informed students are less likely to attend low-quality educational institutions.

Power of Money and Knowledge

Parents with high socioeconomic status are prepared to hire private tutors and pay for university preparation courses for their child. By contributing to students' academic performance and confidence, this additional learning helps them score better on the USE, understand their options and avoid undermatching. According to Prakhov and Sergienko, high-priced 'intensive' courses and high-quality tutors ensure an almost perfect match between student and university.

A family's culture is often measured by the number of books in the home library. 'Books are an essential resource for investment in human capital', the researchers comment. 'In a home with lots of books, a curious child is far more likely to take one from the shelf and read it'. Students who read many books are less likely to enter a low-quality university. Indeed, as far as family factors are concerned, inequality in access to education begins long before university, with the bookshelf in one's parental home.

School as Sorting Machine

Not only family, but school also contributes to inequalities in students' choice of educational path and resulting prospects in life. Quite often, the educational path is decided from the first grade, with more affluent families choosing prestigious lyceums and gymnasiums for their children, and families with limited means choosing schools near their home. Both choices can determine the child's future, especially given that Russian students rarely switch schools, and many stay in the same school until graduation.

Tracking, or selecting a particular academic track and perhaps switching to a certain type of school (e.g. one with a focus on mathematics or foreign languages, etc.), normally occurs in high school and is often linked to families' socioeconomic status, with less resourced families choosing ordinary rather than elite schools. In a few countries, tracking takes place earlier: Germany and Austria assign children to specific tracks at age 10, and Russia is the world leader for pre-tracking, with educational paths determined at the age of six or seven.

Public education effectively perpetuates existing social inequalities, where children of wealthier parents benefit from the best school and university education. According to Prakhov and his co-author Denis Sergienko, graduates of the 300 top-ranking secondary schools in Moscow are less likely than others to undermatch with their chosen university. 'Attending an elite rather than ordinary school contributes significantly to the student's USE score and reduces the risk of undermatching', the researchers emphasise.

Also important is the quality of teaching. Good teachers know how to support their students' motivation and confidence. It has been found that teachers who hold their students to high standards help them develop higher self-esteem.

In Search of a Solution

What then needs to be done to help all aspiring undergraduates make the most of their academic ability and performance? According to experts, schools and families should work together to change the attitudes and improve the knowledge of low-SES parents. Steps need to be taken to minimise the limiting influence of parental background on the choice of educational path for their children.

The attitudes of some schools which tend to be biased against children from low-SES families should also be addressed. It has been shown that teachers and school administrators sometimes perceive parents' low level of education as a signal that their children's educational aspirations are also low, and such students are not given sufficient attention. According to Prakhov and Sergienko, improving teacher performance in non-elite schools could increase the chances of success for their students.

Schools could also offer elective classes focusing specifically on preparation for the USE, for the benefit of low-income students. And finally, students need to be informed and updated on available options of university enrolment and the overall situation in the educational market.

After a severe drought gripped the Prairie Pothole Region of the U.S. and Canada in the 1980s, populations of almost all dabbling duck species that breed there have recovered. But not northern pintails. Now, a new study by a team of researchers suggests why -- they have been caught in an ecological trap.

The Prairie Pothole region straddles the U.S.-Canada border and sprawls from central Iowa in the south to Alberta in the north, covering a large swath of Minnesota, South Dakota, North Dakota, Manitoba and Saskatchewan in between.

"With increasing cropland cover in the region, pintails have been selecting for cropland over scarce alternative nesting habitat, probably because it is similar to the native mixed-grass prairie they evolved to nest in," said lead researcher Frances Buderman, Penn State. "That behavior results in fewer pintails the following year due to nest failures from predation and agricultural practices."

The U.S. Fish and Wildlife Service's North American Waterfowl Management Plan calls for more than 4 million pintails, but recent estimates are only half of that. The reason pintails are not thriving like other dabbling ducks, according to Buderman, assistant professor of quantitative wildlife ecology in the College of Agricultural Sciences, is that they are being "misled" by modern cropping methods and climate change into choosing risky nesting habitat.

Also called puddle ducks, dabbling ducks frequent shallow waters such as flooded fields and marshes. They feed by tipping up rather than diving. There are 38 species of dabbling ducks -- they float high in the water and are swift fliers.

By their very nature, pintails may be vulnerable to the ecological trap, Buderman explained. Despite being an early-spring nester -- a quality that typically would allow for reproductive "plasticity" to climatic conditions -- pintails have demonstrated inflexible breeding behavior, such as being unwilling or unable to delay nest initiation and being less likely to renest than most other waterfowl.

"Inflexible breeding behavior may result in greater vulnerability to unpredictable weather events and changes in climactic conditions," she said. And given their preference for nesting among landscapes of grass-like, low-lying cover, pintails readily nest in fields of stubble in untilled agricultural fields. "Unlike other ducks that generally avoid nesting in stubble, pintails in the Prairie Pothole Region commonly select crop stubble nest sites and often select it over remnant patches of grass and other cover."

Pintails often initiate nests before remaining stubble fields are worked by farmers in the spring, making nests vulnerable to mechanical spring tilling and planting of remaining standing stubble, Buderman explained. That can destroy a large percentage of initial nests. Exacerbating the effect of pintail selections over time, the amount of land in the Prairie Pothole Region annually tilled for spring-seeded crops has increased by approximately 34% since 1959.

Dabbling duck incoming

Another factor that is contributing to pintails' decline, researchers contend, is a trend in some areas of the Prairie Pothole Region to manipulate drainage to consolidate surface water into larger and deeper wetlands that dry out less frequently and have more surface-water connections to other wetlands.

Those drainage practices make mowing around ponds easier for farmers, and most waterfowl species have coped thus far, but it hasn't been good for pintails. Wildlife scientists suspect the birds need the smaller, shallower, ephemeral ponds with which they evolved. For reasons not clearly understood, pintails appear to be particularly sensitive to changes in the number of productive, small wetlands that have occurred across the Prairie Pothole Region.

Buderman pointed out that funding partner Delta Waterfowl is working hard to restore these valuable seasonal wetlands on the U.S. side of the region by establishing a Working Wetlands program in the U.S. Department of Agriculture via the federal farm bill.

To reach their conclusions, researchers used more than 60 years of data from the U.S. Fish and Wildlife Service and the Canadian Wildlife Service, which have monitored spring population sizes for North American waterfowl since 1955. They published their results in the Journal of Animal Ecology,

That information is organized into regions that reflect both habitat differences and political boundaries. For many decades, waterfowl have been counted on both sides of the border by aerial crews flying fixed-wing aircraft along established transect lines at low altitude, while simultaneously, ground counts are conducted at ponds on a subset of air-surveyed areas.

To analyze population dynamics, researchers developed a complex model to deal with a huge dataset that took days to run on a powerful computer, which calculated a "breeding pintail count" for the survey period. The model -- which also took into account precipitation, climatic conditions during the breeding season and pond dynamics -- allowed researchers to identify the relative influence of long-term changes in climate and land use on both the selection and quality of habitat for pintails in the Prairie Pothole Region.

BINGHAMTON, N.Y. -- Early exposure to anesthetics may make adolescents more susceptible to developing alcohol use disorder (AUD), according to new research from Binghamton University, State University of New York.

David Werner, associate professor of psychology, and Linda Spear, distinguished professor of psychology, led a team of Binghamton University researchers in examining whether exposure to anesthetics during adolescence could affect a person's response to alcohol in adulthood, especially the development of AUD.

Anesthetics are commonly used drugs in the healthcare field and are often administered to children to induce unconsciousness and immobility during surgeries.

Researchers discovered that anesthetic exposure during adolescence may be an environmental risk factor that leads to an increased susceptibility to developing AUD later in life. Although not all adolescents who drink alcohol develop AUDs, Werner said it's important to identify risk factors that contribute to an increased susceptibility to alcohol abuse.

"This is highly concerning," Werner said. "Given that although the age of initiation and subsequent binging during adolescence are linked to alcoholism later in life, apart from stress, it was not clear what other environmental factors may play a role. This study now highlights a previously overlooked contributor."

To test this, researchers exposed early-adolescent male rats to isoflurane, a general anesthetic, in short durations and tested them on various alcohol-induced behaviors later in adolescence or adulthood.

The team found that exposure to anesthetics in adolescence had extremely similar behavioral and neural effects as adolescent chornic alcohol exposure. During their study, the adolescent rats exposed to isoflurane had a decreased sensitivity to the negative effects of alcohol, such as its aversive, sedative and socially suppressive effects. These rats also showed an increase in voluntary alcohol consumption and cognitive impairment, and certain behaviors continued into adulthood after their initial anesthetic exposure.

These results further suggest that exposure to anesthetics during adolescence, while in some cases is necessary, may have unintended consequences that incubate over time.

"Apart from infancy to early childhood, adolescence can be considered the most critical developmental stage following birth," Werner said. "Given that adolescence is a time-period that most often coincides with initial exposure to drugs of abuse, primarily alcohol, we initially performed a retrospective analysis of alcohol responding to our previous data with regard to adolescents that had experienced a surgical event. Noting a potential difference, we then wanted to empirically test whether or not the relationship between adolescent anesthetic exposure and behaviors linked to alcohol use disorder susceptibility."

Although the use of anesthetics is vital for certain surgeries and can't be avoided, Werner said it's important to know the drug's potential effects.

"Above all, anesthetics are necessary - which obviously is why they are rightfully included in the essential medicines by the World Health Organization," Werner said. "In the event that the health condition of children and adolescents necessitates an operative procedure, then these should absolutely be used. That being said, we hope that this work can be used to inform people, especially younger individuals considering elective procedures that could be delayed into adulthood such as plastic surgery or weight loss procedures, as well as potentially leading to additional screening diagnostics to help identify individuals who may have greater drug use disorder susceptibility."

Werner plans to continue research on this topic and hopes to examine whether the effects from anesthetics are similar to other substances, as well as the underlying molecular mechanisms in the brain and individual differences.

The effect of nitric acid on aerosol particles in the atmosphere may offer an explanation for the smog seen engulfing cities on frosty days. Under laboratory conditions, researchers at CERN in Switzerland observed the formation of atmospheric aerosols and discovered new information on the link between nitrogen oxides, originating in traffic and the energy industry, and the climate and air quality. These findings were published in the Nature and Science Advances journals.

Based on the findings, nitrogen compounds can, depending on the circumstances, either slow down or accelerate the growth of aerosol particles. This means that reducing sulphur dioxide is not on its own enough to prevent the smog problem seen in large cities. Instead, a comprehensive understanding of the atmospheric particle formation process is needed.

Earlier, nitric acid was not thought to have a significant effect on the formation or early growth of aerosol particles, even though nitrate compounds often occur in larger particles. However, the study published in Nature demonstrates that, in cold climates, nitric acid can boost particle growth to a marked degree, and even form particles together with ammonia in temperatures under -15°C. This is significant, as there are up to a thousand times more nitric acid and ammonia than sulphuric acid in the atmosphere.

The discovery could explain why particles are formed even in highly polluted big cities, notwithstanding the established knowledge according to which pollutants should prevent the formation and growth of new particles. The same mechanism may also generate particles higher up in the atmosphere, where the temperature is always cold and nitrogen oxides are produced as a result of lightnings.

At the same time, nitrogen oxides also affect the oxidation characteristics of organic compounds in the atmosphere. In the project headed by University of Helsinki researchers, it was found that nitrogen oxides increase the volatility of the oxidation products of organic compounds. As a result, particle growth slows down and a smaller share of particles survive compared to circumstances where the air is clean. In areas where particle growth is promoted mainly by organic compounds, such as in the boreal forest zone, the phenomenon can reduce the number of aerosols that form clouds, indirectly resulting in warming the climate. This study was published in the Science Advances journal.

Both studies are based on laboratory experiments carried out at CERN, the European Organization for Nuclear Research. The CLOUD chamber at CERN makes it possible to investigate the formation and growth of aerosol particles with unparalleled precision. The Finnish participants in the CLOUD experiments include the University of Helsinki's Institute for Atmospheric and Earth System Research, the Finnish Meteorological Institute and the University of Eastern Finland.

Subduction of hydrous materials imposes great influence on the structure, dynamics, and evolution of our planet. However, it is largely unclear how subducting slabs chemically interact with the middle mantle. Recently, an oxygen-excess phase (Mg,Fe)2O3+δ was discovered under conditions similar to the Earth's middle mantle (~1000-2000 km) by a team of scientists from the Center of High Pressure Science and Technology Advanced Research (HPSTAR) and Stanford University. This oxygen-excess phase is fully recoverable to ambient conditions for ex-situ investigation using transmission electron microscopy. It contains ferric iron as in hematite (Fe2O3) which is the most oxidized form of iron on the Earth's surface, but this new phase holds more oxygen than hematite through interactions between oxygen atoms. The peculiar nature of oxygen in this new phase may revise our view on the mantle redox chemistry.

"We employed laboratory techniques to simulate the conditions deep inside the Earth and found an oxygen-excess phase emerged when hydrous mineral assemblages (e.g., ferropericlase mixed with brucite) were exposed to laser heating at pressures greater than 40 million times the atmospheric pressure on the Earth's surface" said Dr. Jin Liu from HPTAR. "The formation of this new phase provides strong evidence that water acts as a strong oxidant at high pressure."

"This phase could coexist with the pyrite-type phase hydrogen-bearing FeO2 at deep mantle conditions, whereas the two phases are distinct in crystal chemistry" added by Dr. Qingyang Hu from HPSTAR. "Unlike the formation of the pyrite-type phase which usually forms in deep lower mantle and requires a large quantity of water, this oxygen-excess phase can be formed with a moderate amount of water at mid-mantle conditions. The flexible formation conditions make it potentially a more widespread phase at depths greater than 1000 km in Earth's mantle, occupying almost 2/3 of the mantle." Furthermore, this oxygen-excess phase can co-exist with the major mantle minerals, bridgmanite and ferropericlase, under Earth's lower-mantle conditions.

"The wide-spread presence of the oxygen-excess phase makes it and other oxygen-enriched oxides an important subject for the full range of future geochemistry and mineral physics studies" suggested Dr. Ho-kwang Mao, director of HPSTAR. "Remarkably, this new phase is quenchable. As a matter of fact, most compounds synthesized under the lower mantle conditions and quenchable back to ambient conditions have been discovered and named as minerals such as bridgmanite (Mg,Fe)SiO3 and seifertite SiO2. Hence, this presents an opportunity to search for this oxygen excess phase in nature as diamond inclusions or meteorite shock products."

The crystal structure of this oxygen excess phase may represent a structure prototype which will accommodate other Earth-abundant components (e.g. Al, Ca, Ti, and Ni). At the same time, the channel space in this oxygen-excess phase could offer a great flexibility not only for excess oxygen, but also for other volatiles (e.g. N, S, F, and Cl). Considering its structural versatility, the new phase could be an important volatile carrier in the deep mantle over geological time. More importantly, together with excess Fe3+ from the primordial lower mantle, those oxygen-excess materials may have long-termly oxidized the shallow mantle and the crust, which is fundamental to the evolution and habitability of complex life on the Earth's surface.

These results suggest that the oxygen-excess phase may facilitate oxygen-excess reservoirs out of hydrated slab remnants at depths greater than 1000 km. Oceanic crusts in the mid-mantle thus might deeply regulate the rise of oxygen in Earth's atmosphere and global habitability, like shallowly-recycled fluids. Such intriguing chemistry of deep oxygen sheds light on chemical and dynamic models of mantle slab remnants as well as the interaction and coevolution of Earth's interior and surface.

The nanostructure of the heterogeneous Ziegler-Natta catalyst was clarified on the basis of cutting-edge analytical techniques.

Scientists from Japan Advanced Institute of Science and Technology (JAIST) and University of Torino (UNITO) have cooperatively clarified the nanostructure of the heterogeneous Ziegler-Natta catalyst by means of combined synchrotron X-ray analytical techniques, vibrational spectrocopies, and molecular simulations.

Understanding the structure and the working principle of practical catalysts is largely beneficial for designing catalysts towards desired performances. However, this is often infeasible due to inherent complexity of such catalysts. The Ziegler-Natta catalyst is one of the most sophisticated practical catalysts for its performance in producing desired polyolefins at extremely high yield. Nonetheless, the structure of the nanosized building unit of this catalyst has not been fully understood over six decades.

The collaborative research teams of Japan and Italy quantitatively determined the structural disorder and the dimensions of the building unit based on synchrotron X-ray total scattering analysis aided with molecular simulations. Further, by combining infrared spectroscopies with state-of-the-art DFT simulations, the morphology and the surface exposure of the building unit were clarified. The current research corresponds to the first attempt of adopting synchrotron X-ray total scattering and Far IR spectroscopy for the study of the Ziegler-Natta catalyst. Such the multi-faced approach successfully shed new light on the full elucidation of the nanostructure in practical heterogeneous catalysts.

For several years, scientists at TU Dresden and Fraunhofer IWS have been developing functionalised surfaces by means of laser-based manufacturing processes. Now, they have created a periodic surface structure that is not only water and ice repellent, but also remove dirt particles solely by rolling water drops. In this context, they particularly focussed on the material aluminium. "This material is used in many industrial branches - either in the automotive sector, aircraft construction or the food industry. The use of aggressive cleaning chemicals is particularly critical in food industry, as we naturally do not want to bring these chemicals in contact with our food," emphasises Stephan Milles, PhD student at Technische Universität Dresden. In particular, the Dresden scientists studied the function of self-cleaning laser-structured aluminium. A special camera was used to analyse the self-cleaning effect of the aluminium surfaces and filmed the process at 12,500 frames per second. Thomas Kuntze, scientist in the Microtechnology Technology Field at Fraunhofer IWS, explains: "This way we can perfectly see how a water drop can remove the dirt from the aluminium surface. This method is also suitable for understanding other processes, such as laser cutting and welding or additive manufacturing".